Patent Application
20220380915
The present invention relates to an elastic mat used for an alkaline water electrolysis vessel, and more specifically to an elastic mat used for a zero-gap alkaline water electrolysis vessel, to an alkaline water electrolysis vessel provided with this elastic mat, and to a gas production method using this alkaline water electrolysis vessel.
The alkaline water electrolysis method is known as a method of producing hydrogen gas and oxygen gas. In the alkaline water electrolysis method, water is electrolyzed using a basic solution (alkaline water) in which an alkali metal hydroxide (such as NaOH and KOH) dissolves as an electrolytic solution to generate hydrogen gas at a cathode and oxygen gas at an anode. As the electrolysis vessel for the alkaline water electrolysis, an electrolysis vessel including an anode chamber and a cathode chamber which are separated by an ion-permeable separating membrane is known: the anode is disposed in the anode chamber, and the cathode is disposed in the cathode chamber. Further, an electrolysis vessel having a zero-gap configuration (zero-gap electrolysis vessel) is proposed for reducing energy loss: in this configuration, the anode and the cathode are held so as to be in direct contact with the separating membrane.
Conventionally, a zero-gap electrolysis vessel for sodium chloride electrolysis which comprises a separating membrane (920) instead of an ion-exchange membrane has been used as a zero-gap alkaline water electrolysis vessel in general.
Generally, the proportion of an area where zero-gap is achieved (zero-gap area) in the electrode area is desirably high in a zero-gap electrolysis vessel because a large area where zero-gap is not achieved (not in direct contact with the anode or the cathode, and the ion-exchange membrane or the separating membrane) results in a high solution resistance between the electrodes in this area to increase the operating voltage.
Desirably, the electrodes are completely flat for achieving zero-gap. However, the electrodes are likely to bend often due to gravity, dimensional errors, etc. A bending electrode easily results in formation of a gap between the electrode and the membrane. It is considered that a higher contact pressure at which the membrane is sandwiched between and pushed by the electrodes has a greater advantage in view of increasing the proportion of the zero-gap area in the electrode area even when any of the electrodes bends.
However, in a zero-gap electrolysis vessel comprising an ion-exchange membrane, such as a sodium chloride electrolysis vessel, air bubbles generated following the electrolytic reaction vibrate the electrodes and the ion-exchange membrane, which causes the surface of the ion-exchange membrane sandwiched between the electrodes in a zero-gap state to abrade to impair the function of the ion exchange group, so that the ion-exchange capacity of the ion-exchange membrane deteriorates over time, which is problematic. Such a problem of the deterioration of the ion-exchange membrane due to the vibration caused by the generation of air bubbles is particularly prominent when the contact pressure at which the ion-exchange membrane is sandwiched between and pushed by the electrodes is high. An ion-exchange membrane is generally expensive. Accelerated deterioration of the ion-exchange membrane seriously affects the running costs of the electrolysis process unfavorably. Therefore, in a zero-gap electrolysis vessel comprising an ion-exchange membrane, it is required to suppress the contact pressure at which the ion-exchange membrane is sandwiched between and pushed by the electrodes so that the expensive ion-exchange membrane can be used over a long period of time.
For example, Patent Literature 1 discloses “an ion-exchange membrane electrolysis vessel comprising an anode chamber and a cathode chamber which are separated by an anode ion-exchange membrane, wherein an anode is in the anode chamber and a cathode is in the cathode chamber; both the electrodes are closely disposed and face each other with the ion-exchange membrane being therebetween in structure; one of the electrodes is a porous body that has a lot of pores each having an opening area of 0.05 to 1.0 mm2 and a ratio of the pore opening area of 20% or more, and is a flexible porous plate having a bending flexibility of 0.05 mm/g or more; the other electrode is a rigid porous plate; and the electrode of the flexible porous plate is pushed toward the other electrode at a pressure of 20 to 60 g/cm2 by an elastic mat formed of an aggregate of metal wires which has resilience in 50% compressive deformation of 30 to 50 g/cm2 and resilience in 20% compressive deformation of 10 to 30 g/cm2 in elasticity, the elastic mat being obtained by stacking a plurality of wire nets formed by weaving and crimping a stranded wire including two to eight metal wires each having a diameter of 0.02 to 0.09 mm”.
On the contrary, a separating membrane generally used for alkaline water electrolysis is a porous membrane. The ion-exchange mechanism of a porous membrane does not depend on the chemical effect of the ion-exchange group. Thus, it is considered that the ion-exchange capacity of the separating membrane hardly deteriorates even if the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes is high. That is, in a conventional zero-gap alkaline water electrolysis vessel, if the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes can be increased, it is possible to more stably maintain the zero-gap configuration even if the pressure inside the electrolysis vessel changes and it is expectable to increase the proportion of the zero-gap area in the electrode area to improve the energy efficiency without a large decrease in the lifetime of the separating membrane. However, in a conventional zero-gap alkaline water electrolysis vessel, the elastic mat crushes when the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes is tried to be increased, and thus the zero-gap configuration cannot be maintained and the uniformity of the distribution of the contact pressure among the electrodes and the separating membrane deteriorates. The ununiformity of the distribution of the contact pressure among the electrodes and the separating membrane tends to lead to the ununiformity of the electrolytic current on the electrode face. The ununiformity of the distribution of the electrolytic current on the electrode face causes the operating voltage to increase and the energy efficiency to decrease instead.
An object of the present invention is to provide an elastic mat for an alkaline water electrolysis vessel which makes it possible to increase the energy efficiency of an alkaline water electrolysis vessel. An alkaline water electrolysis vessel provided with this elastic mat, and a gas production method using this alkaline water electrolysis vessel are also provided.
