The present disclosure details header flow divider designs and methods of electrolyte distribution. Internal header flow dividers may include multiple flow channels and may be built into flow frames. Flow channels within internal header flow dividers may divide evenly multiple times in order to form multiple flow channel paths and provide a uniform distribution of electrolytes throughout electrode sheets within electrochemical cells. Furthermore, uniform electrolyte distribution across electrode sheets may not only enhance battery performance, but also prevent zinc dendrites that may be formed in electrode sheets. The prevention of zinc dendrite growth in electrode sheets may increase operating lifetime of flow batteries. The disclosed internal header flow dividers may also be included within end caps of electrochemical cells.