Electrode assemblies, battery cells, batteries and electrical equipment

Abstract

The embodiment of the present application discloses an electrode assembly, a battery cell, a battery and an electric device. The electrode assembly includes a cathode layer, an anode layer and a separator, which are wound to form an electrode assembly, and the separator is wrapped on both sides of the single-layer cathode layer and the single-layer anode layer, wherein the current collector of the anode layer is a three-dimensional porous metal material; the anode layer includes a first anode segment and a second anode segment extending and connected along the winding direction, the winding start end of the second anode segment is substantially aligned with the winding end end of the cathode layer, and the thickness d of the second anode segment is 2 is smaller than the thickness d of the first anode segment 1 The technical solution of the embodiment of the present application can make the active sites in the porous metal material match the metal deposited ions in the cathode in a battery using a three-dimensional porous metal material as an anode, avoiding the growth of sponge-like "dead" metal caused by the excess active site space in the anode, thereby improving the cycle performance and space utilization of the battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to an electrode assembly, a battery cell, a battery and an electrical device. Background Art

[0002] As environmental pollution becomes increasingly serious, the new energy industry has attracted more and more attention. In the new energy industry, battery technology is an important factor related to its development.

[0003] In the development of battery technology, how to improve battery performance is a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide an electrode assembly, a battery cell, a battery and an electrical device, which can enable the active sites in the porous metal material to match the metal deposited ions in the cathode in a battery using a three-dimensional porous metal material as the anode, thereby avoiding the growth of sponge-like "dead" metal due to the excess active site space in the anode, thereby improving the battery's cycle performance and space utilization.

[0005] In a first aspect, an electrode assembly is provided, comprising: a cathode layer, an anode layer and a separator, wherein the cathode layer, the anode layer and the separator are wound to form the electrode assembly, and the separator is wrapped on both sides of a single-layer cathode layer and a single-layer anode layer, wherein the current collector of the anode layer is a three-dimensional porous metal material; the anode layer comprises a first anode segment and a second anode segment extending and connected along a winding direction, the winding starting end of the second anode segment is substantially aligned with the winding ending end of the cathode layer, and the thickness d2 of the second anode segment is less than the thickness d1 of the first anode segment.

[0006] In the embodiment of the present application, the cathode layer, the anode layer and the separator are wound to form an electrode assembly. Each cathode layer and the anode layer are separated by a separator to ensure that the battery will not be short-circuited or open-circuited due to direct contact between the cathode and anode layers in the battery. The anode layer of the three-dimensional porous metal material is composed of a first anode segment and a second anode segment. The winding start end of the second anode segment is substantially aligned with the winding end end of the cathode layer, and the thickness of the second anode segment is less than the first anode segment. By controlling the thickness of the anode layer, in a battery using a three-dimensional porous metal material as an anode, the active sites in the outermost second anode segment match the metal ion capacity in the cathode layer, which can effectively avoid the growth of spongy "dead" metal caused by the extra space in the second anode segment, thereby improving the cycle performance of the battery, and also improving the space utilization inside the battery.

[0007] In a possible implementation manner, the thickness d2 of the second anode segment is:

[0008]

[0009] Wherein, x% is the porosity of the first anode segment. In the embodiment of the present application, the thickness d2 of the second anode segment satisfies the above formula, so that the surface active site density of the second anode segment can be the same as that of the first anode segment, thereby ensuring that the cathode and cathode ratios in the second anode segment are adapted.

[0010] In a possible implementation manner, the thickness d2 of the second anode segment is:

[0011]

[0012] Wherein, x% is the porosity of the first anode segment, and k% is the ductility of the anode layer. In the embodiment of the present application, the thickness d2 of the second anode segment satisfies the above formula, so that the surface active site density of the second anode segment can be the same as that of the first anode segment, thereby ensuring that the cathode and cathode ratios in the second anode segment are adapted.

[0013] In a possible implementation, the second anode segment is configured by rolling so that a thickness d2 of the second anode segment is smaller than a thickness d1 of the first anode segment.

[0014] In the embodiment of the present application, the second anode segment is rolled so that the thickness of the second anode segment is smaller than that of the first anode segment. This method is simple to implement and has strong operability, which is conducive to wide application in production. Moreover, the second anode segment after rolling not only has the same surface density as the first anode segment, but also helps to improve the mechanical strength of the battery.

