Varungh
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Making a Mangnese redox battery
I wss buying Mangnese sulfate for making MnO2 beta annodes(post coming soon) and i wondered if i couild make a redox battery
MnSO4 is in +2 state and when i apply a current,at annode it will be oxidised to +4 MnO2.
At cathode mettalic Mangnese will be formed.
During discharge MnO2 will dissolve as MnSO4 and Mn as MnSO4 too.this should in THEORY make a electric current.
Main problems seem to be the Mn oxisiding to MnSO4 on its own if left for a day or 2 and bad plating of Mn metal.
Also i suppose a whole lot of water will escape as H2 making this inefficient and MnO2 growth disproportionately high compared to Mn.
Seems like a good project to try.i will be waiting for my order.
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Varungh
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I was unable to acquire MnO2. As such I will have to use mangnese chloride route.
Mangnese dioxide is extracted from batteries and is washed
Then it is put in HCl SOln. Exact conc doesn't matter much. I used 12%HCl
MnO2+4HCl->MnCl2+2H2O+Cl2
CHLORINE GAS IS EVOLVED. THE WORKPLACE SHOULD BE VENTILATED.
The MnCl2 is filtered to remove unreacted MnO2 and carbon impurities
The MnCl2 is treated with NaOH to make Mangnese hydroxide. Na2CO3 can be used instead to make its carbonate salt
The mangnese hydroxide is mixed with sulfuric acid. Mangnese sulfate is produced.
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Varungh
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The cell itself is a old coffee bottle made of glass.
2 Carbon rods are taken and put in solution. A potential of 2V is applied
A MnO2 coat forms on the annode. Suprisingly, only little mangnese was deposited.
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Sulaiman
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I think that manganese dioxide is a very poor conductor of electricity
so your cell will have a very high internal resistance.
A zinc:carbon battery is actuallly a zinc manganese dioxide battery
and the manganese dioxide is mixed with carbon powder for conductivity.
A lead:acid battery works because lead dioxide is conductive.
CAUTION : Hobby Chemist, not Professional or even Amateur
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MrDoctor
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Quote: Originally posted by Varungh  | I was unable to acquire MnO2. As such I will have to use mangnese chloride route.
Mangnese dioxide is extracted from batteries and is washed
Then it is put in HCl SOln. Exact conc doesn't matter much. I used 12%HCl
MnO2+4HCl->MnCl2+2H2O+Cl2
CHLORINE GAS IS EVOLVED. THE WORKPLACE SHOULD BE VENTILATED.
The MnCl2 is filtered to remove unreacted MnO2 and carbon impurities
The MnCl2 is treated with NaOH to make Mangnese hydroxide. Na2CO3 can be used instead to make its carbonate salt
The mangnese hydroxide is mixed with sulfuric acid. Mangnese sulfate is produced. |
nurdrage did a video on this, its important that you watch it. there is a critical step, i dont recall off hand but at some stage you need to make the
oxalate salt to seperate the iron impurity that exists in all technical grade / battery / pottery store pigment manganese dioxide. Manganese and iron
otherwise have almost identical oxidation pathways and those salts tend to behave and react the same making them difficult to seperate, kind of how
nickle is also tricky to remove from iron fully, or vice versa.
The second one is, i think at the purified hydroxide stage, you need to cycle through a phase of boiling and chilling, as this will cause the
precipitated hydroxide crystals, which are an ultrafine silt, to seed crystal growth rather than just precipitating again when the saturated solution
is cooled. The purpose of that is to make your manganese sludge filterable. It might actually also be the oxalate this is done to, just watch the
video, i followed it through to sulfate no problem.
Lastly, manganese sulfate is sold as a standard, kind of specialty, fertilizer, for orchids or something, usually paired with zinc sulfate, its
incredibly easy to isolate from zinc using any common sense method including just electrolysis for the most part. zinc salts are also valuable/useful
for an assortment of chemistry, and electroplated zinc metal has many uses too. In australia its available as "Manutec Zinc & Manganese Soluble
Powder" the available elements listed will only add up to like 45-60% but thats just because these sulfates are present as the hydrate, so theres a
balance of water.
