JP2015198164A - Nonaqueous lithium power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous lithium power storage element having a high output and a high capacity per volume, and excellent cycle characteristics.SOLUTION: A nonaqueous lithium power storage element uses an active material having a BET specific surface area of 2600-4500 m/g, a meso pore amount V1 (cc/g) in a range of 0.8<V1≤2.5, calculated by BJH method and derived from pores having a diameter of 20-500 Å, a micro pore amount V2 (cc/g) in a range of 0.92<V2≤3.0, calculated by MP method and derived from pores having a diameter of less than 20 Å, an average particle size of 1-30 μm, and a sphericity of 0.80 or more.

Description

  The present invention relates to a non-aqueous lithium storage element using a non-aqueous electrolyte containing a lithium salt as an electrolyte.

In recent years, midnight power storage systems, home-use distributed power storage systems based on solar power generation technology, and power storage systems for electric vehicles have attracted attention from the viewpoint of the effective use of energy aimed at preserving the global environment and conserving resources. Yes.
The first requirement for power storage elements used in these power storage systems is high energy density. As a high energy density storage element capable of meeting such demands, development of a lithium ion battery has been vigorously advanced.
The second requirement is high output characteristics. For example, a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle) requires high output discharge characteristics in the power storage system during acceleration. ing. An electric double layer capacitor (hereinafter, also simply referred to as “capacitor”) using activated carbon as an electrode has been developed as a high-power storage element that can meet such demands.

The electric double layer capacitor has high durability (cycle characteristics and high temperature storage characteristics) and has an output characteristic of about 0.5 to 1 kW / L. These electric double layer capacitors have been considered to be optimal power storage elements in the field where the above high output is required, but the energy density is only about 1 to 5 Wh / L, and the output is sustained for practical use. Time has become a footstep.
In addition, research for higher output is also being conducted in lithium ion batteries. For example, a lithium ion battery has been developed that can obtain a high output exceeding 3 kW / L at a discharge depth (a value representing what percentage of the device discharge capacity is discharged) 50%, and its energy density is 100 Wh / It is below L, and it has the design which dared to suppress the high energy density which is the biggest characteristic of a lithium ion battery. Further, its durability (cycle characteristics, high temperature storage characteristics) is inferior to that of an electric double layer capacitor. Therefore, in order to give practical durability, the depth of discharge can be used only in a range narrower than the range of 0 to 100%. For this reason, the capacity that can be actually used is further reduced, and research for further improving the durability is being actively pursued.

As described above, there is a strong demand for practical use of a power storage device having high output, high energy density, and durability. However, lithium ion batteries and electric double layer capacitors have advantages and disadvantages. Therefore, development of lithium ion capacitors has become active as a storage element that satisfies these technical requirements.
A lithium ion capacitor is a storage element (non-aqueous lithium storage element) that uses a non-aqueous electrolyte containing a lithium salt as an electrolyte, and the positive electrode adsorbs an anion similar to that of an electric double layer capacitor at about 3 V or more at the positive electrode. A storage element that performs charge and discharge by a non-Faraday reaction by desorption and a Faraday reaction by occlusion / release of lithium ions in the negative electrode similar to a lithium ion battery.

  As described above, in the electric double layer capacitor that charges and discharges by a non-Faraday reaction in both the positive electrode and the negative electrode, the input / output characteristics are excellent (that means that a large current can be charged and discharged in a short time), while the energy density is small. . On the other hand, a secondary battery that charges and discharges by a Faraday reaction in both the positive electrode and the negative electrode is excellent in energy density but inferior in input / output characteristics. A lithium ion capacitor is a power storage element that aims to achieve both excellent input / output characteristics and high energy density by performing charge and discharge by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode.

For lithium ion capacitors, activated carbon is used as the positive electrode active material and natural graphite or artificial graphite, graphitized mesophase carbon microspheres, graphitized mesophase carbon fibers, graphite whiskers, graphitized carbon fibers, or non-graphite are used as the negative electrode active material. A power storage device using carbonized carbon has been proposed. Here, as the activated carbon, activated carbon originally proposed for electric double layer capacitors (for example, see Non-Patent Document 1 below) has been used.
However, the positive electrode of the lithium ion capacitor and the positive and negative electrodes of the electric double layer capacitor are different in that the cations in the non-aqueous electrolyte are lithium ions in the former and quaternary ammonium ions in the latter. Therefore, an attempt has been made to search for a material suitable for a lithium ion capacitor as a positive electrode active material for a lithium ion capacitor, instead of diverting activated carbon for an electric double layer capacitor.
For example, hydrogen / carbon (atomic ratio) is 0.05 to 0.5, BET specific surface area is 300 to 2000 m ² / g, mesopore volume by BJH method is 0.02 to 0.3 ml / g, all by MP method A power storage device using a hydrocarbon material having a pore structure with a pore volume of 0.3 to 1.0 ml / g as a positive electrode and a material obtained by activating an optically anisotropic carbon substance excluding graphite as a negative electrode is proposed. (See Patent Document 1 below).

Further, when the amount of mesopores derived from pores having a diameter of 20 to 500 mm is V1 (cc / g) and the amount of micropores derived from pores having a diameter of less than 20 mm is V2 (cc / g), 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0, and an activated carbon having a BET specific surface area of 1500 m ² / g or more and 3000 m ² / g or less is used as the positive electrode, and the negative electrode has a diameter of 20 mm or more and 500 mm or less. When the amount of mesopores derived from pores is Vm1 (cc / g) and the amount of micropores derived from pores having a diameter of less than 20 mm is Vm2 (cc / g), 0.01 ≦ Vm1 ≦ 0.20 and 0 A non-aqueous lithium storage element using a carbon material satisfying .01 ≦ Vm2 ≦ 0.40 has been proposed (see Patent Document 2 below).

JP 2005-93778 A International Publication No. 2009/063966 Pamphlet

Development and industrialization of electric double layer capacitors, Tsuyoshi Morimoto, “Carbon”, 2004 (No. 214), pages 202-209

  As described above, various non-aqueous lithium storage elements have been proposed, but there is still a demand for a non-aqueous lithium storage element that has a higher output, a higher capacity per volume, and good cycle characteristics. Accordingly, the problem to be solved by the present invention is to provide a non-aqueous lithium storage element having both higher output, higher capacity per volume, and good cycle characteristics.

Capacitance C ₁ per weight to be stored in the electrode active material layer of the storage element electrode is expressed by the following equation (1):
C ₁ [F / g] = (ε ₀ ε _r / δ) [F / m ² ] × S [m ² / g] (1)
{Wherein S is the specific surface area of the active material contained in the electrode active material layer, δ is the thickness of the double layer formed between the active material surface and the charge carrier, ε ₀ is the vacuum dielectric constant, and ε _r is 2 Represents the relative dielectric constant of the multilayer. }.

Activated carbon (ε ₀ ε _r / δ), for example, since in the case of the lithium ion capacitor is generally 0.06~0.08F / ^{m 2} approximately, the capacitance _{C 1} per weight, the specific surface area S is When the activated carbon is 2,500 m ² / g or more, it becomes 150 F / g or more. Thus, it is expected that the capacity per weight C ₁ increases as the specific surface area S increases.
On the other hand, the capacity C ₂ per volume of the electrode active material layer is represented by the following formula (2):
C ₂ [F / cm ³ ] = C ₁ [F / g] × σ [g / cm ³ ] (2)
{Wherein C ₁ is the capacity per weight stored in the electrode active material layer of the storage element electrode, and σ represents the bulk density of the active material layer of the electrode. }.

Therefore, by using an active material having a high specific surface area S, the capacity C ₁ per weight can be increased to improve the capacity C ₂ per volume of the electrode active material layer and / or the bulk of the active material layer of the electrode. By increasing the density σ, the capacity C ₂ per volume of the electrode active material layer can be improved. However, generally, when an active material having a high specific surface area S is used, the bulk density σ of the active material layer tends to decrease, and it is necessary to select an active material to be used in consideration of this balance.
In addition, in order to obtain good cycle characteristics, it is necessary to optimize the electrode structure formed by each of the active material, the conductive material and the binder constituting the electrode in addition to being physicochemically stable. Of particular note is that the reactant produced by the electrochemical reaction associated with the charge / discharge cycle causes clogging of the pores in the active material and the gaps between the active materials, reducing the ionic conductivity of the entire electrode, It has an adverse effect on the charge / discharge characteristics. The electrode structure for maintaining a good cycle characteristic is that the active materials are strongly bonded, the gaps between the active materials are large, and the ionic conductivity of the entire electrode can be formed uniformly within the electrodes. Is necessary to maintain the

  As a result of intensive research and repeated experiments to solve the above problems, the present inventors have used activated carbon having a pore size distribution different from the activated carbon described in Patent Documents 1 and 2, as a positive electrode active material, Found that an active material layer with a high specific surface area and a high bulk density can be produced, and in order to obtain good cycle characteristics, the shape of the active material is high in sphericity (small aspect ratio) and close to spherical Was found to be effective. And it discovered that the non-aqueous lithium-type electrical storage element using this active material layer solved the said subject, and came to complete this invention. The aspect ratio is the ratio of the major axis to the minor axis of the particle image, and can be calculated by “major axis ÷ minor axis”.

That is, the present invention is as follows.
[1] The amount of mesopores V1 (cc / g) derived from pores having a BET specific surface area of 2600 m ² / g to 4500 m ² / g and a diameter of 20 to 500 mm calculated by the BJH method is 0.8. <V1 ≦ 2.5, the amount of micropores V2 (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method is 0.92 <V2 ≦ 3.0, and the average particle size is 1 μm. An active material used for an electrode of a non-aqueous lithium-type energy storage device, having a sphericity of 0.80 or more and a sphericity of 30 μm or less.

[2] The amount of mesopores V1 (cc / g) derived from pores having a BET specific surface area of 2600 m ² / g to 4500 m ² / g and a diameter of 20 mm to 500 mm calculated by the BJH method is 0.8. <V1 ≦ 2.5, the amount of micropores V2 (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method is 0.92 <V2 ≦ 3.0, and the average particle diameter there 1μm or more, comprising a positive electrode active material is 30μm or less, the bulk density of the active material layer containing a positive electrode active material is not more than 0.40 g / cm ³ or more 0.70 g / cm ^3, and the active material layer A positive electrode for a non-aqueous lithium storage element, comprising a positive electrode active material having a roundness of 0.80 or more in a cross section obtained by cutting the positive electrode active material layer perpendicularly to the thickness direction of the electrode electrode.

  [3] In the cross-section obtained when the positive electrode active material layer is cut perpendicularly to the thickness direction of the electrode, the total cross-sectional area of the positive electrode active material having a roundness of 0.80 or more is the total positive electrode The positive electrode for a non-aqueous lithium storage element according to [2], which is 50% or more with respect to the total cross-sectional area of the active material.

  [4] An electrode body in which the positive electrode according to [2] or [3], a separator, and a negative electrode including particles of a negative electrode active material are laminated; a non-aqueous electrolyte solution containing lithium ions; and an exterior body A non-aqueous lithium-type energy storage device.

[5] The non-aqueous lithium storage element according to [4], wherein the positive electrode active material is activated carbon having a BET specific surface area of 3000 m ² / g or more and 4000 m ² / g or less.

[6] The negative electrode active material included in the negative electrode includes a composite porous material in which pitch charcoal is deposited on the surface of activated carbon, and the following i) and ii):
i) The weight ratio of the pitch charcoal to the activated carbon is 10% or more and 60% or less, and the pitch softening point of the pitch charcoal is 100 ° C. or less; and ii) the negative electrode active material is BET specific surface area of 350m ² / g~1500m ² / g, and lithium ions, have been 1100mAh / g~2000mAh / g doped per unit weight;
The non-aqueous lithium storage element according to [4] or [5], wherein

[7] The negative electrode active material includes a composite porous material in which pitch charcoal is deposited on the surface of activated carbon, and the composite porous material is derived from pores having a diameter of 20 to 500 mm calculated by the BJH method. When the amount of mesopores to be made is Vm1 (cc / g) and the amount of micropores derived from pores having a diameter of less than 20 mm calculated by the MP method is Vm2 (cc / g), the following I) to III):
I) 0.010 ≦ Vm1 ≦ 0.300 and 0.010 ≦ Vm2 ≦ 0.200;
II) 0.010 ≦ Vm1 ≦ 0.200 and 0.200 ≦ Vm2 ≦ 0.400; and III) 0.010 ≦ Vm1 ≦ 0.100 and 0.400 ≦ Vm2 ≦ 0.650;
The nonaqueous lithium storage element according to any one of [4] to [6], which satisfies at least one of the following.

  [8] The negative electrode active material has an amount of mesopores Vm1 (cc / g) derived from pores having a diameter of 20 to 500 mm calculated by the BJH method of 0.001 ≦ Vm1 <0.01, and MP [4] or [5], including a non-graphitizable carbon material having a micropore amount Vm2 (cc / g) derived from pores having a diameter of less than 20 mm calculated by the method of 0.001 ≦ Vm2 <0.01. A non-aqueous lithium-type electricity storage device described in 1.

[9] A positive electrode for a non-aqueous lithium storage element including a positive electrode active material layer containing particles of a positive electrode active material, wherein the positive electrode is used as an anode, and metallic lithium is used as a cathode and a reference electrode. When charging / discharging at a current density of 1 mA / cm ² and an anode potential of 2.2 to 4.2 V, the ratio of 2.2 to 3.2 V discharge capacity in the 2.2 to 4.2 V discharge capacity is 0.43. The average particle size of the positive electrode active material is 1 μm or more and 30 μm or less, and the bulk density of the positive electrode active material layer containing the positive electrode active material is 0.40 g / cm ³ or more and 0.70 g / cm ³ or less. And the positive electrode active material layer includes particles of a positive electrode active material having a roundness of 0.80 or more in a cross section obtained by cutting the positive electrode active material layer perpendicularly to the thickness direction of the electrode. A positive electrode for a lithium storage element.

[10] When the separator is kept at 100 ° C. for 1 hour in an unconstrained state, the thermal contraction rate of the separator is 3% or more and 10% or less in the first direction, and the first 2% or more and 10% or less in the second direction orthogonal to the direction,
The area of the positive electrode active material layer of the positive electrode or the area of the negative electrode of the negative electrode active material layer of the negative electrode and the area of the separator have a relationship of (separator area)> (electrode area). ,And,
In an arbitrary straight line parallel to the first direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap in the arbitrary straight line is A, and the electrode area and the separator overlap. When the length of the part that does not become L1 and L1 ′, L1 or L1 ′ of an arbitrary straight line in which either L1 or L1 ′ is the shortest is expressed by the following formula (3):
X1 = (L1 or L1 ′ / (A / 2)) × 100
X1 obtained by substituting
In an arbitrary straight line parallel to the second direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap on the arbitrary straight line is defined as B, and the electrode area and the separator overlap. When the length of the part that does not become L2 and L2 ′, L2 or L2 ′ of an arbitrary straight line in which either L2 or L2 ′ is the shortest is expressed by the following formula (4):
X2 = (L2 or L2 ′ / (A / 2)) × 100
X2 obtained by substituting for each is 0.5 or more and 8.0 or less.
The non-aqueous lithium storage element according to any one of claims 4 to 8.

  [11] The separator according to any one of [4] to [8], wherein the separator is a laminated separator in which a polyolefin porous film and an insulating porous film are laminated, and the insulating porous film is in contact with the negative electrode. Non-aqueous lithium storage element.

  [12] The thickness of the polyolefin porous film of the laminated separator is 5 μm or more and 35 μm or less, and the ratio of the thickness of the insulating porous film to the polyolefin porous film is 0.25 to 1.00. Non-aqueous lithium storage element.

  The non-aqueous lithium storage element of the present invention has a high capacity per volume, high output, and high cycle characteristics.

(A) It is a cross-sectional schematic diagram of the plane direction which shows the one aspect | mode of the electrical storage element of this invention. (B) It is a cross-sectional schematic diagram of the thickness direction which shows the one aspect | mode of the electrical storage element of this invention. It is a schematic diagram of an example of the apparatus used at a pressurization process. It is the schematic explaining the relationship between the electrode area which is either the area of the positive electrode active material layer of a positive electrode body, or the area of the negative electrode active material layer of a negative electrode body, and the area of a separator. It is the schematic explaining the concept of a margin. It is a cross-sectional schematic diagram of the separator in embodiment of this invention. It is a plane schematic diagram of the cell in a nail penetration test. It is a photograph replaced with sectional drawing obtained when a positive electrode active material layer is cut | disconnected perpendicularly to the thickness direction of an electrode.

  The non-aqueous lithium storage element of this embodiment includes a positive electrode active material layer including a positive electrode active material and a positive electrode including a positive electrode current collector, a separator, and a negative electrode including a negative electrode active material layer including a negative electrode active material and a negative electrode current collector. Are laminated, a non-aqueous electrolyte containing lithium ions, and an exterior body. Hereinafter, preferred embodiments of the non-aqueous lithium storage element of the present invention will be described.

(Positive electrode active material)
The positive electrode active material has a mesopore amount derived from pores having a diameter of 20 to 500 mm calculated by the BJH method as V1 (cc / g) and a micropore amount derived from pores having a diameter of less than 20 mm calculated by the MP method. When V2 (cc / g), activated carbon satisfying 0.8 <V1 ≦ 2.5 and 0.92 <V2 ≦ 3.0 is included.
The mesopore amount V1 is preferably a value larger than 0.8 cc / g from the viewpoint of increasing the output characteristics when the positive electrode material is incorporated in the power storage element, and from the viewpoint of suppressing a decrease in the capacity of the power storage element. , Preferably 2.5 cc / g or less. V1 is more preferably 1.00 cc / g or more and 2.0 cc / g or less, and further preferably 1.2 cc / g or more and 1.8 cc / g or less.

  On the other hand, the micropore amount V2 is preferably a value larger than 0.92 cc / g in order to increase the specific surface area of the activated carbon and increase the capacity, and the density of the activated carbon as an electrode is increased. From the viewpoint of increasing the capacity per volume, it is preferably 3.0 cc / g or less. V2 is more preferably greater than 1.0 cc / g and not greater than 2.5 cc / g, and still more preferably not less than 1.5 cc / g and not greater than 2.5 cc / g.

