Improvement of structural and electrochemical properties of AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode materials on high voltage region

The particle surface of Li[Ni1/3Co1/3Mn1/3]O2 was modified by AlF3 as a new coating material to improve the electrochemical properties in the high cutoff voltage of 4.5 V. The AlF3-coated Li[Ni1/3Co1/3Mn1/3]O2 showed no difference in the bulk structure compared with the pristine one and the uniform AlF3 coating layers whose thickness is of about 10 nm covered Li[Ni1/3Co1/3Mn1/3]O2 particles, as confirmed by a transmission electron microscopy. The AlF3 coating on Li[Ni1/3Co1/3Mn1/3]O2 particles improved the overall electrochemical properties such as the cyclability, rate capability and thermal stability compared with those of the pristine Li[Ni1/3Co1/3Mn1/3]O2. Such enhancements were attributed to the presence of the stable AlF3 layer which acts as the interfacial stabilizer on the surface of Li[Ni1/3Co1/3Mn1/3]O2.