Zwitterionic impetus on single lithium-ion conduction in solid polymer electrolyte for all-solid-state lithium-ion batteries

Single lithium-ion conducting solid polymer electrolytes (SLICSPEs) with high ionic conductivity play critical roles in pursuit of efficient and safe energy storage. Herein, we presented a universal and facile strategy towards high-performance SLICSPEs by applying representatively monomeric or polymeric zwitterions as synergistic ion dissociator and phase plasticizer for expedited single Li+ conduction in solid polymer matrix. It is manifested that the strong molecular interactions between zwitterions and SLICSPEs effectively facilitate the disintegration of Li+ from polyanionic backbone, while the impregnation of zwitterions simultaneously reduces the PEO crystallinity and increases the flexibility of EO segments, thus cooperatively promoting the Li+ mobility within the solid polymer matrix without expense of ion selectiveness. Attributed to these unique features, the as-developed SLICSPE achieved a considerable ionic conductivity of 8.39 × 10−5 S/cm at 90 °C without uptake of any organic solvents, as well as a high Li+ transference number approximately to unity, which further powered the decent cyclability and rate capability of the corresponding LiFePO4/SLICSPE/Li batteries, demonstrating a good promise in advancing the development of all-solid-state lithium ion batteries.