Advanced hydrogen membrane fuel cell

Abstract

A process for loading an electrolyte membrane of a hydrogen fuel cell with hydrogen protons is disclosed. The process comprises contacting the electrolyte membrane with hydrogen at a pressure of up to 15,000 psig at a temperature of up to 500 degrees Celsius whilst removing electrons from the hydrogen.

Description

ADVANCED HYDROGEN MEMBRANE FUEL CELLPRIORITY DOCUMENT

[0001] The present application claims priority from Australian Provisional Patent Application No. 2024900134 titled “ADVANCED HYDROGEN MEMBRANE FUEL CELL” and filed on 21 January 2024, the content of which is hereby incorporated by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates to fuel cells. In a particular form the present disclosure relates to proton exchange membrane fuel cells.BACKGROUND

[0003] The proton exchange membrane fuel cell or PEMFC has become a popular fuel cell used in hydrogen fuel cell vehicles. Figure 1 shows a conventional PEMFC in which a proton exchange membrane (PEM) is sandwiched between the anode electrode and the cathode electrode. The electrodes are usually made of graphite with platinum catalyst particles on the active surface where hydrogen or oxygen (or air) is applied to the surface. Conductors connect the electrodes to the load. In operation, the catalyst reduces the hydrogen into hydrogen ions (i.e. protons) and electrons. The electrons travel from the anode electrode to the load and then to the cathode electrode. The hydrogen proton travels to the cathode electrode by diffusion and the proton, electron and oxygen meet at the cathode electrode to form water and complete the fuel cell reaction.

[0004] Unfortunately, the operation of conventional PEMFCs is limited by the rate of travel of the hydrogen proton from the anode electrode to the cathode electrode. As the electrical load increases, the supply of protons cannot keep up and the PEMFC suffers in efficiency and capacity. Consequently, the efficiency of conventional PEMFCs is only around 30 % to 40 % at full load.

[0005] There is a need to provide a PEMFC that overcomes or ameliorates one or more of the problems associated with conventional PEMFCs. Alternatively, or in addition, there is a need to provide a PEMFC that provides a useful alternative to conventional PEMFCs.SUMMARY

[0006] The present disclosure arises from the inventor’s finding that the efficiency and capacity of a conventional solid proton exchange membrane fuel cell can be increased significantly by pre-loading hydrogen protons to the membrane. Protons can be added by applying hydrogen at pressures up to 15 ,000 psig at a temperature up to 500 degrees Celsius while applying a current to remove the electrons and store the electrons in a capacitor. Increased fuel cell efficiency / capacity of about 14 % was achieved with an application pressure of 200 psig, a temperature of 60 degrees Celsius and 24 hours or application.

[0007] According to a first aspect, there is provided a process for loading an electrolyte membrane of a hydrogen fuel cell with hydrogen protons, the process comprising contacting the electrolyte membrane with hydrogen at a pressure of up to 15,000 psig at a temperature of up to 500 degrees Celsius whilst removing electrons from the hydrogen.

[0008] Protons may be loaded onto the electrolyte membrane whilst it is in a PEMFC or during the manufacture of the electrolyte membrane.

[0009] Protons may be loaded into liquid electrolytes of other fuel cells and the electrolytes of the diaphragm-less Unipolar electrolysis of water to increase efficiency and capacity of these processes.

[0010] According to a second aspect, there is provided a membrane electrode assembly, comprising: an anode; a cathode; an electrolyte membrane interposed between the anode and the cathode, wherein the electrolyte membrane is loaded with hydrogen protons.

[0011] According to a third aspect, there is provided a proton exchange membrane fuel cell, comprising the membrane electrode assembly of the second aspect.BRIEF DESCRIPTION OF THE FIGURES

[0012] Embodiments of the present disclosure will be discussed with reference to the accompanying figures wherein:

[0013] Figure 1 is a schematic diagram of a conventional proton exchange membrane fuel cell;

[0014] Figure 2 is a schematic diagram showing (A) long travel of protons in a conventional proton exchange membrane fuel cell; and (B) pre-loading protons in a proton exchange membrane fuel cell with shorter proton travel;

[0015] Figure 3 is a schematic diagram of a support for a pressure vessel for loading protons into a Horizon fuel cell;

[0016] Figure 4 is a schematic diagram showing a process for loading protons to a proton exchange membrane fuel cell;

