Optimizing the structure of layered cathode material for higher electrochemical performance by elucidating structural evolution during heat processing

Improving electrochemical performance of cathode materials for lithium-ion batteries requires comprehensive understanding of their structural properties which could facilitate or impede the diffusion of lithium during charge-discharge. In order to optimize the structure and improve the electrochemical performance of layered cathode material, the detailed structural evolution as a function of heat treatment temperature in LiNi0.8Co0.1Mn0.1O2 was investigated by in-situ and ex-situ neutron powder diffraction methods. We show that both cycling stability and rate performance of LiNi0.8Co0.1Mn0.1O2 can be improved by performing heat treatment at 400 °C, which is attributed to the optimization of surface structure and the enlargement of c/a ratio. Heat treatment of LiNi0.8Co0.1Mn0.1O2 at higher temperature induces a layered-to-rock-salt structure phase transition accompanied with the precipitation of lithium oxide. A 3D phase diagram, which correlates the high temperature phases and room temperature phases, is constructed. The presentation of comprehensive phase diagrams up to 1000 °C could provide the basis for further research on not only synthesis strategy but also thermal stability in Ni-rich layered cathode materials. © 2020 Elsevier Ltd.

Keywords

Neutron diffraction, Phase transformations, Cathodes, Lithium, Nickel, Lithium ion batteries

Citation

Huang, Z., Chu, M., Wang, R., Zhu, W., Zhao, W., Wang, C., Zhang, Y., He, L., Chen, J., Deng, S., Mei, L., Kan, W. H., Avdeev, M., Pan, F., & Xiao, Y. (2020). Optimizing the structure of layered cathode material for higher electrochemical performance by elucidating structural evolution during heat processing. Nano Energy, 78, 105194. doi:10.1016/j.nanoen.2020.105194