Improving Cycling Stability of Lithium-Rich Manganese Oxide Cathodes through Multi-Lanthanide Surface and Interface Engineering.

Lithium-rich manganese-based oxides (LLO) face significant challenges, such as severe capacity loss and voltage decay, limiting their practical applications in lithium-ion batteries. This study proposes a simple multiple lanthanide element doping strategy, which enables simultaneous surface and interface engineering to mitigate these issues. A lanthanide-rich layer decorated with fine lanthanide oxide Ce0.32La0.28Yb0.4O2 nanoparticles is formed on the Li1.2Mn0.54Co0.13Ni0.13O2 surface. At the same time, many strip-shaped and coherent nano-precipitates (Li1.2TMLa0.009O2, where TM represents transition metal element and La represents lanthanide elements) form inside the LLO grains. The precipitates strengthen the weak grain boundaries and interfaces and mitigate volumetric changes during cycling, which improves the electromechanical properties of the LLO structure. The modified LLO demonstrates enhanced cycling stability, retaining 80.4% capacity after 500 cycles compared to 69.8% for unmodified LLO, and improved voltage stability with an average drop of 1.95 mV per cycle versus 2.49 mV. This modification approach can also be applied to Co-free lithium-rich Li1.2Ni0.5Mn0.5O2 cathode materials, offering a general and effective strategy to enhance the cycling stability for a wide range of layered structure cathode materials.