Pole piece and manufacturing method, electrode assembly, battery cell, battery and electrical device

Abstract

The present application relates to a pole piece and a manufacturing method, an electrode assembly, a battery cell, a battery and an electrical device, including a current collecting substrate and an active layer, wherein the active layer is arranged on at least one side of the current collecting substrate along its own thickness direction, and the active layer has a first coating area and a second coating area arranged in parallel along a first direction, wherein the effective energy density of the active layer in the first coating area is not equal to the effective energy density of the active layer in the second coating area, and the pole piece is wound along a second direction intersecting with the first direction. In this way, an active layer with uneven effective energy density is formed in the first direction, and the first coating area and the second coating area with different effective energy densities form a rebound difference, so as to avoid the pole piece from forming through wrinkled stripes during the battery charging and discharging process.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a pole piece and a manufacturing method, an electrode assembly, a battery cell, a battery and an electrical device. Background Art

[0002] Energy conservation and emission reduction are the key to the sustainable development of the automobile industry. Electric vehicles have become an important part of the sustainable development of the automobile industry due to their advantages in energy conservation and environmental protection. For electric vehicles, battery technology is an important factor in their development.

[0003] As the demand for battery cell energy density increases, using cathodes and anodes with high specific energy in batteries is an important means to increase energy density, thereby forming high-energy batteries.

[0004] However, during the charging and discharging process of the battery, due to the high elasticity of the high-energy cathode and anode electrodes, it is easy to cause the electrodes to be penetrated and wrinkled in a certain direction, affecting the quality of the battery. Summary of the invention

[0005] In view of the above problems, the present application provides a pole piece and a manufacturing method, an electrode assembly, a battery cell, a battery and an electrical device, which can alleviate problems such as pole piece penetration and wrinkling generated during the battery charging and discharging process.

[0006] In the first aspect, the present application provides a pole piece, including a current collecting substrate and an active layer, wherein the active layer is arranged on at least one side of the current collecting substrate along its own thickness direction, and the active layer has a first coating area and a second coating area arranged in parallel along a first direction, wherein the effective energy density of the active layer in the first coating area is not equal to the effective energy density of the active layer in the second coating area.

[0007] In the technical solution of the embodiment of the present application, a rebound difference is formed between the first coating area and the second coating area with different effective energy densities, which can avoid the phenomenon of through wrinkles on the cathode electrode sheet or the anode electrode sheet wound in the battery cell during the battery charging and discharging process.

[0008] In some embodiments, the thickness of the active layer in the first coating area is different from the thickness of the active layer in the second coating area, and the height difference in thickness is convenient to measure. The present application increases or decreases the thickness of the active layer in the first coating area, and increases or decreases the effective energy density of the active layer in the first coating area, so that the operation is simple.

[0009] In some embodiments, when the polarity of the electrode is anode, the thickness of the active layer in the first coating area is greater than the thickness of the active layer in the second coating area. By increasing the thickness of the anode active layer of the anode electrode, the probability of lithium ions being embedded in the anode active layer is increased, thereby slowing down the release of lithium.

[0010] In some embodiments, the difference between the thickness of the active layer in the first coating area and the thickness of the active layer in the second coating area is 3um-150um, so as to avoid the active layer being too thin or too thick, thereby causing insufficient energy density or energy waste.

[0011] In some embodiments, the difference between the thickness of the active layer in the first coating area and the thickness of the active layer in the second coating area is 3um-25um. Within the optional range, it can not only play the role of preventing the electrode sheet from being penetrated and wrinkled in this case, but also minimize the loss of battery energy density.

[0012] In some embodiments, when the polarity of the electrode is cathode, the thickness of the active layer in the first coating area is less than the thickness of the active layer in the second coating area. By thinning the thickness of the cathode active layer of the cathode electrode, the lithium ions deintercalated from the cathode active layer are reduced, thereby slowing down the release of lithium.

[0013] In some embodiments, the difference between the thickness of the active layer in the second coating area and the thickness of the active layer in the first coating area is 3um-150um, so as to avoid the active layer being too thin or too thick, thereby causing insufficient energy density or energy waste.

[0014] In some embodiments, the difference between the thickness of the active layer in the second coating area and the thickness of the active layer in the first coating area is 5um-20um. Within the optional range, it can not only play the role of preventing the polar sheet from being penetrated and wrinkled in this case, but also minimize the loss of battery energy density.

[0015] In some embodiments, when the polarity of the electrode is cathode, the surface of the active layer in the first coating area is covered with an insulating layer, and an active layer with uneven effective energy density is formed in the first direction by reducing the energy density of the active layer in the first coating area of ​​the cathode electrode.

[0016] In some embodiments, at least two ends of a portion of the first coating area extend to opposite ends of the current collecting substrate along the second direction, and the second direction is perpendicular to the first direction. In this way, the first coating area is ensured to block the through wrinkling lines generated at any position of the electrode sheet along the first direction, thereby alleviating the problems of battery performance degradation and cycle life shortening caused by through wrinkling that affect battery quality.

[0017] In some embodiments, the active layer further has a third coating area extending along the first direction, the third coating area intersects with at least one first coating area, and the effective energy density of the active layer in the third coating area is different from the effective energy density of the active layer in the second coating area. By providing the third coating area, the wrinkled lines generated on the pole piece can be blocked in multiple directions, thereby further enhancing the anti-wrinkling effect of the pole piece.

