JP6754227B2 - Lithium-ion battery manufacturing method - Google Patents

Description

The present invention relates to a method for producing a lithium ion battery.

Lithium-ion (secondary) batteries have been widely used in various applications in recent years as high-capacity, compact and lightweight secondary batteries. In particular, as an example of a simple manufacturing method for a thin, lightweight, high-energy density lithium-ion battery with a simplified exterior structure, a positive electrode active material layer and a negative electrode active material are formed on the inner surfaces of a sheet-shaped positive electrode and negative electrode current collector, respectively. A method has been proposed in which a material layer is formed, a separator layer is interposed between the positive electrode active material layer and the negative electrode active material layer, and peripheral portions of the positive electrode and negative electrode current collectors are joined via an insulating material (. See Patent Document 1).

JP-A-2002-260739

However, in the conventional method for manufacturing a lithium ion battery described above, a positive electrode active material layer and a negative electrode active material layer are formed on a sheet-shaped positive electrode current collector and a negative electrode current collector, respectively, and such a step is a positive electrode collection. A slurry obtained by dissolving and dispersing positive electrode active material particles and a binder in a solvent and a slurry obtained by dissolving and dispersing negative electrode active material particles and a binder in a solvent on an electric body and a negative electrode current collector. After each is applied to form a coating film, the coating film is dried, sintered, etc. to bind the active material particles to form the positive electrode active material layer and the negative electrode active material layer. Therefore, the positive electrode active material layer and the negative electrode are formed. It took time and effort to form the active material layer.

The present invention has been made in view of the above-mentioned problems, and provides a method for manufacturing a lithium ion battery , which has a simplified exterior structure and can simplify the manufacturing process of a thin and lightweight lithium ion battery. , Is one of the purposes.

In the present invention, a positive electrode composition containing a positive electrode active material and an electrolytic solution and a negative electrode composition containing a negative electrode active material and an electrolytic solution face each other via a separator, and a pair of collections that also serve as a battery exterior. A method for manufacturing a lithium ion battery in which a positive electrode composition, a negative electrode composition, and a separator are sandwiched between electric bodies, a step of forming a current collector having recesses formed at least in a part thereof , and current collection. The step of arranging the positive electrode composition or the negative electrode composition in the recess formed in the body is provided, and the step of arranging the positive electrode composition or the negative electrode composition in the recess is a step of arranging the positive electrode composition or the negative electrode composition in the recess. At least one of the above-mentioned problems is solved by a method for manufacturing a lithium ion battery including a step of filling a positive electrode slurry containing particles and an electrolytic solution or a negative electrode slurry containing negative electrode active material particles and an electrolytic solution. ing.

According to the present invention, it is possible to provide a method for manufacturing a lithium ion battery , which has a simplified exterior structure and can simplify the manufacturing process of a thin and lightweight lithium ion battery.

It is a schematic diagram which shows the manufacturing method of the lithium ion battery which is 1st Embodiment of this invention. It is a top view which shows the current collector applied to the manufacturing method of the lithium ion battery of 1st Embodiment. It is a perspective view which shows the lithium ion battery manufactured by the manufacturing method of the lithium ion battery of 1st Embodiment.

(First Embodiment)
A lithium ion battery and a method for manufacturing the lithium ion battery according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic view showing a method for manufacturing a lithium ion battery according to the first embodiment of the present invention, and FIG. 2 is a plan view showing a current collector applied to the method for manufacturing a lithium ion battery according to the first embodiment. FIG. 3 is a perspective view showing a lithium ion battery manufactured by the method for manufacturing a lithium ion battery of the first embodiment.

Prior to explaining the method for manufacturing the lithium ion battery of the present embodiment, the lithium ion battery manufactured by the method for manufacturing the lithium ion battery of the present embodiment will be described with reference to FIG.

As shown in FIG. 3, the lithium ion battery L of the present embodiment includes a positive electrode current collector 7 and a negative electrode current collector 8. A part of the positive electrode current collector 7 and the negative electrode current collector 8 is formed into convex portions 7a and 8a having substantially the same shape with a substantially rectangular cross section, and the insides of the convex portions 7a and 8a are concave portions. The peripheral edges 7b and 8b of the recess are formed by being sealed by a seal member (not shown) in FIG.

Between the positive electrode current collector 7 and the negative electrode current collector 8, the outer peripheral portion of the flat plate-shaped separator (not shown) in FIG. 3 is the peripheral edge portion 7b of the positive electrode current collector 7 and the peripheral edge portion 8b of the negative electrode current collector 8. It is fixed between the two pole current collectors by being fixed between and. In the recesses formed in the positive electrode current collector 7 and the negative electrode current collector 8, a positive electrode composition containing a positive electrode active material and an electrolytic solution and a negative electrode composition containing a negative electrode active material and an electrolytic solution are contained. Each is arranged, whereby the lithium ion battery L of the present embodiment is formed.

Here, in the present specification, "the electrode composition is arranged" means a state in which the electrode composition corresponding to the recesses formed in the positive electrode current collector 7 and the negative electrode current collector 8 is housed. However, preferably, it means that the positive electrode composition and the negative electrode composition fill the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, respectively. More preferably, the arranged positive electrode composition is in a state in which the positive electrode active material particles and the electrolytic solution are mixed, and the negative electrode electrode composition is in a state in which the negative electrode active material particles and the electrolytic solution are mixed.

In the present invention, in order to make the positive electrode composition and the negative electrode composition arranged in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, powdery positive electrode active material particles and negative electrode active material particles May be directly placed in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, and includes a positive electrode slurry containing the positive electrode active material particles and the electrolytic solution, and negative electrode active material particles and the electrolytic solution. The negative electrode slurry made of the above may be put into the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, respectively. When powdered positive electrode active material particles and negative electrode active material particles are directly placed in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, the positive electrode current collector 7 and the negative electrode current collector are then charged by adding an electrolytic solution. The positive electrode composition and the negative electrode composition are arranged in the recesses of the body 8.

According to the above-mentioned production method, the slurry obtained by dissolving and dispersing the positive electrode active material particles and the binder in a solvent on the positive electrode current collector and the negative electrode current collector, and the negative electrode active material particles and the binder are used as a solvent. A positive electrode composition or a negative electrode is formed in a recess formed in a current collector without drying, sintering, or the like after applying the slurry obtained by dissolving and dispersing in Since the lithium ion battery can be obtained by directly arranging the composition, it is possible to obtain a lithium ion battery capable of simplifying the manufacturing process.

