>
>"Bret Cahill" aol.com> wrote in message news:539db221-8124-4397-8b8e-c89067ada782@2g2000hsn.googlegroups.com...

>> 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.