I need the information to determine if its worth to buy NiFe versus Lead Acid with 15 to 20 Years life and NOT deep discharge but maybe 30 % maximum.
That is not a like-for-like comparison. According to the literature, you could accept 60% deep discharge (or more) on your equivalent NiFe, and so possibly save 50% (or more) of your capacity. So if 1kWh of storage in NiFe costs half again what 1kWh of storage costs in Lead-Acid, you might still win on price.
Someone's alreadly linked "BeUtilityFree": I suspect their manufacturer
is these folks:-
http://www.solar3000.com/inverter_battery.htm
It seems likely that the Chinese price is cheaper than the American one, since one of them is adding a markup and the other isn't. But I don't know the story, since I don't have a price for the Chinese manufacturer.
The problem is the nickel electrode surface area that has to be increased dramatically and the way they were made by Edison implied a lot of chemical work, electrolysis and more chemical work to make flakes that looked like the feathers of a bird in a semicircle size ( if I remember right).
Absolutely correct. Edison nickel-plated copper, then etched away the copper to leave flakes of nickel. These were pressed into the nickel hydroxide to increase conductivity.
incrementing the surface area more than 100 times (?), I do not know how the Chinese are doing them now.
They'll be using standard pocket plate technology -- which wasn't known in Edison's time. The nickel electrode of a nickel-iron battery is absolutely identical to that of a nickel-cadmium battery.
Because nickel-cadmium and nickel-metal-hydride batteries use identical chemistry (and construction) for the nickel electrode, the nickel electrodes of modern storage batteries have advanced nearly a century since Edison's time.
Some modern researchers are using other techniques -- for example, NASA are electroplating grains of nickel hydroxide with nickel before sintering the electrode, to increase the conductivity, and getting batteries where 90%+ of the electrolyte undergoes chemical conversion in charge and discharge. A battery like that is interesting, because its performance in terms of kWh/kg and kWh/litre would far exceed modern lithium cells. To an EV-curious person like me, that is interesting, to say the least.
Electrolyte is critical ( KOH + LIthium) and needs to be protected from Oxygen for the electrolyte to last -- though it may need to be replaced about every 12 to 18 years.
It has to be protected from carbon dioxide, not oxygen. Oxygen is generated in the cell as part of the normal process of charging, when the endpoint is reached.
Carbon dioxide reacts with potassium hydroxide to produce potassium carbonate:-
KOH + CO2 -> K2CO3.
The potassium carbonate is no good as an electrolyte, since it doesn't donate hydroxyl ions. It is the transport of hydroxyl ions from one electrode to the other that stores and carries the charge, so obviously that is vital to the operation.
Nickel-cadmium minature batteries for high power apps use sodium hydroxide in solution, because it is more consistent at higher temperatures. So sodium hydroxide works. The metal ions in the electrolyte do not participate in the reaction, so as long as the concentration of hydroxyl ions is the same, the metal providing the hydroxide is not critical.
I believe that the KOH/LiOH combination is supposed to be better with very long term electrode life, but I've not found enough research online to suggest why this might be -- or even if it's true.
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