Layered LiNi0.8Co0.1Mn0.1O2 oxide (NCM811)
has attracted wide attention as a candidate
for the high-energy cathode in lithium-ion batteries (LIBs). It is
necessary to amend both the insufficient cycling life caused by microstructural
degradation and the poor rate capability due to the restricted kinetics,
especially at high voltage. Here we design and synthesize a special
NCM811 (R-NCM), containing primary particles arranged radially from
the surface to the interior, to address these issues. Compared with
the structure of primary particles randomly distributed in conventional
NCM811 (C-NCM), this special microstructure in R-NCM shows more reversible
cell volume variation, providing more open paths for Li+ transfer, and, more importantly, it significantly alleviates the
mechanical stress induced by volume variation inside the particle
when cycled to high voltage. Consequently, R-NCM delivers high reversible
capacity (221.5 mAh g–1 at a current rate of 0.2
C) and increased rate capability (143 mAh g–1 at
a current rate of 10 C) under a cutoff voltage of 4.6 V. Moreover,
the long-term cycling stability in R-NCM at 4.6 V is remarkably increased
due to the special microstructure. This morphological design provides
a method for preparing advanced cathode materials for practical applications.
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