In situ ambient pressure X-ray photoelectron spectroscopy studies of lithium-oxygen redox reactions

Yi Chun Lu, Ethan J. Crumlin, Gabriel M. Veith, Jonathon R. Harding, Eva Mutoro, Loïc Baggetto, Nancy J. Dudney, Zhi Liu, Yang Shao-Horn

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195 Scopus citations

Abstract

The lack of fundamental understanding of the oxygen reduction and oxygen evolution in nonaqueous electrolytes significantly hinders the development of rechargeable lithium-air batteries. Here we employ a solid-state Li 4+x Ti 5O 12/LiPON/Li xV 2O 5 cell and examine in situ the chemistry of Li-O 2 reaction products on Li xV 2O 5 as a function of applied voltage under ultra high vacuum (UHV) and at 500 mtorr of oxygen pressure using ambient pressure X-ray photoelectron spectroscopy (APXPS). Under UHV, lithium intercalated into Li xV 2O 5 while molecular oxygen was reduced to form lithium peroxide on Li XV 2O 5 in the presence of oxygen upon discharge. Interestingly, the oxidation of Li 2O 2 began at much lower overpotentials (∼240 mV) than the charge overpotentials of conventional Li-O 2 cells with aprotic electrolytes (∼1000 mV). Our study provides the first evidence of reversible lithium peroxide formation and decomposition in situ on an oxide surface using a solid-state cell, and new insights into the reaction mechanism of Li-O 2 chemistry.

Original languageEnglish
Article number715
JournalScientific Reports
Volume2
DOIs
StatePublished - 2012

Funding

This work was supported in part by the MRSEC Program of the National Science Foundation under award number DMR-0819762, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies of the U. S. Department of Energy under contract no. DE-AC03-76SF00098 with the Lawrence Berkeley National Laboratory, and the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy. We thank Dr. Azzam Mansour (Naval Surface Warfare Center, Carderock Division) for helping with ex situ XPS measurements on reference materials and Rui Chang and Baohua Mao for assisting in situ XPS measurements. The ALS is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231. Research conducted at ORNL was supported by the U.S. Department of Energy’s Office of Basic Energy Science, Division of Materials Sciences and Engineering, under contract with UT-Battelle, LLC.

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