JPS5816469A - Heat cell - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the discharge characteristic at the high slewing, by arranging a leakage-proof ring made of inorganic substance between the pellet made of a plurality of electrolytic rings and the depolarization agent arranged concentrically. CONSTITUTION:The cell element of the thermo-cell is formed of a negative pole current collector 1, negative pole active substance 2, inner protective ring 3, outer protective ring 4, positive pole current collector 12 and a plurality of DEB pellets 5-8 integrated with ring-shaped EB layer 10 and DE layer 11, and the leak-proof ring 9 arranged between them. When forming the leak-proof ring 9 with an inorganic binder to be used for DEB pellets 5-8 and the asbestos paper using the inner and outer protective rings 3, 4, the leakage of the thermo- cell when using in a rocket and performing the high slewing can be reduced considerably resulting in the enlargement of the usage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pellet in which an electrolyte layer (EB layer) and a depolarizer layer (DE layer) are integrated, or a pellet (hereinafter referred to as DEB) consisting of a mixture of an electrolyte and a depolarizer. The purpose of this technology is to activate the battery by arranging a leakage prevention ring made of an inorganic material concentrically between a plurality of concentrically arranged pellets. The objective is to prevent leakage of electrolyte during operation and improve battery performance when rotational motion is applied to the battery.

A thermal battery cannot supply electricity at room temperature, but when heated to a high temperature and the electrolyte melts, the electrolyte becomes ionic conductive and can supply electricity. The electrolyte here is KO2-Lice.

Eutectic salts such as KBr-LiBr are used, and these molten salts melt at 330''C to 360'C and have an ionic conductivity about 10 times that of aqueous electrolytes.This type of thermal battery has the following: It is known that the battery has the following characteristics.In other words, there is practically no self-discharge during storage, and the discharge characteristics are the same as those immediately after manufacture even after long-term storage.By incorporating a heating agent inside the battery, the battery can be used easily. The battery can be activated in a short time of less than 0.6 seconds by applying a heating agent at the time of activation.Using an ultra-low potential negative electrode active material that cannot be used with aqueous electrolytes, the output voltage per unit cell can be reduced. It can be used in a wide temperature range from low to high temperatures. It is small and lightweight and can supply a large current. Because of these characteristics, it has been put into practical use as a power source for Rokut and emergency use.

However, the problem with conventional pellet-type thermal batteries is that when the battery is activated, the electrolyte leaks out of the unit cell, resulting in a liquid junction, and the amount of electrolyte inside the DEB pellet decreases, increasing internal resistance. This could cause a voltage drop. In particular, it has been recognized that if a strong swirling motion is applied to the battery, this phenomenon is exacerbated and the discharge life is significantly reduced. Fig. 1 shows a cross section of a unit cell of a thermal battery using a conventional DEB pellet. The cell has a negative electrode current collector 1
．． Negative electrode active material 2. Internal protection ring 3. External protection ring 4
．． It is composed of a DEB pellet 13 in which an EB layer 10 and a DE layer 11 are integrated, and a positive electrode current collector 12. The negative electrode active material 2 is Mq.

Ultra-low potential substances such as Ca and Li are used. D.E.B.
The pellet 13 has an EB layer 1o made of a mixture of electrolyte powder and an inorganic binder such as silica or kaolin to limit the amount of electrolyte to 60 to 80% by weight, and a depolarizer such as calcium chromate powder containing 20 to 30% by weight. There are also pellets in which the DE layer 11 made of a mixture to which electrolyte powder is added are integrated under pressure (7< is a pellet formed by pressure molding a mixture of an electrolyte and a depolarizer. Conventionally, in such unit cells, asbestos The internal protection ring 3 and the external protection ring 4, which are made of heat-resistant materials such as paper, alumina paper, or glass paper, prevent the electrolyte from leaking out of the cell when the battery is activated. These protective rings were unable to sufficiently prevent liquid leakage, and severe liquid leakage was observed particularly from external protective ring 4. Therefore, such liquid leakage was especially severe during high turns, and the battery The discharge capacity of the battery significantly decreased due to an increase in internal resistance due to a short circuit between the batteries and a lack of electrolyte within the unit cell.The following table shows the relationship between the number of rotations and the lifespan up to a cut-off voltage of 2oV in conventional batteries.

