The main difference between flow batteries and other rechargeable battery types is that the aqueous electrolyte solution usually found in other batteries is not stored in the cells around the positive electrode and negative electrode. Instead, the active materials are stored in exterior tanks and. There are some important differences to account for when comparing flow batteries to the leading battery technologies like lithium-ion batteries: With more and more utility companies switching over to time-of-use billing structures, flow batteries provide a compelling solution for microgrid operators or large manufacturing facilities to shift expensive peak loads over to long-duration battery use.