Extracting the Redox Orbitals in Li Battery Materials with High-Resolution X-Ray Compton Scattering Spectroscopy

TL;DR

This paper introduces a high-resolution x-ray Compton scattering technique to directly probe redox orbitals in lithium battery materials, revealing oxygen 2p orbitals and manganese 3d state delocalization during operation.

Contribution

The study develops and applies a novel spectroscopic method to identify and analyze redox orbitals in battery cathodes, providing new insights into their electronic structure during charge cycles.

Findings

Oxygen 2p orbitals are primarily involved in lithium insertion/extraction.

Manganese 3d states become spatially delocalized during battery operation.

The method offers a direct probe of redox processes in battery materials.

Abstract

We present an incisive spectroscopic technique for directly probing redox orbitals based on bulk electron momentum density measurements via high-resolution x-ray Compton scattering. Application of our method to spinel LixMn2O4, a lithium ion battery cathode material, is discussed. The orbital involved in the lithium insertion and extraction process is shown to mainly be the oxygen 2p orbital. Moreover, the manganese 3d states are shown to experience spatial delocalization involving 0.16 electrons per Mn site during the battery operation. Our analysis provides a clear understanding of the fundamental redox process involved in the working of a lithium ion battery.