One-pot synthesis of LiAlO2-coated LiNi0.6Mn0.2Co0.2O2cathode material

Abstract

For the first time, a one-pot synthesis of LiAlO2-coated LiNi0.6Mn0.2Co0.2O2 particles, using a continuous stirred-tank reactor, is reported. Two methods of surface coating were compared with the pristine sample. The composition and morphology of the coated and uncoated cathode materials were characterised by MP-AES, XPS, SEM, and EDX. 27Al MAS NMR coupled with structural characterisation of the materials confirms the presence of a coating layer of LiAlO2 on the surface of the NMC particle with partial diffusion of Al3+ from the surface coating to the NMC structure. By comparing electrochemical performances and thermal stabilities of the coated and uncoated NMC particles at high temperature (45 °C) and at high cut-off voltage (3.0–4.4 V vs. Li+/Li), the coated samples indicate a significant improvement in cycling performance (specific capacity, capacity retention, and rate capability). EIS confirms that the LiAlO2 coating layer prevents side reactions resulting in reduced cathode electrolyte interphase formation and charge-transfer resistance.