Al-doping induced superior lithium ion storage capability of LiNiO2 spheres.

To optimize the performance of LiNiO 2 with minimal modification of the pristine structure, a facile solid-state approach, based on the interdiffusion of elements at the solid/solid interface, is developed to achieve uniformly Al-doped LiNiO 2 using alumina coated Ni(OH) 2 spheres as the precursor. The resulting LiNi 0.95 Al 0.05 O 2 material exhibits excellent discharge capacity (209.9 mAh g−1 at 0.1 C) and cycling stability with a capacity retention of 85.10% after 200 cycles at 0.5 C. This is ascribed to the improved reversibility of the phase transitions by Al-doping as revealed by in-situ XRD characterization. The Al-doping also endows the material with superior rate capability due to the enlarged interlayer spacing in the structure and alleviation of the side reactions at the electrode/electrolyte interface, favorable for lithium ion diffusion. An optimal amount of doped Al is necessary for ensuring the structure stability and interface ionic conductivity of the LiNiO 2 spheres. Thus, the present strategy may provide an opportunity to optimize the performance of LiNiO 2 , with uniform doping of a small amount of Al, producing a promising cathode material for advanced lithium ion batteries. [ABSTRACT FROM AUTHOR]