[0017] Figure 5 shows a graph showing the tested power output of a 5 kW proton exchange membrane fuel cell with pre-loaded protons vs an original factory fuel cell without pre-loaded protons;

[0018] Figure 6 shows a graph showing the voltage vs current of a 5 kW proton exchange membrane fuel cell with pre-loaded protons vs an original factory fuel cell without pre-loaded protons;

[0019] Figure 7 is a schematic diagram showing a process for loading protons to an electrolyte;

[0020] Figure 8 shows embodiments of an advanced fuel cell according to embodiments of the present disclosure, wherein (A) shows an advanced fuel cell according to an embodiment having curved electrodes; (B) shows an advanced fuel cell according to an embodiment having straight electrodes with baffles; and (C) shows an advanced non -diffusion fuel cell according to an embodiment with series connection; and

[0021] Figure 9 shows a design of a cylindrical non-diffusion fuel cell according to embodiments of the present disclosure.DESCRIPTION OF EMBODIMENTS

[0022] This invention concerns the significant improvement in capacity and efficiency of the popular proton exchange membrane fuel cell that is widely used in propelling personal vehicles. This invention may also be useful in the electrolysis of water where proton transfer from the anode to the cathode is important for the production of hydrogen.

[0023] This invention aims to correct the deficiency of the conventional PEMFC by reducing the travel distance of the hydrogen proton from the anode electrode to the cathode electrode. This is achieved by pre-loading protons on the proton electrolyte membrane as shown in Figure 2. In Figure 2(A), the protonstravel the whole width of the proton electrolyte membrane and not enough protons reach the cathode electrode during heavy load on the PEMFC and this limits the efficiency or capacity of the cell.

[0024] In contrast, an embodiment of a modified PEMFC of the present disclosure is shown in Figure 2(B) where protons are pre-loaded on the proton electrolyte membrane and the travel of the protons is shortened. This allows the supply of protons to increase resulting in a higher efficiency and capacity of the PEMFC.

[0025] Thus, disclosed herein is a process for loading an electrolyte membrane of a hydrogen fuel cell with hydrogen protons. The process comprises contacting the electrolyte membrane with hydrogen at a pressure of up to 15,000 psig at a temperature of up to 500 degrees Celsius whilst removing electrons from the hydrogen.

[0026] The electrolyte membrane is a membrane used in a hydrogen fuel cell, in particular a proton exchange membrane fuel cell (PEMFC). Advantages of PEMFCs include high power density, low working temperature, good starting performance, mature technology, etc. A range of PEMFCs are known and typically comprise a proton exchange membrane (PEM) interposed between an anode that includes a catalyst (such as platinum) and a cathode. A fuel, such as hydrogen gas, passes along the anode where the catalyst causes hydrogen atoms to be oxidized (act as a reducing agent) and split into positively -charged ions (e.g., protons in the case where hydrogen is the fuel) and electrons. The positively -charged protons pass through the proton exchange membrane and the electrons travel through an electrical circuit to reunite with the positively charged-ions and other reactants, which are reduced (act as an oxidizing agent) on the cathode side of the fuel cell. The proton exchange membrane (PEM) of these devices may be referred to herein as an “electrolyte membrane”.

[0027] The electrolyte membrane used herein can be formed from any non-conductive material that allows proton transport and is suitable for use between an anode electrode and a cathode electrode of a polymer electrolyte membrane fuel cell. Non-limiting examples of suitable materials include Nafion™, polybenzoimidazole (PBI), sulfonated poly(ether ketone), sulfonated poly(ether ether ketone), sulfonated polyimide, sulfonated poly sulfone, or other polyelectrolytes. The thickness of the electrolyte membrane may be 5 pm to 200 pm.

[0028] Alternatively, the electrolyte membrane may be a liquid electrolyte suitable for use in a diaphragm-less non-diffusion hydrogen fuel cell.

[0029] Hydrogen protons are produced and loaded into the electrolyte membrane as described herein. As used herein, the terms “hydrogen protons” and “protons” means positively charged H+ions. They are formed by reduction of hydrogen (H2).

[0030] To load protons to the electrolyte membrane of a fuel cell, hydrogen is applied under pressure and electrons are removed so that protons are loaded into the electrolyte membrane. A cylindrical pressure vessel as shown on Figure 3 can be used. The pressure vessel is supported in a vertical position.

