JPH02162651A - Cylindrical lithium battery - Google Patents

Abstract

PURPOSE:To prevent generation of wrikles in a film to obtain a battery having no performance deterioration by forming a solid polymer electrolyte film having the functions of separator and electrolyte in either one of positive and negative electrodes. CONSTITUTION:A material for forming a solid polymer electrolyte film having the functions of separator and electrolyte is applied onto both sides of either one of positive and negative electrodes, and active light is irradiated to the material to form the films on the electrode. The other electrode is stacked thereon, and they are spirally wound to form a battery. Since generation of wrikles in the separator is prevented, a cylindrical lithium battery having no performance deterioration can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cylindrical spiral battery formed by winding strip-shaped positive and negative electrode plates with a separator electrolyte in between.

[Prior Art and its Problems] A cylindrical spiral type lithium battery is composed of an electrode group in which positive and negative electrode plates are spirally wound through a separator. Various methods are known for forming the separator. For example, a positive electrode mixture sheet is wrapped in a bag-shaped separator, and a negative electrode plate is further stacked.
After winding it into a spiral shape, it is placed in a battery case.

A known method is to inject a liquid electrolyte into the separator to impregnate it into a battery.

Spiral-shaped lithium batteries are generally used for high discharge current applications such as power sources for cameras.

It is essential to reduce the internal resistance as much as possible. Therefore, it is necessary to increase the electrode area and to make the separator portion thinner, and for example, a porous film obtained by stretching a polypropylene film is used as the separator.

By making the separator thinner, the resistance of the separator portion becomes smaller, and the size of the spiral electrode plate group housed in the same battery container becomes longer, increasing the electrode area, which is effective in increasing the discharge current.

However, the above battery manufacturing method has various problems. For example, a method is adopted in which one of the electrode plates is wrapped in a bag-like separator, but in this case, the separator is distorted between the inside and outside of the electrode plate. Since the adhesion between the separator and the electrode plates is poor, the separator is wrinkled, increasing the distance between the electrode plates, and air bubbles tend to accumulate, increasing the internal resistance of the battery.

Further, during the winding operation, the film is easily damaged due to reasons such as the anisotropy in the strength of the separator film and the uneven surface of the positive electrode mixture sheet, resulting in internal short circuits.

Various methods have already been disclosed to solve these problems, including the following.

JP-A No. 60-41772 (Make the long direction of the micropores in the separator film match the winding direction of the spiral battery)
, JP-A No. 60-79672 (fixing the ends of the separator to the current collector by welding), JP-A No. 61-74267 (using a reinforcing sheet for the separator), JP-A No. 82-139
No. 253 (in which the particle size of Mn02 is made small) and JP-A-63-164170 (in which the Mn02 particles are rolled using a pressing plate) are known. However, the improvement achieved by these methods is not sufficient, and the process becomes complicated.

Therefore, an object of the present invention is to provide a lithium battery with excellent performance and a simple method for manufacturing the same by improving the configuration of the conventional spiral-wound lithium battery and the method for manufacturing the same. .

[Means for Solving the Problems] The present invention provides a spiral battery in which band-shaped positive and negative electrode plates are wound with a separator in between, and a solid material serving as a separator and an electrolyte is formed on both sides of one electrode plate. The above object has been achieved by proposing a cylindrical lithium battery that is created by integrally forming a polymer electrolyte film, then stacking the other electrode plate and winding it in a spiral shape. It is.

According to the present invention, the structure of the battery is such that one electrode plate and a separator made of a solid polymer electrolyte film are integrally molded and then wound.

Problems such as wrinkles caused by the porous film of conventional separators are eliminated. Moreover, the method of integrally forming the solid polymer electrolyte and the electrode plate is also simple, and a cylindrical spiral lithium battery with excellent performance can be manufactured.

The solid polymer electrolyte in the present invention is composed of a lithium ion salt and a polymer having ion conductivity. Lithium ion salts include LiCJ104 and LiBF4.
, LiAsF6.

Examples include LiPF6, Li5CN, LiJL, LLBr, etc.

Examples of polymers with ion conductivity include polymers such as polyethylene oxide, polypropylene oxide, polyethylene sulfide, poly-β-propiolactone, and polyethylene succinate, or polymers made by polymerizing polyethylene glycol methacrylate, polyethylene glycol acrylate, etc. , polymers obtained by crosslinking polyethylene oxide-added glycerin with diisocyanate, polysiloxanes and polyphosphazenes having polyethylene oxide in their side chains, and crosslinked polymers thereof, etc.
Examples include:

Furthermore, in order to improve the mechanical properties of these polymers, thermoplastic elastomers such as polyurethane, high molecular weight polyethylene oxide, etc. may be mixed.
In order to increase the ionic conductivity of the above organic polymer,
Propylene carbonate, acetonitrile, r-butyrolactone, ethylene carbonate, tetrahydrofuran, dimethoxyethane, dimethyl sulfoxide within a range that does not impair the mechanical strength of the solid polymer electrolyte.

