Electrochemical hydrogen pump

Abstract

A multi-stage electrochemical hydrogen pump is provided that includes a first electrochemical hydrogen pump stage fluidly connected to a second electrochemical hydrogen pump stage configured to receive a first gas mixture including hydrogen gas, electrochemically separate hydrogen gas from the first gas mixture to produce a second gas mixture, and output the second gas mixture to the second electrochemical pump stage, and configured to receive the second gas mixture from the first electrochemical hydrogen pump stage, electrochemically separate hydrogen gas from the second gas mixture to produce a third gas mixture, and output the third gas mixture.

Description

Technical Field

[0001] The present invention relates to an electrochemical hydrogen pump.

Background Art

[0002] An electrochemical hydrogen pump is a known type of pump used in various different industries (such as metal wire annealing). An electrochemical hydrogen pump typically functions by using one or more electrochemical cells to separate hydrogen gas from a mixed gas.

[0003] FIG. 1 is a schematic diagram showing a conventional electrochemical hydrogen pump 100 (not to scale). The electrochemical hydrogen pump 100 includes a housing 110, a plurality of electrochemical cells 120, a first current collector 130, a second current collector 140, an input line 150, and an output line 160.

[0004] The housing 110 defines a space in which the remaining components of the electrochemical hydrogen pump 100 are disposed. Specifically, the plurality of electrochemical cells 120, the first current collector 130, the second current collector 140, the input line 150, and the output line 160 are disposed in the space defined by the housing 110.

[0005] Each of the multiple electrochemical cells 120 is configured to receive a first gas mixture containing hydrogen gas, electrochemically separate the hydrogen gas from the first gas mixture, and output a second gas mixture containing the separated hydrogen gas. The multiple electrochemical cells 120 are arranged in a stack and fluidly connected to each other in parallel. Each of the multiple electrochemical cells 120 comprises an anode chamber 122, a cathode chamber 124, and an ion exchange mechanism 126. Each anode chamber 122 is equipped with an anode and is configured to receive the first mixed gas from an input line 150. Each cathode chamber 124 is equipped with a cathode and is configured to output the second mixed gas to an output line 160. Each ion exchange mechanism 126 is positioned between the respective anode chambers and cathode chambers 122, 124, separating them from each other, and the ion exchange mechanism 126 acts as a partial barrier to the fluid flow between the respective anode chambers and cathode chambers 122, 124. The ion exchange mechanism 126 of each electrochemical cell 120 is semipermeable and configured to selectively allow hydrogen ions to pass through it in order to move from their respective anode chambers 122 to their respective cathode chambers 124, but to substantially prevent other components of the first gas mixture from passing through it.

[0006] The first mixed gas consists of hydrogen gas mixed with one or more other types of gases. The second mixed gas is the product of electrochemical hydrogen separation performed by the electrochemical cell 120, and has a much higher proportion of hydrogen gas compared to the first mixed gas. Specifically, the second gas mixture consists almost entirely of hydrogen gas, but still contains trace amounts of one or more other types of gases (which can be called impurities or contaminants) that somehow managed to move across the ion exchange mechanism 126 due to imperfections in the ion exchange mechanism 126.

[0007] The anode can be made of a catalytic material containing platinum nanoparticles that may or may not be supported on carbon nanoparticles. Similarly, the cathode can be made of a catalytic material containing platinum nanoparticles that may or may not be supported on carbon nanoparticles. The ion exchange mechanism 126 can be made of ion exchange mechanism materials such as Nafion or polybenzimidazole (PBI), but is not limited thereto. However, it should be understood that any suitable material or combination of materials can be used as long as the components can function in the manner described herein.

[0008] The first and second current collectors 130 and 140 electrically connect the anodes and cathodes of the multiple electrochemical cells 120 to a power source (not shown) to maintain the positive potential of the anodes and the negative potential of the cathodes.

[0009] The input line 150 is configured to receive a first gas mixture from a source (not shown) located away from the electrochemical hydrogen pump 100 and to send the first gas mixture to the anode chambers 122 of a plurality of electrochemical cells 120. The output line 160 is configured to receive a second gas mixture from the cathode chambers 124 of multiple electrochemical cells 120 and to send the second gas mixture to a desired location (not shown) away from the electrochemical hydrogen pump 100.

