Rechargeable lithium-ion batteries still mainly use the layered oxide LiCoO2 as positive electrode and graphite as negative electrode for high capacity batteries developed for mobile devices. Nevertheless, LiCoO2 remains limited in energy density with a reversible capacity smaller than 160 mAh/g, expensive and with safety issues, to be maintained in large scale batteries for automotive applications. New systems such as Li[NixLi(1/3-2x/3)Mn(2/3-x/3)]O2 and (1-x )LiMO2.xLi2MnO3 (M = Ni, Co), rich in lithium and in manganese, were considered due an exceptionally high reversible capacity. The aim of the study is to get more insight into the atomic structure of the material Li1.20Mn0.54Co0.13Ni0.13O2 and especially into its changes upon cycling. Neutron PDF analysis will allow solving specific issues related with short range / long range disordering / ordering in the materials recovered at key compositions during the deintercalation and intercalation processes. The main goal is to determine changes in the anionic and cationic environment of each cation (Li, Ni, Mn and Co) upon cycling.