Organic solvents known as components of liquid electrolytes such as dioxolane and sulfolane, or liquid substances such as low molecular weight polyethylene glycol, polypropylene glycol, and copolymers thereof may be contained.

Alternatively, a liquid electrolyte in which the lithium ion salt is dissolved in the above organic solvent and a gelling agent made of a polymer such as polyalkyl methacrylate, or a polymerizable monomer and/or macromer, a non-aqueous A liquid mixture consisting of a solvent and a lithium ion salt that is gelled by heat or irradiation with actinic rays can also be used.

Examples of monomers and macromers that can be polymerized with actinic rays include acrylic esters and methacrylic esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate,
Aryl acrylate, methyl methacrylate, ethyl methacrylate.

Propyl methacrylate, butyl methacrylate, aryl methacrylate, 2-hydroxyethyl acrylate, 2
-hydroxyethyl methacrylate), 1,13-hexanediol acrylate, 1,6-hexanediol methacrylate, and the like.

Further, examples of acryloyl-modified polyalkylene oxide include diethylene glycol monoacrylate and diethylene glycol methacrylate.

Triethylene glycol monoacrylate, polyethylene glycol monoacrylate, methoxytetraethylene glycol monoacrylate.

Phenoxytetraethylene glycol monoacrylate, triethylene glycol monomethacrylate, polyethylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, polyethylene glycol dimethacrylate, triethylene glycol trimethylol propane triacrylate, etc., or the ethylene glycol structure is Those with a propylene glycol structure can also be used.

Alternatively, it is also possible to use a structure in which the ethylene glycol structure is changed to a random or block copolymer structure of ethylene oxide and propylene oxide units.

Alternatively, reactive oligomers or polymers used in UV curing paints can also be used. Examples include unsaturated acrylate prepolymers obtained by modifying unsaturated polyesters with acrylic acid, acrylic-modified siloxanes, and acrylic-modified polyurethane prepolymers. Two or more of these can be used in combination.

In addition to these, a small amount of an elastomer such as polyurethane or a polymer compound such as high-molecular polyethylene oxide may be added in order to improve the mechanical strength of the solid polymer electrolyte.

The content of the lithium ion salt is 0.01 to 50 wt%, preferably 0.1 to 50 wt%, based on the ion conductive polymer compound and/or organic solvent.
A range of 30 wt % is preferable. If the lithium ion content is too large, the excess lithium ion salt will not dissociate and become a solid solution, but will simply coexist, resulting in a decrease in ionic conductivity.

Furthermore, if the content is too low, the number of dissociated lithium ions, which are charge carriers, will decrease, resulting in a decrease in ionic conductivity.

Moreover, 4! of the above-mentioned ion-conductive solid polymer electrolyte film! ! Electronic insulating fine powder such as silica, alumina, and zirconia may be appropriately mixed in order to improve mechanical strength, particularly to prevent short circuits caused by film damage due to compression during battery stacking.

on both sides of one electrode plate of the lithium battery of the present invention.

The method for forming the above-mentioned ion-conductive solid polymer electrolyte film is to make a homogeneous solution of the above-mentioned polymer compound and lithium ion salt in both solvents, and apply it to both sides of the electrode plate to a uniform thickness. There is also a method of forming a film by removing the solvent after coating, and a method of coating a liquid composition consisting of a polyethylene macromer etc. and a lithium ion salt.
There is a method of forming a film by increasing the molecular weight or crosslinking and curing by heating or irradiation with actinic rays.

Further, the application method includes, for example, a method of dipping in the above-mentioned liquid composition or solution, or a method such as roller coating, a doctor blade, an eight-coder, a silk screen, or a spin cord to obtain a uniform thickness. A film of ion-conducting solid polymer electrolyte is then applied.

Both sides of the electrode plate are coated and formed integrally.

Examples of the negative electrode active material in the present invention include lithium and lithium alloys, such as alloys of lithium and aluminum, mercury, zinc, and the like. These sheet-like materials can be used as current collectors by being crimped onto a stainless steel mesh, for example.

In addition, as the positive electrode active material, for example, manganese dioxide,
Molybdenum trioxide, vanadium pentoxide.

Titanium or niobium sulfide, chromium oxide.

