Na Doping and CeO₂ Nanoparticle Surface Modification Enhancing the Li-Rich Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ Cathode Material for a Lithium-Ion Battery

Li-rich Mn-based layered oxides with high specific capacity and operating voltages have become one of the most promising materials for lithium-ion batteries (LIBs). However, it still faces several issues of low initial Coulombic efficiency, poor electronic conductivity, and voltage fading due to oxygen release and transition metal rearrangement during cycling. In this study, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ (LMR) cathode material with Na ion doping (LMNaR) and CeO₂ nanoparticle surface modification (LMNaR@CeO₂) is prepared to realize a synergistic modification effect. The doping of Na ions enlarges Li layer spacing to effectively promote the insertion and extraction of lithium ions, which makes the layered structure more stable to reduce the effect of the phase transition. And the CeO₂ nanoparticle surface modification restrains the side reactions between electrode and electrolyte, stabilizes lattice oxygen, and eases oxygen release. As a result, LMNaR@CeO₂ displays a specific capacity of 196 mAh g^-1 after 100 cycles at 0.5 C with a capacity retention of 94% and a merely voltage decay of 0.16 V, which are much better than those of LMR with a specific capacity of 159.6 mAh g^-1 and only a 79% capacity retention. Our strategy here provides a feasible approach for the development of Li-rich Mn-based cathode materials for long-lived LIBs.