Microwave-assisted synthesis of a three-dimensional network ultrathin Ni3S2/NiCo2S4 nanosheets as high-performance supercapacitors

• A simple and fast microwave-assisted strategy of synthesizing Ni 3 S 2 /NiCo 2 S 4 nanosheets. • Numerous ultra-thin Ni 3 S 2 nanosheets were produced on the surface of NiCo 2 S 4 due tounequal ion diffusion. • The Ni 3 S 2 /NiCo 2 S 4 -15 electrode attained an ultra-high specific capacitance of 3299 F/g at 13.3 A/g. The advanced structural design of supercapacitor (SC) electrodes is an effective approach to enhance their performance towards energy conversion and storage. Herein, ultrathin NiCo 2 S 4 nanosheets on Ni foam (NF) with uniform Ni 3 S 2 nanocrystals were synthesised via a simple microwave-assisted sulfidation process. The cooperation of massive ultrathin Ni 3 S 2 nanocrystals and cross-linking NiCo 2 S 4 nanosheets endowed the Ni 3 S 2 /NiCo 2 S 4 /NF electrodes with a high specific capacitance of 3299 F/g at 13.3 A/g (11.5 F/cm 2 at 5 mA/cm 2 ), a remarkable rate capacity of 77% retention at 20 A/g, and cycling performance of 61% retention after 8000 cycles at 50 mA/cm 2 . This work illustrates that the Ni 3 S 2 /NiCo 2 S 4 /NF electrodes synthesised via a simple microwave-assisted method are promising anode materials in asymmetric SCs.