Metal net and preparation method thereof, electrode material and battery

Abstract

The invention discloses a metal net, the metal net is used as an electrode active material or an electrode substrate in a battery, the metal net is of a honeycomb grid structure formed by stacking, fixedly connecting and stretching a plurality of layers of rolled metal foils with the thickness of 0.01-100 mu m in a first direction, and meshes of the metal net are through holes. And the meshes are formed by intervals formed by stretching the adjacent rolled metal foils. The invention discloses a preparation method of a metal net, an electrode material and a battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a metal mesh applied in a battery, a preparation method thereof, an electrode material and a battery. BACKGROUND

[0002] As a core means of energy storage and conversion, the performance of batteries plays a crucial role in the application and development of various electronic devices, new energy vehicles and renewable energy systems. The electrode structure inside the battery has a significant impact on the performance of the battery, especially the performance of the electrode active material and the electrode substrate, which are key factors affecting the electrode structure. Among them, the "electrode active material" generally refers to the material that directly participates in the electrochemical reaction and releases electrical energy in the battery. The "electrode substrate" refers to the conductive framework or current collector that supports the electrode active material, which mainly functions to provide mechanical support, electron conduction path for the electrode active material, and ensure full contact between the electrode active material and the electrolyte.

[0003] Currently, the electrode substrate and electrode active material widely used in the market have many shortcomings. Traditional electrode substrates are mostly made of metal foils (such as copper foil, aluminum foil), but this structure cannot fully meet the performance requirements of the battery due to the limited contact area with the electrolyte.

[0004] Therefore, the prior art proposes a porous structure as an improvement scheme. However, the porous structure still has many problems in actual application and production. For example, foamed metal (such as foamed copper, foamed aluminum) is usually obtained by powder metallurgy or electroplating. Powder metallurgy refers to adding a foaming agent to the powder, and the foaming agent volatilizes during sintering, leaving pores. Electroplating is a method of depositing metal on a porous organic matrix by electrochemical deposition, and the organic matrix is removed after sintering. Although the foamed metal obtained by these methods increases the specific surface area of contact with the electrolyte to some extent, the uniformity and tortuosity of the pore structure are often difficult to accurately control, which limits the permeability of the electrolyte and the ion transport efficiency. In addition, the process of obtaining foamed metal by powder metallurgy or electroplating is complex and costly, making it difficult to achieve large-scale and efficient production.

[0005] The prior art also proposes to prepare porous metal by electrochemically, lithographically or laser cutting metal foils. However, the lithographic and laser cutting processes cannot guarantee the uniformity of the pore size, especially when preparing large areas, the pore size may vary significantly due to processing errors. In addition, during the lithographic and laser cutting process, burrs or cracks may be generated at the edge of the hole due to etching or high temperature, which not only increases the surface roughness of the hole, but also reduces its electrical conductivity. In addition, the lithographic and laser cutting processes usually require layer-by-layer or point-by-point processing, which is low in production efficiency.

[0006] The electrode active material is usually mixed with a conductive agent and a binder in the form of a powder before being coated on a current collector to form an electrode material. This makes the powder-like electrode active material prone to falling off due to volume expansion and contraction during charging and discharging, resulting in a decrease in the stability of the electrode material. To this end, the prior art prepares a porous structure as an electrode material by mixing a powder-like electrode active material with a conductive agent and a binder, coating and depositing the mixture on a porous organic matrix, and removing the organic matrix by sintering. However, this preparation process is complex, and the porous electrode material obtained has poor mechanical properties and is prone to breakage. In addition, the above-mentioned methods require the use of a conductive agent and a binder, the addition of which can improve the conductivity and adhesion of the electrode active material, but also increases the internal resistance of the electrode material, reducing the energy density and charging / discharging efficiency of the battery. SUMMARY

[0007] To solve the above technical problems, embodiments of the present application provide a metal mesh, a method for preparing the same, an electrode material, and a battery.

[0008] In a first aspect, embodiments of the present application disclose a metal mesh as an electrode active material or an electrode substrate in a battery, the metal mesh being a honeycomb mesh structure formed by stacking, fixedly connecting, and stretching a plurality of rolled metal foils with a thickness of 0.01 μm to 100 μm in a first direction, the mesh holes of the metal mesh being through holes formed by stretching adjacent rolled metal foils.

