Opportunities for Polymer Electrolytes in Sustaining High‐Voltage Lithium Metal Batteries

Abstract High‐voltage lithium metal batteries (HVLMBs) integrate emerging cathode materials working above 4 V (vs Li/Li + ) with high‐capacity lithium metal anode, which offer a practical solution to upgrade energy and power density of current rechargeable batteries. Replacing conventional liquid electrolytes with polymer electrolytes (PEs) further empowers HVLMBs with flexibility, processability, and enhanced safety. This is unfortunately hampered by low ionic conductivity, insufficient high‐voltage stability, and poor interfacial compatibility at the anode. This review scrutinizes multifaceted strategies toward an effective implementation of PEs in HVLMBs, spanning from molecular design, material preparation, interfacial engineering, etc. Particular attention is dedicated to electrolyte preparation and the associated polymerization mechanism. Synergistic approaches harmonizing theoretical modeling, advanced material/interface engineering, and scalable manufacturing are extensively discussed. Material‐level innovations to improve the mechanical integrity and flame retardancy of PE‐based HVLMBs are also highlighted. The reflections and insights shared in this work are expected to smooth the barriers in combining theoretical and experimental efforts, and thus spurring the realization of practical and high‐performance HVLMBs with PEs in the future energy landscape.