When the positive electrode active material particles or the positive electrode slurry and the negative electrode active material particles or the negative electrode slurry are put into the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, respectively, the positive electrode current collector 7 and the negative electrode current collector 8 are used. It is preferable to give vibration and impact. It is preferable that the positive electrode active material particles or the positive electrode slurry and the negative electrode active material particles or the negative electrode slurry can be uniformly filled in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8 by applying vibration or impact.

Further, the positive electrode slurry or the negative electrode slurry (hereinafter referred to as an electrode slurry) in which the positive electrode active material particles or the negative electrode active material particles and the electrolytic solution are mixed is usually fluid in which the active material particles are uniformly suspended in the liquid. However, depending on the weight ratio of the positive electrode active material particles or the negative electrode active material particles to the electrolytic solution, the gel-like or active material particles may be in a state close to agglomerates or powders formed by absorbing the liquid. Sometimes.

Then, after the positive electrode composition and the negative electrode composition are arranged in the recesses of the positive electrode current collector 7 and the negative electrode current collector 8, the recesses of the positive electrode current collector 7 and the negative electrode current collector 8 are degassed under reduced pressure. At the same time, the positive electrode current collector 7 and the negative electrode current collector 8 are bonded and sealed using a seal member or the like arranged between the peripheral edge portion 7b of the positive electrode current collector 7 and the peripheral edge portion 8b of the negative electrode current collector 8. By stopping, an example of the lithium ion battery L of the present embodiment can be manufactured.

Since the lithium ion battery of the first embodiment shown in FIG. 3 has a structure in which the positive electrode current collector 7 and the negative electrode current collector 8 are exposed, the exposed positive electrode current collector 7 and the negative electrode current collector 8 are respectively exposed. It can be used as a power source by connecting a current extraction terminal (copper terminal, etc.) to. Further, the lithium ion battery according to the first embodiment shown in FIG. 3 can also be used by being stored in an outer shell container (laminate pack, battery can, etc.) having an insulating property. When stored in an insulating outer shell container for use, the current extraction terminal is provided so as to be connected to the outside of the outer shell container.

Examples of the positive electrode active material particles contained in the positive electrode active material composition include composite oxides of lithium and a transition metal (for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ and LiMn ₂ O ₄ ), and transition metal oxides (for example, MnO ₂ and MnO ₂ ). V ₂ O ₅ ), transition metal sulfides (eg MoS ₂ and TiS ₂ ) and conductive polymers (eg polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene and polycarbazole) and the like.

The negative electrode active material particles contained in the negative electrode active material composition include graphite, non-graphitizable carbon, amorphous carbon, and a fired polymer compound (for example, those obtained by firing and carbonizing a phenol resin, furan resin, etc.). , Coke (eg pitch coke, needle coke and petroleum coke), carbon fibers, conductive polymers (eg polyacetylene and polyquinolin), tin, silicon, and metal alloys (eg lithium-tin alloys, lithium-silicon alloys, etc.) Examples thereof include lithium-aluminum alloys and lithium-aluminum-manganese alloys) and composite oxides of lithium and transition metals (for example, Li ₄ Ti ₅ O1 ₂ etc.).

In the lithium ion battery of the present invention, the positive electrode active material particles or the negative electrode active material particles are coated positive electrode active material particles or coated negative electrode active material particles having a coating layer containing a coating resin composition on at least a part of the surface thereof. It is preferable to have.

When the surface of the active material particles has a coating layer, the volume change of the electrode that occurs during charging and discharging is alleviated, and the expansion of the electrode can be suppressed.
Examples of the coating resin composition contained in the coating layer include vinyl resin, urethane resin, polyester resin, polyamide resin, epoxy resin, polyimide resin, silicone resin, phenol resin, melamine resin, urea resin, aniline resin, and ionomer resin. Examples include polycarbonate. Among these, vinyl resin, urethane resin, polyester resin or polyamide resin is preferable, and among them, vinyl resin is more preferable, and the liquid absorption rate when immersed in the electrolytic solution is 10% or more, and in a saturated liquid absorption state. A vinyl resin (A) having a tensile elongation at break of 10% or more is more preferable.

The liquid absorption rate when immersed in the electrolytic solution is calculated by the following formula by measuring the weights of the vinyl resin before and after the immersion in the electrolytic solution, respectively.
Liquid absorption rate (%) = [(Weight of vinyl resin after immersion in electrolyte solution-Weight of vinyl resin before immersion in electrolyte solution) / Weight of vinyl resin before immersion in electrolyte solution] × 100
As the electrolytic solution for determining the liquid absorption rate, 1 mol / L of LiPF ₆ as an electrolyte was added to a mixed solvent in which ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in a volume ratio of EC: DEC = 3: 7. Use a non-aqueous electrolyte solution dissolved to a concentration.
Immersion in the electrolytic solution for determining the liquid absorption rate is performed at 50 ° C. for 3 days. By immersing at 50 ° C. for 3 days, the resin is in a saturated liquid absorbing state. The saturated liquid absorbing state means a state in which the weight of the vinyl resin does not increase even if it is further immersed in the electrolytic solution.
The electrolytic solution used in manufacturing the lithium ion battery is not limited to the above electrolytic solution, and other electrolytic solutions may be used.

When the liquid absorption rate is 10% or more, the vinyl resin absorbs a sufficient amount of the electrolytic solution, so that lithium ions can easily permeate the vinyl resin, so that between the active material and the electrolytic solution. It is preferable because the movement of lithium ions is good. The liquid absorption rate is preferably 20% or more, and more preferably 30% or more.
The preferred upper limit of the liquid absorption rate is 400%, and the more preferable upper limit is 300%.

For the tensile elongation at break in the saturated liquid absorption state, the vinyl resin is punched out in a dumbbell shape and immersed in the electrolytic solution at 50 ° C. for 3 days in the same manner as the above measurement of the liquid absorption rate to bring the vinyl resin into the saturated liquid absorption state. , ASTM D683 (test piece shape TypeII) can be measured. The tensile elongation at break is a value calculated by the following formula as the elongation at break until the test piece breaks in the tensile test.
Tensile fracture elongation (%) = [(Test piece length at break-Test piece length before test) / Test piece length before test] x 100

When the tensile elongation at break of the vinyl resin in the saturated liquid absorbing state is 10% or more, the vinyl resin has appropriate flexibility so that the coating layer can follow the volume change of the active material during charging and discharging. It is preferable because it has good durability.
The tensile elongation at break is preferably 20% or more, and more preferably 30% or more.
Further, the preferable upper limit value of the tensile elongation at break is 400%, and the more preferable upper limit value is 300%.

