Comprehensive Insights into Aqueous Potassium‐Ion Batteries

Abstract Aqueous potassium‐ion batteries (AKIBs) with mild aqueous electrolytes can significantly mitigate the safety and environmental issues raised from traditional nonaqueous batteries, positioning them as promising candidates for grid‐scale applications. Nonetheless, the progression of AKIBs is currently impeded by the insufficient energy density, largely attributed to the limited voltage window of aqueous electrolytes. This review aims to introduce foundational knowledge about aqueous batteries, illustrates recent advancements in AKIBs, and offers valuable perspectives on designing electrode materials and optimizing electrolytes. To provide a systematic overview, the focus is on the following seven key sections: i) development history, ii) electrode materials, iii) electrolyte design, iv) current collectors, v) aqueous interphase chemistry, vi) full cell configurations, and vii) future prospects. Finally, constructive insights and suggestions are provided for the development of AKIBs with higher energy density.