Constructing highly stable solid electrolyte interphase for Si@Graphene anodes by coupling 2-isocyanatoethyl methacrylate and fluoroethylene carbonate

Si-based anode materials have become the most popular candidate in next generation high-specific energy lithium-ions batteries owing to the advantages of high theoretical capacity, low operation potential, environmental friendliness, and low cost. However, the huge volume changes of Si-based anode during the charging and discharging process results in unstable solid electrolyte interphase (SEI) films and poor cycling performance. Here, 2-isocyanatoethyl methacrylate (IEM) and fluoroethylene carbonate (FEC) are used as functional electrolyte additives to constructing stable and durable inorganic-organic composite SEI films on the surface of Si@Graphene (Si/G) anode. The composite SEI film can tolerate the volume change of Si/G anode. As a result, the Si/G anode shows enhanced initial Coulombic efficiency (ICE), cycling stability and rate capability. Specifically, the ICE of Li||Si/G cell can reach 90%, and the specific capacity of Li||Si/G cell can maintain 1373 mAh g−1 after 100 cycles at the rate of 1 A g−1 by adding 1 vol% IEM and 9 vol% FEC.