Regulating anion coordination and polymer segmental dynamics to accelerate Li ion transport in single-ion conducting solid polymer electrolytes for lithium metal batteries

Single-ion conducting solid polymer electrolytes (SICSPEs) offer a promising route towards safe solid-state lithium metal batteries, yet their Li + conduction remains limited by sluggish Li + dissociation from immobilised anions and subsequent migration through polymer matrices. Herein, we report a dual-regulation strategy that couples anion coordination-environment engineering with polymer segmental dynamic activation to accelerate Li + transport. By enabling the in situ growth of zeolitic imidazolate framework-8 (ZIF-8) within a poly(ethylene glycol) methyl ether methacrylate-2-acrylamido-2-methylpropane sulfonic acid (PEGMEM-AMPS) copolymer matrix, Lewis acid-base interactions are established between the Lewis-acidic Zn centres of ZIF-8 and immobilised sulfonate groups. These interactions weaken Li + -sulfonate association and promote Li + dissociation, while ZIF-8 simultaneously suppresses ethylene oxide crystallinity and enhances segmental dynamics to facilitate Li + migration. The resulting SICSPE delivers a high Li + conductivity of 6.48 × 10 −3 S cm −1 , a Li + transference number of 0.95, and a wide electrochemical stability window of 5.9 V. Solid-state LiFePO 4 //Li cells employing the as-synthesised SICSPE demonstrate promising rate capability and long-term cycling stability with dendrite-free lithium metal deposition. This work highlights the proposed dual-regulation strategy as an effective design principle for overcoming coupled ion-dissociation and ion-migration limitations in high-performance SICSPEs for solid-state lithium metal batteries.