Single-ion conductor gel polymer electrolytes enabling an anionic polymer-induced solid electrolyte interphase for dendrite-free lithium-metal batteries†

Lithium-metal batteries (LMBs) are considered some of the most promising candidates for future energy storage devices. However, the unstable electrolyte–electrode interface and the rapid lithium dendrite growth in LMBs hinder their practical application. Here, we report a three-dimensional (3D) crosslinked single-ion gel polymer electrolyte (SIGPE) with a high lithium-ion transference number and favorable interface to suppress lithium dendrite growth. The SIGPE is synthesized through a weakly interacting anion and coordinating ether oxygen segments. Molecular dynamics simulations reveal a solvated sheath-like structure [Li⁺–anionic polymer] is formed in the SIGPE, and density functional theory calculations show strong interactions between Li⁺ and anionic polymers, which allows the construction of a robust flexible electrolyte–electrode interface through anionic polymer segments. As a result, the Li‖Li symmetric cell with the SIGPE exhibits a stable overpotential after 700 h, indicating an effective suppression of lithium dendrite growth and good interfacial compatibility with the lithium anode. Notably, the as-assembled Li‖LiFePO₄ cell shows prominent cycle stability and coulombic efficiency over 300 cycles at room temperature, demonstrating the significant potential of the SIGPE in lithium metal batteries.