CN117203373A

CN117203373A - Controlling electrode current density of electrolytic cells

Info

Publication number: CN117203373A
Application number: CN202180079616.0A
Authority: CN
Inventors: L·迪阿斯托尔福; L·米克尔森; Y·阮
Original assignee: Alcoa USA Corp
Current assignee: Alcoa USA Corp
Priority date: 2020-11-27
Filing date: 2021-11-25
Publication date: 2023-12-08
Also published as: DK202370308A1; ZA202305469B; CA3197052A1; AU2021388087A1; EP4251790A1; US20240003031A1; WO2022109742A1

Abstract

An apparatus and method for controlling the electrode current density of an electrolytic cell during electrolytic production of metals such as aluminum are disclosed. The cell has anode and cathode plates vertically aligned and alternately arranged in rows. Each electrode defines a connection region for connecting the electrode to the electrolytic cell, a middle region, and an ACO (anode-cathode overlap) region extending from the middle region for overlapping adjacent electrodes. The ratio of the surface area of the ACO region to the surface area of the intermediate region is greater than 1. Alternatively, the average cross-sectional ACO area of the intermediate and connecting areas is greater than 1, preferably greater than 2. The present technique allows for maximizing the current density in the ACO region. Increasing these ratios has less environmental impact because of reduced heat generation and energy consumption, making metal production environmentally friendly, especially when used with inert or oxygen evolving electrodes.

Description

Controlling electrode current density of electrolytic cells

Cross Reference to Related Applications

The present patent application claims priority from U.S. provisional patent application No. 63/118,774 entitled "apparatus and method for controlling electrode current density of an electrolytic cell" filed by the united states patent and trademark office at 11/27 of 2020, the contents of which are incorporated herein by reference.

Technical Field

The present application relates generally to an apparatus and method for the electrolytic production of metals. In particular, the apparatus and method are suitable for producing metals, such as aluminum, using vertical electrodes and cathode plates of inert or oxygen evolving anodes.

Background

An electrolytic cell for producing aluminum or other metals includes flat inert anodes and wettable inert cathodes alternately arranged in rows, immersed in a molten salt bath having sufficient ionic conductivity to pass an electric current. The molten salt bath has the ability to dissolve metal compounds (e.g., metal oxides, chlorides, carbonates, etc.) to be reduced. Gases such as oxygen, chlorine or carbon dioxide are produced at the anode and leave the cell as exhaust gas. Liquid metal is produced on the cathode plate and flows in the form of a film to a pool or sump for collection under gravity. The anode and cathode plates are separated by a distance called anode-cathode distance (ACD) and have an overlap dimension called anode-cathode overlap (ACO).

The cathode is an electrically conductive cathode plate, is chemically resistant to metals and electrolytes, and has good wettability to the resulting metal. The optimum shape and size of the cathode plate is related to the desired cell resistance, current density, anode size and cell size.

The width of each electrode plate can be simply reduced to increase the current density everywhere. However, simply reducing the area of the electrode plates in all areas comes at the cost of increasing cell resistance and specific energy consumption. This increases the heat generation, making it more difficult or impossible to design an electrolytic cell with an appropriate heat balance.

Accordingly, there is a need for a new configuration or design of an electrolytic cell and method thereof for manufacturing metals such as aluminum by increasing the current density of the electrodes.

Disclosure of Invention

The disadvantages of the prior art are generally alleviated by a new apparatus and method for increasing the current density of an electrode during electrolytic production of metals such as aluminum.

Thus, according to a first aspect, there is disclosed an electrode plate for the electrolytic production of metal using an electrolytic cell comprising a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows of said anode and cathode plates. Electrode plate definition: a connection region adjacent the first end of the electrode plate for connecting the electrode plate to the electrolytic cell; an intermediate region extending from the connection region without overlapping with the adjacent electrode plate; and an anode-cathode overlap (ACO) region extending from the intermediate region to a second end of the electrode plate opposite the first end and configured to overlap an adjacent electrode plate; wherein the electrode plate comprises two opposite surfaces for facing the surfaces of the electrode plates of adjacent rows; and wherein the ratio of the surface area of the ACO region to the surface area of the intermediate region is greater than 1 in order to maximize the current density in the ACO region. Preferably, the ACO/intermediate surface area ratio is equal to or greater than 2.