[0010] The precise physical / chemical mechanism behind the operation of the electrochemical cell 120 is well known and will not be detailed herein for the sake of brevity. However, briefly, during the operation of the electrochemical hydrogen pump 100, hydrogen gas in the first gas mixture is oxidized at the anode in the anode chamber 122 to produce hydrogen ions. These hydrogen ions then enter the cathode chamber 124 through the ion exchange mechanism 126, where they undergo a reduction reaction and are reformed into hydrogen gas. The ion exchange mechanism 126 selectively allows hydrogen ions to pass through but substantially prevents other components of the first gas mixture from passing through, so the concentration of hydrogen gas in the second gas mixture increases compared to the concentration of hydrogen gas in the first gas mixture. Thus, hydrogen gas is effectively selectively pumped (or separated) from the first gas mixture by the electrochemical cell 220.

[0011] Figure 2 is a schematic diagram (not to scale) showing a more detailed cross-sectional view of the ion exchange mechanism 126. The ion exchange mechanism forms part of a membrane electrode assembly (MEA) comprising an anode, a cathode, an ion exchange membrane 126a, an anode catalyst layer 126b, a cathode catalyst layer 126c, an anode gas diffusion layer 126d, and a cathode gas diffusion layer 126e. In some embodiments, the anode catalyst layer 126b is the anode of the MEA. In some embodiments, the cathode catalyst layer 126c is the cathode of the MEA. The ion exchange membrane 126a is sandwiched between the anode catalyst layer 126b and the cathode catalyst layer 126c. The anode catalyst layer 126b is sandwiched between the ion exchange membrane 126a and the anode gas diffusion layer 126d. The cathode catalyst layer 126c is sandwiched between the ion exchange membrane 126a and the anode gas diffusion layer 126e. In other words, the ion exchange membrane 126a, the anode catalyst layer 126b, the cathode catalyst layer 126c, the anode gas diffusion layer 126d, and the cathode gas diffusion layer 126e form a layered stack that acts as an ion exchange mechanism. The exact way in which the MEA functions is well known and, for the sake of brevity, will not be described in further detail herein. [Overview of the Initiative] [Problems that the invention aims to solve]

[0012] It is desirable to improve the conventional electrochemical hydrogen pump 100 described above. [Means for solving the problem]

[0013] In a first embodiment, a multistage electrochemical hydrogen pump is provided, comprising a first electrochemical hydrogen pump stage fluidly connected to a second electrochemical hydrogen pump stage. The first electrochemical pump stage is configured to receive a first gas mixture containing hydrogen gas, electrochemically separate the hydrogen gas from the first gas mixture to produce a second gas mixture, and output the second gas mixture to the second electrochemical pump stage. The second electrochemical hydrogen pump stage is configured to receive the second gas mixture from the first electrochemical hydrogen pump stage, electrochemically separate the hydrogen gas from the second gas mixture to produce a third gas mixture, and output the third gas mixture.

[0014] One or both of the first and second electrochemical hydrogen pump stages may comprise a plurality of electrochemical cells fluidly connected to each other in parallel.

[0015] Multiple electrochemical cells in one or both of the first and second electrochemical hydrogen pump stages can be arranged as a stack.

[0016] Each of the first and second electrochemical hydrogen pump stages may comprise a plurality of electrochemical cells fluidly connected to each other in parallel.

[0017] The output of each of the multiple electrochemical cells of the first electrochemical hydrogen pump stage can be fluidly connected to the input of each of the multiple electrochemical cells of the second electrochemical hydrogen pump stage.

[0018] The first and second electrochemical hydrogen pump stages can be fluidly connected to each other via a fluid line or via a flow path defined by a bipolar plate.

[0019] The multi-stage electrochemical hydrogen pump can further include a housing, and the first and second electrochemical hydrogen pump stages are disposed within the housing.

[0020] The second gas mixture has a higher proportion of hydrogen gas compared to the first gas mixture, and the third gas mixture has a higher proportion of hydrogen gas compared to the second gas mixture.

[0021] The first gas mixture can be composed of hydrogen gas and one or more other types of gases, and the one or more other types of gases are selected from the group consisting of nitrogen gas, carbon dioxide gas, helium gas, argon gas, and carbon monoxide gas.

[0022] The hydrogen gas can include one or more of protium, deuterium, and tritium.

[0023] The multi-stage electrochemical hydrogen pump can further include one or more additional electrochemical hydrogen pump stages fluidly connected in series to the first and second electrochemical hydrogen pump stages. 8]

[0024] In a second aspect, a vacuum pump system including the multi-stage electrochemical hydrogen pump of the first aspect is provided.

