WO2025215654A1

WO2025215654A1 - Electrode assembly for electrochemical cells

Info

Publication number: WO2025215654A1
Application number: PCT/IN2024/051575
Authority: WO
Inventors: Aniruddha Pramod KULKARNI; Nachiket Bhide; Daniel Fini; Gaius Eau
Original assignee: Cavendish Renewable Technology Pty Ltd; Adani New Industries Ltd
Current assignee: Cavendish Renewable Technology Pty Ltd; Adani New Industries Ltd
Priority date: 2024-04-08
Filing date: 2024-08-29
Publication date: 2025-10-16
Anticipated expiration: 2026-10-08

Abstract

The present invention relates to an electrode assembly for electrochemical cells comprising a plurality of electrodes stacked in a configuration; wherein each electrode is positioned on top of another electrode, the electrodes having different porosities and creating local turbulence to enhance electrolyte efficiency, said assembly may include two, three, four, or five electrodes, with the pore size of the pores of the first electrode being larger than the pore size of the second electrode to cause turbulent flow over the surfaces of the plurality of electrodes.

Description

“ELECTRODE ASSEMBLY FOR ELECTROCHEMICAL CELLS”

FIELD OF INVENTION:

The present invention relates to the field of electrode assembly for electrochemical cells. More particularly, the present invention relates to hydrogen production from water using the electrode assembly.

BACKGROUND OF INVENTION:

Electrochemical cells are integral components of devices that either generate electrical energy from chemical reactions or cause chemical reactions to occur via the application of electrical power. Electrochemical cells are used in devices such as electrolysers, fuel cells, redox flow batteries, and many more.

Electrolysis is a well-established technology for producing hydrogen from water. This process involves using an electrical current to split water molecules into hydrogen and oxygen gases. Electrolysers can be classified into different types based on operating temperature, pressure, and configuration. Low-temperature electrolysis is a widely used technology for producing hydrogen, as it offers advantages such as easy to operate and low operating costs over other methods.

Despite their potential, the broad-scale implementation of electrolysers has been stymied by their substantial capital and operational expenses. A considerable proportion of these expenses is due to the intricate machining required for the bipolar plates which connect the cells and also control the flow of fluids through the cells in their conventional stacked configurations. Without such machining of flow channels on the bipolar plates, the flow distribution tends to be limited to being laminar and generally restricted to a limited area of the electrodes, which minimizes the reach of electrolyte throughout the available active sites of the electrodes for electrochemical reaction. Further, conventional stacks present several challenges, including a propensity for degradation, a limited operational lifespan, and inconsistent performance under diverse operating conditions such as fluctuating renewable energy electricity for the production of hydrogen.

PRIOR ART AND ITS DISADVANTAGES:

A US patent application number US2013224601A1 discloses the electrode structure for an electrochemical cell, which comprises a first porous support structure with smaller pores that are at least partially contained within the pores of a second porous structure. The second electrode or electroactive materials may be deposited inside the pores of the second support.

However, said prior art fails to create turbulent flow patterns to minimize bubble entrapment. The cited art also fails to provide flow distribution across the larger area and is limited for square-shaped electrolysis cells where liquid tends to flow across the diagonal in the absence of a turbulent flow field created by misaligned pores.

Another US patent application number US2005115825A1 discloses an electrolyzer cell arrangement with a patterned flow field plate arranged in combination with at least two porous metal layers having smooth and flat surfaces, in which water is more uniformly distributed across an active surface of an electrolyte layer, which in turn may lead to a more uniform reaction rate over the active area of the electrolyte layer. However, the above-mentioned prior art fails to provide the intentionally misaligned pores to create a turbulent flow pattern to minimize bubble entrapment as well as provide flow distribution across the larger area.

DISADVANTAGES OF THE PRIOR ART:

Existing technologies used for producing hydrogen from the water suffer from all or at least any of the below-mentioned disadvantages:

• Many of the prior art failed to provide an electrode assembly for electrochemical cells.

• Many of the prior art failed to provide an electrode assembly for the electrochemical cell that produces the hydrogen from the water.

• Many of the prior art failed to provide an electrode assembly for electrochemical cells that increases the productivity of producing hydrogen.

