This proposal is part of a lithium ion battery research project for finding new anode materials. The redox couples Ti4+/Ti3+ and Nb5+/Nb4+ in titanium and niobium oxides show a favourable electrochemical potential, so that such materials are good candidates for lithium intercalation/deintercalation in an electrochemical cell. TiNb2O7 was recently shown to have very good performances in this respect, with the ability to intercalate up to four Li atoms per formula unit. We performed chemical lithiation of TiNb2O7 by butyl-lithium, obtaining LixTiNb2O7 products similar to those formed electrochemically. We propose to collect neutron diffraction data on these compounds by the powder diffractometer INES. The key objective is to determine the location of lithium atoms in the structure, so as to understand the Li intercalation process in the battery. Four days of measurement time are requested.