LAYERED ELECTRODES FOR ENERGY-EFFICIENT FLOW VANADIUM BATTERIES

Vanadium flow batteries (VFB) are becoming widespread as cheap and reliable electric storage cells. In their operating principle, VFB are very similar to fuel cells: they contain a liquid energy carrier (a rechargeable electrolyte) and a stack (a fuel cell in which an electrochemical reaction occurs). For the further development of these systems within the framework of the energy efficiency strategy, it is necessary to increase their efficiency factor, because currently it is only 60-65 %. In the present work, new electrode materials are developed and studied: combined electrodes, allowing a decrease in the internal resistance of the cell (a single element of stack design). To achieve this result, it is proposed to reduce the resistance associated with charge transfer to the electrode surface by creating an active layer with high surface area on the surface of the electrode (felt). The active layer was electrically conductive carbon black CH210, which was pre-functionalized to increase its hydrophilicity (the surface was oxidised in concentrated hydrogen peroxide at elevated pressure and temperature). Electrochemical measurements have shown that the deposition of an active layer increases the cell efficiency factor by 8.6 % at a current density of 50 mA/cm2, which confirms the viability of this approach.