JP6815126B2 - Non-aqueous lithium storage element - Google Patents

Description

The present invention relates to a non-aqueous lithium storage element.

In recent years, from the viewpoint of effective use of energy aiming at conservation of the global environment and resource saving, power smoothing system or midnight power storage system for wind power generation, distributed power storage system for home use based on solar power generation technology, power storage for electric vehicles Systems and the like are attracting attention.
The first requirement of the batteries used in these power storage systems is high energy density. Lithium-ion batteries are being energetically developed as promising candidates for high-energy density batteries that can meet such demands.
The second requirement is high output characteristics. For example, in 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), high output discharge characteristics in the power storage system are required during acceleration. There is.

Currently, electric double layer capacitors, nickel-metal hydride batteries, and the like are being developed as high-power power storage devices.
Among the electric double layer capacitors, those using activated carbon for the electrodes have an output characteristic of about 0.5 to 1 kW / L. This electric double layer capacitor has high durability (cycle characteristics and high temperature storage characteristics), and has been considered to be the most suitable device in the field where high output is required. However, its energy density is only about 1 to 5 Wh / L. Therefore, it is necessary to further improve the energy density.

On the other hand, the nickel-metal hydride battery currently used in hybrid electric vehicles has a high output equivalent to that of an electric double layer capacitor and an energy density of about 160 Wh / L. However, research is being vigorously pursued to further increase its energy density and output and to improve its durability (particularly, stability at high temperatures).

In addition, research is underway to increase the output of lithium-ion batteries. For example, a lithium ion battery has been developed in which a high output exceeding 3 kW / L can be obtained at a discharge depth (a value indicating what percentage of the discharge capacity of the power storage element is discharged) of 50%. However, its energy density is 100 Wh / L or less, and the design is such that the high energy density, which is the greatest feature of the lithium ion battery, is intentionally suppressed. Moreover, its durability (cycle characteristics and high temperature storage characteristics) is inferior to that of electric double layer capacitors. Therefore, in order to have practical durability, it is used in a range where the discharge depth is narrower than the range of 0 to 100%. Since the capacity that can be actually used becomes smaller, research for further improving durability is being vigorously pursued.

As described above, there is a strong demand for practical use of a power storage element having high energy density, high output characteristics, and durability. However, each of the existing power storage elements described above has advantages and disadvantages. Therefore, a new power storage element that satisfies these technical requirements is required. As a promising candidate, a power storage element called a lithium ion capacitor has attracted attention and is being actively developed.

The energy of the capacitor is represented by 1/2 · C · V ² (where C is capacitance and V is voltage). A lithium ion capacitor is a type of power storage element (non-aqueous lithium type power storage element) that uses a non-aqueous electrolyte solution containing a lithium salt. -A power storage element that charges and discharges by a non-Faraday reaction by desorption and a Faraday reaction by the storage and release of lithium ions at the negative electrode, similar to a lithium ion battery.

To summarize the above-mentioned electrode materials and their characteristics, high output and high durability are achieved when a material such as activated carbon is used for the electrodes and charging / discharging is performed by adsorption / desorption (non-Faraday reaction) of ions on the surface of activated carbon. However, the energy density becomes low (for example, it is multiplied by 1). On the other hand, when an oxide or carbon material is used for the electrode and charging / discharging is performed by the Faraday reaction, the energy density becomes high (for example, 10 times that of the non-Faraday reaction using activated carbon), but the durability and output are increased. There is a problem with the characteristics.
As a combination of these electrode materials, the electric double layer capacitor is characterized by using activated carbon (energy density 1 times) for the positive electrode and the negative electrode and charging / discharging both the positive electrode and the negative electrode by a non-Faraday reaction, and has high output and high durability. However, it is characterized by low energy density (1x positive electrode x 1x negative electrode = 1).

The lithium ion secondary battery is characterized by using a lithium transition metal oxide (energy density 10 times) for the positive electrode and a carbon material (energy density 10 times) for the negative electrode, and charging and discharging both the positive electrode and the negative electrode by a Faraday reaction. Although the energy density (positive electrode 10 times x negative electrode 10 times = 100), there are problems in output characteristics and durability. Further, in order to satisfy the high durability required for a hybrid electric vehicle or the like, the discharge depth must be limited, and the lithium ion secondary battery can use only 10 to 50% of its energy.

Lithium-ion capacitors use activated carbon (1x energy density) for the positive electrode and carbon material (10x energy density) for the negative electrode, and are characterized by performing charging and discharging by a non-Faraday reaction at the positive electrode and a Faraday reaction at the negative electrode. It is a new asymmetric capacitor that combines the characteristics of a multi-layer capacitor and a lithium-ion secondary battery. The feature is that it has high energy density (1x positive electrode x 10x negative electrode = 10) while having high output and high durability, and it is not necessary to limit the discharge depth unlike a lithium ion secondary battery. is there.

In the lithium ion capacitor, the negative electrode is pre-doped with lithium in advance to achieve both excellent input / output characteristics and high energy density. Various methods have been proposed as this pre-doping method. The fastest and most reliable method of supplying lithium ions to the negative electrode active material is to attach metallic lithium to the surface of the negative electrode active material layer and inject a non-aqueous electrolyte solution.

Specifically, for example, the following method has been proposed as a pre-doping method using this metallic lithium.
The following Patent Document 1 proposes a method in which a metallic lithium foil is pressure-bonded to an active material layer of a negative electrode using a negative electrode current collector made of a copper foil having through holes and pre-doped.
Further, Patent Document 2 below proposes a method in which the positive electrode current collector and the negative electrode current collector are provided with through holes and the negative electrode is pre-doped by electrochemical contact with the positive electrode or the lithium metal facing the negative electrode. .. However, in these methods, it is possible to uniformly pre-dope the negative electrode with lithium ions, but there is a problem that the metal resistance of the current collector is increased by providing a through hole in the negative electrode current collector, and lithium metal is used. There is a problem that it is easy to precipitate.

Further, Patent Document 3 below proposes a method in which a non-porous metal foil is used for the positive electrode current collector and the negative electrode current collector, and metallic lithium is placed on the side surface of the negative electrode active material to predope. However, this method has a problem that lithium ions cannot be uniformly pre-doped into the negative electrode because the diffusion of lithium ions in the negative electrode is very slow.

Further, Patent Document 4 below proposes a method of oxidizing various lithium compounds as oxides at the positive electrode to recover the capacity of the deteriorated power storage element. However, in this method, since the lithium compound is present inside the positive electrode in the state before deterioration, the electric conductivity of the positive electrode is lowered, and the diffusion of ions in the electrolytic solution retained in the positive electrode is diffused. There is a problem that the internal resistance of the power storage element increases due to the inhibition. Furthermore, there is room for further improvement in high temperature durability and high load charge / discharge cycle characteristics.

Japanese Patent No. 4738042 International Publication No. 98-033227 Japanese Unexamined Patent Publication No. 2011-238885 Japanese Patent No. 5278467

In view of the current state of the art, an object to be solved by the present invention is to provide a non-aqueous lithium storage element exhibiting high initial input / output characteristics, excellent high temperature durability, and charge / discharge cycle characteristics. ..

The present inventors, the problems intensive studies to solve the result of repeated experiments, coverage of lithium carbonate in the positive electrode, and a number average particle diameter of the number-average particle diameter X ₁ and the positive electrode active material of lithium carbonate particles It has been found that the initial input / output characteristics and the charge / discharge cycle characteristics are remarkably improved by appropriately controlling Y ₁ , and the present invention has been completed.
That is, the present invention is as follows.

｛式（１）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝、

｛式（２）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２は水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝、

｛式（３）中、Ｒ^１は、炭素数１〜４のアルキレン基、炭素数１〜４のハロゲン化アルキレン基であり、Ｒ^２、Ｒ^３はそれぞれ独立に水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝からなる群から選択される１種以上の化合物を、該正極物質層の単位質量当たり１．６０×１０^−４ｍｏｌ／ｇ〜３００×１０^−４ｍｏｌ／ｇで含有する、前記［１］〜［５］のいずれかに記載の前記非水系リチウム型蓄電素子。
［７］前記正極活物質層に含まれる正極活物質が、ＢＪＨ法により算出した直径２０Å以上５００Å以下の細孔に由来するメソ孔量をＶ１（ｃｃ／ｇ）、ＭＰ法により算出した直径２０Å未満の細孔に由来するマイクロ孔量をＶ２（ｃｃ／ｇ）とするとき、０．３＜Ｖ１≦０．８、及び０．５≦Ｖ２≦１．０を満たし、かつ、ＢＥＴ法により測定される比表面積が１，５００ｍ^２／ｇ以上３，０００ｍ^２／ｇ以下を示す活性炭である、前記［１］〜［６］のいずれかに記載の非水系リチウム型蓄電素子。
［８］前記正極活物質層に含まれる正極活物質が、ＢＪＨ法により算出した直径２０Å以上５００Å以下の細孔に由来するメソ孔量Ｖ１（ｃｃ／ｇ）が０．８＜Ｖ１≦２．５を満たし、ＭＰ法により算出した直径２０Å未満の細孔に由来するマイクロ孔量Ｖ２（ｃｃ／ｇ）が０．８＜Ｖ２≦３．０を満たし、かつ、ＢＥＴ法により測定される比表面積が２，３００ｍ^２／ｇ以上４，０００ｍ^２／ｇ以下を示す活性炭である、前記［１］〜［６］のいずれかに記載の非水系リチウム型蓄電素子。
［９］前記負極活物質のリチウムイオンのドープ量が、単位質量当たり５３０ｍＡｈ／ｇ以上２，５００ｍＡｈ／ｇ以下である、前記［１］〜［８］のいずれかに記載の非水系リチウム型蓄電素子。
［１０］前記負極活物質のＢＥＴ比表面積が１００ｍ^２／ｇ以上１，５００ｍ^２／ｇ以下である、前記［１］〜［９］のいずれかに記載の非水系リチウム型蓄電素子。 [1] A non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. Contains a carbon material that can be released,
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle diameter of the lithium carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle diameter of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. Moreover, the non-aqueous lithium-type power storage element in which X ₁ <Y ₁ is satisfied.
[2] The non-aqueous lithium according to the above [1], wherein the area ratio of carbonate ion mapping to the cross-sectional area is 2% or more and 20% or less in the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode. Type storage element.
[3] The above-mentioned [1] or [2], wherein the amount of lithium carbonate contained in the positive electrode is 2.5% by mass or more and 30% by mass or less based on the total mass of the positive electrode active material layer. Non-aqueous lithium storage element.
[4] In the element mapping obtained by SEM-EDX on the surface of the positive electrode, the area overlap rate of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is 30% or more and 99% or less. The non-aqueous lithium-type power storage element according to any one of [1] to [3].
[5] In the element mapping obtained by SEM-EDX of the cross section obtained by BIB processing the positive electrode, the area overlap rate of fluorine mapping with respect to oxygen mapping binarized based on the average value of brightness is 10% or more and 65% or less. The non-aqueous lithium-type power storage element according to any one of the above [1] to [4].
[6] The positive electrode active material layer has the following formulas (1) to (3):

{In formula (1), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here). , N is 0 or 1.). },

{In the formula (2), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 carbon atom. A mono or polyhydroxyalkyl group having 10 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a mono or polyhydroxyalkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, X ¹ , X ² are independently − (COO) _n (where n is 0 or 1). },

{In formula (3), R ¹ is an alkylene group having 1 to 4 carbon atoms and a halogenated alkylene group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and having 1 to 10 carbon atoms, respectively. Alkyl group, mono or polyhydroxyalkyl group with 1 to 10 carbon atoms, alkenyl group with 2 to 10 carbon atoms, mono or polyhydroxyalkenyl group with 2 to 10 carbon atoms, cycloalkyl group with 3 to 6 carbon atoms, or aryl It is a group, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1). One or more compounds selected from the group consisting of}, containing at × ¹⁰ 1.60 per unit mass of the positive electrode material layer ^{-4 mol / g~300 × 10 -4 mol} / g, the [1] The non-aqueous lithium-type power storage element according to any one of [5].
[7] The amount of mesopores derived from the pores of the positive electrode active material contained in the positive electrode active material layer having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the diameter is 20 Å calculated by the MP method. When the amount of micropores derived from pores less than is V2 (cc / g), 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the measurement is performed by the BET method. The non-aqueous lithium-type power storage element according to any one of [1] to [6] above, which is an activated carbon having a specific surface area of 1,500 m ² / g or more and 3,000 m ² / g or less.
[8] The amount of mesopores V1 (cc / g) of the positive electrode active material contained in the positive electrode active material layer derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is 0.8 <V1 ≦ 2. The specific surface area measured by the BET method while satisfying 5 and the micropore amount V2 (cc / g) derived from pores having a diameter of less than 20 Å calculated by the MP method satisfies 0.8 <V2 ≦ 3.0. The non-aqueous lithium-type power storage element according to any one of [1] to [6] above, which is an activated carbon exhibiting 2,300 m ² / g or more and 4,000 m ² / g or less.
[9] The non-aqueous lithium-type storage device according to any one of [1] to [8] above, wherein the amount of lithium ion doped in the negative electrode active material is 530 mAh / g or more and 2,500 mAh / g or less per unit mass. element.
[10] The non-aqueous lithium power storage element according to any one of [1] to [9], wherein the negative electrode active material has a BET specific surface area of 100 m ² / g or more and 1,500 m ² / g or less.

[11] The non-aqueous lithium-type power storage element according to any one of [1] to [8], wherein the amount of lithium ions doped in the negative electrode active material is 50 mAh / g or more and 700 mAh / g or less per unit mass.
[12] The non-aqueous lithium-type power storage element according to any one of [1] to [8] and [11], wherein the negative electrode active material has a BET specific surface area of 1 m ² / g or more and 50 m ² / g or less. ..
[13] The non-aqueous lithium power storage device according to any one of [1] to [8], [11], and [12], wherein the negative electrode active material has an average particle size of 1 μm or more and 10 μm or less.
[14] A non-aqueous lithium-type power storage device including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector.
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle diameter of the carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle diameter of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. In addition, X ₁ <Y ₁ and in the non-aqueous lithium type power storage element, the initial internal resistance at a cell voltage of 4 V is Ra (Ω), the capacitance is F (F), and the amount of power is E (Wh). , When the volume of the power storage element is V (L), the following:
(A) The product Ra / F of Ra and F is 0.3 or more and 3.0 or less;
(B) E / V is 15 or more and 50 or less;
The non-aqueous lithium power storage element, which is characterized by simultaneously satisfying.
[15] A non-aqueous lithium-type power storage device including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector.
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle size of the carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle size of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. In addition, X ₁ <Y ₁ and after storing the initial internal resistance at a cell voltage of 4 V for 2 months at Ra (Ω), a cell voltage of 4 V, and an ambient temperature of 60 ° C. in the non-aqueous lithium type power storage element. After performing 60,000 charge / discharge cycles at a rate of 300 C with a cell voltage of 2.2 V to 3.8 V at an internal resistance of Rb (Ω) and an ambient temperature of 25 ° C. at a cell voltage of 4 V. When the internal resistance is Rc (Ω), the following:
(C) Rb / Ra is 3.0 or less;
(D) The amount of gas generated when stored for 2 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 25 × 10 ^-3 cc / F or less at 25 ° C.;
(E) Rc / Ra is 0.9 or more and 2.0 or less;
The non-aqueous lithium-type power storage element, which is characterized by simultaneously satisfying.

The non-aqueous lithium-type power storage element according to the present invention has excellent initial input / output characteristics, high energy density, high load charge / discharge cycle characteristics, and high temperature storage durability.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.
[Storage element]
The power storage element according to the present embodiment includes a positive electrode, a negative electrode, a separator, and a non-aqueous electrolytic solution containing lithium ions. The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector. The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon, which is provided on one side or both sides of the positive electrode current collector.

Hereinafter, the components of the positive electrode body and the negative electrode body of the present embodiment and the manufacturing method will be described in order, and then the assembly, manufacturing method, and evaluation method of the power storage element will be described.
[Positive electrode]
The positive electrode has a positive electrode current collector and a positive electrode active material layer existing on one side or both sides thereof. Further, the positive electrode contains lithium carbonate as a positive electrode precursor before assembling the power storage element. As will be described later, in the present embodiment, it is preferable to pre-dope the negative electrode with lithium ions in the energy storage element assembling process, but the pre-doping method includes the positive electrode precursor containing lithium carbonate, the negative electrode, the separator, and the exterior body. , And after assembling the power storage element using the non-aqueous electrolyte solution, it is preferable to apply a voltage between the positive electrode precursor and the negative electrode. The lithium carbonate is preferably contained in the positive electrode active material layer formed on the positive electrode current collector of the positive electrode precursor.
In the present specification, the positive electrode state before the lithium doping step is defined as a positive electrode precursor, and the positive electrode state after the lithium doping step is defined as a positive electrode.

[Positive electrode active material layer]
The positive electrode active material layer contains a positive electrode active material containing activated carbon. In addition to this, if necessary, an optional component such as a conductive filler, a binder, and a dispersion stabilizer may be contained.
Further, the positive electrode active material layer of the positive electrode precursor contains lithium carbonate.

[Positive electrode active material]
The positive electrode active material contains activated carbon. As the positive electrode active material, only activated carbon may be used, or in addition to activated carbon, other carbon materials as described later may be used in combination. As the carbon material, it is more preferable to use carbon nanotubes, a conductive polymer, or a porous carbon material. The positive electrode active material may be used by mixing one or more kinds of carbon materials including activated carbon, or may contain a material other than the carbon material (for example, a composite oxide of lithium and a transition metal).
The content of the carbon material with respect to the total amount of the positive electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material can be 100% by mass, but from the viewpoint of obtaining a good effect by using other materials in combination, for example, it is preferably 90% by mass or less, and 80% by mass or less. May be good.

When activated carbon is used as the positive electrode active material, there are no particular restrictions on the type of activated carbon and its raw material. However, it is preferable to optimally control the pores of the activated carbon in order to achieve both high input / output characteristics and high energy density. Specifically, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When setting to V2 (cc / g)
(1) For high input / output characteristics, 0.3 <V1 ≦ 0.8 and 0.5 ≦ V2 ≦ 1.0 are satisfied, and the specific surface area measured by the BET method is 1,500 m ² /. Activated carbon having a g or more and 3,000 m ² / g or less (hereinafter, also referred to as activated carbon 1) is preferable, and (2) in order to obtain a high energy density, 0.8 <V1 ≦ 2.5 and 0. Activated carbon (hereinafter, also referred to as activated carbon 2) that satisfies 8 <V2 ≦ 3.0 and has a specific surface area measured by the BET method of 2,300 m ² / g or more and 4,000 m ² / g or less is preferable.

Hereinafter, the activated carbon 1 and the activated carbon 2 will be described individually in sequence.
[Activated carbon 1]
The mesopore amount V1 of the activated carbon 1 is preferably a value larger than 0.3 cc / g in terms of increasing the input / output characteristics when the positive electrode material is incorporated into the power storage element. On the other hand, it is preferably 0.8 cc / g or less from the viewpoint of suppressing a decrease in the bulk density of the positive electrode. The above V1 is more preferably 0.35 cc / g or more and 0.7 cc / g or less, and further preferably 0.4 cc / g or more and 0.6 cc / g or less. The lower limit and the upper limit can be any combination.
The micropore amount V2 of the activated carbon 1 is preferably 0.5 cc / g or more in order to increase the specific surface area and the capacity of the activated carbon. On the other hand, it is preferably 1.0 cc / g or less from the viewpoint of suppressing the bulk of the activated carbon, increasing the density as an electrode, and increasing the capacity per unit volume. V2 is more preferably 0.6 cc / g or more and 1.0 cc / g or less, and further preferably 0.8 cc / g or more and 1.0 cc / g or less. The lower limit and the upper limit can be any combination.

The ratio of the mesopore amount V1 to the micropore amount V2 (V1 / V2) is preferably in the range of 0.3 ≦ V1 / V2 ≦ 0.9. That is, V1 / V2 is preferably 0.3 or more from the viewpoint of increasing the ratio of the mesopore amount to the micropore amount to the extent that the decrease in output characteristics can be suppressed while maintaining a high capacity. On the other hand, V1 / V2 is preferably 0.9 or less from the viewpoint of increasing the ratio of the micropore amount to the mesopore amount to the extent that the decrease in capacitance can be suppressed while maintaining the high output characteristics. A more preferable range of V1 / V2 is 0.4 ≦ V1 / V2 ≦ 0.7, and a more preferable range of V1 / V2 is 0.55 ≦ V1 / V2 ≦ 0.7. The lower limit and the upper limit can be any combination.

The average pore diameter of the activated carbon 1 is preferably 17 Å or more, more preferably 18 Å or more, and most preferably 20 Å or more from the viewpoint of maximizing the output of the obtained power storage element. Further, from the viewpoint of maximizing the capacity, the average pore diameter of the activated carbon 1 is preferably 25 Å or less.
BET specific surface area of the activated carbon 1 is preferably from 1,500 m ² / g or more 3,000 m ² / g, more preferably not more than 1,500 m ² / g or more 2,500 m ² / g. When the BET specific surface area is 1,500 m ² / g or more, good energy density can be easily obtained, while when the BET specific surface area is 3,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved. The lower limit and the upper limit can be any combination.

Activated carbon 1 having the above characteristics can be obtained, for example, by using the raw materials and treatment methods described below.
In the present embodiment, the carbon source used as the raw material of the activated carbon 1 is not particularly limited. For example, plant-based raw materials such as wood, wood flour, coconut shells, by-products during pulp production, bagas, waste sugar honey; peat, sub-charcoal, brown charcoal, bituminous charcoal, smokeless charcoal, petroleum distillation residue components, petroleum pitch, coke, coal tar, etc. Fossil raw materials; various synthetic resins such as phenol resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, resorcinol resin, celluloid, epoxy resin, polyurethane resin, polyester resin, polyamide resin; polybutylene, polybutadiene, polychloroprene, etc. Synthetic rubber; other synthetic wood, synthetic pulp, etc., and carbonized products thereof. Among these raw materials, plant-based raw materials such as coconut shell and wood flour and their carbides are preferable, and coconut shell carbide is particularly preferable, from the viewpoint of mass production and cost.

As a carbonization and activation method for converting these raw materials into the activated carbon 1, for example, known methods such as a fixed bed method, a moving bed method, a fluidized bed method, a slurry method, and a rotary kiln method can be adopted.
Examples of the carbonization method for these raw materials include inert gases such as nitrogen, carbon dioxide, helium, argon, xenone, neon, carbon monoxide, and combustion exhaust gas, or other gases containing these inert gases as main components. Examples thereof include a method of firing at about 400 to 700 ° C. (preferably 450 to 600 ° C.) for about 30 minutes to 10 hours using a mixed gas.

As a method for activating the carbide obtained by the above carbonization method, a gas activation method in which the carbide is fired using an activation gas such as steam, carbon dioxide, or oxygen is preferably used. Of these, a method using steam or carbon dioxide as the activating gas is preferable.
In this activation method, the above-mentioned carbide is supplied for 3 to 12 hours (preferably 5 to 11) while supplying the activation gas at a ratio of 0.5 to 3.0 kg / h (preferably 0.7 to 2.0 kg / h). It is preferable to activate by raising the temperature to 800 to 1,000 ° C. over time, more preferably 6 to 10 hours).
Further, the carbide may be first activated in advance prior to the activation treatment of the carbide. In this primary activation, a method in which a carbon material is usually calcined at a temperature of less than 900 ° C. using an activation gas such as steam, carbon dioxide, or oxygen to activate the gas can be preferably adopted.
By appropriately combining the calcination temperature and calcination time in the carbonization method with the activation gas supply amount, temperature rise rate, and maximum activation temperature in the activation method, activated carbon 1 having the above characteristics that can be used in the present embodiment is produced. can do.

The average particle size of the activated carbon 1 is preferably 3 to 20 μm.
When the average particle size is 3 μm or more, the capacity per electrode volume tends to be high because the density of the active material layer is high. Here, if the average particle size is small, the durability may be low, but if the average particle size is 3 μm or more, such a defect is unlikely to occur. On the other hand, when the average particle size is 15 μm or less, it tends to be easily adapted to high-speed charging / discharging. The average particle size is more preferably 4 to 15 μm, still more preferably 4 to 10 μm. The lower limit and the upper limit can be any combination.

[Activated carbon 2]
The mesopore amount V1 of the activated carbon 2 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 into the power storage element. On the other hand, from the viewpoint of suppressing a decrease in the capacity of the power storage element, it is 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 of the activated carbon 2 is preferably a value larger than 0.8 cc / g in order to increase the specific surface area and the capacity of the activated carbon. On the other hand, from the viewpoint of increasing the density of activated carbon as an electrode and increasing the capacity per unit volume, it is preferably 3.0 cc / g or less. V2 is more preferably greater than 1.0 cc / g and 2.5 cc / g or less, and even more preferably 1.5 cc / g or more and 2.5 cc / g or less. The lower limit and the upper limit can be any combination.

The activated carbon 2 having the above-mentioned meso-pore amount and micro-pore amount has a higher BET specific surface area than the activated carbon used for conventional electric double layer capacitors or lithium ion capacitors. The specific value of the BET specific surface area of the activated carbon 2 is preferably 2,300 m ² / g or more and 4,000 m ² / g or less. The lower limit of the BET specific surface area is more preferably 3,000 m ² / g or more, and further preferably 3,200 m ² / g or more. On the other hand, the upper limit of the BET specific surface area is more preferably 3,800 m ² / g or less. When the BET specific surface area is 2,300 m ² / g or more, a good energy density can be easily obtained, while when the BET specific surface area is 4,000 m ² / g or less, in order to maintain the strength of the electrode. Since it is not necessary to add a large amount of binder, the performance per electrode volume is improved. The lower limit and the upper limit can be any combination.

Activated carbon 2 having the above characteristics can be obtained, for example, by using a raw material and a treatment method as described below.
The carbon source used as a raw material for activated carbon 2 is not particularly limited as long as it is a carbon source normally used as a raw material for activated carbon. For example, plant-based raw materials such as wood, wood flour, and coconut shell; petroleum pitch, coke. Fossil-based raw materials such as, phenol resin, furan resin, vinyl chloride resin, vinyl acetate resin, melamine resin, urea resin, various synthetic resins such as resorcinol resin and the like can be mentioned. Among these raw materials, phenol resin and furan resin are particularly preferable because they are suitable for producing activated carbon having a high specific surface area.

Examples of the method of carbonizing these raw materials and the heating method at the time of activation treatment 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. As the atmosphere at the time of heating, an inert gas such as nitrogen, carbon dioxide, helium, or argon, or a gas containing these inert gases as a main component and mixed with other gases is used. It is preferable to bake at a carbonization temperature of about 400 to 700 ° C. (the lower limit is preferably 450 ° C. or higher, more preferably 500 ° C. or higher, and the upper limit is preferably 650 ° C. or lower) for about 0.5 to 10 hours.

Examples of the method for activating the carbide after the carbonization treatment include a gas activation method in which the carbide is fired using an activated gas such as steam, carbon dioxide, and oxygen, and an alkali metal activation method in which heat treatment is performed after mixing with an alkali metal compound. The alkali metal activation method is preferable for producing activated carbon having a high specific surface area.
In this activation method, the carbides were mixed so that the mass ratio of the carbides to the alkali metal compounds such as KOH and NaOH was 1: 1 or more (the amount of the alkali metal compounds was the same as or larger than the amount of the carbides). Later, heating is carried out in the range of 600 to 900 ° C. (preferably 650 ° C. to 850 ° C.) in an inert gas atmosphere for 0.5 to 5 hours, after which the alkali metal compound is washed and removed with acid and water, and further dried. I do.

As described above, the mass ratio of the carbide to the alkali metal compound (= carbide: alkali metal compound) is preferably 1: 1 or more, but as the amount of the alkali metal compound increases, the amount of mesopores increases, but the mass ratio is 1: 1. Since the amount of pores tends to increase sharply around 3.5, the mass ratio is preferably more than 1: 3 and the amount of the alkali metal compound is preferably 1: 5.5 or less. The mass ratio increases as the amount of the alkali metal compound increases, but it is preferably in the above range in consideration of treatment efficiency such as subsequent cleaning.
In order to increase the amount of micropores and not to increase the amount of mesopores, it is advisable to increase the amount of carbides when activating and mix with KOH. In order to increase both the amount of micropores and the amount of mesopores, it is advisable to use a large amount of KOH. Further, in order to mainly increase the amount of mesopores, it is preferable to perform steam activation after performing alkali activation treatment.
The average particle size of the activated carbon 2 is preferably 3 μm or more and 20 μm or less. It is more preferably 4 μm or more and 15 μm or less, and further preferably 4 μm or more and 10 μm or less. The lower limit and the upper limit can be any combination.

[Usage of activated carbon]
Activated carbons 1 and 2 may be one type of activated carbon, or may be a mixture of two or more types of activated carbon, and each of the above-mentioned characteristic values may be shown as a whole mixture.
The above-mentioned activated carbons 1 and 2 may be used by selecting one of them, or may be used by mixing both.
The positive electrode active material is a material other than activated carbon 1 and 2 (for example, activated carbon that does not have the specific V1 and / or V2, or a material other than activated carbon (for example, a composite oxide of lithium and a transition metal)). It may be included. In an exemplary embodiment, the content of activated carbon 1, the content of activated carbon 2, or the total content of activated carbons 1 and 2 is preferably more than 50% by mass, respectively, and 70% by mass or more of the total positive electrode active material. More preferably, 90% by mass or more is further preferable, and 100% by mass is further preferable.

The content ratio of the positive electrode active material in the positive electrode active material layer is preferably 35% by mass or more and 95% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor. The lower limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, and further preferably 55% by mass or more. On the other hand, the upper limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, and further preferably 80% by mass or less. By setting the content ratio in this range, suitable charge / discharge characteristics are exhibited. The lower limit and the upper limit can be any combination.

[Lithium carbonate]
The positive electrode precursor preferably contains lithium carbonate, and the positive electrode active material layer of the positive electrode precursor more preferably contains lithium carbonate. Lithium carbonate can be decomposed at the positive electrode in the lithium doping step to release lithium ions, has low hygroscopicity, and can be handled in air.
Lithium carbonate is preferably in the form of particles. Various methods can be used for atomizing lithium carbonate. For example, a crusher such as a ball mill, a bead mill, a ring mill, a jet mill, or a rod mill can be used.
The content ratio of the lithium compound in the positive electrode precursor is preferably 5% by mass or more and 60% by mass or less, preferably 10% by mass or more and 50% by mass or less, based on the total mass of the positive electrode active material layer in the positive electrode precursor. Is more preferable. By setting the content ratio in this range, it is possible to exert a suitable function as a dopant source for the negative electrode and to impart an appropriate degree of porosity to the positive electrode, and both of them achieve high load charge / discharge efficiency. It is preferable because it can provide an excellent power storage element.

The positive electrode of this embodiment contains lithium carbonate particles. The lithium carbonate contained in the positive electrode is characterized by being 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode, and is 2.5% by mass or more and 30% by mass or less. Is more preferable. When lithium carbonate is 1% by mass or more, lithium carbonate adsorbs fluorine ions in the electrolytic solution, and lithium carbonate suppresses the side reaction of the electrolytic solution on the positive electrode, so that high temperature durability and high load charge / discharge cycle Durability is improved, and the effect becomes remarkable at 2.5% by mass or more. Further, when lithium carbonate is 50% by mass or less, the electron conductivity between the positive electrode active materials is less likely to be inhibited by lithium carbonate, so that high input / output characteristics are exhibited, and 30% by mass or less is particularly preferable. .. The lower limit and the upper limit can be any combination.

[Method for identifying lithium carbonate in electrodes]
The method for identifying lithium carbonate contained in the positive electrode is not particularly limited, but for example, it can be identified by the following method. For the identification of lithium carbonate, it is preferable to identify by combining a plurality of analysis methods described below.
When measuring SEM-EDX, Raman, and XPS described below, disassemble the non-aqueous lithium-type power storage element in an argon box, take out the positive electrode, clean the electrolyte adhering to the positive electrode surface, and then perform the measurement. Is preferable. As for the method for cleaning the positive electrode, since the electrolyte adhering to the surface of the positive electrode may be washed away, a carbonate solvent such as dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate can be preferably used. As a cleaning method, for example, the positive electrode is immersed in a diethyl carbonate solvent 50 to 100 times the weight of the positive electrode for 10 minutes or more, and then the solvent is replaced and the positive electrode is immersed again. After that, the positive electrode is taken out from diethyl carbonate and vacuum dried (temperature: 0 to 200 ° C., pressure: 0 to 20 kPa, time: 1 to 40 hours, and the condition is that the residual diethyl carbonate in the positive electrode is 1% by mass or less. The residual amount of diethyl carbonate can be quantified based on the calibration line prepared in advance by measuring the GC / MS of the water after washing with distilled water and adjusting the liquid amount, which will be described later.) -Perform EDX, Raman, and XPS analysis.
Regarding ion chromatography described later, carbonate ions can be identified by analyzing the water after washing the positive electrode with distilled water.
If lithium carbonate cannot be identified by the above analysis method, other analysis methods include ⁷ Li-solid NMR, XRD (X-ray diffraction), TOF-SIMS (time-of-flight secondary ion mass spectrometry), and AES (Auger). Lithium carbonate can also be identified by using electron spectroscopy), TPD / MS (heat-of-flight mass spectrometry), DSC (differential scanning calorie analysis), and the like.

[SEM-EDX]
Lithium carbonate and the positive electrode active material can be identified by oxygen mapping using an SEM-EDX image of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As a measurement example of the SEM-EDX image, the acceleration voltage can be measured as 10 kV, the emission current as 1 μA, the number of measurement pixels as 256 × 256 pixels, and the number of integrations as 50 times. In order to prevent the sample from being charged, gold, platinum, osmium or the like can be surface-treated by a method such as vacuum deposition or sputtering. Regarding the method for measuring the SEM-EDX image, it is preferable to adjust the brightness and contrast so that the brightness does not reach the maximum brightness and the average value of the brightness is in the range of 40% to 60%. Lithium carbonate is a particle containing a bright portion having an area of 50% or more, which is binarized with respect to the obtained oxygen mapping based on the average value of brightness.

[Raman]
Lithium carbonate and the positive electrode active material can be discriminated by Raman imaging of the positive electrode surface measured at an observation magnification of 1000 to 4000 times. As an example of measurement conditions, the excitation light is 532 nm, the excitation light intensity is 1%, the long operation of the objective lens is 50 times, the diffraction grating is 1800 gr / mm, the mapping method is point scanning (slit 65 mm, binning 5 pix), 1 mm step, The exposure time per point can be measured for 3 seconds, the number of integrations can be measured once, and the measurement can be performed under the condition of having a noise filter. For the measured Raman spectrum, a straight baseline is set in the range of 1071-1104 cm ^-1 , the area is calculated with a positive value from the baseline as the peak of carbonate ion, and the frequency is integrated. At this time, the noise component is added. The frequency for the bicarbonate peak area approximated by the Gaussian function is subtracted from the above-mentioned bicarbonate frequency distribution.

[XPS]
The bonding state of lithium can be determined by analyzing the electronic state of lithium by XPS. As an example of measurement conditions, the X-ray source is monochromatic AlKα, the X-ray beam diameter is 100 μmφ (25 W, 15 kV), the path energy is narrow scan: 58.70 eV, there is charge neutralization, and the number of sweeps is narrow scan: 10 times. (Carbon, oxygen) 20 times (fluorine) 30 times (phosphorus) 40 times (lithium) 50 times (silicon), energy steps can be measured under the conditions of narrow scan: 0.25 eV. It is preferable to clean the surface of the positive electrode by sputtering before measuring XPS. As the sputtering conditions, for example, the surface of the positive electrode can be cleaned under the condition of an acceleration voltage of 1.0 kV, 2 mm × 2 mm for 1 minute (1.25 nm / min in terms of SiO ₂ ). Regarding the obtained XPS spectrum, the peak of Li1s binding energy of 50 to 54 eV is LiO ₂ or Li-C bond, and the peak of 55 to 60 eV is LiF, Li ₂ CO ₃ , Li _x PO _y F _z (x, y, z). Is an integer of 1 to 6), the peak of C1s binding energy 285 eV is C-C bond, the peak of 286 eV is CO bond, the peak of 288 eV is COO, the peak of 290-292 eV is CO ₃ ^2- , CF Bonding, the peak of binding energy 527 to 530 eV of O1s is O ^2- (Li ₂ O), the peak of 531 to 532 eV is CO, CO ₃ , OH, PO _x (x is an integer of 1 to 4), SiO _x (x) Is an integer of 1 to 4), the peak of 533 eV is CO, SiO _x (x is an integer of 1 to 4), the peak of binding energy 685 eV of F1s is LiF, the peak of 687 eV is CF bond, Li _x PO. Regarding the binding energies of _y F _z (x, y, z are integers 1 to 6), PF ₆ ⁻ , P2p, the peak of 133 eV is PO _x (x is an integer of 1 to 4), and the peak of 134 to 136 eV is PF. _x (x is an integer from 1 to 6), Si peak binding energy 99eV of Si2p, silicide, a peak of _{101~107eV Si x O y (x,} y are arbitrary integers) can be assigned as. When the peaks of the obtained spectrum overlap, it is preferable to separate the peaks assuming a Gaussian function or a Lorentz function and assign the spectra. From the measurement result of the electronic state and the result of the existing element ratio obtained above, it can be determined whether the existing lithium compound is lithium carbonate.

[Ion chromatography]
By analyzing the distilled water washing solution of the positive electrode by ion chromatography, the anion species eluted in water can be identified, so that carbonate ions can be detected. As the column to be used, an ion exchange type, an ion exclusion type, and a reverse phase ion pair type can be used. As the detector, an electric conductivity detector, an ultraviolet visible absorptiometry detector, an electrochemical detector, etc. can be used, a suppressor method in which a suppressor is installed in front of the detector, and electrical conduction without a suppressor. A non-suppressor method using a low-degree solution as the eluent can be used. It is also possible to measure mass spectrometer and charged particle detection in combination with a detector.
The retention time of the sample is constant for each ion species component if conditions such as the column to be used and the eluent are determined, and the magnitude of the peak response differs for each ion species but is proportional to the concentration. It is possible to quantify the carbonate ion species component by measuring in advance a carbonate ion standard solution having a known concentration in which traceability is ensured.

[Lithium carbonate quantification method]
The content ratio of lithium carbonate in the positive electrode is determined by dividing the weight of lithium carbonate contained in the positive electrode by the weight of the positive electrode active material layer. A specific method for quantifying lithium carbonate contained in the positive electrode will be described below. The positive electrode is washed with an organic solvent, then washed with distilled water, and lithium carbonate can be quantified from the change in the weight of the positive electrode before and after washing with distilled water. Although area measurement is positive is not particularly limited, it is preferably, more preferably 25 cm ² or more 150 cm ² or less from the viewpoint of reducing the variation in measurement is 5 cm ² or more 200 cm ² or less. If the area is 5 cm ² or more, the reproducibility of measurement is ensured. If the area is 200 cm ² or less, the handling of the sample is excellent. For cleaning with an organic solvent, the organic solvent is not particularly limited as long as the decomposition products of the electrolytic solution deposited on the surface of the positive electrode can be removed. However, the elution of lithium carbonate can be achieved by using an organic solvent having a solubility of lithium carbonate of 2% or less. It is preferable because it is suppressed. For example, polar solvents such as methanol and acetone are preferably used.

The method for cleaning the positive electrode is to sufficiently immerse the positive electrode in a methanol solution 50 to 100 times the weight of the positive electrode for 3 days or more. At this time, it is preferable to take measures such as covering the container so that methanol does not volatilize. After that, the positive electrode is taken out from methanol and vacuum dried (temperature: 100 to 200 ° C., pressure: 0 to 10 kPa, time: 5 to 20 hours, and the condition is that the residual amount of methanol in the positive electrode is 1% by mass or less. the remaining amount, measured GC / MS of water after washing with distilled water, which will be described later, can be determined based on a calibration curve prepared in advance.), and the weight of the positive electrode at the time M _{0 [g]} And. Subsequently, the positive electrode is sufficiently immersed in distilled water 100 times the weight of the positive electrode (100M ₀ [g]) for 3 days or more. At this time, it is preferable to take measures such as covering the container so that the distilled water does not volatilize. After immersion least 3 days, a distilled water outlet of the positive electrode (when measuring the above-described ion chromatography, the amount of distilled water to adjust the volume so that the 100M 0 _[g].), Of the Vacuum dry in the same way as methanol washing. The weight of the positive electrode at this time is M ₁ [g], and subsequently, in order to measure the weight of the current collector of the obtained positive electrode, a positive electrode active material layer on the current collector is used using a spatula, a brush, a brush, or the like. Get rid of. Assuming that the weight of the obtained positive electrode current collector is M ₂ [g], the mass% Z of lithium carbonate contained in the positive electrode can be calculated by the following formula (4).
Z = 100 × [1- (M _1- M ₂ ) / (M _0- M ₂ )]. .. .. Equation (4)

[Other components of the positive electrode active material layer]
The positive electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material and lithium carbonate, if necessary.
The conductive filler is not particularly limited, and for example, acetylene black, ketjen black, vapor-grown carbon fibers, graphite, carbon nanotubes, a mixture thereof, and the like can be used. The amount of the conductive filler used is preferably 0 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. It is more preferably 0 parts by mass or more and 20 parts by mass or less, and further preferably 1 part by mass or more and 15 parts by mass or less. If the mixing amount is more than 30 parts by mass, the content ratio of the positive electrode active material in the positive electrode active material layer decreases, and the energy density per volume of the positive electrode active material layer decreases, which is not preferable.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer. Etc. can be used. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. It is more preferably 3 parts by mass or more and 27 parts by mass or less, and further preferably 5 parts by mass or more and 25 parts by mass or less. When the amount of the binder is 1% by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry / exit and diffusion of ions into the positive electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the binder used is preferably 0 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry / exit and diffusion of ions into the positive electrode active material.

[Positive current collector]
The material constituting the positive electrode current collector is not particularly limited as long as it has high electron conductivity and does not deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions, but a metal foil is preferable. Aluminum foil is particularly preferable as the positive electrode current collector in the non-aqueous lithium power storage device of the present embodiment.
The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes such as an etching foil may be used.
The thickness of the positive electrode current collector is not particularly limited as long as the shape and strength of the positive electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Preparation of positive electrode precursor]
The positive electrode precursor that serves as the positive electrode of the non-aqueous lithium-type power storage element can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors, and the like. For example, the positive electrode active material, lithium carbonate, and other optional components used as needed are dispersed or dissolved in water or an organic solvent to prepare a slurry coating solution, and this coating solution is collected as a positive electrode. A positive electrode precursor can be obtained by applying a coating on one side or both sides of an electric body to form a coating film and drying the coating. Further, the obtained positive electrode precursor may be pressed to adjust the film thickness and bulk density of the positive electrode active material layer. The positive electrode active material, lithium carbonate, and other optional components used as needed are mixed dry without using a solvent, the resulting mixture is press-molded, and then the positive electrode is used with a conductive adhesive. It is also possible to attach it to the current collector.

In the preparation of the coating liquid for the positive electrode precursor, a part or all of various material powders including the positive electrode active material are dry-blended, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved therein. Alternatively, dispersed liquid or slurry-like substances may be added. Further, various material powders containing a positive electrode active material may be added to a liquid or slurry substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. As the method of dry blending, for example, a positive electrode active material and lithium carbonate are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed so that lithium carbonate having low conductivity is coated with a conductive material. May be done. As a result, lithium carbonate is easily decomposed in the positive electrode precursor in the lithium doping step described later. When water is used as the solvent of the coating liquid, the coating liquid may become alkaline by adding lithium carbonate. Therefore, a pH adjuster may be added if necessary.

The adjustment of the coating liquid of the positive electrode precursor is not particularly limited, but preferably a disperser such as a homodisper, a multi-axis disperser, a planetary mixer, or a thin film swirling high-speed mixer can be used. it can. In order to obtain a coating liquid in a good dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. A peripheral speed of 1 m / s or more is preferable because various materials are satisfactorily dissolved or dispersed. Further, when it is 50 m / s or less, various materials are not destroyed by heat or shearing force due to dispersion, and reaggregation does not occur, which is preferable.
The dispersity of the coating liquid is preferably such that the particle size measured by the grain gauge is 0.1 μm or more and 100 μm or less. The upper limit of the dispersity is more preferably a particle size of 80 μm or less, and further preferably a particle size of 50 μm or less. When the particle size is 0.1 μm or less, the size is smaller than the particle size of various material powders containing the positive electrode active material, and the material is crushed at the time of preparing the coating liquid, which is not preferable. Further, when the particle size is 100 μm or less, stable coating can be performed without clogging at the time of discharging the coating liquid or generation of streaks on the coating film.

The viscosity (ηb) of the coating liquid of the positive electrode precursor is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1, It is 700 mPa · s or more and 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and thickness can be satisfactorily controlled. On the other hand, when it is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the coating film thickness can be controlled to be less than the desired coating film thickness.
The TI value (thixotropy index value) of the coating liquid is preferably 1.1 or more. It is more preferably 1.2 or more, still more preferably 1.5 or more. When the TI value is 1.1 or more, the coating film width and thickness can be satisfactorily controlled.

The formation of the coating film of the positive electrode precursor is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by single-layer coating or multi-layer coating. In the case of multi-layer coating, the composition of the coating liquid may be adjusted so that the content of lithium carbonate in each layer of the coating film is different. The coating speed is preferably 0.1 m / min or more and 100 m / min or less, more preferably 0.5 m / min or more and 70 m / min or less, and further preferably 1 m / min or more and 50 m / min or less. If the coating speed is 0.1 m / min or more, stable coating can be performed. On the other hand, if it is 100 m / min or less, sufficient coating accuracy can be ensured.

The drying of the coating film of the positive electrode precursor is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Moreover, you may dry by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the positive electrode current collector and the positive electrode active material layer can be suppressed.

The press of the positive electrode precursor is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the positive electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The press pressure is preferably 0.5 kN / cm or more and 20 kN / cm or less, more preferably 1 kN / cm or more and 10 kN / cm or less, and further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. On the other hand, when it is 20 kN / cm or less, the positive electrode precursor does not bend or wrinkle, and the desired positive electrode active material layer film thickness and bulk density can be adjusted. Further, the gap between the press rolls can be set to an arbitrary value according to the desired film thickness of the positive electrode active material layer and the film thickness of the positive electrode precursor after drying so as to have a bulk density. Further, the pressing speed can be set to an arbitrary speed at which the positive electrode precursor does not bend or wrinkle. Further, the surface temperature of the pressed portion may be room temperature or may be heated if necessary. The lower limit of the surface temperature of the pressed portion at the time of heating is preferably the melting point of the binder to be used of minus 60 ° C. or higher, more preferably 45 ° C. or higher, still more preferably 30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat it to 90 ° C. or higher and 200 ° C. or lower. It is more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher and 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferably heated to 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. It is to heat to 120 ° C. or higher and 120 ° C. or lower.

The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a heating 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.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The thickness of the positive electrode active material layer is preferably 20 μm or more and 200 μm or less per one side of the positive electrode current collector, more preferably 25 μm or more and 100 μm or less per one side, and further preferably 30 μm or more and 80 μm or less. When the thickness of the positive electrode active material layer is 20 μm or more, sufficient charge / discharge capacity can be exhibited. On the other hand, when the thickness of the positive electrode active material layer is 200 μm or less, the ion diffusion resistance in the electrode can be kept low. Therefore, sufficient output characteristics can be obtained, the cell volume can be reduced, and therefore the energy density can be increased. The thickness of the positive electrode active material layer when the current collector has through holes or irregularities means the average value of the thickness per side of the portion of the current collector that does not have through holes or irregularities. Further, the lower limit and the upper limit can be any combination.

The bulk density of the positive electrode active material layer in the positive electrode after the lithium doping step described later is preferably 0.50 g / cm ³ or more, more preferably 0.55 g / cm ³ or more and 1.3 g / cm ³ or less. Is. When the bulk density of the positive electrode active material layer is 0.50 g / cm ³ or more, a high energy density can be exhibited and the miniaturization of the power storage element can be achieved. On the other hand, when the bulk density is 1.3 g / cm ³ or less, the electrolytic solution is sufficiently diffused in the pores in the positive electrode active material layer, and high output characteristics can be obtained.

In the present specification, the BET specific surface area, the mesopore amount, the micropore amount, and the average pore diameter are values obtained by the following methods, respectively. The sample is vacuum-dried at 200 ° C. for 24 hours, and the isotherms of adsorption and desorption are measured using nitrogen as an adsorbent. Using the adsorption-side isotherms obtained here, the BET specific surface area is calculated by the BET multipoint method or the BET1 point method, the mesopore amount is calculated by the BJH method, and the micropore amount is calculated by the MP method.
The BJH method is a calculation method generally used for analysis of mesopores, and was proposed by Barrett, Joiner, Hallenda et al. (E.P. Barrett, L.G. Joiner and P. Hallenda, J. Am. Chem. Soc., 73, 373 (1951)).
Further, the MP method is a micropore volume, a micropore area, and a micropore area using the “t-plot method” (BC Lippens, JH de Boer, J. Catalysis, 4319 (1965)). It means a method for obtaining the distribution of micropores, and M.I. It is a method devised by Mikhair, Brunauer, and Bodor (RS Mikhair, S. Brunauer, EE Bodor, J. Colloid Interface Sci., 26, 45 (1968)).
The average pore diameter is obtained by measuring the equilibrium adsorption amount of nitrogen gas under each relative pressure under liquid nitrogen temperature, and dividing the total pore volume per mass of the sample by the BET specific surface area. Refers to what you asked for.

In the present specification, the average particle size is the particle size at the point where the cumulative curve is 50% when the cumulative curve is obtained with the total product as 100% when the particle size distribution is measured using a particle size distribution measuring device. That is, it refers to a 50% diameter (Median diameter). This average particle size can be measured using a commercially available laser diffraction type particle size distribution measuring device.

In the present specification, the dispersity is a value obtained by a dispersity evaluation test using a grain gauge specified in JIS K5600. That is, a sufficient amount of sample is poured into the tip of the deeper groove of the grain gauge having a groove having a desired depth according to the size of the grain, and the sample is slightly overflowed from the groove. Next, the long side of the scraper becomes parallel to the width direction of the gauge, and the cutting edge is placed so as to contact the deep tip of the groove of the grain gauge, and the scraper is held so as to be the surface of the gauge while the long side direction of the groove. Pull the surface of the gauge at a right angle to the groove depth of 0 at a uniform speed for 1 to 2 seconds, and shine light at an angle of 20 ° to 30 ° within 3 seconds after the pulling is completed. Observe and read the depth at which the grains appear in the grooves of the grain gauge.

In the present specification, the viscosity (ηb) and the TI value are values obtained by the following methods, respectively. First, a stable viscosity (ηa) is obtained after measuring for 2 minutes or more under the conditions of a temperature of 25 ° C. and a shear rate of 2s- ¹ using an E-type viscometer. Next, the viscosity (ηb) measured under the same conditions as above is obtained except that the shear rate is changed to 20s ^-1 . Using the viscosity value obtained above, the TI value is calculated by the formula TI value = ηa / ηb. When increasing the shear rate from 2s ^-1 to 20s ^-1 , the shear rate may be increased in one step, or the shear rate may be increased in multiple steps within the above range, and the viscosity at the shear rate may be appropriately obtained. You may let me.

[Ratio of carbonate ion area to cross-sectional area of positive electrode active material layer]
The positive electrode active material layer according to the present embodiment contains lithium carbonate, and in the imaging image obtained by microscopic Raman spectroscopy of the positive electrode cross section, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less. It is characterized by being. The area ratio of the carbonate ion mapping is more preferably 2% or more and 20% or less. When the area ratio of the carbonate ion mapping is 1% or more, the high temperature storage durability and the high load charge / discharge cycle characteristics are improved. Although the reason is not clear, it is presumed that the carbonate ion traps the hydrogen ions generated during high-temperature storage or cycle test, thereby suppressing the side reaction of the electrolytic solution. When the area ratio of the carbonate ion mapping is 40% or less, high input / output characteristics can be obtained because lithium carbonate does not interfere with the conductive path between the positive electrode active materials. The lower limit and the upper limit can be any combination.

[Number average particle size of lithium carbonate and positive electrode active material]
For lithium carbonate and the positive electrode active material, when the number average particle size of lithium carbonate is X ₁ and the average particle size of the positive electrode active material is Y ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and 3 μm ≤ Y ₁ ≤ 20 μm. Yes, and it is characterized in that X ₁ <Y ₁ . More preferably about X ₁ is a 2μm ≦ _{X 1} ≦ 4μm. More preferably about Y _1, a 4μm ≦ _{Y 1} ≦ 15μm, particularly preferably 4μm ≦ _{Y 1} ≦ 10μm. When X ₁ is 1 μm or more, lithium carbonate can remain in the positive electrode after lithium doping, so that the high load charge / discharge cycle characteristics are improved by adsorbing the fluorine ions generated in the high load charge / discharge cycle. When X ₁ is 5 μm or less, the reaction area with the fluorine ions generated in the high load charge / discharge cycle increases, so that the adsorption of fluorine ions can be performed efficiently. When Y ₁ is 3 μm or more, electron conductivity between the positive electrode active materials can be ensured. When Y ₁ is 20 μm or less, high output characteristics can be exhibited because the reaction area with the electrolyte ion increases. When X ₁ <Y ₁ , the gaps formed between the positive electrode active materials are filled with lithium carbonate, so that the energy density can be increased while ensuring the electron conductivity between the positive electrode active materials. The lower limit and the upper limit can be any combination.

The measurement method of X ₁ and Y ₁ is not particularly limited, but it can be calculated from a micro Raman image of the positive electrode cross section. As for the method of forming the positive electrode cross section, BIB processing can be used in which an Ar beam is irradiated from the upper part of the positive electrode to form a smooth cross section along the edge of the shielding plate installed directly above the sample, but the direction of the cross section and the like can be used. There is no particular limitation.
X ₁ can be calculated by, for example, the following method. For the Raman spectrum of each measurement point of the microscopic Raman image of the positive cross section, a linear baseline is set around the Raman peak wavelength of carbonate ions, and the area higher than the baseline is positive and the area lower than the baseline is negative. The area (a) is calculated and mapped. A frequency distribution table is created for the area (a) and made into a histogram. Approximate with a Gaussian function as a partial noise component below the area value that gives the maximum frequency, and subtract it from the histogram. Map the measurement position of the spectrum, which shows the area above the maximum frequency in the histogram after subtracting the noise component, and use this as the alkali metal carbonate particles. It is obtained by calculating the average of the major axis of all alkali metal carbonate particles in the measurement range.
Y ₁ can be calculated by, for example, the following method. In the same field of view as the microscopic Raman was measured, the measured optical microscope image and the carbonate ion mapping data were superimposed, and the particles confirmed in the optical microscope image excluding the carbonate particles were the positive electrode active material particles. Then, it is obtained by calculating the average of the major axes of all the active material particles confirmed in the field of view.

[Fluorine compound coverage of lithium carbonate]
If the lithium carbonate contained in the positive electrode is decomposed and gasified by a side reaction, it causes an increase in resistance and a cause of gas generation during high-temperature storage. Therefore, it is preferable to form a film made of a fluorine-containing compound on the surface of lithium carbonate to suppress the decomposition reaction of lithium carbonate.
The method for forming the film of the fluorine-containing compound is not particularly limited, but a method of incorporating the fluorine-containing compound in the electrolytic solution and applying a high voltage equal to or higher than the decomposition potential of the fluorine-containing compound to the non-aqueous lithium-type power storage element, or decomposition. Examples include a method of applying a temperature higher than the temperature.
The coverage of the fluorine compound to be coated on the surface of lithium carbonate (area overlap rate of fluorine mapping with respect to oxygen mapping in the positive electrode surface SEM-EDX image A ₁ ) is preferably 30% or more and 99% or less. When A ₁ is 40% or more, the decomposition of lithium carbonate can be suppressed. When A ₁ is 99% or less, the vicinity of the positive electrode can be kept basic, so that the high load cycle characteristics are excellent.
As a method for measuring the coverage, in the element mapping obtained by SEM-EDX on the positive electrode surface, the area overlap rate of fluorine mapping is calculated for the oxygen mapping binarized based on the average value of brightness. Be done.
The measurement conditions for element mapping of SEM-EDX are not particularly limited, but the number of pixels is preferably in the range of 128 × 128 pixels to 512 × 512 pixels, and the brightness has no pixels that reach the maximum brightness, and the average brightness. It is preferable to adjust the brightness and contrast so that the value falls within the range of 40% to 60% brightness.
In the element mapping obtained by SEM-EDX of the positive electrode cross section, it is preferable that the area overlap ratio A ₂ of the fluorine mapping with respect to the oxygen mapping binarized based on the average value of the brightness is 10% or more and 65% or less. When A ₂ is 10% or more, the decomposition of lithium carbonate can be suppressed. When A ₂ is 65% or less, the inside of lithium carbonate is not fluorinated, so that the vicinity of the positive electrode can be kept basic and the high load cycle characteristics are excellent.

｛式（１）中、Ｒ^１は、炭素数１〜４のアルキル基、炭素数１〜４のハロゲン化アルキル基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（２）中、Ｒ^１は、炭素数１〜４のアルキル基、炭素数１〜４のハロゲン化アルキル基であり、Ｒ^２は水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝

｛式（３）中、Ｒ^１は、炭素数１〜４のアルキル基、炭素数１〜４のハロゲン化アルキル基であり、Ｒ^２、Ｒ^３はそれぞれ独立に水素、炭素数１〜１０のアルキル基、炭素数１〜１０のモノ若しくはポリヒドロキシアルキル基、炭素数２〜１０のアルケニル基、炭素数２〜１０のモノ又はポリヒドロキシアルケニル基、炭素数３〜６のシクロアルキル基、又はアリール基であり、Ｘ^１、Ｘ^２はそれぞれ独立に−（ＣＯＯ）_ｎ（ここで、ｎは０又は１である。）である。｝ [Positive electrode active material layer]
The positive electrode active material layer contains one or more compounds selected from the group consisting of the following formulas (1) to (3) at 1.60 × 10 ^-4 mol / g to 300 × 10 ⁻ per unit mass of the positive electrode material. It is preferably contained at ⁴ mol / g.

