All-solid-state asymmetric supercapacitors with solid composite electrolytes

•All-solid state supercapacitors were prepared and investigated.•Composite 0.4LiClO4–0.6Al2O3 was used as both the electrolyte and the separator.•Specific capacitance of the cells at 150 °С reached 29 F/g.

Inorganic solid electrolytes are mechanically and thermally stable and thus may be regarded as the most promising electrolytes for the development of solid-state electrochemical devices. In this work all-solid-state symmetric and asymmetric supercapacitors with the oxide electrodes LiMn1.5Ni0.45Mg0.05O4, Mn2O3, MnO2 and the composite solid electrolytes 0.4LiClO4–0.6Al2O3 were assembled and investigated. Electrode materials were prepared by mixing of oxides with solid composite electrolyte and carbon black. The cells were prepared by hot-pressing and electrochemically tested. From an analysis of galvanostatic charge–discharge curves it was shown that specific capacitance of the cells at 150 °С and the current density of 0.05 А/g reached 29 F/g corresponding to the charge capacity of 16 mА·h/g.