Flow batteries are rather unique. They generate electricity by the combination of two fluids flowing on either side of a membrane. Typically, this involves the use of some kind of pump to get everything moving. However, [Dusan Caf] has demonstrated another way to make a flow battery operate.
[Dusan]’s build is a zinc-iodide flow battery. It uses two 3D printed reservoirs, each holding a ZnI2 solution and a graphite electrode. Unlike traditional flow batteries, there is no mechanism included to mechanically push the fluid around. Instead, fluid motion is generated by the magnetohydrodynamic effect, which you may know from that Japanese boat that didn’t work very well.
When charging the liquid-based cell, current flows through the conductive electrolyte that sits between both electrodes. This sees zinc electroplated onto the graphite anode, while iodide ions are oxidized at the cathode. There’s also a permanent magnet installed beneath the electrodes, which provides a stable magnetic field. This field, combined with the current flowing through the electrolyte, sees the Lorentz force pushing the electrolyte along, allowing the flow battery to operate. When the cell is being discharged, the reactions happen in reverse, with the flow through the electrodes changing direction in turn. Neatly, as current draw or supply increases, the flow rate increases in turn, naturally regulating the system.
[Dusan] notes this isn’t feasible for large batteries, due to the limited flow rate, but it’s fine for small-scale demos regarding the operation of a flow battery. We’ve featured some more typical flow battery designs in the past, too.
Continue reading “This Flow Battery Operates With No Pump Required”
of a pair of electrolytes. These are held externally to the cell and connected with a pair of pumps. The capacity of a flow battery depends not upon the electrodes but instead the volume and concentration of the electrolyte, which means, for stationary installations, to increase storage, you need a bigger pair of tanks. There are even 4 MWh containerised flow batteries installed in various locations where the storage of renewable-derived energy needs a buffer to smooth out the power flow. The neat thing about vanadium flow batteries is centred around the versatility of vanadium itself. It can exist in four stable oxidation states so that a flow battery can utilise it for both sides of the reaction cell.
