Tailoring Li⁺ Local Coordination Environment of Solid Polymer Electrolytes to Boom Ionic Conductivity

The low ionic conductivity is the key issue of solid polymer electrolytes (SPEs), hampering their practical application. Great efforts have been devoted to reducing their crystallinity to increase ionic conductivity but ignored their Li⁺ local coordination environment influence. Here, Li⁺ local coordination environment tunable poly(vinylidene fluoride-co-hexafluoropropylene)-based solid-state electrolytes are experimentally realized via d-cellobiose octaacetate. d-cellobiose octaacetate competes with anions and polymer chains for coordination of Li⁺ thorough C═O groups to weaken their coordination of Li⁺, increase the number of carriers, and strengthen the transport kinetics of Li⁺, booming the ionic conductivity of SPEs at room temperature. When used in lithium metal symmetric batteries and full batteries, SPEs greatly improve their electrochemical performance at 25 °C. This work clarifies the important influence of Li⁺ local coordination environment on Li⁺ transport and provides a promising strategy to improve the ionic conductivity of SPEs.