Bimetallic Co-Fe selenide with improved electrochemical performance for asymmetric supercapacitors

Abstract Supercapacitors (SCs) have emerged as highly promising candidates for efficient energy storage applications. In this study, a heterostructured cobalt iron selenide (CFS) composite was prepared via a scalable and cost-efficient hydrothermal method. A comprehensive investigation and optimization process was carried out for these composite materials. Morphology characterizations revealed that nanoparticles (NPs) with an approximate size of 20 ~ 30 nm were uniformly distributed in the CFS-1 composite (Co/Fe = 2:1). This unique structure created a shortened ion transport pathway at the electrode-electrolyte interface, thereby enhancing the electrochemical properties of the composites. When evaluated at a current density of 1 A g − 1 , the CFS composite exhibited a high specific capacitance of 968 F g − 1 , showcasing its outstanding electrochemical performance. Furthermore, the material exhibited enhanced cycling stability, maintaining 90.2% of its capacitance even after 8,000 charge-discharge cycles. When employed in an asymmetric supercapacitor configured as CFS//rGO, it achieved an energy density of 50.9 Wh kg − 1 at a power density of 795 W kg − 1 . Additionally, this supercapacitor retained 87% of its capacitance over 10,000 cycles. These findings underscore the considerable promise of the CFS electrode for use in advanced energy storage systems of the future.