`
`1. Technical Field
`
`BACKGROUND
`
`[0001]
`
`2.
`
`The present disclosure relates to an electrochemical
`of the Related Art
`
`hydrogen pump.
`
`hoped
`
`that
`
`hydrogen
`uses
`
`example
`
`and
`
`Description
`Inrecent years, hydrogen has been attracting attention as a clean
`[0002]
`a
`alternative energy source to
`replace fossil fuels against
`background of
`environmental problems, such as
`global warming, and energy issues, such as the
`resources. When burnt, basically, hydrogen only releases
`depletion of petroleum
`water, with zero emissions of carbon dioxide, which causes
`global warming, and
`almost zero emissions of substances like
`nitrogen oxides, and this is why
`is
`it
`of a device that
`will serve as clean energy. An
`asa fuel is fuel cells. The
`
`development
`efficiently
`hydrogen
`popularization of fuel cells are
`ongoing for automotive power supply and
`household power generation applications.
`Inthe forthcoming hydrogen society, technologies will need to be
`to enable not
`only the production but also high-density storage and
`developed
`or use of hydrogen.
`small-volume, low-cost transport
`In particular, further
`popularization of fuel cells, which provide distributed energy sources, requires
`hydrogen. Studies aimed at
`infrastructure for the
`of
`producing,
`to ensure
`are also
`
`[0003]
`
`preparing
`
`purifying,
`
`and
`
`supply
`
`densely storing high-purity hydrogen
`
`ongoing
`
`stable
`
`of
`
`supply
`hydrogen.
`For example, Japanese Unexamined Patent Application Publication No.
`[0004]
`2001-342587 discloses, in relation to an electrochemical hydrogen pump that
`an anode power feeder that includesfirst and
`purifies and pressurizes hydrogen,
`second feeder sections made from two
`
`respective types of titanium metal fibers
`to the electrolyte membrane and
`varying in diameter. This reduces damage
`
`Publication No. 2012-180553
`
`improves energy efficiency.
`Japanese Unexamined Patent
`[0005]
`Application
`discloses an anode power feeder that has a lower percentage of
`of its base than in its base as a result of the
`surface
`
`layer
`pressing
`the power feeder, made as a sintered mass oftitanium powder. This helps
`improve the density and smoothnessof the surface layer, thereby reducing
`1
`
`porosity
`
`in a
`
`of the base of
`
`P1023473
`
`
`
`damage
`
`to the electrolyte membrane.
`
`SUMMARY
`
`and
`
`embodiment
`
`an electrochemical
`
`madeof metal.
`
`[0006] One non-limiting
`exemplary
`provides
`can cost less in terms of its anode gas diffusion
`hydrogen pump that
`with an anode gas diffusion
`layer
`In one
`general aspect, the techniques disclosed here feature an
`[0007]
`electrochemical hydrogen pump. The electrochemical hydrogen pump includes
`an anode on a first primary surface of the electrolyte
`electrolyte membrane,
`a cathode on a second primary surface of the electrolyte membrane,
`membrane,
`and an anode separator
`on the anode. The anode includes an anode catalyst
`on the first
`membrane and an anode gas
`surface of the
`
`layer
`
`than
`
`an
`
`layer
`
`includes
`
`layer
`
`diffusion
`
`primary
`on the anode
`
`electrolyte
`The anode gas diffusion
`
`layer
`catalyst layer.
`porous carbon sheetthat is a
`
`a
`
`molded
`
`powder
`body.
`aspect of the
`[0008] The electrochemical hydrogen pump according
`present disclosure is advantageous in that it can cost less in terms of its anode
`gas diffusion layer than with an anode gas diffusion layer made of metal.
`[0009] Additional benefits and advantages of the disclosed embodimentswill
`become apparent from the specification and drawings. The benefits and/or
`advantages may be individually obtained by the various embodiments and
`which need notall be
`features of the
`and
`
`to an
`
`drawings,
`specification
`to obtain one or more of such benefits and/or
`
`advantages.
`
`provided
`
`in order
`
`[0010]
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`Fig. 1A is a
`example of an electrochemical
`diagram illustrating
`to Embodiment1;
`
`an
`
`hydrogen pump according
`Fig. 1B is an
`enlarged view of portion IB of the electrochemical hydrogen pump
`illustrated in Fig. 1A;
`Fig. 2A is a
`diagram illustrating
`to Embodiment1;
`according
`2B is an
`view of
`
`an
`
`example of an electrochemical hydrogen pump
`
`Fig.
