Dual-Ion Confined-Region Channels Enable Rapid Ion Transport for All-Solid-State Lithium Metal Batteries

Solid polymer electrolytes (SPEs) have attracted extensive attention owing to their flexibility and interfacial compatibility, offering a potential solution to interfacial issues in all-solid-state batteries (ASSBs). However, strong Li⁺-polymer coordination and inefficient ion-conducting pathways result in sluggish ion transport, which significantly hinders the advancement of ASSBs. Herein, we propose a dual-ion confined region strategy for preparing solid-state electrolytes with high ionic conductivity. An ionic phase-separated solid-state electrolyte (IPSE) with unique dual-ion confined-region conduction pathways and abundant ion transport sites is constructed by copolymerizing ionic monomers with incompatible properties. Furthermore, the ionic components promote lithium salt dissociation, offering more mobile Li⁺, whereas the competitive coordination of Li⁺ with anionic and cationic monomers weakens the interaction between Li⁺ and transport sites. Consequently, the IPSE electrolyte exhibits a high ionic conductivity of 1.2 mS cm^-1 and a Li⁺ transference number of 0.78 at 25 °C. The Li||IPSE||Li symmetric batteries achieve stable cycling for over 2000 h at 0.2 mA cm^-2 and 0.2 mAh cm^-2. The Li||IPSE||LFP batteries maintain over 92% capacity retention after 200 cycles. This work provides an innovative strategy for constructing high-performance all-solid-state batteries with fast ion transport.