[0018] In some embodiments, the first coating area and the third coating area are jointly constructed to form a grid structure, which can better ensure that the pole piece is prevented from being penetrated and wrinkled, and makes the pole piece easy to process.

[0019] In the second aspect, the present application provides a method for manufacturing a pole piece, specifically comprising the following steps: providing a pole piece body, wherein the pole piece body comprises a current collecting substrate and an active body disposed on at least one side of the current collecting substrate; coating an active material on a first coating area of ​​the active body, removing at least part of the active material, or attaching an insulating layer, so that the effective energy density of the active layer in the first coating area is different from the effective energy density of the active layer in the second coating area of ​​the active body. The first coating area and the second coating area are arranged side by side along a first direction.

[0020] In a second aspect, the present application provides an electrode assembly, including a cathode electrode piece, an anode electrode piece, and an isolating member separating the cathode electrode piece and the anode electrode piece, wherein the cathode electrode piece and / or the anode electrode piece are the electrode pieces described in any of the above embodiments.

[0021] In a third aspect, the present application provides a battery cell, comprising a shell and an electrode assembly accommodated in the shell.

[0022] In a fourth aspect, the present application provides a battery, which includes the battery cell in the above embodiment.

[0023] In a fifth aspect, the present application provides an electrical device, which includes the battery in the above embodiment, and the battery is used to provide electrical energy.

[0024] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0026] Figure 1 A schematic diagram of the composition of a vehicle in an embodiment of the present application;

[0027] Figure 2 is an exploded schematic diagram of a battery in one embodiment of the present application;

[0028] Figure 3 is an exploded schematic diagram of a battery cell in an embodiment of the present application;

[0029] Figure 4 It is a schematic diagram of the structure of a pole piece in one embodiment of the present application;

[0030] Figure 5 It is a schematic structural diagram of a pole piece in another embodiment of the present application;

[0031] Figure 6 It is a schematic structural diagram of a pole piece in another embodiment of the present application;

[0032] Figure 7 It is a schematic structural diagram of a pole piece in another embodiment of the present application;

[0033] Figure 8 It is a schematic structural diagram of a pole piece in another embodiment of the present application;

[0034] Fig. 9 It is a schematic diagram of the structure of a pole piece in another embodiment of the present application.

[0035] The reference numerals in the specific implementation manner are as follows:

[0036] 1000, vehicle; 100, battery; 200, controller; 300, motor; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, end cap; 22, shell; 23, electrode assembly; 24, pole piece; 241, current collecting substrate; f1, first coating area; f2, second coating area; f3, third coating area; 243, pole ear; 245, active layer; F, thickness direction; Y, first direction; Z, second direction. DETAILED DESCRIPTION

[0037] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0039] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0040] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0042] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0043] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0044] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0045] At present, from the perspective of market development, the application of power batteries is becoming more and more extensive. Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.

[0046] As a battery with higher specific energy, high-energy battery has the advantages of durability and high power supply, and is an important development direction of power batteries. The inventors have noticed that during the charging and discharging process of high-energy batteries, that is, the process in which lithium ions are deintercalated from the cathode and cannot be smoothly embedded in the anode, the high-specific energy cathode electrode sheet and anode electrode sheet of the high-energy battery have high elasticity, which can easily cause the electrode sheet to be through-wrinkled in a certain direction. For example, the anode electrode sheet or the cathode electrode sheet can easily produce through-wrinkled lines along the axial direction of the wound battery cell, thereby causing problems affecting the battery quality such as decreased battery performance and shortened cycle life.

[0047] If the anode or cathode electrode has through wrinkles in a certain direction, it will cause irreversible damage to the electrode, thus causing irreversible impact on the quality of the battery. However, non-through wrinkles can gradually disappear through the electrode's own elasticity and expansion force, thus returning to normal.

[0048] In order to solve the problem of electrode through wrinkling generated during the charge and discharge process of high-energy batteries, the applicant has found that the formation of through wrinkled lines on the electrode is mainly due to the same energy density of the active layer coated on the surface of the electrode, which leads to the through wrinkling conditions (that is, the rebound differences at various positions of the active layer are the same). It can be considered from the perspective of the coating position or coating amount of the active material, and the energy density of the electrode in the direction of the wrinkled lines can be changed to form a discontinuous (that is, uneven energy density) active layer coating surface. The rebound difference between each area due to the uneven energy density makes it impossible to form through wrinkled stripes, thereby blocking the through wrinkling of the electrode in a certain direction.

[0049] To form a discontinuous (ie, non-uniform energy density) active layer coating surface, specifically, the energy density of the local active layer may be reduced or the energy density of the local active layer may be increased.

[0050] Based on the above considerations, in order to alleviate the impact of through-wrinkling on the surface of the cathode electrode or the anode electrode on the battery quality (performance and life), the inventors have designed a electrode after in-depth research. The active layer is constructed into two different coating areas, which are arranged side by side along a set direction, and the effective energy thickness of the active layer in each coating area is different, thereby reducing or increasing the effective active material content in the local area of ​​the active layer, thereby blocking the through-wrinkling lines generated at any position of the electrode along the set direction, and alleviating the problems of battery quality such as battery performance degradation and shortened cycle life caused by through-wrinkling of the electrode.

[0051] The pole piece disclosed in the embodiment of the present application can be used to make a cathode or an anode. The pole piece provided in the embodiment of the present application can be used to coat a lithium-based active slurry to form a pole piece for a lithium battery, but the active layer coated on the pole piece is not limited to a lithium-based active layer, and a lead-based active layer, a nickel-based active layer, a zinc-based active layer, etc. can also be coated to make other types of pole pieces.

[0052] The pole piece disclosed in the embodiment of the present application can be used to make a pole piece. Since the effective energy density of the active layer of the pole piece is not equal along the set direction, the content of the active material in the active layer in the local area increases or decreases, which can alleviate the phenomenon of through-wrinkling lines formed on the pole piece along the set direction. The battery cell made using the pole piece disclosed in the embodiment of the present application can be used in electrical devices such as vehicles, ships or aircraft, but is not limited to it. A power supply system comprising the battery cell, battery, etc. disclosed in the present application can be used to form the electrical device, which is conducive to alleviating battery lithium deposition and improving battery performance and battery life.

[0053] The embodiment of the present application provides an electric device using a battery as a power source, and the electric device may be, but is not limited to, a mobile phone, a tablet, a laptop, an electric toy, an electric tool, a battery car, an electric car, a ship, a spacecraft, etc. Among them, the electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc., and the spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0054] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0055] Please refer to Figure 1 , Figure 1A schematic diagram of the structure of a vehicle 1000 provided for some embodiments of the present application. The vehicle 1000 may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 may be provided at the bottom, head or tail of the vehicle 1000. The battery 100 may be used to power the vehicle 1000, for example, the battery 100 may be used as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300, and the controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0056] In some embodiments of the present application, the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0057] Please refer to Figure 2 , Figure 2 An exploded view of a battery 100 provided in some embodiments of the present application. The battery 100 includes a box 10 and a battery cell 20, and the battery cell 20 is contained in the box 10. Among them, the box 10 is used to provide a storage space for the battery cell 20, and the box 10 can adopt a variety of structures. In some embodiments, the box 10 may include a first part 11 and a second part 12, the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20. The second part 12 may be a hollow structure with one end open, the first part 11 may be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12. Of course, the box 10 formed by the first part 11 and the second part 12 may be in a variety of shapes, such as a cylinder, a cuboid, etc.

[0058] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection. A mixed connection means that the multiple battery cells 20 are both connected in series and in parallel. The multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10. The battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.

[0059] Each battery cell 20 may be a secondary battery or a primary battery, or a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0060] Please refer to Figure 3 , Figure 3 The schematic diagram of the exploded structure of the battery cell 20 provided in some embodiments of the present application. The battery cell 20 refers to the smallest unit that constitutes the battery. Figure 3 The battery cell 20 includes an end cover 21, a shell 22, an electrode assembly 23 and other functional components.

[0061] The end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved. Functional components such as electrode terminals can be provided on the end cap 21. The electrode terminal can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy of the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this. In some embodiments, an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be plastic, rubber, or the like.

[0062] The shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte and other components. The shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening. Without limitation, the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22. The shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23. The material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0063] The electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur. One or more electrode assemblies 23 may be included in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking an anode electrode sheet and a cathode electrode sheet, and a diaphragm is usually provided between the anode electrode sheet and the cathode electrode sheet. The portions of the anode electrode sheet and the cathode electrode sheet with active materials constitute the main body of the electrode assembly, and the portions of the anode electrode sheet and the cathode electrode sheet without active materials each constitute a tab. The anode tab and the cathode tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the anode active material and the cathode active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.

[0064] According to some embodiments of this application, please refer to Figures 4 to 6 The pole piece 24 provided in the present application includes a current collecting substrate 241 and an active layer 245. The active layer 245 is arranged on at least one side of the current collecting substrate 241 along its own thickness direction F. The active layer 245 has a first coating area f1 and a second coating area f2 arranged in parallel along a first direction Y, wherein the effective energy density of the active layer 245 in the first coating area f1 is different from the effective energy density of the active layer 245 in the second coating area f2.

[0065] The current collecting substrate 241 has a conductive current collecting function and can be made of copper foil, aluminum foil, etc. Specifically, when the pole piece 24 is made of copper foil, it can be used to prepare an anode pole piece, and when the pole piece 24 is made of aluminum foil, it can be used to prepare a cathode pole piece.

[0066] The current collecting substrate 241 may be covered with active layers 245 on both sides in the thickness direction F, or may be covered with active layers 245 on only one side in the thickness direction F and not on the other side, in which case it can be used to manufacture a unipolar pole piece 24 .

[0067] The active layer 245 is formed by coating the anode active material or the cathode active material on the side of the current collecting substrate 241 by coating, cold pressing, etc. For example, a certain proportion of carbon black and a certain proportion of a binder are uniformly mixed in a certain medium to form an active layer 245 with cathode polarity or an active layer 245 with anode polarity.

[0068] Energy density refers to the amount of electrical energy stored in a certain space or mass of material. The energy density of the active layer 245 is a reflection of the electrical energy capacity released per unit volume or mass of the active layer 245, which is directly related to the amount of active material per unit volume of the active layer 245. The more active material per unit volume, the greater the energy density of the active layer 245, and the more electricity stored per unit volume.

