|Title of Invention||
ELECTROLYTIC CELL WITH SEGMENTED AND MONOLITHIC ELECTRODE DESIGN
|Abstract||The invention relates to an electrolytic cell with segmented and monolithic electrode assembly. The electrolytic cell consists of two semi-shells and encompassing mainly the inlet and outlet devices, components for the flow control, a membrane as well as anode and cathode. The electrode (1) may have any surface structure and they are connected on the side opposite to the membrane to conductive strip (2) connected to the respective semi-shell. The main feature of the invention is to segment the electrodes (A, B) and to fabricate each electrode segment (A, B) with its adjacent supporting strips (2) as a joint less monolith from a single semi-finished work piece.|
Electrolytic cell with segmented and monolithic electrode design
 The invention relates to an electrolytic cell essentially consisting of two semi-shells
encompassing inlet and outlet devices, components for flow control, an anode and a cathode
separated by a membrane. The electrode may have any surface structure and it is connected
to the respective semi-shell on the side opposite to the membrane through a multiplicity of
conductive strips. According to the invention, at least one of the two electrodes is provided
with a segmented structure, each of the electrode segments and its adjacent supporting
strips being fabricated as a monolithic jointless assembly from a single semi-finished
 It is a state-of-the-art practice to weld the electrodes to the inner wall of the respective
semi-shell through strips that are arranged perpendicularly to the electrode and the semi-
shell rear wall, i.e. aligned in the direction of the pressing force. Electrically insulating
spacers are inserted in the area between the membrane and the electrodes such that the
membrane is clamped and consequently fixed between a multiplicity of spacers with the
pressing force acting from the external side. The spacers are arranged in opposed pairs and
the strips are positioned in correspondence of the spacers on the opposite side of the
 Electrolysers of this type are for instance described in DE 196 41 125 and
EP 0 189 535. The cell components are optimised in order to minimise the amount of
required material simultaneously ensuring the necessary stiffness and strength of the
finished cell. When fabricating a device in accordance with DE 196 41 125 it is necessary to
prefabricate the individual members, part of which have a relatively reduced thickness, to
position the same in a straightening bench and to weld them together to assemble the cell. In
case of large orders this is a very time-consuming and expensive process, considering that
one electrolyser room is usually comprised of many thousand individual cells.
 Stringent requirements must be met for the dimensional accuracy of the cell
components because even minor deviations which may be caused for instance by thermal
expansion of the material, inaccurate positioning of components or dimensional variation of
individual components, may lead to problems of installation or of cell operation.
 It is therefore one of the aims of the invention to overcome the inadequacy of the
present technology and to provide an electrolyser comprising cell components of improved
dimensional accuracy and easier to install.
 This and other aims are achieved by means of an electrolytic cell essentially
consisting of two semi-shells encompassing inlet and outlet devices, components for flow
control, an anode and a cathode separated by a membrane. The electrodes may have any
surface structure, profile or perforation. On the side opposite to the membrane, the
electrodes are electrically connected with the respective semi-shell through strips and are
characterised by a segmented design, each electrode segment being formed from a single
semi-finished piece as a jointless monolith comprising at least one and preferably two
adjacent supporting strips.
 The segmented structure of the electrode of the invention is particularly
advantageous in that the tolerance margin can be consequently reduced, in particular since
the tolerance in the body height merely depends on one component or processing step,
which is particularly important considering the big electrode size in the standard practice (2 -
3 m2). Conversely, in the design of the state of the art the overall construction tolerance is
determined by the features of two distinct components, namely the length of the strip and the
thickness of the electrode sheet, whose junction is moreover exposed to the thermal impact
of the welding process.
