Ternary Metal Sulfides as Electrode Materials for Na/K‐Ion Batteries and Electrochemical Supercapacitor: Advances/Challenges and Prospects

Abstract Ternary metal sulfides (TMSs) have garnered significant attention as alternative electrode materials for rechargeable metal‐ion battery anodes and electrodes for electrochemical supercapacitors (SCs). With the escalating costs of lithium, research has shifted toward alternative sources like sodium‐ion batteries (NIBs) and potassium‐ion batteries (KIBs), offering cost‐effectiveness and greater natural abundance globally. However, pursuing suitable electrode materials beyond lithium‐ion batteries (LIBs), such as NIBs, KIBs, and SCs with enhanced energy and power density, remains a formidable challenge. In this context, TMSs demonstrate remarkable reversibility as NIB, KIB, and SC electrode materials, showcasing multi‐electron redox reactions, improved electronic conductivity, and higher theoretical capacities. Numerous research articles have highlighted the promising future of TMSs as electrodes for electrochemical energy conversion and storage (EECS). Nonetheless, practical applications are hindered by limitations, including structural stability during long‐standing cyclability, electronic conductivity, and scalability. This review systematically demonstrates how varying synthesis routes can tailor nanostructures and their influence on electrochemical activity. Additionally, an in‐depth literature survey is provided on the electrochemical performances of TMSs in NIBs, KIBs, and SCs and summarize recent advancements with the best available literature. Moreover, promising prospects and challenges are highlighted, expressing optimism that TMSs will emerge as pivotal electrodes for EECS.