Issue 45, 2023

The decisive role of electrostatic interactions in transport mode and phase segregation of lithium ions in LiFePO4

Abstract

Understanding the mechanism of slow lithium ion (Li+) transport kinetics in LiFePO4 is not only practically important for high power density batteries but also fundamentally significant as a prototypical ion-coupled electron transfer process. Substantial evidence has shown that the slow ion transport kinetics originates from the coupled transfer between electrons and ions and the phase segregation of Li+. Combining a model Hamiltonian analysis and DFT calculations, we reveal that electrostatic interactions play a decisive role in coupled charge transfer and Li+ segregation. The obtained potential energy surfaces prove that ion–electron coupled transfer is the optimal reaction pathway due to electrostatic attractions between Li+ and e (Fe2+), while prohibitively large energy barriers are required for separate electron tunneling or ion hopping to overcome the electrostatic energy between the Li+–e (Fe2+) pair. The model reveals that Li+–Li+ repulsive interaction in the [010] transport channels together with Li+–e (Fe2+)–Li+ attractive interaction along the [100] direction cause the phase segregation of Li+. It explains why the thermodynamically stable phase interface between Li-rich and Li-poor phases in LiFePO4 is perpendicular to [010] channels.

Graphical abstract: The decisive role of electrostatic interactions in transport mode and phase segregation of lithium ions in LiFePO4

Supplementary files

Article information

Article type
Edge Article
Submitted
16 Aug. 2023
Accepted
24 Okt. 2023
First published
07 Nov. 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 13042-13049

The decisive role of electrostatic interactions in transport mode and phase segregation of lithium ions in LiFePO4

X. Wang, J. Huang, Y. Liu and S. Chen, Chem. Sci., 2023, 14, 13042 DOI: 10.1039/D3SC04297A

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, 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 commercial 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