{In formula (1), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here). , N is 0 or 1.). }

{In formula (2), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 carbon atom. A mono or polyhydroxyalkyl group having 10 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a mono or polyhydroxyalkenyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or an aryl group, X ¹ , X ² are independently − (COO) _n (where n is 0 or 1). }

{In formula (3), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and having 1 to 10 carbon atoms, respectively. Alkyl group, mono or polyhydroxyalkyl group with 1 to 10 carbon atoms, alkenyl group with 2 to 10 carbon atoms, mono or polyhydroxyalkenyl group with 2 to 10 carbon atoms, cycloalkyl group with 3 to 6 carbon atoms, or aryl It is a group, and X ¹ and X ² are independently − (COO) _n (where n is 0 or 1). }

In the formula (1), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and X ¹ and X ² are independently − (COO) _n (here, here). n is 0 or 1).
Particularly preferred compounds are the compounds represented by LiOC ₂ H ₄ OLi, LiOC ₃ H ₆ OLi, LiOC ₂ H ₄ OCOOLi, LiOCOOC ₃ H ₆ OLi, LiOCOOC ₂ H ₄ OCOOLi and LiOCOOC ₃ H ₆ OCOOLi.

In the formula (2), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and R ² is hydrogen, an alkyl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms. 10 mono or polyhydroxyalkyl groups or lithium alkoxides thereof, alkenyl groups having 2 to 10 carbon atoms, mono or polyhydroxyalkenyl groups having 2 to 10 carbon atoms, cycloalkyl groups having 3 to 6 carbon atoms, or aryl groups. , X ¹ and X ² are independently − (COO) _n (where n is 0 or 1).
Particularly preferred compounds are LiOC ₂ H ₄ OH, LiOC ₃ H ₆ OH, LiOC ₂ H ₄ OCOOH, LiOC ₃ H ₆ OCOOH, LiOCOOC ₂ H ₄ OCOOH, LiOCOOC ₃ H ₆ OCOOH, LiOC ₂ H ₄ OCH ₃ , LiOC _{3 H 6 OCH 3, LiOC 2 H} 4 OCOOCH 3, LiOC 3 H 6 OCOOCH 3, LiOCOOC 2 H 4 OCOOCH 3, LiOCOOC 3 H 6 OCOOCH 3, LiOC 2 H 4 OC 2 H 5, LiOC 3 H 6 OC 2 H 5 , LiOC ₂ H ₄ OCOC ₂ H ₅ , LiOC ₃ H ₆ OCOC ₂ H ₅ , LiOCOC ₂ H ₄ OCOC ₂ H ₅ , LiOCOC ₃ H ₆ OCOC ₂ H ₅ .

In the formula (3), R ¹ is an alkyl group having 1 to 4 carbon atoms and an alkyl halide group having 1 to 4 carbon atoms, and R ² and R ³ are independently hydrogen and an alkyl having 1 to 10 carbon atoms, respectively. Group, mono or polyhydroxyalkyl group having 1 to 10 carbon atoms or lithium alkylate thereof, alkenyl group having 2 to 10 carbon atoms, mono or polyhydroxyalkylyl group having 2 to 10 carbon atoms, cycloalkyl group having 3 to 6 carbon atoms , Or an aryl group, where X ¹ and X ² are independently − (COO) _n (where n is 0 or 1).
Particularly preferred compounds are HOC ₂ H ₄ OH, HOC ₃ H ₆ OH, HOC ₂ H ₄ OCOOH, HOC ₃ H ₆ OCOOH, HOCOC OC ₂ H ₄ OCOOH, HOCOC ₃ H ₆ OCOOH, HOC ₂ H ₄ OCH ₃ , HOC _{3 H 6 OCH 3, HOC 2 H} 4 OCOOCH 3, HOC 3 H 6 OCOOCH 3, HOCOOC 2 H 4 OCOOCH 3, HOCOOC 3 H 6 OCOOCH 3, HOC 2 H 4 OC 2 H 5, HOC 3 H 6 OC 2 H 5 _{, HOC 2 H 4 OCOOC 2 H} 5, HOC 3 H 6 OCOOC 2 H 5, HOCOOC 2 H 4 OCOOC 2 H 5, HOCOOC 3 H 6 OCOOC 2 H 5, CH 3 OC 2 H 4 OCH 3, CH 3 OC 3 H ₆ OCH ₃ , CH ₃ OC ₂ H ₄ OCOOCH ₃ , CH ₃ OC ₃ H ₆ OCOCCH ₃ , CH ₃ OCOC ₂ H ₄ OCOCCH ₃ , CH ₃ OCOC ₃ H ₆ OCOCCH ₃ , CH ₃ OC ₂ H ₄ OC ₂ H ₅ , CH ₃ OC ₃ H ₆ OC ₂ H ₅ , CH ₃ OC ₂ H ₄ OCOC ₂ H ₅ , CH ₃ OC ₃ H ₆ OCOC ₂ H ₅ , CH ₃ OCOC ₂ H ₄ OCOC ₂ H ₅ , CH ₃ OCOC ₃ H ₆ OCOC ₂ H ₅ , C ₂ H ₅ OC ₂ H ₄ OC ₂ H ₅ , C ₂ H ₅ OC ₃ H ₆ OC ₂ H ₅ , C ₂ H ₅ OC ₂ H ₄ OCOC ₂ H ₅ , C ₂ H ₅ OC ₃ H ₆ OCOC ₂ H ₅ , C ₂ H ₅ OCOC ₂ H ₄ OCOC ₂ H ₅ , C ₂ H ₅ OCOC ₃ H ₆ OCOC ₂ H ₅
It is a compound represented by.

Examples of the method for incorporating the compound in the positive electrode active material layer include a method of mixing the compound in the positive electrode active material layer, a method of adsorbing the compound in the positive electrode active material layer, and a method of adsorbing the compound in the positive electrode active material layer. Examples thereof include a method of electrochemically precipitating.
Above all, a positive electrode active material layer is contained in a non-aqueous electrolytic solution that can be decomposed to produce these compounds, and the decomposition reaction of the precursor in the step of producing a power storage element is utilized. A method of depositing the compound inside is preferable.

As the precursor for forming the compound, it is preferable to use at least one organic solvent selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, and fluoroethylene carbonate, and ethylene carbonate and / Or it is more preferred to use propylene carbonate.

Here, the total amount of the compound is preferably 1.60 × 10 ^-4 mol / g or more, and preferably 5.0 × 10 ^-4 mol / g or more, per unit mass of the positive electrode active material. More preferred. When the total amount of the compound is 1.60 × 10 ^-4 mol / g or more per unit mass of the positive electrode active material layer, the non-aqueous electrolyte solution does not come into contact with the positive electrode active material, and the non-aqueous electrolyte solution is oxidatively decomposed. Can be suppressed.
The total amount of the compound is 300 × 10 ^-4 mol / g or less, more preferably 150 × 10 ^-4 mol / g or less, and 100 × 10 ^-4 per unit mass of the positive electrode active material. It is more preferably mol / g or less. When the total amount of the compound is 300 × 10 ^-4 mol / g or less per unit mass of the positive electrode active material, high input / output characteristics can be exhibited without inhibiting the diffusion of Li ions. The lower limit and the upper limit can be any combination.

[Negative electrode]
The negative electrode has a negative electrode current collector and a negative electrode active material layer existing on one side or both sides thereof.
[Negative electrode active material layer]
The negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions. In addition to this, if necessary, an optional component such as a conductive filler, a binder, and a dispersant stabilizer may be contained.

[Negative electrode active material]
As the negative electrode active material, a substance capable of storing and releasing lithium ions can be used. Specific examples thereof include carbon materials, titanium oxides, silicon, silicon oxides, silicon alloys, silicon compounds, tin and tin compounds. The content of the carbon material with respect to the total amount of the negative electrode active material is preferably 50% by mass or more, and more preferably 70% by mass or more. The content of the carbon material can be 100% by mass, but from the viewpoint of obtaining a good effect by using other materials in combination, for example, it is preferably 90% by mass or less, and 80% by mass or less. May be good.

The negative electrode active material is preferably doped with lithium ions. In the present specification, the lithium ions doped in the negative electrode active material mainly include three forms.
The first form is lithium ions that are occluded as a design value in the negative electrode active material before the non-aqueous lithium-type power storage element is manufactured.
The second form is lithium ions occluded in the negative electrode active material when a non-aqueous lithium storage element is manufactured and shipped.
The third form is lithium ions occluded in the negative electrode active material after the non-aqueous lithium storage element is used as a device.
By doping the negative electrode active material with lithium ions, it is possible to satisfactorily control the capacity and operating voltage of the obtained non-aqueous lithium-type power storage element.

Examples of the carbon material include non-graphitizable carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon globules; graphite whiskers; polyacene-based substances. Amorphous carbonaceous materials such as; petroleum-based pitches, coal-based pitches, carbonaceous materials such as mesocarbon microbeads, coke, synthetic resins (eg, phenolic resins, etc.) Carbonated materials obtained by heat treatment of precursors; Thermal decomposition products of furfuryl alcohol resin or novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof can be mentioned.

Among these, from the viewpoint of lowering the resistance of the negative electrode, heat treatment is performed in a state where one or more of the carbon materials (hereinafter, also referred to as a base material) and the carbonaceous material precursor coexist, and the base material and the carbon are coexisted. A composite carbon material obtained by combining a carbon material derived from a quality material precursor is preferable. The carbonaceous material precursor is not particularly limited as long as it becomes the carbonaceous material by heat treatment, but a petroleum-based pitch or a coal-based pitch is particularly preferable. The substrate and the carbonaceous material precursor may be mixed at a temperature higher than the melting point of the carbonaceous material precursor before the heat treatment. The heat treatment temperature may be any temperature as long as the component generated by volatilization or thermal decomposition of the carbonaceous material precursor to be used becomes the carbonaceous material, but is preferably 400 ° C. or higher and 2500 ° C. or lower, more preferably 500 ° C. It is 2000 ° C. or lower, more preferably 550 ° C. or higher and 1500 ° C. or lower. The atmosphere in which the heat treatment is performed is not particularly limited, but a non-oxidizing atmosphere is preferable.

Preferred examples of the composite carbon material are the composite carbon materials 1 and 2 described later. Either of these may be selected and used, or both of them may be used in combination.
[Composite carbon material 1]
The composite carbon material 1 is the composite carbon material using one or more carbon materials having a BET specific surface area of 100 m ² / g or more and 3000 m ² / g or less as the base material. The base material is not particularly limited, but activated carbon, carbon black, template porous carbon, high specific surface area graphite, carbon nanoparticles and the like can be preferably used.

The BET specific surface area of the composite carbon material 1 is preferably 100 m ² / g or more and 1,500 m ² / g or less, more preferably 150 m ² / g or more and 1,100 m ² / g or less, and further preferably 180 m ² / g or more and 550 m. ^{It is 2} / g or less. When the BET specific surface area is 100 m ² / g or more, the pores can be appropriately retained and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited. On the other hand, when it is 1,500 m ² / g or less, the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is not impaired.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 1 is preferably 10% or more and 200% or less. This mass ratio is preferably 12% or more and 180% or less, more preferably 15% or more and 160% or less, and particularly preferably 18% or more and 150% or less. When the mass ratio of the carbonaceous material is 10% or more, the micropores of the base material can be appropriately filled with the carbonic material, and the charge / discharge efficiency of lithium ions is improved, which is good. It can show cycle durability. Further, when the mass ratio of the carbonaceous material is 200% or less, the pores can be appropriately retained and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited.

The doping amount of lithium ions per unit mass of the composite carbon material 1 is preferably 530 mAh / g or more and 2,500 mAh / g or less. It is more preferably 620 mAh / g or more and 2,100 mAh / g or less, further preferably 760 mAh / g or more and 1,700 mAh / g or less, and particularly preferably 840 mAh / g or more and 1,500 mAh / g or less.
By doping with lithium ions, the negative electrode potential is lowered. Therefore, when the negative electrode containing the lithium ion-doped composite carbon material 1 is combined with the positive electrode, the voltage of the non-aqueous lithium-type power storage element becomes high and the utilization capacity of the positive electrode becomes large. Therefore, the capacity and energy density of the obtained non-aqueous lithium-type power storage element are increased.
When the doping amount is 530 mAh / g or more, the lithium ions are well doped in the irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 1 are inserted, and the composite carbon material 1 with respect to the desired lithium amount is further doped. Can be reduced. Therefore, the film thickness of the negative electrode can be reduced, and a high energy density can be obtained. As the doping amount increases, the negative electrode potential decreases, and the input / output characteristics, energy density, and durability improve. On the other hand, when the doping amount is 2,500 mAh / g or less, there is no possibility that side effects such as precipitation of lithium metal will occur.

Hereinafter, as a preferable example of the composite carbon material 1, the composite carbon material 1a using activated carbon as the base material will be described.
The composite carbon material 1a has a mesopore amount of Vm1 (cc / g) derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method, and a micropore amount derived from pores having a diameter of less than 20 Å calculated by the MP method. When Vm2 (cc / g), 0.010 ≦ Vm1 ≦ 0.300 and 0.001 ≦ Vm2 ≦ 0.650 are preferable.
The mesopore amount Vm1 is more preferably 0.010 ≦ Vm1 ≦ 0.225, and further preferably 0.010 ≦ Vm1 ≦ 0.200. The micropore amount Vm2 is more preferably 0.001 ≦ Vm2 ≦ 0.200, further preferably 0.001 ≦ Vm2 ≦ 0.150, and particularly preferably 0.001 ≦ Vm2 ≦ 0.100.

When the mesopore amount Vm1 is 0.300 cc / g or less, the BET specific surface area can be increased, the doping amount of lithium ions can be increased, and the bulk density of the negative electrode can be increased. Can be thinned. Further, when the micropore amount Vm2 is 0.650 cc / g or less, high charge / discharge efficiency for lithium ions can be maintained. On the other hand, when the mesopore amount Vm1 and the micropore amount Vm2 are equal to or higher than the lower limit (0.010 ≦ Vm1, 0.001 ≦ Vm2), high input / output characteristics can be obtained.

The BET specific surface area of the composite carbon material 1a is preferably 100 m ² / g or more and 1,500 m ² / g or less, more preferably 150 m ² / g or more and 1,100 m ² / g or less, and further preferably 180 m ² / g or more and 550 m. ^{It is 2} / g or less. When the BET specific surface area is 100 m ² / g or more, the pores can be appropriately retained and the diffusion of lithium ions becomes good, so that high input / output characteristics can be exhibited. Moreover, since the doping amount of lithium ions can be increased, the negative electrode can be thinned. On the other hand, when it is 1,500 m ² / g or less, the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is not impaired.

The average pore diameter of the composite carbon material 1a is preferably 20 Å or more, more preferably 25 Å or more, and even more preferably 30 Å or more, from the viewpoint of providing high input / output characteristics. On the other hand, from the viewpoint of increasing the energy density, the average pore diameter is preferably 65 Å or less, and more preferably 60 Å or less.

The average particle size of the composite carbon material 1a is preferably 1 μm or more and 10 μm or less. The lower limit is more preferably 2 μm or more, still more preferably 2.5 μm or more. The upper limit is more preferably 6 μm or less, still more preferably 4 μm or less. Good durability is maintained when the average particle size is 1 μm or more and 10 μm or less.

The atomic number ratio (H / C) of hydrogen atom / carbon atom of the composite carbon material 1a is preferably 0.05 or more and 0.35 or less, and more preferably 0.05 or more and 0.15 or less. .. When the H / C is 0.35 or less, the structure of the carbonaceous material adhered to the surface of the activated carbon (typically, the polycyclic aromatic conjugated structure) is well developed and the capacity (energy). Density) and charge / discharge efficiency increase. On the other hand, when the H / C is 0.05 or more, carbonization does not proceed excessively, so that a good energy density can be obtained. H / C is measured by an elemental analyzer.

The composite carbon material 1a has an amorphous structure derived from the activated carbon of the base material, and at the same time, has a crystal structure mainly derived from the adhered carbonaceous material. According to the X-ray wide-angle diffraction method, the composite carbon material 1a has a (002) plane spacing d002 of 3.60 Å or more and 4.00 Å or less, and crystallites in the c-axis direction obtained from the half-value width of this peak. The size Lc is preferably 8.0 Å or more and 20.0 Å or less, d002 is 3.60 Å or more and 3.75 Å or less, and the crystallite size Lc in the c-axis direction obtained from the half-value width of this peak is 11. More preferably, it is 0 Å or more and 16.0 Å or less.

The activated carbon used as the base material of the composite carbon material 1a is not particularly limited as long as the obtained composite carbon material 1a exhibits desired properties. For example, commercially available products obtained from various raw materials such as petroleum-based, coal-based, plant-based, and polymer-based can be used. In particular, it is preferable to use activated carbon powder having an average particle size of 1 μm or more and 15 μm or less, and more preferably 2 μm or more and 10 μm or less.

In order to obtain the composite carbon material 1a having the pore distribution range specified in the present embodiment, the pore distribution of the activated carbon used for the base material is important.
In the activated carbon, the amount of mesopores derived from pores having a diameter of 20 Å or more and 500 Å or less calculated by the BJH method is V1 (cc / g), and the amount of micropores derived from pores having a diameter of less than 20 Å calculated by the MP method. When V2 (cc / g) is set, it is preferable that 0.050 ≦ V1 ≦ 0.500, 0.005 ≦ V2 ≦ 1.000, and 0.2 ≦ V1 / V2 ≦ 20.0.

Regarding the mesopore amount V1, 0.050 ≦ V1 ≦ 0.350 is more preferable, and 0.100 ≦ V1 ≦ 0.300 is even more preferable. Regarding the micropore amount V2, 0.005 ≦ V2 ≦ 0.850 is more preferable, and 0.100 ≦ V2 ≦ 0.800 is even more preferable. Regarding the ratio of mesopore amount / micropore amount, 0.22 ≦ V1 / V2 ≦ 15.0 is more preferable, and 0.25 ≦ V1 / V2 ≦ 10.0 is even more preferable. When the mesopore amount V1 of the activated carbon is 0.500 or less and the micropore amount V2 is 1.000 or less, an appropriate amount of carbonaceous material is obtained in order to obtain the pore structure of the composite carbon material 1a in the present embodiment. Since it is sufficient to adhere the material, it becomes easy to control the pore structure. On the other hand, when the mesopore amount V1 of the activated carbon is 0.050 or more, the micropore amount V2 is 0.005 or more, V1 / V2 is 0.2 or more, and V1 / V2 is 20.0. The structure can be easily obtained even in the following cases.

The carbonaceous material precursor used as a raw material of the composite carbon material 1a is a solid, liquid, or solvent-soluble organic material capable of adhering the carbonic material to activated carbon by heat treatment. Examples of the carbonaceous material precursor include pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenol resin, etc.) and the like. Among these carbonaceous material precursors, it is preferable to use an inexpensive pitch in terms of manufacturing cost. Pitches are roughly divided into petroleum-based pitches and coal-based pitches. Examples of petroleum-based pitches include distillation residue of crude oil, fluid contact decomposition residue (decant oil, etc.), bottom oil derived from thermal crackers, ethylene tar obtained during naphtha cracking, and the like.

