Characterisation of lithium-ion battery anodes fabricated via in-situ Cu6Sn5 growth on a copper current collector

Li-ion batteries (LIBs) are favoured in many applications due to their high energy density and good cyclic performance. However, some safety concerns remain with respect to the risk of fires and explosions with LIBs. Carbon-based anode materials in LIBs operate close to the Li metal reduction potential, therefore Li dendrites can grow during voltage fluctuations, causing short circuits which may lead to fires. The Cu6Sn5 anodes has the lithiation potential at about 0.4 V vs Li/Li+ and therefore less prone to Li metal plating. A new manufacturing method involving direct in-situ formation of Cu6Sn5 on a Cu current collector via melt-solid contact is proposed. This method combines the active material production and the anode fabrication into a single process. Lithiation and delithiation mechanisms of the anode produced are studied by in-situ synchrotron X-ray powder diffraction (XRPD) and ex-situ high voltage transmission electron microscope (HV-TEM). The in-situ XRPD study shows a reversible two-step reaction during cycling, and also reveals the differences in the reaction mechanisms at higher charge/discharge rates than those in published data.