JPH10261420A - Organic electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electrolyte battery having a spiral electrode group, and to prevent an insulation failure due to winding shifts of an electrode, a resistance welding failure between a negative electrode current collecting plate and an armored can. SOLUTION: An organic electrolyte battery has a spiral electrode group 3 formed by winding a sheet-shaped positive electrode plate and a sheet-shaped negative electrode plate made of alkaline metal or its alloys through the medium of a separator. In this case, a steel plate having a Vickers hardness HV of 120 or less includes a nickel. layer on its surface, and is used as a negative electrode current collecting plate 7 for making an electrical connection between a nagative electrode plate 6 and an armored can 1 serving as a nagative electrode terminal. By using the steel plate having such hardness, the flexibility of the negative electrode plate 6 with the negative electrode current collecting plate 7 pressed thereagainst is improved to prevent winding shifts of an electrode and a resistance welding failure between it and the armored can 1. The surface of the steel plate forms the nickel layer, thereby lowering contact resistance and conduction resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electrolyte battery provided with a spiral electrode, and more particularly, to the above-mentioned organic electrolyte battery in which the material of a negative electrode current collector is improved.

[0002]

2. Description of the Related Art In recent years, as a non-aqueous electrolyte battery, an organic electrolyte battery using an alkali metal such as lithium or sodium as a negative electrode has attracted attention as a battery having high voltage, high energy density and long-term reliability. For example, a lithium temporary battery using manganese dioxide MnO ₂ , fluorocarbon (CF ₂ ) _n, or the like as a positive electrode active material is frequently used as a power source for cameras, calculators, watches, and the like, and as a backup battery for memory. Particularly in a cylindrical organic electrolyte battery, a demand for a large current as a power source for a camera or the like is increasing. Therefore, in order to obtain a large current, this type of battery uses an electrode group having a structure in which a sheet-like positive electrode and a negative electrode are spirally wound via a separator to increase the reaction area of the electrode.

[0003] In this case, as a method for collecting the sheet-like electrode, the positive electrode active material itself has low conductivity on the positive electrode side, and therefore, as shown in FIG. Such a metal current collector is arranged, and a part of the metal current collector is electrically connected to the positive electrode terminal via a current collecting lead.

On the negative electrode side, since an alkali metal such as lithium is used as an active material, it has high conductivity itself, so that it is not necessary to arrange a current collector on the entire sheet.
Further, in order to reduce the volume of the current collector as much as possible and increase the amount of the active material, that is, the electric capacity of the negative electrode, as shown in FIG. 3, a part of the sheet-shaped negative electrode was formed into an L-shape or an I-shape. One end of a negative electrode current collector made of a thin metal plate was crimped, and the other end was used as a negative electrode lead by resistance welding to the inner surface of the outer can to make a conductive connection. Conventionally, as a material of the negative electrode current collector plate, a thin plate of pure nickel has been used in view of corrosion resistance and conductivity.

[0005]

However, when a thin plate made of pure nickel is used as the negative electrode current collector plate as in the above-mentioned conventional example, there are the following problems. Normally, a pure nickel thin plate has a Vickers hardness of about Hv180 to 200, and has a higher bending strength and a stronger spring property as compared with a negative electrode active material composed of an alkali metal having extremely high flexibility. Therefore, the bending strength of the negative electrode plate to which the negative electrode current collector plate is crimped is not uniform. There is a problem that insulation failure occurs.

Further, when one end of the negative electrode current collector protruding from the wound electrode group is bent inward in the end face of the electrode group via an insulating plate made of resin, and inserted into the outer can, However, there is a problem in that it is difficult to bend and poor insertion into the outer can or poor welding with the outer can due to deformation of the current collector plate occurs.

Conventionally, nickel-plated steel sheets have been used as the material of the outer can in terms of workability and corrosion resistance. On the other hand, pure nickel used for the negative electrode current collector plate has low electric resistance of itself, and it is difficult to perform resistance welding. Therefore, when resistance welding is performed between the outer can and the negative electrode current collector plate, the welding strength becomes unstable, the variation in the internal resistance of the battery due to the occurrence of poor welding increases, and further, the problem of poor performance due to this occurs. there were.

The present invention has been made in view of such circumstances, and has as its object to solve the above-mentioned problems, namely, insulation failure due to electrode winding deviation, resistance welding failure between the current collector plate and the outer can, and the like. It is an object of the present invention to provide a highly reliable organic electrolyte battery with small variations in battery performance, and to improve the efficiency of battery assembly work.

[0009]

In order to achieve the above-mentioned object, the present invention relates to an organic electrolyte battery in which a negative electrode current collector is improved, comprising a sheet-shaped positive electrode plate and an alkali metal or an alloy thereof. In an organic electrolyte battery having a spiral electrode group formed by winding a sheet-shaped negative electrode plate made of a separator through a separator, a negative electrode current collector plate for electrically connecting the negative electrode plate and an outer can serving also as a negative electrode terminal has a surface. A Vickers hardness Hv 120 or less having a nickel layer.

