Technologies
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ZnBr Batteries
Description:
In each cell of a ZnBr battery, two different electrolytes flow past carbon-plastic composite electrodes in two compartments separated by a microporous polyolefin membrane.
During discharge, Zn and Br combine into zinc bromide, generating 1.8 volts across each cell. This will increase the Zn2+ and Br- ion density in both electrolyte tanks. During charge, metallic zinc will be deposited (plated) as a thin film on one side of the carbon-plastic composite electrode. Meanwhile, bromine evolves as a dilute solution on the other side of the membrane, reacting with other agents (organic amines) to make thick bromine oil that sinks down to the bottom of the electrolytic tank. It is allowed to mix with the rest of the electrolyte during discharge. The net efficiency of this battery is about 75%.
Deployment Status:
The ZnBr battery was developed by Exxon in the early 1970’s.
Integrated ZnBr energy storage systems are now available in a range if sizes:
- On transportable trailers (storage systems including power electronics) with unit capacities of up to 1MW/3MWh for utility-scale applications. As a building block, these units can be paralleled and expanded for much larger applications
- As 5kW/20kWh Community Energy Storage (CES)
systems that are now being deployed by electricity utilities.
Developers / Suppliers:
ZBB Energy Corp
Premium Power Corporation
RedFlow Technologies Ltd