Thermodynamic, thermomechanical, and electrochemical evaluation of CsHSO4

Tetsuya Uda, Dane A. Boysen, Sossina M. Haile*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


A thermodynamic analysis of CsHSO4 in oxygen and hydrogen atmospheres has been carried out. In an oxygen atmosphere, the phase relationship for the dehydration of CsHSO4 as a function of H 2O partial pressure was established. It is concluded that CsHSO 4 is stable in a humidified oxygen atmosphere, pH2O = 0.03 atm, up to 170°C. However, in hydrogen atmospheres, it was affirmed that CsHSO4 is reduced to H2S and Cs2SO4. Electromotive force (EMF) measurements in a humidified oxygen concentration cell, pH2O = 0.03 atm confirmed the ionic nature of the charge-carrying species. Upon thermal cycling, the voltage obtained from the high temperature phase (T = 149°C) remained unchanged for over 85 h of measurement. The volume change upon transformation to the superprotonic phase, as directly measured by high temperature X-ray powder diffraction, is +0.54%. These results demonstrate not only the stability of CsHSO4 in oxygen but also the viability of solid acid-based electrochemical devices that would likely be subjected to thermal cycling during operation.

Original languageEnglish (US)
Pages (from-to)127-133
Number of pages7
JournalSolid State Ionics
Issue number1-2
StatePublished - Jan 14 2005


  • Fuel cell
  • Proton conductor
  • Solid acid
  • Superprotonic transition
  • Thermodynamics

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Fingerprint Dive into the research topics of 'Thermodynamic, thermomechanical, and electrochemical evaluation of CsHSO<sub>4</sub>'. Together they form a unique fingerprint.

Cite this