Electrochemical potential window of battery electrolytes: the HOMO–LUMO misconception

By P. Peljo, H. Girault. 2018

302 citations recorded by the source corpus.

A widespread misconception in the lithium ion battery literature is the equality of the energy difference of HOMO and LUMO of the solvent with the electrochemical stability window. HOMO and LUMO are concepts derived from approximated electronic structure theory while investigating electronic properties of isolated molecules, and their energy levels do not indicate species participating in redox reactions. On the other hand, redox potentials are directly related to the Gibbs free energy difference of the reactants and products. While redox potentials in some cases show strong correlation with HOMO energies, the offset can be of several eVs. Presence of electrolytes and other molecules can also significantly affect the redox potentials of the solvent leading to offset as high as 4 eV from the HOMO energies. In this opinion we provide a correct thermodynamic representation for the electrochemical stability of the electrolyte, based on redox potentials and Fermi level of the electron in solution, and demonstrate that the use of terms HOMO and LUMO should be avoided when talking about the electrochemical stability of electrolytes. Instead, it is more correct to speak of potential of electrolyte reduction at negative potentials, and of potential of solvent oxidation at positive potentials.

Subfields: Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/c81884351304a6ad2f65c572a3f833f09472e2cb

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In Electrical and Electronic Engineering

1. Qiang Bai
2. Adelaide M. Nolan
3. Xingfeng He
4. Yizhou Zhu
5. Yifei Mo
6. Gerbrand Ceder
7. W. Zeier
8. J. Janek

Citations in the corpus

• Computation-Accelerated Design of Materials and Interfaces for All-Solid-State Lithium-Ion Batteries (2018, background): “The electrochemical window is the gap between the reduction and oxidation potentials based on the Gibbs free energy difference of the reactants and products, and is different from the band gap or the gap between the levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular ”