CN219497829U - Pole piece, electrode assembly, battery cell, battery module and power utilization device - Google Patents

Abstract

The application provides a pole piece, an electrode assembly, a battery cell, a battery module and an electricity utilization device. The pole piece comprises a current collector, a packaging structure and an active substance layer, wherein the current collector comprises two surfaces which are opposite to each other along the thickness direction of the current collector. The packaging structure is connected to at least one of the two surfaces and forms a containing cavity together with the current collector. The active material layer is arranged in the accommodating cavity and comprises solid-liquid mixed active materials. According to the embodiment of the application, the cycle performance and the energy density of the battery monomer can be effectively improved.

Description

Pole piece, electrode assembly, battery cell, battery module and power utilization device

Technical Field

The application relates to the technical field of batteries, in particular to a pole piece, an electrode assembly, a battery cell, a battery module and an electric device.

Background

In recent years, as the application range of the battery is wider and wider, the battery is widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power, solar power stations and the like, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. Among them, the cycle performance and energy density of the battery cells have been one of the key points of the research in the industry.

In order to improve the energy density of the battery cell, one of the currently mainstream technical means is to blend a certain proportion of silicon-based negative electrode material into the graphite negative electrode material of the pole piece in the battery. And because the expansion rate of the silicon-based anode material is higher, the silicon-based anode material is easy to crack and pulverize after undergoing the process of ion embedding or extracting for many times, so that the pole pieces lose effective electric connection, the cycle performance of the battery is poor, and the improvement of the single energy density of the battery is limited. In view of this, improvements in the pole pieces are needed.

Disclosure of Invention

In view of the above, the present application provides a pole piece, an electrode assembly, a battery cell, a battery module and an electric device, which can effectively improve the cycle performance and energy density of the battery cell.

In a first aspect, embodiments of the present application provide a pole piece, where the pole piece includes a current collector, a packaging structure, and an active material layer, where the current collector includes two surfaces that are opposite to each other along a thickness direction of the current collector. The packaging structure is connected to at least one of the two surfaces and forms a containing cavity together with the current collector. The active material layer is arranged in the accommodating cavity and comprises solid-liquid mixed active materials.

In some embodiments of the first aspect, the package structure includes a frame and a separator, the frame being connected between the current collector and the separator.

In some embodiments of the first aspect, the bezel is disposed around an edge of the diaphragm.

In some embodiments of the first aspect, the frame is provided with a reinforcing structure, and the reinforcing structure protrudes from a surface of the frame.

In some embodiments of the first aspect, the reinforcing structure is disposed along a circumferential extension of the bezel.

In some embodiments of the first aspect, the frame is an integrally formed structure with the current collector.

In some embodiments of the first aspect, the thickness d1 of the bezel satisfies: d1 is more than or equal to 40 mu m and less than or equal to 90 mu m, and the thickness d2 of the diaphragm meets the following conditions: d2 is more than or equal to 25 mu m and less than or equal to 50 mu m.

In some embodiments of the first aspect, the active material layer is a silicon-based active material layer.

In a second aspect, embodiments of the present application provide an electrode assembly comprising a pole piece provided in any one of the embodiments of the first aspect.

In a third aspect, embodiments of the present application provide a battery cell including a housing and an electrode assembly provided by an embodiment of the second aspect, the electrode assembly being housed within the housing.

In a fourth aspect, embodiments of the present application provide a battery module, including the battery cell provided in the embodiment of the third aspect.

In a fifth aspect, an embodiment of the present application provides an electrical device, including a battery cell provided in an embodiment of the fourth aspect, where the battery cell is configured to provide electrical energy.

The pole piece, the electrode assembly, the battery monomer, the battery and the power utilization device provided by the application are characterized in that the packaging structure is arranged in the pole piece and connected to at least one of two surfaces which are opposite to each other in the thickness direction of the pole piece, and the packaging structure and the current collector form a containing cavity together. The active material layer is disposed in the accommodating chamber, and the active material layer includes a solid-liquid mixed active material. Wherein the active material in the active material layer and the conductive agent are dispersed in the fluid, and the conductive agent forms a dynamic conductive network in the fluid and the active material is electrically connected. After the battery circulates for many times, the active material can still be effectively and electrically connected with a dynamic conductive network formed by the conductive agent in the fluid even if the active material is broken and pulverized due to expansion, so that the circulation performance of the battery can be effectively improved. In addition, the problem that the active material loses effective electrical connection due to expansion of the active material is solved, so that the upper limit of the adding proportion of the active material in the pole piece can be greatly increased, and the energy density of the battery cell can be effectively improved.

