Electrolytic cell and electrolytic cell having a cell casing made of metal foil

Abstract

The present invention relates to an electrolytic cell comprising a cell casing (2) and a sheet separator (3), wherein an anode chamber (4) and a cathode chamber (5) separated by the sheet separator (3) are defined by the cell casing (2), and the anode chamber (4) and the cathode chamber (5) each comprise an anode (6) and a cathode (7), and the cell casing (2) comprises at least two metal foil sheets (8, 9) each having a peripheral rim region (10, 11), and the metal foil sheets (8, 9) are attached to each other in the rim regions (10, 11) by an electrical insulating adhesive bond (12) between the metal foil sheets (8, 9), and the sheet separator (3) is mounted within the cell by being included in the adhesive bond (12) between the rim regions (10, 11), and a plurality of such electrolytic cells This relates to an electrolytic cell containing cells (1).

Description

Technology Field

[0001] The present invention relates to an electrolytic cell according to the preamble of claim 1 and an electrolytic cell according to the preamble of claim 7. Background Technology

[0002] One type of anode electrolytic cell for large-scale production (i.e., megawatt range) of hydrogen by alkaline water electrolysis and / or chlorine by chlorine-alkali electrolysis is a so-called single-element design.

[0003] In a single-element design electrolytic cell, each electrolytic cell is a separately sealed unit. The casing of each electrolytic cell comprises two half-shells with a separator and a gasket interposed between them, which are bolted together at their rim regions. Thus, each half-shell forms one half-cell of the electrolytic cell, and the half-shells are separated by a separator. The sealing force for sealing the electrolytic cell is provided by a plurality of bolts distributed circumferentially along the rim regions of the cell elements. Depending on the intended purpose of the electrolytic cell, the separator may be an ion exchange membrane or a porous diaphragm. A short circuit between the two half-shells forming the casing of each electrolytic cell must be reliably prevented; for this reason, in addition to the gaskets, at least one layer of electrical insulating material is interposed in the rim regions before sealing. The electrolytic cells are typically suspended from above in a cell rack and pressed against each other using a compression device to form a bipolar stack.

[0004] DE 196 41 125 A1 shows an example of an electrolytic cell of a single-element type bipolar electrolytic cell.

[0005] Known electrolytic cells of a single-element design have the disadvantage that the cell casing requires a significant amount of high-grade metallic material, typically nickel and / or titanium, to provide dimensional stability to the single-element electrolytic cell. The material strength of the cell casing is selected to support the weight of the cell under operating conditions, i.e., when filled with electrolyte. This design results in a significant weight of the cell casing and high material costs. The problem to be solved

[0006] The object of the present invention is to provide a lightweight electrolytic cell with reduced material costs and an electrolytic cell capable of accommodating such cells. means of solving the problem

[0007] This objective is achieved by an electrolytic cell according to the features of claim 1 and an electrolytic cell having the features of claim 7.

[0008] Thus, an electrolytic cell comprising a cell casing and a sheet separator is provided, wherein an anode chamber and a cathode chamber separated by a sheet separator are defined by the cell casing. The anode chamber and the cathode chamber each comprise an anode and a cathode. According to the present invention, the cell casing comprises at least two metal foil sheets, each having a peripheral rim region. The metal foil sheets are attached to each other at the rim regions by an electrically insulating adhesive bond between the metal foil sheets. The sheet separator is mounted within the cell by being included in the adhesive bond between the rim regions. The adhesive bond according to the present disclosure is any bond maintained by an adhesive force between the bonded parts and a bonding material, which provides a connecting element between the bonded parts.

[0009] Advantageously, the electrolytic cell of the present invention combines a new sealing concept for the cell casing by means of an adhesive bond with the use of a metal foil sheet as the main material for the cell casing. As a result, the function of the cell casing is reduced to the purpose of confining the chamber of the electrolytic cell in an electrically conductive manner. The dimensional stability of the cell is no longer provided by the cell casing, but is provided only by the cell rack in which the cell is positioned within the electrolytic cell. The use of metal foil reduces the amount and weight of metal material required for the casing to less than 15% compared to the prior art. In addition, sealing by an adhesive bond reduces the weight of the cell because bolts or frame bars are not required. The new cell design also facilitates the automation of cell assembly.