[0015] In a possible implementation manner, the second anode segment surrounds the outermost cathode layer by no more than one circle.

[0016] In the embodiment of the present application, in a traditional battery with a three-dimensional porous metal material as the anode, the middle anode layer corresponds to the cathode layer on the upper and lower sides, and the outermost anode layer corresponds to the cathode layer on one side, thus causing the capacity mismatch between the outermost anode layer and the cathode layer, and then the sponge-like "dead" metal will appear, and finally lead to a short circuit or open circuit of the battery. By making the second anode segment surround the outermost cathode layer and limiting the encircling length of the second anode segment to no more than one circle, it can be ensured that the outermost second anode segment and the middle area have the same surface metal ion deposition active site density, so as to achieve the overall balance of the cathode and cathode capacity of the battery.

[0017] In a possible implementation, the cathode layer includes a first cathode segment and a second cathode segment extending in a winding direction and connected to each other, and a winding start end of the second cathode segment is substantially aligned with a winding start end of the first anode segment.

[0018] In the embodiment of the present application, the cathode layer is composed of a first cathode segment and a second cathode segment, and the winding starting end of the second cathode segment is basically aligned with the winding starting end of the first anode segment, which can ensure that the innermost circle of the anode layer has a corresponding first cathode layer, thereby ensuring the balance of the cathode and cathode ratios in the innermost circle of the battery.

[0019] In a possible embodiment, the first cathode segment is located between a first inner anode layer and a second inner anode layer, the first inner anode layer is a first straight anode layer of the anode layer along the winding direction, and the second inner anode layer is a second straight anode layer of the anode layer along the winding direction.

[0020] In the embodiment of the present application, in a conventional battery using a three-dimensional porous metal material as an anode, the innermost anode layer has no corresponding cathode layer, that is, no metal ions are deposited in the innermost three-dimensional porous material, which not only wastes the anode material, but also causes a decrease in the battery mass energy density and volume energy density. By placing the first cathode segment between the innermost anode layers, so that the first cathode segment faces the innermost anode layer, the utilization rate of the active material and space inside the battery can be improved, and the battery mass energy density and volume energy density can also be improved.

[0021] In a possible implementation manner, the winding start end of the first cathode segment extends to the bent anode layer between the first inner anode layer and the second inner anode layer.

[0022] In the embodiment of the present application, the first cathode segment is placed close to the innermost anode layer, that is, the innermost anode layer completely corresponds to the cathode layer, which can maximize the utilization of active materials and space inside the battery.

[0023] In a possible implementation manner, the thickness of the cathode layer is consistent with the thickness of the first anode segment.

[0024] In the embodiment of the present application, the cathode layer is composed of a first cathode segment and a second cathode segment. The first cathode segment corresponds to the innermost anode layer, and the second cathode segment corresponds to the remaining anode layers. The thickness of the cathode layer and the first anode segment is ensured to be the same, so that the ratio of anions and cations in the entire battery can be maintained in a matching state, avoiding the growth of sponge-like "dead" metal in the battery, thereby improving the battery's cycle performance.

[0025] In a second aspect, a battery cell is provided, comprising: the electrode assembly in the above embodiment; a shell having an opening for accommodating the electrode assembly; and an end cover for closing the opening.

[0026] In a third aspect, a battery is provided, comprising the battery cell in the above embodiment.

[0027] In a fourth aspect, an electrical device is provided, comprising the battery in the above embodiment, wherein the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a structural schematic diagram of a vehicle according to an embodiment of the present application;

[0029] Figure 2 is a schematic diagram of the exploded structure of a battery according to an embodiment of the present application;

[0030] Figure 3 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0031] Figure 4 is a schematic diagram of an electrode assembly according to an embodiment of the present application;

[0032] Figure 5 is a schematic diagram of an electrode assembly according to another embodiment of the present application;

[0033] Figure 6 is a front view of an electrode assembly according to an embodiment of the present application;

[0034] Figure 7 yes Figure 6 A magnified view of the area;

[0035] Reference numerals:

[0036] Vehicle 1, battery 2, battery cell 3;

[0037] Controller 11, motor 12, housing 20, electrode assembly 31, housing 32, electrode terminal 33, connecting member 34, pressure relief mechanism 35;

[0038] First housing 201, second housing 202, accommodating space 203, cathode layer 311, anode layer 312, separator 313, enlarged region 314, housing 321, end cover 322, positive electrode terminal 331, negative electrode terminal 332;

[0039] A first cathode segment 3111 , a second cathode segment 3112 , a first anode segment 3121 , a second anode segment 3122 , a first inner anode layer 31211 , and a second inner anode layer 31212 . DETAILED DESCRIPTION

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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).

