JP3984008B2 - Method for manufacturing electrochemical device - Google Patents

Description

【００８８】
図１から明らかなように、実施例３、６以外は比較例１と同程度に良好な充放電特性を示した。実施例３、６は負極とポリオレフイン多孔膜との間に初期にポリマーを介在させていない電池である。このような電池の充放電特性が優れない原因としては、初期充電時のＳＥＩ（Solid Electrlyte Interphase ）形成前に電解液分解に起因する負極からのガス発生により電解質層と電極との密着が取れなくなり、その結果、電流分布が生じ充放電特性が落ちていると考えられる。これに対して負極とポリオレフイン多孔膜との間にポリマーを介在させた電池においては、上記ガス発生によっても、電解質層と電極との密着が保たれているため、優れた電池特性を維持していると考えられる。
【００８９】
また、表１から固体電解質層に電極とイオン伝導を所定湿度で遮断するセパレータを介在させることによって、高温加熱時や、過充電時の温度上昇に電極間のイオン伝導を無くし、また、このため過充電および内部ショートによる熱暴走を防ぐことが可能となり安全性の高い電池を提供できることがわかる。
【００９０】
以上より、固体状電解質の正極もしくは負極側にある温度以上で，電極と固体状電解質層とのイオン伝導を遮断する第二の層を介在させることにより、安全性の高い電池が供給できるが、特に負極とイオン伝導を遮断する第二の層との間にポリマーを存在させることによって電池特性の優れた電池を供給する事が可能である。
【００９１】
【発明の効果】
以上のように本発明によれば、十分な電解質の保持能力を有し、性能が優れた固体電解質を備え、製造が容易な電気化学デバイスの製造方法を提供することができる。
【００９２】
また、異常時においても自己安全性の機能に優れた電気化学デバイスの製造方法を提供することができる。
【図面の簡単な説明】
【図１】実施例、比較例の固体状電解質電池の充放電特性を示したグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a safety mechanism of an electrochemical device such as a lithium ion secondary battery and an electric double layer capacitor, and a manufacturing method thereof.
[0002]
[Prior art]
The development of portable devices in recent years has been remarkable, and as one of the driving forces, high energy batteries such as lithium ion secondary batteries contribute greatly. Currently, the market for lithium secondary ion batteries exceeds 300 billion a year, and the development of various portable devices can be predicted in the future.
[0003]
Such a lithium ion secondary battery is usually composed of a positive electrode, a liquid or solid electrolyte layer, and a negative electrode. This positive and negative electrode material is obtained by mixing a positive electrode active material and a negative electrode active material with a conductive additive and a binder and applying the mixture on a current collector. In such a lithium ion secondary battery, a high energy density of the battery is required as a development trend, and a thin battery is being developed as a countermeasure.
[0004]
As a technique for obtaining such a thin and light battery, there is a polymer battery in which the electrolyte portion that is a solution is made solid to reduce the thickness. This technique is already known, for example, USP 5418091. However, in recent years, the characteristics have been improved, and the battery characteristics have been improved to the extent that they cannot be compared with the original disclosure of the technique.
[0005]
There are various types of batteries using such a solid electrolyte, but they are roughly classified into the following three types.
[0006]
(1) Type using lithium ion conduction in polymer polymer as electrolyte
(2) Type using lithium ion conduction in plasticized polymer polymer as electrolyte
(3) Type using lithium ion conduction in polymer polymer plasticized with organic solvent and plasticizer as electrolyte
Among them, the battery component (3), the organic polymer component, and the electrolyte salt are mixed and gelled (solidified), and the battery is in practical use because it exhibits characteristics not inferior to those of the solution battery.
[0007]
As a typical example of a method for producing a gelled solid battery of the type (3), there is a battery manufacturing method described in, for example, USP5296318 and USP5418091. This produces a solid polyvinylidene fluoride-based solid electrolyte medium, which is joined to a positive electrode and a negative electrode, extracts a plasticizer from the entire battery body, and further injects an electrolyte solution to gel the whole. Is.
[0008]
By gelling the entire battery body in this way, there is no free electrolyte in the battery. Therefore, it may be said that it has a completely different form from the conventional solution battery. Furthermore, according to the contents disclosed in the patents USP5296318 and USP5418091, the battery characteristics are also excellent.
