CeOx enhanced electrochemical performance of LiNi0.80Mn0.1Co0.1O2 cathode active material for Li-ion batteries

Nickel-rich layered oxides, such as LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NMC811), are considered as an attractive cathode active material (CAM) due to their high power and high energy density. However, NMC811 CAM faces severe challenges, such as structural instability and high surface reactivity at high voltages. To overcome these challenges, cerium doping by solid-state synthesis route and CeO x coatings by atomic layer deposition (ALD) technique not only stabilize the NMC811 structure but also provide a safe protective layer on the electrode surface. The optimized electrochemical performance achieved by incorporating cerium into the NMC811 structure enhances cycling stability at the voltage range of 3.0 - 4.4 V in Li half-cells, as confirmed by X-ray absorption spectroscopy (XAS), indicating a cerium oxidation state of +4. Likewise, CeO x coatings (∼1 nm) by ALD technique enhances the rate performance and cycling stability at high voltages (3.0 - 4.6 V) in Li half cells due to the formation of Ce 3+ on the surface of NMC811 electrodes, confirmed by XAS analysis. Overall, doping and coating demonstrate that cerium is effective in both strategies, especially the ALD technique helps to reduce metal dissolution, better cycling stability and achieve high voltage operations. This work highlights the role of cerium incorporated by doping and coatings on the surface in order to stabilize the NMC811 structure and suppress the parasitic reactions that occur at high voltages to utilize the full capacity.