The foregoing description is only an overview of the technical solutions of the present application, and may be implemented according to the content of the specification in order to make the technical means of the present application more clearly understood, and in order to make the above-mentioned and other objects, features and advantages of the present application more clearly understood, the following detailed description of the present application will be given.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

fig. 1 is a schematic diagram of a current collector and packaging structure of a pole piece according to some embodiments of the present application;

fig. 2 is a schematic structural diagram of a current collector and packaging structure of a pole piece according to some embodiments of the present disclosure;

FIG. 3 is a schematic illustration of a pole piece according to some embodiments of the present disclosure;

FIG. 4 is a schematic view of a first view angle structure of another pole piece according to some embodiments of the present application;

fig. 5 is a schematic view of a second view structure of another pole piece according to some embodiments of the present application.

Reference numerals in the specific embodiments are as follows:

10. a current collector; 20. a package structure; 21. a frame; 22. a diaphragm; 30. a receiving chamber; 40. an active material layer; 50. reinforcing structure.

Detailed Description

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection of the present application.

It should be noted that unless otherwise indicated, technical or scientific terms used in the embodiments of the present application should be given the ordinary meanings as understood by those skilled in the art to which the embodiments of the present application belong.

In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom".

The references to the orientation or positional relationship of "inner", "outer", "clockwise", "counter-clockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience in describing the embodiments of the present application and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the embodiments of the present application.

Furthermore, the technical terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or be integrated; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of embodiments of the present application, unless explicitly specified and limited otherwise, a first feature "up" or "down" on a second feature may be that the first and second features are in direct contact, or that the first and second features are in indirect contact via an intermediary. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In recent years, as the application range of the battery is wider and wider, the battery is widely applied to energy storage power supply systems such as hydraulic power, firepower, wind power, solar power stations and the like, and a plurality of fields such as electric tools, electric bicycles, electric motorcycles, electric automobiles, military equipment, aerospace and the like. Among them, the cycle performance and energy density of the battery have been one of the key points of the research in the industry.

In order to improve the energy density of a battery, one of the currently mainstream technical means is to blend a certain proportion of silicon-based negative electrode material into the graphite negative electrode material of a pole piece in the battery. The inventor of the application notes that the silicon-based anode material has higher expansion rate, and is easy to crack and pulverize after undergoing the process of ion embedding or extracting for many times, so that the pole pieces lose effective electric connection, the cycle performance of the battery is poor, and the improvement of the energy density of the battery is limited.

The inventor of the application researches and discovers that the packaging structure can be arranged in the pole piece and connected to at least one surface of two surfaces opposite to each other in the thickness direction of the pole piece, and the packaging structure and the current collector form a containing cavity together. The active material layer is disposed in the accommodating chamber, and the active material layer includes a solid-liquid mixed active material. Wherein the active material in the active material layer and the conductive agent are dispersed in the fluid, and the conductive agent forms a dynamic conductive network in the fluid and the active material is electrically connected. After the battery circulates for many times, the active material can still be effectively and electrically connected with a dynamic conductive network formed by the conductive agent in the fluid even if the active material is broken and pulverized due to expansion, so that the circulation performance of the battery can be effectively improved. In addition, the problem that the active material loses effective electrical connection due to expansion of the active material is solved, so that the upper limit of the adding proportion of the active material in the pole piece can be greatly increased, and the energy density of the battery cell can be effectively improved.

In order to solve the problems in the prior art, the embodiment of the application provides a pole piece, an electrode assembly, a battery monomer, a battery and an electricity utilization device, and the cycle performance and the energy density of the battery monomer can be effectively improved. The pole piece provided in the embodiment of the present application will be described first.

Fig. 1 is a schematic diagram of a current collector and packaging structure of a pole piece according to some embodiments of the present application. Fig. 2 is a schematic structural diagram of a current collector and packaging structure of a pole piece according to some embodiments of the present application. Fig. 3 is a schematic structural diagram of a pole piece according to some embodiments of the present application.

As shown in fig. 1 and 3, the present embodiment provides a pole piece, which includes a current collector 10, a package structure 20, and an active material layer 40, and the current collector 10 includes two surfaces opposite to each other in a thickness direction thereof. The package structure 20 is connected to at least one of the two surfaces, and forms a receiving cavity 30 together with the current collector 10. The active material layer 40 is disposed in the accommodating chamber 30, and the active material layer 40 includes a solid-liquid mixed active material.

