Novel strategy for cathode in iron-lead single-flow battery: Electrochemically modified porous graphite plate electrode

Porous electrodes play a pivotal role in shaping the electrochemical performance, cost, and the assembly complexity of redox flow batteries. In this paper, the effects of porous structure on the electrochemical performance of graphite electrodes are first studied. Subsequently, a low-cost, high-performance graphite plate cathode is developed for redox flow battery using controlled electrochemical corrosion as a facile and effective electrode modification method. As a result, the electrochemical performance of the porous graphite electrode is significantly enhanced, and a revolutionary design of the iron‑lead single-flow battery is implemented by substituting graphite felt cathode with the modified porous graphite plate electrode. The iron‑lead battery with modified flat graphite plate cathode demonstrates high energy efficiencies, ranging from 90.91 % to 77.13 % between 10 and 40 mA/cm2, comparable to those obtained with graphite felt cathode. By combining the anode, bipolar plate, and cathode into one piece of graphite plate, a novel stack design is achieved with significant thickness reduction of the unit cell from 9 mm to 3 mm, resulting in notably increased energy and power density, improved assembly efficiency and reduced components cost of stacks. •Porous graphite cathodes are developed with electrochemical treatment for Fe-Pb single-flow battery.•With the graphite plate cathode, the thickness of the cathode is significantly reduced.•The graphite plate cathode provides excellent performance similar to the graphite felt electrode.•The Fe-Pb single-flow battery exhibits energy efficiency of 90.91 % and excellent cycling stability.