`
`enlarged
`
`portion
`
`IIB of the electrochemical
`
`hydrogen pump
`
`illustrated in
`
`Fig. 2A;
`
`example of a porous carbon sheetin an
`Fig. 3 is a
`diagram illustrating
`to Embodiment1;
`electrochemical hydrogen pump according
`2
`
`an
`
`P1023473
`
`
`
`diagram illustrating exemplary results of an
`Fig. 4 is a
`analysis by Raman
`spectroscopy of a porous carbon sheetin an electrochemical hydrogen pump
`to Embodiment1;
`
`according
`5 is a
`
`Fig.
`
`diagram illustrating
`
`an
`
`example
`
`of a
`
`porous carbon sheetin an
`
`electrochemical
`
`6 is a
`
`hydrogen pump according
`measured
`
`to
`
`2 of Embodiment 1; and
`Example
`porosity percentages of a
`Fig.
`diagram illustrating exemplary
`porous carbon sheet in an electrochemical hydrogen pump according
`to
`3 of Embodiment 1.
`
`Example
`
`DETAILED DESCRIPTION
`
`[0011] Both Japanese Unexamined Patent Application Publication Nos. 2001-
`342587 and 2012-180553 use
`made of metal.
`If made of
`gas diffusion
`
`layers
`
`need to be
`
`with a noble metal to be
`
`metal, however, gas diffusion
`layers
`plated
`resistant to corrosion in acidic environments, and this causes a cost
`acceptably
`increase. The inventors considered using carbon-based gas diffusion layers,
`which resist corrosion in acidic environments and cost less, but found the problem
`that the anode gas diffusion layer buckles into a flow channel in the anode
`separator under the effect of a
`high cathodic pressure.
`[0012] After extensive research to address this, the inventors came up with
`a carbon sheet which is a
`powder molded body in the anode to reduce the
`and conceived an
`disclosure as
`of the
`
`using
`
`risk of this
`
`aspect
`buckling
`described below. The inventors also came
`up with
`
`present
`a
`
`using
`
`porous carbon sheet
`
`carbon in the anode to reducethe risk of this
`
`buckling
`
`and
`
`containing amorphous
`conceived an
`aspect of the present disclosure as described below.
`to a first aspect of
`an electrochemical hydrogen pump according
`[0013] That is,
`the present disclosure includes an
`an anode on a first
`electrolyte membrane,
`a cathode on a second primary
`primary surface of the electrolyte membrane,
`surface of the electrolyte membrane, and an anode separator
`on the anode. The
`anode includes an anode catalyst layer
`on the first primary surface of the
`membrane and an anode gas diffusion
`on the anode
`layer
`catalyst
`includes a
`porous carbon sheetthatis a
`
`electrolyte
`The anode gas diffusion
`
`layer.
`
`layer
`
`powder
`
`molded
`
`body.
`as
`
`such, the electrochemical hydrogen pump according to this
`[0014] Configured
`can costless in terms of its anode gas diffusion layer than with an anode
`3
`
`aspect
`
`P1023473
`
`
`
`gas diffusion layer made of metal. At the same
`time, the risk of the buckling of the
`can be reduced.
`anode gas diffusion layer into the anode separator
`Specifically, the electrochemical hydrogen pump according to this aspect
`a
`with ones
`offers enhanced
`for
`porous carbon
`
`[0015]
`
`having
`porous carbon sheet made
`
`a
`
`rigidity,
`example compared
`sheet made from carbon fibers, by
`from a
`molded
`
`virtue of
`
`having
`
`powder
`body.
`to a second aspectof the
`[0016] An electrochemical hydrogen pump according
`present disclosure includes an
`an anode ona first primary
`electrolyte membrane,
`a cathode on a second primary surface of the
`surface of the electrolyte membrane,
`electrolyte membrane, and an anode separator
`on the anode. The anode includes
`an anode catalyst layer
`on the first primary surface of the electrolyte membrane
`and an anode gas diffusion
`on the anode
`The anode gas
`includes a
`
`layer
`closer to the anode separator, contains
`amorphous
`carbon sheet is analyzed by Raman spectroscopy, D/G
`as
`such, the electrochemical hydrogen pump according to this
`[0017] Configured
`can costless in terms of its anode gas diffusion layer than with an anode
`aspect
`gas diffusion layer made of metal. At the same
`time, the risk of the buckling of the
`can be reduced.
`anode gas diffusion layer into the anode separator
`a porous carbon sheet containing amorphous carbon has
`that have been observed with the hitherto used metal
`
`diffusion
`
`layer
`catalyst layer.
