Experimental and Computational Analysis of the Solvent-Dependent O2/Li(+)-O2(-) Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium-Oxygen Batteries

David G Kwabi; Vyacheslav S Bryantsev; Thomas P Batcho; Daniil M Itkis; Carl V Thompson; Yang Shao-Horn

doi:10.1002/anie.201509143

Experimental and Computational Analysis of the Solvent-Dependent O2/Li(+)-O2(-) Redox Couple: Standard Potentials, Coupling Strength, and Implications for Lithium-Oxygen Batteries

Angew Chem Int Ed Engl. 2016 Feb 24;55(9):3129-34. doi: 10.1002/anie.201509143. Epub 2016 Jan 28.

Authors

David G Kwabi¹, Vyacheslav S Bryantsev^{2

3}, Thomas P Batcho⁴, Daniil M Itkis⁵, Carl V Thompson⁴, Yang Shao-Horn^{6

7}

Affiliations

¹ Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
² Liox Power Inc, 129 North Hill Ave, Suite 103, Pasadena, CA, 911106, USA.
³ Oak Ridge National Lab, Chemical Sciences Division, 1 Bethel Valley Rd, Oak Ridge, TN, 37831-6119, USA.
⁴ Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
⁵ Department of Chemistry and Materials Science, Moscow State University, Moscow, 119992, Russia.
⁶ Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA. shaohorn@mit.edu.
⁷ Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA. shaohorn@mit.edu.

PMID: 26822277
DOI: 10.1002/anie.201509143

Abstract

Understanding and controlling the kinetics of O2 reduction in the presence of Li(+)-containing aprotic solvents, to either Li(+)-O2(-) by one-electron reduction or Li2 O2 by two-electron reduction, is instrumental to enhance the discharge voltage and capacity of aprotic Li-O2 batteries. Standard potentials of O2 /Li(+)-O2(-) and O2/O2(-) were experimentally measured and computed using a mixed cluster-continuum model of ion solvation. Increasing combined solvation of Li(+) and O2(-) was found to lower the coupling of Li(+)-O2(-) and the difference between O2/Li(+)-O2(-) and O2/O2(-) potentials. The solvation energy of Li(+) trended with donor number (DN), and varied greater than that of O2 (-) ions, which correlated with acceptor number (AN), explaining a previously reported correlation between Li(+)-O2(-) 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.

Keywords: acid-base interactions; lithium; oxygen electrochemistry; solvation; superoxide.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.