Note: Descriptions are shown in the official language in which they were submitted.
1086378 `
This invention relates to devices employing electro-
chemical reactions as well as to the processes employed in these
devices.
These devices comprise a cell having at least one
anode compartment and one cathode compartment. Each of these com-
partments comprises an electrode with at least one active material
participating in the electrochemical reaction carried out in said ; !
compartment, and an electrically conductive member, referred to
as the electron collector, intended to collect the electric charges
liberated during the electrochemical reaction or to deliver the
electrical charges necessary for said reaction, which collector may
be part of the electrode.
The invention concerns, in particular, electrochemical
devices at least one compartment of which contains a fluid in move-
.~ ment, said fluid being in contact with one face of a plate. This
plate, which is mounted in a support, constitutes, for instance, ~ :
a separator, in particular an ion-permeable separator, or an elec-
trode of a polarity opposite that of the compartment in which the
fluid is contained.
The production of the assembly of the plate and sup-
port is customarily effected in the following manner:
~ -the plate is cut out along a given geometrical profile
and to precise dimensions:
: - the production by machining or molding of a support
comprising, recessed therein, a profile of a shape identical to ~ :
that of the edges of the plate:
- assembling of the plate to the support by gluing, the
purpose of this glue being to assure the mechanical holding of the
- plate and the thightness of the assembly with respect to fluid,
- finishing operation directed at obtaining, by scrap- :
ing off the excess glue, uniform surfaces in the vicinity of the
junctions of the plate with the glue.
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1086378
This method of mounting has the following drawbacks:
(a) it requires a succession of manual operations which
are lengthy, costly, and nonreproducible, since the quality of the
finished product is due to a large extent to the skill of the oper-
ator;
(b) the scraping may well damage the surface of the
plate,
(c) it is impossible to obtain perfectly uniform junc-
tion surfaces, despite a careful scraping off of the excess glue;
as a matter of fact, irregularities remain at the
junction surfaces in the form of hollows or roughnesses which cause
heterogeneities in the circulation of the fluid with spaces in
which the fluid is stagnant without being renewed; as a result,
- there takes place in these spaces an accunulation of reaction pro-
ducts or of active material, particularly when the fluid is a
liquid, for instance an electrolyte, which causes passivation pheno-
mena as a result of insufficient diffusion velocities, furthermore,
when the fluid contains solid or liquid particles, the accumula-
tion of said particles in the spaces where the fluid is stagnant
rapidly leads to the obstruction of the compartment; the device thus
becomes rapidly unusable;
(d) in order to avoid the appearance of bubbles in the
glue, it is necessary to limit its thickness, withlthe result that
the mechan1cal strength of the assembly and its tightness to fluid
is made very questionable. m e mechanical strength and the tight-
ness are still more difficult to obtain when the plate has a material
which is difficult to glue on one of its surfaces. This is true,
in particular, of gaseous diffusion electrodes having a hydrophobic
coating or a hydrophobic membrane.
The purpose of the invention is to avoid these draw-
backs.
Accordingly, the assembly in accordance with the inven-
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1~)86378 ~ .
tion, which is intended to be used in an electrochemical device,
this assembly comprising a plate and a support, is characterized
by the fact that the plate has a bend forming a bend line on at
least one edge, the peripheral zone of said bend, referred to as
the anchoring zone, being situated in the support, and at least
a portion of the support being obtained by the molding of one or
more moldable materials onto said anchoring zone in such a manner
that a face of the support adjacent to the anchoring zone connects
with a face of said plate along a connecting line forming a uni-
form junction surface, these faces being intended to be in contactwith a fluid in movement in the electrochemical device, an angle a
determined, in the vicinity of the bend line, by said face of the
plate and the extension of the corresponding face of the anchoring
zone being situated outside the plate, said angle ~ being measured
in a plane perpendicular to said face of the plate and to said ex-
tension of the corresponding face of the anchoring zone.
The invention will be readily understood by means of
the description of illustrative, nonlimitative examples given below
~ with reference to the drawing, in which:
; 20 F1g. 1 shows schemitically a cross section of a known
assembly:
Figs. 2 and 3 each show schematically a cross section
of an assembly effected by molding;
Fig. 4 shows schematically a cross se,ction of an as-
sembly in accordance with the invention taken on section line IV-
IV of Fig. 5:
Fig. 5 shows schematically a top plan view of the as-
sembly shown in Fig. 4;
Fig. 6 shows schematically a cross section of another
assembly in accordance with the invention;
Fig. 7 shows schematically a cross section of still
another assembly in accordance with the invention; ... !