In the event you try something else, manganese should work in a flow cell design, and if nothing else id say its friendlier than iron, manganese
precipitates tend to be very fine and soft, and impellor type pump friendly. though zinc would also work there too if you include a brightening
additive, i think its called, so it plates evenly.
imo flow cell batteries are the future, you can store kilowatts of power in the form of an oxidized electrolyte, underground in something not unlike a
septic tank, your rate of input/output is largely just bottlenecked by how big the electrode/cell is, but the energy capacity itself is massive and
capable of sustaining a home with a well designed system. Iron flow cells just use pure iron as electrodes, or the purer the better, and in the event
the electrode is eaten away, assuming you cant just mig weld it yourself, it can be swapped for a piece of generic mild steel, or galvanized sheet
provided the zinc is stripped off. really flow cells have the same dilema as hydrogen fuel cells, its easy to store huge amounts (of kilowatts worth)
of gas, but the in/out rate is limited to the cell which is incredibly expensive, or at least the out is, where a seperate electrolyzer is used for
input.
meanwhile certain flow cells simply just dont last that long but are easily DIYd.
Lastly idk how useful this is but, if you take some graphite and rub it on a piece of etched titanium like you are coloring it with a lead pencil (i
dont think actual graphite pencils will work btw), then you calcine in an oxygen free environment at 500C which can be acheived more easily by just
sandwiching the plate between heaters, you get some sort of weird titanium-carbide graphene layer that demonstrates many of the ideal graphene
properties like a 1-molecule thick layer coating being a viable inert anode despite there being, really not even micrograms of carbon, the layer can
only be a single molecule thick, the outermost exposed titanium forms a carbide layer, but then the carbonds are also all linked somehow, preventing
corrosion in the same way that an uninterupted sheet of graphene is indestructible in the circumstances where it is. a good way to think of it is like
that new "PFC-free" non stick coating formulation where its just a single monoflurocarbon added to the end of a silicone-polymer chain to get the same
effects as an entire teflon coating, basically a mono-molecular coating too since its added like a coating to silicone. somehow that just works
sometimes.
Anyway these titanium electrodes can be used as anodes, they are said to be catalytically active in a manner useable for perchlorate production, and
overall are a perfect base for baking other protective oxides on like manganese, cobalt and lead.
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Varungh
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| Quote: Originally posted by MrDoctor | | Quote: Originally posted by Varungh | I was unable to acquire MnO2. As such I will have to use mangnese chloride route.
Mangnese dioxide is extracted from batteries and is washed
Then it is put in HCl SOln. Exact conc doesn't matter much. I used 12%HCl
MnO2+4HCl->MnCl2+2H2O+Cl2
CHLORINE GAS IS EVOLVED. THE WORKPLACE SHOULD BE VENTILATED.
The MnCl2 is filtered to remove unreacted MnO2 and carbon impurities
The MnCl2 is treated with NaOH to make Mangnese hydroxide. Na2CO3 can be used instead to make its carbonate salt
The mangnese hydroxide is mixed with sulfuric acid. Mangnese sulfate is produced. |
nurdrage did a video on this, its important that you watch it. there is a critical step, i dont recall off hand but at some stage you need to make the
oxalate salt to seperate the iron impurity that exists in all technical grade / battery / pottery store pigment manganese dioxide. Manganese and iron
otherwise have almost identical oxidation pathways and those salts tend to behave and react the same making them difficult to seperate, kind of how
nickle is also tricky to remove from iron fully, or vice versa.
The second one is, i think at the purified hydroxide stage, you need to cycle through a phase of boiling and chilling, as this will cause the
precipitated hydroxide crystals, which are an ultrafine silt, to seed crystal growth rather than just precipitating again when the saturated solution
is cooled. The purpose of that is to make your manganese sludge filterable. It might actually also be the oxalate this is done to, just watch the
video, i followed it through to sulfate no problem.
