Improving the Ni-rich LiNi0.5Co0.2Mn0.3O2 cathode properties at high operating voltage by double coating layer of Al2O3 and AlPO4

Al2O3 and AlPO4 single-coated and double-coated LiNi0.5Co0.2Mn0.3O2 materials have been synthesized by a wet-coating method in this paper. XRD, XPS, SEM, TEM, DSC as well as electrochemical methods are employed to investigate the structure, surface properties, thermal stability as well as electrochemical properties. The obtained layers are homogenously coated on the particles and the coating thickness is around 20–30 nm, the surface compositions are analyzed by XPS in detail as well. Comparing with those single-coated or uncoated samples, the double-coated one exhibits more superior thermal stability as well as electrochemical properties. The possible reason is mainly due to the dense and uniform coating layer as well as the formation of Li3PO4 and LiAlO2 on the cathode surface. Based on these results, it seems that Al2O3 and AlPO4 double-coating is an efficient strategy in improving the properties of LiNi0.5Co0.2Mn0.3O2 materials, which can be also applied to other Ni-rich layered materials.