JPS60221972A - Sodium-sulfur battery - Google Patents

Abstract

PURPOSE:To increase utilization factor of positive active material by arranging a porous metal which is corroded by sulfur between a cathode electric conductive material and solid electrolyte. CONSTITUTION:A metallic material 9 at least whose surface is changed to sulfide is arranged between a solid electrolyte tube 1 and a cathode electric conductive material 6. Passages in which sodium ions can move to a cathode active material 5 are formed in the metallic material 9. To forming these passages, the metallic material is formed in porous form such as fiber, textile fabric, sinter, plate-shaped fibrous body or sinter or net having numberless holes or slits. The metallic material 9 consists of metal of alloy such as aluminium, copper, nickel, iron, zinc, tin, stainless steel, or magnetisum whose surface or the entire part is corroded by sulfur or sodium polysulfide, but iron is most preferable among them.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anode for a sodium-sulfur battery.
By placing a sulfur-corrosive porous metal between the anode electrode leg and the solid electrolyte, the utilization rate of the anode active material is increased.

The anode chamber of a sodium-sulfur battery is made of sodium ion conductive β'-alumina, β
- The outside of the solid type FF+44 tube 1 made of alumina etc. is used as an anode chamber, and the lower surface of the α-alumina ring 2 glass-bonded to the upper end is welded to the anode lid 3 which is thermo-pressure bonded. An anode 1h conductor 6 impregnated with an anode active material 1jI5 (sulfur or polysulfide) is disposed between the battery container 4 and the solid electrolyte tube 1, and a graphite felt disk 7 is arranged at the bottom. It is constructed by welding the lid 8 to an electrode <11I4. Does it release at battery operating temperature of 300°C to 570°C? At 1f5, the cathode active material is used.) IJium is ionized and passes through the solid electrolyte tube 1.
reacts with the group 11 to form the product Na2Sx, and the anode active material 5 in the anode 1 reacts with Na2S2. z～3
Discharge stops when the temperature reaches o. During charging, the released 71 (sulfur in the product) IJum is returned to the cathode chamber, but as shown in Figure 2, in the case of immediate discharge, all the sulfur becomes the final discharge composition, and the theoretical capacity value is observed. , 1-+I cycle charging could only charge about 70%. Furthermore, the subsequent charging and discharging cycles showed a similar tendency, and the charging ■ at the 150th cycle was approximately 54% of the Ripu 0 capacity value, which was positive II! i
The utilization rate of the j active material was approximately 54%, and it was confirmed from the results of other batteries K K'A that it would further decrease in subsequent cycles.

The present invention improves the above-mentioned decrease in the utilization rate of the anode active material, and as shown in the enlarged view of the main part in FIG. 6 and the enlarged perspective view of the main part in FIG. 4, the solid electrolyte tube 1 and the anode conductive material 6 are A metal material 9 whose surface is at least sulfurized is provided between them.

A passage is provided in the metal phase 9 so that the anode active material*5u sodium ions can move.

For channel formation, the shape of the metal phase can be changed to a porous material, such as a fibrous material (felt-like non-woven fabric, non-woven fabric made of pressure-fired fibers, etc.), a knitted material, a sintered material (+1: )fB, or a suitable filter material. . ! In the case of 5i fiber, the utilization rate of one cycle poem was the best at 94% to 96%.

86% to 90% for braided bodies, 87% to 92% for sintered bodies
, 72% to 76% for hole or slit, 75 for 1 net
% to 83%. The material of the metal phase 9 is aluminum, copper, iron, iron, etc., which are easily corroded by sulfur and sodium polysulfide.
, t'Q, t+sz Gold P of stainless steel, magnesium, etc.
5 or alloy, consisting of 11 or lli body, especially? J
(It is desirable to have a donation of . Also, Friday) The thickness of April 9th is preferably 2 or less R. If the metal is sulfurized if it is 2M or more, the effective amount of sulfur in the anode active material 5 that contributes to the 1) cell reaction will be reduced, the battery capacity will be reduced, the thickness of the base sulfide layer will increase, and the ) 'J '1' 1. Blocks the movement of IJ umuimen and increases the internal resistance of the battery. i. Stratify pond performance. Furthermore, the porosity of the metal phase 9 is also one of the above factors, but if it is about 75% to about 98% by volume, it will not affect the All you have to do is increase the amount of sulfur just in case.

This will be explained below using examples.

