Engineering of Transition Metal Sulfide Nanostructures as Efficient Electrodes for High-Performance Supercapacitors

Supercapacitors (SCs) are highly promising electrochemical energy conversion and storage devices. SCs display an outstanding power performance, excellent reversibility, long-term stability, simple operation, and high feasibility for integration into electronic devices, including consumer electronics, memory backup systems, and industrial power and energy management systems. The electrode materials determine the cell capacitance, operating voltage, power density, energy density, and time constant of SCs. Transition metal-based electrode materials (TMEMs) are among the most promising electrodes for SCs, due to their outstanding energy density, specific capacitance, and quick charging/discharging rates, in addition to their ease of preparation in a high yield from low-cost and earth-abundant resources. Binary transition metal sulfides (BTMSs) possess various advantages relative to other TMEMs, including higher storage capacity, higher electrical conductivity, excellent redox properties, better specific capacitance, quicker electron/ion diffusion, and superior reversibility with long cycle life. Herein, the inventory and the recent progress in the rational design of BTMS electrodes for SCs are deliberated, spaning from the preparation methods to the operative conditions, performance, and mechanism. To help assist in the further development of BTMS electrodes for efficient and durable SCs, current underlying challenges and possible solutions are identified and addressed, with emphasis on device performance vs BTMS type and relative merits.