According to a preferred embodiment of the first aspect described above, the electrode plate has a rectangular shape, wherein the width of the electrode plate is constant from the ACO region to the intermediate region and the connection region.

According to a second aspect, an electrode plate for the electrolytic production of metal using an electrolytic cell is disclosed, the cell comprising a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows of said anode and cathode plates, the electrode plates defining: a connection region adjacent the first end of the electrode plate for connecting the electrode plate to the electrolytic cell; an intermediate region extending from the connection region without overlapping with the adjacent electrode; and an ACO region extending from the intermediate region and configured to overlap an adjacent electrode; wherein the average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1 so as to maximize the current density in the ACO region while maintaining the mechanical strength of the connecting region for supporting the electrode plate. Preferably, the average ACO/intermediate cross-sectional area ratio is equal to or greater than 2.

The following preferred embodiments apply to the first and second aspects disclosed above, unless otherwise indicated.

According to a preferred embodiment, the electrode plate has a gatepost shape, wherein the intermediate region and the connecting region each define a pair of legs on either side thereof, a central gap between the legs being located below the ACO region.

According to a preferred embodiment, the electrode plates are paddle-shaped, wherein the ACO region has a first width, the intermediate region and the connecting region have a second width, the second width being smaller than the first width.

According to a preferred embodiment, the electrode plate has a trapezoidal shape, wherein the width of the electrode plate decreases continuously from the second end to the first end of the electrode plate.

According to a preferred embodiment, the ACO region and the intermediate region of the electrode plate have a trapezoidal shape, the width of the electrode plate decreasing from the second end of the electrode plate to the junction between the intermediate region and the connection region, the connection region having a rectangular shape.

According to a preferred embodiment of the first aspect described above, the peripheral edge of the surface has a rounded transition between the first end of the plate and the connection area and/or the peripheral edge has a rounded transition between the second end and the ACO area.

According to a preferred embodiment of the above second aspect, the electrode plate comprises two opposing surfaces for facing the surfaces of the electrode plates of the adjacent rows, the peripheral edge of the surfaces having a rounded transition between the first end of the plate and the connection region and/or the peripheral edge having a rounded transition between the second end of the ACO region.

According to a preferred embodiment, the metal to be produced is aluminum and the electrode plates are wettable by liquid aluminum metal.

According to a preferred embodiment, the electrode plate is a cathode plate.

According to a third aspect, an electrolytic cell for the electrolytic production of metal is disclosed, comprising one or more electrode plates as disclosed herein. Preferably, the metal is aluminum.

According to a third aspect, the use of an electrode plate as disclosed herein or an electrolytic cell as disclosed herein for manufacturing an electrolytic cell comprising a plurality of electrode plates is disclosed.

According to a fourth aspect, the use of an electrode plate as disclosed herein or an electrolytic cell as disclosed herein for the electrolytic production of aluminium is disclosed.

According to a fifth aspect, a method for controlling current density of a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in an electrolytic cell is disclosed, the electrode plates defining: a connection region for connecting the electrode plate to the electrolytic cell; an intermediate region extending from the connection region without overlapping with the adjacent electrode; and an ACO region extending from the intermediate region and configured to overlap an adjacent electrode; wherein each electrode plate includes a surface facing another electrode plate of an adjacent row; the method comprises the following steps: the current density in the ACO region is maximized by varying the ratio of the surface area of the ACO region to the surface area of the intermediate region, e.g., the ACO/intermediate surface area ratio is greater than 1.

According to a sixth aspect, a method is disclosed for controlling current density of a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in an electrolytic cell, the electrode plates defining: a connection region for connecting the electrode plate to the electrolytic cell; an intermediate region extending from the connection region without overlapping with the adjacent electrode; and an ACO region extending from the intermediate region and configured to overlap an adjacent electrode; the method comprises the following steps: an electrode plate is provided in which the average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1 in order to maximize the current density in the ACO region while maintaining the mechanical strength of the connecting region for supporting the electrode plate.

According to a seventh aspect, a method for maximizing the current density of an electrolytic cell is disclosed, the electrolytic cell comprising a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in the electrolytic cell, the method comprising the steps of: each existing electrode plate of the cell is replaced with an electrode plate disclosed herein.