`porous carbon sheet whose first surface
`
`which is
`
`layer,
`carbon. When the porous
`> 1.0.
`
`[0018]
`
`Specifically,
`
`few of
`
`relatively
`sharp points
`porous media. Even when such a
`
`porous carbon sheetis
`
`pressed against
`
`an
`
`membrane, it is
`
`that the
`
`membrane is
`
`electrolyte
`unlikely
`electrolyte
`damaged.
`to this aspect, therefore, offers
`The electrochemical hydrogen pump according
`to the electrolyte membrane compared with known ones
`reducedrisk of damage
`made with a metal porous medium.
`
`In general, furthermore, amorphous carbon, in which carbon-carbon
`[0019]
`bonds are in an
`amorphous structure, is more
`rigid than carbon in which carbon-
`carbon bonds are in acrystalline
`structure. The anode gas diffusion layer in the
`to this
`electrochemical
`is therefore
`
`hydrogen pump according
`aspect
`because the porous carbon sheetin it contains
`> 1.0 when the sheet is
`
`rigid
`amount that D/G
`
`amorphous
`Raman spectroscopy.
`analyzed by
`to a third aspect of the
`[0020] An electrochemical hydrogen pump according
`present disclosure is: In the first or second aspect, the porous carbon sheetin the
`4
`
`acceptably
`carbon in such an
`
`P1023473
`
`
`
`electrochemical hydrogen pump may have a
`Young's modulus in the direction of
`thickness higher than or
`equal to 2.5 GPa atleast in its first surface layer, which is
`closer to the anode separator.
`V\hen its porous carbon sheet has a desired
`
`[0021]
`
`20 MPa)
`
`buckling
`channel in the anode separator caused
`An electrochemical
`
`compressive strength (e.g.,
`the direction of thickness, the electrochemical
`hydrogen pump
`in
`as described above, suffers to a lesser
`to this aspect, configured
`according
`degree
`a differential pressure
`the deformation of its anode gas diffusion layer caused by
`(high pressure) that occurs between the cathode and anode during hydrogen
`pressurization than it would if the Young's modulus in the direction of thickness of
`were lower than 2.5
`the first surface layer, which is closer to the anode separator,
`GPa. For example, the electrochemical hydrogen pump according to this aspect
`in a flow
`offers reducedrisk of the
`of the anode gas diffusion
`layer
`sucha differential pressure.
`to a fourth aspect of the
`hydrogen pump according
`[0022]
`present disclosure is: In the first or second aspect, the porous carbon sheet in the
`electrochemical hydrogen pump may have a
`Young's modulus in the direction of
`thickness higher than or
`equal to 7.8 GPa atleast in its first surface layer, which is
`closer to the anode separator.
`Vvhen its porous carbon sheet has a desired compressive strength (e.g.,
`[0023]
`40 MPa) in the direction of thickness, the electrochemical hydrogen pump
`as described above, suffers to a lesser
`to this
`aspect, configured
`degree
`according
`the deformation of its anode gas diffusion
`caused bya differential pressure
`layer
`that occurs between the cathode and anode
`
`by
`
`(high pressure)
`during hydrogen
`pressurization than it would if the Young's modulus in the direction of thickness of
`were lower than 7.8
`the first surface layer, which is closer to the anode separator,
`GPa. For example, the electrochemical hydrogen pump according to this aspect
`offers reducedrisk of the buckling of the anode gas diffusion layer in a flow
`differential pressure.
`channel in the anode separator caused by such
`to a fifth aspect of the
`[0024] An electrochemical hydrogen pump according
`present disclosure is: In the first or second
`the porous carbon sheetin the
`aspect,
`hydrogen pump may havea flexural
`than or
`strength higher
`equal
`to 10 MPa atleastin its first surface
`which is closer to the anode separator.
`layer,
`Vvhen its porous carbon sheet has a desired compressive strength (e.g.,
`[0025]
`20 MPa) in the direction of thickness, the electrochemical hydrogen pump
`5
`
`electrochemical
`
`P1023473
`
`
`
`strength
`were lower than 10 MPa. For
`
`pressurization
`is closer to the anode separator,
`example,
`electrochemical
`hydrogen pump according to this aspect offers reduced risk of the
`buckling of the anode gas diffusion layer in a flow channel in the anode separator
`caused by such a differential pressure.
