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Not much recent research/development has been aimed at improving Edison's original design of Nickel-Iron batteries, but with a few minor tweaks they'd make pretty good laptop, and other low-power application, batteries.
- they last forever and are impossible to damage.
- totally non-poisonous and
easily recycleable materials should they ever need to be recycled.
- 70% throughput rate is low compared to a new Lithium battery (NiFe have approximately the same specs as Lead Acid batteries in that respect), but laptops haven't got very large power requirements: the wasted power is easily written off against the lifespan.
The only caveat is that, being composed of wet cells, they'd have to be equipped with a level-sensor to ensure that they're only charged in the upright position (to allow the occasional bit of H2 to escape), and even then there are catalytic caps on the market to put the H2 back into solution as water.
(bit of a problem finding a comparison of volumetric energy-density for different battery types right this minute)
Pictures of digits
http://www.flickr.c...ups/numerical/pool/
[mouseposture, Oct 15 2010]
(?) "Nickel Iron batteries last forever?"
http://www.thejoojo...b70-2.html?t=410085
Some other forum's discussion about NiFe batteries. [goldbb, Oct 17 2010]
maker
http://ironedison.com/
a maker of batteries [popbottle, Nov 07 2014]
maker
http://www.zappworks.com/
a maker of batteries [popbottle, Nov 07 2014]
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Isn't this just a new use for an old (but still used)
technology? |
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Meh,"poisoning'" was the operative word there,
anyway. |
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//laptops haven't got very large power requirements: // |
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Is that true? I thought laptops were fairly power-hungry. And
are you thinking of peak current drain or total usage time? If
it's the latter, then it's a quite crucial factor - battery life (I
mean, time available from a full charge, not the overall
lifespan of the battery) is never long enough, in my
experience. |
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Well, they don't have very large power requirements in the grand scheme of things. My mention of it was to point out that the efficiency difference would be balanced out by the lifetime. |
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I've just purchased an old laptop with a Li-ion battery rated at 10.8V and 3.8Ah (~40Wh) rated for 2 hours normal use, which (after 10 years) holds a total of 15 minutes charge, making it effectively useless as a portable*. Gonna look around later to get vol energy density (I don't think power density is a concern) to find the equivalent size compared to a modern Li battery. |
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//poisonous//
what you're thinking of is actually Nickel Carbonyl poisoning: not the same thing. |
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* the money went to charity. I don't really need a laptop so the charge retention problem is just enough of an annoyance to cause this post. |
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Who wants to look at pictures of digits? |
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//Who wants to look at pictures of digits?// <link> |
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based on slicing and dicing specs of a commercial product <link>, I end up with 4lbs for 40Wh (casing, electronics, etc. included) at maybe 3x the size of my comatose Li-ion battery. Not svelte... but not bad either for an effectively indestructible rechargeable battery. |
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//car batteries// the original electric cars used them... from a bit of reading it looks like lead-acid won out for use as normal vehicle batteries due to politics and built-in obsolescence. They're very much equivalent to lead-acid in specs, except for longevity and ruggedness where NiFe clearly wins out. |
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However, compared to Li based cells, the cycle efficiency is less, so I'm using the current, ridiculous paradigm of having to purchase an expensive, difficult to recycle, new laptop battery every 5 years or every time you buy a new laptop, to build a case for using NiFe tech. |
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With automobiles it's a little different: while usage as an ICE vehicle battery is definitely a good idea, in a fully electric vehicle weight becomes an issue for anything larger than a NEV (Neighbourhood Electric Vehicle). |
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two reasons the lead acid battery won the day: peak output and better voltage at low temperatures. my understanding is that the cold cranking output of a ni-fe was pretty abysmal, at least in the heyday of the automobile. |
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But I have to point out that during charging NiFe
batteries have a tendency to lose some more of
their water to electrolysis than many more
common battery types. |
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The obvious solution to this problem is to make
them vent when their internal pressure is high
enough, and provide a means to top them up with
distilled water. Partial loss of electrolyte due to
evaporation or electrolysis will do less damage to
NiFe batteries than to lead acid batteries. |
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The more elegant solution is one that allows the
battery to be permanently sealed. Include in each
cell a small catalyst which will recombine the
hydrogen and oxygen into water. |
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For lead acid batteries, such a catalyst is typically
incorporated into something called "catalyst
battery caps." The catalyst *must* be on the top
of the battery, since the acidic electrolyte would
destroy it if it were to make contact. |
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Since the electrolyte in a NiFe battery is KOH, a
strong base, it should won't react with and
destroy the catalyst. |
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If it's safe for the electrolyte and catalyst to make
contact, then the catalyst can be located
anywhere within the battery. |
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To maximize the surface area and minimize the
mass of catalyst used, it might be possible to
suspend micro- or nano- sized granules of it in the
electrolyte. |
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I do however have one other concern... the only
pictures of NiFe batteries I've seen are those by
BeUtilityFree, which are basically flooded
batteries. |
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For a portable application such as a laptop, I'd
want a battery which is unspillable (even if
broken) and usable in any orientation. |
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This would probably require that the electrolyte
be made into a paste, as in a dry cell. |
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While I don't think that this would be difficult, it's
not something that's been done before using
nickel iron batteries. |
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The container could be coated on the inside with platinum. |
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the platinum infusion idea of yours is post-, if not patent, worthy... sounds like the best, but how would you keep the platinum particles from settling out ? |
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