The vinyl resin (A) is a resin containing a polymer (A1) containing the vinyl monomer (a) as an essential constituent monomer, and the polymer (A1) is a resin from the viewpoint of the liquid absorption rate of the electrolytic solution and the like. , The vinyl monomer (a) preferably contains a vinyl monomer (a1) having a carboxyl group or an acid anhydride group, or a vinyl monomer (a2) represented by the following general formula (1).
CH ₂ = C (R ¹ ) COOR ² (1)
[In the formula (1), R ¹ is a hydrogen atom or a methyl group, and R ² is a straight chain having 4 to 12 carbon atoms or a branched alkyl group having 4 to 36 carbon atoms. ]

Examples of the vinyl monomer (a1) having a carboxyl group or an acid anhydride group include monocarboxylic acids having 3 to 15 carbon atoms such as (meth) acrylic acid (a11), crotonic acid, and itaconic acid; (anhydrous) maleic acid and fumal. Dicarboxylic acids with 4 to 24 carbon atoms such as acids, (maleic) itaconic acid, citraconic acid, and mesaconic acid; trivalent to tetravalent or higher valent polycarboxylic acids with 6 to 24 carbon atoms such as aconitic acid, etc. Can be mentioned. Among these, (meth) acrylic acid (a11) is preferable, and methacrylic acid is more preferable.

In the vinyl monomer (a2) represented by the general formula (1), R ¹ represents a hydrogen atom or a methyl group. R ¹ is preferably a methyl group.
R ² is a linear or branched alkyl group having 4 to 12 carbon atoms, or is preferably a branched alkyl group having 13 to 36 carbon atoms and each ester the following compounds.

(A21) Ester compound in which R ² is a linear or branched alkyl group having 4 to 12 carbon atoms Examples of the linear alkyl group having 4 to 12 carbon atoms include a butyl group, a pentyl group, a hexyl group, a heptyl group and an octyl group. Examples include a nonyl group, a decyl group, an undecyl group, and a dodecyl group.
The branched alkyl group having 4 to 12 carbon atoms includes a 1-methylpropyl group (sec-butyl group), a 2-methylpropyl group, a 1,1-dimethylethyl group (tert-butyl group), a 1-methylbutyl group, and 1 , 1-dimethylpropyl group, 1,2-dimethylpropyl group, 2,2-dimethylpropyl group (neopentyl group), 1-methylpentyl group, 2-methylpentyl group, 3-methylpentyl group, 4-methylpentyl group , 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group , 1-methylhexyl group, 2-methylhexyl group, 2-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 1-ethylpentyl group, 2-ethylpentyl group, 3-ethylpentyl group, 1 , 1-dimethylpentyl group, 1,2-dimethylpentyl group, 1,3-dimethylpentyl group, 2,2-dimethylpentyl group, 2,3-dimethylpentyl group, 2-ethylpentyl group, 1-methylheptyl group , 2-Methylheptyl group, 3-Methylheptyl group, 4-Methylheptyl group, 5-Methylheptyl group, 6-Methylheptyl group, 1,1-dimethylhexyl group, 1,2-dimethylhexyl group, 1,3 -Dimethylhexyl group, 1,4-dimethylhexyl group, 1,5-dimethylhexyl group, 1-ethylhexyl group, 2-ethylhexyl group, 1-methyloctyl group, 2-methyloctyl group, 3-methyloctyl group, 4 -Methyloctyl group, 5-methyloctyl group, 6-methyloctyl group, 7-methyloctyl group, 1,1-dimethylheptyl group, 1,2-dimethylheptyl group, 1,3-dimethylheptyl group, 1,4 -Dimethylheptyl group, 1,5-dimethylheptyl group, 1,6-dimethylheptyl group, 1-ethylheptyl group, 2-ethylheptyl group, 1-methylnonyl group, 2-methylnonyl group, 3-methylnonyl group, 4- Methylnonyl group, 5-methylnonyl group, 6-methylnonyl group, 7-methylnonyl group, 8-methylnonyl group, 1,1-dimethyloctyl group, 1,2-dimethyloctyl group, 1,3-dimethyloctyl group, 1,4 -Dimethyloctyl group, 1,5-dimethyloctyl group, 1,6-dimethyloctyl group, 1,7-dimethyloctyl group, 1-ethyloctyl group, 2-ethyloctyl group, 1-methyldecyl group, 2-methyldecyl group , 3-Mech Rudecyl group, 4-methyldecyl group, 5-methyldecyl group, 6-methyldecyl group, 7-methyldecyl group, 8-methyldecyl group, 9-methyldecyl group, 1,1-dimethylnonyl group, 1,2-dimethylnonyl group, 1 , 3-Dimethylnonyl group, 1,4-dimethylnonyl group, 1,5-dimethylnonyl group, 1,6-dimethylnonyl group, 1,7-dimethylnonyl group, 1,8-dimethylnonyl group, 1-ethylnonyl Group, 2-ethylnonyl group, 1-methylundecyl group, 2-methylundesyl group, 3-methylundesyl group, 4-methylundesyl group, 5-methylundesyl group, 6-methylundesyl group, 7 -Methylundecyl group, 8-methylundesyl group, 9-methylundesyl group, 10-methylundesyl group, 1,1-dimethyldecyl group, 1,2-dimethyldecyl group, 1,3-dimethyldecyl group , 1,4-dimethyldecyl group, 1,5-dimethyldecyl group, 1,6-dimethyldecyl group, 1,7-dimethyldecyl group, 1,8-dimethyldecyl group, 1,9-dimethyldecyl group, 1 -Ethyldecyl group, 2-ethyldecyl group and the like can be mentioned.

(A22) An ester compound in which R ² is a branched alkyl group having 13 to 36 carbon atoms. Examples of the branched alkyl group having 13 to 36 carbon atoms include a 1-alkylalkyl group [1-methyldodecyl group, 1-butyleicosyl group, 1-hexyl octadecyl group, 1-octyl hexadecyl group, 1-decyl tetradecyl group, 1-undecyl tridecyl group, etc.], 2-alkylalkyl group [2-methyldodecyl group, 2-hexyl octadecyl group, 2- Octyl hexadecyl group, 2-decyl tetradecyl group, 2-undecyl tridecyl group, 2-dodecyl hexadecyl group, 2-tridecyl pentadecyl group, 2-decyl octadecyl group, 2-tetradecyl octadecyl group, 2- Hexadecyl octadecyl group, 2-tetradecyl eicosyl group, 2-hexadecyl eicosyl group, etc.] 3-34-alkylalkyl groups (3-alkylalkyl groups, 4-alkylalkyl groups, 5-alkylalkyl groups, 32 -Alkylalkyl groups, 33-alkylalkyl groups, 34-alkylalkyl groups, etc.), as well as propylene oligomers (7-11 mer), ethylene / propylene (molar ratio 16 / 1-1 / 11) oligomers, isobutylene oligomers ( One or more branched alkyl groups such as residues obtained by removing hydroxyl groups from oxoalcohols obtained from 7 to 8 mer) and α-olefin (5 to 20 carbon atoms) oligomers (4 to 8 mer). Examples thereof include mixed alkyl groups contained therein.

