WO2023232238A1

WO2023232238A1 - Mica multilayer plate

Info

Publication number: WO2023232238A1
Application number: PCT/EP2022/064819
Authority: WO
Inventors: Thomas Hupfer; Nils Giesselmann
Original assignee: Ceres Intellectual Property Company Limited; Robert Bosch Gesellschaft mit beschränkter Haftung
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2023-12-07
Also published as: TW202348411A

Abstract

The invention relates to a mica multilayer plate (10), preferably for a use as insulation plate in an electrochemical cell assembly, the mica multilayer plate comprising a plurality of mica layers (12) overlying one another along a stacking direction (14), wherein at least one of said plurality of mica layers (12) is a perforated mica layer (16), said at least one perforated mica layer having at least one machined hole. The invention also relates to a method of manufacturing a mica multilayer plate and to an electrochemical cell assembly comprising a mica multilayer plate.

Description

Title

Mica multilayer plate

State of the Art

The invention relates to the field of mica material for thermal and electrical insulation. More specifically, the invention relates to the field of mica plates, and electrochemical cell assemblies comprising such mica plates.

Mica material is used for a range of insulation applications, such as thermal and electrical insulation. Typically, mica is provided in a plate-like geometry, consisting of multiple layers of mica paper glued together with a binder material.

An exemplary field of application for mica is the field of electrochemical cell stacks, such as fuel cell stacks or electrolyser cell stacks. Fuel cells are energy conversion devices that allow for conversion of electrochemical fuel to electricity. Electrolyser cells are fuels cells running in reverse mode, i.e. using electricity to generate chemicals. Reversible cells are capable of operating in both modes. Solid oxide cells (SOCs) are a particular class of electrochemical cells, which can be run as solid oxide fuel cell (SOFC) or as solid oxide electrolyser cell (SOEC). SOFCs use an electrochemical conversion process that oxidises fuel to produce electricity. SOECs are SOCs run in reverse mode compared to SOFCs and are commonly used for the generation of chemicals using electricity (e.g. electrolysis of water).

Typically, multiple electrochemical cells are stacked upon one another to form a cell "stack", wherein the stacked cells are held in compression between end plates provided on opposite ends of the fuel cell stack. In such cell stacks, a mica plate is commonly provided between each end plate and the stack of cell repeat units in order to electrically insulate the endplate from the cell stack. Despite its intrinsically high electrical insulation properties, the electrical insulation capability of mica may be reduced at high operating temperatures, e.g. when used in a SOC (operating temperatures of SOCs typically range from 600 °C to 1000 °C). More specifically, thermally activated ionic conductivity may occur at high operating temperatures, thus increasing the risk of undesired leak currents.

The invention seeks to improve the electric insulation properties of mica material, in particular of mica plates.

Summary of the Invention

According to the invention, there is provided a mica multilayer plate, preferably for use as an insulation plate in an electrochemical cell assembly. The mica multilayer plate comprises a plurality of areally extending mica layers overlying one another along a stacking direction. That is, the mica layers preferably are stacked upon one another along the stacking direction. According to the invention, at least one of said plurality of mica layers is a perforated mica layer, said at least one perforated mica layer having at least one machined hole (i.e. at least one through-hole), extending along the stacking direction.

The proposed mica multilayer plate allows for improved electrical insulation over a wide temperature range. Furthermore, the proposed multilayer design allows for reduced material thickness compared to prior art mica plates with the same insulation properties. More specifically, due to the at least one hole in the at least one perforated mica layer, local cavities may be formed inside the mica multilayer plate, thus reducing the number of potential conductive paths. In addition, the multilayer concept allows for providing undercuts and closed cavities which are not available via mechanical machining. In the context of this application, the term "machined hole" does not include microscopically small defects or holes naturally occurring in the mica material. That is to say, a machined hole is a deliberately introduced cavity or recess in the final multi-layered material. Preferably, the mica layers each have the same outer dimensions (i.e. same areal extent perpendicular to the stacking direction). Preferably, the mica layers each comprise or consist of mica paper. In the context of this application, the term "mica paper" is used in its usual-sense to refer to a sheet-like aggregate of mica particles. Mica paper is commonly prepared by grinding mica material into fine particles, preparing an aqueous suspension or slurry of said mica particles, and then forming it into paper (e.g. sheet) by conventional papermaking techniques. Preferably, the mica paper, in particular each mica layer of the mica multilayer plate, has a thickness along the stacking direction of at least 10 pm and/or at most 500 pm, more preferably at most 300 pm, and even more preferably at most 200 pm.

