Recent Progress in Electrolyte Development and Design Strategies for Next-Generation Potassium-Ion Batteries

Abstract

Rechargeable lithium-ion batteries (LIBs) have attained tremendous success and are extensively used in a wide range of fields. However, due to the scarcity and uneven geographical distribution of Li resources, its price is steadily increasing, which may limit its sustainable application in the near future. Potassium-ion batteries (PIBs) are promising alternatives to LIBs owing to the earth abundance, low cost, and eco-friendliness of potassium, and high energy density of PIBs. Although the field of PIBs has seen significant progress in the recent years, some challenges remain that limit their application, such as the severe side reactions between the electrolyte and electrodes, which result in an unstable solid electrolyte interphase, and thus, a low coulombic efficiency. Hence, designing suitable electrolytes is necessary for the development of PIBs. This review summarises the current developments in PIB electrolytes and comprehensively discusses electrolyte design strategies for four major classes of electrolytes, namely non-aqueous, aqueous, ionic liquid, and solid-state electrolytes. In addition, the effects of the properties of each class of electrolyte are discussed in detail. Furthermore, ionic liquid electrolytes, an emerging class of electrolytes, are discussed in detail with respect to PIBs. Finally, several critical issues, challenges, and prospects of PIB electrolytes are discussed, and an outlook for the future research direction of PIBs is presented.