Se vacancy-enabled ZIF-derived multimetal selenides: crafting high-performance battery-type supercapacitors

Metal-organic framework (MOF) materials, as electrodes for supercapacitors, have promising applications, but their conductivity and capacitance performance are critical limitations to their practical use. By constructing rational structures and incorporating various active materials, the conductivity and capacitance performance of MOF-derived materials can be significantly enhanced. This study presented the application of trimetallic selenide electrode materials V_a-ZnSe/NiCoSe₂ in supercapacitors prepared through sequential Ni²⁺ etching, selenization and NaBH₄ reduction of ZIF-8@ZIF-67 core-shell structure. The results exhibited that an appropriate number of Se vacancy defects effectively enhanced the specific capacitance and conductivity of the material, thereby improving the performance of supercapacitors. When NaBH₄ concentration was 1 M, the obtained V₁-ZnSe/NiCoSe₂ electrode material presented excellent supercapacitor performance with a maximum specific capacitance (capacity) of 1563 F·g^-1 (705.5 C^.g^-1) at a current density of 1 A·g^-1 as well as high rate capability and long-term cycling stability. Additionally, the assembled V₁-ZnSe/NiCoSe₂//AC asymmetric supercapacitor delivered a high energy density of 41.9 Wh·kg^-1 at a power density of 750 W·kg^-1, highlighting its great potential in the field of energy storage.