Synergistic Battery‐Type Charge Storage in CuO:Tb 3+ Nanorods for Advanced Hybrid Solid‐State Supercapacitors

Terbium‐doped copper oxide (CuO:Tb 3+ ) nanorods with different Tb 3+ dopant concentrations (1%, 3%, and 5%) were prepared as battery‐type supercapacitor electrode materials. The electrochemical behaviors of CuO:Tb 3+ electrodes depend on the Tb 3+ concentration. The CuO:Tb 3+ (3%) showed the highest specific capacity of 622.64 C/g at 1 A/g, with remarkable retention capacity of 92.6% after 10 000 charge–discharge cycles at 5 A/g. Kinetic studies of CuO:Tb 3+ electrode reveal that energy storage mechanism is strongly diffusion‐controlled, indicating battery‐type behavior. The hybrid solid‐state supercapacitor (CuO:Tb 3+ (3%)//AC) delivered maximum energy density of 33.61 Wh/kg at power density of 699.8 W/kg. The excellent electrochemical properties of CuO:Tb 3+ nanorods are attributed to the synergetic effects of experimentally observed improved oxygen vacancies, high surface porosity, and reduced charge transfer resistance. Owing to the excellent electrochemical properties, the CuO:Tb 3+ (3%)//AC supercapacitor can be utilized for lighting red light‐emitting diode for real‐time applications.