The electrode plates disclosed herein, in particular the cathode plates, allow:

increasing the ratio of the surface area of the ACO region to the surface area of the intermediate region by reducing the surface area or average cross-sectional area of the lower current density region below or above the ACO region, thereby producing less impact on heat generation and energy consumption; and/or

The average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1, preferably greater than 2, in order to maximize the current density in the ACO region while maintaining the mechanical strength of the connecting region for supporting the electrode plates in the electrolytic cell.

Furthermore, electrode plates, and in particular cathode plates, as disclosed herein may be used to make new electrolytic cells, as well as to replace electrodes of existing electrolytic cells, in order to reduce energy (e.g., electricity) consumption, thereby providing an environmentally friendly process for metal production, and in particular aluminum production, more preferably when the cathode plates disclosed herein are used in combination with inert oxygen evolving anodes.

Drawings

The above and other aspects, features and advantages of the present application will become more apparent from the following description with reference to the accompanying drawings in which:

FIG. 1A is a partial schematic cross-sectional view of an electrolytic cell known in the art;

FIG. 1B is a side view of a portion of an interleaved anode and cathode module as known in the art;

fig. 2A is a schematic diagram of an electrode plate according to a first embodiment of the present disclosure;

fig. 2B is a schematic view of an electrode plate according to a second embodiment of the present disclosure;

fig. 2C is a schematic view of an electrode plate according to a third embodiment of the present disclosure;

fig. 2D is a schematic diagram of an electrode plate according to a fourth embodiment of the present disclosure;

fig. 3 is a front view of an electrode plate according to a fifth embodiment of the present disclosure;

FIG. 4 illustrates a method for controlling current density of a plurality of electrode plates according to a preferred embodiment of the present disclosure;

FIG. 5 illustrates a method for controlling current density of a plurality of electrode plates according to another preferred embodiment of the present disclosure; and

fig. 6 illustrates a method for maximizing current density of an electrolytic cell including a plurality of electrode plates according to a preferred embodiment of the present disclosure.

Detailed Description

The novel apparatus and method will be described below. While the present application has been described in terms of specific illustrative embodiments, it should be understood that the embodiments described herein are illustrative only and that the scope of the application is not limited thereto.

The terminology used herein is consistent with the definitions given below.

By "about" is meant that the value of weight percent (wt.%) time, voltage, resistance, volume, or temperature may vary within a range depending on the error magnitude of the method or apparatus used to evaluate such weight percent time, voltage, resistance, volume, or temperature. An error magnitude of 10% is generally acceptable.

The following description and the embodiments described therein are provided by way of illustration of specific embodiments of the principles and aspects of the present application. These examples are provided to illustrate, but not to limit, those principles of the application. In the description that follows, like parts and/or steps are marked throughout the specification and drawings with the same reference numerals.

As described above, the application disclosed herein relates to a new configuration of an electrolytic cell (particularly an electrode plate) for increasing current density.

In a vertical inert anode cell, the cathode and anode plates are arranged in parallel alternating rows as shown in fig. 1A and 1B of U.S. patent No. 10,415,147 (LIU Xinghua), the contents of which are incorporated herein by reference.

