Traditional flow batteries suffer from slow response rates due to faradaic reactions at the electrode-electrolyte surface and have limited cycle lifetimes (<12,000 cycles) which is a critical factor for grid scale energy storage. In contrast, the electrochemical flow capacitor is a rechargeable electrochemical energy storage system that utilizes flow battery architecture and is based on the fundamental working principles of supercapacitors. The primary difference between traditional flow cells and the EFC is that the EFC utilizes a flowable carbon-electrolyte ‘slurry electrode’ for capacitive energy storage (see Figure below).  During operation the slurry is pumped from a storage reservoir through two polarized plates (charging process). Once fully charged, the slurry is pumped out of the cell and stored in external reservoirs until the process is reversed and the slurry is discharged. The charged slurry stores charge electrostatically at the carbon/electrolyte interface, which allows for rapid charging and discharging leading to a higher power density. Faradaic charging processes have losses that cause degradation of the device over time compared to electrostatic charging, which has near 100% efficiency and millions of charge-discharge cycles.