Composites of NiCo Layered Double Hydroxide Nanosheets and Co3S4 Nanoparticles for Asymmetric Supercapacitors

Transition metal layered double hydroxides (LDHs) with high theoretical specific capacity and abundant redox active centers are considered as ideal cathode materials for asymmetric supercapacitors, but limited specific surface area (SSA) and low conductivity hinder its electrochemical performance. Herein, layered NiCo-LDH nanosheets were synthesized by simple one-step ion exchange and co-precipitation method at room temperature using Co-ZIF-L as the metal precursor. Subsequently, Co3S4 nanoparticles were grown on NiCo-LDH nanosheets by controlling the amount of sulfur addition, thus constructing NiCo-LDH/Co3S4 composites with heterogeneous structures. The large SSA provided more active centers for the pseudocapacitance reaction, resulting in NiCo-LDH/Co3S4 obtaining high specific capacity and good rate capability (728.1 C g–1 at 1 A g–1 and 452.9 C g–1 at 20 A g–1). In addition, the assembled asymmetric supercapacitor (NiCo-LDH/S-100//AC) achieved a superior energy density (35.21 Wh g–1 at 749.98 W kg–1), showing considerable potential for practical applications.