[0009]
However, when the solid gelled electrolyte is used, no problem occurs during normal use, but current breakage due to resin dissolution does not function sufficiently in an abnormal state, for example, overcharge and a heating test. This led to thermal runaway, which could lead to rupture and fire.
[0010]
In order to solve such a problem, for example, Japanese Patent Laid-Open No. 2001-43897 discusses a method of using a solid electrolyte and a shutdown separator in combination. However, in order to manufacture the battery described in this publication, a gel electrolyte must be formed by previously forming a gel electrolyte on the positive electrode and the negative electrode, and then facing the positive and negative electrodes across the separator. However, since the gel electrolyte must be handled in a dry atmosphere, the subsequent manufacturing process needs to be a dry atmosphere, which makes the manufacturing process very difficult.
[0011]
  In addition, in order to form a solid electrolyte, a matrix polymer is applied, dried, and an electrolyte is poured into this to form a solid electrolyte. At this time, the matrix polymer, separator, and electrode are sufficiently impregnated with the electrolyte. It is necessary to let For this reason, the matrix polymer must have sufficiently fine pores for holding the electrolyte, but the conventional manufacturing method does not provide sufficient openings, resulting in impregnation and holding of the electrolyte.Not enoughOnly a solid electrolyte was obtained.
[0012]
[Problems to be solved by the invention]
  Of the present inventionThe purpose is easy to manufactureIt is to provide a method for manufacturing an electrochemical device.
[0014]
[Means for Solving the Problems]
  That is, the above object is achieved by the following configuration of the present invention.
(1) Two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes, and between at least one of the two electrodes and the separator layer A method for producing an electrochemical device having the solid electrolyte layer,
  A matrix resin for forming the solid electrolyte,Only one side of the separator layer or at least one side of at least one of the two electrodesA method for producing an electrochemical device, which is applied to the substrate and dried to form a laminate, which is then poured into the matrix resin to form a solid electrolyte.
(2)Two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes, and at least one of the two electrodes and the solid layer between the separator layer A method for producing an electrochemical device having a state electrolyte layer,
The matrix resin that forms the solid electrolyte is applied to at least one of the two electrodes and the separator layer, dried to form a laminate, and then poured into the matrix resin to form a solid electrolyte. age,
The method for producing an electrochemical device, wherein the matrix resin is dissolved in at least two kinds of mixed solvents and dried under at least two kinds of different conditions.
(3)The method for producing an electrochemical device according to (2), wherein at least one of the two or more mixed solvents is insoluble in the matrix resin.
(4)The method for producing an electrochemical device according to any one of (1) to (3), wherein the separator is a shutdown separator that blocks ion conduction between the electrode and the solid electrolyte layer at a predetermined temperature or higher.
(5) The method for producing an electrochemical device according to any one of (1) to (4), wherein the matrix resin is a PVDF homopolymer.
(6) The method for producing an electrochemical device according to any one of (1) to (5), wherein the electrochemical device is a lithium secondary battery.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
  In one embodiment of the method for producing an electrochemical device of the present invention, two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes, and at least of the two electrodes. A method for producing an electrochemical device having the solid electrolyte layer between any one of the electrodes and the separator layer, wherein the matrix resin for forming the solid electrolyte comprises:Only one side of the separator layer or at least one side of at least one of the two electrodesThis is applied to the substrate and dried to obtain a laminate, and then poured into the matrix resin to obtain a solid electrolyte.
[0016]
  in this way,Only one side of the separator layer or at least one side of at least one of the two electrodesBy applying the matrix resin, drying and laminating, and finally injecting the solution into a gel electrolyte, only the injecting step and the sealing step may be in a dry atmosphere, and the manufacturing becomes extremely easy.
  In another embodiment of the method for producing an electrochemical device of the present invention, two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes. A method of manufacturing an electrochemical device having the solid electrolyte layer between any one of the electrodes and the separator layer, wherein the matrix resin forming the solid electrolyte includes at least two electrodes and a separator It is applied to any one surface of the layer, dried to form a laminate, and then poured into the matrix resin to form a solid electrolyte, and the matrix resin is dissolved in at least two kinds of mixed solvents, It is dried under at least two different conditions.
[0017]
Next, the method of the present invention will be described in detail.
