Hydrophobic dispersion-derived Si/rGO nanocomposites in SiOC ceramic matrix as anode materials for high performance lithium-ion batteries

Silicon, which has high theoretical capacity (3570 mA h g −1 ) and low discharge potential, is gaining attention as a next-generation high-capacity anode material for lithium-ion batteries (LIBs) because it can overcome the limited capacity of commercially available graphite. Nevertheless, silicon exhibits a volumetric change of approximately 400% in the process of repeated charging and discharging, and simultaneously, an unstable solid electrolyte interface (SEI) is continuously formed. Consequently, the battery life decreases rapidly, leading to capacity loss; thus, commercialization is difficult. In this study, hydrophobic reduced graphene oxide (rGO) was introduced onto a silicon surface modified with tannic acid (TA) to induce uniform dispersion in a silicone oil precursor, and then a silicon-based composite was embedded without agglomeration in a silicon oxycarbide (SiOC) matrix (Si/rGO/SiOC) via a simple pyrolysis process. In the Si/rGO/SiOC composite, rGO supported the uniform distribution of silicon and improved the electrical conductivity. SiOC showed its potential as a buffer matrix by sufficiently overcoming the problems of silicon with mechanical stability. As a result, the Si/rGO/SiOC composite exhibited a high reversible capacity of approximately 1230 mA h g −1 at 0.5 A g −1 and demonstrated excellent electrochemical properties with a cycle stability of 97.3% even after the 100th cycle, proving its potential as a high-efficiency anode material for LIBs. A Si/rGO/SiOC composite is designed using hydrophobic rGO for uniform distribution of Si in SiOC matrix. rGO contributed to the improvement of electrical conductivity, and the volume expansion of Si was effectively alleviated by the SiOC material.