In-situ construction of PDOL electrolyte with dual-reinforced stable interface for high-voltage lithium metal batteries

In-situ polymerized electrolytes significantly enhance the interfacial compatibility of lithium metal batteries (LMBs). Typically, in-situ polymerized 1,3-dioxolane (PDOL) exhibits low interfacial resistance, yet still suffers from low ionic conductivity and a narrow electrochemical stability window (ESW). Here, an ultra-stable PDOL-based polymer electrolyte is developed by incorporating plasticizers of tetramethylene sulfone (TMS) and fluorinated ethylene carbonate (FEC) into the 3D cross-linked network, achieving a significant enhancement in the transport capacity and efficiency of Li-ion. The ionic conductivity reaches 3.63×10⁻⁴ S cm⁻¹ even at room temperature, and the transference number ( \(t_{{\rm Li}^{+}}\) $$t_{{\mathrm{L}\mathrm{i}}^{+}}$$ ) is even higher at 0.85. Furthermore, the ESW of this electrolyte can be increased to 4.5 V with the addition of TMS, which forms a thin and robust antioxidant cathode-electrolyte interface (CEI) on the surface of high-voltage LiCoO₂. FEC generates an inorganic-rich solid-electrolyte interface (SEI) on the Li anode, which effectively inhibits the growth of lithium dendrites. Benefiting from the aforementioned advantages, the high-voltage lithium metal battery demonstrates outstanding long-cycle stability, with 93.2% capacity retention after 200 cycles. This work offers a straightforward and accessible method for the practical implementation of high energy density in-situ polymerized solid-state LMBs.