Preferably, the, some or each perforated mica layer comprises a plurality of holes, that is two or more holes. The two or more holes preferably are spaced apart from each other by mica material. The plurality of holes may be arranged randomly along the layer plane. Alternatively, the plurality of holes may arranged in an array fashion (that is a repetitive pattern of geometrical shapes) along the layer plane, e.g. in a hexagonal or square array. The latter allows for tuning the layer properties in a defined way.

According to a general aspect, at least one of the plurality of mica layers may be a non-perforated mica layer, said at least one non-perforated mica layer preferably being distinguished from said at least one perforated mica layer in that said at least one non-perforated mica layer does not have a machined hole.

In some embodiments, a first outer surface (e.g. a top surface) and/or an opposite second outer surface (e.g. a bottom surface) of the mica multilayer plate may be provided by a non-perforated mica-layer. That is to say, the first and/or the second surface does not have a machined hole, thus providing a flat outer surface. In some embodiments, a top layer of the mica multilayer plate and/or a bottom layer of the mica multilayer plate may be a non-perforated mica-layer or group of non-perforated mica layers.

Alternatively, a first outer surface (e.g. a top surface) and/or an opposite second outer surface (e.g. a bottom surface) of the mica multilayer plate may be provided by a perforated mica-layer. Thus, the first and/or the second surface may have at least one hole. This has the advantage that a contact area of the mica multilayer plate, e.g. to an end plate of an electrochemical cell assembly (see below), may be reduced, thus improving electrical insulation due to reduced potential electrical pathways. In some embodiments, a top layer of the mica multilayer plate and/or a bottom layer of the mica multilayer plate may be a perforated mica-layer or group of perforated mica layers.

The proposed multilayer concept also allows for tuning the physical properties of the mica multilayer plate. For example, placing perforated and/or non-perforated mica layers with defined orientation and/or stacking order relative to each other may influence the Young's modulus and/or the gas permeability of the mica multilayer plate. In addition, anisotropic electrical insulation properties may be achieved.

The mica multilayer plate may comprise at least two perforated mica layers having the same hole configuration, said at least two perforated mica layers being arranged in the multilayer plate in different rotational orientation around the stacking direction.

Alternatively or in addition, the mica multilayer plate may comprise at least a first and a second perforated mica layer, said first and second perforated mica layers having different hole configurations. That is to say, first and second perforated mica layers may have a different number of holes, the holes may have a different shape, the holes may have different size, and/or the holes may be arranged at different positions along the mica layer (first and second perforated mica layers preferably have the same outer dimensions). As set out above, this allows for tuning the properties of the mica multilayer plate.

In one embodiment, a first outer surface (e.g. top surface) of the mica multilayer plate may be provided by a first non-perforated mica layer, and an opposite second outer surface (e.g. bottom surface) of the mica multilayer plate may be provided by a second non-perforated mica-layer, wherein at least two perforated mica layers or groups of perforated mica layers are arranged between said first and second non-perforated mica layers, and wherein at least one additional nonperforated mica layer or group of non-perforated mica layers is arranged between said at least two perforated mica layer. In some embodiments, multiple non-perforated mica layers or groups of nonperforated mica layers and multiple perforated mica layers or groups of perforated mica layers may be stacked in an alternating fashion along the stacking direction. Thus, a plurality of internal cavities may be formed inside the mica multilayer plate, which allows for better insulation properties as described above.