[0010] In a specific embodiment of the present invention, the adhesive bond may be provided by a chemically cured adhesive or a dried solvent-based adhesive. Chemically cured adhesives and solvent-based adhesives have the advantage of a particularly strong adhesive bond capable of withstanding high temperatures and / or harsh chemicals.

[0011] In another embodiment, the adhesive bond is provided by a thermoplastic material. The thermoplastic material has the advantage of allowing the electrolytic cell to be opened and resealed in an easy and non-destructive manner. For maintenance purposes, for example, as a replacement of the separator, the rim area can be reheated until the thermoplastic material is in a thermoplastic state again, and the cell element can be separated. Thermoplastic materials comprising polypropylene (PP), particularly atactic polypropylene (PP-R), and / or polyvinyl chloride (PVC) are particularly preferred for sealing the electrolytic cells.

[0012] Preferably, the metal foil sheet has a thickness of 0.2 mm or less. A particularly thin metal foil is preferred as a cell casing to not only reduce the total amount of material required but also to improve the flexibility of the cell casing, which is advantageous for establishing extensive planar electrical connections between adjacent cells when multiple cells are compressed in a cell stack.

[0013] The electrolytic cell can preferably be rectangular, square, hexagonal, or round in shape.

[0014] In particular, the present invention relates to an industrial-scale electrolytic cell used for alkaline water electrolysis or chlorine-alkali electrolysis. Accordingly, the separator of the electrolytic cell according to the present invention preferably has an area of ​​0.5 m² to 4 m². In addition, the electrolytic cell is preferably configured for a current density of at least 3 kA / m².

[0015] In an embodiment of the present invention, the cell casing is coated with an electrical insulating layer on the outer side of the rim region. The electrical insulating layer on the rim region of the cell casing is particularly desirable for reducing stray current within the cell to be operated in a tank filled with barrier liquid. Even if the barrier liquid is selected to have high electrical resistance, stray current at the junction of the rim regions cannot be eliminated, particularly if any contamination of the barrier liquid with electrolyte from within the cells occurs. In this setting, the electrical insulating coating on the outer side of the rim regions will be advantageous for reducing stray current.

[0016] The objective is further achieved by an electrolytic cell comprising a cell rack and a cell stack. The cell stack comprises a plurality of electrolytic cells stacked in the axial direction. The cell rack includes a compression device that compresses the electrolytic cells of the cell stack in the axial direction to maintain the electrical connection of the electrolytic cells in series. The cell stack is mounted within the cell rack in a state where the axial direction is extended horizontally. According to the present invention, the electrolytic cells within the cell stack are configured as described above.

[0017] Preferably, the cell rack provides at least one internal interface for the cell stack, and this interface provides dimensional stability to the cell stack by supporting the electrolytic cells at least laterally and downward. The metal foils used for the cell casing are typically robust enough to be handled when the cell is empty, but they do not provide sufficient dimensional stability on their own when filled with liquid electrolyte, i.e., during operation. Therefore, this function is preferably transferred to the cell rack. The internal interface of the cell rack, which supports the electrolytic cells at least laterally and downward, achieves pressure balance between the outside and inside of the metal foil, so that the interface dissipates the gravitational force of the electrolyte and / or any additional pressure applied to the electrolyte. The internal interface can dissipate these forces by contacting the outer surface of the cell casing directly, or indirectly by an intermediate medium filling the space between the outer surface of the cell casing and the internal interface of the cell rack.

[0018] In a preferred embodiment, the cell rack comprises a tank having tank walls, the cell stack is located within the tank, the tank walls form at least one internal interface for the cell stack, and the tank is filled with an electrically nonconductive barrier liquid that transfers the dimensional stability of the cell rack to the cell stack submerged in the barrier liquid. The barrier liquid within the tank can provide a pressure balance between the liquid electrolyte within the cell and the outside, thereby relieving stress occurring within the material of the metal foil sheet. In particular, to achieve a similar height distribution of pressure due to gravity, it is preferable that the barrier liquid have a density within the range of + / - 40% of the density of the liquid electrolyte.

[0019] Preferably, the tank is a pressure vessel with a round cross-section. Then, the setup allows for electrolysis at elevated or even high pressures. The pressure vessel forms an external protective cover of a simple geometric structure, and in this case, it is relatively easy to comply with pressure vessel regulations, while the individual cells contained in the vessel do not need to be designed according to these regulations.

