Hydrogen‐Bonded Organic Frameworks (HOFs) Composite Polymer Electrolyte Enables the Stable Long‐Term Cycling of Lithium Metal Batteries with High‐Voltage Cathode

Abstract Solid‐state lithium batteries have attracted significant interest due to their potential to enhance the safety and energy density of modern energy storage systems. However, challenges such as low ionic conductivity and poor interfacial compatibility have hindered their widespread adoption. In this study, a novel hydrogen‐bonded organic framework (HOF) composite polymer electrolyte (HCPG@SPE) is developed by integrating trimesic acid and melamine‐based HOFs with a natural polymer matrix composed of gelatin and chitosan. The hydrogen‐bonding interactions between the matrix and HOF in HCPG@SPE impart remarkable mechanical strength and thermal stability. Additionally, due to the weak interactions between HOF and lithium‐ions, and its anion adsorption capacity, HCPG@SPE effectively generates more free lithium‐ions, facilitating their migration while inhibiting anion movement. Electrochemical tests revealed that HCPG@SPE exhibited high ionic conductivity (5.74 × 10⁻ 3 S cm⁻¹ at 30 °C), a favorable lithium‐ion transference number (0.71), and an extended electrochemical stability window (5.4 V). Additionally, lithium metal batteries utilizing this electrolyte achieved outstanding performance, with LFP| HCPG@SPE| Li cells retaining 98% capacity after 1000 cycles at 5 C, and NCM811| HCPG@SPE| Li cells demonstrating stable cycling for 700 cycles at 1 C. The results suggest that the HOF‐based composite electrolyte holds significant promise for next‐generation high‐performance solid‐state lithium batteries.