9 ms·

Why are there no flow batteries with symmetric ferrocyanide electrolytes?

55 points by DamonHD 24d ago

theturtle 24d ago
[dead]
mshafir 24d ago
Thank you for this, as somebody with almost no background in chemistry, I can now appreciate just a bit more the complexity that goes into battery development. Where does one learn about this?
- SoftTalker 19d ago
  Do a degree in inorganic chemistry?
kakacik 24d ago
To give the answer its the cyanide part... which I knew already when looking at the title, without having much clue about underlying chemistry. Good luck selling batteries full of some variant of cyanide to general public, i can almost imagine it working till people hear that keyword.
- greenavocado 24d ago
  There are plenty of battery customers besides the usual suspects
- psd1 24d ago
  Somewhat true, but consumers are buying vast quantities of lithium batteries and carrying them in their pockets. Those things are eager to catch fire and emit hydrofluoric acid. You can have safe battery chemistry or useful battery chemistry. (Not an expert, open to correction.)
- somat 24d ago
  The public is not going to buy a flow battery anyway. Or perhaps they will, but only when public is taken in the context as in public utility or public city. But individuals are not going to buy a flow battery, it is a chemical plant.
  - SoftTalker 19d ago
    If we're going to do chemical-plant scale utility batteries, why not just lead-acid? It's well understood, simple, and the ingredients are cheap. Yes lead is toxic but it's easily contained and recyclable.
    - pjc50 18d ago
      I think the very fact that PbS and for that matter NiFe have been around for decades and aren't widely deployed for utility scale probably counts against it. I suspect the answer may be that weight matters enough just in the cost of delivery to the site. Where utility scale storage is being deployed it's lithium; may switch to sodium as that crosses over in cost.
- BenjiWiebe 24d ago
  Have to abbreviate it as FCN. Cyanide is ~320 times more toxic than ferrocyanide.
- jjk166 23d ago
  Yeah, just like no one would ever buy a lead-acid battery. I don't think many people are concerned about their batteries being safe for ingestion.
  - LoganDark 19d ago
    But toddlers could swallow it! Just like they swallow lead-acid batteries.
  - zamadatix 18d ago
    After all, people painted the walls and enhanced their gas with cyanide in large quantities for years before even realizing it had to be carefully handled so they are basically the same risk in the typical mind. The problem is free cyanide is extraordinarily dangerous in the air and you'd likely kill a lot of people before someone realized what was going on with the battery, not just that people eat batteries. Even lithium batteries honestly get pretty close to not being worth the risk for consumers, cyanide is still a bit of a step after that yet.
- fch42 19d ago
  Well they sell that liquid explosive terrorists use to make molotov cocktail firebombs, at every fuel station without particular volume limits at all. It's also sufficiently toxic that care is taken at salespoint to limit customer exposure to the vapours. (these things are "all relative, if the value, measured in "convenience to the customer", is high enough, ways will be found to permit sale)
  - SoftTalker 19d ago
