Building a better battery requires dealing with problems in materials science, chemistry and manufacturing. We regularly cover work in progress in the previous two categories, but we receive a good number of complaints about our inability to deal with the third: finding out how companies manage to bring solutions to science and converting them into usable products. So it was exciting to see that a company called StoreDot, which was claiming the development of a battery that would allow a five-minute charge of electric vehicles, was apparently willing to speak to the press.
Unfortunately, the answer to our questions fell a little short of our hopes. “Thank you for your interest,” was the reply, “we are still in pure R&D mode and cannot share any information or answer any questions at the moment.” Apparently, the company gave The Guardian exclusivity and was not talking to anyone else.
Relentless, we have since removed all the information we found from the StoreDot website to find out more or less what they were doing and went back from there to look for research that we previously covered that could be related. What follows is an attempt to gather an image of technology and the challenges that a company has to face in order to take research concepts and make products with them.
The need for speed
To some extent, StoreDot is using ideas that have been floating around in research labs and startups for years, but is taking a little risk using these ideas in a way that is different from its apparent promise. The bet that StoreDot is making is that it is not the absolute load range of an electric vehicle that matters; is how quickly you can extend that reach. So while it is taking advantage of research on technologies that enable greater capacity in lithium-ion batteries, it is changing and sacrificing some of that capacity to make charging faster.
In other words, the bet is that people would rather add 300 km to their car’s range in five minutes than having a car with a range of 600 km that takes an hour to fully charge.
What are the implications of this bet at the hardware level? They are mainly dictated by heat management. As anyone who is connected to a low-charge laptop while sitting on their laps knows, charging a battery produces a lot of heat. Charging faster produces even more. To deal with this heat, StoreDot is essentially producing a diffuse battery with a lot of space between the individual cells, as you can see in the four-minute mark in this video (embedded below). The cells have significant gaps between them and the battery compartment has holes that allow air to flow between them. It is loaded on a stand with fans that force air through the battery to keep the heat in check.
Anyone could do this with existing battery technology, but there is a very obvious cost: a much lower energy density, which means that a battery has to be much larger to maintain the same amount of charge. StoreDot is paying off by working on technology that allows for a much higher load density, which compensates for the lower density of materials. In the end, the battery must maintain similar amounts of charge per volume as existing batteries, despite having less battery material present.