• Many of the prior art failed to provide an electrode assembly for the electrochemical cell that removes the bubble effect.

• Many of the prior art failed to provide an electrode assembly for electrochemical cells that can create turbulent flow.

• Many of the prior art failed to provide an electrode assembly for electrochemical cells that have a prolonged lifespan.

• Many of the prior art failed to provide an electrode assembly for electrochemical cells that are cost-efficient. OBJECTS OF INVENTION:

The main object of the present invention is to provide an electrode assembly for electrochemical cells.

Another object of the present invention is to provide an electrode assembly for electrochemical cells that is cost-effective.

Yet another object of the present invention is to provide an electrode assembly for the electrochemical cell that has a prolonged lifespan.

Yet another object of the present invention is to provide an electrode assembly for the electrochemical cell that produces hydrogen from the water.

Yet another object of the present invention is to provide an electrode assembly for the electrochemical cell that increases the productivity of producing hydrogen.

Yet another object of the present invention is to provide an electrode assembly for the electrochemical cell that creates turbulent flow.

Yet another object of the present invention is to provide an electrode assembly for the electrochemical cell that requires low-temperature electrochemical cells for producing hydrogen.

BRIEF DESCRIPTION OF THE DRAWINGS:

Reference numerals of said component parts of the present invention.

1 : Membrane

2 : Fine porous electrode

3 : Coarse electrode 1

4 : Coarse electrode 2

5 : Liquid in SUMMARY OF THE INVENTION:

DETAILED DESCRIPTION OF THE INVENTION:

The following description is presented to enable any person skilled in the art to make and use the invention and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and features disclosed herein.

It is to be understood that the term “comprising” or “comprises” used in the specification and claims refers to the element of the invention which comprises X, Y, and Z, which means that the invention might have other elements in addition to X, Y, and Z. For example, this invention could include A, B, and/or C as long as it also has X, Y, and Z. It is further to be understood that the present invention's industrial applicability may be in any device that comprises electrical cells, including fuel cells for converting hydrogen back to electricity and redox flow batteries.

The present invention provides an electrode assembly for electrochemical cells that is cost-effective, has a prolonged lifespan, produces hydrogen from the water, increases the productivity of producing hydrogen, creates turbulent flow, and requires low- temperature electrochemical cells for producing hydrogen.

Now, referring to Figure 1A, a conventional electrochemical cell is shown, which comprises of a membrane (1) and fine porous electrodes (2) configured on the membrane (1).

However, according to the embodiments shown in Figure IB, an electrochemical cell of the present invention comprises one or more electrodes (2) configured in stacked form, where each electrode is positioned one on top of another electrode, respectively. In the depicted configuration, a fine porous electrode (2) is situated on a membrane (1), and the coarse electrode 1 (3) and coarse electrode 2 (4) are placed on the said fine porous electrode (1), respectively. The electrodes have different porosities, with those having a finer porosity closer to the membrane and more coarse electrodes arranged further away.

The electrode assembly in certain embodiments incorporates electrochemical cells comprising an electrode system with a graded pore size.

The number of electrodes utilized in the present invention may be two or more. The assembly may include two, three, four, or five electrodes. Each electrode comprises an array of pores, with the pore size of the pores of the first electrode being larger than the pore size of the second electrode. Consequently, the fluid directed onto the electrode assembly causes turbulent flow over the surfaces of the plurality of electrodes.

The plurality of electrodes may be stacked in various configurations. In certain embodiments, the electrodes may be stacked such that the smaller pores near the electrolyte interface increase the surface interfacial area for the electrochemical reaction. The pore size of successive electrodes in the stack increases, which creates local turbulence within the cell compartment that enhances the electrolyte efficiency.

It is to be understood that the present embodiments are not limited to the specific electrochemical cell configuration shown and described but may encompass various modifications and equivalent arrangements within the scope of the appended claims.