[0069] The effective energy density refers to the energy density of active materials that can only generate free lithium ions or receive free lithium ions to participate in the charging and discharging process. It can be understood that active materials coated on the surface of the current collecting substrate 241 but inactive and unable to participate in the charging and discharging process are not included in the effective energy density range.

[0070] The first direction is Y, Figure 4 In the direction F indicated by the arrow, the pole piece 24 can be wound along a second direction Z intersecting with the first direction Y. The second direction Z, i.e. Figure 5 The arrow in the middle shows the Z direction, as Figure 6 As shown, the pole piece 24 is wound along the second direction Z to form a wound battery cell, and the pole ear 243 arranged at one end of the pole piece 24 in the first direction Y is protruding. At this time, the first direction Y is finally transformed into the axial direction of the wound battery cell.

[0071] In this way, by setting the effective energy densities of the first coating area f1 and the second coating area f2 in the first direction Y to be unequal, an active layer 245 with uneven effective energy density is formed in the first direction Y, thereby forming a rebound difference between the first coating area f1 and the second coating area f2 with different effective energy densities. During the charging and discharging process of the battery 100, the through wrinkles generated by the electrode sheet 24 are blocked, thereby avoiding the phenomenon of through wrinkles generated by the cathode electrode sheet or the anode electrode sheet wound in the battery cell 100.

[0072] In the embodiment of the present application, the first coating area f1 is used as a region for changing the effective energy density of the active layer 245 to alleviate the through wrinkling, and the second coating area f2 is used as a region where the active layer 245 is coated at a normal energy density.

[0073] It can be understood that during the charge and discharge process of the battery 100, when the electrode 24 forms through wrinkles and damages the surface structure of the electrode 24, there will be a lithium precipitation phenomenon, that is, lithium ions are deintercalated from the cathode and cannot be smoothly embedded in the anode. The lithium ions can only be precipitated on the surface of the anode to form a layer of gray substance, which will cause the performance of the battery 100 to be reduced, the cycle life to be shortened, and other hazards.

[0074] In order to alleviate the problem of lithium deposition caused by the formation of through wrinkles on the electrode sheet 24, the applicant has found that lithium deposition is mainly caused by the fact that lithium ions released from the cathode electrode sheet cannot be smoothly embedded in the anode electrode sheet 24 and are deposited on the surface of the anode electrode sheet. The probability of lithium ions released from the cathode electrode sheet being embedded in the anode electrode sheet can be increased by reducing the amount of lithium ions generated by the cathode electrode sheet or increasing the embedded volume of the anode electrode sheet.

[0075] Specifically, in combination with the above description, reducing the amount of cathode active material coverage is to reduce the effective energy density of the first coating area f1 of the active layer 245 of the cathode electrode, and increasing the amount of anode active material coverage is to increase the effective energy density of the active layer 245 of the anode electrode, thereby avoiding lithium deposition of the electrode 24.

[0076] In some embodiments, optionally, the thickness of the active layer 245 in the first coating region f1 is different from the thickness of the active layer 245 in the second coating region f2.

[0077] In actual operation, along the first direction Y, the thickness of the active layer 245 in the first coating area f1 is different from the thickness of the active layer 245 in the second coating area f2, that is, along the thickness direction F of the current collecting substrate 241, the heights of the active layer 245 in the first coating area f1 and the second coating area f2 in the thickness direction F of the current collecting substrate 241 are different. Among them, the first coating area f1 and the second coating area f2 can both be planes with the same height everywhere in the thickness direction F or curved surfaces with different heights everywhere, as long as the first coating area f1 is higher or lower than the second coating area f2 as a whole in the thickness direction F.

[0078] The height difference of thickness is convenient to measure. The present application increases or decreases the thickness of the active layer 245 in the first coating area f1 to increase or decrease the effective energy density of the active layer 245 in the first coating area f1, thereby simplifying the operation.

[0079] Furthermore, if during the charge and discharge process of the battery 100, due to the above-mentioned setting, the electrode 24 produces non-penetrating wrinkles along the first direction Y, at this time, due to the rebound difference between the first coating area f1 and the second coating area f2, an expansion force is generated, thereby gradually restoring the smooth surface and making the non-penetrating wrinkles disappear.

[0080] In some embodiments, optionally, when the polarity of the pole piece 24 is anode, the thickness of the active layer 245 in the first coating area f1 is greater than the thickness of the active layer 245 in the second coating area f2.

[0081] Specifically, when the active layer 245 is an anode active material, the electrode 24 provided in the present application is used to manufacture an electrode 24 with anode polarity, such as Figure 4 The active layer 245 of the second coating area f2 is coated with a standard thickness, and the first coating area f1 is greater in height in the thickness direction F of the current collecting substrate 241 than the second coating area f2. The anode active material coated on the first coating area f1 is thicker, thereby achieving thickening of the active layer 245 in some areas, thereby achieving an increase in the effective density of the active layer 245 in some areas.

[0082] It can be understood that by increasing the thickness of the active layer 245 of the anode electrode, the probability of lithium ions being embedded in the active layer 245 is increased, thereby slowing down the release of lithium.

