Theoretical Study on Inhibition of Oxygen Evolution in Layered Cathode Materials during Charging

Abstract

In recent years, Ni, Mn-based layered cathode materials (Li1.2Ni0.2Mn0.6O2, LiNi1-x-yCoxMnyO2) have shown great promise for high energy density LIBs. Research has shown that nickel-rich materials are ideal candidates for high-capacity batteries. The valence state from Ni2+ to Ni4+ allows more Li+ to transfer between the cathode and anode, providing excellent electrochemical performance. However, the oxidation of oxygen atoms triggers irreversible structural rearrangements on the surface, while Ni3+ introduces Jahn-Teller distortion. At high voltages, the stability of layered cathode materials is severely hampered. We present theoretical work on Li1.2Ni0.2Mn0.6O2 and LiNi1-x-yCoxMnyO2 using density functional theory, considering cation- and anion-doped surface treatments. We found that doped layered cathode materials successfully suppressed O2 formation at highly delithiated levels. Through DFT calculations, we understand the mechanism of oxygen evolution from layered cathode materials during the charging process and discover how to suppress oxygen evolution strategies.