The Lithium Economy
Why hydrogen might not power future vehicles and lithium-based batteries might.
The need to reduce carbon emissions and to find a long-term replacement for oil has many people looking at hydrogen fuel cells to power factories and vehicles. But finding ways to store volatile hydrogen safely and bring down the costs of fuel-cell ingredients, which currently include the fantastically expensive element platinum, has proved difficult.
While the quest for the affordable fuel cell continues, many environment-conscious consumers have been turning to hybrid cars to reduce emissions. At the heart of the hybrid is a technology that may be less “sexy” than fuel cells, but, according to MIT’s Donald Sadoway, could be key to a fossil-fuel-free tomorrow – the rechargeable battery.
TechnologyReview.com’s nanotechnology and materials science editor, Kevin Bullis, recently talked with Sadoway, a professor in the department of materials science and engineering. He holds 13 patents, has received multiple teaching awards, and has published more than 100 papers on the future of batteries and the all-electric car.
Technology Review: Why did you get into battery research?
Donald Sadoway: What got me into this in the first place was the desire to get rid of the internal combustion engine. As far as powering portable devices and so on, there are business opportunities there, but I don’t get excited about it. I did not get into this line of research because I wanted to help somebody talk 30 percent longer on his cell phone.
TR: Why get rid of the internal combustion engine?
DS: The real problem is greenhouse gas accumulation in the atmosphere. If we don’t start dealing with that question, the rest doesn’t make a damn bit of difference – if 25 years from now the general temperature of the United States is 10 degrees Fahrenheit higher and the oceans are four feet [higher]. We really need to think about sustainable ways of generating electric power and then moving [around] as much as we can without burning carbon.
TR: What about using fuel cells for vehicles to reduce emissions?
DS: I don’t believe in fuel cells for portable power. I think it’s a dumb idea. The good news is: they burn hydrogen with oxygen to produce electricity, and only water vapor is the byproduct. The bad news is: you have to deal with molecular hydrogen gas, and that’s what’s stymieing the research and in my opinion is always going to stymie the research.
That’s why I don’t work on fuel cells. Where’s the infrastructure? Where are we going to get hydrogen from? Hydrogen is a molecule, it’s H2. To break it apart, to get H+, you’ve got to go from H2 to H, and that covalent bond is very strong. To break that bond you have to catalyze the reaction, and guess what the catalyst is? It’s noble metals – platinum and palladium. Have you seen the price of platinum? Lithium [for lithium ion batteries] is expensive. But it’s not like platinum. Lithium right now is probably $40 a pound. Platinum is $500 an ounce. If I could give the fuel-cell guys platinum for $40 a pound, they would be carrying me around on their shoulders until the day I die.
TR: We’ve heard about all-electric cars for some time, but so far they haven’t panned out – you can’t get very far on a single charge, for example. What has happened in battery development that makes you think this will change?
DS: There was a lot of trial and error with good rules of thumb. But there’s far too many possibilities, and that’s where [MIT materials science professor] Gerbrand Ceder came in, who was using the principles of quantum mechanics to predict the principles of compounds yet unsynthesized. With Gerbrand’s computational materials science, we were able to identify compounds previously ignored in this application.
TR: How good can batteries get?
DS: I think we could easily double [the energy capacity of] what we have right now. We have cells in the lab that, if you run the numbers for a thin-film cell of reasonable size, you end up with two to three times current lithium ion [batteries].
But there’s more. The fantasy of all fantasies is chromium. If we could stabilize chromium [as a material for battery cathodes] and I could…give you a battery with 600–700 watts per kilogram [of energy capacity] with reasonable drain rate, that says good-bye hydrogen economy.
TR: You’ve driven an electric car before. What was that like?
DS: I opened the sun roof, rolled down the windows, and I pulled out. It was like a magic carpet. You hear people laughing, talking, and you’re interacting with the city. I returned the vehicle to the fellow at Boston Edison, and I came back here and said, “I’ve got to work harder. I’ve got to make this thing happen.” The only reason that car isn’t everywhere: it couldn’t go more than 70 miles on a charge. But you make it 270, game over. Anybody who drives it will never go back to internal combustion.
TR: What’s next?
DS: What we need to understand better is systems. Up to now we’ve been asking, “What makes the best polymer electrolyte?” and then we test it against some cathode and some anode. We need to understand what happens when we put the battery together.
Let’s keep the research going. Let’s use the phrase that they used in the early days of nuclear power – “I want this stuff too cheap to meter.” I want these batteries so cheap you can give them away. We’ve got a long way to go, but we’ve got to work at it.