Fullerene-like elastic carbon coatings on silicon nanoparticles by solvent controlled association of natural polyaromatic molecules as high-performance lithium-ion battery anodes

Carbon coating is one of the most common methods to improve the performance of Li-ion batteries, especially for materials such as silicon and silicon oxides (SiOx) of poor electronic conductivity and large volume changes during cycling. However, its brittle nature and low elasticity make the conventional carbon coatings crack easily and hence lose the conductive connection with active materials after a few cycles. In this work, we propose a scalable and low-cost synthesis method to deposit a highly-elastic fullerene-like protective carbon layer on silicon nanoparticles by molecular-level controlled association of natural polyaromatic molecules in heavy oil. The fullerene-like carbon layer is shown to recover by > 90% after deformation, which ensures the structural stability of the carbon coatings during cycling. Fullerene-like carbon coated silicon nanoparticles exhibit a high cycle stability with a reversible capacity of 1230 mAh g-1 and capacity retention of 94.6% after 600 cycles at 1 C. These results demonstrate the great commercial potential of this synthesis method in producing anode materials of high-performance lithium-ion batteries.