According to a preferred aspect, the mica multilayer plate may comprise a stacking group of perforated mica layers, that is a group of perforated mica layers stacked upon one another along the stacking direction. Preferably, the perforated mica layers of said stacking group are configured and stacked directly on each other such that at least a subset of the holes of adjacent perforated mica layers of said stacking group at least partially overlap with one another, thus forming at least one through-hole or cavity, preferably extending throughout the stacking group along the stacking direction. Thus, air trapped in said at least one through- hole or cavity may improve the thermal insulation properties of the mica multilayer plate. Preferably, the perforated mica layers of the stacking group each comprise a plurality of holes such that a plurality of through-holes or cavities are formed in the stacking group. Preferably, the holes of adjacent layers of the stacking group are arranged coaxially to each other, thus forming through-holes extending throughout the entire thickness of the stacking group. Preferably, the perforated mica layers of the stacking group have the same hole configuration, i.e. same number of holes, same hole shape, and same hole position. This eases manufacturing as only one type of perforated mica layer must be provided.

In some embodiments, the stacking group of perforated mica layers may be located between a first non-perforated mica layer or first group of non-perforated mica layers and a second non-perforated mica layer or second group of nonperforated mica layers. That is, the stacking group may be sandwiched between a first non-perforated mica layer and a second non-perforated mica layer. Thus, the at least one through-hole formed in the stacking group is closed on both sides, thus forming at least one closed cavity inside the mica multilayer plate. The first non-perforated mica layer or group of non-perforated mica layer may form a base part of the mica multilayer plate. The second non-perforated mica layer or group of non-perforated mica layers may form a top part of the mica multilayer plate. In some embodiments, the mica multilayer plate may comprise a group of nonperforated mica layers stacked upon another along the stacking direction, said group of non-perforated mica layers forming a base or top part of the mica multilayer plate, and the stacking group of perforated mica layers may form a top or base part of the multilayer plate. Thus, the mica multilayer plate may comprise openings (that is the through-holes formed in the stacking group) at one face, which allows for gaseous components (e.g. binder components) leaving the mica multilayer plate during thermal load.

In some embodiments, the stacking group of perforated mica layers may be located between a first perforated mica layer or first group of perforated mica layers and a second perforated mica layer or second group of perforated mica layers, said first and second perforated mica layers or groups of perforated mica layer being configured and/or arranged such that at least a subset of the holes of the first and second perforated mica layers, preferably all holes, do not overlap with the holes in the perforated mica layers of the stacking group of perforated mica layers. In such a configuration, closed cavities may be formed inside the multilayer plate without using non-perforated mica layers.

When viewed along the stacking direction, some or all of the holes of a respective perforated mica layer may have the same shape, e.g. square, circular, or anisotropic shapes. This allows using the same machining tool to prepare the holes, thus reducing manufacturing costs.

To achieve good electrical insulation properties, it may be advantageous if - for the, some or each perforated mica layer - a ratio between the surface area of the layer plane occupied by the hole or holes and the total area of the perforated mica layer defined by the outer dimensions of said perforated mica layer is at least 20%, preferably at least 30%. For improved mechanical stability, it may be advantageous if said ratio is at most 90%.

Preferably, adjacent mica layers are bonded with a binder material. The binder preferably is configured not to degas at elevated temperatures, or at least is configured to decompose with minimal gas evolution. Preferably, the binder comprises an inorganic base material, for example a silicone. Silicones (as well as siloxanes) are hybrid organic-inorganic materials that decompose at high temperatures to inorganic material and gas.

According to a general aspect, the at least one machined hole in the perforated mica layers may be formed by cutting or punching the respective mica layer, e.g. using a cutting plotter.

The invention also relates to a method of manufacturing a mica multilayer plate. The features and advantages described above with respect to the mica multilayer plate are also applicable to the method of manufacturing. The method comprises a step of providing a plurality of mica layers, preferably comprising or consisting of mica paper. The method further comprises a step of processing, in particular machining, at least one of said plurality of mica layers to form at least one hole (i.e. through-hole), within the material of said at least one mica layer. The method further comprises a step of overlying said plurality of processed and/or unprocessed (i.e. perforated and non-perforated) mica layers one upon another along a stacking direction. Optionally, the method may comprise a step of applying a binder between the mica layers before stacking them upon one another.

In some embodiments, the step of forming the at least one hole may include a step of cutting, laser cutting, plotting, or punching, preferably rotary punching, said at least one mica layer.

