原位聚合法制备PEGDMA凝胶电解质及其性能研究

Research on the Preparation and Performance of PEGDMA Gel Electrolytes Via In-Situ Polymerization

摘要: 固–固界面接触阻抗是固态电解质(含准固态体系)实用化进程中始终面临的严峻挑战。在此背景下，原位聚合技术制备凝胶聚合物电解质因其独特的“液态浸润–固态稳定”转化特性，成为突破界面技术瓶颈的有效手段。本研究采用原位聚合的方法，制备了聚乙二醇二甲基丙烯酸酯(PEGDMA)凝胶聚合物准固态电解质，通过系统调控聚合物单体含量(5~20 wt%)，构建了浓度梯度聚合物电解质，并深入揭示了组分–结构–性能的构效关系。实验结果表明，当聚合物单体含量为10 wt%时，电解质呈现出最优性质：热分解温度达215℃，拉伸强度提升至15.62 MPa，离子电导率高达1.28 × 10⁻³ S cm⁻¹ (较液态体系提升15.3%)。同时，活化能降低至0.064 eV，锂离子迁移数提高至0.43，在Li||Li对称电池测试中展现出优异的界面稳定性(临界电流密度达2 mA cm⁻²)。基于该电解质构建的Li||LiFePO₄全电池体系在0.5 C倍率下首圈放电比容量达160 mAh g⁻¹，经300次循环后容量保持率高达96.8%。本研究通过原位聚合策略成功制备了具有高离子传导与机械稳定性的凝胶聚合物电解质，证实了其在高安全、高能量密度、长循环寿命准固态电池中的应用潜力。

Abstract: The solid-solid interfacial contact impedance presents a significant challenge in the practical application of solid-state electrolytes, including quasi-solid systems. In this context, in situ polymerization techniques have emerged as an effective means to overcome interface technology bottlenecks, particularly in the preparation of gel polymer electrolytes due to their unique “liquid wetting-solid stabilization” conversion characteristics. In this study, we employed in situ polymerization to fabricate polyethylene glycol dimethylacrylate (PEGDMA) gel polymer quasi-solid electrolytes. By systematically adjusting the polymer monomer content (5~20 wt%), we constructed a concentration gradient polymer electrolyte and thoroughly revealed the component-structure-performance relationship. The experimental results indicated that at a polymer monomer content of 10 wt%, the electrolyte exhibited optimal properties: a thermal decomposition temperature of 215˚C, a tensile strength of 15.62 MPa, and an ionic conductivity of 1.28 × 10⁻³ S cm⁻¹ (an increase of 15.3% compared to liquid systems). Additionally, the activation energy was reduced to 0.064 eV, and the lithium-ion transference number increased to 0.43, demonstrating excellent interfacial stability in Li||Li symmetric cell tests (with a critical current density of 2 mA cm⁻²). The Li||LiFePO₄ full cell system constructed with this electrolyte achieved a discharge specific capacity of 160 mAh g⁻¹ at a rate of 0.5 C in the first cycle, with a capacity retention of 96.8% after 300 cycles. This study successfully demonstrated the preparation of a gel polymer solid-state electrolyte with high ionic conductivity and mechanical stability using an in-situ polymerization strategy, confirming its potential application in high-safety, high-energy-density, and long-cycle-life quasi-solid-state batteries.