JP6967901B2 - Manufacturing method of non-aqueous lithium-type power storage element - Google Patents

Description

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

In power storage systems such as load leveling devices such as solar power generation or wind power generation, instantaneous voltage drop countermeasure devices, and energy regeneration devices for electric vehicles or hybrid vehicles, power storage has a large energy capacity and can be rapidly charged and discharged. Elements are needed.

In recent years, a power storage module using a power storage element such as a lithium ion secondary battery, a nickel hydrogen battery, an electric double layer capacitor, or a lithium ion capacitor has been developed. These power storage modules include a power storage body in which a plurality of power storage elements are connected in series or in parallel, and can be charged and discharged in a high voltage or large capacity state, and thus are used in various applications as a power supply device. ..

Such a power storage module is also in the limelight for in-vehicle applications such as hybrid vehicles, and not only has good performance as a power storage element contained therein, but also has a higher level of performance and vibration resistance as a power storage module. Sex is required.
For the power storage element used in the power storage module, for example, a flat electrode winder in which a positive electrode precursor and a negative electrode are stacked via a separator, wound in a spiral shape, and then pressurized to be flat, is used. Some are housed in a square or flat exterior (for example, Patent Document 1). This exterior body is generally a metal case such as an aluminum alloy or a stainless alloy, and when mounted on an automobile or the like, the case itself having high rigidity in the metal case structure serves as a holding member, so that it is caused by vibration. Distortion or deformation can be suppressed, and the influence of tearing of the current collecting foil of the power storage element, damage to the connection portion of the power storage module, and the like can be suppressed.

Japanese Unexamined Patent Publication No. 2015-103479

However, when the positive electrode precursor and the negative electrode are stacked via a separator, wound in a spiral shape, and then pressed to be flat to form an electrode wound body, the bent portion of the electrode wound body is formed. When pressure is applied, the positions of the positive electrode, separator, and negative electrode may shift. In addition, the electrode winding body may open (rewind) when it returns to its original position, resulting in misalignment. If the positions of the positive electrode, the separator, and the negative electrode are displaced, unevenness may occur between the portion where the distance between the positive electrode and the negative electrode is narrow and the portion where the distance between the positive electrode and the negative electrode is wide, and as a result, the doping may not be performed uniformly (there may be uneven doping). There is. That is, the dope is efficiently performed in the portion where the distance between the positive electrode and the negative electrode is narrow, while the efficiency of the dope decreases in the portion where the distance between the positive electrode and the negative electrode is wide. As a result, repeated charging and discharging with uneven doping leads to deterioration of the entire power storage element.
In view of the above situation, the problem to be solved by the present invention is to suppress the displacement of the positive electrode, the separator, and the negative electrode in the manufacture of the non-aqueous lithium storage element using the flat square outer body, and to make the dope uneven. It is to provide a manufacturing method that can be carried out uniformly without any problems.

The problems described above are solved by the following technical means.
[1]
The following steps:
(1) A step of forming a positive electrode active material layer containing activated carbon and a lithium compound on a positive electrode current collector to obtain a positive electrode precursor;
(2) An electrode including the positive electrode precursor, a negative electrode having a negative electrode active material layer capable of occluding and releasing lithium ions on a negative electrode current collector, and a separator arranged between the positive electrode precursor and the negative electrode. Step of forming a laminate;
(3) A step of winding the electrode laminate to form an electrode wound body;
(4) A step of pressing the electrode winding body to form a flat electrode winding body;
(5) The flat electrode winding body is housed in a flat square can, and a non-aqueous electrolytic solution containing a lithium salt different from the lithium compound is injected from the opening of the flat can, and the opening is opened. The step of forming a sealed non-aqueous lithium storage element; and (6) the sealed non-aqueous lithium storage element is sandwiched between a pair of jigs having a pressure surface, and the thickness direction of the flat square can. A step of decomposing a lithium compound to generate lithium ions and doping the negative electrode active material layer with the lithium ions;
In the doping step (6), when the maximum in-plane pressing force of the flat square can is P _max and the in-plane minimum pressing force is P _min , (P _{max −} P _min ) / P _max ≦ Pressurize to 0.5 and at the same time
In the doping step (6), a sealed non-sealed type can is pressed so that a force applied to the peripheral portion is larger than that in the central portion in the main surface of the flat square can. A method for manufacturing an aqueous lithium storage element.
[ 2 ]
The method for manufacturing a sealed non-aqueous lithium storage element according to [1 ], wherein in the jig, the pressurized surface has an inclination such that the central portion is concave.
[ 3 ]
The sealed non-aqueous lithium according to [1] or [2] , wherein the hardness of the material of the pressurized surface in contact with the main surface of the flat square can is shore A5 or more and shore A70 or less as measured by JIS K6253. Manufacturing method of power storage element.
[ 4 ]
The method for manufacturing a sealed non-aqueous lithium storage element according to any one of [1] to [ 3 ], wherein the jig is made of a material having a thermal conductivity of 200 W · m ^-1 · K ^{-1 or more.} ..
[ 5 ]
The sealed non-aqueous lithium storage device according to any one of [1] to [4 ], wherein the insulating tape used for fixing the electrode winding body is located at a bent portion of the electrode winding body. Method of manufacturing the element.
[ 6 ]
In step (6) to said doped, average pressure _{P A} applied to the main surface of the flat, square cans is 0.5 kgf / cm ² or more 20 kgf / cm ² or less, any of [1] to [5] The method for manufacturing a sealed non-aqueous lithium storage element according to item 1.
[ 7 ]
The method for manufacturing a sealed non-aqueous lithium storage element according to any one of [1] to [6 ], wherein the doping step (6) is performed in a dry environment.

In the present invention, in the doping step, pressure is applied in a state where the surface pressure distribution in the main surface of the flat square can is optimally controlled, so that the position shift due to the bending portion and rewinding of the flat electrode winding body is performed. It is possible to provide a method for manufacturing a non-aqueous lithium-type power storage element capable of uniformly and evenly doping.

It is a perspective view which shows the appearance of the non-aqueous lithium type storage element which concerns on this invention. FIG. 1 is a vertical cross-sectional view taken along the line YY. FIG. 1 is a cross-sectional view taken along the line XX. It is sectional drawing which shows the state which presses the flat square type can which accommodated the flat type electrode winding body by sandwiching with a pair of jigs. It is a top view which shows the pressurizing surface of the jig shown in FIG. It is a figure explaining the averaging of the surface pressure distribution data.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

Generally, a non-aqueous lithium storage element includes a positive electrode, a negative electrode, a separator, an electrolytic solution, and an exterior body as main components. As the electrolytic solution, an organic solvent in which a lithium salt is dissolved (hereinafter referred to as a non-aqueous electrolytic solution) is used.

Here, FIGS. 1 to 3 are views showing a configuration example of a non-aqueous lithium-type power storage element according to the present embodiment, FIG. 1 is a perspective view showing an appearance, and FIG. 2 is Y in FIG. FIG. 3 is a vertical cross-sectional view taken along the line Y, and FIG. 3 is a cross-sectional view taken along the line XX in FIG. 1.
In this non-aqueous lithium-type power storage element, the positive electrode (positive electrode precursor) and the negative electrode are wound in a spiral shape via a separator, and then pressed so as to be flat to form a flat electrode winding body 6. It is housed in a flat-angled exterior body 4 together with a non-aqueous electrolyte solution. However, in the figure, in order to avoid complication, the metal foil as the current collector used for manufacturing the positive electrode (positive electrode precursor) and the negative electrode, each layer of the separator, the non-aqueous electrolytic solution, and the like are not shown.

