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deepmind.google·6d ago
AI Engineering
Hacker News·Sep 2·5 min read
Why are there no flow batteries with symmetric ferrocyanide electrolytes?
TL;DR
Ferrocyanide is a popular redox couple in flow batteries due to its stability and solubility, but its use in symmetric systems is hindered by decomposition issues and the formation of insoluble compounds. This limits the development of effective flow battery systems using ferrocyanide electrolytes.
✦ Why It Matters
Consider alternative redox couples for flow battery designs to avoid ferrocyanide's decomposition issues.
Key Takeaways
- Ferrocyanide is stable but unsuitable for symmetric flow batteries.
- Insoluble compounds form with heavy metals, complicating battery design.
- Decomposition at low potentials generates toxic cyanide.
- Safety risks necessitate professional handling of ferrocyanide.
Full Summary
Ferrocyanide and ferricyanide are widely recognized for their high redox stability and solubility, making them attractive for flow battery applications. However, there are no successful implementations of ferrocyanide in symmetric flow battery systems, where the same electrolyte is used on both sides.
The primary issue is that ferrocyanide can form insoluble compounds with heavy metals, complicating metal reduction processes. While methods exist to dissolve these compounds, ferrocyanide decomposes at low potentials, generating free cyanide, which poses safety risks.
Attempts to couple ferrocyanide with higher redox potential systems also lead to cyanide oxidation and further instability. Ultimately, ferrocyanide's behavior under extreme potentials makes it unsuitable for symmetric systems, limiting its economic viability and safety in practical applications.