GB2469265A

GB2469265A - Electrode configuration of electrolysers to protect catalyst from oxidation.

Info

Publication number: GB2469265A
Application number: GB0905808A
Authority: GB
Inventors: Amitava Roy
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-04-06
Filing date: 2009-04-06
Publication date: 2010-10-13
Anticipated expiration: 2029-04-06
Also published as: US20120031753A1; GB2469265B; GB0905808D0; HK1148792A1; GB2469265B8

Abstract

An electrode configuration for a water electrolyser wherein the anode and cathode are coated with a protective material which protects the active catalysts when the apparatus is not in use or is in standby mode. The anode is coated with a material defined as an "oxygen storage material" such that the coating is preferentially oxidised over the anodic active catalyst. The material may be cerium dioxide (ceria) or zirconium. The cathode is coated with a material defined as a "hydrogen storage material" which supplies or releases hydrogen when the electrolyses is not in use. When the electrolyser is not in use a reduction load is connected between the anode and cathode which converts metal oxides into pure metal by consuming oxygen from the electrolyser cell and hydrogen released by the hydrogen storage material. The coatings will increase the life time and durability of electrodes.

Description

Title: Electrode configuration of electrolysers to protect catalyst from oxidation.

Description:

Field of Invention:

[001] Renewable energy powered electrolysers for hydrogen production.

[002] Electrolysers powered by renewable energy sources produce hydrogen gas which can be used as transport fuel or backup electricity generation by fuel cells.

[003] However, the current electrolyser technology is not matured for dynamic and intermittent operation, which suffers from early failures compared to long life in smooth, steady state operation.

[004] Conventional alkaline electrolysers have limited on-off switching cycle for example only 2500 cycles in the state of the art conventional electrolyser for intermittent operation which are primarily used for steady state smooth operation in industrial applications.

[005] During stand-by mode and shut-down mode oxygen remains trapped inside the porous anodic catalyst layer and other parts of the electrolyser cell which then creates a high open circuit voltage in contact with conductive KOH electrolyte against the reference platinum electrode.

[006] At high open circuit voltage during stand-by mode and shut-down mode anodic active catalyst is gradually oxidised thus the catalytic activity of anodes is decreased, leading to greater electrochemical losses and increased cell voltage which then increases the energy consumption of electrolyser per unit volume of hydrogen production.

[0071 This in turn increases the energy consumption of electrolysers by more than 10% within a year.

[0081 The guaranteed quota of 2500 cycles in conventional electrolysers is generally consumed in less than a year for on-off switching cycle by 7 times per day which is unsuitable for renewable energy powered intermittent operation because the electrolyser should be capable for unlimited on-off switching cycle within its lifetime for renewable energy powered intermittent operation.

[0091 Some electrolysers available in the market apply a small cunent across the cell called protective current to prevent corrosion or oxidation of catalyst.

[010] The protective current is a very small direct current passing through the stack during the stand-by mode in order to maintain the flow of current in one direction.

[011] However, this approach is not feasible due to the limited operating range from 20-100% of alkaline electrolysers.

[012] A separate power supply for example a battery is required to apply protective cunent.

[013] However, another major concern of protective current is hydrogen and oxygen gas permeate through the membrane and creates a potentially explosive mixture over a period of time as the produced gas is not taken out of the cell or consumed.

[014] This then requires frequent purging of the cell, followed by nitrogen purging at start up stage of the electrolyser.

[015] All these issues make protective cunent practically unfeasible or difficult to apply.

[016] As a result current electrolysers are less compatible for renewable energy powered operation and as an example, the electrolyser used in a demonstration project of hydrogen and renewable integration at West Beacon Farm, Loughborough, Leicestershire, UK has been replaced due to stack failure within 2000 on-off switching cycle and the replaced second stack has also suffered a similar degradation.

[017] Therefore a solution must be found which prevents oxidation of catalyst in stand-by and shut-down mode and due to on-off switching.

Background to the Invention:

[018] The invention relates to an electrode configuration to protect active catalyst from oxidation in electrolysers by using oxygen storage materials in contact with anodic active catalyst as a preventive measure as shown in figure 1, where the oxygen storage material will be preferentially oxidised prior to the active catalyst.

[019] During stand-by mode at open circuit voltage the oxygen storage material will preferentially be oxidised than the anodic active catalyst due to close physical contact between the catalyst and oxygen storage materials.

[020] The close contact between the anodic active catalyst and oxygen storage material is ensured by different manufacturing techniques.

