Lithium-ion (Li-ion) batteries are continuously being developed to enhance safety and energy density. One promising approach involves combining high nickel cathode material (NCM811) with Gel Polymer Electrolyte (GPE). However, achieving compatibility between these components remains a challenge. In this study, we investigate the use of Ethyl difluoroacetate (DFEA) to enhance the mechanical stability, ionic conductivity, and heat-resisting of polyethylene glycol dimethacrylate (PEGDMA) based GPE, thereby improving battery performance. The modified GPE/DFEA exhibits a smoother surface, increased Young's modulus (2.2 GPa), and high ionic conductivity (7.10 mS cm⁻¹). Additionally, it enables the in-situ formation of a LiF-rich interface film on the electrode/electrolyte surfaces. Moreover, the Li||Li symmetrical cell with GPE/DFEA demonstrates stable cycling for 500 h without dendrite growth. Furthermore, Li|Cu asymmetrical cells using GPE/DFEA achieve an average Coulombic efficiency (CE) of 99.0% over 200 cycles at 1 mA cm⁻², compared to only 62.2% for liquid electrolyte (LE). Importantly, the GPE/DFEA allows for operation beyond the conventional voltage limit of 4.25 V, reaching 4.38 V. It is successfully implemented in an Ah-level NCM811/graphite pouch cell, resulting in an energy density of 250 Wh/kg and improved cycle stability at 45 °C compared to standard electrolytes. Moreover, the GPE/DFEA-based batteries exhibit enhanced safety performance under conditions such as needle puncture and overcharge. The developed GPE can meet the practical requirements for battery applications.

锂离子（Li-ion）电池正在不断开发以提高安全性和能量密度。一种有前途的方法是将高镍阴极材料 (NCM811) 与凝胶聚合物电解质 (GPE)结合起来。然而，实现这些组件之间的兼容性仍然是一个挑战。在本研究中，我们研究了使用二氟乙酸乙酯（DFEA）来增强聚乙二醇二甲基丙烯酸酯（PEGDMA）基GPE的机械稳定性、离子电导率和耐热性，从而提高电池性能。改性后的GPE/DFEA表现出更光滑的表面、更高的杨氏模量（2.2 GPa）和高离子电导率（7.10 mS cm ^-1）。此外，它还能够在电极/电解质表面原位形成富含 LiF 的界面膜。此外，具有 GPE/DFEA 的 Li||Li 对称电池表现出 500 小时的稳定循环，没有枝晶生长。^{此外，使用GPE/DFEA的Li|Cu不对称电池在1 mA cm -2}下经过200次循环后实现了99.0%的平均库仑效率（CE），而液体电解质（LE）的平均库仑效率（CE）仅为62.2%。重要的是，GPE/DFEA 允许在超出传统电压限制 4.25 V 的情况下运行，达到 4.38 V。它已成功应用于 Ah 级 NCM811/石墨软包电池，能量密度达到 250 Wh/kg，并改善了循环次数与标准电解液相比，45°C 下的稳定性更高。此外，基于GPE/DFEA的电池在针刺和过充等条件下表现出增强的安全性能。所开发的GPE可以满足电池应用的实际要求。