[0018]
As a matrix resin constituting the solid electrolyte,
(1) Polyalkylene oxides such as polyethylene oxide and polypropylene oxide,
(2) a copolymer of ethylene oxide and acrylate,
(3) a copolymer of ethylene oxide and glycyl ether,
(4) a copolymer of ethylene oxide, glycyl ether and allyl glycyl ether,
(5) Polyacrylate
(6) Polyacrylonitrile
(7) Polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-trichloroethylene copolymer, vinylidene fluoride-hexafluoropropylene fluororubber, vinylidene fluoride “tetrafluoroethylene- Fluoropolymers such as hexafluoropropylene fluororubber can be used.
[0019]
Among these resins, polyvinylidene fluoride (PVDF), polyethylene oxide, polyacrylonitrile, and the like are preferable, and polyvinylidene fluoride homopolymer is particularly preferable. PVDF homopolymer has a wide redox window, is electrochemically stable, and has excellent long-term stability.
[0020]
This matrix resin is dissolved in a predetermined solvent, preferably a mixed solvent of two or more. As a solvent for dissolving the matrix resin, it is necessary that the matrix resin can be dissolved and does not adversely affect the underlying material. It is necessary to satisfy. That is, one solvent is a solvent capable of dissolving the matrix resin, the other solvent is a solvent that does not dissolve the matrix resin and has a boiling point higher than that of the one solvent, and further, both solvents are not separated. It is necessary to be able to mix.
[0021]
Thus, by using a solvent that dissolves the matrix resin and a solvent that does not dissolve the matrix resin, the solvent that dissolves the matrix resin is removed first, and then the solvent that does not dissolve the matrix resin is removed. Pores can be formed in the membrane.
[0022]
Examples of the solvent for dissolving the matrix resin include dimethylacetamide (DMAC), acetone, tetrahydrofuran, methyl ethyl ketone, dimethylformamide (DMF), tetramethylurea, dimethyl sulfoxide, trimethyl phosphate, N-methyl-2-pyrrolidone and the like. Of these, dimethylacetamide (DMAC), dimethylformamide (DMF) and the like are preferable.
[0023]
Examples of resins that do not dissolve the matrix resin include 1-octanol, butylcellsorgo, propylene carbonate, methyl isobutyl ketone, N-butyl acetate, dimethyl adipate, methyl glycolate, cyclohexanone, diacetone alcohol, diisobutyl ketone, ethyl acetoacetate, Examples include dimethyl malonate, triethyl phosphate, cadaflex triacetin, dimethyl phthalate, pentane, methyl alcohol, hexane, carbon tetrachloride, benzene, trichloroethylene, isopropyl acetate, ethyl alcohol, toluene, tetrachloroethylene, xylene, o-chlorobenzene, decane, etc. Of these, 1-octanol, butylcellsorgo and the like are preferable.
[0024]
When two or more solvents are used, the boiling point between the two solvents is preferably 15 ° C. or higher, particularly 20 ° C. or higher. By using two or more kinds of solvents having different boiling points in this way, it is possible to perform the treatment under a plurality of conditions and remove each of the plurality of kinds of solvents separately in the desolvation step (drying step). And by performing such a process, the micropores of the matrix resin are sufficiently opened, and the electrolyte can be sufficiently impregnated.
[0025]
Examples of combinations of solvents having different boiling points include dimethylacetamide (DMAC) and 1-octanol, dimethylformamide (DMF) and butylcellsorgo.
[0026]
The matrix resin dissolved in the solvent is applied to at least one surface of at least one of the separator and the electrode. Further, it is preferably applied on the separator side of the negative electrode, more preferably on the negative electrode surface of the separator, particularly on both surfaces of the separator.
[0027]
The separator sheet forming the separator is composed of one or more of polyolefins such as polyethylene and polypropylene (in the case of two or more, there is a laminate of two or more films), polyethylene terephthalate Polyesters such as these, thermoplastic fluororesins such as ethylene-tetrafluoroethylene copolymer, and celluloses. The form of the sheet includes a microporous membrane film, a woven fabric, a non-woven fabric, etc. having an air permeability measured by the method specified in JIS-P8117 of about 5 to 2000 seconds / 100 cc and a thickness of about 5 to 100 μm.