[0020] In addition, it is desirable for the electrolytic cell to include a conductivity sensor for monitoring the electrical conductivity of the barrier liquid. Under normal operation, the conductivity of the barrier liquid must be below a specific threshold. Conductivity rising above this threshold indicates a failure, particularly leakage from one of the cells, because electrolyte leaking from the cell will increase the conductivity of the barrier liquid.

[0021] In a preferred embodiment, the barrier liquid includes an indicator liquid to indicate leakage of electrolyte from the cell stack by a color change. Alternatively or additionally, the pH value of the barrier liquid can be monitored by a pH sensor.

[0022] In a further preferred embodiment, the tank is connected to a circulation loop of the barrier liquid, and the circulation loop includes a heat exchanger for heating and / or cooling the barrier liquid. Generally, the electrolysis process generates waste heat. This waste heat can be discharged at least partially by cooling the barrier liquid through the heat exchanger. During startup, it may be desirable to heat the barrier liquid to rapidly reach a desired operating temperature.

[0023] Advantageously, a pressure sensor is provided to monitor the pressure within the tank, and the pressure sensor is connected to a control unit configured to control the pressure of the barrier liquid by regulating the pressure applied to the tank from an external pressure source. In particular, pressure control can be used to adjust the pressure of the barrier within the tank to the pressure of the electrolyte within the cells, that is, to maintain the differential pressure between the inside and outside of the cells below a specific threshold. The pressure from the external source can be applied by a gaseous auxiliary medium. In particular, an auxiliary medium that is inert to the product of electrolysis is preferred. In the case of chlorine-alkali or alkaline water electrolysis, nitrogen, for example, is a preferred auxiliary medium.

[0024] In another preferred embodiment, the tank is completely filled with barrier liquid and sealed for autogenous pressure control of the barrier liquid. Thus, there is essentially no gaseous phase inside the tank outside the electrolytic cell. Due to the flexibility of the cell casing, the pressure of the barrier liquid will automatically follow the pressure of the electrolyte inside the cell, and the cell casing will deform to maintain pressure balance.

[0025] Additional advantages of the present invention are described below in relation to the embodiments illustrated in the accompanying drawings. Brief explanation of the drawing

[0026] FIG. 1 schematically illustrates three electrolytic cells according to the present invention. FIG. 2 schematically illustrates a first embodiment of an electrolytic cell according to the present invention, wherein electrolytic cells are stacked and supported from the side and from below by the boundary surface of a cell rack. FIG. 3 schematically illustrates a second embodiment of an electrolytic cell according to the present invention, wherein a stack of electrolytic cells is mounted in a tank filled with a barrier liquid having external pressure control. FIG. 4 schematically illustrates a third embodiment of an electrolytic cell according to the present invention, wherein a stack of electrolytic cells is mounted within a closed tank filled with a barrier liquid having autogeneous pressure control. FIGS. 5a to 5c schematically illustrate three different cell configurations of electrolytic cells mounted inside a tank with a round cross-section. Specific details for implementing the invention

[0027] Identical parts in a drawing are consistently identified by the same reference numeral, so they are generally described and referred to only once.

[0028] FIG. 1 illustrates three electrolytic cells (1) according to the present invention, with one stacked on top of the other. Each electrolytic cell (1) includes a cell casing (2) and a sheet separator (3). An anode chamber (4) and a cathode chamber (5) are defined by the cell casing (2) and separated from each other by the sheet separator (3). The anode chamber (4) and the cathode chamber (5) each include an anode (6) and a cathode (7).

[0029] The cell casing (2) comprises at least two metal foil sheets (8, 9), each having a peripheral rim area (10, 11). The metal foil sheets (8, 9) are attached to each other in the rim areas (10, 11) by an electrically insulating adhesive bond (12) between the metal foil sheets (8, 9). A sheet separator (3) is mounted in the cell by being included in the adhesive bond (12) between the rim areas (10, 11).

[0030] Preferably, the metal foil sheet (8, 9) has a thickness of 0.1 mm or less.

[0031] The anode (6) and cathode (7) are preferably provided by a mesh of wires, particularly a woven mesh. Compared to a mesh made of expanded metal, the wires have the advantage of not having sharp edges that could damage the metal foil (8, 9).

