Local structure modification in lithium rich layered Li-Mn-O cathode material

X-ray absorption spectroscopy (XAS) is applied to study the local geometry of Co, Ni, and Mn sites in a new high voltage cathode for lithium batteries. The material is a solid solution between Li${}_2$MnO${}_3$ and Li${}_{(x)}$Mn${}_{0.4}$Ni${}_{0.4}$Co${}_{0.2}$O${}_2$. The XAS technique has permitted to check the local atomic structure and charge associated with the metals in a series of electrodes with different lithium concentration x, obtained during the first charge operation, and compared to the first discharge and a successive charge. The ex-situ XAS investigation on the initial activation of the cathode material (first charge) can be described by two separated reaction of LiMO${}_2$ (M = Ni and Co) and Li${}_2$MnO${}_3$. The strength and limitations of the EXAFS approach in these materials is underlined.