In certain embodiments, an alkaline electrolyzer comprises three electrodes, with the first and second electrodes being made of 1mm diameter stainless steel backing plates. These backing plates are used in conjunction with a nickel electrode, which may be in the form of nickel foam or nickel mesh with a pore diameter of less than 1mm. The predefined misalignment of the first and second electrodes reduces porosity and misaligns the pores, creating local flow path deflection and causing the liquid to experience local flow velocity reductions. This combined effect generates turbulence for faster gas bubble removal. This configuration results in higher productivity and increases the hydrogen production rate. The present invention provides enhanced turbulence of liquid flow within the stack, which may reduce the wear of the electrodes and internal components of the cells, enhancing the mass transfer of reactants to the electrode surfaces and increasing the active surface area available for the reactions in an electrolyzer due to effective gas bubble removal.

The pore size of the pores in each electrode of the plurality of electrodes may independently vary from a few millimeters to the submicron scale. If the pores are too large, then the pore size may vary in a few millimeters. If the pores are too small, then the pore size of the electrodes may vary from micro to nano. In some embodiments, the pore size in one or more electrodes may include, but is not limited to 2mm, 1mm, 0.5mm, 0.1mm, 50pm, 25pm, 10pm, 5pm, 1pm, 0.5pm, and 0. lpm.

In some embodiments, the pores of the adjacent electrodes in the plurality of electrodes in the stacked configuration may be configured in a way that they are out of alignment with one another. This configuration helps to enhance the turbulent flow.

Referring to Figure 2, separate layers of a graded electrode system are depicted, with

A. two of said electrodes having the same sized (relatively larger) pores depicted in an out-of-alignment configuration, and

B. a fine electrode having smaller pores.

The electrodes are made from the same or different conductive materials such as stainless steel, nickel, titanium, and other alloys. In some embodiments, one or more electrodes may have catalytic properties. The electrodes may be infiltrated or coated with a catalyst. The catalyst may be incorporated in a manner that includes metal oxides, mixed metal oxides, precious metal oxides, zeolites, and transition metal-based materials. Any configuration that causes the fluid directed onto the electrode assembly to turbulently flow over the surfaces of the electrodes is suitable for use in the present invention. In some embodiments, the electrode assembly may be configured for fluid to be presented to an edge of the stacked electrodes.

Now, referring to Figures 3 and 4, liquid enters in the active area zone, which encounters an uneven lip that creates turbulence for the liquid entering the area. The present electrode assembly may be used in any system or device that typically includes electrodes. In some embodiments, the present electrode assembly may be used in low- temperature electrochemical cells. In some embodiments, the present electrode assembly may be used in an electrolyzer, a fuel cell, or a redox flow battery.

In certain embodiments, the present invention discloses low- temperature electrochemical cells designed to ensure adequate fluid circulation through the creation of turbulent flow fields for effective fluid distribution across the entire surface of the electrode and removal of formed bubbles without the need for intricate machining of bipolar plates.

The electrochemical cells comprise an electrolyte that separates the electrodes. The selection of electrolytes in the present invention depends on various factors including the type of electrochemical device, operating temperatures, and feed material. The electrolyte may consist of either a porous membrane or a non-porous polymeric membrane formed by casting onto porous tabular support from a solution of membrane precursors.

The porous membrane may be a porous polymer membrane or a porous ceramic membrane. The porous polymer membrane includes, but is not limited to, proton exchange membranes such as Nafion, anion exchange membranes such as sustanion, and alkaline electrolysis membranes such as zircon. Additionally, the porous ceramic membrane includes but is not limited to, doped titanium oxide, zirconium oxide, and zeolites for alkaline electrolysis. The ceramic layer is porous and allows for lower temperatures during membrane fabrication.

Moreover, the porous membrane may have a suitable pore size distribution compatible with the required functionality in the electrochemical cell, with a pore size distribution ranging between 10 microns to 15 microns.

The electrochemical cells also include current collectors to enable the flow of electrical current through the cell. These current collectors are made from conductive materials such as nickel wire, nickel strips, nickel-plated stainless steel wire, and gold-plated stainless steel wire. The current collectors are configured within the electrochemical cell in a manner consistent with the cell’s operation. In certain embodiments, one of the current collectors is located in the inner channel in electrical contact with the support, while another is situated in the outer channel in electrical contact with the outer electrode. TEST DATA:

The testing process entails the measurement of various characteristics (e.g., current density, running time, and voltage) of the cell, followed by consistent voltage measurement through the application of a 1.9V voltage (equivalent to approximately 50 kWh for 1 kg of hydrogen production) to the electrochemical cell. The electric current, the voltage across the electrochemical cell, and the temperature of the electrolyte solution are continuously monitored and recorded. The operating temperature is nominally set at 80°C. Electric heaters and thermocouples at the inlets to both the anode and cathode are used to maintain the solution temperature at 80°C, with a Powertech power supply and data logger utilized for accurate current-voltage measurements .