(Left below) As is clear from this table, as the number of rotations increases, the discharge life of the battery is significantly shortened, and when the battery is disassembled after discharge, it is found that the battery subjected to high rotation (IC) poo ~ 12,000 rpm) Severe liquid leakage was observed on the side of the external protection ring 4, and a liquid junction between the unit cells was confirmed. It was also observed that the amount of electrolyte in the pellet decreased due to leakage, increasing the internal resistance of the battery.

The present invention improves on these drawbacks by arranging a leakage prevention ring made of an inorganic material between ring-shaped DEB pellets concentrically with the DEB pellets to improve leakage resistance during high rotations. It was planned. FIG. 2A shows a cross-sectional view of a unit cell according to an embodiment of the present invention, and FIG. 2B shows a plan view thereof. The unit cell has a negative electrode current collector 1. Negative electrode active material 2
．． Internal protection ring 3. External protection ring 4. DEB pellet 6.6°7. EB layer 10 and DE layer 11 are integrated.
8. Leak prevention ring9. It is composed of a positive electrode current collector 12. The leak prevention ring 9 according to the present invention is made of an inorganic binder such as kaolin, silica, etc. used for the DEB pellets 5, 6, 7.8, or asbestos paper, alumina paper, glass paper used for the outer and inner protective rings 4, 3. DEB pellets 5, 6, and 7.8, or they are formed by adsorbing less electrolyte than DEB pellets 5, 6, and 7.8 on their inorganic rings.

These rings 9 have the ability to adsorb electrolyte and prevent leakage of electrolyte to the outside of the unit cell. The width a of this leakage prevention ring 9 varies depending on the size of the unit cell, but if it is 6W or less, DEB pellets 5, 6, 7.
They are arranged concentrically between 8. In this example, a binder with several weight percent of electrolyte adsorbed was used with a width of 21111 mm.
It was used in three layers. In addition, each DEB pellet 5, 6,
In No. 7.8, the contact surface with the negative electrode was made equal to minimize the variation in current density. In other words, the DEB pellet throat is 5 (6 (8) and the pellet near the outer periphery of the cell has a long throat radius, so the width of the pellet is 8. The aim was to equalize the

Conventionally, for example, 27th Power 5source
In 3ymposium, a technique is known in which grooves are provided in the DEB beret to prevent the alloy produced by the battery reaction from leaking out of the unit cell, but the present invention does not include a technique to provide grooves in the DEB beret. It is a completely different technology that incorporates a leakage prevention ring to adsorb electrolyte and prevent leakage.

Next, a stacked battery similar to the conventional example was constructed using the unit cell according to the present invention, and the results of a comparative study will be described. FIG. 3 is a sectional view of a stacked battery, showing a positive terminal 141, an ignition terminal 162, an igniter 16. Negative terminal 17. Heating agent 18. Unit battery 19. It is composed of an outer can 20 and a heat insulating layer 21. The laminated battery according to the present invention constructed as described above was subjected to a swirling discharge test similar to that of conventional products, and the results are shown in the chart. Compared to the results for conventional products, the discharge life during no-swivel and low-swivel conditions is not much different, but 100
The discharge life during high rotation exceeding 00 rpm is about 2
It has doubled in size. Furthermore, even when the battery was disassembled after discharge, it was confirmed that leakage from the external protection ring 4 side was suppressed. Furthermore, since leakage was suppressed, the increase in internal resistance due to electrolyte shortage was also suppressed, and the voltage at the initial stage of discharge was also found to be flat.

As described above, the use of the present invention can significantly improve the deterioration of discharge characteristics during high rotation, which was a drawback of conventional thermal batteries, and is useful for expanding the range of use of thermal batteries. be.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a unit cell used in a conventional pellet-type thermal battery, FIG. 2A is a longitudinal sectional view of a unit cell according to an embodiment of the present invention, and FIG. The plan view and FIG. 3 are cross-sectional views of a stacked battery using the unit cell shown in FIG. 2. 2...Negative electrode active material, 3...-Inner protection ring, 4...Outer protection ring, 5, 6, 7, 8
, 13...DEB Pere Nodo, 9...
Leakage prevention tl='Jng. Name of agent: Patent attorney Toshi Nakao TL or one person Figure 1 (11) 131! m

Claims (2)

[Claims] (1) A thermal battery characterized in that a leakage prevention ring made of an inorganic substance is arranged between pellets made of a plurality of ring-shaped electrolytes and depolarizers arranged concentrically. (2) The thermal battery according to claim 1, wherein the leakage prevention ring adsorbs less electrolyte than the pellets.