Morphological Control to Enhance Diffusion Kinetics and Structural Stability on Li-Rich Layered Oxides Cathode for Long-Cycle Batteries

The morphology of cathode materials usually plays a crucial role in determining their electrochemical performance. It is a major research focus aimed at improving Li⁺ diffusion kinetics and enhancing structural stability on Li-rich layered oxides cathode. In this work, through finite element analysis simulations, thin plate particles with a lower ratio of active planes exhibit a more uneven Li⁺ concentration distribution and severe stress accumulation between the active and inactive planes after almost complete deintercalation. Columnar polyhedron and thin plate shapes were synthesized by controlling the precursor components using the typical carbonate and hydroxide coprecipitation method, respectively. It is found that the columnar polyhedron shape has a higher proportion of active planes compared to the thin plate shape. As a result, materials with a higher proportion of active planes exhibit superior Li⁺ diffusion kinetics and enhanced stability during cycling; specifically, the more satisfied Li⁺ diffusion coefficient and 88.3% capacity retention ratio following 200 cycles, while those with fewer active planes face challenges in maintaining capacity retention due to structural degradation, characterized by scanning transmission electron microscopy-high angle annular dark field and geometric phase analysis. Further research into optimizing the morphology for improved electrochemical properties is warranted.