The Effect of the Thickness of a Carbon-Black Active Layer on the Properties of Combined Electrodes in a Cell of the Vanadium Redox Flow Battery

The development of vanadium redox flow batteries requires elaborating new materials to improve their performance. To date, the studies of electrode materials for these energy storage devices are focused on increasing their specific power and energy efficiency. It is known that the energy efficiency can be increased by reducing the electrode polarization, which hinders the transport of the ions that carry charge between half-elements. This can be achieved for an electrochemically active layer localized immediately near the membrane surface. For this purpose, it is proposed to use bilayer composite electrodes with the active layer localized immediately at the electrode/membrane boundary. For the active layer of carbon black CH210 and a PVDF binder with a loading of 20 mg/cm2, the energy efficiency stays and a level of 79.6% for the current density of 150 mA/cm2. However, an increase in the layer thickness reduces the discharge capacity to 1% of its initial value corresponding to the uncoated electrode at a current density of 25 mA/cm2. Thus, the development of an active layer on the surface of a commercially available GFD 4.6 EA material by airbrush spraying is a fairly simple way to increase the efficiency of the charge-discharge cycle for a cell in a vanadium redox flow battery.