JP2527838Y2 - Cylindrical polymer battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cylindrical polymer battery.

[Prior art] Polymer materials such as polyaniline take in and release electrolyte ions by an electrochemically reversible Redox reaction. Secondary batteries using this principle have attracted attention in recent years. (JP-A-56-136469). These polymer materials form a special complex by incorporating an electrolyte cation or an anion therein, and a complex with an anion is particularly stable. This so-called doping is more stable in a non-aqueous electrolyte and is therefore excellent as a positive electrode for a non-aqueous secondary battery. Since a high voltage can be obtained by using an alkali metal such as Li or Na as the negative electrode active material, it is expected to realize a high energy density as well as a weight reduction by the polymer.

[Problem to be Solved by the Invention] However, when a conductive polymer is used as an active material of a secondary battery, there are problems such as a short cycle life and a large self-discharge.

Further, although the voltage is high, the energy density is equal to or lower than that of the current practical use.

As described above, for practical use as a secondary battery,
Improvements in doping, anodes, electrolytes, packaging must be considered. In particular, for the package, there are many problems to be solved by the electrode molding method based on the properties of the active material so as to increase the mounting density of the active material in the container. Also, as compared with conventional batteries, the active material is an organic compound, so the shape is complex granular or fibrous, and applied to a current collecting matrix.
Alternatively, it is formed by a method of impregnating and holding or a method of polymerizing a conductive polymer directly on a current collector such as polyaniline. However, when spirally winding electrodes and the like to form a spirally wound cylindrical battery by laminating the positive electrode, the separator, and the negative electrode, the positive electrode active material is uniformly formed on the current collector as shown in FIG. In the case of spiraling, when spirally wound, it is pulled inward and outward, and a compressive force is generated, the density decreases on the outside,
The bonding force of the active material is weakened, cracks and cracks are generated, the density is increased inside, the bonding force with the current collector is weakened, and peeling is caused (FIG. 2). This was causing a short circuit.

Therefore, an object of the present invention is to provide a cylindrical polymer battery which does not cause the above-described problems even when formed in a spiral shape.

[Means for Solving the Problems] As a result of intensive studies to solve the problems, the present inventors have found that it is effective to stack a positive electrode, a separator, and a negative electrode and form them into a rectangular spiral shape. It was found and led to the present invention.

That is, in the present invention, in a battery having a positive electrode, a negative electrode and an electrolyte as main components, a positive electrode, a separator and a negative electrode in which a positive electrode active material is formed in stripes on a positive electrode current collector are stacked, and the positive electrode active material is present. This is a tubular polymer battery in which a portion not formed is bent to form a square spiral.

At present, secondary batteries are aiming for higher energy and longer life, and the amount of active material used is further increasing. Therefore, the thickness of the active material on the current collector is also increasing, and the tendency of the polymer positive electrode active material to crack is further increased. However, this problem can be solved at once by the present invention. .

According to the present invention, the positive electrode, the separator, the negative electrode laminate,
When spirally wound, it is wound in a straight line, that is, in a square spiral shape, but if the amount of active material for high density energy batteries is large, there is no positive electrode active material at the corner, Is also formed in a very small amount. That is, for example, they are formed in a stripe shape as shown in FIG. By forming in this way, the angle portion due to bending is applied to the portion having no active material amount, so that the positive electrode active material can be wound without any influence as shown in FIGS. it can.

In the present invention, another advantage of forming the positive electrode active material in a strip shape as described above is that a hole through which the electrolyte passes is formed in a gap between the positive electrode materials at the corners. As a result, a sufficient amount of the electrolytic solution reaches all the positive electrode active materials.

Examples of the positive electrode active material used in the present invention include conductive polymer materials such as graphite and polyaniline, polythiophene, polyfuran, polypyrrole, polyphenylene sulfide, polyphenylene oxide, and polyacetylene that can be doped with an anion. ,
The positive electrode active material can be selected not only from a conductive polymer, but also from those usually used as a positive electrode of a lithium secondary battery.
For example, TiO ₂ , Cr ₂ O ₃ , V ₂ O ₅ , V ₆ O ₁₃ , MnO ₂ , CuO, MnO ₃ , C
u ₅ V ₂ O metal oxide such as _{15, TiS 2, FeS, CuCoS} 4, MoS metal sulfides such as _3, NbSe, may be used, such as metal selenides such as VSe _2, conductive Among these The conductive polymer is particularly excellent in compatibility with the electrode of the present invention, and when a conductive polymer material is used for the positive electrode, polyanilines can be most preferably used.