Lastly, manganese sulfate is sold as a standard, kind of specialty, fertilizer, for orchids or something, usually paired with zinc sulfate, its
incredibly easy to isolate from zinc using any common sense method including just electrolysis for the most part. zinc salts are also valuable/useful
for an assortment of chemistry, and electroplated zinc metal has many uses too. In australia its available as "Manutec Zinc & Manganese Soluble
Powder" the available elements listed will only add up to like 45-60% but thats just because these sulfates are present as the hydrate, so theres a
balance of water.
In the event you try something else, manganese should work in a flow cell design, and if nothing else id say its friendlier than iron, manganese
precipitates tend to be very fine and soft, and impellor type pump friendly. though zinc would also work there too if you include a brightening
additive, i think its called, so it plates evenly.
imo flow cell batteries are the future, you can store kilowatts of power in the form of an oxidized electrolyte, underground in something not unlike a
septic tank, your rate of input/output is largely just bottlenecked by how big the electrode/cell is, but the energy capacity itself is massive and
capable of sustaining a home with a well designed system. Iron flow cells just use pure iron as electrodes, or the purer the better, and in the event
the electrode is eaten away, assuming you cant just mig weld it yourself, it can be swapped for a piece of generic mild steel, or galvanized sheet
provided the zinc is stripped off. really flow cells have the same dilema as hydrogen fuel cells, its easy to store huge amounts (of kilowatts worth)
of gas, but the in/out rate is limited to the cell which is incredibly expensive, or at least the out is, where a seperate electrolyzer is used for
input.
meanwhile certain flow cells simply just dont last that long but are easily DIYd.
Lastly idk how useful this is but, if you take some graphite and rub it on a piece of etched titanium like you are coloring it with a lead pencil (i
dont think actual graphite pencils will work btw), then you calcine in an oxygen free environment at 500C which can be acheived more easily by just
sandwiching the plate between heaters, you get some sort of weird titanium-carbide graphene layer that demonstrates many of the ideal graphene
properties like a 1-molecule thick layer coating being a viable inert anode despite there being, really not even micrograms of carbon, the layer can
only be a single molecule thick, the outermost exposed titanium forms a carbide layer, but then the carbonds are also all linked somehow, preventing
corrosion in the same way that an uninterupted sheet of graphene is indestructible in the circumstances where it is. a good way to think of it is like
that new "PFC-free" non stick coating formulation where its just a single monoflurocarbon added to the end of a silicone-polymer chain to get the same
effects as an entire teflon coating, basically a mono-molecular coating too since its added like a coating to silicone. somehow that just works
sometimes.
Anyway these titanium electrodes can be used as anodes, they are said to be catalytically active in a manner useable for perchlorate production, and
overall are a perfect base for baking other protective oxides on like manganese, cobalt and lead. |
About the titanium you talked about, can I have more information on it. If it is as good you talk about,we may have a good annode on our hand. Also
Can it make persulfate, sulfuric acid, chlorate and nitric acid by diaphram electrolyser or a single cell electrolysis methods?
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MrDoctor
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I have glossed over it and realized something, i may either have talked it up, or, a second paper explaining how some ideal form of Ti-C is the bees
knees, followed by this one which then demonstrates a realistic way one can conceivably make said Ti-C at home, which together provide a pathway to
what i described.
I dont have the time to deeply re-read the whole thing so i must humbly concede that i may have talked it up a bit much earlier, or accidentally
committed speculation to memory as fact, but the fact the layer is mere microns should say, its stronger than graphite alone, microns of graphite will
vanish in a watthour or two.
