A theoretical and experimental study of the lithiation of $\eta '$-Cu$_6$Sn$_5$ in a lithium-ion battery

TL;DR

This paper combines theoretical calculations and experimental techniques to investigate how lithium inserts into $ ext{Cu}_6 ext{Sn}_5$ during battery operation, revealing detailed mechanisms and voltage characteristics.

Contribution

It provides a comprehensive analysis of lithiation mechanisms in $ ext{Cu}_6 ext{Sn}_5$ using first principles calculations and in situ X-ray diffraction, which is novel in this context.

Findings

Lithiation mechanism of $ ext{Cu}_6 ext{Sn}_5$ to $ ext{Li}_2 ext{CuSn}$ is elucidated.

Calculated average insertion voltage matches experimental data.

Structural and electronic changes during lithiation are characterized.

Abstract

In this work, the mechanism of Li insertion in $\eta '$-Cu$_6$Sn$_5$ to form Li$_2$CuSn is discussed in detail, based on both theoretical calculations and experimental results. The mechanism is investigated by means of first principles calculations, with the full potential linearized augmented plane wave method, in combination with {\it in situ} X-ray diffraction experiments. The $\eta '$-Cu$_6$Sn$_5$ structure, as well as its lithiated products, have been optimized and the electronic charge density calculated in order to study the change in bond character on lithiation. The average insertion voltage of the $\eta '$-Cu$_6$Sn$_5$-Li$_2$CuSn transformation has been calculated to be 0.378V in good agreement with the experimental value.