JP2001243985A - Polymer electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte battery that is high in safety. SOLUTION: The polymer electrolyte battery comprises a laminate electrode which has laminated positive electrode having a positive electrode mixture layer on a current collector and a negative electrode having a negative electrode mixture layer on a current collector through a polymer electrolyte therebetween, or a laminate electrode group having laminated two or more of the above laminate electrodes, or a wound electrode having wound the above laminate electrode packed by an outer packaging. At least one of the electrode mixture of positive electrode or negative electrode mixture has photo-transmitting particles. And it is desirable that polymer electrolyte is formed in the electrode mixture. And it is desirable that the photo-transmitting particles are made of white or transparent material with a substance of either glass, plastic or titan oxide, and that the configurations are either of spherical, fiber chip or pellet shape, and further that they have average particle size of 0.3 to 2 times of the average particle size of the active material and that their content in the electrode mixture is 1.5 to 5 weight%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte battery, and more particularly, to a polymer electrolyte battery particularly suitable for use as a power source for portable electronic devices, electric vehicles, road leveling, and the like.

[0002]

2. Description of the Related Art In a polymer electrolyte battery, the electrolyte can be made into a sheet shape, thereby making it possible to produce a large-area and thin battery such as an A4 size plate or a B5 size plate.
Application to various thin products has become possible, and the range of use of batteries has been greatly expanded. Batteries using this polymer electrolyte are excellent in liquid leakage resistance and the like, and are thin and flexible. Therefore, they have a feature not found in conventional batteries that a battery can be designed according to the shape of equipment.

[0003] The polymer electrolyte in this polymer electrolyte battery corresponds to a liquid electrolyte (hereinafter referred to as "electrolyte solution") gelled with a polymer. When the electrolyte solution is gelled, polyvinylidene fluoride, Using a linear polymer such as polyethylene oxide, polyacrylonitrile, and vinylidene fluoride-propylene hexafluoride copolymer, dissolving the linear polymer in the electrolyte by heating, and then cooling. A method of gelling an electrolytic solution by dissolving a polymerizable gelling agent such as a monomer or prepolymer polymerizable with an actinic ray such as ultraviolet light in an electrolytic solution, and polymerizing the polymerizable gelling agent such as the monomer or prepolymer. By irradiating the dissolved electrolyte with actinic rays, monomers and prepolymers are polymerized. The method of gelling the electrolyte has been adopted, but recently, the latter method of gelling the electrolyte by polymerizing monomers and prepolymers by irradiation with actinic rays is faster than gelation. It is commonly used because of its high productivity and excellent productivity.

[0004]

However, in the case where the electrolytic solution is gelled by polymerizing a liquid monomer or a prepolymer by irradiating with an actinic ray, where the actinic ray can easily penetrate, the Although the gelation is performed smoothly, there has been a situation that the gelation of the electrolytic solution is hard to occur in a place where the actinic ray is hardly transmitted. Therefore, the electrolyte solution in which a polymerizable gelling agent such as a monomer or a prepolymer as described above is dissolved is impregnated inside the electrode, that is, in the electrode mixture, and is irradiated with an actinic ray to convert the monomer or the prepolymer into a polymer. When the polymer electrolyte is formed in the electrode mixture by forming the electrolyte solution into a gel by gelling the electrolyte solution, actinic rays hardly penetrate into the electrode mixture, and L, which is generally used as a positive electrode active material, is used.
Metal oxides such as iCoO ₂ (lithium cobalt oxide) and graphite used as a negative electrode active material are black and hard to transmit light, and are more difficult to transmit active light in the electrode mixture. In the mixture, the gelation of the electrolytic solution is unlikely to occur, and therefore, when an abnormality such as a short circuit or heating occurs, a large current may concentrate and flow to the ungelled portion of the electrolytic solution. Further, in the polymer electrolyte battery, since a nonwoven fabric having no shutdown function is used as a support for the polymer electrolyte layer, the current cutoff mechanism does not operate even when an abnormality such as a short circuit or heating occurs. If a large current flows intensively in the non-gelled portion, there is a possibility that smoke, fire or rupture may occur.

[0005] The present invention solves the above problems,
The addition of additives to the electrode mixture promotes the gelling of the electrolyte inside the electrode, and prevents large currents from intensively flowing to the non-gelled portion of the electrolyte, thereby improving battery safety. And thereby provide a polymer electrolyte battery with high safety.

[0006]

SUMMARY OF THE INVENTION The present invention provides a polymer electrolyte comprising a positive electrode having a positive electrode mixture layer formed on a current collector and a negative electrode having a negative electrode mixture layer formed on the current collector. In a polymer electrolyte battery in which a laminated electrode having two or more laminated electrodes laminated or a laminated electrode group in which two or more laminated electrodes are laminated or a wound electrode in which the laminated electrode is wound is packaged with a package, a positive electrode mixture or a negative electrode mixture is used. By including light-transmitting particles in at least one electrode mixture of the agent, the amount of light necessary for polymerizing monomers and prepolymers is transmitted to the inside of the electrode, and gelation of the electrolytic solution inside the electrode To promote
An object of the present invention is to improve the safety of a polymer electrolyte battery and solve the above-mentioned problems.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the light-transmitting particles contained in an electrode mixture such as a positive electrode mixture and a negative electrode mixture include ultraviolet rays (UV) used for polymerizing a monomer or a prepolymer. ), Particles of a material having a high transmittance to actinic rays such as visible light and far ultraviolet rays are preferable, and suitable substances for such light-transmitting particles include white or transparent glass, plastic, titanium oxide, and indium tin composite oxide. From the viewpoint of stability in the electrode mixture, glass, plastic, titanium oxide and the like are particularly preferably used.

