JPS609067A - Sodium-sulfuric battery - Google Patents

Abstract

PURPOSE:To heighten the safety of a battery, by disposing a sodium reservoir on the top of a solid electrolytic tube, while installing a fully hermetically sealed metallic vessel filled up with a substance to be turned into inert gas or high temperature gas, in the lower part of the said reservoir. CONSTITUTION:A metallic vessel 15 consisting of a low-melting point metal or the like is installed inside a solid electrolytic tube 1 so as to be broken down with a direct reaction of heat between a negative pole active material 11 and a positive pole active material 6, while inside the metallic vessel 15, materials of inert gases such as nitrogen, argon, etc., and sodium azide being gasified into the inert gas at high temperature are filled up and fully sealed up. When a crack happens in the solid electrolytic tube 1, if fused sulfur and sodium directly react, the metallic vessel 15 is broken down the heat produced whereby the inert gas inside is forced out. With pressure of this discharged gas, a sodium interconnecting passage 19 is reversely pushed up from downward by the fused sodium in consequence, and therefore feed of the fused sodium from a sodium reservoir 16 comes to a stop so that continuous direct reaction never happens there.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode chamber structure of a sodium sulfur battery.
The purpose is to improve battery safety by 6 hours.

The structure of a conventional IJ Umu sulfur battery is explained with reference to FIG. 1. A cathode auxiliary cauterization 6 is provided at the upper end of a sodium ion conductive solid electrolyte tube 1 made of β-alumina, β'-alumina, etc. An α-alumina ring 2 serving as an electrically insulating member is glass-bonded, and an anode cover 4 is thermo-pressure bonded to the bottom surface of the anode lid 4 via an aluminum ring under high temperature and pressure. A battery device 5 made of a molten sulfur-resistant metal and serving as a hyperpyroelectric material is welded to the anode lid 4, and an anode active material 6 made of fibers such as graphite or carbon impregnated with sulfur and molded is used as an anode conductor. material 7 is arranged, solid electrolyte tube 1
A felt made of graphite or carbon, which also serves as a cushioning material 8, is disposed at the bottom of the cushion. A bottom cover 9 is welded to the bottom of the battery container 5 in a solid wall or in an inert gas.
The polar chamber is sealed. On the other hand, regarding the cathode chamber, a sodium communication passage 10 is welded to the upper lid, a sodium container 12 filled with sodium as the cathode active material 11 and having an inert gas chamber at the top is inserted into the solid electrolyte tube 1, and a sodium container 12 is inserted into the solid electrolyte tube 1. The negative electrode 14 to which the terminal 13 is welded is vacuum-sealed by welding the negative electrode auxiliary lid 6 to the negative electrode auxiliary cover 6 in a vacuum. When the battery having the above configuration is heated to an operating temperature of about 300 N550°C, the sodium 11 in the sodium container 12
is melted and is supplied from above through the sodium communication path 10 by the gas pressure in the upper space inside the container 12 to fill the gap between the solid electrolyte tube 1 and the container 12. In such a state, if a crack occurs at the joint with the solid electrolyte tube 1 or the a-alumina ring 2 due to thermal interference, mechanical impact, or non-uniformity of current distribution, the anode conductive material 7 The molten sulfur 6 and molten sodium 11 in the container come into contact and a direct reaction occurs, and the heat generated at that time (for example, several kcal, 1 to several hundreds of kcal) destroys the container 12 and further damages the inside of the container 12. The large amount of molten sodium directly reacts with molten sulfur, causing complete destruction of the battery, and also the destruction of adjacent batteries due to thermal effects.

The present invention solves the above-mentioned problems, and will be explained in detail with reference to Examples below. To explain the embodiment shown in FIG. 2, 1 is a solid electrolyte tube, 2 is an α-alumina ring, 6' is a cathode cover made of aluminum coated steel,
It is thermo-pressure bonded to the alumina ring 2. 4 is the anode lid;
5 is a battery container, 6 is an anode active material, 7 is an anode conductive material, 8 is a cushion material, 9 is a bottom cover, 11 is a cathode active material, 15 is @
A metal container made of a low melting point metal or a thin metal so as to be easily destroyed by the heat of direct reaction between the polar active material 11 and the @polar active material 6, 16 a sodium reservoir made of a molten sodium resistant metal such as stainless steel, 19 The bottom cover 17 of the sodium reservoir 16 (in this case, it also serves as the top cover of the metal container 15) and the metal container 1 are placed in the metal container 15.
5, a sodium communication passage whose open end is welded to the bottom cover 18 of the sodium reservoir 16; 21, a cathode current collecting pipe for calming the sodium dust charging/exhausting sodium passage welded to the top cover 20 of the sodium reservoir 16; and metal container 15; Inside is an inert gas such as nitrogen gas, argon gas or helium gas,
It is filled with a substance such as sodium azide, which gasifies into an inert gas upon cooling, and is completely sealed. After disposing the above cathode structure in the solid electrolyte tube 1, sodium may be quantitatively filled through the cathode current collection pipe 21 by vacuum impregnation, and the upper end of the cathode current collection pipe 21 may be sealed, thereby forming a sodium reservoir filled with sodium. Metal container 1 comprising 16
After arranging the cathode structure consisting of 5 in the solid electrolyte tube 1,
The cathode cover 31 and the bottom cover 17 may be welded and sealed in a vacuum. When the battery configured as described above is heated to a battery operating temperature of approximately 350°C, molten sodium in the sodium reservoir 16 passes through the sodium communication path 19 and is supplied to the gap between the solid electrolyte tube 1 and the metal container 15, filling it ( Note that if sodium is filled after the cathode side is assembled, the interstitial region is filled with sodium from the beginning). When discharging, sodium moves to the anode side through the solid electrolyte 'jii and the tube 1, and according to the amount of sodium extinguished R, from within the sodium reservoir 16 through the sodium communication path 19, there is always no depletion point in the interfreezing area. supply will continue.