Representative examples of aniline polymers include aniline,
2-methoxyaniline, 3-methoxyaniline, 2,5-
Polymers such as dimethoxyaniline, 2,6-dimethylaniline, N-methylaniline, N-ethylaniline, para-phenylenediamine, ortho-phenylenediamine, para-diphenylamine, 1-aminonaphthalene, 1-aminopyrene and the like. However, among these, the most preferred is a polymer of aniline.

Examples of the sheet forming these polymers include a sheet obtained by subjecting a metal sheet such as stainless steel, iron, titanium, and aluminum to an ex-band processing, a sheet cut into a net shape, or a punched sheet. Furthermore, the metal
A foil of 50 μm or less can be used. It is also possible to use a foamed metal or a porous sintered powder of the metal.

Graphite sheets and carbon fiber cloths can also be used.

As a method of forming the positive electrode active material on the sheet, first, the sheet is masked only in a necessary portion in a strip shape, and then the electrolytic polymerization method, the extrusion molding method, and the polymer are applied in a sheet shape together with a binder. It is good. The thickness of the amount of the active material is preferably from 0.3 mm to 2.0 mm, and when the thickness is 0.3 mm or less, a circular spiral is possible. When the thickness is 2.0 mm or more, the effect of the square spiral is small. Preferably it is 0.5 mm or more and 1.5 mm or less.

As a negative electrode active material, a binary system or more containing alkali metals such as Li, Na, and K, and alkali metals such as Li-Al, Li-Si, Li-Se, Li-Pb, and Li-Al-Mg Metal. These may be used in the form of a sheet as they are, or may be used in the form of a powder, a sintered sheet or a paste, and basically applied. Further, the above metal or alloy may be melted and impregnated into a porous substrate before use. Further, the above-mentioned metals and alloys may be used by being deposited on a substrate by vapor deposition or sputtering. In addition, when the amount of the negative electrode active material is large, a favorable cylindrical shape is obtained by forming the negative electrode active material in the same manner as the positive electrode.

Examples of the separator include a microporous polypropylene sheet, a nonwoven fabric of glass, and an ion-selective membrane.

As the electrolyte, anions doped into the polymer of anions, for example, halide anions of the Vb group element such as PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , SbCl ₆ ⁻ , BF ₄ ⁻ , and AlCl ₄ ⁻ halogenated anions of group IIIb elements such as, I ^-, Br ^-, C
l ^- alkali metal salts or alkyl ammonium compound containing halogen anion, such as and the like. These salts vary depending on the type of the solvent to be dissolved, but are preferably used in a type of about 0.1 M to 5 M. Also, two or more kinds may be mixed and used.

As the solvent, a non-aqueous electrolytic solution which is aprotic, has a high dielectric constant, and has a wide liquid temperature range around room temperature is desirable.

[Examples] The present invention will be described in more detail with reference to the following examples.

A circular hole having a diameter of 100 μm was formed in a sheet-like stainless steel having a thickness of 20 μm as a current collector of the positive electrode by a chemical etching method in a size of 1 cm ^2.
After the sheet was provided at a ratio of 100 pieces, the sheet surface was roughened by a plast treatment.

Example 1 A 1 mm Teflon tape was attached to the current collector 40 mm wide and 120 mm long at intervals of 4 mm. And 0.5M aniline, 1.5N
H ₂ SO ₄ was dissolved in water, and polyaniline was formed on the current collector with a thickness of 1.5 mm on one side, a total of 3 mm in thickness, by a 0.75 V vs S. CE constant potential polymerization method. Then, when the Teflon tape was peeled off, the SUS surface having a width of about 1 mm was exposed at intervals of 4 mm. This was passed through a rolling roll several times and wound with a rectangular spiral together with Tonentapirus and 80 μm-thick lithium, which had been sufficiently immersed in the electrolyte, and was smoothly mounted on the battery can.
A capacity of 7.5 mAh / g was obtained.

