JP2885426B2 - Plastic rechargeable battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plastic secondary battery, and more particularly to a secondary battery that can be used as a power source for various electronic devices.

[Related Art] In recent years, batteries using polyacetylene, polypyrrole, polyaniline, or the like as an active material have been proposed.

The so-called conductive polymer material has a higher energy density than conventional inorganic battery materials, and is not inferior to the theoretical energy density of new batteries. However, since the density of the organic polymer material itself is lower than that of the conventional inorganic active material, the volume energy density is low, and when the density is increased by, for example, pressing, the permeation of the electrolytic solution is deteriorated. For this reason, in order to uniformly store energy (doping) in the entire active material, it is necessary to devise a mounting surface in order to improve morphology and volume energy density suitable for the penetration of the electrolyte. is there.

Therefore, when producing a mixture as in the case of conventional battery materials, it is important to minimize the amount of binder and conductive filler to be added and to efficiently extract energy.

To achieve these tasks, the following considerations are required.

Fill the active material with high density Improve the electrical conductivity of the mixture Improve the ionic conductivity, that is, the ion diffusivity in the mixture In order to perform doping quickly, the morphology so that the electrolyte spreads as close as the active material To consider.

Specifically, a method for producing a positive electrode mixture includes: 1) dispersing various carbon bodies in an appropriate amount in an active material to prevent an increase in impedance at the time of discharge; and 2) forming a fluorine-based binder to form the active material. It has been proposed that a method such as mixing is also performed for a battery using a conductive polymer material for the positive electrode, but the conventional mixture composition is not sufficient because the active material is an organic polymer material. It has been difficult to bring out good battery performance.

[Problems to be Solved by the Invention] An object of the present invention is to solve the problems of the conventional plastic secondary battery and to provide a plastic secondary battery having excellent performance.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in a secondary battery using an organic polymer material as an active material, an ion-conductive material is formed inside an electrode binder. By using a polymer material, we found a new positive electrode for batteries that is completely different from conventional ones. Also, by using a fibrous filler as the conductive filler, the battery performance was significantly improved.

That is, the structure of the present invention relates to a battery using a conductive or semiconductive polymer material as a positive electrode active material, wherein the positive electrode is composed of an active material, a conductive filler, and an ion conductive binder. Battery.

Examples of the polymer material that can be an active material in the present invention include redox active polymer materials such as polyacetylene, polypyrrole, polythiophene, polyaniline, polydiphenylbenzidine, polycarbazole, polyvinylcarzole, and polytriphenylamine.

These polymer materials form a complex with electrolyte ions by electrochemical doping, accumulate energy and show high electrical conductivity, and release ions through dedoping to release energy through an external circuit and increase electrical resistance . The electrode material is required to have an electrical conductivity of 10 ⁻³ S / cm or more in a doped state.

The present invention is a secondary battery using as an electrode a mixture obtained by adding at least an ion-conductive polymer material and a conductive filler to a redox polymer material. The ion-conductive polymer material is a polymer matrix capable of forming a solid solution with an electrolyte salt and refers to a polymer having a molecular weight of several hundred or more oligomers, and can be cross-linked by a functional group at the end of these segments. Examples of the polymer compound that forms a solid solution with an electrolyte salt include a polymer composed of a linear polymer segment having a heteroatom having a high donor property such as oxygen and nitrogen, such as polyethylene oxide, polyethylene imine, and polypropylene oxide. A polymer compound having an ion-dissociable group as a main chain or a side chain is exemplified. Specifically, polyethylene oxide, polypropylene oxide, polyethylene imine, and copolymers thereof, or polyphosphazenes, polysiloxanes, polypeptides, polyacrylates, polymethacrylates, and the like having an ion-dissociating group in a side chain. Is raised. Further, esters such as poly-β-propiolactone, polyvinylene carbonate, and the like can be mentioned. Above all, a crosslinked product of a polyethylene oxide-based polymer material is excellent, and if the crosslink density is reduced by an appropriate amount, the crosslinkable material has tackiness and the binding force increases. The crosslink density is preferably 30 to 70%, and if it is less than 30%, it has fluidity in the battery system, and if it exceeds 70%, it lacks in adhesive strength.

The amount of ion conductive polymer material used is 3-30%,
Preferably it is 5 to 20%. If it is 3%, there is a problem in terms of binding force and ionic conductivity, and if it is 30% or more, it is disadvantageous in terms of energy density.

Conductive fillers include conductive carbon powders such as acetylene black, aniline black, activated carbon, and graphite powders; carbon materials starting from PAN, pitch, cellulose, and phenol; and carbon oxides and metal oxides such as Ti, Sn, and In. Powder, stainless steel, metal powder such as nickel,
Fiber. The properties required for these conductive fillers include high electrical conductivity and an effect with a small amount of addition, and fibrous fillers are particularly preferred.