[021] For example the oxygen storage material is deposited first on to the anodic perforated current collector as shown in figure 1 by various methods for example, spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc, followed by depositing the anodic active catalyst on top of oxygen storage material layer by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [022] The thickness of each layer of anodic active catalyst layer, oxygen storage layer or the combined layer of anodic active catalyst and oxygen storage material is in the range of less than one micron to few millimetre with nominal thickness of 25-500 micron.

[023] The surface area of the anodic active catalyst and oxygen storage material can vary from less than 1m2/g to 1000m2/g.

[024] The current collector is normally perforated or highly porous with open area in the range from 20% to 80%.

[025] The invention further relates to reduction of oxides in situ from electrodes during stand-by and shut down mode of electrolysers using a diode assisted unidirectional reduction load to bring the electrode potentials to zero with respect to the Pt reference electrode.

[026] During operation over a period of time if any part of the active catalyst is oxidised, then catalyst-oxides is removed by means of the reduction load.

[027] The reduction load is a small resistor connected across the positively charged anode and negatively charged cathode, whose value can vary from less than imilli-Ohm to several mega-Ohm depending on the capacity of the stack.

[028] During electrolyser operation some hydrogen is stored in cathodes in the form of metal hydride and oxygen is stored in anodes in the form of oxides and oxygen ion in the active catalyst and oxygen storage materials.

[029] The presence of oxygen in anodes creates a high open circuit voltage which is 1V measured against a Pt reference electrode.

[030] The reduction load connected across the anode and cathode of the electrolyser consumes hydrogen and oxygen in a fuel cell mode to produce a current density from less than lmA/cm2 to 2OmA/cm2, through the reduction load.

[031] The reduction load can be applied in constant current mode or in constant power mode.

[032] The half cell voltage of oxygen electrode will drop rapidly from its open circuit voltage and therefore the anodic metal oxide converts into pure metal by breaking the oxides under reducing voltage to supply oxygen to the fuel cell reaction through the reduction load.

[033] The configuration of reduction load can have a sophisticated electronic circuit using of diodes, capacitors and other electronic components to ensure the direction of electron flow through the reduction load from hydrogen producing/consuming electrode which is cathode in the electrolyser mode to the oxygen producing/consuming electrode which is anode in the electrolyser mode.

[034] The invention also relates to the use of hydrogen storage material in cathodes as shown in figure 4 to supply adequate hydrogen to consume all the oxygen when the reduction load is applied.

[035] The presence of hydrogen will create a reducing condition and thus it will protect cathodes from oxidation during intermittent operation, shut down and stand by mode.

[036] These inventions allow electrolysers to undertake increased on-off switching cycle over a long period of time by repeated reduction of the oxides which makes them suitable for renewable energy powered dynamic and intermittent operation.

Description of the Invention:

[037] This invention describes an electrode configuration of electrolysers which increases the on-off switching cycle without degradation over a long period of time.

[038] Firstly, oxygen storage material causes preferential oxidation as a preventive measure.

[039] Secondly, the application of reduction load converts metal oxides back to pure metal catalyst by consuming oxygen from anodes in a fuel cell reaction which is done by connecting the anode and cathode together using a resistive load.

[040] Electricity will be produced when the anodes and cathodes of an electrolyser is directly connected via a resistive reduction load soon after its operation due to recombination of hydrogen and oxygen present in electrodes.

[041] The invention relates to the use of hydrogen and oxygen storage materials which would facilitate to break metal oxides into pure active metal catalyst in order to supply oxygen for the fuel cell reaction.

Example specification 1

[042] The figure 1 shows the first example of one of the various electrode configurations described under this invention.

[043] As per figure 1, Oxygen storage material (3) is deposited on to anodic perforated current collector (4) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [044] As per figure 1, the anodic active catalyst (2) is then deposited on top of oxygen storage material (3) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [045] As per figure 1, the complete anode structure is then placed on one side of porous separator (1).

[046] As per figure 1, the anode monopolar plate (5) is compressed to the back of anodic perforated current collector (4) for supplying electricity and taking oxygen gas out of the cell.

[047] As per figure 1, cathodic active catalyst (6) is deposited on to cathodic perforated current collector (7) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [048] As per figure 1, the cathode monopolar plate (8) is compressed to the back of the cathodic perforated current collector (7) for supplying electricity and taking hydrogen gas out of the cell.

[049] As per figure 1, this combined configuration with one anode comprising with anode monopolar plate (5), anodic perforated current collector (4), oxygen storage material (3) and anodic active catalyst (2) is placed one side of the porous separator (1).

