A Novel Single-Ion-Conducting Polymer Electrolyte Derived from CO₂-Based Multifunctional Polycarbonate

This work demonstrates the facile and efficient synthesis of a novel environmentally friendly CO₂-based multifunctional polycarbonate single-ion-conducting polymer electrolyte with good electrochemistry performance. The terpolymerizations of CO₂, propylene epoxide (PO), and allyl glycidyl ether (AGE) catalyzed by zinc glutarate (ZnGA) were performed to generate poly(propylene carbonate allyl glycidyl ether) (PPCAGE) with various alkene groups contents which can undergo clickable reaction. The obtained terpolymers exhibit an alternating polycarbonate structure confirmed by ¹H NMR spectra and an amorphous microstructure with glass transition temperatures (T_g) lower than 11.0 °C evidenced by differential scanning calorimetry analysis. The terpolymers were further functionalized with 3-mercaptopropionic acid via efficient thiol-ene click reaction, followed by reacting with lithium hydroxide, to afford single-ion-conducting polymer electrolytes with different lithium contents. The all-solid-state polymer electrolyte with the 41.0 mol % lithium containing moiety shows a high ionic conductivity of 1.61 × 10^-4 S/cm at 80 °C and a high lithium ion transference number of 0.86. It also exhibits electrochemical stability up to 4.3 V vs Li⁺/Li. This work provides an interesting design way to synthesize an all-solid-state electrolyte used for different lithium batteries.