The polymer (A1) preferably further contains an ester compound (a3) of a monohydric aliphatic alcohol having 1 to 3 carbon atoms and (meth) acrylic acid.
Examples of the monohydric aliphatic alcohol having 1 to 3 carbon atoms constituting the ester compound (a3) include methanol, ethanol, 1-propanol and 2-propanol.

The content of the ester compound (a3) is preferably 10 to 60% by weight, preferably 15 to 55% by weight, based on the total weight of the polymer (A1) from the viewpoint of suppressing volume change of the active material. More preferably, it is more preferably 20 to 50% by weight.

Further, the polymer (A1) preferably further contains a salt (a4) of an anionic monomer having a polymerizable unsaturated double bond and an anionic group.
Examples of the structure having a polymerizable unsaturated double bond include a vinyl group, an allyl group, a styrenyl group and a (meth) acryloyl group.
Examples of the anionic group include a sulfonic acid group and a carboxyl group.
Anionic monomers having a polymerizable unsaturated double bond and an anionic group are compounds obtained by combining these, and examples thereof include vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid and (meth) acrylic acid. Be done.
The (meth) acryloyl group means an acryloyl group and / or a methacryloyl group.
Examples of the cation constituting the salt (a4) of the anionic monomer include lithium ion, sodium ion, potassium ion, ammonium ion and the like.

The content of the salt (a4) of the anionic monomer is preferably 0.1 to 15% by weight, preferably 1 to 15% by weight, based on the total weight of the polymer compounds from the viewpoint of internal resistance and the like. More preferably, it is more preferably 2 to 10% by weight.

The polymer (A1) contains (meth) acrylic acid (a11), a vinyl monomer (a2) represented by the above general formula (1), a monovalent aliphatic alcohol having 1 to 3 carbon atoms, and (meth) acrylic acid. A monomer composition containing the ester compound (a3) of the above and a salt (a4) of an anionic monomer having a polymerizable unsaturated double bond and an anionic group is polymerized to form the vinyl monomer (a). The weight ratio of the weight ratio of a2) to the (meth) acrylic acid (a11) [the vinyl monomer (a2) / the (meth) acrylic acid (a11)] is preferably 10/90 to 90/10.
When the weight ratio of the vinyl monomer (a2) to the (meth) acrylic acid (a11) is 10/90 to 90/10, the polymer obtained by polymerizing the vinyl monomer (a2) has good adhesiveness to the active material and peels off. It becomes difficult.
The weight ratio is preferably 30/70 to 85/15, and more preferably 40/60 to 70/30.

The monomer constituting the polymer (A1) includes a vinyl monomer (a1) having a carboxyl group or an acid anhydride group, a vinyl monomer (a2), and a monovalent aliphatic alcohol having 1 to 3 carbon atoms. In addition to the ester compound (a3) with (meth) acrylic acid and the anionic monomer salt (a4) having a polymerizable unsaturated double bond and an anionic group, other radical polymerizations containing no active hydrogen. The sex vinyl monomer (a5) [acrylamide, acrylonitrile, styrene, etc.] may be contained.

The preferred lower limit of the number average molecular weight of the polymer (A1) is 3,000, more preferably 50,000, still more preferably 100,000, particularly preferably 200,000, and the preferred upper limit is 2,000,000. It is preferably 1,500,000, more preferably 1,000,000, and particularly preferably 800,000.

The number average molecular weight of the polymer (A1) can be determined by gel permeation chromatography (hereinafter abbreviated as GPC) measurement under the following conditions.
Equipment: Alliance GPC V2000 (manufactured by Waters)
Solvent: Ortodichlorobenzene Standard substance: Polystyrene detector: RI
Sample concentration: 3 mg / ml
Column stationary phase: PLgel 10 μm, two MIXED-B in series (manufactured by Polymer Laboratories)
Column temperature: 135 ° C

The glass transition point of the polymer (A1) [hereinafter abbreviated as Tg, measuring method: DSC (scanning differential thermal analysis) method] is preferably 80 to 200 ° C., more preferably 90, from the viewpoint of battery heat resistance. It is ~ 180 ° C., more preferably 100 to 150 ° C.

The polymer (A1) can be produced by a known polymerization method (bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc.).
In the polymerization, known polymerization initiators {azo-based initiators [2,2'-azobis (2-methylpropionitrile), 2,2'-azobis (2,4-dimethylvaleronitrile, etc.)], peroxides It may be carried out by using a system initiator (benzoyl peroxide, di-t-butyl peroxide, lauryl peroxide, etc.)}.

The polymer (A1) is a crosslinked polymer (A1) formed by cross-linking the polymer (A1) with a polyepoxy compound (a'1) (polyglucidyl ether or the like) and / or a polyol compound (a'2) (ethylene glycol, diethylene glycol or the like). It may be a polymer.

Examples of the method of cross-linking the polymer (A1) using the cross-linking agent (A') include a method of coating the active material particles with the polymer (A1) and then cross-linking the active material particles and the polymer (A1). By mixing a resin solution containing the above material and removing the solvent, a coating active material in which the active material particles are coated with the polymer (A1) is produced, and then the solution containing the cross-linking agent (A') is mixed with the coating active material. Then, a method of causing a cross-linking reaction with solvent removal and cross-linking the polymer (A1) with a cross-linking agent (A') is carried out on the surface of the active material particles.

The coating layer may further contain a conductive auxiliary agent, and the conductive auxiliary agent is selected from materials having conductivity.

Specific examples of the conductive material include metals [aluminum, stainless steel (SUS), silver, gold, copper and titanium], carbon [graphite, carbon black (acetylene black, ketjen black, furnace black, channel). Black, thermal lamp black, etc.), carbon nanotubes (single-walled, multilayer, and mixtures thereof, etc.), etc.], and mixtures thereof, etc., but are not limited thereto.

