PolyFuel Inc. announced here today a new, thinner fuel cell membrane that delivers the highest power levels ever demonstrated for passive direct methanol fuel cells (DMFCs). The company also revealed that in Japan, PolyFuel is now working with six major corporations that are developing DMFC systems, including NEC and Sanyo Electric.
The new hydrocarbon DMFC membrane, with a thickness of 45 microns, delivers 33% more power than the previous industry benchmark, PolyFuel's own 62-micron PolyFuel membrane, which is being utilized or studied worldwide by original equipment manufacturers (OEMs), particularly in Japan. The reduced thickness increases performance by reducing the resistivity of the membrane, while allowing a higher level of water back diffusion.
"PolyFuel has been working very hard with OEMs to refine its membrane technology to meet their specific needs," said Jim Balcom, president and CEO of PolyFuel. "Perhaps the most requested feature has been a thinner membrane that retained the methanol crossover, water crossover and durability advantages of our 62-micron membrane, while meeting aggressive, new fuel cell performance targets. We are pleased that we have been able to specifically engineer a membrane to meet these requests."
Of the company’s six Japanese OEM partners, five are already evaluating the 45-micron membrane for near-term commercial use, including conducting extensive durability and performance testing. All are agreed, said Balcom, that PolyFuel's hydrocarbon membranes have been very helpful to their DMFC system development efforts.
According to Balcom, the new 45-micron membrane's peak electrochemical performance in passive hardware at 40C is 80 milliwatts per square centimeter of membrane (80mW/cm²) at 0.28V versus 60mW/cm-squared for the 62-micron membrane – a 33% improvement that results directly from the 27% reduction in thickness.
Methanol crossover at open circuit voltage (OCV) now stands at approximately 57 mA/cm², slightly above previous levels, but still significantly below that of fluorocarbon membranes. Water back diffusion has been improved by 30%, this is particularly important for advanced passive fuel cell systems using pure or high concentrations of methanol (fuel).