[0025] The multi-stage electrochemical hydrogen pump can be fluidly connected to a vacuum pump and configured to receive the first gas mixture from the vacuum pump.

[0026] In a third aspect, an extreme ultraviolet lithography system including the vacuum pump system of the second aspect is provided.

[0027] The first gas mixture can be composed of hydrogen gas and nitrogen gas.

[0028] In a fourth aspect, the use of the multi-stage electrochemical hydrogen pump of the first aspect is provided. 8]]

Brief Description of the Drawings

[0029] [Figure 1] This is a schematic diagram of a conventional electrochemical hydrogen pump (not to scale). [Figure 2] This is a schematic diagram (not to scale) showing a cross-section of the ion exchange mechanism of a conventional electrochemical hydrogen pump. [Figure 3] This is a schematic diagram (not to scale) showing a multi-stage electrochemical hydrogen pump. [Figure 4] This is a schematic diagram (not to scale) showing another multi-stage electrochemical hydrogen pump. [Modes for carrying out the invention]

[0030] Figure 3 is a schematic diagram (not to scale) showing a multi-stage electrochemical hydrogen pump 200 according to one embodiment. The electrochemical hydrogen pump 200 comprises a housing 210, a first electrochemical hydrogen pump stage 300, a second electrochemical hydrogen pump stage 400, a first current collector 230, and a second current collector 240.

[0031] The housing 210 defines the space in which the remaining components of the electrochemical hydrogen pump 200 are located. Specifically, the first electrochemical hydrogen pump stage 300, the second electrochemical hydrogen pump stage 400, the first current collector 230, and the second current collector 240 are located in the space defined by the housing 110.

[0032] The first electrochemical hydrogen pump stage 300 comprises a plurality of first electrochemical cells 220a, a first input line 250a, and a first output line 260a. Each of the multiple first electrochemical cells 220a is configured to receive a first gas mixture containing hydrogen gas, electrochemically separate the hydrogen gas from the first gas mixture, and output a second gas mixture containing the separated hydrogen gas.

[0033] The hydrogen gas in the first and second gas mixtures may contain one or any combination of different isotopes of hydrogen (i.e., protium, deuterium, and tritium).

[0034] Multiple first electrochemical cells 220a are arranged in a stack and fluidly connected to one another in parallel. Each of the multiple first electrochemical cells 220a comprises a first anode chamber 222a, a first cathode chamber 224a, and a first ion exchange mechanism 226a. Each first anode chamber 222a is equipped with an anode and configured to receive a first mixed gas from a first input line 250a. Each first cathode chamber 224a is equipped with a cathode and configured to output a second mixed gas to a first output line 260a. Each first ion exchange mechanism 226a is positioned between the respective first anode and cathode chambers 222a and 224a, separating them from each other, and acts as a partial barrier to the fluid flow between the respective first anode and cathode chambers 222a and 224a. The first ion exchange mechanism 226a of each first electrochemical cell 220a is semipermeable and configured to selectively allow hydrogen ions to pass through it to move from the respective first anode chamber 222a to the respective first cathode chamber 224a, but substantially prevent other components of the first gas mixture from passing through it. Each first ion exchange mechanism 226a has the same structure as the ion exchange mechanism 126 described above with reference to Figure 2.

[0035] The first mixed gas consists of hydrogen gas mixed with one or more other types of gases (e.g., nitrogen, carbon dioxide, helium, argon, carbon monoxide). For example, the first mixed gas can be 50% hydrogen gas and 50% one or more other types of gases. The second gas mixture is the product of electrochemical hydrogen separation carried out by the first electrochemical cell 220a and has a much higher proportion of hydrogen gas compared to the first gas mixture. Specifically, the second gas mixture consists almost entirely of hydrogen gas, but still contains trace amounts of one or more other types of gases that somehow managed to pass through the first ion exchange mechanism 226, for example, due to the imperfections in the selective permeability of the first ion exchange mechanism 226. For example, the second mixed gas may have about 100 ppm (parts per million) of one or more other types of gases (i.e., impurities or contaminants), with the remainder being hydrogen gas.