Here is a link https://www.sciencedirect.com/science/article/pii/S223878542...
all i saw in the paper unless i missed it, was the use of the graphite as a priming agent to keep the electrode ready for subsequent deposition of
substances that normally could not be. Also seems i was wrong, pencils can be used, also the temp needed is 750C not 500C
I am still moderately confident that this substrate either is directly viable or at very least easily modified to/with graphene, to form a superior
MMO alternative, because that was the subject, not just because MMO is an excellent surface material to bind bulk secondary agents to like PbO2, but
in its useability. I distinctly recall the ease by which it splits hydrogen being raised and that it was somehow superior to either titanium or
graphite alone.
Anyway if i turned out to be wrong, i apologize. I cant find the conversation i had either, sadly. I recently got a benchtop kiln and this was
specifically one of the things i got it for too.
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Varungh
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Well then I sincerely hope the benchtop manages to accomplish what you intend. About PbO2 electrodes, isn't it made by oxidising lead to PbO2 in a
electrolytic cell containing H2SO4? What would be of such benefit to do such work?
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bnull
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Are you talking of redox battery as in "making a flow battery" or as in "making a battery that uses two different oxidation states of manganese in a
way that one species is reduced and the other is oxidized, hence redox"? I forgot to ask when you first posted.
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Varungh
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| Quote: Originally posted by bnull | | Are you talking of redox battery as in "making a flow battery" or as in "making a battery that uses two different oxidation states of manganese in a
way that one species is reduced and the other is oxidized, hence redox"? I forgot to ask when you first posted. |
Redox as in using 2 oxidation states. Mn metal and MnO2.
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Varungh
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I have hit 3 issues with the battery namely
The mangnese deposit barely forms. This is because competing H2 evolution likes to destroy my battery. Needless to say, it has extremely long charging
times.
The MnO2 is not very conductive. When the battery is barely charged the thin layers work well, but thick layers and you may as well just use a zinc
cathode and MnO2 annode. This would be better but defeat the point of the battery.
A additional problem is extremely high self discharge. The battery discharges in 2-3 days by itself.
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bnull
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Then the second half of @MrDoctor's post is not adequate to your problem. You see, "redox battery" is another name for flow batteries, and your
battery is closer to a common Leclanché cell.
There is something you can do to improve your battery. Make manganese dioxide, grind it with graphite or some other conductive carbon powder, wet the
mix and cram it tight in a small porous bag. Then you stick a graphite electrode into it. Doing this you increase conductivity and surface area.
You may want to try another solvent, or an inert thickener for the electrolyte (use a paste of sodium sulfate, for example). If you slow down the
movement of the ions across the battery, I think that you may extend the charged state for a few days more. But I may be wrong again.
I made a small copper sulfate battery a few years ago. Copper and zinc electrodes, a filter paper separator, and a paste made from copper sulfate and
glycerol. Solubility was good enough to develop some voltage and a feeble current.
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Varungh
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| Quote: Originally posted by bnull |
Then the second half of @MrDoctor's post is not adequate to your problem. You see, "redox battery" is another name for flow batteries, and your
battery is closer to a common Leclanché cell.
There is something you can do to improve your battery. Make manganese dioxide, grind it with graphite or some other conductive carbon powder, wet the
mix and cram it tight in a small porous bag. Then you stick a graphite electrode into it. Doing this you increase conductivity and surface area.
You may want to try another solvent, or an inert thickener for the electrolyte (use a paste of sodium sulfate, for example). If you slow down the
movement of the ions across the battery, I think that you may extend the charged state for a few days more. But I may be wrong again.
I made a small copper sulfate battery a few years ago. Copper and zinc electrodes, a filter paper separator, and a paste made from copper sulfate and
glycerol. Solubility was good enough to develop some voltage and a feeble current. |
I don't think I will work on it any longer. It is not fit to be a battery considered how wasteful it is. Besides I am hitting a new problem -
precipitation of hydroxides.
As I electrolyze the solution chloride ions leave as chlorine. During discharge, the mangnese compounds cannot dissolve as there is no chloride.
Sulfate fixes this, if only I had it.
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