The shape of the light-transmitting particles is preferably spherical, fibrous strip, pellet, or the like from the viewpoint of the transmission efficiency of active light rays into the inside of the electrode.

Usually, the light-transmitting particles preferably have an average particle diameter in the range of 2.1 to 20 μm, and the size of the light-transmitting particles is adjusted according to the size of the active material particles of the electrode. Preferably, for example, the light-transmitting particles have an average particle diameter of 0.3 times or more the average particle diameter of the active material particles of the electrode from the viewpoint of the transmission efficiency of the active light rays into the inside of the electrode. The average particle diameter is preferably not more than twice the average particle diameter of the active material particles so as not to inhibit the electrochemical reaction of the active material. In order to sufficiently exhibit the effects of the present invention, the light-transmitting particles are preferably contained in the electrode mixture in an amount of 1.5% by weight or more, more preferably 2% by weight or more. In order to secure the loading amount of the active material and maintain good load characteristics, it is preferable that the light-transmitting particles be contained in the electrode mixture within a range of 5% by weight or less.

The light-transmitting particles are mixed in an electrode mixture which is impregnated with an electrolytic solution in which a polymerizable gelling agent such as a monomer or a prepolymer which is polymerized by actinic rays is dissolved to form a polymer electrolyte inside the electrode. Should be included in the
Therefore, the light-transmitting particles may be contained in any of the positive electrode mixture and the negative electrode mixture, and an electrolytic solution in which a polymerizable gelling agent such as a monomer or a prepolymer is dissolved is mixed with the positive electrode mixture. When impregnating both the inside and the negative electrode mixture, it is preferable to include the light transmitting particles in both the positive electrode mixture and the negative electrode mixture.

In addition, when the light-transmitting particles are contained in the electrode mixture, a gap is formed between the active material particles, and the movement of lithium ions around the active material particles is facilitated. The effect is also recognized. Therefore, the effect of including the light-transmitting particles in the electrode mixture is not limited to the case where the polymer electrolyte is generated inside the electrode (that is, in the electrode mixture). It may be contained in an electrode mixture that does not produce a polymer electrolyte.

In the present invention, as the positive electrode active material used for producing the positive electrode, various materials can be used without particular limitation, and transition metal oxides containing lithium have high energy density and excellent reversibility. For example, specifically, for example, lithium cobalt oxide such as LiCoO ₂ , lithium manganese oxide such as LiMn ₂ O ₄ , lithium nickel oxide such as LiNiO ₂ , a mixture thereof, and further, LiNiO ₂ Ni
Is preferably used in which a part of is replaced by Co or Mn. However, the positive electrode active material is not limited to those exemplified above, for example, one-dimensional chain structure, two-dimensional layered structure, three-dimensional channel structure, cobalt, nickel, vanadium, manganese, iron having an amorphous structure and the like It may be appropriately selected and used from lithium-containing oxides such as oxides or lithium-containing substances such as chalcogens or conductive polymers.

In the present invention, the light-transmitting particles are contained in at least one of the positive electrode mixture and the negative electrode mixture, but when the light-transmitting particles are contained in the positive electrode mixture, the positive electrode mixture is used. The agent is prepared, for example, by mixing the above-described positive electrode active material, light-transmitting particles, and a conductive additive or a binder that is added as necessary. When the binder is dissolved in an organic solvent in advance and then mixed with the positive electrode active material or the light-transmitting particles, the positive electrode active material, the light-transmitting particles, the binder, the conductive additive, and the like are mixed. A paste containing the positive electrode mixture is prepared, and the paste containing the positive electrode mixture is coated on a current collector and dried to form a positive electrode mixture layer. What is necessary is just to make it contain a particle.

As the current collector of the positive electrode, for example, a foil of aluminum, nickel, stainless steel, or the like, a punching metal, a net, an expanded metal, or the like can be used, and an aluminum foil is particularly preferable. The current collector of the positive electrode has a thickness of 30 μm in order to reduce the thickness of the entire positive electrode.
m or less is preferable. However, if it is too thin, wrinkles may occur when the positive electrode mixture-containing paste is applied in producing the positive electrode, or the film may be broken by pulling. Therefore, the thickness is 30 μm as described above.
m and 10 μm or more. The lead portion of the positive electrode is generally provided by leaving a part of the current collector exposed without forming a positive electrode mixture layer on a part of the current collector when the positive electrode is manufactured.

The negative electrode active material used in the preparation of the negative electrode is not particularly limited as long as it is a substance capable of doping and undoping lithium ions, and various materials can be used, and a carbonaceous material is particularly preferable. Specifically, for example, graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads, carbon fibers, activated carbon, graphite, carbon colloids and the like are preferably used. However, in the present invention,
In the case where a flaky carbonaceous material such as natural graphite or flaky graphite is used, since the orientation of the negative electrode active material is disturbed by the presence of the light-transmitting particles, the effect of improving the load characteristics is particularly remarkable. Is expressed.