Fig. 1A shows a schematic cross section of an electrolytic cell 10 that uses electrochemical reduction of an anode and a cathode to produce a metal (e.g., aluminum) by an electrolyte (e.g., alumina dissolved in molten cryolite). The electrolytic cell 10 has at least one anode module 12 comprising a plurality of vertically oriented anodes 12E suspended above at least one cathode module 14 having a plurality of vertically oriented cathodes 14E in an electrolytic cell reservoir 16. The vertical cathode 14E extends upward toward the anode module 12. Although a particular number of multiple anodes 12E and cathodes 14E are shown in FIGS. 1A and 1B, any number of anodes 12E and cathodes 14E greater than or equal to 1 may be used to define an anode module 12 or a cathode module 14, respectively. In some embodiments, the cathode module 14 is fixedly coupled to the bottom of the electrolytic cell 10, the cathode 14E is supported in a cathode support 14B that is located on a cathode block 18, e.g., made of carbonaceous material, in the electrolytic cell reservoir 16, which is electrically connected to one or more cathode collector bars 20. The cathode block 18 may be fixedly coupled to the bottom of the electrolytic cell 10. The tank 16 may have a steel shell 16S lined with an insulating material 16A, a refractory material 16B, and a sidewall material 16C. The reservoir 16 is capable of holding therein a molten electrolytic bath (shown by dashed line 22) and a molten aluminum metal pad. The portion of anode bus bar 24 that provides current to anode module 12 is shown pressed in electrical contact with anode rod 12L of anode module 12. The anode rod 12L is structurally and electrically connected to an anode distribution plate 12S to which a heat insulating layer 12B is attached. The anode 12E extends through the insulating layer 12B and mechanically and electrically contacts the anode distribution plate 12S. The anode bus 24 conducts direct current from a suitable power source 26 through the anode rod 12L, anode distribution plate 12S, anode elements, electrolyte bath 22 to the cathode 14E and from there through the cathode support 14B, cathode block 18 and cathode collector bar 20 to the other pole of the power source 26. The anode 12E of each anode module 12 is electrically connected. Similarly, the cathode 14E of each cathode module 14 is electrically connected.

Fig. 1B shows an anode module 12 and a cathode module 14, with electrodes 12E and 14E in a staggered relationship. The height of bath 22 relative to cathode 14 may be referred to as the "bath-to-cathode distance" or BCD. The anode module 12 may be raised and lowered in height (i.e., selectively positionable) relative to the position of the cathode module 14, as indicated by double-ended arrow V. In some embodiments, during metal production, anode 12E is not completely immersed in the bath, but extends through bath-steam interface 22. This vertical adjustability allows for adjustment of the "overlap" Y of anode 12E and cathode 14E. The level of the electrolyte bath 22, the height of the anode 12E and cathode 14E may require adjustment of the position of the anode module 12 relative to the cathode module 14 in the vertical direction to achieve a selected anode-cathode overlap (ACO) Y and depth of immersion in the electrolyte 22. In some embodiments, as shown in fig. 1B, anode electrode 12E is at least partially immersed in the electrolyte and cathode electrode 14E is fully immersed in the electrolyte. Changing ACO Y can be used to change cell resistance and maintain a stable cell temperature.

Due to O in the molten electrolyte ₂ The buoyancy of the bubbles, the opposing vertically oriented electrodes 12E, 14E allow a gas phase (O) to be generated thereabout ₂ ) Separated from anode 12E and physically separated from anode 12E. Since the bubbles freely escape from the surface of the anode 12, no electric insulating/resistive layer is formed by accumulation on the anode surface, thus accumulating potential, resulting in high resistance and high power consumption. The anodes 12E may be arranged in rows or columns with or without edge-to-edge gaps or spaces between them to create channels that enhance movement of the molten electrolyte, thereby improving mass transfer and allowing dissolved alumina to reach the surface of the anode module 12. The number of rows of anodes 12E may vary from 1 to any selected number, and the number of anodes 12E in a row may vary from 1 to any number. The cathodes 14E may be similarly arranged in rows with or without edge-to-edge gaps (spaces) between them, and the number of rows and the number of cathodes 14E in a row may be similarly varied from 1 to any number.

The shape of the vertical anode and cathode shown in fig. 1A and 1B is generally plate-shaped. Most commonly, these plates are thin, rectangular in shape. More complex shapes (including sharp angles and rapidly changing cross sections) may be the location of crack initiation, particularly during thermal cycling.

New electrode shapes were then developed and described below with reference to fig. 2A-D and 3.

As shown by the double arrow on the left side of fig. 2A, the electrode plates 100, 200, 300, 400 may define three regions:

an ACO (anode-cathode overlap) region 110 (labeled "Y" in fig. 1B) configured to be located opposite the anode and cathode materials, wherein the current density on the cathode plate is high or maximum for positive production of aluminum;

an intermediate region 120 not opposite the anode or cathode material, wherein the surface current density at the electrode is low. When the electrode plate is the cathode, the middle region is also referred to as an AMD (anode-to-metal distance) region, and as previously described, when the electrode plate is the anode, it is referred to as a BCD (bath-to-cathode distance) region; and

a connection region 130 extending from the intermediate region 120 for connecting the electrode plate 100 to the electrolytic cell. When the electrode plate 100 is a cathode plate extending from the cell bottom 14B

(fig. 1B), which is typically located in the metal pad 30 (see fig. 1B), where the surface current density of the actively generated aluminum is zero, and which is also referred to as the "metal pad area" 30.

