Recent progress in nonaqueous electrolytes and interfaces for potassium-ion batteries

Potassium-ion batteries (PIBs) with huge advantages of low cost and high energy density have been considered to be one of the most potential energy storage technologies for grid-level storage of renewable energy. As the heart of PIBs, the electrolytes demonstrate determined role in the electrochemically K-storage thermodynamics and kinetics. This review presents the recent progress on the electrolyte design for PIBs, including the solvents (organic solvents and ionic liquids), salt species and concentrations, as well as additives. Importantly, the design principles and interfacial formation mechanisms of solid-electrolyte interphases (SEI) based on electrolyte engineering and artificial SEI strategies are summarized. Subsequently, the successful manipulation of SEI on various anode materials including carbon, alloy-type, metal sulfides, and organic materials are systematically presented. Finally, the future development directions including the multiple molecular design of advanced metal salts and solvents, electrolyte solvation manipulations, as well as precise characterizations for deep reveling and understanding of K-storage electrochemistries. This review provides a broad perspective on the electrolyte designs and interfacial mechanisms for fabricating high-performance PIBs.