[3 of 3] Its range is skyrocketing and its cost is approaching gasoline vehicles. The electric car has made giant strides thanks to the improvement of lithium-ion batteries. Is the next revolution for tomorrow?

The promises follow each other and look alike: a battery that stores three times more energy, another that costs almost nothing or that charges in two minutes.

Reading the announcements made by the various research laboratories, one has the impression that a revolution is about to occur. So would it be wiser to wait for the next generation of batteries before taking the electric turn?

Professor Jeff Dahn of Dalhousie University in Halifax sees it differently. “Lithium-ion batteries continue to improve, even if the gains are perhaps less impressive than at the beginning”, summarizes the researcher, who has devoted their entire career to him and to whom we already owe several advances major.

Its work is now partly funded by the American manufacturer Tesla, as part of a unique partnership supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).

The research program he directs aims at short-term gains on three aspects: the energy density of batteries, their lifespan, but above all their cost.

The large family of lithium-ion batteries in fact brings together several different chemistries, each of which has its specialized applications. A cell phone, for example, does not have the same requirements as a drill or a car.

However, these batteries have their general construction in common: inside a cell, lithium salts are dissolved in a liquid, the electrolyte, which allows them to go back and forth between two electrodes, one positive, the other negative.

The differences between the types of batteries are in the electrolyte, but especially in the composition of the coating of each of the two electrodes. By modifying these ingredients, we influence the different properties of the battery: energy density, charging speed, power supplied, safety, cost, lifespan, etc.

For researchers, the challenge is to improve the recipe without compromising this fragile balance.

“For example, if you change the coating of the positive electrode to reduce the cost of a battery, it can sometimes take months or years of work before finding the right electrolyte recipe to obtain the desired performance,” explains Jeff Dahn.

Speed ​​up research

Jeff Dahn’s laboratory is a real hive, where more than 1000 battery recipes are tested each month, all slightly different.

The lifespan of a battery is an essential criterion, but it is also the most difficult to measure, according to Jeff Dahn.

For a car, we aim for a lifespan of at least 10 years. As researchers, we cannot afford to test each cell for 10 years, so we had to develop advanced diagnostic tools to reduce our tests to a few weeks. Jeff Dahn, holder of the NSERC-Tesla Industrial Research Chair

His laboratory has a veritable arsenal to measure the minute degradation of a battery between each recharge cycle or to detect the slightest loss of heat or the production of gas in a cell, which are all signs of chemical reactions. undesirable that compromise the durability of the batteries.

Several of these tools, developed to speed up the work of Jeff Dahn, have also been adopted by other teams in search of more efficient batteries, which can thus identify promising veins more quickly.

The bunny and the turtle

With the increasing popularity of electric cars, research on batteries is in full swing and many laboratories hope to develop the technology that will replace lithium-ion batteries.

You never know when someone is going to hit a homerun. Several teams are working on really interesting chemistries. Jeff Dahn, holder of the NSERC-Tesla Industrial Research Chair

Some of this work could lead to much more efficient batteries than at present. But, between a discovery in the laboratory and the next generation of electric cars, the road is often full of pitfalls, as evidenced by decades of work devoted to optimizing lithium-ion batteries.

Until the next technological revolution, Jeff Dahn therefore continues to bet on lithium-ion, because even if the gains are sometimes modest, they can quickly materialize in the next models. And, for 10 years, it is this approach in small steps that has made a giant leap in the electric car.