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1086378
Fi.g 8 shows schematically a cross section of yet an-
other assembly in accordance with the invention in which the plate
is a gaseous diffusion electrode; and
Fig. 9 shows schematically a cross section of an elec-
trochemical device suing the assembly shown in Fig. 8.
Fig. 1 shows an assembly 10 comprising a plate 1 and a
support 2, this assembly being produced in known manner. The plate
1, for instance, is of rectangular shape, the support 2 being arrang-
ed around said plate. The support 2 has a recess 21 which corres-
ponds substantially, in recess, to the profile of the edge 11 ofthe plate 1. A glue 3 makes it possible to assemble the plate 1 to
the support 2.
The assembly 10 is intended to be mounted in an electro-
chemical device (not shown in this figure) in such a manner that the ;-
face 12 of the platel is in contact with a moving fluid. The plate
1 may, for instance, be a separator or an electrode. -~
The surface 31 of the glue 3 which assures the connec-
tion of the support 2 with the face 12 of the plate 1 is referred
to as the junction surface. This junction surface 31, which is in-
tended to be also in contact with the fluid, has irregularities 311,
which irregularities 311 are impossible to avoid completely, even -
with a careful scraping off of the excess of the glue 3.
Moreover, the amount of glue 3 is neclessarily small in
order to avoid the appearance of bubbles during the effecting of the
assembling and during the drying of this glue 3. One then observes
the drawbacks described above.
Fig. 2 shows another assembly 100 of the plate 1 with
the support 2. In this assembly 100, the molded product 3 was intro-
duced by molding between the support 2 and the plate 1 in such a
manner that the junction surface 31 does not have any irregularities
this junction~surface 31 and the face 12 of the plate 1 being locat-
ed in the extension of each other.
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1~)86378 ~ !
This assembly 100 avoids heterogeneities in flow of
the fluid in the electrochemical device and limits the number of
operations to be carried out in order to effect the assembling, b~ut
on the other hand the mechanical strength and the tightness,of the
assembly 100 are still insufficient, since the molded product 3 at
no place covers or overlaps the face 12, so that the drawbacks
described above are avoided only for a short period of use.
Fig. 3 shows another assembly 1000, in which the por-
tion 32 of the molded product 3 covers or overlaps the portion 121
of the face 12 of the plate 1. The junction surface 320 of this
portion 32 connects with the face 12 along the connecting line 120. ~-
This junction surface 320 forms the angle A with the
portion 122 of the face 12 not covered or overlapped by the portion
32, said portion 122 and the junction surface 320 being in contact
with the fluid. The angle A is measured in the vicinity of the
connecting line 120, in a plane perpendicular to the junction sur-
face 320 and to the portion 122 (plane of Fig. 3).
Despite the covering or overlapping of the portion 121,
this assembly 1000 is, however, fragile when the angle A is greater
than 160 as a result of the accentuated wedge shape of the portion
32. As a matter of fact, the angle B of this wedge, measured in
the vicinity of the connecting line 120 and perpendicular to the
junction surface 320 and the portion 121, is then ~ess than 20,
since it is equal to 180 - A. This fragility becomes particularly
critical when the angle A is equal to 180, that is to say when the
junction surface 320 and the face 12 connect tangentially with each
other. Furthermore, poor union may take place between the molded
product 3 and the plate 1, causing defective tightness of this
- assembly 1000 whatever the angle A.
Figs. 4 and 5 show an assembly 400 in accordance with
- the invention. This assembly 400 comprises a plate 4 which is iden-
tical to the plate 1 except that it has bends 41 on its edges. The
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face 40 of the plate 4 is intended to be in contact with a fluid
when the assembly 400 is used in an electrochemical device (not
shown in this figure). The peripheral portion 411 of each bend 41,
called the anchoring zone, comprises a face 4110 corresponding to
the face 40. In the vicinity of the bend line 4111 of each bend
41, said bend line 4111 separating the faces 40 and 4110, the face
40 forms with the extension 41100 of the face 4110 and angle ~
located outside the plate 4, this angle ~ being measured in a plane
perpendicular to the face 40 and to the extension 41100 of the face
4110 (plane of Fig. 4). In order to simplify the assembling, the
angles ~ of the bends 41 of the assembly 400 may have the same value
b~t this is not necessary. The bends 41 of angle ~ can be obtained
either directly upon the production of the plate or by a mechanical
operation carried out subsequently on the plate after its produc-
tion, for instance a shaping operation by stamping or pressing. The
assembly 400 was obtained by placing the plate 4 in a mold (not
shown) and by producing the reinforcements 51 and 52 constituting
the support 5 by introducing into the mold a moldable material, for
instance a thermoplastic or thermosetting material. The face 53
of the reinforcement 51 connects with the face 40 along a con-
necting line which is, for instance, substantially identical with
the bend line 4111 of the corresponding bend 41. The face 53, which
is therefore a junction surface and which is without irregularities,
forms with the face 40 of the plate 4 the angle A, the definition
of which is identical to that given above for the angle A shown in
Fig. 3, the angles A of the assembly 400 having, for instance - but
; not necessarily - the same values. This face 53 of the support 5
forms the angle C with the face 4110 of the bend 41, said angle C
- being measured at the vicinity of the bend line 4111 and in a plane
30- perpendicular to the faces 53 and 4110 (plane of Fig. 4). The angle
C is eq~al to 180 + a - A and, therefore, whatever the angle A,
one can select the value of the angle ~ such that the angle C ob-
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tained, preferably at least equal to 20, assures a good anchoring
of the plate 4 in the support 5, that is to say a good firmness and
a goodtightness, the reinforcements 51 and 52 surrounding each an-
choring zone 411. For example, when the angle A is equal to 180,
that is to say when the faces 53 and 40 connect tangentially with
each other along the bend line 4111, the angle a is selected prefer- -
ably at least equal to 20 and at most equal to 90.
