Abstract: Polymer electrolyte shows great promise for enabling solid-state batteries with intrinsic safety. However, it faces a fundamental challenge in the trade-off between ionic conductivity and robustness, stemming from conflicting requirements for polymeric chain segment mobility. In this work, we design a crosslinked poly(vinyl ethylene carbonate) (PVEC)-based electrolyte, incorporating hydrogen bond contained crosslinker to create a covalent and hydrogen bond dual-crosslinked architecture. The covalent crosslink from C=C group reactions and complementary N-H…O hydrogen bond crosslink synergistically restricts polymer chain segment mobility while modulating the Li⁺ coordination environment, thus enabling exceptional robustness without sacrificing ionic transport. The optimized electrolyte simultaneously achieves high ionic conductivity (2.1×10^-4 S cm^-1 at 25 °C) and enhanced Young’s modulus (2.51 MPa). When implemented in LiFePO₄||Li cells, the cell delivers a high capacity of 150.2 mAh g^-1 and maintains 92 % capacity after 1000 cycles at 0.5 C. Furthermore, it maintains superior performance under high cathode loading or low-temperature operation. This strategy provides a remarkable design for developing polymer electrolytes, paving a promising route toward practical solid-state lithium batteries with enhanced safety and cycle life.

Key words: Polymer electrolyte, Solid-state lithium batteries, In-situ polymerization, High cathode loading, Low-temperature operation