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Water effect on the conductivity behavior of NH4PO3-based electrolytes for intermediate temperature fuel cells |
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| Authors: | Xilin Chen Changrong Xia Ulrich Stimming |
| Affiliation: | aLaboratory for Renewable Clean Energy, Department of Materials Science and Engineering, University of Science and Technology of China, Hefei, 230026 Anhui, China bDepartment of Physics E19, Technical University of Munich, James-Franck-Strasse 1, 85748 Garching, Germany |
| Abstract: | The electrical conductivity at intermediate temperature of 150–250 °C and the activation energy for conductivity of composite proton conductors, 2NH4PO3–(NH4)2Mn(PO3)4 and 2NH4PO3–(NH4)2SiP4O13, were investigated as a function of water vapor pressure, PH2O. The activation energy decreased linearly with the natural logarithm of PH2O, indicating that water is chemically adsorbed to the electrolytes. The decrease in activation energy is possibly caused by formation of hydrogen bonds between the adsorbed water and the electrolytes. In addition, the pre-exponential factor of Arrhenius equation, σ0, increased with PH2O. This suggests that the adsorbed water may generate additional mobile protons for the composite electrolyte. Therefore, the enhancement in the electrical conductivity of a NH4PO3-based electrolyte in a water-vapor rich atmosphere originates possibly from the decrease in activation energy as well as the increase in mobile proton concentration. |
| Keywords: | Intermediate temperature fuel cell Proton conductor Water effect NH4PO3-based electrolyte Activation energy |
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