The fibrous filler preferably has an aspect ratio of 3 to 1000, more preferably 10 to 100, and can achieve high current collection efficiency with a small amount of addition compared to the granular filler. In this respect, carbon fibers and stainless fibers are preferable. If the aspect ratio is small, the effect is low and too large.
The higher the oil absorption, the better. The effect is obtained with a small amount of addition, and the energy of the active material can be efficiently extracted. The most suitable filler for these requirements is carbon fiber. Phenolic carbon fibers are preferred from the viewpoint of increasing the energy capacity. The mixture thus obtained can be added in a range of 10% or less.

The mixture is obtained by kneading the above components alone or together with a solvent and coating and / or vacuum pressure molding.
The appropriate pressure at this time was 50 to 500 kg.

The thickness of the mixture layer of the positive electrode is 1 to 1000 μm, preferably 5 to 500 μm. If it is 5 μm or less, it is disadvantageous in terms of energy density, and if it is 1000 μm or more, it is disadvantageous in terms of current collection efficiency. In coating, a flexible layer can be obtained by forming a film having a thickness within several tens of μm on a substrate.

The non-aqueous secondary battery system of the present invention basically comprises a mixture of these conductive or semiconductive positive electrode active materials together with the above-mentioned conductive filler and ion-conductive binder, and a non-aqueous electrolyte. It is composed of a liquid and a negative electrode.

 The battery configuration of the present invention will be described in more detail.

The electrolyte solvent of the present invention is propylene carbonate, ethylene carbonate, carbonates such as butylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, ethers such as 1,2-dimethoxyethane, ethoxymethoxyethane, methyldiglyme, methyltriglyme, 1 1,3-dioxolane, 4-methyldioxolane, gamma-butyl lactone, sulfolane, 3-methylsulfolane, etc. can be used alone or as a mixture. A mixture of a solvent mainly composed of carbonates, lactones and ethers exhibits particularly excellent performance. . The positive electrode mixture in the present invention is obtained by incorporating a large amount of this electrolyte into Redox.
The reaction takes place immediately. Therefore, it is preferable that the electrolyte composition is previously contained in the positive electrode mixture from the viewpoint of enhancing performance, and the density of the mixture is preferably 0.6 to 0.9.

Further, the electrolyte salt in the present invention comprises an anion containing a halogen and a cation, and as an anion, Br ⁻ , Cl ⁻ ,
F ^- Other halogen ions, such _{^{as, ClO 4 -, BF 4 -}} , AsF 6 -, Sb
_{^{F 6 -, PF 6 -,}} AlF 6 3-, SiF 6 2-, CF 3 SO 3 - is like, BF ₄ ^- or PF ₆ ^- is excellent in combination with polymeric active material.

As the negative electrode active material, conductive polymers such as polyacetylene, polythiophene, polyparaphenylene, and polypyridine, alloys of Li and Al, Mg, Pb, Si, Ga, and In can be used. For the negative electrode, the sheet-shaped negative electrode active material can be used alone.However, in order to improve the handleability of the sheet-shaped negative electrode and the current collection efficiency, the composite of the negative electrode active material and the current collector is required. Can be used.

As a material of the negative electrode current collector, Ni, Al, Cu, Pt, Au, stainless steel and the like are preferable, but Al is more preferable from the viewpoint of weight reduction. Conventionally, to prevent dendrite, Al-Li
Although an alloy is used as the negative electrode, Al and Li may not be alloyed.

As a method of laminating the negative electrode active material on the negative electrode current collector, there are a method of forming the negative electrode active material by vapor deposition or an electrochemical method, and a mechanical method such as bonding of the current collector to an active material such as Li. Can be

In the electrochemical method, Li or the like may be deposited using the negative electrode current collector itself as an electrode. However, after the negative electrode current collector is coated with an ion-conductive polymer and then electrolytically deposited, the current collector is deposited. -An active material such as Li can be uniformly deposited on a polymer interface.

As the separator, a microporous membrane or nonwoven fabric such as polypropylene or polyethylene, a glass fiber filter, a nonwoven fabric, or a nonwoven fabric composed of polypropylene, polyethylene fiber and glass fiber is used. The separator can be mounted in a form that is simply bonded to the positive electrode, but preferably, a mixture of the positive electrode active material, the conductive filler, and the ionic conductive binder is applied to the separator, molded, and the separator and the positive electrode are integrated. It is advantageous in terms of handling at the time of mounting, and short-circuiting and capacity reduction due to displacement of the separator and the electrode can be prevented.

