On Extending Cycle-Life of the Soluble Lead Redox Flow Battery

Cycle-life of the soluble lead redox flow battery (SLRFB) is limited due to the oxygen evolution reaction taking place at its cathode. This parasitic reaction leads to imbalanced deposition of lead metal at anode and PbO2 particles at cathode. As a result, the concentration of Pb2+ ions decreases in the electrolyte during repeated charge and discharge cycles leading to formation of sludge containing Pb and PbO2. In this study, we have developed and demonstrated a method of using a bi-functional auxiliary gas-diffusion electrode to mitigate these problems that consequently helps extending cycle life of the SLRFB. The auxiliary gas-diffusion electrode is operated either as an (a) air electrode or (b) a hydrogen electrode. When the auxiliary gas-diffusion electrode is an air electrode, it is used as positive electrode and on coupling with anode of the SLRFB, it forms a galvanic Pb – air cell that on discharge results in dissolving Pb particles. When auxiliary gas-diffusion electrode is a hydrogen electrode, it acts as negative electrode and on coupling with the cathode of the SLRFB forms a galvanic PbO2-H2 cell which on discharge dissolves the PbO2 particles. A novel insight on extending the performance of the SLRFB will be discussed.