[0009] With the above technical solution, the metal mesh as an electrode active material or an electrode substrate in a battery has a honeycomb mesh structure, through holes, hole walls formed by rolled foils, and an ultra-thin hole wall thickness, which not only helps to improve the electrical properties of the electrode material, including conductivity, ion transport performance, interface resistance, and energy density, but also helps to enhance the mechanical properties of the electrode active material or the electrode substrate, such as tensile strength and elongation.

[0010] In a second aspect, embodiments of the present application disclose a metal mesh as an electrode active material or an electrode substrate in a battery, the mesh holes of the metal mesh being through holes arranged to form a honeycomb mesh structure, the mesh holes being formed by the intervals between adjacent rolled metal foils in a plurality of stacked rolled metal foils, wherein the hole walls between adjacent mesh holes are the base layers of the rolled metal foils, and the thickness of the hole walls is 0.01 μm to 100 μm.

[0011] The metal mesh can be used as an electrode active material or an electrode substrate in a battery. The honeycomb mesh structure, the through holes, the hole walls formed by the calendered foil, and the ultra-thin hole wall thickness not only optimize the electrolyte permeation and ion transmission efficiency, improve the electrical performance of the electrode active material or the electrode substrate, but also improve the mechanical performance of the electrode active material or the electrode substrate, and prolong the cycle service life of the battery.

[0012] According to another specific embodiment of the present application, the specific surface area of the metal mesh is 0.1 m 2 / g to 100 m 2 / g.

[0013] According to another specific embodiment of the present application, the calendered metal foil is a copper foil, an aluminum foil, a lithium foil, a steel foil, an iron foil, or a nickel foil.

[0014] According to another specific embodiment of the present application, when the calendered metal foil is a copper foil, the tensile strength of the calendered metal foil is 200-350 MPa; when the calendered metal foil is an aluminum foil, the tensile strength of the calendered metal foil is 120-200 MPa; when the calendered metal foil is a steel foil, an iron foil, or a nickel foil, the tensile strength of the calendered metal foil is 400-700 MPa; and when the calendered metal foil is a lithium foil, the tensile strength of the calendered metal foil is 30-100 MPa.

[0015] According to another specific embodiment of the present application, the surface roughness (Rz) of the calendered metal foil is 0.6-1.5 μm.

[0016] According to another specific embodiment of the present application, the cross-sectional shape of the mesh hole is a quadrilateral or a hexagon.

[0017] According to another specific embodiment of the present application, the thickness of the hole wall between adjacent mesh holes is 0.01 μm to 100 μm.

[0018] According to another specific embodiment of the present application, the volume of the plurality of mesh holes accounts for 75% to 99.994% of the volume of the metal mesh.

[0019] According to another specific embodiment of the present application, the thickness of the metal mesh is 0.1 mm to 50 mm.

[0020] In a third aspect, embodiments of the present application disclose a preparation method of a metal mesh, for preparing the metal mesh in any of the embodiments of the first aspect or the second aspect, comprising the following steps:

[0021] Preparation of the stack: arranging a plurality of spaced contact areas on the surface of a calendered metal foil material with a thickness of 0.01 μm to 100 μm, stacking a plurality of layers of the calendered metal foil material along a first direction, and fixing and connecting adjacent calendered metal foil materials through the contact areas to form a stack;

[0022] Stretching: stretching the stack along the first direction to form the metal mesh.

[0023] The above technical solution can not only significantly improve the production efficiency of the metal mesh, but also make the metal mesh have a large specific surface area, and at the same time, have good mechanical properties and electrical properties.

[0024] According to another specific embodiment of the present application, the fixed and connected manner is gluing or welding.

[0025] In a fourth aspect, the embodiments of the present application disclose an electrode material, comprising the metal mesh in any one of the embodiments of the first aspect or the second aspect, or comprising the metal mesh prepared by the preparation method in any one of the embodiments of the third aspect.

[0026] The above technical solution can not only significantly improve the specific surface area, ion transmission efficiency and energy density of the electrode material, but also optimize the stability and mechanical properties of the electrode material.

[0027] In a fifth aspect, the embodiments of the present application further disclose a battery comprising the electrode material in the embodiments of the fourth aspect.

