| 摘要 |
PURPOSE:To obtain a sodium-sulfur battery having high utilization factor of cathode active material and long life by forming a cathode comprising carbon fibers impregnated with molten sulfur so as to have density gradient of carbon fibers in an axis direction. CONSTITUTION:A cathode is formed by accommodating sulfur 3 and carbon fibers 4 such as PAN carbon fibers in a container and heating at about 150 deg.C in an atmosphere of inactive gas. The cathode is divided into three pieces, for example. The piece 4a is formed by stacking n pieces of carbon fiber felts each of which has a specified thickness, and the pieces 4b and 4c are formed by stacking (n-1) pieces and (n-2) pieces of carbon fiber felts respectively. Or density gradient is formed by molding carbon felts having different length, then impregnating molten sulfur in the felts. Thereby, moving down of molten sulfur caused by gravity can be prevented. Therefore, a sodium-sulfur battery having high utilization factor of cathode active material, long life, and high energy density is obtained. |