`to a sixth aspect of the
`[0026] An electrochemical hydrogen pump according
`present disclosure is: In the first or second aspect, the porous carbon sheetin the
`electrochemical hydrogen pump may
`a flexural strength higher than or
`to 20 MPa atleastin its first surface
`which is closer to the anode
`
`the
`
`equal
`
`separator.
`
`have
`
`as described above, suffers to a lesser degree
`to this aspect, configured
`according
`a differential pressure
`the deformation of its anode gas diffusion layer caused by
`(high pressure) that occurs between the cathode and anode during hydrogen
`than it would if the flexural
`of the first surface
`which
`
`layer,
`
`layer,
`VVhen its porous carbon sheet has a desired
`
`[0027]
`
`40 MPa)
`
`compressive strength (e.g.,
`the direction of thickness, the electrochemical
`hydrogen pump
`in
`as described above, suffers to a lesser degree
`to this aspect, configured
`according
`a differential pressure
`the deformation of its anode gas diffusion layer caused by
`(high pressure) that occurs between the cathode and anode during hydrogen
`pressurization than it would if the flexural strength of the first surface layer, which
`were lower than 20 MPa. For example, the
`is closer to the anode separator,
`to this aspect offers reduced risk of the
`electrochemical hydrogen pump according
`in a flow channel in the anode
`of the anode gas diffusion
`layer
`such a differential pressure.
`
`buckling
`
`caused
`
`by
`
`separator
`
`An electrochemical
`
`to a seventh aspectof the
`hydrogen pump according
`[0028]
`present disclosureis: In any one of the first, second, third, and fifth aspects, the
`porous carbon sheet in the electrochemical hydrogen pump may have a
`porosity
`lower than or
`to 45% at least in its first surface layer, which is closer to the
`equal
`to an
`anode separator. An electrochemical hydrogen pump according
`eighth
`aspect of the present disclosure, furthermore, is: In any one of the first, second,
`fourth, and sixth aspects, the porous carbon sheetin the electrochemical hydrogen
`may
`a
`lower than or
`to 39% at leastin its first surface
`
`pump
`
`layer,
`
`have
`porosity
`equal
`which is closer to the anode separator.
`An electrochemical
`
`hydrogen pump according
`[0029]
`present disclosureis: In the seventh aspect, the porous carbon sheetin the
`electrochemical hydrogen pump may havea
`porosity lower than or
`to 45%
`6
`
`to a ninth aspectof the
`
`equal
`
`P1023473
`
`
`
`in its second surface layer, which is closer to the anode catalyst layer. An
`to a tenth aspect of the present
`electrochemical hydrogen pump according
`disclosure, furthermore, is: In the eighth aspect, the porous carbon sheetin the
`lower than or
`hydrogen pump may have a
`electrochemical
`to 39%
`which is closer to the anode
`in its second surface
`
`porosity
`
`equal
`
`layer,
`
`catalyst layer.
`to an eleventh aspect of
`hydrogen pump according
`[0030]
`the present disclosure is: In any oneof the first to tenth aspects, the porous
`carbon sheetin the electrochemical hydrogen pump may
`havehigher rigidity in its
`first surface layer, which is closer to the anode separator, than in the layer lying
`to a
`under this first surface layer. An electrochemical hydrogen pump according
`twelfth aspect of the present disclosure, furthermore, is: In the eleventh aspect, the
`porous carbon sheet in the electrochemical
`hydrogen pump may have
`which is closer to the anode
`
`in its second surface
`
`An electrochemical
`
`rigidity
`
`layer,
`
`higher
`
`catalyst layer,
`
`than
`
`in the
`
`layer lying
`
`under this second surface
`
`layer.
`as described above, the electrochemical hydrogen pumps
`[0031] Configured
`to these aspects suffer to a lesser degree the deformation of their anode
`according
`a differential pressure (high pressure) that occurs
`gas diffusion layer caused by
`between the cathode and anode during hydrogen pressurization. For example,
`to these aspects offer reduced risk
`the electrochemical hydrogen pumps according
`of the buckling of the anode gas diffusion layer in a flow channel in the anode
`sucha differential pressure.
`caused
`
`separator
`
`by
`
`An electrochemical
`
`a thirteenth aspect of
`hydrogen pump according to
`[0032]
`one of the first to twelfth aspects, the porous
`the present disclosure is: In any
`carbon sheetin the electrochemical hydrogen pump may have a lower porosityin
`its first surface layer, which is closer to the anode separator, than in the layer lying
`to a
`under this first surface layer. An electrochemical hydrogen pump according
`fourteenth aspect of the present disclosure, furthermore, is: In the thirteenth
`aspect, the porous carbon sheetin the electrochemical hydrogen pump may have
`a lower porosity in its second surface layer, which is closer to the anode catalyst
`than in the
`under this second surface
`
`layer,
`
`[0033]
`
`carbon
`
`layer lying
`If the porous carbon sheetis, for
`
`layer.
