Redox flow batteries store energy in a different way from conventional electrochemical batteries. However, redox flow chemistry is not perfect either. Scientists are still tackling crossover in redox flow battery tanks, but they are getting there.
Comparing Conventional and Redox Flow Chemistries
Electrodes hold most of the active materials that store and release energy in conventional batteries. Whereas in a redox flow battery, the energy-storing chemicals are in large external tanks.
How Redox Flow Batteries Discharge and Recharge
Pumps move electrolyte liquids through tanks separated by membranes. Chemical redox reactions called oxidation and reduction occur as the battery discharges and recharges.This process converts chemical energy into electricity and back again.
Operators can increase energy storage by installing larger tanks and more electrolyte. They can increase power output too, by adding more cells. This flexibility makes flow batteries attractive for renewable energy storage and electrical grid support.
Please Describe the Main Types Of Flow Batteries
We have been watching as two flow battery types continue to gain acceptance:
- Vanadium redox flow batteries lead. They offer long service life and can withstand many cycles.
- Zinc-bromine flow batteries provide another successful commercial option, and they often cost less.
How Crossover Happens Between Redox Flow Tanks
We come to our thoughts about tackling crossover in redox flow batteries. A flow battery membrane is supposed to allow ONLY certain ions to flow between tanks.
But in practice, some active material DOES cross over into the opposite tank. This gradually reduces both capacity and efficiency. Engineers have tried to solve this by using thicker, more selective membranes, but that often reduces power output.
A Fresh New Idea to Prevent Material Crossover
Scientists at Hong Kong University of Science and Technology have taken a different approach. They adjusted the electrolyte compositions to make them more complimentary. This reduced unwanted ion movement across the membrane.
Their inspiration slashed capacity decay and efficiency loss by 75% in their laboratory. Their prototype flow battery discharged and recharged over 1,000 times too, using a thin, high-performance membrane.
The Way Forward For This Innovative Idea
Tackling crossover in redox flow batteries successfully this way, should make them more competitive for grid-scale energy storage. Sometimes , it seems, the simplest ideas work best!
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