The positive plate comprises a positive plate and a negative plate, and takes a lithium ion battery as an example, the material of the current collector 10 in the positive plate can be aluminum, and the active substance can be lithium cobaltate, lithium iron phosphate, ternary lithium or lithium manganate and the like; the material of the current collector 10 in the negative electrode sheet may be copper, and the active material may be carbon, silicon, or the like. In order to more clearly describe the embodiments of the present application, the present application will be described by taking the negative electrode sheet and the active material as silicon-based active materials as examples.

Illustratively, the package structure 20 may be a cover structure, and the package structure 20 may be connected to one of two surfaces of the current collector 10 opposite to each other in the thickness direction thereof, and form a receiving cavity 30 together with the current collector 10; or may be connected to two surfaces of the current collector 10 opposite to each other in the thickness direction thereof, and form two accommodating chambers 30 together with the current collector 10. The accommodating chamber 30 is for accommodating an active substance.

In some alternative embodiments, the active material layer 40 may be a silicon-based active material layer including an active material, a solvent, and a conductive agent, wherein the solvent may be deionized water, or the like; the active material may be, but is not limited to, silicon alloys, silicon oxides, silicon carbon composites, silicon carbon oxides, and the like; the conductive agent may be, but is not limited to, conductive carbon black, carbon nanotubes, graphene, and the like.

In some alternative embodiments, the silicon-based active material layer may further include a binder and a thickener, the binder may be, but is not limited to, styrene butadiene elastomers, and aqueous dispersions of acrylonitrile copolymers, etc.; the thickener may be carboxymethyl cellulose or the like.

In some alternative embodiments, the silicon-based active material layer includes a dispersion matrix and an active material, wherein the active material is blended in the dispersion matrix, which may be graphite or the like, and the active material may be, but is not limited to, silicon alloys, silicon oxides, or the like.

In the embodiment of the present application, the active material layer 40 includes a solid-liquid mixed active material filled in the accommodating chamber 30. Wherein the active material in the active material layer 40 and the conductive agent are dispersed in the fluid, the conductive agent forms a dynamic conductive network in the fluid and the active material remains electrically connected. After the battery circulates for many times, the active material can still be effectively and electrically connected with a dynamic conductive network formed by the conductive agent in the fluid even if the active material is broken and pulverized due to expansion, so that the circulation performance of the battery can be effectively improved. In addition, the problem that the active material loses effective electrical connection due to expansion of the active material is solved, so that the upper limit of the adding proportion of the active material in the pole piece can be greatly increased, and the energy density of the battery cell can be effectively improved.

In the above technical solution, by arranging the packaging structure 20 in the pole piece, the packaging structure 20 is connected to at least one of two surfaces opposite to each other in the thickness direction of the pole piece, and forms the accommodating cavity 30 together with the current collector 10. The active material layer 40 includes a solid-liquid mixed active material, and the solid-liquid mixed active material is disposed in the accommodating cavity 30, so that the active material can be always and effectively electrically connected with a dynamic conductive network formed by the conductive agent in the fluid in the process of battery circulation, and further, the circulation performance of the battery monomer can be effectively improved and the energy density of the battery monomer can be improved.

In some embodiments, the package structure 20 includes a frame 21 and a separator 22, the frame 21 being connected between the current collector 10 and the separator 22.

Alternatively, the frame 21 may be a rectangular frame having a closed structure, and the frame 21 may be made of a metal material, such as copper, or a non-metal material, such as polyethylene or polypropylene. The separator 22 has a plurality of through micropores, can ensure free passage of electrolyte ions, and has good penetrability to lithium ions. The material of the separator 22 may be PP (polypropylene) or PE (polyethylene).

Illustratively, frame 21 is connected to at least one of two surfaces of current collector 10 that are opposite in the thickness direction thereof. Alternatively, the number of the frames 21 may be one, and one frame 21 is connected to one of two surfaces of the current collector 10 opposite to each other in the thickness direction thereof; the number of the frames 21 may be two, and the two frames 21 are respectively connected to two surfaces of the current collector 10 opposite to each other in the thickness direction thereof. The frame 21 and the current collector 10 together form the accommodating cavity 30, and the frame 21 and the current collector 10 may be connected by, but not limited to, welding or bonding. The separator 22 is attached to a side of the frame 21 facing away from the current collector 10 to encapsulate the accommodating chamber 30.

