Enhanced cycling stability of Sn-doped Li[Ni₀.₉₀Co₀.₀₅Mn₀.₀₅]O₂ via optimization of particle shape and orientation

Abstract

Ni-rich Li[NixCoyMn1-x-y]O-2 (x >= 0.8) cathodes suffer from structural degradation and capacity fading owing to the microcracks generated by abrupt volume contraction in the deeply charged state. To resolve this problem, the substitution of Ni by Sn in Li[Ni0.90Co0.05Mn0.05]O-2 is proposed. Li[Ni0.897Co0.05Mn0.05Sn0.003]O-2 (SnNCM90) has a unique microstructure in which the primary particles are oriented along the radial direction. This radial alignment, combined with the (001) crystallographic texture, suppresses microcrack formation and propagation by effectively relieving an internal strain in the deeply charged state. The microstructure-modified Sn-NCM90 cathode delivers a discharge capacity of 224.3 mAh g(-1) and exhibits a capacity retention of 92.9% after 100 cycles at 4.3 V and 82.9% at 4.4 V. The proposed Sn substitution method shows that appropriate microstructural modification of the cathode can improve the cycling stability of Ni-rich layered cathodes.