Example 2 A 1 mm Teflon tape was attached to the current collector 40 mm wide and 160 mm long at 8 mm intervals. And 0.1M pyrrole, 0.05
M sodium paratoluenesulfonate was dissolved in acetonitrile and subjected to 5 V constant potential electrolysis to form 1 mm thick polypyrrole on one side and 2 mm on both sides. After peeling off the Teflon tape, this positive electrode sheet, a glass fiber non-woven fabric sufficiently immersed in electrolyte and 100μm lithium-20wt% aluminum are wound in a circular spiral, and can be smoothly mounted on a φ16 battery can. As a result, a capacity of 90 mAh / g was obtained.

Example 3 The same method as in Example 1 was applied to the current collector 40 mm in width and 130 mm in length.
A μm thick polyaniline was prepared. And 1 at 4mm intervals
After masking with a tape having a width of mm, a chemically polymerized polyaniline and a binder were mixed, formed on this positive electrode to a thickness of 1.5 mm and a total thickness of 3 mm, and the mask was peeled off to prepare a positive electrode sheet. This is fully soaked with electrolyte and tonentapirus and 100μ
m-thick lithium was wound into a square shape. Then, when mounted on a battery can, a capacity of 107.8 mAh / g was obtained.

Example 4 A Teflon tape having a width of 1 mm was attached to the current collector at a width of 40 mm and a length of 200 mm at intervals of 8 mm. Then, the chemically polymerized polyaniline and the binder were mixed to form a total of 1 mm on the sheet in 0.5 mm increments. This was made into a glass fiber non-woven fabric sufficiently immersed in an electrolytic solution and 80 μm of lithium-20 wt% aluminum in a rectangular spiral, and mounted on a battery can to obtain a capacity of 125 mAh / g.

Comparative Example 1 Polyaniline was formed to a thickness of 1.5 mm on one side and a thickness of 3 mm on both sides with the current collector width of 40 mm and length of 100 mm by the method of Example 1 to obtain a positive electrode sheet. Separator fully soaked with electrolyte and 80
A circular spiral with lithium having a thickness of μm was sealed in a battery can, and a charge / discharge test was performed. As a result, only 105 mAh / g was obtained.

Comparative Example 2 Polypyrrole of 2 mm was formed on both sides of the current collector with a width of 40 mm and a length of 160 mm in the same manner as in Example 2 to obtain a positive electrode sheet. When this was formed into a circular spiral together with the separator and the negative electrode through a rolling roll, a phenomenon that polypyrrole was peeled off from the current collector near the center occurred. Capacity is also 61mAh / g
I could only get it.

Comparative Example 3 The current collector was 40 μm wide and 130 mm long and 20 μm as in Example 3.
A chemically polymerized polyaniline having a total thickness of 3 mm was formed on the m-thick polyaniline with a binder. However, in the case of a circular spiral, peeling and peeling occurred, and a capacity of only 88 mAh / g was obtained.

COMPARATIVE EXAMPLE 4 A chemically polymerized polyaniline was formed to a thickness of 3 mm with a binder in a thickness of 1.5 mm each with a binder in a width of the current collector of 40 mm and a length of 160 mm.
When a test was conducted by forming a spiral shape along with the μm sheet into a battery can and mounting it on a battery can, only 74 mAh / g was obtained.

[Effects of the Invention] As described above, according to the present invention, even if the laminate of the positive electrode, the separator, and the negative electrode is spirally wound, it is possible to prevent the positive electrode active material from being cracked, cracked, and peeled off. Thus, a cylindrical polymer battery with improved performance can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a layer configuration of a conventional positive electrode, FIG. 2 is a diagram illustrating a state where peeling or the like occurs in an active material when the conventional positive electrode of FIG. 1 is wound, FIG. Fig. 3b is a view for explaining the layer structure of the positive electrode used in the cylindrical polymer battery of the present invention, Figs. 4a and 4b and Figs. 5a and 5b.
FIG. 3 is a view for explaining a state in which the positive electrode shown in FIGS. 3A and 3B is wound.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kouri Kimura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-56-136469 (JP, A) 37-165 (JP, Y1)

Claims (1)

(57) [Scope of request for utility model registration] In a battery comprising a positive electrode, a negative electrode and an electrolyte as main components, a positive electrode active material is formed by laminating a positive electrode, a separator and a negative electrode formed on a positive electrode current collector in stripes. A cylindrical polymer battery in which the part that has not been bent is bent into a rectangular spiral shape.