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

  • Author(s): Lu, YC
  • Crumlin, EJ
  • Veith, GM
  • Harding, JR
  • Mutoro, E
  • Baggetto, L
  • Dudney, NJ
  • Liu, Z
  • Shao-Horn, Y
  • et al.

Published Web Location

https://doi.org/10.1038/srep00715
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 Li4+xTi5O12/LiPON/LixV2O5cell and examine in situ the chemistry of Li-O2reaction products on LixV2O5as 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 LixV2O5while molecular oxygen was reduced to form lithium peroxide on LiXV2O5in the presence of oxygen upon discharge. Interestingly, the oxidation of Li2O2began at much lower overpotentials (∼240 mV) than the charge overpotentials of conventional Li-O2cells 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-O2chemistry.

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