`a sintered
`
`made from
`
`example,
`body
`of the porous carbon sheetwill increase
`
`the
`
`particles, reducing
`porosity
`necking between the carbon particles forming the porous carbon sheet (bonding
`together of the particles). Hencethe rigidity of the porous carbon sheetis
`7
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`P1023473
`
`
`
`to the thirteenth aspect
`improved. The electrochemical hydrogen pump according
`therefore offers improved rigidity of the first surface layer, which is closer to the
`anode separator, of its porous carbon sheet. The electrochemical hydrogen pump
`of the second
`to the fourteenth aspectalso offers
`
`according
`
`surface
`
`layer,
`sheet. As aresult, these electrochemical
`
`improvedrigidity
`which is closer to the anode
`of its porous carbon
`catalyst layer,
`hydrogen pumps suffer to a lesser
`degree the deformation of their anode gas diffusion layer caused bya differential
`pressure that occurs between the cathode and anode during hydrogen
`pressurization. For example, the electrochemical hydrogen pumps according
`these aspects offer reduced risk of the buckling of the anode gas diffusion layer in
`a flow channel in the anode separator caused by such a differential pressure.
`to a fifteenth
`An electrochemical
`of the
`
`to
`
`hydrogen pump according
`aspect
`[0034]
`oneof the first to fourteenth aspects, the porous
`present disclosureis: In any
`hydrogen pump may have a
`carbon sheetin the electrochemical
`diameter smaller than the thickness of the electrolyte membrane.
`larger than or
`If the peak pore diameter of the porous carbon sheet were
`[0035]
`to the thickness of the electrolyte membrane, the electrolyte membrane
`equal
`to
`could break while the electrochemical hydrogen pump is operating
`pressurize
`as a result of the electrolyte membrane falling into a pore in the porous
`hydrogen
`carbon sheet becauseof a differential pressure that occurs between the cathode
`
`peak pore
`
`and anode. The electrochemical
`
`to this
`
`hydrogen pump according
`aspect,
`however, offers reduced risk of such an event
`peak pore diameter
`smaller than the thickness of the
`of the porous carbon sheet
`
`virtue of the
`
`by
`
`being
`
`electrolyte
`
`membrane.
`
`to a sixteenth aspect of the
`[0036] An electrochemical hydrogen pump according
`present disclosureis: In any one ofthe first to fifteenth aspects, the porous carbon
`sheetin the electrochemical hydrogen pump may
`an overall porosity higher
`than or
`to 20%.
`
`have
`
`equal
`If the overall porosity of the porous carbon sheet were lower than 20%,
`in
`of the anode gas diffusion
`diffusing gases into the anode
`could be insufficient. The electrochemical
`
`[0037]
`
`the
`
`diffusibility
`
`layer
`
`hydrogen pump according
`catalyst layer
`to this aspect, however, offers sufficient
`of the anode gas diffusion
`diffusibility
`in terms of gas diffusion into the anode catalyst layer because the 20% or
`higher
`overall porosity of the porous carbon sheet encourages the presence of pores
`8
`
`layer
`
`P1023473
`
`
`
`to the outside (open holes) in the anode gas diffusion layer. By virtue of
`leading
`to the anode
`this, anode gas coming from the anode separator is supplied properly
`catalyst layer through the anode gas diffusion layer.
`when an electric current flows between an anode and a
`
`Incidentally,
`[0038]
`cathode in an electrochemical
`
`hydrogen pump, protons
`water with them.
`membrane from the anode to the cathode, bringing
`operating temperature of the electrochemical hydrogen pump is higher than or
`equal to a
`particular temperature, the water that has moved from the anode to the
`as steam. As the hydrogen gas
`cathode (electroosmotic water) is present
`pressure at the cathode becomes higher, however, the percentage of liquid
`water is present in the cathode, part of the water is pushed
`increases.