[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 preferably contains a lithium compound 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 assembly process. As the predoping method, a voltage is applied between the positive electrode precursor and the negative electrode after assembling the power storage element using the positive electrode precursor containing the lithium compound, the negative electrode, the separator, the exterior body, and the non-aqueous electrolyte solution. Is preferable. The lithium compound 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 process is defined as a positive electrode precursor, and the positive electrode state after the lithium doping process is defined as a positive electrode.

[Positive electrode active material layer]
The positive electrode active material layer contained in the positive electrode is made of a material containing activated carbon. The material contains a positive electrode active material, including activated carbon. In addition to this, the positive electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary.
Further, it is preferable that the positive electrode active material layer of the positive electrode precursor contains a lithium compound other than the positive electrode active material.

[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 a carbon nanotube, 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, more preferably 70% by mass or more. The content of the carbon material can be 100% by mass, but is preferably 90% by mass or less or 80% by mass or less, for example, from the viewpoint of obtaining a good effect by the combined use of other materials.

There are no particular restrictions on the type of activated carbon used as the positive electrode active material and its raw materials. 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 is used. 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 it is also preferable.
(2) In order to obtain a high energy density, 0.8 <V1 ≦ 2.5 and 0.8 <V2 ≦ 3.0 are satisfied, and the specific surface area measured by the BET method is 2,300 m ^2. Activated carbon having a / g or more and 4,000 m ² / g or less (hereinafter, also referred to as activated carbon 2) is preferable.

[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 of them.
The positive electrode active material is a material other than activated carbons 1 and 2 (for example, activated carbon without 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, and 70% by mass or more, respectively, of the total positive electrode active material. More preferably, 90% by mass or more is further preferable, and 100% by mass is most 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 upper limit of the content ratio of the positive electrode active material is more preferably 45% by mass or more, further preferably 55% by mass or more. On the other hand, the lower limit of the content ratio of the positive electrode active material is more preferably 90% by mass or less, further preferably 80% by mass or less. By setting the content ratio in this range, suitable charge / discharge characteristics are exhibited.

[Lithium compound]
It is preferable that the positive electrode active material layer of the positive electrode precursor of the present embodiment contains a lithium compound other than the positive electrode active material. Further, the positive electrode active material layer of the positive electrode of the present embodiment contains a lithium compound other than the positive electrode active material.
The lithium compound can be decomposed at the positive electrode in the lithium doping step described later to release lithium ions, and from the viewpoint that lithium carbonate, lithium oxide, lithium sulfide, lithium hydroxide, lithium fluoride, and lithium chloride can be released. , Lithium oxalate, lithium iodide, lithium nitride, lithium oxalate, and one or more selected from lithium acetate are preferably used. Among them, at least one selected from the group consisting of lithium carbonate, lithium oxide, lithium sulfide and lithium hydroxide is more preferable, and lithium carbonate can be handled in the air and has low moisture absorption. Is more preferably used. Such a lithium compound decomposes when a voltage is applied, functions as a dopant source for lithium doping to the negative electrode, and forms pores in the positive electrode active material layer, so that the electrolytic solution has excellent retention and ionic conductivity. It is possible to form an excellent positive electrode.

[Lithium compound of positive electrode precursor]
The lithium compound is preferably in the form of particles. The average particle size of the lithium compound contained in the positive electrode precursor is preferably 0.1 μm or more and 100 μm or less. The upper limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 50 μm or less, further preferably 20 μm or less, and most preferably 10 μm or less. On the other hand, the lower limit of the average particle size of the lithium compound contained in the positive electrode precursor is more preferably 0.3 μm or more, and further preferably 0.5 μm or more. When the average particle size of the lithium compound is 0.1 μm or more, the pores remaining after the oxidation reaction of the lithium compound in the positive electrode have a sufficient volume to hold the electrolytic solution, so that the high load charge / discharge characteristics are exhibited. improves. When the average particle size of the lithium compound is 100 μm or less, the surface area of the lithium compound does not become excessively small, so that the rate of the oxidation reaction of the lithium compound can be ensured. The upper and lower limits of the range of the average particle size of the lithium compound can be arbitrarily combined.
Various methods can be used for atomizing the lithium compound. 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 active material layer of the positive electrode precursor is preferably 5% by mass or more and 60% by mass or less based on the total mass of the positive electrode active material layer in the positive electrode precursor, and is preferably 10% by mass or more and 50% by mass. It is more preferably mass% or less. By setting the content ratio in this range, it is possible to exert a suitable function as a dopant source for the negative electrode, to impart an appropriate degree of porosity to the positive electrode, and to combine both of them with high load charge / discharge efficiency. It is possible to provide an excellent power storage element. The upper and lower limits of this content ratio range can be arbitrarily combined.

The lithium compound contained in the positive electrode other than the positive electrode active material is preferably 2% by mass or more and 20% by mass or less, preferably 2.5% by mass or more and 10% by mass, based on the total mass of the positive electrode active material layer in the positive electrode. The following is more preferable. When the amount of the lithium compound is 2% by mass or more, the positive electrode active materials form stronger bonds with each other, so that the rigidity of the positive electrode becomes high, and the effect becomes remarkable when the amount is 2.5% by mass or more. By increasing the rigidity of the positive electrode, the rigidity of the non-aqueous lithium-type power storage element is also improved.

[Arbitrary component of positive electrode active material layer]
If necessary, the positive electrode active material layer in the present embodiment may contain optional components such as a conductive filler, a binder, and a dispersion stabilizer in addition to the positive electrode active material and the lithium compound.
The conductive filler is not particularly limited, and for example, acetylene black, ketjen black, vapor-grown carbon fiber, graphite, carbon nanotubes, a mixture thereof and the like can be used. The amount of the conductive filler used is preferably more than 0 parts by mass and 30 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. It is more preferably 0.01 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 amount of the conductive filler used is more than 30 parts by mass, the content ratio of the positive electrode active material in the positive electrode active material layer is small, and the energy density per volume of the positive electrode active material layer is lowered, which is not preferable.

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 dispersion stabilizer used is preferably more than 0 parts by mass or 0.1 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 used is 10 parts by mass or less, high input / output characteristics are exhibited without inhibiting the ingress / egress and diffusion of ions into the positive electrode active material.

[Positive current collector]
As the material constituting the positive electrode current collector in the present embodiment, a metal foil is preferable because it has high electron conductivity and does not deteriorate due to elution into the electrolytic solution and reaction with the electrolyte or ions. Aluminum foil is particularly preferable as the positive electrode current collector in the non-aqueous lithium storage element of the present embodiment.
Further, the positive electrode current collector is preferably a plain foil. In general, plain foil is sometimes referred to as non-perforated foil. When the positive electrode current collector is a perforated foil, the rigidity of the perforated portion depends on the rigidity of the active material, whereas when the positive electrode current collector is a plain foil, the rigidity of the active material is low. The electric foil can keep the rigidity of the electrode high. 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 may be, for example, 1 to 100 μm.

[Negative]
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 is a layer capable of occluding and releasing lithium ions. The negative electrode active material layer contains a negative electrode active material that can occlude and release lithium ions. In addition to this, the negative electrode active material layer may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, if necessary.

[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 may 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 preferably 80% by mass or less.

