To check the feasibility of this rebalancing strategy in our system, a capacity balanced cell was built by using 10 mL 0.1 M Fe(Bhmbpy)3 (Fe:Bhmbpy = 1:3.5, initial pH 2) pairing with 5 mL 0.1 M BHPC in a three-chamber cell. The cell capacity fading was recovered by exposing BHPC side to air (Fig. ). The oxygen-mediated oxidation of BHPC in the negolyte will result in net accumulation of hydroxide ions, which will not hurt the cell performance. The voltage-capacity curve shows the stable cycling voltage. Therefore, during the cell cycling in our case, air exposure was applied if the cell went out of balance.