Fluorine-Free Cycloaliphatic\nEpoxy-Based Siloxane\nNanohybrid Binder with High Polar Hydroxyl Group Content Enabling\nLiFePO<sub>4</sub>‑Type Battery with High Electrochemical Performance\nand Stability

LiFePO<sub>4</sub>-type (LFP) batteries have attracted\nsignificant\nattention in most battery manufacturing industries due to their long\nlifespan, high-temperature safety, and low cost of raw materials.\nHowever, as an active material, LFP still suffers from several intrinsic\ndrawbacks, including poor conductivity, a low Li<sup>+</sup> diffusion\ncoefficient, low capacity, and a lack of electrochemical stability,\nprimarily due to conventional fluorine-based binders. Here, we report\na simple yet effective approach to developing a fluorine-free binder\nbased on a robust cycloaliphatic epoxy-based siloxane nanohybrid material\n(CES) to achieve high electrochemical stability in LFP batteries.\nThe high content of silanol moieties in CES induces a strong affinity\nfor the active material and conductive agent, significantly improving\nrheological (thixotropy) and mechanical (adhesion and cohesion) properties,\nwhich enable the formation of a uniformly coated electrode. As a result,\nwe achieved superior electrochemical performance and stability in\nCES-applied electrodes compared to those with conventional fluorine-based\nbinders. We investigate the reasons behind the contribution of CES\nto the electrochemical stability of LFP batteries through various\nanalyses. The high thermal and oxidation stability of CES effectively\nprevents degradation of LFP-based active materials. Our binder development\nstrategy offers a significant breakthrough in replacing conventional\nfluorine-based binders, advancing the development of high-performance\nand stable secondary batteries.