Since the organic electrolyte battery of the present invention uses a steel plate having a Vickers hardness of Hv 120 or less as the negative electrode current collector, the negative electrode plate to which the negative electrode current collector has been pressed is more flexible than before. Therefore, winding deviation during battery assembly is prevented, and bending of the negative electrode lead is also improved, so that work efficiency is improved. In addition, since the material of the negative electrode current collector plate is the same as the material of the outer can, the variation in the strength of resistance welding between the negative electrode lead and the bottom of the outer can is suppressed, and poor welding is eliminated. Furthermore, since the surface of the negative electrode current collector plate has a nickel layer, the contact resistance with the alkali metal as the negative electrode active material and the conductive resistance of the lead itself can be suppressed low, and the variation in battery performance can be suppressed. Furthermore, since a steel sheet having a nickel layer on its surface is less expensive than conventional pure nickel, the cost of the battery can be reduced.

As the positive electrode of the organic electrolyte battery of the present invention,
For example, a material in which manganese dioxide, fluorocarbon, or the like, which is an active material, is applied to a plate surface of an expanded metal or a punched metal, which is a positive electrode current collector, may be used. Examples of the negative electrode include metallic lithium foil, sodium foil, and lithium aluminum alloy foil.

Examples of the electrolytic solution usable in the present invention include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyl lactone,
Sulfolane, acetonitrile, 1,2-dimethoxyethane, 1,3-dimethoxypropane, dimethyl ether,
Tetrahydrofuran, 2-methyltetrahydrofuran,
Lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (Non-aqueous solvent) comprising at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propionate L
iPF _6), lithium borofluoride (LiBF _4), lithium hexafluoroarsenate (LiAsF _6), lithium trifluoromethanesulfonate (LiCF ₃ SO _3), lithium trifluoromethanesulfonate imide salt (LiN (C
Lithium salt (electrolyte) such as F ₃ SO ₃ ) ₂ )
An organic electrolytic solution in which about 1.5 mol / l is dissolved is generally mentioned. Instead of the non-aqueous electrolyte, an ion-conductive solid electrolyte such as a polymer solid electrolyte in which a lithium salt is combined with a polymer compound can be used. The material of the negative electrode current collector plate may have a nickel layer on the surface, for example, a nickel-plated steel plate,
A nickel-clad steel plate or the like can be used.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment) FIG. 1 is a cross-sectional view showing a main configuration of an organic electrolyte battery (CR123A) according to an embodiment of the present invention.
90 parts by weight of MnO ₂ as a positive electrode active material, 5 parts by weight of graphite powder as a conductive agent, and 5 parts by weight (solid content) of an aqueous PTFE dispersion as a binder were kneaded to form a positive electrode mixture, which was made of stainless steel. , And dried and rolled, cut into a predetermined shape, and dried again to obtain a sheet-shaped positive electrode plate 4.

Further, a lithium aluminum alloy (containing 0.1% by weight of aluminum) foil as a negative electrode active material is cut into a predetermined size, and a part of the foil is annealed to have a hardness of Hv120 and has a nickel layer on the surface. One end of a negative electrode current collector plate 7 made of a substantially L-shaped steel plate was pressure-bonded to form a sheet-shaped negative electrode plate 6. The steel plate used here had a thickness of 0.0
A 7 mm nickel-plated steel plate having a plating thickness of 3 to 6 μm was annealed at a temperature of 700 ° C. for 10 minutes. Annealing conditions are as follows: at a temperature of 500 to 900 ° C., 0.5 minutes to 36 hours.
The same effect can be obtained within the time range. If the temperature is lower than this range, good annealing cannot be performed, and if the temperature is higher than this range, nickel diffuses into iron and is not a pure nickel layer, so that the conductive resistance and contact with alkali metal which is a negative electrode active material are obtained. The resistance increases.

Next, the sheet-like positive electrode plate 4 and the sheet-like negative electrode plate 6 were spirally wound through a separator 12 made of a microporous film made of polypropylene to form an electrode group 3. The end of the negative electrode current collector 7 protruding from the end face in the direction perpendicular to the winding center axis of the electrode group 3 is connected to the electrode group 3
The electrode group 3 is bent inward through a resin insulating plate 8 disposed in parallel with the end face, and the end face of the electrode group 3 on the side of the negative electrode current collector plate from the open end of the exterior can 1 also serving as the negative electrode terminal is headed. And the inner bottom surface of the outer can 1 and the negative electrode current collector 7
Resistance welding was performed on the end portion at a portion 9 in FIG. After storing the electrode group 3 in the outer can 1 as described above, 1 mol / l of lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ) is dissolved in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane in an equal volume. A predetermined amount of the obtained organic electrolyte was injected, and the sealing body 2 was fixed by caulking at the open end of the outer can 1, thereby obtaining the organic electrolyte battery shown in FIG.