When pitch is used, the pitch is heat-treated in the coexistence with activated carbon, and the volatile component or pyrolysis component of the pitch is thermally reacted on the surface of the activated carbon to coat the activated carbon with a carbonaceous material. 1a is obtained. In this case, the adhesion of the volatile component or the thermal decomposition component of the pitch into the activated carbon pores proceeds at a temperature of about 200 to 500 ° C., and the reaction in which the adhered component becomes a carbonaceous material proceeds at 400 ° C. or higher. To do. The peak temperature (maximum temperature reached) during the heat treatment is appropriately determined depending on the characteristics of the obtained composite carbon material 1a, the thermal reaction pattern, the thermal reaction atmosphere, etc., but is preferably 400 ° C. or higher, more preferably 400 ° C. or higher. Is 450 ° C. to 1,000 ° C., more preferably about 500 to 800 ° C. The time for maintaining the peak temperature during the heat treatment is preferably 30 minutes to 10 hours, more preferably 1 hour to 7 hours, and further preferably 2 hours to 5 hours. For example, when heat-treating at a peak temperature of about 500 to 800 ° C. for 2 hours to 5 hours, it is considered that the carbonaceous material adhered to the surface of the activated carbon is a polycyclic aromatic hydrocarbon. ..

The softening point of the pitch used is preferably 30 ° C. or higher and 250 ° C. or lower, and more preferably 60 ° C. or higher and 130 ° C. or lower. A pitch having a softening point of 30 ° C. or higher does not hinder handleability and can be charged with high accuracy. Since a pitch having a softening point of 250 ° C. or lower contains a large amount of relatively low-molecular-weight compounds, it is possible to adhere to fine pores in the activated carbon by using the pitch.
As a specific method for producing the composite carbon material 1a, for example, the activated carbon is heat-treated in an inert atmosphere containing a hydrocarbon gas volatilized from the carbon material precursor, and the carbon material is adhered in the vapor phase. The method can be mentioned. Further, a method in which the activated carbon and the carbonaceous material precursor are mixed in advance and heat-treated, or a method in which the carbonic material precursor dissolved in a solvent is applied to the activated carbon, dried, and then heat-treated is also possible.

The mass ratio of the carbonaceous material to the activated carbon in the composite carbon material 1a is preferably 10% or more and 100% or less, and more preferably 15% or more and 80% or less. When the mass ratio of the carbonaceous material is 10% or more, the micropores of the activated carbon can be appropriately filled with the carbonic material, and the charge / discharge efficiency of lithium ions is improved, so that the cycle durability is improved. Is not impaired. Further, when the mass ratio of the carbonaceous material is 100% or less, the pores of the composite carbon material 1a are appropriately retained and the specific surface area is maintained large. Therefore, from the result that the doping amount of lithium ions can be increased, high output density and high durability can be maintained even if the negative electrode is thinned.

[Composite carbon material 2]
The composite carbon material 2 is the composite carbon material using one or more carbon materials having a BET specific surface area of 0.5 m ² / g or more and 80 m ² / g or less as the base material. The base material is not particularly limited, but natural graphite, artificial graphite, low crystal graphite, hard carbon, soft carbon, carbon black and the like can be preferably used.

BET specific surface area of the composite carbon material 2, ^{1 m} 2 / g or more ^{50 m} 2 / g or less, more preferably 1.5 m ² / g or more ^{40 m} 2 / g or less, more preferably ^2m 2 / g or more ^{25 m} 2 / It is less than or equal to g. When the BET specific surface area is 1 m ² / g or more, a sufficient reaction field with lithium ions can be secured, so that high input / output characteristics can be exhibited. On the other hand, when it is 50 m ² / g or less, the charge / discharge efficiency of lithium ions is improved and the decomposition reaction of the non-aqueous electrolyte solution during charge / discharge is suppressed, so that high cycle durability can be exhibited.

The average particle size of the composite carbon material 2 is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and further preferably 3 μm or more and 6 μm or less. When the average particle size is 1 μm or more, the charge / discharge efficiency of lithium ions can be improved, so that high cycle durability can be exhibited. On the other hand, if it is 10 μm or less, the reaction area between the composite carbon material 2 and the non-aqueous electrolytic solution increases, so that high input / output characteristics can be exhibited.

The mass ratio of the carbonaceous material to the base material in the composite carbon material 2 is preferably 1% or more and 30% or less, more preferably 1.2% or more and 25% or less, and further preferably 1.5% or more and 20% or less. is there. When the mass ratio of the carbonaceous material is 1% or more, the carbonaceous material can sufficiently increase the reaction sites with lithium ions, and the desolvation of lithium ions becomes easy, so that high input / output characteristics are exhibited. be able to. On the other hand, when the mass ratio of the carbonaceous material is 20% or less, the diffusion of lithium ions between the carbonic material and the base material in the solid can be well maintained, so that high input / output characteristics can be exhibited. .. Moreover, since the charge / discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

The doping amount of lithium ions per unit mass of the composite carbon material 2 is preferably 50 mAh / g or more and 700 mAh / g or less, preferably 70 mAh / g or more and 650 mAh / g or less, and more preferably 90 mAh / g or more and 600 mAh or less. It is / g or less, more preferably 100 mAh / g or more and 550 mAh / g or less.
Since the negative electrode potential is lowered by doping with lithium ions, when the negative electrode containing the lithium ion-doped composite carbon material 2 is combined with the positive electrode, the voltage of the non-aqueous lithium storage element becomes high and the positive electrode The used capacity increases. Therefore, the capacity and energy density of the obtained non-aqueous lithium-type power storage element are increased.
When the doping amount is 50 mAh / g or more, the lithium ions are well doped in the irreversible sites that cannot be desorbed once the lithium ions in the composite carbon material 2 are inserted, so that a high energy density can be obtained. As the doping amount increases, the negative electrode potential decreases, and the input / output characteristics, energy density, and durability improve.
On the other hand, when the doping amount is 700 mAh / g or less, there is no possibility that side effects such as precipitation of lithium metal will occur.

Hereinafter, as a preferable example of the composite carbon material 2, the composite carbon material 2a using a graphite material as the base material will be described.
The average particle size of the composite carbon material 2a is preferably 1 μm or more and 10 μm or less, more preferably 2 μm or more and 8 μm or less, and further preferably 3 μm or more and 6 μm or less. When the average particle size is 1 μm or more, the charge / discharge efficiency of lithium ions can be improved, so that high cycle durability can be exhibited. On the other hand, if it is 10 μm or less, the reaction area between the composite carbon material 2a and the non-aqueous electrolytic solution increases, so that high input / output characteristics can be exhibited.

The BET specific surface area of the composite carbon material 2a is preferably 1 m ² / g or more and 20 m ² / g or less, and more preferably 1 m ² / g or more and 15 m ² / g or less. When the BET specific surface area is 1 m ² / g or more, a sufficient reaction field with lithium ions can be secured, so that high input / output characteristics can be exhibited. On the other hand, when it is 20 m ² / g or less, the charge / discharge efficiency of lithium ions is improved and the decomposition reaction of the non-aqueous electrolyte solution during charge / discharge is suppressed, so that high cycle durability can be exhibited.

The graphite material used as the base material is not particularly limited as long as the obtained composite carbon material 2a exhibits desired properties. For example, artificial graphite, natural graphite, graphitized mesophase carbon globules, graphite whiskers and the like can be used. The average particle size of the graphite material is preferably 1 μm or more and 10 μm or less, and more preferably 2 μm or more and 8 μm or less.

The carbonaceous material precursor used as a raw material of the composite carbon material 2a is a solid, liquid, or solvent-soluble organic material capable of combining the carbonic material with the graphite material by heat treatment. Examples of the carbonaceous material precursor include pitch, mesocarbon microbeads, coke, synthetic resin (for example, phenol resin, etc.) and the like. Among these carbonaceous material precursors, it is preferable to use an inexpensive pitch in terms of manufacturing cost. Pitches are roughly divided into petroleum-based pitches and coal-based pitches. Examples of petroleum-based pitches include distillation residue of crude oil, fluid contact decomposition residue (decant oil, etc.), bottom oil derived from thermal crackers, ethylene tar obtained during naphtha cracking, and the like.

The mass ratio of the carbonaceous material to the graphite material in the composite carbon material 2a is preferably 1% or more and 10% or less, more preferably 1.2% or more and 8% or less, still more preferably 1.5% or more and 6% or less. Even more preferably, it is 2% or more and 5% or less. When the mass ratio of the carbonaceous material is 1% or more, the carbonaceous material can sufficiently increase the reaction sites with lithium ions, and the desolvation of lithium ions becomes easy, so that high input / output characteristics are exhibited. be able to. On the other hand, when the mass ratio of the carbonaceous material is 20% or less, the diffusion of lithium ions between the carbonic material and the graphite material in the solid can be well maintained, so that high input / output characteristics can be exhibited. .. Moreover, since the charge / discharge efficiency of lithium ions can be improved, high cycle durability can be exhibited.

[Arbitrary component]
If necessary, the negative electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersant stabilizer in addition to the negative electrode active material.
The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor-grown carbon fiber. The amount of the conductive filler used is preferably 0 parts by mass or more and 30 parts by mass or less, more preferably 0 parts by mass or more and 20 parts by mass or less, and further preferably 0 parts by mass or more with respect to 100 parts by mass of the negative electrode active material. It is 15 parts by mass or less.

The binder is not particularly limited, but for example, PVdF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), polyimide, latex, styrene-butadiene copolymer, fluororubber, acrylic copolymer. Etc. can be used. The amount of the binder used is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 2 parts by mass or more and 27 parts by mass or less, and further preferably 3 parts by mass or more with respect to 100 parts by mass of the negative electrode active material. It is 25 parts by mass or less. When the amount of the binder is 1% by mass or more, sufficient electrode strength is exhibited. On the other hand, when the amount of the binder is 30 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of lithium ions into the negative electrode active material.

The dispersion stabilizer is not particularly limited, but for example, PVP (polyvinylpyrrolidone), PVA (polyvinyl alcohol), a cellulose derivative and the like can be used. The amount of the binder used is preferably 0 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the negative electrode active material. When the amount of the dispersion stabilizer is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the entry and exit of lithium ions into the negative electrode active material.

[Negative electrode current collector]
The material constituting the negative electrode current collector is preferably a metal foil having high electron conductivity and not deteriorating due to elution into a non-aqueous electrolyte solution and reaction with an electrolyte or ions. Such metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. Copper foil is preferable as the negative electrode current collector in the non-aqueous lithium power storage device of the present embodiment.
The metal foil may be a normal metal foil having no irregularities or through holes, a metal foil having irregularities subjected to embossing, chemical etching, electrolytic precipitation, blasting, etc., expanded metal, punching metal, etc. , A metal foil having through holes 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 and strength of the negative electrode can be sufficiently maintained, but is preferably 1 to 100 μm, for example.

[Manufacturing of negative electrode]
The negative electrode has a negative electrode active material layer on one side or both sides of the negative electrode current collector. In a typical embodiment, the negative electrode active material layer is fixed to the negative electrode current collector.
The negative electrode can be manufactured by a technique for manufacturing electrodes in known lithium ion batteries, electric double layer capacitors and the like. For example, various materials including the negative electrode active material are dispersed or dissolved in water or an organic solvent to prepare a slurry coating liquid, and this coating liquid is applied to one or both sides of the negative electrode current collector. A negative electrode can be obtained by forming a coating film and drying it. Further, the obtained negative electrode may be pressed to adjust the film thickness and bulk density of the negative electrode active material layer. It is also possible to dry-mix various materials including the negative electrode active material without using a solvent, press-mold the obtained mixture, and then attach it to the negative electrode current collector using a conductive adhesive.

In the preparation of the coating liquid, a part or all of various material powders including the negative electrode active material are dry-blended, and then water or an organic solvent and / or a liquid in which a binder or a dispersion stabilizer is dissolved or dispersed therein. Alternatively, a slurry-like substance may be added. Further, various material powders containing a negative electrode active material may be added to a liquid or slurry substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. The preparation of the coating liquid is not particularly limited, but preferably a disperser such as a homodisper, a multi-axis disperser, a planetary mixer, or a thin film swirling high-speed mixer can be used. In order to obtain a coating liquid in a good dispersed state, it is preferable to disperse at a peripheral speed of 1 m / s or more and 50 m / s or less. A peripheral speed of 1 m / s or more is preferable because various materials are satisfactorily dissolved or dispersed. Further, when it is 50 m / s or less, various materials are not destroyed by heat or shearing force due to dispersion, and reaggregation does not occur, which is preferable.

The viscosity (ηb) of the coating liquid is preferably 1,000 mPa · s or more and 20,000 mPa · s or less, more preferably 1,500 mPa · s or more and 10,000 mPa · s or less, and further preferably 1,700 mPa · s or more. It is 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during coating film formation is suppressed, and the coating film width and thickness can be satisfactorily controlled. On the other hand, when it is 20,000 mPa · s or less, the pressure loss in the flow path of the coating liquid when using the coating machine is small and stable coating can be performed, and the coating film thickness can be controlled to be less than the desired coating film thickness.
The TI value (thixotropy index value) of the coating liquid is preferably 1.1 or more, more preferably 1.2 or more, and further preferably 1.5 or more. When the TI value is 1.1 or more, the coating film width and thickness can be satisfactorily controlled.

The formation of the coating film is not particularly limited, but a coating machine such as a die coater, a comma coater, a knife coater, or a gravure coating machine can be preferably used. The coating film may be formed by single-layer coating or multi-layer coating. The coating speed is preferably 0.1 m / min or more and 100 m / min or less, more preferably 0.5 m / min or more and 70 m / min or less, and further preferably 1 m / min or more and 50 m / min or less. If the coating speed is 0.1 m / min or more, stable coating can be performed. On the other hand, if it is 100 m / min or less, sufficient coating accuracy can be ensured.

The drying of the coating film is not particularly limited, but a drying method such as hot air drying or infrared (IR) drying can be preferably used. The coating film may be dried at a single temperature, or may be dried at different temperatures in multiple stages. Moreover, you may dry by combining a plurality of drying methods. The drying temperature is preferably 25 ° C. or higher and 200 ° C. or lower, more preferably 40 ° C. or higher and 180 ° C. or lower, and further preferably 50 ° C. or higher and 160 ° C. or lower. When the drying temperature is 25 ° C. or higher, the solvent in the coating film can be sufficiently volatilized. On the other hand, when the temperature is 200 ° C. or lower, cracks in the coating film due to rapid volatilization of the solvent, uneven distribution of the binder due to migration, and oxidation of the negative electrode current collector and the negative electrode active material layer can be suppressed.

The press of the negative electrode is not particularly limited, but a press machine such as a hydraulic press machine or a vacuum press machine can be preferably used. The film thickness, bulk density, and electrode strength of the negative electrode active material layer can be adjusted by the press pressure, the gap, and the surface temperature of the press portion, which will be described later. The press pressure is preferably 0.5 kN / cm or more and 20 kN / cm or less, more preferably 1 kN / cm or more and 10 kN / cm or less, and further preferably 2 kN / cm or more and 7 kN / cm or less. When the press pressure is 0.5 kN / cm or more, the electrode strength can be sufficiently increased. On the other hand, when it is 20 kN / cm or less, the negative electrode does not bend or wrinkle, and the desired negative electrode active material layer film thickness and bulk density can be adjusted. Further, the gap between the press rolls can be set to an arbitrary value according to the film thickness of the desired negative electrode active material layer and the negative electrode film thickness after drying so as to have a bulk density. Further, the pressing speed can be set to an arbitrary speed at which the negative electrode does not bend or wrinkle. Further, the surface temperature of the pressed portion may be room temperature or may be heated if necessary. The lower limit of the surface temperature of the pressed portion at the time of heating is preferably the melting point of the binder to be used of minus 60 ° C. or higher, more preferably 45 ° C. or higher, still more preferably 30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion when heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably 30 ° C. or lower, and further preferably 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as a binder, the temperature is preferably 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further preferably 120 ° C. or higher. It is to heat to 170 ° C. or lower. When a styrene-butadiene copolymer (melting point 100 ° C.) is used as the binder, it is preferably heated to 40 ° C. or higher and 150 ° C. or lower, more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° C. It is to heat to 120 ° C. or higher and 120 ° C. or lower.
The melting point of the binder can be determined from the endothermic peak position of DSC (Differential Scanning Calorimetry, differential scanning calorimetry). For example, using a differential scanning calorimeter "DSC7" manufactured by PerkinElmer, 10 mg of sample resin is set in a measurement cell, and the temperature rises from 30 ° C. to 250 ° C. at a heating 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.
Further, the press may be performed a plurality of times while changing the conditions of the press pressure, the gap, the speed, and the surface temperature of the press portion.

The thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per side. The lower limit of the thickness of the negative electrode active material layer is more preferably 7 μm or more, and more preferably 10 μm or more. The upper limit of the thickness of the negative electrode active material layer is more preferably 80 μm or less, and more preferably 60 μm or less. When the thickness of the negative electrode active material layer is 5 μm or more, no streaks or the like are generated when the negative electrode active material layer is applied, and the coatability is excellent. On the other hand, when the thickness of the negative electrode active material layer is 100 μm or less, high energy density can be developed by reducing the cell volume. The thickness of the negative electrode active material layer when the current collector has through holes or irregularities means the average value of the thickness per side of the portion of the current collector that does not have through holes or irregularities.

The bulk density of the negative electrode active material layer is preferably 0.30 g / cm ³ or more and 1.8 g / cm ³ or less, more preferably 0.40 g / cm ³ or more and 1.5 g / cm ³ or less, and further preferably 0. .45g / cm ³ or more 1.3g / cm ³ or less. When the bulk density is 0.30 g / cm ³ or more, sufficient strength can be maintained and sufficient conductivity between the negative electrode active materials can be exhibited. On the other hand, if it is 1.8 g / cm ³ or less, pores capable of sufficiently diffusing ions can be secured in the negative electrode active material layer.

The amount of lithium ions doped in the negative electrode active material in the non-aqueous lithium-type power storage device at the time of shipment and after use in the present embodiment can be known, for example, as follows.
First, the negative electrode active material layer in the present embodiment is washed with ethyl methyl carbonate or dimethyl carbonate and air-dried, and then an extract extracted with a mixed solvent consisting of methanol and isopropanol and an extracted negative electrode active material layer are obtained. This extraction is typically performed in an Ar box at an environmental temperature of 23 ° C.
The amount of lithium contained in the extract thus obtained and the negative electrode active material layer after extraction is quantified using, for example, ICP-MS (inductively coupled plasma mass spectrometer), and the amount thereof is quantified. By obtaining the total, the amount of lithium ion doped in the negative electrode active material can be known. The obtained value may be allocated by the amount of the negative electrode active material used for extraction, and the numerical value in the above unit may be calculated.

For the primary particle size, the powder is photographed in several fields with an electron microscope, and the particle size of the particles in those fields of view is measured by about 2,000 to 3,000 using a fully automatic image processing device or the like. Can be obtained by a method in which the value obtained by arithmetically averaging is used as the primary particle size.