The invention also relates to an electrochemical cell assembly comprising a stack of cell repeat units and at least one mica multilayer plate as defined above. The features and advantages described above with respect to the mica multilayer plate itself are also applicable to the electrochemical cell assembly. Preferably, the stack of cell repeat units comprises a plurality of electrochemical cells (cell repeat units) stacked upon one another along the stacking direction.

More specifically, the invention relates to an electrochemical cell assembly comprising a stack of cell repeat units and at least one insulation plate, wherein the at least one insulation plate comprises a mica multilayer plate as defined above, and wherein the stack of cell repeat units and the at least one insulation plate are stacked upon one another along a stacking direction. The invention also relates to an electrochemical cell assembly comprising a first end plate, a stack of cell repeat units, and a second end plate. The stack of cell repeat units comprises a plurality of electrochemical cells (cell repeat units) stacked upon one another along a stacking direction. Said stack of cell repeat units is located between said first end plate and said second end plate. The electrochemical cell assembly further comprises a first mica multilayer plate constituted as described above and located between said first end plate and said stack of cell repeat units and/or a second mica multilayer plate constituted as described above and located between said second end plate and said stack of chemical cell repeat units.

The end plates may be metal plates.

The cell repeat units may be fuel cell units, electrolyser cell units or reversible cell units. The cell repeat units may be metal-supported electrochemical cell units. The cell repeat units may be solid oxide fuel cell units or solid oxide electrolyser cell units. The cell units each may comprise multiple layers, including a mechanical support layer, electrochemically active layers, and, optionally, a spacer or interconnector. The electrochemically active layers may comprise a fuel electrode layer, an electrolyte layer and an air or oxidant electrode layer. The electrochemically active layers may be deposited (e.g. as thin coatings or films) on and supported by the mechanical support layer, e.g. by a metal support plate, such as a metal foil. The stack of cell repeat units, in addition to said cell repeat units, may comprise further components, such as electrical connectors, electrical contact plates (e.g. monopole plates) or sealing gaskets.

Further embodiments are derivable from the following description and the drawings.

In the drawings:

Fig. 1 shows a simplified outline of a mica multilayer plate from a perspective view;

Fig. 2 shows a top view of an example of a perforated mica layer; Fig. 3 shows a simplified outline of an embodiment of a mica multilayer plate from an exploded perspective view;

Fig. 4 shows a simplified outline of a further embodiment of a mica multilayer plate from an exploded perspective view;

Fig. 5 shows a sectional view of a further embodiment of a mica multilayer plate;

Fig. 6 shows a sectional view of a further embodiment of a mica multilayer plate;

Fig. 7 shows a simplified outline of an embodiment of an electrochemical cell assembly.

Figure 1 schematically shows an example of a mica multilayer plate 10. The mica multilayer plate 10 comprises a plurality of mica layers 12, stacked upon one another along a stacking direction 14. Preferably, the mica layer 12 are bonded with a binder material (known in the art).

The mica layers 12 each comprise or consist of mica paper. More specifically, each mica layer 12 may consist of a single mica paper sheet. Alternatively, each mica layer 12 may comprise several mica paper sheets stacked one upon another along the stacking direction 14, and, optionally, bonded with a binder material. Preferably, each mica layer 12 has a thickness of at least 10 pm and/or usually at most 200 pm.

At least one of said mica layers 12 is a perforated mica layer 16, said at least one perforated mica layer 16 having at least one machined through-hole 18, e.g. formed by cutting or punching the mica layer 12. Referring to Fig. 2, there is shown a top view of an example of such a perforated mica layer 16. In this example, the perforated mica layer 16 comprises a plurality of holes 18, said holes 18 being separated from each other by mica material 20, and arranged in an array fashion. Exemplarily, the holes 18 are square-shaped.

In embodiments not shown, the holes 18 may be arranged in a random fashion and/or have different shape, e.g. circular, rectangular, oval, etc, and/or have different size. In addition, a perforated mica layer 16 may comprise more or less holes 18.

Preferably, a ratio between the surface area occupied by the hole or holes 18 and the total area of the perforated mica layer 16 defined by the outer dimensions of said perforated mica layer 16 is at least 20%, more usually at least 30% and/or is at most 90%.

