To further evaluate the performance of the three-chamber and pH recovery cell combination, we utilized a high concentration aqueous redox pair. 2 M FeCl3 (pH 1-3) was paired with 1 M BHPC (pH 13-14, introducing high pH swing) realizing high volumetric capacity. The testing results demonstrated promising cycling performance and successful pH recovery through the BPM cell (Fig. ). However, the results also showed fast capacity fading due to iron ion crossover (Fig. ).