JPH054205Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of Industrial Application The present invention relates to a battery in which at least one of the electrode plates has an electrode body formed by spirally winding positive and negative electrode plates each having a core body through a separator. It is something.

B. Prior Art Generally, in order to improve the high-rate characteristics of a battery, a spiral electrode structure is used to increase the facing area of the positive and negative electrode plates. A battery with such a spiral electrode body is convenient for extracting a large current, but on the other hand, if an external short circuit occurs, the temperature of the battery will rise due to the heat of the current, causing the separator to melt. This may cause an internal short circuit, and the battery temperature may further rise, causing the electrolyte to evaporate or decompose into gas, resulting in an increase in battery internal pressure, which may cause the battery to explode or catch fire. In particular, lithium batteries that use active lithium as a negative electrode active material have a high risk of ignition.

Therefore, in order to ensure safety in the event of an external short circuit,
For example, as disclosed in JP-A No. 60-23954, a microporous membrane separator is used to prevent internal short circuits by melting the separator and forming an insulating film when an external short circuit occurs, or to prevent internal short circuits in assembled batteries. incorporates a PTC element to ensure safety.

However, the above-mentioned configuration is not effective in the case of an internal short circuit caused by the battery being deformed by mechanical external force, such as when the battery is dropped, and the core of one plate is pushed into the other plate. .

C. Problems to be solved by the invention The invention aims to suppress the occurrence of internal short circuits caused by deformation of the battery due to external mechanical force.

D. Means for solving the problem A porous metal plate is used as the core of the electrode plate, which has directional breaking strength and which breaks in one direction when external force is applied to the battery.

E. Effect When the battery is deformed by external mechanical force, the core of the electrode plate is partially severed. The degree to which the core is cut has a great influence on the internal short circuit phenomenon. In other words, since lath plates and punched plates that are generally used as core bodies do not have a directional nature of fracture, the cut portions are partially formed without directionality, and some are warped. It penetrates the separator from the surface of the electrode plate and is inserted into the other electrode plate.

On the other hand, if the cut portion is formed only in one direction, it will not be so extreme that it will poke into the other electrode plate.

F. Example Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 and 2, taking a non-aqueous electrolyte battery as an example.

1 is a positive electrode plate formed by applying a paste containing manganese dioxide as an active material to an electrode plate core 2 and drying it, and 3 is a negative electrode plate made of a lithium plate, which is the gist of the present invention. It is wound through a separator 4 to form a spiral electrode body. Reference numeral 5 denotes an exterior can which also serves as a negative terminal and which houses the spiral electrode body, and its opening is closed via an insulating packing 6 with a sealing lid 8 which also serves as a positive terminal to which a safety valve mechanism 7 is attached. 9 and 10 are a positive electrode lead plate and a negative electrode lead plate.

Therefore, the electrode plate core 2 has a portion a as shown in FIG. 2A.
Made of lath board with deep cuts. When this lath plate is subjected to an external mechanical force, it is cut in one direction as shown by the broken line, resulting in the state shown in FIG. 2B. Figure 3A shows a lath plate used as a conventional electrode plate core.
In this case, when an external mechanical force is applied, the material is cut without directionality as shown by the broken line, resulting in the state shown in FIG. 3B.

A battery of the present invention using a lath plate as the electrode plate core shown in FIG. 2 and a conventional battery using a lath plate as an electrode plate shown in FIG. When the battery was deformed to about 1/2 of its diameter, there were no problems with the battery of the present invention, but with the conventional battery, the electrolyte came out from the safety valve after deformation.

When these batteries were disassembled, it was found that in the conventional batteries, the cut portion of the electrode plate core had no directionality, and a portion of the cut portion was warped and stuck into the negative electrode. It is thought that this caused a short circuit inside the battery, causing a current to flow and the temperature to rise rapidly in some areas, causing the internal pressure of the battery to rise due to evaporation of the electrolyte and generation of decomposed gas, causing the safety valve to operate.

It should be noted that various shapes of the electrode plate core applicable to the present invention are conceivable in addition to those shown in the embodiments. For example, it is also possible to use a punching plate in which shallow grooves are formed between the holes in only one direction so that the punching plate is easily cut in one direction when an external force is applied.

G. Effects of the invention As mentioned above, the present invention uses a porous metal plate with directional breaking strength as the core of the electrode plate, so that external force is not applied to the battery using this core. At this time, this core is cut in one direction, so
It is possible to suppress the occurrence of internal short circuits caused by deformation of the battery due to external mechanical force, and the safety of the battery can be improved, so its practical value is extremely large.

[Brief explanation of drawings]

Figures 1 and 2 relate to the present invention; Figure 1 is a vertical cross-sectional view of the battery, and Figure 2 is an enlarged view of the electrode plate core, where A is the state before cutting and B is the state after cutting. The status is shown respectively. FIG. 3 is an enlarged view of a conventional electrode plate core, with A showing the state before cutting and B showing the state after cutting. FIG. 4 shows a schematic diagram of the battery deformation test. 1... Positive electrode, 2... Plate core, 3... Negative electrode, 4
... Separator, 5 ... Exterior can, 6 ... Insulation packing, 8 ... Sealing lid.

Claims (1)

[Scope of utility model registration request] A battery comprising an electrode body in which at least one of the electrode plates is formed by spirally winding positive and negative electrode plates with a core body through a separator, the core body being a porous metal having directionality in breaking strength. A battery characterized by using a plate.