Cerium Oxide Coating on Nickel-Rich Oxide Cathodes to Mitigate Lithium-Ion Battery Thermal Runaway

Nickel-rich layered oxide cathodes are promising for next-generation lithium-ion batteries due to their high energy density and lower cost compared to the lithium cobalt oxide (LCO) cathode. However, their practical application is often limited by their thermal instability at high nickel content, which is associated with oxygen evolution and the risk of thermal runaway. In this study, discrete cerium oxide (CeO2) nanoparticles were coated on Li[Ni0.91Co0.05Mn0.03Al0.01]O2 (NCMA) cathodes via the coprecipitation method in water. CeO2 with the low redox potential of Ce3+/Ce4+ couple serves as an oxygen storage material on the surface of the NCMA cathode. The CeO2-coated NCMA (C-NCMA) shows 30% less total heat release and a higher onset temperature of cathode decomposition than uncoated NCMA (P-NCMA) due to 3.6% less oxygen release and robust barriers between the NCMA cathode surface and the electrolyte. Furthermore, long-term cycling stability at 25 °C and enhanced cycling performance at 45 °C with a low cutoff voltage (4.2 V) were observed for C-NCMA due to the suppression and delay of the H2–H3 phase transition peak, despite the kinetic hindrance from the relatively thick CeO2 nanoparticles. At a higher cutoff voltage (4.5 V) under severe cycling conditions, C-NCMA shows a capacity retention of 96.4% after 60 cycles compared to 84.4% for P-NCMA. To obtain both enhanced thermal stability and improved cycling performance, the cutoff voltage should be pushed to a higher value for these discrete CeO2 nanoparticle coating morphologies. This study presents an outlook on the rationale for applying discrete nanoparticle coatings to nickel-rich cathode materials for future battery development.