Importance of constructing synergistic protective layers in Si-reduced graphene oxide-amorphous carbon ternary composite as anode for lithium-ion batteries

Si is regarded as a promising anode candidate for lithium-ion batteries (LIBs) due to its high theoretical capacity and appropriate Li⁺ ions insertion voltage (<0.4 V vs Li⁺/Li). However, its intrinsic inferior electronic conductivity and huge volume changes during cycling lead to poor cyclic performance. Integrating Si with carbon materials has been proved to be an efficient route to improve its electrochemical performance. In this report, we successfully synthesized Si-reduced graphene oxide-amorphous carbon (Si-rGO-C) composite assisted with a facile guar gum hydrogel method and studied the protective effect of different kinds of carbon. In the Si-rGO-C ternary composite, the Si nanoparticles (NPs) are embedded in amorphous carbon and tightly anchored to rGO sheets. The amorphous carbon and rGO serve as synergistic protective layers. The Si-rGO-C composite possesses good structural integrity accompanied by enhanced conductive framework. The resulting Si-rGO-C composite exhibits much improved electrochemical performance (a high capacity of 913 mAh g⁻¹ can be maintained after 100 cycles at 0.5 A g⁻¹ with almost no capacity decay) compared with the Si-rGO and Si-C composites with only single protective layer, indicating the importance of constructing synergistic carbon layers in Si-rGO-C ternary composite for LIB anodes. - Highlights: • Si-reduced graphene oxide-amorphous carbon (Si-rGO-C) composite is prepared through a facile guar gum hydrogel method. • Protective effects derived from different kinds of carbon are studied. • The Si-rGO-C composite exhibits much improved electrochemical performance compared with the Si-rGO and Si-C composites with only single protective layer.