Semi-interpenetrating polymer network-based gel polymer electrolytes for Li-ion batteries applications

Abstract

In this study, a series of high-performance semi-interpenetrating polymer network (sIPN)-based gel polymer electrolytes (GPEs) were prepared using UV-initiated polymerization of unsaturated-bond-containing ethylene oxide oligomers (specifically poly(ethylene glycol) methyl ether methacrylate(PEGMAMA) and poly(ethylene glycol) diacrylate(PEGDA)), followed by blending with linear poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP). PEGDA was used as the crosslinking agent to form a crosslinked structure with PEGMAMA. This unique architecture not only provided abundant ethylene oxide chain segments but also disrupted the crystallinity of PVDF-HFP. The sIPNs structure imparts GPEs with high thermal stabilities and robust mechanical properties. Among the sIPN-based GPEs, PP₂P₃-IL exhibited a high conductivity of 1.05 × 10⁻³ S cm⁻¹. Owing to the excellent dissociation ability of the sIPNs structure toward Li salts, PP₂P₃-IL shows a high Li-ion transference number of 0.68. The Li|PP₂P₃-IL|Li battery maintained a low steady-state overpotential, even after 800 h. Moreover, the discharge capacity of the Li/LiFePO₄ battery reached 150 mAh g⁻¹, and its capacity retention higher than 95 % even after 100 cycles, demonstrating its strong potential for application in Li-ion battery.