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Building a powerhouse for the electric car

Gillian Goward's research will improve the reliability and cost of batteries that power electric vehicles.
Building a powerhouse for the electric car

Gillian Goward holds a magnetic resonance probe, which will be modified to run lithium ion cells with the probe, in the spectrometer.

As they search for a power source for tomorrow’s electric cars, Gillian Goward and her colleagues are peering into the tiniest of worlds: the dance of the atoms in battery electrodes and electrolytes. The McMaster University researchers are seeing electrically charged ions move about in milliseconds in lithium ion batteries.

 All of this demands work at the molecular level. Researchers must see the movements of atoms to learn how a battery performs, to understand its ionic conductivity. That calls for the powerful images of nuclear magnetic resonance spectroscopy. NMR, says the associate professor of chemistry, provides “an important piece of the puzzle".  

 Using NMR as a tool is similar to what doctors do when they employ magnetic resonance imaging (MRI) to see within a human body. Non-invasive MRI imaging supplies high-contrast “slices” along a plane or dimension, scans whose images can show disease patterns or organ abnormalities.

 The spectra seen with NMR offer information on the number and types of chemical entities in a molecule. Researchers are able to see chemical interactions, how batteries hold a charge, and what happens when a battery gets hot. NMR imaging can do that, in real-time, in the range of 5 to 10 milliseconds.

 Around the globe, the hunt is on for advanced technologies in batteries that will power electric vehicles. For perhaps a decade, the standard has been the lithium-cobalt oxide battery. But cobalt is costly and a very toxic material. So, many researchers have been studying the dynamics and chemistry of lithium ion batteries.

 “Lithium technology is going to be the next technology to make the plug-in electric vehicle possible,” says Dr. Goward. Lithium-ion batteries are considered low-maintenance, rechargeable units that can provide both high voltage and great capacity, resulting in high energy density within the battery.

 A note of explanation: today’s hybrid vehicles are more likely to use nickel-metal hydride batteries. Such hybrids are not true electric vehicles. They combine gasoline-fueled engines with electric motors. Typically, the electric motor provides extra power to assist the engine in accelerating, passing, or hill climbing.

 It was the rechargeable lithium-ion battery that energized the consumer electronics revolution, units that were used in cellphones and digital cameras. But plug-in electric car batteries must be able to survive the abuses of daily driving and must last far beyond the typical two- or three-year lifespan of a laptop.

 Dr. Goward is one of more than 200 researchers at Canadian universities engaged in the Auto21 project. Auto21 is an industry/government/university collaboration focused on all manner of advanced vehicle technologies. For her, a “reasonable goal, industry-wise”, is to develop a battery that can be recharged up to 10,000 times.

She and colleagues at the universities of Calgary and Saskatchewan study things like  tradeoffs between safety, energy density, the length of storage time, the degradation of a battery’s capacity, and extended cycle-life. They also study different cathode (the positively charged electrode) host materials, such as iron and manganese.

 But lithium, the alkali metal, is not a truly renewable commodity like solar rays or wind. True, its use in batteries will eliminate the need for carbon-based gasoline and the resultant vehicle emissions. But lithium is not a real green-energy source, it is “an electrical currency”, says Dr. Goward.

 A true green source would be something like using hydrogen derived in efficient and commercial quantities, not from fossil fuels but from, say, water, via a non-emissions technology. And that hydrogen would have to be available where vehicles could be “gassed" up or be able to be stored in long-term fashion within a recyclable battery.

“Batteries are only green as long as the energy is coming from a green source, and you are able to recycle the cell itself,” she said in an interview for a recent Auto21 publication. “Ultimately, we need to be doing both those things. Batteries on their own are not going to save the day.”