Graphene/carbon-coated Si nanoparticle hybrids as high-performance anode materials for Li-ion batteries

Si is regarded as one of the most promising anode materials for next generation Li-ion batteries, but it usually exhibits poor cycling stability due to the low intrinsic electrical conductivity and huge volume change induced by the alloying reaction with Li. In this study, we present a double protection strategy by fabricating graphene/carbon-coated Si nanoparticle hybrids to improve the electrochemical performance of Si in Li storage. The Si nanoparticles are wrapped between the graphene and the amorphous carbon coating layers in the hybrids. The graphene and the amorphous carbon coating layers work together to effectively suppress the aggregation and destruction of Si nanoparticles, keeping the overall electrode highly conductive and active in Li storage. As a result, the produced graphene/carbon-coated Si nanoparticle hybrids exhibit outstanding reversible capacity for Li storage (902 mAh g(-1) after 100 cycles at 300 mA g(-1)). This work suggests a strategy to improve the electrochemical performance of Li-ion batteries by using graphene as supporting sheets for loading of active materials and carbon as the covering layers.