The above-mentioned micropore amount and mesopore amount are values obtained by the following method. That is, the sample is vacuum-dried at 500 ° C. all day and night, and the adsorption and desorption isotherm is measured using nitrogen as an adsorbate. Using the isotherm on the desorption side at this time, the micropore volume is calculated by the MP method, and the mesopore volume is calculated by the BJH method.
The MP method uses a “t-plot method” (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)), and uses a micropore volume, a micropore area, and a micropore. Is a method for obtaining the distribution of M.M. It is a method devised by Mikhal, Brunauer, Bodor (RS Mikhal, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)). The BJH method is a calculation method generally used for analysis of mesopores and proposed by Barrett, Joyner, Halenda et al. (EP Barrett, LG Joyner and P. Halenda, J. Amer.Chem.Soc., 73, 373 (1951)).

The activated carbon having the mesopore amount and the micropore amount described above has a higher BET specific surface area than the activated carbon used for conventional electric double layer capacitors or lithium ion capacitors. Specific values of the BET specific surface area are 2600 m ² / g or more and 4500 m ² / g or less, and preferably 3000 m ² / g or more and 4000 m ² / g or less. When the BET specific surface area is 2600 m ² / g or more, good energy density is easily obtained. On the other hand, when the BET specific surface area is 4500 m ² / g or less, a large amount of binder is used to maintain the strength of the electrode. Since it is not necessary to put in, the performance per electrode volume tends to be high.

The positive electrode active material of the present invention includes particles having a sphericity of 0.80 or more. Particles having a sphericity of 0.80 or more have a structure close to a sphere, have large gaps formed by the active material particles, and are uniformly distributed in the electrode. In particular, the more active material particles having a sphericity of 0.80 or more in the electrode, the better the cycle characteristics. More preferably, the sphericity is 0.85 or more, and most preferably the sphericity is 0.90 or more.
Here, the roundness of 0.80 or more means that the roundness of the cross-sectional area of the spherical active material obtained by an electron microscope is 0.80 or more, and the roundness is 0.80 or more. Means that the aspect ratio in the cross-sectional area of the spherical active material is 1.25 or less.
Further, in the present invention, the roundness of 100 cross-sectional areas arbitrarily selected in the cross section in the electron microscope obtained when the positive electrode active material layer constituting the positive electrode is cut perpendicularly to the thickness direction of the electrode. The total cross-sectional area of the positive electrode active material of 0.80 or more is preferably 30% or more, more preferably 50% or more, more preferably 60% or more, with respect to the entire cross-sectional area of all the positive electrode active materials in the electrode cross section. Most preferably, it is 85% or more.

In order to obtain spherical particles having a sphericity of 0.80 or more with an aspect ratio in the cross section of 1.25 or less, the shape of the raw material before carbonization has an aspect ratio in the cross sectional area of 1.25 or less, There is a method of molding to a sphericity of 0.80 or more.
The raw material used for the production conditions can be selected from various synthetic resins such as phenol resin, furan resin, and resorcinol resin polymerized by emulsion polymerization.
Since these resins can control the sphericity by an emulsion polymerization method, the aspect ratio of the cross-sectional area of activated carbon as the positive electrode active material after the carbonization of the present invention and after the activation treatment is 1.25 or less. The sphericity can be molded to 0.80 or more.
As another method, after pulverizing the raw material before carbonization such as coconut shell, it is formed into a spherical shape, and then subjected to a process after baking and carbonized, and the shape of the raw material before baking is reduced to an aspect ratio of 1.25 or less. Although the method of shape | molding beforehand is also mentioned, From the surface of manufacturing efficiency, the method of controlling the sphericity of the raw material before carbonizing by emulsion polymerization is preferable.
The above production conditions include, for example, plant-based materials such as wood, wood flour, and coconut shells; fossil-based materials such as petroleum pitch and coke; vinyl chloride resin, vinyl acetate resin, melamine resin, and urea resin. Carbonaceous materials such as various synthetic resins can also be used.

The raw material before carbonization obtained by the above production method is subsequently carbonized by heating (hereinafter sometimes referred to as “carbonization”).
The heating for carbonization is preferably performed at a carbonization temperature of about 400 to 700 ° C. for 0.5 to 10 hours. Examples of the heating method include known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method. The atmosphere at the time of heating is an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas mixed with other gases containing these inert gases as a main component.
The raw material carbonized by heating for carbonization is then subjected to activation treatment. This is because fine pores are imparted to the surface of the carbonized raw material.

Hereinafter, the conditions for the activation process will be described in detail.
As activation methods, there are a gas activation method in which firing is performed using an activation gas such as water vapor, carbon dioxide, oxygen, and an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound. For this purpose, an alkali metal activation method is preferred. In this activation method, after mixing so that the weight ratio of carbide and an alkali metal compound such as KOH and NaOH is 1: 1 or more, in the range of 600 to 900 ° C. in an inert gas atmosphere, 0.5 to Heating is performed for 5 hours, and then the alkali metal compound is removed by washing with an acid and water, followed by drying.
For the heating, it is possible to use a method similar to the heating method used for carbonization.
In addition, after pulverizing the raw material such as coconut shell into the raw material and then forming it into a spherical shape, when using the method of performing the process after baking, after performing the classification treatment, the treatment is performed by the activation method described above. Good. By performing the activation treatment after the pulverization / classification treatment, it is possible to prevent deterioration of characteristics due to the nascent interface that occurs when pulverization after activation is performed.

  When carbonaceous particles (raw material before carbonization) having a particle diameter of 1 μm to 30 μm and an aspect ratio of a cross-sectional area of 1.25 or less and a sphericity of 0.80 or more are prepared, The firing activation (carbonization and activation) can be performed without classification. On the other hand, if the carbonaceous material (carbide) in the form of a lump or crushed is pulverized and classified in advance before activation, it can be activated efficiently.

In the activation method used in the present invention, the mass ratio of carbide to alkali metal compound (= carbide: alkali metal compound) is preferably 1: 1 or more. However, the amount of mesopore increases as the amount of the alkali metal compound increases. However, since there is a tendency for the amount of pores to increase suddenly at a mass ratio of about 1: 3.5, the mass ratio is preferably more than 1: 3, and is preferably 1: 5.5 or less. It is preferable. As the mass ratio increases, the amount of pores increases as the number of alkali metal compounds increases.
In order to increase the amount of micropores and not increase the amount of mesopores, a larger amount of carbide is mixed with KOH when activated. In order to increase the amount of both pores, KOH is increased with respect to the ratio of carbide to KOH. In order to mainly increase the amount of mesopores, water vapor activation is performed after alkali activation treatment.

Under the above production conditions, activated carbon can be obtained from a raw material of spherical particles having an aspect ratio of 1.25 or less and a sphericity of 0.80 or more. The obtained activated carbon is also spherical particles having an aspect ratio of 1.25 or less and a sphericity of 0.80 or more.
And the average particle diameter of the activated carbon which is a positive electrode active material used for the non-aqueous lithium storage element of the present invention obtained under the above production conditions is 1 μm or more and 30 μm or less, preferably 2 μm or more and 20 μm or less. More preferably, it is 2 μm or more and 10 μm or less. It may be a mixture of two kinds of activated carbons having different average particle sizes. Here, the average particle diameter is 50% when the particle size distribution is measured using a particle size distribution measuring device, and when the cumulative curve is determined with the total volume being 100%, the cumulative curve is 50%. The diameter refers to the 50% diameter (Median diameter).

Regarding the particle size distribution, from the viewpoint of good cycle characteristics, when the particle size of 10% cumulative from the small particle side obtained by particle size distribution measurement is D10, the cumulative 50% is D50, and the cumulative 90% is D90, The particle size distribution parameter represented by the following formula (5) is preferably 2.5 or less, more preferably 2.0 or less, and still more preferably 1.5 or less:
Particle size distribution parameter = (D90−D10) / D50 (5)
The particle size distribution measurement uses a laser diffraction method. For the measurement, either a dry method or a wet method can be used.

In the positive electrode using activated carbon, when LiPF ₆ or LiBF ₄ is used as the electrolyte of the electrolyte, solvated lithium ions are adsorbed in the pores in the range of 2.2 to 3.2 V with respect to the potential of metallic lithium. In the range of 3.2 to 4.2 V, it is considered that anions PF ₆ ⁻ and BF ₄ ⁻ are adsorbed. The active material of the present invention having a large amount of mesopores is characterized by a large capacity due to adsorption of solvated lithium ions having a large ionic radius.
In the activated carbon of the present invention, in a single electrode cell in which metallic lithium is used as a cathode and a reference electrode, when the current density is 1 mA / cm ² and the anode potential is charged and discharged in the range of 2.2 to 4.2 V, 2.2 V The ratio of 2.2V to 3.2V discharge capacity in the discharge capacity in the range of ~ 4.2V is 0.43 or more.

(Positive electrode)
Activated carbon as the positive electrode active material described above constitutes the positive electrode under the following conditions.
The positive electrode may have a positive electrode active material layer formed on only one side of the positive electrode current collector, or may be formed on both sides. The thickness of the positive electrode active material layer is preferably, for example, 30 μm to 200 μm per side.
The material of the positive electrode current collector is not particularly limited as long as it is a conductive material that does not cause degradation such as elution into the electrolytic solution or reaction when the power storage element is formed. A suitable material is aluminum. As the shape of the positive electrode current collector, a metal foil or a structure (such as a foam) in which an electrode can be formed in a gap between metals can be used. The metal foil may be a normal metal foil having no through hole, or a metal foil having a through hole such as an expanded metal or a punching metal. Further, the thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the electrode can be sufficiently maintained, but for example, from the viewpoint of strength, conductive resistance, and capacity per volume, 1 to 100 μm is preferable.

  The binder used for the positive electrode active material layer is not particularly limited, and PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), a styrene-butadiene copolymer, or the like can be used. The binder content in the positive electrode active material layer is preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the positive electrode active material, for example. Moreover, an electroconductive filler can be added to a positive electrode active material layer as needed. The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor grown carbon fiber. As for the addition amount of an electroconductive filler, 0-30 mass parts is preferable with respect to 100 mass parts of active materials, for example.

  The positive electrode can be manufactured using a known electrode forming technique such as a lithium ion battery or an electric double layer capacitor. For example, a slurry in which a positive electrode active material, a conductive filler, and a binder are dispersed in a solvent, The positive electrode active material layer can be obtained by performing a coating process on the positive electrode current collector, a drying process for drying the solvent, and a pressurizing process for improving the bulk density of the positive electrode active material layer by pressurization.

The bulk density of the positive electrode active material layer is 0.40 g / cm ³ or more, preferably 0.45 g / cm ³ or more, 0.70 g / cm ³ or less. When the bulk density is 0.40 g / cm ³ or more, the capacity of the electrode per volume can be increased, and the storage element can be reduced in size. Further, if the bulk density is 0.70 g / cm ³ or less, it is considered that the electrolyte solution is sufficiently diffused in the voids in the positive electrode active material layer and the charge / discharge characteristics at a large current are high.
The bulk density of the positive electrode active material layer used in one embodiment of the present invention is due to the fact that it has a specific amount of micropores and mesopores, so that the bulk of a normal activated carbon active material layer produced by the same method is used. Small compared to density. In that case, in order to achieve the above-mentioned bulk density in a state of being formed as the positive electrode active material layer, for example, the surface temperature is increased while being heated by a roll set to a temperature not lower than the melting point of the binder minus 40 ° C. and lower than the melting point. A pressing method (hereinafter also referred to as “heating press”) can be used.

  Further, a molding process in which activated carbon and a binder are mixed by a dry method without using a solvent, and are pressed into a plate shape while being heated to a temperature of the melting point of the binder minus 40 ° C. or higher and lower than the melting point, and The bonding step of attaching the formed positive electrode active material layer to the positive electrode current collector with a conductive adhesive may be performed. In addition, melting | fusing point can be calculated | required in the endothermic peak position of DSC (Differential Scanning Calorimetry). For example, using a differential scanning calorimeter “DSC7” manufactured by PerkinElmer Co., Ltd., 10 mg of sample resin is set in a measurement cell, and the temperature is increased from 30 ° C. to 250 ° C. at a temperature increase rate of 10 ° C./min in a nitrogen gas atmosphere. The temperature is raised, and the endothermic peak temperature in the temperature raising process becomes the melting point.

The hot press method can be performed, for example, in the following steps. The equipment used for the heating press will be described with reference to FIG.
The unwinding roll (1) which wound up the positive electrode (6) which apply | coated the positive electrode active material layer to the positive electrode electrical power collector is unwound and installed in a roll position. As shown in FIG. 2, the positive electrode (6) is wound around a winding roll (4) through a first guide (2), a heated press roll (3), and a second guide (2) in this order.
The surface temperature of the heated press roll (3) is set to a temperature not lower than the melting point minus 40 ° C. and not higher than the melting point of the binder contained in the positive electrode active material layer. It selects from the temperature below melting | fusing point minus 20 degreeC and below melting | fusing point. For example, when PVDF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferably heated in the range of 110 to 150 ° C., more preferably in the range of 120 to 150 ° C. When a styrene-butadiene copolymer (melting point: 100 ° C.) is used as the binder, it is preferably heated in the range of 60 to 100 ° C., more preferably in the range of 70 to 100 ° C.

The pressurizing pressure at the time of heat pressing and the speed at which the pressing is performed are adjusted by the bulk density of the positive electrode to be obtained. The press pressure of the heated press roll is kept constant by adjusting the pressure of the hydraulic cylinder (5). The pressing pressure is preferably 50 kgf / cm or more and 300 kgf / cm or less. The pressing speed is preferably 15 m / min or less, more preferably 10 m / min or less, and still more preferably 5 m / min or less. A sufficient bulk density can be obtained at the above pressing speed.
In addition, when the pressing pressure is too high, the active material layer is peeled off from the current collector. Therefore, it is preferable to determine the pressing pressure by measuring the resistance of the cell, the discharge capacity retention rate, and the like.
The distance between the press rolls (distance between the rolls) can be arbitrarily selected. In the first press, pressing is performed at a distance between the rolls that is at least narrower than the electrode thickness to be pressed, but the effect of increasing the bulk density by the press is small at the distance between the rolls that is closer to the electrode thickness. In order to peel from the body, it is preferable to select the distance between rolls by measuring the resistance of the cell, the discharge capacity maintenance rate, and the like.

The positive electrode of the present invention is preferably pressed twice or more. A single press cannot increase the bulk density sufficiently, or in order to increase the bulk density, it is necessary to press at a press pressure that is too high or a distance between rolls that is too narrow, resulting in peeling and cell resistance. And the performance such as the discharge capacity maintenance rate is reduced. If the positive electrode is significantly damaged, the cell may not be produced.
For example, when the press is pressed twice or more, it is preferable that the distance between the rolls is equal to the distance between the rolls during the second press, more preferably narrower than that during the first press. Specifically, when the first roll distance is 1, the second roll distance is 0.4 to 0.6, and when the third roll is performed, the second roll distance is 1. When the press is performed with the third inter-roll distance being 0.2 to 0.4, the desired bulk density can be obtained. You may further press as needed. However, from the viewpoint of production efficiency, a press number of about 2 to 3 is preferable. Moreover, when pressing twice or more, you may perform the first press at room temperature.
Further, the pressing pressure may be the same as or higher in the second pressing than in the first pressing. A higher pressing pressure is preferable for improving the density.

  The heated press roll (3) is rotated in the direction in which the positive electrode (6) is sent from the unwinding roll (1) to the winding roll (4), and controlled to an arbitrary speed. The winding roll (4) rotates so that the tension of the electrode becomes an appropriate value and winds up the positive electrode (6). The unwinding roll (1) does not need to rotate, but is preferably a load that gives a tension that does not sag the positive electrode (6).

  In the present invention, a material other than activated carbon having the specific V1, V2 (for example, activated carbon not having the specific V1, V2 or a composite oxide of lithium and transition metal) is included in the positive electrode active material. When it contains, content of the activated carbon which has the said specific V1, V2 shall be more than 50 weight% of all the positive electrode active materials. The content of the activated carbon having the specific V1, V2 in the total positive electrode active material is more preferably 70% by weight or more, further preferably 90% by weight or more, and most preferably 100% by weight.

(Negative electrode active material)
<Negative electrode active material>
The negative electrode combined with the positive electrode can exhibit a sufficient effect even when the active material uses crystalline graphite or a non-graphitizable carbon material, but the negative electrode active satisfying the following 1) and 2) simultaneously. A negative electrode using a substance is preferable.
Tripolar cell in which LiPF ₆ is dissolved in 1 mol / L in a solvent in which the working electrode is a negative electrode, the counter electrode is lithium, the reference electrode is lithium, and the electrolytic solution is a mixture of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 1: 4. In this case, lithium is charged with a constant current under the condition that the current value is 100 mA / g per negative electrode active material and the cell temperature is 45 ° C., and is switched to a constant voltage when the negative electrode potential reaches 1 mV. The amount of charge after a total of 40 hours by constant current and constant voltage charge is the initial lithium charge amount, and after the above charge, the current value is 50 mA / g per negative electrode active material, and the cell temperature is When the discharge amount when lithium was discharged at a constant current until the negative electrode potential became 2.5 V under the condition of 45 ° C., the initial lithium discharge amount,
In the initial lithium charge / discharge characteristics,
1) The charge amount is 1100 mAh / g or more and 2000 mAh / g or less; and 2) The discharge amount is 100 mAh / g or more at a negative electrode potential of 0 to 0.5 V.

  As for 1), if the charge amount is 1100 mAh / g or more, the amount of the negative electrode active material in the negative electrode can be reduced, the negative electrode active material layer can be made thin, and the energy storage device can express a high energy density. If the charge amount is 2000 mAh / g or less, the amount of pores in the negative electrode active material does not increase excessively, and the bulk density of the negative electrode active material layer can be increased. As described above, the charge amount is preferably 1200 mAh / g or more and 1700 mAh / g or less, and more preferably 1300 mAh / g or more and 1600 mAh / g or less.

  Regarding 2), when the negative electrode potential is between 0 and 0.5 V, if the discharge amount is 100 mAh / g or more, the negative electrode potential is operated at a low potential in the charge / discharge process when the battery is used. And high durability can be exhibited. From the above, the discharge amount between the negative electrode potential of 0 to 0.5 V is preferably 120 mAh / g or more, more preferably 140 mAh / g or more.

  Specifically, the structure of the negative electrode active material constituting the negative electrode preferably includes a composite porous material in which pitch charcoal is deposited on the surface of activated carbon.

The negative electrode active material containing the composite porous material of the present invention is characterized by satisfying the following i) and ii) simultaneously:
i) The weight ratio of the pitch charcoal to the activated carbon is 10% or more and 60% or less, and the pitch softening point of the pitch charcoal is 100 ° C. or less; and ii) the negative electrode active material is BET specific surface area of 350m ² / g~1500m ² / g, and lithium ions, have been 1100mAh / g~2000mAh / g doped per unit weight.

