JP3136903B2 - Thermal battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal battery, and more particularly to a thermal insulator for a thermal battery.

[0002]

2. Description of the Related Art A thermal battery is a battery in which a eutectic salt such as LiCl-KCl is used as an electrolyte. At room temperature, the electrolyte is a solid non-conductive material. The battery is a battery having such a property that the electrolyte becomes a good ion-conductive molten salt, becomes active as a battery, and can supply electric power to the outside.

This type of battery has practically no self-discharge inside the battery as compared with a general battery, and exhibits the same discharge characteristics as immediately after production even after long-term storage. The exothermic agent for heating the unit cell is incorporated at the time of manufacturing, and the exothermic agent acts when the battery is used, so that the battery can be activated instantaneously, which is convenient for emergency use. Since the electrode is operated at a high temperature, the electrode reaction easily proceeds and has high output characteristics. Because of these features, it has been put to practical use as a power source in the fields of various flying objects and guidance equipment.

[0004] In general, a thermal battery is activated by instantaneously applying a current of 0.5 to several A to an igniter from an external terminal for activation of the thermal battery. For cases where it is not possible to use a power source for ignition due to the system, there has been proposed a thermal battery provided with a piezoelectric igniter that ignites using a high voltage generated when a piezoelectric element is hit. Thus, the ignition charge is ignited, and the flame ignites and burns the exothermic agent. The combustion heat heats the unit cell, the electrolyte in the unit cell melts, instantaneously generates power, and can supply power to the outside. Structurally, a power generation unit in which unit cells and exothermic agents are alternately stacked, a igniter for starting up, a heat insulating material for keeping heat, etc. are contained in a metal container, and a fitting part with the battery lid is TIG-welded. With a completely sealed structure. For this reason, impact resistance, which is one of the environmental resistances, also has better characteristics than other batteries,
The limit of the thermal battery is about 5,000 G, and it has a drawback that it is difficult to use the thermal battery in applications exceeding the impact resistance.

[0005]

In a conventional thermal battery having the above-mentioned disadvantage, an alumina sintered body was used for the lid heat insulator. However, if the impact resistance exceeds 5,000 G, the impact force is reduced. For this reason, the power generation unit below the lid heat insulator collides with the lid heat insulator, and the lid heat insulator is destroyed, so that the tightening pressure of the power generation unit decreases and the contact resistance increases. In particular, the utilization rate of the active material of the unit cell at the time of high rate discharge decreases, the output voltage decreases,
The problem of deterioration of the discharge life occurred.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a practical thermal battery up to 25,000 G in impact resistance.

[0007]

SUMMARY OF THE INVENTION In order to solve these problems, the present invention uses a heat insulator and a heat-resistant impact-resistant resin molding material inside a battery, thereby providing a heat-insulating material for the cover.
The present invention is characterized in that the lid insulator is prevented from being destroyed even when a shock of 5,000 G is applied.

[0008]

According to the present invention, by using a lid heat insulator made of a resin molding material having heat resistance and impact resistance inside the battery,
The tightening pressure of the power generation unit becomes constant, the utilization rate of the active material of the unit cell is improved particularly at the time of high-rate discharge, a stable output voltage is obtained, and the discharge life can be extended.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. In the examples, for convenience of testing,
A thermal battery using a piezoelectric ignition ball was constructed and evaluated.

FIG. 1 is a longitudinal sectional view of a thermal battery according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a unit cell composed of a negative electrode layer made of Li, an electrolyte layer using a LiCl-KCl eutectic mixed salt as an electrolyte, and a positive electrode layer containing FeS ₂ as a main component. For example, a heating agent for heating and generating electricity in the unit cell 1 in which Fe powder and KClO ₄ are mixed, and a plurality of these are alternately combined to constitute a laminate. At the top of this stack is the lid insulator 11 of the present invention. The lid insulator 11 is usually located below the exterior lid 9.

Reference numeral 3 denotes a piezoelectric ignition device comprising a piezoelectric element 4;
The piezoelectric ignition ball 8 is composed of an ignition terminal 5 and an igniting agent 6, for example, a mixture containing Zr powder, BaCrO ₄ and inorganic short fibers as main components, and a high voltage generated from the piezoelectric element 4 due to impact or the like is applied from the ignition terminal input pin 7. When supplied, a spark discharge is generated at the tip of the ignition terminal 5. The spark activates the igniter 6 and the exothermic agent 2 burns through the ignition sheet 10 to activate the battery.

FIG. 2 is a detailed view of the lid heat insulator used in the present invention. FIG. 2 (a) is a plan view and FIG. 2 (b) is a sectional view. The lid heat insulator is formed using a resin molding material of polyphenylene sulfide. This lid heat insulator was incorporated into the lid inside the battery, and 450 batteries were prototyped to produce 25,000G.
After applying a shock, a discharge test (load rate condition
800 mA / cm ² for 0 seconds, then 2000 mA for 6 seconds
/ Cm ² , a discharge test at a constant current of 800 mA / cm ² after 16 seconds) gave the results shown in FIG. As shown in FIG. 3, the discharge performance did not deteriorate due to the impact, and the utilization rate of the active material of the unit cell at the time of high rate discharge was improved as compared with the case of using the conventional alumina sintered body lid heat insulator, and the discharge life was extended. Was confirmed.

Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. Also in this example, a thermal battery using a piezoelectric ignition device was configured and evaluated. FIG.
FIG. 4A is a detailed view of a lid heat insulator made of a resin molding material in which the function of a piezoelectric ignition ball is shown in a second embodiment of the present invention, and FIG. 4A is a plan view and FIG. It is sectional drawing. 1 in that a function of a piezoelectric ignition ball is provided in the lid heat insulator 11. In FIG. 4, 12 is an ignition terminal electrode, 13 is a fine powder mixture (hereinafter, referred to as an igniting charge) composed of Zr powder, BaCrO ₄ and inorganic short fibers, and 14 is a coating agent (acetic acid) for protecting the fine powder serving as the 13 igniting charge. The lid heat insulator is composed of cellulose: methyl acetate = 5: 95 Wt% dried).

The function of the lid heat insulator configured as described above will be described below. The energy output from the piezoelectric element in the piezoelectric ignition device is supplied to the ignition terminal electrode from the ignition terminal input pin attached to the outer cover, and electrons repeatedly impact and ionize between the ignition terminal electrodes, and this gap is short-circuited by an electron avalanche. As a result, an instantaneous current is generated, and a sharp drop in voltage occurs. Then, a current is caused to continue to discharge by itself, and the energy is used to ignite the ignition charge between the ignition terminal electrodes.

In the present invention, the distance of the gap between the ignition terminal electrodes (hereinafter referred to as gap length) may be set to be equal to or less than the distance between the ignition terminal input pins, but the gap length is set to 1/10 or less of the distance between the ignition terminal input pins. By doing so, the discharge self-sustaining condition (flowing a current to sustain the discharge by itself) is easily satisfied, and energy equal to or more than the energy required to ignite the ignition charge is supplied to the ignition charge. More preferably, it is 0.6 mm or less, and more stable discharge becomes possible between the gap lengths, and the ignition charge can be ignited.

[0016] Fifty batteries in which the lid heat insulator was incorporated into the lid inside the battery were prototyped, subjected to an impact of 25,000 G, and subjected to an ignitability test. As a result, it was confirmed that 100% ignition occurred. As for the discharge performance, the same result as in FIG. 3 was obtained. That is, the discharge performance was not deteriorated by the impact, the utilization rate of the active material of the unit cell at the time of high-rate discharge was improved, and the extension of the discharge life was confirmed.

As described above, by providing the lid insulator of the resin molding material in which the function of the piezoelectric ignition ball is incorporated in the lid insulator, a stable discharge can be achieved in the gap between the ignition terminal electrodes. % Reliable and 2
Because it can be used even under a high impact of 5,000 G, it can be used for a wide range of applications.

In the first embodiment, the lid heat insulator 11 is used.
Was carried out using a resin molding material of polyphenylene sulfide, but the lid heat insulator 11 was made of a resin molding material containing glass fiber in melamine, phenol, polyimide, silicone resin, unsaturated polyester, or their resin derivatives, or their resins. After applying a shock of 000 G, a discharge test was performed, and the same effect was confirmed.

Although the negative electrode layer of the unit cell 1 was Li,
Li-Al alloy, Li-Si alloy, Li-B alloy, Ca
It may be. Although the positive electrode layer of the unit cell 1 was FeS _2, it may be _{TiS 2, V 2 O 5,} V 6 0 13, CaCrO 4.

Also, in the second embodiment, the function of the piezoelectric ignition ball is made of a resin-molded material in which the function of the piezoelectric ignition ball is incorporated in the lid heat insulator. A lid heat insulator made of a molding material may be used.

[0021]

As described above, according to the present invention, by using a heat insulating and heat-resistant resin-molded lid heat insulator inside a thermal battery, even if an impact of 25,000 G is applied, the tightening pressure is reduced. Can be kept constant, especially the utilization rate of the active material of the cell at the time of high rate discharge is improved, a stable output voltage is obtained, and the life of the discharge can be extended,
Further, a thermal battery provided with a lid heat insulator having stable ignition performance can be realized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a thermal battery having a piezoelectric ignition ball, showing one embodiment of the present invention.

FIG. 2A is a plan view of the lid heat insulator of the present invention. FIG. 2B is a cross-sectional view of the lid heat insulator.

FIG. 3 is a diagram showing discharge performances before and after an impact test of the lid insulator of the present invention and a conventional lid insulator.

FIG. 4A is a plan view of a lid heat insulator according to a second embodiment of the present invention. FIG. 4B is a cross-sectional view of the lid heat insulator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unit cell 2 Heating agent 3 Piezoelectric igniter 4 Piezoelectric element 5 Ignition terminal 6 Ignition agent 7 Ignition terminal input pin 8 Piezoelectric ignition ball 9 Exterior lid 10 Ignition sheet 11 Lid insulator 12 Ignition terminal electrode 13 Ignition agent 14 Coating agent

Continuation of the front page (72) Inventor Tetsuji Hayashi 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 6/36 JICST file (JOIS )

Claims (3)

(57) [Claims] 1. A thermal battery having a power generating section in which a unit cell and a heating agent are laminated, wherein a heat-resistant and impact-resistant resin molding material is used for a lid heat insulator. 2. A resin molding material for the lid heat insulator, wherein polyphenylene sulfide, melamine, phenol, polyimide, silicone resin, unsaturated polyester, a resin derivative thereof, or a resin containing glass fiber in the resin is used. The thermal battery as described. 3. The thermal battery according to claim 1, wherein a lid insulator made of a resin molding material is used in which the function of the piezoelectric ignition ball or the electric igniter is incorporated in the lid insulator.