Oxygen Reduction Reaction in Highly Concentrated Electrolyte Solutions of Lithium Bis(trifluoromethanesulfonyl)amide/Dimethyl Sulfoxide

TitleOxygen Reduction Reaction in Highly Concentrated Electrolyte Solutions of Lithium Bis(trifluoromethanesulfonyl)amide/Dimethyl Sulfoxide
Publication TypeJournal Article
Year of Publication2017
AuthorsTatara, R, Kwabi, DG, Batcho, TP, Tulodziecki, M, Watanabe, K, Kwon, H-M, Thomas, ML, Ueno, K, Thompson, CV, Dokko, K, Shao-Horn, Y, Watanabete, M
JournalJournal of Physical Chemistry C
Volume121
Issue17
Pagination9162 - 9172
Date Published2017/05/04/
ISBN Number1932-7447
Keywordsaprotic-solvents, dimethyl-sulfoxide, li-air batteries, li-o-2 batteries, o-2 reduction, phase-behavior, physicochemical properties, raman-spectroscopy, superconcentrated electrolytes, temperature ionic liquids
Abstract

The performance of current Liair batteries is greatly limited by critical obstacles such as electrolyte decomposition, high charging overpotentials, and limited cycle life. Thus, much effort is devoted to fundamental studies to understand the mechanisms of discharge/charge processes and overcome the above-mentioned obstacles. In particular, the search for new stable electrolytes is vital for long-lasting and highly cyclable batteries. The highly reactive lithium superoxide intermediate (LiO2) produced during discharge process can react with the electrolyte and produce a variety of byproducts that will shorten battery life span. To study this degradation mechanism, we investigated oxygen reduction reaction (ORR) in highly concentrated electrolyte solutions of lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA])/dimethyl sulfoxide (DMSO). On the basis of rotating ring disk electrode measurements, we showed that LiO2 dissolution can be limited by increasing lithium salt concentration over 2.3 mol dm(-3). Our Raman results suggested that this phenomenon can be related to lack of free DMSO molecules and increasing DMSO-Li+ interactions with higher Li+ concentration. X-ray diffraction measurements for the products of ORR suggested that the side reaction of DMSO with Li2O2 and/or LiO2 could be suppressed by decreasing the solubility of LiO2 in highly concentrated electrolytes.

Short TitleJ. Phys. Chem. C