Simulating NEXAFS spectra for Li k-edge in Li-ion Battery materials
| Title: |
Simulating NEXAFS spectra for Li k-edge in Li-ion Battery materials |
| DNr: |
NAISS 2024/22-787 |
| Project Type: |
NAISS Small Compute |
| Principal Investigator: |
Peter Broqvist <peter.broqvist@kemi.uu.se> |
| Affiliation: |
Uppsala universitet |
| Duration: |
2024-05-30 – 2025-06-01 |
| Classification: |
10407 |
| Keywords: |
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Abstract
The Si-graphite composite is an emerging anode material for Li-ion batteries owing to its high theoretical capacity. However, various Li compounds, as well as electrolyte decomposition products, create deposits on the anode material which induce a structure change of the anode material, leading to degrading performance. It is therefore of vital importance to find and quantify the various Li-products in the anode during lithation/delithiation, as well as to follow the structural (and chemical) evolution of the anode material to understand how these affect battery performance.
Near edge X-ray adsorption fine structure gives the opportunity to study the local structure of the materials by exciting the electron to unoccupied state or above fermi level to create a core hole. The core hole decay in the form of ejecting an auger electron or emission of the fluorescence can be detected, giving the electronic state and local structure information, which are shown in the spectrum as adsorption edge. Li-K edge was comparably less studied due to its low adsorption energy at 55 eV, which is often below the lower energy limit of most synchrotron radiation source. Given the complexity of the experimental conditions, simulations will provide an additional route for aiding in the interpreting of the experimental data.
In this study, the electronic structure of a Si anode is being investigated. The experimental NEXAFS spectra are compared with simulated spectra from VASP calculation. The Li components in the Si anode at different lithiation states and their interactions Si will be studied. With this combined experimental and theoretical study, we aim to obtain quantitative information regarding lithiation products and oxidation states in the Si anode.
