High-temperature supercapacitor with a proton-conducting metal pyrophosphate electrolyte

Expanding the range of supercapacitor operation to temperatures above 100 degrees C is important because this would enable capacitors to operate under the severe conditions required for next-generation energy storage devices. In this study, we address this challenge by the fabrication of a solid-state supercapacitor with a proton-conducting Sn0.95Al0.05H0.05P2O7 (SAPO)-polytetrafluoroethylene (PTFE) composite electrolyte and a highly condensed H3PO4 electrode ionomer. At a temperature of 200 degrees C, the SAPO-PTFE electrolyte exhibits a high proton conductivity of 0.02 S cm(-1) and a wide withstanding voltage range of +/- 2 V. The H3PO4 ionomer also has good wettability with micropore-rich activated carbon, which realizes a capacitance of 210 F g(-1) at 200 degrees C. The resulting supercapacitor exhibits an energy density of 32 Wh kg(-1) at 3 A g(-1) and stable cyclability after 7000 cycles from room temperature to 150 degrees C.