Alternatively, the positive electrode active material and the ionic conductive binder containing no conductive filler may be processed into a film shape, and may be pressed on the positive electrode or formed on the positive electrode to have the function of a separator and an electrolytic solution.

As a form at the time of mounting, the thickness of the positive electrode can be arbitrarily changed to 20 to 1000 μm, and since it is flexible, it can be mounted in any form such as a card type, a coin type and a spiral type.

 Hereinafter, the present invention will be described specifically with reference to Examples.

EXAMPLES Synthesis Method 1 of Positive Electrode Active Material Polyaniline synthesized by the method described in Conducting Polymers, 105 (1987) was reduced with a hydrazine-methanol solution.

Synthesis Method 2 of Positive Electrode Active Material A polyaniline was synthesized from a 0.75 MH ₂ SO ₄ , 0.5 M aniline solution by 0.8 V vs. SCE constant potential electrolytic polymerization, and then 0.1 M HBF ₄
After performing a reduction treatment with -0.4 V vs SCE in an aqueous solution, pulverization was performed to obtain a polyaniline powder.

Synthesis Method 3 of Positive Electrode Active Material After dissolving 20 g of FeCl ₃ .6H ₂ O in 100 ml of acetonitrile, 5 g of pyrrole was added and stirred for 30 minutes to obtain a polypyrrole powder.

Production Method 1 of Positive Electrode A phenolic carbon fiber 0.05 having an aspect ratio of 30 was added to polyaniline 1 obtained by a method for synthesizing a positive electrode active material, and a PEO-PPO block copolymer triol represented by
g, tolylene-2,4-diisocyanate 0.30 g, dibutyltin dilaurate 0.01 g was dissolved in methyl ethyl ketone 10 g, and LiClO ₄ was dissolved in 0.23 g to obtain an ionic conductor of 0.03 g.
The components added at a ratio of 5 were mixed, cast on a polypropylene nonwoven fabric at a thickness of 100 μm, and heated at 100 ° C. for 20 minutes.

Positive electrode production method 2 A positive electrode was produced in the same manner as in the positive electrode production method 1 except that the polypyrrole obtained in the positive electrode active material production method 3 was used.

Positive electrode manufacturing method 3 To polyaniline 1 obtained in positive electrode active material manufacturing method 2, cinnamoylated polyethylene oxide 0.08 was mixed with PAN-based carbon fiber 0.06 having an aspect ratio of 52, and 10 μm SU
The S foil was applied on a foil blasted with 200 mesh emery particles at a thickness of 150 μm, and irradiated with ultraviolet rays to produce a positive electrode.

Positive electrode manufacturing method 4 In positive electrode manufacturing method 1, an aspect ratio of 42 was used as a conductive agent.
A positive electrode mixture was produced in the same manner except that SUS fiber was used, and a 20 μm SUS foil was applied in a thickness of 150 μm on a foil blasted with 200 mesh emery particles to produce a positive electrode.

Example 1 using the electrode produced in the positive electrode manufacturing 1 one punched out into discs with a diameter of 18mm to the positive electrode, 5M LiBF ₄ / propylene carbonate + dimethoxyethane as an electrolyte using Li as a negative electrode (7: 3) using A CR-2016 type coin-type battery was manufactured.

Example 2 A coin-type battery was manufactured in the same manner as in Example 1 except that the positive electrode manufactured by the positive electrode manufacturing method 2 was used.

Example 3 A positive electrode manufactured using the method 1 for manufacturing a positive electrode was used, and a negative electrode was used.
A coin-type battery was manufactured in the same manner as in Example 1 except that a Li-Al alloy, 3M LiBF ₄ / propylene carbonate was used as an electrolyte, and a polypropylene microporous membrane 3 was used as a separator.

Example 4 A coin-type battery was manufactured in the same manner as in Example 3, except that the positive electrode manufactured by the positive electrode manufacturing method 4 was used as the positive electrode.

Comparative Example 1 A coin-type battery was manufactured in the same manner as in Example 1 except that Teflon dispersion was used as a binder.

Comparative Example 2 A coin battery was manufactured in the same manner as in Example 1 except that Ketjen Black was used as the conductive agent.

The above battery was charged and discharged at a constant current of 1 mA, and the battery performance was tested.

[Effects of the Invention] As described above, the electrode of the present invention has a high weight energy density and is excellent in flexibility.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumito Masuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Toshiyuki Kahata 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 4/00-4/04 H01M 4/36-4/62 H01M 10/36-10/40

Claims (1)

(57) [Claims] 1. A battery using a conductive or semiconductive polymer material as a positive electrode active material, wherein the positive electrode is composed of an active material, a conductive filler, and an ion conductive binder. Plastic secondary battery.