Due to the use of inert or oxygen evolving anodes, the voltage loss is about 1 volt and the energy loss is about 3kWh/kg compared to conventional techniques. This is because the inert anode generates oxygen (O) ₂ ) Rather than carbon dioxide gas (CO) generated by a carbon anode ₂ ). These losses can be compensated for by reducing the current density (anode current density and cathode current density).

This reduction in current density is achieved by developing proprietary anode and cathode plate materials that are dimensionally stable. The cathode plate is preferably wettable by liquid aluminium metal. These proprietary materials are then arranged in the vertical configuration disclosed herein, which allows the same current per square foot of building space to be maintained at the active surface at a lower current density.

Minimizing the intermediate zone 120 results in minimizing the impact on cell resistance and energy efficiency because there is little current flow in this zone.

Various shapes of vertical electrodes are proposed. When considering the shape of the electrode plate, particularly the shape of the cathode plate that produces metal, it is necessary to consider complexity, manufacturing difficulty, and concerns about cracking and insufficient strength.

Another method includes minimizing the middle region 120 of the electrode plate 100 as much as its mechanical strength and stability allow. For example, for thin electrode plates, wherein the thickness is much smaller than its length or width, and wherein the aspect ratio of the length to the average width is between 5 and 10, in a preferred embodiment about 8, the ratio of the cross-sectional area of the top of the electrode plate to the cross-sectional area of the bottom of the electrode plate should be greater than 1, more preferably equal to or greater than 2.

As shown in fig. 2A, the electrode plate 100 has a straight rectangular shape in which the average cross-sectional area ratio of the ACO region to the middle or lower region is 1 (one). However, the surface ratio between the ACO and the intermediate region may be adjusted or tuned by changing the ACO region so that the surface ratio is greater than 1.

Fig. 2B, 2C and 2D show more complex shapes, with the electrode plates having a larger area in the high current density region and a smaller area in the low current density region. One can choose the shape and size of the electrode plates while optimizing cell voltage, energy consumption and mechanical strength of the electrode plates.

Fig. 2B shows an electrode plate 200 having a gatepost shape with a pair of narrow legs 210 on each side, a gap 220 in the middle, and connection regions 120, 130 below the ACO region 110.

Fig. 2C shows an electrode plate 300 in the form of a paddle that is wider in the ACO region 110 and narrower in the intermediate/connection regions 120, 130.

Fig. 2D shows an electrode plate 400 in a trapezoidal shape, wherein the width of the electrode plate continuously decreases from the ACO region 110 to the middle region 120 and then to the connection region 130.

The shape resulting in the highest current density is the shape with the smallest area in the intermediate/connection regions 120, 130 below the ACO region 110, e.g. with the gatepost shape 200 and the paddle shape 300.

The trapezoidal shape 400 of fig. 2D preferably combines the following advantages: maximizing the metal created in the upper ACO region 110, ease of manufacture (i.e., the component may be made in a mesh without cuts), low manufacturing cost, sufficient strength, and avoiding abrupt changes in cross-section or internal cuts that are sources of crack initiation (i.e., no weak points or crack initiation sites are introduced).

In general, when used as a cathode plate, the electrode plate as defined herein may be formed of titanium diboride (TiB ₂ ) Or zirconium diboride (ZrB) ₂ ) Is prepared. Any material that is electrically conductive, resistant to molten metal and electrolyte, and wettable by metal (e.g., aluminum) may be used without departing from the scope of the present disclosure.

As shown in fig. 4 and 5, a method 1000 or method 2000, respectively, for controlling the current density of a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in an electrolytic cell, the electrode plates defining: a connection region for connecting the electrode plate to the electrolytic cell; an intermediate region extending from the connection region without overlapping with the adjacent electrode; and an ACO region extending from the intermediate region and configured to overlap an adjacent electrode; wherein each electrode plate includes a surface facing another electrode plate of an adjacent row.