The present invention encompasses the following embodiments [1] to [14]:
[1] an elastic mat for an alkaline water electrolysis vessel, the elastic mat comprising:
at least one wire net being woven or knitted with a metal wire and having spring elasticity in a thickness direction thereof,
wherein the metal wire is a solid wire having a diameter of 0.16 to 0.29 mm, or a stranded wire including a plurality of solid wires each having a diameter of 0.08 to 0.15 mm, or any combination thereof;
[2] the elastic mat according [1],
wherein resilience of the elastic mat per unit area when the elastic mat is subjected to 50% compressive deformation is 100 to 450 gf/cm2;
[3] the elastic mat according to [1] or [2],
wherein when the 50% compressive deformation of the elastic mat is repeated twice, resilience of the elastic mat per unit area in a second 50% compressive deformation is no less than 40 gf/cm2;
[4] the elastic mat according to any one of [1] to [3],
wherein the wire net has a wave shape having an amplitude in the thickness direction of the wire net;
[5] the elastic mat according to [4],
the elastic mat comprising a plurality of the wire nets stacked in the thickness direction of the plurality of the wire nets,
wherein each pair of two adjacent wire nets of the plurality of the wire nets are stacked in such a way that ridge parts of the wave shape of a first wire net of the pair and ridge parts of the wave shape of a second wire net of the pair cross each other in a plan view of the elastic mat;
[6] the elastic mat according to any one of [1] to [5],
wherein the elastic mat has a total thickness of 7.5 to 10 mm;
[7] an alkaline water electrolysis vessel comprising:
an anode chamber housing an anode and generating oxygen gas;
a cathode chamber housing a cathode and generating hydrogen gas;
an ion-permeable separating membrane separating the anode chamber and the cathode chamber; and
a first elastic mat being the elastic mat as defined in any one of [1] to [6],
wherein the cathode is a first electrode;
the anode is a second electrode; and
the first electrode is a flexible porous plate, and is pushed toward the second electrode by the first elastic mat;
[8] an alkaline water electrolysis vessel comprising:
an anode chamber housing an anode and generating oxygen gas;
a cathode chamber housing a cathode and generating hydrogen gas;
an ion-permeable separating membrane separating the anode chamber and the cathode chamber; and
a first elastic mat being the elastic mat as defined in any one of [1] to [6],
wherein the anode is a first electrode;
the cathode is a second electrode; and
the first electrode is a flexible porous plate, and is pushed toward the second electrode by the first elastic mat;
[9] the alkaline water electrolysis vessel according to [7] or [8],
wherein the second electrode is a rigid porous plate;
[10] the alkaline water electrolysis vessel according to [9], further comprising:
wherein the second electrode is pushed toward the first electrode by the second elastic mat;
[11] the alkaline water electrolysis vessel according to [7] or [8], further comprising:
a second elastic mat being the elastic mat as defined in any one of [1] to [6],
wherein the second electrode is a second flexible porous plate; and
the second electrode is pushed toward the first electrode by the second elastic mat;
[12] the alkaline water electrolysis vessel according to [7] or [8], further comprising:
an electroconductive rigid current collector contacting the second electrode,
wherein the second electrode is a second flexible porous plate; and
the second electrode is supported by the rigid current collector;
[13] the alkaline water electrolysis vessel according to [12], further comprising:
a second elastic mat being the elastic mat as defined in any one of [1] to [6],
wherein the second electrode is pushed toward the first electrode by the second elastic mat, wherein the rigid current collector is arranged between the second electrode and the second elastic mat; and
[14] a gas production method comprising:
(a) electrolyzing alkaline water by means of the alkaline water electrolysis vessel as defined in any one of [7] to [13],
wherein hydrogen gas and oxygen gas are produced.
An elastic mat for an alkaline water electrolysis vessel according to the first aspect of the present invention comprises a wire net being woven or knitted with a predetermined metal wire, whereby the resilience thereof can be increased. The use of an elastic mat for an alkaline water electrolysis vessel according to the present invention in an alkaline water electrolysis vessel as an electroconductive elastic mat can lead to an increased contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area, so that the energy efficiency of the alkaline water electrolysis vessel can be improved.
In an alkaline water electrolysis vessel according to the second aspect of the present invention, one electrode is pushed toward the other electrode by an elastic mat according to the first aspect of the present invention. This makes it possible to increase the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area, so that the operating voltage can be decreased to improve the energy efficiency.
In a gas production method according to the third aspect of the present invention, electrolysis is carried out by means of an alkaline water electrolysis vessel according to the second aspect of the present invention, so that the operating voltage can be decreased to improve the energy efficiency.
The description of the embodiments as follows will clarify the above-described effects and advantages of the present invention. Hereinafter the embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to these embodiments. The dimensions in the drawings do not always represent exact dimensions. Some reference signs may be omitted in the drawings. In the present description, the expression “A to B” concerning numeral values A and B shall mean “no less than A and no more than B” unless otherwise specified. In such an expression, if a unit is added only to the numeral value B, this unit shall be applied to the numeral value A as well. A word “or” shall mean a logical sum unless otherwise specified. The expression “E1 and/or E2” concerning elements E1 and E2 shall mean “E1, or E2, or the combination thereof”, and the expression “E1, . . . , EN-1, and/or EN” concerning elements E1, . . . , EN (N is an integer of 3 or more) shall mean “E1, . . . , EN-1, or EN, or any combination thereof”.
<1. Elastic Mat for Alkaline Water Electrolysis Vessel>
As shown in
The metal wire 1 is a solid wire having a diameter of 0.16 to 0.29 mm, or a stranded wire including a plurality of solid wires each having a diameter of 0.08 to 0.15 mm, or any combination thereof. In other words, the metal wire 1 may be a solid wire having a diameter of 0.16 to 0.29 mm, and may be a stranded wire including a plurality of solid wires each having a diameter of 0.08 to 0.15 mm. The wire net 10 may be woven or knitted with the solid wire and the stranded wire in combination. For example, the metal wires 1-1, 1-3, . . . 1-(2k−1), . . . may be the solid wires, and the metal wires 1-2, 1-4, . . . 1-(2k), . . . may be the stranded wires (k=1, 2, . . . ).
When the metal wire 1 is the solid wire, the diameter of the solid wire is 0.16 to 0.29 mm as described above, and preferably 0.16 to 0.25 mm. When the metal wire 1 is the stranded wire, the diameter of each of the solid wires included in the stranded wire is 0.08 to 0.15 mm as described above, and preferably 0.08 to 0.12 mm. The respective diameters at the above lower limits or higher can lead to increased spring elasticity of the elastic mat 100, which makes it possible to, when the elastic mat 100 is used in an alkaline water electrolysis vessel, more stably maintain the zero-gap configuration even if the pressure inside the alkaline water electrolysis vessel changes, and to increase the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area, so that the energy efficiency can be improved. The respective diameters at the above upper limits or lower can lead to increased repetitive resilience so that sufficient resilience can be maintained even in long-term use, which makes it possible to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
The number of the solid wires included in the stranded wire is not particularly limited, but is preferably 2 to 4, and can be 2 to 3 in one embodiment. The number of the solid wires included in the stranded wire at the above lower limit or higher can lead to increased spring elasticity of the elastic mat 100, which makes it possible to, when the elastic mat 100 is used in an alkaline water electrolysis vessel, more stably maintain the zero-gap configuration even if the pressure inside the alkaline water electrolysis vessel changes, and to increase the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area, so that the energy efficiency can be improved. The number of the solid wires included in the stranded wire at the above upper limit or lower makes it possible to suppress mechanical damage to the surface of the separating membrane.