[0028]
  In the present invention, it is particularly desirable to use a so-called shutdown separator as the separator. By using the shutdown separator, as the temperature inside the electrochemical device rises, the micropores of the separator close, suppressing the conduction of ions and suppressing the current,Thermal runawayCan be prevented. As such a shutdown separator, for example, fine pores containing at least one of low density polyethylene (LDPE), linear low density polyethylene (LLDPE), and high density polyethylene (HDPE) described in Japanese Patent No. 2642206 are disclosed. A separator made of a synthetic resin film having a weight average molecular weight of 7 × 10 5 or more described in Japanese Patent No. 2520316 and containing 1% by weight or more, and a weight average molecular weight / number average molecular weight of 10 to 300 Lithium having a thickness of 0.1 to 25 μm, a porosity of 40 to 95%, an average through hole diameter of 0.001 to 0.1 μm, and a 10 mm width breaking strength of 0.5 kg or more. A method for producing a battery separator, wherein the polyethylene composition is added to a nonvolatile solvent comprising an aliphatic hydrocarbon, a cyclic hydrocarbon, or a mineral oil fraction. A lithium battery separator or the like characterized by being dissolved into a uniform solution, extruding the solution from a die to form a gel-like sheet, removing the non-volatile solvent, and stretching at least twice in one axial direction Can be mentioned.
[0029]
By using a solid electrolyte for such a separator, a highly functional electrochemical device having both the characteristics of the separator and the characteristics of the solid electrolyte can be obtained. That is, the adhesiveness with the electrode is improved, the film strength can be maintained, and an electrochemical device excellent in environmental change and mechanical strength can be obtained. In particular, by applying a matrix resin to the separator in the manufacturing process, handling becomes easy, and manufacturing up to a liquid injection process described later becomes easy. It is desirable that the porosity of such a separator is in the range of 30 to 50%.
[0030]
As another form, a particle layer that does not swell with an organic solvent-based material and melts at a certain temperature may be interposed in the solid electrolyte layer or on the surface of the layer.
[0031]
  The method for applying the matrix resin is not particularly limited and is a known method.Application methodCan be used. Specifically, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method and the like are used. Thereafter, rolling may be performed by a flat plate press, a calender roll, or the like, if necessary.
[0032]
What is necessary is just to apply | coat so that the film thickness of the apply | coated matrix resin may be set to 0.5-10 micrometers by the film thickness at the time of drying, especially 1-5 micrometers.
[0033]
The matrix resin is applied and then dried to remove the solvent. What is necessary is just to heat the drying process for removal of a solvent at the optimal temperature with the solvent used.
[0034]
After the drying step, the matrix resin may be thermally bonded to the separator sheet by heat treatment. The heating temperature at this time varies depending on the matrix resin used, but is specifically about 100 to 120 ° C.
[0035]
The obtained gel electrolyte sheet precursor is sandwiched between a positive electrode and a negative electrode and laminated to obtain a laminate. After this laminated body is put in an exterior body such as an aluminum laminated film, an electrolytic solution is injected and impregnated in a matrix resin. In the gelation process in such a post process, it is necessary to provide the matrix resin with sufficient openings as described above.
[0036]
Finally, the outer package is sealed and subjected to hot pressing to obtain a solid electrolyte electrochemical device.
[0037]
The structure of the electrochemical device of the present invention can be applied to both a wound structure and a stacked structure, but in the case of a stacked structure, a positive electrode, a negative electrode, a solid electrolyte layer, and a separator layer are sequentially stacked. Because of the structure, the film strength required for the winding mold is not required, and the mechanical restrictions on the material for the separator are reduced.
[0038]
The electrochemical element used in the electrochemical device of the present invention is not limited to a battery such as a lithium secondary battery, and a capacitor having a similar structure can be used.
[0039]
<Lithium secondary battery>
The structure of the lithium secondary battery is not particularly limited, but is usually composed of a positive electrode, a negative electrode, and a solid electrolyte / separator, and is applied to a stacked battery, a wound battery, or the like.
[0040]
In addition, the electrode combined with the polymer solid electrolyte may be appropriately selected from those known as electrodes for lithium secondary batteries, and is preferably a composition of an electrode active material and a gel electrolyte, and if necessary, a conductive aid. Is used.