[0032] The adhesive bond (12) can be provided by a chemically cured adhesive or a dried solvent-based adhesive. Alternatively, the adhesive bond (12) can be provided by a thermoplastic material.

[0033] When stacked together and compressed axially, the electrolytic cells (1) formed by the flexible cell casings (2) of the metal foils (8, 9) form an extended contact surface between the anode chamber (4) and the cathode chamber (5) of the adjacent cell (1). Preferably, there will be a pressure balance at the contact surface between the pressure (p1) inside the anode chamber (4) and the pressure (p2) inside the cathode chamber (5). Furthermore, there is a pressure balance between the internal pressure (p1, p2) and the external pressure (p0) of the cell (1). Preferably, the pressures p1, p2, and p0 are adjusted to be equal to a relative difference of 10% to reduce material stress within the metal foil sheets (8, 9). Preferably, the pressure difference between the pressures p1, p2, and p0 does not exceed 0.5 bar (g).

[0034] As illustrated in FIG. 1, the cell casing (2) is coated with an electrical insulation layer (13) on the outer side of the rim area (10, 11) in a preferred embodiment. The insulation layer (13), located on the outer side of the metal foil (8, 9) in the rim area, particularly in the non-contact area of ​​adjacent cells (1), helps to prevent stray current in the case of a barrier liquid that is an incomplete insulating liquid or becomes an incomplete insulating liquid (e.g., due to slight leakage during operation). Of course, due to the requirement that a contact surface exists between adjacent cells (1), there will always be imperfections at the ends of the insulation layer (13) where stray current may cause damage. However, the insulation layer (13) generally reduces stray current by reducing the cross-section through which stray current flows.

[0035] In FIG. 2, an electrolytic cell (100) comprising a cell rack (110) and a cell stack (120) is illustrated. The cell stack (120) comprises a plurality of electrolytic cells (1) according to the present invention stacked in an axial direction (A). The cell rack (110) comprises a compression device (111) that compresses the electrolytic cells (1) of the cell stack (120) in an axial direction (A) to maintain the electrical connection of the cells (1) in series. The cell stack (120) is mounted on the cell rack (110) with the axial direction (A) extended horizontally.

[0036] Different possibilities exist for installing cells (1) in a cell stack (120): for example, the cells (1) can be suspended individually from the upper frame (not shown) of the cell rack (110). Alternatively, the cells (1) can be stacked one on top of the other while the cell rack is in an upright position with an axial direction (A) that extends vertically. Once all the cells (1) of the stack (120) are stacked in advance and a compressive force is applied to the stack (120), the entire stack (120) is positioned in an operational state, i.e., with the axial direction (A) extended horizontally.

[0037] The cell rack (110) illustrated in FIG. 2 provides an internal boundary surface (112) for a cell stack (120), and this boundary surface (112) provides dimensional stability to the cell stack (120) by supporting the electrolytic cells (1) at least laterally and downward.

[0038] For the operation of the electrolytic cell (100), power (170, 171) is connected to the outermost cell casings (2) of the stack (120). Additionally, the anode chamber (4) and cathode chamber (5) of the cell are connected to an inlet header (172) and an outlet header (173) for the supply and discharge of the electrolyte as well as the discharge of the electrolysis products. The inlet header (172) and the outlet header (173) preferably extend within the tank (113) to minimize the number of openings within the tank (113). However, in principle, headers outside the tank may also be used. For connection to the inlet header (172) and the outlet header (173), fittings of a harder material are heat-welded to the openings within the metal foil sheets (8, 9). These fittings are connected to the headers, for example, by threaded connections, hose-nozzle connections, or gasket connections.

[0039] In FIG. 3, a second embodiment of an electrolytic cell (100) according to the present invention is illustrated, wherein a cell rack (110) comprises a tank (113) having a tank wall (114), and a cell stack (120) is located within the tank (113). The tank wall (114) forms an internal boundary surface (112) for the cell stack (120). The tank (113) is filled with an electrically non-conductive barrier liquid (130) that provides dimensional stability of the cell rack (110) to the cell stack (120) submerged in the barrier liquid (130). In particular, the tank (113) may be a pressure vessel having a round cross-section. For example, demineralized water may be used as the barrier liquid (130).

