Quinone-based batteries could reduce need for metals, but project costs are high
By Cosmin Laslau and Steven Minnihan
The stationary energy storage market needs lower battery costs to reach a market of $6.5 billion in 2020.
Developers have been pursuing flow batteries as one possible way to lower these costs. This type of battery pumps two liquid electrolytes of different oxidation states across the sides of a proton exchange membrane, and chemistries vary - they include vanadium-redox flow batteries, zinc-bromine, iron-chromium, and zinc-chloride. Harvard University researchers are now pursuing a metal-free flow battery chemistry, based on small organic molecules called quinones.
The team claims the quinones are abundant and safer because they are dispersed in a water solvent and have tested the battery to about 100 cycles.
The quinone-battery design has some fundamental limitations to overcome: its large molecules and low voltages may lead to low energy density and low power density. While in theory that may not be a limitation since the developer can build bigger tanks of flow material to increase energy and use larger-area membranes to increase power, there will be practical constraints. In any instance where the battery is sited on a customer’s property or in a suburban distribution substation, there will be a real cost attached to the footprint. This increased land cost will certainly eat into (and maybe even erase) whatever cost advantage the cheaper quinone active material might have.