Engineering metal selenides for sodium-and potassium-ion batteries

Summary Battery technologies based on Earth's abundant elements are indispensable for sustainable energy storage. Sodium- and potassium-ion batteries (NIBs and KIBs) have begun to show promise as alternatives for lithium-ion batteries. Alongside the discovery of new anode materials, the last few years have seen rapidly increasing interest in metal selenides for NIBs and KIBs. This review presents a timely summary of the recent progress on using metal selenides to electrochemically store Na+ and K+. The review features the design strategies for metal selenides and discusses the roles of the strategies in addressing the current issues of applying metal selenides in NIBs and KIBs. Future opportunities are also presented to signpost open questions that are worth investigating to allow further development of metal selenides and their NIB and KIB performance. This review may shed some light on the material design for not only the electrochemical community but also wider research domains.