JPS58121565A - Layer-built type thermobattery - Google Patents

Abstract

PURPOSE:To uniform the temperature distribution inside a thermobattery as well as to improve the duration of discharge, by decreasing the weight of each heating agent in proportion as going toward the bottom from an igniter side, in case of a layer-built type thermobattery laminating an elementary cell and the heating agent alternately. CONSTITUTION:Shown in illustration, 1 is of an elementary cell, 2, 3 and 4 is of heating agents having altered weight at every block unit of the upper part, middle part and bottom part, 5 is of heat insulating materials including asbestos, etc., 6 is of a cathode output terminal, 7 is of an anode output polar body, 8 is of a cathode outut lead, 9 is of anode output lead, 10 is of an igniter for igniting heating agents 2, 3 and 4, and 11 is of an igniter energizing terminal, respectively. The weight of heating agent 3 at the central part is set to be smaller by 2wt% as compared with the heating agent weight of the upper heating agent 2 and likewise the heating agent 4 at the bottom is set to be smaller by 4wt% in the same way. With this, the temperature stop a layer-built body is raised up while an over-heating tendency at the bottom can be checked and thereby the temperature distribution in the whole layer-built body can be almost entirely uniformized, through which considerable improvement in the discharge duration of a layer-built battery have been recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stacked thermal battery in which a unit cell and a heating agent are alternately stacked and built in, and the purpose is to reduce the weight of the heating agent to the igniter side (hereinafter referred to as the upper part). By decreasing the amount toward the bottom, the temperature distribution inside the thermal battery is made uniform, and the discharge time is significantly extended and improved.

In general, thermal batteries are used as power sources for flying objects and emergency power sources because of their ability to draw a large amount of current in a relatively short period of time. This battery uses a molten salt (which is solid at room temperature) in the electrolyte.
(KCffl-LiCA, KBr-LiBr, etc.) is used, and electric power can be supplied by heating 7IO to above its melting point. For this reason, many thermal batteries have a built-in heating agent.

A typical battery configuration is a metal carunium plate for the negative electrode.

A unit cell that uses a eutectic mixed salt of KO2-LiC-e as an electrolyte, calcium chromate as a depolarizer, and nickel or iron as a current collector, and zirconium powder as a heating agent for battery activation. Mixed molded products with barium chromate powder are alternately laminated.

In conventional thermal batteries, the heating agent is placed within a predetermined weight range within the stack to generate the amount of heat necessary to melt the electrolyte and activate the battery. That is, heating agents having the same weight range are arranged from the top to the bottom of the unit cell stack so that the same amount of heat is generated in every part of the stack.

However, in Japanese Patent Publication No. 49-11497, a method is adopted in which only the heating agents disposed at the extreme and bottom portions of the laminate rather than at the center generate a greater amount of heat than other heating agents.

However, the igniter, output leads, output terminals, etc. are concentrated at the top of the stack. Due to the reduction in the insulation effect due to the creation of spaces without insulation material, significant variations in temperature distribution within the laminate occurred.

Figure 1 shows the upper part 2 of the laminate. 7 is a graph showing the relationship between discharge time and temperature change in the center part 3 and bottom part 4.

Note that C indicates a temperature range considered appropriate for the thermal battery to supply power.

From this graph, it is clear that in conventional batteries, the temperature decreases quickly in the upper part of the stack due to the aforementioned reduction in heat absorption and insulation effect, and the bottom part tends to overheat at the beginning of discharge. For this reason, in the unit cells located in the upper part of the stack, the molten electrolyte solidified quickly and the internal resistance increased significantly.

In addition, because the unit cell at the bottom tends to overheat at the beginning of discharge, self-depletion due to the direct reaction between the positive electrode active material and the negative electrode metal increases, and 3/Ca Cr O
In the 4-series thermal battery, internal short circuits caused by the alloy were more likely to occur. Therefore, an increase in internal resistance due to coagulation of the electrolyte in the second part of the laminate and an increase in self-depletion in the bottom part of the laminate limit the rate of discharge of the entire laminate battery, leading to a reduction in the discharge life. Such drawbacks could not be resolved at all using conventional methods.

