GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

           MASTER OF SCIENCE  

on Wednesday, April 5, 2023

12:00 PM

the 

MASTER'S THESIS DEFENSE

will be held for 

Abiram Krishnan 

via

Teams Meeting

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Meeting ID: 239 585 605 62
Passcode: mUove5

"Operando Characterization of Lithium-Ion Batteries Using Lab-Scale X-ray Emission/Absorption Spectroscopy"

Committee Members:

Dr. Faisal Alamgir, Advisor, MSE

Dr. Gleb Yushin, MSE

Dr. Mohan Srinivasarao, MSE

Dr. Anju Toor, MSE

Abstract:

Tracking changes in the electronic structure of target elements is crucial to investigate the nature of redox reactions occurring in battery electrodes. Core-hole characterization techniques such as X-ray Emission Spectroscopy (XES) and X-ray Absorption Fine Structure (XAFS) perform this role well through the generation/quenching of core holes in the sample. Laboratory-based core hole x-ray spectroscopy techniques have recently gained popularity as they are more accessible and provide energy resolution close to that of a synchrotron source.

In this study, the use of lab-scale XES along with XAFS to investigate the change in the electronic structure around transition elements present in cathode/anode material for lithium-ion batteries is explored as a function of lithium removal. The spin sensitivity of Kβ1,3 XES allows the user to explore changes in magnetic properties during the charging/discharging of electrode material. This is employed to study the change in the 3d shell of transition metals for reference compounds followed by ex-situ and operando electrodes for lithium-ion batteries. Additionally, the spin sensitivity of Kα and Kβ1,3 XES is utilized to study the magnetic behavior of LCO cathodes in the first 10% of lithium removal along with K-edge XAFS for oxygen and cobalt to explore spin transitions.