UV‐Cured Semi‐Interpenetrating Polymer Network Electrolyte for High‐Performance Bipolar‐Stacked Quasi‐Solid‐State Lithium Metal Batteries

ABSTRACT

Lithium metal batteries are regarded as promising candidates for next‐generation energy storage systems due to their high energy density. However, electrolyte instability and lithium dendrite formation remain critical challenges. Accordingly, a semi‐interpenetrating polymer network (semi‐IPN) quasi‐solid polymer electrolyte (QSPE) is developed by incorporating polyethylene glycol monomethyl ether methacrylate (PEGMA), polyethylene glycol dimethacrylate (PEGDA), and vinyl ethylene carbonate (VEC) into a polyvinyl alcohol (PVA) matrix via UV curing. The prepared semi‐IPN QSPE exhibits a high ionic conductivity of 1.36 × 10 ⁻³ S cm ⁻¹ and a Li‐ion transference number of 0.78 at room temperature, while maintaining flexibility with a tensile strength of 5.2 MPa and a Young's modulus of 25.1 MPa. Furthermore, it demonstrates a wide electrochemical stability window up to 4.8 V and excellent interfacial compatibility with a lithium (Li) anode. Based on these properties, bipolar cells, constructed by serially connecting two LFP/QSPE/Li unit cells, not only achieve an open‐circuit voltage of 6.36 V stably, but also deliver a discharge capacity of 144 mAh g ⁻¹ at 0.2 C with 77.0% capacity retention and 99.0% coulombic efficiency after 100 cycles.