The negative electrode active material is preferably doped with lithium ions. In the present specification, the lithium ion doped in the negative electrode active material mainly includes three forms.
The first form is lithium ion, which is preliminarily occluded as a design value in the negative electrode active material before manufacturing the non-aqueous lithium-type power storage element.
The second form is lithium ions stored in the negative electrode active material when a non-aqueous lithium-type power storage element is manufactured and shipped.
The third form is lithium ions occluded in the negative electrode active material after using the non-aqueous lithium-type power storage element 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 refractory carbon materials; easily graphitizable carbon materials; carbon black; carbon nanoparticles; activated carbon; artificial graphite; natural graphite; graphitized mesophase carbon spherules; graphite whiskers; polyacenese-based substances. Amorphous carbonaceous materials such as; petroleum-based pitches, coal-based pitches, mesocarbon microbeads, coke, carbonic materials such as synthetic resins (eg, phenolic resins, etc.) Carbonated materials obtained by heat treatment of precursors; full Thermal decomposition products of frill alcohol resin or novolak resin; fullerene; carbon nanophones; and composite carbon materials thereof can be mentioned.

The carbon material is preferably a material containing graphite as a main component from the viewpoint of adsorption and desorption of lithium ions. Having graphite as a main component means that the content of graphite is 50% by mass or more based on the mass of the carbon material.

[Arbitrary ingredient]
The negative electrode active material layer in the present invention may contain an optional component such as a conductive filler, a binder, and a dispersion stabilizer, in addition to the negative electrode active material, if necessary.
The type of the conductive filler is not particularly limited, and examples thereof include acetylene black, ketjen black, and vapor phase 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 with respect to 100 parts by mass of the negative electrode active material. It is more preferably 0 parts by mass or more and 20 parts by mass or less, and further preferably 0 parts by mass or more and 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 and the like. 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 part by mass or more, sufficient electrode strength is developed. 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 dispersion stabilizer used is preferably more than 0 parts by mass 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 in the present invention is preferably a metal foil having high electron conductivity and not deteriorated by elution into a non-aqueous electrolyte solution and reaction with an electrolyte or ions. Further, it is more preferable that the negative electrode current collector is a plain foil. When the negative electrode current collector is a perforated foil, the rigidity of the perforated part depends on the rigidity of the active material, but in the case of a plain foil, the rigidity of the electrode is maintained high by the current collector foil even if the rigidity of the active material is low. be able to. Such metal foil is not particularly limited, and examples thereof include aluminum foil, copper foil, nickel foil, and stainless steel foil. A copper foil is preferable as the negative electrode current collector in the non-aqueous lithium storage element of the present embodiment.

[Electrolytic solution]
The electrolytic solution of 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 preferably contains 0.5 mol / L or more of a 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.

[Lithium salt]
The non-aqueous electrolyte solution of the present embodiment has, as lithium salts, 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 mol / L or more and 2.0 mol / L or less, based on the total amount of the non-aqueous electrolyte solution. .. 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 electrolytic solution and the viscosity of the electrolytic solution from becoming too high, resulting in a decrease in conductivity. It is preferable because it does not deteriorate the output characteristics.

The non-aqueous electrolyte solution of the present embodiment preferably contains _{LiN (SO 2} F) ₂ having a concentration of 0.1 mol / L or more and 1.5 mol / L or less based on the total amount of the non-aqueous electrolyte solution. The concentration of SO ₂ F) ₂ is more preferably 0.3 mol / L or more and 1.2 mol / L or less. When the LiN (SO ₂ F) ₂ concentration is 0.1 mol / L or more, the ionic conductivity of the electrolytic solution is increased, and an appropriate amount of the electrolyte film is deposited on the negative electrode interface, whereby the gas due to the decomposition of the electrolytic solution is released. Can be reduced. On the other hand, when this concentration is 1.5 mol / L or less, precipitation of the electrolyte salt does not occur during charging and discharging, and the viscosity of the electrolytic solution does not increase even after a long period of time.

[Non-aqueous solvent]
The non-aqueous electrolyte solution of the present embodiment 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 in the positive electrode active material layer. Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), 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, it is possible to dissolve a lithium salt having a desired concentration, and high lithium ion conductivity can be exhibited. Further, an appropriate amount of the 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 of the present embodiment contains a chain carbonate as a non-aqueous solvent. The inclusion of the chain carbonate in the non-aqueous electrolyte solution is advantageous in that it exhibits high lithium ion conductivity. Examples of the chain carbonate include dialkyl carbonate compounds typified by dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), 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. be. 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.

[Separator]
The positive electrode precursor and the negative electrode are laminated and wound via the separator to form 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 micro shorts tends to be small. On the other hand, a thickness of 35 μm or less is preferable because the input / output characteristics of the non-aqueous lithium storage element tend to be high.
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 micro shorts tends to be small. On the other hand, a thickness of 10 μm or less is preferable because the input / output characteristics of the non-aqueous lithium storage element tend to be improved.

[Non-aqueous lithium-type power storage element]
As shown in FIGS. 1 to 3, the non-aqueous lithium storage element of the present embodiment includes a flat electrode winding body 6 in which a positive electrode precursor and a negative electrode are laminated and pressed via a separator. It is housed and sealed in an exterior body (flat square can 4) together with a non-aqueous electrolyte solution. Further, from the viewpoint of rigidity, it is preferable that both the positive and negative current collectors included in the electrode winding body are plain foils.

Next, a method for manufacturing the non-aqueous lithium-type power storage element as described above will be described.
That is, the method for manufacturing the non-aqueous lithium storage element of the present embodiment is as follows.
The following steps:
(1) A step of forming a positive electrode active material layer containing activated carbon and a lithium compound on a positive electrode current collector to obtain a positive electrode precursor;
(2) An electrode laminate including a positive electrode precursor, a negative electrode having a negative electrode active material layer capable of occluding and releasing lithium ions on a negative electrode current collector, and a separator arranged between the positive electrode precursor and the negative electrode. Forming process;
(3) A step of winding an electrode laminate to form an electrode wound body;
(4) A step of pressing the electrode winding body to form a flat electrode winding body;
(5) The flat electrode winder is housed in a flat square can, a non-aqueous electrolytic solution containing a lithium salt different from the lithium compound is injected from the opening of the flat can, and the opening is sealed. , A step of forming a sealed non-aqueous lithium storage element; and (6) a state in which the sealed non-aqueous lithium storage element is sandwiched between a pair of jigs having a pressure surface and pressurized in the thickness direction of the flat square can. A step of decomposing lithium carbonate to generate lithium ions and doping the negative electrode active material layer with the lithium ions;
In the method for manufacturing a non-aqueous lithium storage element of the present embodiment, when the maximum pressure in the main surface of the flat square can is P _max and the minimum pressure in the surface is P _min in the doping step (6), ( It is characterized in that pressurization is performed so that P _max −P _min ) / P _{max ≦ 0.5.}
Hereinafter, each step will be described in detail.

(1) A positive electrode active material layer containing activated carbon and a lithium compound is formed on a positive electrode current collector to obtain a positive electrode precursor.
[Manufacturing of positive electrode precursor]
In the present embodiment, the positive electrode precursor to be 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, a positive electrode active material, a lithium compound, and other optional components used as necessary are dispersed or dissolved in water or an organic solvent to prepare a slurry-like coating liquid, and this coating liquid is collected as a positive electrode. A positive electrode precursor can be obtained by applying a coating film on one or both sides of an electric body to form a coating film and drying the coating film. Further, the obtained positive electrode precursor may be pressed to adjust the film thickness or bulk density of the positive electrode active material layer. Alternatively, without the use of solvents, the positive electrode active material and lithium compound, as well as other optional components used as needed, are dry mixed, the resulting mixture is press molded and then conductively bonded. It is also possible to attach the agent to the positive electrode current collector.