Hereinafter, i) will be described.
If the weight ratio of the pitch charcoal to the activated carbon is 10% or more, the micropores that the activated charcoal has can be appropriately filled with the pitch charcoal, and durability is improved by improving the charge / discharge efficiency of lithium ions. Will not be damaged. Further, if the weight ratio of the carbonaceous material is 60% or less, the specific surface area can be increased by appropriately holding the pores of the composite porous material, and the pre-doping amount of lithium ions can be increased. High power density and high durability can be maintained even if the film is thinned. From the above, this weight ratio is preferably 15% or more and 55% or less, more preferably 18% or more and 50% or less, and further preferably 20% or more and 47% or less.

  Furthermore, if the softening point of the pitch coal raw material is 100 ° C. or less, it is not bound by theory, but the micropores possessed by the activated carbon can be appropriately filled with the pitch coal. In addition, since the charge / discharge efficiency of the initial lithium charge / discharge characteristics is improved, the discharge amount can be increased when the negative electrode potential is between 0 and 0.5 V, and the durability can be improved. From the above, the pitch softening point is preferably 90 ° C. or lower, and more preferably 50 ° C. or lower. The pitch softening point is preferably about 35 ° C. or higher.

Hereinafter, ii) will be described.
When the specific surface area of the negative electrode active material in the BET method is 350 m ² / g or more, the pores of the negative electrode active material can be appropriately retained, and the doping amount of lithium ions can be increased. Can be realized. On the other hand, when the specific surface area is 1500 m ² / g or less, the micropores of the activated carbon can be appropriately filled, and the charge / discharge efficiency of the initial lithium charge / discharge characteristics is improved, so that the negative electrode potential is 0 to 0.5V. It is possible to increase the amount of discharge when it is between, and durability can be improved. From the above, the specific surface area is preferably 350m ² / g~1100m ² / g, more preferably 370m ² / g~600m ² / g.

  Further, the negative electrode active material is doped with lithium ions (also referred to as pre-doping). The pre-doping amount is 1100 mAh / g or more and 2000 mAh / g or less per unit weight of the composite porous material. This pre-doping amount is preferably 1200 mAh / g or more and 1700 mAh / g or less, and more preferably 1300 mAh / g or more and 1600 mAh / g or less. By pre-doping with lithium ions, the negative electrode potential is lowered, the cell voltage is increased when combined with the positive electrode, and the utilization capacity of the positive electrode is increased, resulting in higher capacity and higher energy density.

  In the negative electrode for a non-aqueous lithium storage element according to the present invention, if the pre-doping amount is 1100 mAh / g or more, lithium ions are sufficiently pre-doped at irreversible sites that cannot be desorbed once lithium ions in the negative electrode material are inserted. In addition, since the amount of the negative electrode active material relative to the desired amount of lithium can be reduced, the negative electrode film thickness can be reduced, and high durability, output characteristics, and high energy density can be obtained. The higher the pre-doping amount, the lower the negative electrode potential and the more the durability and energy density. However, when the pre-doping amount is 2000 mAh / g or less, there is little risk of side effects such as precipitation of lithium metal.

The negative electrode active material may be used alone or in combination of two or more.
The composite porous material can be obtained, for example, by heat treatment in a state where activated carbon and pitch coexist.

The activated carbon used as a raw material for the composite porous material is not particularly limited as long as the raw material before activated carbon is used as long as the obtained composite porous material exhibits desired characteristics. Commercial products obtained from various raw materials such as molecular systems can be used. It is preferable to use activated carbon powder having an average particle size of 1 μm to 15 μm, more preferably 2 μm to 10 μm.
The average particle size in the present invention is the particle size at which the cumulative curve becomes 50% when the cumulative curve is determined with the total volume being 100% when the particle size distribution is measured using a particle size distribution measuring device. % Diameter, and refers to the 50% diameter (Median diameter). This average particle diameter can be measured with a commercially available laser diffraction particle size distribution analyzer.

  On the other hand, the pitch used for the raw material of the composite porous material is roughly divided into petroleum pitch and coal pitch. Examples of petroleum pitches include crude oil distillation residue, fluid catalytic cracking residue (such as decant oil), bottom oil from thermal crackers, and ethylene tar obtained during naphtha cracking.

  The composite porous material is obtained by depositing pitch charcoal on the activated carbon by thermally reacting the volatile component or pyrolysis component of the pitch on the surface of the activated carbon. In this case, at a temperature of about 200 to 500 ° C., the deposition of pitch volatile components or pyrolysis components into the activated carbon pores proceeds, and at 400 ° C. or higher, the reaction in which the deposited components become pitch charcoal proceeds. . The peak temperature during the heat treatment is appropriately determined depending on the characteristics of the composite porous material to be obtained, the thermal reaction pattern, the thermal reaction atmosphere, etc., but is preferably 400 ° C. or higher, more preferably 450 ° C. to 1000 ° C. ° C, more preferably about 500 to 800 ° C. Moreover, the time which maintains the peak temperature at the time of heat processing should just be 30 minutes-10 hours, Preferably they are 1 hour-7 hours, More preferably, they are 2 hours-5 hours. When heat treatment is performed at a peak temperature of about 500 to 800 ° C. for 2 to 5 hours, the pitch charcoal deposited on the activated carbon surface is considered to be a polycyclic aromatic hydrocarbon.

  Examples of the method for producing the composite porous material include a method in which activated carbon is heat-treated in an inert atmosphere containing hydrocarbon gas volatilized from pitch, and pitch charcoal is deposited in the gas phase. Moreover, the method of heat-mixing activated carbon and pitch previously, or the method of heat-processing after apply | coating and drying the pitch melt | dissolved in the solvent on activated carbon can also be utilized.

The composite porous material is obtained by depositing pitch charcoal on the surface of activated carbon, but the pore distribution after the pitch is deposited inside the pores of the activated carbon is important. Can be defined by quantity. That is, the composite porous material has a mesopore amount derived from pores having a diameter of 20 to 500 mm calculated by the BJH method as Vm1 (cc / g), and a micropore derived from pores having a diameter of less than 20 mm calculated by the MP method. When the pore volume is Vm2 (cc / g), the following I) to III):
I) 0.010 ≦ Vm1 ≦ 0.300 and 0.010 ≦ Vm2 ≦ 0.200;
II) 0.010 ≦ Vm1 ≦ 0.200 and 0.200 ≦ Vm2 ≦ 0.400; and III) 0.010 ≦ Vm1 ≦ 0.100 and 0.400 ≦ Vm2 ≦ 0.650;
It is preferable to satisfy at least one of the following.

If the mesopore amount Vm1 is less than or equal to the upper limit value (Vm1 ≦ 0.300), the specific surface area of the composite porous material can be increased, the pre-doping amount of lithium ions can be increased, and the bulk density of the negative electrode As a result, the negative electrode can be thinned. Moreover, if the micropore amount Vm2 is not more than the upper limit value (Vm1 ≦ 0.650), high charge / discharge efficiency with respect to lithium ions can be maintained. On the other hand, if the mesopore volume Vm1 and the micropore volume Vm2 are not less than the lower limit values (0.010 ≦ Vm1, 0.010 ≦ Vm2), high output characteristics can be obtained.
The composite porous material preferably satisfies the above I) or II) among the above I) to III). In the above I), the mesopore volume Vm1 is preferably 0.050 ≦ Vm1 ≦ 0.300.

In the present invention, the micropore volume and mesopore volume are values determined by the following method. That is, the sample is vacuum-dried at 500 ° C. all day and night, and the adsorption and desorption isotherm is measured using nitrogen as an adsorbate. Using the isotherm on the desorption side at this time, the micropore volume was calculated by the MP method, and the mesopore volume was calculated by the BJH method. The MP method and BJH method are as described in the section of the positive electrode active material.
In the present invention, as described above, the amount of mesopores and the amount of micropores after depositing pitch charcoal on the surface of activated carbon is important, but composite porous materials having a pore distribution range defined in the present invention are used. In order to obtain, the pore distribution of the activated carbon used as a raw material is important.

The activated carbon has a mesopore amount derived from pores having a diameter of 20 to 500 mm calculated by the BJH method as V1 (cc / g) and a micropore amount derived from pores having a diameter of less than 20 mm calculated by the MP method. When V2 (cc / g), it is preferable that 0.050 ≦ V1 ≦ 0.500, 0.005 ≦ V2 ≦ 1.000, and 0.2 ≦ V1 / V2 ≦ 20.0.
The amount of mesopores is more preferably 0.050 ≦ V1 ≦ 0.350, and further preferably 0.100 ≦ V1 ≦ 0.300. The amount of micropores is more preferably 0.005 ≦ V2 ≦ 0.850, and further preferably 0.100 ≦ V2 ≦ 0.800. The ratio of mesopore amount / micropore amount is more preferably 0.22 ≦ V1 / V2 ≦ 10.0, and further preferably 0.25 ≦ V1 / V2 ≦ 10.0. When the upper limit is exceeded, that is, when the mesopore volume V1 of the activated carbon is greater than 0.5 and when the micropore volume V2 is greater than 1.0, it is often necessary to obtain the pore structure of the composite porous material of the present invention. Therefore, it is difficult to control the pore structure.

  In addition, unlike the general surface coating, the process for producing the composite porous material described above is less likely to occur after the pitch charcoal is deposited on the surface of the activated carbon, and the average particle diameter before and after the deposition is Characterized by almost no change. In the present invention, the amount of micropores and the amount of mesopores are reduced after deposition, as is clear from the characteristics of the above-mentioned process for producing the composite porous material and the examples described later. It can be presumed that most of the volatile component or pyrolysis component of the pitch is deposited in the pores of the activated carbon, and the reaction in which the deposited component becomes pitch charcoal has progressed.

  As described above, the average particle size of the composite porous material in the present invention is almost the same as that of the activated carbon before deposition, but is preferably 1 μm or more and 10 μm or less. About a lower limit, More preferably, it is 2 micrometers or more, More preferably, it is 2.5 micrometers or more. About an upper limit, More preferably, it is 6 micrometers or less, More preferably, it is 4 micrometers or less. If the average particle diameter is 2 μm or more and 10 μm or less, sufficient durability is maintained. The measuring method of the average particle diameter of the composite porous material said here is the same method as the activated carbon used for the above-mentioned raw material.

  In the above composite porous material, the average pore diameter is preferably 28 mm or more, more preferably 30 mm or more from the viewpoint of achieving high output characteristics. On the other hand, from the viewpoint of achieving a high energy density, it is preferably 65 mm or less, and more preferably 60 kg or less. In this specification, the average pore diameter is obtained by dividing the total pore volume per weight obtained by measuring each equilibrium adsorption amount of nitrogen gas at each relative pressure at the liquid nitrogen temperature by the BET specific surface area. Means something.

  In the above composite porous material, the atomic ratio of hydrogen atoms / carbon atoms (hereinafter also referred to as H / C) is preferably 0.05 or more and 0.35 or less, and 0.05 or more and 0.15. The following is more preferable. When H / C exceeds the upper limit, the carbonaceous material polycyclic aromatic conjugated structure deposited on the activated carbon surface is not sufficiently developed, so the capacity (energy density) and charge / discharge efficiency are low. Become. On the other hand, when H / C is lower than the lower limit, carbonization may proceed excessively and a sufficient energy density may not be obtained. H / C is measured by an elemental analyzer.

The composite porous material has an amorphous structure derived from the activated carbon as a raw material, but at the same time has a crystal structure mainly derived from the deposited carbonaceous material. According to the X-ray wide-angle diffraction method, the composite porous material has a (002) plane spacing d ₀₀₂ of 3.60 to 4.00 and a c-axis direction crystal obtained from the half width of this peak. preferably has child size Lc is less 20.0Å than 8.0 Å, d ₀₀₂ is less 3.75Å than 3.60A, the crystallite size Lc in the c-axis direction obtained from the half-value width of this peak What is 11.0 to 16.0 is more preferable.

<Other components of negative electrode active material layer>
In addition to the negative electrode active material, a conductive filler and a binder can be added to the negative electrode active material layer as necessary. The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor grown carbon fiber. For example, the addition amount of the conductive filler is preferably 0 to 30% by mass with respect to the negative electrode active material. The binder is not particularly limited, and PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), styrene-butadiene copolymer, and the like can be used. The amount of the binder added is preferably, for example, in the range of 3 to 20% by mass with respect to the negative electrode active material.

<Molding of negative electrode>
A negative electrode for a non-aqueous lithium-type storage element can be manufactured by an electrode molding method such as a known lithium ion battery or an electric double layer capacitor. For example, a negative electrode active material, a conductive filler, and a binder are used as a solvent. It is obtained by dispersing, forming a slurry, applying the active material layer on the current collector, drying, and pressing as necessary. In addition, it is possible to dry-mix without using a solvent and press-mold the active material, and then affix it to the current collector using a conductive adhesive or the like.

The negative electrode for a non-aqueous lithium storage element may have a negative electrode active material layer formed on only one side of the current collector or may be formed on both sides. The thickness of the negative electrode active material layer is 15 μm or more and 45 μm or less per side, preferably 20 μm or more and 40 μm or less. When the thickness is 15 μm or more, sufficient charge / discharge capacity can be exhibited. On the other hand, if this thickness is 45 μm or less, the energy density can be increased by reducing the cell volume.
When the current collector has holes, the thickness of the negative electrode active material layer refers to the average value of the thickness per side of the portion of the current collector that does not have holes. In this case, examples of the hole include a punching metal through-hole portion and an expanded metal opening portion.

The bulk density of the negative electrode active material layer is preferably 0.60 g / cm ³ or more and 1.2 g / cm ³ or less, more preferably 0.70 g / cm ³ or more and 1.0 g / cm ³ or less. When the bulk density is 0.60 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the active materials can be expressed. Moreover, if it is 1.2 g / cm < ³ > or less, the hole which ion can fully spread | diffuse in an active material layer is securable.

  The material of the negative electrode current collector is not particularly limited as long as it does not cause degradation such as elution and reaction when the storage element is formed, and examples thereof include copper, iron, and stainless steel. In the negative electrode for a non-aqueous lithium storage element of the present invention, copper is preferably used as the negative electrode current collector. As the shape of the negative electrode current collector, a metal foil or a structure in which an electrode can be formed in a gap between metals can be used, and the metal foil may be a normal metal foil having no through hole, expanded metal, punching metal Alternatively, a metal foil having a through hole such as an etching foil may be used. The thickness of the negative electrode current collector is not particularly limited as long as the shape or strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

<Pre-doping of lithium ions into the negative electrode active material>
A known method can be used as a method of pre-doping lithium ions into the negative electrode for a non-aqueous lithium storage element. For example, after forming a negative electrode active material into an electrode, using the negative electrode as a working electrode and metallic lithium as a counter electrode, an electrochemical cell combining non-aqueous electrolyte is prepared, and lithium ions are electrochemically pre-doped. A method is mentioned. It is also possible to pre-dope lithium ions into the negative electrode by pressing a metal lithium foil on the negative electrode and placing it in a non-aqueous electrolyte.

<Both energy density, output characteristics and durability>
From the viewpoint of providing a negative electrode that is excellent in energy density, output characteristics, and durability, a negative electrode active material obtained by depositing pitch charcoal on the surface of activated carbon includes a composite porous material. i) and ii):
i) The weight ratio of the pitch charcoal to the activated carbon is 10% or more and 60% or less, and the pitch softening point of the pitch charcoal is 100 ° C. or less; and ii) the negative electrode active material is BET specific surface area of 350m ² / g~1500m ² / g, and a lithium ion, is 1100mAh / g~2000mAh / g doped per unit weight;
It is preferable to satisfy.
More specifically, in order to improve energy density [capacitance of storage element (mAh) / negative electrode volume (cm ³ )], the thickness of the negative electrode active material layer is adjusted to 15 μm or more and 45 μm or less, and pitch charcoal / It is preferable to adjust the activated carbon (weight ratio) and the pitch softening point within a range in which the durability of the negative electrode is not impaired and the pre-doping amount of lithium ions can be increased.

Hereinafter, a separator that can bring out the capability of the nonaqueous lithium electricity storage device of the present invention will be described.
In the present invention, it is possible to use two types of separators, a single membrane separator and an inorganic separator in which an insulating porous membrane is applied to the single membrane separator.
<Single membrane separator>
The separator used in the capacitor of the present invention insulates the positive electrode body and the negative electrode body from being in direct electrical contact with each other, and holds the electrolytic solution in the internal gap to provide a lithium ion conduction path between the electrodes. Play a role to form. In this embodiment, the separator is made of a polyolefin resin containing polyethylene, and when the separator is kept at 100 ° C. for 1 hour in an unconstrained state, the thermal shrinkage rate of the separator is 3% in the first direction. It is 10% or less and 2% or more and 10% or less in the second direction orthogonal to the first direction. The thermal contraction rate of the separator is more preferably 4% or more and 9% or less in the first direction, 3% or more and 9% or less in the second direction, and further preferably 5% in the first direction. It is 8% or less and 3.5% or more and 5% or less in the second direction.

  The first direction is the MD direction (the advancing direction when the sheet-formed separator is wound on a roll, also referred to as “longitudinal direction”), and the second direction is the TD direction (perpendicular to the MD direction). Direction, also referred to as “width direction” or “short direction”), which is a preferred embodiment because the manufacture of the separator is facilitated (hereinafter, the first direction is MD, and the second direction is May be written as TD). In this specification, the “unconstrained state” means a state in which the object is not fixed, and means, for example, that a sheet-like separator is put in an oven as it is. This heat shrinkage rate is measured according to the method described in the following examples.

Further, the area of the positive electrode active material layer of the positive electrode body of the present invention or the negative electrode area of the negative electrode active material layer of the negative electrode body and the area of the separator is (separator area)> ( In an arbitrary straight line that is parallel to the first direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap in the arbitrary straight line is A, _'when a, L _{1, L 1'} the length of the portion in which the electrode area and the separator do not overlap L _1, L 1 and either shortest such optional straight line L ₁ or L _{1 'of} the Following formula (3):
X ¹ = (L ₁ or L ₁ ′ / (A / 2)) × 100
X ¹ obtained by substituting
In an arbitrary straight line parallel to the second direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap on the arbitrary straight line is defined as B, and the electrode area and the separator overlap. 'when _a, L 2, _{L 2'} the length of not is not part _L 2, _{L 2} or is shortest such optional straight _{L 2} or _{L 2} 'of the following formula (4):
X ² = (L ₂ or L ₂ ′ / (A / 2)) × 100
X ² obtained by substituting for is 0.5 or more and 8.0 or less.

