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Inventor of the graphite anode – key Li-ion battery tech – says he can now charge an electric car in 10 minutes

Morocco-born Dr Rachid Yazami has lived all over the world, thanks to an invention he made in his first year as a PhD student – the graphite anode – which is one of the key components that make lithium-ion batteries perform so well.

With electric vehicles on the rise, he believes the invention will soon take you everywhere, too.

Yazami’s story starts in the mid-1970s when scientists knew that graphite could help to form molten or powdered lithium into a usable energy storage material but struggled to turn it into a product. In 1983 Yazami and co-author Ph. Touzain cracked the problem by using a solid polymer electrolyte .

Their technique helped to make mass-manufactured Li-Ion batteries affordable, reliable, long-lived and possessing the power cycling stability that has made them ubiquitous.

The anode has since propelled Yazami to a globe-spanning career in France, California, Japan and now Singapore, where The Register caught up with him in the offices of his company, KVI near the National Technological University.

Professor Yazami said the anode “made me popular, but not rich.” It also gave him some bragging rights:

Pre-pandemic, the anode was estimated by Lux Research analysts to be worth 10 to 15 per cent of the total cost of a lithium-ion battery and the global anode material market was predicted to grow to $US10B by 2025.

These days, Yazami is chasing another breakthrough: fast-charging batteries. And he says his company is already breaking records:

Yazami said his company’s rapid charging tech works by using a new approach to getting current into a car.

“Traditionally, batteries have been charged by applying constant current, much in the way that one would fill up a gas tank, you put the nozzle in and start pumping,” he explained.

Yazami’s method instead uses “nonlinear voltammetry” that controls voltage instead of controlling the current.

As explained to The Register this involves thinking of voltage like steps on a ladder. Voltage must stay constant, essentially on one rung of the ladder, until parameters are met and it can move up to the next step, eventually reaching the top of the ladder with full charge. Yazami said this method gives batteries a rest during the charging process, changing how they respond.

“The speed a battery will charge depends on its resilience to take a charge,” said Yazami. “You have to make the battery happy.”

While a fast charge is convenient for a consumer, it is also important for the life of the battery and at the top of the list of things Yazami would like to improve for the future of lithium-ion batteries.

“The technology that enables fast charging also extends the life of the battery by avoiding stress. Instead of keeping your battery for five years, you can keep it for ten years, because the way we are charging the battery does not put it under high temperature or high current stress,” he said. His dream battery situation would be ten minutes of charge for a range of 800km.

The two other problems he sees with batteries are energy density — which can help a driver stay on the road longer — and safety.

”Energy density has been increasing since the inception of lithium-ion batteries in 1991, until 2015 or 2016 when it plateaued,” he said. “The increase before it plateaued was about 80 per cent a year.”

”To give you an idea, when Sony first launched a [Li-Ion] battery, it was about 90 watt hours per kilogram. We are now close to 270, which is three times that. Some of the lithium-ion batteries can provide 290 watt hour per kilogram. I have tested them in the lab — they are commercial batteries, they are already there.”

”The target is to go to 300. To my knowledge there is no 300 watt hour per kilogram on the market — not yet. There are some prototypes, but when you increase the energy density there are some problems with life and safety of battery.”

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Safety is also on Yazami’s mind, because Li-ion batteries can behave badly if they are punctured or stressed. Preliminary reports regarding a fatal crash of a 2019 Tesla Model S in Texas last month revealed that a fire started in the battery, which was damaged in the crash.

”We can’t prevent fire in extreme situations, but at least we can have signs before it happens,” the professor told The Register.

“We need a technology that is proactive many weeks or even one month in advance. A weak battery with a risk, you’ll know it as the end user. You can then choose to service the battery pack, or replace it, or not use it at all. That will increase the safety by three or four times.”

He went on to describe what this could like: a sensor on the battery that measures its size as the material expands with heat, and a display system that in turn alerts the driver.

“It’s like a seat belt – it is not a total prevention strategy,” said Yazami.

The scientist reckons EV battery technology will continue to extend beyond cars and scooters, and we will see the rise of electric airplanes – likely predominantly for individual use – in the next 20 to 30 years.

He also predicted Europe will grow from providing 3 per cent of battery manufacturing to 20 per cent, as the EU continues to increase the number of billion-dollar gigafactories.

“Currently the EV market is in the EU, and the manufacturing is in China,” said Yazami. “That’s a problem.” ®


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