The coating liquid of the positive electrode precursor is a dry blend of a part or all of various material powders including a positive electrode active material, and then water or an organic solvent and / or a binder or a dispersion stabilizer is dissolved or dispersed in them. The liquid or slurry-like substance may be added and prepared. Further, various material powders containing a positive electrode active material may be added to a liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent to prepare a coating liquid. good. As the method of dry blending, for example, a positive electrode active material and a lithium compound are premixed using a ball mill or the like, and if necessary, a conductive filler is premixed so that the lithium compound having low conductivity is coated with the conductive filler. You may do. This facilitates the decomposition of the lithium compound 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 the lithium compound, so a pH adjuster may be added if necessary.

The preparation of the coating liquid for the positive electrode precursor is not particularly limited, but preferably a homodisper or a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirling high-speed mixer or the like is used. Can be done. In order to obtain a coating liquid in a good dispersed state, it is preferable to perform dispersion at a peripheral speed of 1 m / s or more and 50 m / s or less. When the peripheral speed is 1 m / s or more, it is preferable because various materials are satisfactorily dissolved or dispersed. Further, when the peripheral speed 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 80 μm or less in particle size, and further preferably 50 μm or less in particle size. If the particle size is less than 0.1 μm, 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, there is no clogging at the time of discharging the coating liquid, streaks of the coating film are not generated, and stable coating can be performed.

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, still more preferably 1. , 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 formation of the coating film is suppressed, and the width and film thickness of the coating film can be satisfactorily controlled. Further, when the viscosity (ηb) 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 is less than the desired thickness. Can be controlled.
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 the film 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 a single-layer coating or a multi-layer coating. In the case of multi-layer coating, the coating liquid composition may be adjusted so that the content of the lithium compound 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 the coating speed 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. Further, the coating film may be dried 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 drying temperature is 200 ° C. or lower, it is possible to suppress cracking of 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.

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 the press pressure 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 or 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 positive electrode precursor after drying so as to have a desired film thickness or bulk density of the positive electrode active material layer. Further, the pressing speed can be set to any 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 the pressed portion may be heated if necessary. The lower limit of the surface temperature of the pressed portion in the case of heating is preferably a melting point of minus 60 ° C. or higher, more preferably a melting point of −45 ° C. or higher, and further preferably a melting point of −30 ° C. or higher. On the other hand, the upper limit of the surface temperature of the pressed portion in the case of heating is preferably the melting point plus 50 ° C. or lower, more preferably the melting point plus 30 ° C. or lower, and further preferably the melting point plus 20 ° C. or lower. For example, when PVdF (polyvinylidene fluoride: melting point 150 ° C.) is used as the binder, it is preferable to heat the surface of the pressed portion to 90 ° C. or higher and 200 ° C. or lower, more preferably 105 ° C. or higher and 180 ° C. or lower, and further. It is preferably heated to 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 preferable to heat the surface of the pressed portion to 40 ° C. or higher and 150 ° C. or lower, and more preferably 55 ° C. or higher and 130 ° C. or lower. More preferably, it is heated to 70 ° 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). 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 temperature rise 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 film 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. The thickness of the positive electrode active material layer is more preferably 25 μm or more and 100 μm or less, and further preferably 30 μm or more and 80 μm or less per one side. When this film thickness is 20 μm or more, a sufficient charge / discharge capacity can be developed. On the other hand, when this film thickness 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 upper and lower limits of the film thickness range of the positive electrode active material layer can be arbitrarily combined. The film thickness of the positive electrode active material layer when the current collector has irregularities means the average value of the film thickness per one side of the portion of the current collector that does not have irregularities.

(1-1) A negative electrode active material layer capable of occluding and releasing lithium ions is formed on a negative electrode current collector to obtain a negative electrode.
[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-like 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 or bulk density of the negative electrode active material layer. Alternatively, a method in which various materials including a negative electrode active material are mixed in a dry manner without using a solvent, the obtained mixture is press-molded, and then attached to a negative electrode current collector using a conductive adhesive. Is also possible.

The coating liquid is prepared by dry-blending a part or all of various material powders including the negative electrode active material, and then water or an organic solvent and / or a liquid or a dispersion in which a binder or a dispersion stabilizer is dissolved or dispersed. A slurry-like substance may be added and prepared. Further, various material powders containing a negative electrode active material may be added to a liquid or slurry-like substance in which a binder or a dispersion stabilizer is dissolved or dispersed in water or an organic solvent. Although the preparation of the coating liquid is not particularly limited, a homodisper or a multi-axis disperser, a planetary mixer, a disperser such as a thin film swirling high-speed mixer and the like can be preferably 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 the peripheral speed 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. It is 5,000 mPa · s or less. When the viscosity (ηb) is 1,000 mPa · s or more, liquid dripping during formation of the coating film is suppressed, and the width and film thickness of the coating film can be satisfactorily controlled. Further, 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 the film 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 a single-layer coating or a 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 the coating speed 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. Further, a plurality of drying methods may be combined and dried. 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 drying temperature is 200 ° C. or lower, it is possible to suppress cracking of the coating film due to rapid volatilization of the solvent or uneven distribution of the binder due to migration, and oxidation of the negative electrode current collector or the negative electrode active material layer.

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, the surface temperature of the press portion, etc., 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 the press pressure is 20 kN / cm or less, the negative electrode does not bend or wrinkle, and the film thickness or bulk density of the negative electrode active material can be adjusted to a desired value. Further, the gap between the press rolls can be set to an arbitrary value according to the film thickness of the negative electrode after drying so as to have a desired film thickness or bulk density of the negative electrode active material layer. Further, the pressing speed can be set to any 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 in the case of heating is preferably the melting point of the binder to be used at −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 in the case of heating is preferably the melting point of the binder used plus 50 ° C. or lower, more preferably 30 ° C. or lower, still more 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 preferable to heat it to 40 ° C. or higher and 150 ° C. or lower. It is more preferably 55 ° C. or higher and 130 ° C. or lower, and further preferably 70 ° 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). 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 temperature rise 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 film thickness of the negative electrode active material layer is preferably 5 μm or more and 100 μm or less per one side. The lower limit of the film 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 film thickness of the negative electrode active material layer is more preferably 80 μm or less, and more preferably 60 μm or less. When this film thickness 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 this film thickness is 100 μm or less, high energy density can be developed by reducing the cell volume. The film thickness of the negative electrode active material layer when the current collector has irregularities means the average value of the film thickness per one side of the portion of the current collector that does not have 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. Further, if it is 1.8 g / cm ³ or less, it is possible to secure pores in which ions can be sufficiently diffused in the negative electrode active material layer.

(2) An electrode laminate including a positive electrode precursor, a negative electrode, and a separator arranged between the positive electrode precursor and the negative electrode is formed.
(3) The electrode laminated body is wound to form an electrode wound body.
(4) The electrode winding body is pressed to form a flat electrode winding body.
[assembly]
The electrode winding body obtained in the cell assembly step is made by stacking a positive electrode precursor and a negative electrode via a separator to form an electrode laminated body, winding them in a spiral shape, and then pressurizing them to flatten them. The mold electrode winding body 6 is formed by connecting the positive electrode terminal 7 and the negative electrode terminal 8. The winding end of the electrode winding body may be fixed with insulating tape. At this time, it is preferable that the insulating tape used for fixing the electrode winding body is located at the bent portion of the electrode winding body. 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.

(5) The flat electrode winder is housed in a flat square can, a non-aqueous electrolytic solution containing a lithium salt different from the lithium compound is injected from the opening of the flat can, and the opening is sealed. , Form a sealed non-aqueous lithium storage element.

