Charging a battery is more difficult than you might think. While it has become an everyday event for all of us (more than once a day if you have an older iPhone…), getting electricity from a socket into a lithium-ion battery is trickier than it sounds.
Basically, what you’re chemically trying to do is to get the ions of lithium (molecules of lithium metal that have a positive electric charge) to move from the positive cathode of the battery to the negative anode.
You do this by passing an electrical current through the battery, but beware — try to add too much electricity too quickly, and you’ll have problems. Too much power means that the lithium ions move too quickly, and some get left behind. These left-behind ions cause lithium plating on the anode, which damages it and makes the battery less efficient. This is the beginning of battery degradation.
While worries about electric car batteries degrading quickly have been largely proven wrong so far, there is an ineluctable science to this — faster charges, and more of them, mean damage to the battery’s internal chemical structure, which makes it less efficient over time.
Worse, too much fast charging can actually trigger physical damage — a study by the University of California found that high charging temperatures and electrical resistance caused by high-speed battery charging can trigger physical cracks and leaks of the battery’s liquid electrolyte (the electricity-friendly fluid that fills the core of a lithium battery).
The research found that rapidly charging a battery too often can result in the battery’s anode and cathode becoming exposed to the air, and that dramatically increases the risk of a battery fire. Little wonder, then, that most electric cars now come with warning notices on their infotainment systems telling you not to charge a battery above 80 per cent power. We seem to be stuck charging slowly and steadily, something that massively restricts the usefulness of electric cars.
There may be a solution. Indeed, Dr Eric Dufek reckons that he can get you charged up and back on the road in about 10 minutes.
Dufek is the department manager for Idaho National Laboratory’s energy-storage and electric vehicle department. He and his team have been working on a potential solution to the problem of not just fast charging but really fast charging. While many carmakers and battery producers are saying that solid-state battery technology (where the liquid electrolyte is replaced by a ceramic one) will solve problems of both speed and degradation, solid-state tech always seems to be about five years away, and some in the battery industry have begun to express doubts about its commercial viability.
Dufek isn’t waiting, and is instead working on making the charging of existing lithium-ion batteries safer, more efficient and less damaging. He and his team at the Idaho National Laboratory have a solution that is, on the face of it, rather simple — listen to what the battery is telling you.
Okay, so batteries can’t talk but computers can talk to each other, in a sense, and that’s what Dufek is doing — creating artificially intelligent machine-learning software for an EV charger that communicates with the battery of each individual car. By learning from each battery what its current physical and chemical state is, the charger can in real time adjust the power and speed of the charging process to most efficiently top the battery up.
“Fast charging is the key to increasing consumer confidence and overall adoption of electric vehicles,” Dufek told The Irish Times. “It would allow vehicle charging to be very similar to filling up at a gas station. We’ve significantly increased the amount of energy that can go into a battery cell in a short amount of time. Currently, we’re seeing batteries charge to over 90 per cent in 10 minutes without lithium plating or cathode cracking.”
Ten minutes to charge a battery is a heck of a lot better than the current best-case scenario, in which massively powerful 350kW chargers can get a battery from flat to 80 per cent in about 25 minutes (depending on the electric car in question). Ten minutes is only about five minutes more than the time you’d take to fill a tank of petrol or diesel, rather than five times that length. In this scenario, your EV could be charged to almost full before you’ve even queued for a coffee.
Dufek says that one advantage of their machine-learning model is that it ties the protocols to the physics of what is actually happening in a battery. The researchers plan to use their model to develop even better methods and to help design new lithium-ion batteries that are optimised to undergo fast charging. Dufek says that the ultimate goal is for electric vehicles to be able to “tell” charging stations how to power up their specific batteries quickly and safely.
The research will be first presented this week at a conference of the American Chemical Society, an organisation set up by the US Congress to “advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people”.