[0046] 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.

[0047] 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.

[0048] In the present application, the battery cell may include a lithium metal secondary battery, a sodium metal battery or a magnesium metal battery, etc., which is not limited in the embodiments of the present application. The battery cell may be cylindrical, flat or in other shapes, etc., which is not limited in the embodiments of the present application. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, which is not limited in the embodiments of the present application. For the convenience of explanation, the following embodiments take lithium metal batteries as an example.

[0049] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity. For example, the battery mentioned in the present application may include a battery module or a battery pack. The battery generally includes a box for encapsulating one or more battery cells. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.

[0050] In the embodiment of the present application, the electrode assembly is a wound structure. For the convenience of description, the following embodiments are described by taking a square battery cell as an example.

[0051] With the increasing demand for battery energy density in energy storage devices and power batteries, traditional metal-ion batteries have been difficult to meet users' requirements for energy density. New secondary batteries with metals as anodes have become potential substitutes for metal-ion commercial batteries and have broad prospects.

[0052] Metal batteries often use three-dimensional porous metals as current collectors, which can not only reduce the local current density and inhibit the growth of dendrites, but also the deposited metal in the three-dimensional metal pores can reduce its volume change during the charge and discharge process. The application of three-dimensional porous metal current collectors has been widely adopted in theory. In academia, button batteries using three-dimensional porous metal current collectors have shown electrochemical performance that exceeds that of metal ion batteries in some aspects. However, in actual application, the operability is not strong.

[0053] First, taking ordinary foil as an example, in commonly used battery cell designs such as wound hard shells, wound soft packs, and wound cylinders, due to the high cost of cathode materials and the fact that the cathode is the main source of lithium ions, it is necessary to design the cathode to be an anode (the anode area is larger than the cathode area, and all cathode areas have anode areas facing each other). The simplest and most direct effect of such a design is that the anode is facing the anode in the innermost layer of the battery cell. Since the battery cells are double-layer coated, that is, active materials are coated on both sides of the current collector, the anode active materials in the outer layer of the anode in the outermost circle and the inner layer of the anode in the innermost circle are not utilized, which not only wastes the anode material and causes the battery cost to rise, but also causes the mass energy density and volume energy density of the battery cell to decrease.

[0054] Due to the difference between three-dimensional porous metal materials and traditional foil materials, in traditional foil materials, metal ions from the cathode material cannot penetrate the foil and deposit in the outermost and innermost graphite layers, so the ratio of the cathode and cathode facing each other can be guaranteed to be within the design range. However, in metal batteries with three-dimensional porous metal materials as anodes, metal ions from the cathode can freely shuttle and deposit inside the anode, so that metal ions may be deposited in the outermost layer or the innermost layer. This means that the innermost and outermost layers are double-layer anode active sites corresponding to single-layer cathode active sites, and the ratio of the cathode and cathode is greatly unbalanced. The metal ions that lose their constraints begin to deposit and grow freely, and are easy to react with the electrolyte and generate sponge-like "dead" metal. Since the capacity of the battery cell is often restricted by the number of active metal ions in the battery cell, if the above situation occurs, a large amount of active metal ions will be lost, resulting in a large amount of capacity loss. The generation of sponge-like "dead" metal will consume a large amount of electrolyte and produce gas, which will affect the gas production and residual electrolyte of the battery cell. Therefore, in metal batteries that use three-dimensional porous metal materials as anodes, we must find a way to solve this problem.

[0055] Based on the above considerations, the present application provides a porous metal electrode with differentiated tail, which can enable the active sites of the porous metal material to match the metal deposited ions of the cathode in a battery using a three-dimensional porous metal material as the anode, thereby avoiding the growth of sponge-like "dead" metal due to excess active site space in the anode, thereby improving the battery's cycle performance and improving the space utilization in the battery.

