Flow batteries are currently limited by their energy density. Introducing solid-state ion-insertion compounds in a mixed-conducting, flowable suspension increases the energy density. However, the increased viscosity of this suspension incurs two efficiency losses; the electroactive region extends the cell stack and non-uniformity of the flow field. These inefficiencies reduce the discharge energy and overall energetic efficiency. This technology models suspension flow batteries and determines the material properties and flow volume control needed to obtain both a discharge energy as a percentage of theoretical value and an energetic efficiency >95%.