Construction of core-shell heterostructures Co3S4@NiCo2S4 as cathode and covalent organic framework derived carbon as anode for hybrid supercapacitors

Abstract

Structured design helps to play out the coordination advantage and optimize the performance of electrochemical reactions. In this work, hierarchical hollow microspheres (Co3S4@NiCo2S4) with unique core-shell heterostructure were successfully prepared through simple template and solvothermal methods. Thanks to the hollow structure, cross-linked nanowire arrays, and in-situ coating of zeolite imidazole framework (ZIF), Co3S4@NiCo2S4 demonstrated excellent electrochemical performance with a specific capacitance of up to 2697.7 F g−1 at 1 A g−1 and cycling stability of 80.5% after 5000 cycles. The covalent organic framework (COF) derived nano carbon, which had undergone secondary calcination and ZnCl2 activation, also exhibited excellent double-layer energy storage performance. Compared to a single calcination, the incredible increase in capacitance was up to 208.5 times greater, reaching 291.9 F g−1 at 1 A g−1 while maintaining ultra-high rate performance (81.0% at 20 A g−1). The hybrid supercapacitor, assembled with Co3S4@NiCo2S4 as the cathode and COF-derived carbon as the anode, exhibited an extremely high energy density (79.7 Wh kg−1 at 693.5 W kg−1) and excellent cyclic stability (maintained 79.3% after 10,000 cycles of 20 A g−1), further explaining the reliable and practical characteristics. This work provided reference for the structural optimization of transition metal sulfides and the high-temperature activation of COF-derived carbon.