[0041]
The negative electrode uses a negative electrode active material such as a carbon material, lithium metal, lithium alloy or oxide material, and the positive electrode such as an oxide or carbon material capable of intercalating / deintercalating lithium ions. It is preferable to use a positive electrode active material. By using such an electrode, a lithium secondary battery having good characteristics can be obtained.
[0042]
The carbon material used as the electrode active material may be appropriately selected from, for example, mesocarbon microbeads (MCMB), natural or artificial graphite, resin-fired carbon material, carbon black, carbon fiber, and the like. These are used as powders. Of these, graphite is preferable, and the average particle size is preferably 1 to 30 μm, particularly preferably 5 to 25 μm. When the average particle size is too small, the charge / discharge cycle life is shortened and the capacity variation (individual difference) tends to increase. When the average particle diameter is too large, the variation in capacity becomes remarkably large and the average capacity becomes small. The reason why the variation in capacity occurs when the average particle size is large is thought to be because the contact between graphite and the current collector or the contact between graphites varies.
[0043]
As an oxide capable of intercalating and deintercalating lithium ions, a composite oxide containing lithium is preferable. For example, LiCoO₂, LiMn₂O_Four, LiNiO₂, LiV₂O_FourEtc. The average particle diameter of these oxide powders is preferably about 1 to 40 μm.
[0044]
If necessary, a conductive additive is added to the electrode. Preferred examples of the conductive aid include metals such as graphite, carbon black, carbon fiber, nickel, aluminum, copper, and silver, and graphite and carbon black are particularly preferable.
[0045]
The electrode composition is preferably in the range of active material: conducting aid: binder = 80 to 94: 2 to 8: 2 to 18 by weight ratio for the positive electrode, and active material: conducting aid: binding by weight ratio for the negative electrode. Adhesive = 70 to 97: 0 to 25: 3 to 10 is preferable.
[0046]
As the binder, a thermoplastic resin such as a fluorine resin, a polyolefin resin, a styrene resin, or an acrylic resin, or a rubber resin such as fluorine rubber can be used. Specific examples include polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polyacrylonitrile, nitrile rubber, polybutadiene, butylene rubber, polystyrene, styrene-butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, carboxymethyl cellulose, and the like.
[0047]
In producing the electrode, first, an active material and, if necessary, a conductive additive are dispersed in a binder solution to prepare a coating solution.
[0048]
And this electrode coating liquid is apply | coated to a collector. The means for applying is not particularly limited, and may be appropriately determined according to the material and shape of the current collector. In general, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, a roll coating method, a doctor blade method, a gravure coating method, a screen printing method and the like are used. Then, if necessary, a rolling process is performed using a flat plate press, a calendar roll, or the like.
[0049]
The current collector may be appropriately selected from ordinary current collectors according to the shape of the device used by the battery, the method of arranging the current collector in the case, and the like. Generally, aluminum or the like is used for the positive electrode, and copper, nickel, or the like is used for the negative electrode. In addition, a metal foil, a metal mesh, etc. are normally used for a collector. The metal mesh has a smaller contact resistance with the electrode than the metal foil, but a sufficiently small contact resistance can be obtained even with the metal foil.
[0050]
Then, the solvent is evaporated to produce an electrode. The coating thickness is preferably about 50 to 400 μm.
[0051]
Such a positive electrode, a solid electrolyte / separator, and a negative electrode are laminated in this order, and are pressed to form a battery body.
[0052]
The electrolyte solution impregnated in the solid electrolyte / separator generally comprises an electrolyte salt and a solvent. Examples of the electrolyte salt include LiBF._Four, LiPF₆, LiAsF₆, LiSO_ThreeCF_ThreeLiClO_Four, LiN (SO₂ CF_Three )₂ Lithium salts such as can be applied.
[0053]
The solvent of the electrolytic solution is not particularly limited as long as it has good compatibility with the above-described solid polymer electrolyte and electrolyte salt, but a polar organic solvent that does not decompose even at a high operating voltage in a lithium battery, for example, , Ethylene carbonate (abbreviation EC), propylene carbonate (abbreviation PC), butylene carbonate, dimethyl carbonate (abbreviation DMC), carbonates such as diethyl carbonate and ethyl methyl carbonate, cyclic ethers such as tetrahydrofuran (THF) and 2-methyltetrahydrofuran Cyclic ethers such as 1,3-dioxolane and 4-methyldioxolane, lactones such as γ-butyrolactone, sulfolane and the like are preferably used. 3-methylsulfolane, dimethoxyethane, diethoxyethane, ethoxymethoxyethane, ethyl diglyme and the like may be used.
