Not So Secret Anymore
EEStor has been playing the reverse psychology trick on most of us; the less they tell us about their supposedly revolutionary EESU (electrical energy storage unit) based on ultracapacitors, the more we want to know about it. But recently, part of the veil has been lifted when the company was granted a fairly detailed patent. Read on for more.
An Idea of What To Expect
on December 16th EEStor was granted a US patent for their EESU. The patent is a highly information-rich document that give a remarkable insight into these potential devices. EEStor notes "the present invention provides a unique lightweight electric-energy storage unit that has the capability to store ultrahigh amounts of energy".
The core ingredient is an aluminum coated barium titanate powder immersed in a polyethylene terephthalate plastic matrix. The EESU is composed of 31,353 of these components arranged in parallel. It is said to have a total capacitance of 30.693 F and can hold 52.220 kWh of energy. The device is said to have a weight of 281.56 pound including the box and all hardware. Unlike lithium-ion cells, the technology is said not to degrade with cycling and thus has a functionally unlimited lifetime.
If that's correct, that's very impressive.
The Tesla Roadster's li-ion battery pack holds around 53kwh, but to prolong battery life, a certain portion of the battery is never completely discharged. This would mean that functionally, more power would be available.
Also, the Tesla's battery weights almost a thousand pounds, so the EEStor device would be more than three times lighter (making the vehicle use less energy to move the battery around). It could also probably be charged faster if enough current is available.
Tesla battery pack.
Very promising indeed, though the main difference between it and the Tesla's battery is that we know that the Tesla battery exists and works, while the EEStor's EESU is still vaporware as far as we know.
Still, as we've said before, we'd love to see ultracapacitors and hypercapacitors leapfrog batteries and bring electric cars closer to commercial reality. Maybe it will be a combination of the two technologies that will end up winning this technological race (f.ex. Use hypercapacitors for the first 15-20 miles, and batteries after that, that way you put a lot fewer cycles on the batteries, extending its life considerably)? The future will tell.
The EEStor patent can be found here (PDF).
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