JPS6158162A - Sealed battery - Google Patents

Abstract

PURPOSE:To prevent short at the edges of electrodes by covering edges of a cathode and an anode with edge of a separator when the cathode and anode are stacked with the separator interposed. CONSTITUTION:A sealed battery is formed in such a way that an electrode group is constructed by stacking an anode 1 comprising lithium and a cathode comprising manganese dioxide with a porous separator 3' interposed, or by spirally winding them. Edge of the separator 3' is formed in a L-shape and edges of the cathode 2 and anode 1 are covered by the edge of the separator 3' when they are stacked. Short caused by direct contact of edges of the cathode and anode can be prevented, and insulating plate necessary in the upper and lower parts of usual electrode group are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention constructs an electrode group by laminating a cathode, an anode, and a separator that insulates them. This is a sealed battery in which the electrode group is housed in a storage can, and the purpose is to prevent internal contact at the ends of the cathode and anode.

BACKGROUND ART In general, in a battery comprising an electrode group 4 consisting of a cathode 1, an anode 2, and a separator 3, the cathode 1 and the anode 2 are active materials, for example, lithium for the cathode 1 and 7 for the anode 2.
In batteries using carbonized graphite or manganese dioxide, the n-pole 1
A method is adopted in which the anode 2 and the anode 2 are sandwiched between the separators 3 to form an fRWI (laminated type), or a laminated structure is wound around a central axis to form an electrode group (winding type).

In addition, in a battery that uses lithium for the cathode 1 and active materials such as thionyl chloride, sulfuryl chloride, and sulfur dioxide gas for the anode 2 mixed with a solvent with good electrical conductivity, in addition to the electrode group 4, the cathode current collector 5 is placed in a storage case. There is a so-called inside-out type in which lithium, which is a cathode active material, is placed in the center of the storage can 6 so as to surround the anode 2 along the side wall of the storage can 6. However, in general, a laminated type or a wound type is often used, and it is well known that the inside-out type is particularly unsuitable for batteries intended for high rate discharge. In other words, when comparing the mounting density of the cell components in the same storage can between the laminated type, wound type and inside-out type, the laminated type and wound type can have a much higher density than the inside-out type. It's for a reason.

Electrode group 4 includes positive electrode 4@2, negative electrode 1 and porous separator 3
It has a structure in which the electrodes are stacked one on top of the other and wound around the central axis, and an anode current collector 7 and a cathode current collector 5 are attached to each electrode by a method that maintains good electrical contact. ing. After storing the lower insulating plate 8 at the bottom of the storage can 6 that stores the electrode group 4, the electrode group 4 is stored.
The upper part of the is covered with an upper insulating plate 9. Reference numeral 10 denotes a metal lid to which a cathode output terminal 112 insulated with an electrical insulator 11 such as ceramic or glass is attached. The anode current collector 7 is placed in the storage can 6, and the cathode current collector 5 is placed in the cathode output terminal 12.
After welding, the metal lid 10 is fitted into the storage can 6, and the joint 13 is laser welded to complete a completely sealed lithium-thionyl chloride battery.

Thionyl chloride, which is the active material of the anode, and lithium aluminum tetrachloride, which is added to improve ion conductivity, are mixed in advance in a predetermined amount, and before the metal lid 10 is fitted into the storage can 6 (the predetermined amount of the mixed solution is added to the electrode). Alternatively, the mixed solution can be supplied from the cathode output terminal 12 after the metal lid 1o is fitted into the storage can 6 and the joint 13 is laser welded using a pipe for the cathode output terminal 12. After supplying the mixed solution, a complete seal is maintained by sealing the tip of the pipe.

Problems to be Solved by the Invention Since the Y-layer type or winding disk is based on a structure in which the anode 2 and the cathode 1 are stacked one on top of the other with a porous separator 3 in between, the two electrodes cannot come into contact at the electrode ends. The disadvantage is that it often occurs. Causes of this include microscopic particles, so-called "backs", generated when cutting the electrodes to a specified size, and misalignment when the two electrodes and the separator are overlapped.

