Montmorillonite Enabled Self-Healing Fluorinated Polyurethane Electrolyte with High Ion Conductivity and Interfacial Stability in Quasi-Solid Lithium Metal Batteries

Quasi-solid-state polymer electrolytes show promise for lithium metal batteries but suffer from sluggish ion transport and severe high-potential interfacial side reactions. Herein, we rationally design a fluorinated polyurethane (FTPU) matrix with dynamic hydrogen-bond networks and construct a series of exfoliated montmorillonite (MMT)-reinforced self-healing composite gel electrolytes. The soft segments provide continuous Li+ transport pathways, while the hard segments and montmorillonite nanofillers synergistically enhance the mechanical stability and promote LiF-rich solid electrolyte interphase (SEI) formation. The composite electrolyte achieves room-temperature ionic conductivity of 0.581 mS cm–1, low activation energy of 0.06 eV, wide electrochemical window of 5.38 V, and high Li+ transference number of 0.76. The corresponding quasi-solid-state lithium–metal battery incorporating this electrolyte delivers high capacity retention (80.9%) after 100 cycles at 0.2 C. This study provides important theoretical foundations and experimental support for the structural design and interface regulation of polymer electrolytes for high-performance lithium–metal batteries.