Exploration of new materials and chemistry has always been a hotspot in battery research. The methodology to study essential materials & interface properties, mechanisms of chemical & physical processes, as well as the materials manufacturing & processing involved in battery fabrication plays a very important role in improving battery performance. The Liu Lab group is currently investing in developing advanced methods for both liquid and solid state batteries and enabling methodology to study the evolution of organic species in solid state interphase (SEI) composition by utilizing our freshly minted gradient wash method integrated with IR and MALDI techniques.
Gradient Solvent Wash for Electrode Surface Study
Gradient polarity solvent wash technique involving the use of solvents with gradually increased polarities is employed to sequentially remove different SEI components from electrode surfaces. Fourier transform infrared (FTIR) spectroscopy is utilized to characterize the SEI composition. The impacts of electrolyte additives and discharge rates over SEI formation are illustrated.
This study presents a new concept of rationally controlled solvent wash technique for electrode surface analysis that can selectively remove targeted components. The findings in this study provide experimental support for the slow charge formation processes commonly employed for LIBs in industry.
Fang, C.; Liu, Z. M.; Lau, J.; Elzouka, M.; Zhang, G. Z.; Khomein, P.; Lubner, S.; Ross, P. N.; Liu, G., Gradient Polarity Solvent Wash for Separation and Analysis of Electrolyte Decomposition Products on Electrode Surfaces. J. Electrochem. Soc. 2020, 167 (2), 7.
On-Electrode Chromatography and MALDI
The on-electrode chromatography technique is employed for fractionating different molecular species on electrode surfaces, which proves crucial for identification of organic and polymeric species in solid electrolyte interphase (SEI) by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry.
Precise structural assignment has been provided for the large molecule components in SEIs. The introduced methods exemplify a highly practical and readily adoptable strategy for characterization of the organic and polymeric decomposition products in SEIs.