As shown in fig. 4, the method 1000 includes the steps of:

1100, maximizing the current density in the ACO region by varying the ratio of the surface area of the ACO region to the surface area of the intermediate region, e.g. the ACO/intermediate surface area ratio is greater than 1.

As shown in fig. 5, the method 2000 includes the steps of:

-2100 providing an electrode plate, wherein the average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1 in order to maximize the current density in the ACO region while maintaining the mechanical strength of the connecting region for supporting the electrode plate.

As shown in fig. 6, a method 3000 for maximizing the current density of an electrolytic cell is also disclosed, the electrolytic cell comprising a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in the electrolytic cell. The method 3000 includes the steps of:

3100 replacing each existing electrode plate of the electrolytic cell with that disclosed herein.

Example

Fig. 3 shows an example of an electrode plate 500 according to a preferred embodiment of the present disclosure, which also includes an ACO region 110, a connection region 130, and an intermediate region 120 extending therebetween.

The electrode plate 500 is different from the trapezoidal electrode plate 400 of fig. 2D in that the opposite edges 530a, 530b of the connection region 130 of the electrode plate 500 are parallel to each other. The width of the electrode plate 500 continuously decreases from X1 at the top end 510 of the ACO region 110 to X2 at the bottom end 520 of the intermediate region 120, and the bottom 530 of the electrode plate forms the connection region 130, which has a rectangular-like shape with parallel edges 530a, 530 b.

According to a preferred embodiment, as shown in fig. 3, the electrode plate 500 may also have a rounded transition, indicated by radius R1, between the top end 510 of the ACO region 110 and each of the two opposing edges 510a, 510 b. In addition, the electrode plate 500 may have a rounded transition, represented by radius R2, between the bottom end 530 of the connection region 130 and each of the two opposing edges 530a, 530 b. Such rounded transitions R1 and/or R2 allow avoiding the introduction of weak points or crack initiation sites of the electrode plate 500.

Table 1 below provides some dimensions of the electrode plate 500 shown in fig. 3, where L represents the overall length of the electrode plate.

Table 1: examples of electrode plates (FIG. 3)

The electrode plates disclosed herein avoid the drawbacks discussed in accordance with the previous embodiments because there are no abrupt geometric changes or narrow cross-sections. The component can be formed as a net without cuts that can introduce flaw and crack initiation sites.

The application enables competitive energy efficiency in metal production. The application also allows less heat loss in the cathode plate.

While the illustrative and presently preferred embodiments of the present disclosure have been described in detail above, it should be understood that the inventive concepts may be variously embodied and employed, and that the appended claims are intended to be construed to include such variations unless limited to the prior art.

Claims

1. An electrode plate for use in the electrolytic production of metal using an electrolytic cell, the electrolytic cell comprising a plurality of said electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows of said anode and cathode plates, said electrode plates defining:

a connection region adjacent a first end of the electrode plate for connecting the electrode plate to the electrolytic cell;

an intermediate region extending from the connection region without overlapping an adjacent electrode plate; and

an anode-cathode overlap (ACO) region extending from the intermediate region to a second end of the electrode plate opposite the first end and configured to overlap an adjacent electrode plate;

wherein the electrode plate comprises two opposite surfaces for facing the surfaces of the electrode plates of adjacent rows; and is also provided with

Wherein the ratio of the surface area of the ACO region to the surface area of the intermediate region is greater than 1 in order to maximize the current density in the ACO region.

2. The electrode plate of claim 1, wherein the ACO/intermediate surface area ratio is equal to or greater than 2.

3. The electrode plate according to claim 1 or 2, wherein the electrode plate has a rectangular shape, wherein the width of the electrode plate is constant from the ACO region to the intermediate region and the connection region.

4. The electrode plate of claim 1 or 2, wherein the electrode plate is in the shape of a gatepost, wherein the intermediate region and the connecting region each define a pair of legs on either side thereof, a central gap between the legs being located below the ACO region.

5. The electrode plate of claim 1 or 2, wherein the electrode plate is paddle-shaped, wherein the ACO region has a first width, the intermediate region and the connecting region have a second width, the second width being less than the first width.

6. The electrode plate of claim 1 or 2, wherein the electrode plate is trapezoidal in shape, wherein the width of the electrode plate decreases from the second end to the first end of the electrode plate.

