With the coming era of large-scale energy storage, development of next-generation non–Li-based rechargeable battery technologies is imperative. Owing to the abundance, economy, and high energy density, K-ion batteries (KIBs) have attracted much attention. However, the overlarge K-ion can greatly destroy the electrode materials during potassiation-depotassiation process, resulting in a sharp decrease of the cycle life, which will enormously restrict the applications of KIBs. Currently, one of the effective strategies is adopting potassium bis(fluorosulfonyl)imide (KFSI) to replace conventional KPF₆ as solute in electrolytes. Such KFSI-containing electrolyte can induce forming stable solid-electrolyte interphase (SEI) layer, which is in favor of the stability of electrode material after cycles. In this review, we summarize all current materials cooperated with KFSI-containing electrolytes for KIBs and attempt to provide a better understanding of the improving mechanism for K-ion storage and the effect of the unique SEI layer. In addition, some critical issues and perspectives of KFSI-containing electrolytes for K-ion storage are also discussed, which will provide a developmental direction of KIBs.

随着大规模储能时代的到来，下一代非锂基可充电电池技术的发展势在必行。由于其丰度，经济性和高能量密度，K离子电池（KIB）备受关注。但是，过大的K离子会在钾化-去钾化过程中极大地破坏电极材料，导致循环寿命急剧下降，这将极大地限制KIBs的应用。当前，一种有效的策略是采用双（氟磺酰基）酰亚胺钾（KFSI）代替传统的KPF ₆作为电解质中的溶质。这种含KFSI的电解质可以诱导形成稳定的固体电解质中间相（SEI）层，这有利于循环后电极材料的稳定性。在这篇综述中，我们总结了目前所有与KIB含KFSI的电解质配合使用的材料，并试图更好地理解K离子存储的改善机理以及独特SEI层的作用。此外，还讨论了一些用于K离子存储的含KFSI的电解质的关键问题和观点，这将为KIBs的发展提供方向。