Lithium-ion batteries contain porous electrodes separated by an ion-permeable membrane. Those electrodes are manufactured by coating metal foils with battery slurry, a complex fluid that contains the raw materials that make the batteries function. We will present the foundations of a physics-based understanding of battery slurry behavior under flow, with a special emphasis on evolving material microstructure. We will take a close look at the unique tools that can explore this microstructure at the relevant length scale and in the relevant environment. We will show that these findings have relevance to the prediction of both the battery slurry rheology and the coated properties of battery electrodes, thereby improving the efficiency of battery manufacturing.