[0054]
The concentration of the electrolyte salt when it is considered that the electrolytic solution is composed of the solvent and the electrolyte salt is preferably 0.3 to 5 mol / l. Usually, the highest ion conductivity is shown around 0.8 to 1.5 mol / l.
[0055]
<Electric double layer capacitor>
The structure of the electric double layer capacitor used in the present invention is not particularly limited, but usually, a pair of polarizable electrodes are arranged via a solid electrolyte / separator, and the polar electrodes and the periphery of the solid electrolyte / separator are An insulating gasket is preferably arranged. Such an electric double layer capacitor may be any of a paper type, a multilayer type, and the like.
[0056]
As a polarizable electrode, activated carbon, activated carbon fiber, or the like is used as a conductive active material, and a fluororesin, fluororubber, or the like is added as a binder. And it is preferable to use what formed this mixture in the sheet-like electrode. The amount of the binder is about 5 to 15% by mass. A gel electrolyte may be used as the binder.
[0057]
The current collector used for the polarizable electrode may be a conductive rubber such as platinum or conductive butyl rubber, or may be formed by thermal spraying of a metal such as aluminum or nickel. A mesh may be attached.
[0058]
The electric double layer capacitor is combined with the above polarizable electrode and a solid electrolyte / separator.
[0059]
As an electrolyte salt, (C₂H_Five)_FourNBF_Four, (C₂H_Five)_ThreeCH_ThreeNBF_Four, (C₂H_Five)_FourPBF_FourEtc.
[0060]
The non-aqueous solvent used in the electrolytic solution may be various known ones, and is an electrochemically stable non-aqueous solvent such as propylene carbonate, ethylene carbonate, γ-butyrolactone, acetonitrile, dimethylformamide, 1,2-dimethoxy. Ethane, sulfolane alone or a mixed solvent is preferred.
[0061]
The concentration of the electrolyte in such a nonaqueous solvent electrolyte solution may be 0.1 to 3 mol / l.
[0062]
When the composition of the polymer solid electrolyte is represented by resin / electrolytic solution, the ratio of the electrolytic solution is preferably 40 to 90% by mass from the viewpoint of the strength of the membrane and the ionic conductivity.
[0063]
An insulating material such as polypropylene or butyl rubber may be used as the insulating gasket.
[0064]
The exterior bag is composed of a laminated film in which a polyolefin resin layer such as polypropylene or polyethylene as a heat-adhesive resin layer or a heat-resistant polyester resin layer is laminated on both surfaces of a metal layer such as aluminum. The exterior bag is formed in a bag shape in which two laminated films are bonded in advance to each other by thermally bonding the heat-adhesive resin layers on the end surfaces of the three sides to form a first seal portion. Alternatively, a single laminate film may be folded and the end faces of both sides may be thermally bonded to form a seal portion to form a bag.
[0065]
As a laminate film, a laminate film having a laminated structure of a heat-adhesive resin layer / polyester resin layer / metal foil / polyester resin layer from the interior side is used to ensure insulation between the metal foil constituting the laminate film and the lead-out terminal. It is preferable to use it. By using such a laminate film, the polyester resin layer having a high melting point remains undissolved at the time of thermal bonding, so that a separation distance between the lead-out terminal and the metal foil of the outer bag can be secured and insulation can be secured. Therefore, the thickness of the polyester resin layer of the laminate film is preferably about 5 to 100 μm.
[0066]
【Example】
The present invention will be described below with reference to examples.
[0067]
<Example 1>
LiCoO as positive electrode active material₂ (90 parts by weight), carbon black (6 parts by weight) as a conductive additive, and PVDF Kynar 761A (4 parts by weight) as a binder are mixed to form a positive electrode mixture, and N-methyl-2-pyrrolidone is used as a solvent. Dispersed into a slurry. The obtained slurry was applied onto an Al foil as a current collector and dried to obtain a positive electrode.