[0028] The above technical solution can significantly improve the ion transmission efficiency, energy density, cycle stability and safety of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A scanning electron microscope image of the metal mesh in the specific embodiment of the present application is shown;

[0030] Figure 2 A perspective view of the metal mesh in the specific embodiment of the present application is shown;

[0031] Figure 3 A perspective view of the stack in the specific embodiment of the present application is shown;

[0032] Figure 4 A top view of the metal mesh in the specific embodiment of the present application is shown;

[0033] Figure 5 A metallographic image of the surface of the calendered metal foil material as a copper foil is shown;

[0034] Figure 6 A metallograph showing a surface of an electrolytic metal foil as copper foil;

[0035] Figure 7 A photograph showing a structure of a laminated layer formed by artificial stretching in the embodiment of the present application;

[0036] Figure 8 A photograph showing a metal mesh of Example 2 of the present application, No. 1;

[0037] Figure 9 A photograph showing a metal mesh of Example 2 of the present application, No. 2.

[0038] (Symbol explanation)

[0039] x. First direction, y. Thickness direction, d1. Thickness of a hole wall, d2. Thickness of a metal mesh, 1. Calendered metal foil, 10. Mesh hole, 11. Contact area. DETAILED DESCRIPTION

[0040] The present application will now be described by way of specific embodiments, which will best be understood by reference to the accompanying drawings. While the present application is described in conjunction with the preferred embodiments, it will be understood that they are given by way of example only. None of the appended drawings, describing the preferred embodiments of the application, is necessarily to scale. Additionally, some of the drawings can have been simplified for illustrative purposes. It should be understood that the drawings and detailed description thereto are not intended to limit the application to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present application as defined by the appended claims. Numerous specific details of the application are described below to provide a thorough understanding of the application. The application can be practiced without some or all of the specific details. In other instances, well known

[0041] It should be noted that in this specification and in the claims that follow, similar reference numbers and letters indicate similar elements unless context dictates otherwise. The reference numbers and letters used in the following embodiments are merely used to facilitate understanding of the present application, and therefore, should not be construed to limit the scope of the present application.

[0042] The terms "first", "second", and the like, do not denote any order, quantity, combination, or importance, but are used to distinguish one element from another.

[0043] In the description of the embodiments, it also needs to be explained that, unless otherwise explicitly specified and limited, the terms "arranged", "connected", "linked" should be understood in a broad sense, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, can be electrically connected; can be directly connected, can be indirectly connected through an intermediate medium, can be internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments can be understood according to the specific circumstances.

[0044] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0045] In the first aspect, as shown in the drawings, the embodiments of the present application disclose a metal mesh as an electrode active material or an electrode substrate in a battery. The metal mesh is stacked by a plurality of layers of rolled metal foils 1 in a first direction (for example, the x direction shown in the drawings), and adjacent rolled metal foils 1 are fixedly connected in the first direction, and then the plurality of layers of rolled metal foils 1 are stretched in the first direction (for example, the x direction shown in the drawings) to form a honeycomb grid structure, and the mesh holes 10 of the metal mesh are through holes extending and penetrating in the thickness direction (for example, the y direction shown in the drawings) of the metal mesh. Among them, the mesh holes 10 are composed of intervals formed by stretching adjacent rolled metal foils 1. The thickness of the rolled metal foil 1 is 0.01 μm to 100 μm. Exemplarily, the thickness of the rolled metal foil 1 is 0.01 μm to 10 μm. Exemplarily, the thickness of the rolled metal foil 1 is 0.01 μm, 0.05 μm, 1 μm or 10 μm. Figures 1-4 Figures 2-4 Specifically, the surface of the rolled metal foil 1 is provided with uniformly spaced contact areas 11, and after the plurality of layers of rolled metal foils 1 are stacked in the first direction (for example, the x direction shown in the drawings), the adjacent rolled metal foils 1 are fixedly connected through the contact areas 11 to form a stack. Then, along the first direction (for example, the x direction shown in the drawings), the plurality of layers of rolled metal foils 1 are stretched to form a honeycomb grid structure. Figures 2-4 Figure 2 Figure 3

