Significantly improving energy density of cathode for lithium ion batteries: the effect of Li-Zr composite oxides coating on LiNi0.6Co0.2Mn0.2O2
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LiNi0.6Co0.2Mn0.2O2 (NCM622) powders with Li-Zr composite oxides coating layers are synthesized by solid-state reaction using Ni0.6Co0.2Mn0.2(OH)2, Li2CO3, and nano-ZrO2 as raw materials. The morphology is characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the phase composition is analyzed by X-ray diffraction (XRD). 0.5 mol% Zr-modified NCM622 exhibits a discharge capacity of 208.1 mAh g−1 and a cathode energy density of 811.6 Wh kg−1 over 3.0~4.5 V, which is 36.0 Wh kg−1 higher than the pristine NCM622’s. The coated nano-ZrO2 might react with residual LiOH and Li2CO3 on the surface of NCM622 and formed Li8ZrO6 and Li2ZrO3; these Li-Zr composite oxides are good lithium-ion conductors which could improve lithium-ion diffusion and reduce the interface impedance with electrolyte. In addition, Li8ZrO6 might partly participate in (de)lithiation reaction during 3.0~4.5 V and induces higher energy density.
KeywordsLi-Zr composite oxides coating layer Li8ZrO6 LiNi0.6Mn0.2Co0.2O2 Energy density Lithium-ion battery
The authors are very grateful for the financial support from Youth Innovation Fund of BGRIMM Technology Group Co, Ltd.
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