[050] As per figure 1, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (8), cathodic perforated current collector (7) and cathodic active catalyst (6) is placed to construct a complete electrolyser cell.

Example specification 2

[051] The figure 2 shows the second example of one of the various electrode configurations described under this invention.

[052] As per figure 2, the anodic active catalyst (2) is deposited on to anodic perforated current collector (4) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [053] As per figure 2, oxygen storage material (3) is then deposited on top of anodic active catalyst (2) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [054] As per figure 2, the complete anode structure is then placed on one side of porous separator (1).

[055] As per figure 2, the anode monopolar plate (5) is compressed to the back of anodic perforated cunent collector (4) for supplying electricity and taking oxygen gas out of the cell.

[056] As per figure 2, cathodic active catalyst (6) is deposited on to cathodic perforated current collector (7) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electrofoming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [057] As per figure 2, the cathode monopolar plate (8) is compressed to the back of the cathodic perforated culTent collector (7) for supplying electricity and taking hydrogen gas out of the cell.

[058] As per figure 2, this combined configuration with one anode comprising with anode monopolar plate (5), anodic perforated current collector (4), oxygen storage material (3) and anodic active catalyst (2) is placed one side of the porous separator (1).

[059] As per figure 2, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (8), cathodic perforated current collector (7) and cathodic active catalyst (6) is placed to construct a complete electrolyser cell.

Example specification 3

[060] The figure 3 shows the third example of one of the various electrode configurations described under this invention.

[061] As per figure 3, anodic active catalyst and oxygen storage material mixture (2) is deposited on to anodic perforated current collector (3) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [062] As per figure 3, the anode monopolar plate (4) is compressed to the back of anodic perforated cunent collector (4) for supplying electricity and taking oxygen gas out of the cell.

[063] As per figure 3, cathodic active catalyst (5) is deposited on to cathodic perforated current collector (6) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electrofoming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [064] As per figure 3, the cathode monopolar plate (7) is compressed to the back of the cathodic perforated culTent collector (6) for supplying electricity and taking hydrogen gas out of the cell.

[065] As per figure 3, this combined configuration with one anode comprising with anode monopolar plate (4), anodic perforated current collector (3), anodic active catalyst and oxygen storage material mixture (2) is placed one side of the porous separator (1).

[066] As per figure 3, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (7), cathodic perforated current collector (6) and cathodic active catalyst (5) is placed to construct a complete electrolyser cell.

Example specification 4

[067] The figure 4 shows the fourth example of one of the various electrode configurations described under this invention.

[068] As per figure 4, oxygen storage material (3) is deposited on to anodic perforated current collector (4) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [069] As per figure 4, the anodic active catalyst (2) is then deposited on top of oxygen storage material (3) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [070] As per figure 4, the complete anode structure is then placed on one side of porous separator (1).

[071] As per figure 4, the anode monopolar plate (5) is compressed to the back of anodic perforated cunent collector (4) for supplying electricity and taking oxygen gas out of the cell.

[072] As per figure 4, hydrogen storage material (7) is deposited on to cathodic perforated current collector (8) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [073] As per figure 4, the cathodic active catalyst (6) is then deposited on top of hydrogen storage material (7) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [074] As per figure 4, the complete cathode structure is then placed on one side of porous separator (1).

[075] As per figure 4, the cathode monopolar plate (9) is compressed to the back of cathodic perforated current collector (8) for supplying electricity and taking hydrogen gas out of the cell.

[0761 As per figure 4, this combined configuration with one anode comprising with anode monopolar plate (5), anodic perforated current collector (4), oxygen storage material (3) and anodic active catalyst (2) is placed one side of the porous separator (1).

[077] As per figure 4, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (9), cathodic perforated current collector (8), hydrogen storage material (7) and cathodic active catalyst (6) is placed to construct a complete electrolyser cell.

Example specification 5

[078] The figure 5 shows the fifth example of one of the various electrode configurations described under this invention.

[079] As per figure 5, oxygen storage material (3) is deposited on to anodic perforated cunent collector (4) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [080] As per figure 5, the anodic active catalyst (2) is then deposited on top of oxygen storage material (3) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [081] As per figure 5, the complete anode structure is then placed on one side of porous separator (1).

[082] As per figure 5, the anode monopolar plate (5) is compressed to the back of anodic perforated cunent collector (4) for supplying electricity and taking oxygen gas out of the cell.

