Engineering self-supported metal selenide architectures for high-energy supercapacitors

Transition-metal selenides are considered emerging electroactive materials for high-performance supercapacitors owing to their high electrical conductivity, multivalent redox chemistry, and tunable electronic structures. The distinct features facilitate rapid charge-transfer kinetics and higher charge-storage efficiency, demonstrating metal selenides as potential pseudocapacitive and battery-type electrodes. Moreover, Electrode design is a key factor for assessing the electrochemical performance of supercapacitors. Notably, developing self-supported metal selenide-based electrode formations effectively boosts the electroactive material-current collector interface and improves charge transfer kinetics, resulting in improved durability of electrodes. Recent advances in materials synthesis and interfacial engineering have enabled the direct integration of metal selenide nanostructures onto conductive frameworks. Controlled fabrication techniques facilitate the production of ordered nanoarrays and hierarchical designs. The unique nanostructures offer consistent electron transport channels, reduced ion diffusion lengths, and increased mechanical flexibility, ultimately resulting in improved rate capability and cycling stability. This review explains the charge-storage mechanism in metal selenides and the rationale for selecting self-supported electrode configurations. The structural dependence of the electrochemical performance of metal selenide-based electroactive materials, such as hybrid materials and multicomponent heterostructures, is systematically analyzed. Finally, the challenges and future perspectives of metal-selenide-based materials for the development of self-supported supercapacitors in next-generation sustainable clean energy storage technologies.