Author Topic: DIY NiFe?  (Read 8313 times)

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JWSmythe

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DIY NiFe?
« on: March 09, 2015, 09:49:47 PM »
Does anyone have any advice on attempting to build NiFe batteries?   Well besides "don't".  :)   I'm going to build something.  I'd rather do it myself where I can rebuild it later, than having a large recurring bill.  I like the idea of the NiFe over lead acid for safety in building them.

I'm just going to dump a lot of info at once as I think of what I've found so far.   I just don't want to be pointed at "there's this guy who sells this thing that..."   This seemed like the better place for info in searching.

I read through Bill Blake's comments in other threads.  Thanks Bill!   His posts are the ones I found via Google.   I've also seen a lot of other stuff, and a lot of questionable claims.   

The ChangHong documentation on theirs says they use "nickel [II] hydroxide and graphite" for the positive plate; "ferroferric oxide" for the negative plate; both in plates made of "perforated steel strips"; "KOH aqueous solution with a little LiOH" for the electrolyte.   The electrolyte is later defined as KOH 240~270g/L, and 20g LiOH, but they don't specify if the LiOH is per liter or not.

Reading through what have about the Edison battery is enough to give anyone a headache.   There's enough conflicting information out there, where the plates may be a squirrel and a goldfish.   

So far the running theme is:   

Positive: Nickel (electroplate), NiO, Ni2O3,  BaNiO3.
Negative: Iron (plate or powder), FeO, Fe2O3, Fe3O4, Fe(OH)2

And various electrolytes.

Some say solid plates.  Some say flakes or powder in something (like ChangHong's "perforated steel strips").   Of course, nobody defines "steel", so I don't have a clue about carbon content, or even if they're talking about another alloy like stainless steel.

Here's my initial thoughts on it, that I would try first if I started experimenting today. 

Packed powdered Ni2O3 and FeO in plastic tubes with open tops, and carbon rods down the middle of the tubes for conductivity.  Electrolyte covering all the powder and above the tops of the tubes.  First test would be with just water as an electrolyte, then various mixes of whatever.

If that was successful, expand that out to plastic plates, like 3x4x0.25" filled the same way.  Only one electrode per plate should be necessary, I think.

That's not to build anything that would be production, it would just be experimenting with single 2 plate cells.

Opinions?

If it's not practical, then I'll just punt to making lead acid batteries.  I can just cast plates, make housings, and assemble them myself.   I just think the NiFe battery sounds more practical.


joestue

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Re: DIY NiFe?
« Reply #1 on: March 10, 2015, 12:41:09 AM »
far as i know most of the cost of traditional cells is labour.

LA cells have been made in a not so long lasting form because straight from the factory they can deliver high AH without cycling the cells much.
some/most AGM battery datasheets show the capacity increasing for the first 10-100 cycles, then decreasing as the battery $#|+s itself.
an additional issue is the antimony is too expensive so everyone switched to calcium instead.

for nickel iron cells.. you're dealing with half the volts and more ohms for impedance, is the life cycle cost worth it really? i can't answer that but i'm thinking.. no, go with lithium iron phosphate instead.
I think, provided you can duplicate the process and get the chemistry right, that you can make your own cells quite easily, but that nickel two trioxide is going to cost you.. if however, if cycling the cell you can convert other nickel oxide(s) into the right material.. i think this will work
but it will probably be a two step process.
cycle the plates, then press them again.

given the chemistry, i would think adding lithium hydroxide is only for the purpose of reducing the resistance only.
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richhagen

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Re: DIY NiFe?
« Reply #2 on: March 11, 2015, 04:51:06 PM »
I would not tell you 'don't', I think the technology is reasonably well documented.  There is a Google book available on line outlining Edison's process and technology.  He used nickle plated perforated steel tubes to hold the nickle hydroxide and pocket plates in the end for the ferric oxide pole.  I think he started with tubes on the iron side, but the difference in volume for charged and depleted cells on the iron side was large enough to cause tube designs problems over time.  Just bear in mind that nickle salts have environmental and therefore waste disposal problems.  Not that you would want to be losing them to the environment anyway.  I have read of projects where people have made working batteries in jars with filter bags that could withstand the hydroxide electrolytes used in these to hold the reactants mixed with nickel wool with nickle or nickel plated rods to get the current out of these home built batteries.  The bags of polypropylene fabric or some similar just have to be porous to allow for ion mobility and electrically insulating to keep the reactants out of direct electrical contact except via the electrolyte.  As for the electrolyte KOH conducts a bit better than NaOH, and the KOH is often mixed with a bit of lithium hydroxide in commercial battery electrolyte formulations.  If you can't get lithium hydroxide, an AA size energizer ultimate lithium battery can be 'carefully' disassembled to reveal a thin sheet of lithium metal that will react readily with distilled water to form the hydroxide salt.   Please post anything that you do build.  Rich
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richhagen

