Operando XAS investigation of LiNiO2 cathode for improved applications

Battery applications such as electric vehicles request high energy densities. In this context, layered LiNiO2 (LNO) cathode could contribute with the highest specific capacity in the LiNi1−x−yCoxMnyO2 (NCM) family. To achieve high capacities requires a defect free crystal structure, which is not easily achieved due to the natural occurrence of Ni excess on the Li site and/or anti-site defects where Ni and Li switch crystallographic sites. The amount of excess of nickel should be small to obtain a large rechargeable capacity, while the oxygen loss is widely recognized as a major factor in the structural degradation of Ni-rich layered cathode materials. A study on the role of the inevitable Li/Ni disordering defects is still lacking, and is the focus of the present proposal. Our aim is to characterize the evolution of the Ni electronic and local structural properties by means of Ni K-edge operando XAS study on a set of LiNiO2 cathodes with well characterized different Li+/Ni2+ mixing. We will focus on the effect of the Li+/Ni2+ mixing on the charge compensation mechanism. This approach will allow addressing fundamental electronical and structural aspects that define the functional properties of Ni-rich cathode materials for Li-ion batteries.