JPH06132035A - Thermal cell - Google Patents

Abstract

PURPOSE:To provide a long life type thermal cell having flat cell voltage and the advantage of decreased manhours by inserting cell stacks into a battery case while holding a cell stack between ceramic plates. CONSTITUTION:A stack fixing rod 12 is inserted in a center open part of cell stacks prepared by reciprocally combining cells 1 using a molten salt and heat generating agent 2. A ceramic plate 13 is used for both end parts of the stack fixing rod 12 to pinch a cell stack and the fastening pressure is fixed and the material of the stack fixing rod is specified, so that the quality of a thermal cell is stabilized and the cell is manufactured easily.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to thermal batteries, and more particularly to improvements in battery assembly.

[0002]

2. Description of the Related Art Thermal batteries have excellent characteristics such as high density discharge characteristics because electrode reactions easily proceed and polarization is small because they are operated at high temperatures. Furthermore, when a use signal is desired, power can be instantly taken out by inputting a start signal. . From this,
It can be said that the thermal battery is a battery suitable for miniaturization and high output, which is a recent trend. On the other hand, generally, in a stack type battery, the tightening pressure of the stack has a great influence on the discharge time and discharge voltage. Thermal batteries are also used as this type of laminated battery, and the following problems occur unless the laminated stack is clamped with an appropriate stack clamping pressure. 1. If the tightening pressure is higher than the appropriate pressure, the separation layer of the cell is destroyed and the positive and negative electrodes are short-circuited. 2. If the pressure is lower than the proper pressure, the contact resistance between the cells may increase and the discharge output may decrease.

Therefore, it is necessary to find a proper stack insertion pressure range and keep the stack pressure during discharge within a proper range. Conventionally, there have been the following methods.

(1) A method of taping the cell stack with a heat resistant tape to integrate them, and then once removing from the jig and inserting. (2) A method of temporarily fixing the cell stack with a metal stack rod using the central through hole of the cell, loading the battery into the battery case, and then removing the metal rod. In the method (1), the final assembly pressure cannot be grasped and maintained due to the loose stack structure.
The quality is not stable. The method (2) requires a step of pulling out the metal stack rod 24 fixing the cell stack, so that the upper and lower battery lids 23 and 27 shown in FIG.
It is necessary to fit and weld 2 and 21 respectively. As described above, there is a problem that the assembling method becomes complicated because the assembling process increases. Therefore, as a conventional improvement method, the following methods have been used for Mg and Ca-based thermal batteries. (3) The igniter 3 is built in the central through hole of the cell, and the ignition hole 19 through which the flame emitted from the igniter passes
There is a method of arranging a cylindrical constraining rod 18 having the above and a fastening plate 20 of the cell stack at the upper and lower ends of the constraining rod 18 and fixing them with this.

[0005]

However, in the conventional method of the above (3), the diameter of the restraint bar 18 cannot be increased in consideration of effectively using the reaction area of the cell. Therefore, in order to maintain the mechanical strength of the restraint rod 18, the thickness of the restraint rod is increased, the inner diameter of the restraint rod that guides the flame from the igniter is small, and the ignition hole 19 provided on the side surface of the restraint rod is also reduced. As a result, the flame from the igniter may not ignite the exothermic agent 2.

Further, the restraint rod and the tightening plate are insulated by using heat-resistant paint, enamel, or ceramic on the metal rod, but in the lithium thermal battery operating for 3 to 30 minutes, the restraint rod and the tightening plate are discharged. Since 18 and the inner wall of the center hole of the cell are in contact with each other, the restraining rod 18 is deteriorated due to a corrosion reaction by the lithium as the negative electrode active material of the cell and the molten salt as the electrolyte, and is broken and the stack pressure is relaxed. Further, in the case of metal, there was a problem that the heat-resistant paint or enamel peeled off and the insulation was lost, causing a short circuit in the power generation section.

The present invention solves the above-mentioned conventional problems, finds an appropriate stack pressure, and facilitates the manufacture of a battery for maintaining this pressure, and a heat having a structure effective for stabilizing the battery output. The purpose is to provide a battery.

[0008]

In order to solve this problem, the present invention provides an opening of a cell stack in which cells having an opening in the center and exothermic agents having the same shape and opening at the same position are alternately laminated. The stack fixing rod is penetrated, and ceramic plates that sandwich the cell stack are arranged at both ends of this stack fixing rod and tightened with fixing screws.
A thermal battery with excellent characteristics because it is fixed at 40 kg / cm ² , and the stack fixing rod is made of a material that does not react with lithium and molten salt and has no electronic conductivity, for example, magnesium oxide as a main component. The structure of the

[0009]

According to this structure, even in a stack of multiple laminated bodies, it is possible to assemble it in the battery case with the tightening pressure at the time of assembling, and the ignition pad and the igniter zone ignite, so that the reliability of battery startup is improved. Since the stack fixing rod uses magnesium oxide, which does not react with lithium and the molten salt as the electrolyte, as a main component even during battery discharge, it retains its function without deterioration.