[0046] Specifically, the surface of the rolled metal foil 1 is provided with uniformly spaced contact areas 11, and after the plurality of layers of rolled metal foils 1 are stacked in the first direction (for example, the x direction shown in the drawings), the adjacent rolled metal foils 1 are fixedly connected through the contact areas 11 to form a stack. Then, along the first direction (for example, the x direction shown in the drawings), the plurality of layers of rolled metal foils 1 are stretched to form a honeycomb grid structure. Figures 2-4 Figures 2-4 ​​​​​The stretching of the stack (in the x direction as shown) causes the adjacent rolled metal foils 1 to form a space, which forms the mesh hole 10. That is, the hole wall between adjacent mesh holes 10 is formed by the layered substrate of the rolled metal foil 1, that is, the layer of the rolled metal foil 1, specifically, the unsecured area on the layered substrate of the rolled metal foil 1, which is the other area (i.e., the non-contact area) relative to the contact area 11, and can also be referred to as the free area. The layer thickness of the unsecured area is the thickness d1 of the hole wall (i.e., the wall thickness). In other words, the free areas of adjacent rolled metal foils 1 are pulled apart during the stretching process to form the mesh hole 10, which is uniformly and regularly distributed in a plane perpendicular to the thickness direction of the metal mesh. This plane is also the extension plane of the metal mesh. The mesh hole 10 extends in the thickness direction of the metal mesh (e.g., the y direction as shown), and the thickness direction (e.g., the y direction as shown) is perpendicular to the first direction (e.g., the x direction as shown). Figure 2 and Figure 3 the y direction as shown) extends in the thickness direction of the metal mesh (e.g., the y direction as shown), and the thickness direction (e.g., the y direction as shown) is perpendicular to the first direction (e.g., the x direction as shown). Figure 2 and Figure 3 the y direction as shown) extends in the thickness direction of the metal mesh (e.g., the y direction as shown), and the thickness direction (e.g., the y direction as shown) is perpendicular to the first direction (e.g., the x direction as shown). Figures 2-4

[0047] The metal mesh of the present application is formed by stacking, fixedly connecting, and stretching the multi-layered rolled metal foil 1, and can efficiently obtain a honeycomb mesh structure with uniform pore distribution. The formed honeycomb mesh structure can uniformly disperse stress in all directions, effectively buffer the volume change (expansion / contraction) of the metal mesh during charging and discharging, avoid damage to the electrode structure, and thus prolong the cycle life of the battery.

[0048] In the specific embodiment of the present application, the metal mesh is formed by stacking, fixedly connecting, and stretching the rolled metal foil 1. The rolled metal foil refers to a metal foil with a small thickness (e.g., about 20 cm) formed by repeatedly rolling a large metal raw material (e.g., a metal ingot or a metal block) and annealing processing. The metal raw material is a non-electrolytic metal. The rolled metal foil of the present application is different from an electrolytic metal foil, which refers to a metal foil formed by depositing a plating solution containing a desired metal on a bright stainless steel (or titanium) roller to form a uniform film of the desired metal, and then continuously peeling and winding it.

[0049] The rolled metal foil 1 has high density and low surface roughness after repeated rolling. The present application uses a rolled metal foil with extremely thin thickness formed by rolling to form the metal mesh. Compared with an extremely thin metal foil also obtained by electrolysis, deposition, etc., the rolled metal foil used in the present application has higher mechanical strength and a smoother surface, so that the metal mesh obtained as an active material or metal substrate can more favorably improve the electrical performance of the battery. The rolled metal foil is also less prone to damage when forming a honeycomb mesh structure by stretching. In addition, the rolling method is more efficient and suitable for large-scale production.​

[0050] As shown in Figure 5 and Figure 6 Compared with electrolytic metal foil, the calendered metal foil 1 has a small surface roughness, thereby shortening the transmission distance of ions and electrons on the surface of the electrode substrate or the surface of the electrode active material; the calendered metal foil 1 has a high density, thereby having a higher tensile strength and elongation, and further improving the mechanical properties of the metal mesh. The calendered metal foil used in the present application has a thickness of 0.01 μm to 100 μm, that is, the thickness d1 of the hole wall between adjacent mesh holes 10 is 0.01 μm to 100 μm. Research shows that the calendered metal foil 1 with such thickness enables the metal mesh of the honeycomb mesh structure to have a large specific surface area, and the large specific surface area means more active sites, which can significantly improve the energy density of the battery.