[0068]
  Artificial graphite powder (90 parts by weight) as a negative electrode active material and PVDF Kynar 761A (10 parts by weight) as a binder were dispersed in N-methyl-2-pyrrolidone to form a slurry. This slurryNegative electrode current collectorIt was applied on a Cu foil and dried to obtain a negative electrode.
[0069]
The electrolyte used was a mixed solvent of ethylene carbonate (30 parts by volume) and diethyl carbonate (70 parts by volume), and LiPF.₆ 1 mol dm^-3 The non-aqueous electrolyte made into a solute at a ratio of
[0070]
The following were used as solid electrolyte components.
[0071]
Polymer: Elf Atchem Kyner 301F
Polyolefin sheet: Asahi Kasei Polyethylene (PE) H6022 sheet thickness 27μm
  3 weights of dimethylacetamide (DMAC) solution for the above polymerPart1-octanol and 1 weightPart2 μm each was applied to both surfaces of the polyolefin sheet by the doctor blade method. Thereafter, DMAC was evaporated at an initial drying step of 65 ° C. and then dried at 100 ° C. to evaporate 1-octanol.
[0072]
Finally, it heated to 110 degreeC, the polyolefin sheet and the polymer were laminated, and the gel electrolyte sheet was obtained.
[0073]
The obtained gel electrolyte sheet is sandwiched between the positive electrode and the negative electrode, laminated, the laminate is put in an aluminum laminate film, impregnated by injecting the electrolyte, and then sealed and subjected to 80 ° C. hot pressing. Ten samples of the laminated solid electrolyte lithium battery were obtained.
[0074]
<Example 2>
In Example 1, a gel electrolyte sheet in which a polymer was applied and adhered to only one side of a polyolefin sheet was prepared, and in the case of battery stacking, the same procedure as in Example 1 was performed except that the polymer-coated surface was stacked so that the negative electrode surface side was the side A laminated solid electrolyte lithium battery was obtained.
[0075]
<Example 3>
In Example 2, a laminated solid electrolyte lithium battery was obtained in the same manner as in Example 2 except that the polymer-coated surface of the gel electrolyte sheet was laminated so as to be on the positive electrode side.
[0076]
<Example 4>
In Example 1, a polymer was applied to the positive and negative electrodes to a film thickness of 2 μm by the doctor blade method, and the electrode and the polymer were adhered by heating to 110 ° C. Thereafter, a laminated solid electrolyte lithium battery was obtained in the same manner as in Example 1 except that a laminate was obtained by sandwiching a polyolefin sheet between both electrodes.
[0077]
<Example 5>
In Example 4, a laminated solid electrolyte lithium battery was obtained in the same manner as in Example 4 except that the polymer was applied only to the negative electrode.
[0078]
<Example 6>
In Example 4, a stacked solid electrolyte lithium battery was obtained in the same manner as in Example 4 except that the polymer was applied only to the positive electrode.
[0079]
<Comparative Example 1>
The following were used as solid electrolyte components.
[0080]
  Polymer: PVDF Kynar 2801 made by Elf Atchem (VDF: HFP = 90: 10wt%)
Plasticizer: Dibutyl phthalate (DBP)
Filler: Fumed silica (average particle size 16 nm)
  Each of the above components by weight ratio PVDF: DBP: SiO₂ = Weighed to 30:50:20 and 3 weights of acetone to this mixturePartIn addition, these were mixed and dissolved at room temperature to obtain a slurry gel electrolyte solution.
[0081]
And this gel electrolyte solution was apply | coated to the polyethylene terephthalate (PET) film with the doctor blade method, acetone was evaporated at about 50 degreeC, and the gel electrolysis sheet | seat was obtained.
[0082]
The gel electrolyte sheet was then immersed in hexane to extract the plasticizer DBP. The film thickness (dry film thickness) of this gel electrolyte sheet was 30 μm.
[0083]
Ten samples of solid electrolyte lithium batteries were prepared in the same manner as in Example 1 except that the obtained gel electrolyte sheet was used instead of the gel electrolyte sheet of Example 1.
[0084]
<Comparative example 2>
In Example 1, ten samples of solid electrolyte lithium batteries were prepared in the same manner as in Comparative Example 1 except that the process of applying the polymer was omitted.
