ABSTRACT In situ polymerized quasi‐solid‐state electrolytes (QSEs) are promising for lithium metal batteries (LMBs) yet face challenges regarding high‐voltage stability and kinetics. Herein, a novel ether‐ester hybrid QSE is achieved through the in situ copolymerization of 2,2,2‐trifluoroethyl acrylate (TFEA) and 2‐isocyanatoethyl methacrylate (IEM) within a tetraethylene glycol dimethyl ether (G4)/fluoroethylene carbonate (FEC) solvent system. This design leverages synergistic interactions between the functionalized polymer matrix (─CF 3 and ─N═C═O) and liquid components. The incorporation of FEC and the regulatory effect of the polymer backbone tailor the Li + solvation structure toward an anion‐rich configuration, which gives rise to a robust, antioxidative, and inorganic‐rich interphase. Furthermore, hydrogen bonding interactions effectively immobilize PF 6 − anions and free G4 molecules, thereby elevating the Li + transference number and enabling the electrochemical stability window over 4.8 V (vs. Li + /Li). The QSE exhibited a high room‐temperature ionic conductivity of 2.2 × 10 −3 S cm −1 . Consequently, 4.2 V Li|| LiFePO 4 (LFP) cells demonstrate 93% capacity retention over 1,000 cycles, while 4.5 V Li||NCM811 (NCM811) cells retain 80% over 300 cycles. A specific energy of 302.64 Wh kg −1 is attained in a 2 Ah Li||NCM811 pouch‐type cell. These findings highlight tailored molecular design and controlled interactions as a viable route for advancing high‐energy‐density quasi‐solid‐state batteries.
Zhang et al. (Tue,) studied this question.