[0051] Compared with foamed metal (for example, foamed copper), the metal mesh of the present application not only has a honeycomb network structure, but also has mesh holes 10 that are independent of each other and extend and penetrate in the thickness direction, thereby providing a fast and uniform penetration channel for the electrolyte, so that the electrolyte can quickly and uniformly reach every corner of the electrode material, and accelerate the ion transmission process. Such efficient electrolyte penetration and ion transmission capability can effectively shorten the charging and discharging time of the battery, improve the power density of the battery, and make the metal mesh of the present application more suitable for high-power applications, such as fast charging of electric vehicles.

[0052] The porous metal prepared by photolithography or laser cutting of the layered metal foil has a hole wall composed of the layered metal foil remaining after photolithography or laser cutting, and the thickness of the hole wall is relatively thick. The thin hole wall is not easy to control, and the smoothness and mechanical properties of the hole wall itself formed by the above-mentioned punching method are weak. In addition, the existing active material formed by punching, such as porous lithium, and the current collector, such as porous copper foil and porous aluminum foil, is a two-dimensional layered material. In order to increase the specific surface area and electrical properties, the strategy adopted is to reduce the thickness of the two-dimensional layered material. The metal mesh of the present application is a three-dimensional structure formed by stacking, fixedly connecting and stretching a plurality of calendered metal foils 1, and the mesh holes are surrounded by the unfixed areas of adjacent calendered metal foils 1. The calendered metal foil 1 constituting the hole wall is formed by a calendering process and needs to be pressed to 0.01 μm to 100 μm, so that the calendered metal foil 1 has a relatively thin thickness, and the calendered metal foil 1 pressed to this thickness also has a high density and a low surface roughness, so that the hole wall between the mesh holes 10 of the obtained metal mesh can have the properties of the calendered metal foil 1. This means that the specific surface area of the metal mesh is increased, the current density per unit area of the metal mesh is reduced, the generation of lithium dendrites is effectively avoided, and at the same time, the hole wall of the mesh hole is more solid, thereby improving the electrical properties and mechanical properties of the electrode material.

[0053] In addition, when the metal mesh of the present application is used as an electrode active material in a battery, the metal mesh with the three-dimensional structure of the present application can be directly used as the electrode material, eliminating the need for adding conductive agents and binders in the preparation process of the traditional electrode material, and without the need for using a current collector for support. This makes the electrode active material of the present application not only be in full contact with the electrolyte, improving the conductivity of the electrode material, while avoiding the problems of increased internal resistance and reduced energy density caused by the addition of conductive agents and binders, but also simplifying the preparation process of the electrode material and reducing the production cost.

[0054] Therefore, by using the above technical solution, the metal mesh of the present application has a honeycomb network structure, the mesh hole 10 is a through hole, and the thickness d1 of the mesh hole wall is 0.01 μm to 100 μm. The metal mesh as an electrode active material or an electrode substrate in a battery is not only beneficial to improving the electrical properties of the electrode material, including conductivity, ion transport performance, interface resistance, and energy density, but also beneficial to enhancing the mechanical properties of the electrode material, such as tensile strength, and beneficial to the penetration of the electrolyte.

[0055] In a second aspect, as shown in Figures 1-4 , the embodiment of the present application proposes a metal mesh, the metal mesh as an electrode active material or an electrode substrate in a battery, the mesh hole 10 of the metal mesh is a through hole extending along the thickness direction (for example Figure 2 and Figure 3 y direction as shown), the mesh hole 10 is arranged to form a honeycomb grid structure, and the mesh hole 10 is formed by the interval between the adjacent calendered metal foils 1 in the multi-layer stacked calendered metal foils 1, wherein the hole wall between the adjacent mesh holes 10 is the base layer of the calendered metal foil 1, and the thickness d1 of the hole wall is 0.01 μm to 100 μm.

[0056] Among them, the base layer of the calendered metal foil 1 is the unfixed area of the calendered metal foil, and the unfixed area is the other area (i.e. non-contact area) relative to the contact area, which can also be called the free area. At this time, the layer thickness of the unfixed area is the thickness d1 of the hole wall. In other words, the free area of the adjacent calendered metal foil 1 is pulled apart to form the mesh hole 10 in the stretching process, and the mesh hole 10 is regularly distributed along the plane parallel to the first direction (for example Figures 2-4 as shown Figure 2 and Figure 3 y direction as shown) extends along the thickness direction of the metal mesh.

