JPH0328783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a thermal battery using a molten salt as an electrolyte, and makes it possible to manufacture a thermal battery using a thin unit cell.

Thermal batteries have almost no self-discharge at room temperature because their electrolyte is a non-conductive solid.
During use, when heated to high temperatures, the electrolyte melts and exhibits extremely high conductivity, allowing large current discharge. For this reason, thermal batteries can be stored for long periods of time and are excellent as reliable, high-output power sources for emergencies.

Generally, a thermal battery has a structure in which a plurality of unit cells are stacked to obtain high voltage. A unit cell is composed of three layers: a positive electrode layer, an electrolyte layer, and a negative electrode layer, but each of the constituent layers is extremely fragile and difficult to handle, making it difficult to make a thin unit cell with a thickness of 1 mm or less. I couldn't. In particular, batteries that use lithium alloys such as lithium-aluminum alloys or lithium-silicon alloys for the negative electrode and sulfides such as sulfur, iron oxide, and iron disulfide for the positive electrode are expected to have high energy density, but they cannot be molded. However, because the unit cell was fragile, it was difficult to make it thinner, and its characteristics could not be fully demonstrated.

The present invention aims to improve such drawbacks, and provides a thermal battery including a unit cell configured by integrally press-molding a positive electrode raw material powder, an electrolyte raw material powder, and a negative electrode raw material powder into three layers. The electrolyte layer is characterized in that an electrode reinforcing body is provided between the electrolyte layer and the electrolyte layer.

Conventionally, unit cells of thermal batteries have been constructed by separately molding and combining three layers: a positive electrode layer, an electrolyte layer, and a negative electrode layer. Therefore, even if each constituent layer is molded to a thickness of 1 mm or less, the thickness of the unit cell is 2 mm or more. The present invention reduces the thickness of the molded unit cell by integrally molding three layers: a positive electrode layer, an electrolyte layer, and a negative electrode layer, and further includes an electrode reinforcement between the positive electrode layer and the electrolyte layer. This increases the mechanical strength of the unit cell and makes it easier to handle when assembling the battery.

Examples thereof will be described below.

FIG. 1 is a sectional view of a unit cell embodying the present invention. In the figure, 1 is a negative electrode layer, 2 is an electrolyte layer, 3 is a positive electrode layer, and 4 is an electrode reinforcing body. Each of these layers is integrally press-molded to constitute the unit cell 5. The electrode reinforcement 4 must be interposed between the electrolyte layer 2 and the positive electrode layer 3. For the purpose of reinforcing the electrode, the reinforcing body may be placed on the surface of the negative or positive electrode, but if the reinforcing body is located on the surface of the negative or positive electrode, the unit cell formed in one piece may warp due to pressure. It was recognized that the disadvantage was that it caused
This seems to be because there is a difference in the extension of the reinforcement body and the unit cell structure due to pressurization. Warped unit cells were difficult to stack, and could crack and cause short circuits. This drawback could be improved by interposing the electrode reinforcement between the electrolyte layer 2 and the positive electrode layer 3 and embedding it within the unit cell.

0.2g of lithium-silicon alloy as negative electrode raw material powder, 200 mesh stainless steel as electrode reinforcement, 0.1g of positive electrode mixture mainly composed of iron disulfide as positive electrode raw material powder, and eutectic salt of LiCl-KCl and magnesium oxide. Using 0.3 g of the electrolyte raw material powder of the mixture, a unit cell with a diameter of 24 mm was obtained by pressure molding at a pressure of 2 t/cm ² . The thickness of the cell is 0.8
mm, and no warpage was observed.

FIG. 2 is a cross-sectional view of a thermal battery in which unit cells are stacked. In the figure, 5 is each stacked unit cell,
Reference numeral 6 denotes a heat generating agent which is alternately stacked with the unit cells 5.
7 is a negative terminal, and 8 is a positive terminal. Reference numeral 9 denotes an igniter, and when an instantaneous current is applied to the ignition terminal 10, the igniter 9 ignites, ignites the exothermic agent 6, and activates the battery. 11 is a heat insulator for keeping the battery warm, and 12 is a battery container.

The electrode reinforcing body used in the present invention preferably has a large pore size so as not to adversely affect the internal resistance of the battery. For example, nets, expanded nets, foamed metals, punched metals, porous sintered bodies, etc. are all suitable. Preferable materials include chromium, niobium, molybdenum, tungsten, and stainless steel. Since the unit cell manufactured according to the present invention includes an electrode reinforcing body inside, it has high mechanical strength and is easy to handle. Conventionally, unit cells have low mechanical strength, making them extremely susceptible to breakage, and it has been difficult to assemble unit cells unless they are stacked to a thickness of 1.5 mm or more. According to the present invention, it is possible to reduce the thickness of the unit cell to 1 mm or less even including the electrode reinforcing body, and it has become possible to manufacture a higher voltage thermal battery with the same volume. Furthermore, since the three layers are integrally molded, it also has the advantage of being easy to stack.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a unit cell of the present invention, and FIG. 2 is a sectional view of a stacked thermal battery. DESCRIPTION OF SYMBOLS 1... Negative electrode layer, 2... Electrolyte layer, 3... Positive electrode layer, 4... Electrode reinforcing body, 5... Unit cell, 6... Exothermic agent, 7... Negative electrode terminal, 8... Positive electrode terminal, 9 ……
Ignition tool, 10...Ignition terminal, 11...Insulator,
12...Battery container.

Claims (1)

[Claims] 1. A thermal battery comprising a unit cell 5 configured by integrally press-molding a negative electrode raw material powder using a lithium alloy, an electrolyte raw material powder, and a positive electrode raw material powder using a sulfide into three layers. In this case, the unit cell 5 includes an electrode reinforcing body 4 between the positive electrode layer 3 and the electrolyte layer 2, and the electrode reinforcing body 4 is made of a corrosion-resistant metal such as chromium, niobium, molybdenum, tungsten, or stainless steel. A thermal battery characterized by being made of a mesh, an expanded mesh, a foamed metal, a punched metal, or a porous sintered body.