[0031] To load the electrolyte membrane with protons, it is contacted with hydrogen at a pressure of up to 15,000 psig. The loading of protons may be carried out at a pressure of from about 100 psig to about 15,000psig, such as about 100 psig to about 500 psig, such as about lOOpsig, about 150 psig, about 200 psig, about 250 psig, about 300 psig, about 350 psig, about 400 psig, about 450 psig, or about 500 psig. In certain embodiments, loading of protons is carried out at a pressure of about 200 psig.

[0032] The electrolyte membrane is contacted with hydrogen at a temperature of up to about 500 degrees Celsius, for example from about 50 degrees Celsius to about 500 degrees Celsius, such as about 50 degrees Celsius, about 60 degrees Celsius, about 70 degrees Celsius, about 80 degrees Celsius, about 90 degrees Celsius or about 100 degrees Celsius. In certain embodiments, loading of protons is carried out at temperature of 58 degrees Celsius.

[0033] The loading of protons onto or into the electrolyte membrane can be carried out for a suitable time, for example from about 1 hour to about 48 hours, such as about 24 hours.

[0034] The loading or protons requires removal of electrons from the hydrogen. The electrons can be removed using a cathode electrode and an anode electrode in contact with the electrolyte membrane. The electrodes may be made of carbon, such as graphene. A DC voltage of up to 6.5 Volts, such as about 6 Volts, can be applied to the electrodes. Electrons are withdrawn from the electrodes to produce hydrogen protons. Once removed, the electrons can be stored in a capacitor.

[0035] The electrodes and / or the electrolyte membrane may contain a catalyst to allow more hydrogen protons to be loaded. The catalyst may be selected from the group consisting of platinum, gold, cobalt, iron, rubidium, nickel, silver, palladium and a combination thereof.

[0036] Also disclosed herein is a membrane electrode assembly comprising an anode, a cathode, and an electrolyte membrane interposed between the anode and the cathode, wherein the electrolyte membrane is loaded with hydrogen protons. The electrolyte membrane can be loaded with hydrogen protons using the process as described herein. Also disclosed herein is a proton exchange membrane fuel cell (PEMFC) comprising the membrane electrode assembly.

[0037] Following is an example of a process according to the present disclosure.

[0038] A 5 kW Horizon fuel cell was used in experiments to pre-load protons on the electrolyte membrane. Unmodified Horizon fuel cells provide the power shown in Table 1.

[0039] Table 1 - Factory test on 5kW Horizon fuel cell

[0040] The 5 kW Horizon fuel cell contains 120 electrodes in a stack. Only 12 electrodes can be accommodated in the pressure vessel 30 shown in Figure 3.

[0041] Figure 4 shows an apparatus 40 that can be used to load protons on to the electrolyte membrane 42. The electrodes 44a and 44b in the pressure vessel are connected to a DC power supply 46. Hydrogen is supplied to the pressure vessel 30 and about 6 Volts is applied. Electrons are withdrawn from the electrodes 44a and 44b to produce hydrogen protons. The electrons are stored in a 10 million farad capacitor 48. This process was carried out for 12 electrodes for 24 hours. The experimental procedure is recorded in Table 2 for the 5thof the 10 short stacks of electrodes.

[0042] Table 2 - Pre-loading of protons to a group of 12 electrodes of a Horizon fuel cell — 5thof 10 stacks

[0043] The loading of protons was carried out at 200 psig, 58 degrees Celsius and over a 24 hour period. The voltage applied to the electrodes was 6.5 Volts and the initial current was 10 amperes. The capacitor has a capacity of 10 million farads and the initial voltage was 0.0042 Volts rising to 2.1035 Volts after 24 hours. This indicated that protons were being produced during this phase.

[0044] The ten x 12 electrodes pre-loaded with protons were then assembled back into the Horizon fuel cell. The fuel cell was run for 30 minutes at full load before the test started , starting from a low load to past the maximumratedloadof the fuel cell. Two tests were carried out as shown in Table 3, one dated 19 / 07 / 2023 and the second on 21 / 07 / 2023.

[0045] Table 3 - Fuel cell voltage and power output before and after pre-loading with hydrogen protons

[0046] Benefits of pre-loading protons are shown in Figure 5 where the cell power output is plotted against cell current. Clearly, the power output of the pre-loaded proton fuel cell is higher than the power of the original fuel cell. At 60 amperes which is the rated capacity of the original fuel cell, the pre-loaded fuel cell delivered about 12 % more power. Also, the power of the pre-loaded proton fuel cell increases with higher current. This is likely because the proton supply is better even at higher current load.

