Eu2O3-doped Li4SiO4 coating layer with a high ionic conductivity improving performance of LiNi0.8Co0.1Mn0.1O2 cathode materials

Ni-rich layered cathode materials are being paid much attention to because their high capacity can handily improve energy density of lithium-ion batteries. However, Ni-rich cathode materials still suffer from the deficiencies such as poor cycle stability, weak structural and thermal stability. In this work, Eu2O3-doped Li4SiO4 with an enhanced ionic conductivity is proposed as surface coating layer for LiNi0.8Co0.1Mn0.1O2 (NCM) cathode material to improve the capacity retention and structural stability during cycling. The doping of Eu2O3 in Li4SiO4 makes the coating layer have higher ion conductivity and better stability than pure Li4SiO4 layer. When the doping amount is 10 mol% of Li4SiO4, the corresponding cathode material NCM-LS3-0.10Eu2O3 exhibits the optimal cycle and rate performance. The discharge specific capacity and capacity retention after 400 cycles at 1 C rate are 150.1 mAh g−1 and 80.48%, respectively. In particular, the NCM-LS3-0.10Eu2O3 secondary particles avoid the appearance of serious cracks and maintain excellent structural stability even after long cycling. It is proved finally that the Eu2O3-doped Li4SiO4 coating layer can not only inhibit the side reactions caused by the contact between electrode surface and electrolyte, but also reduce the resistance of lithium ion migration and suppress the microstructure changes caused by local stress.