[Separator]
The positive electrode precursor and the negative electrode are laminated or wound via a separator to form an electrode laminate or an electrode wound body having the positive electrode precursor, the negative electrode and the separator.
As the separator, a polyethylene microporous film or polypropylene microporous film used in a lithium ion secondary battery, a cellulose non-woven paper used in an electric double layer capacitor, or the like can be used. A film made of organic or inorganic fine particles may be laminated on one side or both sides of these separators. Further, organic or inorganic fine particles may be contained inside the separator.
The thickness of the separator is preferably 5 μm or more and 35 μm or less. A thickness of 5 μm or more is preferable because self-discharge due to internal microshorts tends to be small. On the other hand, when the thickness is 35 μm or less, the output characteristics of the power storage element tend to be high, which is preferable.
The film made of organic or inorganic fine particles is preferably 1 μm or more and 10 μm or less. A thickness of 1 μm or more is preferable because self-discharge due to internal microshorts tends to be small. On the other hand, when the thickness is 10 μm or less, the output characteristics of the power storage element tend to be high, which is preferable.

[assembly]
The electrode laminate obtained in the cell assembly step is a laminate obtained by laminating a positive electrode precursor and a negative electrode cut into a single-wafer shape via a separator, and connecting a positive electrode terminal and a negative electrode terminal to the laminate. Further, the electrode winding body is formed by winding a positive electrode precursor and a negative electrode via a separator, and connecting a positive electrode terminal and a negative electrode terminal to the winding body. The shape of the electrode winding body may be cylindrical or flat.
The method of connecting the positive electrode terminal and the negative electrode terminal is not particularly limited, but a method such as resistance welding or ultrasonic welding is used.

[Exterior body]
As the exterior body, a metal can, a laminated packaging material, or the like can be used.
The metal can is preferably made of aluminum. As the laminated packaging material, a film obtained by laminating a metal foil and a resin film is preferable, and a three-layer structure composed of an outer layer resin film / metal foil / interior resin film is exemplified. 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 preferably used. The metal foil is for preventing the permeation of water and gas, and a foil of copper, aluminum, stainless steel or the like can be preferably used. Further, the interior resin film is for protecting the metal foil from the electrolytic solution stored inside and for melt-sealing the exterior body at the time of heat sealing, and polyolefins, acid-modified polyolefins and the like can be preferably used.

[Storage in the exterior]
The electrode laminate or electrode wound body to which the positive electrode terminal and the negative electrode terminal are connected should be housed in an exterior body typified by a metal can or a laminated packaging material, and sealed with only one opening left. Is preferable. The sealing method of the outer body is not particularly limited, but when a laminated packaging material is used, a method such as heat sealing or impulse sealing is used.

[Dry]
It is preferable that the electrode laminate or the electrode wound body is dried to remove the residual solvent. The drying method is not limited, but it is dried by vacuum drying or the like. The drying step may be performed before connecting the positive electrode terminal and the negative electrode terminal to the electrode laminate or the electrode wound body, or may be performed after the connection. Further, the electrode laminate or the electrode wound body may be performed before being stored in the exterior material, or may be performed after the electrode wound body is stored. The residual solvent is preferably 1.5 wt.% Or less per weight of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5 wt.%, The solvent remains in the system and deteriorates the self-discharge characteristics and the cycle characteristics, which is not preferable.

[Electrolytic solution]
The electrolytic solution according to this embodiment is a non-aqueous electrolytic solution. That is, this electrolytic solution contains a non-aqueous solvent described later. The non-aqueous electrolyte solution contains 0.5 mol / L or more of lithium salt based on the total amount of the non-aqueous electrolyte solution. That is, the non-aqueous electrolyte solution contains lithium ions as an electrolyte.

The non-aqueous electrolyte solution is, for example, (LiN (SO ₂ F) ₂ ), LiN (SO ₂ CF ₃ ) ₂ , 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), LiC (SO ₂ F) ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂ C ₂ F ₅₎ ) ₃ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiPF ₆ , LiBF _4, etc. can be used alone, or two or more of them may be mixed and used. It is preferable to contain LiPF ₆ and / or LiN (SO ₂ F) ₂ because it can exhibit high conductivity.
The lithium salt concentration in the non-aqueous electrolyte solution is preferably 0.5 mol / L or more, more preferably 0.5 to 2.0 mol / L. When the lithium salt concentration is 0.5 mol / L or more, anions are sufficiently present, so that the capacity of the power storage element can be sufficiently increased. Further, when the lithium salt concentration is 2.0 mol / L or less, it is possible to prevent undissolved lithium salt from precipitating in the non-aqueous electrolyte solution and the viscosity of the electrolyte solution from becoming too high, resulting in a decrease in conductivity. It is preferable because it does not reduce the output characteristics.

The non-aqueous electrolyte solution preferably contains LiN (SO ₂ F) ₂ of 0.3 mol / L or more and 1.5 mol / L or less. More preferably, it is 0.6 mol / L or more and 1.2 mol / L or less. When LiN (SO ₂ F) ₂ is 0.3 mol / L or more, the ionic conductivity of the electrolytic solution is increased, and an appropriate amount of an electrolyte film is deposited on the negative electrode interface, which causes the electrolytic solution to decompose. Can be reduced. On the other hand, when this value is 1.5 mol / L or less, precipitation of the electrolyte salt does not occur during charging / discharging, and the viscosity of the electrolytic solution does not increase even after a long period of time.

The non-aqueous electrolyte solution preferably contains a cyclic carbonate as a non-aqueous solvent. The inclusion of the cyclic carbonate in the non-aqueous electrolyte solution is advantageous in that it dissolves a lithium salt having a desired concentration and that an appropriate amount of the lithium compound is deposited on the positive electrode active material layer. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate and the like.
The total content of the cyclic carbonate is preferably 15% by mass or more, more preferably 20% by mass or more, based on the total amount of the non-aqueous electrolyte solution. When the total content is 15% by mass or more, a lithium salt having a desired concentration can be dissolved, and high lithium ion conductivity can be exhibited. Further, an appropriate amount of lithium compound can be deposited on the positive electrode active material layer, and oxidative decomposition of the electrolytic solution can be suppressed.

The non-aqueous electrolyte solution preferably contains a chain carbonate as a non-aqueous solvent. It is advantageous that the non-aqueous electrolyte solution contains a chain carbonate in that it exhibits high lithium ion conductivity. Examples of the chain carbonate include dialkyl carbonate compounds typified by dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl carbonate and the like. Dialkyl carbonate compounds are typically unsubstituted.
The total content of the chain carbonate is preferably 30% by mass or more, more preferably 35% by mass or more, preferably 95% by mass or less, and more preferably 90% by mass or less, based on the total amount of the non-aqueous electrolyte solution. is there. When the content of the chain carbonate is 30% by mass or more, the viscosity of the electrolytic solution can be reduced and high lithium ion conductivity can be exhibited. When the total concentration is 95% by mass or less, the electrolytic solution can further contain the additives described later.

The non-aqueous electrolyte solution may further contain additives. The additive is not particularly limited, and for example, a sultone compound, cyclic phosphazene, acyclic fluorinated ether, fluorinated cyclic carbonate, cyclic carbonate, cyclic carboxylic acid ester, cyclic acid anhydride and the like may be used alone. It is possible, and two or more kinds may be mixed and used.

｛式（５）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（６）中、Ｒ^１１〜Ｒ^１４は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよく；そしてｎは０〜３の整数である。｝

｛式（７）中、Ｒ^１１〜Ｒ^１６は、水素原子、ハロゲン原子、炭素数１〜１２のアルキル基、又は炭素数１〜１２のハロゲン化アルキル基を表し、互いに同一であっても異なっていてもよい。｝ Examples of the sultone compound include sultone compounds represented by the following general formulas (5) to (7). These sultone compounds may be used alone or in combination of two or more.

{In formula (5), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be; and n is an integer from 0 to 3. }

{In formula (6), R ^{11 to} R ¹⁴ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be; and n is an integer from 0 to 3. }

{In formula (7), R ^{11 to} R ¹⁶ represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkyl halide group having 1 to 12 carbon atoms, and they are different even if they are the same. May be. }

In the present embodiment, the sultone compound represented by the general formula (5) is selected from the viewpoint of having little adverse effect on resistance and suppressing decomposition of the non-aqueous electrolyte solution at high temperature to suppress gas generation. 1,3-Propane sultone, 2,4-butane sultone, 1,4-butane sultone, 1,3-butane sultone or 2,4-pentane sultone are preferable, and the sultone compound represented by the general formula (6) is 1, 3-Propens sultone or 1,4-butene sultone is preferable, and the sultone compound represented by the general formula (7) is 1,5,2,4-dioxadithioepan 2,2,4,4-tetraoxide. As the other sultone compounds, methylenebis (benzenesulfonic acid), methylenebis (phenylmethanesulfonic acid), methylenebis (ethanesulfonic acid), methylenebis (2,4,6,trimethylbenzenesulfonic acid), and methylenebis (2). -Trifluoromethylbenzene sulfonic acid), and it is preferable to select at least one selected from these.

The total content of the sultone compound in the non-aqueous electrolyte solution of the non-aqueous lithium-type power storage device in the present embodiment is preferably 0.5% by mass to 15% by mass based on the total amount of the non-aqueous electrolyte solution. When the total content of the sultone compound in the non-aqueous electrolytic solution is 0.5% by mass or more, it is possible to suppress the decomposition of the electrolytic solution at a high temperature and suppress the gas generation. On the other hand, when the total content is 15% by mass or less, it is possible to suppress a decrease in the ionic conductivity of the electrolytic solution and maintain high input / output characteristics. Further, the content of the sultone compound present in the non-aqueous electrolyte solution of the non-aqueous lithium-type power storage element is preferably 1% by mass or more and 10% by mass or less from the viewpoint of achieving both high input / output characteristics and durability. It is preferably 3% by mass or more and 8% by mass or less.

Examples of the cyclic phosphazene include ethoxypentafluorocyclotriphosphazene, diethoxytetrafluorocyclotriphosphazene, phenoxypentafluorocyclotriphosphazene, and the like, and one or more selected from these is preferable.

The content of cyclic phosphazene in the non-aqueous electrolyte solution is preferably 0.5% by mass to 20% by mass based on the total amount of the non-aqueous electrolyte solution. When this value is 0.5% by weight or more, it is possible to suppress the decomposition of the electrolytic solution at a high temperature and suppress the gas generation. On the other hand, when this value is 20% by mass or less, the decrease in ionic conductivity of the electrolytic solution can be suppressed, and high input / output characteristics can be maintained. The content of cyclic phosphazene is more preferably 2% by mass or more and 15% by mass or less, and further preferably 4% by mass or more and 12% by mass or less.
These cyclic phosphazenes may be used alone or in combination of two or more.

Examples of the acyclic fluorine-containing ether include HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₂ CF ₂ CF ₂ H, HCF ₂ CF ₂ CH ₂ OCH ₂ CF ₂ CF ₂ H, CF ₃ CF HCF. ₂ OCH ₂ CF ₂ CFHCF _{3 and the} like can be mentioned, and among them, HCF ₂ CF ₂ OCH ₂ CF ₂ CF ₂ H is preferable from the viewpoint of electrochemical stability.

The content of the acyclic fluorinated ether is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the acyclic fluorinated ether is 0.5% by mass or more, the stability of the non-aqueous electrolyte solution against oxidative decomposition is enhanced, and a power storage element having high durability at high temperatures can be obtained. On the other hand, when the content of the acyclic fluorinated ether is 15% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be kept high, so that the concentration is high. It is possible to express input / output characteristics.
The above-mentioned acyclic fluorine-containing ether may be used alone or in combination of two or more.

The fluorine-containing cyclic carbonate is preferably used by selecting from fluoroethylene carbonate (FEC) and difluoroethylene carbonate (dFEC) from the viewpoint of compatibility with other non-aqueous solvents.
The content of the cyclic carbonate containing a fluorine atom is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the cyclic carbonate containing a fluorine atom is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the temperature is high. A power storage element with high durability can be obtained. On the other hand, when the content of the cyclic carbonate containing a fluorine atom is 10% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be kept high. It is possible to express a high degree of input / output characteristics.
The above-mentioned cyclic carbonate containing a fluorine atom may be used alone or in combination of two or more.

As for the cyclic carbonate, vinylene carbonate is preferable.
The content of the cyclic carbonate is preferably 0.5% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of the cyclic carbonate is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the durability at high temperature can be improved. A high power storage element can be obtained. On the other hand, when the content of the cyclic carbonate is 10% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, and therefore high input / output characteristics can be maintained. Can be expressed.

Examples of the cyclic carboxylic acid ester include gamma-butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like, and it is preferable to use one or more selected from these. Of these, gamma-butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

The content of the cyclic carboxylic acid ester is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 5% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of cyclic acid anhydride is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, durability at high temperature is achieved. A high power storage element can be obtained. On the other hand, when the content of the cyclic carboxylic acid ester is 5% by mass or less, the solubility of the electrolyte salt can be kept good, and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, and therefore a high degree of input / output can be maintained. It becomes possible to express the property.
The above cyclic carboxylic acid ester may be used alone or in combination of two or more.

As the cyclic acid anhydride, one or more selected from succinic anhydride, maleic anhydride, citraconic anhydride, and itaconic anhydride are preferable. Among them, it is preferable to select from succinic anhydride and maleic anhydride from the viewpoint that the production cost of the electrolytic solution can be suppressed due to industrial availability and that it is easily dissolved in the non-aqueous electrolytic solution.

The content of the cyclic acid anhydride is preferably 0.5% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass or less, based on the total amount of the non-aqueous electrolyte solution. When the content of cyclic acid anhydride is 0.5% by mass or more, a high-quality film can be formed on the negative electrode, and by suppressing the reductive decomposition of the electrolytic solution on the negative electrode, the durability at high temperature can be improved. A high power storage element can be obtained. On the other hand, when the content of the cyclic acid anhydride is 10% by mass or less, the solubility of the electrolyte salt can be kept good and the ionic conductivity of the non-aqueous electrolyte solution can be maintained high, so that high input / output It becomes possible to express the property.
The above cyclic acid anhydride may be used alone or in combination of two or more.

[Liquid injection, impregnation, sealing process]
After the assembly process is completed, the non-aqueous electrolyte solution is injected into the electrode laminate housed in the exterior material. After the completion of the liquid injection step, it is desirable to further impregnate and sufficiently immerse the positive electrode, the negative electrode, and the separator with a non-aqueous electrolytic solution. When the electrolytic solution is not immersed in at least a part of the positive electrode, the negative electrode, and the separator, the doping proceeds non-uniformly in the lithium doping step described later, so that the resistance of the obtained non-aqueous lithium storage element increases. Or the durability is reduced. The impregnation method is not particularly limited, but for example, a non-aqueous lithium-type power storage element after injection is installed in a decompression chamber with the exterior material open, and the inside of the chamber is decompressed using a vacuum pump. Then, a method of returning to atmospheric pressure can be used. After the impregnation step is completed, the non-aqueous lithium-type power storage element in which the exterior material is open is sealed while reducing the pressure.

[Lithium doping process]
In the lithium doping step, as a preferable step, a voltage is applied between the positive electrode precursor and the negative electrode to decompose the lithium carbonate, thereby decomposing the lithium carbonate in the positive electrode precursor and releasing lithium ions. By reducing lithium ions at the negative electrode, liotium ions are pre-doped into the negative electrode active material layer.
In this lithium doping step, gas such as CO ₂ is generated due to oxidative decomposition of lithium carbonate in the positive electrode precursor. Therefore, when applying a voltage, it is preferable to take measures to release the generated gas to the outside of the exterior body. As this means, for example, a method of applying a voltage with a part of the exterior body opened; a state in which an appropriate gas release means such as a gas vent valve or a gas permeable film is previously installed in the part of the exterior body. Method of applying voltage with
And so on.

[Aging process]
After completion of the lithium doping step, it is preferable to age the non-aqueous lithium power storage device. In the aging step, the solvent in the electrolytic solution is decomposed at the negative electrode, and a lithium ion permeable solid polymer film is formed on the surface of the negative electrode.
The aging method is not particularly limited, but for example, a method of reacting the solvent in the electrolytic solution in a high temperature environment can be used.

[Degassing process]
After the aging step is completed, it is preferable to further degas to surely remove the gas remaining in the electrolytic solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the electrolytic solution, the positive electrode, and the negative electrode, ion conduction is inhibited, so that the resistance of the obtained non-aqueous lithium storage element increases.
The degassing method is not particularly limited, but for example, a non-aqueous lithium-type power storage element is installed in a decompression chamber with the exterior body open, and the inside of the chamber is decompressed by using a vacuum pump. Can be used.

[Characteristic evaluation of power storage element]
[Capacitance]
In the present specification, the capacitance F (F) is a value obtained by the following method:
First, in a constant temperature bath in which the cell corresponding to the non-aqueous lithium-type power storage element is set to 25 ° C, constant current charging is performed until the current value of 2C reaches 3.8V, and then a constant voltage of 3.8V is applied. The constant voltage charging to be applied is performed for a total of 30 minutes. After that, let Q be the capacitance when constant current discharge is performed with a current value of 2C up to 2.2V. It means a value calculated by F = Q / (3.8-2.2) using the Q obtained here.
Here, the C rate of the current is a current value at which the discharge is completed in one hour when the constant current discharge is performed from the upper limit voltage to the lower limit voltage, and is referred to as 1C. In the present specification, 1C is the current value at which the discharge is completed in 1 hour when the constant current discharge is performed from the upper limit voltage of 3.8 V to the lower limit voltage of 2.2 V.

[Internal resistance]
In the present specification, the internal resistance is a value obtained by the following method, respectively:
First, the cell corresponding to the non-aqueous lithium-type power storage element is charged with a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V with a current value of 20 C, and then a constant voltage of 3.8 V is applied. The constant voltage charging is performed for a total of 30 minutes. Then, a constant current discharge is performed up to 2.2 V with a current value of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, when the voltage at the discharge time = 0 seconds obtained by extrapolating from the voltage values at the discharge times of 2 seconds and 4 seconds is set to Eo, the drop voltage ΔE = 3.8- It is a value calculated by Eo and R = ΔE / (20C (current value A)).

[Electric energy]
In the present specification, the electric energy E (Wh) is a value obtained by the following method:
It refers to the value calculated by F × (3.8 ² -2.2 ² ) / 7200 using the capacitance F (F) calculated by the method described above.

[volume]
The volume of the power storage element is not particularly specified, but the volume of the portion of the electrode laminate or electrode wound body in which the positive electrode active material layer and the negative electrode active material layer are stacked is the volume of the portion housed by the exterior material. Point to.
For example, in the case of an electrode laminate or an electrode wound body housed by a laminate film, a region of the electrode laminate or the electrode wound body in which the positive electrode active material layer and the negative electrode active material layer are present is cup-molded. Although it is housed in the laminated film, the volume (V ₁ ) of this power storage element is the outer dimension length (l ₁ ) and outer dimension width (w ₁ ) of the cup-molded portion, and the storage including the laminated film. It is calculated by V ₁ = l ₁ × w ₁ × t _{1 according} to the thickness of the element (t ₁ ).
In the case of an electrode laminate or an electrode winding body housed in a square metal can, the volume of the power storage element is simply the volume of the outer dimension of the metal can. That is, the volume (V ₂ ) of this power storage element depends on the outer dimension length (l ₂ ), outer dimension width (w ₂ ), and outer dimension thickness (t ₂ ) of the square metal can, and V ₂ = l ₂ It is calculated by × w ₂ × t ₂ .
Further, even in the case of an electrode winding body housed in a cylindrical metal can, the volume of the power storage element in the outer dimension of the metal can is used. That is, the volume (V ₃ ) of this power storage element depends on the outer radius (r) and the outer dimension length (l ₃ ) of the bottom surface or the upper surface of the cylindrical metal can, and V ₃ = 3.14 × r × r. It is calculated by × l ₃ .

