Sulfonated poly(aryl ether)-type polymers as proton exchange membranes: synthesis and performance

Peer reviewed: YesNRC publication: Ye

Methanol crossover in direct methanol fuel cell systems.

Direct methanol fuel cells (DMFCs) are currently being investigated for a number of different applications from several milliwatts to near kilowatt size scales (cell phones, laptops, auxiliary power units, etc .). Because methanol has a very high energy density, over 6000 W hr/kg, a DMFC can possibly have greatly extended lifetimes compared to the batteries, doesn't present the storage problems associated with hydrogen fuel cells and can possibly operate more efficiently and cleanly than internal combustion engines

Effect of BPSH post treatment on DMFC performance and properties

Direct methanol fuel cells (DMFCs) are being investigated for applications ranging from milliwatt (cell phones) to kilowatt (MUS) size scales. A common pitfall for DMFCs has been the inability of the electrolyte, typically Nafion, to act as an effective methanol barrier. Methanol crossover adversely affects the cell by lowering the cell voltage due to a mixed potential at the cathode and lower fuel utilization. Improved DMFC performance was demonstrated with sulfonated poly(arylene ether sulfone) copolymer membranes (1). Another study has shown the dependence of polymer properties and morphology on the post treatment of such membranes (2). In agreement with measurements on free-standing films, the fuel cell characteristics of these membranes have been found to have a strong dependence on acidification treatment. Methanol permeability, proton conductivity, and electro-osmotic drag coefficient all were found to increase when the membranes were acidified under boiling conditions versus a low-temperature process

Six cell 'single cell' stack diagnostics and membrane electrode assembly evaluation

Polymer electrolyte fuel cells are promising candidates as energy conversion devices in applications from portable power to stationary applications or electric vehicles. In order to achieve practical voltage, power and energy density, stacks are employed for almost all applications. Here, we present a six-cell 'single cell' stack in which individual cells can be isolated from the stack by current carrying leads found within each of the bipolar plates. The current carrying leads allow individual cells to be isolated from the rest of the stack, so that cells can either be tested together or independently. The design of the stack, utility for specific applications, including stack diagnostics and membrane electrode assembly (MEA) testing, and some experimental results, obtained using the stack, are presented. Special focus is given in this paper to the area of direct methanol fuel cell (DMFC) stacks, however the equipment and many of the experimental results presented are appropriate for other fuel cell systems