An alkali-resistant metal wire of high toughness may be preferably used for the metal wire 1. Further, the metal wire 1 preferably has high electrical conductivity since the elastic mat 100 also functions as a current collector. Preferred examples of such a metal wire include a nickel wire; and low carbon steel wires, stainless steel wires such as SUS304, SUS310, SUS310S, SUS316, SUS316L, and metal wires obtained by nickeling any of them. In one embodiment, a plurality of metal wires of different materials may be used in combination. For example, a low carbon steel wire or a stainless wire that has high toughness but is not excellent in electrical conductivity in particular, and a nickel wire that has high electrical conductivity but is not excellent in toughness in particular may be used in combination. In one embodiment, a stranded wire including a plurality of solid wires of different materials may be used.
The stitch shown in
The metal wire 1-n has a first end part 1-ne and a second end part 1-nf. The process on the end parts of the metal wire 1 are not limited to any specific embodiment.
In one embodiment, the first end part 1-ne of the metal wire 1-n may be joined to the first end part 1-(n+1)e of the metal wire 1-(n+1), which is adjacent to the metal wire 1-n, and the second end part 1-nf of the metal wire 1-n may be joined to the second end part 1-(n+1)nf of the metal wire 1-(n+1), which is adjacent to the metal wire 1-n. A planar wire net 10-pre1 that has one layer being knitted with the metal wires 1-1, 1-2, 1-3, . . . shown in
In another embodiment, the first end part 1-(2k−1)e of the metal wire 1-(2k−1) (k=1, 2, . . . ) may be joined to or continuous with the first end part 1-(2k)e of the metal wire 1-(2k) (k=1, 2, . . . ), which is adjacent to the metal wire 1-(2k−1), and the second end part 1-(2k)f of the metal wire 1-(2k) (k=1, 2, . . . ) may be joined to or continuous with the second end part 1-(2k+1)f of the metal wire 1-(2k+1) (k=1, 2, . . . ), which is adjacent to the metal wire 1-(2k). For example, in
In another embodiment, the first end part 1-ne of the metal wire 1-n may be joined to the second end part 1-nf of the metal wire 1-n. A wire net 10-cyl that is cylindrical as a whole (
In another embodiment, the first end part 1-ne of the metal wire 1-n may be joined to or continuous with the second end part 1-(n+1)f of the metal wire 1-(n+1), which is adjacent to the metal wire 1-n on the downstream side (upper side of the sheet in
The wire net 10 having spring elasticity in the thickness direction thereof (see
The pitch λ of the wave shape of the wire net 10 (space between adjacent ridge parts (ridgelines) R in a plan view of the wire net. See
The resilience of the elastic mat 100 per unit area when the elastic mat 100 is subjected to 50% compressive deformation is preferably 100 to 450 gf/cm2, and more preferably 150 to 300 gf/cm2. The resilience of the elastic mat 100 per unit area when the elastic mat 100 is subjected to 50% compressive deformation at the above lower limit or higher makes it possible to, when the elastic mat 100 is used in an alkaline water electrolysis vessel, more stably maintain the zero-gap configuration even if the pressure inside the alkaline water electrolysis vessel changes, and to further increase the contact pressure at which the separating membrane is sandwiched between and pushed by the electrodes without impairing the uniformity of the contact pressure, to further increase the proportion of the zero-gap area in the electrode area, so that the energy efficiency can be further improved. The resilience of the elastic mat 100 per unit area when the elastic mat 100 is subjected to 50% compressive deformation at the above upper limit or lower makes it easy to further increase the repetitive resilience, to maintain sufficient resilience even in long-term use, and to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term. In the present description, “50% compressive deformation” which the elastic mat is subjected to means that the elastic mat is compressively deformed in the thickness direction, so that the thickness thereof is 50% of the thickness thereof before the deformation.
When the 50% compressive deformation of the elastic mat 100 is repeated twice, the resilience of the elastic mat 100 per unit area in the second 50% compressive deformation is preferably no less than 40 gf/cm2, and more preferably no less than 50 gf/cm2. The resilience of the elastic mat 100 per unit area in the second 50% compressive deformation at the above lower limit or higher makes it easy to maintain the repetitive resilience for a longer term, and to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term. In the present description, “the 50% compressive deformation (of the elastic mat) is repeated twice” means that after the first 50% compressive deformation, the compressive force applied to the elastic mat is taken off, so that the thickness of the elastic mat naturally recovers sufficiently, and thereafter the elastic mat is compressively deformed in the thickness direction again, so that the thickness thereof is 50% of the initial thickness (thickness before the first 50% compressive deformation).
In the present description, the method of measuring the resilience of the elastic mat per unit area in the first and the second 50% compressive deformations is as follows.
The thickness of the elastic mat 100 (thickness before the compression deformation) t (see
An example in the above description on the present invention is the elastic mat 100 comprising the wire net 10 having a triangular wave shape in a plan view of the wire net 10 (see
An example in the above description on the present invention is the elastic mat 100 comprising the wire net 10 having a wave shape including the linear ridge parts (ridgelines) R in a plan view of the wire net 10 (see
Examples in the above description on the present invention are the elastic mats 100, 200 and 300 each comprising one wire net. The present invention is not limited to these embodiments. For example, the elastic mat can comprise at least two stacked wire nets.
As shown in
In the elastic mat 400, the adjacent wire nets 10a and 10b in a pair are joined at least along the periphery to be united into one body. For joining the adjacent wire nets in a pair, a known joining means such as welding, soldering, pinning, and binding with a resin wire or a metal wire may be used without particular limitations.
Concerning the elastic mat 400, a preferred thickness (thickness before the compression deformation) t (see
In view of pushing the electrodes by the elastic mat at a more uniform pressure over the entire faces of the electrodes in the alkaline water electrolysis vessel, the pitch λ of the wave shape of the wire net (space between two adjacent ridge parts (ridgelines) R in a plan view of the wire net. See
Concerning the elastic mat 100, the thickness tunit of the wire net 10 only is equal to the thickness t of the entire elastic mat 100. Concerning the elastic mat 400, the thickness tunit of one wire net 10 only is equal to t/2 when t is defined as the thickness of the entire elastic mat 400. The ratio tunit/λ (dimensionless number) of the thickness tunit of the wire net only to the pitch λ of the wave shape of this wire net is preferably 0.25 to 1.00, and more preferably 0.46 to 0.71. The ratio tunit/λ at the above lower limit or higher makes it easy to increase the resilience of the elastic mat as a whole. The ratio tunit/λ at the above upper limit or lower makes it easy to increase the repetitive resilience of the elastic mat.