[0040] The tank (113) is originally composed of at least two parts that are joined after the cell rack (120) is installed inside the tank (113). In the example shown in FIG. 3, the tank (113) is divided axially (A) into three parts, namely a central part and two leads, which are joined together at two flanges (115) by bolting. For installation, it is preferable that the electrolytic cell (1) be mounted on the frame (not shown) of the cell rack (120) in an axially movable manner. Then, the frame is inserted into the open tank (113) from one side. Finally, the tank is closed by bolting the flanges (115).

[0041] The compression device (111) may be located entirely within the tank (113) as shown in FIG. 3. In this case, rigidity of the tank (113) is more easily achieved, which is particularly advantageous when the tank (113) is designed as a pressure vessel. Alternatively, the compression device (111) may be partially extended outside the tank (113), for example, having an actuation rod that extends outward.

[0042] The tank (113) is connected to a circulation loop (150) of barrier liquid (130), and the circulation loop (150) includes a heat exchanger (151) for heating and / or cooling the barrier liquid (130). The circulation loop (150) further includes a pump (152) for circulating the barrier liquid (130).

[0043] For pressure control of the barrier liquid (130), a pressure sensor (160) is provided to monitor the pressure within the tank (113). The pressure sensor (160) is connected to a control unit (161) configured to control the pressure of the barrier liquid (130) by adjusting the pressure applied to the tank from an external pressure source (162). The external pressure source (162) may provide an inert gas, such as nitrogen, to the tank (113). Preferably, the pressure (p0) of the barrier liquid (130) is controlled to be equal to the pressures (p1, p2) within the anode chamber (4) and cathode chamber (5) up to a relative pressure difference of up to 10%.

[0044] The pressure sensor (160) can also be used to monitor the pressure of the barrier liquid (130) to detect events such as sudden pressure events (e.g., caused by a small ignition). Monitoring of the barrier liquid (130) by the pressure sensor (160) is more sensitive than monitoring the pressure within the outlet header (173), for example, because the barrier liquid (130) is substantially incompressible compared to the gas portion within the outlet header (173).

[0045] The electrolytic cell (100) may further include a conductivity sensor (140) for monitoring the electrical conductivity of the barrier liquid (130).

[0046] Additionally, the barrier liquid (130) includes an indicator liquid to indicate leakage of the electrolyte from the cell stack (120) by a color change. This color change can be recognized, for example, through an inspection window (116) or by using at least partially transparent ducts within the circulation loop (150).

[0047] Accordingly, in all other respects, the description of the first embodiment shown in FIG. 2 can be applied to the second embodiment shown in FIG. 3.

[0048] FIG. 4 illustrates a third embodiment of an electrolytic cell (100) according to the present invention. The third embodiment differs from the second embodiment in that the tank (113) is completely filled with barrier liquid (130) and sealed to control the self-generating pressure of the barrier liquid (130). Thus, the tank (113) does not contain a gaseous phase outside the cell stack (120) and is not connected to a barrier liquid circulation loop. In this case, due to the incompressibility of the liquid compared to the gas, the pressure of the barrier liquid (130) will follow the pressure of the medium inside the electrolytic cell (1), thereby maintaining pressure balance in the cell case (2).

[0049] For example, the tank of FIG. 4 is divided longitudinally and bolted together at a horizontal flange (115). It may also be possible to join the tank pieces by welding, but; maintenance of the cell stack (120) will be compromised.

[0050] Accordingly, in all other respects, the description of the first and second embodiments illustrated in FIG. 2 and FIG. 3 may be applied to the third embodiment illustrated in FIG. 4. In particular, the electrolytic cell of FIG. 4 will have an inlet header and an outlet header similar to those in FIG. 3, which are not illustrated in FIG. 4 for simplification.

[0051] FIGS. 5a through 5c illustrate other possible geometric structures of an electrolytic cell (1) within a tank (113) of the second and third embodiments illustrated in FIGS. 3 and 4. Generally, due to the use of a barrier liquid (130) to mediate the dimensional stabilization effect of the tank wall (114) relative to the cell casing (2), the cross-section of the cell (1) can be selected independently of the cross-section of the tank. Within a tank (113) with a round cross-section, an electrolytic cell (1) of a rectangular or quadratic shape (Fig. 5a), a hexagonal shape (Fig. 5b), or a circular shape (Fig. 5c) is particularly preferred. Explanation of the symbols

