Oxygen Vacancies and Ordering of d‐levels Control Voltage Suppression in Oxide Cathodes: the Case of Spinel LiNi0.5Mn1.5O4‐δ

Abstract This study presents a microscopic model for the correlation between the concentration of oxygen vacancies and voltage suppression in high voltage spinel cathodes for Li‐ion batteries. Using first principles simulations, it is shown that neutral oxygen vacancies in LiNi 0.5 Mn 1.5 O 4‐ δ promote substitutional Ni/Mn disorder and the formation of Ni‐rich and Ni‐poor regions. The former trap oxygen vacancies, while the latter trap electrons associated with these vacancies. This leads to the creation of deep and shallow Mn 3+ states and affects the stability of the lattice Li ions. Together, these two factors result in a characteristic profile of the voltage dependence on Li content. This insight provides guidance for mitigating the voltage suppression in LiNi 0.5 Mn 1.5 O 4 and other cathodes.