Short circuits account for approximately 30% of product defects in the battery manufacturing process.Although most of these types of sheets can be discovered during manufacturing, they can occur even if they are not present at the time of manufacture. If a battery is stored or discharged in an environment of -40°C to +70°C, it may fail due to the causes mentioned above.

FIG. 5 is an enlarged view of the upper end of electrode #4 and shows an ideal structure. However, in reality, the end portions often end up as shown in FIGS. 6a and 6b due to dimensional errors in the constituent members, manufacturing errors resulting therefrom, and tolerances of the assembly machine itself. That is, Fig. 6a is a structural diagram when the paris 14 is exposed at the end of the anode 2, and Fig. 6 is a structural diagram when the paris 14 is protruded from the end of the anode 2, and at the same time both electrodes and the porous separator are exposed. 3 is a structural diagram in the case where a winding misalignment occurs.

In FIGS. 6a and 6b, when stress is applied to the porous separator 3 in the thickness direction and the porous separator 3 is deformed, the ends of the anode 2 and the cathode 1 come into contact, resulting in an electrical short circuit. If the short-circuit condition continues, the temperature inside the battery will rise abnormally, leading to burnout of the constituent members, an increase in the internal pressure of the storage can 6, and a direct reaction between the cathode active material and the anode active material due to melting of lithium, which may lead to an explosion.

One way to solve the problem is to cover the end of the anode or cathode with the end face of the separator of the electrode group.

Preventing internal contact at the ends of the working cathode and anode
are stacked on top of each other with a porous separator 3 in between, and are wound around a central axis 9 to form an electrode group 4. Compared to the conventional battery structure diagram shown in FIG. 4, there is no upper insulating plate 9 and lower insulating plate 8. In order to explain this (2, Fig. 2 (a partial cross-sectional view of the end of the two electrode groups 4 is shown), the end of the porous separator 3' is designed to cover the end of the anode 2 or the cathode 1. It has been processed into an L-shape.

Therefore, the internal short circuit caused by direct contact between the ends ζ2 of the anode 2 and the cathode 1 can be eliminated, and as shown in FIG.
In the conventional battery, an upper insulating plate 9 and a lower insulating plate 8 are required at the upper and lower parts of the electrode group 4, respectively, but in the embodiment of the present invention, the L-shaped part of the porous separator 3' is used as the upper insulating plate. Since it has the roles of the plate 9 and the lower insulating plate 8, the number of components can be reduced. Figure 3 shows a cross section of the end of the porous separator 3' after various treatments.
Possible shapes include an L-shape, an S-shape, and a U-shape, but the porous separator 3' can be easily processed into such a shape. It is easily possible to overlap the anode 2 and the cathode 1, to laminate a large number of them, and to wind the overlapped structure using conventional manufacturing processes.

As an example, a rolled-up battery is shown, but it goes without saying that the present invention can also be applied to a rectangular battery using flat plate electrodes.

Effects of the Invention As described above, according to the present invention, 7i! It is possible to eliminate short circuits at the ends of the electrodes within the electrode group, and it also eliminates the need for an upper insulating plate and a lower insulating plate, which is of great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the sealed battery of the present invention, FIG. 2 is an enlarged view of the upper end of the electrode group according to the present invention, and FIG. 3 is a porous separator used in the present invention: a figure-8 porous separator;
C indicates a U-shaped porous separator, respectively. Fig. 4 is a cross-sectional view of a conventional lithium-thionyl chloride battery, Fig. 5 is an enlarged view of the same at the upper end of the electrode group, and Fig. 6 shows the relationship between the electrodes and the porous separator in the same electrode group. In the explanatory drawings, a shows a state in which there is a hole at the end of the anode, and b
1 and 2 show cases in which pars appears at the end of the anode and misalignment occurs between the electrode and the porous separator. 1 is a cathode, 2 is an anode, 3 is a porous separator, 4 is an electrode group, 6 is a storage can

Claims (1)

[Claims] 1. A sealed battery in which an electrode group is housed in a storage can, characterized in that an end of a separator of the electrode group covers an end of an anode or a cathode of the electrode group.