Zinc-Bromine flow batteries are a type of rechargeable battery that uses zinc and bromine as the electrolytes to store and release electrical energy. In these batteries, zinc and bromine are stored in separate tanks and are pumped into a reactor cell when the battery needs to be charged.
During charging, the zinc ions in the electrolyte are oxidised at the anode to form zinc ions with a positive charge, which then flow through the reactor cell and react with the bromine ions at the cathode to form zinc bromide. This reaction releases electrons, which are then used to power an external circuit.
During discharge, the reaction is reversed, with the zinc ions flowing back to the anode and the bromine ions flowing back to the cathode. This releases energy that can be used to power a device or an electrical grid.
Advantages of Zinc–Bromine Flow Batteries
High energy density: Zinc-Bromine flow batteries have a high energy density, which means they can store a large amount of energy in a relatively small volume.
Long lifespan: Zinc-Bromine flow batteries have a longer lifespan than other types of batteries, which makes them a more cost-effective option in the long run.
Scalability: Zinc-Bromine flow batteries have a modular design that allows for easy scalability. They can be easily expanded by adding more batteries to the system as needed.
High efficiency: Zinc-Bromine flow batteries have a high efficiency rate, meaning they can convert a high percentage of the energy they store into usable electricity.
Environmentally friendly: Zinc-Bromine flow batteries are fully recyclable, with the ability to reuse up to 95% of their components. They are also free from toxic metals such as lead and cadmium.
Safe: Zinc-Bromine flow batteries are considered safe to use, as they do not produce flammable gases and do not pose a risk of explosion.
Disadvantages of Zinc–Bromine Flow Batteries
Cost: Zinc-Bromine flow batteries can be more expensive than other types of batteries, such as lead-acid batteries, which may make them less attractive for some applications.
Complexity: Zinc-Bromine flow batteries have a complex design and require more maintenance than other types of batteries, which can increase their overall cost of ownership.
Performance in cold temperatures: While Zinc-Bromine flow batteries can operate in a wide range of temperatures, they may have reduced performance in very cold temperatures, which can limit their use in certain environments.
Redflow Zinc-Bromine Batteries
Redflow is an Australian company that has been at the forefront of developing and manufacturing Zinc-Bromine flow batteries for the last decade. Since its founding in 2005, the company has focused on creating energy storage solutions that are both efficient and sustainable.
One of the key advantages of Redflow's Zinc-Bromine flow batteries is their high energy density, which means they can store a large amount of energy in a relatively small volume. This makes them an ideal choice for grid-scale energy storage applications where space is limited. Additionally, they have a longer lifespan than other types of batteries, and their modular design allows for easy scalability and maintenance.
Redflow offers several Zinc-Bromine flow battery products, including its flagship ZBM3 battery. The ZBM3 battery from Redflow is currently the world's most compact commercially available zinc-bromine flow battery. Its adaptable and modular design makes it suitable for use in various settings, ranging from small commercial installations to multi-megawatt hour storage systems. Compared to its previous versions, the ZBM3 is simpler, smaller, and more compatible. The design features a compact stack and a bi-directional DC-DC converter integrated into the Battery Control Module, which enables energy flow flexibility from 0-60 volts. This design feature eliminates the need for external voltage conversion, making it a suitable and compatible energy storage solution for various applications.
| Voltage | 48 Vdc nominal batteries (typical operating range 40 V to 60 V) |
|---|---|
| Capacity | Maximum 10 kWh energy output per cycle. No reserved battery capacity requirement – full 10 kWh cycle depth available |
| Degradation | Minimal (avg. 0.5% p.a.) capacity reduction over 10 year lifetime. |
| Dimensions | (W x D x H): 400 x 861 x 747 mm; 16 x 34 x 29 in. |
| Weight | 240 kg (530 lb) with electrolyte; 90 kg (198 lb) without electrolyte. |
| Electrolyte volume | 100 L (26 Gal). |
| Stack energy efficiency | 80% DC-DC Max. |
| Internal electrolyte operating temperature | 15 °C to 50 °C (59 °F to 122 °F). ZBM3 can operate at ambient temperatures outside this range depending on enclosure design. Additional cold weather kit available per individual battery. |
| Communication | MODBUS RS485 MODBUS-TCP, CANBUS. |
| Safety data sheet | DG Class 8 for electrolyte. |
| Power rating | 3 kW continuous (5 kW peak). |
| Regulatory compliance | CE (EU) and RCM (AU) pending. |
| Performance | No cycle depth limitations – battery performance and lifetime not sensitive to cycle depth. |
| Warranty | : 1 year / 3,650 kWh standard warranty (whichever comes first) and up to 10 year / 36,500 kWh extended warranty via an optional long term service agreement. |
| Standards | Certification to UL9540a completed. |
One of the unique features of Redflow's Zinc-Bromine flow batteries is their ability to operate in a wide range of temperatures, making them suitable for use in harsh environments. They are also fully recyclable, with the ability to reuse up to 95% of their components, making them an environmentally friendly choice.
Redflow's Zinc-Bromine flow batteries have been deployed in various projects around the world, including in Australia, Africa, and Asia. One notable project is a 4xZBM2 zinc-bromine flow battery system holding 40 kilowatt-hours (kWh) of energy at Mossel Bay, Southern Cape, South Africa.
Click here to view the Mossel Bay Municipality ZBM2 case study PDF.
Redflow has also been working to improve the performance and cost-effectiveness of its Zinc-Bromine flow batteries through ongoing research and development.