The mica multilayer plate 10 may additionally comprise at least one nonperforated mica layer 22, that is a mica layer 12 without machined holes 18. In the example of Fig. 1 , the top layer 24 of the mica multilayer plate 10 is a nonperforated mica layer 22. Thus, a first outer surface 26 (top surface 26) of the mica multilayer plate 10 is provided by a non-perforated mica layer 22.

Referring to Figure 3 to 6, there are shown various examples of a mica multilayer plate 10.

In the example of Fig. 3, both a top layer 24 and a bottom layer 28 are nonperforated mica layers 22 or groups of non-perforated mica layers 22. Thus, both a top surface 26 (first outer surface 26) and a bottom surface 30 (second outer surface 30) are provided by a non-perforated mica layer 22. In the example, a group 32 of perforated mica layers 16 (difference to non-perforated mica layers 22 is only schematically indicated in Fig. 3 by the different hatching) is sandwiched between the non-perforated mica layers 22 at the top and at the bottom of the mica multilayer plate 10. The perforated mica layers 16 may have the same hole configuration or different hole configuration. For instance, the perforated mica layers 16 may be configured as shown in Fig. 2.

Figure 4 shows a further example of a mica multilayer plate 10. In this example, again, both a top layer 24 and a bottom layer 28 of the mica multilayer plate 10 are non-perforated mica layers 22 or groups of non-perforated mica layers 22. Thus, a top surface 26 (first outer surface 26) is provided by a first non-perforated mica layer 24 and a bottom surface 30 (second outer surface 30) is provided by a second non-perforated mica layer 28. In addition, there are two perforated mica layers 16 or groups of perforated mica layers 16 arranged between said first nonperforated mica layer 24 or group of non-perforated mica layers 22 and said second non-perforated mica layer 28 or group of non-perforated mica layers 22. Furthermore, there is provided an additional non-perforated mica layer 22 or group of non-perforated mica layers 22 arranged between said perforated mica layers 16 or groups of perforated mica layers. Thus, in the example of Fig. 4, perforated mica layers 16 and non-perforated mica layers 22 are stacked upon one another along the stacking direction 14 in an alternating fashion. The perforated mica layers 16 may have the same hole configuration or may have different hole configuration, as exemplarily indicated in Fig. 4 by the different hatching.

Referring to Fig. 5, there is shown a further example of a mica multilayer plate 10, comprising a group 34 of non-perforated mica layers 22 forming a base part 36 of the mica multilayer plate 10, and a group 38 of non-perforated mica layers 22 forming a top part 40 of the mica multilayer plate 10. The groups 34, 38 preferably comprise a plurality of non-perforated mica layers 22 stacked upon one another along the stacking direction 14. In addition, there is provided a plurality of perforated mica layers 16, stacked upon one another along the stacking direction 14 to form a stacking group 42, said stacking group 42 being sandwiched between the groups 34, 38 of non-perforated mica layers 22.

As can be seen from Fig. 5, the perforated mica layers 16 of the stacking group 42 preferably have the same configuration of holes 18 and are stacked upon one another along the stacking direction 14 such that the holes 18 of adjacent perforated mica layers 16 overlap, exemplarily in a coaxial fashion. Thus, internal cavities 44 are formed in the mica multilayer plate 10. As set out above, said cavities 44 may trap air inside the mica multilayer plate 10, which enhances the insulation properties of the mica multilayer plate 10.

Although being advantageous, the perforated mica layers 16 of the stacking group 42 not necessarily need to have the same configuration of holes 18. For example, the perforated mica layers 16 of the stacking group 42 may be configured such that only a subset of the holes of adjacent perforated mica layers at least partially overlap with one another.

In embodiments not shown, the base part 36 and/or the top part 40 may be formed from a perforated mica layer 16 or group of perforated mica layers 16, said perforated mica layer 16 or group of perforated mica layers being configured such the holes 18 of said perforated mica layer 16 or group of perforated mica layers 16 do not overlap with the cavities 44 formed in the stacking group 42, i.e. do not overlap with the holes 18 in the perforated mica layers 16 of the stacking group 42.

