Recent progress of Ni3S2-based nanomaterials in different dimensions for pseudocapacitor application: synthesis, optimization, and challenge

Electrochemical supercapacitors have attracted tremendous interest as promising sustainable energy storage devices to complement batteries because of their unique features, such as high specific power, fast charge-discharge rates, long life span, and favorable operational safety. Recently, transition metal sulfides, especially Ni3S2-based materials, have emerged as promising active candidates for high-performance pseudocapacitors. Nevertheless, little attempt has been made to provide a comprehensive understanding of advancement in this field. Thus, this review provides the latest progress of Ni3S2-based electrode materials for pseudocapacitor applications. The fundamentals of supercapacitors, including the charge storage mechanism, key parameter calculations, and performance evaluation, are first presented. Afterwards, the conventional synthetic methodologies for the preparation of Ni3S2-based materials of different dimensions and advanced design strategies are summarized to enhance the electrochemical performance of Ni3S2-based pseudocapacitive materials, including dimension control, structure regulation, metal doping, and carbon material support. Finally, the major challenges and future directions in improving the pseudocapacitor performance and stability of Ni3S2-based materials are proposed. This review article is expected to provide fundamental insights and guide the rational design and synthesis of next-generation Ni3S2-based pseudocapacitive materials for practical applications.