| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2001: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2000: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
In the present study, research on the development of molten sulfur secondary battery which is non-explosive and systematically safe was investigated. This battery consists of a mixed sulfide anode, a carbon cathode, and a molten sulfur electrolyte. In the battery, the intercalation reaction of alkali metal from the melt to the sulfide electrode is applied and no isolating materials are needed. First, the mixed sulfide such as BaTiS_3 and BaZrS_3 were prepared by the newly developed low-temperature sulfide synthesis method using sulfur melt. The synthetic conditions and the structure, composition of the these mixed sulfides were investigated as well as the stability of these materials in molten sulfur. Next, the intercalation of alkali metal into the sulfides was examined by the addition of alkali metal compounds into molten sulfur. Since the molten sulfur has an ultra high resistance between 150 and 300 ℃, the increase of the electrical conductivity was examined by the addition of alkali metal compounds into the sulfur melt. The electrical conductivity was measured from melting point to 250 ℃ by using two pole ultra high resistance meter. The electrical conductivity increased with increasing amount of the added compounds. The addition of alkali metal was found to be more effective compared with other compounds, such as chlorides, sulfates and azides. When the melt was ultrasonically treated, the conductivity drastically increased and attained to the level of practical use. Based on the obtained results, the molten sulfur secondary battery was evaluated by optimizing the components and conditions for electrodes and electrolytes.
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