Referring to Fig. 6, there is shown a further embodiment of a mica multilayer plate 10, said embodiment differing from the embodiment of Fig. 5 in that the group 38 of non-perforated mica layers 22 forming the top part 40 is omitted. Thus, in the example of Fig. 6, the stacking group 42 forms the top part 40 of the mica multilayer plate 10. In this configuration, the cavities 44 are open at one side, thus allowing for gases to evaporate.

The mica multilayer plates 10 described above may be manufactured by a method comprising the steps of: providing a plurality of mica layers 12; providing at least one perforated mica layer 16 by processing at least one of said plurality of mica layers 12 to form at least one hole 18 within the material of said at least one mica layer 12 (e.g. by cutting, optionally laser cutting, plotting, or punching, optionally rotary punching); overlying said plurality of mica layers 12 (i.e. including perforated mica layers 16 and, optionally, non-perforated mica layers 22) upon another along the stacking direction 14.

Figure 7 shows a schematic outline of an example of an electrochemical cell assembly 100 (simplified to illustrate key aspects of the invention). The electrochemical cell assembly comprises a first end plate 102, a second end plate 104, and a stack 106 of cell repeat units, said stack 106 of cell repeat units being located between said first end plate 102 and said second end plate 104. The stack 106 comprises a plurality of cell repeat units 108 stacked upon one another along the stacking direction 14. As set out above, the cell repeat units 108 may be fuel cells or electrolyser cells.

Preferably, the stack 104 is held in a compressed fashion between said end plates 104, 106. For this, the electrochemical cell assembly 100 may comprise additional compression means (not shown) known in the art, such as tension rods, compression springs or bolts, clamps or other means for compression.

The electrochemical cell assembly 100 further comprises a first mica multilayer plate 10 located between the first end plate 102 and the stack 106 of cell repeat units 108 and a second mica multilayer plate 10 located between the second end plate 104 and the stack 106 of cell repeat units 108. The mica multilayer plates 10 (in Fig. 7 only schematically indicated) may be constituted according to any of the examples described above.

Claims

1. Mica multilayer plate (10), preferably for a use as insulation plate in an electrochemical cell assembly (100), the mica multilayer plate (10) comprising a plurality of mica layers (12) overlying one another along a stacking direction (14), wherein at least one of said plurality of mica layers (12) is a perforated mica layer (16), said at least one perforated mica layer (16) having at least one machined hole (18).

2. Mica multilayer plate (10) according to claim 1, wherein the, some or each perforated mica layer (16) comprises a plurality of holes (18).

3. Mica multilayer plate (10) according to claim 1 or claim 2, wherein at least one of said plurality of mica layers (12) is a non-perforated mica layer (22).

4. Mica multilayer plate (10) according to claim 3, wherein a first outer surface (26) and/or an opposite second outer surface (30) of the mica multilayer plate (10) is provided by a non-perforated mica-layer (22).

5. Mica multilayer plate (10) according to any of claims 1 to 3, wherein a first outer surface (26) and/or an opposite second outer surface (30) of the mica multilayer plate (10) is provided by a perforated mica-layer (16).

6. Mica multilayer plate (10) according to any one of the preceding claims, wherein the mica multilayer plate (10) comprises at least two perforated mica layers (16) having the same hole configuration, said at least two perforated mica layers (16) being arranged in different rotational orientation around the stacking direction (14).

7. Mica multilayer plate (10) according to any one of the preceding claims, wherein the mica multilayer plate (10) comprises at least two perforated mica layers (16) having different hole configurations.

8. Mica multilayer plate (10) according to any of claims 3 to 7, wherein: a first outer surface (26) of the mica multilayer plate (10) is provided by a first non-perforated mica layer (22), an opposite second outer surface (30) of the mica multilayer plate (10) is provided by a second non-perforated mica-layer (22), at least two perforated mica layers (16) are arranged between said first and second non-perforated mica layers (22) and at least one additional non-perforated mica layer (22) is arranged between said at least two perforated mica layer (16).

9. Mica multilayer plate (10) according to any of claims 3 to 8, wherein multiple non-perforated mica layers (22) or groups of non-perforated mica layers (22) and multiple perforated mica layers (16) or groups of perforated mica layers (16) are stacked in an alternating fashion along the stacking direction (14).

