Hierarchical porous silicon oxycarbide as a stable anode material for lithium-ion batteries

The porous and amorphous silicon oxycarbides (SiOC) derived from polymer precursors are regarded as promising anode materials for lithium-ion batteries due to their high theoretical capacity and minimal volume expansion. Modulations of carbon nanoclusters and reversible species in Si-O-C units have been performed to improve lithium storage properties of SiOC anodes. Herein, we report the effects of pore structure on cycling stability and rate performance of SiOC anode materials, which are prepared by a sol-gel approach using different additions of solvents and a subsequent calcination. The increase in the solvent addition promotes the formation of macropores in the hierarchical porous structure of the SiOC, thereby facilitating rapid Li ion migration and mitigating volume expansion during the lithiation of the SiOC. The as-prepared SiOC anode exhibits competitive reversible capacities of 750.4 mAh g⁻¹ at 0.1 A g⁻¹ after 150 cycles and 437.1 mAh g⁻¹ at 1 A g⁻¹ after 500 cycles, compared to those of previously reported SiOC anodes. This work provides a new strategy for designing of high-capacity and high-stability SiOC anode materials.