posted on 2021-11-17, 16:33authored byYang-Yang Wang, Xiang Song, Sheng Liu, Guo-Ran Li, Shi-Hai Ye, Xue-Ping Gao
The
merits of Ni-rich layered oxide cathodes in specific capacity
and material cost accelerate their practical applications in electric
vehicles and grid energy storage. However, detrimental structural
deterioration occurs inevitably during long-term cycling, leading
to potential instability and capacity decay of the cathodes. In this
work, we investigate the effect of the doped cation radius on the
electrochemical performance and structural stability of Ni-rich cathode
materials by doping with Mg and Ca ions in LiNi0.8Co0.1Mn0.1O2. The results reveal that an
increase in the doping ion radius can enlarge the interlayer spacing
but lead to the collapse of the layered structure if the ion radius
is too large, which undermines the cycling stability of the cathode
material. Compared with the Ca-doped sample and the pristine material,
Mg-doped LiNi0.8Co0.1Mn0.1O2 presents improved structural stability and superior thermal stability
due to the pillar and glue roles of medium-sized Mg ions in the lithium
layer. The results of this study suggest that a suitable ionic radius
of the dopant is critical for stabilizing the structure and improving
the electrochemical properties of Ni-rich layered oxide cathode materials.