Researchers look to break the barriers of battery technology for electric vehicles

At his lab at Dalhousie University in Halifax, physicist Jeff Dahn leads a team of 20 researchers and staff who work on some of the most vexing challenges presented by the lithium-ion battery.

Dr. Dahn receives funding from California-based Tesla Inc. and Canada’s National Science and Engineering Research Council to improve the performance, extend the life and lower the costs of the battery that powers electric vehicles (EVs).

Currently, lithium-ion batteries that are light enough and cheap enough for a mass-market car can store only enough electricity to run the vehicle for a few hundred kilometres.

However, there have been significant advances in recent years. Researchers around the world are teaming up with governments, traditional auto makers and new entrants into the business to create battery-powered cars that can compete head-on with traditional vehicles.

“We need to focus on cost reduction,” Dr. Dahn said in a recent interview. “You can make really good electric vehicles with lithium-ion batteries as it stands today. Decreasing the battery cost will lead to a corresponding decrease in electric-vehicle costs.”

He argues electric vehicles are already a practical choice for most drivers, who rarely exceed their range limits.

But researchers such as Dr. Dahn are also focused on increasing the energy density of EV batteries. Among metals, lithium offers the best potential, but it also produces “parasitic reactions” – unwanted chemical processes that degrade the battery’s function and reduce its lifespan.

Dr. Dahn can’t talk about the specific work he is doing for Tesla, but his lab is focusing on those parasitic reactions. To avoid them, a battery must be routinely charged below its maximum voltage levels. The Dalhousie lab is testing different materials to determine whether the parasitic reactions can be reduced without sacrificing energy density or charging – or cost. If you can increase the efficiency of a battery, you reduce the cost of achieving better performance.

Industry began using lithium for battery anodes in the 1970s, but the metal was unstable and the batteries were prone to ignite. So researchers came up with the lithium-ion battery, which uses lithium in a solvent as the electrolyte – the material that carries the charge between the battery’s two end points.

Karim Zaghib leads Hydro-Québec’s research on advanced batteries at its Montreal-area labs, where the provincial utility has been studying batteries since 1979. Dr. Zaghib is focused on moving the industry beyond the lithium-ion battery to a solid-state version.

The difference is in the electrolyte material. In current lithium-ion batteries, the electrolyte is organic, liquid material. The newer technology uses solid lithium-based electrolyte material, which is more energy-dense and less likely to short-circuit. Over the next four years, Dr. Zaghib believes his labs will produce a solid-state battery with twice the energy density of existing lithium-ion batteries, while also reducing costs and speeding up charging time.

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