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Re: DIY NiFe?
« Reply #3 on: March 11, 2015, 05:11:32 PM »
A couple of more thoughts.  your ability to store energy in such a battery is dependent upon the mass of the nickel and iron salts.  I do not think you are going to make a very useful battery from just the thin layers forming on metal plates.  I would not use stainless steel, I would use an alloy composed of as pure of iron, or iron and carbon as possible.  Other metals and elements present will only likely serve to interfere with or poison the reaction you are trying to foster.  Nickel plated steel is what is used to hold the reactants in commercial batteries.  Edison had a special process for plating and then baking the steel to protect it in his batteries.  Metalic nickel might form a very thin layer of hydroxide over time on its surface, but is generally nonreactive in the battery at the operating voltages of the battery, which is why Edison used it.  He did not want the framework holding the batteries active components, namely the iron and nickel compounds to fall apart over time ruining the battery.  Also, a working battery will have provisions to allow for gas products produced, namely hydrogen and oxygen, to escape, without allowing of entry of atmospheric air which would contain carbon dioxide which would neutralize the electrolytes over time decreasing the performance of the cell over time.  For a homebrew design perhaps fermentation caps could work, if there is small enough head space for gases such that decreases in temperature experience by the battery do not cause atmospheric gases to be drawn back into the battery backwards through the trap.

You end up with a battery that is generally less energy efficient than a lead acid, in terms of how much energy you put in vs. how much you get back out, although the life expectancy could be a multiple of that of a lead acid battery if it is well designed.  Whether this tradeoff is worth it depends upon your perspective and usage. 
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JWSmythe

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Re: DIY NiFe?
« Reply #4 on: March 11, 2015, 06:23:38 PM »
joestue,  With just some quick reading, I think LiFePO4 may be too difficult to do myself.    I like the relative simplicity of NiFe or Lead acid. 

JWSmythe

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Re: DIY NiFe?
« Reply #5 on: March 11, 2015, 07:02:35 PM »
...  I do not think you are going to make a very useful battery from just the thin layers forming on metal plates. ...

I agree.  I only mentioned plating, because a lot of the information I found talked about people trying it with plating.   They usually said something about the base material being very undesirable to have exposed to the electrolyte.   That may work ok in tests, but I could foresee it failing horribly in the long term.

I would not use stainless steel, I would use an alloy composed of as pure of iron, or iron and carbon as possible.

Ya, I'll try to stay as inert as I can.  I had a lot of success with carbon/graphite plates and rods on another project.  Repeated motion was the only real drawback on that, leaving conductive residue in the bottom of the box.  Since these are intended to stay stationary, that won't be a problem.

Also, a working battery will have provisions to allow for gas products produced,


Yes, I did consider that too.   Here, there's a good chance of salts from the water, pollen, etc, etc.   If they go from testing to construction, they'll have one-way valves of some sort.   I didn't think of fermentation caps, that would probably work.  In my head, it was just going to be a tube with a rubber flap.  The whole thing will live in a well vented shed so I don't have those pesky exploding problems.

You end up with a battery that is generally less energy efficient than a lead acid, in terms of how much energy you put in vs. how much you get back out, although the life expectancy...


My main consideration will be, can I build and maintain my own for cheaper than buying and replacing at intervals.   Even if I have to build twice as many NiFe batteries, that's ok.   If it would take up so much space it's not reasonable, then I'm doing something wrong.

Thanks for your input.  And yes, I will post if/when I have something worth showing. :)

Harold in CR

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Re: DIY NiFe?
« Reply #6 on: April 05, 2015, 07:48:35 AM »

 I followed a you tube channel from "Edsworkshop". He made NiFe ?? squares using a press and was going to do 5 gallon sized cells, but, somehow, I lost track of him. The main thing I remember was, he was very specific about what steel wool he used. He stated emphatically, that all steel wool is not the same.

 Maybe you could do a search. It was a series of videos.