In the present invention, when the light-transmitting particles are contained in the negative electrode mixture, the negative electrode mixture is prepared, for example, by mixing the above-mentioned negative electrode active material, light transmitting particles, a binder and the like. Is done. When the binder is dissolved in an organic solvent in advance and then mixed with the negative electrode active material or the light transmitting particles, the negative electrode active material, the light transmitting particles, the negative electrode mixture containing the binder and the like are included. A paste is prepared, the negative electrode mixture-containing paste is coated on a current collector and dried to form a negative electrode mixture layer, and the light-transmitting particles are contained in the negative electrode mixture constituting the negative electrode mixture layer. What is necessary is just to be contained.

As the current collector of the negative electrode, for example, a foil of copper, nickel, or the like, a punching metal, a net, an expanded metal, or the like can be used. In particular, a copper foil or a nickel foil is preferable. The current collector of the negative electrode preferably has a thickness of 30 μm or less in order to reduce the thickness of the entire negative electrode. However, if it is too thin, wrinkles may occur when the negative electrode mixture-containing paste is applied during the preparation of the negative electrode, or the film may be broken by pulling,
The thickness is preferably 30 μm or less and 5 μm or more as described above. The lead portion on the negative electrode side is usually provided by leaving an exposed portion of the negative electrode current collector without forming the negative electrode mixture layer on a part of the negative electrode current collector at the time of manufacturing the negative electrode.

In the present invention, as a binder used for producing a positive electrode or a negative electrode, for example, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene butadiene rubber, fluororubber and the like can be mentioned. In addition, examples of the conductive assistant include graphite, acetylene black, carbon black, Ketjen black, carbon fiber, metal powder, metal fiber, and the like.

In the present invention, the polymer electrolyte is an electrolyte.
Transfer the solution to a polymerizable gelling agent such as a monomer or prepolymer.
Prepared by gelling using remerification
Is used to prepare the polymer electrolyte.
As the liquid, for example, dimethyl carbonate, diethyl
Carbonate, methyl ethyl carbonate, propion
Methyl ester, ethylene carbonate, propion carbonate
, Butylene carbonate, gamma-butyrolact
, Ethylene glycol sulfite, 1,2-dimet
Xiethane, 1,3-dioxolan, tetrahydrofura
2-methyl-tetrahydrofuran, diethyl ether
Organic solvents such as LiClO _Four, LiPF
₆, LiBF_Four, LiAsF₆, LiSbF₆, LiC
F_ThreeSO_Three, LiC_FourF₉SO_Three, LiCF_ThreeCO_Two,
Li_TwoC_TwoF_Four(SO_Three)_Two, LiN (CF_ThreeSO_Two)
_Two, LiC (CF_ThreeSO_Two)_Three, LiC_nF_{2n + 1}SO_Three
(N ≧ 2), LiN (RfOSO_Two)_Two[Where Rf is
Dissolve inorganic ion salts such as fluoroalkyl groups)
What has been prepared is used. This inorganic ion
The concentration of the salt in the electrolyte is 0.5 mol / l or more.
Is preferably, and more preferably 0.9 mol / l or more.
1.5 mol / l or less, preferably 1.25 mol / l
/ L or less is more preferable.

As the gelling agent for gelling the above-mentioned electrolytic solution to convert it into a polymer electrolyte, a crosslinkable composition mainly composed of a monomer or a prepolymer containing at least two double bonds per molecule which can be polymerized by actinic rays. A polymerizable gelling agent such as a product is used. Therefore, the expressions such as a monomer and a prepolymer so far are examples of the polymerizable gelling agent.

Examples of the monomer capable of being polymerized by actinic light include monomers having two double bonds per molecule (bifunctional crosslinkable monomers) such as 1,3-butanediol diacrylate and 1,4 -Butanediol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate Acrylate, tripropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, novolak diacrylate, propoxylated neopentyl glycol diacryle Such as difunctional acrylates and the acrylate and similar difunctional methacrylates such as bets and the like.

Examples of a monomer having three double bonds per molecule which can be polymerized by actinic rays (trifunctional crosslinkable monomer) include, for example, tris (2-hydroxyethyl) isocyanurate triacrylate, trimethylolpropane Trifunctional acrylates such as acrylate, ethoxylated trimethylolpropane triacrylate, pentaerythritol triacrylate, propoxylated trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, caprolactone-modified trimethylolpropane triacrylate, and trifunctional methacrylates similar to the above acrylates And so on.

Examples of the monomer having four or more double bonds per molecule which can be polymerized by actinic light (tetrafunctional or more crosslinkable monomer) include, for example, pentaerythritol tetraacrylate, ditrimethylolpropane tetraacrylate, ethoxylated Examples include tetrafunctional or higher acrylates such as pentaerythritol tetraacrylate, dipentaerythritol hydroxypentaacrylate, dipentaerythritol hexaacrylate, and tetrafunctional or higher methacrylate similar to the above acrylate.

Further, two double bonds polymerizable by actinic rays
Examples of the prepolymer having at least four, preferably four or more include prepolymers of urethane acrylate, epoxy acrylate, and polyester acrylate, and can be used in place of the above-mentioned monomers.

