Mixed transition metal phosphides: recent progress and frontiers in secondary batteries and supercapacitors

Metal phosphides, which have been extensively explored for energy storage applications such as batteries and supercapacitors, possess unique physicochemical, morphological, and electrochemical properties. Among other uses, applying mixed transition metal phosphides (MTMPs) as active electrode materials for electrochemical energy storage devices remains understudied. It faces a number of significant challenges that necessitate the development of viable methodologies demonstrating controlled morphology, crystallinity, high selectivity, and the desired yield. In this context, a careful examination of the underlying reaction processes and controlled synthesis of electrode materials based on MTMPs can provide deeper insights into the practical realization of intended applications. This review aims to provide a detailed study of recent developments in synthesis techniques for the tunable and tailored engineering of the structural, morphological, and electrochemical properties of MTMPs. MTMPs have garnered significant interest due to their enhanced electrochemical properties. The advanced electrochemistry of MTMPs, compared to their monometallic counterparts, is also analyzed in this review, particularly when they are employed as active materials in supercapacitors and secondary batteries. Additionally, we present the energy storage applications of MTMPs in secondary batteries, including Zn-air batteries, Na-ion batteries, and Li-S batteries, with a specific focus on how the characteristics of MTMPs influence their electrochemical performance. Finally, the prospects and key challenges associated with the energy-related applications of MTMPs are emphasized, particularly regarding future innovative research in this expanding field.