Hybrid Density Functional Theory Comparison of Oxygen Release and Solvent Decomposition Kinetics on LiNiO₂ Surfaces

High-nickel-content layered oxides are among the most promising electric vehicle battery cathode materials. However, their interfacial reactivity with electrolytes and tendency toward oxygen release (possibly yielding reactive ¹O₂) remain degradation concerns. Elucidating the most relevant (i.e., fastest) interfacial degradation mechanism will facilitate future mitigation strategies. We apply screened hybrid density functional (HSE06) calculations to compare the reaction kinetics of LiNiO₂ surfaces with ethylene carbonate (EC) with those of O₂ release. On both the (001) and (104) facets, EC oxidative decomposition exhibits lower activation energies than O₂ release. Our calculations, coupled with previously computed liquid-phase reaction rates of ¹O₂ with EC, strongly question the role of "reactive ¹O₂" species in electrolyte oxidative degradation. The possible role of other oxygen species is discussed. To deal with the challenges of modeling LiNiO₂ surface reactivity, we emphasize a "local structure" approach instead of pursuing the global energy minimum.