[Exterior body]
The exterior body includes a flat square can 4 and a lid plate 9. A positive electrode terminal 7 and a negative electrode terminal 8 connected to one ends of the positive electrode precursor and the negative electrode are drawn out from the flat electrode winding body 6 composed of the positive electrode precursor, the negative electrode, and the separator.
Further, a positive electrode terminal 7 and a negative electrode terminal 8 are attached to a lid plate 9 that seals and seals the opening of the flat square can 4 via an insulating packing 10.
The flat square can 4 and the lid plate 9 are made of, for example, an aluminum alloy.

Then, the lid plate 9 is inserted into the opening of the flat square can 4, and by welding the joint between the two, the opening of the flat can 4 is sealed and the inside of the power storage element is sealed. Further, in the example shown in FIG. 1, a non-aqueous electrolytic solution injection port 14 is provided on the lid plate 9, and the non-aqueous electrolytic solution injection port 14 is, for example, laser welded with a sealing member inserted. It is welded and sealed by means of such as, and the airtightness of the power storage element is ensured. Further, the lid plate 9 is provided with a cleavage vent 15 as a mechanism for discharging the internal gas to the outside when the temperature of the power storage element rises.

[Storage in the exterior]
The flat electrode winding body 6 is welded to the positive electrode terminal 7 and the negative electrode terminal 8, inserted into the flat square can 4, and the lid plate 9 is welded to the open end of the flat can 4.

[Drying]
It is preferable that the electrode wound body housed in the outer 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 residual solvent is preferably 1.5% by mass or less per mass of the positive electrode active material layer or the negative electrode active material layer. If the residual solvent is more than 1.5% by mass, the solvent remains in the system and the self-discharge characteristics or the cycle characteristics are deteriorated, which is not preferable.

[Liquid injection, impregnation, sealing process]
After the assembly step is completed, the non-aqueous electrolyte solution is injected into the electrode winding body 6 housed in the flat square can 4 from the electrolyte solution injection port 14 provided in the lid plate 9 of the exterior body. 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 electrolyte solution. When the non-aqueous electrolyte 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. It rises or becomes less durable. The method of impregnation is not particularly limited, but for example, the electrode winding body after injection is installed in a decompression chamber with the outer body open, and the inside of the chamber is decompressed by using a vacuum pump. A method of returning to atmospheric pressure again can be used. After that, the electrolytic solution injection port 14 is sealed.

(6) A sealed non-aqueous lithium storage element is sandwiched between a pair of jigs having a pressurized surface, and the lithium compound is decomposed to generate lithium ions while the pressure is applied in the thickness direction of the flat square can. , Lithium ion is doped into the negative electrode active material layer.
[Lithium dope process]
In the lithium doping step, preferably, a voltage is applied between the positive electrode precursor and the negative electrode to decompose the lithium compound, thereby decomposing the lithium compound (for example, lithium carbonate) in the positive electrode precursor and lithium. Lithium ions are predoped into the negative electrode active material layer by releasing the ions and reducing the lithium ions at the negative electrode.
_{In this lithium doping step, gas such as CO 2} is generated due to oxidative decomposition of the lithium compound 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 discharge means such as a gas vent valve or a gas permeable film is previously installed in the part of the exterior body. A method of applying a voltage with the above;
Further, this lithium doping step is preferably performed in a dry environment (eg, humidity of 30% or less).

[Pressurization by jig]
In the present embodiment, as shown in FIG. 4, the lithium doping step is performed by sandwiching a sealed non-aqueous lithium storage element between a pair of jigs 20 having a pressure surface 20a and pressurizing the flat square can 4 in the thickness direction. Do it in the same state.
When the flat electrode winding body is pressurized in the thickness direction, if there are pressure spots in the pressure plane, spots occur in the distance between the positive electrode and the negative electrode, so that potential difference spots occur in the plane of the positive and negative electrodes. This may result in spots on the dope.
Further, as described above, the displacement between the positive electrode, the separator, and the negative electrode due to the bending portion or rewinding of the flat electrode winding body 6 causes unevenness in the distance between the positive electrode and the negative electrode, and as a result, the doping is uniform. There is a possibility that it will not be done (there is uneven doping).

Therefore, in the present embodiment, the non-aqueous lithium storage element is sandwiched between a pair of jigs having a pressurized surface, and the lithium compound is decomposed in a state of being pressurized in the thickness direction of the flat square can to generate lithium ions. In the step of doping the negative electrode active material layer with lithium ions, when the main surface of the flat square can is pressurized, the maximum pressure applied in the main surface is P _max and the minimum pressure is P _min. Pressurization is performed so that P _max −P _min ) / P _{max ≦ 0.5. Preferably, (P max -P min) /} P a _max ≦ 0.4, more preferably from _{(P max} -P min) /Pmax≦0.3. When (P _{max −} P _min ) / P _max is 0.5 or less, the pressure unevenness in the plane due to pressurization can be reduced when doping the non-aqueous lithium storage element, so that between the positive and negative electrodes in the electrode body. The variation in the distance can be suppressed, and the Li-doping reaction in the doping step can be made uniform over the entire in-plane area.

<Measurement method of surface pressure distribution of non-aqueous lithium storage element>
A surface pressure distribution measurement system I-SCAN (manufactured by Nitta Corporation) is used as a method for measuring the surface pressure distribution in the pressurization of the non-aqueous lithium storage element of the present embodiment. The sensor sheet for measuring the surface pressure distribution preferably has an area covering the entire pressurized surface of the non-aqueous lithium storage element. For example, if the pressurized surface is 60 mm in length × 100 mm in width, an I-SCAN100 sensor (measurement surface dimensions: 112 mm × 112 mm) can be used.
The sensor sheet is arranged between the main surface of the exterior body of the non-aqueous lithium power storage element and a pair of jigs having a pressurized surface.
The maximum measured pressure of the sensor sheet is preferably greater than or equal to the maximum pressing force applied to the non-aqueous lithium storage element and preferably not more than three times the maximum pressing force. For example, if the maximum pressure applied to the non-aqueous lithium storage element is 5 kgf / cm ² , the maximum measured pressure of the ^{sensor sheet is preferably 5 kgf / cm 2} or more and 15 kgf / cm ² or less. Therefore, for example, the sensor sheet is I-. It is preferable to use SCAN100 (R) (maximum measurement pressure: 13 kgf / cm ^2). If the maximum measured pressure of the sensor sheet is greater than or equal to the maximum pressure applied to the non-aqueous lithium storage element and less than three times the maximum pressure applied, the in-plane pressure applied to the non-aqueous lithium storage element is accurately measured. It is preferable because it can be used.
The number of sensor points on the sensor sheet is preferably 400 points (length 20 x width 20 points) or more, and more preferably 900 points or more (length 30 x width 30 points). For example, when the pressurized area S ₁ is 60 mm in length × 100 mm in width (60 cm ² ), the I-SCAN 100 sensor (measurement area S _s : 112 mm × 112 mm = 125.44 cm ² , sensor points 1936 points) can be applied. The number of sensor points used for the entire pressurized surface is S ₁ / S _s × 1936 points = 926 points, which is preferable.
In the present specification, kgf / cm ² is used as an example of the unit of pressure, but the unit may be any one indicating pressure, and may be, for example, Pa, mmHg, Bar, atm, or the like.