[0036] The first input line 250a is configured to receive a first gas mixture from a source (not shown) located away from the electrochemical hydrogen pump 200 and to deliver the first gas mixture to the first anode chambers 222a of a plurality of first electrochemical cells 220a. The first input line 250a is a fluid line, and is, for example, a pipe or tube made of some suitable material.

[0037] The first output line 260a is configured to receive the second gas mixture from the first cathode chambers 224a of a plurality of first electrochemical cells 220a and to send the second gas mixture to the second electrochemical hydrogen pump stage 400. The first output line 260a is a fluid line, and is, for example, a pipe or tube made of some suitable material.

[0038] The second electrochemical hydrogen pump stage 400 comprises a plurality of second electrochemical cells 220b, a second input line 250b, and a second output line 260b.

[0039] Each of the multiple second electrochemical cells 220b is configured to receive a second gas mixture, electrochemically separate hydrogen gas from the second gas mixture, and output a third gas mixture containing the separated hydrogen gas. The multiple second electrochemical cells 220b are arranged in a stack and fluidly connected to one another in parallel. Each of the multiple second electrochemical cells 220b comprises a second anode chamber 222b, a second cathode chamber 224b, and a second ion exchange mechanism 226b. Each second anode chamber 222b is equipped with an anode and is configured to receive a second mixed gas from a second input line 250b. Each second cathode chamber 224b is equipped with a cathode and is configured to output a third mixed gas to a second output line 260b. Each second ion exchange mechanism 226b is positioned between the respective second anode and cathode chambers 222b and 224b, separating them from each other, and acts as a partial barrier to the fluid flow between the respective second anode and cathode chambers 222b and 224b. The second ion exchange mechanism 226b of each second electrochemical cell 220b is semipermeable and configured to selectively allow hydrogen ions to pass through it to move from the respective second anode chamber 222b to the respective second cathode chamber 224b, but substantially prevent other components of the second gas mixture from passing through it. Each second ion exchange mechanism 226b has the same structure as the ion exchange mechanism 126 described above with reference to Figure 2.

[0040] The third gas mixture is the product of a further stage of electrochemical hydrogen separation carried out by the second electrochemical cell 220b, and has a higher proportion of hydrogen gas compared to the second gas mixture. In other words, the third gas mixture has a lower proportion of non-hydrogen gases than the second gas mixture. For example, the third gas mixture contains approximately 40 ppb (parts per billion) of impurities or contaminants, with the remainder being hydrogen gas.

[0041] The second input line 250b is fluidically connected to the first output line 260a. The second input line 250b is configured to receive the second gas mixture from the first output line 160a of the first electrochemical hydrogen pump stage 300 and to send the second gas mixture to the second anode chambers 222b of a plurality of second electrochemical cells 220b. The second input line 250b is a fluid line, and is, for example, a pipe or tube made of some suitable material.

[0042] The second output line 260b is configured to receive the third gas mixture from the second cathode chambers 224b of a plurality of second electrochemical cells 220b and to send the third gas mixture to a desired location (not shown) away from the electrochemical hydrogen pump 200. The second output line 260b is a fluid line, and is, for example, a pipe or tube made of some suitable material.

[0043] The first and second current collectors 230 and 240 electrically connect the negative and positive electrodes of the first and second electrochemical cells 220a and 220b to a power source (not shown), maintaining the positive charge of the negative electrode and the negative charge of the positive electrode.

[0044] The precise physical / chemical mechanisms behind the operation of the first and second electrochemical cells 220a and 220b are well known and will not be detailed herein for the sake of brevity. However, briefly, during the operation of the electrochemical hydrogen pump 200, hydrogen gas in the first mixed gas is oxidized at the anodes of the first and second anode chambers 222a and 222b to produce hydrogen ions. These hydrogen ions then enter the first and second cathode chambers 224a and 224b through the first and second ion exchange mechanisms 226a and 226b, where they undergo a reduction reaction at the cathode and are reformed into hydrogen gas. The first and second ion exchange mechanisms 226a and 226b selectively allow hydrogen ions to pass through them, but substantially block other components of the first and second gas mixtures from passing through them. As a result, the concentration of hydrogen gas in the second gas mixture increases more than that in the first gas mixture, and the concentration of hydrogen gas in the third gas mixture increases more than that in the second gas mixture. Thus, hydrogen gas is effectively and selectively pumped (or separated) from the first and second gas mixtures by the first and second electrochemical cells 220a and 220b, respectively.

