Rare-Earth Ce DopingStrategy to Optimize the ElectrochemicalPerformance of (Ni,Co)Se2 Nanostructures for Supercapacitors

Abstract Transition-metal selenides have been widely investigated as promising candidates for energy-storage electrodes, benefiting from their intrinsic electronic transport capability and considerable theoretical charge-storage capacity. Despite their advantages, the practical utilization of these materials remains challenging because of sluggish kinetics and poor cycling durability. To overcome these challenges, this study introduced rare-earth Ce into (Ni,Co)Se2 and successfully synthesized Ce-doped (Ni,Co)Se2 nanomaterials. The incorporation of Ce refined the microstructure, resulting in a more porous architecture with an enhanced number of electroactive sites. Meanwhile, the conductivity, ion diffusion kinetics, and structural stability were also improved through the synergistic effect of the Ce3+/Ce4+ redox pairs. The 5% Ce-doped electrode reveals a capacitance of 1928.7 F g–1 (964.4 C g–1) at 1 A g–1 and sustained 85.3% of its initial value after 8000 cycles. The fabricated device delivered an energy density of 87.7 Wh kg–1 at 800 W kg–1. This research offers valuable insights and experimental support for the design of energy-dense and long-lasting supercapacitor electrodes.