Novel bipolar electrodes for battery applications

A novel bipolar graphite felt electrode for use in redox flow batteries and other electrochemical systems is described. The new electrode features a unique approach in the design of bipolar electrodes, employing carbon black free, nonconductive polymer materials as substrates. This innovation allows a dramatic reduction of processing time and cost compared to conventional carbon polymer composite electrodes used in bipolar battery systems. The conductivity of the new electrode assembly is similar to that of conventional bipolar electrodes, however, it shows significant improvements in mechanical properties. The functionality of these novel electrodes has been evaluated in the vanadium redox battery application and the results show comparable performance with conventional composite materials. An important operational advantage, however, is that side reactions leading to the deterioration of conductive filler in the electrode substrate material (i.e., electrode delamination due to CO₂-evolution) during cell overcharging are eliminated, making these electrodes more durable than the conventional designs. To date, these bipolar electrodes have been applied in vanadium redox cells but their design and properties promise further applications in a range of other redox flow batteries and bipolar electrochemical cell systems.