[0056] The tail-differentiated porous metal electrode described in the embodiments of the present application is suitable for electrode assemblies, battery cells, batteries, and electrical equipment using batteries.

[0057] Electrical equipment may be vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, electric tools, and the like. Vehicles may be fuel vehicles, gas vehicles, or new energy vehicles, and new energy vehicles may be pure electric vehicles, hybrid vehicles, or extended-range vehicles, and the like; spacecraft include airplanes, rockets, space shuttles, and spacecraft, and the like; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, and the like. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0058] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0059] Figure 1 This is a schematic diagram of the structure of a vehicle 1 provided in an embodiment of the present application. Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

[0060] The vehicle 1 may further include a controller 11 and a motor 12 , wherein the controller 11 is used to control the battery 2 to supply power to the motor 12 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

[0061] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0062] Figure 2 This is a schematic diagram of an explosion of a battery 2 provided in one embodiment of the present application. Figure 2 As shown, the battery 2 includes a box body 20 and a battery cell 3 , wherein the battery cell 3 is accommodated in the box body 20 .

[0063] The box 20 is used to accommodate the battery cell 3. The box 20 can be a variety of structures. In some embodiments, the box 20 may include a first box portion 201 and a second box portion 202, the first box portion 201 and the second box portion 202 cover each other, and the first box portion 201 and the second box portion 202 jointly define a storage space 203 for accommodating the battery cell 3. The second box portion 202 may be a hollow structure with one end open, the first box portion 201 is a plate-like structure, and the first box portion 201 covers the open side of the second box portion 202 to form a box 20 with a storage space 203; the first box portion 201 and the second box portion 202 may also be hollow structures with one side open, and the open side of the first box portion 201 covers the open side of the second box portion 202 to form a box 20 with a storage space 203. Of course, the first box body 201 and the second box body 202 can be in various shapes, such as a cylinder, a cuboid, etc.

[0064] In order to improve the sealing performance after the first box body 201 and the second box body 202 are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 201 and the second box body 202 .

[0065] Assuming that the first box body portion 201 covers the top of the second box body portion 202 , the first box body portion 201 can also be referred to as an upper box cover, and the second box body portion 202 can also be referred to as a lower box.

[0066] In the battery 2, there are multiple battery cells 3. Multiple battery cells 3 can be connected in series, in parallel, or in mixed connection. Mixed connection means that multiple battery cells 3 are both connected in series and in parallel. Multiple battery cells 3 can be directly connected in series, in parallel, or in mixed connection, and then the whole formed by multiple battery cells 3 is accommodated in the box 20; of course, multiple battery cells 3 can also be connected in series, in parallel, or in mixed connection to form a battery module (not shown in the figure), and multiple battery modules are then connected in series, in parallel, or in mixed connection to form a whole, and accommodated in the box 20. Multiple battery cells 3 in the battery module can be electrically connected through a busbar component to achieve parallel, series, or mixed connection of multiple battery cells 3 in the battery module.

[0067] like Figure 3As shown, it is a schematic diagram of the structure of a battery cell 3 of an embodiment of the present application, and the battery cell 3 includes one or more electrode assemblies 31, a shell 321 and an end cap 322. The shell 321 and the end cap 322 form a shell or battery box 32. The wall of the shell 321 and the end cap 322 are both called the wall of the battery cell 3, wherein for a rectangular battery cell 3, the wall of the shell 321 includes a bottom wall and four side walls. The shell 321 is determined according to the shape of one or more electrode assemblies 31 after combination. For example, the shell 321 can be a hollow cuboid or cube or cylinder, and one of the faces of the shell 321 has an opening so that one or more electrode assemblies 31 can be placed in the shell 321. For example, when the shell 321 is a hollow cuboid or cube, one of the planes of the shell 321 is an open surface, that is, the plane does not have a wall body so that the inside and outside of the shell 321 are connected. When the shell 321 can be a hollow cylinder, the end surface of the shell 321 is an open surface, that is, the end surface has no wall so that the inside and outside of the shell 321 are connected. The end cover 322 covers the opening and is connected to the shell 321 to form a closed cavity for placing the electrode assembly 31. The shell 321 is filled with an electrolyte, such as an electrolyte.

