Why are there no flow batteries with symmetric ferrocyanide electrolytes?

Ferrocyanide is a highly stable and soluble redox couple widely used in asymmetric flow batteries, but symmetric systems (where both electrodes start with the same electrolyte) are not viable because ferrocyanide decomposes at both reducing potentials (below -0.5V) and oxidizing potentials, releasing toxic free cyanide and iron metal. The compound's instability when exposed to potentials beyond ±1V from its redox potential makes it unsuitable for creating economically viable symmetric flow batteries.