`If liquid
`back to the anode because ofa differential pressure between the cathode and
`
`moveinside an
`
`electrolyte
`
`If the
`
`water
`
`anode. The amount of water
`
`backto the anode increases with
`
`to a
`
`elevating
`pushed
`hydrogen gas pressure at the
`hydrogen gas pressure at the cathode. As the
`cathode increases, therefore, it becomes more
`likely that the anode floods with
`pushed back to the anode. When such an eventof flooding
`occurs and
`water
`interferes with gas diffusion at the anode, the electrochemical hydrogen pump may
`become less efficient in hydrogen pressurization because of increased diffusion
`resistance in the electrochemical hydrogen pump.
`an electrochemical hydrogen pump according
`[0039] To address this,
`one of the first to sixteenth
`seventeenth
`of the
`disclosure is: In any
`
`aspect
`present
`aspects, the second surface
`the anode gas diffusion
`
`repellent.
`
`layer
`
`in the electrochemical
`
`layer,
`
`which is closer to the anode
`
`catalyst layer,
`hydrogen pump may be water-
`
`of
`
`as
`
`[0040] Configured
`
`such, the electrochemical hydrogen pump according to this
`on a stream of anode gas, water
`pushed back to the anode
`aspect quickly drains,
`by virtue of the second surface layer, which is closer to the anode catalyst layer, of
`the anode gas diffusion layer being water-repellent. Flooding is therefore reduced,
`as a
`result, adequate gas diffusibility is maintained at the anode.
`an
`In
`membrane becomes
`
`and,
`
`[0041]
`
`general,
`
`electrolyte
`
`highly proton-conductive
`
`under
`
`and
`
`humidified conditions
`
`high-temperature
`highly
`(e€.g., approximately
`60°C), and an electrochemical hydrogen pump becomes moreefficient in
`hydrogen pressurization under such conditions. As stated, when an electric
`current flows between an anode and a cathode in an electrochemical hydrogen
`9
`
`P1023473
`
`
`
`pump, protons
`
`moveinside an
`
`electrolyte membrane from the anode to the
`water with them. Then part of the electroosmotic water, which
`cathode, bringing
`has moved from the anode to the cathode, is drained from the cathode together
`with
`
`high-pressure hydrogen gas.
`
`[0042]
`
`If the electric current that flows between the anode and cathode has
`
`increased
`
`In that
`
`the amount of electroosmotic water increases, and the amount
`density,
`of electroosmotic water drained out of the cathode increases accordingly.
`case, the electrochemical hydrogen pump may become less efficient in hydrogen
`pressurization because the electrolyte membrane in the electrochemical hydrogen
`pump dries more
`
`quickly.
`[0043] To address this,
`of the
`
`present
`eighteenth aspect
`seventeenth aspects, the first surface
`separator, of the anode gas diffusion
`may be hydrophilic.
`
`an electrochemical hydrogen pump according
`one ofthe first to
`disclosure is: In any
`
`to an
`
`layer,
`
`which is closer to the anode
`
`layer
`
`in the electrochemical
`
`hydrogen pump
`
`as
`
`such, the electrochemical hydrogen pump according to this
`[0044] Configured
`aspect has a
`water-retaining function in the first surface layer, which is closer to
`the anode separator, of its anode gas diffusion layer by virtue ofthis first surface
`layer being hydrophilic. Water in anode gas can therefore be easily supplied
`to
`the electrolyte membrane through the anode gas diffusion layer, hence reduced
`risk of
`membrane in the electrochemical
`drying up of the
`
`electrolyte
`
`hydrogen
`
`pump.
`
`The
`
`describes embodiments of the present disclosure with
`[0045]
`following
`reference to the attached drawings. The embodiments described below areall
`illustrate examples of the aspects described above. The shapes, materials,
`structural elements, the positions of and connections between elements, and other
`information given below are
`merely examples and are not intendedto limit the
`aspects described above unless given in a claim. Those elements that are not
`recited in the independent claims, which represent the most
`generic concepts of
`are described as
`the
`elements. An element
`described above,
`aspects
`the same reference
`
`only
`
`to
`
`help
`
`assigned
`once. The
`
`optional
`drawings may be described
`sign
`are schematic illustrations of structural elements
`
`in different
`
`drawings
`given
`understand and therefore may be inaccurate in the representation of shape,
`relative dimensions, etc.
`
`10
`
`P1023473
`
`
`
`Embediment 1
`
`Device Configuration
`Figs. 1A and 2A are
`electrochemical
`
`[0046]
`
`hydrogen pump according
`
`diagrams illustrating
`
`an
`
`example of an
`1B is an
`to Embodiment 1.
`
`Fig.
`
`enlarged
`
`view of
`
`portion
`2B is an
`
`1A.