In the above technical solution, by arranging the packaging structure 20 in a form of connecting the frame 21 and the diaphragm 22, in the manufacturing process of the pole piece, the frame 21 and the current collector 10 can be connected to form the accommodating cavity 30, then the active material slurry is injected into the accommodating cavity 30, and finally the diaphragm 22 and the frame 21 are connected to encapsulate the accommodating cavity 30 and the active material slurry in the accommodating cavity 30. Simplifying the manufacturing mode of the pole piece and being beneficial to improving the yield.

In some embodiments, the rim 21 surrounds the edge of the septum 22.

Illustratively, the front projection of the current collector 10 covers the front projection of the separator 22 and the front projection of the frame 21 in the thickness direction of the pole piece, that is, the front projection area of the current collector 10 is larger than the front projection area of the package structure 20 in the thickness direction of the pole piece. The active material layer 40 is disposed in the accommodating cavity 30 of the package structure 20, that is, along the thickness direction of the pole piece, the orthographic projection area of the current collector 10 is larger than the orthographic projection area of the active material layer 40, and the portion of the current collector 10 where the active material layer 40 is not disposed may form a tab.

In the above technical scheme, the frame 21 extends and distributes along the edge of the diaphragm 22, so that the orthographic projection area of the accommodating cavity 30 on the current collector 10 is maximized, the volume of the accommodating cavity 30 is larger, more active substances can be accommodated, and the energy density of the battery cell can be further improved.

Fig. 4 is a schematic view of a first view structure of another pole piece according to some embodiments of the present application. Fig. 5 is a schematic view of a second view structure of another pole piece according to some embodiments of the present application.

With continued reference to fig. 4-5, in some embodiments, a reinforcing structure 50 is disposed on the frame 21, and the reinforcing structure 50 protrudes from the surface of the frame 21.

Illustratively, the reinforcing structure 50 may be a surface protruding from a side of the frame 21 close to the accommodating cavity 30, a surface protruding from a side of the frame 21 away from the accommodating cavity 30, or a surface protruding from a side of the frame 21 close to the accommodating cavity 30, or a surface protruding from a side of the frame 21 away from the accommodating cavity 30. Alternatively, the reinforcing structure 50 may be a reinforcing rib or a solid bump or the like.

In some alternative embodiments, the reinforcing structure 50 is disposed to protrude from the surface of the side of the frame 21 facing away from the accommodating cavity 30, so that the reinforcing structure 50 can be prevented from occupying the space of the accommodating cavity 30, so as not to affect the energy density of the battery cell.

In the above technical scheme, the reinforcing structure 50 is arranged on the frame 21, so that the frame 21 has a concave-convex structure, the structural strength of the frame 21 can be effectively improved, and the reliability of the pole piece is further improved.

In some alternative embodiments, reinforcing structure 50 is an integral structure with bezel 21. The frame 21 integrally forms the reinforcing structure 50 through a stamping process, so that the reinforcing structure 50 and the frame 21 are in an integrated structure, on one hand, the reinforcing structure 50 and the frame 21 are not required to be connected through additional welding or bonding and other connecting processes, and the manufacturing process flow of the reinforcing structure 50 is simplified. Meanwhile, compared with the connection between the reinforcing structure 50 and the frame 21 through a welding or bonding process, the reinforcing structure 50 and the frame 21 in an integrated structure have higher connection firmness.

In some embodiments, reinforcing structure 50 is disposed along a circumferential extension of bezel 21.

Illustratively, the reinforcing structure 50 extends along the circumferential direction of the frame 21, that is, the extending length of the reinforcing structure 50 is consistent with the circumferential length of the frame 21, so that the structural strength of the frame 21 can be improved to the greatest extent, and the reliability of the pole piece is further improved.

In some embodiments, frame 21 is an integrally formed structure with current collector 10.

The current collector 10 integrally forms the frame 21 through a stamping process, so that the frame 21 and the current collector 10 are in an integrated structure, on one hand, the frame 21 and the current collector 10 are not required to be connected through additional welding or bonding and other connecting processes, and the manufacturing process flow of the frame 21 is simplified. Meanwhile, compared with the connection of the frame 21 and the current collector 10 through a connection process such as welding or bonding, the frame 21 and the current collector 10 which are in an integrated structure have higher connection firmness.

In some embodiments, the thickness d1 of the bezel 21 satisfies: d1 is 40 μm or less and 90 μm or less, and the thickness d2 of the diaphragm 22 satisfies: d2 is more than or equal to 25 mu m and less than or equal to 50 mu m.

In this embodiment, the thickness d1 of the frame 21 may be understood as a distance between a side surface of the frame 21 close to the accommodating cavity and a side surface of the frame 21 away from the accommodating cavity, and the thickness d2 of the diaphragm 22 is the thickness of the diaphragm 22 itself.