(Comparative Example 1) An organic electrolyte battery having the same configuration as that of Example 1 except that the material of the negative electrode current collector plate 7 was made of pure nickel having a hardness of Hv200, was used as Comparative Example 1.

(Comparative Example 2) An organic electrolyte battery having the same structure as that of the embodiment except that the material of the negative electrode current collector plate 7 was made of pure nickel having a hardness of Hv120 subjected to an annealing treatment was manufactured. And

(Comparative Example 3) An organic electrolyte battery having the same structure as that of the embodiment except that the material of the negative electrode current collector plate 7 was a cold-rolled nickel-plated steel plate having a hardness of Hv200 and not subjected to annealing treatment was manufactured. And Comparative Example 2.

(Comparative Example 4) An organic electrolyte battery having the same configuration as that of the embodiment except that the material of the negative electrode current collector plate 7 was a cold-rolled nickel-plated steel plate having a hardness of Hv150 and not subjected to annealing treatment was manufactured. And Comparative Example 4.

[0020] Each of the above-mentioned batteries was manufactured in a quantity of 1,000 pieces, and the winding slip insulation failure, the poor insertion of the current collector plate 7 into the outer can 1 due to insufficient bending, and the internal resistance of the fabricated batteries were examined. The results are shown in Table 1.

[0021]

[Table 1]

As can be seen from Table 1, when the battery had a hardness Hv of 120 or more (Comparative Examples 1, 3, and 4), the negative electrode current collector plate had high hardness and poor workability during battery assembly. Poor insulation or poor insertion into the outer can occurred. In addition, when pure nickel was used (Comparative Examples 1 and 2), the weldability between the negative electrode current collector plate and the outer can was poor, so that the variation in the internal resistance was extremely large. The average value of the internal resistance was the same regardless of whether pure nickel or a nickel-plated steel sheet was used. This is because iron, the base material of nickel-plated steel sheets, has a slightly lower electrical conductivity than nickel,
It has a nickel layer on the surface, and since the current mainly passes through the surface layer, it is considered that the influence of the base material does not occur.

In the embodiment of the present invention, if the thickness including the nickel layer of the steel sheet having the nickel layer used for the negative electrode current collector plate is in the range of 0.03 to 0.3 mm, the same effect can be obtained. If it is less than 0.03 mm, the bending strength is reduced and the bendability is improved, but the welding strength is reduced. On the other hand, when the thickness is 0.3 mm or more, the volume of the current collector plate itself increases and the volume efficiency of the battery decreases, and the workability of bending the terminal portion decreases due to an increase in bending strength.

Further, the thickness of the nickel layer is at least 0.5 μm, and at most 20% of the thickness of the steel sheet as the base material.
If it is less than this range, the electrical conductivity will be reduced and the corrosion resistance of the surface will be significantly reduced, and if it is more than this range, the strength of the nickel layer will be increased, and even if an annealing treatment is performed, the overall hardness will be reduced. Becomes Hv120 or more, and the effect of the present invention cannot be obtained.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the invention. In addition, the components of the positive electrode and the negative electrode and the components of the separator can be replaced with the already known positive electrode,
The same operation and effect can be obtained by adopting a configuration changed to a negative electrode, a separator, and the like.

[0026]

As described above, in the organic electrolyte battery according to the present invention, in order to improve the workability of the negative electrode current collector plate, when forming an electrode group, insulation failure due to winding deviation is eliminated, and furthermore, the exterior Work efficiency,
The productivity is improved, and the reliability is increased without any performance failure. Therefore, the organic electrolyte battery according to the present invention can be used as a power source corresponding to high reliability of portable electronic devices.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of an organic electrolyte battery according to an embodiment of the present invention.

FIG. 2 is a plan view of a sheet-like positive electrode plate of an organic electrolyte battery according to a conventional example and an example of the present invention.

FIG. 3 is a plan view of a sheet-shaped negative electrode plate of an organic electrolyte battery according to a conventional example and an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer can, 2 ... Sealing body, 3 ... Electrode group, 4 ... Sheet positive electrode plate, 5 ... Positive electrode lead, 6 ... Sheet negative electrode plate, 7 ... Negative current collector plate, 8 ... Insulating plate, 9 ... Resistance welding Part 10, negative electrode terminal, 11 positive electrode terminal, 12 separator, 13 positive electrode current collector, 14 positive electrode active material, 15 negative electrode active material.

Claims (2)

[Claims] 1. An organic electrolyte battery having a spirally wound electrode group in which a sheet-like positive electrode plate and a sheet-like negative electrode plate made of an alkali metal or an alloy thereof are wound with a separator interposed therebetween, wherein the negative electrode plate also serves as a negative electrode terminal. An organic electrolyte battery, wherein the negative electrode current collector plate electrically connected to the outer can is a steel plate having a nickel layer on the surface and having a Vickers hardness of Hv 120 or less. 2. The organic electrolyte battery according to claim 1, wherein a steel sheet having a nickel layer on the surface and having a Vickers hardness of Hv 120 or less is annealed.