The findings of these experiments are depicted in Figures 5 to 7. Figure 5 exhibits the experimental data from the alkaline electrolyzer using the graded electrode system and highlights 1,400 hours of uninterrupted testing data, demonstrating the longevity and stability of the system. Figure 6 provides a comparison of Voltage-Current curves for alkaline electrolysers, with one employing the graded system proposed in this invention (•) and the other using a non-graded electrode system (A). Furthermore, Figure 7 displays a comparison of Voltage-Current curves for anion exchange membrane electrolysers, highlighting one employing the graded system proposed in this invention (•) and the other employing a non-graded electrode system (A). ADVANTAGES OF INVENTION:

• The present invention provides the electrode assembly for electrochemical cells.

• The present invention provides the electrode assembly which has low-temperature electrochemical cells.

• The present invention provides the electrode assembly for electrochemical cells that can create a turbulent flow.

• The present invention provides the electrode assembly for electrochemical cells that removes the bubbles on electrodes. • The present invention provides the electrode assembly for electrochemical cells that have a prolonged lifespan.

• The present invention provides an electrode assembly for electrochemical cells that is cost-effective.

• The present invention provides the electrode assembly for electrochemical cells that increases the hydrogen production rate.

Claims

CLAIM,

1. An electrode assembly for electrochemical cells comprising a plurality of electrodes stacked in a configuration; wherein each electrode is positioned on top of another electrode, the electrodes having different porosities and creating local turbulence to enhance electrolyte efficiency, said assembly may include two, three, four, or five electrodes, with the pore size of the pores of the first electrode being larger than the pore size of the second electrode to cause turbulent flow over the surfaces of the plurality of electrodes.

2. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein the pore size in one or more electrodes may range from 2mm to 0. 1pm.

3. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein the plurality of electrodes is in a stacked configuration such that smaller pores near the electrolyte interface increase the surface interfacial area for the electrochemical reaction and the pore size of successive electrodes is configured in the stack to increase, thereby creating local turbulence within the cell compartment to enhance electrolyte efficiency.

4. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein three electrodes, with the first and second electrodes being made of 1mm pore diameter stainless steel backing plates, a nickel electrode, in the form of nickel foam or nickel mesh, with a pore diameter of less than 1mm, predefined misalignment of the first and second electrodes to reduce pore volume , distort pore shape and misalign the pores, creating local flow path deflection and causing the liquid to experience local flow velocity reductions, thus generating turbulence for faster gas bubble removal and increasing productivity and hydrogen production rate.

5. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein the configuration of pores in each electrode of the plurality of electrodes with independent variation from a few millimeters to the submicron scale to enhance gas bubble removal and mass transfer of reactants to the electrode surfaces.

6. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein pores of adjacent electrodes are configured to be out of alignment with one another.

7. The electrode assembly for electrochemical cells as claimed in claims 1 and 6, wherein two electrodes with relatively larger pores are positioned in an out-of-alignment configuration and a fine electrode with smaller pores, wherein the electrodes are made from the same or different conductive materials.

8. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein one or more electrodes have catalytic properties, and wherein the catalyst may be incorporated in a manner including metal oxides, mixed metal oxides, precious metal oxides, zeolites, and transition metal-based materials.

9. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein the cells comprise an electrolyte that separates the electrodes and utilizes a porous or non-porous polymeric membrane.

10. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein said electrode assembly may be used in low-temperature electrochemical cells.

11. The electrode assembly for electrochemical cells as claimed in claim 1 , wherein said electrolyte for low- temperature electrochemical cells, comprising a porous membrane consisting of a porous polymer membrane such as Nafion, an anion exchange membrane such as sustanion, or an alkaline electrolysis membrane such as zircon, or a porous ceramic membrane such as doped titanium oxide, zirconium oxide, or zeolites.