Open AccessOperando Measurements of Electrolyte Li-ion Concentration during fast charging with FTIR/ATR
Author(s) -
Lydia Meyer,
David J. Curran,
Ryan Brow,
Shriram Santhanagopalan,
Jason M. Porter
Publication year - 2021
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac1d7a
Subject(s) - electrolyte , ethylene carbonate , lithium (medication) , chemistry , fourier transform infrared spectroscopy , anode , ion , analytical chemistry (journal) , attenuated total reflection , graphite , lithium ion battery , inorganic chemistry , absorption (acoustics) , battery (electricity) , infrared spectroscopy , materials science , chemical engineering , chromatography , organic chemistry , electrode , composite material , medicine , power (physics) , physics , quantum mechanics , engineering , endocrinology
The ability to charge a Li-ion battery at high charging rates is critical for electric vehicle adoption; however, further study of ion transport is required to develop electrolytes suitable for fast charge. Fourier transform infrared spectroscopy (FTIR) used with attenuated total reflection (ATR) enables operando measurements of liquid electrolytes. This research focused on solvation shifting of solvent infrared absorption bands in the presence of lithium ions. Lithium-shifted infrared absorption bands and non-shifted bands of ethyl methyl carbonate (EMC) and ethylene carbonate (EC) were compared to infer ion concentration changes during cycling. Lithium concentrations were calibrated using EC/EMC/LiPF 6 electrolytes with known lithium concentrations. A Li-ion half-cell with a graphite anode and EC/EMC/LiPF 6 electrolyte was observed with FTIR/ATR. The results showed that the magnitude of lithium concentration changes increased with increasing C-rate. During a galvanostatic intermittent titration technique (GITT) test, changes in lithium concentration could be observed. During intercalation, a lithium depletion occurred when a negative current was applied, and a lithium surplus occurred during deintercalation when a positive current was applied. The capability of observing lithium concentration has significant implications for the utility of operando studies and the potential to link lithium movement to battery performance.