Orbital-free density functional theory study of crystalline Li-Si alloys

Junchao Xia, Emily A. Carter

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Li-Si interactions are of great interest currently due to the potential use of silicon anodes in Li-ion batteries. As a first step toward eventual nanoscale characterization of lithiation of silicon, here we study the crystalline Li-Si alloys LiSi, Li12Si7, Li 7Si3, Li13Si4, Li 15Si4, and Li22Si5 using orbital-free density functional theory (OFDFT). The recently proposed Wang-Govind-Carter decomposition (WGCD) and Huang-Carter (HC) kinetic energy density functionals (KEDFs) are used to evaluate the electron kinetic energy. Both KEDFs predict accurate cell lattice vectors, equilibrium volumes, bulk moduli, and ground-state densities when compared to Kohn-Sham density functional theory (KSDFT) benchmarks. Elastic constants and alloy formation energies calculated with the WGCD KEDF also agree reasonably well with KSDFT. Finally, Li atom adsorption energies on the Si(100) - 2 × 1 surface are calculated as a simple initial test of the Li-Si mixing process during lithiation of silicon. The OFDFT adsorption energies again are fairly close to KSDFT values. The results in this work demonstrate the accuracy of the WGCD and HC KEDFs for materials with mixed covalent-metallic character and their considerable transferability under different chemical environments. Because of its quasilinear scaling, coupled with the level of accuracy shown here, OFDFT appears quite promising for large-scale simulation of such materials phenomena.

Original languageEnglish (US)
Pages (from-to)62-72
Number of pages11
JournalJournal of Power Sources
Volume254
DOIs
StatePublished - May 15 2014

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering

Keywords

  • Elastic constant
  • Kinetic energy density functional
  • Li-Si alloy
  • Li-ion battery
  • Orbital-free density functional theory

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