Battery Technology
How it Works
The ZBB EnerStore flow battery technology is based on the reaction between two commonly available chemicals, zinc and bromide. The ZBB EnerStore consists of a zinc negative electrode and a bromide positive electrode separated by a micro porous separator.
An aqueous solution of zinc/bromide is circulated through the two compartments of the cell from two separate reservoirs. The electrolyte stream in contact with the positive electrode contains bromide which is maintained at the desired concentration by equilibrating with a bromide storage medium.
The bromide storage medium is immiscible with an aqueous solution containing zinc bromide. All battery components are made from a bromide inert plastic.
ZBB EnerStore Flow Battery Chemistry - Watch Video
The ZBB EnerStore battery relies on a flowing electrolyte system:
- Chemical reaction takes place in the replaceable cell stack
- Electrolyte is stored in external tanks and circulated through the cell stacks
- The predominantly aqueous electrolyte is composed of zinc bromide salt dissolved in water
- During charge, metallic zinc is plated from the electrolyte solution onto the negative electrode surfaces in the cell stacks
- Bromide is converted to bromine at the positive electrode surface of the cell stack and is immediately stored as a safe, chemically complex organic phase in the electrolyte tank
- Each cell stack has 60 bi-polar electrodes between a pair of anode and cathode end blocks
- Operates quietly
- Operates at full output across a wide ambient temperature range
Unlike most batteries, ZBB EnerStore electrodes don't take part in the chemical reactions; they are simply substrates for the reactions. That means no loss of performance from repeated cycling that typically causes electrode material deterioration. When the ZBB EnerStore discharges, the metallic zinc plated on the negative electrodes dissolves in the electrolyte and is available to be plated again at the next charge cycle. In the fully discharged state, it can be left indefinitely.
The ZBB EnerStore flow battery is based on a 50 kWh module which incorporates all the hardware and software to operate as a complete energy storage system capable of being grid connected, or operating as a stand-alone unit. Modules can be linked to provide larger storage capacity.
The ZBB EnerStore module offers 2 to 3 times the energy density (75 to 85 watt-hours per kilogram) with associated size and weight savings over present lead/acid batteries. The power characteristics of the ZBB EnerStore can be modified, for selected applications. Therefore, the ZBB EnerStore has operational capabilities that make it extremely useful as a multi-purpose energy storage option.