Atomistic Mechanisms of Mg Insertion Reactions in Group XIV Anodes for Mg-Ion Batteries

Mingchao Wang, Jodie A. Yuwono, Vallabh Vasudevan, Nick Birbilis, Nikhil V. Medhekar

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)

Abstract

Magnesium (Mg) metal has been widely explored as an anode material for Mg-ion batteries (MIBs) owing to its large specific capacity and dendrite-free operation. However, critical challenges, such as the formation of passivation layers during battery operation and anode-electrolyte-cathode incompatibilities, limit the practical application of Mg-metal anodes for MIBs. Motivated by the promise of group XIV elements (namely, Si, Ge, and Sn) as anodes for lithium- and sodium-ion batteries, here, we conduct systematic first-principles calculations to explore the thermodynamics and kinetics of group XIV anodes for MIBs and to identify the atomistic mechanisms of the electrochemical insertion reactions of Mg ions. We confirm the formation of amorphous MgxX phases (where X = Si, Ge, and Sn) in anodes via the breaking of the stronger X-X bonding network replaced by weaker Mg-X bonding. Mg ions have higher diffusivities in Ge and Sn anodes than in Si, resulting from weaker Ge-Ge and Sn-Sn bonding networks. In addition, we identify thermodynamic instabilities of MgxX that require a small overpotential to avoid aggregation (plating) of Mg at anode/electrolyte interfaces. Such comprehensive first-principles calculations demonstrate that amorphous Ge and crystalline Sn can be potentially effective anodes for practical applications in MIBs.

Original languageEnglish
Pages (from-to)774-783
Number of pages10
JournalACS Applied Materials and Interfaces
Volume11
Issue number1
DOIs
Publication statusPublished - 9 Jan 2019

Keywords

  • anode materials
  • electrode potential
  • first-principles calculations
  • group XIV elements
  • ionic diffusivity
  • Mg-ion batteries
  • overpotential
  • phase transition

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