Abiram Krishnan

(Advisor: Prof. Faisal Alamgir)

will defend a doctoral thesis entitled,

Revealing Anion Contributions in Lithium-Ion Batteries using Inner-Shell X-Ray Spectroscopy

On

Friday, November 6, 2026

 12 pm - 2 pm ET

Callaway Manufacturing Research Building – Auditorium 101

or

Virtually via Microsoft Teams:

Join the meeting now

Meeting ID: 267 067 734 536 012

Passcode: hn9uZ366

Committee:

Prof. Faisal Alamgir – School of Material Science and Engineering (advisor)

Prof. Preet Singh – School of Material Science and Engineering

Prof. Matthew McDowell – School of Material Science and Engineering

Prof. Gleb Yushin – School of Material Science and Engineering

Prof. Yang Shao-Horn - Department of Material Science and Engineering at MIT

Dr. Jagjit Nanda - SLAC National Accelerator Laboratory

Abstract

The chemical state of elements in a lithium-ion battery (LIB) electrode provides valuable insights into the redox reactions occurring at the electrode site during cycling. While previous research has extensively investigated the role of cations in these reactions, the contribution of anions remains relatively unexplored. This is primarily due to the limited tools available to directly study the chemical state of anions. Inner-shell x-ray spectroscopy (ISXS) is well-suited for this purpose due to its element selectivity and ability of X-rays to probe electrode materials during in-situ or operando studies. Among these methods, x-ray absorption spectroscopy (XAS) examines the process of generating electron holes, offering insights into the electronic structure and local atomic arrangements of specific elements. Complementarily, x-ray emission spectroscopy (XES) studies the quenching of generated electron holes, providing sensitivity to chemical state, spin state, and ligand environment, making it an essential companion to XAS.

In this thesis, I will investigate the mechanism behind oxygen activity (redox) and their effects on the physical property of layered LiCoO2 (LCO), LiNixMnyCozO2 (NMCs, x + y + z = 1),  and polyanion-based LiFePO4 (LFP) cathode material for LIBs. First, the onset of oxygen reactions in LCO and NMC cathodes is identified using a combination of several ISXS methods, followed by an investigation into the resulting changes in their structure and physical properties. Next, the formation of metastable phase during the charge process of LFP is qualitatively studied using linear combination analysis of iron K-edge XAS. The role of anions, specifically phosphorus and oxygen, in LFP is then investigated during charging using phosphorus K emissions and oxygen K-edge absorption, respectively. Finally, Kβ XES is explored as a probe for monitoring the chemical state of transition metals and their covalency with oxygen during LIB cycling, with its results benchmarked against those obtained using XAS.