[0083] In this solution, the active layer 245 coated in the first coating area f1 is arranged to protrude relative to the active layer 245 of the second coating area f2. The cross section of the active layer 245 in the first coating area f1 perpendicular to the thickness direction F of the current collecting substrate 241 can be circular, square, or irregular, and can also be arranged according to the actual assembly shape, without specific limitation. It should be noted that the active layer 245 can be coated on the second coating area f2 by, but not limited to, coating, casting, deposition, etc., and the thickness of the active layer 245 in the first coating area f1 can be increased by coating active materials and other solutions so that the material of the active layer 245 in the corresponding area is increased.

[0084] Specifically in the embodiment, optionally, the difference between the thickness of the active layer 245 in the first coating area f1 and the thickness of the active layer 245 in the second coating area f2 is 3 um-150 um.

[0085] That is, when the pole piece 24 provided in the present application is used to form a pole piece 24 with anode polarity, the difference between the thickness of the active layer 245 in the first coating area f1 and the height of the active layer 245 in the second coating area f2 is 3um-150um, which can ensure that the first coating area f1 can achieve the corresponding function of preventing penetration and wrinkling, and avoid the active layer 245 being too thin or too thick, thereby causing insufficient energy density or energy waste. In addition, by the above range, the active layer 245 is prevented from being too thick, which helps to achieve lightweighting of the battery 100.

[0086] In some embodiments, optionally, the difference between the thickness of the active layer 245 in the first coating region f1 and the thickness of the active layer 245 in the second coating region f2 is 3 um-25 um.

[0087] In the first direction Y, the difference between the thickness of the active layer 245 in the first coating area f1 and the height of the active layer 245 in the second coating area f2 is 3um-25um. Within the optional range, it can not only play the role of wrinkling the anti-polar sheet 24 in this case, but also minimize the loss of energy density of the battery 100.

[0088] In some embodiments, optionally, when the polarity of the pole piece 24 is cathode, the thickness of the active layer 245 in the first coating area f1 is less than the thickness of the active layer 245 in the second coating area f2.

[0089] Specifically, when the active layer 245 is a cathode active material, the electrode 24 provided in the present application is used to make a cathode electrode, such as Figure 5 The cathode polarity active layer 245 of the second coating area f2 is coated according to the standard thickness. The height of the first coating area f1 in the thickness direction F of the current collecting substrate 241 is smaller than that of the second coating area f2. The cathode polarity active layer 245 coated on the first coating area f1 is thinner, thereby achieving thinning of the active layer 245 in some areas, thereby achieving a reduction in the effective density of the active layer 245 in some areas.

[0090] It can be understood that by reducing the thickness of the active layer 245 of the cathode electrode, the lithium ions extracted from the active layer 245 of the cathode are reduced, thereby slowing down the release of lithium.

[0091] In this scheme, the active layer 245 in the first coating area f1 is recessed relative to the active layer 245 in the second coating area f2. The cross-section of the active layer 245 in the first coating area f1 perpendicular to the thickness direction F of the current collecting substrate 241 can be circular, square, irregular, etc., and can also be set according to the actual assembly shape, without specific limitation.

[0092] It should be noted that the active layer 245 can be coated on the second coating area f2 by, but not limited to, coating, casting, deposition, etc., and the thickness of the active layer 245 in the first coating area f1 can be thinned by laser processing, grooving, and other methods to reduce the material of the active layer 245 in the corresponding area.

[0093] Specifically in the embodiment, optionally, the difference between the thickness of the active layer 245 in the second coating area f2 and the thickness of the active layer 245 in the first coating area f1 is 3 um-150 um.

[0094] That is, when the electrode sheet 24 provided in the present application is used to form a cathode electrode sheet, the difference between the thickness of the active layer 245 in the second coating area f2 and the height of the active layer 245 in the first coating area f1 is 3um-150um, which can ensure that the first coating area f1 can achieve the corresponding function of preventing penetration and wrinkling, and avoid the active layer 245 being too thin or too thick, thereby causing insufficient energy density or energy waste. In addition, by the above range, the active layer 245 is prevented from being too thick, which helps to achieve lightweighting of the battery 100.

[0095] In some embodiments, optionally, the difference between the thickness of the active layer 245 in the second coating region f2 and the thickness of the active layer 245 in the first coating region f1 is 5 um-20 um.

[0096] In the first direction Y, the difference between the thickness of the active layer 245 in the second coating area f2 and the height of the active layer 245 in the first coating area f1 is 5um-20um. Within the optional range, it can not only play the role of preventing the polar plate 24 from penetrating and wrinkling in this case, but also minimize the loss of energy density of the battery 100.

[0097] In this way, by setting the thickness of the first coating area f1 and the second coating area f2, an uneven active layer 245 is formed, and then the rebound difference of different areas of the active layer 245 is used to block the penetrating wrinkles generated at any position of the electrode sheet 24 along the first direction Y, thereby avoiding the phenomenon of penetrating wrinkles generated on the cathode electrode sheet or the anode electrode sheet wound in the battery cell 100.

[0098] In some embodiments, optionally, when the polarity of the pole piece 24 is cathode, the surface of the active layer 245 of the first coating region f1 is covered with an insulating layer.

