CuLi₂Sn and Cu₂LiSn: Characterization by single crystal XRD and structural discussion towards new anode materials for...

The stannides CuLi₂Sn (CSD-427095) and Cu₂LiSn (CSD-427096) were synthesized by induction melting of the pure elements and annealing at 400 °C. The phases were reinvestigated by X-ray powder and single-crystal X-ray diffractometry. Within both crystal structures the ordered CuSn and Cu₂Sn lattices form channels which host Cu and Li atoms at partly mixed occupied positions exhibiting extensive vacancies. For CuLi₂Sn, the space group F-43m. was verified (structure type CuHg₂Ti; a=6.295(2) Å; wR₂(F²)=0.0355 for 78 unique reflections). The 4(c) and 4(d) positions are occupied by Cu atoms and Cu+Li atoms, respectively. For Cu₂LiSn, the space group P6₃/mmc was confirmed (structure type InPt₂Gd; a=4.3022(15) Å, c=7.618(3) Å; wR₂(F²)=0.060 for 199 unique reflections). The Cu and Li atoms exhibit extensive disorder; they are distributed over the partly occupied positions 2(a), 2(b) and 4(e). Both phases seem to be interesting in terms of application of Cu-Sn alloys as anode materials for Li-ion batteries.