Material and Device Design for Rapid Response and Long Lifetime Proton Exchange Membrane Fuel Cells (PEMFCs)
- Author(s): Shen, Gurong
- Advisor(s): Lu, Yunfeng
- et al.
Proton exchange membrane fuel cells (PEMFCs) have been regarded as the most promising candidate for fuel cell vehicles and tools. Their broader adaption, however, has been impeded by cost and lifetime, as well as the inability to respond to fluctuations associated with operation conditions, fuel supply, and transient load. In this dissertation, a novel strategy to improve the performance and durability of PEMFCs for automotive application is purposed. Unlike the conventional hybrid strategies, which batteries or capacitors are always integrated with the fuel cell to achieve high fuel efficiency and high-power output, the novel fuel cell is integrated with energy-storage materials to form a hybrid device.
Tungsten oxide is proved to be a promising energy-storage material using in the PEMFC application, which has high chemical stability and excellent electrochemical performance in the fuel cell configuration. By integrating a thin layer of tungsten oxide (WO3) within the anodes, novel PEMFCs shows significantly enhanced power performance for transient operation, as well as improved durability against adverse operating conditions. Meanwhile, the enhanced power performance minimizes the use of auxiliary energy-storage systems and reduces costs.
In addition, the mechanisms of degradation of PEMFCs, as well as the working principles of WO3 in the hybrid cell are studied. The WO3 layer in the hybrid cell serves as a rapid-response hydrogen reservoir, oxygen scavenger, sensor for power demand, and regulator for hydrogen-disassociation reaction, effectively stabilize the anode potential and inhibit rising of the anode potential during the transient conditions.