Gravity Induced Flow Cell Using Suspension-Based Flow Electrodes

Technology 

This invention replaces the pumps and valves in conventional flow batteries with a rectangular cell that relies on gravity to induce flow.  The entire assembly can be constructed from low cost components using well-established manufacturing techniques, such as injection-molding.  Additionally, the mechanical simplifications made in this invention makes it more reliable than conventional flow batteries, making this design particularly suitable for large-scale applications.The cell contains separate reservoirs for the cathode and anode electrolytes.  When the cell is tilted, the electrolytes flow down the reservoirs, through the electroactive region, and into a second set of reservoirs. The electrolyte flow rate, which also determines the electrical current, is regulated by adjusting the angle of the rectangular cell and the pneumatic pressure within the reservoirs.  Flipping the cell flows the electrolytes in the other direction, allowing multiple passes during charge or discharge and allowing the battery to be cycled.  When the surfaces in contact with the electrolytes are made non-stick, this design minimizes shear strain on the electrolyte so it is suitable for the fully liquid electrolytes used in conventional flow batteries as well as semi-solid suspension electrolytes that have much higher energy densities.  

Problem Addressed

Flow batteries typically require expensive and mechanically complex pump systems to control the redox reaction and electrolyte flow.  This technology simplifies flow battery systems by using a gravity-driven design that does not use pumps.  Unlike conventional flow battery systems, this design can accommodate semi-solid as well as fully liquid electrolytes, expanding the number of redox chemistries that can be used in the battery and increasing energy density.   

Advantages

• Simplified and higher energy density flow battery design 
• Can accomodate a wide range of redox chemistries
• Low cost and simple manufacturing techniques
• Scalable to fit a variety of energy capacities