As the metal phase 9, i:q ash, diameter of about 25 μ, fiber length of 5 to 100 mm, 11: with average pore size of about 1
A non-Rin cloth with a thickness of 50μ and about 0.4 rM was placed on the inner surface of the anode conductive material 6, impregnated with sulfur and pressure molded, and the anode molded body divided into 24 vertical sections was used for 2/Kameike. When a charge/discharge test was conducted, as shown by the broken line in FIG. 2, almost no decrease in battery capacity was observed even after 150 cycles, and the utilization rate of the anode active material was approximately 94%. Furthermore, another feature of the present invention is that the metal material 9 is divided into at least two parts vertically, horizontally, or diagonally in order to make it easier to accommodate or mold the metal material 9 in the battery.
Furthermore, this division is the same as that of the anode conductive material 6. This makes handling easier by fixing the metal phase 9 with the positive electrode active material 5 on the surface of the positive tL + conductive material 5, and at the same time, by storing the metal phase 9 in the battery, the battery can be heated to the battery operating temperature. When the tie is moistened, 1 anode active material 5 melts,
Yang 1! The purpose is to suppress and bring the lj conductive layer 6 into contact with the surface of the solid electrolyte tube 1. The present invention having such a configuration not only improves the utilization rate of the anode active material, but also partially penetrates into the anode conductive material 6 as a muddy substance and forms an electrical resistance gradient, thereby reducing sulfur during charging. prevent the segregation of
Ha3sX → 2Na of the anode active material 5 in the anode conductive material 6
+XS reaction is further promoted. This effect becomes more pronounced as the metal material 9 becomes sulfurized, that is, as the metal material 9 undergoes charging and discharging cycles.

Further examples will be described below.

Example 1: Stainless steel felt with a fiber diameter of 8μ has a porosity of 9
Gold J-, which was pressure molded to have a thickness of 0.8 mm and has a thickness of 4.
・When using [port] 9, the instant discharge capacity was about 150 AH at 150 cycles compared to the instant discharge capacity ft156 AH.

Example 2. When a copper wire with a diameter of 0.1 ni is made into a net and the thickness is 0.4πm, positive t! IJH
The utilization rate of the active material was approximately 78% at 150 cycles.

Note that the size of the metal material 9 of the present invention varies depending on the battery shape, and there are no particular limitations on the length, rl], porosity, number of days until complete sulfidation, amount of sulfur required for sulfidation, etc.

As explained above, the present invention is effective in increasing the utilization rate of the positive electrode active material of sodium-sulfur batteries, and has great industrial value.

[Brief explanation of the drawing]

Figure 1...Longitudinal diagram of a sodium-sulfur battery Figure 2.
...Charge/discharge voltage characteristics 1a Fig. 6...Enlarged view of main parts of the battery of the present invention Fig. 4...Enlarged perspective view of main parts of the battery of the invention 1...Solid electrolyte tube 6...Anode Conductive material 5... anode active material 9
・・・Metal material input Yuasa Battery Co., Ltd. Figure 1 Figure 3 Figure 4 Figure 2 Figure 1 2:3 4 5 6 7 8 9 10 songs "1L
L time (Ilr)

Claims (1)

[Scope of Claims] (1) A sodium ion conductive solid electrolyte tube characterized in that a metal material whose surface is at least sulfurized is provided between the sodium ion conductive solid electrolyte tube and the anode electrolyte material made of graphite felt or carbon felt. sulfur battery. (2) The →-Thorium-Sulfur Tunke according to Claim 1, characterized in that the thickness of the gold Fi6fA is 2 or less. (6) IJ Umu sulfur battery according to claims 1 and 2, characterized in that the metal material is porous. (4) A feature i1'f characterized in that the gold plate is made of a fibrous body such as felt or non-woven fabric, a knitted body, a plate-like body having holes or slits, or a sintered body. Fifth
Sodium-sulfur battery as described in section. (5) The sodium-sulfur battery according to any one of claims 1 to 4, wherein the metal material is divided into at least two parts in a vertical direction, a horizontal direction, or an oblique direction. (6) The metal material is molded and fixed on the surface of the anode conductive phase by the anode active material, and is pressed against the solid electrolyte tube surface at the battery operating temperature.
The sodium-sulfur battery according to item 5. (The metal phase is aluminum, nickel, *11, iron,
The IJ Umu sulfur battery according to claims 1 to 6, characterized in that it is coated or made of a metal or alloy such as tin, zinc, lead, madanesium, or stainless steel.