Electrochemical Kinetics and Cycle Stability Improvement with Nb Doping for Lithium-Rich Layered Oxides

Lithium-rich layered oxide materials are extremely important for improving the energy density of lithium-ion batteries. However, the electrochemical kinetics and cycle stability of these materials are still not good enough for further industrial application. Here, the effects of Nb doping on the crystalline structure, surface chemistry, cycle stability, and electrochemical kinetics of Li1.13Mn0.52Ni0.26Co0.10O2 are studied. Results show that Nb doping can significantly promote the cycle stability and electrochemical kinetics of Li1.13Mn0.52Ni0.26Co0.10O2. After 200 cycles, the discharge capacity retention increases from 59.2% (pristine material) to 78.8% (1% Nb element doping) with obvious enhanced rate performance. Via X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and galvanostatic intermittent titration analysis, it is confirmed that Nb element has been successfully doped into the bulk of Li1.13Mn0.52Ni0.26Co0.10O2. Doping sites of Nb element in structure and influence on lithium migration has also been studied by the Rietveld refinement and first principle theoretical calculation methods. Doped Nb element efficiently changes the lattice parameters, inhibits the resistance rise, accelerates lithium ion diffusion, and finally promotes the cycle stability, and electrochemical kinetics of Li1.13Mn0.52Ni0.26Co0.10O2.