[0099] The insulating layer can be an insulating paint or an insulating glue, which is covered on the surface of the active layer 245 in the first coating area f1, and can insulate or inactivate the active material of the active layer 245 covered thereunder, making it invalid (i.e., it does not participate in the charging and discharging process of the battery 100), thereby reducing the effective energy density of the active layer 245 in the first coating area f1.

[0100] By reducing the energy density of the active layer 245 in the first coating area f1 of the electrode piece 24 with cathode polarity, an active layer 245 with uneven effective energy density is formed in the first direction Y, thereby blocking the through-type wrinkling produced by the electrode piece 24 with cathode polarity. At the same time, the coverage of the active layer 245 with cathode polarity is reduced to avoid lithium deposition.

[0101] In some embodiments, optionally, Figure 6 At least two ends of a portion of the first coating region f1 extend along a second direction Z to two opposite ends of the current collecting substrate 241 , respectively. The second direction Z is perpendicular to the first direction Y.

[0102] Understandably, referring to Figures 6 to 9 The number of the first coating areas f1 can be multiple, and the multiple first coating areas f1 are arranged at intervals along the first direction Y to form multiple first coating areas f1, and the second coating area f2 is between two adjacent first coating areas f1. The shape, size and shape of the first coating area f1 are not limited.

[0103] The first coating area f1 can be continuous or segmented, and can be set as a whole area or multiple areas. It needs to be ensured that a through line drawn from any position of the current collecting substrate 241 along the first direction Y can pass through at least one first coating area f1, so that the two ends of at least one first coating area f1 extend to the opposite ends of the current collecting substrate 241 in the second direction Z, so as to ensure that the first coating area f1 achieves "full coverage" of the current collecting substrate 241 from the second direction Z.

[0104] In this way, the first coating region f1 is ensured to block the through wrinkles generated at any position of the electrode sheet 24 along the first direction Y, thereby alleviating the problems affecting the quality of the battery 100 such as performance degradation and cycle life shortening caused by the through wrinkles.

[0105] In some embodiments, optionally, one side of the pole piece 24 generally forms only a surface of one polarity, and the surface of one polarity only selectively thins or thickens the active layer 245 in the first coating area f1 according to the polarity. In this case, each surface of the pole piece 24 can be processed and formed based on the same processing method, and the production efficiency of the pole piece 24 is higher. At the same time, generally the pole piece 24 is coated with the same active material on both sides, and in this case, all surfaces of the current collecting substrate 241 have the same polarity, which is more suitable for actual needs.

[0106] In some embodiments, optionally, Figure 6 and Figure 7 As shown, the active layer 245 also has a third coating area f3 extending along the first direction Y, the third coating area f3 intersects with at least one first coating area f1, and the effective energy density of the active layer 245 in the third coating area f3 is different from the effective energy density of the active layer 245 in the second coating area f2.

[0107] The thickness of the active layer 245 in the third coating area f3 is the same as that in the first coating area f1. The thickness setting of the first coating area f1 is also applicable to the third coating area f3, which will not be described again. At the same time, by setting the third coating area f3, the wrinkled lines generated on the pole piece 24 can be blocked in multiple directions, thereby further enhancing the anti-wrinkling effect of the pole piece 24.

[0108] In some embodiments, Figure 6 and Figure 7 As shown, the first coating area f1 and the third coating area f3 jointly form a grid-like structure.

[0109] At this time, the first coating area f1 and the third coating area f3 arranged in a grid-like pattern can be in the shape of a "king" character, an "open" character, or other forms. Moreover, the first coating area f1 extending along the second direction Z to the opposite ends of the current collector substrate 241 can cover any position of the current collector substrate 241 in the second direction Z, intersect and block the through-type wrinkling patterns in the first direction Y generated at any position of the current collector substrate 241 in the second direction Z. At the same time, the third coating area f3 can also block the through-type wrinkling generated in the direction intersecting itself. In this way, it can better ensure the anti-through wrinkling of the electrode sheet 24 and facilitate the processing of the electrode sheet 24.

[0110] It can be understood that in the above embodiments, by controlling the thickness difference of the active layer 245 between the first coating area f1 and the second coating area f2, the unequal effective energy density of the active layer 245 in the first coating area f1 and the second coating area f2 is achieved. It can be understood that there is naturally also a difference in the weight of the active layer 245. Therefore, the above effect can also be achieved by controlling the weight per unit volume of the active layer 245 in the first coating area f1 and the second coating area f2.

[0111] Specifically, in some embodiments, when the difference in the thickness of the active layer 245 between the first coating area f1 and the second coating area f2 is 3um - 150um, the deviation range of the weight per unit volume of the active layer 245 in the first coating area f1 and the second coating area f2 is within 6mg / 1540.25mm 2 - 500mg / 1540.25mm 2 .

[0112] Specifically, in some embodiments, when the polarity of the electrode sheet 24 is the cathode, the difference in the thickness of the active layer 245 between the second coating area f2 and the first coating area f1 is 5um - 20um, and the deviation range of the weight per unit volume of the active layer 245 in the first coating area f1 and the second coating area f2 is within 6mg / 1540.25mm 2 - 60mg / 1540.25mm 2 .

