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

Abstract

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.