In the present invention, the monomer or prepolymer having two or more double bonds polymerizable by actinic light per molecule may be used as a main component, and may be used for adjusting physical properties such as gel hardness. For this purpose, a -functional monomer or the like can be used in combination. Further, a usage such as mixing a bifunctional monomer and a hexafunctional monomer is also possible.

In the present invention, the term "crosslinkable composition comprising a monomer or prepolymer having at least two double bonds per molecule which can be polymerized by actinic light" as a main component refers to the above-mentioned crosslinkable composition polymerized by actinic light. Monomers or prepolymers containing only possible monomers or prepolymers having two or more double bonds per molecule, and monomers or prepolymers having two or more double bonds per molecule that can be polymerized with actinic rays with monofunctional monomers In the case where a monomer or a prepolymer having two or more double bonds capable of being polymerized by actinic light per molecule as in the latter is used in combination with a monofunctional monomer or the like, the crosslinkable composition Of a monomer or a prepolymer having two or more double bonds per molecule which can be polymerized by actinic light, more than 50% by weight, especially 70% by weight. Or more at a wavelength of 550 nm. Also,
The crosslinkable composition does not have to be all crosslinkable as long as the constituents thereof are not crosslinkable, as long as it is entirely crosslinkable.
Other components can be added as needed.

And, if necessary, as a polymerization initiator,
For example, benzoins, benzoin alkyl ethers, benzophenones, benzoylphenylphosphine oxides, acetophenones, thioxanthones, anthraquinones, and the like can be used. Further, alkylamines, aminoesters and the like can be used as a sensitizer of the polymerization initiator.

In the present invention, for example, ultraviolet rays (UV), electron rays (EB), visible rays, far infrared rays and the like can be used as the active rays.

In the present invention, the polymer electrolyte is formed as a polymer electrolyte layer interposed between the positive electrode and the negative electrode, and formed inside the electrode, that is, in the electrode mixture of at least one of the positive electrode mixture and the negative electrode mixture. When formed as a polymer electrolyte layer interposed between the positive electrode and the negative electrode, usually, a porous sheet is used as a support, and, for example, a nonwoven fabric is preferably used as the support. Can be That is, the nonwoven fabric has a high porosity and can easily hold the electrolytic solution containing the polymerizable gelling agent. For example, a very thin nonwoven fabric having a basis weight of 12 g / m ² and a thickness of 30 μm can be used. It is suitable for reducing the internal resistance of the polymer electrolyte layer. And
As the nonwoven fabric, for example, a nonwoven fabric such as polypropylene, polyethylene, polyethylene terephthalate, and polybutylene terephthalate is used.

The polymer electrolyte layer interposed between the positive electrode and the negative electrode may be formed separately from the positive electrode and the negative electrode, and may be interposed between the positive electrode and the negative electrode to form a laminated electrode. Alternatively, one of the positive electrode and the negative electrode or the positive electrode and the negative electrode may be integrally formed around the respective electrodes so that the polymer electrolyte layer is interposed between the positive electrode and the negative electrode. Good.

As described above, the electrode is surrounded by the support,
By integrating the support with the electrode, the insufficient strength of the support can be compensated for by the strength of the electrode even when the strength is low and the strength is low. Therefore, as described above, a thin non-woven fabric can be used as the support, and as a result, the thickness of the polymer electrolyte layer can be reduced, thereby reducing the internal resistance and improving the load characteristics. I do.

Further, the thinner the porous sheet such as a non-woven fabric, the lower the strength and the more difficult it becomes to handle.
When it is laminated as a support with electrodes such as a positive electrode and a negative electrode, misalignment or wrinkles (wrinkles) are likely to occur and workability is reduced. If the electrode is accommodated in it, or the strip-shaped support is folded at almost the center and the electrode is sandwiched between them, the electrode is surrounded by the support, and the support and the electrode are integrated in advance. In addition, it is possible to suppress the occurrence of displacement and wrinkles of the support, and to improve workability. In particular, when the support is formed in a bag shape, occurrence of displacement and wrinkles can be efficiently suppressed, and workability can be significantly improved.

As an embodiment in which the electrode is surrounded by a support made of a porous sheet and the electrode and the support are integrated, the electrode is housed in a bag-like support so that the electrode is surrounded by the support. , When the electrode and the support are integrated, and when the electrode is
There is a case where the electrode is surrounded by the support by sandwiching the support between one or two strip-shaped supports, and the electrode and the support are integrated. Furthermore, when the latter electrode is sandwiched by a strip-shaped support and the electrode is surrounded by the support, the electrode is folded at substantially the center of one strip-shaped support and the electrode is sandwiched therebetween to support the electrode. In some cases, the electrodes are surrounded by the support by sealing one end of two strip-shaped supports and sandwiching the electrode between them.

As described above, the electrode and the support are integrated by surrounding the electrode with the support made of a porous sheet such as a non-woven fabric, and then impregnated with an electrolytic solution containing a gelling component and irradiated with actinic rays. By gelling by polymerizing a gelling component such as a monomer by doing, the gap between the electrode and the polymer electrolyte is closer to the interface than by gelling alone and laminating from the electrode and the polymer electrolyte layer. The bonding state is good, no air bubbles or foreign substances are interposed between the layers, the ion movement at the interface is smooth, and the reactivity between the positive and negative electrodes is improved. In addition, by surrounding one of the positive electrode and the negative electrode with a support, it can serve as a physical separator. However, the integration of the electrode and the support means that the electrode and the support are brought into close contact with each other without including bubbles or foreign matter between the electrode and the support, and are inseparably bonded. It does not mean that.