[0045] Figure 4 is a schematic diagram (not to scale) showing a multistage electrochemical hydrogen pump 500 according to another embodiment. The embodiment in Figure 4 is the same as the embodiment in Figure 3, except that instead of using fluid lines, the anode and cathode chambers are fluidly connected via channels and holes defined (or machined into) by bipolar plates (not shown) that sandwich each electrochemical cell. In this embodiment, each electrochemical cell is sandwiched between a pair of bipolar plates, and each of the anode and cathode chambers of each electrochemical cell is defined between one of the pair of bipolar plates and the ion exchange mechanism of that electrochemical cell.

[0046] More specifically, the first anode chambers of the first electrochemical hydrogen pump stage are in fluid communication with each other via a first flow path 510a extending through a bipolar plate and first holes 520a in the bipolar plate. The first anode chambers are configured to receive a first mixed gas from a source located away from the electrochemical hydrogen pump 500 via the first flow path 510a and the first holes 520a.

[0047] The second cathode chambers of the second electrochemical hydrogen pump stage are in fluid communication with each other via a second flow path 510b extending through the bipolar plate and second holes 520b in the bipolar plate. The second cathode chambers are configured to output a third mixed gas to the outside of the electrochemical hydrogen pump 500 via the second holes 520b and the second flow path 510b.

[0048] The first cathode chambers of the first electrochemical hydrogen pump stage are in fluid communication with each other via a third flow channel 510c extending through a bipolar plate and third holes 520c in each of the bipolar plates. The first cathode chambers are configured to output a second mixed gas to the third flow channel 510c via the third holes 520c.

[0049] The second anode chambers of the second electrochemical hydrogen pump stage are in fluid communication with each other via the third flow path 510c and their respective fourth holes 520d. The second anode chambers are configured to receive the second mixed gas from the third flow path 510c via the fourth holes 520d.

[0050] The first cathode chamber of the first electrochemical hydrogen pump stage and the second anode chamber of the second electrochemical hydrogen pump stage are in fluid communication with each other via a third flow path 510c. The third flow path 510c is configured to deliver the second mixed gas from the first cathode chamber of the first electrochemical hydrogen pump stage to the second anode chamber of the second electrochemical hydrogen pump stage. Advantageously, the embodiment in Figure 4 is relatively compact and utilizes a method of fluidically connecting two electrochemical hydrogen pump stages without using fluid lines such as pipes to perform the functions described above. In this way, a multi-stage electrochemical hydrogen pump is provided.

[0051] The multistage electrochemical hydrogen pump described above can be used to supply hydrogen gas in any suitable system that requires it. For example, the multistage electrochemical hydrogen pump described above can be used as part of an extreme ultraviolet (EUV) lithography system. Specifically, the multistage electrochemical hydrogen pump can be part of the vacuum pump system of an EUV lithography system, configured to receive a first gas mixture from the vacuum pump and output a third gas mixture to where it is needed in the EUV lithography system. An example of such a location would be the input section of an EUV lithography tool as part of a semi-closed-loop hydrogen recycling process. The EUV tool requires a large amount of hydrogen, which is eventually discharged (along with impurities) through a vacuum exhaust system. By removing impurities and pressurizing the hydrogen with a multistage electrochemical pump, hydrogen that would normally be discarded as contaminated waste can be reused in the EUV lithography tool. In an EUV lithography system, the first gas mixture can consist of hydrogen gas and nitrogen gas.

[0052] Advantageously, the multi-stage electrochemical hydrogen pump described above tends to output a final mixed gas with a higher proportion of hydrogen gas compared to the conventional single-stage electrochemical hydrogen pump shown in Figure 1. In other words, the final mixed gas (i.e., the third mixed gas) output by the multi-stage electrochemical hydrogen pump described above tends to contain less non-hydrogen gas (i.e., contaminants or impurities). For example, tests have shown that the output of the multi-stage electrochemical hydrogen pump described above, referring to Figures 3 and 4, tends to have 40 ppb of impurities, while the output of the single-stage electrochemical hydrogen pump described above, referring to Figure 1, tends to have 100 ppm of impurities (i.e., about 2500 times the output of the multi-stage pump). Therefore, the multi-stage electrochemical hydrogen pump described above tends to have a much higher purity output than the conventional single-stage electrochemical hydrogen pump. For this reason, the use of multi-stage electrochemical pumps tends to be particularly beneficial in systems that require very high purity hydrogen gas, such as extreme ultraviolet (EUV) lithography systems.

