An Acrylate-Based Ion-Conductive network binder with interfacial modulation capability for High-Performance Si/C composite anodes in lithium-ion batteries

Silicon-graphite composites (Si/C) are one of the most promising commercial anode materials due to the higher specific capacity than graphite and lower swelling effect than silicon, but their volume expansion and capacity degradation due to complex interfacial structure remain challenges. Here, the binder with interfacial modulation capability and high lithium-ion conductivity was prepared by acrylate emulsion polymerization and in-situ thermal esterification cross-linking, which can improve the affinity between the binder and Si/C particles through supramolecular interactions of hydrogen bonding and $\pi$$\pi$- $\pi$$\pi$ conjugate. In addition, functional cyano groups and long ether-bonded chain segments in the binder contribute to efficient SEI construction and Li-ion transport, respectively. With this binder, the Si/C anode maintains a reversible specific capacity of 560.1 mAh/g after 400 cycles at a current density of 1C with the capacity retention rate of 87.3 %, and stable cycling (472.0 mAh/g after 180 cycles) even when the loading of Si/C are doubled. Furthermore, the reversible specific capacity of the anode was stabilized at 349.9 mAh/g at the high current density of 4C.