By way of example, the thickness d1 of the rim 21 may be, but is not limited to, 45 μm, 50 μm, 55 μm, 60 μm, 80 μm, 85 μm. The thickness d2 of the diaphragm 22 may be, but is not limited to, 30 μm, 35 μm, 40 μm, 45 μm, 48 μm.

In the above-described embodiments, the thickness d1 of the frame 21 and the thickness d2 of the diaphragm 22 are set within the above-described ranges, so that the structural strength of the entire package structure 20 can be further improved.

According to some embodiments of the present application, there is also provided an electrode assembly comprising a pole piece of any of the above aspects.

The electrode assembly is mainly formed by winding or stacking a positive electrode sheet and a negative electrode sheet, and a separator is generally provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having the active material constitute the main body portion of the electrode assembly, and the portions of the positive electrode sheet and the negative electrode sheet having no active material constitute the tabs, respectively. The positive electrode tab and the negative electrode tab may be located at one end of the main body portion together or located at two ends of the main body portion respectively. During charge and discharge of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tab is connected with the electrode terminal to form a current loop.

According to some embodiments of the present application, there is also provided a battery cell including a case and an electrode assembly of the above aspects, the electrode assembly being accommodated in the case.

The battery cell provided by the embodiment of the application comprises an electrode assembly and a shell, wherein the electrode assembly is accommodated in the shell. The housing may also be used to contain an electrolyte, such as an electrolyte solution.

The housing may be of various shapes, such as a cylinder, a rectangular parallelepiped, etc. The shape of the case may be determined according to the specific shape of the electrode assembly. For example, if the electrode assembly is a cylindrical structure, a cylindrical case may be selected; if the electrode assembly is of a rectangular parallelepiped configuration, a rectangular parallelepiped housing may be selected.

In the battery cell, the electrode assemblies accommodated in the case may be one, two, or more.

According to some embodiments of the present application, the present application further provides a battery module, including the battery cell of the above scheme.

The battery module according to the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. The battery module generally includes a case for enclosing one or more battery cells. The case body can prevent liquid or other foreign matters from affecting the charge or discharge of the battery cells.

The plurality of battery cells in the battery module can be electrically connected through the converging component so as to realize parallel connection, serial connection or series-parallel connection of the plurality of battery cells in the battery module.

According to some embodiments of the present application, there is further provided an electrical device including the battery cell according to the above scheme, where the battery cell is used to provide electrical energy.

The electric device may be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, or the like. The vehicle can be a fuel oil vehicle, a fuel gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle; spacecraft including airplanes, rockets, space planes, spacecraft, and the like; the electric toy includes fixed or mobile electric toys, such as a game machine, an electric car toy, an electric ship toy, and an electric airplane toy; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railroad power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete shakers, and electric planers, among others. The embodiment of the application does not limit the electric device in particular.

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the embodiments, and are intended to be included within the scope of the claims and description. In particular, the technical features mentioned in the respective embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions falling within the scope of the claims.

Claims (12)

1. A pole piece, comprising:

the current collector comprises two surfaces which are opposite in the thickness direction of the current collector;

a packaging structure connected to at least one of the two surfaces and forming a containing cavity together with the current collector;

the active material layer is arranged in the accommodating cavity and comprises solid-liquid mixed active materials.

2. The pole piece of claim 1, wherein the packaging structure includes a frame and a diaphragm, the frame being connected between the current collector and the diaphragm.

3. The pole piece of claim 2, wherein the rim is located around an edge of the diaphragm.

4. The pole piece of claim 2, wherein the frame is provided with a reinforcing structure protruding from a surface of the frame.

5. The pole piece of claim 4, wherein the reinforcing structure extends circumferentially along the rim.

6. The pole piece of claim 2, wherein the frame is of unitary construction with the current collector.

7. The pole piece of claim 2, wherein the thickness d1 of the rim satisfies: d1 is more than or equal to 40 mu m and less than or equal to 90 mu m, and the thickness d2 of the diaphragm meets the following conditions: d2 is more than or equal to 25 mu m and less than or equal to 50 mu m.

8. The pole piece of claim 1, wherein the active material layer is a silicon-based active material layer.

9. An electrode assembly comprising a pole piece according to any one of claims 1 to 8.

10. A battery cell comprising a housing and the electrode assembly of claim 9, wherein the electrode assembly is contained within the housing.

11. A battery module comprising a plurality of the battery cells of claim 10.

12. An electrical device comprising the battery cell of claim 10 for providing electrical energy.