Category Archives: News

Battery researchers

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Pictured above are Daniel and Jerome, in the battery lab at CUNY. Both of these guys are going to grad school in the fall after working here for a while. It’s been great having them, and we’ll miss them a lot.

Jerome was a student in my transport phenomena class at NYU three years ago. When class was over he was about to enter his last year, and he asked if he could do his senior project working with me. One day a week he took the train up to Harlem, where CUNY is, and built batteries for a year. He must have liked it, because after graduating he started working here as an engineer, and now has a hand in just about everything we do.

Each year since then I’ve had a new student from NYU working on batteries at CUNY. They get their senior thesis out of it, but also they get a chance to see how research really works, and I think that’s important for someone who wants to work in science and engineering. Interpersonal skills, how to get time on lab equipment, how to organize your data, how to find important variables, how to tell what experimental noise looks like, etc. Back in the 90s I was a co-op student at Owens Corning, and I learned a lot of things there … skills I still use today.

New Book About Enzyme Electrodes

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I wrote Chapter 9 in Enzymatic Fuel Cells: From Fundamentals to Applications, which is coming out May 19th. It’s edited by Plamen Atanassov, Heather Luckarift, and Glenn Johnson. The book grew out of a multi-university research project I was part of as a graduate student, with the goal of using biological catalysts for small power sources.

This is controversial research: it is, trust me. But if it works it has a high payoff. Summarizing just one possible application: we as humanity use an expensive element, platinum, for almost all of our room-temperature catalysis. This is why you don’t own very many things that involve room-temperature catalysis. However, living things do catalysis at physiological temperature (98.6 degrees F, not much higher) all the time. If we could use their tricks, catalysis would get much less expensive.

Some enzyme electrodes actually have incredibly high volumetric energy densities. The ones I was making as a graduate student reduced oxygen at 40 A/cm3 at 0.7 V, which is higher than some old-school platinum electrodes, and they do all the catalysis with copper. The downside is they don’t last a long time. But since platinum is 21,000 times more expensive than copper, it could be worth it.

My chapter gave a me a chance to summarize my graduate research in a unified way, making the point I wanted to make. Essentially I showed you could double the catalytic current of one of these electrodes by being smarter about the transport phenomena involved. I published the results in two papers with dry, academic titles, because let’s face it I sometimes like the dry and academic. Only now, after a few more years of experience, I feel it would have been better to publish them together and title it The Point Is The Current Is Twice As High. Here’s the important graph below (from here):

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See how the curves are S-shaped, and the bottom part is at about -7 mA/cm2 in one case and about -14 mA/cm2 in another? That’s the doubling. There’s actually a more important figure earlier in the paper, but this one is the easiest to explain. Science: it’s also about communication.

Leveling zinc with bismuth

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Just published a paper called “An in situ synchrotron study of zinc anode planarization by a bismuth additive.” It’s a mechanistic study to explain a result we discovered in the early days of the CUNY Energy Institute. I was looking for an additive to kill dendrite formation in zinc, working with Dan Steingart and Abhinav Gaikwad, who was a graduate student at the time. Turns out a little bit of bismuth can keep zinc layers quite flat when electroplated from a flowing electrolyte. The middle image below shows it clearly:

bismuth levels zinc

The percentages are % of the bismuth saturation limit, which is very low. 10% is 3 ppm, an almost undetectable amount, and it has an enormous impact. This result could be used to increase the energy density of zinc batteries, by keeping the zinc layer compact. When naming the paper I called it “planarization” instead of “leveling” because the mechanism is different than that of a leveler in traditional electroplating.

Exciting results from inside batteries

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Screen Shot 2014-01-22 at 12.55.23 PMWe just had a paper published in The Journal of Materials Chemistry A about some research done at Brookhaven National Lab. It’s cool and new because it uses extremely high-power X-rays that can penetrate thick materials, even metals. The technique was developed to find points of strain inside high-performance materials like turbine blades. We use it to do the same thing, but inside batteries. And not just small batteries, but very thick ones, like D-cell batteries, which are an inch or two across.

Inside the battery, the X-rays bounce off crystal faces of the materials, and because of that you can know things about how far apart the atoms are. A D-cell has zinc at its center (anode) and manganese dioxide around its outside (cathode). The lines in the image above are like fingerprints of these materials. (And the numbers like (002) refer to the crystal faces themselves.)

Another cool thing about this technique is that it is very fast. You can scan the battery in a few minutes. This means that as it’s charging and discharging you can watch the materials changing in real time, inside the sealed battery. Basically this is what we do in the paper, shown below, seeing some things no one has ever been able to see before (except by cracking a battery open after cycling it, which can sometimes be effective, but not always). Brookhaven (on Long Island, in New York) is one of the only places in the world you can do this.

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