The flow field design and material composition of the electrode plays an important role in the performance of redox flow batteries, especially when using highly viscous liquids. To enhance the discharge power density of zinc slurry air flow batteries, an optimum slurry distribution in the cell is key. Hence, several types of flow fields (serpentine, parallel, plastic flow frames) were tested in this study to improve the discharge power density of the battery. The serpentine flow field delivered a power density of 55 mW∙cm−2, while parallel and flow frame resulted in 30 mW∙cm−2 and 10 mW∙cm−2, respectively. Moreover, when the anode bipolar plate material was changed from graphite to copper, the power density of the flow frame increased to 65 mW∙cm−2, and further improvement was attained when the bipolar plate material was further changed to copper–nickel. These results show the potential to increase the power density of slurry-based flow batteries by flow field optimization and design of bipolar plate materials.