A typical electrochemical flow cell comprises various essential components (Fig. ). For simplicity, we here describe the typical setup of an all-liquid redox flow cell. A similar architecture is used for fuel cells -however the feed are gasses -or water electrolyzers -where the feed is liquid water. In such a cell, the cathode and anode sides deal with separate electrolyte solutions, known as catholytes and anolytes, which contain the chemical energy in dissolved redox active species. The current collector provides the electrical connection between the external circuit and the components in the flow cell. The bipolar plates (depicted together with the current collector as a single component in Fig. ) conduct electrons between the porous electrode and the current collector and contain engraved flow fields to control the fluid distribution. As illustrated in Fig. , electrolyte from the anode and cathode sides is pumped through porous electrodes located on each side within a cell stack. These electrodes are separated by an ion-exchange membrane to prevent mixing. Electrochemical redox reactions take place on the surfaces of the electrodes. The distinctive design of redox flow cells allows for independent scaling of power and energy. The power is determined by the size and performance of the electrochemical cell (the stack), while the energy/capacity is influenced by the volume of stored electrolyte and the concentration of active species .