[0068] The battery cell 3 may also include two electrode terminals 33, which may be disposed on the end cap 322. The end cap 322 is generally in the shape of a flat plate, and the two electrode terminals 33 are fixed on the flat surface of the end cap 322, and the two electrode terminals 33 are respectively a positive electrode terminal 331 and a negative electrode terminal 332. Each electrode terminal 33 is provided with a corresponding connection member 34, or may also be referred to as a current collecting member 34, which is located between the end cap 322 and the electrode assembly 31, and is used to electrically connect the electrode assembly 31 and the electrode terminal 33.

[0069] In the battery cell 3, the battery assembly 31 can be provided as a single one or multiple ones according to actual use requirements, such as Figure 3 As shown, four independent battery assemblies 31 are arranged in the battery cell 3 .

[0070] A pressure relief mechanism 35 may also be provided on the battery cell 3. The pressure relief mechanism 35 is used to be activated to release the internal pressure or temperature of the battery cell 3 when the internal pressure or temperature reaches a threshold value.

[0071] The pressure relief mechanism 35 may be any possible pressure relief structure, which is not limited in the embodiments of the present application. For example, the pressure relief mechanism 35 may be a temperature-sensitive pressure relief mechanism, which is configured to melt when the internal temperature of the battery cell 3 provided with the pressure relief mechanism 35 reaches a threshold value; and / or, the pressure relief mechanism 35 may be a pressure-sensitive pressure relief mechanism, which is configured to rupture when the internal air pressure of the battery cell 3 provided with the pressure relief mechanism 35 reaches a threshold value.

[0072] Figure 4and Figure 5 They are schematic diagrams of battery assemblies according to different embodiments of the present application, Figure 4 It is a cylindrical electrode assembly. Figure 5 The present application does not impose any limitation on the shape of the electrode assembly 31. Figure 5 The rectangular electrode assembly shown is used as an example for explanation.

[0073] Figure 6 yes Figure 5 A front view of the electrode assembly shown, Figure 7 yes Figure 6 A partial enlarged view of a certain area in the image. Figure 6 As shown, the electrode assembly 31 includes a cathode layer 311, an anode layer 312 and a separator 313, the cathode layer 311, the anode layer 312 and the separator 313 are wound to form the electrode assembly 31, and both sides of the single-layer cathode layer 311 and the single-layer anode layer 312 are wrapped with the separator 313, wherein the current collector of the anode layer 312 is a three-dimensional porous metal material; Figure 7 As shown, the anode layer 312 includes a first anode segment 3121 and a second anode segment 3122 extending and connected along the winding direction, the winding starting end of the second anode segment 3122 is basically aligned with the winding ending end of the cathode layer 311, and the thickness d2 of the second anode segment 3122 is less than the thickness d1 of the first anode segment 3121.

[0074] The current collector of the cathode layer 311 is a metal material, such as metallic lithium, metallic sodium, etc., which is not limited in the present application. For the sake of clarity in the following embodiments, metallic lithium is used as an example for illustration.

[0075] The current collector of the anode layer 312 is a three-dimensional porous metal material, that is, a large number of holes are dispersed inside the metal, and these holes can provide deposition sites for the metal lithium in the lithium metal battery, that is, active sites of the lithium metal battery anode, so as to deposit the metal lithium in the porous metal material. In addition, the three-dimensional porous metal material has a large porosity, so as to be used as the anode layer 312 in the battery 2, the energy density of the battery can be greatly improved.

[0076] The isolation membrane 313 is a microporous membrane used to separate the cathode layer 311 and the anode layer 312, and is a polymer functional material with a nano-scale microporous structure. The main function of the isolation membrane 313 is to prevent the two poles from contacting and short-circuiting while allowing electrolyte particles to pass through. In the embodiment of the present application, the isolation membrane 313 can be high molecular weight polyethylene and polypropylene, because these two types have the advantages of high strength, good acid and alkali corrosion resistance, waterproof, chemical resistance, good biocompatibility, non-toxicity, etc., but the present application does not specifically limit the type of isolation membrane 313.