`
`IB of the electrochemical
`
`in
`
`hydrogen pump illustrated
`IIB of the electrochemical
`
`view of
`
`portion
`
`hydrogen
`
`Fig.
`Fig.
`enlarged
`pump illustrated in Fig. 2A.
`1A illustrates a vertical section of an electrochemical hydrogen pump
`Fig.
`[0047]
`100 that includes a
`straight line passing through the center of the electrochemical
`hydrogen pump 100 and the center of a cathode gas outlet manifold 50 in plan
`view. Fig. 2A illustrates a vertical section of the electrochemical hydrogen pump
`100 that includesa
`the center of the electrochemical
`line
`
`straight
`passing through
`hydrogen pump 100, the center of an anode gas inlet manifold 27, and the center
`of an anode gas outlet manifold 30 in
`view.
`
`plan
`In the example illustrated in Figs. 1A and 2A, the electrochemical
`[0048]
`hydrogen pump 100 includes at least one
`hydrogen pump unit 100A.
`[0049] The electrochemical hydrogen pump 100 has a stack of multiple
`hydrogen pump units 100A. For example, in Figs. 1A and 2A, there is a three-tier
`stack of hydrogen pump units 100A. This, however, is not the only possible
`number of hydrogen pump units 100A. That is, any number of hydrogen pump
`units 100A can be used as
`on the basis of the
`
`such as the volume of
`
`hydrogen
`
`the electrochemical
`
`appropriate
`
`operating conditions,
`hydrogen pump 100
`
`an
`
`pressurizes.
`[0050] A hydrogen pump unit 100A includes an
`electrolyte membrane 11,
`a cathode CA,
`a cathode separator 16,
`an anode separator 17, and an
`anode AN,
`In a
`an
`insulator 21.
`hydrogen pump unit 100A, furthermore,
`electrolyte
`an anode catalyst layer 13,
`a cathode catalyst layer 12,
`an anode
`a cathode gas diffusion layer 14,
`an anode separator 17,
`gas diffusion layer 15,
`and a cathode separator 16 are stacked together.
`The anode AN is on
`first
`surface of the
`
`membrane 11,
`
`primary
`[0051]
`11. The anode AN is an electrode that includes an anode
`
`electrolyte
`
`membrane
`
`catalyst layer
`
`13 and an
`
`anode gas diffusion
`
`15. There is a
`
`layer
`ring-shaped
`surrounding
`anode catalyst layer 13 in plan view, and the anode catalyst layer 13 is sealed with
`the seal 43 properly.
`
`seal 43
`
`the
`
`11
`
`P1023473
`
`
`
`[0052] The cathode CAis on a second primary surface of the electrolyte
`membrane 11. The cathode CA is an electrode that includes a cathode catalyst
`layer 12 and a cathode gas diffusion layer 14. There is a
`ring-shaped seal 42
`the cathode
`12 in
`plan view, and the cathode
`
`surrounding
`
`catalyst layer
`
`catalyst
`
`layer
`
`12 is sealed with the seal 42
`
`properly.
`
`membrane 11 is sandwiched between
`
`As aresult of these, the
`[0053]
`electrolyte
`the anode AN and cathode CA to touch each of the anode and cathode catalyst
`layers 13 and 12. The stack of the cathode CA, electrolyte membrane 11, and
`anode AN is referred to as a membrane electrode assembly (hereinafter MEA).
`[0054] The electrolyte membrane 11 is proton-conductive. The electrolyte
`as
`membrane 11 can be of any type
`as it is proton-conductive. For example,
`long
`membrane 11 can be a
`or
`the
`
`electrolyte
`
`fluoropolymer
`these are not the
`
`hydrocarbon polymer
`
`only possibilities. Specific
`
`electrolyte membrane, although
`of membranes that can be used as the
`
`membrane 11 include
`
`electrolyte
`examples
`Aciplex® (Asahi Kasei Corporation) membranes.
`Nafion® (DuPont) and
`[0055] The anode catalyst layer 13 is on the first primary surface of the
`electrolyte membrane 11. An example of a
`catalyst metal contained in the anode
`catalyst layer 13 is platinum, but this is not the only possibility.
`[0056] The cathode catalyst layer 12 is on the second primary surface of the
`electrolyte membrane 11. An example of a
`catalyst metal contained in the
`but this is not the
`cathode
`12 is
`
`catalyst layer
`
`platinum,
`
`only possibility.
`
`of
`
`carriers for the cathode and anode
`
`catalyst layers
`
`for
`
`example
`
`of carbon
`
`[0057] Examples
`catalyst
`12 and 13 include, but are notlimited to, carbon
`particles,
`black or
`graphite, and electrically conductive oxide particles.
