Rebalancing cell system for redox flow battery

Patent metadata

Field	Value
Publication number	US-2024194921-A1
Application number	US-202218065576-A
Country	US
Kind code	A1
Filing date	Dec 13, 2022
Priority date	Dec 13, 2022
Publication date	Jun 13, 2024
Grant date	—

Abstract

Systems and methods are provided for rebalancing cells in a redox flow battery. In one example, a method of operating a rebalancing cell in a redox flow battery system includes measuring a state-of-charge (SOC) of a redox flow battery in the redox flow battery system, calculating an electrolyte concentration from the measured SOC of the redox flow battery, and maintaining a rebalancing reaction rate at the rebalancing cell. In one example, maintaining the rebalancing includes, responsive to a change in the electrolyte concentration, adjusting an electrolyte flow rate to the rebalancing cell and adjusting a hydrogen flow rate to the rebalancing cell.

First claim

1 . A method of operating a rebalancing cell in a redox flow battery system, comprising:
measuring a state-of-charge (SOC) of a redox flow battery in the redox flow battery system, calculating an electrolyte concentration from the measured SOC of the redox flow battery, and maintaining a rebalancing reaction rate at the rebalancing cell, including, responsive to a change in the electrolyte concentration,
adjusting an electrolyte flow rate to the rebalancing cell and
adjusting a hydrogen flow rate to the rebalancing cell.

2 . The method of claim 1 , wherein adjusting the electrolyte flow rate responsive to the change in the electrolyte concentration includes reducing the electrolyte flow rate responsive to an increase in the electrolyte concentration during a third condition, including when the electrolyte concentration is above a threshold electrolyte concentration.

3 . The method of claim 2 , wherein adjusting the hydrogen flow rate responsive to the change in the electrolyte concentration includes increasing the hydrogen flow rate responsive to the increase in the electrolyte concentration during a first condition, including when the electrolyte concentration is below the threshold electrolyte concentration.

4 . The method of claim 3 , wherein adjusting the electrolyte flow rate responsive to the change in the electrolyte concentration includes setting the electrolyte flow rate to an upper threshold electrolyte flow rate during the first condition.

5 . The method of claim 2 , wherein adjusting the hydrogen flow rate responsive to the change in the electrolyte concentration includes setting the hydrogen flow rate to an upper threshold hydrogen flow rate during the third condition.

6 . The method of claim 1 , wherein maintaining the rebalancing reaction rate at the rebalancing cell includes maintaining the electrolyte flow rate below an upper threshold electrolyte flow rate.

7 . The method of claim 1 , wherein maintaining the rebalancing reaction rate at the rebalancing cell includes maintaining the hydrogen flow rate above a lower threshold hydrogen flow rate.

8 . The method of claim 3 , wherein adjusting the electrolyte flow rate responsive to the change in the electrolyte concentration includes setting the electrolyte flow rate to the upper threshold electrolyte flow rate during a second condition, including when the electrolyte concentration is at the threshold electrolyte concentration.

9 . The method of claim 8 , wherein adjusting the hydrogen flow rate responsive to the change in the electrolyte concentration includes setting the hydrogen flow rate to an upper threshold hydrogen flow rate during the second condition.

10 . A redox flow battery system, comprising:
a redox flow battery, a rebalancing cell fluidly coupled to the redox flow battery an electrolyte flow control device fluidly coupled between the redox flow battery and the rebalancing cell, a hydrogen flow control device fluidly coupled between the redox flow battery and the rebalancing cell, and a controller, including executable instructions stored in non-transitory memory thereon to,
maintain an electrolyte rebalancing reaction rate at the rebalancing cell, including, responsive to a change in a concentration of an electrolyte,
modulating the electrolyte flow control device to adjust a flow rate of the electrolyte supplied to the rebalancing cell, and
modulating the hydrogen flow control device to adjust a flow rate of hydrogen supplied to the rebalancing cell.