10. Mica multilayer plate (10) according to any one of the preceding claims, wherein the mica multilayer plate (10) comprises a stacking group (42) of perforated mica layers (16), the perforated mica layers (16) of said stacking group (42) being configured and stacked on each other such that at least a subset of the holes (18) of adjacent perforated mica layers (16) at least partially overlap with one another.

11. Mica multilayer plate (10) according to the preceding claim, wherein the stacking group (42) of perforated mica layers (16) is located between a first group (34) of non-perforated mica layers (22) forming a base part (36) of the mica multilayer plate (10) and a second group (38) of non-perforated mica layers (22) forming a top part (40) of the mica multilayer plate (10).

12. Mica multilayer plate (10) according to claim 10, wherein the mica multilayer plate (10) comprises a group (34) of non-perforated mica layers (22) forming a base part (36) of the mica multilayer plate (10) and wherein the stacking group (42) of perforated mica layers (16) forms a top part (40) of the multilayer plate (10).

13. Mica multilayer plate (10) according to claim 10, wherein the stacking group (42) of perforated mica layers (16) is located between a first perforated mica layer (16) and a second perforated mica layer (16), said first and second perforated mica layers (16) being configured and/or arranged such that at least a subset of the holes (18) of said first and second perforated mica layers (16) does not overlap with the holes (18) in the perforated mica layers (16) of the stacking group (42).

14. Mica multilayer plate (10) according to any one of claims 10 to 13, wherein the perforated mica layers (16) of the stacking group (42) have the same hole configuration.

15. Mica multilayer plate (10) according to any one of claims 2 to 14, wherein the plurality of holes (18) of a perforated mica layer (16) are arranged in an array fashion.

16. Mica multilayer plate (10) according to any one of the preceding claims, wherein, when viewed along the stacking direction 14, some or all of the holes (18) of a respective perforated mica layer (16) have the same shape.

17. Mica multilayer plate (10) according to any one of the preceding claims, wherein for the, some or each perforated mica layer (16), a ratio between the surface area occupied by the hole (18) or holes (18) and the total area of the perforated mica layer (16) defined by the outer dimensions of said perforated mica layer (16) is at least 20%, preferably at least 30% and/or is at most 90%.

18. Mica multilayer plate (10) according to any one of the preceding claims, wherein the mica layers (12) each comprise or consist of mica paper, preferably with a thickness of at least 10 pm and/or at most 500 pm.

19. Mica multilayer plate (10) according to any one of the preceding claims, wherein adjacent mica layers (12) are bonded by binder.

20. Mica multilayer plate (10) according to any one of the preceding claims, wherein the at least one hole (18) in a perforated mica layer (16) is formed by cutting or punching a respective mica layer (12).

21. Method of manufacturing a mica multilayer plate (10) according to any one of the preceding claims, the method comprising: providing a plurality of mica layers (12); processing at least one of said plurality of mica layers (12) to form at least one hole (18) within the material of said at least one mica layer (12); overlying said plurality of mica layers (12) upon another along a stacking direction (14). Method according to claim 21 , wherein the step of forming the at least one hole (18) includes at least cutting, optionally laser cutting, plotting, or punching, optionally rotary punching, said at least one mica layer (12). An electrochemical cell assembly (100) comprising a stack (106) of cell repeat units (108) and at least one insulation plate, said stack (106) of cell repeat units (108) and said at least one insulation plate being stacked upon one another along a stacking direction (14), wherein the at least one insulation plate comprises a mica multilayer plate (10) according to any one of claims 1 to 20. An electrochemical cell assembly (100) comprising a first end plate (102), a stack (106) of cell repeat units (108), comprising a plurality of cell repeat units (108) stacked upon one another along a stacking direction (14), and a second end plate (104), said stack (106) of cell repeat units (108) being located between said first end plate (102) and said second end plate (104), the electrochemical cell assembly (100) further comprising a first mica multilayer plate (10) according to any one of claims 1 to 20 located between said first end plate (102) and said stack (106) of cell repeat units (108) and/or a second mica multilayer plate (10) according to any one of claims 1 to 20 located between said second end plate (104) and said stack (106) of cell repeat units (108).