Issue 4, 2019

Energy landscape of the charge transfer reaction at the complex Li/SEI/electrolyte interface

Abstract

The charge transfer reaction is the fundamental reaction for rechargeable batteries. The energy landscape of this reaction depicts the equilibrium and kinetics of the electrochemical process. Typically, a Li-metal electrode is always covered by a thin layer of solid electrolyte interphase (SEI), forming a complex Li/SEI/electrolyte interface. In this paper, a new modeling framework was developed to predict the energy landscape of the lithiation/delithiation charge transfer reaction at a Li/Li2CO3/EC-electrolyte interface, with combined density functional theory (DFT) and tight-binding (DFTB) calculations. It was found that Li+ ions are much more energetically favorable to be dissolved in the electrolyte on a zero-charged Li-metal electrode, indicating that the SEI is a necessary kinetic barrier to prevent complete solvation of Li-metal into the electrolyte. During delithiation, Li+ ions would be stripped from the surface non-uniformly and form a large void on the Li-metal surface. During lithiation, it was demonstrated that the annihilation of Li+ ions and electrons occurs at the Li/SEI interface, for an idealized defect free SEI. Furthermore, at the experimentally defined zero voltage for Li+/Li0, the Li-metal surface is negatively charged (−0.62 ± 0.12 e nm−2) to maintain the electrochemical equilibrium. The electric field created by the negatively charged surface can reorient the electrolyte into an ordered structure, lower the Li+ ion desolvation energy barrier, and help the Li+ ion transport through the SEI. The charge transfer coefficient, α, in the Butler–Volmer equation was directly computed to be ∼0.22 from the simulated energy landscape, consistent with the experimental measurements. Thus, this model enables a bottom-up multiscale modeling approach for ion-transfer electrochemical reactions.

Graphical abstract: Energy landscape of the charge transfer reaction at the complex Li/SEI/electrolyte interface

Supplementary files

Article information

Article type
Paper
Submitted
10 dec 2018
Accepted
05 mar 2019
First published
06 mar 2019

Energy Environ. Sci., 2019,12, 1286-1295

Author version available

Energy landscape of the charge transfer reaction at the complex Li/SEI/electrolyte interface

Y. Li and Y. Qi, Energy Environ. Sci., 2019, 12, 1286 DOI: 10.1039/C8EE03586E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements