Room-temperature solid-state sodium/sulfur battery

Solid-state sodium/sulfur batteries using polyvinylidene-fluoride-hexafluoropropene (PVDF) polymer electrolyte were prepared and tested at room temperature. Solid sodium/sulfur batteries may be composed of solid-composite-type sulfur electrodes, sodium metal electrodes, and PVDF gel polymer electrolyte. The PVDF gel polymer electrolyte with tetraglyme plasticizer and NaCF 3 SO 3 salt had a high sodium ion conductivity of 5.1 X 10 -4 S cm -1 at 25°C. During the first discharge, the sodium/sulfur battery showed two plateau potentials of 2.27 and 1.73 V, respectively. The first discharge capacity was 489 mAh/g sulfur at room temperature, which was similar to the high temperature battery. The discharge capacity drastically decreased by repeated charge-discharge cycling, and remained at 40 mAh/g after 20 cycles.