Developing Dynamic Ion Transport Channels in Polymer Solid Electrolytes for High-Performance Lithium Metal Batteries

Solid polymer electrolytes (SPEs) are promising for next-generation solid-state lithium metal batteries owing to their electrochemical stability and high safety. However, limited ionic conductivity and poor interfacial stability have hindered their practical applications. To address these challenges, we propose a novel approach by incorporating trace amounts of sulfone (SL) into polyacrylic-based SPEs, purposely creating "dynamic ion transport channels." Molecular dynamics simulations and experimental validation demonstrate that the optimal incorporation of SL (in situ-SL2) precisely tunes the solvation structure, establishing dense, multipoint coordination networks via gradient ion-dipole interactions. The inherent flexibility of SL facilitates rapid conformational changes and dynamic bridging with Li⁺ ions, reducing energy barriers for Li⁺ elastic hopping and thus enhancing ionic conductivity and lithium-ion transference numbers. Detailed interfacial analysis reveals that in situ SL2 SPE promotes the formation of a stable, inorganic-rich solid electrolyte interphase (SEI), effectively suppressing the metal dendrite growth. The LFP|In situ-SL2|Li cell exhibits over 91.7% capacity retention after 2000 cycles at 3 C, highlighting a superior performance and long-term stability. This work provides valuable insights into designing high-performance SPEs for long-lifetime and safe lithium metal batteries.