`Inthe cathode and anode catalyst layers 12 and 13, fine particles of
`[0058]
`catalyst metal are held on a
`catalyst carrier in a
`state.
`highly dispersed
`Usually,
`hydrogen ion-conductive ionomer componentis added to these cathode and
`anode catalyst layers 12 and 13 to
`expand the field for electrode reactions.
`[0059] The cathode gas diffusion layer 14 is on the cathode catalyst layer 12.
`14 is a
`and
`The cathode gas diffusion
`porous medium, conducts
`
`layer
`
`therethrough. Desirably,
`
`electricity,
`the cathode gas diffusion
`
`layer
`
`a
`
`14
`
`follow the
`
`and deformation of
`
`properly
`displacement
`structural elements of the electrochemical hydrogen pump 100 that occur in
`response to a differential pressure between the cathode CA and anode ANwhile
`12
`
`P1023473
`
`allows gases to diffuse
`is elastic so thatit will
`
`
`
`In this embodiment, the cathode gas
`the hydrogen pump 100 is in operation.
`diffusion layer 14 in the electrochemical hydrogen pump 100 is an element made
`from carbon fibers. For example, the cathode gas diffusion layer 14 may be a
`or
`porous carbon fiber sheet, such as a
`of carbon paper, carbon cloth,
`piece
`carbon felt. The base material for the cathode gas diffusion
`does not need to be a carbon fiber sheet. For
`
`the base material for the
`
`layer 14, however,
`
`rigid
`
`the electrochemical
`
`layer
`
`highly
`
`example,
`cathode gas diffusion layer 14 may be a sintered mass of metal fibers, for example
`a sintered mass of metal
`or stainless steel,
`a titanium alloy,
`made from titanium,
`particles made from any such metal, etc.
`[0060] The anode gasdiffusion layer 15 is on the anode catalyst layer 13. The
`anode gas diffusion layer 15 is a porous medium, conducts electricity, and allows
`gases to diffuse
`15 is
`the anode gas diffusion
`therethrough. Desirably,
`so that it will limit the
`and deformation of structural elements of
`displacement
`hydrogen pump 100 that occur in responseto a differential
`pressure between the cathode CA and anode AN while the hydrogen pump 100is
`in operation.
`Inthis embodiment, the anode gas diffusion layer 15 in the
`[0061]
`electrochemical hydrogen pump 100 includes a porous carbon sheetthatis a
`may
`a sheet-
`powder molded body. This powder molded body
`be, for example,
`shaped sintered body made from carbon particles (carbon powder sintered body).
`To take a
`15 may
`the anode gas diffusion
`
`[0062]
`as illustrated in
`
`specific example,
`layer
`a
`porous carbon sheet 15S whose first surface
`
`include,
`
`rigid
`
`layer 15B,
`Fig. 3,
`whichis closer to the anode separator 17, contains
`carbon. Asstated,
`amorphous
`the porous carbon sheet 15S can be a
`sheet-shaped sintered body made from
`In that case, the carbon particles in the porous carbon sheet 15S
`carbon particles.
`are of amorphous carbon, in which carbon-carbon bonds are in an
`amorphous
`structure. As such, amorphous carbon is highly rigid. That is, the higher the
`percentage of amorphous carbon in the porous carbon sheet 15S is, the more
`the porous carbon sheet 15S is. The porous carbon sheet 15S, therefore, has
`layer 15B, which is closer to the anode
`separator
`or an inner
`under this first surface
`
`in its first surface
`
`higher rigidity
`17, than in the
`
`layer
`
`15A
`
`lying
`
`layer 15B,
`
`layer
`
`15A.
`[0063] To summarize, the porous carbon sheet 15S is a stack in which one
`primary surfaceofits first surface layer 15B is in contact with a
`primary surface of
`13
`
`P1023473
`
`
`
`the anode separator 17, with the other primary surface of the first surface layer
`15B in contact with one
`primary surface of the layer 15A therebeneath (inner
`layer). The other primary surface of the inner layer 15A is in contact with the
`anode
`13.
`
`catalyst layer
`
`[0064] Examples
`
`of
`
`amorphous
`
`carbon materials include
`
`glassy
`
`carbon
`
`(glass-
`
`like
`
`and diamond-like carbon
`
`carbon)
`(DLC).
`In this embodiment, furthermore, the thicknesst of the rigid layer, which
`[0065]
`is in contac
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