[0052] 1 electrolytic cell 2-cell casing 3 Sheet-type Separator 4 anode chambers 5 cathode chambers 6 anodes 7 cathodes 8, 9 Metal foil sheet 10, 11 Rim area 12 adhesive bonds 13 electrical insulation layer 100 electrolyzers 110 cell racks 111 compression device 112 boundary surface 113 tank 114 tank wall 115 flange 116 Inspection Window 120 cell stack 130 barrier liquid 140 conductivity sensor 150 loop 151 heat exchanger 152 pump 160 pressure sensors 161 Control Unit 162 External pressure source 170, 171 Power 172 Entrance Header 173 Exit Header A-axis direction

Claims

Claim 1 An electrolytic cell comprising a cell rack (110) and a cell stack (120), wherein the cell stack (120) comprises a plurality of electrolytic cells (1) stacked in an axial direction (A), and the cell rack (110) comprises a compression device (111) for compressing the electrolytic cells (1) of the cell stack (120) in the axial direction (A) to maintain the electrical connection of the electrolytic cells (1) in series, and the cell stack (120) is mounted within the cell rack (110) in a state in which the axial direction (A) is extended horizontally, and each of the electrolytic cells (1) comprises a cell casing (2) and a sheet-type separator (3), wherein an anode chamber (4) and a cathode chamber (5) separated by the sheet-type separator (3) are defined by the cell casing (2), and the anode chamber (4) and the cathode chamber (5) are each An electrolytic cell comprising an anode (6) and a cathode (7), wherein the cell casing (2) comprises at least two metal foil sheets (8, 9) each having a peripheral rim area (10, 11), the metal foil sheets (8, 9) are attached to each other in the rim areas (10, 11) by an electrical insulating adhesive bond (12) between the metal foil sheets (8, 9), the sheet separator (3) is mounted in the cell by being included in the adhesive bond (12) between the rim areas (10, 11), the cell rack (110) provides at least one internal boundary surface (112) for the cell stack (120), and the boundary surface (112) provides dimensional stability to the cell stack (120) by supporting the electrolytic cells (1) at least laterally and downward. Claim 2 The electrolytic cell according to claim 1, characterized in that the adhesive bond (12) is provided by a chemically cured adhesive or a dried solvent-based adhesive. Claim 3 The electrolytic cell according to claim 1, characterized in that the adhesive bond (12) is provided by a thermoplastic material. Claim 4 The electrolytic cell according to claim 1, characterized in that the metal foil sheet (8, 9) has a thickness of 0.2 mm or less. Claim 5 An electrolytic cell according to claim 1, characterized in that the cross-sectional shape perpendicular to the axial direction (A) of the electrolytic cells (1) is rectangular, square, hexagonal, or circular. Claim 6 An electrolytic cell according to any one of claims 1 to 5, wherein the cell casing (2) is coated with an electrical insulation layer (13) on the outside in the rim regions (10, 11). Claim 7 delete Claim 8 delete Claim 9 An electrolytic cell according to claim 1, wherein the cell rack (110) comprises a tank (113) having a tank wall (114), the cell stack (120) is located within the tank (113), the tank wall (114) forms at least one internal boundary surface (112) for the cell stack (120), and the tank (113) is filled with an electrically nonconductive barrier liquid (130). Claim 10 In claim 9, the electrolytic cell is characterized in that the tank (113) is a pressure vessel having a round cross-section. Claim 11 In claim 9, the electrolytic cell is characterized by further including a conductivity sensor (140) for monitoring the electrical conductivity of the barrier liquid (130). Claim 12 In claim 9, the electrolytic cell is characterized in that the barrier liquid (130) includes an indicator liquid for indicating leakage of electrolyte from the cell stack (120) by a color change. Claim 13 An electrolytic cell according to claim 9, wherein the tank (113) is connected to a circulation loop (150) of the barrier liquid (130), and the circulation loop (150) comprises a heat exchanger (151) for heating and / or cooling the barrier liquid (130). Claim 14 An electrolytic cell according to claim 9, wherein a pressure sensor (160) is provided to monitor the pressure within the tank (113), and the pressure sensor (160) is connected to a control unit (161) configured to control the pressure of the barrier liquid (130) by adjusting the pressure applied to the tank from an external pressure source (162). Claim 15 In claim 9, the electrolytic cell is characterized in that the tank (113) is completely filled with the barrier liquid (130) and does not contain a gaseous phase outside the cell stack (120).

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