[0831 As per figure 5, the cathodic active catalyst (6) is deposited on to cathodic perforated current collector (8) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [0841 As per figure 5, hydrogen storage material (7) is then deposited on top of cathodic active catalyst (6) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [0851 As per figure 5, the complete cathode structure is then placed on one side of porous separator (1).

[0861 As per figure 5, the cathode monopolar plate (9) is compressed to the back of cathodic perforated current collector (8) for supplying electricity and taking hydrogen gas out of the cell.

[0871 As per figure 5, this combined configuration with one anode comprising with anode monopolar plate (5), anodic perforated current collector (4), oxygen storage material (3) and anodic active catalyst (2) is placed one side of the porous separator (1).

[0881 As per figure 5, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (9), cathodic perforated current collector (8), cathodic active catalyst (6) and hydrogen storage material (7) is placed to construct a complete electrolyser cell.

Example specification 6

[0891 The figure 6 shows the sixth example of one of the various electrode configurations described under this invention.

[0901 As per figure 6, the anodic active catalyst (2) is deposited on to anodic perforated current collector (3) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [091] As per figure 6, the complete anode structure is then placed on one side of porous separator (1).

[092] As per figure 6, the anode monopolar plate (4) is compressed to the back of anodic perforated current collector (3) for supplying electricity and taking oxygen gas out of the cell.

[093] As per figure 6, the cathodic active catalyst (6) is deposited on to cathodic perforated current collector (7) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [094] As per figure 6, hydrogen storage material (5) is then deposited on top of cathodic active catalyst (6) by various methods for example spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting etc. [095] As per figure 6, the complete cathode structure is then placed on one side of porous separator (1).

[096] As per figure 6, the cathode monopolar plate (8) is compressed to the back of cathodic perforated current collector (7) for supplying electricity and taking hydrogen gas out of the cell.

[097] As per figure 6, this combined configuration with one anode comprising with anode monopolar plate (4), anodic perforated current collector (3) and anodic active catalyst (2) is placed one side of the porous separator (1).

[0981 As per figure 6, on the opposite side of the porous separator (1) one cathode comprising with cathode monopolar plate (8), cathodic perforated current collector (7), cathodic active catalyst (6) and hydrogen storage material (5) is placed to construct a complete electrolyser cell.

[099] The thickness of individual layers in example specification 1 to example specification 6, for porous separator, anodic active catalyst, oxygen storage material, anodic perforated current collector, hydrogen storage material, cathodic active catalyst, cathodic perforated cunent collector, anode monopolar plate and cathode monopolar plate can vary for each layer in the range of less than one micron to few millimetres with nominal thickness of 25-500 micron.

[1001 The surface area of the anodic active catalyst, oxygen storage material, cathodic active catalyst and hydrogen storage material can vary from less than 1m2/g to 1 000m2/g.

[1011 The anodic perforated cunent collector and cathodic perforated current collector have porosity and open area from 10% to 90%.

Summary of invention:

[102] The invention provides various configurations of electrode layers as a protective measure to prevent oxidation of anodic and cathodic active catalyst layer.

[103] Oxygen storage material is used in anodes to be preferentially oxidised than the anodic active catalyst due to close physical contact between the catalyst and oxygen storage materials during normal operation, stand-by mode, shut down mode, at open circuit voltage and intermittent operation due to on-off switching cycle.

[104] Hydrogen storage material is deposited on cathodes in contact with cathodic active catalyst materials to supply hydrogen under the reduction load to react with oxygen supplied from anodes.

[105] A diode assisted unidirectional, resistive reduction load is connected between the anode and cathode during stand by mode and shut down mode to consume oxygen from the electrolyser cell by reacting hydrogen from cathodes and oxygen from anodes and metal oxides.

[106] Hydrogen storage material and the reduction load create reducing conditions and lower the cell voltage than the open circuit voltage to prevent oxidation and to convert oxides into pure metal during stand-by mode, shut down mode, intermittent operation and normal operation of electrolyser powered by renewable energy and other power sources.

[107] The electrode configurations as shown in figure 1 to figure 6 describe some examples of the sequence of each layer from which several others combinations can be made under this innovation.

