Thermodynamically stable lithium silicides and germanides from density functional theory calculations

Andrew J. Morris, C. P. Grey, Chris J. Pickard

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52 Citations (Scopus)


High-throughput density functional theory (DFT) calculations have been performed on the Li-Si and Li-Ge systems. Lithiated Si and Ge, including their metastable phases, play an important technological role as Li-ion battery (LIB) anodes. The calculations comprise structural optimizations on crystal structures obtained by swapping atomic species to Li-Si and Li-Ge from the
X − Y structures in the International Crystal Structure Database, where
X = {Li, Na, K, Rb, Cs} and Y = {Si, Ge, Sn, Pb}. To complement this at various Li-Si and Li-Ge stoichiometries, ab initio random structure searching (AIRSS) was also performed. Between the ground-state stoichiometries, including the recently found Li17Si4 phase, the average voltages were calculated, indicating that germanium may be a safer alternative to silicon anodes in LIB due to its higher lithium insertion voltage. Calculations predict high-density Li1 Si1 and
Li1 Ge1 P4/mmm layered phases which become the ground states above 2.5 and 5 GPa, respectively, and reveal silicon and germanium's propensity to form dumbbells in the Lix Si, x = 2.33–3.25, stoichiometry range. DFT predicts the stability of the Li11 Ge6 Cmmm, Li12 Ge7 Pnma, and Li7 Ge3 P3212 phases and several new Li-Ge compounds, with stoichiometries Li5 Ge2, Li13 Ge5,
Li8 Ge3 and Li13 Ge4.
Original languageEnglish
Article number054111
Number of pages9
JournalPhysical Review B
Issue number5
Publication statusPublished - 21 Aug 2014


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