Design and synthesis of Co3S4@CoCH/NF for high performance asymmetric supercapacitors

Abstract

As one of the energy storage devices, supercapacitors (SCs) have the advantages of high-power density, short charging time and excellent cycle stability, and have received widespread attention. Therefore, designing and synthesizing a supercapacitor material with high energy density has become a key factor to promote the development of SCs. In this work, the inter-crosslinked Co 3 S 4 nanosheets which derived from ZIF-67 are successfully loaded on Co 2 (CO 3 )(OH) 2 nanowires (CoCH NWs) can significantly facilitate the diffusion of electrolyte ions and enhance mass/electron transfer. The obtained Co 3 S 4 @CoCH composite grows directly on nickel foam (NF) substrates without binder, which improves the conductivity of Co 3 S 4 @CoCH/NF electrode. Consequently, the obtained Co 3 S 4 @CoCH/NF electrode possesses an excellent capacitance of 2697.1 F g −1 at 2 A g −1 and outstanding rate capability (84.4 % retention at 2–20 A g −1 ). In the three-electrode system, the capacitance retention is 79.8 % after 8000 cycles at a current density of 10 A g −1 . An asymmetric supercapacitor assembled from Co 3 S 4 @CoCH/NF and activated carbon as cathode and anode respectively which has fabulous energy density of 42.2 W h kg −1 at 799.0 W kg −1 and stability (74.0 % retention after 8000 cycles). It improves that Co 3 S 4 @CoCH/NF is a promising cathode material for supercapacitors. • Co 3 S 4 are anchored on Co 2 (CO 3 )(OH) 2 nanowires (CoCH NWs) to form composites and supported on foamed nickel. • Co 3 S 4 @CoCH/NF has excellent specific capacitance and outstanding rate capability. • The introduction of CoCH NWs improves the structure of Co 3 S 4 nanosheet. • Asymmetric supercapacitor Co 3 S 4 @CoCH/NF//AC (activated carbon) exhibits great performance.