Only time will tell but I think the lithium iron phosphate cells will
displace nimh, so I am not to worried about the patents.
First of all the construction of the cells is very similar. The
materials and chemicals differ, but very similar.
Second, the LiFePo4 cell chemistry was designed to be cheaper. It should
be, but we have to wait for economies of scale to catch up.
Nickel is expensive, Cobalt is very expensive. Metallic Lithium is
expensive, but the LiFePo4 is a starved Li-ion cell, not really that
much lithium in it.
I think when the cell is built there is no lithium in either the anode
or the cathode. The lithium-hexafluoride electrolyte has the lithium
ions and the commissioning charge causes the ions to migrate to the anode.
The iron,phosphate and graphite are relatively inexpensive.
Unlike the manufacturing of lithium cobalt, the binders are now aqueous
based and don't need an inert gas environment. The electrolyte is now
less reactive (and less carcynogenic)
The cost of materials and manufacturing is a fraction of lithium cobalt.
Again it is an economy of scale thing. with 4 LiFePo4 factories coming
on line this summer, we have about a year(ok, like any opinion, this
and $3.50 will get you a decent cup of coffee)
IC's needed for balancing were all geared towards lithium-cobalt so
balancing circuits have been more discrete and more expensive and rare,
that is changing too.