[0077] In the above scheme, the cathode layer 311, the anode layer 312 and the separator 313 are wound to form the electrode assembly 31. Each cathode layer 311 and the anode layer 312 are separated by the separator 313 to ensure that the battery 2 will not be short-circuited or open-circuited due to the direct contact between the cathode layer 311 and the anode layer 312. The anode layer 312 of the three-dimensional porous metal material is composed of a first anode segment 3121 and a second anode segment 3122, and the winding start end of the second anode segment 3122 is substantially aligned with the winding end end of the cathode layer 311, and the thickness of the second anode segment 3122 is less than the first anode segment 3121. By controlling the thickness of the anode layer 312, in the battery 2 using the three-dimensional porous metal material as the anode, the active sites in the outermost second anode segment 3122 match the metal ion capacity in the cathode layer 311, which can effectively avoid the growth of sponge-like "dead" metal caused by the excess space in the second anode segment 3122, thereby improving the cycle performance of the battery 2 and also improving the space utilization inside the battery 2.

[0078] Optionally, the thickness d2 of the second anode segment 3122 is:

[0079]

[0080] In the above solution, by making the thickness d2 of the second anode segment 3122 satisfy the above formula, the surface active site density of the second anode segment 3122 can be made the same as that of the first anode segment 3121 , thereby ensuring that the anode and cathode ratios in the second anode segment 3122 are adapted.

[0081] The details are as follows:

[0082] The area of ​​the single-layer anode layer 312 facing the single-layer cathode layer 311 is S, and the porosity of the three-dimensional porous metal material is x%. Then the volume V1 that the first anode segment 3121 can provide for metal lithium deposition is:

[0083] V1=V 孔 =S*d1*x%

[0084] The thickness of the second anode segment 3122 changes, and the porosity also changes. The amount V of the three-dimensional porous metal material per unit area S 金 No change, V 金 for:

[0085] V 金 =S*d1*(1-x%)

[0086] The second anode segment 3122 only needs to provide the outermost cathode layer 311 with a volume V2 for depositing metallic lithium, and V2 is:

[0087]

[0088] The total volume V of the three-dimensional porous metal material of the second anode segment 3122 does not change, and V is:

[0089]

[0090] To ensure that the surface active site density of the second anode segment 3122 is the same as that of the first anode segment 3121, the area of ​​the second anode segment 3122 facing the cathode layer 311 is the same as the area of ​​the first anode segment 3121 facing the cathode layer 311. Divide S on both sides of the equation to obtain d2:

[0091]

[0092] Optionally, when d1 is 200 um and x% is 80%, d2 is 120 um.

[0093] Optionally, x% may be 30% to 97%. For example, in one embodiment of the present application, x% may be 30% to 75%.

[0094] Optionally, the thickness d2 of the second anode segment 3122 is:

[0095]

[0096] In the above solution, by making the thickness d2 of the second anode segment 3122 satisfy the above formula, the surface active site density of the second anode segment 3122 can be made the same as that of the first anode segment 3121 , thereby ensuring that the anode and cathode ratios in the second anode segment 3122 are adapted.

[0097] The details are as follows:

[0098] The first anode segment 3121 can provide a volume V1 for metal lithium deposition, an amount V2 of the three-dimensional porous metal material, and a volume V3 of the three-dimensional porous metal material. 金 The volume V2 provided by the second anode segment 3122 for depositing metallic lithium is the same as that in the above embodiment and will not be described again here.

[0099] The elongation of the three-dimensional porous metal material is k%, and the S 金 for:

[0100] S 金 =S*(1+k%)

[0101] Then the volume V of the second anode segment 3122 is 金’ for:

[0102] V 金’ =V 金 / (1+k%)

[0103] The total volume V of the three-dimensional porous metal material of the second anode segment 3122 does not change, and V is:

[0104]

[0105] To ensure that the surface active site density of the second anode segment 3122 is the same as that of the first anode segment 3121, the area of ​​the second anode segment 3122 facing the cathode layer 311 is the same as the area of ​​the first anode segment 3121 facing the cathode layer 311. Divide S on both sides of the equation to obtain d2:

[0106]

[0107] Optionally, when d1 is 200 um, x% is 80%, and k% is 5%, d2 is 118 um.

