JPS58164150A - Battery - Google Patents

Abstract

PURPOSE:To efficiently release heat generated in a battery to make possible use at high rate discharge and keep safety even in misuse such as short circuit by setting a metallic sealed hollow body, and filling liquid, and connecting electrically one electrode and an outer terminal with the hollow body. CONSTITUTION:When a positive terminal and a negative terminal are shorted, or a battery is discharged at large current, joule heat is generated inside the battery, and battery temperature is increased. Heat is released to outside in the outside of the battery, and transmitted to the side wall of a tube 2'' in the center portion. Pure water in the tube is heated and vaporize and heat is absorbed by temperature increase and heat of vaporization. Vapor is cooled by outside air in a cap 2', and liquefied to water, and heat of condensation is released at the same time. Heat generated in the battery is quickly released outside and overheating inside the battery is suppressed. Liquefied water in the cap 2' moves along inner wall of the tube 2'' and again vaporized by heat in the inside of the battery, and then liquefied. This cycle is repeated and water functions as heat transmission media.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to relatively large, high-output batteries that tend to overheat due to self-heating during strong discharge or short circuit, such as large non-aqueous electrolyte lithium batteries, alkaline electrolyte batteries, etc. The present invention relates to a suitable heat dissipation mechanism.

Conventionally, when the above-mentioned batteries are used with strong discharge, the temperature of the battery rises due to self-heating of the battery, causing plastic materials such as the battery separator, gasket, and exterior body to melt or soften, resulting in damage to the battery. For this reason, the upper limit of the discharge current is regulated, making it difficult to supply the sufficient output required by the equipment, and often placing constraints on equipment design. In addition, if the battery's terminals are short-circuited or connected in a near-short-circuit condition due to misuse, or if an internal short-circuit occurs, the battery may be damaged as described above due to self-heating, or in severe cases. There was a high risk of rupture, explosion, or fire. To address these problems, some methods have been adopted to prevent accidents by installing current fuses and temperature fuses in batteries and equipment to cut off the circuit when excessive current flows.
When a fuse is provided within a battery, it is not practical because it is impossible to replace the fuse, which is uneconomical, and the space required to install the fuse within the battery is required and the work is frequent. Also, when installing fuses on equipment,
It was not possible to prevent dangers due to mishandling, such as short-circuiting of batteries outside the equipment.

The present invention solves the problems in the conventional examples described above, effectively dissipates the amount of heat generated within the battery to the outside of the battery, suppresses the danger of battery heat generation, enables use with large current discharge, and short circuits. The aim is to provide batteries that are safe even when used incorrectly.

The present invention provides a metallic sealed hollow body that penetrates the battery container from the inside of the battery and is partially exposed to the outside of the battery, and the interior of this hollow body is kept in a reduced pressure or vacuum state, and a liquid is sealed inside. In addition to the first feature, the second feature is that the hollow body electrically connects one electrode and the external terminal.

The effects of the present invention are, firstly, that the heat generated inside the battery is conducted to the hollow body and dissipated to the outside of the battery, thereby suppressing the temperature rise due to self-heating of the battery;
When the heat inside the battery is conducted to the hollow body and the temperature rises, the temperature of the liquid that occupies a part of the interior volume increases and the liquid gains the amount of heat necessary for evaporation (latent heat of vaporization). The vaporized vapor spreads inside the hollow body and is cooled and liquefied in the part of the hollow body that is exposed to the outside of the battery, which has a much lower temperature than the inside of the battery, and is dissipated as heat of condensation. The generated heat is dissipated to the outside of the battery through the hollow body. The liquefied liquid returns to the high temperature inside the battery and lowers the temperature inside the battery.

By repeating the cycle of absorbing heat, vaporizing it, dissipating heat through the hollow body exposed to the outside of the battery, and liquefying it, the heat inside the battery is effectively dissipated to the outside of the battery using the liquid sealed inside the hollow body as a medium. Can be done. At this time, by reducing the pressure or creating a vacuum in the space within the hollow body, it is possible to facilitate the vaporization of the liquid and to suppress an excessive rise in pressure within the hollow body.

