Binary-compositional core-shell structure Ni-rich cathode material with radially oriented primary particles in shell for long cycling lifespan lithium-ion batteries

Ni-rich layered oxides LiNixCoyMnzO2(denoted as NCM, x + y + z = 1, x ≥ 0.8) are prevailing cathode materials for lithium-ion batteries due to their high practical capacity and moderate cost. However, the inferior structural stability and rapid capacity fading stemming from the intergranular cracks induced by anisotropic volume changes in the deeply delithiated state significantly hamper the large-scale application of Ni-rich cathodes. In order to overcome these intractable issues, binary-compositional core-shell structure Ni-rich cathodes composed of LiNi0.6Co0.2Mn0.2O2(NCM622) shell and LiNi0.9Co0.05Mn0.05O2(NCM9055) core are proposed. In this unique core-shell structure, the low Ni fractional NCM622 shell with radially oriented primary particles could reduce the surface side reaction with electrolyte and alleviate internal stress, thereby effectively inhibiting the intergranular crack formation. Specifically, 40 wt% NCM622 coating NCM9055 cathode exhibits a high reversible discharge capacity of 160.5 mA/h/g with a remarkable capacity retention of 85.0% after 200 cycles at 0.5 °C, which is far superior to the pristine NCM9055 cathode with a low reversible capacity of 123.2 mA/h/g and inferior capacity retention of 62.9%. This work provides a new insight into the rational design of Ni-rich cathodes with high structural stability and long cycling lifespan.