Recent research points to significant oxygen involvement during the charging of nickel-based lithium-ion cathode materials . Such activity is evidenced by incomplete oxidation from Ni 3+ to Ni 4+ in LiNiO 2 at the top of charge , alongside resonant inelastic X-ray scattering (RIXS) spectra that indicate oxygen-redox activity and oxygen dimer formation . These phenomena have drawn comparison with known behaviors in lithium-rich cathodes. In these systems anion-redox activity is coupled with transition metal migration and the formation of voids that facilitate the stabilization of molecular-oxygen-like dimers , with a similar mechanism now being proposed in LiNiO 2 and other nickelrich automotive-grade cathode materials .