The data acquired by I-SCAN obtained above can easily detect excessive pressure that is not related to the actual pressure due to the influence of burrs on the jig at the edges and corners of the jig. Not used as data to evaluate in-plane pressure spots. Specifically, regarding the measured total pressure data in the pressurized surface, the three points of the data on the four sides are not used as data. For example, if the data in the pressure plane is 44 points vertically x 30 points horizontally, the rows for the first 3 points and the rows for the last 3 points are deleted from the 44 points vertically, and the rows for the last 3 points are deleted. , In-plane pressure spots are evaluated using the data with the first 3 points and the last 3 points removed.

Since the surface pressure distribution data acquired by the I-SCAN obtained above contains noise such as measurement error, the noise is eliminated by averaging. As shown in FIG. 6, the averaging is performed by the pressure data P (m, n) at one point and the pressure data P (m + a, P + b) at eight points surrounding the point (a and b are independently -1,0, respectively. , 1 and other than a = b = 0), and the average value of the pressures at 9 points in total is _Pavg (m, n) (Equation (1)).
P _avg (m, n) = ΣP (m + a, n + b) / 9 ... Equation (1)
(A and b are independently -1, 0, 1)

By using the data of the surface pressure distribution measured as described above, (P _{max −} P _min ) / P _max can be calculated.

In the present embodiment, it is preferable to pressurize the peripheral portion of the flat square can 4 so that the applied force is larger than that of the central portion in the main surface of the can.
In the present embodiment, the flat square can 4 is housed in the flat can 4 by pressurizing the peripheral portion rather than the central portion in the main surface of the flat square can 4 so that the applied force becomes larger. The bent portion and the wound end surface (peripheral portion) of the flat electrode winding body 6 are pressurized more strongly than the other portions (central portion). That is, by pressurizing the peripheral portion of the flat square can 4 more strongly at the time of doping, the bent portion and the wound end surface of the flat electrode winding body 6 are fixed, and the positive electrode, the separator, and the negative electrode due to the bent portion and the rewinding are fixed. Positional deviation can be suppressed. As a result, the doping can be performed evenly and uniformly.

In the present embodiment, the "peripheral portion" and the "central portion" on the main surface of the flat square can 4 are not particularly limited as long as the above object can be achieved, but for example, for example. As shown in FIG. 5, in the main surface of the flat square can 4, the region surrounded by one-third of the outer circumference in the line segment connecting the center C and the outer circumference (vertex and four sides) is the “central portion”. The other parts are referred to as "peripheral parts".

The method of pressurizing the peripheral portion of the flat square can 4 so that the applied force is larger than that of the central portion in the main surface is not particularly limited, but for example, FIGS. 4 and 4 and FIGS. As shown in 5, it is preferable to pressurize the pressurizing surface 20a by using a jig 20 having an inclination 20b such that the central portion is concave. The pressurized surface having an inclination may be a curved surface, a combination of planes, or a combination of a plane and a curved surface.
Further, the jig 20 is preferably made of a material having a thermal conductivity of 200 W / m · K or more. As a result, the in-plane temperature can be made uniform. Further, when the element generates heat in the lithium doping process, heat can be quickly dissipated.

As a pressurizing method before the doping process of the non-aqueous lithium storage element according to the present embodiment, the hardness measured by JIS K6253 is used as the material of the pressurized surface of the jig that comes into contact with the flat surface of the exterior of the non-aqueous lithium storage element. , Shore A5 or more, and shore A70 or less are preferable. It is more preferably shore A20 or more and shore A65 or less, and further preferably shore A6530 or more and shore A60 or less. When the hardness of the material of the pressure surface of the pressure jig is within the above range, a suitable pressure is applied to the flat surface of the exterior body of the non-aqueous lithium storage element, the pressure distribution in the surface is relaxed, and the pressure unevenness is applied. Can be pressurized with less pressure.
There is no particular limitation on the method of changing the material of the pressurized surface. For example, the change may be made by attaching a sheet-like material to the pressurized surface of the jig body, or the material of the jig body itself may be changed.

In the non-aqueous lithium storage element according to the present embodiment, the position of the insulating tape for fixing the electrode body is preferably not the flat portion of the electrode body. For example, in the case of a flat wound body, the position of the insulating seal is preferably the bent R portion of the flat wound body. When the insulating tape is on the flat part of the electrode body, when the flat surface of the exterior body of the non-aqueous lithium storage element is pressed, the thickness of the fixing tape inside the exterior body causes local pressure on the electrode body. This is not preferable because it causes Li-doped spots in the doping process.

The average pressing force of the non-aqueous lithium storage element according to the present embodiment ^{is preferably 0.5 kgf / cm 2} or more and 20 kgf / cm ² or less. It is more preferably 1 kgf / cm ² or more and 15 kgf / cm ² or less, and further preferably 1.5 kgf / cm ² or more and 10 kgf / cm ² or less. Mean pressure _{P A,} when a load W (kgf) applied to the flat portion of the non-aqueous lithium storage element has a pressure area _S 1 of the compressing clamp (cm _^2), is calculated by P A = W / _{S 1} NS. Within the above range average pressure P _A, the entire flat surface of the electrode body without generating fine short can apply a sufficient pressure, it is possible to promote the Li doped reaction.

[Aging process]
After the lithium doping step is completed, it is preferable to perform aging on the electrode winding body. In the aging step, the solvent in the non-aqueous electrolyte 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, and for example, a method of reacting a solvent in a non-aqueous electrolyte 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 non-aqueous electrolyte solution, the positive electrode, and the negative electrode. In a state where gas remains in at least a part of the non-aqueous electrolyte 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.

<Characteristic evaluation of non-aqueous lithium storage element>
[Capacitance]
In the present specification, the capacitance Fa (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 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. Perform constant voltage charging for a total of 30 minutes. After that, the capacity when a constant current discharge is performed with a current value of 2C up to 2.2V is defined as Q (C). Using the Q obtained here and the voltage change ΔV _x (V), the value calculated by the capacitance Fa = Q / ΔV _x = Q / (3.8-2.2) is the capacitance Fa. It is called (F).
Here, the current discharge rate (also referred to as "C rate") is the relative ratio of the current at the time of discharge to the discharge capacity, and generally, when performing constant current discharge from the upper limit voltage to the lower limit voltage, it takes 1 hour. The current value at which the discharge is completed is called 1C. In the present specification, 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 is defined as 1C.

[Internal resistance]
As used herein, the internal resistance Ra (Ω) is a value obtained by the following method:
First, in a constant temperature bath in which the non-aqueous lithium storage element is set to 25 ° C, constant current charging is performed until the current value of 20C reaches 3.8V, and then constant voltage charging is performed by applying a constant voltage of 3.8V. Do this for a total of 30 minutes. Subsequently, the sampling interval is set to 0.1 seconds, and constant current discharge is performed up to 2.2 V at 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 second obtained by extrapolating from the voltage values at the discharge times of 2 seconds and 4 seconds is taken as Eo, the voltage drop ΔE = 3.8-. It is a value calculated from Eo as Ra = ΔE / (current value of 20C).

[High load charge / discharge cycle test]
In the present specification, the resistance change rate and the amount of gas generated after the high load charge / discharge cycle test are measured by the following methods.
(Rate of resistance change after high load charge / discharge cycle)
First, the cell corresponding to the non-aqueous lithium 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 200 C, and then to 2.2 V at a current value of 200 C. Discharge with constant current until it reaches the point. This high load charge / discharge cycle is repeated 60,000 times, and the internal resistance Rb after the high load charge / discharge cycle is measured according to the above method for measuring internal resistance. Let Rb / Ra be the rate of change in resistance after a high load charge / discharge cycle.