7. The electrode plate according to claim 1 or 2, wherein the ACO region and the intermediate region of the electrode plate have a trapezoidal shape, the width of the electrode plate decreasing from the second end of the electrode plate to a junction between the intermediate region and a connection region, the connection region having a rectangular shape.

8. The electrode plate of any one of claims 1 to 7, wherein a peripheral edge of the surface has a rounded transition between the first end of the plate and the connection region and/or the peripheral edge has a rounded transition between the second end and the ACO region.

9. The electrode plate of any one of claims 1 to 8, wherein the metal to be produced is aluminum, the electrode plate being wettable by liquid aluminum metal.

10. The electrode plate of any one of claims 1 to 9, wherein the electrode plate is a cathode plate.

11. An electrode plate for use in the electrolytic production of metal using an electrolytic cell, the electrolytic cell comprising a plurality of said electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows of said anode and cathode plates, said electrode plates defining:

an intermediate region extending from the connection region without overlapping with an adjacent electrode; and

an ACO region extending from the intermediate region and configured to overlap an adjacent electrode;

wherein the average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1 so as to maximize the current density in the ACO region while maintaining the mechanical strength of the connecting region for supporting the electrode plate.

12. The electrode plate of claim 11, wherein the average ACO/intermediate cross-sectional area ratio is equal to or greater than 2.

13. The electrode plate of claim 11 or 12, wherein the electrode plate is in the shape of a gatepost, wherein the intermediate region and the connecting region each define a pair of legs on either side thereof, a central gap between the legs being located below the ACO region.

14. The electrode plate of claim 11 or 12, wherein the electrode plate is paddle-shaped, wherein the ACO region has a first width, the intermediate region and the connecting region have a second width, the second width being less than the first width.

15. The electrode plate of claim 11 or 12, wherein the electrode plate has a trapezoidal shape, wherein the width of the electrode plate decreases from the second end to the first end of the electrode plate.

16. The electrode plate of claim 11 or 12, wherein the ACO region and the intermediate region of the electrode plate are trapezoidal in shape, the width of the electrode plate decreasing from the second end of the electrode plate to a junction between the intermediate region and a connection region, the connection region being rectangular in shape.

17. The electrode plate of any one of claims 11 to 16, wherein the electrode plate comprises two opposing surfaces for facing surfaces of electrode plates of adjacent rows, and wherein a peripheral edge of the surfaces has a rounded transition between a first end of the plate and the connection region, and/or the peripheral edge has a rounded transition between the second end and the ACO region.

18. The electrode plate of any one of claims 11 to 17, wherein the metal is aluminum, the electrode plate being wettable by liquid aluminum metal.

19. The electrode plate of any one of claims 11 to 18, wherein the electrode plate is a cathode plate.

20. An electrolytic cell for the electrolytic production of metal, the cell comprising one or more electrode plates according to any one of claims 1 to 19.

21. The electrolytic cell of claim 20 wherein the metal is aluminum.

22. Use of an electrode plate according to any one of claims 1 to 19 or an electrolytic cell according to claim 20 or 21 for manufacturing an electrolytic cell comprising a plurality of said electrode plates.

23. A method for controlling current density of a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in an electrolytic cell, the electrode plates defining:

a connection region for connecting the electrode plate to the electrolytic cell;

wherein each electrode plate includes a surface facing another electrode plate of an adjacent row;

the method comprises the following steps:

the current density in the ACO region is maximized by varying the ratio of the surface area of the ACO region to the surface area of the intermediate region, e.g., the ACO/intermediate surface area ratio is greater than 1.

24. A method for controlling current density of a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in an electrolytic cell, the electrode plates defining:

the method comprises the following steps:

providing an electrode plate, wherein the average cross-sectional area ratio of the ACO region to the intermediate region and the connecting region is greater than 1, so as to maximize current density in the ACO region while maintaining mechanical strength of the connecting region for supporting the electrode plate.

25. A method for maximizing the current density of an electrolytic cell comprising a plurality of electrode plates defining vertically aligned anode and cathode plates and arranged in alternating rows in the cell, the method comprising the steps of: each existing electrode plate of the cell is replaced with an electrode plate according to any one of claims 1 to 19.