How Bulk Sensitive is Hard X-ray Photoelectron Spectroscopy: Accounting for the Cathode-Electrolyte Interface when Addressing Oxygen Redox

Zachary W. Lebens-Higgins, Hyeseung Chung, Mateusz J. Zuba, Jatinkumar Rana, Yixuan Li, Nicholas V. Faenza, Nathalie Pereira, Bryan D. McCloskey, Fanny Rodolakis, Wanli Yang, M. Stanley Whittingham, Glenn G. Amatucci, Ying Shirley Meng, Tien Lin Lee, Louis F.J. Piper

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Sensitivity to the "bulk" oxygen core orbital makes hard X-ray photoelectron spectroscopy (HAXPES) an appealing technique for studying oxygen redox candidates. Various studies have reported an additional O 1s peak (530-531 eV) at high voltages, which has been considered a direct signature of the bulk oxygen redox process. Here, we find the emergence of a 530.4 eV O 1s HAXPES peak for three model cathodes - Li2MnO3, Li-rich NMC, and NMC 442 - that shows no clear link to oxygen redox. Instead, the 530.4 eV peak for these three systems is attributed to transition metal reduction and electrolyte decomposition in the near-surface region. Claims of oxygen redox relying on photoelectron spectroscopy must explicitly account for the surface sensitivity of this technique and the extent of the cathode degradation layer.

Original languageEnglish (US)
Pages (from-to)2106-2112
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume11
Issue number6
DOIs
StatePublished - Mar 19 2020

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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