Electrochemical performance studies of Li-rich cathode materials with different primary particle sizes

The spherical Li-rich materials 0.3Li₂MnO₃·0. 7LiNi_0.5Mn_0.5O₂ are synthesized by a standard co-precipitation method followed by solid state sintering. The primary particle size and morphologies of the 0.3Li₂MnO₃·0. 7LiNi_0.5Mn_0.5O₂ materials can be readily controlled by altering the heat-treatment temperature. With different primary size, the materials show different rate discharge capabilities. However, due to similar chemical composition, they show similar discharge capacity at high temperature and low current density. Subsequent galvanostatic intermittent titration tests indicate that the larger the particle size, the larger the chemical diffusion coefficient of the Li⁺. The relationship between the primary particle size and electrochemical kinetics is discussed. Of all the samples in this study, the material with a primary particle size of 200 nm, obtained at 900 C, exhibits the best integrated electrochemical performance.