Can single-flow membraneless flow batteries reduce system capital costs?

To reduce system capital costs, single-flow membraneless flow batteries are under intense investigation, but require intricate flow engineering. In this work, we analytically and numerically model the flow and chemical species transport for a novel single-flow geometry, and show enhancement of reactant transport and separation.

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.

How does a flow battery stack work?

In a flow battery stack, individual cells are typically fed with electrolyte in a parallel configuration, resulting in identical pressure drops across each cell. In this parallel liquid supply system, the distribution of electrolyte flow is closely related to the flow resistance in each branch.

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 are the flow channels of single-flow cells?

Typically, the flow channels of single-flow cells are long and thin rectangles, with a length to height ratio of approximately ten or higher ( Esan et al., 2020 ). To balance the myriad requirements on the electrolyte flow, novel channel geometries should be investigated to optimize flow and battery efficiency.

How do flow batteries maintain charge neutrality?

The charge neutrality condition for the each half-cell is maintained by a selective ion exchange membrane separating the anode and cathode compartments. The key differentiating factor of flow batteries is that the power and energy components are separate and can be scaled independently.