Towards high-performance anodes: Design and construction of cobalt-based sulfide materials for sodium-ion batteries

Sodium-ion batteries are increasingly becoming important in the energy storage field owing to their low cost and high natural abundance of sodium. Cobalt-based sulfide materials have been extensively studied as anode materials owing to their remarkable Na storage capability. Nevertheless, the application of cobalt-based sulfides is hampered by their serious capacity degradation and unsatisfactory cycling stability due to severe structural changes during cycling. Therefore, it is important to comprehensively summarize advances in the understanding and modification of cobalt-based sulfides from various perspectives. In the present review, recent advances on various cobalt-based sulfides, such as CoS, CoS2, Co3S4, Co9S8, NiCo2S4, CuCo2S4, and SnCoS4, are outlined with particular attention paid to strategies that improve their sodium storage performance. First, the mechanisms of charge storage are introduced. Subsequently, the key barriers to their extensive application and corresponding strategies for designing high-performance cobalt-based sulfide anode materials are discussed. Finally, key developments are summarized and future research directions are proposed based on recent advancements, aiming to offer possible fascinating strategies for the future promotion of cobalt-based sulfides as anode materials applied in sodium-ion batteries.