Mo Doping to Modify Lattice and Morphology of the LiNi<sub>0.9</sub>Co<sub>0.05</sub>Mn<sub>0.05</sub>O<sub>2</sub> Cathode toward High-Efficient Lithium-Ion Storage
Liang Qiao, Qi You, X. Ben Wu, Huihua Min, Xiaomin Liu, Hui Yang
Abstract
The Ni-rich Co-poor layered cathode (LiNi x Co y Mn 1– x – y O 2, 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 LiNi 0.9 Co 0.05 Mn 0.05 O 2 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.