The zinc morphology on repeated charging and discharging in flow-assisted zinc–nickel oxide cells was studied. The results show that higher charge rates cause more dendritic growth of zinc deposition on charging and tend to cause deterioration of battery cells. However, when the electrolyte velocity is higher than 15cms−1, the direction of dendrites was distorted toward the flow direction and the internal short circuit was suppressed. Good cycle life was obtained – 1500 cycles at 100% depth of discharge and C/2 charge and discharge rate. Also, the battery was scaled up to a 100Wh prismatic cell, and more than 200 cycles were obtained.