The Figure 3, A, L1, L1 'will be described for obtaining the ^{X 1.} 1 is a separator, 2 is the electrode of the positive electrode active material layer of the positive electrode body or the negative electrode area of the negative electrode active material layer of the negative electrode body, whichever is larger, 3 is the electrode of 2 A current collector (portion where the active material layer is not applied) is shown. The same is true for X ^2.
X ¹ and X ² are preferably 2.0 or more and 6.0 or less, and more preferably 3.0 or more and 5.0 or less.

The concept of “margin” in the present invention will be described with reference to FIG.
(1) Points of interest The margin was defined by the ratio of the width (L ₁ , L ₂ , L ₃ , L ₄ ) of the separator protruding from the electrode and the electrode width (A ₁ , A ₂ ).
The margin part (L ₁ ) with the shortest width shrinks to the inside of the electrode by heating the fastest and causes a short circuit. (L ₁ <L ₃ <L ₂ <L ₄ ). Accordingly, the margin portion (L ₁ ) having the shortest width is determined as a specific method corresponding to various shapes.
(2) Identification method First, the direction of the separator is identified. The separator has an MD direction and a TD direction in production, and the flowed product is also decomposed and heated, and the direction can be specified from the heat-shrinkable state. Therefore, the MD direction and the TD direction are specified. Here, MD direction = first direction and TD direction = second direction.
A margin was then defined. Assuming an arbitrary line parallel to the above specified direction, the electrode width (A ₁ , A ₂ ) and the protruding width of the separator (L ₁ , L ₂ , L ₃ , L ₄ ) are specified, and the protruding of the separator The margin was defined using L ₁ having the shortest width.
Margin _{= [L 1 / (A 1} /2)] × 100 (%)
_{"A 1} and _L 1, _{L 3"} electrode width _{(A 1/2)} by a reference to equalize the rate of thermal contraction of _{"A 2} and _L 2, _{L 4".}

  When a sealed electricity storage element using a laminate film exterior body is exposed to an abnormally high temperature state that greatly exceeds the boiling point of the electrolyte solution for a long time, the electrolyte solution is vaporized and the exterior body is opened by pressure. Such a separator prevents the capacitor from bursting and firing, because the electrolyte in the capacitor evaporates due to the continuation of abnormally high temperature, and the capacitor can be short-circuited before the exterior body is opened by the pressure. From the viewpoint of improving the ratio. Here, “rupture” refers to a state in which the electrode laminate is broken and scattered with the electrolyte when the outer package is opened.

  In the separator of a lithium ion battery, it is necessary to shut down at an abnormally high temperature, but it is necessary to avoid as much as possible that the positive electrode body and the negative electrode body are short-circuited due to a further high temperature. . Therefore, a separator that has a low heat shrinkage rate and is difficult to melt down has been used. On the other hand, in the separator of a lithium ion capacitor, it has been considered that there is no need to shut down at an abnormally high temperature. Therefore, a paper separator that does not shut down and does not melt down even at a high temperature has been used. However, the present inventor also has a risk of rupture / ignition when a high capacity / high output is promoted even in a lithium ion capacitor. I found it effective. That is, a separator made of a polyolefin resin containing polyethylene having a heat shrinkage rate as described above is melted down in a short time at an abnormally high temperature, and when the exterior body is opened due to the continuation of the abnormally high temperature state, It has been found preferable because the capacitor can be safely short-circuited without ignition and the safety can be improved.

From the above, if the thermal contraction rate of the separator of the present invention is 3% or more in the first direction and 2% or more in the second direction, the separator can be melted down at an abnormally high temperature in a short period of time, resulting in rupture or ignition. Capacitor can be safely short-circuited without the need to improve safety, and if the first direction is 10% or less and the second direction is 10% or less, the capacitor function is maintained without being short-circuited in the normal operating temperature range. can do.
If X ¹ and X ² are 0.5% or more, the capacitor function can be maintained without being short-circuited in the normal operating temperature range, and if it is 8.0% or less, it is short at an abnormally high temperature. It can be melted down in time, and the capacitor can be safely short-circuited without rupture or ignition, improving safety.

In the present embodiment, the separator is preferably a microporous membrane, and the puncture strength (absolute strength) of the microporous membrane is preferably 200 g or more, and more preferably 300 g or more. When the piercing strength is 200 g or more, when a microporous film is used as a capacitor separator, pinholes and cracks are also generated when sharp portions such as electrode materials provided in the capacitor pierce the microporous film. It is preferable from the viewpoint that generation can be reduced. Although there is no restriction | limiting in particular as an upper limit of puncture strength, It is preferable that it is 1000 g or less. The puncture strength is measured according to the method described in the examples below.
The porosity of the microporous membrane of this embodiment is preferably 30% to 70%, more preferably 55 to 70%. Setting the porosity to 30% or more is preferable from the viewpoint of following the rapid movement of lithium ions at a high rate when a microporous film is used as a capacitor separator. On the other hand, setting the porosity to 70% or less is preferable from the viewpoint of improving the film strength, and also preferable from the viewpoint of suppressing self-discharge when the microporous film is used as a capacitor separator. The porosity is measured according to the method described in the following examples.

Further, the AC resistance of the microporous membrane of this embodiment, the viewpoint preferably 0.9Ω · cm ² or less from the output when used as a separator for capacitors, and more preferably 0.6 ohm · cm ² or less, 0.3 [Omega -More preferably cm ² or less. The AC resistance of the microporous membrane is measured according to the method described in the examples below.

Examples of means for forming a microporous membrane having various properties as described above include, for example, the concentration of polyolefin during extrusion, the blending ratio of various polyolefins such as polyethylene and polypropylene in the polyolefin, the molecular weight of polyolefin, the draw ratio, and after extraction. And a method of optimizing the stretching and relaxation operations.
Moreover, the thermal contraction rate in the MD direction and the TD direction of the separator can be adjusted by optimizing the stretching temperature and the magnification at the time of heat setting.
Moreover, the aspect of the microporous membrane may be an aspect of a single layer or an aspect of a laminate.

  Next, the manufacturing method of the microporous film of this embodiment will be exemplarily described. However, if the obtained microporous membrane is the above-mentioned microporous membrane, the production method of the present embodiment includes a polymer type, a solvent type, an extrusion method, a stretching method, an extraction method, an opening method, a heat setting / heat treatment. The method is not limited at all.

  The manufacturing method of the microporous membrane of this embodiment includes a step of melt-kneading and molding a polymer and a plasticizer, or a polymer, a plasticizer and a filler, a stretching step, a plasticizer (and a filler if necessary) ) It is preferable from the viewpoint of appropriately controlling the balance between physical properties of permeability and membrane strength to include an extraction step and a heat setting step.

More specifically, for example, the following (1) to (4):
(1) a kneading step in which a polyolefin, a plasticizer, and a filler as necessary are kneaded to form a kneaded product;
(2) A sheet forming step of extruding the kneaded material after the kneading step, forming it into a single-layered or laminated sheet and cooling and solidifying it;
(3) After the sheet forming step, a plasticizer and / or filler is extracted as necessary, and the sheet (sheet-like formed body) is further stretched in a uniaxial direction or more;
(4) A post-processing step of extracting a plasticizer and / or filler as necessary after the stretching step and further performing a heat treatment;
A method for producing a microporous membrane comprising the following steps can be used:

The polyolefin used in the kneading step (1) includes polyethylene as an essential component. The polyolefin may be composed of one kind of polyethylene, or may be a polyolefin composition containing plural kinds of polyolefins.
Examples of the polyolefin include polyethylene, polypropylene, and poly-4-methyl-1-pentene, and a mixture of two or more of these may be used. Hereinafter, polyethylene may be abbreviated as “PE” and polypropylene may be abbreviated as “PP”.

  The viscosity average molecular weight (Mv) of polyolefin is preferably 50,000 to 3,000,000, more preferably 150,000 to 2,000,000. When the viscosity average molecular weight is 50,000 or more, a high-strength microporous membrane tends to be obtained, and when it is 3 million or less, the effect of facilitating the extrusion process tends to be obtained. A viscosity average molecular weight is measured based on the method as described in the following Example.

The melting point of the polyolefin is preferably 100 to 165 ° C, more preferably 110 to 140 ° C. When the melting point is 100 ° C. or higher, the function in a high temperature environment tends to be stable, and when the melting point is 165 ° C. or lower, a meltdown occurs at a high temperature or a fuse effect tends to be obtained. The melting point means the temperature of the melting peak in differential scanning calorimetry (DSC) measurement. Further, the melting point of polyolefin when polyolefin is used as a mixture of plural kinds means the temperature of the peak having the largest melting peak area in DSC measurement of the mixture.
As the polyolefin, it is preferable to use high-density polyethylene from the viewpoint that heat fixation can be performed at a higher temperature while suppressing clogging of the pores.

The proportion of such high density polyethylene in the polyolefin is preferably 5% by mass or more, and more preferably 10% by mass or more. When the ratio is 5% by mass or more, heat fixation can be performed at a higher temperature while further suppressing the blockage of the holes. On the other hand, the proportion of the high density polyethylene in the polyolefin is preferably 99% by mass or less, and more preferably 95% by mass or less. When the ratio is 50% by mass or less, the microporous membrane can have not only the effect of high density polyethylene but also the effect of other polyolefins in a well-balanced manner.
Moreover, as a polyolefin, a viscosity average molecular weight (Mv) is 100,000-300,000 from a viewpoint of improving the shutdown characteristic at the time of using a microporous film as a capacitor separator, or improving the safety | security of a nail penetration test. It is preferable to use polyethylene.

The ratio of such 100,000 to 300,000 polyethylene in the polyolefin is preferably 30% by mass or more, and more preferably 45% by mass or more. When the ratio is 30% by mass or more, the shutdown characteristics when the microporous film is used as a capacitor separator can be improved, or the safety of the nail penetration test can be improved. On the other hand, the ratio of 100,000 to 300,000 polyethylene in the polyolefin is preferably 100% by mass or less, and more preferably 95% by mass or less.
Polypropylene may be added and used as the polyolefin from the viewpoint of controlling the meltdown temperature.

  The proportion of such polypropylene in the polyolefin is preferably 5% by mass or more, more preferably 8% by mass or more. It is preferable that the ratio is 5% by mass or more from the viewpoint of improving the film resistance at high temperatures. On the other hand, the proportion of polypropylene in the polyolefin is preferably 20% by mass or less, and more preferably 18% by mass or less. It is preferable that the ratio is 20% by mass or less from the viewpoint of realizing a microporous membrane that has not only the effect of polypropylene but also the effect of other polyolefins in a well-balanced manner.

  The plasticizer used in the kneading step (1) may be those conventionally used for polyolefin microporous membranes, and may be abbreviated as, for example, dioctyl phthalate (hereinafter referred to as “DOP”). ), Phthalic acid esters such as diheptyl phthalate and dibutyl phthalate; organic acid esters other than phthalic acid esters such as adipic acid ester and glyceric acid ester; phosphoric acid esters such as trioctyl phosphate; liquid paraffin; solid wax; Mineral oil is mentioned. These are used alone or in combination of two or more. Among these, phthalate ester is particularly preferable in consideration of compatibility with polyethylene.

In the kneading step (1), a polyolefin and a plasticizer may be kneaded to form a kneaded product, or a polyolefin, a plasticizer, and a filler may be kneaded to form a kneaded product. As the filler used in the latter case, at least one of organic fine particles and inorganic fine particles can be used.
Examples of the organic fine particles include modified polystyrene fine particles and modified acrylic resin particles.
Examples of inorganic fine particles include oxide ceramics such as alumina, silica (silicon oxide), titania, zirconia, magnesia, ceria, yttria, zinc oxide and iron oxide; nitrides such as silicon nitride, titanium nitride and boron nitride Ceramics: silicon carbide, calcium carbonate, aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, asbestos, zeolite, Ceramics such as calcium silicate, magnesium silicate, diatomaceous earth, and silica sand; glass fiber.

The blend ratio of the polyolefin, the plasticizer, and the filler used as necessary in the kneading step (1) is not particularly limited. The proportion of the polyolefin kneaded product is preferably 25 to 50% by mass from the viewpoint of the strength and film-forming property of the resulting microporous membrane. The proportion of the plasticizer in the kneaded product is preferably 30 to 60% by mass from the viewpoint of obtaining a viscosity suitable for extrusion. The proportion of the filler in the kneaded product is preferably 10% by mass or more from the viewpoint of improving the uniformity of the pore diameter of the obtained microporous membrane, and preferably 40% by mass or less from the viewpoint of film forming properties.
In addition, the kneaded material may be further phenolic, phosphorus-based, sulfur-based, such as pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], if necessary. Antioxidants such as calcium soaps, metal soaps such as calcium stearate and zinc stearate; ultraviolet absorbers; light stabilizers; antistatic agents; antifogging agents; and various additives such as color pigments may be mixed.

There is no restriction | limiting in particular in the kneading | mixing method in the kneading | mixing process of (1), The method used conventionally may be used. For example, the kneading order is a general mixing of a Henschel mixer, a V-blender, a pro-shear mixer, a ribbon blender, etc., in which a polyolefin, a plasticizer, and a part of a filler used as necessary are mixed in advance. After mixing in advance using a machine, the remaining raw materials may be further kneaded, or all of the raw materials may be kneaded simultaneously.
Moreover, there is no restriction | limiting in particular also in the apparatus used for kneading | mixing, For example, it can knead | mix using melt-kneading apparatuses, such as an extruder and a kneader.

  The sheet forming step (2) is, for example, a step of extruding the kneaded material into a sheet shape via a T die or the like, and bringing the extrudate into contact with a heat conductor to cool and solidify. As the heat conductor, metal, water, air, and the plasticizer itself can be used. Moreover, it is preferable to cool and solidify by sandwiching the extrudate between a pair of rolls from the viewpoint of increasing the film strength of the obtained sheet-like molded article and improving the surface smoothness of the sheet-like molded article.

  The stretching step (3) is a step of stretching a sheet (sheet-like molded body) obtained through the sheet forming step to obtain a stretched sheet. Sheet stretching methods in the stretching process include MD uniaxial stretching with a roll stretching machine, TD uniaxial stretching with a tenter, a combination of roll stretching machine and tenter, or sequential biaxial stretching with a combination of tenter and tenter, simultaneous biaxial tenter Or simultaneous biaxial stretching by inflation molding is mentioned. From the viewpoint of obtaining a more uniform film, the sheet stretching method is preferably simultaneous biaxial stretching. The total surface magnification at the time of stretching is preferably 8 times or more, more preferably 15 times or more, and more preferably 30 times or more from the viewpoint of film thickness uniformity and balance of tensile elongation, porosity and average pore diameter. Further preferred. When the total surface magnification is 30 times or more, a high-strength microporous film is easily obtained. The stretching temperature is preferably 121 ° C. or higher from the viewpoint of imparting high permeability and high temperature and low shrinkage, and is preferably 135 ° C. or lower from the viewpoint of film strength.

The extraction prior to the stretching in the stretching step of (3) or the heat treatment in the post-processing step of (4) is a method of immersing the sheet or the stretched sheet in the extraction solvent or showering the extraction solvent on the sheet or the stretched sheet It is done by. The extraction solvent is preferably a poor solvent for polyolefin and a good solvent for plasticizer and filler, and preferably has a boiling point lower than the melting point of polyolefin. Examples of such extraction solvents include hydrocarbons such as n-hexane and cyclohexane; halogenated hydrocarbons such as methylene chloride, 1,1,1-trichloroethane and fluorocarbon; alcohols such as ethanol and isopropanol; acetone and 2 -Ketones such as butanone; and alkaline water. An extraction solvent is used individually by 1 type or in combination of 2 or more types.
Note that the filler may be extracted in whole or in part in any of the steps, or may remain in the finally obtained microporous membrane. Moreover, there is no restriction | limiting in particular about the order of extraction, a method, and the frequency | count.

  (4) As a heat treatment method in the post-processing step, the stretched sheet obtained through the stretching step is stretched and / or relaxed at a predetermined temperature using a tenter and / or a roll stretching machine. A heat setting method may be mentioned. The relaxation operation is a reduction operation performed at a predetermined relaxation rate on the MD and / or TD of the film. The relaxation rate is a value obtained by dividing the MD dimension of the film after the relaxation operation by the MD dimension of the film before the operation, or a value obtained by dividing the TD dimension after the relaxation operation by the TD dimension of the film before the operation, or MD In the case of relaxation by both TD and TD, it is a value obtained by multiplying the relaxation rate of MD and the relaxation rate of TD. The predetermined temperature is preferably 130 ° C. or lower and more preferably 123 ° C. or lower from the viewpoint of controlling the thermal shrinkage rate or controlling the film resistance. On the other hand, from the viewpoint of stretchability, the predetermined temperature is preferably 115 ° C. or higher. Further, from the viewpoint of heat shrinkage and permeability, in the post-processing step, the stretched sheet is preferably stretched 1.5 times or more to TD, and more preferably 1.8 times or more to TD. On the other hand, from the viewpoint of safety, it is preferable to stretch the stretched sheet to TD to 6.0 times or less, and from the viewpoint of maintaining a balance between film strength and permeability, 4.0 times or less is more preferable. The predetermined relaxation rate is preferably 0.9 times or less from the viewpoint of suppression of heat shrinkage, and is preferably 0.6 times or more from the viewpoint of preventing wrinkle generation, porosity, and permeability. The relaxation operation may be performed in both directions of MD and TD, but may be a relaxation operation of only one of MD and TD. Even if the relaxation operation is performed on only one of MD and TD, it is possible to reduce the thermal contraction rate not only in the operation direction but also in the other direction.

The viscosity average molecular weight of the obtained microporous membrane is preferably 200,000 to 1,000,000. If the viscosity average molecular weight is 200,000 or more, the strength of the film is easily maintained, and if it is 1,000,000 or less, the moldability is excellent.
The film thickness of the microporous membrane is preferably 5 μm or more from the viewpoint of safety, preferably 35 μm or less from the viewpoint of high output and high capacity density, and more preferably 25 μm or less. This film thickness is measured according to the method described in the following Examples.

The pore diameter of the microporous membrane is preferably 0.01 μm to 0.1 μm, and the number of pores is preferably 100 to 250 / μm ² . When the pore diameter is 0.01 μm or more, the size is such that ions can be sufficiently diffused, and when the pore diameter is 0.1 μm or less, the roughness of the film surface can be reduced, so that short-circuiting due to the electrode biting in can be prevented. Can be prevented. When the number of pores is 100 / μm ² or more, it is possible to have a sufficient space for ions to diffuse, and when the number is 250 / μm ² or less, the strength of the film can be maintained. The pore diameter and the number of pores are measured according to the methods described in the following examples.

