Reagents assisted Mg-doped CeO₂ for high-performance energy-storage applications

A novel Mg-doped CeO₂ electrode materials were prepared by simple and cost effective hydrothermal method by using three different reagents (ammonium fluoride, potassium hydroxide and hexamethylenetetramine). Successful preparation was confirmed by using various characterizations. In three electrode setup, CeO₂: Mg-NH₄F, CeO₂: Mg-KOH, and CeO₂: Mg-HMTA showed a high specific capacitance of 432, 275 and 221 F g⁻¹ at 1 A g⁻¹ respectively. After 10,000 continuous cycles of charging and discharging, only 11% fade in the specific capacitance was observed for CeO₂: Mg-NH₄F. Moreover, CeO₂: Mg-NH₄F was used as a positive electrode and (activated carbon) AC as a negative electrode for asymmetric supercapacitor (ASC) device. The highest specific capacity of 130C g⁻¹ at 1 A g⁻¹ was obtained for ASC device. ASC device delivered a high energy density of 28.8 Wh kg⁻¹ at a power density of 775 W kg⁻¹. ASC device showed an excellent retention of 83% and an outstanding coulombic efficiency of 99% after 9000 cycles. All these attractive results suggest the importance of this electrode material towards practical applications.