Pr doped single-crystal LiNi0.5Mn0.3Co0.2O2 cathode enables high rate capability and cycle stability for lithium ion batteries
Xiaopei Zhu, Yu Han, Lina Cheng, Feifei Xu, Zilu Wang, Li‐Zhen Fan
Abstract
The massive application of single crystal (SC) ternary cathode material LiNi1-x-yMnxCoyO2 is largely restricted by the unsatisfactory rate capability which is caused by the sluggish Li+ diffusion and structural instability. Herein, Pr3+, a large radius ion is introduced to single-crystal LiNi0.5Mn0.3Co0.2O2 to enhance Li + conductivity and structural stability. With 0.4% Pr doping, the Li(Ni0.5Mn0.3Co0.2)0.996Pr0.004O2 cathode displays a capacity retention of 79.72% at 10 C, and a 98.17% capacity retention after 50 cycles at 25 °C and 96.3% capacity retention after 50 cycles at 55 °C within a 3.0–4.5 V voltage window. Electrochemical impedance spectroscopy confirms that the Pr doping can effectively lower the charge-transfer resistance and facilitate the transportation of Li+ on the surface of LiNi0.5Mn0.3Co0.2O2. The Direct current internal resistance result implies that the structure of the Pr-doped cathode particles is more stable during cycling. In addition, differential scanning calorimetry measurements measurement combined with in situ X-ray diffraction confirms the thermo-stabilization effect of the Pr dopant.