Scientists use superconducting nanowires to replace Li-ion car batteries

Could the ultracapacitor replace lithium ion in hybrids and plug-in vehicles? Our senior automotive editor already thinks the science adds up, but it’s in a tiny box at a messy lab that the future of automotive efficiency is taking a surprising turn toward extending range and battery life.

One of the most promising experiments here is tucked away in what appears to be the messiest part of the entire lab, a small room littered with hand tools and testing gear. Joel Schindall, the associate director of LEES, pulls a tray out of a cabinet and flips it open. Inside are four black squares, like overturned tiles from a Magnetic Poetry set. If my job was to clean out this lab, I would probably take one look at these unassuming little things and fling the entire tray into the nearest trash can. Because unless they’re under an electron microscope, vertically aligned carbon nanotube arrays don’t look like much.

The point of these particular arrays is to capture ions and eventually give traditional rechargeable batteries a run for their money. The focus of Schindall’s research is ultracapacitors, which store drastically less energy than a battery but have essentially none of the drawbacks. In any capacitor, there’s no battery memory caused by partial discharging and no reduction in capacity with each recharge. “They never wear out, they have no electrolyte, they don’t have any chemistry taking place in them,” Schindall says. “It’s just an electric field that stores the energy. So you can recharge a capacitor a gazillion times. It’s very efficient—just the internal resistance of the wires.” The ions cling electrostatically to materials in a capacitor, which also allows for much quicker charge times. And by avoiding the chemical reaction that drives traditional batteries, there’s no real danger of a capacitor suddenly overloading—or exploding like a laptop’s lithium-ion battery pack. (For more on how this technology works, read senior automotive editor Mike Allen’s new take on why ultracapacitors could replace batteries in hybrid cars.)

A group of scientists has created a new, improved fuel-cell electrode that is very lightweight and thin. Composed of a network of single-walled carbon nanotubes, the electrode functions nearly as well as conventional electrodes but renders the entire fuel cell much lighter. The research is an important step toward lightweight power supplies, which are becoming necessary as electronic devices get ever smaller and more streamlined.

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Earlier approaches utilizing carbon nanotubes in fuel cells have not taken full advantage of this material, only used as an additive to improve some of the properties of conventional electrode materials. But, until now, carbon nanotubes haven't been recognized as having the potential to replace the entire electrode.

Typically, carbon without any crystalline structure, known as amorphous carbon, is used in fuel cells because of its large surface area and porosity. Networks made of pure, single-walled carbon nanotubes boast the same properties, but weigh far less. They are ten times thinner and lighter than traditional electrodes. In addition, the long, thin shapes of the nanotubes give them a high conductivity—more than one thousand times larger than that of amorphous carbon. This is high enough that the current collector, another component of fuel cells, can be replaced as well.