摘要 |
PURPOSE:To prevent the solid electrolyte from being broken by impurities by performing belt purification to remove the impurities contained in sulfur or sodium polysulfide constituting the positive active material. CONSTITUTION:After sulfur or sodium polysulfide is molten, the molten sulfur or sodium polysulfide is poured onto an auxiliary conductive material such as graphite which is placed in a purification device to make the material to be impregnated with the molten substance. Next, the molten sulfur or sodium polysulfude held in the material is solidified and the belt purification is successively performed on the material placed horizontally. This treatment adjust the content of impurities such as calcium or potassium to a level of, for example, at most 5ppm to prevent the solid electrolyte from being broken by the impurities, thereby increasing the life of the battery. |