The Ni-rich Co-poor layered cathode (LiNixCoyMn1-x-yO2, x ≥ 0.9) is a candidate for the next-generation lithium-ion batteries due to its high specific capacity and low cost. However, the inherent structural instability and slow kinetics of Li+ migration hinder their large-scale application. Mo doping is proposed to enhance the crystal structure stability of LiNi0.9Co0.05Mn0.05O2 and to ensure the preservation of the spherical secondary particles after the cycle. The characterization results indicate that Mo doping not only significantly relieves the lattice strain accompanied by H2 → H3 phase transition but also alleviates particle stress accumulation to avoid pulverization. The Mo-modification allows the generation of uniform fine primary particulates and further agglomeration into the smooth secondary particles to inhibit electrolyte penetration. Hence, the Mo-modified sample NCM90-1%Mo displays an excellent capacity retention of 85.9% after 200 cycles at 0.5 C current density, which is 23.8% higher than that of the pristine NCM90. In addition, with the expansion of the Li slab to accelerate Li+ diffusion and the fine primary particles to shorten the Li+ pathway, the NCM90-1%Mo sample exhibits a high discharge capacity of 150 mAh g-1 at 5 C current density. This work provides a new thought for the design and construction of high-capacity cathode materials for the next-generation lithium-ion batteries.
Keywords: Ni-rich Co-poor layered cathode; kinetics of Li+ migration; lattice ion substitution (Mo doping); lattice strain; microstructure.