The cost of a flow battery system can be reduced by increasing its power density and thereby reducing its stack area. If per-pass utilizations are held constant, higher battery power densities can only be achie.
What is a flow battery?
Flow batteries allow for independent scaleup of power and capacity specifications since the chemical species are stored outside the cell. The power each cell generates depends on the current density and voltage. Flow batteries have typically been operated at about 50 mA/cm 2, approximately the same as batteries without convection.
Do flow batteries need a fluid model?
Flow batteries require electrolyte to be pumped through the cell stack Pumps require power Pump power affects efficiency Need a fluid model for the battery in order to understand how mechanical losses affect efficiency K. Webb ESE 471 29 RFB Fluid Model Power required to pump electrolyte through cell stack Pumping power is proportional to
Flow batteries comprise two components: Electrochemical cell Conversion between chemical and electrical energy External electrolyte storage tanks Energy storage Source: EPRI K. Webb ESE 471 5 Flow Battery Electrochemical Cell Electrochemical cell Two half-cellsseparated by a proton-exchange membrane(PEM)
What is the difference between power and capacity of a flow battery?
The capacity is a function of the amount of electrolyte and concentration of the active ions, whereas the power is primarily a function of electrode area within the cell. Similar to lithium-ion cells, flow battery cells can be stacked in series to meet voltage requirements. However, the electrolyte tanks remain external to the system.
What determines the energy storage capacity of a flow battery?
Volume of electrolyte in external tanks determines energy storage capacity Flow batteries can be tailored for an particular application Very fast response times- < 1 msec Time to switch between full-power charge and full-power discharge Typically limited by controls and power electronics Potentially very long discharge times
Why is a flow battery more efficient?
Also, note that as the volume of the cell components gets small relative to the volume of the electrolytes, the flow battery approaches its theoretical maximum of energy density. Higher capacity systems are thus more efficient in this respect, as the majority of the weight is the electrolyte which directly stores energy.