These conductive aids may be used alone or in combination of two or more. Moreover, these alloys or metal oxides may be used. From the viewpoint of electrical stability, aluminum, stainless steel, carbon, silver, gold, copper, titanium and mixtures thereof are preferable, silver, gold, aluminum, stainless steel and carbon are more preferable, and carbon is more preferable. is there. Further, these conductive auxiliaries may be those obtained by coating a conductive material (a metal one among the above-mentioned conductive auxiliary materials) around a particle-based ceramic material or a resin material by plating or the like.

It is also possible to use conductive fibers as the conductive auxiliary agent. As the conductive fiber, carbon fiber such as PAN-based carbon fiber and pitch-based carbon fiber, conductive fiber obtained by uniformly dispersing a metal having good conductivity or graphite in synthetic fiber, and a metal such as stainless steel are used. Examples thereof include fibrous metal fibers, conductive fibers in which the surface of organic fibers is coated with metal, and conductive fibers in which the surface of organic fibers is coated with a resin containing a conductive substance. Among these conductive fibers, carbon fibers are preferable.

When the coating layer contained in the coating active material particles contains a conductive auxiliary agent, the weight of the coating layer is 3 to 3 to the total weight of the active material particles, the coating resin composition, and the conductive auxiliary agent used if necessary. It is preferably 25% by weight.

The coating active material particles can be produced by mixing the coating resin composition, the active material particles, and the conductive auxiliary agent used if necessary, and the coating resin composition and the conductive auxiliary agent used if necessary are mixed. It may be produced by mixing the obtained coating agent and the active material particles, or may be produced by simultaneously mixing the coating resin composition, the conductive additive used if necessary, and the active material particles. When the active material particles, the coating resin composition, and the conductive auxiliary agent used as necessary are mixed, the mixing order is not particularly limited, but after the active material particles and the coating resin composition are mixed, further It is preferable to add a conductive agent and further mix. The coating resin composition is preferably mixed as a solution containing the coating resin. For example, a resin containing the coating resin composition in a state where the active material particles are placed in a universal mixer and stirred at 30 to 500 rpm. The solution is added dropwise over 1 to 90 minutes, a conductive additive is further mixed, the temperature is raised to 50 to 200 ° C. with stirring, the pressure is reduced to 0.007 to 0.04 MPa, and then the solution is held for 10 to 150 minutes. Can be obtained by

As the electrolytic solution used for the electrode slurry in which the active material particles and the electrolytic solution are mixed, an electrolytic solution containing a known electrolyte and a non-aqueous solvent used for producing a lithium ion battery can be used.

As the electrolyte, those used in ordinary electrolytes can be used, for example, lithium salts of inorganic acids such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ and LiClO ₄ , LiN (CF ₃ SO ₂ ). _2. Lithium salts of organic acids such as LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ can be mentioned. Of these, LiPF ₆ is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

As the non-aqueous solvent, those used in ordinary electrolytic solutions can be used, and for example, a lactone compound, a cyclic or chain carbonate, a chain carboxylic acid ester, a cyclic or chain ether, a phosphoric acid ester, or a nitrile can be used. Compounds, amide compounds, sulfones, sulfolanes and the like and mixtures thereof can be used.

One type of non-aqueous solvent may be used alone, or two or more types may be used in combination.

Among the non-aqueous solvents, lactone compounds, cyclic carbonates, chain carbonates and phosphate esters are preferable from the viewpoint of battery output and charge / discharge cycle characteristics, and lactone compounds, cyclic carbonates and chains are more preferable. A carbonic acid ester is preferable, and a mixed solution of a cyclic carbonic acid ester and a chain carbonic acid ester is more preferable. Particularly preferred is propylene carbonate (PC) or a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC).

The electrode slurry is obtained by mixing and dispersing the active material particles in the electrolytic solution using a known dispersion device, and the weight of the active material particles contained in the electrode slurry is 10 to 60% by weight based on the weight of the electrolytic solution. It is preferable to prepare by dispersing and slurrying at the concentration of. When the above-mentioned coated active material particles are used as the active material particles contained in the electrode slurry, the weight of the active material particles contained in the electrode slurry is calculated using the weight of the coated active material particles.

At least one of the positive electrode composition and the negative electrode composition may further contain a conductive auxiliary agent in addition to the conductive auxiliary agent contained in the coating layer of the coating active material particles. Further, as the conductive auxiliary agent to be contained, the same conductive auxiliary agent as that contained in the above-mentioned coating agent can be used, and preferable ones include the conductive fibers exemplified as the above-mentioned conductive auxiliary agent, and carbon. Fiber is more preferred.
Further, the positive electrode composition and the negative electrode composition containing the conductive auxiliary agent can be formed by using an electrode slurry containing the conductive auxiliary agent obtained by mixing and dispersing the active material particles, the electrolytic solution and the conductive auxiliary agent. .. The positive electrode composition and the negative electrode composition arranged using the slurry containing the conductive auxiliary agent contain the conductive auxiliary agent between the active material particles, whereby the electron transfer in the electrode composition is improved.

In the present invention, it is preferable that the slurry used for forming the positive electrode composition and the negative electrode composition does not contain a binder (also referred to as a binder). The binder referred to here is a known binder (starch, polyvinylidene fluoride) used for the purpose of binding the active material particles to the current collector and binding the active material particles to each other in the electrode of the lithium ion battery. , Polyvinyl alcohol, carboxymethyl cellulose, polyvinylpyrrolidone, tetrafluoroethylene, styrene-butadiene rubber, polymer compounds such as polyethylene and polypropylene) and the like. In an electrode for a lithium ion battery using active material particles other than the coating active material particles, it is necessary to maintain the conductive path by fixing the active material particles in the electrode with a binder. However, when the coating active material particles are used, it is not necessary to add a binder because the conductive path can be maintained without fixing the active material particles in the electrode by the action of the coating resin. By not adding the binder, the active material particles are not immobilized in the electrode, so that the ability to alleviate the volume change of the active material particles is improved.

The separator 4 includes a microporous film film made of polyolefin such as polyethylene and polypropylene, a multilayer film of a porous polyethylene film and polypropylene, a non-woven fabric made of polyester fiber, aramid fiber, glass fiber and the like, and silica on their surfaces. Examples thereof include those to which ceramic fine particles such as alumina and titania are attached.

The positive electrode current collector 7 and the negative electrode current collector 8 are a pair of current collectors, and a resin current collector including a metal current collector and a conductive resin layer can be used. As the metal current collector, a known metal current collector can be used. For example, metal collectors are selected from the group consisting of copper, aluminum, titanium, nickel, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, antimony, and alloys containing one or more of these, as well as stainless alloys. It is preferable that the current collector is from one or more types. The metal collector may be formed from a thin plate or a metal foil, or a metal layer made of the above metal may be formed on the surface of another film-like base material by a method such as sputtering, electrodeposition, or coating. In this embodiment, a resin current collector is preferably applied. By using a resin current collector, it becomes easy for the current collector to also serve as a battery exterior, which is preferable.

