Green Car Congress  
Home Topics Archives About Contact  RSS Headlines

« Mercedes-Benz Vans strategic initiative adVANce: holistic system solutions for transport; electric Vision Van | Main | LeddarTech launches LeddarVu, a new scalable platform towards high-resolution LiDAR; Vu8 solid-state LiDAR »

Print this post

Sandia fuel cell membrane outperforms market; temperature range and durability

7 September 2016

Researchers at Sandia National Laboratories, have developed a new membrane for fuel cells based on quaternary ammonium-biphosphate ion pairs that can operate under conditions unattainable with existing fuel cell technologies. A paper describing the Sandia-patented technology is published in the journal Nature Energy.

Fuel cells with this membrane technology exhibit stable performance at 80–160 ˚C with a conductivity decay rate more than three orders of magnitude lower than that of a commercial high-temperature PEM fuel cell. By increasing the operational flexibility, this class of fuel cell can simplify the requirements for heat and water management, and potentially reduce the costs associated with the existing fully functional fuel cell systems, the researchers said.

Currently, commercial PEMs in most fuel-cell-powered vehicles use a water-swollen co-polymer film for the critical proton exchange. Electrons are peeled off by oxidation of the hydrogen atoms and hydrated protons pass through the film to combine with oxygen on the other side to form water as a byproduct. The efficiency of the exchange process depends upon water, so efficiency—measured as proton conductivity—goes down as humidity goes down. (Earlier post.) Further, this means that the operating temperature can’t get higher than water’s boiling point. Higher temperatures dry out the membrane, increase cell resistance and reduce performance.

Part of the issues with the current PEMs is that you need to hydrate the hydrogen fuel stream for high performance, and the fuel cell can’t run effectively at temperatures higher than the boiling point of water. This problem can be solved by employing hydrated fuel streams and having a larger radiator to more effectively dissipate waste heat. Automakers are doing this now. But if PEM fuel cells didn’t need water to run, it would make things a lot simpler.

—Sandia chemist Cy Fujimoto

Another problem is that material costs for the current membrane of choice can be approximately $250-$500 per square meter. The US Department of Energy (DOE) would like to see $5 to $20 a square meter, Fujimoto said.

Researchers have tried to solve these problems with a high-temperature method that uses phosphoric acid to dope a polybenzimidazole membrane at more than 180 ˚C. But the membrane can’t operate below 140 ˚C without degrading the phosphoric acid. Thus the membrane is unsuitable for automotive applications, where water condensation from cold engine start-ups and other normal reactions at the fuel cell cathode unavoidably bring the temperature down into undesirable ranges that leach the phosphoric acid out of the reaction.

The Sandia ammonium-biphosphate ion pairs have exhibited stable performance over a wide range of temperatures.

There probably will be industrial interest in this discovery. Our polymer contains a tethered positive charge which interacts more strongly with phosphoric acid, which improves acid retention. Heating the fuel cell and adding humidity doesn’t reduce performance.

—Cy Fujimoto

The fuel cell work was supported by the Fuel Cell Technology Office of the Department of Energy’s Office of Energy Efficiency and Renewable Energy.

Resources

  • Kwan-Soo Lee, Jacob S. Spendelow, Yoong-Kee Choe, Cy Fujimoto & Yu Seung Kim (2016) “An operationally flexible fuel cell based on quaternary ammonium-biphosphate ion pairs” Nature Energy 1, Article number: 16120 doi: 10.1038/nenergy.2016.120

September 7, 2016 in Fuel Cells, Hydrogen | Permalink | Comments (7)

Comments

This could become one of the 'all around' superior FC to hit the market place by 2020 or so.

Vehicle manufacturers like Toyota, Honda and Hyundai will certainly adapt that technology to their future FCs and FCEVs. Others will follow.

Not having phosphoric acid helps, temperature above 100c makes water management easier, it is just vapor at the output.

It makes all thermal management easier; less cooling air to do the same job.  It also helps with e.g. use of heat to warm the cabin; higher temperatures mean smaller heat exchangers.

All this hydrogen fuelcell technology is just a joke at best. It cost 7x time more than a normal gasoline ice engine. This is just financial fraud paid on your tax bill. These are scammers.

This would be awesome for winter driving, assuming the fuel cell had enough waste heat to be manageable. Defroster air potentially hot enough to harm you. (yes it would be blended, but it's intriguing)

Finally there is hope to shave a few hundred pounds of gaudy radiators off of fuel cells.


Problem is the car probably can't sit for a long while without having fuel /battery charge. The modules' would have to be small, so a whole bunch of heat wouldn't have to be used to maintain the life of the PEM.

We really could have a tiny radiator on this thing.

I imagine a 10-25kw range extender bev car with a 50kwh battery, have a long range mode selector for cross country trips and have basically an EV only car the rest of the time.


BEV LD trucks would probably need 50-150kw generation, and a >100kwh battery.

Best of both worlds and completely comparable to gasoline cars.

You could have 90% of driving under BEV only, and longer drives could be met with fast charge EV networks and hydrogen stations.

A higher-temperature PEM electrolyzer cell can use steam instead of water, thereby can shave off 6 kWh off of the 50 kWh to make 1 kg of H2. This is because it takes about 6 kWh of energy per kg of H2 produced, to turn liquid water into steam, before the steam can be separated into gaseous H2 and O2.

Thus, the waste heat of the electrolyzer can be used to turn water into steam, then the steam will take only 44 kWh of electricity to make 33 kWh in 1 kg of H2. Thus, the efficiency of electrolysis will be raised from 66% to 75% for H2 at LHV (Lower Heating Value) to use as a fuel, or to ~90% for H2 at HHV (Higher Heating Value) when the H2 will be used for space heating.

High-efficiency electrolysis will make H2-E-storage medium just as efficient as battery for combined heat and power applications, with round-trip efficiency at nearly 90%.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Green Car Congress © 2017 BioAge Group, LLC. All Rights Reserved. | Home | BioAge Group