One-step synthesis of interface-coupled Si@SiOX@C from whole rice-husks for high-performance lithium storage

Abstract As the world transitions towards an electric vehicle-driven future, demand for energy storage materials has continued to grow. Silicon-carbon composites are considered one of the most promising anode materials for lithium-ion batteries owing to their superior electrochemical performance. However, their commercialization is seriously limited due to the use of chemical reagents as carbon source, unstable coating structures and the complexity of the synthesis process. Herein, a facile one-step carbonization method at 800 °C was used to prepare Si@SiOX@C-800 composite by using rice husks, 1‑butyl‑3-methylimidazolium acetate (BMIMAcO) and silicon nanoparticles (Si-NPs). When the optimized Si@SiOx@C-800 was applied to the anode of lithium-ion batteries, it exhibited prominent reversible capacity (694 mAh g−1 at 0.1 A g−1), with remarkable rate performance (220 mAh g−1 at 2 A g−1), and excellent cyclic stability (460 mAh g−1 with a capacity retention of 105.7% at 1 A g−1 after 1000 cycles). The coupling of interfaces by Si-N bonds led to the formation of a double-layered structure which enhanced Li+ diffusion coefficients and electrochemical kinetics, while tremendously limiting the volume variation of Si nanoparticles (Si NPs). The double-shell-structured Si@SiOX@C-800 composite material which was facilely synthesized using an eco-friendly approach presented superior electrochemical performance.