A resin current collector including a conductive resin layer is a current collector including a conductive layer made of a conductive polymer material, and the conductive resin layer is known as a conductive polymer material. It can be obtained by molding into a sheet by the method of. In the lithium ion battery of the present invention, another conductive layer (metal layer or other conductive resin) is added to the conductive resin layer obtained by molding a conductive polymer material into a sheet by a known method. Layers) may be laminated.
The conductive polymer material constituting the conductive resin layer contained in the resin current collector may be a conductive polymer, or a polymer material in which conductivity is imparted to a non-conductive polymer. It may be.

Among the polymer materials constituting the conductive resin layer, examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, and polyoxadiazole.

Examples of the non-conductive polymer material include aliphatic polyolefins [polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), and polyisobutylene. , Polybutadiene and polymethylpentene (PMP) and their copolymers, etc.], Alicyclic polyolefin [Polycycloolefin (PCO), etc.], Polyester resin [Polyethylene terephthalate (PET), etc.], Polyethernitrile (PEN), Synthetic rubber [styrene butadiene rubber (SBR), etc.], acrylic resin [polyacrylonitrile (PAN), polymethylacrylate (PMA), polymethylmethacrylate (PMMA), etc.], polyvinylidene fluoride (PVdF), epoxy resin, silicone resin and Examples thereof include a mixture thereof.

As the polymer constituting the conductive resin layer, it is preferable to use polyethylene, polypropylene, or a modified polyolefin in which a polar functional group is introduced into a copolymer thereof. When the modified polyolefin is contained, the polar functional group interacts with the conductive filler to function as a dispersant for dispersing the conductive filler in the conductive resin layer, which is preferable. When the modified polyolefin is contained, the content of the modified polyolefin is preferably 1 to 25% by mass with respect to the total mass of the polymer material and the conductive filler.

Modified polyolefin resins in which polar functional groups are introduced into polyethylene, polypropylene, or copolymers thereof are commercially available as dispersants for resins, resin modifiers, compatibilizers, etc., and are manufactured by Sanyo Kasei Co., Ltd., Yumex Series and Mitsui. It is available as an Admer series manufactured by Kagaku Co., Ltd.

From the viewpoint of electrical stability, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferable, and polyethylene (PE), polypropylene (PP) and polymethylpentene are more preferable. (PMP).

Further, the resin current collector is a conductive filler for the purpose of improving the conductivity of the resin current collector containing the conductive polymer material or for the purpose of imparting conductivity to a non-conductive polymer. It is preferable to include. The conductive filler is selected from materials having conductivity. Preferably, from the viewpoint of suppressing ion permeation in the current collector, it is preferable to use a material having no conductivity with respect to ions used as a charge transfer medium. Specific examples thereof include, but are not limited to, carbon materials, aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, antimonide, titanium, and nickel. These conductive fillers may be used alone or in combination of two or more. Further, these alloy materials such as stainless steel (SUS) may be used. From the viewpoint of corrosion resistance, aluminum, stainless steel, carbon material, nickel, and more preferably carbon material are preferable. Further, these conductive fillers may be a particle-based ceramic material or a resin material coated with the metal shown above by plating or the like.

The resin current collector can be obtained by a known method described in Japanese Patent Application Laid-Open No. 2012-150905 and International Publication No. WO 2015/005116, and as a specific example, acetylene black is added to polypropylene as a conductive filler in 5- Examples thereof include those obtained by dispersing 20 parts and then rolling with a hot press. Further, the thickness thereof is not particularly limited, and the same as known ones or appropriately modified ones can be applied.

The material constituting the seal member is not particularly limited as long as it has adhesiveness to the current collectors 7 and 8 and is durable against the electrolytic solution, but is not particularly limited, but is a polymer material, particularly a thermosetting resin. Is preferable. Specific examples thereof include epoxy-based resins, polyolefin-based resins, polyurethane-based resins, and polyvinylidene fluoride resins, and epoxy-based resins are preferable because they have high durability and are easy to handle.
As the sealing member, a double-sided tape-shaped sealing member (such as a sealing member formed by applying the above-mentioned thermosetting resin or the like on both sides of a flat base material) can be used, and a three-layer structure sealing film can be used. Known materials such as (a film in which a modified polypropylene film is laminated on top of a polyethylene naphthalate film, etc.) can be used. The seal film can be sealed by heat-pressing using a known sealing device such as an impulse sealer.

Next, a method for manufacturing the lithium ion battery of the present embodiment will be described with reference to FIGS. 1 and 2.

First, as shown in FIGS. 1A and 2, a flat plate-shaped positive electrode current collector 7 and a negative electrode current collector in which a plurality of recesses 7c and 8c having substantially rectangular shapes in both a plan view and a cross-sectional view are formed in a grid shape. The electric body 8 is formed. The method of forming the recesses 7c and 8c in the positive electrode current collector 7 and the negative electrode current collector 8 is not limited, and the method of forming the recesses 7c and 8c may be appropriately selected depending on the material of the current collectors 7 and 8. If the positive electrode current collector 7 and the negative electrode current collector 8 are resin current collectors, a method of molding the sheet-shaped resin current collector using a molding die in which the recesses 7c and 8c are heated to the softening point or higher, and An example is a method in which a melt of a conductive polymer material is placed in a mold having a predetermined shape and integrally molded. If the positive electrode and negative electrode current collectors 7 and 8 are metal current collectors, a flat plate shape is used. Examples thereof include a method in which a molding die is pressed into the positive electrode current collector 7 and the negative electrode current collector 8 to form recesses 7c and 8c.

In FIG. 1A, the seal members 9 are arranged on the four peripheral edges 7b and 8b of the recesses 7c and 8c formed in the positive electrode current collector 7 and the negative electrode current collector 8, but the seal members 9 are arranged. As long as it is before the step of arranging the separator 4, it may be performed before or after the formation of the concave portion. Although only the positive electrode current collector 7 is shown as a representative in FIGS. 1 (a) to 1 (b) and FIG. 2, the same steps are performed for both the positive electrode current collector and the negative electrode current collectors 7 and 8. Will be.

