The Polymer Society of Korea

Abstract

Gel polymer electrolytes (GPEs) for lithium metal batteries (LMBs) must overcome two major challenges: trade-off between ionic conductivity and mechanical strength, and insufficient interfacial stability. Here, we present an in-situ dual-curable GPE that integrates polymerization-induced phase separation (PIPS) with a semi-interpenetrating network (semi-IPN) structure to simultaneously achieve high ionic conductivity and mechanical robustness. In the first UV-curing step, BPAEDA polymerizes and undergoes PIPS with the liquid electrolyte, generating a continuous electrolyte-rich phase that provides an efficient ion-conduction pathway, yielding an ionic conductivity of 2.0 × 10⁻³ S/cm at room temperature. The VEC component does not polymerize under UV exposure and therefore remains in the liquid phase at this stage, enhancing wetting and conformal contact at the electrolyte/electrode interfaces after cell assembly. A subsequent thermal-curing step polymerizes VEC in situ, forming a semi-IPN matrix that increases the shear storage modulus to 1.36 × 10⁵ Pa and promotes void-minimized solid–solid contact at the electrode/electrolyte interfaces. The resulting electrolyte exhibits a low interfacial resistance of 473 Ω and effectively suppresses dendritic growth, enabling stable Li plating/stripping for over 2000 h with minimal overpotential in symmetric cells. When applied to Li||LFP full cells at 1C, the GPE delivers excellent cycling stability, retaining 81.3% of its capacity after 524 cycles. This strategy offers a promising route for developing durable and high-performance electrolytes for next-generation LMBs.