An example in the above description on the present invention is the elastic mat 400 comprising a plurality of the stacked wire nets 10 having the linear ridge parts (ridgelines)R, R, . . . in a plan view. The present invention is not limited to this embodiment. For example, the elastic mat can comprise a plurality of the stacked wire nets 210 having V-shaped ridge parts (ridgelines)R, R, . . . in a plan view (
Examples in the above description on the present invention are the elastic mats 400, 500 and 600 each comprising the two stacked wire nets. The present invention is not limited to these embodiments. For example, the elastic mat can comprise at least three stacked wire nets. The number of the stacked wire nets can be preferably 2 to 8, and more preferably 2 to 4. Even in the elastic mat comprising at least three stacked wire nets, the wire nets are preferably stacked in such a way that the ridge parts (ridgelines)R, R, . . . of the wave shape of one wire net and the ridge parts (ridgelines)R, R, . . . of the wave shape of the other metal cross each other in each pair of two adjacent wire nets.
Examples in the above description on the present invention are the elastic mats 400, 500 and 600 each comprising a plurality of the stacked wire nets: adjacent wire nets in each pair are joined at least along the periphery to be united into one body. The present invention is not limited to these embodiments. For example, the elastic mat can comprise a plurality of stacked wire nets having the peripheries joined to and held by a flange part (described later) or a current collector (described later) of an electrolysis element, to be united into one body.
Examples in the above description on the present invention are the elastic mats 100, 200, 300, 400, 500 and 600 each comprising the wire nets 10, 210 or 310 with stockinette stitches with the metal wire. The present invention is not limited to these embodiments. For example, the elastic mat for an alkaline water electrolysis vessel can comprise a wire net being woven or knitted with a metal wire according to a weaving way or a knitting way other than the stockinette stitch. The weaving or the knitting way for weaving or knitting the wire net with a metal wire is not particularly limited as long as the wire net can have spring elasticity in the thickness direction thereof. Examples of such another weaving or knitting way include reverse stockinette stitch and rib stitch.
<2. Alkaline Water Electrolysis Vessel>
In the electrolysis vessel 1000, the separating membrane 1010 is sandwiched between and pushed by the cathode (first electrode) 30 and the anode (second electrode) 40, that is, the zero-gap configuration is realized by pushing the cathode (first electrode) 30 toward the anode (second electrode) 40 by the elastic mat (first elastic mat) 100.
As the anode-side frame 51 and the cathode-side frame 52, any known frame used for an alkaline water electrolysis vessel may be used without particular limitations as long as capable of defining each of the anode chamber A and the cathode chamber C. The anode-side frame 51 has the electroconductive backside separating wall 51a, and the flange part 51b uniting with the entire periphery of the backside separating wall 51a so as to have watertightness. Likewise, the cathode-side frame 52 has the electroconductive backside separating wall 52a, and the flange part 52b uniting with the entire periphery of the backside separating wall 52a so as to have watertightness. The backside separating walls 51a and 52a separate adjacent electrolytic cells, and electrically connect the adjacent electrolytic cells in series. The flange part 51b, together with the backside separating wall 51a, the separating membrane 1010 and the gasket 21, defines the anode chamber. The flange part 52b, together with the backside separating wall 52a, the separating membrane 1010 and the gasket 22, defines the cathode chamber. The flange parts 51b and 52b have shapes corresponding to the gaskets 21 and 22, respectively. That is, when the gaskets 21 and 22 and the separating membrane 1010 are sandwiched between and held by the anode-side frame 51 and the cathode-side frame 52, the flange part 51b of the anode-side frame 51 is in contact with the gasket 21 without any gap, and the flange part 52b of the cathode-side frame 52 is in contact with the gasket 22 without any gap. The flange part 51b includes an anolyte supply flow path to supply an anolyte to the anode chamber A, and an anolyte collection flow path to collect the anolyte and gas generated at the anode from the anode chamber A, which are not shown in
As the electroconductive rib 61 and the electroconductive rib 62, any known electroconductive rib used for an alkaline water electrolysis vessel may be used without particular limitations. In the electrolysis vessel 1000, the electroconductive rib 61 protrudes from the backside separating wall 51a of the anode-side frame 51, and the electroconductive rib 62 protrudes from the backside separating wall 52a of the cathode-side frame 52. The shape, number, and arrangement of the electroconductive rib 61 are not particularly limited as long as the anode 40 can be fixed to and held by the anode-side frame 51 by means of the electroconductive rib 61. The shape, number, and arrangement of the electroconductive rib 62 are not particularly limited either as long as the current collector 72 can be fixed to and held by the cathode-side frame 52 by means of the electroconductive rib 62. As the material of the electroconductive rib 61 and the electroconductive rib 62, any alkali-resistant rigid electroconductive material may be used without particular limitations. Examples of such a material include materials such as simple metals such as nickel and iron; stainless steel such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals obtained by nickeling any of them.
As the current collector 72, any known current collector used for an alkaline water electrolysis vessel may be used without particular limitations. For example, an expanded metal or punching metal made from an alkali-resistant rigid electroconductive material may be preferably employed. Examples of the material of the current collector 72 include simple metals such as nickel and iron; stainless steel such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals obtained by nickeling any of them. For holding the current collector 72 by means of the electroconductive rib 62, any known means such as welding and pinning may be employed without particular limitations.
The elastic mat 100 is as described above. For holding the elastic mat 100 by means of the current collector 72, any known means such as welding, pinning, and bolting may be employed without particular limitations.
As the separating membrane 1010, any known ion-permeable separating membrane used for a zero-gap alkaline water electrolysis vessel may be used without particular limitations. Desirably, the separating membrane 1010 has low gas permeability, low electric conductivity, and high strength. Examples of the separating membrane 1010 include ion-permeable porous membranes such as porous membranes formed of asbestos and/or modified asbestos, porous membranes using a polysulfone-based polymer, cloths using a polyphenylene sulfide fiber, fluorinated porous membranes, and porous membranes using a hybrid material that includes both inorganic and organic materials.
Any insulating gasket that may be used for an alkaline water electrolysis vessel may be used as the gaskets 21 and 22 without particular limitations.
