SiOC nanolayer wrapped 3D interconnected graphene sponge as a high-performance anode for lithium ion batteries

Abstract

Silicon oxycarbides (SiOCs) are promising anode materials for high-energy LIBs because of their high theoretical capacity. However, due to their intrinsically poor electronic conductivity, the battery performance is often restricted. Herein, high performance anodes are demonstrated by designing a hierarchical 3D interconnected structure using graphene sponge as a scaffold. The graphene sponge was infiltrated with a polysiloxane precursor and further converted into porous frameworks consisting of multi-layered sandwich-like nanosheets (SiOC@graphene@SiOC) by subsequent pyrolysis. The deliberate structure not only improved the electrical conductivity, accelerated ion insertion, and shortened the ionic diffusion distance but also enabled full utilization of SiOC active sites in the anode. The 3D-GNS/SiOC anodes exhibited excellent electrochemical performance, including high initial discharge capacity (1280 mA h g⁻¹ at 0.1 A g⁻¹), high reversibility and stability (701 mA h g⁻¹/371 μA h cm⁻² after 100 cycles) and extreme rate performance (656 mA h g⁻¹/348 μA h cm⁻² at 0.5 A g⁻¹). For full-cells, high initial charge capacity (680 mA h g⁻¹ at 0.5 A g⁻¹) and high stability (416 mA h g⁻¹ at 0.5 A g⁻¹ after 100 cycles) were obtained. Significantly, this simple and scalable method can be extended to fabricate high-rate and long-cycle SiOC or other anode materials for commercial LIBs.