    Vapor recovery requirements vary by locality. Where I live, none of the gas pumps have it.
    - fch42 18d ago
      well, if money were to be spent, in that case better build electrical charging infrastructure than upgrading the gas pumps ...
- jillesvangurp 19d ago
  That's pretty much what the article states: > When using ferrocyanide, also consider that while this salt is relatively safe in its unaltered state, subjecting it to electrochemical abuse WILL generate free cyanide and it’s likely to pose a significant danger to you and others. For this reason, I would recommend to stay away from testing ferrocyanides in symmetric systems entirely, unless you are a trained professional and professionally well equipped to handle both the potential operational hazards and wastes generated from its decomposition products.
ambicapter 24d ago
Glad I finally have a name (flow battery) for a concept that I've been wanting to be made for a long time (liquid batteries).
- tveita 24d ago
  You might find the home made batteries of this guy interesting as well https://www.youtube.com/watch?v=eq7fR9ISuCw https://www.youtube.com/watch?v=eq7fR9ISuCw
- sfn42 24d ago
  It's not a new idea, they already exist. A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-builds-worlds-most-powerful-redox-flow-battery/91181119 https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...
  - gilleain 24d ago
    A vanadium one, which (as mentioned in the piece) is symmetric. The 'Just Have a Think' channel did a video on the Swiss battery here - https://www.youtube.com/watch?v=CPAFeTvjVzY https://www.youtube.com/watch?v=CPAFeTvjVzY
    - pfdietz 19d ago
      The advantage of vanadium batteries, as I understand it, is that leakage does not corrupt the system. The vanadium gets converted to the right chemical species on either side.
  - meindnoch 19d ago
    "We will be able to inject or absorb up to 1.2 gigawatt-hours (GWh) of electricity in a few milliseconds" 1.2GWh in a few milliseconds? I'm pressing (X) to doubt.
    - colechristensen 19d ago
stuaxo 24d ago
Cyanide batteries... hmm..
- BenjiWiebe 24d ago
  *ferrocyanide Less toxic than cyanide. Potassium ferrocyanide: 1.6g/kg LD50 Potassium cyanide: 5mg/kg So cyanide is approx 320 times more toxic.
  - bastawhiz 19d ago
    Exactly. Table salt has an LD50 of 0.5-1g/kg, 1.5-3x more toxic. I weigh ~85kg, I'd have to eat about 46 cubic centimeters of potassium ferrocyanide (on the conservative side) to consume an LD50 worth. If you're talking about the chemicals in batteries we have today, the LD50 is probably way lower for most of them. If we're talking about batteries for consumer electronics, you'd have to eat (density wise) multiple batteries worth of potassium ferrocyanide to hit LD50.
- philipkglass 24d ago
  Ferrocyanide is not dangerous. Sodium ferrocyanide is used as an anti-caking agent in table salt. It's considered safe for this use in both the US and the EU, e.g.: https://ec.europa.eu/food/food-feed-portal/screen/food-additives/search/details/POL-FAD-IMPORT-3229 https://ec.europa.eu/food/food-feed-portal/screen/food-addit...
  - pjc50 19d ago
    Yes, but as the article points out, the process likes to evolve free cynanide in operation.
  - marcosdumay 19d ago
    Putting stuff in electric fields while thinking "well, it's stable" is a fool's errand. (As the article says...)
deleted 24d ago
[deleted]

