Boosting the Energy Density Through In Situ Thermal Gelation of Polymer Electrolyte with Lithium‐Graphite Composite Anode

We have entered the age of renewable energy revolution. Hence, energy‐dense all‐solid‐state lithium metal batteries are now being actively researched as one of the most promising energy storage systems. However, they have not yet been a silver bullet due to the dendrite formation and interfacial issue. Here, we introduce the hybrid polymer electrolyte via a novel solvent‐free strategy as well as utilize a polymerization and gelation effect of cyanoethyl polyvinyl alcohol to achieve superior electrochemical performance. The hybrid polymer electrolyte, using cyanoethyl polyvinyl alcohol, demonstrates a stable artificial solid electrolyte interface layer, which suppresses the continuous decomposition of Li salts. Importantly, we also present the lithium‐graphite composite anode to reach the super‐high‐energy‐density anode materials. Taken together, these advancements represent a significant stride toward addressing the challenges associated with all‐solid‐state lithium metal batteries.