JPS6057185B2 - thermal battery - Google Patents

Description

Detailed Description of the Invention The present invention relates to a thermal battery that uses calcium as the main active material of the negative electrode and lithium salt as the main electrolyte, and also has a built-in exothermic agent. CaLi produced during oxidation.

The purpose is to prevent short circuits caused by alloy leakage and achieve high reliability. Since thermal batteries generally use molten salt as an electrolyte, highly active Mg is used as the negative electrode active material.
, Ca, Li, and other metals can be used. Thermal batteries often used in flying objects such as rockets are required to be small, high-output, short-time discharge, and have a fast rise time, and among the negative electrode materials mentioned above, Ca is the most suitable for meeting these requirements. It has been found that various eutectic salts containing LiCl and L1Br as main components are excellent as electrolytes. As mentioned above, the disadvantage of these negative electrode-electrolyte combinations is that CaLi has a low melting point and is produced by ionization of Ca and metallization of Li ions. It is due to alloy outflow. If the outflow of this alloy to the outside of the unit cell structure is slight, a small voltage fluctuation will be sufficient, but if the outflow is significant, it may even reach the point where the entire function of the battery is lost. In order to prevent such a phenomenon, the present invention attaches or impregnates an oxidizing agent to the protective ring used to protect the area around the negative electrode in a unit cell, and oxidizes the CaLi2 alloy that flows out with the oxidizing agent to make it unusable. The idea is to improve the reliability of batteries by making them conductive.

The present inventors previously proposed a method for preventing the outflow of low melting point alloys by improving the unit cell structure, particularly the shape of the DEB pellet, but in the present invention, further improvements are made on the above proposal to ensure that the outflow of the alloy is prevented. It is intended to prevent

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1, FIG. 2, and FIG. 3 all show the structure of a unit cell in an embodiment of the present invention, and in these figures, 1
2 is a negative electrode current collector plate made of iron, nickel, etc., and 2 is a negative electrode active material mainly composed of Ca, which is integrated with the negative electrode current collector plate 1 in an electrically conductive manner. 3 is an electrolyte containing lithium salt, such as lithium chloride (43% by weight) and potassium monochloride (57% by weight).
an electrolyte layer 3' in which an inorganic adsorbent such as silica, alumina, or kaolin is impregnated with a eutectic salt of DEB pellets are made by press-molding two layers of "DEB pellets" and are generally called DEB pellets.

4 is a positive electrode current collector plate made of the same material as the negative electrode current collector plate 1.

5 is a protective ring of the present invention, for example, asbestos vapor,
Heat-resistant base materials such as alumina vapor and glass vapor, chromates such as potassium chromate and calcium chromate, nitrates such as calcium nitrate, halogenates such as KCfO3, various metal oxides such as manganese dioxide, etc. Other oxidizing agents may be attached by an appropriate method such as impregnation or painting.

As shown in these figures, when a conduit hole 6 is provided, the protective ring 5 is composed of an inner protective ring 5'' and an outer protective ring 5''. FIG. 4 is a diagram showing the overall structure of a laminated thermal battery in which unit cells and exothermic agents are alternately laminated using the protective ring of the present invention.

In the figure, 7 is a unit cell of the present invention, and 8 is a heat generating agent, which is a mixture of an oxidizing agent and metal powder such as barium chromate and zirconium powder, lead chromate, potassium permanganate, and zirconium powder, and an igniter. It is ignited by the flame from 9, exhibits an exothermic reaction, heats the unit cell 7, melts the electrolyte, and generates electricity.

10 is a pair of starting terminals for inputting a signal current to the igniter 9;
Reference numeral 11 denotes a pair of output terminals for extracting the electromotive force of the battery to the outside, and each is an exterior lid to which a starting terminal 10 and an output terminal 11 are attached, and the fitting part with the exterior case 14 is welded to create a completely sealed structure. .

15 is a heat insulating layer.

In the above configuration, the thermal battery of the present invention is characterized by a protection ring 5 (inner ring 5'' and outer link 5'') used for the unit cell.
) has been treated with an oxidizing agent, and this battery is normally inactive, but when an ignition current is passed from the starting terminal, terminal 10, the igniter emits a flame, which passes through the vent hole 6 and spreads through each layer. The disposed exothermic agent 8 is ignited to generate heat, and the entire battery becomes active.

Ca. The formation of a low melting point alloy with l5Li+ is as follows. It is thought that it is produced by a reaction.

The above reaction (1) means contact between the negative electrode and the electrolyte, and is an essential reaction for battery construction.

However, since the Li metal produced contributes to the discharge reaction, it is consumed while being produced. On the other hand, in reaction (2), the reaction progresses due to the unconsumed Li metal. Therefore, while controlling free Li+ by optimizing the mixing ratio of the electrolyte adsorption/retention agent and electrolyte and selecting an adsorbent with strong electrolyte retention ability, measures are also taken to prevent the low melting point alloy of CaLi2 from flowing out from the battery structure. I have been teaching. These reactions can ensure high reliability under limited and narrow conditions, but if designed to be used at a high rate of discharge and over a wide temperature range of -50°C to +70°C, some CaLi2 The formation of alloys cannot be avoided. Therefore, some new means have become necessary to ensure high reliability. Based on the above-mentioned idea, the present invention allows the formation of CaLi2 alloy, which cannot be avoided with the current technology, and attempts to transform the CaLi2 alloy into a form that does not have any harmful effects.

The protective rings 5'', 5'' of FIGS. 1, 2, and 3 are immersed in a supersaturated solution of K2CrO48OOg in water 1e and then dried to crystallize and adhere K2CrO4. In this case, it may be used in combination with colloidal silica to improve adhesive strength. When the battery is activated and CaLi2 alloy is generated and moves out of the battery, the protective ring 5'',
The CaLi2 alloy in contact with the oxidizer K2crO
4 and transforms into CaO and Ll2O. C
Since aO and Li2O are nonconductors, no voltage fluctuation occurs even when they come into contact with the anode current collector plate 4. As described above, according to the present invention, it is possible to suppress battery voltage fluctuations by making the CaL]2 alloy produced by the discharge reaction nonconductive, and high reliability of the battery can be ensured with simple measures. It is something.

[Brief explanation of drawings]

1, 2, and 3 are cross-sectional views of a unit cell according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view showing the overall structure of a laminated thermal battery. 2... Negative electrode active material, (Ca), 3...
DEB pellet, 4... Positive electrode current collector plate, 5...
...Protection ring, (outer ring 5'', inner ring 5''
).

Claims (1)

[Claims] 1. A battery comprising a negative electrode containing calcium as a main component, an electrolyte containing a lithium salt, and a protective ring that protects at least the periphery of the negative electrode, in which an oxidizing agent is attached to the protective ring. A thermal battery characterized by: 2 The oxidizing agent adhering to the protective ring is chromate,
The thermal battery according to claim 1, which is any one selected from the group consisting of nitrates, halogenates, and metal oxides.