"John Larkin"
highNOTlandTHIStechnologyPART.com> wrote in message news:brpma4trqvtb6qqoklm3qilsmei3uf37ea@4ax.com...> On Tue, 19 Aug 2008 16:45:47 -0700, "Rob Dekker"
verific.com>
> wrote:
>>>> Anyone knowledgeable on energy storage technology who gives advice on
>>> investing in, say, copper, might be wondering about future advances in
>>> battery technology.
>>>
>>> No one can predict names, dates or improvements but time-profiles of
>>> the most plausible developments may be useful.
>>>
>>> Fix cost/watt-hr and plot energy density vs time.
>>>
>>> or
>>>
>>> Fix efficiency and plot cost-watt-hr vs. time.
>>>
>>> or
>>>
>>> and so on.
>>>
>>>
>>> Bret Cahill
>>>
>>
>>There seem to be moderate improvements with some breakthroughs in all important aspects of rechargeable batteries : energy
>>density,
>>power density, (deep) cycle life, cycle efficiency, cost, safety etc. But it's nothing like what Moore's law does in
>>microelectronics.
>>
>>When thinking about future battery developments, one interesting fact stands out like a sore :
>>
>>The actual energy density obtained for packaged batteries today is FAR lower than the theoretical specific energy density !
>>
>>I've long scratched my head why that is. This site talks about that difference briefly :
>>
http://books.nap.edu/openbook.php?record_id=10595&page=24
>>
>>I can understand that container, electrode support, connectors, diluted electrolyte, unreacted materials etc would reduce the
>>capacity to 75%% or so of theoretical.
>>But it's much worse than that. Most types get only 15-25%% of their theoretical capacity !
>>
>>For example, molten salt Na-NiCl2 cells (ZEBRAs) used to be spec'ed at 90 Wh/kg, recently enhanced by MESA to 120 Wh/kg.
>
>
> I don't think I want to drive a car that's lugging around a hundred
> kilograms of liquid sodium at 300C or so. Or wait two days or so for
> it to warm up. Or wait a couple of hours to recharge it.
John,
My point was about battery development in general ; that engineering has a lot of room to play with until theoretical limits are
obtained in current cell chemistries.
Your comment is specifically on the Zebra, but seems rather uninformed.
But since you brought it up, here goes :
The Zebra has been tested by NREL and found to be safe under all fail conditions :
http://www.osti.gov/energycitations/servlets/purl/7101-0by8BY/native/7101.PDF
Regarding the liquid sodium : Noone (including NREL) has been able to rapture the cell and get liquid sodium out.
The explanation : the sodium will immediately react with the clorine ions when the cell is ruptured, creating....NaCl (table salt).
On warming up : Only needed if the battery cooled down all the way AND there is no auxilary power unit in the vehicle.
On recharge : Mostly 'recharge' is considered a benefit of batteries. Remember 'plug-in' ?
>
> It's admittedly a little more appealing than a sodium-sulphur battery.
>
Sodium-sulphur had serious safety issues, so I agree.
> Gasoline-powered cars work great, and don't need to be fixed. As the
> price of gas goes up, people will be discouraged from driving hideous
> beasts like Expeditions and Escalades and Ram trucks; fine by me.
Opinion.
>
> John
>
>
>
