Which is better iron liquid flow battery or vanadium liquid flow battery

Energy storage is the main differing aspect separating flow batteries and conventional batteries. Flow batteries store energy in a liquid form (electrolyte) compared to being stored in an electrode in conventional batteries. Due to the energy being stored as electrolyte liquid it is easy to increase capacity through adding more fluid to the tank.

There's no such thing as a flow-battery Tesla. But the companies at the International Flow Battery Forum in Prague in late June were adamant that flow batteries are now cheaper, more reliable, and safer than lithium ion in a growing number of real-world stationary energy applications.

On charging, ions from one electrolyte move through the battery's membrane to the second electrolyte. At large scale, flow batteries are cheaper than other batteries over their lifetimes. Source: Saudi Aramco. Note: The comparison is of the lifetime cost of a 10 MW battery capable of supplying electricity for 4 h at a time.

One advantage of flow batteries is that they can also be immediately “recharged” by replacing the spent liquids in the tank with energised liquid. The volume of liquid electrolyte determines the battery energy capacity, with the surface area of the electrodes determining the battery power – so typically flow batteries are quite large and heavy!

Redox flow batteries have a reputation of being second best. Less energy intensive and slower to charge and discharge than their lithium-ion cousins, they fail to meet the performance requirements of snazzy, mainstream applications, such as cars and cell phones. There's no such thing as a flow-battery Tesla.

Vanadium Redox Flow Batteries (VRFBs) are proven technologies that are known to be durable and long lasting. They are the work horses and long-haul trucks of the battery world compared to the sports car, like fast Lithium-Ion (Li-Ion) batteries. However, VRFBs have developed a reputation for being notoriously expensive.