Next, as shown in FIG. 1B, the positive electrode active material 5 which is the positive electrode composition and the negative electrode active material 6 which is the negative electrode composition are formed in the recesses 7c and 8c of the positive electrode current collector 7 and the negative electrode current collector 8. Are placed respectively. The method of arranging the positive electrode active material 5 and the negative electrode active material 6 in the recesses 7c and 8c of the positive electrode current collector 7 and the negative electrode current collector 8 is not limited, and as an example, from the tank in which the positive electrode slurry and the negative electrode slurry are stored, respectively. A method of filling the recesses 7c and 8c with the positive electrode slurry and the negative electrode slurry via the nozzle 20, and a method of filling the recesses 7c and 8c of the positive electrode current collector 7 and the negative electrode current collector 8 with the positive electrode slurry and the negative electrode slurry by an inkjet device. Well-known methods such as, etc. are preferably applied.

The amounts of the positive electrode active material 5 and the negative electrode active material 6 arranged in the recesses 7c and 8c of the positive electrode current collector 7 and the negative electrode current collector 7 are such that at least the recesses 7c and 8c are the positive electrode active material 5 and the negative electrode active material. The amount is filled with the substance 6, and preferably, the positive electrode active material 5 and the negative electrode active material 6 are slightly raised from the peripheral portions 7b and 8b of the recesses 7c and 8c of the positive electrode current collector 7 and the negative electrode current collector 7. Is preferably the amount of.

Next, as shown in FIG. 1C, the flat plate-shaped separator 4 was arranged in the recess by arranging the flat plate-shaped separator 4 on the upper surface of any one of the positive electrode current collector 7 and the negative electrode current collector 8 in the drawing. The upper surface of either the positive electrode active material 5 or the negative electrode active material 6 is covered with the separator 4. At this time, when the positive electrode active material 5 or the negative electrode active material 6 is filled in the concave portion 7c or 8c so as to rise from the peripheral portion 7b or 8b of the concave portion 7c or 8c as described above, the upper surface of the separator 4 in the drawing is covered with the roller 10. It is preferable to level the positive electrode or negative electrode active materials 5 and 6 by arranging the separator 4 while pressing the separator.

Next, as shown in FIG. 1D, one of the positive electrode and negative electrode current collectors 7 and 8 is turned upside down, and then the positive electrode and negative electrode current collectors 7 and 8 are relative to the recesses 7c and 8c, respectively. Place it so that it faces.

Next, as shown in FIG. 1 (e), of the sealing members 9 arranged in the four peripheral edges 7b and 8b of the recesses 7c and 8c, the three peripheral edges 7b excluding any of the peripheral edges 7b and 8b, By heating 8b or the like, peripheral portions 7b and 8b except for a part are sealed.

In this state, the insides of the recesses 7c and 8c are depressurized and degassed, and the remaining peripheral edges 7b and 8b are further heated to degas the insides of the recesses 7c and 8c as shown in FIG. 1 (f). Seal in this state.

Then, as shown in FIGS. 1 (g) and 1 (h), the peripheral portions 7b and 8b of the recesses in which the recesses 7c and 8c are sealed are cut with a cutter 21 or the like to form lithium as shown in FIG. An ion battery L can be obtained.

According to the method for manufacturing a lithium ion battery of the present embodiment, the positive electrode and negative electrode active materials 5 and 6 are arranged in the recesses 7c and 8c of the positive electrode and negative electrode current collectors 7 and 8, and the peripheral portions 7b and 8b are formed. Since the lithium ion battery L can be manufactured by sealing with the sealing member 9 and then cutting the peripheral portions 7b and 8b, the sheet-shaped positive electrode current collector and the negative electrode current collector contain a slurry containing a positive electrode active material and a negative electrode active material. A lithium ion battery and a manufacturing method thereof that can simplify the manufacturing process without the need to apply a slurry containing a substance to form a coating film and further perform steps such as drying and sintering the coating film. Can be provided.

Further, in the lithium ion battery of the present embodiment, the positive electrode current collector 7 and the negative electrode current collector 8 can also serve as the battery exterior body, and the recesses 7c formed in the positive electrode current collector 7 and the negative electrode current collector 8 are formed. , 8c are obtained by directly inserting the electrode slurry or the like constituting the positive electrode active material 5 which is the positive electrode composition and the negative electrode active material 6 which is the negative electrode composition, respectively, and thus the shapes of the recesses 7c and 8c. Can be provided with a certain degree of shape freedom, and the inner surfaces of the positive electrode current collector 7 and the negative electrode current collector 8 can be efficiently filled with the positive electrode active material 5 and the negative electrode active material 6. Therefore, according to the present embodiment, a lithium ion battery capable of further increasing the degree of freedom in the shape of the outer shape of the battery and more effectively utilizing the storage space inside the positive electrode current collector 7 and the negative electrode current collector 8 and the like. The manufacturing method can be realized.

Further, the lithium ion battery of the present embodiment has an advantage that even if the positive electrode current collector 7 and the negative electrode current collector 8 are deformed during use, there is very little possibility that a problem will occur in the characteristics of the lithium ion battery L. There is. That is, in the lithium ion battery L of the present embodiment, the positive electrode active material particles and the negative electrode active material particles are fixed by drying the slurry containing the binder as in the conventional lithium ion battery, and the positive electrode active material layer and the negative electrode active material are fixed. Since no layer is formed, the positive electrode active material 5 and the negative electrode active material 6 can follow the deformation when the entire battery is deformed, so that the active material is peeled off from the current collector to form a lithium ion battery L. The possibility of causing a problem in the characteristics of the above is extremely small, and the lithium ion battery L can continue to supply the power supply voltage even after the positive electrode current collector 7 and the negative electrode current collector 8 are deformed.

Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the Examples as long as the gist of the present invention is not deviated. Unless otherwise specified, parts mean parts by weight and% means% by weight.

(Preparation of coating resin solution)
407.9 parts of N, N-dimethylformamide (hereinafter referred to as DMF) was charged in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, a dropping funnel and a nitrogen gas introduction tube, and the temperature was raised to 75 ° C. did. Next, a monomer compound solution containing 242.8 parts of methacrylic acid, 97.1 parts of methyl methacrylate, 242.8 parts of 2-ethylhexyl methacrylate, and 116.5 parts of DMF, and 2,2'-azobis (2,4-dimethyl). 1.7 parts of valeronitrile) and 4.7 parts of 2,2'-azobis (2-methylbutyronitrile) dissolved in 58.3 parts of DMF with an initiator solution while blowing nitrogen into a four-necked flask. Under stirring, radical polymerization was carried out by continuously dropping with a dropping funnel over 2 hours. After completion of the dropping, the reaction was continued at 75 ° C. for 3 hours. Then, the temperature was raised to 80 ° C. and the reaction was continued for 3 hours to obtain a copolymer solution having a resin concentration of 50%. 789.8 parts of DMF was added thereto to obtain a coating resin solution having a resin solid content concentration of 30% by weight.

