A polymer electrolyte with a thermally induced interfacial ion-blocking function enables safety-enhanced lithium metal batteries

Lithium metal batteries (LMBs) have recently been revitalized as one of the most promising electrochemical energy storage systems, owing to the ultrahigh specific capacity (3860 mAh g−1) and ultralow potential (−3.04 ​V vs. standard hydrogen electrode) of lithium metal anodes. However, safety hazards originating from lithium dendrite growth and pulverization during cycling and thermal stimulation present significant challenges to the practical application of LMBs. To address this issue, we have developed an in situ polymer electrolyte with thermally induced interfacial ion-blocking ability. We demonstrate that the repolymerization and deposition of residual vinylene carbonate in the as-prepared electrolyte under thermal abuse predominantly results in thermally induced ion blocking at the solid electrolyte interface, thus achieving superior LMB safety. The developed polymer electrolyte also yields superior cyclability in LMBs. This design philosophy provides a good paradigm for improving the safety of LMBs.