# US 12,191,548 B2 · Hybrid redox fuel cell system

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- Number: US 12,191,548 B2
- Document ID: US12191548B2
- Status: Granted
- Kind: B2
- Application number: 17/929,623
- Filed: 2022-09-02
- Published: 2023-03-23
- Granted: 2025-01-07
- Earliest claimed: 2021-09-20
- Assignees: Ess Tech, Inc.
- Applicants: Ess Tech, Inc.
- Inventors: Yang Song; Craig Evans
- Web page: https://patentgrep.com/patent/US12191548B2

## CPC

- H01M 8/1009: with one of the reactants being liquid, solid or liquid-charged (H01M8/12 takes precedence)
- H01M 8/188: {by recharging of redox couples containing fluids; Redox flow type batteries}
- H01M 4/90: Selection of catalytic material
- H01M 8/0693: {Treatment of the electrolyte residue, e.g. reconcentrating}
- H01M 8/16: Biochemical fuel cells, i.e. cells in which microorganisms function as catalysts
- H01M 8/225: {Fuel cells in which the fuel is based on materials comprising particulate active material in the form of a suspension, a dispersion, a fluidised bed or a paste}
- Y02E 60/50: Fuel cells
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A hybrid redox fuel cell system includes a hybrid redox fuel cell including an anode side through which a reductant is flowed and a cathode side through which liquid electrolyte is flowed, and a trickle bed reactor including a catalyst bed fluidly connected to the cathode side of the hybrid redox fuel cell. Furthermore, the liquid electrolyte includes a metal ion at a higher oxidation state and the metal ion at a lower oxidation state, and power is generated at the hybrid redox fuel cell by way of reducing the metal ion at the higher oxidation state to the lower oxidation state at the cathode side while oxidizing the reductant at the anode side.

## Claims

### Claim 1

A hybrid redox fuel cell system, comprising:
a hybrid redox fuel cell including an anode side through which a reductant is flowed and a cathode side through which a liquid electrolyte is flowed,
a trickle bed reactor including a catalyst bed fluidly connected to the cathode side, and
a plurality of flow control devices, each of the plurality of flow control devices comprising one or more of a control valve, a flow meter and a pressure regulator, the plurality of flow control devices comprising:
a first flow control device located between a reductant supply line, the reductant supply line fluidly connecting a reductant source and the anode side, and a reductant discharge line; and
a second flow control device located between a first oxidant supply line, the first oxidant supply line fluidly connecting an outlet of the catalyst bed and the cathode side, and an oxidant discharge line, the oxidant discharge line fluidly connecting the cathode side and an inlet of the catalyst bed;
wherein,
the liquid electrolyte includes a metal ion at a higher oxidation state and the metal ion at a lower oxidation state, and
power is generated at the hybrid redox fuel cell by reducing the metal ion at the higher oxidation state to the lower oxidation state at the cathode side while oxidizing the reductant at the anode side.

### Claim 2 (depends on 1)

The hybrid redox fuel cell system of claim 1, wherein the hybrid redox fuel cell includes a hydrogen-ferric/ferrous ion hybrid redox fuel cell, the reductant includes hydrogen gas, the metal ion at the lower oxidation state includes ferrous ion, and the metal ion at the higher oxidation state includes ferric ion.

### Claim 3 (depends on 1)

The hybrid redox fuel cell system of claim 1, further comprising a pump positioned between the hybrid redox fuel cell and the catalyst bed, wherein the pump directs the liquid electrolyte from the cathode side to the catalyst bed, and recirculates the liquid electrolyte from the catalyst bed back to the cathode side after the liquid electrolyte fluidly contacts the catalyst bed.

### Claim 4 (depends on 3)

The hybrid redox fuel cell system of claim 3, wherein the metal ion at the lower oxidation state is oxidized to the metal ion at the higher oxidation state while fluidly contacting the catalyst bed.

### Claim 5 (depends on 4)

The hybrid redox fuel cell system of claim 4, wherein a concentration of the metal ion at the higher oxidation state is higher in the liquid electrolyte directed from the catalyst bed to the cathode side than the concentration of the metal ion at the higher oxidation state in the liquid electrolyte directed from the cathode side to the catalyst bed.

### Claim 6 (depends on 5)

The hybrid redox fuel cell system of claim 5, wherein the anode side is fluidly decoupled from the catalyst bed except for hydrogen protons crossing over from the anode to the cathode side through a separator.

### Claim 7 (depends on 3)

The hybrid redox fuel cell system of claim 3, wherein the catalyst bed includes a chemolithotrophic microorganism.

### Claim 8 (depends on 7)

The hybrid redox fuel cell system of claim 7, wherein the catalyst bed includes the chemolithotrophic microorganism immobilized on biomass support particles.

### Claim 9 (depends on 8)

The hybrid redox fuel cell system of claim 8, further comprising a regeneration gas source, wherein carbon dioxide gas is directed from the regeneration gas source to the catalyst bed.