Further, it is preferable that the measured Burgmann index is 2.0 to 3.0 when the methyl ethyl carbonate of the microporous membrane is measured as a probe molecule. The Burgman index is ε × D = ε ^α × D ₀ (where, using a diffusion coefficient (D) obtained from a pulse magnetic field gradient nuclear magnetic resonance method (PFG-NMR method) using methyl ethyl carbonate as a probe molecule. ε is the porosity of the membrane, D ₀ is the diffusion coefficient in free space, and α is the Burgman index). This value expresses the quality of the pore structure of the membrane independent of the porosity. is there. Therefore, the smaller the Burgman index, the better the pore structure in ion diffusion. When the index is 2.0 or more, the strength of the film can be maintained, and when the index is 3.0 or less, a pore structure sufficiently suitable for ion diffusion can be obtained. This index is measured according to the method described in the Examples below.

  In addition to the above steps (1) to (4), the method for producing a microporous membrane may include a step of superimposing a plurality of single layer bodies as a step for obtaining a laminate. In addition, the production method may include a step of subjecting the microporous film to surface treatment such as electron beam irradiation, plasma irradiation, surfactant coating, and chemical modification.

Hereinafter, an inorganic membrane separator in which an insulating porous membrane is applied to a single membrane separator will be described.
<Inorganic membrane separator>
The inorganic membrane separator includes a polyolefin porous membrane and an insulating porous membrane formed on one side of the polyolefin porous membrane. By using the separator of the present invention, in the event of an internal short circuit, the insulating porous film suppresses the temperature rise of the capacitor, suppresses the occurrence of gasification, smoke, and ignition, and the polyolefin porous film reduces the resistance (that is, high output density). ) And high cycle characteristics.

As shown in FIG. 5, the separator of the present invention is a two-layer laminated separator (hereinafter referred to as “ Also referred to as “laminated separator”.
In addition, the lithium ion capacitor of the present invention is characterized in that the insulating porous film of the separator is laminated so as to be in contact with the negative electrode body.

The effect exhibited by the lithium ion capacitor of the present invention having a structure in which the insulating porous film of the separator is laminated so as to be in contact with the negative electrode body is estimated as follows.
In a lithium ion capacitor, the energy capacity of the negative electrode is much larger than that of the positive electrode, so the insulating porous film of the separator and the negative electrode body face each other to prevent thermal runaway during internal short circuit and gasification・ Smoke and fire are less likely to occur, ensuring high safety of lithium ion capacitors.
In a lithium ion capacitor, since the positive electrode is faster in adsorption and desorption of ions during charge and discharge than the negative electrode, reducing the speed increases the resistance of the device. Therefore, by facing a polyolefin film having a diffusion resistance smaller than that of the insulating porous film on the positive electrode side, a high output density can be obtained without increasing the resistance of the device.
Furthermore, although the polyolefin porous film is inferior in liquid retention, the presence of an insulating porous film excellent in liquid retention does not cause liquid drainage in the separator during device cycle, and high cycle characteristics can be obtained. .
Accordingly, in the present invention, as long as the insulating porous film is in contact with the negative electrode side and the polyolefin film is in contact with the positive electrode side, a plurality of polyolefin porous films (1) and insulating porous films (2) may be laminated. A plurality of porous membranes (1) and insulating porous membranes (2) may be laminated alternately, but in order to obtain a low resistance and high cycle lithium ion capacitor, the polyolefin porous membrane (1) and the insulating porous membrane A two-layer structure in which the films (2) are laminated one by one is more preferable.
In the lithium ion secondary battery, the difference in energy capacity between the positive electrode and the negative electrode is not as great as that of the lithium ion capacitor. Therefore, when using the separator having the laminated structure of the present invention, in order to suppress the oxidation of the separator, the insulating porous film is generally disposed so as to face the positive electrode body in a highly oxidized state. That is, since the energy capacity of the negative electrode is much larger than that of the positive electrode, the concept of utilizing the insulating porous film is completely different from the present invention in which the insulating porous film of the laminated separator is opposed to the negative electrode body.

In the laminated separator according to the present invention, the ratio of the thickness of the insulating porous film to the thickness of the polyolefin porous film is preferably 0.25 to 1.00. When the ratio of the thickness of the insulating porous film to the thickness of the polyolefin porous film is 0.25 or more, the temperature rise of the capacitor can be sufficiently suppressed at the time of an internal short circuit, and sufficient liquid retention of the electrolytic solution is achieved. On the other hand, 1.00 or less is preferable because a large increase in ion diffusion resistance can be suppressed and sufficient output characteristics can be expressed.
The total thickness of the separator is preferably 8 μm or more and 65 μm or less.

  In the embodiment of the present invention, the puncture strength (absolute strength) of the separator is preferably 200 g or more, and more preferably 400 g or more. When the piercing strength is 200 g or more, when a microporous film is used as a capacitor separator, pinholes or cracks may occur even when sharp parts such as electrode materials provided in the capacitor pierce the microporous film. It is preferable from the viewpoint that generation can be reduced. Although there is no restriction | limiting in particular as an upper limit of puncture strength, It is preferable that it is 1000 g or less. The puncture strength is measured according to the method described in the following examples.

Further, it is preferable that the Burgmann index calculated by measuring methyl ethyl carbonate of the separator as a probe molecule is 2.5 to 3.5. The Burgman index does not depend on the porosity calculated using the diffusion coefficient (D) of methyl ethyl carbonate in the separator film thickness direction, which is obtained by the pulsed magnetic field gradient nuclear magnetic resonance method (PFG-NMR method). It is a value that expresses the quality of the pore structure of the membrane.
When the separator is a polyolefin porous membrane, ε × D = εα × D ₀ (where ε is the porosity of the membrane, D ₀ is the diffusion coefficient of methyl ethyl carbonate in free space at 30 ° C., and α is The Burgman index is calculated according to the above.
When the separator is a laminated porous membrane of a polyolefin porous membrane and an insulating porous layer, methyl ethyl carbonate in the polyolefin porous membrane and methyl ethyl carbonate in the insulating porous layer are detected as separate peaks by the PFG-NMR method. The diffusion coefficients in the individual film thickness directions are calculated. In this case, L1 / (L1 + L2) × ε1 × D1 + L2 / (L1 + L2) × ε2 × D2 = (L1 / (L1 + L2) × ε1 + L2 / (L1 + L2) × ε2) α × D ₀ (where L1: polyolefin porous Film thickness, L2: insulating porous layer thickness, ε1: porosity of polyolefin porous membrane, ε2: porosity of insulating porous layer, D1: film thickness of methyl ethyl carbonate in polyolefin porous membrane at 30 ° C D2 is a diffusion coefficient in the direction of film thickness of methyl ethyl carbonate in the insulating porous layer at 30 ° C., D ₀ is a diffusion coefficient of methyl ethyl carbonate in free space at 30 ° C., and α is a Burgman index. )), The Burgman index is calculated.
Therefore, the smaller the Burgman index, the better the pore structure in ion diffusion. If the index is 2.5 or more, the strength of the film can be maintained, and if the index is 3.5 or less, a pore structure sufficiently suitable for ion diffusion can be obtained. This index is measured according to the method described in the Examples below.

In the embodiment of the present invention, when the separator is kept at 100 ° C. for 1 hour in an unconstrained state, the thermal shrinkage rate of the separator is in the MD direction (the sheet-formed separator is wound in a roll state). 0% or more in any of the advancing direction when taking and also referred to as “longitudinal direction”) and TD direction (direction perpendicular to the MD direction, also referred to as “width direction” or “short direction”). It is preferable that it is 3% or less. If the heat shrinkage rate is 3% or less, a large temperature rise can be suppressed by instantaneously short-circuiting internally due to the meltdown of the separator and causing a large current to flow. In this specification, the “unconstrained state” means a state in which the object is not fixed, and means, for example, that a sheet-like separator is put in an oven as it is. This heat shrinkage rate is measured according to the method described in the following examples.
In addition, the thermal contraction rate in MD direction and TD direction of a separator can be adjusted by optimizing the extending | stretching temperature and magnification at the time of heat setting.

  Examples of means for forming a microporous separator having various characteristics as described above include, for example, the ratio of the thickness of the polyolefin porous film to the thickness of the insulating porous layer, the concentration of polyolefin during extrusion, and polyethylene and polypropylene in the polyolefin. Optimize the blending ratio of various polyolefins, the molecular weight of the polyolefin, the draw ratio, the method of optimizing stretching and relaxation after extraction, the type or particle size of insulating particles in the insulating porous layer, and the blending ratio of insulating particles and binder A method is mentioned.

<Components of separator>
Hereinafter, the polyolefin porous membrane and the insulating porous membrane, which are constituent elements of the separator, will be described.
<Polyolefin porous membrane>
The polyolefin porous membrane is a porous membrane made of polyolefin.
In the embodiment of the present invention, the polyolefin porous membrane preferably has a thickness of 5 μm or more and 35 μm or less. When the thickness of the polyolefin porous film is 5 μm or more, it is preferable because the capacitor can be sufficiently impregnated with the capacitor, and further, when the thickness is 35 μm or less, the ion diffusion resistance is increased. This is preferable because it can be suppressed and a high output density of the capacitor can be exhibited. Furthermore, the thickness of the polyolefin porous membrane is more preferably 20 μm or less.
In the embodiment of the present invention, the porosity of the polyolefin porous membrane is preferably 50% to 75%. Setting the porosity to 50% or more is preferable from the viewpoint of following the rapid movement of lithium ions at the high rate when the polyolefin porous membrane is used as a part of the separator. On the other hand, setting the porosity to 75% or less is preferable from the viewpoint of improving the film strength, and is also preferable from the viewpoint of suppressing self-discharge when the polyolefin porous film is used as a part of the separator. The porosity is measured according to the method described in the following examples.

Moreover, the pore diameter of the polyolefin porous membrane is preferably 0.01 μm to 0.1 μm, and the number of pores is preferably 100 to 250 / μm ² . When the pore diameter is 0.01 μm or more, the ion can be sufficiently diffused, and when the pore diameter is 0.1 μm or less, the roughness of the film surface can be reduced, so that a short circuit due to the electrode biting in. Can be prevented. When the number of pores is 100 / μm ² or more, it is possible to have a sufficient space for ions to diffuse, and when the number is 250 / μm ² or less, the strength of the film can be maintained. . The pore diameter and the number of pores are measured according to the methods described in the following examples.
In the embodiment of the present invention, the polyolefin used for forming the polyolefin porous membrane preferably contains polyethylene as an essential component. The polyolefin may be composed of one kind of polyethylene or a polyolefin composition containing plural kinds of polyolefins.
The polyolefin is the same as the polyolefin and material used for the single membrane separator, the clay average molecular weight (Mv), and the melting point.
As polyolefin, it is preferable to use high-density polyethylene from the point that heat fixation can be performed at a higher temperature while suppressing clogging of pores. The proportion of polyethylene in the polyolefin is the same as that of the single membrane separator.
Moreover, as a polyolefin, the viscosity average molecular weight (Mv) is 100,000-300,000 from a viewpoint of improving the shutdown characteristic at the time of using a microporous film as a capacitor separator, or improving the safety | security of a nail penetration test. It is preferable to use polyethylene as well as a single membrane separator,
The ratio of such 100,000 to 300,000 polyethylene in the polyolefin is the same as that of the single membrane separator. Polypropylene may be used by adding polypropylene from the viewpoint of controlling the meltdown temperature, and the proportion of polypropylene in the polyolefin is the same as that of a single membrane separator.

<Insulating porous membrane>
The insulating porous film is a porous film having electrical insulating properties.
The insulating porous film is formed on one side of the polyolefin porous film.
In the embodiment of the present invention, the insulating porous film preferably includes insulating particles, and more preferably includes an inorganic filler and a resin binder.
In the embodiment of the present invention, the thickness of the insulating porous film is preferably 3 μm or more and 30 μm or less. The thickness of the insulating porous film is preferably 3 μm or more because it is possible to suppress the temperature rise of the capacitor at the time of an internal short circuit and suppress the occurrence of gasification, smoke generation and ignition, and on the other hand, if it is 30 μm or less, It is preferable because an increase in ion diffusion resistance can be suppressed and a high output density can be expressed.
Examples of the inorganic filler include oxide ceramics such as alumina, silica (silicon oxide), titania, zirconia, magnesia, ceria, yttria, zinc oxide and iron oxide; nitrides such as silicon nitride, titanium nitride and boron nitride Ceramics: silicon carbide, calcium carbonate, aluminum sulfate, aluminum hydroxide, potassium titanate, talc, kaolin clay, kaolinite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amicite, bentonite, asbestos, zeolite, Ceramics such as calcium silicate, magnesium silicate, diatomaceous earth, and silica sand; glass fiber.

The average particle size of the inorganic filler is preferably more than 0.1 μm and not more than 4.0 μm, more preferably more than 0.2 μm and not more than 3.5 μm, and more than 0.4 μm and not more than 3.0 μm. Further preferred. It is preferable to make the average particle size of the inorganic filler larger than 0.1 μm because an increase in ion diffusion resistance can be suppressed and a high output density is easily expressed. It is preferable to set the average particle size of the inorganic filler to 4.0 μm or less because it is easy to suppress the temperature rise of the capacitor and to suppress the occurrence of gasification, smoke generation, and ignition during an internal short circuit. Examples of the method of adjusting the particle size ratio include a method of reducing the particle size by pulverizing the inorganic filler using a ball mill, a bead mill, a jet mill or the like.
The proportion of the insulating particles in the insulating porous film can be appropriately determined from the viewpoints of the binding properties of the inorganic filler, the ion diffusion resistance and the heat resistance of the multilayer porous film, and the like. It is preferably less than mass%, more preferably from 70 mass% to 99.99 mass%, further preferably from 80 mass% to 99.9 mass%, particularly preferably from 90 mass% to 99 mass%. .

As the resin binder, it is preferable that an inorganic filler can be bound, it is insoluble in the electrolyte solution of the lithium ion secondary battery, and it is electrochemically stable within the use range of the lithium ion secondary battery.
Examples of such resin binders include polyolefins such as polyethylene and polypropylene, fluorine-containing resins such as polyvinylidene fluoride and polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymers, and ethylene-tetrafluoro. Fluorine-containing rubber such as ethylene copolymer, styrene-butadiene copolymer or its hydride, acrylonitrile-butadiene copolymer or its hydride, acrylonitrile-butadiene-styrene copolymer or its hydride, methacrylate ester-acrylic Rubber such as acid ester copolymer, styrene-acrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, ethylene propylene rubber, polyvinyl alcohol, polyvinyl acetate , Polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyetherimide, polyamideimide, polyamide, melting point and / or glass transition temperature of such polyesters are 180 ° C. or more resins. These can be used alone or in combination of two or more.

As the resin binder, a resin latex binder is preferable. When a resin latex binder is used, when a porous layer containing an inorganic filler and a binder is laminated on at least one surface of a polyolefin porous membrane, ion permeability is unlikely to decrease and high output characteristics are easily obtained. In addition, even when the temperature rise during abnormal heat generation is fast, a smooth shutdown is shown and high safety is easily obtained. On the other hand, after part or all of the resin binder is dissolved in a solvent, it is laminated on at least one side of the polyolefin porous membrane, and when the resin binder is bound by immersion in a poor solvent or solvent removal by drying, etc. Not only is it difficult to obtain high output characteristics, it is difficult to exhibit smooth shutdown characteristics, and there is a tendency to be inferior in safety.
The average particle size of the resin binder in the present embodiment is preferably 50 to 500 nm, more preferably 60 to 460 nm, and still more preferably 80 to 250 nm. When the resin binder has an average particle size of 50 nm or more, when a porous layer containing an inorganic filler and a binder is laminated on at least one surface of the polyolefin porous film, the ion permeability is unlikely to decrease and high output characteristics are easily obtained. In addition, even when the temperature rise during abnormal heat generation is fast, a smooth shutdown is shown and high safety is easily obtained. When the average particle diameter of the resin binder is 500 nm or less, good binding properties are exhibited, and when a multilayer porous film is formed, heat shrinkage tends to be good and the safety tends to be excellent.
The average particle diameter of the resin binder can be controlled by adjusting the polymerization time, polymerization temperature, raw material composition ratio, raw material charging order, pH, and the like.

<Method for producing laminated separator (two-layer laminated separator)>
An exemplary method for manufacturing a separator according to an embodiment of the present invention will be described. However, as long as a separator as described above can be obtained, the production method of the present embodiment includes a polymer type, an insulating particle type, a solvent type, an extrusion method, a stretching method, an extraction method, an opening method, It is not limited to the heat setting / heat treatment method.
The separator manufacturing method includes a step of melting and kneading a polymer and a plasticizer or a polymer, a plasticizer and a filler, a stretching step, a plasticizer (and filler if necessary) extraction step, a heat It is preferable to include a fixing step from the viewpoint of appropriately controlling the physical property balance between permeability and membrane strength.

More specifically, the separator manufacturing method can include, for example, the following steps (1) to (4):
(1) A kneading step in which a polyolefin, a plasticizer, and a filler as necessary are kneaded to form a kneaded product.
(2) A sheet forming step of extruding the kneaded material after the kneading step, forming it into a single-layered or laminated sheet and cooling and solidifying it.
(3) A stretching step of extracting a plasticizer and / or filler as necessary after the sheet molding step and further stretching the sheet (sheet-like molded body) in a direction of one axis or more.
(4) A post-processing step in which a plasticizer and / or a filler is extracted as necessary after the stretching step and further subjected to heat treatment.
After passing through the above four steps, the inorganic membrane separator of the present invention is manufactured through the following step (5).
(5) A coating step in which a separator is obtained by coating a mixture of insulating particles and a resin binder on at least one surface of the obtained polyolefin film.

Each of the steps (1) to (4) described above is performed in the same manner as the single membrane separator.
Examples of the coating step (5) include a method of forming a porous layer by applying and drying a coating liquid containing insulating particles and a resin binder on at least one surface of a porous film containing a polyolefin resin as a main component.
As the solvent for the coating solution, those capable of uniformly and stably dispersing or dissolving the insulating particles and the resin binder are preferable. For example, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, water , Ethanol, toluene, hot xylene, methylene chloride, hexane and the like.
The concentration of the coating solution ((mass of insulating particles + mass of resin binder) × 100 / mass of coating solution) is preferably 10 to 90%, more preferably 15 to 80%, and still more preferably 20 to 70%. Since the viscosity can be lowered if the concentration of the coating solution is 90% or less, thin film coating is facilitated. On the other hand, if the concentration of the coating solution is 10% or more, the drying time is short and the film thickness can be easily adjusted.
Various additives such as surfactants, thickeners, wetting agents, antifoaming agents, PH preparations containing acids and alkalis are added to the coating solution in order to stabilize dispersion and improve coating properties. May be added. These additives are preferably those that can be removed when the solvent is removed. However, if these additives are electrochemically stable in the range of use of the lithium ion secondary battery or capacitor, do not inhibit the battery reaction, and are stable up to about 200 ° C. For example, it may remain in the porous layer.

