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.
A moderate improvement, similar to what we see with development of other battery types.
In contrast, the theoretical energy density of a Na-NiCl2 cell is 790 Wh/kg.
790 Wh/kg !!!! That is some 5-6 times higher than current best Li-ion's !!
ZEBRAs are made from very cheap materials : Nickel and NaCl (table salt) and a little bit of aluminum (at the basics).
So just imagine if we could make a ZEBRA that gets even HALF of its theoretical capacity !!
Combined with a reasonable power-density and good cycle lifetime, that would completely change (read 'solve') the economics of
battery driven vehicles.
It would open up a multi-billion dollar market ! Talking about incentives !
This brings up an interesting issue : Reducing the 'inactive' material in rechargeable batteries is an engineering task, and not a
task that requires scientific breakthroughs.
So, for future developments, I expect gradual improvement of existing battery types over time as engineers find more optimal ways to
make the chemistry work with less and less inactive material in the cell.
From an investment point of view, Lithium (metal) is probably the safest bet to invest in (or buy lithium carbonate futures if they
exist).
Once we start using Lithium for hybrids/PHEVs in large volume, the price of Lithium will likely go through the roof rather fast.
Even without Lithium cells used for hybrids, the world's 'easily harvested' Lithium supplies are pretty limited, and could even be
peaking pretty soon, and that is why I don't believe that large-scale use of Lithium-ion for electric drive vehicles is smart. But
as an investment it should be (pretty succesfull).
My 2 cts
Rob