[0053] In the above-described embodiment, the multistage electrochemical hydrogen pump has only two electrochemical hydrogen pump stages connected in series. However, in other embodiments, three or more electrochemical hydrogen pump stages connected in series are used to further reduce the proportion of impurities or contaminants in the gas output by the multistage electrochemical hydrogen pump. [Explanation of Symbols]

[0054] 100, 200, 500 Electrochemical Hydrogen Pumps 110, 210 Housing 120, 220a, 220b electrochemical cells 122, 222a, 222b Anode chamber 124, 224a, 224b cathode chamber 126, 226a, 226b Ion exchange mechanism 126a Ion exchange membrane 126b Anode catalyst layer 126c Cathode catalyst layer 126d Anode gas diffusion layer 126e Cathode gas diffusion layer 130, 230 First current collector 140, 240 Second current collector 150, 250a, 250b input lines 160, 260a, 260b output lines 300 First electrochemical hydrogen pump stage 400 Second electrochemical hydrogen pump stage 510a First channel 510b Second channel 510c Third channel 520a First hole 520b Second hole 520c Third hole 520d Fourth hole

Claims

1. A multistage electrochemical hydrogen pump comprising a first electrochemical hydrogen pump stage fluid-connected to a second electrochemical hydrogen pump stage, The first electrochemical hydrogen pump stage is configured to receive a first gas mixture containing hydrogen gas, electrochemically separate the hydrogen gas from the first gas mixture to produce a second gas mixture, and output the second gas mixture to the second electrochemical hydrogen pump stage. The second electrochemical hydrogen pump stage is configured to receive the second gas mixture from the first electrochemical hydrogen pump stage, electrochemically separate hydrogen gas from the second gas mixture to produce a third gas mixture, and output the third gas mixture. The first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage, or both thereof, comprise a plurality of electrochemical cells fluidly connected to each other in parallel. The plurality of electrochemical cells in one or both of the first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage are arranged as a stack. Each of the first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage comprises a plurality of electrochemical cells fluidly connected in parallel to each other, and the output of each of the plurality of electrochemical cells of the first electrochemical hydrogen pump stage is fluidly connected to the input of each of the plurality of electrochemical cells of the second electrochemical hydrogen pump stage. The first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage are fluidly connected to each other via channels and holes defined by or machined into a bipolar plate. A multi-stage electrochemical hydrogen pump, each of which comprises multiple electrochemical cells, an anode chamber, a cathode chamber, and an ion exchange mechanism, wherein the anode and cathode chambers are fluidly connected via channels and holes defined by or machined into bipolar plates flanking each electrochemical cell.

2. The multistage electrochemical hydrogen pump according to claim 1, further comprising a housing, wherein the first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage are arranged within the housing.

3. The multistage electrochemical hydrogen pump according to claim 1 or 2, wherein the second gas mixture has a higher proportion of hydrogen gas than the first gas mixture, and the third gas mixture has a higher proportion of hydrogen gas than the second gas mixture.

4. The multistage electrochemical hydrogen pump according to any one of claims 1 to 3, wherein the first gas mixture comprises hydrogen gas and one or more other types of gas, the one or more other types of gas being selected from the group consisting of nitrogen gas, carbon dioxide gas, helium gas, argon gas, and carbon monoxide gas.

5. The multistage electrochemical hydrogen pump according to any one of claims 1 to 4, wherein the hydrogen gas comprises one or more of protium, deutherium, and tritium.

6. A multistage electrochemical hydrogen pump according to any one of claims 1 to 5, further comprising one or more further electrochemical hydrogen pump stages fluidly connected in series with the first electrochemical hydrogen pump stage and the second electrochemical hydrogen pump stage.

7. A vacuum pump system comprising a multi-stage electrochemical hydrogen pump according to any one of claims 1 to 6.

8. The vacuum pump system according to claim 7, wherein the multistage electrochemical hydrogen pump is fluidly connected to a vacuum pump and configured to receive the first gas mixture from the vacuum pump.

9. An extreme ultraviolet lithography system comprising the vacuum pump system according to claim 7 or 8.

10. The extreme ultraviolet lithography system according to claim 9, wherein the first gas mixture comprises hydrogen gas and nitrogen gas.

11. Use of a multistage electrochemical hydrogen pump according to any one of claims 1 to 6 for pumping hydrogen gas.

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