Dynamic Imine Bonds-Based Vitrimer Electrolytes for Stable Interfaces in Lithium Metal Electrodes

Vitrimer solid polymer electrolytes (V-SPEs) incorporating dynamic imine bonds are developed as solid-state electrolytes for the use in lithium metal batteries (LMBs). By systematically tuning the ratio of ethylene oxide (EO) units to Li+ and the EO chain length, the ionic transport properties of the polymer matrix are optimized. The formulation containing extended EO segments achieves a considerable ionic conductivity of 2.88 × 10–4 S cm–1 at 60 °C. The V-SPE exhibits pronounced stress relaxation, where viscosity decreased linearly with temperature in accordance with the Arrhenius relationship, showing an activation energy of 48 kJ mol–1 derived from imine bond exchange dynamics. Owing to these reversible imine exchanges, the V-SPEs are capable of self-healing at room temperature. These dynamic exchanges result in a 75% decrease in interfacial resistance over 120 charge–discharge cycles, confirming the adaptive nature of the polymer network at the electrode–electrolyte interface. Furthermore, a full Li metal cell employing the optimized V-SPE delivers stable cycling performance with good C-rate capability up to 100 cycles at the conditions of 60 °C and 0.1 C. Overall, the results demonstrate the promise of V-SPEs as solid-state electrolytes for LMBs.