Sulfidation of ZIF-derived templates for preparing (Zn₀.₂Co₀.₈)(OH)₂/ZnₓCo₁₋ₓS heterostructures toward highperformance supercapacitors

Abstract

The development of supercapacitor electrodes with superior performance is aimed at addressing energy storage challenges. Transition metal sulfides (TMS) are often utilized as electrode materials in such research activities, typically obtained through the direct sulfidation of layered double hydroxides (LDH). In this study, we adopted a methodology involving the growth of zeolitic imidazolate frameworks (ZIF) onto LDH, followed by sulfidation to produce rough nanosheets of (Zn₀.₂Co₀.₈)(OH)₂/ZnₓCo₁₋ₓS heterostructures. The results reveal that the nanoflowers, consisting of interconnected rough nanosheets obtained post-sulfidation of ZIF, exhibit an increased number of active sites. In threeelectrode measurements, a remarkable specific capacitance of 9.63 F cm⁻² was achieved at a current density of 2 mA cm⁻², with a capacitance retention ratio of 83.9% after 5000 cycles at a current density of 20 mA cm⁻². When configured as a two-electrode device, it demonstrated extremely high energy density (E) and power density (P) at a current density of 2 A g⁻¹, with E reaching 145.78 Wh kg⁻¹ and P achieving 1585 W kg⁻¹. Furthermore, after 10,000 charge-discharge cycles at a current density of 10 A g⁻¹, the capacitance retention remained at 85%.