In addition, the metal hollow body in the present invention functions as a current collector by connecting it to one of the electrode plates, and the part exposed to the outside of the battery can be directly used as a battery terminal, or can be used as a battery terminal. It can be a conductive medium for connecting.

In the present invention, the material of the hollow body is
- It is assumed that it has corrosion resistance even when it comes into contact with elements. For example, in non-aqueous electrolyte batteries, if the cylinder also serves as the positive electrode current collector, aluminum, titanium, or stainless steel can be used, and the negative electrode current collector If it also serves as a body, nickel, copper, stainless steel, titanium, etc. can be used. Nickel is still used in nickel-cadmium batteries that use an alkaline electrolyte, and nickel is used in alkaline batteries that use a zinc negative electrode when it also serves as the positive electrode current collector.
When serving also as a negative electrode current collector, a metal whose surface is covered with copper, brass, or tinwork at least in the portion located inside the battery can be used.

In addition, the liquid sealed inside the cylinder occupied a part of the internal space of the cylinder, and the other space was maintained in a reduced pressure or vacuum state, and the liquid existed inside the battery through the wall of the hollow body. The effect of the present invention is effectively exhibited in this state, and the effect is most effective when the battery is placed upright. This can be easily understood from the heat dissipation mechanism based on the liquefaction and vaporization cycles described above.

In addition, it is desirable to select a liquid that has a large latent heat of vaporization and heat of solidification as the liquid sealed inside the cylinder, and its boiling point should preferably be above room temperature and below the temperature at which there is concern about battery damage. can be used.

Furthermore, the shape of the hollow body has a large surface area for both the internal and external parts of the battery, making it easy to absorb and dissipate heat.
It is effective to set the wall thickness of the cylinder to the minimum thickness sufficient to ensure mechanical strength.

Examples will be described below.

Figure 1 shows a cross section of a battery to which the present invention is applied.
Reference numeral 1 denotes a sealing lid made of polypropylene, and numeral 2 denotes a hollow body made of stainless steel, which passes through a hole in the center of the sealing lid 1 and partially protrudes from the inside of the battery to the outside. This hollow body 2 is composed of a cap part 2 that functions as a negative electrode terminal and a cylindrical part 21 that functions as a negative electrode current collector.
After reducing the pressure to 0 +oHg and injecting the purified water 3 into the bottom of the hollow part, the cap part 21, the cylinder part 2IV, the flange part 2''
1 are joined by laser welding to form an airtight structure. 4,
Reference numeral 4' denotes a washer made of stainless steel, which is provided as a reinforcing material for integrating the sealing lid 1 and the hollow body 2 by caulking. 6 is a negative electrode made of metallic lithium that is in close contact with the outer wall of the cylindrical portion 2''; 6 is a liquid-retaining material made of polypropylene nonwoven fabric that also serves as a separator; and 7 is a material mainly composed of fluorocarbon, in which carbon powder and fluororesin powder are added. 8 is a stainless steel battery container that also serves as a positive electrode terminal, and the battery element is sealed by bending the opening inward through the sealing lid 1. 7 and the liquid retaining material 6 are impregnated with an electrolytic solution in which 1% JIZ- lithium borofluoride is dissolved in γ-gutyrolactone.

