Abstract
The unique properties of solid acid electrolytes, in particular CsH2PO4, are in many ways ideal for fuel cell operation. However, the technology is constrained by high cathode overpotentials. Here a simplified cathode geometry is employed to obtain the fundamental electrochemical parameters (exchange current density and charge transfer coefficient) describing the oxygen reduction reaction (ORR) at the CsH2PO4-Pt-gas interface. The parameters are incorporated into a 1D model of the voltage–current characteristics of realistic SAFC cathodes, which reproduced the measured polarization behavior of such cathodes without recourse to fitting adjustable parameters. Following this validation, the model is utilized to evaluate the impact of changes to cathode properties, microstructure, and operating conditions. Of these, the charge transfer coefficient, measured to have a value of ≈0.6 for ORR on Pt in the SAFC cathode environment, is found to have the greatest impact on power output. Nevertheless, even without material modifications, a combination of microstructural and operational modifications are identified with projected performance metrics meeting Department of Energy targets (0.8 V at 300 mA cm−2, and peak power density of 1 W cm−2), albeit at high Pt loadings. However, the analysis indicates that truly meaningful advances will likely necessitate the discovery of alternative ORR catalysts.
| Original language | English (US) |
|---|---|
| Article number | 2400119 |
| Journal | Advanced Materials Interfaces |
| Volume | 11 |
| Issue number | 20 |
| DOIs | |
| State | Published - Jul 16 2024 |
Funding
This work was supported as part of the Hydrogen in Information and Energy Sciences (HEISs) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE\u2010SC0023450. L.S.W. acknowledges a graduate fellowship through the US National Science Foundation. The authors thank Dr. Calum Chisholm and Mandy Abbott for assistance with SAFC fabrication, Dr. Neil Schweitzer for assistance with BET measurements, and Dr. Dalton Cox for valuable discussions in the model development. Access to several excellent user facilities at Northwestern University and the support of the associated technical staff is also gratefully acknowledged: the Jerome B. Cohen X\u2010ray Diffraction Facility, which receives support from the SHyNE Resource (NSF ECCS\u20102025633) and from Northwestern's MRSEC program (NSF DMR\u20102308691); the EPIC facility at the NUANCE center, which receives support from the International Institute of Nanoscience, as well as from the SHyNE Resource and Northwestern's MRSEC program; and the Reactor Engineering and Catalyst Testing (REACT) facility of the Trienens Institute for Sustainability and Energy. Selected experiments were performed in the Flex Lab of the Trienens Institute for Sustainability and Energy.
Keywords
- CsHPO
- Pt nanoparticles
- fuel cell
- oxygen reduction reaction
- solid acid fuel cell
ASJC Scopus subject areas
- Mechanics of Materials
- Mechanical Engineering
