research & development

Cheaper, Better Battery for Hybrids

CSIRO researchers in Melbourne, Australia have developed a new type of lead-acid battery to replace the NiMH batteries used in hybrid cars. The UltraBattery, developed by Dr. Lan Trieu Lam and his CSIRO team, combines a lead-acid battery with a supercapacitor. The combination stores as much energy as a standard lead-acid battery, but without the messy deposits on the plate.

"By acting as a buffer during charging and discharging, the capacitor boosts the battery's life to match that of NiMH batteries," says Lam.

During lab tests the UltraBattery lasted four times as long as the best lead-acid batteries, while producing 50% more power. A test vehicle using the UltraBattery has so far covered 185,000km.

Japanese firm Furukawa Battery Co. has started modifying a plant to to make the UltraBattery by the middle of next year. In the U.S., battery manufacturer East Penn in Pennsylvania will make the device.

Micro-Batteries for Miniature Devices

Massachusetts Institute of Technology engineers have developed a way to at once create and install micro-batteries by stamping them onto a variety of surfaces, reports Frost & Sullivan Technical Insights. These batteries could power miniature devices from labs-on-a-chip to implantable medical sensors.

The MIT team created both the anode and the electrolyte. First, on a clear, rubbery material the team used a common technique called soft lithography to create a pattern of tiny posts either four or eight millionths of a meter in diameter. On top of these posts, they then deposited several layers of two polymers that together act as the solid electrolyte and battery separator.

The next step involved viruses that self-assemble atop the polymer layers on the posts, ultimately forming the anode. They altered the virus's genes so that it formed protein coats that collect molecules of cobalt oxide to form ultra-thin wires. The final result: a stamp of tiny posts each covered with layers of electrolyte and the cobalt oxide anode. This was then turned over and transferred to a platinum structure.

The resulting electrode arrays exhibit full electrochemical functionality.

Better Batteries for Future Vehicles

One way to improve lithium-battery technology is to replace traditional carbon anodes with negative electrodes made of materials that are reduced by lithium to form a metal and a corresponding lithium compound.

French scientist Luc Aymard led a research team that developed new conversion reaction electrodes that used metal hydrides ‚ compounds with a metal covalently bonded to hydrogen. Incidentally, metal hydrides may also be useful for fuel-cell technology, which is another candidate for powering electric vehicles.

Although many metal hydrides are available, Aymard and colleagues chose the inexpensive magnesium hydride due to its advantageous electrochemical properties. The magnesium hydride electrodes mitigated battery cell polarization, meaning that the electrochemical process is highly reversible. The reversible capacity is nearly the same as the discharge capacity: about three times better than current Li-ion batteries. The capacities are sustainable for at least 50 cycles, and the design can be tweaked to go much longer.

Overall, magnesium hydride dramatically lowered the polarization of Li-ion batteries without losing the advantage of having a high capacity. In addition, the relatively mild conditions required for hydrogen absorption and desorption point to potential benefits of using magnesium hydride in fuel cells.