Claims

Claim(s) To prevent limited on-off switching cycle in conventional electrolysers the present invention uses oxygen storage materials deposited on positively charged anodes of electrolysers in contact with anodic active catalyst materials to prevent oxidation of the anodic active catalyst materials by means of preferential oxidation of oxygen storage materials to allow unlimited on-off switching without corrosion of electrodes during stand-by mode, shut down mode, intermittent operation and normal operation of electrolyser powered by renewable energy and other power sources.
2. The oxygen storage materials and the anodic active catalyst materials of positively charged anodes become partially oxidised over a period of time, which is then reduced to pure metal by connecting a unidirectional, resistive reduction load across the anode and cathode of electrolysers to break the oxides from anodes to supply oxygen to react with hydrogen stored in cathodes.
3. In accordance with claim 1 and claim 2 the use of oxygen storage material and the use of the reduction load to convert the oxides into pure metal by reduction eliminates the use of protective current in stand by mode as in conventional electrolysers and as a result nitrogen purging during stand by mode and start up phase of electrolyser becomes unnecessary.
4. In accordance with claim 1 the oxygen storage materials and the anodic active catalyst materials of anodes is deposited in adjacent layers with direct contact or as a mixture by various techniques such as spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting and other similar techniques.
5. In accordance with claim 1, the thickness of oxygen storage layer and anodic active catalyst layers or the combination of both materials in one layer of the active catalyst and oxygen storage material vary from less than one micron to few millimetres and it is uniformly distributed all over the electrode area.
6. In accordance with claim 1 the oxygen storage materials such as ceria, zirconium and other similar types are used which is preferentially oxidised than various anodic active catalyst such as silver, nickel, alloys of silver and nickel, titanium, platinum, iridium, ruthenium, gold and other suitable catalyst materials for oxygen evolution reactions.
7. In accordance with claim 1 the oxygen storage materials used in anodes can be doped with other materials or combined with other materials suitable for oxygen storage.
8. In accordance with claim 1 the surface area of the active catalyst and oxygen storage material vary from less than 1m2/g to 1000m2/g.
9. In accordance with claim 2 the reduction load is used during stand-by mode, shut down mode, at the start up stage and at open circuit voltage of electrolysers.
10. In accordance with claim 2, unidirectional reduction load has at least a diode and a resistor and any other type of electronic circuit or components for the same purpose of diode as described to ensure the direction of flow of electron from cathodes which produces hydrogen to anodes which produces oxygen.
11. In accordance with claim 2, the open circuit voltage of cathodes against the platinum reference electrodes is lowered to zero volts or close to zero volts by means of the reduction load by consuming oxygen from the metallic oxides from anodes to react with hydrogen from cathodes under the reducing voltage.
12. In accordance with claim 2 the reduction load can be applied in constant current mode or in constant power mode.
13. In accordance with claim 2 and claim 10, hydrogen storage materials is deposited in some configurations as shown in example specification 4 to example specification 6 on the negatively charged cathodes in contact with cathodic active catalyst materials to supply hydrogen under the reduction load to react with oxygen from anodes.
14. In accordance with claim 2 and claim 10, the hydrogen storage material and reduction load create reducing conditions to prevent oxidation and to convert oxides into metal during stand-by mode, shut down mode, intermittent operation and normal operation of electrolyser powered by renewable energy and other power sources.
15. In accordance with claim 13 hydrogen storage materials and the cathodic active catalyst materials of cathodes is deposited in adjacent layers with direct contact or as a mixture by various techniques such as spraying, screen printing, hot pressing, sintering, thermal spraying, electroplating, electroforming, co-deposition by electroplating, electroless plating, dip coating, painting and other similar techniques.
16. In accordance with claim 13, the hydrogen storage material and cathodic active catalyst can be mixed together and then deposited on to cathodic perforated current collector.
17. In accordance with claim 13 the hydrogen storage materials used in cathodes can be doped with other materials or combined with other materials suitable for hydrogen storage.
18. The thickness of individual layer for porous separator, anodic active catalyst, oxygen storage material, anodic perforated current collector, hydrogen storage material, cathodic active catalyst, cathodic perforated cunent collector, anode monopolar plate and cathode monopolar plate can vary in the range of less than one micron to few millimetres with nominal thickness of 25-500 micron.
19. The anodic perforated current collector and cathodic perforated cunent collector have porosity and open area from 10% to 90%.
20. The invention primarily relates to electrolysers of any type for example alkaline, proton exchange membrane, solid oxide etc and the invention is also extended to other electrochemical cells for example fuel cells and battery of any type for example alkaline, acidic, proton exchange membrane, solid oxide etc.
21. In accordance with claim 2, the application of reduction load is canied out manually or automatically for switchover from normal operation to intermittent operation, stand-by mode and start up stage of electrolysers.