In order to form a polymer electrolyte in the electrode mixture, the electrode mixture layer is impregnated with an electrolytic solution containing a polymerizable gelling agent such as a monomer or a prepolymer, and irradiated with actinic rays. This is carried out by polymerizing a polymerizable gelling agent such as a monomer or a prepolymer to gel the electrolytic solution.

In the present invention, the exterior body may be any as long as it can externally enclose a power generation element portion such as the above-mentioned laminated electrode, laminated electrode group, and wound electrode in a sealed state. For example, nylon film-aluminum foil-modified A laminate film of a three-layer structure of a polyolefin resin film, a laminate film such as a polyester film-aluminum foil-modified polyolefin resin film, a battery can, a sealing plate, a gasket, and the like may be used.
When forming the outer package with the laminated film, usually, two laminated films are used, and one or both of them are formed in a container with a flange in advance according to the thickness of the laminated electrode, the laminated electrode group, the wound electrode, and the like. It may be molded.

[0037]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited only to those illustrated in the embodiments.

Example 1 In Example 1, the average particle diameter was 5 μm as the light transmitting particles.
m of silica particles, the silica particles are contained in the positive electrode mixture and the negative electrode mixture while varying the amount thereof, and a polymer electrolyte battery is manufactured, and the discharge capacities at 0.2C discharge and 2C discharge are measured. And a short-circuit test was performed to confirm safety. First, the production of the positive electrode used for the polymer electrolyte battery will be described.

Preparation of positive electrode: In the positive electrode of Example 1, LiCoO ₂ having an average particle diameter of 7 μm was used as a positive electrode active material, and the amount of LiCoO ₂ used was fixed at 90 parts by weight.
Using polyvinylidene fluoride as a binder, fixing the amount of polyvinylidene fluoride used to 5 parts by weight, using carbon black as a conductive aid, fixing the amount of carbon black used to 5 parts by weight, Silica particles having a spherical average particle diameter of 5 μm are used as the particles, and the amount of the silica particles used is 0 parts by weight, 1 part by weight, 2 parts by weight,
Parts by weight, 5 parts by weight, 7 parts by weight, and 11 parts by weight, and mixed with N-methyl-2-pyrrolidone as a solvent. Prepared. However, in its preparation, polyvinylidene fluoride was previously dissolved in N-methyl-2-pyrrolidone, and LiCoO ₂ , carbon black and silica particles were added to the polyvinylidene fluoride solution and mixed.

The content of the silica particles in the positive electrode mixture in the seven types of positive electrode mixture-containing pastes thus prepared was 0% by weight, 1.0% by weight, 2.0% by weight, and 2. 9%, 4.8%, 6.5% and 9.9% by weight. However, in calculating the content of the silica particles in the positive electrode mixture, two decimal places are rounded off. This is the same in the following embodiments.

Then, the positive electrode mixture-containing paste is applied to both surfaces of a current collector made of aluminum foil having a thickness of 20 μm, dried to form a positive electrode mixture layer, and subjected to a calendering treatment to give a total thickness of 130 μm. The thickness of the positive electrode mixture layer is adjusted so that the area of the positive electrode mixture layer formation portion on one side is 76 m.
The electrode was cut to have a size of mx 42.5 mm to produce a positive electrode. However, in producing the positive electrode, the paste containing the positive electrode mixture was not applied to part of the aluminum foil, the exposed portion of the aluminum foil was left as a lead portion, and the lead portion was used as a connection portion with the positive electrode terminal.

Preparation of negative electrode: 90 parts by weight of flaky graphite having an average particle diameter of 10 μm, 8 parts by weight of polyvinylidene fluoride, and 2 parts by weight of spherical silica particles having an average particle diameter of 5 μm as light transmitting particles Was mixed uniformly using N-methyl-2-pyrrolidone as a solvent to prepare a negative electrode mixture-containing paste. However, in preparation,
Polyvinylidene fluoride was previously dissolved in N-methyl-2-pyrrolidone, and flaky graphite and silica particles were added to the polyvinylidene fluoride solution and mixed.

The paste containing the negative electrode mixture was applied to both surfaces of a current collector made of a copper foil having a thickness of 10 μm, dried to form a negative electrode mixture layer, and then subjected to a calendering treatment to give a total thickness of 130 μm. The thickness of the negative electrode mixture layer was adjusted so that the area of the negative electrode mixture layer formation portion on one side was 76 mm × 4.
A negative electrode was prepared by cutting to 4.5 mm. In Example 1, the content of the silica particles of the negative electrode in the negative electrode mixture was 2% by weight. However, in producing the negative electrode, the paste containing the negative electrode mixture was not applied to part of the copper foil,
The exposed portion of the copper foil was left as a lead portion, and the lead portion was used as a connection portion with the negative electrode terminal. In the above cutting, the lead portion serving as the connection portion with the negative electrode terminal was set at the center position in the width direction of the negative electrode.