[0085]
<Comparative Example 3>
In Example 1, 10 samples of solid electrolyte lithium batteries were prepared in the same manner as in Example 1 except that 1-octanol was not mixed and the 1-octanol drying step was omitted.
[0086]
The batteries prepared in Examples 1-6 and Comparative Example 1-3 were subjected to a charge / discharge cycle test at 23 ° C. with a constant current of 0.5 A and a charge end voltage of 4.2 V and a discharge end voltage of 3.0 V. The cycle test results are shown in FIG. 1, and the overcharge results at 0.5 A current and the heat test results at 155 ° C. for 30 minutes are shown in Table 1. In Table 1,
○: No rupture, ignition, or smoke
×: Any of bursting, ignition, or smoke
It is.
[0087]
[Table 1]

[0088]
As is clear from FIG. 1, charge / discharge characteristics as good as those of Comparative Example 1 were exhibited except for Examples 3 and 6. Examples 3 and 6 are batteries in which no polymer was initially interposed between the negative electrode and the polyolefin porous membrane. The reason why the charge / discharge characteristics of such a battery are not excellent is that the adhesion between the electrolyte layer and the electrode becomes impossible due to gas generation from the negative electrode due to the decomposition of the electrolyte before the formation of SEI (Solid Electrlyte Interphase) during initial charging. As a result, it is considered that current distribution occurs and the charge / discharge characteristics are degraded. On the other hand, in a battery in which a polymer is interposed between the negative electrode and the porous polyolefin membrane, the adhesion between the electrolyte layer and the electrode is maintained even by the gas generation, so that excellent battery characteristics are maintained. It is thought that there is.
[0089]
Also, by interposing a separator that blocks the electrode and ion conduction at a predetermined humidity in the solid electrolyte layer from Table 1, the ion conduction between the electrodes is eliminated due to the temperature rise during high temperature heating or overcharge. It can be seen that thermal runaway due to overcharge and internal short circuit can be prevented, and a highly safe battery can be provided.
[0090]
From the above, it is possible to supply a battery with high safety by interposing the second layer that blocks ion conduction between the electrode and the solid electrolyte layer at a temperature higher than the temperature on the positive electrode or negative electrode side of the solid electrolyte. In particular, it is possible to supply a battery having excellent battery characteristics by allowing a polymer to exist between the negative electrode and the second layer that blocks ion conduction.
[0091]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for manufacturing an electrochemical device that includes a solid electrolyte that has a sufficient ability to retain an electrolyte, has excellent performance, and is easy to manufacture.
[0092]
Moreover, the manufacturing method of the electrochemical device excellent in the self-safety function at the time of abnormality can be provided.
[Brief description of the drawings]
FIG. 1 is a graph showing charge / discharge characteristics of solid electrolyte batteries of Examples and Comparative Examples.

Claims (6)

Two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes, and at least one of the two electrodes and the solid layer between the separator layer A method for producing an electrochemical device having a state electrolyte layer,
The matrix resin that forms the solid electrolyte is applied to only one surface of the separator layer or at least one surface of at least one of the two electrodes , and is dried to form a laminate, and then the matrix resin. A method for producing an electrochemical device by injecting a liquid into a solid electrolyte. Two electrodes are formed to face each other, and have a solid electrolyte layer and a separator layer between the two electrodes, and at least one of the two electrodes and the solid layer between the separator layer A method for producing an electrochemical device having a state electrolyte layer,
  The matrix resin that forms the solid electrolyte is applied to at least one of the two electrodes and the separator layer, dried to form a laminate, and then poured into the matrix resin to form a solid electrolyte. age,
  The method for producing an electrochemical device, wherein the matrix resin is dissolved in at least two kinds of mixed solvents and dried under at least two kinds of different conditions. The method for producing an electrochemical device according to claim 2 , wherein at least one of the two or more mixed solvents is insoluble in the matrix resin. The method for manufacturing an electrochemical device according to claim 1, wherein the separator is a shutdown separator that blocks ion conduction between the electrode and the solid electrolyte layer at a predetermined temperature or higher.   The method for producing an electrochemical device according to claim 1, wherein the matrix resin is a PVDF homopolymer.   The method for producing an electrochemical device according to claim 1, wherein the electrochemical device is a lithium secondary battery.

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