Single‐Ion Gel Polymer Electrolyte based on In‐Situ UV Irradiation Cross‐Linked Polyimide Complexed with PEO for Lithium‐Ion Batteries

Lithium-ion batteries (LIBs) have become the research focus of energy storage products. Due to the combination of Li⁺ and the Lewis basic sites of polymer chains, anions move more than five times faster, which do not participate in the electrode reaction during the discharge cycles, leading to concentration polarization, voltage losses, and high internal resistance. To solve this phenomenon, in this work, a polymer network structure of single-ion polymer electrolyte-based polyimide (DPI-SIGPE) with plasticizer ethylene carbonate (EC)/dimethyl carbonate (DMC) is formed by in-situ cross-linking double bond polyimide, 4-styrene sulfonyl (benzenesulfonyl) imide, and cross-linking agent pentaerythritol tetra(2-thiol acetate) under UV irradiation. By incorporating the anion as a part of the polymer chain, DPI-SIGPE exhibits high lithium-ion conductivity of 2.7 × 10^-4 S cm^-1 at 30 °C and transference number of 0.87. Typical lithium stripping/plating cycling of 900 h demonstrates uniform lithium deposition impacted by DPI-SIGPE. Meanwhile, it has good dimensional thermal stability with no obvious shrinkage at 200 °C for 0.5 h and wide electrochemical window of 4.6 V. Thus, the polyimide-based cross-linked single-ion gel polymer electrolyte has the promising potential for application in LIBs.