 These copper atoms are displaced to the grain boundaries when charged to form Li2CuSn.With retention of most of the metal-metal bonding down to 0.5V, Cu6Sn5 has become an attractive potential anode material due to its high theoretical specific capacity, resistance against Li metal plating especially when compared to carbon-based anodes, and ambient stability.In this and related NiAs-type materials, lithium intercalation occurs through an insertion process to fill the two crystallographic vacancies in the lattice, at the same time as the 0.2 extra coppers are displaced to the grain boundaries.