Preparation of electrolytic solution containing gelling monomer: 1.22 mol / l of LiPF ₆ dissolved in a mixed solvent of propylene carbonate and ethylene carbonate at a volume ratio of 1: 1 as a polymerization initiator 2,4,6-Trimethylbenzoyldiphenylphosphine oxide (trade name: Lucylin TPO, manufactured by BSF Japan Co., Ltd.) was previously added and dissolved at a ratio of 2% by weight to the monomer, and dissolved.
10 minutes before the start of use, dipentaerythritol hexaacrylate was added as a monomer of the polymerizable gelling agent so as to have a concentration of 6% by weight, and mixed, and an electrolytic solution containing the monomer as a polymerizable gelling agent was added. Prepared. The electrolytic solution containing a monomer as a polymerizable gelling agent is hereinafter simply referred to as a “gelling monomer-containing electrolytic solution” as described above.

In Example 1, the positive electrode was wrapped with a nonwoven fabric serving as a support for the polymer electrolyte layer, the positive electrode and the support were integrated into a positive electrode unit, and the whole was impregnated with an electrolyte solution containing a monomer for gelation. And gel the electrolyte,
Polymer electrolyte layer-Polymer electrolyte-containing positive electrode unit was obtained. The negative electrode was impregnated with a gelling monomer-containing electrolyte solution without being wrapped with a nonwoven fabric, and the electrolyte solution was gelled to obtain a polymer electrolyte-containing negative electrode. The production thereof is described below.

Preparation of Polymer Electrolyte Layer-Polymer Electrolyte Containing Positive Electrode Unit: As a support for the polymer electrolyte layer, a polybutylene terephthalate nonwoven fabric having a thickness of 30 μm and a basis weight of 12 g / m ² [MB1230 (trade name, manufactured by NKK)] This was cut into a strip having a length × width of 80 mm × 45 mm.

A polyimide tape having a thickness of 50 μm and a width of 3 mm was attached to both sides of the positive electrode mixture layer forming portion of the positive electrode and the lead portion to prevent short circuit and maintain the strength of the terminal. In addition, after covering all surfaces of the portion used for welding of the terminal with a heat-peeling tape that loses the adhesiveness of the bonding surface due to heat, it is placed on the left side of the center in the length direction of the polybutylene terephthalate nonwoven fabric. Then, the right side is turned over to cover the positive electrode, and both sides in the width direction are sealed with a heat sealer (trade name: Policyrar, manufactured by Fuji Impulse Co., Ltd.), and polybutylene terephthalate is used as a support. The nonwoven fabric was made into a bag shape, and the two were brought into close contact with each other to integrate the positive electrode and the support into a positive electrode unit. The positive electrode unit was immersed in the gelling monomer-containing electrolyte solution under reduced pressure for 1 minute to impregnate the gelling monomer-containing electrolyte solution into the positive electrode unit, and then placed in a polyethylene bag and sealed. Next, from both sides of the polyethylene bag,
Using an ultraviolet irradiation device manufactured by Fusion UV Systems Japan Co., Ltd., ultraviolet light was irradiated at an illuminance of 1 W / cm ² for 1 hour.
Irradiation was performed for 0 second to polymerize the monomer in the electrolytic solution to polymerize it, and the electrolytic solution was gelled to obtain a gel polymer electrolyte. As a result, a gelled polymer electrolyte is formed inside the positive electrode, that is, in the positive electrode mixture, and a positive electrode containing the polymer electrolyte is obtained, and a polymer electrolyte layer having a polybutylene terephthalate nonwoven fabric as a support is formed therearound. Was.

As described above, the integrated product of the positive electrode containing the gel polymer electrolyte and the polymer electrolyte layer is taken out of the bag, and the terminal portion is blown with hot air at 150 ° C. to peel off the thermal release tape from the terminal portion. Thus, a polymer electrolyte layer-a polymer electrolyte-containing positive electrode unit was obtained.

Preparation of a negative electrode containing a polymer electrolyte: As in the case of the positive electrode, a polyimide tape having a thickness of 50 μm and a width of 3 mm is attached to both sides of the negative electrode mixture layer forming portion and the lead portion of the negative electrode, The short circuit was prevented and the strength of the terminal was maintained. In addition, the entire surface of the portion used for welding the terminal is covered with a heat-peeling tape that loses the adhesiveness of the adhesive surface due to heat, and immersed in the gelling monomer-containing electrolytic solution under reduced pressure for 1 minute to form a gel. After being impregnated with the electrolytic solution containing the monomer for chemical conversion, the resultant was put in a polyethylene bag and sealed.
Next, from both sides of the polyethylene bag, fusion U
Using an ultraviolet irradiator manufactured by V Systems Japan Co., Ltd., irradiate ultraviolet rays at an illuminance of 1 W / cm ² for 10 seconds,
The monomers in the electrolyte were polymerized by polymerization, and the electrolyte was gelled to form a gel polymer electrolyte. As a result, a gel polymer electrolyte was formed inside the negative electrode, that is, in the negative electrode mixture, and a negative electrode containing the polymer electrolyte was obtained.

The negative electrode containing the gel polymer electrolyte was taken out of the bag as described above, and 15
By blowing hot air at 0 ° C., the thermal release tape was peeled off from the terminal portion, thereby obtaining a polymer electrolyte-containing negative electrode.

The polymer electrolyte layer-polymer electrolyte-containing positive electrode unit and the polymer electrolyte-containing negative electrode obtained as described above were overlaid to produce a laminated electrode.

