Anode and cathode materials, graphite and LiCoO2, are studied by neutron diffraction under "in operando" conditions in commercial batteries (ICR 18650-type). The evolution of their crystal structure versus state of charge (SOC) and fatigue (state of health, SOH) has been analyzed using the Rietveld refinement technique. Neutron radiography data and their tomography reconstruction revealed the local neutron absorption density, which reflects mainly the Li-distribution density, but also further details of the battery design. Changes in the neutron absorption contrast have also been evaluated in dependence on SOC and SOH. (C) 2011 Elsevier B.V. All rights reserved.