[0108] Optionally, x% may be 30% to 97%. For example, in one embodiment of the present application, x% may be 30% to 75%.

[0109] Optionally, k% may be 0% to 10%. For example, in one embodiment of the present application, k% may be 0% to 5%.

[0110] Optionally, the second anode segment 3122 is configured by rolling so that a thickness d2 of the second anode segment 3122 is smaller than a thickness d1 of the first anode segment 3121 .

[0111] After being processed, the second anode segment 3122 has the same lithium metal deposition surface density as the first anode segment 3121, corresponding to the outermost cathode layer 311. The second anode segment 3122 can be processed by a variety of methods, as long as the thickness requirement is met, and this application does not impose any limitation on this.

[0112] In the above scheme, the second anode segment 3122 is rolled so that the thickness of the second anode segment 3122 is smaller than that of the first anode segment 3121. This method is simple to implement and has strong operability, which is conducive to wide application in production. Moreover, the second anode segment 3122 after rolling not only has the same surface density as the first anode segment 3121, but also helps to improve the mechanical strength of the battery 2.

[0113] Optionally, the second anode segment 3122 surrounds the outermost cathode layer 311 by no more than one circle.

[0114] In order to make the outermost second anode segment 3122 and the first anode segment 3121 have the same metal ion deposition surface density, the second anode segment 3122 is rolled to align with the outermost cathode layer 311. If the length of the second anode segment 3122 is greater than the length of the outermost cathode layer 311, the cathode and cathode ratio in the battery 2 will still be unbalanced.

[0115] In the above scheme, in the conventional battery 2 with three-dimensional porous metal material as the anode, the middle anode layer 312 corresponds to the cathode layer 311 on both sides, and the outermost anode layer 312 corresponds to the cathode layer 311 on one side, thus causing the capacity mismatch between the outermost anode layer 312 and the cathode layer 311, and then there will be sponge-like "dead" metal, and finally lead to short circuit or open circuit of the battery 2. The second anode segment 3122 is made to surround the outermost cathode layer 311 and the encircling length of the second anode segment 3122 is limited to no more than one circle, which can ensure that the outermost second anode segment 3122 and the middle area have the same surface metal ion deposition active site density, so as to achieve the overall positive and negative electrode capacity balance of the battery 2.

[0116] Optionally, the cathode layer 311 includes a first cathode segment 3111 and a second cathode segment 3112 extending in a winding direction and connected to each other, and a winding start end of the second cathode segment 3112 is substantially aligned with a winding start end of the first anode segment 3121 .

[0117] In the above scheme, the cathode layer 311 is composed of a first cathode segment 3111 and a second cathode segment 3112, and the winding starting end of the second cathode segment 3112 is basically aligned with the winding starting end of the first anode segment 3121, which can ensure that the innermost circle of the anode layer 312 has a corresponding first cathode layer 3111, thereby ensuring the balance of the cathode and cathode ratios in the innermost circle of the electrode assembly 31.

[0118] Optionally, the first cathode segment 3111 is located between the first inner anode layer 31211 and the second inner anode layer 31212, the first inner anode layer 31211 is the first straight section of the anode layer 312 along the winding direction, and the second inner anode layer 31212 is the second straight section of the anode layer 312 along the winding direction.

[0119] In a traditional battery 2 made of three-dimensional porous metal materials, the innermost anode layer 312 has no corresponding cathode layer 311, that is, the single-layer cathode layer 311 closest to the innermost anode layer 312 corresponds to a double-layer anode active site, resulting in a capacity mismatch between the innermost anode layer 312 and the cathode layer 311.

[0120] In the above scheme, the cathode layer 311 is inserted between the innermost anode layers 312, that is, the first cathode layer 3111 is inserted into the innermost anode layer 312. The second cathode layer 3112 is substantially aligned with the first anode segment 3121, so that the capacity of the innermost anode layer 312 and the cathode layer 311 in the electrode assembly 31 can be matched, thereby making full use of the anode material and improving the overall energy density of the battery 2.

[0121] Optionally, the winding start end of the first cathode segment 3111 extends to the bent anode layer 312 between the first inner anode layer 31211 and the second inner anode layer 31212 .