[0047] In electricity supply, voltage regulation is important. Figure 6 shows the variation of the voltage against the current of the original fuel cell and the proton pre-loaded fuel cell. The voltage of the pre- loaded fuel cell is higher than the voltage of the original fuel cell and the difference increases with higher current loads. This indicates the supply of protons in the pre-loaded fuel cell is better to accommodate higher current loads.

[0048] There will be fuel cells where the electrolyte is a liquid instead of a solid electrolyte used in the PEMFC. The efficiency of the liquid electrolyte can be improved by adding protons as shown in Figure 7.

[0049] The electrolyte is circulated through electrodes coated with fine particles of platinum or other catalyst. Hydrogen is applied under high pressure; protons are produced and mix with the electrolyte while the electrons are stored in a capacitor.

[0050] One such hydrogen fuel cell is shown in Figure 8. The non-conductive liquid electrolyte is pumped through the space between the anode electrode and the cathode electrode as shown in Figure 8(C). The electrodes may be connected in series as shown in Figure 8(C). Instead of the wave shape of the electrodes, the electrodes may be flat but the electrolyte is baffled so that the electrolyte weaves in a wave to transfer the protons from the anode electrode to the cathode electrode. Figure 9 shows a cylindrical fuel cell with a liquid electrolyte where the rotating centre transfers the protons from the anode electrode to the cathode electrode.

[0051] This concept of pre-loading protons to the electrolyte may also apply to electrolyte in processes where the supply of protons is important for the efficiency of the process. Specific examples are in the diaphragm-less phosphoric acid fuel cell of the applicant and in the diaphragm -less Unipolar electrolysis of water.

[0052] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

[0053] It will be understood that the terms “comprise” and “include” and any of their derivatives (e .g. comprises, comprising, includes, including) as usedin this specification , and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

[0054] In some cases, a single embodiment may, for succinctness and / or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim Further a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of : a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

[0055] It will be appreciated by those skilled in the art that the disclosure is not restricted in its use to the particular application or applications described. Neither is the present disclosure restricted in itspreferred embodiment with regard to the particular elements and / or features described or depicted herein. It will be appreciated that the disclosure is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope as set forth and defined by the following claims.

Claims

CLAIMS1. A process for loading an electrolyte membrane of a hydrogen fuel cell with hydrogen protons, the process comprising contacting the electrolyte membrane with hydrogen at a pressure of up to 15 ,000 psig at a temperature of up to 500 degrees Celsius whilst removing electrons from the hydrogen.

2. The process of claim 1, wherein the removed electrons are stored in a capacitor.

3. The process of either claim 1 or claim 2, wherein the electrons are removed using a cathode electrode and an anode electrode in contact with the electrolyte membrane.

4. The process of claim 3, wherein the electrodes are made of carbon.

5. The process of claim 4, wherein the electrodes are made of graphene.

6. The process of any one of claims 3 to 5, wherein the electrodes and / or the electrolyte membrane contain a catalyst to allow more hydrogen protons to be loaded.

7. The process of any one of claims 3 to 6, comprising applying a DC voltage to the electrodes.

8. The process of claim 7, wherein the DC voltage is up to 6.5 Volts.

9. The process of any one of claims 1 to 8, wherein the electrolyte membrane is loaded with hydrogen protons during manufacture of the electrolyte membrane.

10. The process of any one of claims 1 to 9, wherein the electrolyte membrane is in a fuel cell.

11. The process of any one of claims 1 to 10, wherein the electrolyte membrane is a non-conductive material suitable for use between an anode electrode and a cathode electrode of a polymer electrolyte membrane fuel cell.

12. The process of any one of claims 1 to 10, wherein the electrolyte membrane is an electrolyte suitable for use in a diaphragm-less non-diffusion hydrogen fuel cell.

13. A membrane electrode assembly comprising: an anode; a cathode;an electrolyte membrane interposed between the anode and the cathode, wherein the electrolyte membrane is loaded with hydrogen protons.

14. The membrane electrode assembly of claim 13, wherein the electrolyte membrane has been loaded with hydrogen protons using the process of any one of claims 1 to 12.

15. A proton exchange membrane fuel cell (PEMFC) comprising the membrane electrode assembly of either claim 13 or claim 14.

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