As the cathode (first electrode) 30, any known cathode for generating hydrogen which is used for a zero-gap alkaline water electrolysis vessel and is a flexible porous plate may be used without particular limitations. The cathode 30 usually includes an electroconductive base material, and a catalyst layer covering the surface of the base material. As the electroconductive base material of the cathode 30, for example, nickel, a nickel alloy, stainless steel, mild steel, a nickel alloy, nickeled stainless steel, or nickeled mild steel may be preferably employed. As the catalyst layer of the cathode 30, a coating formed of a noble metal oxide, nickel, cobalt, molybdenum, or manganese, or an oxide or a noble metal oxide thereof may be preferably employed. As the cathode 30 of a flexible porous plate, a porous plate including a flexible electroconductive base material (such as a wire net being woven (or knitted) with a metal wire, and a thin punching metal) and the above described catalyst layer may be used. The opening area of one pore of the cathode 30 of a flexible porous plate is preferably 0.05 to 2.0 mm2, and more preferably 0.1 to 0.5 mm2. The ratio of the pore opening area to the area of a current-carrying cross section of the cathode 30 of a flexible porous plate is preferably no less than 20%, and more preferably 20 to 50%. The bending flexibility of the cathode 30 of a flexible porous plate is preferably no less than 0.05 mm/g, and more preferably 0.1 to 0.8 mm/g. Bending flexibility in the present description is represented by a value obtained in such a way that: one side of a sample 10 mm square is fixed, so that the sample is horizontal, and a deflection (mm) of another side (end of the sample) that is opposite to the fixed side, when a given load is downwardly applied to the other side is divided by the load (g). That is, the bending flexibility is a parameter showing characteristics inverse to bending rigidity. For example, the bending flexibility may be adjusted by the material and thickness of the porous plate, and in the case of a wire net, by the way of weaving (or knitting) a metal wire constituting the wire net. The cathode 30 may be fixed to the current collector 72, and may be fixed to the elastic mat 100. For fixing the cathode 30 to the current collector 72 or the elastic mat 100, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the cathode 30 in the periphery end of the current collector 72 to fix the cathode 30. When fixed, the cathode 30 is preferably fixed, so that the resilience of the elastic mat 100 is not impaired.
As the anode (second electrode) 40, any known anode for generating oxygen which is used for a zero-gap alkaline water electrolysis vessel and is a rigid porous plate may be used without particular limitations. The anode 40 usually includes an electroconductive base material, and a catalyst layer covering the surface of the base material. The catalyst layer is preferably porous. As the electroconductive base material of the anode 40, for example, ferronickel, vanadium, molybdenum, copper, silver, manganese, a platinum group metal, graphite, or chromium, or any combination thereof may be used. In the anode 40, an electroconductive base material formed of nickel may be preferably used. The catalyst layer includes nickel as an element. The catalyst layer preferably includes nickel oxide, metallic nickel or nickel hydroxide, or any combination thereof, and may include an alloy of nickel and at least one other metal. The catalyst layer is especially preferably formed of metallic nickel. The catalyst layer may further include chromium, molybdenum, cobalt, tantalum, zirconium, aluminum, zinc, a platinum group metal, or a rare earth element, or any combination thereof. Rhodium, palladium, iridium, or ruthenium, or any combination thereof may be further supported on the surface of the catalyst layer as an additional catalyst. As the anode 40 of a rigid porous plate, a porous plate including a rigid electroconductive base material (such as an expanded metal) and the above described catalyst layer may be used. For holding the anode 40 by the electroconductive rib 61, any known means such as welding, pinning, and bolting may be employed without particular limitations.
In the electrolysis vessel 1000, the cathode 30 is pushed toward the anode 40 by the elastic mat 100 according to the present invention, which makes it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 40 and the cathode 30 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 1000, the contact pressure at which the cathode (first electrode) 30 is pushed toward the anode (second electrode) 40 is preferably 100 to 450 gf/cm2, and more preferably 150 to 300 gf/cm2. The contact pressure at the above lower limit or higher makes it possible to more stably maintain the zero-gap configuration even if the pressure inside the electrolysis vessel changes, and to further reduce the operating voltage to further improve the energy efficiency. The contact pressure at the above upper limit or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
An example in the above description on the present invention is the alkaline water electrolysis vessel 1000 comprising the cathode (first electrode) 30 of a flexible porous plate which is pushed toward the anode (second electrode) 40 by the first elastic mat 100. The present invention is not limited to this embodiment. For example, the alkaline water electrolysis vessel can comprise the anode 40 of a flexible porous plate which is pushed toward the cathode 30 by the first elastic mat 100.
In the electrolysis vessel 2000, the separating membrane 1010 is sandwiched between and pushed by the anode (first electrode) 2040 and the cathode (second electrode) 2030, that is, the zero-gap configuration is realized by pushing the anode (first electrode) 2040 toward the cathode (second electrode) 2030 by the elastic mat (first elastic mat) 100.
As the current collector 71, any known current collector used for an alkaline water electrolysis vessel may be used without particular limitations. For example, an expanded metal, punching metal or net made from an alkali-resistant rigid electroconductive material may be preferably employed. Examples of the material of the current collector 71 include simple metals such as nickel and iron; stainless steel such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals obtained by nickeling any of them. For holding the current collector 71 by means of the electroconductive rib 61, any known means such as welding and pinning may be employed without particular limitations.
The elastic mat 100 is as described above. For holding the elastic mat 100 by the current collector 71, any known means such as welding and pinning may be employed without particular limitations.
As the anode (first electrode) 2040, any known anode that is for alkaline water electrolysis same as the above-described anode 40, and is a flexible porous plate may be used without particular limitations. As the anode 2040 of a flexible porous plate, a porous plate including a flexible electroconductive base material (such as a wire net being woven (or knitted) with a metal wire, and a thin punching metal) and the above described catalyst layer may be used. The opening area of one pore of the anode 2040 of a flexible porous plate is preferably 0.05 to 2.0 mm2, and more preferably 0.1 to 0.5 mm2. The ratio of the pore opening area to the area of a current-carrying cross section of the anode 2040 of a flexible porous plate is preferably no less than 20%, and more preferably 20 to 50%. The bending flexibility of the anode 2040 of a flexible porous plate is preferably no less than 0.05 mm/g, and more preferably 0.1 to 0.8 mm/g. The anode 2040 may be fixed to the current collector 71, and may be fixed to the elastic mat 100. For fixing the anode 2040 to the current collector 71 or the elastic mat 100, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the anode 2040 in the periphery end of the current collector 71 to fix the anode 2040. When fixed, the anode 2040 is preferably fixed, so that the resilience of the elastic mat 100 is not impaired.
As the cathode (second electrode) 2030, any known cathode that is for alkaline water electrolysis same as the above described cathode 30, and is a rigid porous plate may be used without particular limitations. As the cathode 2030 of a rigid porous plate, a porous plate including a rigid electroconductive base material (such as an expanded metal) and the above described catalyst layer may be used. For holding the cathode 2030 by the electroconductive rib 62, any known means such as welding, pinning, and bolting may be employed without particular limitations.
