Composite flow plate for electrolytic cell
A flow plate for use as an anode current collector in an electrolytic cell for the production of hydrogen from water is provided. The flow plate comprises a channel plate and a cover plate. A front face of the channel plate is provided with a flow field pattern of open-faced channels defined by depressed portions alternating with elevated portions. The cover plate made of a material that is corrosion resistant in an anodic environment of water electrolysis. The cover plate is arranged parallel on top of the channel plate and in electrical contact with the front face thereof. The cover plate is further provided with a pattern of through-going apertures alternating with closed portions, and the closed portions cover at least the elevated portions of the channel plate.
1. Electrolytic cell for the production of hydrogen from water by electrolysis, the electrolytic cell comprising
a planar membrane electrode assembly (MEA) with a polymer electrolyte membrane (PEM) sandwiched between an anode and a cathode,
on the anode side, an anode side fluid distribution medium in contact with the anode, an anode current collector in contact with the anode side fluid distribution medium,
on the cathode side, a cathode side fluid distribution medium in contact with the cathode, and a cathode current collector in contact with the cathode side fluid distribution medium, wherein
the anode current collector is a flow plate comprising a channel plate made of a carbon/graphite compound connectable to a water source, wherein a front face of the channel plate is provided with a flow field pattern of open-faced channels for water distribution defined by depressed portions alternating with elevated portions, and a cover plate made of a material that is corrosion resistant in an anodic environment of water electrolysis, wherein the cover plate is arranged parallel on top of the channel plate and in electrical contact with the front face thereof, wherein the cover plate is provided with a pattern of through-going apertures to handle fine distribution of water over an anode surface of an MEA alternating with closed portions, wherein the pattern of through-going apertures is aligned with the depressed portions, and wherein the closed portions cover at least the elevated portions of the channel plate; and
a water source connected to the channels of the flow plate.
2. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the flow field pattern on the channel plate is a system of inter-digitized feed and drain channels for water,
wherein each of the feed channels for water has an upstream end that is connected to at least one feed port for water via at least one feed manifold connectable to a water source, and has a downstream end that terminates on the channel plate,
wherein each of the drain channels for water has an upstream end that terminates on the channel plate and a downstream end that is connected to at least one drain port for water via at least one drain manifold, and
wherein the apertures in the cover plate are arranged as an inter-digitized pattern of feed and drain apertures corresponding to the inter-digitized pattern of feed and drain channels.
3. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 2 , wherein the at least one feed manifold and the at least one drain manifold are arranged on opposite portions of the periphery of the channel plate, and wherein the lateral distance between adjacent feed and drain channels in the inter-digitized flow field on the front face of the channel plate is smaller in a centre portion as compared to a peripheral portion of the channel plate.
4. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the width of the apertures in the cover plate is less than the width of the underlying channels in the channel plate.
5. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the width of the apertures in the cover plate is less than 0.5 mm, or between 0.1 mm and 0.5 mm.
6. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the cover plate has a thickness of at least 0.2 mm, or between 0.2 mm and 3 mm, alternatively between 0.3 mm and 1.5 mm, alternatively between 0.5 mm and 1 mm.
7. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the cover plate is made of stainless steel, titanium, or a titanium alloy.
8. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the channels on the front face have a depth of between 0.3 mm and 1 mm.
9. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the channel has at the top plane a width of between 0.3 mm and 3 mm.
10. Electrolytic cell for the production of hydrogen from water by electrolysis according to claim 1 , wherein the flow plate is generally circular as seen in a vertical direction.
11. Electrolytic cell according to claim 1 , wherein the anode current collector and the cathode current collector are on respective bipolar separator plates.
12. Electrolytic cell according to claim 1 , wherein a minimum distance r between the anode and inner surfaces of the channels of the channel plate exceeds 1 mm.
13. Stacked cell electrolyser for the production of hydrogen from water by electrolysis, wherein the electrolyser is formed as a stack of electrolytic cells according to claim 11 .