[0113] Specifically, in some embodiments, when the polarity of the electrode sheet 24 is the anode, the difference in the thickness of the active layer 245 between the first coating area f1 and the second coating area f2 is 3um - 25um, and the deviation range of the weight per unit volume of the active layer 245 in the first coating area f1 and the second coating area f2 is within 5mg / 1540.25mm 2-40mg / 1540.25mm 2 .

[0114] In some preferred embodiments of the present application, the pole piece 24 includes a current collecting substrate 241, which is wound into the battery 100 along the second direction Z, and has an active layer 245 on one side of the thickness direction F of the current collecting substrate 241. The active layer 245 includes a plurality of first coating regions f1 extending to opposite ends of the current collecting substrate 241 along the second direction Z, a second coating region f2 disposed between and parallel to two adjacent first coating regions f1, and a third coating region f3 extending along the first direction Y and intersecting with the first coating region f1, wherein the effective energy density of the active layer 245 in the third coating region f3 and the effective energy density of the active layer 245 in the first coating region f1 are both different from the effective energy density of the active layer 245 in the second coating region f2. In this way, an active layer 245 with uneven effective energy density is formed, thereby forming a rebound difference in the first coating region f1, the second coating region f2 and the third coating region f3 with different effective energy densities, avoiding the pole piece 24 from generating through-wrinkling lines in any direction, and helping to improve the quality of the battery 100.

[0115] On the other hand, some embodiments of the present application further provide a method for manufacturing a pole piece, which is used to manufacture the pole piece 24 in any of the above embodiments, and specifically includes the following steps:

[0116] S10, providing a pole piece body, wherein the pole piece body includes a current collecting matrix 241 and an active body disposed on at least one side of the current collecting matrix 241;

[0117] S20, coating active material on the first coating area f1 of the active body, removing at least part of the active material or attaching an insulating layer, so that the effective energy density of the active layer 245 in the first coating area f1 is different from the effective energy density of the active layer 245 in the second coating area f2 of the active body.

[0118] The first coating area f1 and the second coating area f2 are arranged in parallel along the first direction Y.

[0119] The pole piece body refers to an intermediate component formed after coating the active body on at least one side of the current collector. The coating method of the active body is the same as the coating method of the second coating area f2 in the active layer 245 in the above embodiment. For the explanation of the current collector and other terms, please refer to the above embodiment and will not be repeated here.

[0120] Active material is coated on the first coating area f1 of the pole piece body, at least part of the active material is removed, or an insulating layer is attached, so that the effective energy density of the active layer 245 in the first coating area f1 is increased or decreased, and the remaining part is used as the untreated second coating area f2, so that the effective energy density of the active layer 245 in the first coating area f1 is different from the effective energy density of the active layer 245 in the second coating area f2.

[0121] In this way, by setting the effective energy densities of the first coating area f1 and the second coating area f2 in the first direction Y to be unequal, an active layer 245 with uneven effective energy density is formed in the first direction Y, thereby forming a rebound difference in the first coating area f1 and the second coating area f2 with different effective energy densities. During the charging and discharging process of the battery 100, the through wrinkles generated at any position of the electrode sheet 24 are blocked, thereby avoiding the phenomenon of through wrinkles generated by the cathode electrode sheet or the anode electrode sheet wound in the battery cell 100.

[0122] In some embodiments, optionally, in step S20, when the active body is a cathode active material, etching and trenching are performed on the first coating region f1 of the active body to remove at least a portion of the active material.

[0123] Specifically, the first coating area f1 and the second coating area f2 can both be planes with equal heights in the thickness direction F or curved surfaces with unequal heights, as long as the first coating area f1 is made higher or lower than the second coating area f2 as a whole in the thickness direction F by etching or grooving, so as to reduce the content of active substances in the active layer 245 in the first coating area f1.

[0124] In some embodiments, optionally, in step S20, when the active body is a cathode active material, an insulating layer is attached to the first coating region f1 of the active body.

[0125] The insulating layer can be an insulating paint or an insulating glue, which is covered on the surface of the active layer 245 in the first coating area f1, and can insulate or inactivate the active material of the active layer 245 covered thereunder, making it invalid (i.e., it does not participate in the charging and discharging process of the battery 100), thereby reducing the effective energy density of the active layer 245 in the first coating area f1.

[0126] By reducing the energy density of the active layer 245 in the first coating area f1 of the cathode electrode, an active layer 245 with uneven effective energy density is formed in the first direction Y, thereby blocking the through-type wrinkling of the cathode electrode along the first direction Y. At the same time, the coating amount of the cathode active material is reduced and lithium plating is avoided.

[0127] In some embodiments, optionally, in step S20 , when the active body is an anode active material, the anode active material is overcoated on the surface of the active layer 245 in the first coating region f1 .

[0128] Specifically, the active layer 245 of the second coating area f2 is coated according to the standard thickness, and the height of the first coating area f1 in the thickness direction F of the current collecting substrate 241 is greater than that of the second coating area f2. The active layer 245 coated on the first coating area f1 is thicker, thereby achieving thickening of the active layer 245 in some areas, thereby achieving an increase in the effective density of the active layer 245 in some areas.

[0129] On the other hand, some embodiments of the present application further provide an electrode assembly 23, including a cathode electrode piece, an anode electrode piece, and an isolation piece separating the cathode electrode piece and the anode electrode piece, wherein the cathode electrode piece and / or the anode electrode piece is the electrode piece 24 described in any of the above embodiments.