In the electrolysis vessel 2000, the anode 2040 is pushed toward the cathode 2030 by the elastic mat 100 according to the present invention, which makes it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 2040 and the cathode 2030 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 2000, the contact pressure at which the anode (first electrode) 2040 is pushed toward the cathode (second electrode) 2030 is preferably 100 to 450 gf/cm2, and more preferably 150 to 300 gf/cm2. The contact pressure at the above lower limit or higher makes it possible to more stably maintain the zero-gap configuration even if the pressure inside the electrolysis vessel changes, and to further reduce the operating voltage to further improve the energy efficiency. The contact pressure at the above upper limit or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
Examples in the above description on the present invention are the alkaline water electrolysis vessel 1000 comprising the second electrode (anode) 40 of a rigid porous plate, which is held by the electroconductive rib 61, and the alkaline water electrolysis vessel 2000 comprising the second electrode (cathode) 2030 of a rigid porous plate, which is held by the electroconductive rib 62. The present invention is not limited to these embodiments. For example, the alkaline water electrolysis vessel can comprise the second electrode of a rigid porous plate which is pushed toward the first electrode by a second elastic mat that is an elastic mat for an alkaline water electrolysis vessel according to the present invention.
In the electrolysis vessel 3000, the cathode (first electrode) 30 is a flexible porous plate (first porous plate). The cathode 30 may be fixed to the current collector 72, and may be fixed to the first elastic mat 100a. For fixing the cathode 30 to the current collector 72 or the first elastic mat 100a, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the cathode 30 in the periphery end of the current collector 72 to fix the cathode 30. When fixed, the cathode 30 is preferably fixed, so that the resilience of the elastic mat 100a is not impaired.
In the electrolysis vessel 3000, the anode (second electrode) 40 may be a rigid porous plate, and may be a flexible porous plate (second porous plate). Preferably, the anode 40 is a rigid porous plate. The anode 40 of a flexible porous plate may be fixed to the current collector 71, and may be fixed to the second elastic mat 100b. The anode 40 of a rigid porous plate can be fixed to the second elastic mat 100b. For fixing the anode 40 to the current collector 71 or the second elastic mat 100b, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the anode 40 in the periphery end of the current collector 71 to fix the anode 40. When fixed, the anode 40 is preferably fixed, so that the resilience of the elastic mat 100b is not impaired.
In the electrolysis vessel 3000, the separating membrane 1010 is sandwiched between and pushed by the cathode (first electrode) 30 and the anode (second electrode) 40, that is, the zero-gap configuration is realized by pushing the cathode (first electrode) 30 toward the anode (second electrode) 40 by the first elastic mat 100a, and pushing the anode (second electrode) 40 toward the cathode (second electrode) 30 by the second elastic mat 100b.
According to the electrolysis vessel 3000, the separating membrane 1010 receives the pressure from both the elastic mats on the anode side and the cathode side, which makes it easy to suppress deformation of the separating membrane 1010 in the vicinity of the periphery of the electrodes.
In the electrolysis vessel 3000, the cathode (first electrode) 30 is pushed toward the anode (second electrode) 40 by the elastic mat (first elastic mat) 100a according to the present invention, and the anode (second electrode) 40 is pushed toward the cathode (first electrode) 30 by the elastic mat (second elastic mat) 100b according to the present invention, which make it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 40 and the cathode 30 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 3000, the contact pressure at which the cathode (first electrode) 30 is pushed toward the anode (second electrode) 40, and the contact pressure at which the anode (second electrode) 40 is pushed toward the cathode (first electrode) 30 is each preferably 50 to 225 gf/cm2, and more preferably 75 to 150 gf/cm2. The respective contact pressures at the above lower limits or higher make it possible to further reduce the operating voltage to further increase the energy efficiency. The respective contact pressures at the above upper limits or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
Examples in the above description on the present invention are the alkaline water electrolysis vessels 1000, 2000 and 3000 each comprising the first electrode of a flexible porous plate and/or the second electrode of a rigid porous plate. The present invention is not limited to these embodiments. For example, the alkaline water electrolysis vessel can comprise the first electrode of a flexible porous plate, and the second electrode of a flexible porous plate as well.
In the electrolysis vessel 4000, the cathode (first electrode) 30 is a flexible porous plate (first porous plate). The cathode 30 may be fixed to the current collector 72, and may be fixed to the first elastic mat 100a. For fixing the cathode 30 to the current collector 72 or the first elastic mat 100a, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the cathode 30 in the periphery end of the current collector 72 to fix the cathode 30. When fixed, the cathode 30 is preferably fixed, so that the resilience of the elastic mat 100a is not impaired.
In the electrolysis vessel 4000, the anode (second electrode) 2040 is a flexible porous plate (second porous plate), and is fixed to the rigid current collector 91. For fixing the anode 2040 to the rigid current collector 91, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the anode 2040 in the periphery end of the current collector 71 to fix the anode 2040. When fixed, the anode 2040 is preferably fixed, so that the resilience of the elastic mat 100b is not impaired.
In the electrolysis vessel 4000, the separating membrane 1010 is sandwiched between and pushed by the cathode (first electrode) 30 and the anode (second electrode) 2040, that is, the zero-gap configuration is realized by pushing the cathode (first electrode) 30 toward the anode (second electrode) 2040 by the first elastic mat 100a, and pushing the anode (second electrode) 2040 toward the cathode (first electrode) 30 by the second elastic mat 100b, wherein the rigid current collector 91 is arranged between the anode 2040 and the second elastic mat 100b.
In the electrolysis vessel 4000, the rigid current collector 91 is disposed, so that the second electrode (anode) 2040 is sandwiched between the rigid current collector 91 and the separating membrane 1010. The second electrode (anode) 2040 is supported by the rigid current collector 91. As the rigid current collector 91, any known electroconductive rigid current collector may be used. For example, an expanded metal or punching metal made from an alkali-resistant rigid electroconductive material may be preferably employed. Examples of the material of the rigid current collector 91 include simple metals such as nickel and iron; stainless steel such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals obtained by nickeling any of them. The rigid current collector 91 may be, but is not necessarily, held by the elastic mat 100b. For holding the rigid current collector 91 by the second elastic mat 100b, any known means such as welding, pinning, and bolting may be employed without particular limitations.
