Improved low-temperature performance of surface modified lithium-rich Li1.2Ni0.13Co0.13Mn0.54O2 cathode materials for lithium ion batteries

High capacity lithium-rich layered oxide Li1.2Ni0.13Co0.13Mn0.54O2 cathode material is considered as a most promising cathode material for lithium ion batteries. However, its application is greatly limited due to the characteristics of low initial coulombic efficiency and poor low-temperature performance. In this study, AlF3-coated Li1.2Ni0.13Co0.13Mn0.54O2 has been prepared via a facile wet chemical process. It is found that a dense AlF3 layer with a nanoscale thickness is covered on the surface of Li1.2Ni0.13Co0.13Mn0.54O2 particles, building a rapid lithium transport bridge for adjacent active materials and reducing side reaction between the electrolyte and active material. Compared to the pristine Li1.2Ni0.13Co0.13Mn0.54O2, 2% AlF3-coated sample exhibits higher discharge capacity and initial coulombic efficiency (86.7%). Meanwhile, 2% AlF3-coated sample displays obviously superior rate capability at 0 degrees C and higher capacity retention at -10 and - 20 degrees C. The improvement of low-temperature performance can reasonably be attributed to the formation of the spinel structure and the LiAlO2 on the surface of the active materials, which can improve the electronic conductivity and lithium ion conductivity of the cathode material, respectively.