Experimental and Computational Analysis of the Solvent-Dependent O-2/Li+-O-2(-) Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium-Oxygen Batteries

TitleExperimental and Computational Analysis of the Solvent-Dependent O-2/Li+-O-2(-) Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium-Oxygen Batteries
Publication TypeJournal Article
Year of Publication2016
AuthorsKwabi, DG, Bryantsev, VS, Batcho, TP, Itkis, DM, Thompson, CV, Shao-Horn, Y
JournalAngewandte Chemie-International Edition
Volume55
Issue9
Pagination3129 - 3134
Date Published2016/02/24/
ISBN Number1433-7851
Keywordsacid-base interactions, aprotic-solvents, dimethyl-sulfoxide, electrochemical reduction, electrolyte, li-air batteries, lithium, mechanism, oxygen electrochemistry, rechargeable li-o-2 batteries, solvate ionic liquids, solvation, stability, superoxide, superoxide anion
Abstract

Understanding and controlling the kinetics of O-2 reduction in the presence of Li+-containing aprotic solvents, to either Li+-O-2(-) by one-electron reduction or Li2O2 by two-electron reduction, is instrumental to enhance the discharge voltage and capacity of aprotic Li-O-2 batteries. Standard potentials of O-2/Li+-O-2(-) and O-2/O-2(-) were experimentally measured and computed using a mixed cluster-continuum model of ion solvation. Increasing combined solvation of Li+ and O-2(-) was found to lower the coupling of Li+-O-2(-) and the difference between O-2/Li+-O-2(-) and O-2/O-2(-) potentials. The solvation energy of Li+ trended with donor number (DN), and varied greater than that of O-2(-) ions, which correlated with acceptor number (AN), explaining a previously reported correlation between Li+-O-2(-) solubility and DN. These results highlight the importance of the interplay between ion-solvent and ion-ion interactions for manipulating the energetics of intermediate species produced in aprotic metal-oxygen batteries.

Short TitleAngew. Chem.-Int. Edit.