The obtained laminated electrode was packaged with a package consisting of a laminate film having a three-layer structure of a nylon film-aluminum foil-modified polyolefin resin film to prepare a polymer electrolyte battery.

FIG. 1 is a schematic sectional view of the polymer electrolyte battery. The polymer electrolyte battery shown in FIG. 1 will be described. A polymer electrolyte layer 3 having a polybutylene terephthalate non-woven fabric as a support is formed around a positive electrode 1, and the polymer electrolyte layer 3 disposed on the upper surface of the positive electrode 1 is formed.
And the negative electrode 2 is disposed so as to face through. The positive electrode 1 and the negative electrode 2 contain the polymer electrolyte generated as described above in the inside thereof, that is, in the electrode mixture, and are formed by stacking the positive electrode 1, the polymer electrolyte layer 3, and the negative electrode 2. The electrodes are packaged with a package consisting of a laminated film having a three-layer structure of a nylon film-aluminum foil-modified polyolefin resin film. For the exterior of the laminated electrode, two laminated films as the exterior body 4 are used, and the two laminated films are arranged so that the respective modified polyolefin resin films face the upper and lower surfaces of the laminated electrode. The modified polyolefin resin film at the joint of the laminate film is heat-sealed to seal the power generating element portion of the laminated electrode. However, from the positive electrode 1, one end of the positive electrode terminal 5 is drawn out of the battery through the joint of the outer package 4, and from the negative electrode 2, one end of the negative electrode terminal 6 passes through the joint of the outer package. Is pulled out of the battery. FIG. 1 schematically illustrates the polymer electrolyte battery of Example 1, and illustrates the current collector used in manufacturing the positive electrode 1 and the negative electrode 2 and the nonwoven fabric used in manufacturing the polymer electrolyte layer 3. Or positive terminal 5
The details of the connection between the inner end of the battery and the lead of the positive electrode and the details of the connection between the inner end of the negative electrode terminal 6 and the lead of the negative electrode are not shown. Also, in an actual polymer electrolyte battery, the positive electrode terminal 5 and the negative electrode terminal 6 are often provided in the same direction with a gap provided between them. Alternatively, one of the negative terminals 6 cannot be illustrated, and FIG. 1 schematically illustrates the positive terminal 5 and the negative terminal 6 as drawn in opposite directions.

The above batteries were measured for discharge capacity at 0.2 C discharge and discharge capacity at 2 C discharge, and were subjected to a short-circuit test. Table 1 shows the results. The discharge capacity was a constant current of 4.2 V at the above-mentioned 0.2 C and 2 C, respectively.
The measurement was performed by charging at a constant voltage and discharging at a constant current of 2.75 V. The load characteristics under heavy load can be determined from the measurement result of the discharge capacity in the 2C discharge. The short-circuit test was conducted in 4.2
In a charged state of 5 V, nail penetration was performed at a nail penetration speed of 50 mm / s, and the presence or absence of smoke from the inside of the battery and the maximum temperature when the temperature of the battery increased were examined.

[0055]

[Table 1]

As is clear from the results shown in Table 1, by incorporating silica particles in the positive electrode mixture, it is possible to suppress the temperature rise of the battery in the short-circuit test, prevent the generation of smoke, and improve the safety. Can be. However, when the content of the silica particles increases, the discharge capacity in 2C discharge decreases, and the load characteristics tend to decrease.

Example 2 The content of the silica particles in the positive electrode mixture was set to 2% by weight, the content of the silica particles in the negative electrode mixture was set to 3% by weight, and the spherical silica particles contained in the negative electrode mixture were mixed. Average particle size is 1μ
Example 1 except that the negative electrode mixture was included in the negative electrode mixture instead of m, 2 μm, 5 μm, 10 μm, 20 μm, and 30 μm.
6 types of polymer electrolyte batteries were produced in the same manner as described above.
To explain this in more detail, the composition of the positive electrode mixture is 90 parts by weight of LiCoO ₂ having an average particle diameter of 7 μm, 5 parts by weight of polyvinylidene fluoride, 5 parts by weight of carbon black, and 2.04 parts by weight of spherical silica particles having an average particle diameter of 5 μm. And the content of silica particles in the positive electrode mixture is 2% by weight. The composition of the negative electrode mixture was composed of 90 parts by weight of graphite having an average particle diameter of 10 μm, 8 parts by weight of polyvinylidene fluoride, and 3.03 parts by weight of silica particles,
The content of silica particles in this negative electrode mixture was 3% by weight.
It is. However, in this negative electrode mixture, silica particles having an average particle diameter of 1 μm, 2 μm, 5 μm, 10 μm,
They are changed to 0 μm and 30 μm. Therefore, there are six types of negative electrode mixtures, and there are also six types of polymer electrolyte batteries.

With respect to the above six types of polymer electrolyte batteries, the discharge capacity at 0.2 C and 2 C was measured in the same manner as in Example 1, and a short-circuit test was performed. Table 2 shows the results.

[0059]

[Table 2]

As is evident from the results shown in Table 2, the average particle diameter of the silica particles contained in the negative electrode mixture was the average particle diameter of graphite as the negative electrode active material (in Example 2, the average particle diameter of graphite was (In this example 2, the average particle diameter of the silica particles is 5 μm, 10 μm).
m, 20 μm), the temperature rise of the battery in the short-circuit test can be suppressed, smoke can be prevented, and safety can be improved.