When the positive and negative terminals of a battery with this configuration are externally shorted or discharged with a large current, Joule heat is generated within the battery and the battery temperature rises. In this case, heat is radiated to the outside of the battery at the outer part of the battery, and heat is transferred to the side wall of the cylindrical part 21 in the center part, and the purified water 3 inside the cylindrical part is heated and vaporized, and the heat necessary to raise the temperature is The vaporized water vapor absorbs the heat inside the battery as heat of vaporization, and the vaporized water vapor is cooled by the outside air in the cap part 21 of the hollow body 2 and liquefies into water. At the same time, the heat generated inside the battery is quickly dissipated by dissipating the condensation heat. dissipates to the outside, suppressing overheating inside the battery. The water liquefied in the cap part 21 moves along the inner wall of the cylindrical part 21, is vaporized again by the heat inside the battery, and is liquefied in the cap part 21. The cycle of water liquefied in the cap part 21 is repeated, and acts as a heat transfer medium.

In Fig. 1, the solid line arrow indicates the direction of movement of steam, and the dotted line arrow indicates the direction of movement of reflux liquid. In order to confirm the effect of the present invention, a diameter of 60 mm and a height of 50 mm was used.
A prototype battery was manufactured and a comparison was made between the product of the present invention and a conventional product. The product A of the present invention uses a battery having the structure of the above embodiment, and the conventional product B uses a battery having the same structure as that of the embodiment, but has a hollow body with the same outer shape and material and no hollow part, and this is used as a negative electrode current collector. The configuration was the same except that the negative terminal was used. FIG. 2 shows changes in the temperature of the outer wall of the battery and the internal temperature of the battery measured by inserting a temperature sensor into the gap between the positive and negative electrodes when both batteries are short-circuited. In FIG. 2, the solid line shows the characteristics of the conventional product B, and the dotted line shows the characteristics of the invention product A.・The marks are the external wall temperature of the battery, and the ○ marks are the actual measurement points of the internal temperature of the battery.

In conventional products, the temperature inside the battery rises over time, and the temperature inside the battery increases by approximately 2
When the temperature reached 00°C, the sealing lid softened and deformed, and a portion of the sealing part opened and molten metal lithium was blown out of the battery along with the vaporized electrolyte, creating a dangerous situation. At this time, the temperature of the outer wall of the battery was approximately 105° C., which was a relatively small temperature increase due to heat radiation from the outer wall of the battery. On the other hand, in the product of the present invention, the internal temperature of the battery is 96°C, and the temperature of the outer wall is 7°C.
After the short circuit started at 6°C, it became almost constant after about 40 minutes.
No increase in temperature was observed after that, and there was no change in appearance.

The softening temperature of the sealing lid and liquid retaining material used for this battery is approximately 90'C.
In the case of liquid retaining material, it becomes obvious that it softens at about 110 degrees Celsius, and in the case of sealing lids, it becomes obvious that it softens at about 120 degrees Celsius, making it impossible to fully demonstrate its functions. In addition, most of the liquid retaining material was in a molten state, and the positive and negative electrodes were short-circuited internally.These problems did not occur with the product of the present invention.

From the above results, it is recognized that the present invention has an extremely superior effect of discharging the internal heat of the battery to the outside. This is due to its extremely good conductivity, and there are various embodiments of the present invention that apply this principle. For example, the shape of the hollow body may be varied depending on the battery structure, and the shape of the hollow body may be varied depending on the battery structure. The effect can be enhanced by making the thin tube spiral or by providing unevenness on the surface in order to increase the area of the heat absorption part.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a battery according to an embodiment of the present invention, and FIG. 2 is a diagram showing temperature rise changes in the same battery during a short circuit. 1...Resin sealing lid, 2...Stainless steel hollow body, 2"...Cap portion, 2
“...Cylinder portion forming a current collector, 2”1...
7. Lunge part, 6... Negative electrode, 6... Liquid retaining material, 7... Positive electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
15a 2nd drawing interval (this evening

Claims (2)

[Claims] (1) A battery characterized in that a metallic hollow body is provided that penetrates the battery container from inside the battery and a portion thereof is exposed outside the battery, and a liquid is sealed inside the hollow body under reduced pressure or vacuum conditions. (2) The battery according to claim 1, wherein the metallic hollow body electrically connects one electrode and an external terminal.