In-operando photoelectron spectroscopy for batteries: Set-up using pristine thin film cathode and first results on NaxCoO2

Conrad Guhl; Philipp Kehne; Qianli Ma; Frank Tietz; Lambert Alff; Philipp Komissinskiy; Wolfram Jaegermann; René Hausbrand

doi:10.1063/1.5022616

In-operando photoelectron spectroscopy for batteries: Set-up using pristine thin film cathode and first results on Na_xCoO₂

Rev Sci Instrum. 2018 Jul;89(7):073104. doi: 10.1063/1.5022616.

Authors

Conrad Guhl¹, Philipp Kehne², Qianli Ma³, Frank Tietz³, Lambert Alff², Philipp Komissinskiy², Wolfram Jaegermann¹, René Hausbrand¹

Affiliations

¹ Institute of Materials Science, Surface Science, TU-Darmstadt, Otto-Berndt-Str. 3, 64287 Darmstadt, Germany.
² Institute of Materials Science, Advanced Thin Film Technology, TU-Darmstadt, Alarich-Weiss-Str. 2, 64287 Darmstadt, Germany.
³ Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), 52425 Jülich, Germany.

PMID: 30068114
DOI: 10.1063/1.5022616

Abstract

A model all-solid-state battery cell with a thin film Na_xCoO₂ cathode was assembled under ultra-high vacuum conditions and cycled inside the vacuum chamber, using a dedicated sample holder. We present in-operando x-ray photoelectron spectroscopy measurements of a Na_xCoO₂ cathode at different charging states. During battery operation, the change in sodium content, the change in cobalt oxidation state, and the evolution of the O1s and VB emissions could be monitored. Comparison with a conventional post-mortem analysis technique showed that the new measurement technique produces comparable results regarding the oxidation state of the transition metal, but sodium and oxygen results show differences due to cathode/electrolyte interfacial reactions for conventional analysis. By using surface layer-free samples in the presented techniques, we could circumvent such reactions and obtain reliable spectra for the pure bulk-like active cathode material.