[Power storage module]
Generally, the power storage module is also referred to as a battery module, a capacitor module, a capacitor module, a storage battery or a battery, and the power storage element is also referred to as a capacitor, a cell, a storage cell or a storage battery.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

(Example 1)
[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, the peripheral speed is 10.0 m / s. Was crushed for 9 minutes. The lithium carbonate particle size to be charged was determined by measuring the average particle size of the lithium carbonate obtained by preventing thermal denaturation at -196 ° C. and brittle fracture, and found to be 2.0 μm.

[Preparation of positive electrode active material]
[Preparation of activated carbon]
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 in the preheating furnace, and the temperature was raised to 900 ° C. over 8 hours for activation. The activated carbonized material 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 for 10 hours in an electric dryer kept at 115 ° C., activated carbon was obtained by pulverizing with a ball mill for 1 hour.

[Preparation of positive electrode coating liquid]
The positive electrode coating liquid (composition a) was produced by the following method using the activated carbon obtained above as the positive electrode active material and the lithium carbonate obtained above as the charged lithium compound.
46.5 parts by mass of activated carbon, 38.0 parts by mass of lithium carbonate or oxidation, sulfide or lithium hydroxide, 4.0 parts by mass of Ketjen Black, 1.5 parts by mass of PVP (polyvinylpyrrolidone), and PVDF ( (Polyfluoride vinylidene) is mixed with 10.0 parts by mass and NMP (N-methylpyrrolidone), and this is mixed with a thin film swirling high-speed mixer fill mix manufactured by PRIMIX under the condition of a peripheral speed of 17.0 m / s. It was dispersed to obtain a coating liquid.

[Preparation of positive electrode precursor]
The above coating liquid is 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. at a coating speed of 1 m / s, and dried at a drying temperature of 100 ° C. to obtain a positive electrode precursor. Obtained. 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 pressed portion of 25 ° C.

[Manufacturing of negative electrode]
[Preparation example of negative electrode]
150 g of artificial graphite with an average particle size of 4.9 μm and a BET specific surface area of 6.1 m ² / g was placed in a stainless steel mesh cage, and 15 g of coal-based pitch (softening point: 65 ° C.) was placed. They were placed on a stainless steel bat and both were installed in an electric furnace (effective size in the furnace 300 mm × 300 mm × 300 mm). This was heated to 1000 ° C. in a nitrogen atmosphere in 8 hours and kept at the same temperature for 4 hours to cause a thermal reaction to obtain a composite carbon material 1. The obtained composite carbon material was cooled to 60 ° C. by natural cooling and then taken out from an electric furnace.

The negative electrode 1 was manufactured using the composite carbon material as the negative electrode active material.
80 parts by mass of composite carbon material, 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 mixer manufactured by PRIMIX. A coating liquid was obtained by dispersing using a fill mix under the condition of a peripheral speed of 15 m / s. As a result of measuring the viscosity (ηb) and TI value of the obtained coating liquid using an E-type viscometer TVE-35H manufactured by Toki Sangyo Co., Ltd., the viscosity (ηb) was 2,791 mPa · s and the TI value was 2. It was 7. The above coating liquid is applied to both sides of an electrolytic copper foil (plain foil) having a thickness of 10 μm and having no through holes at a coating speed of 1 m / s using a die coater manufactured by Toray Engineering Co., Ltd., and the drying temperature is changed. It was dried at 85 ° C. to obtain a negative electrode. The obtained negative electrode was pressed using a roll press machine.

[Preparation of electrolytic solution]
As an organic solvent, a mixed solvent of ethylene carbonate (EC): methyl ethyl carbonate (MEC) = 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 25:75 (molar ratio) is non-aqueous electrolysis. Used as a liquid.
_{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.

A non-aqueous lithium power storage element was prepared as follows using a positive electrode active material, a positive electrode coating liquid, a lithium compound, a current collector and a negative electrode active material.

[Preparation of non-aqueous lithium-type power storage element]
[Assembly process]
The obtained double-sided negative electrode 1 and double-sided positive electrode precursor were cut into strips of ^{12.0 cm × 210.0 cm (2520 cm 2).} A microporous membrane separator having a thickness of 15 μm was sandwiched between the negative electrode and the positive electrode precursor, laminated, spirally wound, and then pressed so as to be flat to form a flat electrode wound body. At this time, an insulating tape for fixing the flat electrode winding body was attached to the R portion formed on the electrode winding body. 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.
This electrode wound body was vacuum dried at a temperature of 80 ° C. and a pressure of 50 Pa under the conditions of a drying time of 60 hr. The dried electrode winding body was housed in an exterior body made of a flat square can made of an aluminum alloy having an outer size of 5 mm, a width of 150 mm, and a height of 70 mm in a dry environment with a dew point of −45 ° C. Then, a lid plate was inserted into the opening of the flat square can, and the joint between the two was welded to seal the opening of the flat can.

[Liquid injection, impregnation, sealing process]
About 80 g of the above non-aqueous electrolyte solution is applied to the electrode winding body housed in the exterior body from the electrolyte solution injection port provided on the lid plate of the exterior body under a dry air environment with a dew point of -40 ° C or less. It was injected under atmospheric pressure at a temperature of 25 ° C. Subsequently, 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 process 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 the pressure was returned to atmospheric pressure. Similarly, the steps of depressurizing and returning to atmospheric pressure were repeated 7 times in total (decompressed to -95, 96, 97, 81, 97, 97, 97 kPa, respectively). By the above steps, the electrode winding body was impregnated with the non-aqueous electrolyte solution. Then, the electrolytic solution injection port was sealed.

[Lithium dope process]
The obtained non-aqueous lithium-type power storage element is charged with a constant current using a charging / discharging device (TOSCAT-3100U) manufactured by Toyo System Co., Ltd. until the voltage reaches 4.5 V at a current value of 50 mA under a 25 ° C environment. After that, the initial charge was continuously carried out by a method of continuing 4.5 V constant voltage charging for 72 hours, and the negative electrode was lithium-doped.
At this time, the exterior body (flat square can) was sandwiched between a pair of jigs having a pressure surface as shown in FIG. 4, and the pressure was applied in the thickness direction of the flat square can with a force of 500 kgf. .. This jig has an inclination such that the central portion is concave on the pressure surface, so that the force applied to the peripheral portion is larger than that of the central portion in the main surface of the flat square can. Was pressurized. When the surface pressure distribution measurement system I-SCAN and I-SCAN 100 (R) as the sensor sheet were used for measurement and the above-mentioned data processing was performed, the maximum in-plane pressure Pmax was 9.1 kgf / cm ² / cm. The pressing force in the peripheral portion was 5.5 kgf / cm ² . The jig body was made of aluminum (thermal conductivity: 236 W · m ^-1 · K ^-1 .

[Aging process]
The lithium-doped non-aqueous lithium-type power storage element is subjected to constant current discharge at 1.0 A at 1.0 A until the voltage reaches 3.0 V, and then 3.0 V constant current discharge is performed for 1 hour to reduce 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]
After aging, the flat wound electrode body was opened with a liquid injection hole at a temperature of 25 ° C. and a dew point of −40 ° C. in a dry air environment. Subsequently, the flat wound electrode body was placed in the decompression chamber, and the pressure was reduced from atmospheric pressure to -80 kPa for 3 minutes using a diaphragm pump (KNF, N816.3KT.45.18) for 3 minutes. The process of returning to atmospheric pressure was repeated three times in total. Then, the flat wound electrode body was put in the decompression device, the pressure was reduced to −90 kPa, and then the aluminum lid was sealed again by laser welding the injection hole to prepare a non-aqueous lithium storage element. Through the above steps, a non-aqueous lithium storage element was manufactured.