The method for dispersing or dissolving the insulating particles and the resin binder in the solvent of the coating solution is not particularly limited as long as it is a method capable of realizing the dispersion characteristics of the coating solution necessary for the coating step. Examples thereof include a ball mill, a bead mill, a planetary ball mill, a vibrating ball mill, a sand mill, a colloid mill, an attritor, a roll mill, a high-speed impeller dispersion, a disperser, a homogenizer, a high-speed impact mill, ultrasonic dispersion, and mechanical stirring using a stirring blade.
The method for applying the coating solution to the porous film is not particularly limited as long as the required layer thickness or coating area can be realized. Examples include coater method, kiss coater method, dip coater method, knife coater method, air doctor coater method, blade coater method, rod coater method, squeeze coater method, cast coater method, die coater method, screen printing method, spray coating method, etc. .
The method for removing the solvent from the coating film after coating is not particularly limited as long as it does not adversely affect the porous film. For example, a method of drying at a temperature below its melting point while fixing the porous membrane, a method of drying under reduced pressure at a low temperature, and the like can be mentioned.

In addition, in addition to each process of said (1)-(5), the manufacturing method of a separator can have the process of laminating | stacking several single layer bodies as a process for obtaining a laminated body. In addition, the production method may include a step of subjecting the polyolefin porous film and the insulating porous layer to surface treatment such as electron beam irradiation, plasma irradiation, surfactant coating, and chemical modification.
Hereinafter, other constituent materials used for the non-aqueous lithium storage element of the present invention will be described.

(Electrode terminal)
An electrode terminal (collectively referred to as a positive electrode terminal and a negative electrode terminal) generally has a substantially rectangular shape, one end of which is electrically connected to an electrode current collector, and the other end is externally connected during use. It is electrically connected to a load (when discharging) or a power source (when charging). One end of the positive electrode terminal is electrically connected to the positive electrode, and one end of the negative electrode terminal is electrically connected to the negative electrode. Specifically, the positive electrode terminal is electrically connected to the uncoated region of the positive electrode active material layer of the positive electrode current collector, and the negative electrode terminal is electrically connected to the uncoated region of the negative electrode active material layer of the negative electrode current collector. In the electrode terminal, the material of the positive electrode terminal is preferably aluminum, and the material of the negative electrode terminal is preferably copper plated with nickel.
It is preferable that a resin film such as polypropylene is attached to the central portion of the electrode terminal, which is a sealing portion of the laminate film outer package described below. This prevents a short circuit between the electrode terminal and the metal foil constituting the laminate film, and improves the sealing hermeticity.
For example, an ultrasonic welding method is generally used as an electrical connection method between the electrode body and the electrode terminal. However, resistance welding, laser welding, or the like may be used, and the method is not limited.

(Exterior body)
As a metal can used for an exterior body, the thing made from aluminum is preferable. Further, the outer package can be formed from a laminate film, and the laminate film used in that case is preferably a film in which a metal foil and a resin film are laminated, and is composed of three layers comprising an outer layer resin film / metal foil / inner layer resin film. The thing of a structure is illustrated. The outer layer resin film is for preventing the metal foil from being damaged by contact or the like, and a resin such as nylon or polyester can be suitably used. The metal foil is for preventing the permeation of moisture or gas, and a foil of copper, aluminum, stainless steel or the like can be suitably used. The inner layer resin film protects the metal foil from the electrolyte contained therein and melts and seals it at the time of heat sealing. Polyolefin and acid-modified polyolefin can be preferably used.

(Non-aqueous electrolyte)
In this embodiment, as a solvent for the non-aqueous electrolyte used in the electricity storage element, cyclic carbonate represented by ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), A chain carbonate represented by ethyl methyl carbonate (MEC), a lactone such as γ-butyrolactone (γBL), or a mixed solvent thereof can be used.
The electrolyte dissolved in the solvent needs to be a lithium salt, and preferable lithium salts include LiBF ₄ , LiPF ₆ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ ). F ₅ ), LiN (SO ₂ CF ₃ ) (SO ₂ C ₂ F ₄ H), or a mixed salt thereof. The electrolyte concentration in the non-aqueous electrolyte is preferably in the range of 0.5 to 2.0 mol / L. If it is 0.5 mol / L or more, the supply of anions will not be insufficient, and the capacity of the electricity storage element will increase. On the other hand, if it is 2.0 mol / L or less, the undissolved salt precipitates in the electrolyte solution, or the viscosity of the electrolyte solution becomes too high. There is no risk of decline.

(Storage element)
In the non-aqueous lithium storage element of this embodiment, the positive electrode and the negative electrode are inserted into an exterior body formed from a metal can or a laminate film as an electrode body laminated or wound around via a separator.
One embodiment of the non-aqueous lithium storage element of this embodiment is represented by the schematic cross-sectional views of FIGS. 1A and 1B, and includes a positive electrode terminal (7) and a negative electrode terminal (8). This is a mode derived from one side of the electrode body (10). As another embodiment, a mode in which the positive electrode terminal (7) and the negative electrode terminal (8) are led out from two opposing sides of the electrode body (10) can be mentioned. The latter embodiment is suitable for applications in which a larger current flows because the electrode terminals can be made wider.

  The power storage element includes a positive electrode (16) in which a positive electrode active material layer (12) is laminated on a positive electrode current collector (11), and a negative electrode (17) in which a negative electrode current collector (14) is laminated with a negative electrode active material layer (15). Are stacked alternately so that the positive electrode active material layer (12) and the negative electrode active material layer (15) face each other with the separator (13) interposed therebetween to form the electrode body (10), and the positive electrode terminal (7) Is connected to the positive electrode current collector (11), the negative electrode terminal (8) is connected to the negative electrode current collector (14), the electrode body (10) is housed in the exterior body (9), and a non-aqueous electrolyte ( The outer periphery of the exterior body (9) is poured into the exterior body (9) and the ends of the positive terminal (7) and the negative terminal (8) are pulled out of the exterior body (9). The part is sealed.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited at all by these Examples.
<Example 1>
(Preparation of positive electrode)
A resin raw material having an aspect ratio of 1.25 or less was prepared as follows. After preparing 10000 g of a mixed solution having a formaldehyde concentration of 15 wt% and a hydrochloric acid concentration of 15 wt% using 35 wt% hydrochloric acid and a 36 wt% aqueous formaldehyde solution, 40 g of a 2 wt% aqueous solution of carboxymethylcellulose sodium salt was added to the mixed solution. And stirred to make a homogeneous solution. Next, after adjusting the temperature of the homogeneous solution to 20 ° C., 400 g of 95 wt% phenol at 30 ° C. was added with stirring. About 120 seconds after the addition of phenol, the reaction solution became cloudy. After the white turbidity, the reaction was continued at a reduced stirring speed. As a result, about 30 minutes after the addition of phenol, the reaction solution was colored pale pink. At this time, the temperature of the reaction solution had reached 30 ° C. After coloring the reaction solution, the reaction solution was heated to 90 ° C. by external heating and kept at this temperature for 30 minutes. Next, this reaction solution was filtered, and the resulting cake was washed with water, then suspended in a 0.5 wt% aqueous ammonia solution, and neutralized at 40 ° C. for 1 hour. After the neutralization reaction, the suspension was subjected to suction filtration using an aspirator, washed with water, and dried in a dryer at 50 ° C. for 20 hours to obtain 350 g of a spherical phenol resin.
The phenol resin was carbonized in a baking furnace at 600 ° C. for 2 hours in a nitrogen atmosphere to obtain a carbide. KOH was mixed with this carbide in a weight ratio of 1: 3.5, and the mixture was activated in a firing furnace by heating at 800 ° C. for 1 hour in a nitrogen atmosphere. Then, after stirring and washing with dilute hydrochloric acid adjusted to 2 mol / L for 1 hour, boiling and washing with distilled water until it is stable between pH 5 and 6, followed by drying, spherical activated carbon having an average particle diameter of about 7 μm (A ) Was produced.

When the aspect ratio of 100 particles was observed with a scanning electron microscope S-4700 (manufactured by Hitachi High-Technologies) at an acceleration voltage of 5 kV and a magnification of 2000, the average was 1.06.
On the other hand, the novolac type phenol resin was carbonized in a baking furnace at 600 ° C. for 2 hours in a nitrogen atmosphere. Thereafter, the fired product was pulverized with a ball mill and classified to obtain a crushed carbide having an average particle size of 7 μm. KOH was mixed with this carbide in a weight ratio of 1: 3.5, and the mixture was activated in a firing furnace by heating at 800 ° C. for 1 hour in a nitrogen atmosphere. Thereafter, the mixture was stirred and washed with dilute hydrochloric acid adjusted to 2 mol / L for 1 hour, then boiled and washed with distilled water until it became stable between pH 5 and 6, and then dried to produce crushed activated carbon (B).
35% by weight of activated carbon (A) and 65% by weight of activated carbon (B) were mixed. The particle size distribution of this mixture was measured using a laser diffraction dry particle size distribution measuring device HELOS & RODOS. The particle size distribution parameter was 2.06. This mixture was used as a positive electrode active material.

The activated carbon of the present invention relating to the positive electrode active material obtained by mixing the activated carbon (A) and the activated carbon (B) is measured with a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics Co., Ltd. Distribution was determined by the above-described method, and BET specific surface area was determined by the BET one-point method. As a result, the mesopore volume V1 was 0.98 cc / g, the micropore volume V2 was 1.05 cc / g, and the BET specific surface area was 2640 m ² / g.
Using this activated carbon as a positive electrode active material, activated carbon 83.4 parts by mass, conductive carbon black (Lion Corporation Ketjen Black ECP600JD) 8.3 parts by mass and PVDF (polyvinylidene fluoride, Kureha KF polymer W # 9300, 8.3 parts by mass of mp 163 ° C. were mixed with NMP (N-methylpyrrolidone) to obtain a slurry-like active material layer. Next, the obtained active material layer was applied to one side of a 15 μm thick aluminum foil having a conductive layer applied to the surface and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.31 g / cm ³ . Note that the basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was the weight of the electrode excluding the current collector and the current density in a dry room in which a sufficiently dried electrode was controlled at −60 ° C. or less. The thickness of the electrode active material layer excluding the thickness of the electric body was obtained and calculated. Ono Sokki DG-4120 was used for the measurement of thickness.

The electrode coated with the active material layer is installed at the unwinding roll position in FIG. The distance between the rolls was 60 μm, and the pressure was applied at 30 μm for the second time to obtain a positive electrode having a bulk density of the electrode active material layer of 0.45 g / cm ³ and a thickness of the electrode layer of 53 μm. The pressing speed was 5 m / min. The temperature of the heating roll was measured by detecting the roll surface temperature in a non-contact manner with an infrared radiation thermometer IT2-60 manufactured by KEYENCE, and adjusting the temperature to the set temperature by PID control. The linear pressure was calculated from the pressure applied to the pressure roll and the length of contact between the upper and lower rolls.
Sample pieces of this electrode were cut out at five locations, cut with an Ar ion beam, and cross-sections were observed with a scanning electron microscope S-4700 (manufactured by Hitachi High-Technologies) at an acceleration voltage of 5 kV and a magnification of 2000 times. Randomly selecting an image of 100 particles and determining the cross-sectional shape and cross-sectional area of each activated carbon particle, the ratio of the area of the particles having an aspect ratio of 1.25 or less is 32% of the total area of all particles. %Met.

(Preparation of negative electrode)
The cured phenol resin was placed in a stainless steel dish and allowed to react by heat. The thermal reaction was carried out in a nitrogen atmosphere, the temperature was raised until the inside of the furnace reached 700 ° C., kept at the same temperature for 4 hours, and then naturally cooled. The obtained material was pulverized using a planetary ball mill to obtain a non-graphitizable carbon material serving as a negative electrode active material. The pore distribution of this carbon material was determined by the aforementioned method using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the mesopore volume Vm1 was 0.0084 cc / g, and the micropore volume Vm2 was 0.0061 cc / g. The negative electrode had a lithium ion storage capacity of 600 mAh / g.
Next, 83.4 parts by mass of the negative electrode active material obtained above, 8.3 parts by mass of acetylene black (Denka Black, Denki Kagaku Kogyo Co., Ltd.) and PVDF (KF polymer KF polymer W # 9300, melting point 163 ° C.) 8. 3 parts by mass was mixed with NMP (N-methylpyrrolidone) to obtain a slurry. Next, the obtained slurry was applied to one side of a copper foil having a thickness of 14 μm, dried, and pressed to obtain a negative electrode having a thickness of 60 μm.

The negative electrode obtained above was cut out to have an area of 3 cm ² , used as a working electrode, metallic lithium as a counter electrode and a reference electrode, and a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a weight ratio of 1: 4. An electrochemical cell was prepared in an argon dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / L as an electrolyte. This electrochemical cell was charged with a constant current at a rate of 85 mAh / g with respect to the weight of the negative electrode active material, using a charge / discharge device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd. until it reached 1 mV with respect to the lithium potential. Thereafter, constant voltage charging was performed at 1 mV, and a total of 500 mAh / g of lithium ions was doped in advance with respect to the weight of the negative electrode active material.

Hereinafter, a method of doping lithium ions will be described.
The negative electrode obtained above was cut out to have an area of 3 cm ² , used as a working electrode, metallic lithium as a counter electrode and a reference electrode, and a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a weight ratio of 1: 4. An electrochemical cell was prepared in an argon dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / L as an electrolyte. This electrochemical cell was charged with a constant current at a rate of 85 mAh / g with respect to the weight of the negative electrode active material, using a charge / discharge device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd. until it reached 1 mV with respect to the lithium potential. Thereafter, constant voltage charging was performed at 1 mV, and a total of 500 mAh / g of lithium ions was doped in advance with respect to the weight of the negative electrode active material.

(Assembly and performance evaluation of storage element)
The positive electrode obtained above was cut out to 3 cm ² , and the positive electrode and the negative electrode previously doped with lithium were ultrasonically fused to the positive electrode terminal and the negative electrode terminal, respectively, to make a 30 μm thick cellulose product. The non-woven fabric separator was placed opposite to each other, housed in an exterior body made of a laminate film of polypropylene, aluminum, and nylon. The exterior body was sealed by heat sealing in the state, and a lithium ion capacitor was assembled. At this time, a solution in which LiPF ₆ was dissolved to a concentration of 1 mol / L in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a ratio of 1: 4 (weight ratio) was used as an electrolytic solution.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The discharge capacity was 0.711 mAh. The capacity per active material weight of the electrode was 165 F / g, and the capacity per volume of the electrode active material layer (hereinafter also referred to as “volume capacity”) was 79 F / cm ³ .
Next, when the same charge was performed and the battery was discharged at 100 mA to 2.0 V, a discharge capacity of 0.626 mAh was obtained. The ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 88%.

(Assembly and performance evaluation of storage element)
The positive electrode obtained above was cut out to 3 cm ² , and the positive electrode and the negative electrode previously doped with lithium were ultrasonically fused to the positive electrode terminal and the negative electrode terminal, respectively, to make a 30 μm thick cellulose product. The non-woven fabric separator was placed opposite to each other, housed in an exterior body made of a laminate film of polypropylene, aluminum, and nylon. The exterior body was sealed by heat sealing in the state, and a lithium ion capacitor was assembled. At this time, a solution in which LiPF ₆ was dissolved to a concentration of 1.2 mol / L in a solvent obtained by mixing ethylene carbonate and methyl ethyl carbonate at a weight ratio of 1: 2 was used as an electrolytic solution.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The discharge capacity per active material weight of the electrode was 163 F / g, and the capacity per volume of the electrode active material layer (hereinafter also referred to as “volume capacity”) was 73 F / cm ³ .

This cell is subjected to cycle charge / discharge that repeats constant current charge and constant current discharge at 300C in the voltage range from 2V to 4V, and the cycle capacity is maintained by comparing the discharge capacity at 1mA after repeating 100,000 times with the initial discharge capacity. The rate was 75%.
A positive electrode cut out in an area of 3 cm @ 2 and a counter electrode made by attaching a metal lithium foil of 0.5 mm thickness of the same size to a stainless steel mesh cut out in the same size are opposed to each other through a glass filter of 1 mm thickness. And the monopolar cell which pressed and fixed the outer side of the stainless steel mesh with the glass plate was produced. Metal lithium was installed near the positive electrode as a reference electrode, and the positive electrode was charged with constant current and discharged at a current density of 1 mA / cm @ 2 in the range of 4.2 V to 2.2 V with respect to the metal lithium. The relationship between the discharge capacity and voltage at the time of discharge was determined. The ratio of the discharge capacity from 3.2 V to 2.2 V to the discharge capacity from 4.2 V to 2.2 V was 0.43.

<Example 2>
(Preparation of positive electrode)
The spherical carbide and crushed carbide described in Example 1 were activated by mixing KOH at a weight ratio of 1: 4.3 to obtain activated carbon (A) and (B), and then mixing them. Activated carbon was produced under the same conditions as in Example 1. The particle size distribution parameter of this mixture was 2.11.
When the mixed activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.21 cc / g, the micropore volume V2 was 1.84 cc / g, and the BET specific surface area was 3100 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 33% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 172 F / g, and the volume capacity was 74 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 88%.
When the cycle maintenance ratio was evaluated in the same manner as in Example 1, it was 74%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Example 3>
(Preparation of positive electrode)
Except for mixing and activating KOH at a weight ratio of 1: 5 to the spherical carbides and crushed carbides described in Example 1 to obtain activated carbon (A) and (B), and then mixing them, Example 1 Activated charcoal was produced under the same conditions. The particle size distribution parameter of this mixture was 2.08.
When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.32 cc / g, the micropore volume V2 was 2.12 cc / g, and the BET specific surface area was 3380 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.28 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time with a linear pressure of 130 kgf / cm with the heated press roll heated to 140 ° C. The second time Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.41 g / cm ³ and a thickness of 59 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 32% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 181 F / g, and the volume capacity was 74 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 78%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.46.

