posted on 2021-03-12, 18:08authored byLu Nie, Chao Liang, Shaojie Chen, Yingjie He, Weiyan Liu, Haojie Zhao, Tianyi Gao, Zhetao Sun, Qilin Hu, Yue Zhang, Yi Yu, Wei Liu
Lithium-rich
layered oxide cathodes with high specific energy have
become one of the most popular cathode materials for high-performance
lithium-ion batteries. However, spinel phase formation due to the
migration of transition metals and the release of lattice oxygen leads
to the degradation of electrochemical performance. Here, we develop
a synthesis approach for Li-rich layered oxide cathodes by a two-step
heat-treatment process, which includes precursor calcination and pellet
sintering. Compared with the sample prepared by the traditional one-step
calcination, the oxide particles prepared by the two-step heat treatment
show increased grain size from 217 to 425 nm. The Li-rich layered
oxide cathodes with larger crystal grains indicate a mitigated formation
of spinel phase and reduced voltage decay, which result in improved
specific capacity, cycle stability, and rate capability. In addition,
the thermal stability of the oxides is also improved. The improved
electrochemical performance is because of the large single grains
having a reduced contact area with a liquid electrolyte and the stable
crystal lattice during cycling. Our strategy not only provides a simple
and effective way to enhance the stability of the Li-rich layered
oxide cathodes but also extends to the preparation of oxide powders
with large grains.