<Evaluation of non-aqueous lithium storage element>
[Measurement of capacitance Fa]
For one of the obtained non-aqueous lithium storage elements, a current value of 2C was used in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Fukushima Limited. Constant current charging was performed at (1.6A) until it reached 3.8V, followed by constant voltage charging to which a constant voltage of 3.8V was applied for a total of 30 minutes. After that, the capacitance when constant current discharge is applied to a current value of 2C (1.6A) up to 2.2V is defined as Q [C], and the capacitance calculated by F = Q / (3.8-2.2). The capacity Fa was 1722F.

[Measurement of internal resistance Ra]
The non-aqueous lithium storage element is 3.8V at a current value (16A) of 20C using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Fukushima Limited in a constant temperature bath set at 25 ° C. It was charged with a constant current until it reached the above, and then a constant voltage charge with a constant voltage of 3.8 V was performed for a total of 30 minutes. After that, the sampling time was set to 0.1 seconds, and constant current discharge was performed up to 2.2 V at a current value (16 A) of 20 C to obtain a discharge curve (time-voltage). In this discharge curve, the voltage at the discharge time = 0 second obtained by extrapolating from the voltage values at the time points of the discharge time of 2 seconds and 4 seconds is defined as Eo, the voltage drop ΔE = 3.8-Eo, and. When the internal resistance Ra was calculated by R = ΔE / (current value 20C), it was 1.46 mΩ.

[High load charge / discharge cycle test]
3. Regarding the non-aqueous lithium storage element, a current value (160A) of 200C was used in a constant temperature bath set at 25 ° C. using a charging / discharging device (5V, 360A) manufactured by Fujitsu Telecom Networks Limited. The charging / discharging process of constant current charging until reaching 8 V and then constant current discharging at a current value of 200 C was repeated 60,000 times under the condition of no pause. When the internal resistance Rb was measured after the end of the cycle, it was 1.57 mΩ, and Rb / Ra = 1.08.

(Examples 2 to 8 and Comparative Examples 1 to 2)
Regarding the pressurizing jig in the lithium doping step, a non-aqueous lithium storage element was produced by the same method as in Example 1 except that the pressurized surface was flattened and the materials shown in Table 1 were attached to the pressurized surface. .. The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are also shown in Table 1.

(Examples 9 to 12)
Regarding the pressurizing jig in the lithium-doped step, except that the pressurized surface was flattened, chloroprene rubber (Shore A70) was attached to the pressurized surface, and the pressing force was changed as shown in Table 1, the same as in Example 1. A non-aqueous lithium storage element was manufactured by the same method. The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are also shown in Table 1.

(Example 13)
In the assembly process, the pressurized surface is flattened, chloroprene rubber (shore A70) is attached to the pressurized surface, and the position of the insulating tape for fixing the flat electrode winding body is attached to the flat part (main surface portion) of the electrode winding body. A non-aqueous lithium storage element was produced by the same method as in Example 1 except for the above. The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are shown in Table 1.

(Example 14)
Regarding the pressurizing jig in the lithium doping process, the pressurized surface is flattened, chloroprene rubber (shore A70) is attached to the pressurized surface, and the material of the pressurizing jig body is copper (thermal conductivity: 403 W ・ m ^-1・ K). ^A non-aqueous lithium storage element was produced by the same method as in Example 1 except that the case was changed to -1). The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are shown in Table 1.

(Example 15)
Regarding the pressurizing jig in the lithium doping process, the pressurized surface is flattened, chloroprene rubber (shore A70) is attached to the pressurized surface, and the material of the pressurizing jig body is a carbon material (thermal conductivity: 173 W ・ m ^-1. A non-aqueous lithium storage element was produced by the same method as in Example 1 except that the case was changed to K- ^1). The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are shown in Table 1.

(Comparative Example 3)
Regarding the pressurizing jig in the lithium doping step, a non-aqueous lithium storage element was produced by the same method as in Example 1 except that the pressurized surface was flattened. The results of measurements for the internal resistance Ra and the Rb / Ra obtained by the high load charge / discharge cycle test are shown in Table 1.

As is clear from the table, it can be seen that the non-aqueous lithium storage device of the example has a smaller internal resistance and better charge / discharge cycle characteristics than the comparative example.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the spirit of the invention.

The non-aqueous lithium-type power storage element obtained by the manufacturing method of 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. It can be suitably used in the field of a hybrid drive system combining an internal combustion engine or a fuel cell, a motor, and a power storage element, an emergency battery backup application, and an instantaneous power peak assist application.

4 Flat square can 6 Flat electrode winding body 7 Positive electrode terminal 8 Negative terminal 9 Lid plate 10 Insulation packing 14 Non-aqueous electrolyte injection port 15 Cleavage vent 20 Jig 20a Pressurized surface 20b Inclined

Claims (7)

The following steps:
(1) A step of forming a positive electrode active material layer containing activated carbon and a lithium compound on a positive electrode current collector to obtain a positive electrode precursor;
(2) An electrode including the positive electrode precursor, a negative electrode having a negative electrode active material layer capable of occluding and releasing lithium ions on a negative electrode current collector, and a separator arranged between the positive electrode precursor and the negative electrode. Step of forming a laminate;
(3) A step of winding the electrode laminate to form an electrode wound body;
(4) A step of pressing the electrode winding body to form a flat electrode winding body;
(5) The flat electrode winding body is housed in a flat square can, and a non-aqueous electrolytic solution containing a lithium salt different from the lithium compound is injected from the opening of the flat can, and the opening is opened. The step of forming a sealed non-aqueous lithium storage element; and (6) the sealed non-aqueous lithium storage element is sandwiched between a pair of jigs having a pressure surface, and the thickness direction of the flat square can. A step of decomposing a lithium compound to generate lithium ions and doping the negative electrode active material layer with the lithium ions;
In the doping step (6), when the maximum in-plane pressing force of the flat square can is P _max and the in-plane minimum pressing force is P _min , (P _{max −} P _min ) / P _max ≦ Pressurize to 0.5 and at the same time
In the doping step (6), a sealed type is characterized in that pressure is applied to the peripheral portion of the flat square can so as to increase the applied force to the peripheral portion rather than the central portion in the main surface. A method for manufacturing a non-aqueous lithium storage element. The method for manufacturing a sealed non-aqueous lithium storage element according to claim 1 , wherein in the jig, the pressurized surface has an inclination such that the central portion is concave. The sealed non-aqueous lithium storage element according to claim 1 or 2 , wherein the hardness of the material of the pressurized surface in contact with the main surface of the flat square can is shore A5 or more and shore A70 or less as measured by JIS K6253. Manufacturing method. The method for manufacturing a sealed non-aqueous lithium storage element according to any one of claims 1 to 3 , wherein the jig is made of a material having a thermal conductivity of 200 W · m ^-1 · K ^{-1 or more.} The sealed non-aqueous lithium storage element according to any one of claims 1 to 4 , wherein the insulating tape used for fixing the electrode winding body is located at a bent portion of the electrode winding body. Production method. In step (6) to said doped, average pressure _{P A} applied to the main surface of the flat, square cans is 0.5 kgf / cm ² or more 20 kgf / cm ² or less, claim 1-5 one The method for manufacturing a sealed non-aqueous lithium storage element according to the above item. The method for manufacturing a sealed non-aqueous lithium storage element according to any one of claims 1 to 6 , wherein the doping step (6) is performed in a dry environment.

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