Tuning of dynamic solvation structures via click chemistry for PEO-based solid polymer electrolytes

The Li⁺-transport mechanisms in both solid polymer electrolytes (SPEs) and liquid electrolytes (LEs) are fundamentally governed by solvation dynamics, requiring an optimal balance between continuous coordination and moderate binding strength. Poly(ethylene oxide) (PEO) is a classic SPE matrix that leverages its -CH₂-CH₂-O- (EO) segments to provide continuous oxygen coordination for Li⁺ transport via amorphous regions. While continuous EO segments facilitate the intra-chain Li⁺-transport, their strong multidentate solvation of Li⁺ through a chelate effect - each Li⁺ chelates with 4-6 ethylene oxide (EO) units - significantly hinders the inter-chain Li⁺ mobility. This effect creates rigid solvation cages that both immobilize Li⁺ and resist modification by alternative moieties (e.g. carbonate or nitrile groups), resulting in poor room-temperature ionic conductivity (σ) and low Li⁺ transference number (t_Li+). To address these challenges, we developed a series of precise Li⁺-transport models (LTMs) through click chemistry, strategically combining acrylate-PEG and acrylonitrile to engineer balanced interactions between multidentate (EO) and monodentate (C = O, C ≡ N) coordination sites. This design achieved synergistic enhancement of both inter- and intra-chain transport pathways, demonstrated by significantly improved performance with σ = 6.40 × 10^- 5 S/cm and t_Li+ = 0.44 at 25 °C. This approach permits tailored control of dynamic solvation structures, offering new opportunities to enhance Li⁺ transport in PEO-based solid polymer electrolytes.