<Example 4>
(Preparation of positive electrode)
The activated carbon (A) produced in Example 1 was mixed with 65% by weight and the activated carbon (B) was mixed with 35% by weight. The particle size distribution parameter of this mixture was 1.67.
When the mixed activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 0.99 cc / g, the micropore volume V2 was 1.12 cc / g, and the BET specific surface area was 2690 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.31 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll device in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 110 kgf / cm with a heated press roll heated to 140 ° C. Pressure was applied at 30 μm to obtain a positive electrode having a bulk density of 0.46 g / cm ³ and a thickness of 52 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 61% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 164 F / g, and the volume capacity was 75 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 88%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 80%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.43.

<Example 5>
(Preparation of positive electrode)
65% by weight of the activated carbon (A) prepared in Example 2 and 35% by weight of the activated carbon (B) were mixed. The particle size distribution parameter of this mixture was 1.74.
When the mixed activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.25 cc / g, the micropore volume V2 was 1.83 cc / g, and the BET specific surface area was 3140 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.44 g / cm ³ and a thickness of 55 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 63% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1. Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 173 F / g, and the volume capacity was 76 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 82%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.44.

<Example 6>
(Preparation of positive electrode)
65% by weight of the activated carbon (A) prepared in Example 3 and 35% by weight of the activated carbon (B) were mixed. The particle size distribution parameter of this mixture was 1.72.
When the mixed activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.31 cc / g, the micropore volume V2 was 1.92 cc / g, and the BET specific surface area was 3420 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.41 g / cm ³ and a thickness of 59 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 60% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 180 F / g, and the volume capacity was 74 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 90%.
When the cycle maintenance ratio was evaluated in the same manner as in Example 1, it was 83%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.46.

<Example 7>
(Preparation of positive electrode)
Only the spherical activated carbon (A) produced in Example 1 was used. The particle size distribution parameter of this activated carbon was 1.21.
When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.00 cc / g, the micropore volume V2 was 1.08 cc / g, and the BET specific surface area was 2650 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.31 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.47 g / cm ³ and a thickness of 51 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 92% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 161 F / g, and the volume capacity was 76 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 85%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.44.

<Example 8>
(Preparation of positive electrode)
Only the spherical activated carbon (A) produced in Example 2 was used. The particle size distribution parameter of this activated carbon was 1.24.
When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.19 cc / g, the micropore volume V2 was 1.85 cc / g, and the BET specific surface area was 3110 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.44 g / cm ³ and a thickness of 55 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 91% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 173 F / g, and the volume capacity was 76 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 91%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 86%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Example 9>
(Preparation of positive electrode)
Only the activated carbon (A) prepared in Example 3 was used. The particle size distribution parameter of this activated carbon was 1.31.
When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.28 cc / g, the micropore volume V2 was 1.86 cc / g, and the BET specific surface area was 3430 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.28 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.42 g / cm ³ and a thickness of 57 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 89% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 181 F / g, and the volume capacity was 76 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 92%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 90%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.47.

<Example 10>
(Preparation of positive electrode)
The electrode in which the active material layer was applied on the aluminum foil in Example 8 was not heated at the first time, but was pressed at a linear pressure of 120 kgf / cm with a room temperature roll at a distance of 60 μm between the rolls, and heated to 140 ° C. the second time. Pressurization was performed with a heated press roll at a linear pressure of 120 kgf / cm and a distance between the rolls of 30 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 91% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 174 F / g, and the volume capacity was 75 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle maintenance ratio was evaluated in the same manner as in Example 1, it was 89%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.47.

<Example 11>
(Preparation of positive electrode)
The electrode in which the active material layer was applied on the aluminum foil in Example 8 was placed in a heated press roll device, and the distance between the rolls was 60 μm at the first time with a linear pressure of 120 kgf / cm using a heated press roll heated to 140 ° C., The second pressure was applied at 36 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 88% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 171 F / g, and the volume capacity was 74 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 87%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Example 12>
(Preparation of positive electrode)
Treatment with 10000 g of a mixed solution having a formaldehyde concentration of 20% by weight and a hydrochloric acid concentration of 10% by weight under the production conditions of the spherical activated carbon (A) of Example 1, and mixing KOH with carbide in a weight ratio of 1: 4.3 The activated carbon (A) having an average particle diameter of 10 μm was obtained by the same method as that for producing the spherical activated carbon (A) in Example 1 except that the activated carbon was activated. The particle size distribution parameter of this activated carbon was 1.46. When the aspect ratio of 100 particles was observed with a scanning electron microscope S-4700 (manufactured by Hitachi High-Technologies) at an acceleration voltage of 5 kV and a magnification of 2000, the average was 1.12.
When this activated carbon (A) was measured in the same manner as in Example 1, the mesopore volume V1 was 1.23 cc / g, the micropore volume V2 was 1.86 cc / g, and the BET specific surface area was 3100 m ² / g. Using only this activated carbon (A), a slurry-like active material layer was prepared in the same manner as in Example 1, and applied to one side of a 15 μm thick aluminum foil having a conductive layer applied to the surface and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 90% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 172 F / g, and the volume capacity was 74 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 89%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 85%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Example 13>
(Preparation of positive electrode)
Under the production conditions of the spherical activated carbon (A) of Example 1, the mixture was treated with 10000 g of a mixed solution having a formaldehyde concentration of 10% by weight and a hydrochloric acid concentration of 20% by weight, and KOH was mixed with carbides in a weight ratio of 1: 4.3. The activated carbon (A) having an average particle diameter of 2 μm was obtained by the same method as the production conditions of the spherical activated carbon (A) of Example 1 except that the activated carbon was activated. The particle size distribution parameter of this activated carbon was 1.16. When the aspect ratio of 100 particles was observed with a scanning electron microscope S-4700 (manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 5 kV and a magnification of 2000 times, the average was 1.05.
When this activated carbon (A) was measured in the same manner as in Example 1, the mesopore volume V1 was 1.22 cc / g, the micropore volume V2 was 1.84 cc / g, and the BET specific surface area was 3080 m ² / g. Using only this activated carbon (A), a slurry-like active material layer was prepared in the same manner as in Example 1, and applied to one side of a 15 μm thick aluminum foil having a conductive layer applied to the surface and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode in which the active material layer was applied on the aluminum foil in Example 1 was installed in a heated press roll apparatus, and the distance between the rolls was 60 μm at the first time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. The second pressure was applied at 24 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 94% with respect to all particles.
(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 169 F / g, and the volume capacity was 73 F / cm ³ .

Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 90%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 86%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.46.

<Example 14>
(Preparation of positive electrode)
Example 8 The positive electrode used was used.
(Preparation of negative electrode) OGC
The pore distribution was measured using a commercially available coconut shell activated carbon with a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics Co., Ltd. using nitrogen as an adsorbate. The specific surface area was determined by the BET single point method. Further, as described above, using the isotherm on the desorption side, the mesopore amount was determined by the BJH method, and the micropore amount was determined by the MP method. As a result, the BET specific surface area was 1,780 m2 / g, the mesopore volume (V1) was 0.198 cc / g, the micropore volume (V2) was 0.695 cc / g, V1 / V2 = 0.29, and the average pore diameter. Was 21.2 kg.
150 g of this activated carbon is placed in a stainless steel mesh jar, placed on a stainless steel bat containing 75 g of coal-based pitch (softening point: 80 ° C.), and placed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). It was installed and a thermal reaction was performed. The heat treatment was performed in a nitrogen atmosphere in 2 hours up to 680 ° C., held at the same temperature for 4 hours, then cooled to 60 ° C. by natural cooling, and then taken out from the furnace to be a composite porous material 1 serving as a negative electrode material Got.
In the composite porous material 1, the weight ratio of the deposited carbonaceous material (hereinafter also referred to as “pitch charcoal”) to the activated carbon is 20%, the BET specific surface area is 958 m 2 / g, and the mesopore amount (Vm 1) is 0.00. It was 153 cc / g and the micropore amount (Vm2) was 0.381 cc / g. Furthermore, it was 3.01 micrometer as a result of measuring an average particle diameter using the Shimadzu Corporation laser diffraction type particle size distribution analyzer (SALD-2000J).
Next, 83.4 parts by weight of the composite porous material 1 obtained above, 8.3 parts by weight of acetylene black, 8.3 parts by weight of PVDF (polyvinylidene fluoride) and NMP (N-methylpyrrolidone) were mixed. To obtain a slurry. Next, the obtained slurry was applied to one side of a 15 μm thick copper foil, dried, and pressed to obtain a negative electrode having a negative electrode active material layer thickness of 30 μm. The thickness of the negative electrode active material layer is determined by calculating the thickness of the copper foil from the average value of the thickness of the negative electrode measured at 10 locations on the negative electrode using a thickness gauge (Linear Gauge Sensor GS-551) manufactured by Ono Keiki Co., Ltd. The value obtained by subtraction.

The negative electrode obtained above was cut out to 3 cm ² , and the working electrode was a negative electrode, the counter electrode was lithium, the reference electrode was lithium, the electrolyte was 1 mol in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a volume ratio of 1: 4. In a tripolar cell in which LiPF ₆ is dissolved, the current value is 100 mA / g per negative electrode active material and the cell temperature is 45 ° C. When lithium is charged and the negative electrode potential reaches 1 mV, it is switched to a constant voltage and further charged. The charge amount after 40 hours in total at constant current and constant voltage charge is defined as the initial lithium charge amount. Discharge when lithium is discharged at a constant current until the negative electrode potential becomes 2.5 V under the condition that the value is 50 mA / g per substance and the cell temperature is 45 ° C. Is the initial lithium discharge amount, the initial lithium charge amount is 1605 mAh / g, and of the initial lithium discharge amount, the discharge amount when the negative electrode potential is between 0 and 0.5 V is 145 mAh / g. It was.
Furthermore, the same slurry as above was applied to both sides of the copper foil, dried, and then pressed to obtain a negative electrode having a negative electrode active material layer thickness of 60 μm. This negative electrode was cut out to 3 cm ^2, and a total of 1605 mAh / g of lithium ions was pre-doped with respect to the weight of the composite porous material 1 to produce a negative electrode.

(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 171 F / g, and the volume capacity was 75 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 91%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 85%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Comparative Example 1>
(Preparation of positive electrode)
Activated carbon was produced under the same conditions as in Example 1 except that only the crushed activated carbon (B) produced in Example 1 was used. The particle size distribution parameter of this activated carbon was 2.51. When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 0.98 cc / g, the micropore volume V2 was 0.98 cc / g, and the BET specific surface area was 2630 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.31 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 100 kgf / cm with a heated press roll heated to 140 ° C. Pressure was applied at 30 μm to obtain a positive electrode having a bulk density of 0.46 g / cm ³ and a thickness of 52 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 9% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 163 F / g, and the volume capacity was 74 F / cm ³ .
Next, the same charge was performed and the battery was discharged to 2.0 V at 100 mA. The ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was 86%.
When the cycle retention rate was evaluated in the same manner as in Example 1, the result was as low as 59%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.43.

<Comparative Example 2>
(Preparation of positive electrode)
Activated carbon was produced under the same conditions as in Example 1 except that only activated carbon (B) produced in Example 2 was used. The particle size distribution parameter of this activated carbon was 2.62. When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.26 cc / g, the micropore volume V2 was 1.85 cc / g, and the BET specific surface area was 3120 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.29 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll device in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 110 kgf / cm with a heated press roll heated to 140 ° C. Pressurization was performed at 30 μm to obtain a positive electrode having a bulk density of 0.43 g / cm ³ and a thickness of 56 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 11% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 175 F / g, and the volume capacity was 75 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was 88%.
When the cycle retention rate was evaluated in the same manner as in Example 1, the result was as low as 64%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.45.

<Comparative Example 3>
(Preparation of positive electrode)
Activated carbon was produced under the same conditions as in Example 1 except that only activated carbon (B) produced in Example 3 was used. The particle size distribution parameter of this activated carbon was 2.65. When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 1.37 cc / g, the micropore volume V2 was 2.09 cc / g, and the BET specific surface area was 3410 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.28 g / cm ³ .
The electrode coated with the active material layer was installed in a heated press roll apparatus as in Example 1, but the distance between the rolls was 60 μm for the first time at a linear pressure of 100 kgf / cm with a press roll at room temperature without heating. The second pressure was applied at 30 μm to obtain a positive electrode having a bulk density of 0.41 g / cm ³ and a thickness of 59 μm of the electrode active material layer. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 12% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 179 / g, and the volume capacity was 73 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was 89%.
When the cycle retention rate was evaluated by the same method as in Example 1, the result was as low as 65%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.47.

<Comparative Example 4>
(Preparation of positive electrode)
Activated carbon was produced under the same conditions as in Example 1 except that only the spherical carbide produced in Example 1 was used and KOH was mixed with the carbide in a weight ratio of 1: 2.2 with respect to the weight of the carbide. The particle size distribution parameter of this activated carbon was 1.23. When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 0.31 cc / g, the micropore volume V2 was 0.78 cc / g, and the BET specific surface area was 2100 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.33 g / cm ³ .
When the electrode in which the active material layer was applied on the aluminum foil in Example 1 was pressed only once with a linear pressure of 100 kgf / cm and a distance between rolls of 60 μm, the bulk density of the electrode active material layer was 0.54 g / cm ³ , The thickness was 44 μm, and a positive electrode having a higher bulk density than that of Example 1 was obtained. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 92% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 140 F / g, and the volume capacity was 76 F / cm ³ .
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was a low value of 79%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 84%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.40.

<Comparative Example 5>
(Preparation of positive electrode)
Activated carbon was used under the same conditions as in Example 1 except that only the activated carbon (A) prepared in Example 1 was used and KOH was mixed with the carbide in a weight ratio of 1: 3.5 with respect to the weight of the carbide (A). Was made. The particle size distribution parameter of this activated carbon was 1.25. When this activated carbon was measured in the same manner as in Example 1, the mesopore volume V1 was 0.95 cc / g, the micropore volume V2 was 1.08 cc / g, and the BET specific surface area was 2660 m ² / g. Using this activated carbon, a slurry-like active material layer was prepared in the same manner as in Example 1, applied to one side of a 15 μm thick aluminum foil having a conductive layer applied on the surface, and dried. The basis weight of the electrode active material layer was 24 g / m ^{2 and the} bulk density was 0.31 g / cm ³ . When the electrode in which the active material layer was applied on the aluminum foil in Example 1 was pressed only once with a linear pressure of 120 kgf / cm and a distance between the rolls of 60 μm, the bulk density of the electrode active material layer was 0.36 g / cm 3 and the thickness was The thickness was 67 μm, which was a positive electrode having a lower bulk density than that of Example 1. The pressing speed was 5 m / min.
When the cross section of the electrode was observed in the same manner as in Example 1 and the ratio of the aspect ratio of 1.25 or less was calculated, it was 91% with respect to all particles.

(Preparation of negative electrode)
The same operation as in Example 1 was performed.
(Assembly and performance evaluation of storage element)
The assembly of the lithium ion capacitor was performed in the same manner as in Example 1.
Using the charge / discharge device (ACD-01) manufactured by Asuka Electronics, the prepared lithium ion capacitor was charged to 4.0 V with a current of 1 mA, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed. Done for hours. Subsequently, the battery was discharged to 2.0 V with a constant current of 1 mA. The capacity per active material weight of the electrode was 162 F / g, and the volume capacity was 58 F / cm ³ , which was a low value.
Next, when the same charge was performed and the battery was discharged to 2.0 V at 100 mA, the ratio of the discharge capacity at 100 mA to the discharge capacity at 1 mA was as good as 87%.
When the cycle retention rate was evaluated in the same manner as in Example 1, it was 85%.
Moreover, when the single electrode cell was produced and evaluated by the same method as Example 1, the discharge capacity from 3.2V to 2.2V was compared with the discharge capacity from 4.2V to 2.2V. The ratio was 0.44.

<Example 15>
(Preparation of positive electrode)
Using the activated carbon used in Example 8, a slurry was produced with the same composition as in Example 1. Next, the obtained active material layer was applied to one side and both sides of a 15 μm thick aluminum foil having a conductive layer applied to the surface and dried. Basis weight of the electrode active material layer is 24 g / ^{m 2} on one surface coating ^electrode, 48 g / ^{m 2} huge bulk density in a double side coating electrode was 0.29 g / cm ^3.
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurizing at 30 μm, the bulk density of the electrode active material layer was 0.44 g / cm ³ for both single-sided and double-sided coated electrodes. The pressing speed was 5 m / min.
(Preparation of negative electrode)
The same slurry as the negative electrode produced in Example 14 was applied to both sides of the etched copper foil having through-holes, dried, and pressed to obtain a negative electrode having a negative electrode active material layer thickness of 60 μm. A negative electrode was produced by pre-doping a total of 1605 mAh / g of lithium ions with respect to the weight of the composite porous material.

(Preparation of separator)
As a pure polymer, homopolymers of polyethylene having Mv of 250,000 and 700,000 were prepared in a weight ratio of 50:50, respectively. To 99% by mass of the pure polymer, 1.0% by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is added as an antioxidant, and a tumbler blender is used. By using and dry blending, a polymer mixture was obtained. The obtained mixture of polymers and the like was fed by a feeder under a nitrogen atmosphere to a twin-screw extruder in which the system was purged with nitrogen. Further, liquid paraffin as a plasticizer was injected into the cylinder of the extruder by a plunger pump. Feeder and pump so that the amount ratio of liquid paraffin in the total mixture extruded and melt-kneaded by a twin screw extruder is 68% by mass (that is, the amount ratio of the polymer mixture (PC) is 32% by mass). Adjusted. The melt kneading conditions were a set temperature of 200 ° C., a screw rotation speed of 100 rpm, and a discharge rate of 12 kg / hour.
Subsequently, the obtained melt-kneaded product was extruded through a T-die onto a cooling roll controlled at a surface temperature of 40 ° C. and cast to obtain a gel sheet having a thickness of 1600 μm.
Next, the obtained gel sheet was guided to a simultaneous biaxial tenter stretching machine, and biaxial stretching was performed to obtain a stretched sheet. The set stretching conditions were an MD draw ratio of 7.0 times, a TD draw ratio of 6.1 times, and a set temperature of 121 ° C.
Next, the stretched sheet was introduced into a methyl ethyl ketone bath and sufficiently immersed in methyl ethyl ketone to extract and remove liquid paraffin from the stretched sheet, and then the methyl ethyl ketone was removed by drying.
Next, the stretched sheet from which methyl ethyl ketone was removed by drying was guided to a TD tenter and heat-set. The heat setting temperature was 121 ° C., the TD maximum magnification was 2.0 times, and the relaxation rate was 0.90 times. The evaluation results of various properties of the microporous membrane separator 1 thus obtained are shown in Table 1 below together with the composition.

(Preparation of electrolyte)
A solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a mass ratio of 1: 4 was used as an electrolytic solution.

