I have been looking at the recently issued US patent 7466536 for a radical "battery" design from EEstor. In summary, the "battery" is actually an array of 31353 physically small capacitors of 980uF at 3500 volts making a total of 30.693 Farads and capable of storing 52.22 KWh of energy in a package weighing 128 Kg.
All the numbers add up, but look a bit calculated. Assuming it actually exists, there seem to be a number of practical problems for any automotive environment, including safety concerns.
On this note, the patent document says, somewhat disingenuously I feel:
" None of the EESU materials used to fabricate the EESU, which are aluminum, aluminum oxide, copper, composition-modified barium titanate powder, silver-filled epoxy, and poly(ethylene terephthalate) plastic will explode when being recharged or impacted. Thus the EESU is a safe product when used in electric vehicles, buses, bicycles, tractors, or any device that is used for transportation or to perform work, portable tools of all kinds, portable computers, or any device or system that requires electrical energy storage. "
Well, um!
I am not at all sure that I would like the consequences of a shorted "battery" dumping 50 KWh into a plasma. This is not likely to be a peaceful event, and I suspect it could be similar to detonating a few pounds of TNT.
As the invention claims the possibility of charging the "battery" in 3 minutes or less (about 300A at 3.5KV) the battery resistance would have to be very low if it is not to be cooked on recharge, and this would indicate the possibility of a high intensity discharge. How could safety of recharge by the unskilled be guaranteed?
Notwithstanding all that, I think that this is a very interesting development that it will pay to follow.
All the best Ian Macmillan