Example 3 The content of the silica particles in the positive electrode mixture was 2% by weight, and the content of the silica particles in the negative electrode mixture was 0 part by weight, 1 part by weight,
7 kinds of polymer electrolyte batteries were prepared in the same manner as in Example 1 except that the silica particles were contained in the negative electrode mixture by changing to 3 parts by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, and 11 parts by weight. Produced. To explain this in more detail, the composition of the positive electrode mixture is 90 parts by weight of LiCoO ₂ having an average particle diameter of 7 μm, 5 parts by weight of polyvinylidene fluoride, 5 parts by weight of carbon black, and 2.04 parts by weight of spherical silica particles having an average particle diameter of 5 μm. And the content of silica particles in the positive electrode mixture is 2% by weight. On the other hand, in the negative electrode mixture, 90 parts by weight of graphite having an average particle diameter of 10 μm and 8 parts by weight of polyvinylidene fluoride are fixed, and the amount of silica particles having an average particle diameter of 5 μm as light-transmitting particles is reduced. A negative electrode mixture was prepared for each of 0 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight and 11 parts by weight. Accordingly, there are seven types of negative electrode mixtures, and polymer electrolyte batteries are manufactured according to the respective negative electrode mixtures, so that there are seven types of polymer electrolyte batteries. And the content of the silica particles in the negative electrode mixture is
2. 0 wt%, 1.0 wt%, 2.0 wt%, and 3 wt%, respectively.
0%, 4.9%, 6.7% and 10.1%
% By weight.

For the above seven types of polymer electrolyte batteries, the discharge capacities at 0.2 C and 2 C were measured in the same manner as in Example 1, and a short-circuit test was performed. Table 3 shows the results.

[0063]

[Table 3]

As is evident from the results shown in Table 3, by including silica particles in the negative electrode mixture, the temperature rise of the battery in the short-circuit test can be suppressed, smoke can be prevented, and safety can be improved. Can be. However, when the content of the silica particles in the negative electrode mixture increases, the discharge capacity in 2C discharge tends to decrease, and in order to maintain good heavy load characteristics, the content of the silica particles in the negative electrode mixture increases. Is preferably not too high.

Comparative Example 1 A polymer electrolyte battery was produced in the same manner as in Example 1 except that the light-transmitting particles were not contained in the positive electrode mixture and the negative electrode mixture. The load characteristics of this polymer electrolyte battery were measured in the same manner as in Example 1, and the results were as follows.
The discharge capacity at 2C was 1600 mAh, and the discharge capacity at 2C discharge was 893 mAh. Further, when a short-circuit test was performed, the battery exploded and ignition was recognized.

In the above Examples 1 to 3, the case where silica particles were used as the light-transmitting particles was shown. However, in addition to the silica particles, glass fiber flakes, plastic fiber flakes, plastic pellets, Similar results were obtained when using titanium oxide.

[0067]

As described above, the present invention provides a highly safe polymer electrolyte battery by including light-transmitting particles in at least one of the positive electrode mixture and the negative electrode mixture. We were able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing one example of a polymer electrolyte battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Polymer electrolyte layer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Eri Yokoyama 1-88 Ushitora, Ibaraki-shi, Osaka F-term in Hitachi Maxell Co., Ltd. 5H024 AA01 AA02 BB07 CC04 EE05 EE06 EE09 HH01 HH13 5H029 AJ12 AK03 AK05 AK16 AL07 AL08 AM03 AM04 AM05 AM07 AM16 BJ04 DJ08 DJ15 DJ16 HJ01 HJ05 5H050 AA15 BA18 CA07 CB08 CB09 DA09 DA14 EA12 EA13 EA23 FA02 FA05 FA16 FA17 HA01 HA05

Claims (8)

[Claims] 1. A positive electrode having a positive electrode mixture layer formed on a current collector, and a negative electrode having a negative electrode mixture layer formed on a current collector,
A polymer electrolyte battery in which a laminated electrode laminated with a polymer electrolyte layer interposed, a laminated electrode group in which two or more laminated electrodes are laminated, or a wound electrode wound with the laminated electrode is packaged with a package. A polymer electrolyte battery comprising light-transmitting particles contained in at least one electrode mixture of a negative electrode mixture or a negative electrode mixture. 2. The polymer electrolyte battery according to claim 1, wherein a polymer electrolyte is generated in the positive electrode mixture. 3. The polymer electrolyte battery according to claim 1, wherein the light transmitting particles are a white or transparent substance. 4. The polymer electrolyte battery according to claim 1, wherein the material of the light transmitting particles is any one of glass, plastic, and titanium oxide. 5. The polymer electrolyte battery according to claim 1, wherein the shape of the light transmitting particles is any one of a sphere, a fibrous strip, and a pellet. 6. The polymer according to claim 1, wherein the average particle diameter of the light-transmitting particles is in the range of 0.3 to 2 times the average particle diameter of the active material. Electrolyte battery. 7. The polymer electrolyte battery according to claim 1, wherein the content of the light transmitting particles in the electrode mixture is 1.5 to 5% by weight. 8. The polymer electrolyte battery according to claim 1, wherein natural graphite or flaky graphite is used as the negative electrode active material.