11 . The redox flow battery system of claim 10 , wherein the redox flow battery includes an all iron redox flow battery (IFB), and the electrolyte includes ferric ion.

12 . The redox flow battery system of claim 10 , wherein the rebalancing cell includes a stack of electrode assemblies, each electrode assembly of the stack of electrode assemblies including an interfacing pair of positive and negative electrodes, wherein the electrolyte rebalancing reaction rate is driven via internal electrical shorting of interfacing pairs of the positive and negative electrodes of the rebalancing cell and the electrolyte and the hydrogen being convected through the electrolyte rebalancing cell.

13 . The redox flow battery system of claim 10 , wherein the electrolyte flow control device includes one of a pump and a flow control valve.

14 . The redox flow battery system of claim 10 , wherein the hydrogen flow control device includes a speed modulation device coupled to one of a venturi injector and a blower.

15 . A method of operating a redox flow battery system, comprising:
recirculating an electrolyte between a redox flow battery and a rebalancing cell,
supplying a hydrogen gas to the rebalancing cell,
measuring a state-of-charge (SOC) of the redox flow battery, and
maintaining a rebalancing reaction rate at the rebalancing cell, including,
adjusting a flow rate of the electrolyte to the rebalancing cell and adjusting a flow rate of the hydrogen gas to the rebalancing cell based on the measured SOC of the redox flow battery.

16 . The method of claim 15 , wherein adjusting the flow rate of the electrolyte to the rebalancing cell and adjusting the flow rate of the hydrogen gas to the rebalancing cell based on the measured SOC of the redox flow battery includes reducing the flow rate of the electrolyte responsive to an increase in the measured SOC of the redox flow battery while maintaining a flow rate of the hydrogen gas at an upper threshold hydrogen gas flow rate during a condition when the measured SOC of the redox flow battery is above a threshold redox flow battery SOC.

17 . The method of claim 15 , wherein adjusting the flow rate of the electrolyte to the rebalancing cell and adjusting the flow rate of the hydrogen gas to the rebalancing cell based on the measured SOC of the redox flow battery includes increasing the flow rate of the hydrogen gas responsive to an increase in the measured SOC of the redox flow battery while maintaining a flow rate of the electrolyte at an upper threshold electrolyte flow rate during a condition when the measured SOC of the redox flow battery is below a threshold redox flow battery SOC.

18 . The method of claim 15 , wherein adjusting the flow rate of the electrolyte to the rebalancing cell and adjusting the flow rate of the hydrogen gas to the rebalancing cell based on the measured SOC of the redox flow battery includes maintaining the flow rate of the hydrogen gas at the upper threshold hydrogen gas flow rate and maintaining the flow rate of the electrolyte at the upper threshold electrolyte flow rate during a condition when the measured SOC of the redox flow battery is at the threshold redox flow battery SOC.

19 . The method of claim 15 , wherein maintaining a rebalancing reaction rate at the rebalancing cell includes maintaining a ratio of a mass flow rate of the hydrogen gas to the rebalancing cell to a mass flow rate of the electrolyte to the rebalancing cell above a threshold mass flow ratio.

20 . The method of claim 19 , wherein maintaining the ratio of the mass flow rate of the hydrogen gas to the rebalancing cell to the mass flow rate of the electrolyte to the rebalancing cell above the threshold mass flow ratio includes maintaining a stoichiometric excess in hydrogen gas relative to the electrolyte at the rebalancing cell.

Assignees

• Ess Technology Inc

Inventors

• Kissick Sean
• Song Yang
• Mcdonald Timothy J

Classifications

• H01M8/188 Primary

  by recharging of redox couples containing fluids; Redox flow type batteries · CPC title

• H01M8/04753

  of fuel cell reactants · CPC title

• H01M8/04477

  of the electrolyte · CPC title

• H01M8/04313 Primary

  characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function · CPC title

• Y02E60/50

  Fuel cells · CPC title