According to the electrolysis vessel 4000, the second elastic mat 100b pushes the anode 2040, wherein the rigid current collector 91 is arranged between the second elastic mat 100b and the anode 2040 (that is, the second electrode 2040 is supported by the rigid current collector 91 from the back), which can cause the pressure at which both the electrodes are pushed toward the separating membrane 1010 to be more uniform over the entire faces of the electrodes even when the second electrode 2040 is flexible, and thus can cause the current density to be more uniform. The separating membrane 1010 receives the pressure from both the elastic bodies on the anode side and the cathode side, which makes it easy to suppress deformation of the separating membrane 1010 in the vicinity of the periphery of the electrodes.
In the electrolysis vessel 4000, the cathode (first electrode) 30 is pushed toward the anode (second electrode) 2040 by the elastic mat (first elastic mat) 100a according to the present invention, and the anode (second electrode) 2040 is pushed toward the cathode (first electrode) 30 by the elastic mat (second elastic mat) 100b according to the present invention, wherein the rigid current collector 91 is arranged between the anode 2040 and the elastic mat 100b, which makes it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 2040 and the cathode 30 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 4000, the contact pressure at which the cathode (first electrode) 30 is pushed toward the anode (second electrode) 2040, and the contact pressure at which the anode (second electrode) 2040 is pushed toward the cathode (first electrode) 30 is each preferably 50 to 225 gf/cm2, and more preferably 75 to 150 gf/cm2. The respective contact pressures at the above lower limits or higher make it possible to further reduce the operating voltage to further improve the energy efficiency. The respective contact pressures at the above upper limits or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
An example in the above description on the present invention is the alkaline water electrolysis vessel 4000 comprising the current collector 71 supported by the electroconductive rib 61, the second elastic mat 100b supported by the current collector 71, and the rigid current collector 91 supported by the second elastic mat 100b. The present invention is not limited to this embodiment. For example, the electrolysis vessel 4000 can be an alkaline water electrolysis vessel not comprising the second elastic mat 100b, but comprising the rigid current collector 91 supported by the current collector 71. For example, the electrolysis vessel 4000 can be an alkaline water electrolysis vessel not comprising the second elastic mat 100b or the current collector 71, but comprising the rigid current collector 91 directly supported by the electroconductive rib 61.
An example in the above description on the present invention is the alkaline water electrolysis vessel 4000 comprising the second elastic mat 100b pushing the anode 2040 toward the cathode 30, wherein the rigid current collector 91 is arranged between the anode 2040 and the second elastic mat 100b. The present invention is not limited to this embodiment. For example, the alkaline water electrolysis vessel can comprise the second elastic mat pushing the cathode toward the anode, wherein the rigid current collector is arranged between the cathode and the second elastic mat.
In the electrolysis vessel 5000, the anode (first electrode) 2040 is a flexible porous plate (first porous plate). The anode 2040 may be fixed to the current collector 71, and may be fixed to the first elastic mat 100a. For fixing the anode 2040 to the current collector 71 or the first elastic mat 100a, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the anode 2040 in the periphery end of the current collector 71 to fix the periphery of the anode 2040. When fixed, the anode 2040 is preferably fixed so that the resilience of the elastic mat 100a is not impaired.
In the electrolysis vessel 5000, the cathode (second electrode) 30 is a flexible porous plate (second porous plate), and is fixed to the rigid current collector 92. For fixing the cathode 30 to the rigid current collector 92, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may tuck the periphery of the cathode 30 in the periphery end of the current collector 72 to fix the cathode 30. When fixed, the cathode 30 is preferably fixed so that the resilience of the elastic mat 100b is not impaired.
In the electrolysis vessel 5000, the separating membrane 1010 is sandwiched between and pushed by the anode (first electrode) 2040 and the cathode (second electrode) 30, that is, the zero-gap configuration is realized by pushing the anode (first electrode) 2040 toward the cathode (second electrode) 30 by the first elastic mat 100a, and pushing the cathode (second electrode) 30 toward the anode (first electrode) 2040 by the second elastic mat 100b, wherein the rigid current collector 92 is arranged between the cathode 30 and the second elastic mat 100b.
In the electrolysis vessel 5000, the rigid current collector 92 is disposed, so that the second electrode (cathode) 30 is sandwiched between the rigid current collector 92 and the separating membrane 1010. The second electrode (cathode) 30 is supported by the rigid current collector 92. As the rigid current collector 92, any known electroconductive rigid current collector may be used. For example, an expanded metal or punching metal made from an alkali-resistant rigid electroconductive material may be preferably employed. Examples of the material of the rigid current collector 92 include simple metals such as nickel and iron; stainless steel such as SUS304, SUS310, SUS310S, SUS316, and SUS316L; and metals obtained by nickeling any of them. The rigid current collector 92 may be, but is not necessarily, held by the elastic mat 100b. For holding the rigid current collector 92 by the second elastic mat 100b, any known means such as welding, pinning, and bolting may be employed without particular limitations.
According to the electrolysis vessel 5000, the second elastic mat 100b pushes the second electrode 30, wherein the rigid current collector 92 is arranged between the second electrode 30 and the second elastic mat 100b (that is, the second electrode 30 is supported by the rigid current collector 92 from the back), which can cause the pressure at which both the electrodes are pushed toward the separating membrane 1010 to be more uniform over the entire faces of the electrodes even when the second electrode 30 is flexible, and thus can cause the current density to be more uniform. The separating membrane 1010 receives the pressure from both the elastic bodies on the anode side and the cathode side, which makes it easy to suppress deformation of the separating membrane 1010 in the vicinity of the periphery of the electrodes.
In the electrolysis vessel 5000, the anode (first electrode) 2040 is pushed toward the cathode (second electrode) 30 by the elastic mat (first elastic mat) 100a according to the present invention, and the cathode (second electrode) 30 is pushed toward the anode (first electrode) 2040 by the elastic mat (second elastic mat) 100b according to the present invention, wherein the rigid current collector 92 is arranged between the cathode 30 and the elastic mat 100b, which makes it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 2040 and the cathode 30 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 5000, the contact pressure at which the anode (first electrode) 2040 is pushed toward the cathode (second electrode) 30, and the contact pressure at which the cathode (second electrode) 30 is pushed toward the anode (first electrode) 2040, wherein the rigid current collector 92 is arranged between the cathode 30 and the second elastic mat 100b is each preferably 50 to 225 gf/cm2, and more preferably 75 to 150 gf/cm2. The respective contact pressures at the above lower limits or higher make it possible to further reduce the operating voltage to further improve the energy efficiency. The respective contact pressures at the above upper limits or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
An example in the above description on the present invention is the alkaline water electrolysis vessel 5000 comprising the current collector 72 supported by the electroconductive rib 62, the second elastic mat 100b supported by the current collector 72, and the rigid current collector 92 supported by the second elastic mat 100b. The present invention is not limited to this embodiment. For example, the electrolysis vessel 5000 can be an alkaline water electrolysis vessel not comprising the second elastic mat 100b, but comprising the rigid current collector 92 supported by the current collector 72. For example, the electrolysis vessel 5000 can be an alkaline water electrolysis vessel not comprising the second elastic mat 100b or the current collector 72, but comprising the rigid current collector 92 directly supported by the electroconductive rib 62.