The mechanical strength of the assembly 400 and its
tightness are particularly good when the plate 4 has a porous struc-
ture, for instance a sintered structure, and when the bends 41 are
; obtained by a mechanical operation carried out on the plate 4, for
instance a shaping in a press. In fact, there are obtained in this
manner micro-cracks which permit a limited migration of the moldable
material or materials. In this case, the value of the angle a
preferably does not exceed 60, since a bend of an angle a greater
than 60 may cause a decrease in the mechanical strength of the
plate 4 as a result of excessive cracks, this angle a being then
preferably substantially equal to 45.
The plate 4 may comprise an additional bend 42, locat-
ed at the periphery of bend 41 of angle a, as shown on Fig. 4. Thie
angle ~ of this bend 42, determined in a manner similar to the angle
a by the face 4110 of the bend 41 and the extension 4200 of the
corresponding face 420 of the peripheral portion 421 of the bend 42, .
is of a direction opposite that of the angle a of,the corresponding
bend 41, that is to say the angle ~ is located inside the plate 4, ;~
said angle ~ being measured, in the vicinity of the bend line 4112
-: of the corresponding bend 42, in a plane perpendicular to the face
4110 of the anchoring zone 411 and to the extension 4200 of the
face 420, said bend line 4112 separating the faces 4110 and 420.
One thus.further improves the mechanical strength and
the tightness of the assembly 400, the additional bend 42 being
preferably on the inside of the support 5. The absolute value of
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:1086378
the angle ~ is preferably substantially equal to that of the cor-
responding angle a, as shown in Fig. 4.
If h is the distance between the bend lines 4111 and
4112 which form the ends of the face 4110 of the anchoring zone 411,
said distance being measured in a plane containing the corresponding
angle a and perpendicular to the portion of face 40 adjacent
the face 4110, h is preferably between e and 6e, e being the thick-
ness of the plate 4 when said thickness is constant, or the thich-
ness of the plate 4 in the vicinity of said anchoring zone 411 if
said thickness is variable.
In the assembly 400 thus described, the face 53 of the
support 5 and the face 40 of the plate 4 can, for instance, form a
uniform flat surfaoeiwhich permits a particularly homogeneous flow
of the fluid with which they are in contact when the assembly 400
is mounted in the electrochemical device, the good coherence of the
assembly 400 also permitting good thightness with respect to this
fluid.
This arrangement,in which the faces 53 and 40 connect
tangentially with each other, is particularly useful in the event
that the fluid contains particles, since a connection of angle A
other than 180 runs the risk of causing a catching of the particles.
.
One can also, for instance, contemplate assemblies in accordance
with the invention such that the faces 53 and 40 of the support 5
and of the plate 4, respectively, connect with each other substan-
tially tangentially, without their being in the extension of each
other.
Fig. 6 shows such an assembly 60 in accordance with
the invention. The constituent elements of this assembly 60 are
the same as those of the assembly 400, with the difference that
the faces 54 of the support 5 which connect tangentially with the
face 40 of the plate 4 have the shape of portions of cylinders of
revolution of radius r, the faces 54 and 40 thus assuring a uniform
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1086378
passage for the flow of the fluid in the electrochemical device,
this fluid, for instance, possibly containing particles.
