Rare-Earth Perovskite Reduced Graphene Oxide Nanocomposites as High-Stability Supercapacitor Electrodes

Rare-earth perovskite/reduced graphene oxide (rGO) nanocomposites were designed and characterized for their potential as electrode materials in high performance supercapacitors. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS), and cycling stability tests of six electrode materials including pure rGO, LaFeO3, LaFeO3/rGO, SmFeO3/rGO, and GdFeO3/rGO nanocomposites at an optimized 20 wt% rGO loading are presented. The electrochemical performance of the perovskite/rGO composites benefited from the synergistic effects of pseudocapacitive perovskite oxide and electrically conductive rGO, as an improved electrochemical performance relative to that of either single component was observed. SmFeO3/rGO (20 wt%) exhibited the highest specific capacitance (Cs) of 488 F g⁻¹ at 1 A g⁻¹, energy density (E) of ~68 Wh kg⁻¹, a series resistance (Rs) of only 0.45 Ω, and maintained 95% capacitance retention after 5,000 charge–discharge cycles. Coulombic efficiency for all optimized composites approached a stable value above 99.5% after 1,000 cycles. The rare-earth cation was found to play an important role in determining the charge-transfer kinetics and structural stability. These results show that rare-earth perovskite/rGO nanocomposites are promising materials for energy storage devices.