We have elaborated a new nano-crystallized high capacity Li-Mn-O cathode material, exhibiting record reversible capacities larger than 355 mAh/g and good cyclabilities. RT neutron powder diffraction at D1B, synchrotron x-ray diffraction and Pair Distribution Function (PDF) analysis at D2AM (ESRF)and neutron PDF at D4c (ILL) showed that this material has an MnO rock-salt type structure albeit highly disordered due to the Li/Mn mixing in the cation site and the presence of ~1/6 of oxygen vacancies. The evolution of the magnetic ordering in the pristine Li4Mn2O5 material was previously studied at D1B demonstrating the presence of a disordered magnetic phase in the form of the appearance of magnetic diffuse scattering at the corresponding Mn-Mn distances. Therefore, we propose to measure the magnetic-PDF of Li4Mn2O5 at GEM, in order to determine the evolution of the magnetic configuration.