The present invention improves this drawback by reducing the weight of the heating agent from the top to the bottom of the battery stack.
By creating a gradient in the amount of heat generated and making the temperature distribution of the laminate uniform, the discharge duration is significantly extended. In other words, the weight of the heating agent for each sheet of the laminate may be reduced from the top to the bottom, or the laminate may be divided into several blocks such as the top, center, and bottom, and the weight of the heating agent used for each block may be reduced. This method creates a gradient in the amount of heat generated through a step-by-step method that reduces the amount of heat generated. Hereinafter, the present invention will be explained using figures.

FIG. 2 is a longitudinal sectional view of a stacked battery according to an embodiment of the present invention. In the figure, 1 is a unit cell, 2,3゜4 is a heating agent whose weight is changed for each block at the top, middle, and bottom, 5 is an insulating material such as asbestos, 6 is a negative output terminal, and T is a positive output terminal. , 8 is a negative output lead, 9 is a positive output lead, 1Q is an igniter for igniting the heating agents 2, 3.4, and 11 is a terminal for energizing the igniter. Reference numeral 12 denotes a space without a heat insulating layer, which is created at the connection between the output leads 8 and 9 and the output terminals 6 and 7, and 13 is a space without a heat insulating layer, which is created by disposing the igniter. 14 is an exterior body.

In this embodiment, the heating agent is divided into three blocks, the upper block 2, the middle block 3, and the bottom block 4, and the heating agent in the central heating agent 3 is heavier than the heating agent in the upper heating agent 2. A method was used in which the weight of each block was reduced, and the weight of the bottom heating agent 4 was lower than that of the central heating agent 3, thereby creating a stepwise gradient in the amount of heat generated for each block. Incidentally, the center heating agent 3 was reduced by 2 weight percent of the heating agent weight of the upper heating agent 2, and the bottom heating agent 4 was reduced by 4% by weight. This makes it possible to raise the temperature at the top of the laminate while simultaneously suppressing the tendency to overheat at the bottom.
The temperature distribution throughout the stack was approximately equal to the discharge curve of the conventional battery of the Ca Cr OJ system and the discharge curve B of the battery according to the invention of the same system. In conventional batteries, as described above, the electrolyte at the top of the stack is rapidly assimilated, increasing the internal resistance, and the discharge duration of the entire stack is quite short due to self-depletion at the bottom. Furthermore, at a rate of about 30%, a short circuit phenomenon occurred at the bottom, causing voltage fluctuations. However, in the battery of the present invention, by lowering the temperature at the top of the stack and further lowering the temperature at the bottom, the temperature distribution within the stack was almost uniformly within the appropriate temperature range C. In addition to effectively discharging, there is no voltage fluctuation due to short circuits, and the discharge duration is significantly extended.

In this embodiment, a case has been described in which the amount of heating agent is changed stepwise for each of the three blocks of the top, center, and bottom, but the finer the division, the more uniform the temperature distribution will be, so it is preferable. However, since it is necessary to adjust many kinds of heating agents with different weights, it is very troublesome, and therefore a limit naturally arises. In the explanation, Ca/KC Swamp-LiC, 8/C
Although the aCrO4 system has been described, it can be similarly applied to batteries using Mq or Li as the negative electrode, or batteries using WO2°FeS2 or the like as the positive electrode.

As described above, the present invention reduces the weight of the heating agent in the laminate sequentially or stepwise from the top to the bottom, thereby making the temperature distribution of the laminate uniform and extending the discharge life of the stacked battery. It has been significantly extended.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between discharge time and temperature changes at the top, center, and bottom of a stacked battery. FIG. 2 is a longitudinal cross-sectional view of a stacked battery according to an embodiment of the present invention. 1 is a graph showing discharge curves of a stacked battery according to the present invention and a conventional stacked battery; 1...Battery, 2...Top heating agent, 3...
...Central heating agent, 4...Tail heating agent, 10.
...Igniter. Cicada Kai 3 Sa 9 \ Zuhe ″
−~ C”) Morimi

Claims (1)

[Claims] A stacked battery comprising a plurality of unit cells and a heating agent alternately stacked, the weight of the heating agent being reduced sequentially or stepwise from the top to the bottom of the battery. thermal battery.