Examples in the above description on the present invention are the alkaline water electrolysis vessels 1000 to 5000 each comprising the electroconductive rib 61 in the anode chamber, and the electroconductive rib 62 in the cathode chamber. The present invention is not limited to these embodiments. For example, the alkaline water electrolysis vessel can comprise no electroconductive rib in one or both of the anode chamber and the cathode chamber.
In the electrolysis vessel 6000, the cathode (first electrode) 30 is a flexible porous plate (first porous plate). The cathode 30 can be fixed to the backside separating wall 52a or the first elastic mat 100a. For fixing the cathode 30 to the backside separating wall 52a or the first elastic mat 100a, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may provide a hook (hooked member) at the surface of the inside of the backside separating wall 52a, and fit the cathode 30 to the hook, to fix the cathode 30 to the backside separating wall 52a. When fixed, the cathode 30 is preferably fixed, so that the resilience of the elastic mat 100a is not impaired.
In the electrolysis vessel 6000, the anode (second electrode) 40 may be a rigid porous plate, and may be a flexible porous plate (second porous plate). The anode 40 is preferably a rigid porous plate. When being a flexible porous plate, the anode 40 may be fixed to the backside separating wall 51a, and may be fixed to the second elastic mat 100b. When being a rigid porous plate, the anode 40 can be fixed to the second elastic mat 100b. For fixing the anode 40 to the backside separating wall 51a or the second elastic mat 100b, for example, any known means such as welding, pinning, and bolting may be employed without particular limitations. For example, one may provide a hook (hooked member) at the surface of the inside of the backside separating wall 51a, and fit the anode 40 to the hook, to fix the anode 40 to the backside separating wall 51a. When fixed, the anode 40 is preferably fixed, so that the resilience of the elastic mat 100b is not impaired.
In the electrolysis vessel 6000, the separating membrane 1010 is sandwiched between and pushed by the cathode (first electrode) 30 and the anode (second electrode) 40, that is, the zero-gap configuration realized by pushing the cathode (first electrode) 30 toward the anode (second electrode) 40 by the first elastic mat 100a, and pushing the anode (second electrode) 40 toward the cathode (first electrode) 30 by the second elastic mat 100b.
Such an alkaline water electrolysis vessel 6000 can also exert the same effect as that the electrolysis vessel 3000 does. That is, according to the alkaline water electrolysis vessel 6000, the separating membrane 1010 receives the pressure from both the elastic mats on the anode side and the cathode side, which makes it easy to suppress deformation of the separating membrane 1010 in the vicinity of the periphery of the electrodes. Further, in the electrolysis vessel 6000, the anode chamber A and the cathode chamber C comprise no electroconductive rib, which makes it possible to thinner each electrolytic cell, and thus to downsize the electrolysis vessel to increase the gas production per occupied site area. One or both of the anode chamber and the cathode chamber comprise(s) no electroconductive rib, which makes it possible to reduce the amount of the materials to constitute the electrolysis vessel, and the steps necessary for making the electrolysis vessel.
In the electrolysis vessel 6000, the cathode (first electrode) 30 is pushed toward the anode (second electrode) 40 by the elastic mat (first elastic mat) 100a according to the present invention, and the anode (second electrode) 40 is pushed toward the cathode (first electrode) 30 by the elastic mat (second elastic mat) 100b according to the present invention, which makes it possible to increase the contact pressure at which the separating membrane 1010 is sandwiched between and pushed by the anode 40 and the cathode 30 without impairing the uniformity of the contact pressure, to increase the proportion of the zero-gap area in the electrode area. This makes it possible to reduce the operating voltage to improve the energy efficiency.
In the electrolysis vessel 6000, the contact pressure at which the cathode (first electrode) 30 is pushed toward the anode (second electrode) 40, and the contact pressure at which the anode (second electrode) 40 is pushed toward the cathode (first electrode) 30 is each preferably 50 to 225 gf/cm2, and more preferably 75 to 150 gf/cm2. The respective contact pressures at the above lower limits or higher make it possible to further reduce the operating voltage to further improve the energy efficiency. The respective contact pressures at the above upper limits or lower can lead to further increased repetitive resilience to maintain sufficient resilience even in long-term use, which makes it easy to keep the energy efficiency of the alkaline water electrolysis vessel high for a long term.
Examples in the above description on the present invention are the alkaline water electrolysis vessels 1000, 2000, 3000, 4000, 5000 and 6000 each comprising the elastic mat 100 for an alkaline water electrolysis vessel according to one embodiment of the present invention (
<3. Gas Production Method>
A gas production method according to the third aspect of the present invention is a gas production method comprising: (a) electrolyzing alkaline water by means of the alkaline water electrolysis vessel according to the present invention (hereinafter may be referred to as “step (a)”), wherein hydrogen gas and oxygen gas are produced. As the alkaline water electrolysis vessel in the step (a), any of the alkaline water electrolysis vessels according to the above described embodiments may be used. As the alkaline water, a known basic aqueous solution used for producing hydrogen gas and oxygen gas by the alkaline water electrolysis method (such as a KOH aqueous solution and a NaOH aqueous solution) may be employed without particular limitations.
The step (a) can be carried out by supplying an electrolyte (alkaline water) to each of the anode chamber and the cathode chamber of an alkaline water electrolysis vessel according to the present invention, and applying voltage so that a predetermined electrolytic current can flow between the anode and the cathode. Hydrogen gas can be retrieved from the cathode chamber, and oxygen gas can be retrieved from the anode chamber by: retrieving the gas generated by the electrolysis from each chamber together with the electrolyte; and subjecting the retrieved gas to gas-liquid separation. The electrolyte separated from the gas by the gas-liquid separation can be supplied again to each chamber, together with water added to the electrolyte as necessary.
According to the gas production method of the present invention, alkaline water is electrolyzed by means of an alkaline water electrolysis vessel according to the present invention, which makes it possible to improve the energy efficiency in the gas production by alkaline water electrolysis.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-198760 | Oct 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/039947 | 10/23/2020 | WO |
