Pr doped single-crystal LiNi0.5Mn0.3Co0.2O2 cathode enables high rate capability and cycle stability for lithium ion batteries

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.