High-coulombic-efficiency Si-based hybrid microspheres synthesized by the combination of graphene and IL-derived carbon

The low initial coulombic efficiency of a Si-based anode can hinder the performance of practical full-cell Li-ion batteries (LIBs), as the irreversible capacity loss of the anode can diminish the reversible full-cell capacity and the energy efficiency. Therefore, it is critical to develop high-coulombic-efficiency Si-based anode materials from a practical perspective. To this end, we developed a high-coulombic-efficiency Si-based hybrid anode material with suitable cycling performance by developing a spray-assisted assembly process based on a combination of graphene and ionic liquid (IL). During the assembly process, the IL was trapped between the graphene and Si nanoparticles. Then, it was easily converted into IL-derived carbon, to generate additional protective/binding layers in the resultant Si-based hybrid microspheres. This IL-derived carbon layer played an important role in improving the electrochemical performance of the Si-based hybrid microspheres. The resultant Si-based hybrid microsphere electrode exhibited enhanced initial coulombic efficiency along with improved cycling performance, owing to the formation of the protective/binding carbon layers derived from the IL.