Recent progress of NiCo2S4-based electrodes materials for supercapacitor

Supercapacitors (SCs) have been intensively studied in energy storage because of excellent power density, exceptional stability, long cycle lifetimes and eco-friendly properties. The electrode material is an important factor affecting the performance of supercapacitors. NiCo2S4 has been widely studied as SCs electrode material owing to preeminent specific capacitance, tunable electronic structure and excellent cycling stability. However, the application of NiCo2S4 is hampered by their inherent low conductivity and charge/discharge volume expansion. Tuning electronic structures of NiCo2S4 or building heterogeneous structures with other materials are effective approaches to address these issues. Therefore, it is of great significance to comprehensively summarize advances and modification strategies of NiCo2S4-based electrode materials from various perspectives. This review summarized recent advancements in NiCo2S4-based electrode materials on SCs. Firstly, we briefly introduced the crystal structure, electrochemical energy storage characteristics and electrochemical energy storage mechanism of NiCo2S4 materials. Then, based on two major modification ideas of defect engineering and material recombination, we discussed and summarized several modification strategies of NiCo2S4 in detail, mainly including elemental doping and surface defects, composite design with carbon materials, transition metal oxides/hydroxides/sulfides, conductive polymers (CPs) and other materials. Finally, we proposed challenges and prospects for the development of NiCo2S4-based nanocomposites as SCs electrodes.