Synthesis and pseudocapacitive investigation of LiCr x Mn2-x O4 cathode material for aqueous hybrid supercapacitor

Abstract

A series of Cr-substituted LiMn2O4 samples (LiCr x Mn2-x O4, 0 ≤ x ≤ 0.3) were synthesized by a urea-assisted combustion method to enhance pseudocapacitive properties of LiMn2O4 material in aqueous electrolyte. Their structure and morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The LiCr x Mn2-x O4 and activated carbon (AC) electrode were used as the cathode and anode in hybrid supercapacitors, respectively, which capacitive properties were determined by cyclic voltammetry (CV), galvanostatic charge/discharge test, and electrochemical impedance spectroscopy (EIS) in Li2SO4 solution. The results revealed that the partial substitution of Mn3+ by Cr3+ decreased initial capacity, but it prevented capacity fading. In the working voltage of 0–1.4 V, the AC/LiCr0.1Mn1.9O4 capacitor delivered an initial specific capacitance of 41.6 F g−1 (based on the total active mass of two electrodes) at a current density of 100 mA g−1 in 1 M Li2SO4 solution. After 1,000 cycles, its capacity loss was only 1.7 %.