In-situ growth of NiCo-LDH-S nanosheets with granular NiS/Co9S8 on nickel foam as self-supported electrode for high-performance supercapacitors

Self-supported electrodes with nanostructural active materials have gained extensive attention because they have low electron/ion transfer resistance, fast reaction kinetics and strong mechanical stability. Herein, NiCo-LDH-S@NF self-supported electrode is fabricated by in-situ growing NiCo-LDH-S on nickel foam (NF) in this work. Firstly, orthohexagonal Ni(OH)2 nanosheets in-situ grow on NF in alkaline solution without additional introduction of nickel source, templates or surfactant. Then, rectangular NiCo-LDH (layered double hydroxides) nanosheets array are converted from the Ni(OH)2 nanosheets by hydrothermal method. The rough NiCo-LDH-S nanosheets are finally formed via sulfuration, to provide remarkable surface area for electrochemical reaction. The as-prepared NiCo-LDH-S@NF exhibits a specific capacity of 5884 mF cm−2 at 1.0 mA cm−2 and an outstanding retention rate of 46.3 % when current density reaches up to 24 mA cm−2. Furthermore, the asymmetric supercapacitor (ASC) prepared by NiCo-LDH-S@NF and CC (commercial conductive carbon cloth) presents a maximal energy density of 0.57 mWh cm−2 at 0.9 mW cm−2, and maintains 95.45 % of capacity retention after 12,000 charge-discharge cycles. Therefore, the in-situ grown self-supported NiCo-LDH-S@NF electrodes are promising for energy storage.