Design and fabrication of MOF-derived leaf-like Zn-Co-S nanosheet arrays decorated with Ni-Zn-P ultrathin nanostructure for hybrid supercapacitors

by Karimi, A.; Ensafi, A. A.; Rezaei, B.

Transitional Metal phosphides and sulfides are considered a promising electrode material in energy storage sources due to their high electronic conductivity, rich valences and high electrochemical activity, and excellent stability. Here, we report porous Ni-Zn-P/Zn-Co-S hybrid nanostructures on nickel foam as a novel free-binder electrode achieved via a facile three-step immersion procedure, a sulfurization process, followed by an elec-trodeposition approach consisting of leaf-like Zn-Co-S nanosheet arrays covered with ultrathin Ni-Zn-P nano-sheets. The unique multicomponent heterostructure of Ni-Zn-P/Zn-Co-S can possess the large accessible surface area, more active sites, promotes free diffusion of electrolytes, shortens the path of electron transfer in elec-trochemical reaction process, and the synergistic effect from both components, leading to better electrochemical performances. The Ni-Zn-P/Zn-Co-S electrode demonstrates outstanding electrochemical performance, including ultrahigh specific capacitance of 2803 F g  1 at 1.0 A g  1, favourable rate capability, and supreme stability with 91.3% capacitance retention after 3000 cycles.More importantly, a prototype hybrid asymmetric supercapacitor is assembled based on Ni-Zn-P/Zn-Co-S as the battery-type electrode and rGO as the capacitive-type electrode. The fabricated device has a capacitance of 94.51 F g  1 at 2.3 A g  1 and demonstrates an energy density of 30.6 Wh kg  1 at a power density of 1742 W kg  1 with a remarkably long cycle life. This work delivers a simple and innovative strategy to develop advanced binder-free electrodes as a next-generation energy storage system.

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