 Positioning the electrode parallel to the membrane plane is facilitated as the strips are
already attached to the electrode. Allowing for a displacement during the alignment can also
be obtained in a straightforward manner by providing a correspondingly large tolerance in the
contact area of the strip feet and in the level parallel to the membrane. No thermal distortion
will take place when the strips are fixed to the electrode as these are no longer welded but
cold-formed on bending or punching machines. A further advantage is obviously in the
reduced quantity of individual components compared to those required for the standard
 In an improved embodiment of the invention the strips are provided with one or
several feet aligned parallel to the electrode, formed from the same monolithic semi-finished
piece as a jointless integral element and then welded to the respective semi-shell of the
electrolytic cell. The strip feet facilitate the welding also enhancing the stiffness of the
monolithic electrode segments and of the cell as a compact assembly.
 In a more preferred embodiment the electrode segment feet are advantageously
shaped as teeth matching the tooth profile of the adjacent electrode segment.
 In a preferred embodiment of the invention the strip feet are bent along the whole
length of the strip so that they all run parallel to the electrode and point in the same direction.
This variant permits any width of the feet attached to the monolithic electrode segments.
 Moreover, the invention also provides shaped pieces to be positioned between the
strips of adjacent electrode segments and on the transition edges between the electrodes
and the strips, in order to fix the membrane and distribute forces. The shaped pieces and the
transition areas of the electrode segments are formed in such a way that they can either be
inserted or engaged. The spacer is ideally shaped so that it comprises one section which is
- located above the membrane and is supported by the electrode and a further section which
is inserted as a spring or a plug into the groove formed by the space between adjacent strips.
 An important advantage of the improved positioning of the spacers with respect to the
standard practice of the prior art was observed in that said spacers were surprisingly brought
to overlap more precisely the respective counter-pieces by means of the electrode segments:
each electrically insulated spacer renders the membrane inactive in the contact area so that
any pair of spacers not precisely overlapping will enlarge the inactive membrane surface
 A further improved embodiment of the invention provides for strips with grooves in
which at least one plate for flow control or for reinforcement of the assembly can be
 The latter option and the relevant advantage for flow control are not available in the
cells of the prior art on the grounds of manufacturing techniques because the degree of
freedom required in that case for the alignment of the strips would have been lost as a result
of such an inserted plate. However, since in the electrolytic cell of the present invention the
strips are fixed and the spacers placed at the transition edges of the electrodes are aligned
thereto, this option can be easily practiced.
 A particularly preferred embodiment provides for a groove for accommodating a plate
angled up to 15° to the electrode. The halogen gas formed during cell operation rises in form
of gas bubbles so that in the upper part of the electrolytic cell a larger volume fraction is
occupied by foam and gas bubbles. An inclined plate establishing a larger open cross-
section in the upper part of the electrode allows optimising the foam discharge from the cell
and the return flow of residual liquor to the lower part of the electrode.
 The invention is hereinafter described by means of the attached drawings which are
provided by way of example and shall not be intended as a limitation of the scope thereof.
 Fig. 1 is a perspective view of two electrode segments in accordance with the present
 Fig. 2 is a perspective view of two electrode segments in accordance with the present
invention provided with spacers.
 Fig. 3 shows a preferred embodiment of two electrode segments in accordance with
the present invention comprising a plate for reinforcement and flow control.
 Fig. 1 illustrates the perspective view of two segments, indicated as A and B, of
electrode 1. The electrode 1 is secured to strips 2 via the transitional area 3 on both sides.
 The strips 2 are provided with feet 4 parallel to the major surface of electrode 1 and
bent towards the external side perpendicularly to strip 2. The strip feet 4 are secured to the
rear side 10 of the cell wall. The feet 4 shown in Fig. 1 are continuous.
 Fig. 2 illustrates a spacer 7 placed in the transitional area 3 between electrode 1 and
strip 2. There is also shown a shaped piece whose upper part 8 is located in the transitional
area 3 and whose lower part 9 is inserted into the gap formed by adjacent strips 2. The feet 4
shown in Fig. 2 are also continuous feet.
 Fig. 3 depicts an embodiment wherein the strip feet 4 are shaped as teeth. The rows
of teeth are inserted in the construction phase below the adjacent strip, so that a supporting
surface as small as possible is formed. The dimensions of the individual teeth are selected
so that a small adjustment space in the inserted state and before welding is provided for a
possible necessary alignment.
