Room-Temperature,\nAll-Solid-State Electrolyte Based\non a Polymeric Single-Ion Conductor

Solid-state single Li<sup>+</sup>-ion conductors are\nemerging as\na superior alternative to conventional liquid electrolytes, offering\nenhanced safety and energy density for secondary lithium batteries.\nHowever, their applications often needed additional solvent due to\nthe relatively low conductivity and poor interfacial contact between\nthe solid-state electrolyte and active materials. In this study, we\nsynthesize a new solvent-free, free-standing single-ion conductor\nwith an ethylene–vinyl alcohol main chain and sulfonated poly(ethylene\noxide) side chains. Its single-ion conductor films were prepared by\na drop-casting method, using E<sub>38</sub>V<sub>62</sub>O–DEG–BuSO<sub>3</sub>Li with an optimized branch length and distance, exhibiting\ndecent mechanical strength, high Li<sup>+</sup>-ion transference number,\nand significant ionic conductivity at room temperature. The symmetrical\ncell with the prepared E<sub>38</sub>V<sub>62</sub>O–DEG–BuSO<sub>3</sub>Li film sandwiched between two lithium electrodes without\nadditional solvent shows good cycling stability with a low overpotential\nand suppressing the growth of lithium dendrites. These results suggest\nthat this novel single-ion conductor is promising for application\nin next-generation Li<sup>+</sup>-ion batteries.