Al2O3 coated LiNi1/3Co1/3Mn1/3O2 cathode material by sol–gel method: Preparation and characterization

LiNi1/3Co1/3Mn1/3O2, a promising cathode material over conventional ones for lithium-ion battery, was synthesized via the sol–gel method. The cathode material was coated by Al2O3 through a modified coating process to improve the electrochemical cycle performance and rate capacity. For samples with thicker Al2O3 coating, there was an increase with a subsequent decrease in the discharge capacity for cut-off voltage increasing from 4.3–3.0 V to 4.5–3.0 V. The Al2O3 coating optimized at 5% can apparently improve the discharge capacity and the cycle performance of LiNi1/3Co1/3Mn1/3O2 at high voltage. Transmission electron microscope (TEM) images also confirmed uniform coating at this optimized content. Electrochemical impedance spectroscopy (EIS) and conductivity test results suggested suppression in the growth of charge transfer resistance and an enhancement in the conductivity for Al2O3-coated LiNi1/3Co1/3Mn1/3O2.