Single-Ion-Conducting Gel Polymer Electrolyte Based on Lithiated Nafion

The use of gel polymer electrolytes (GPEs) is recognized as a promising strategy to improve the safety characteristics of current lithium-ion batteries (LIBs) due to the incorporation of polymer matrix and immobilization of the liquid phase. To achieve high performance and efficient Li+ transport in GPEs, the selection of polymer is critically important. Herein, a single-ion-conducting GPE with a high lithium-ion transference number is proposed with lithiated Nafion (Li-Nafion) and polyacrylonitrile (PAN) polymers. We found that the interactions between electron-withdrawing C≡N groups Li+ facilitate fast Li+ transport and reduce the Li+ migration barrier of Li+ on the −SO3– groups. As a consequence, the designed GPE shows a high lithium-ion transference number of 0.93, an admirable ionic conductivity of 1.93 × 10–4 S cm–1, and a wide electrochemical stability window up to 5.0 V at 30 °C. Further validation of the Li|LiFePO4 cell shows a decent cycling performance with an initial discharge specific capacity of 126.1 mAh g–1 and a high capacity retention of 90.1% after 200 charge/discharge cycles at 1C. This study provides a strategy of Li-Nafion and a "decoupling" polymer to enhance the GPE performance and its applications on LIBs.