Unfolding tin-cobalt interactions in oxide-based composite electrodes for Li-ion batteries by Mössbauer spectroscopy.

With a view to the development of new composite electrodes for lithium-ion batteries with electroactive tin and cobalt, Co-doped tin dioxide samples are studied. The role played by oxygen and cobalt atoms in the electrochemical behavior of tin-based electrodes for Li-ion batteries is examined by the powerful and selective (119)Sn Mössbauer spectroscopy. For the discharged electrodes, the oxygen atoms in the lithia matrix tend to destabilize the Sn(0) atoms. In contrast, the presence of cobalt atoms helps to form a matrix that stabilizes the reduced tin atoms. Cobalt-tin interactions in electrochemical reduced Co(x)Sn(1-x)O(2) electrodes are deduced from the electrochemical and Mössbauer results.