Understanding the Redflow battery

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Flow Battery Characteristics

In its general definition, a flow battery features an electrolyte flowing continuously between a storage compartment (i.e. one or more tanks) and a reaction chamber where the electrodes are placed. Compared to a lead-acid battery, a flow battery contains more components and greater design complexity, with moving parts and sophisticated chemical containment. These batteries are typically deployed in stationary energy storage applications as changes to the system vertical alignment or changes in momentum or inertia Redflow delivers a new type of battery Redflow is a publicly-listed Australian company that has developed the world’s smallest zinc-bromine flow battery, that can be used anywhere from individual homes right up to grid-scale deployment can negatively affect the electrolyte flow, and thus the battery’s electrical performance.

The ZBM2 onboard Module Management System (MMS), which controls and safeguards the battery, adds an active element to each battery that is not present in standard batteries. While it increases the battery’s complexity, the MMS provides advantageous functions that enable the ZBM2 to be self-managing and to protect itself against potential environmental or operational damage risks. Where a ZBM2 replaces a conventional battery in a system design, its charge cycle is started by simply presenting an appropriate charging voltage and current to the Redflow battery. The MMS responds to this voltage by commencing a charge cycle. Likewise, a discharge cycle is commenced by simply drawing power from the battery, with the MMS managing the underlying active components to deliver the energy to the external load as required. A common characteristic of flow batteries, including the ZBM2, is that the battery can completely discharge during normal operation without incurring any damage or performance degradation. Unlike a conventional battery, a complete discharge is harmless to a ZBM2. However, this 100 per cent discharge capability results in the battery output voltage falling to zero volts and the on-board MMS halting operation. This is a circumstance that a conventional battery management system may report as an alarm or may respond by halting system operations. As noted above, after a complete discharge, the ZBM2 operation is re-commenced by simply applying an appropriate charge voltage to the system. In response, the MMS re-starts and commences a ZBM2 charging cycle. Consequently, the design of a system incorporating a ZBM2 battery or batteries needs to accommodate this 100 per cent discharge and re-start scenario as a normal part of battery operations.

ZBM2 Battery Advantages

The various flow battery characteristics discussed in this section can be leveraged to deliver unique advantages in an energy storage system using the ZBM2 zinc-bromine flow battery. Stack and tank separation.

 As with most flow batteries, the Redflow ZBM2 features a separation of the energy section – the tanks filled with the electrolyte – and the power section – the stack composed by electrodes. This separation enables unique advantages for flow batteries, such as flexibility in design and recycling of the battery parts at the end of life. Thus, the Redflow ZBM2 is one of the most sustainable and cost-effective batteries available today.

Decreased likelihood of theft

Another advantage of the ZBM2 battery over legacy technologies such as lead-acid batteries is the reduced risk of theft in the field. Conventional battery banks, which contain several 2V, 6V or 12V batteries, are attractive targets for theft as these single elements can be sold or reused. The uniqueness of the ZBM2 design and components mean that the battery is of little value to a potential thief outside of the application for which it has been designed. Also, with a total weight of about 240kg, the ZBM2 is too heavy for routine incidents of opportunistic theft to which conventional batteries are prone in remote field applications.

Control of immediate shut down

The separation of power and energy components in the ZBM2 battery also permits a shutdown within seconds by interrupting power supply to the flow pumps. Since no reactants are supplied to the electrodes after the pumps stop running, no electrical energy is transferred, so the system becomes still and safe. This enables the safe transport of ZBM2 batteries in this shutdown state. Also, a ZBM2 suffering mechanical damage does not risk explosion, dangerous high current output from short-circuit, or “thermal runaway”.