Effects of Operating Conditions on Internal Resistances in Enzyme Fuel Cells Studied via Electrochemical Impedance Spectroscopy
- Georgia Institute of Technology
- ORNL
Enzyme fuel cells (EFCs) offer some advantages over traditional precious-metal-catalyzed fuel cells, such as polymer electrolyte membrane fuel cells (PEMFCs). However, EFCs exhibit far less power output than PEMFCs and have relatively short life spans before materials must be replaced. In this work, electrochemical impedance spectroscopy (EIS) is used to analyze the internal resistances throughout the EFC at a variety of operating conditions. EIS analysis is focused primarily on the resistances of the anode, solution/membrane, and cathode. Increased enzyme loading results in improved power output and reductions in internal resistance. Conditions are identified for which enzyme loading does not limit the EFC performance. EIS experiments are also reported for EFCs operated continuously for 2 days; power output declines sharply over time, while all internal resistances increase. Drying of the cathode and enzyme/mediator degradation are believed to have contributed to this behavior. Finally, experiments are performed at varying air-humidification temperatures. Little effect on internal resistances or power output is observed. However, it is anticipated that increased air humidification can improve longevity by delivering more water to the cathode. Improvements to the enzymatic cathode are needed for EFC development. These improvements need to focus on improving transport rather than increasing enzyme loading.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE; Work for Others (WFO)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1033524
- Journal Information:
- Journal of Power Sources, Vol. 201, Issue 1 March; ISSN 0378-7753
- Country of Publication:
- United States
- Language:
- English
Similar Records
Operating proton exchange membrane fuel cells without external humidification of the reactant gases
Effects of proton-exchange membrane fuel-cell operating conditions on charge transfer resistances measured by electrochemical impedance spectroscopy