Suppressing Li⁺ crosstalk and sequencing delithiation in silicon-graphite anodes via active oxide nanoparticles

Silicon-graphite (Si-Gr) anodes for lithium-ion batteries suffer from incompatible volume changes and competitive lithium-ion transport, leading to localized electrochemical potential disturbances and rapid capacity degradation. Existing strategies, ranging from nanoscale engineering to gradient electrode designs, remain limited in universally regulating their (de-)lithiation behavior. Here, we revisit lithiable oxide coatings, using TiO₂ as an example, traditionally seen as passive buffers. Combined electrochemical-mechanical simulation and experimental validation reveal that TiO₂ promotes a more homogeneous Li⁺ distribution, alters overpotential dynamics, and sequences the delithiation process-Gr delithiates preferentially and more completely before Si activation. This regulation suppresses concurrent delithiation, reduces polarization, and fosters a stable solid electrolyte interphase (SEI). Consequently, the TiO₂-modified electrode exhibits significantly enhanced rate capability and cycling stability. Crucially, this approach demonstrates practical efficacy in 4.9 Ah LiCoO₂ || CSi/Gr pouch full-cells, where the TiO₂-modified cell retains a higher reversible capacity of 3.71 Ah after 300 cycles at 1.5C-rate, compared to 3.47 Ah for the unmodified cell, alongside mitigated polarization. The generality of this strategy is confirmed using other oxides (Fe₃O₄, ZnO, Nb₂O₅), providing a scalable materials-level solution to decouple chemo-mechanical interplay in high-Si-content anodes.