ZnCoS/ZnCoLDH lamellar core-shell materials for high-performance asymmetric supercapacitors

The imperative for supercapacitors with elevated energy densities in contemporary energy storage applications is addressed by leveraging the high redox potential and theoretical capacitance of transition metal sulfides (TMSs). Despite their promise, TMSs often confront challenges such as diminished electrical conductivity and substantial volumetric expansion, which can degrade performance. This manuscript details the synthesis of ZnCoS nanosheets via a hydrothermal sulfurization process of ZnCo-MOF precursors, followed by the precise electrodeposition of ZnCo-LDH to form a uniformly dense outer layer, yielding a core-shell structured ZnCoS/ZnCo-LDH composite. This architecturally distinct core-shell configuration has been meticulously engineered to transcend the electrochemical limitations of its constituent materials, manifesting in an enhanced specific capacity of 248.9 mA h g −1 (2240 F g −1 ) at a current density of 1 A g −1 , and an exemplary capacity retention of 77.9 % post 5000 cycles. Furthermore, the ZnCoS/ZnCo-LDH//AC asymmetric supercapacitor, integrated with activated carbon (AC) as the anodic material, achieves an energy density of 36.4 Wh kg −1 at a notable power density of 850 W kg −1 . Upon advancement to a quasi-solid-state flexible supercapacitor configuration, the device sustains the rotation of a miniature windmill, underscoring its prospective utility within energy storage systems.