Cobalt is essential for stopping the battery from overheating and the stability it brings to the battery materials also allows users to charge and discharge their car over many years. But it is also the most expensive of the metals used — hindering the ability of carmakers to lower the cost of electric cars to compete against their petrol counterparts.
Analysts at Liberum, the London-based brokerage and investment bank, estimate that the cost of cobalt in a kilogram of battery cathode material is about $12, compared with $8 for lithium and $5 for nickel. Metals account for about 25 percent of the battery cost, they estimate. While new sources of cobalt are being developed in Idaho, Alaska and Australia, they are not due to produce metal until after 2020.
Mr. Zimmerman, a materials scientist, started to look at a relatively unexplored area of research — the electrolyte, which is generally what catches fire in batteries. If a solid material instead of a liquid were used, so the theory goes, the batteries could be safer and lighter. It could also allow carmakers to reduce the amount of cobalt in the cathode or even, he says, eliminate it entirely.
The first electrically conductive solid was discovered in the 1830s by British scientist Michael Faraday but it had never worked in a battery at room temperature. Working in his basement Mr. Zimmerman created a polymer material that could do just that.
"It was a really ugly piece of plastic in a roll with little pinholes in it everywhere, but you had to say 'wow'," recalls Mr. Joy, who was searching for a solid state battery technology while at venture capital firm Kleiner Perkins. "This is just amazing that it demonstrated feasibility of a property that had been sought for so long."
Carmakers from Toyota to Mercedes-Benz and the British engineering group Dyson are working on so-called solid state batteries like Mr. Zimmerman's and there were about $400m of investments in the technology in the first half of the year, according to consultancy Wood Mackenzie. They forecast that such batteries will make up the majority of electric car technology by 2030 but will not enter the market until 2025.
"There are still a number of challenging problems in order for an all solid state battery to be a commercially viable proposition," says Peter Bruce, a professor in the department of materials at Oxford university. "But they are now being addressed."
Ionic is one of a number of start-ups hoping to commercialize the next battery breakthrough. It is a field that has seen its fair share of failures, such as the bankruptcy of Pittsburgh-based saltwater battery company Aquion Energy, which raised money from Bill Gates and Kleiner Perkins, in March last year.
In the meantime, battery companies are racing to reduce the amount of cobalt they use with conventional technology. Yoshio Ito, the head of Panasonic's automotive business, which supplies Tesla, told reporters in Tokyo last month that it aims to decrease the use of cobalt in Tesla's EVs in two to three years. Tesla has said the company was "aiming to achieve close to zero usage of cobalt in the near future".
Most carmakers are moving towards batteries that use more nickel and as much as 75 percent less cobalt. These products are expected to pick up market share over the next few years.
Venkat Viswanathan, a professor at Carnegie Mellon University, says cobalt can be reduced using liquid electrolyte chemistries. "Ionic Materials is one pathway to making low cobalt cathodes but a liquid electrolyte pathway is also something that many battery makers are working on and have feasible solutions," he says.
Yet, even with a shift to lower cobalt batteries, demand for the metal is still expected to more than double by 2025, according to Wood Mackenzie. "Zero cobalt is hard, low is possible, [but] zero is very tricky at this point," Mr. Viswanathan says.
For his part, Mr. Zimmerman says the low-cobalt batteries still come with a considerable fire risk that will require expensive monitoring technology.
In his small study he plays videos on his laptop of nails going into the latest low-cobalt cathodes with liquid electrolytes, which he calls the "nail penetration test". There's smoke, fire and "bad things about to happen", he says, as we watch the cells catch fire in a metal chamber. In such fires toxic gases are produced that require fire crews to wear specialist clothes. "It's just fundamentally unsafe," he says.
"The cobalt is expensive — and it gets mined from unethical sources in the Congo, so people want to put less cobalt in," Mr. Zimmerman adds. "When you put less cobalt in, the voltage of the cathode goes up and the current liquid electrolytes can't work at that higher voltage. But our polymer can."
Ionic says it has tested its polymer material with cathodes that have either little cobalt or none at all and is working with companies to commercialize the technology. If successful, it says it could find its way into batteries within a few years and into electric cars after that.
Mr. Joy, who co-founded Sun Microsystems and wrote some of the founding code of the internet, says such technologies are critical to addressing climate change. The current mix of materials has been "stretched to the limit", he says.
"What happened with Sony inventing the lithium-ion . . . well, we ended up with things that get rechargeability," he says. "But they gave up . . . not only safety and cost but also abundance because there isn't physically enough cobalt to electrify the world."
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