(Assembly of capacitor)
The obtained single-sided positive electrode, double-sided positive electrode, and double-sided negative electrode body were cut into 100 mm × 100 mm. Next, the single-sided positive electrode body is used for the uppermost surface and the lowermost surface, and the intermediate portion is formed by alternately laminating 20 double-sided negative electrode bodies and 19 double-sided positive electrode bodies through the microporous membrane separator, Electrode terminals were connected to the negative electrode body and the positive electrode body to form an electrode laminate. The electrode laminate was inserted into an outer package made of a laminate film, and the electrolyte was injected with the end of the electrode terminal pulled out to seal the outer package, and a lithium ion capacitor was assembled.
At this time, the dimension of the separator is such that the area of the positive electrode active material layer of the positive electrode body or the area of the negative electrode of the negative electrode active material layer of the negative electrode body and the area of the separator are (separator area). )> (Electrode area), and in any straight line parallel to the first direction of the separator in the above-described top view, the electrode area and the separator overlap in the arbitrary straight line. the length of the portion as a, _{'when a, L} 1, L _1' the length of the portion in which the electrode area and the separator do not overlap L _1, L 1 either shortest such optional straight L ₁ or L ₁ ′ of the following formula (3):
X ¹ = (L ₁ or L ₁ ′ / (A / 2)) × 100
B and X ¹ obtained by substituting, in top view, in an arbitrary straight line as the second parallel to the direction of the separator, the length of the portion and the electrode area and the separator in the arbitrary straight line overlaps and then, the electrodes _'when a, L _{2, L 2'} area and the length of the portion the separator do not overlap L _2, L 2 arbitrary straight line of L ₂ or any such is the shortest of the L ₂ 'In the following formula (4):
X ² = (L ₂ or L ₂ ′ / (A / 2)) × 100
X ² determined by substituting for was 1.0.

[Heating test and characteristic evaluation]
A heating test of the fabricated capacitor was performed. The battery was charged to 4.0 V at a current value of 2 C, and then a constant current and constant voltage charge for applying a constant voltage of 4.0 V was performed for 2 hours. Next, a thermocouple was affixed to the center of one surface of the capacitor with a polyimide tape, sandwiched between metal plates, wound with a ribbon heater, used as a heating medium, and set in a thermostatic chamber in an atmospheric atmosphere. The temperature rise rate of the ribbon heater was 5 ° C./min, and the voltage and temperature of the capacitor were measured. The short-circuit start temperature was 128 ° C., and the complete short-circuit temperature was 138 ° C. When the temperature exceeded 200 ° C., the capacitor was opened without rupture and ignition, and almost no gas injection was observed, indicating a safe change.
The manufactured capacitor is charged to 3.8 V by constant current constant voltage charging that can secure a constant voltage charging time of 1 hour at a current value of 1.5 C, and constant current discharge is also performed at a current value of 1.5 C up to 2.2 V. gave. From the capacitance and voltage change at that time, it was found that the capacitance of this capacitor was 1320F.
The produced capacitor was evaluated in an environment of 25 ° C. The battery was charged to 4.0 V with a current amount of 1 C, and then subjected to constant current constant voltage charging in which a constant voltage of 4.0 V was applied for 2 hours. Subsequently, the battery was discharged to 2.0 V with a current amount of 1C. Next, after charging for 2 hours, the battery was discharged to 2.0 V at a current value of 300C. The ratio of the discharge capacity at 300 C to the discharge capacity at 1 C was 82%. Next, the characteristics were evaluated in an environment of −20 ° C. The same charge as above was performed, and the battery was discharged to 2.0 V with a current amount of 200C. The ratio of the discharge capacity at 200 C at −20 ° C. to the discharge capacity at 1 C at 25 ° C. was 58%.

<Example 16>
(Preparation of positive electrode)
Using the activated carbon used in Example 8, a slurry was produced with the same composition as in Example 1. Next, the obtained active material layer was applied to one side and both sides of a 15 μm thick aluminum foil having a conductive layer applied to the surface and dried. Basis weight of the electrode active material layer is 24 g / ^{m 2} on one surface coating ^electrode, 48 g / ^{m 2} huge bulk density in a double side coating electrode was 0.29 g / cm ^3.
The electrode coated with the active material layer was installed in a heated press roll apparatus in the same manner as in Example 1, and the distance between the rolls was 60 μm at the first time and the second time at a linear pressure of 120 kgf / cm with a heated press roll heated to 140 ° C. Pressurizing at 30 μm, the bulk density of the electrode active material layer was 0.44 g / cm ³ for both single-sided and double-sided coated electrodes. The pressing speed was 5 m / min.
(Preparation of negative electrode)
The same slurry as the negative electrode produced in Example 14 was applied to both sides of the etched copper foil having through-holes, dried, and pressed to obtain a negative electrode having a negative electrode active material layer thickness of 60 μm. A negative electrode was produced by pre-doping a total of 1605 mAh / g of lithium ions with respect to the weight of the composite porous material.

(Preparation of separator)
Separator 2 (inorganic film)
As the pure polymer, polyethylene homopolymers having Mv of 250,000 and 700,000 were prepared in a weight ratio of 50:50, respectively. To 99% by mass of the pure polymer, 1.0% by mass of pentaerythrityl-tetrakis- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] is added as an antioxidant, and a tumbler blender is used. By using and dry blending, a polymer mixture was obtained. The obtained mixture of polymers and the like was fed by a feeder under a nitrogen atmosphere to a twin-screw extruder in which the system was purged with nitrogen. Further, liquid paraffin as a plasticizer was injected into the cylinder of the extruder by a plunger pump. Feeder and pump are adjusted so that the ratio of liquid paraffin in the total mixture to be extruded is 68% by mass (that is, the ratio of mixture of polymers (PC) is 32% by mass). did. The melt kneading conditions were a set temperature of 200 ° C., a screw rotation speed of 100 rpm, and a discharge rate of 12 kg / hour.
Subsequently, the obtained melt-kneaded product was extruded through a T-die onto a cooling roll controlled at a surface temperature of 40 ° C. and cast to obtain a gel sheet having a thickness of 1600 μm.
Next, the obtained gel sheet was guided to a simultaneous biaxial tenter stretching machine and biaxially stretched to obtain a stretched sheet. The set stretching conditions were an MD draw ratio of 7.0 times, a TD draw ratio of 6.1 times, and a set temperature of 121 ° C.
Next, the stretched sheet was introduced into a methyl ethyl ketone bath and sufficiently immersed in methyl ethyl ketone to extract and remove liquid paraffin from the stretched sheet, and then the methyl ethyl ketone was removed by drying.
Next, the stretched sheet from which methyl ethyl ketone was removed by drying was guided to a TD tenter and heat-set. The heat setting temperature was 121 ° C., the TD maximum magnification was 2.0 times, and the relaxation rate was 0.90 times. The obtained polyolefin porous film had a thickness of 16 μm, a porosity of 65%, a pore diameter of 0.05 μm, and a number of holes of 190 / μm ² .
Next, a coating liquid in which insulating alumina particles are dispersed is applied to one side of the obtained polyolefin porous film using a micro gravure coater, and dried at 60 ° C. to form an insulating porous film having a thickness of 5 μm on the polyolefin porous film. Formed. The coating solution was 96.0 parts by mass of alumina whose particle size was adjusted with a bead mill so that the average particle size (Dp50) was 1.0 μm, and acrylic latex (solid content concentration 40%, average particle size 145 nm as a resin binder). ) 4.0 parts by mass and 1.0 part by mass of an aqueous solution of ammonium polycarboxylate (SN Dispersant 5468 manufactured by San Nopco) were uniformly dispersed in 100 parts by mass of water and prepared.

(Preparation of electrolyte)
A solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were mixed at a mass ratio of 1: 4 was used as an electrolytic solution.
(Assembly of capacitor)
The obtained single-sided positive electrode body, double-sided positive electrode body, and double-sided negative electrode body were cut into 100 mm × 100 mm. Next, the single-sided positive electrode body is used for the uppermost surface and the lowermost surface, and the intermediate portion is formed by alternately stacking 20 double-sided negative electrode bodies and 19 double-sided positive electrode bodies with the microporous membrane separator 1 interposed therebetween. Electrode terminals were connected to the negative electrode body and the positive electrode body to form an electrode laminate. The electrode laminate was inserted into an outer package made of a laminate film, and the electrolyte was injected with the end of the electrode terminal pulled out to seal the outer package, and a lithium ion capacitor was assembled.

(Characteristic evaluation)
The produced capacitor was evaluated in an environment of 25 ° C. The battery was charged to 4.0 V with a current amount of 1 C, and then subjected to constant current constant voltage charging in which a constant voltage of 4.0 V was applied for 2 hours. Subsequently, the battery was discharged to 2.0 V with a current amount of 1C. Next, after charging for 2 hours, the battery was discharged to 2.0 V at a current value of 300C. The ratio of the discharge capacity at 300 C to the discharge capacity at 1 C was 78%. Next, the characteristics were evaluated in an environment of −20 ° C. The same charge as above was performed, and the battery was discharged to 2.0 V with a current amount of 200C. The ratio of the discharge capacity at 200 C at −20 ° C. to the discharge capacity at 1 C at 25 ° C. was 49%.
Further, as a durability test, a cycle test in which a constant current charge and a constant current discharge were repeated from 25 V to a voltage range of 2.0 V to 4.0 V at a current amount of 300 C at 25 ° C. was performed. The capacity maintenance rate after the elapse of 100,000 cycles with respect to the start of the test (10th cycle) at a current amount of 300 C was measured. The capacity maintenance rate here is a numerical value represented by {(discharge capacity after 100,000 cycles have passed) / (discharge capacity at the 10th cycle)} × 100. The capacity retention rate after the elapse of 100,000 cycles was 88%.

(Nail penetration test)
Testing machine: Shimadzu Autograph AG-X
Nail: φ2.5mm-SUS304
Evaluation: As shown in FIG. 6, the cell (3) was fixed horizontally, and pierced at the nail penetration position (8) at the center of the cell until it penetrated the nail at a speed of 10 mm / sec. The temperature was measured with a thermocouple attached to the temperature measurement position (6, 7), and the maximum temperature was determined. In addition, the amount of generated gas and smoke was observed, and the opening of the capacitor was observed. As a result, the maximum temperature of the laminate was 52 ° C., there was no gas generation and smoke generation, and the laminate was not opened. In FIG. 6, the heat seal portion (9) does not contain an electrode body or an electrolytic solution.

  The power storage element using the negative electrode material for a power storage element of the present invention is suitable for automobiles, in the field of hybrid drive systems combining an internal combustion engine or a fuel cell, a motor, and a power storage element, and for assisting instantaneous power peak. Available.

(Reference in FIG. 1)
7 Positive electrode terminal 8 Negative electrode terminal 9 Exterior body 10 Electrode body 11 Positive electrode current collector 12 Positive electrode active material layer 13 Separator 14 Negative electrode current collector 15 Negative electrode active material layer 16 Positive electrode 17 Negative electrode (reference numeral in FIG. 2)
1 Winding roll 2 Guide 3 Heating press roll 4 Winding roll 5 Hydraulic cylinder 6 Positive electrode (reference numeral in FIG. 3)
A The length of the portion where the electrode area and the separator overlap in the arbitrary straight line parallel to the first direction of the separator L1 The electrode area and the length of the portion where the separator does not overlap L1 ′ The electrode area and the separator 1 Separator 2 Current collector (active electrode) of electrode 32, whichever is greater of the area of the positive electrode active material layer of the positive electrode body or the negative electrode area of the negative electrode active material layer of the negative electrode body The part where the substance layer is not applied)
(Reference in FIG. 4)
Width of separator protruding from L ₁ electrode Width of separator protruding from L ₂ electrode Width of separator protruding from L ₃ electrode Width of separator protruding from L ₄ electrode A ₁ electrode width A ₂ electrode width (reference numeral in FIG. 5)
1 Polyolefin porous membrane 2 Insulating porous membrane (symbol in FIG. 6)
3 cell 4 positive electrode terminal 5 negative electrode terminal 6 temperature measurement position 7 temperature measurement position 8 nail penetration position 9 heat seal part

Claims (12)

The amount of mesopores V1 (cc / g) derived from pores having a BET specific surface area of 2600 m ² / g to 4500 m ² / g and a diameter of 20 mm to 500 mm calculated by the BJH method is 0.8 <V1 ≦ The micropore amount V2 (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method is 0.92 <V2 ≦ 3.0, and the average particle size is 1 μm or more and 30 μm or less. And an active material used for an electrode of a non-aqueous lithium storage element, characterized by having a sphericity of 0.80 or more. The amount of mesopores V1 (cc / g) derived from pores having a BET specific surface area of 2600 m ² / g to 4500 m ² / g and a diameter of 20 mm to 500 mm calculated by the BJH method is 0.8 <V1 ≦ 2.5, the amount of micropores V2 (cc / g) derived from pores having a diameter of less than 20 mm calculated by the MP method is 0.92 <V2 ≦ 3.0, and the average particle size is 1 μm or more includes a positive electrode active material is 30μm or less, the bulk density of the active material layer containing a positive electrode active material is not more than 0.40 g / cm ³ or more 0.70 g / cm ^3, and the active material layer, positive electrode A positive electrode for a non-aqueous lithium storage element, comprising a positive electrode active material having a roundness of 0.80 or more in a cross section obtained when the active material layer is cut perpendicularly to the thickness direction of the electrode.   In the cross section obtained when the positive electrode active material layer is cut perpendicularly to the thickness direction of the electrode, the total cross-sectional area of the positive electrode active material having a roundness of 0.80 or more is equal to the total positive electrode active material in the electrode cross section. The positive electrode for a non-aqueous lithium storage element according to claim 2, wherein the positive electrode is 50% or more with respect to the total cross-sectional area.   An electrode body comprising the positive electrode according to claim 2, a separator, and a negative electrode including negative electrode active material particles; a non-aqueous electrolyte containing lithium ions; and a non-aqueous lithium type having an exterior body Power storage element. The non-aqueous lithium storage element according to claim 4, wherein the positive electrode active material is activated carbon having a BET specific surface area of 3000 m ² / g or more and 4000 m ² / g or less. The negative electrode active material included in the negative electrode includes a composite porous material in which pitch charcoal is deposited on the surface of activated carbon, and the following i) and ii):
i) The weight ratio of the pitch charcoal to the activated carbon is 10% or more and 60% or less, and the pitch softening point of the pitch charcoal is 100 ° C. or less; and ii) the negative electrode active material is BET specific surface area of 350m ² / g~1500m ² / g, and lithium ions, have been 1100mAh / g~2000mAh / g doped per unit weight;
The non-aqueous lithium storage element according to claim 4 or 5, wherein The negative electrode active material includes a composite porous material in which pitch charcoal is deposited on the surface of activated carbon, and the composite porous material is a mesopore derived from pores having a diameter of 20 to 500 mm calculated by the BJH method. When the amount is Vm1 (cc / g) and the amount of micropores derived from pores having a diameter of less than 20 mm calculated by the MP method is Vm2 (cc / g), the following I) to III):
I) 0.010 ≦ Vm1 ≦ 0.300 and 0.010 ≦ Vm2 ≦ 0.200;
II) 0.010 ≦ Vm1 ≦ 0.200 and 0.200 ≦ Vm2 ≦ 0.400; and III) 0.010 ≦ Vm1 ≦ 0.100 and 0.400 ≦ Vm2 ≦ 0.650;
The non-aqueous lithium storage element according to any one of claims 4 to 6, satisfying at least one of the following.   The negative electrode active material has a mesopore volume Vm1 (cc / g) derived from pores having a diameter of 20 mm or more and 500 mm or less calculated by the BJH method of 0.001 ≦ Vm1 <0.01, and calculated by the MP method. 6. The non-aqueous lithium according to claim 4, comprising a non-graphitizable carbon material in which the micropore amount Vm2 (cc / g) derived from pores having a diameter of less than 20 mm is 0.001 ≦ Vm2 <0.01. Type storage element. A positive electrode for a non-aqueous lithium storage element including a positive electrode active material layer containing particles of a positive electrode active material, wherein the current density is 1 mA in a single electrode cell using the positive electrode as an anode and metallic lithium as a cathode and a reference electrode. When charging / discharging in the range of / cm ² and anode potential of 2.2 to 4.2 V, the ratio of 2.2 to 3.2 V discharge capacity in the 2.2 to 4.2 V discharge capacity is 0.43 or more. The positive electrode active material has an average particle size of 1 μm or more and 30 μm or less, and the positive electrode active material layer containing the positive electrode active material has a bulk density of 0.40 g / cm ³ or more and 0.70 g / cm ³ or less, and The positive electrode active material layer includes particles of a positive electrode active material having a roundness of 0.80 or more in a cross section obtained by cutting the positive electrode active material layer perpendicularly to the thickness direction of the electrode. Positive electrode for device. When the separator is kept at 100 ° C. for 1 hour in an unconstrained state, the thermal contraction rate of the separator is 3% or more and 10% or less in the first direction, and is orthogonal to the first direction. 2% to 10% in the second direction
The area of the positive electrode active material layer of the positive electrode or the area of the negative electrode of the negative electrode active material layer of the negative electrode and the area of the separator have a relationship of (separator area)> (electrode area). ,And,
In an arbitrary straight line parallel to the first direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap in the arbitrary straight line is A, and the electrode area and the separator overlap. When the length of the part that does not become L1 and L1 ′, L1 or L1 ′ of an arbitrary straight line in which either L1 or L1 ′ is the shortest is expressed by the following formula (3):
X1 = (L1 or L1 ′ / (A / 2)) × 100
X1 obtained by substituting
In an arbitrary straight line parallel to the second direction of the separator in a top view, the length of the portion where the electrode area and the separator overlap on the arbitrary straight line is defined as B, and the electrode area and the separator overlap. When the length of the part that does not become L2 and L2 ′, L2 or L2 ′ of an arbitrary straight line in which either L2 or L2 ′ is the shortest is expressed by the following formula (4):
X2 = (L2 or L2 ′ / (A / 2)) × 100
X2 obtained by substituting for each is 0.5 or more and 8.0 or less.
The non-aqueous lithium storage element according to any one of claims 4 to 8.   The nonaqueous lithium according to any one of claims 4 to 8, wherein the separator is a laminated separator obtained by laminating a polyolefin porous film and an insulating porous film, and the insulating porous film is in contact with the negative electrode. Type storage element.   The non-aqueous lithium according to claim 11, wherein a thickness of the polyolefin porous film of the laminated separator is 5 μm or more and 35 μm or less, and a ratio of the thickness of the insulating porous film to the polyolefin porous film is 0.25 to 1.00. Type storage element.