Materials known as positive electrode active materials for lithium batteries, such as copper oxide, can be used. For use as a positive electrode, these active materials are mixed with a conductive agent such as graphite, and if necessary, a binder such as polytetrafluoroethylene or the solid polymer electrolyte described above, and formed into a sheet. It will be done. Also, if necessary,
In order to maintain the shape of the sheet, a stainless steel mesh or the like may be used as a retaining agent inside.

This positive electrode sheet is overlaid with the integrally molded negative electrode sheet coated with the solid polymer electrolyte, wound into a spiral shape using a current collector rod with a lid as a core rod, placed in a cylindrical battery case, and poured with electrolyte. The battery of the present invention is produced by draining and sealing.

Examples of the cylindrical spiral type lithium battery of the present invention will be described in detail below.

[Examples and Comparative Examples] Example 1 The negative electrode plate was made by pressing lithium foil onto a stainless steel mesh (current collector, body), and polyethylene glycol monomethacrylate (manufactured by Shin Nakamura Chemical, M-90G) was coated on both sides of the negative electrode plate. 2
53g<Okibe, 75 parts by weight of polyethylene glycol dimethacrylate (manufactured by Shin Nakamura Chemical, 9G), 100 parts by weight of dimethoxypolyethylene glycol (manufactured by Asahi Denka, 0LE-400, average molecular weight 400), lithium perchlorate (Li
C 0/1) 10 parts by weight and 2.2 parts as a sensitizer
-dimethoxy-2-phenylacetophenone 0.1f4
The mixed liquid composition was applied and irradiated with a UV lamp to form a coating film of solid polymer electrolyte about 20 gm thick.

As a positive electrode mixture, 75 parts by weight of manganese dioxide, 10 parts by weight of acetylene black, and 15 parts by weight of a polymer having the same composition as the electrolyte membrane were mixed, and this was mixed into a positive electrode using a stainless wire mesh as a reinforcing material. I created a sheet.

The above positive electrode sheet was laminated and wound around the negative electrode plate coated with the above solid polymer electrolyte membrane, and as an electrolyte, 1.0% LiClO4 was added to an equal volume mixture of propylene carbonate and 1,2-dimethoxyethane. Put the 0M/L solution into a cylindrical battery case and make it into a cylindrical battery case with a diameter of 11.8m.
A battery with a height of 10.8 mm and a height of 10.8 mm was created.

Although 10 pieces were made, there were no problems such as wrinkles in the electrolyte membrane of the separator. The discharge characteristics were measured at 20° C. with a constant resistance of 1.5Ω.

A battery capacity of 180 mAh was obtained.

Example 2 In Example 1, as raw materials for the solid polymer electrolyte, 100 parts by weight of polyethylene glycol dimethacrylate (manufactured by Shin Nakamura Chemical, 4G), 200 parts by weight of a propylene carbonate solution in which LiClO4 was dissolved in IM/L, and A battery was produced in the same manner as in Example 1, except that a liquid composition containing 0.1 part by weight of 2,2-dimethoxy-2-phenylacetophenone was used as the sensitizer. The battery capacity was 195mAh.

Example 3 A battery was produced in the same manner as in Example 2, except that 30 parts by weight of micro glass beads (GB 210 manufactured by Toshiba Ballotini) were mixed into the raw material liquid composition. The battery capacity was 193mAh.

Comparative Example 1 In Example 1, a porous polypropylene film (manufactured by Hoechst Celanese, Duraguard) was used as a separator to wrap the positive electrode sheet.

Similar batteries were made by impregnating them with electrolyte, but three of the 10 batteries encountered problems during the lamination process, such as wrinkles and breakage of the separator.

[Effects of the Invention] According to the present invention, the structure of the battery is such that one electrode plate and a separator made of a solid polymer electrolyte film are integrally molded and then wound. This eliminates problems such as wrinkles.

Moreover, the method of integrally forming the solid polymer electrolyte and the electrode plate is also simple, and a cylindrical spiral lithium battery with excellent performance can be manufactured.

Patent applicant: Ube Industries Co., Ltd.

Claims (2)

[Claims] (1) A spiral battery in which band-shaped positive and negative electrode plates are wound with a separator in between, and a solid polymer electrolyte film that serves as the separator and electrolyte is integrally formed on both sides of one electrode plate. Later, the cylindrical spiral type lithium battery was created by stacking the other electrode plate and winding it in a spiral shape. (2) In the method of integrally forming the solid polymer electrolyte film, a monomer polymerizable with actinic rays and/or
The cylindrical spiral lithium battery according to claim 1, wherein a liquid composition comprising a macromer and a lithium ion salt is applied to an electrode plate and irradiated with actinic rays.