TESLA / WIRED

In April, Elon Musk stood before a crowd of investors at an invitation-only event at Tesla’s headquarters in Palo Alto. On stage, he made a series of wild predictions that might stretch the credulity of the most bullish Tesla fans. By the middle of 2020, he said, Tesla would have put one million 'Level 5' (completely autonomous) taxis in the hands of customers. Currently there are zero Level 5 cars on the road.

But another of Musk’s predictions might be on its way to becoming reality. At the Palo Alto event Musk promised that Tesla would soon make cars that could last for at least a million miles without requiring any significant maintenance. Now, a scientific paper published by Jeff Danh – an academic at the University of Dalhousie in Canada who also leads Tesla’s battery research group – suggests that Musk’s prediction may already be possible.


In a paper published in the Journal of the Electrochemical Society Dahn and his co-authors detailed tests of a new kind of battery that could drive more than a million miles and lose relatively little of its capacity. In ideal circumstances, the researchers suggest, the batteries could last for decades and be driven for a little under two million miles.

“We conclude that cells of this type should be able to power an electric vehicle for over 1.6 million kilometres (1 million miles) and last at least two decades in grid energy storage,” Dahn and his co-authors write. Such long-lasting batteries would be particularly useful for vehicles that travel much more than the average car – such as lorries and taxis – as well as feeding energy from car batteries back to the grid so electric vehicles, in effect, become mobile forms of energy storage. (Tesla did not respond to a request for comment for this story).

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This breakthrough – if it ever does come to production vehicles – would help more than just drivers of electric lorries, says David Bailey at the University of Birmingham's department of management. “If we can show drivers that actually this battery is going to last a million miles, the battery’s going to last longer than the car. You will take away a whole load of uncertainty so it will underpin pickup of electric cars anyway,” he says.

The focus in Dahn’s paper is firmly on haulage, robotic taxis and grid storage. According to the AAA Foundation for Traffic Safety Survey, the average American drives a little under 30 miles every day. A Tesla Model 3 has a range of upwards of 300 miles, depending on the exact model, meaning that a single charge would last the average driver more than a week.


But taxis and lorries are driven a lot more than commuter vehicles. Taxis – which are often shared between two or more drivers – can be driven all day long, racking up hundreds of miles every day. And all but the most short haul of lorry drivers are likely to deplete a 300-mile battery capacity in a single day.

It’s on this part of the market – vehicles with batteries that are depleted and recharged at least daily – that Dahn’s research paper is focused. He tested a new kind of lithium-ion battery pouch that contained graphite. Conventional batteries are usually cylindrical.

The study found that batteries kept at 20 degrees Celsius lost only four per cent of their capacity after being completely recharged 3,400 times over 2.25 years. Kept at full charge and stored at 20 degrees Celsius the batteries lost none of their capacity over 1.3 years. They performed slightly less well at higher temperatures, losing three per cent of their capacity when being stored for 1.3 years at 40 degrees Celsius.

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This would be particularly useful for vehicle-to-grid applications, where electric vehicles connected to the energy supply can drip-feed energy back to the grid when demand and energy prices are high, says Bailey. This would let electric vehicles charge up their vehicles when electricity is cheap – overnight, for example – and then sell any excess charge back to the grid during moments of peak demand.


And for Tesla, positioning itself at the forefront of battery technology is obviously a big business advantage. Tesla already sells batteries for renewable energy storage and the firm is currently building its third battery-producing “Gigafactory” in Shanghai, China, which will join the current facilities in New York and Nevada. At the moment, Tesla doesn’t actually make its own batteries – those made at factory in Nevada are made out of Panasonic cells – but with this latest research it could be taking tentative steps towards owning the entire battery-making process. According to a report in The Verge the supply of cells from Panasonic is the “fundamental constraint” holding Tesla back from producing more cars.

But no matter what happens in California or Canada, charging infrastructure will have to come on a long way if it’s going to take advantage of the next generation of batteries. In the UK, a lack of government investment has held back the roll out of charging infrastructure, making electric vehicles much less practical for drivers. “We’re lagging behind with really fast chargers,” he says. What good is a battery that can last a million miles if you can’t find a place to charge it?

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