STUDY OF THE SURFACE REACTIVITY OF Ni-RICH POSITIVE ELECTRODE MATERIALS FOR Li-ION CELLS

Abstract

The growth of surface impurities on positive electrode materials used in Li-ion cells is detrimental to the electrochemical performance of the cells. Ni-rich layered lithium metal oxides are promising materials for the production of high capacity Li-ion batteries but are prone to surface impurity growth. For this reason, it is common in industry to wash these materials. However, very little mechanistic understanding of the reaction between the materials and the aqueous solution used for washing is known. In this work, the effects of exposing Ni-rich positive electrode materials to aqueous solutions were studied. Additionally, core-shell materials containing a gradient-concentration of Ni were tested for the possibility to increase the air stability of Ni-rich positive electrode materials with minimal compromise to electrochemical properties. By improving both the washing process for Ni-rich materials and increasing their air stability, Ni-rich positive electrodes could reach high performance levels which are currently, commercially unattained.