Enhancing the cycling stability of nickel-rich oxide cathode materials through a multifunctional CeO₂ coating

The main challenges for the commercialization of LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) as a high-energy-density Li-ion metal-oxide cathode material are the inhibition of crystal structure collapse triggered by side reactions at the electrode-electrolyte interface, the release of lattice oxygen, and the formation of microcracks. Herein, a general strategy for synthesizing stable cerium oxide (CeO₂) coatings on the surface of NCM622 material is proposed to overcome the faced challenges. The coating can effectively slow down the rapid decline in capacity after charge/discharge cycles, in which the 1% CeO₂@NCM622 cathode exhibits excellent long-term stability with a capacity retention of 97.43% after 200 cycles at 1C, an increase of 21.35% over the pristine NCM622 cathode. The XPS test shows that the CeO₂ coating has good oxygen storage and release properties, effectively stabilizes the release of lattice oxygen in the layered structure, and suppresses the phase transition caused by lattice relaxation. The coating offers a new idea to further optimize the electrochemical performance of Li-ion nickel-rich (Ni-rich) cathode materials.