The potential of solid-state potassium-ion batteries with polymer-based electrolytes

As a potential substitute for traditional nonaqueous organic electrolytes, polymer-based solid-state electrolytes (SSEs) have the advantages of high safety, flexibility, low density, and easy processing. In contrast, they still face challenges, such as low room-temperature ionic conductivity, narrow electrochemical windows, and poor mechanical strength. To realize the practical application of all-solid-state alkali metal ion batteries, there has been a lot of research on modifying the chemical composition or structure of polymer-based SSEs. In this review, the transport mechanism of alkali metal ions in polymer SSEs is briefly introduced. We systematically summarize the recent strategies to improve polymer-based SSEs, which have been validated in lithium-ion batteries and sodium-ion batteries, including lamellar electrolyte structure, dual salts hybridization, oriented filler alignment, and so on. Then, taking the unique properties of potassium metal and potassium ions into consideration, the feasibility of potassium-ion batteries for practical use enabled by these novel modification methods is discussed.