When the bends are obtained by mechanical operation,
the operation can possibly be carried out directly in the mold. On
the other hand, the process in accordance with the invention is ap-
plicable to any known molding operation, such as, for instance, in-
jection molding. The moldable materials used for the molding may
be very different, inorganic, metallic, or organic, for instance
elastomeric, thermoplastic, or thermosetting polymers.
The support 5 is made by molding two reinforcements 51
and 52 around the anchoring zone 411 of the plate 4, but it is also
possible to produce the support 5 by molding a single reinforcement
or more than two reinforcements, the materials of these reinforce-
ments being either identical or different. -
It may also be advantageous, in order to increase the
speed of production, to introduce one or more reinforcements which
;~ have already been prepared, for instance in the form of special
shapes, into the mold together with the plate, the rest of the sup-
port being produced by molding or one more materials in order to
assure the bond between the different components of the assembly.
Fig. 7 shows such an assembly 70. This assembly 70
is produced by arranging the plate 4 on a profiled member 55 of a
support S in a mold (not shown). This profiled sh,ape comprises a
groove 551, on the bottom of which there rest the bends 41 and 42
via the faces thereof opposite the face 40 of the plate 4. A mold-
i~ able material is injected into the mold so as to fill up the empty
' space of said groove 551, the smooth face 561 of this reinforcement
56 which is thus obtained connecting, for instance, substantially
tangentially to the face 40.
` 30 Fig. 8 shows, in a section similar to that of Fig. 4,
another assembly 80 in accordance with the invention, similar to the
assembly 400 shown in Figs. 4 and 5, the angle A being equal to 180.
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1()86378
In this assembly 80, the plate 4 is a gaseous diffusion
electrode. This electrode 4 comprises a porous body 43. Against
one face 431 of this porous body 43 a porous layer 44 is applied,
which is intended to serve as a hydrophilic separator.
The face of this separator 44 opposite the face 431 of
the body 43 constitutes the face 40 of the plate 4. On the face
432 of the body 43 which is opposite the face 431 there is applied
a porous layer 45 intended to serve as a hydrophobic separator.
The thicknesses of the separators 44 and 45 forming part of the
electrode 4 are preferably small as compared with thickness of the
body 43, these thicknesses being measured in ~he central zone of
the electrode 4, the ratio between each of the thicknesses of the
separators and the thickness of the body 43 being for instance
between 0.25 and 0.05. The body 43 has a fine metallic grid
430 intended to serve as electron collector and electrically con-
nected with a metal rod 6 intended to be connected to an electric
terminal in the electrochemical device. By way of illustration
and not of limitation, the assembly 80 is made in the following
manner: the body 43 is prepared in known manner by the sintering,
in the form of a substantially rectangular plate, of a mixture
of powdered carbon black and powdered nickel, which mixture is
`~ arranged around the nickle grid 430, said body containing silver,j ,
as the catalyst and polytetrafluorethylene as the hydrophobic
agent. - ;
The hydrophilic separator 44 is produced by dispersing
fibers onto the face 431 from a solution of one or more organic
~ polymers in a solvent or a solvent mixture, as described in a
; - patent application in France No. 75 38 242 which has become
available to the public on 8 July 1977, under Mo. 2,335,062.
- 30 By way of example, this dispersion is effected from a
solution of polyvinylchloride in a mixture of tetrahydrofuran and
cyclohexanone, the respective proportions (parts by weight) of poly-
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1086378
mer, tetrahydrofuran, and cyclohexanone being 15-70-15, respective-
ly.
The hydrophobic separator 45 is produced by applying
a sheet of polytetrafluorethylene onto the face 432 of the body 43.
The body which is thus covered with the separators 44
and 45 is then shaped in a press in such a manner as to obtain the
bends 41 and 42, these bends surrouding the rectangular face 40 of
the plate 4 (Fig. 5). The angles a and ~ ~not shown in order not
to clutter Fig. 3 of the drawing) have absolute values which are
substantially equal to 45.
The electrode 4 which is thus shaped is placed in a
mold (not shown) with the metal bar 6, for instance of copper, this
bar being placed against one of the sides of the electrode 4, and
the reinforcements 51 and 52 are obtained by molding resin compounds
comprising for instance an epoxy resin for example resin Epikote -
828 from the Shell company around the edges of the electrode and
around the bar 6, one end of which remains free, the faces 53 and
40, in the extension of each other, forming a flat surface. ~ -
The desirability of effecting the press shaping on an
electrode having the separa-tors described is due to the fact that
this shaping causes the appearance of microfissures both in the
body 43 and in the separators 44 and 45 and therefore a good mecha- ~ -
nical strength of the assembly 80 as a result of al;migration of the
moldable compound into these microfissures during the molding. In
order to avoid excessive migration, the content of fillers in the
moldable compound is maintained preferably at least equal to 80 %
, (
by weight of the total mixture.
