SeO2-infused grain boundaries effectively improve rate and stability performance of Li-rich manganese-based layered cathode materials

For polycrystalline lithium-rich manganese-based layered oxides (LMLO), the presence of porous microstructures always leads to the greater oxygen release and lower conductivity, impairing their rate and cycling stability performance for real applications. Here, by temperature-controlled annealing, we propose a facile and scalable method to infuse molten SeO2 into the intracrystalline grain boundary of the polycrystalline Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) particles. Then the uniform surface and double nanolayer structure composed of interconnected Li2SeO4 and robust Li2NixCoyO4 are revealed on primary particles. Accordingly, SeO2-infused LMNCO(Se-LMNCO) gains an upraised rate performance with 97 % capacity retenting rate after charge and discharge under 0.1–5 C then returned to 0.1 C and an improved cycling stability with a capacity retention of 80.0 % over 200 cycles at 1 C (1 C=250 mAh g−1). Our work highlights the significance of surface engineering inside the secondary LMLO particles and the improvement of electrochemical rate and stability performance toward lithium-ion batteries with LMLO electrode.