[High load charge / discharge cycle test]
In the present specification, the resistance increase rate after the high load charge / discharge cycle test is measured by the following method:
First, the cell corresponding to the non-aqueous lithium-type power storage element is charged at a constant current in a constant temperature bath set at 25 ° C. until it reaches 3.8 V at a current value of 300 C, and then 2.2 V at a current value of 300 C. Constant current discharge is performed until reaches. When the charge / discharge process is repeated 60,000 times and the internal resistance is measured before the start of the test and after the end of the test, the internal resistance before the start of the test is Ra (Ω) and the internal resistance after the end of the test is Rc (Ω). The resistance increase rate after the high load charge / discharge cycle test before the start of the test is calculated by Rc / Ra.

In the non-aqueous lithium storage element of this embodiment, the initial internal resistance at a cell voltage of 4 V is Ra (Ω), the capacitance is F (F), the electric energy is E (Wh), and the volume of the storage element is V. When (L) is set, the following:
(A) The product Ra / F of Ra and F is 0.3 or more and 3.0 or less;
(B) E / V is 15 or more and 50 or less;
It is preferable that the above conditions are satisfied at the same time.

Regarding (a), Ra and F are preferably 3.0 or less, more preferably 1.9 or less, and further, from the viewpoint of developing sufficient charge capacity and discharge capacity with respect to a large current. It is preferably 1.6 or less. When Ra and F are not more than the above upper limit values, a power storage element having excellent input / output characteristics can be obtained. Therefore, by combining a power storage system using a power storage element with, for example, a high-efficiency engine, it is possible to sufficiently withstand a high load applied to the power storage element, which is preferable.

Regarding (b), the E / V is preferably 15 or more, more preferably 18 or more, and further preferably 20 or more, from the viewpoint of developing a sufficient charge capacity and discharge capacity. When the E / V is equal to or higher than the above lower limit value, a power storage element having an excellent volumetric energy density can be obtained. Therefore, when a power storage system using a power storage element is used in combination with, for example, an engine of an automobile, it is possible to install the power storage system in a limited narrow space in the automobile, which is preferable.

The non-aqueous lithium power storage element of the present embodiment stores the initial internal resistance at a cell voltage of 4 V at Ra (Ω), a cell voltage of 4 V, and an ambient temperature of 60 ° C. for 2 months, and then stores the internal resistance at a cell voltage of 4 V. The internal resistance is Rc (Ω) after 60,000 charge / discharge cycles at a cell voltage of 2.2 V to 3.8 V and a rate of 300 C at an ambient temperature of 25 ° C. with a resistance of Rb (Ω). When, the following:
(C) Rb / Ra is 3.0 or less;
(D) The amount of gas generated when stored for 2 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 30 × 10 ^-3 cc / F or less at 25 ° C.;
(E) Rc / Ra is 0.9 or more and 2.0 or less;
Is preferably satisfied at the same time.

Regarding (c), Rb / Ra is preferably 3.0 or less from the viewpoint of developing sufficient charge capacity and discharge capacity for a large current when exposed to a high temperature environment for a long time. , More preferably 2.0 or less, still more preferably 1.5 or less. When Rc / Ra is not more than the above upper limit value, stable and excellent output characteristics can be obtained for a long period of time, which leads to a long life of the device.

Regarding (d), the amount of gas generated when stored for 2 months at a cell voltage of 4.0 V and an environmental temperature of 60 ° C. is 25 ° C. from the viewpoint that the generated gas does not deteriorate the characteristics of the device. The value measured in 1 is preferably 25 × 10 ^-3 cc / F or less, more preferably 16 × 10 ^-3 cc / F or less, and further preferably 6.0 × 10 ^-3 cc / F or less. Is. When the amount of gas generated under the above conditions is equal to or less than the above upper limit value, there is no possibility that the cell will expand due to gas generation even when the device is exposed to a high temperature for a long period of time. Therefore, a power storage element having sufficient safety and durability can be obtained.

Regarding (e), the resistance increase rate Rc / Ra after the high load charge / discharge cycle test is preferably 2.0 or less, more preferably 1.5 or less, and further preferably 1.2 or less. .. If the resistance increase rate after the high load charge / discharge cycle test is not more than the above upper limit value, the characteristics of the device are maintained even if charging / discharging is repeated. Therefore, it is possible to stably obtain excellent output characteristics for a long period of time, which leads to a long life of the device.

In the non-aqueous lithium type power storage element of the present embodiment, the initial internal resistance at a cell voltage of 4 V is Ra (Ω), the capacitance is F (F), the electric energy is E (Wh), and the volume of the power storage element is V. (L), the internal resistance was Rc (Ω) after 60,000 charge / discharge cycles at a cell voltage of 2.2 V to 3.8 V and a rate of 300 C at an ambient temperature of 25 ° C. When:
(A) The product Ra / F of Ra and F is 0.3 or more and 3.0 or less;
(B) E / V is 15 or more and 50 or less;
(E) Rc / Ra is 0.9 or more and 2.0 or less;
It is preferable that all of the above are satisfied.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[Crushing lithium carbonate]
200 g of lithium carbonate having an average particle diameter of 53 μm is cooled to -196 ° C. with liquid nitrogen using a crusher (liquid nitrogen bead mill LNM) manufactured by Imex, and then using dry ice beads at a peripheral speed of 10.0 m / s. Was crushed for 10 minutes. When the average particle size of lithium carbonate 1 obtained by preventing thermal denaturation at -196 ° C. and brittle fracture was measured, the charged lithium carbonate particle size was determined to be 4.7 μm.

[Preparation of positive electrode precursor]
[Preparation of activated carbon 1]
The crushed coconut shell carbide was carbonized in nitrogen at 500 ° C. for 3 hours in a small carbonization furnace to obtain carbonized material. The obtained carbide was put into an activation furnace, and 1 kg / h of steam was introduced into the activation furnace in a state of being heated by the preheating furnace, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbon was taken out and cooled in a nitrogen atmosphere to obtain activated activated carbon. The obtained activated carbon was washed with water for 10 hours and then drained. Then, after drying in an electric dryer maintained at 115 ° C. for 10 hours, activated carbon 1 was obtained by pulverizing with a ball mill for 1 hour. The average particle size of this activated carbon 1 was 4.2 μm as a result of measuring the average particle size using a laser diffraction type particle size distribution measuring device (SALD-2000J) manufactured by Shimadzu Corporation. In addition, the pore distribution was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 2360 m ² / g, the mesopore amount (V1) was 0.52 cc / g, the micropore amount (V2) was 0.88 cc / g, and V1 / V2 = 0.59.

[Preparation of activated carbon 2]
The phenol resin was carbonized in a firing furnace at 600 ° C. for 2 hours in a nitrogen atmosphere, then pulverized with a ball mill and classified to obtain a carbide having an average particle size of 7 μm. This carbide and KOH were mixed at a mass ratio of 1: 5, and activated by heating in a firing furnace at 800 ° C. for 1 hour in a nitrogen atmosphere. Then, activated carbon 2 was obtained by stirring and washing in dilute hydrochloric acid adjusted to a concentration of 2 mol / L for 1 hour, boiling and washing with distilled water until the pH became stable between 5 and 6, and then drying. The pore distribution of this activated carbon 2 was measured using a pore distribution measuring device (AUTOSORB-1 AS-1-MP) manufactured by Yuasa Ionics. As a result, the BET specific surface area was 3627 m ² / g, the mesopore amount (V1) was 1.50 cc / g, the micropore amount (V2) was 2.28 cc / g, and V1 / V2 = 0.66.

[Preparation of positive electrode coating liquid (composition a)]
The positive electrode coating liquid (composition a) was produced by the following method using the activated carbon 1 or 2 obtained above as the positive electrode active material and the lithium carbonate obtained above as the charged lithium carbonate.
Activated carbon 1 or 2 by 34.5 parts by mass, lithium carbonate by 56.0 parts by mass, Ketjen black by 2.0 parts by mass, PVP (polyvinylidene) by 1.5 parts by mass, and PVDF (polyvinylidene fluoride) by mass. 6.0 parts by mass and NMP (N-methylpyrrolidone) are mixed, and the mixture is dispersed and coated at a peripheral speed of 15.0 m / s using a thin film swirling high-speed mixer fill mix manufactured by PRIMIX. A liquid (composition a) was obtained.

[Preparation of positive electrode coating liquid (composition b)]
The positive electrode coating liquid (composition b) was produced by the following method using the activated carbon 1 or 2 obtained above as the positive electrode active material and the lithium carbonate obtained above as the charged lithium carbonate.
59.5 parts by mass of activated carbon 1 or 2, 28.0 parts by mass of lithium carbonate, 3.0 parts by mass of Ketjen Black, 1.5 parts by mass of PVP (polyvinylidene), and PVDF (polyvinylidene fluoride). 8.0 parts by mass and NMP (N-methylpyrrolidone) are mixed, and the mixture is dispersed and coated at a peripheral speed of 15.0 m / s using a thin film swirling high-speed mixer fill mix manufactured by PRIMIX. A liquid (composition b) was obtained.

[Preparation of positive electrode precursor]
The coating liquid (composition a) or coating liquid (composition b) obtained above was applied to one or both sides of an aluminum foil having a thickness of 15 μm using a die coater manufactured by Toray Engineering Co., Ltd. under the condition of a coating speed of 2 m / s. It was coated and dried at a drying temperature of 100 ° C. to obtain a positive electrode precursor. The obtained positive electrode precursor was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the press portion of 25 ° C.

[Preparation of negative electrode 1]
The average particle diameter of 3.0 [mu] m, BET specific surface area was placed a commercial coconut shell activated carbon 150g of 1,780m ² / g in a stainless steel mesh steel basket, coal-based pitch (softening point: 50 ° C.) stainless steel containing the 270g A composite carbon material 1a was obtained by placing them on a bat, placing both of them in an electric furnace (effective dimensions in the furnace 300 mm × 300 mm × 300 mm), and conducting a thermal reaction. This heat treatment was carried out in a nitrogen atmosphere, the temperature was raised to 600 ° C. in 8 hours, and the temperature was maintained at the same temperature for 4 hours. Then, after cooling to 60 ° C. by natural cooling, the composite carbon material 1 was taken out from the furnace.
With respect to the obtained composite carbon material 1, the average particle size and the BET specific surface area were measured by the same method as described above. As a result, the average particle size was 3.2 μm and the BET specific surface area was 262 m ² / g. The mass ratio of the carboniferous material derived from the carboniferous pitch to the activated carbon was 78%.

Next, a negative electrode was prepared using the composite carbon material 1 as the negative electrode active material.
85 parts by mass of composite carbon material 1, 10 parts by mass of acetylene black, 5 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed and mixed with a thin film swirl type high speed manufactured by PRIMIX Corporation. A coating liquid was obtained by dispersing using a mixer fill mix under the condition of a peripheral speed of 15 m / s. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. The viscosity (ηb) was 2,789 mPa · s, and the TI value was 4.3. The above coating liquid was applied to both sides of an electrolytic copper foil having a thickness of 10 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 85 ° C. to obtain a negative electrode 1. It was. The obtained negative electrode 1 was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the pressed portion of 25 ° C. The film thickness of the negative electrode active material layer of the negative electrode 1 obtained above was measured from the average value of the thickness measured at any 10 points of the negative electrode 1 using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. , Calculated by subtracting the thickness of the copper foil. The film thickness of the negative electrode active material layer of the negative electrode 1 was 40 μm per side.

[Preparation of negative electrode 2]
Made of stainless steel containing 150 g of commercially available artificial graphite with a BET specific surface area of 3.1 m ² / g and an average particle size of 4.8 μm in a stainless steel mesh cage and 15 g of coal-based pitch (softening point: 50 ° C.). The composite carbon material 2 was obtained by placing it on a bat, placing both of them in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm), and conducting a thermal reaction. This heat treatment was carried out in a nitrogen atmosphere, the temperature was raised to 1000 ° C. in 8 hours, and the temperature was maintained at the same temperature for 4 hours. Subsequently, after cooling to 60 ° C. by natural cooling, the composite carbon material 2 was taken out from the furnace.
The average particle size and BET specific surface area of the obtained composite carbon material 2 were measured by the same method as described above. As a result, the average particle size was 4.9 μm and the BET specific surface area was 6.1 m ² / g. The mass ratio of the carboniferous material derived from the carboniferous pitch to artificial graphite was 2%.

Next, a negative electrode was prepared using the composite carbon material 2 as the negative electrode active material.
80 parts by mass of composite carbon material 2, 8 parts by mass of acetylene black, 12 parts by mass of PVdF (polyvinylidene fluoride), and NMP (N-methylpyrrolidone) are mixed and mixed with a thin film swirl type high speed manufactured by PRIMIX Corporation. A coating liquid was obtained by dispersing under the condition of a peripheral speed of 15 m / s using a mixer fill mix. The viscosity (ηb) and TI value of the obtained coating liquid were measured using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd. The viscosity (ηb) was 2,798 mPa · s, and the TI value was 2.7. The above coating liquid is applied to both sides of an electrolytic copper foil having a thickness of 10 μm using a die coater manufactured by Toray Engineering Co., Ltd. at a coating speed of 1 m / s, and dried at a drying temperature of 85 ° C. to obtain a negative electrode 2. It was. The obtained negative electrode 2 was pressed using a roll press machine under the conditions of a pressure of 4 kN / cm and a surface temperature of the press portion of 25 ° C. The film thickness of the negative electrode active material layer of the negative electrode 2 obtained above was measured from the average value of the thickness measured at any 10 locations of the negative electrode 2 using a film thickness meter Linear Gauge Sensor GS-551 manufactured by Ono Keiki Co., Ltd. , Calculated by subtracting the thickness of the copper foil. The film thickness of the negative electrode active material layer of the negative electrode 1 was 25 μm per side.

[Preparation of electrolyte]
As an organic solvent, a mixed solvent of ethylene carbonate (EC): methyl ethyl carbonate (EMC) = 33: 67 (volume ratio) was used, and the concentration ratio of LiN (SO ₂ F) ₂ and LiPF _{6 to} the total electrolytic solution was A solution obtained by dissolving each electrolyte salt so that the sum of the concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ is 1.2 mol / L at 75:25 (molar ratio) is non-aqueous. Used as an electrolyte.
The concentrations of LiN (SO ₂ F) ₂ and LiPF ₆ in the electrolytic solution prepared here were 0.3 mol / L and 0.9 mol / L, respectively.

[Example 1]
[Preparation of power storage element]
[Assembly and drying of power storage element]
Using the obtained double-sided negative electrode 1, activated carbon 1 as the positive electrode active material, and lithium carbonate having an average particle size of 4.7 μm as the charged lithium carbonate, the double-sided positive electrode precursor obtained from the coating liquid composition (a) produced was 10 cm. It was cut into × 10 cm (100 cm ² ). Single-sided positive electrode precursors are used for the uppermost and lowermost surfaces, 21 double-sided negative electrode 1s and 20 double-sided positive electrode precursors are used, and a microporous membrane separator having a thickness of 15 μm is inserted between the negative electrode and the positive electrode precursor. It was sandwiched and laminated. Then, the negative electrode terminal and the positive electrode terminal were connected to the negative electrode and the positive electrode precursor by ultrasonic welding, respectively, to form an electrode laminate. This electrode laminate was vacuum dried at a temperature of 80 ° C. and a pressure of 50 Pa under a drying time of 60 hr. The dried electrode laminate is housed in an exterior body made of aluminum laminate packaging material in a dry environment with a dew point of −45 ° C., and the electrode terminal portion and the bottom exterior body are placed at a temperature of 180 ° C. and a sealing time of 20 sec. Heat sealing was performed under the condition of a sealing pressure of 1.0 MPa.

[Liquid injection, impregnation, sealing of power storage elements]
About 80 g of the non-aqueous electrolyte solution was injected under atmospheric pressure into the electrode laminate housed in the aluminum laminate packaging material in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. or lower. Next, the non-aqueous lithium-type power storage element was placed in the decompression chamber, the pressure was reduced from normal pressure to −87 kPa, the pressure was returned to atmospheric pressure, and the mixture was allowed to stand for 5 minutes. Then, after reducing the pressure from normal pressure to −87 kPa, the step of returning to atmospheric pressure was repeated 4 times, and then the mixture was allowed to stand for 15 minutes. Further, the pressure was reduced from normal pressure to −91 kPa, and then returned to atmospheric pressure. Similarly, the steps of depressurizing and returning to atmospheric pressure were repeated 7 times in total. (Reduced pressure to -95, 96, 97, 81, 97, 97, 97 kPa, respectively). Through the above steps, the electrode laminate was impregnated with the non-aqueous electrolyte solution.
Then, the non-aqueous lithium-type power storage element was placed in a vacuum sealing machine, and the aluminum laminate packaging material was sealed by sealing at 180 ° C. for 10 seconds at a pressure of 0.1 MPa with the pressure reduced to −95 kPa.

[Lithium doping process]
For the obtained non-aqueous lithium-type power storage element, a charging / discharging device (TOSCAT-3100U) manufactured by Toyo Systems Co., Ltd. was used to determine the voltage until the voltage reached 4.5 V at a current value of 1.0 A in an environment of 25 ° C. After the current charge, the initial charge was carried out by the method of continuing the 4.5 V constant voltage charge for 72 hours, and the negative electrode was lithium-doped.

[Aging process]
The non-aqueous lithium-type power storage element after lithium doping is subjected to constant current discharge at 1.0 A until the voltage reaches 3.0 V in an environment of 25 ° C., and then 3.0 V constant current discharge is performed for 1 hour to increase the voltage. Adjusted to 3.0V. Then, the non-aqueous lithium-type power storage element was stored in a constant temperature bath at 60 ° C. for 60 hours.

[Degassing process]
A part of the aluminum laminate packaging material was opened in a dry air environment at a temperature of 25 ° C. and a dew point of −40 ° C. for the aged non-aqueous lithium-type power storage element. Next, the non-aqueous lithium-type power storage element is placed in the decompression chamber, and the pressure is reduced from atmospheric pressure to -80 kPa using a diaphragm pump (N816.3KT.45.18) manufactured by KNF for 3 minutes, and then 3 The process of returning to atmospheric pressure over a minute was repeated a total of 3 times. Then, a non-aqueous lithium-type power storage element was placed in a vacuum sealing machine, the pressure was reduced to −90 kPa, and the aluminum laminate packaging material was sealed by sealing at 200 ° C. for 10 seconds at a pressure of 0.1 MPa.
Through the above steps, the power storage element was completed.

[Evaluation of power storage element]
[Measurement of capacitance]
The power storage element obtained in the above step reaches 3.8V at a current value of 2C using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited in a constant temperature bath set at 25 ° C. Constant current charging was performed until the voltage was increased, and then constant voltage charging was performed for a total of 30 minutes by applying a constant voltage of 3.8 V. After that, the capacitance when constant current discharge was performed with a current value of 2C up to 2.2V was defined as Q, and the capacitance F calculated by F = Q / (3.8-2.2) was 1000F. ..

[Calculation of Ra / F]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Co., Ltd. until it reaches 3.8V at a current value of 20C. Current charging, followed by constant voltage charging with a constant voltage of 3.8V for a total of 30 minutes, followed by constant current discharge to 2.2V with a current value of 20C, discharge curve (time-voltage) Got In this discharge curve, the voltage at the discharge time = 0 seconds obtained by extrapolating from the voltage values at the time points of the discharge times of 2 seconds and 4 seconds is defined as Eo, the voltage drop ΔE = 3.8-Eo, and The room temperature internal resistance Ra was calculated from R = ΔE / (20C (current value A)).
The product Ra · F of the capacitance F and the internal resistance Ra at 25 ° C. was 1.05 ΩF.

