In situ surface modification via KMnO4 pre-oxidation enables air stability and high temperature resistance in LiNi0.83Co0.11Mn0.06O2 cathodes

In this work, the effect of potassium permanganate (KMnO 4 ) pre-oxidation treatment on the electrochemical properties of LiNi 0.83 Co 0.11 Mn 0.06 O 2 (NCM811) cathode materials was investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) tests revealed that the pre-oxidation treatment promoted the oxidation of Ni 2+ to Ni 3+ and the formation of a stable Mn-rich surface. Electrochemical testing showed that the electrochemical performance of the NCM811 material pre-oxidized with an appropriate amount of KMnO 4 (811–3) was significantly improved at both ambient (25 ℃) and elevated temperatures (55 ℃) compared to the untreated sample. Additionally, the air stability of 811–3 was enhanced. Specifically, the pre-oxidation treatment increased the oxidation state of nickel, minimized side reactions with CO 2 and moisture in the air, and improved cycling stability, rate performance, and lithium-ion diffusion. It also resulted in a lower self-discharge rate, ensuring better long-term voltage retention. These results indicated that KMnO 4 pre-oxidation is an effective strategy for improving the electrochemical performance of NCM811 and has the potential for application to other Ni-rich cathode materials.