Modeling of Thermomechanical Properties of SiBOC Ceramics: A Molecular Dynamics Approach

ABSTRACT This study employs molecular dynamics (MD) simulations to investigate the atomic structure, mechanical stability, and lithium storage behavior of silicon–boron–oxycarbide (SiBOC) ceramics. The incorporation of boron into the SiOC matrix enhances network connectivity via Si–B–O and B–O–C linkages, improving structural flexibility and Li‐ion diffusion. Theoretical analysis reveals that the specific capacity increases from 1747 to 5243 mAh/g as the Li content rises from 0.1 to 0.2 wt.%, underscoring the material's high energy storage potential. Increasing the free carbon content slightly reduces the theoretical capacity but enhances the reversible capacity from 451 to 997 mAh/g (0.2–5.3 wt.% C), due to improved conductivity and lithium reversibility. Radial distribution function (RDF) analysis reveals strong Li–Si interactions (2.3–2.5 Å), which explains the partial irreversible trapping, while the mean square displacement (MSD) confirms faster Li diffusion in SiBOC than in SiOC. Porosity decreases from 26% to 5% with the addition of carbon, yielding a denser and more robust structure. SiBOC also exhibits minimal volume expansion (3%–5%), which is significantly lower than the ∼300% swelling observed in pure silicon. Overall, SiBOC with optimal boron (∼0.8 wt.%) and carbon (∼4–5 wt.%) content offers high capacity, excellent reversibility, mechanical integrity, and dimensional stability—ideal for next‐generation lithium‐ion battery anodes.