Enhanced electrochemical properties of LiNiO2-based cathode materials by nanoscale manganese carbonate treatment

LiNiO 2 -based layered oxides are of great importance as cathode materials for rechargeable batteries. In this paper, illustrating LiNi 0.8 Co 0.15 Al 0.05 O 2 as an example, the effect of nanoscale MnCO 3 treatment on LiNiO 2 -based materials is investigated for the first time. The structures of materials and the properties about the object surface are characterized by XRD, SEM, TEM, EDAX and XPS. The results demonstrate that a part of MnCO 3 is able to react with lithium impurities to form nonstoichiometric Li x Mn y O 4 and the rest of MnCO 3 is converted to MnO 2 coating on the surface of the material in situ. After 100 repeated cycles at 1C, the modified material exhibits a capacity retention rate of 91.2%, while the bare material only remains 84.8%. And the modified material exhibits more significantly improved cycling stability when cycling at 60   °C, maintaining 85.7% of its initial capacity at 1C after 100th cycles. The consumption of Li impurities can decelerate the decomposition of electrolyte during cycling, thus result in less resistive byproducts. Moreover, the obtained MnO 2 coating layer acts as an isolating layer to suppress the drastic reaction between active material and electrolyte. This synergistic effect is responsible for the excellent properties of MnCO 3 -modified material.