In addition, the supply from the sodium reservoir 16 to the cathode side is as follows:
n) The gravitational effect of IJum may be used, or the gas pressure effect obtained by filling a small amount of inert gas in the upper space of the sodium reservoir 16 may be used. During charging, on the contrary, sodium is returned from the anode chamber side and returned into the sodium reservoir 16 through the sodium communication path 19.

Next, regarding the safety effect of the battery configured as described above, if a crack occurs in the solid electrolyte tube 1, the heat generated when molten sulfur and molten sodium react directly causes the metal container 15 with a low melting point or thin wall to break down. It is destroyed and the inert gas inside is released. The released gas pressure reversely pushed up the molten sodium from below through the sodium communication path 19, stopping the supply of molten sodium from the sodium reservoir 16, and no continued direct reaction occurred.

The table below shows the results of investigating the damage status of batteries with various materials and wall thicknesses for the metal container 15 for improving safety.

In other words, if the metal is a metal with a low melting point or a thin wall, the metal container 15 will be easily destroyed, the gas inside will be released, and the subsequent supply of sodium will be stopped.

In addition, the sodium communication path 19 passes through the inside of the metal container 15 and communicates the inside of the sodium reservoir 16 with the gap area between the solid electrolyte tube 1 and the metal container 15, thereby connecting the bottom cover 17 of the sodium reservoir 16 and the metal container 15. It can also be used as a top lid and also has a sodium reservoir.
Since the sodium supply passage from 6 to the gap region can be lengthened and the flow velocity can be suppressed by changing the diameter, sodium supply can be stopped even with a slight gas pressure at the time of destruction.

In the present invention, the amount of gas, gas pressure or amount of gasified substance in the metal container and the sodium reservoir, the material, diameter and length of the sodium communication path and cathode current collecting pipe, the material, wall thickness and size of the sodium reservoir The shape of the metal container is not particularly limited and can be selected as appropriate.

As described above, the present invention includes a metal container filled with an inert gas or the like in a solid electrolyte tube, and prevents contact between the anode active material and the cathode active material due to the occurrence of cracks by using the inert gas when the metal container is broken. It suppresses the ram by pushing it back into the sodium reservoir, improving battery safety. City value is large 0

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of a conventional sodium-sulfur battery;
The figure is a longitudinal sectional view of an embodiment of a sulfur battery according to the present invention. 1...Solid electrolyte tube, 10.19...S) IJum communication path, 12...S) IJum container, 15...Metal container, 16...Sodium reservoir, 21...Cathode collection Electric pipe. Applicant Yuasa Battery Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1) In a sodium-sulfur battery with a sodium ion-conducting solid electrolyte as a cathode chamber, a sodium reservoir is arranged above the solid electrolyte, and an inert gas or a high-temperature gas is placed below the sodium reservoir. A sodium-sulfur battery contains a completely hermetically sealed metal container filled with a substance that oxidizes. 2) The sodium-sulfur battery according to claim 1, which is provided with an IJium communication path (2) communicating the inside of the metal container from the sodium reservoir. 6) The sodium-sulfur battery according to claim 1, wherein a cathode current collecting pipe, which also serves as a sodium filling and exhaust passage, is welded to the upper lid of the sodium reservoir. 4) The sodium-sulfur battery according to claim 6, wherein a sodium communication path is inserted in the top electrode current collecting vibe. 5) The sodium-sulfur battery according to claim 1, wherein the gold 8 container is made of a thin metal or a thin metal. 6) The metal container is aluminum with a wall thickness of approximately 211M or less,
Claim 5 consisting of stainless steel with a thickness of about 4 mm or less
) IJ Umu sulfur battery.