The assembly 80 is used, for instance, in an electro-
chemical generator of the metaljair type whose anode compartment
contains in movement a liquid electrolyte, in which there are con-
tained particles formed at least in part of an anodic active metal,
in particular zinc. Such a generator 9 is shown in Fig. 9. This
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~086378
generator 9 comprises an anode compartment 7 and a cathode compart-
ment 8. Within the cathode compartment 8 there is arranged the
assembly 80 comprising the electrode 4 which is used as an air or
oxygen diffusion cathode, the cathodic active material being oxygen.
The conduits for the entrance and departure of the gas
into and from the cathode compartment 8 are indicated diagrammatical-
ly by the arrows F8 and F'8. The air or oxygen arrives in the
cathode ccmpartment 8 in contact with the hydrophobic separator 45,
which is intended in known manner to avoid the migration of the elec-
trolyte through the entire thickness of the cathode 4.
The anode compartment 7 comprises an anode collector
71 arxanged opposite the hydrophilic separator 44 and consisting for
instance of a metal sheet. The anode compartment 7 contains an al- -
kaline aqueous electrolyte ~not shown) in which there are contained
zinc particles 72, the hydrophilic separator 44 being permeable to
the electrolyte and impermeable to the zinc particles 72. The elec-
trolyte and the zinc particles 72 constitute the anode of the gene-
rator.
~;~ A deuice, diagrammatically indicated by the arrow F7,
makes it possible to introduce into the anode compartment 7 the
~ electrolyte and the zinc particles 72 which flow in the anode com-
,l partment 7 between, on the one hand, the anode collector 71 and, on
the other hand, the surfaces 40 and 53 of the asse,mbly 80. The zinc
particles 72 are oxidized during the course of their contacts with
the collector 71, losing electrons, while the oxygen is reduced in
the gaseous diffusion electrode 4 by electrons coming from the dis-
charge circuit (not shown) disposed between the positive terminal P
connected to the rod 6 and the negative terminal ~ connected to
the anode collector 71. A device diagrammatically indicated by the
arrow F'7 makes it possible to evacuate from the anode compartment
7 the eiectrolyte which contains the zinc particles 72 which have
not been entirely consumed by electrochemical oxidation. A path 91
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outside the anode compartment 7 makes it possible to recycle the
electrolyte and the particles 72 into the feed device F7 from the
evacuation device F'7 via a pump 910 and a surge tank 911. A de-
vice 912 leading into the path 91 makes it possible to introduce
zinc particles into said path so as to maintain the percentage by
weight of zinc in the electrolyte constant during each test.
The operating conditions, which are in no way limita-
tive, may for instance be as follows:
- electrolyte: 4-12 N potassium hydroxide solution
10 (4 to 12 mols of potassium hydroxide per liter),
- average size of the zinc particles introduced into
the electrolyte: 10-20 microns,
- percentage by weight of zinc in the electrolyte:
- 20-30% of the weight of the electrolyte,
- speed of circulation of the electrolyte in the anode
compartment: 10-30 m/minute. r
; One thus continuously obtains a power of the order of
` 50 watts by maintaining the amount of zinc dissolved in the elec-
trolyte at less than a value above which the zinc particles would
20 become passivated, this limit being, for instance, 120 g/L in the
case of 6 N potassium hydroxide solution. This regulation is ob-
tained, for instance, be regenerating the electrolyte in an annex-
ed installation or by replacing the zincated elect,rolyte by a pure
" solution of potassium hydroxide when the critical value is reached.
The operation of the generator is thus limited only by the life of
the diffusion electrode 4, namely several thousands of hours, since
no disturbance of the flow and no degradation of the assembly 80
are observed.
On the other hand, the use in this same generator of
30 assemblies similar to those shown in Figs.l to 3 comprising an elec-
trode identical to the electrode 4 but without bend rapidly leads
to obstruction of the anode compartment 7, the operating conditions
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1~86378
. being the same as previously. This obstruction is due to the catch-
. ing of the particles on the irregularities of the faces of these
assemblies in contact with the electrolyte, which irregularities
are due either to the production of the assemblies or to the degra-
dation of these assemblies in the generator. .
Furthermore, the poor thightness of these assemblies
leads to a migration of the electrolyte towards the air or oxygen
in contact with the hydrophob.ic separator 45,. which very detrimental-
ly affects the performance of the electrode 4.
Of course, the invention is not limited-to the embodi-
ments which have been described above, on basis of which one can
contemplate other modes and embodiments, without thereby going be-
yond the scope of the invention.
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