55 points by DamonHD 24d ago

[dead]

Thank you for this, as somebody with almost no background in chemistry, I can now appreciate just a bit more the complexity that goes into battery development. Where does one learn about this?

SoftTalker 19d ago
Do a degree in inorganic chemistry?

kakacik 24d ago

To give the answer its the cyanide part... which I knew already when looking at the title, without having much clue about underlying chemistry. Good luck selling batteries full of some variant of cyanide to general public, i can almost imagine it working till people hear that keyword.

greenavocado 24d ago
There are plenty of battery customers besides the usual suspects
psd1 24d ago
Somewhat true, but consumers are buying vast quantities of lithium batteries and carrying them in their pockets. Those things are eager to catch fire and emit hydrofluoric acid. You can have safe battery chemistry or useful battery chemistry. (Not an expert, open to correction.)
somat 24d ago
The public is not going to buy a flow battery anyway. Or perhaps they will, but only when public is taken in the context as in public utility or public city. But individuals are not going to buy a flow battery, it is a chemical plant.
- SoftTalker 19d ago
  If we're going to do chemical-plant scale utility batteries, why not just lead-acid? It's well understood, simple, and the ingredients are cheap. Yes lead is toxic but it's easily contained and recyclable.
  - pjc50 18d ago
    I think the very fact that PbS and for that matter NiFe have been around for decades and aren't widely deployed for utility scale probably counts against it. I suspect the answer may be that weight matters enough just in the cost of delivery to the site. Where utility scale storage is being deployed it's lithium; may switch to sodium as that crosses over in cost.
BenjiWiebe 24d ago
Have to abbreviate it as FCN. Cyanide is ~320 times more toxic than ferrocyanide.
jjk166 23d ago
Yeah, just like no one would ever buy a lead-acid battery. I don't think many people are concerned about their batteries being safe for ingestion.
- LoganDark 19d ago
  But toddlers could swallow it! Just like they swallow lead-acid batteries.
- zamadatix 18d ago
  After all, people painted the walls and enhanced their gas with cyanide in large quantities for years before even realizing it had to be carefully handled so they are basically the same risk in the typical mind. The problem is free cyanide is extraordinarily dangerous in the air and you'd likely kill a lot of people before someone realized what was going on with the battery, not just that people eat batteries. Even lithium batteries honestly get pretty close to not being worth the risk for consumers, cyanide is still a bit of a step after that yet.
fch42 19d ago
Well they sell that liquid explosive terrorists use to make molotov cocktail firebombs, at every fuel station without particular volume limits at all. It's also sufficiently toxic that care is taken at salespoint to limit customer exposure to the vapours. (these things are "all relative, if the value, measured in "convenience to the customer", is high enough, ways will be found to permit sale)
- SoftTalker 19d ago
  Vapor recovery requirements vary by locality. Where I live, none of the gas pumps have it.
  - fch42 18d ago
    well, if money were to be spent, in that case better build electrical charging infrastructure than upgrading the gas pumps ...
jillesvangurp 19d ago
That's pretty much what the article states: > When using ferrocyanide, also consider that while this salt is relatively safe in its unaltered state, subjecting it to electrochemical abuse WILL generate free cyanide and it’s likely to pose a significant danger to you and others. For this reason, I would recommend to stay away from testing ferrocyanides in symmetric systems entirely, unless you are a trained professional and professionally well equipped to handle both the potential operational hazards and wastes generated from its decomposition products.

ambicapter 24d ago

Glad I finally have a name (flow battery) for a concept that I've been wanting to be made for a long time (liquid batteries).

tveita 24d ago
You might find the home made batteries of this guy interesting as well https://www.youtube.com/watch?v=eq7fR9ISuCw https://www.youtube.com/watch?v=eq7fR9ISuCw
sfn42 24d ago
It's not a new idea, they already exist. A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-builds-worlds-most-powerful-redox-flow-battery/91181119 https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...
- gilleain 24d ago
  A vanadium one, which (as mentioned in the piece) is symmetric. The 'Just Have a Think' channel did a video on the Swiss battery here - https://www.youtube.com/watch?v=CPAFeTvjVzY https://www.youtube.com/watch?v=CPAFeTvjVzY
  - pfdietz 19d ago
    The advantage of vanadium batteries, as I understand it, is that leakage does not corrupt the system. The vanadium gets converted to the right chemical species on either side.
- meindnoch 19d ago
  "We will be able to inject or absorb up to 1.2 gigawatt-hours (GWh) of electricity in a few milliseconds" 1.2GWh in a few milliseconds? I'm pressing (X) to doubt.
  - colechristensen 19d ago

stuaxo 24d ago

Cyanide batteries... hmm..

BenjiWiebe 24d ago
*ferrocyanide Less toxic than cyanide. Potassium ferrocyanide: 1.6g/kg LD50 Potassium cyanide: 5mg/kg So cyanide is approx 320 times more toxic.
- bastawhiz 19d ago
  Exactly. Table salt has an LD50 of 0.5-1g/kg, 1.5-3x more toxic. I weigh ~85kg, I'd have to eat about 46 cubic centimeters of potassium ferrocyanide (on the conservative side) to consume an LD50 worth. If you're talking about the chemicals in batteries we have today, the LD50 is probably way lower for most of them. If we're talking about batteries for consumer electronics, you'd have to eat (density wise) multiple batteries worth of potassium ferrocyanide to hit LD50.
philipkglass 24d ago
Ferrocyanide is not dangerous. Sodium ferrocyanide is used as an anti-caking agent in table salt. It's considered safe for this use in both the US and the EU, e.g.: https://ec.europa.eu/food/food-feed-portal/screen/food-additives/search/details/POL-FAD-IMPORT-3229 https://ec.europa.eu/food/food-feed-portal/screen/food-addit...
- pjc50 19d ago
  Yes, but as the article points out, the process likes to evolve free cynanide in operation.
- marcosdumay 19d ago
  Putting stuff in electric fields while thinking "well, it's stable" is a fool's errand. (As the article says...)

deleted 24d ago

[deleted]