Decrypting the structural regulation of SiOC anodes through SiH induced carbon deficiency effect in precursors

Silicon oxycarbide (SiOC) ceramics have garnered significant attention as anode materials for lithium-ion batteries due to their tunable chemical composition, minimal volume expansion, and high theoretical capacity. However, achieving simultaneous control over the structure and composition of both the SiOC tetrahedral phase and free carbon remains a formidable challenge. To address this, we introduce a concept leveraging the Si H induced carbon-deficiency effect in precursors. Through a controlled reduction reaction, partial replacement of Si–OH with Si H groups facilitates carbon free radical migration during pyrolysis, promoting the rearrangement of both SiOC phases and free carbon structures. By tailoring Si H precursors and optimizing pyrolysis conditions, we synthesized SiOC ceramics with high reversible phase content (SiO 2 C 2 and SiO 3 C) and highly ordered free carbon. The M1-Ph-25% sample demonstrated an impressive reversible capacity of 849 mAh g −1 after 250 cycles at 0.5 A g −1 . Furthermore, in a full cell coupled with LiFePO 4 (LFP), over 100 mAh g −1 was achieved after 550 cycles at 0.2 A g −1 . This study provides valuable insights into the controlled fabrication of SiOC ceramics with tailored compositions and structures, offering a promising route for improving SiOC-based anodes in energy storage applications.