Operando Investigation of Zr Doping in NMC811 Cathode for High Energy Density Lithium Ion Batteries

Abstract LiNi0.8Mn0.1Co0.1O2 (NMC811) is one of the most promising cathode materials for high energy density Li‐ion batteries (LiBs). However, NMC811 suffers from capacity fading during electrochemical cycling because of its structure instability at voltages >4.2 V vs Li|Li + due to the known hexagonal H2→H3 phase transition. Zr doping has proven to be effective in enhancing electrochemical performances of the NMC811. In depth investigations are conducted through operando x‐ray diffraction (XRD) and ex situ x‐ray absorption spectroscopy (XAS) measurements to mechanistically understand the benefits of Zr‐doping in a NMC811 material when doped during the co‐precipitation step. Herein, Zr‐doping in NMC811 reduces the formation of the detrimental H3 phase and mitigates the transition metal dissolution upon cycling.