[0057] With the metal net as the electrode active material or the electrode substrate in the battery in the technical solution, the honeycomb grid structure, the through holes, the hole walls formed by the calendered metal foil material, and the ultra-thin hole wall thickness not only improve the electrical performance of the electrode material, but also improve the mechanical performance of the electrode material and optimize the permeation of the electrolyte, thereby ensuring the overall performance of the battery, including the energy density, the first charge-discharge efficiency, the cycle service life, the thermal stability, and the mechanical performance. Specifically, as described above, details are not repeated here.

[0058] In some possible embodiments provided by the present application, the present application discloses an electrode active material, which is the metal net as described above. Specifically, the electrode active material can be a negative electrode active material, more specifically a lithium negative electrode material, for example, a honeycomb lithium.

[0059] In some possible embodiments provided by the present application, the present application discloses an electrode substrate, which is the metal net as described above. Specifically, the electrode substrate can be a current collector, for example, a honeycomb copper foil or a honeycomb aluminum foil.

[0060] In some possible embodiments provided by the present application, the calendered metal foil material 1 is a copper foil, an aluminum foil, a lithium foil, a steel foil, an iron foil, or a nickel foil. When the calendered metal foil material 1 is a steel foil, a copper foil, or an aluminum foil, the metal net is used as an electrode substrate in the battery; when the calendered metal foil material 1 is a lithium foil, a steel foil, an iron foil, or a nickel foil, the metal net is used as an electrode active material in the battery.

[0061] In some possible embodiments provided by the present application, the calendered metal foil material 1 is in a hard state or a soft state. Preferably, the calendered metal foil material 1 is in a hard state. In this embodiment, the calendered metal foil material in a hard state can be understood as a calendered metal foil material with a relatively high tensile strength. For example, when the calendered metal foil material 1 is a copper foil, the tensile strength of the calendered metal foil material 1 in a hard state is 200-350 MPa; when the calendered metal foil material 1 is an aluminum foil, the tensile strength of the calendered metal foil material 1 in a hard state is 120-200 MPa; when the calendered metal foil material 1 is a steel foil, an iron foil, or a nickel foil, the tensile strength of the calendered metal foil material 1 in a hard state is 400-700 MPa; and when the calendered metal foil material 1 is a lithium foil, the tensile strength of the calendered metal foil material 1 in a hard state is 30-100 MPa. That is to say, the metal in a hard state used by the calendered metal foil material 1 in the present embodiment can make the hole walls of the mesh holes have a relatively high hardness and tensile strength, so that the metal net of the present application can withstand a relatively large mechanical stress, which is helpful to improve the mechanical performance of the electrode material.

[0062] In some possible embodiments provided by the present application, the surface roughness (Rz) of the rolled metal foil 1 is 0.6-1.5 μm. The surface roughness (Rz) of the electrolytic metal foil is generally 4 μm or more. Thus, compared with the electrolytic metal foil, the transmission distance of ions and electrons on the metal mesh can be effectively shortened. In addition, when the metal mesh is an electrode substrate, the surface roughness in this range can make the electrode substrate have appropriate adhesion, so that the active material can be more firmly attached to the electrode substrate, reducing the shedding of the active material during the charging and discharging process, thereby improving the stability of the electrode and the cycle life of the battery.

[0063] Further, the cross-sectional shape of the mesh hole 10 in the embodiment is a polygon, and further a hexagon or a quadrilateral. Exemplarily, the cross-sectional shape of the mesh hole 10 is a hexagon. The hexagonal structure has excellent structural stability, so that the hole wall of the mesh hole 10 is not easy to locally collapse, and the original pore structure of the metal mesh can be better maintained, ensuring that the metal mesh has stable mechanical properties and electrical properties. In addition, the hexagonal mesh hole can provide the maximum porosity and specific surface area in a unit volume. This means that under the same volume or mass, the hexagonal mesh hole 10 can accommodate more active material or provide more active sites, thereby significantly improving the battery capacity. Exemplarily, the cross-sectional shape of the mesh hole 10 is a quadrilateral. This means that when the adjacent rolled metal foils are fixedly connected through the contact area, for example, the contact area can be point-like or line-like, which is beneficial to further improve the specific surface area of the metal mesh. Further, the quadrilateral is a rhombus, i.e., the cross-sectional shape of the mesh hole 10 is a rhombus, and the symmetrical rhombus structure is also beneficial to ensure that the metal mesh has stable mechanical properties and electrical properties.