(Preparation of coated positive electrode active material particles)
LiCoO ₂ powder [Celseed C-8G manufactured by Nippon Kagaku Kogyo Co., Ltd.] was placed in a universal mixer and stirred at room temperature at 150 rpm, and a coating resin solution (resin solid content concentration: 30% by weight) was added to the resin. The mixture was added dropwise over 60 minutes so that the solid content was 2 parts by weight, and the mixture was further stirred for 30 minutes.

Next, 2 parts by weight of acetylene black [Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd.] was mixed in 3 portions in a stirred state, and the temperature was raised to 70 ° C. with stirring for 30 minutes to 100 mmHg. The pressure was reduced and the mixture was held for 30 minutes. The coated positive electrode active material particles were obtained by the above operation.

(Preparation of coated negative electrode active material particles)
Non-graphitizable carbon [Carbotron (registered trademark) PS (F) manufactured by Kureha Battery Materials Japan Co., Ltd.] 90 parts by weight is placed in a universal mixer and stirred at room temperature at 150 rpm, and is a coating resin. The solution (resin solid content concentration: 30% by weight) was added dropwise over 60 minutes so as to have a resin solid content of 5 parts by weight, and the mixture was further stirred for 30 minutes.

Next, 5 parts by weight of acetylene black [Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd.] was mixed in 3 portions with stirring, and the temperature was raised to 70 ° C. with stirring for 30 minutes. The pressure was reduced to 01 MPa and the mixture was held for 30 minutes. The coated negative electrode active material particles were obtained by the above operation.

(Preparation of electrolyte)
LiPF ₆ was dissolved in a mixed solvent (volume ratio 1: 1) of ethylene carbonate (EC) and diethyl carbonate (DEC) at a ratio of 1 mol / L to prepare an electrolytic solution for a lithium ion battery.

(Manufacturing of positive electrode slurry)
67 parts by weight of the coated positive electrode active material, 1 part by weight of carbon fiber [Donna Carbo Milled S-243 manufactured by Osaka Gas Chemical Co., Ltd .: average fiber length 500 μm, average fiber diameter 13 μm], and 32 parts by weight of the electrolytic solution were mixed. A positive electrode slurry was prepared.

(Manufacturing of negative electrode slurry)
A negative electrode slurry was prepared by mixing 52 parts by weight of the coated negative electrode active material particles, 1 part by weight of the same carbon fiber used in producing the positive electrode slurry, and 47 parts by weight of the electrolytic solution.

(Manufacturing of resin current collectors)
In a twin-screw extruder, polypropylene (PP) [trade name "SunAllomer (registered trademark) PL500A", manufactured by SunAllomer Ltd.] 75% by weight, acetylene black [trade name "Denka Black HS-100"] 20% by weight, and Resin modifier [trade name "Umex (registered trademark) 1001", manufactured by Sanyo Kasei Kogyo Co., Ltd.] 5% by weight is melt-kneaded at 180 ° C., 100 rpm, and a residence time of 10 minutes to obtain a material for a current collector. It was. The amount of each of the above components represents a mixing ratio, and the total of polypropylene, acetylene black and the resin modifier is 100% by weight. The obtained current collector material was rolled by a hot press to obtain a positive electrode current collector having a thickness of 100 μm.

(Molding of current collector)
As a mold for forming a current collector, a SUS mold having a convex portion having a width of 5 mm, a length of 30 mm, and a height of 1 mm and a SUS mold having a concave portion paired with the convex portion were prepared. The current collector for the positive electrode is sandwiched between the concave portion and the convex portion of the mold, allowed to stand in a high temperature bath at 80 ° C. for 6 hours to heat, then allowed to cool to room temperature, and the mold is removed. , A positive electrode current collector having a recess was obtained.

A commercially available electrolytic copper foil for batteries was used as the negative electrode current collector. A negative electrode current collector having a concave portion similar to that of the positive electrode current collector is formed by sandwiching the electrolytic copper foil between the concave portion and the convex portion of the above-mentioned current collector molding mold and pressurizing the electrolytic copper foil to form the electrolytic copper foil. Obtained.

(Example of lithium-ion battery)
The positive electrode slurry was injected into the concave portion of the positive electrode current collector having the concave portion formed to prepare a positive electrode having a positive electrode active material layer formed therein. Subsequently, the negative electrode slurry was injected into the concave portion of the negative electrode current collector having the concave portion formed therein to prepare a negative electrode having a negative electrode active material layer formed therein. A separator is placed on the surface of the positive electrode on the positive electrode active material layer side, and the negative electrode active material layer of the negative electrode is formed on the separator. The positive electrode current collector and the peripheral edges of the recesses of the negative electrode current collector are separated from each other. A single cell was manufactured by sealing between the peripheral edge portion and the separator, which were covered so as to overlap with each other, with a commercially available epoxy resin adhesive.
After connecting the lead part (current extraction terminal) connected to the outside of the container to each of the positive electrode and negative electrode current collectors of the single cell with a conductive adhesive, it was covered with an aluminum laminate and sealed under vacuum to manufacture a lithium ion battery. ..

In order to confirm the operation as a battery, a charge / discharge tester was connected to the lead part from the current collector and a charge / discharge test was performed. It was confirmed that it can be charged and discharged and functions as a lithium-ion secondary battery.

L Lithium-ion battery 4 Separator 5 Positive electrode active material 6 Negative electrode active material 7 Positive electrode current collector 7a Convex part 7b Peripheral part 7c Concave part 8 Negative electrode current collector 9 Sealing member

Claims (1)

The positive electrode composition containing the positive electrode active material and the electrolytic solution and the negative electrode composition containing the negative electrode active material and the electrolytic solution face each other via a separator, and the pair of current collectors also serving as a battery exterior is formed. A method for producing a lithium ion battery in which a positive electrode composition, the negative electrode composition, and the separator are sandwiched.
The step of forming the current collector having recesses formed at least in part thereof, and
A step of arranging the positive electrode composition or the negative electrode composition in the recess formed in the current collector.
With
In the step of arranging the positive electrode composition or the negative electrode composition in the recess, the positive electrode slurry or the negative electrode active material particles and the electrolytic solution containing the positive electrode active material particles and the electrolytic solution are placed in the recess. A method for manufacturing a lithium ion battery , which comprises a step of filling a negative electrode slurry containing the mixture.

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