First-principles modeling of PVdF on oxidized silicon surface for next-generation Li-ion anodes

Silicon’s high theoretical capacity makes it a promising anode material for lithium-ion batteries (LIBs). However, challenges such as volume expansion and an unstable solid electrolyte interphase (SEI) limit its practical application. This study investigates the role of polyvinylidene fluoride (PVdF) binders in addressing these challenges by exploring the effects of oxygen surface coverage and PVdF phase on the silicon-binder interface using density functional theory (DFT). The results reveal that oxygen coverage enhances the binding of PVdF to silicon surfaces, significantly improving the interfacial stability in specific configurations. For α -PVdF, increasing oxygen coverage induces surface polarization, leading to weaker binding interactions, while β -PVdF exhibits contrasting behaviors depending on its orientation. When β -PVdF faces the silicon surface with its hydrogen side, it forms a stronger bond due to favorable dipole alignment and charge transfer. In contrast, the fluorine side orientation of β -PVdF results in weaker interactions due to repulsion from the oxidized surface. These findings provide valuable insights into the molecular interactions at silicon-binder interfaces, highlighting the critical role of oxygen and PVdF phase in optimizing the performance of silicon-based anodes for next-generation LIBs. • Quantifying the effect of oxygen on interfacial stability and PVdF adsorption energy. • Detailed analysis of binding mechanisms through CDD and DOS analyses. • Insights into the role of PVdF phase and orientation on interfacial interactions. • Implications for designing novel silicon-based anode materials with improved performance.