Single Crystal Growth and Thermodynamic Stability of Li17Si4

Single crystals of Li17Si4 were synthesized from melts LixSi100–x (x > 85) at various temperatures and isolated by isothermal centrifugation. Li17Si4 crystallizes in the space group F4̅3m (a = 18.7259(1) Å, Z = 20). The highly air and moisture sensitive compound is isotypic with Li17Sn4. Li17Si4 represents a new compound and thus the lithium-richest phase in the binary system Li–Si superseding known Li21Si5 (Li16.8Si4). As previously shown Li22Si5 (Li17.6Si4) has been determined incorrectly. The findings are supported by theoretical calculations of the electronic structure, total energies, and structural optimizations using first-principles methods. Results from melt equilibration experiments and differential scanning calorimetry investigations suggest that Li17Si4 decomposes peritectically at 481 ± 2 °C to “Li4Si” and melt. In addition a detailed investigation of the Li–Si phase system at the Li-rich side by thermal analysis using differential scanning calorimetry is given.