Effect of Particle Morphology on the Cycle Life of LiNixCoyMn1-x-YO2 Electrode in Li-Ion Cell

LiCoO2 is one of the widely used cathode material in portable Li-ion batteries. Cobalt is expensive metal, therefore it is substituted with cheaper metals such as nickel, but the delithiated structure of Li_xNiO₂ is not thermally stable in the presence of organic electrolyte. However, as a result of partial substitution of cobalt with nickel and manganese, LiNi_xCo_yMn_1-x-yO₂ has high thermal stability and is widely investigated as positive electrode material for the Li-ion batteries.

The aim of this research was to understand how metal substitutions and particle morphology effect on the electrode cycle life in the Li-ion cell.  Electrode materials LiCoO₂ and LiNi_xCo_yMn_1-x-yO₂ were prepared from a several of precursors under different synthesis conditions to achieve optimal crystal sizes and morphologies for Li-ion cell. Phase purities and crystal sizes were studied by XRD and morphologies of particles were investigated by FESEM from the electrode foil cross-sections. After electrochemical cycle tests, the morphologies of particles were re-investigated to see how the testing affect to the different morphologies and chemistries of samples.

Results indicate that crystal size and morphology has big influence on the electrochemical cycling properties of LiNi_xCo_yMn_1-x-yO₂ electrode material in the Li-ion cells. The optimum particle size and morphology were obtained from the experiments and discussed.