[Calculation of E / V]
The E / V is the value of the capacitance F obtained by the above method, the outer dimension length (l ₁ ) and the outer dimension width (w ₁ ) of the cup-molded portion of the laminated film of the power storage element, and the laminated film. E / V = F × (3.8 ² -2.2 ² ) / 7200 / V using V ₁ = l ₁ × w ₁ × t ₁ obtained by the thickness (t ₁ ) of the power storage element included. It was calculated as 18.5 Wh / L from ₁ .

[Gas generated after high temperature storage test]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited until it reaches 4.0V at a current value of 100C. Current charging was followed by constant voltage charging to which a constant voltage of 4.0 V was applied for a total of 10 minutes. After that, the cell was stored in a 60 ° C environment, taken out from the 60 ° C environment every two weeks, charged to 4.0 V in the cell voltage in the same charging step, and then the cell was stored again in the 60 ° C environment. .. This step was repeated for 2 months, and the cell volume Va before the start of the preservation test and the cell volume Vb 2 months after the preservation test were measured by the Archimedes method. The amount of gas generated by Vb-Va was 10.3 × 10 ^-3 cc / F.

[Calculation of Rb / Ra]
For the power storage element after the high temperature storage test, the room temperature internal resistance Rb after the high temperature storage test was calculated in the same manner as in the above [Calculation of Ra and F].
The ratio Rb / Ra calculated by dividing this Rb (Ω) by the internal resistance Ra (Ω) before the high temperature storage test obtained in the above [Calculation of Ra / F] was 1.38.

[High load charge / discharge cycle test]
The obtained power storage element is fixed in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited until it reaches 3.8V at a current value of 300C. The charge / discharge step of charging with a current and then performing a constant current discharge with a current value of 300 C until reaching 2.2 V was repeated 60,000 times. After the high load charge / discharge cycle test, the room temperature internal resistance Rc after the high temperature storage test was calculated in the same manner as in the above [Calculation of Ra / F]. The ratio Rc / Ra calculated by dividing this Rc (Ω) by the internal resistance Ra (Ω) before the high load charge / discharge cycle test obtained in the above [Calculation of Ra / F] was 1.17.

[Microscopic Raman measurement of positive electrode]
Of the multiple non-aqueous lithium-type power storage elements completed, after adjusting several elements to 2.9V, Ar is installed in a room at 23 ° C and controlled at a dew point of -90 ° C or less and an oxygen concentration of 1 ppm or less. The positive electrode body was taken out by disassembling in the box. The removed positive electrode body was immersed and washed with dimethyl carbonate (DMC), and then vacuum dried in a side box under a state where it was not exposed to the atmosphere.
The dried positive electrode body was transferred from the side box to the Ar box while maintaining non-exposure to the atmosphere. The positive electrode body was transported to a cross-section processing apparatus while maintaining non-exposure to the atmosphere, and a cross-section was prepared. When transporting the electrode body from the Ar box to the cross-section processing device, a sealed container that can maintain non-exposure to the atmosphere was used. The cross-section processing apparatus is characterized by etching processing by irradiating a sample with an ion beam, and for example, SM-09020CP manufactured by JEOL Ltd. is used. The cross-section processing conditions are not particularly limited, but it is preferable that the conditions are such that processing damage to the sample is suppressed. A positive electrode body having a cross section produced by the above method is transported from a cross-section processing device to an Ar box while maintaining non-exposure to the atmosphere, and an air non-exposed cell corresponding to micro Raman measurement, for example, a LIB cell manufactured by Nanophoton Co., Ltd. It was transferred to a sample for microscopic Raman measurement.

Bicarbonate ion mapping was performed using a Renishaw microscopic Raman spectrometer in Via Reflex. The wavelength of the laser of the excitation light was 532 nm, and a 50x objective lens with a long working distance was used to focus the light so that the power was about 0.7 mW at the sample position. A Raman spectrum of each measurement point was obtained by point scanning a range of 90 μm in the thickness direction of the positive electrode cross section and 30 μm in the direction perpendicular to the thickness direction at 1 μm intervals. For the bicarbonate peak observed at 1086 cm ^-1 in Raman spectrum, draw a straight baseline from 1071 cm ^-1 to 1104 cm ^-1, and the area appearing in the positive region from the baseline and appearing negative from the baseline. The area was calculated as the peak area. The sign of the area that appears negative from the baseline is set to be a negative value. The image of the carbonate ion was obtained by drawing it as a spatial distribution of the peak area of the carbonate ion.

[Calculation method of area ratio of carbonate ion mapping]
The area ratio of carbonate ion mapping can be calculated as follows. In the Raman spectrum of 2700 points obtained at each measurement position, a straight baseline is set at the position of 1071, 1104 cm ^-1 , and the area higher than the baseline is positive and the area lower than the baseline is negative. (A). Mapping data of this area (a) is created. Further, the maximum value to the minimum value of the area (a) are divided into 100 sections to create a histogram A. Next, in the histogram A, the noise component was approximated by the Gaussian function B by fitting the portion on the negative side of the area value giving the maximum frequency by the least squares method using the Gaussian function. Difference obtained by subtracting the fitting with Gaussian function B from the original histogram A is a histogram C of CO ₃ ^2- in the peak area. In this histogram C, and cumulative frequency area (b) above to give the maximum frequency was determined mapping frequency of CO ₃ ^2- ions, it was 462. By dividing this by the total frequency of 2700, the area ratio of carbonate ion mapping was calculated and found to be 5.1%.

[Calculation method of number average particle diameter X ₁ of lithium carbonate particles]
As a method of calculating the number average particle diameter X ₁ of lithium carbonate, the measurement position given the area (b) or more given the maximum frequency is mapped in the histogram C obtained by the above method, and this is mapped to the lithium carbonate particles. It was used as data. From this data, the number n of lithium carbonate particles and the particle major axis X _i (i = 1, 2, 3, ..., N) were obtained. Further, when the number average particle diameter X ₁ was calculated by the following formula (8), X ₁ was determined to be 2.0 μm.

[The positive electrode active number average calculation method of the particle diameter Y ₁ of material particles]
The number average particle diameter Y ₁ of the positive electrode active material particles was obtained by superimposing the measured optical microscope image and the carbonate ion mapping data in the same field of view as in which the microscopic Raman was measured. As a result, the particles confirmed by the optical microscope image obtained by removing the carbonate particles are used as the positive electrode active material particles, and the number of active material particles m confirmed in the field of view and the particle major axis Y _i (i = 1, 2). , 3, ..., m) was obtained. Further, when the number average particle diameter Y ₁ was calculated by the following formula (9), Y ₁ was determined to be 12.3 μm.

[Quantification of lithium carbonate]
The positive electrode sample 1 was cut into a size of 5 cm × 5 cm (weight 0.256 g), immersed in 20 g of methanol, the container was covered, and the mixture was allowed to stand in an environment of 25 ° C. for 3 days. Then, the positive electrode was taken out and vacuum dried at 120 ° C. and 5 kPa for 10 hours. At this time, the positive electrode weight M ₀ is 0.250 g, and the GC / MS of the methanol solution after washing is measured under the condition that a calibration curve is prepared in advance, and the abundance of diethyl carbonate is less than 1%. confirmed. Then, 25.00 g of distilled water was impregnated with a positive electrode, the container was covered, and the mixture was allowed to stand in an environment of 45 ° C. for 3 days. Since the weight of distilled water after standing for 3 days was 24.65 g, 0.35 g of distilled water was added. Then, the positive electrode was taken out and vacuum dried at 150 ° C. and 3 kPa for 12 hours. At this time, the positive weight M ₁ was 0.223 g, and GC / MS was measured on the distilled water after washing under the condition that a calibration curve was prepared in advance, and it was confirmed that the abundance of methanol was less than 1%. did. Then, a spatula, a brush, remove the active material layer on the positive electrode current collector by using a brush, it was 0.099g was weighed M ₂ of the positive electrode current collector. When lithium carbonate in the positive electrode was quantified by the above formula (4), it was 6.0% by mass.

[Calculation of A ₁ and A ₂ ]
[Preparation of positive electrode sample]
The remaining non-aqueous lithium-type power storage element was disassembled in an argon box having a dew point temperature of −72 ° C., and a positive electrode coated with a positive electrode active material layer on both sides was cut into a size of 10 cm × 5 cm, and 30 g of diethyl was obtained. Immersed in carbonate solvent, occasionally moving the positive electrode with tweezers and washing for 10 minutes. Subsequently, the positive electrode was taken out, air-dried in an argon box for 5 minutes, the positive electrode was immersed in a newly prepared 30 g of diethyl carbonate solvent, and washed for 10 minutes in the same manner as described above. The positive electrode was taken out from the argon box and dried using a vacuum dryer (manufactured by Yamato Scientific Co., Ltd., DP33) at a temperature of 25 ° C. and a pressure of 1 kPa for 20 hours to obtain a positive electrode sample 1.

[Measurement of positive electrode surface SEM and EDX]
A small piece of 1 cm × 1 cm was cut out from the positive electrode sample 1, and the surface was coated with gold by sputtering in a vacuum of 10 Pa. Next, SEM and EDX on the surface of the positive electrode were measured under the conditions shown below under atmospheric exposure.
[SEM-EDX measurement conditions]
-Measuring device: Electron emission scanning electron microscope FE-SEM S-4700 manufactured by Hitachi High-Technology
・ Acceleration voltage: 10kV
・ Emission current: 1 μA
・ Measurement magnification: 2000 times ・ Electron beam incident angle: 90 °
・ X-ray extraction angle: 30 °
・ Dead time: 15%
-Mapping elements: C, O, F
-Number of measurement pixels: 256 x 256 pixels-Measurement time: 60 sec.
-Number of integrations: 50 times-The brightness and contrast were adjusted so that there were no pixels that reached the maximum brightness and the average value of the brightness was within the range of 40% to 60%.

[Analysis of SEM-EDX]
The obtained oxygen mapping and fluorine mapping were binarized based on the average value of brightness using image analysis software (ImageJ). The area of oxygen mapping at this time was 15.1% of the total image, and the area of fluorine mapping was 31.5%. The overlapping area of the oxygen mapping and the fluorine mapping obtained by binarization is 14.0% for all images, and if the area overlapping rate of the fluorine mapping for the oxygen mapping is A ₁ [%], A ₁ = It was calculated as 77.5% from 100 × 11.7 / 15.1.

[Measurement of positive electrode cross section SEM and EDX]
A small piece of 1 cm × 1 cm is cut out from the positive electrode sample 1, and a cross section perpendicular to the plane direction of the positive electrode sample 1 is formed under the conditions of an acceleration voltage of 4 kV and a beam diameter of 500 μm using SM-09020CP manufactured by JEOL Ltd. and argon gas. Made. Then, the positive electrode cross sections SEM and EDX were measured by the above-mentioned method.
For SEM-EDX of the obtained positive electrode section, said the binarized oxygen mapping and fluorine mapping as well, was 32.6% when calculating the area overlapping ratio A ₂ fluorine mapping for oxygen mapping.

[Analysis of positive electrode active material layer]
Of the multiple non-aqueous lithium-type power storage elements completed, after adjusting several elements to 2.9V, Ar is installed in a room at 23 ° C and controlled at a dew point of -90 ° C or less and an oxygen concentration of 1 ppm or less. The positive electrode body was taken out by disassembling in the box. The positive electrode body taken out was immersed and washed with dimethyl carbonate (DMC), and then vacuum dried in a side box under a state where it was not exposed to the atmosphere.
The dried positive electrode body was transferred from the side box to the Ar box while maintaining non-exposure to the atmosphere, and immersed in heavy water for extraction to obtain a positive electrode body extract. The extract was analyzed by (1) IC and (2) ¹ H-NMR, and the concentration A (mol / ml) of each compound in the obtained positive electrode body extract and the volume B of heavy water used for extraction were obtained. From (ml) and the mass C (g) of the positive electrode active material used for extraction, the following formula (10):
Abundance per unit mass (mol / g) = A × B ÷ C. .. .. Equation (10)
The abundance (mol / g) of each compound deposited on the positive electrode body per unit mass of the positive electrode active material was determined.
The mass of the positive electrode active material layer used for extraction was determined by the following method.
The mixture (positive electrode active material layer) was peeled off from the current collector of the positive electrode body remaining after extraction with heavy water, and the peeled mixture was washed with water and then vacuum dried. The mixture obtained by vacuum drying was washed with NMP or DMF. Subsequently, the obtained positive electrode active material layer was vacuum-dried again and then weighed to examine the mass of the positive electrode active material layer used for extraction.

The positive electrode body extract was placed in a 3 mmφ NMR tube (PN-002 manufactured by Shigemi Co., Ltd.), and a 5 mmφ NMR tube containing deuterated chloroform containing 1,2,4,5-tetrafluorobenzene (N manufactured by Nippon Seimitsu Kagaku Co., Ltd.). It was inserted into -5) and ¹ H NMR measurement was performed by the double tube method. The signal of 1,2,4,5-tetrafluorobenzene was standardized at 7.1 ppm (m, 2H), and the integrated value of each observed compound was obtained.
In addition, deuterated chloroform containing dimethyl sulfoxide of known concentration was placed in a 3 mmφ NMR tube (PN-002 manufactured by Shigemi Co., Ltd.), and the same 1,2,4,5-tetrafluorobenzene-containing deuterated chloroform as described above was placed. It was inserted into a 5 mmφ NMR tube (N-5 manufactured by Nippon Seimitsu Kagaku Co., Ltd.) containing chloroform, and ¹ H NMR measurement was performed by the double tube method. In the same manner as above, the signal of 1,2,4,5-tetrafluorobenzene was standardized at 7.1 ppm (m, 2H), and the integrated value of the signal of dimethyl sulfoxide at 2.6 ppm (s, 6H) was obtained. From the relationship between the concentration of dimethyl sulfoxide used and the integrated value, the concentration A of each compound in the positive electrode body extract was determined.

¹ The attribution of the ¹ H NMR spectrum is as follows.
[About XOCH ₂ CH ₂ OX]
XOCH ₂ CH ₂ OX CH ₂ : 3.7 ppm (s, 4H)
CH ₃ OX: 3.3 ppm (s, 3H)
CH ₃ CH ₂ OX CH ₃ : 1.2 ppm (t, 3H)
CH ₂ O of CH ₃ CH ₂ OX: 3.7 ppm (q, 2H) As described above, the signal of CH ₂ of XOCH ₂ CH ₂ OX (3.7 ppm) is _that of CH ₂ O of CH ₃ CH ₂ OX. since overlaps the signal (3.7 _ppm), with the exception of the CH ₂ O equivalent of _CH 3 _CH 2 OX calculated from the signal of CH 3 _CH 2 OX of _{CH 3 (1.2ppm), XOCH 2} CH 2 Calculate the amount of OX.
In the above, X is − (COO) _n Li or − (COO) _n R ¹ (where n is 0 or 1, R ¹ is an alkyl group having 1 to 4 carbon atoms and 1 carbon atom, respectively. It is an alkyl halide group of ~ 4).

Based on the concentration of each compound in the extract obtained by the analysis of (1) IC and (2) ¹ H-NMR, the volume of heavy water used for extraction, and the active material mass of the positive electrode used for extraction, the above positive electrode XOCH ₂ CH ₂ OX was present in the electrode body at 229.8 × 10 ^-4 mol / g.

[Examples 2 to 44 and Comparative Examples 1 to 5]
The positive electrode active material of the positive electrode precursor, the particle size of lithium carbonate charged into the positive electrode precursor, the coating liquid composition, the peripheral speed of the film, the negative electrode, and the voltage and time of the lithium doping process are shown in Table 1 below. In the same manner as in Example 1, non-aqueous lithium-type electricity storage elements of Examples 2 to 44 and Comparative Examples 1 to 5 were produced and evaluated in various ways. The evaluation results of the obtained non-aqueous lithium-type power storage element are shown in Table 2 below.

From the above examples, it has been verified that the power storage element according to the present embodiment has excellent initial input / output characteristics, high energy density, high load charge / discharge cycle characteristics, and excellent high temperature storage durability. It was.

The non-aqueous lithium-type power storage element according to the present invention has excellent initial input / output characteristics, high energy density, high load charge / discharge cycle characteristics, and excellent high temperature storage durability. Therefore, for example, in an automobile, an internal combustion engine or a fuel It can be suitably used in the field of hybrid drive systems that combine batteries, motors, and power storage elements, as well as in applications such as assisting instantaneous power peaks.

Claims (4)

A non-aqueous lithium-type power storage element including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector, and the negative electrode active material occludes lithium ions. Contains a carbon material that can be released,
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle diameter of the lithium carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle diameter of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. Moreover, the non-aqueous lithium-type power storage element in which X ₁ <Y ₁ is satisfied. The non-aqueous lithium-type power storage element according to claim 1, wherein the area ratio of carbonate ion mapping to the cross-sectional area is 2% or more and 20% or less in the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode. A non-aqueous lithium-type power storage device including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector.
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle diameter of the lithium carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle diameter of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. In addition, X ₁ <Y ₁ and in the non-aqueous lithium type power storage element, the initial internal resistance at a cell voltage of 4 V is Ra (Ω), the capacitance is F (F), and the electric energy is E (Wh). , When the volume of the power storage element is V (L), the following:
(A) The product Ra / F of Ra and F is 0.3 or more and 3.0 or less;
(B) E / V is 15 or more and 50 or less;
The non-aqueous lithium power storage element, which is characterized by simultaneously satisfying. A non-aqueous lithium-type power storage device including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution containing lithium ions.
The negative electrode has a negative electrode current collector and a negative electrode active material layer containing a negative electrode active material provided on one side or both sides of the negative electrode current collector.
The positive electrode has a positive electrode current collector and a positive electrode active material layer containing a positive electrode active material made of activated carbon provided on one side or both sides of the positive electrode current collector.
The positive electrode contains lithium carbonate particles of 1% by mass or more and 50% by mass or less based on the total mass of the positive electrode active material layer.
In the imaging image obtained by microscopic Raman spectroscopic measurement of the cross section of the positive electrode, the area ratio of carbonate ion mapping to the cross section is 1% or more and 40% or less.
When the number average particle size of the lithium carbonate particles is X ₁ , 1 μm ≤ X ₁ ≤ 5 μm, and when the number average particle size of the positive electrode active material is Y ₁ , 3 μm ≤ Y ₁ ≤ 20 μm. In addition, X ₁ <Y ₁ and after storing the initial internal resistance at a cell voltage of 4 V for 2 months at Ra (Ω), a cell voltage of 4 V, and an ambient temperature of 60 ° C. in the non-aqueous lithium type power storage element. After performing 60,000 charge / discharge cycles at a rate of 300 C, the internal resistance at a cell voltage of 4 V is Rb (Ω), the cell voltage is from 2.2 V to 3.8 V at an ambient temperature of 25 ° C. When the internal resistance is Rc (Ω), the following:
(C) Rb / Ra is 3.0 or less;
(D) The amount of gas generated when stored for 2 months at a cell voltage of 4 V and an environmental temperature of 60 ° C. is 25 × 10 ^-3 cc / F or less at 25 ° C.;
(E) Rc / Ra is 0.9 or more and 2.0 or less;
The non-aqueous lithium-type power storage element, which is characterized by simultaneously satisfying.