Quote: Originally posted by Varungh  |
| Quote: Originally posted by MrDoctor | |
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. |
| Quote: Originally posted by bnull |
| Quote: Originally posted by Varungh |
| 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. |