Study on different power and cycling performance of crystalline KxMnO2·nH2O as cathode material for supercapacitors in Li2SO4, Na2SO4, and K2SO4 aqueous electrolytes

Abstract The charge/discharge, electrochemical impedance, cyclic voltammogram, and cycling behaviors of crystalline K x MnO 2 · n H 2 O as cathode material for supercapacitors in Li 2 SO 4 , Na 2 SO 4 , and K 2 SO 4 electrolytes were compared. The different power and cycling performance of K x MnO 2 · n H 2 O during charge/discharge in the three electrolytes were elucidated by analyzing its composition and structure evolution. Compared with the Li 2 SO 4 and Na 2 SO 4 electrolytes, the highest ionic conductivity of K 2 SO 4 electrolyte, the fastest charge-transfer process and slightest structural evolution of K x MnO 2 · n H 2 O during charge/discharge in the K 2 SO 4 electrolyte lead to a superior power and cycling behavior for supercapacitor application.