To demonstrate the effectiveness of this in situ pH recovery strategy, we pumped partially charged electrolytes through a BPM sub-cell and discharged them across the BPM. Linear-sweep a b c d voltammetry (LSV) was applied to study the polarization of the BPM cell (Fig. ). In Fig. we also show the LSV toward discharge in the three-chamber cell. The voltage difference between the two discharge curves is primarily from the energy cost of water dissociation. Therefore, the difference between them can be interpreted as the acid-base recovery energy cost. More detailed polarization curves of the BPM using different pH pairs were also recorded in a four-electrode setup (Fig. ). During pH recovery, we applied 40 mA cm -2 constant current density on the BPM cell through an independent potentiostat. A typical BPM cell voltage profile during pH recovery is shown in Fig. (dark blue curve, orange-highlighted region). The cell voltage during a few CCCV cycles before and after recovery is also shown. The recovery discharge voltage is lower than the normal cycling discharge voltage, the difference resulting from the thermodynamic water dissociation potential plus the overpotential of the BPM. This additional applied voltage creates an energy cost associated with in situ pH recovery. The ideal thermodynamic cost of generating 1 M each of acid and base from water is equivalent to 0.83 V, based on assumptions of unit activities of protons and hydroxides in their respective membrane layers. If the acid-base crossover is rapid, in situ pH recovery would be required frequently, and the added energy cost would be impractically severe, as shown in see Fig. . In contrast, in our mild pH-decoupling scheme, low crossover fluxes can be achieved, and just four pH recovery cycles (each with a capacity of about 6 mAh) were sufficient to keep the system stable for over a week (Fig. , at vertical arrows). After each recovery cycle, the pH of the negolyte increased (Fig. , light blue trace, and Fig. ), while the pH of the posolyte decreased (Fig. , orange trace, and Fig. ). The voltage-capacity profile shows stable cycling after pH recovery (Fig. ). The resistance of the BPM increased after two weeks of usage; we attribute this to the degradation of the catalytic layer in the BPM. BPMs with lower resistance, lower water dissociation overpotential and higher stability can further increase the practicability of these designs. pH buffering electrolytes can be applied to help maintain a more stable pH during pH recovery intervals. The capacity fade rate was smaller than 0.07%/day, and Coulombic efficiency was around 99%. The Coulombic efficiency drop during recovery was due to capacity utilization during BPM subcell discharge.