Thermally stable bulk-type all-solid-state capacitor with a highly deformable oxide solid electrolyte

The development of all-solid-state capacitors (ASSCs) based on inorganic solid electrolytes (SEs) with high thermal stability is desired. However, because of their high cell resistance, such capacitors have lower capacitances and rate capabilities than conventional electric double-layer capacitors (EDLCs) that use aqueous solutions and organic liquid electrolytes. The high resistance is caused by the mechanical and electrochemical properties of the SE. In this study, a highly deformable Li-ion conducting oxide SE was investigated to improve the electrochemical performance of ASSCs. Bulk-type symmetric ASSCs, with a 33Li(3)BO(3)center dot 33Li(2)SO(4)center dot 33Li(2)CO(3) (LBSC) SE layer between two electrode layers of an LBSC-CNT composite, showed low resistance and were operable at 100-300 degrees C. Additionally, the highest capacitance at the highest current reported for ASSCs till date was achieved. The highly deformable SE will facilitate the design of ASSCs and expand the potential range of applications of EDLCs.