 Fig. 3 also shows two electrode segments which in this example have a lamellar
structure. A groove 5 is provided in the strips 2 , in which the plate 6 is inserted. On the one
hand, this plate improves the stability of the electrode segments and on the other hand it
delimits two flow channels establishing respective counter-current flows. During cell
operation there is an upward stream in the space between electrode 1 and plate 6 and a
downward stream in the space between cell rear wall 10 (shown as dashed line) and plate 6.
The flow change takes place in the space at the upper and lower end of the electrolyser. In a
test cell, the flat electrode of the prior art design with an overall anode surface area of 2.7 m2
was replaced by an electrode according to the invention comprising 18 segments, each with
an electrode surface area of 0.15 m2. Such cell was operated at a current density of 3 kA/m2
and 6 kA/m2.
 The use of the electrolysis cell of the invention permitted a reduction of the cell
voltage by 8 mV at a current density of 3 kA/m2 and by approx. 16 mV at a current density of
 The above description shall not be understood as limiting the invention, which may be
practised according to different embodiments without departing from the scopes thereof, and
whose extent is solely defined by the appended claims.
 In the description and claims of the present application, the word "comprise" and its
variations such as "comprising" and "comprised" are not intended to exclude the presence of
other elements or additional components.
1. Electrolytic cell delimited by two semi-shells each fixed to an electrode (1) by
means of a multiplicity of conductive strips (2), the electrodes being an anode
and a cathode having a major surface separated by a membrane, characterised
in that at least one of the electrodes is made of a multiplicity of electrode
segments (A,B), each of said electrode segments being attached to at least one
of said conductive strips prior to the fixing to the respective semi-shell, said
electrode segments and said conductive strips attached thereto being obtained
as jointless integral elements from single semi-finished workpieces, when a
multiplicity of shaped pieces are placed between said strips of adjacent electrode
segments (A,B) and at the transition edges (3) between the said electrodes and
said strips, comprising a first section located above the membrane and a second
section between said strips in the construction state.
2. The cell as claimed in claim 1, wherein each of said electrode segments (A, B) is
attached to two of said conductive strips.
3. The cell as claimed in claim 1 and 2, wherein the conductive strips (2) are
provided with protruding feet (4) parallel to the major surface of said at least one
electrode, said feet being part of said joint less integral elements obtained from
said single semi-finished work piece, said feet being welded to the respective
semi-shell of the electrolyte cell.
4. The cell as claimed in claim 3, wherein said feet are shaped as teeth matching
the opposite tooth profile of an adjacent electrode segment (A,B).
5. The cell as claimed in claim 3 or 4, wherein said feet are bent along the overall
length of the strip (2) so that they are in a position parallel to the major surface of
said at least one electrode and pointing towards the same direction.
6. The cell as claimed in any claim from 1 to 6, wherein the said strips are provided
with a groove (5) in which it is inserted at least one reinforcement plate (6).
7. The cell as claimed in claim 7, wherein the said groove accommodating said
plate is angled up to 15° to the electrode (1).
The invention relates to an electrolytic cell with segmented and monolithic electrode
assembly. The electrolytic cell consists of two semi-shells and encompassing mainly the
inlet and outlet devices, components for the flow control, a membrane as well as anode
and cathode. The electrode (1) may have any surface structure and they are connected
on the side opposite to the membrane to conductive strip (2) connected to the
respective semi-shell. The main feature of the invention is to segment the electrodes (A,
B) and to fabricate each electrode segment (A, B) with its adjacent supporting strips (2)
as a joint less monolith from a single semi-finished work piece.
|Indian Patent Application Number||2689/KOLNP/2007|
|PG Journal Number||07/2011|
|Date of Filing||19-Jul-2007|
|Name of Patentee||UHDENORA S.P.A.|
|Applicant Address||VIA BISTOLFI, 35, 20134 MILAN|
|PCT International Classification Number||C25B 9/08|
|PCT International Application Number||PCT/EP2006/000644|
|PCT International Filing date||2006-01-25|