[0122] In the above solution, the first cathode segment 3111 is placed close to the innermost anode layer 312, that is, the innermost anode layer 312 completely corresponds to the cathode layer 311, which can maximize the utilization of active materials and space inside the battery 2.

[0123] Optionally, the thickness of the cathode layer 311 is consistent with the thickness of the first anode segment 3121 .

[0124] In order to balance the overall positive and negative ratios in the battery assembly 31, the innermost and innermost anode layers 312 and the middle region are kept with the same metal ion active sites by rolling the first anode segment 3122 and inserting the first cathode segment 3111 between the first inner anode layer 31211 and the second inner anode layer 31212. To ensure the overall balance of the electrode assembly 31, the thickness of the cathode layer 311 must be kept consistent with the thickness of the first anode segment 3121.

[0125] In the above scheme, the cathode layer 311 is composed of a first cathode segment 3111 and a second cathode segment 3112, the first cathode segment 3111 corresponds to the innermost anode layer 312, and the second cathode segment 3112 corresponds to the remaining anode layer 312. Ensuring that the thickness of the cathode layer 311 is the same as that of the first anode segment 3121 can maintain the ratio of anions and cations in the entire battery assembly 31 in a matching state, avoiding the growth of sponge-like "dead" metal in the battery 2, thereby improving the cycle performance of the battery.

[0126] The embodiment of the present application further provides a battery cell 3, comprising the battery assembly 31 in the aforementioned embodiment; a shell 321 having an opening for accommodating the electrode assembly 31; and an end cover 322 for closing the opening.

[0127] The embodiment of the present application further provides a battery 2, comprising the battery cell 3 in the aforementioned embodiment.

[0128] The embodiment of the present application further provides an electrical device, comprising the battery 2 in the aforementioned embodiment, and the battery 2 is used to provide electrical energy.

[0129] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode assembly, characterized in that: include: A cathode layer, an anode layer, and a separator, wherein the cathode layer, the anode layer, and the separator are wound to form the electrode assembly, and both sides of the single-layer cathode layer and the single-layer anode layer are wrapped with the separator, wherein the current collector of the anode layer is a three-dimensional porous metal material; The anode layer includes a first anode segment and a second anode segment extending in a winding direction and connected to each other. The winding start end of the second anode segment is substantially aligned with the winding end end of the cathode layer. The thickness d2 of the second anode segment is smaller than the thickness d1 of the first anode segment.

2. The electrode assembly according to claim 1, characterized in that: The thickness d2 of the second anode segment is: Wherein, x% is the porosity of the first anode segment.

3. The electrode assembly according to claim 1, characterized in that: The thickness d2 of the second anode segment is: Wherein, x% is the porosity of the first anode segment, and k% is the elongation of the anode layer.

4. The electrode assembly according to claim 2, characterized in that: The second anode segment is configured by rolling so that a thickness d2 of the second anode segment is smaller than a thickness d1 of the first anode segment.

5. The electrode assembly according to claim 1, characterized in that: The second anode segment surrounds the outermost cathode layer by no more than one circle.

6. The electrode assembly according to claim 1, characterized in that: The cathode layer includes a first cathode segment and a second cathode segment extending in a winding direction and connected to each other, wherein a winding start end of the second cathode segment is substantially aligned with a winding start end of the first anode segment.

7. The electrode assembly according to claim 6, characterized in that: The first cathode segment is located between a first inner anode layer and a second inner anode layer, the first inner anode layer is the first straight anode layer of the anode layer along the winding direction, and the second inner anode layer is the second straight anode layer of the anode layer along the winding direction.

8. The electrode assembly according to claim 7, characterized in that: The winding start end of the first cathode segment extends to the bent anode layer between the first inner anode layer and the second inner anode layer.

9. The electrode assembly according to any one of claims 1 to 8, characterized in that: The thickness of the cathode layer is consistent with the thickness of the first anode segment.

10. A battery cell, characterized in that: include: The electrode assembly according to any one of claims 1 to 9; a shell having an opening for accommodating the electrode assembly; An end cover is used to close the opening.

11. A battery, characterized in that: include: A plurality of battery cells as claimed in claim 10.

12. An electrical equipment, characterized in that: include: The battery according to claim 11, wherein the battery is used to provide electrical energy.

Images