[0010]

EXAMPLE FIG. 1 shows a cross-sectional view of a long-term thermal battery used in this example. In the figure, reference numeral 1 denotes a cell, a negative electrode 8 made of lithium or a lithium alloy, and LiC on magnesium oxide.
It is composed of an electrolyte 9 impregnated with a molten salt of 1-KCl or LiCl-LiBr-LiF and a positive electrode 10 containing iron disulfide as a main component. Reference numeral 2 is an exothermic agent, which is a mixed molding of iron powder as a reducing agent and potassium perchlorate powder as an oxidizing agent. Reference numeral 4 denotes a squib, which transmits a flame from the ignition pad 5 to each exothermic agent to heat the cell to generate electricity. Reference numerals 6 and 6'indicate internal lead wires and a pair of output terminals 7 and 7 ', and reference numerals 11 and 11' indicate a pair of start terminals for electrically connecting to a pair of igniter lead wires.

Further, the position of the igniter 3 is not arranged at the center of the battery lid 17 as in the conventional case, but is arranged at a position displaced from the center. Reference numeral 15 is a heat insulating material arranged on the outer periphery of the stack, and has a space portion 29 that serves as a space for the stack fixing rod 12 and the fixing screw 14. The stack structure is such that a stack fixing rod 12 made of magnesium oxide is erected on a ceramic plate 13 made of silicon dioxide, and a cell having a hole larger than the outer diameter of the stack fixing rod and a heat generating agent are alternately laminated at the center of the cell. A ceramic plate 13 made of silicon and a fixing screw 14 are tightened at a predetermined pressure.

Power generation including this cell stack and battery lid 17
Part is inserted into the battery case 16, and the battery lid 17 and the battery case
The fitting portion 16 is welded to form a hermetically sealed structure.
In this embodiment, 18 cells are configured in series, and the
Tack pressure is 5-80kg / cm ²8 prototypes of
A comparison was made with the battery having the configuration of Example (3).

Here, the stack pressure 5, 10, 20, 3
0,40,50,60,80kg / cm ²Book when tightening with
The constituent batteries of Example and Conventional Example (3) were 0.1 A / cm.²Fixed
When discharging with current discharge and final voltage of 27V
The results during the period are shown in FIG.

Further, using the battery of this embodiment having a stack pressure of 30 kg / cm ² as the invention product and the battery of the conventional example (3) having the same pressure as the conventional product, an ignition test was performed on 30 batteries, and the ratio of ignition and The results of the discharge time according to the discharge conditions are shown in Table 1.

[0015]

[Table 1]

From the results shown in FIG. 4, in the conventional example (3), when the stack pressure is 30 kg / cm ² or more, the fixing rod is deteriorated and cut and the output is remarkably reduced. According to this embodiment, the stack pressure is 10 to 10. At 40 kg / cm ² , the discharge life of 300 seconds or more is maintained and the output characteristics of the battery are stable. From this, it was determined that the proper pressure range of the stack of the present invention was 10 to 40 kg / cm ² . Regarding the ignitability, the results of Table 1 show that the product of the present invention has a high ignitability of 100%, high reliability, and excellent discharge time. Although the thermal battery using iron disulfide as the positive electrode active material was described in this example, similar results can be obtained for the thermal battery using vanadium oxide, chromium oxide, and manganese oxide as the positive electrode active material. It was

[0017]

As is apparent from the above description, the cell stack is inserted into the battery case while being kept in an appropriate pressure range, and the cell stack is kept under pressure during discharging, so that stable output characteristics are obtained. Indicates. In addition, the flame emitted from the igniter was also reliably transmitted to the exothermic agent, improving the ignitability.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a completed thermal battery according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a completed thermal battery in Conventional Example (3).

FIG. 3 is a vertical sectional view of a manufacturing process in a conventional example (2).

FIG. 4 is a discharge characteristic diagram when the stack pressure is changed.

[Explanation of symbols]

 1 Cell 2 Exothermic Agent 3 Igniter 5 Ignition Pad 12 Stack Fixing Rod 13 Ceramic Plate 14 Fixing Screw

Claims (2)

[Claims] 1. In a thermal battery comprising a negative electrode of lithium and a lithium alloy, an electrolyte using a molten salt, and a positive electrode, a cell 1 having an opening at the central portion and a heat generating agent 2 having the same shape and an opening at the same position are alternately arranged. A stack fixing rod 12 that does not react with lithium and molten salt and has no electronic conductivity is penetrated through the openings of the stacked cell stacks, and ceramic plates 13 for sandwiching the cell stack are arranged at both ends of the stack fixing rod 12. A thermal battery characterized by tightening with a fixing screw 14 and fixing the tightening pressure to 10 to 40 kg / cm ² . 2. The stack fixing rod 12 is mainly composed of magnesium oxide which does not react with lithium and molten salt,
The thermal battery according to claim 1, wherein the ceramic plates sandwiching the cell stack are also made of a material having no electrical conductivity.