[0130] It can be understood that by reducing the energy density of the active layer 245 of the first coating area f1 of the cathode electrode and / or increasing the energy density of the active layer 245 of the first coating area f1 of the anode electrode, it is ensured that the prevention of wrinkling and lithium deposition of the electrode 24 as described in any of the above embodiments can be achieved.

[0131] The separator is used to electrically isolate the cathode electrode piece and the anode electrode piece and allows the electrolyte to flow. The separator can be, but is not limited to, a separator film. As a common component in the art, the separator is not limited or elaborated herein.

[0132] Since the electrode assembly 23 includes the electrode piece 24 , it has all the above-mentioned beneficial effects, which are not limited here.

[0133] On the other hand, some embodiments of the present application further provide a battery cell 20 , including a shell 22 and an electrode assembly 23 accommodated in the shell 22 .

[0134] On the other hand, some embodiments of the present application further provide a battery 100 including the above-mentioned battery cell 20 .

[0135] On the other hand, some embodiments of the present application further provide an electrical device, comprising the above-mentioned battery 100, where the battery 100 is used to provide electrical energy.

[0136] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A pole piece, characterized in that: include: current collecting matrix; and An active layer is disposed on at least one side of the current collecting substrate along its thickness direction, and the active layer has a first coating area and a second coating area disposed in parallel along a first direction; The effective energy density of the active layer in the first coating area is different from the effective energy density of the active layer in the second coating area.

2. The pole piece according to claim 1, characterized in that: The thickness of the active layer in the first coating area is different from the thickness of the active layer in the second coating area.

3. The pole piece according to claim 2, characterized in that: When the polarity of the pole piece is anode, the thickness of the active layer in the first coating area is greater than the thickness of the active layer in the second coating area.

4. The pole piece according to claim 3, characterized in that: The difference between the thickness of the active layer in the first coating area and the thickness of the active layer in the second coating area is 3 um-150 um.

5. The pole piece according to claim 4, characterized in that: The difference between the thickness of the active layer in the first coating area and the thickness of the active layer in the second coating area is 3um-25um.

6. The pole piece according to claim 2, characterized in that: When the polarity of the pole piece is cathode, the thickness of the active layer in the first coating area is less than the thickness of the active layer in the second coating area.

7. The pole piece according to claim 6, characterized in that: The difference between the thickness of the active layer in the second coating area and the thickness of the active layer in the first coating area is 3 um-150 um.

8. The pole piece according to claim 7, characterized in that: The difference between the thickness of the active layer in the second coating area and the thickness of the active layer in the first coating area is 5um-20um.

9. The pole piece according to claim 1, characterized in that: When the polarity of the pole piece is cathode, the surface of the active layer in the first coating area is covered with an insulating layer.

10. The pole piece according to any one of claims 1 to 9, characterized in that: Two ends of at least a portion of the first coating region extend to opposite ends of the current collecting substrate along a second direction, respectively, and the second direction is perpendicular to the first direction.

11. The pole piece according to any one of claims 1 to 9, characterized in that: The active layer also has a third coating area extending along the first direction, and the third coating area intersects with at least one of the first coating areas; and the effective energy density of the active layer in the third coating area is different from the effective energy density of the active layer in the second coating area.

12. The pole piece according to claim 11, characterized in that: The first coating area and the third coating area are jointly constructed to form a grid structure.

13. A method for manufacturing a pole piece, characterized in that: The steps include: Providing a pole piece body, wherein the pole piece body comprises a current collecting matrix and an active body disposed on at least one side of the current collecting matrix; Active material is overlaid on the first coating area of ​​the active body, at least part of the active material is removed, or an insulating layer is attached, so that the effective energy density of the active layer in the first coating area is different from the effective energy density of the active layer in the second coating area of ​​the active body; wherein the first coating area and the second coating area are arranged side by side along a first direction.

14. The method for manufacturing a pole piece according to claim 13, characterized in that: The step of coating the active material on the first coating area of ​​the active body, removing at least part of the active material or attaching an insulating layer comprises: When the active body is a cathode active material, etching and trenching are performed on the first coating region of the active body to remove at least a portion of the active material.

15. The method for manufacturing a pole piece according to claim 13, characterized in that: The step of coating the active material on the first coating area of ​​the active body, removing at least part of the active material or attaching an insulating layer comprises: When the active body is a cathode active material, an insulating layer is attached to the first coating region of the active body.

16. The method for manufacturing a pole piece according to claim 13, characterized in that: The step of coating the active material on the first coating area of ​​the active body, removing at least part of the active material or attaching an insulating layer comprises: When the active body is an anode active material, the anode active material is overcoated on the surface of the active layer in the first coating region.

17. An electrode assembly, characterized in that: It includes a cathode electrode piece, an anode electrode piece and an isolating member isolated between the cathode electrode piece and the anode electrode piece; Wherein, the cathode electrode piece and / or the anode electrode piece is the electrode piece described in any one of claims 1-12.

18. A battery cell, characterized in that: include: A shell and the electrode assembly as claimed in claim 17 accommodated in the shell.

19. A battery, characterized in that: Comprising the battery cell as claimed in claim 18.

20. An electrical device, characterized in that: Comprising a battery as claimed in claim 19, the battery is used to provide electrical energy.

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