Figure shows the fade rate versus OH -concentration under different cycling conditions including 100%, 0-85% SOC restriction, and 0-85% SOC restriction combined with a regeneration step; the values at 100% cycling are copied from Figure for comparison purposes. The impact of SOC restriction on the fade rate of a DHAQ flow cell was previously reported in 1 M OH -14 . However, Figure shows how a combination of SOC restriction cycling and OH -concentration affects the fade rate. Under 0-85% SOC cycling conditions, as the OH -concentration increases to 2.0 M, the fade rate decreases to 0.09%/day. Thus, with a combination of 85% SOC restriction and OH -concentration, a fade rate of 0.09%/day is achievable that is ∼8 and ∼45 times lower than the fade rate in 1 M OH -with and without employing 0-85% SOC restriction, respectively. This observation confirms that increasing the OH -concentration beyond 1.0 M significantly reduces the fade rate even when the SOC restriction technique is utilized.