Yes - thats what I was thinking too. It is much better to call it a 35Ah cell (300 Wh/kg) cell.drees wrote:Is it really a 45Ah cell when it drops to 35Ah after a dozen cycles? That's nearly a 25% loss in capacity. Better to call it a 35Ah battery which is still impressive.
After 400-500 80% cycles it's down to 25Ah - 30% down from 35Ah and only about half of it's fresh capacity. By this point it's only nominally better than today's tech.
If they can get the anode to hold up better it'd be a lot more impressive.
This is what the Envision guy wrote in MT. I don't know enough about battery research to say whether his claim (that some more engr work will improve cycle life) is true or not.
Read more: http://blogs.motortrend.com/cost-cuttin ... z1nboBBen0" onclick="window.open(this.href);return false;Please note that the cells have cycled 400 times in our labs and are still cycling. Cells have also been sent to NSWC for cycle tests. The important thing is to first reach the energy density and then continue to improve cycle life. If cycle life was less then 20 cycles, one could make an argument that there is a science issue. At this point, having cycled over 400 times and still cycling – engineering work will be needed to increase cycle life.
Also note, number of cycles as cited in USABC manual for electric cars is a 1000 cycles. For a 300 mile car, if you cycle all the way 1000 times, you get 300 * 1000 = 300,000 miles.
I think even a 500 cycle, 80 kWh battery @300Wh/kg that comes in at $15k, 500 pounds of cells (close to Leaf battery) in 2015 will be very compelling to a large % of population. That will give about 250 miles of range when new. It will be 3 times better than the Leaf battery in terms of density.
Ofcourse, the cost isn't proven yet. But the cost is probably good because they aren't using expensive materials like Cobalt. Some Chinese manufacturers already offer cells in the $200/kWh range.