Oxygen vacancies in CeO2 surface coating to improve the activation of layered Li1.2Mn0.54Ni0.13Co0.13O2 cathode material for Li-ion batteries

This work reports the surface coating of Li1.2Mn0.54Ni0.13Co0.13O2 cathode material with nano-CeO2 by a versatile hydrothermal method. Thus, obtained nano-CeO2-coated Li1.2Mn0.54Ni0.13Co0.13O2 material was characterized by XRD, SEM, and TEM. It is revealed that the synthesized nano-CeO2 material has rich oxygen vacancies, and a spinel-phase layer is formed on the surface of host material. The electrochemical testing results show that Li1.2Mn0.54Ni0.13Co0.13O2 with 4 wt% CeO2 coating (denoted as C3) has good rate capability and enhanced cyclic stability, enhanced initial discharge capacity of 298.5 mA h g−1 (0.05 C) compared to 281.9 mAh g−1, and excellent initial coulombic efficiency of 86.94% compared to 77.28% for the pristine one in the potential range 2.0–4.8 V (vs. Li/Li+). It is worth noting that this modified strategy greatly reduces the irreversible capacity loss (ICR) of the first cycle of active materials, the ICR of the C3 (44.8 mAh g−1) is markedly lower than pristine material (82.9 mAh g−1) at the current density of 12.5 mA g−1 (0.05 C). Such improvements are mainly ascribed to the oxygen vacancies in nano-CeO2 coating layer, which are responsible for the promoted activation of Li2MnO3. Moreover, the formation of the spinel structure is beneficial to stabilize the crystal lattice of the bulk material and facilitate Li+ diffusion by unique 3D transport channels.