Quasi-solid-state lithium metal batteries achieve stable operation through self-healing sulfamide electrolytes that utilize hydrogen bonding

Quasi-solid-state polymer electrolytes (QSSPEs) are promising for high-energy lithium metal batteries (LMBs), yet suffer from unstable interphases and poor fast-charging stability. This work develops self-healing sulfamide-fluorinated ether quasi-solid electrolytes (SF-X; X = 20, 40, and 60), with the optimized SF-40 electrolyte featuring balanced molecular architecture. Its dynamic hydrogen/(H)-bonded network enables structural self-healing, while fluorinated ether nano-domains induce uniform lithium fluoride (LiF)-rich electrode interphases. SF-40 delivers a high lithium/(Li)-ion transference number (t⁺ = 0.32) and excellent plating/stripping reversibility with 99.1% Coulombic efficiency (CE) over 800 cycles. High-loading lithium-nickel manganese cobalt oxide (Li||NMC811) full cells achieve 92.0% capacity retention after 500 fast-charging cycles and 90.0% retention after 400 high-temperature cycles, outperforming counterpart electrolytes. This molecular modulation strategy affords robust, fast-charging compatible QSSPEs for practical LMBs.