[0064] In some possible embodiments provided by the present application, the thickness d1 of the hole wall between adjacent mesh holes is 0.01-12 μm, i.e., the thickness of the rolled metal foil 1 used in the specific embodiments of the present application is 0.01-12 μm. Under this thickness, on the one hand, the specific surface area of the metal mesh can be significantly improved, thereby improving the conductivity of the electrode material and the energy density of the battery. On the other hand, a thinner wall thickness also means that the path to be passed by electrons and ions during transmission is shorter, thereby reducing the internal resistance of the metal mesh, which is beneficial to achieve higher energy density and longer endurance time.

[0065] Further, the thickness d1 of the hole wall between adjacent mesh holes is 0.01-6 μm, i.e. the thickness of the rolled metal foil 1 is 0.01-6 μm. According to the prior art industry standard, a metal foil with a thickness of ≤ 12 μm is referred to as an ultra-thin metal foil, and a metal foil with a thickness of ≤ 6 μm is referred to as an extremely thin metal foil. Currently, the electrolytic metal foil in the prior art can only reach the level of an extremely thin metal foil. The thickness of the rolled metal foil 1 used in the present application reaches the level of the thickness of the electrolytic metal foil, and the specific surface area of the metal mesh is further increased. This means that the metal mesh can further provide more active sites under the same volume or mass, greatly promoting the contact and reaction between the electrode and the electrolyte. During the charging and discharging process of the battery, this will significantly accelerate the transmission of ions, further shorten the charging and discharging time, and also help to further reduce the internal resistance of the electrode material and improve the energy density of the battery.

[0066] Further, the thickness d1 of the hole wall between adjacent mesh holes is 0.01-6 μm, i.e. the thickness of the rolled metal foil 1 is 0.01-6 μm. According to the prior art industry standard, a metal foil with a thickness of ≤ 12 μm is referred to as an ultra-thin metal foil, and a metal foil with a thickness of ≤ 6 μm is referred to as an extremely thin metal foil. Currently, the electrolytic metal foil in the prior art can only reach the level of an extremely thin metal foil. The thickness of the rolled metal foil 1 used in the present application reaches the level of the thickness of the electrolytic metal foil, and the specific surface area of the metal mesh is further increased. This means that the metal mesh can further provide more active sites under the same volume or mass, greatly promoting the contact and reaction between the electrode and the electrolyte. During the charging and discharging process of the battery, this will significantly accelerate the transmission of ions, further shorten the charging and discharging time, and also help to further reduce the internal resistance of the electrode material and improve the energy density of the battery. 2 2 Further, the thickness d1 of the hole wall between adjacent mesh holes is 0.01-6 μm, i.e. the thickness of the rolled metal foil 1 is 0.01-6 μm. According to the prior art industry standard, a metal foil with a thickness of ≤ 12 μm is referred to as an ultra-thin metal foil, and a metal foil with a thickness of ≤ 6 μm is referred to as an extremely thin metal foil. Currently, the electrolytic metal foil in the prior art can only reach the level of an extremely thin metal foil. The thickness of the rolled metal foil 1 used in the present application reaches the level of the thickness of the electrolytic metal foil, and the specific surface area of the metal mesh is further increased. This means that the metal mesh can further provide more active sites under the same volume or mass, greatly promoting the contact and reaction between the electrode and the electrolyte. During the charging and discharging process of the battery, this will significantly accelerate the transmission of ions, further shorten the charging and discharging time, and also help to further reduce the internal resistance of the electrode material and improve the energy density of the battery.

[0067] In some possible embodiments provided by the present application, the volume of the plurality of mesh holes 10 accounts for 75-99.994% of the volume of the metal mesh, i.e. it can be understood that the porosity of the metal mesh is 75-99.994%. Therefore, this means that the effective surface area of the metal mesh in contact with the electrolyte is significantly increased. This directly promotes the ion transmission rate between the electrode active material and the electrolyte, so that active substances such as lithium ions can be embedded and extracted more quickly and uniformly inside the metal mesh, thereby greatly improving the rate performance of the battery, i.e. the charging and discharging ability of the battery under high current density is significantly enhanced, the polarization phenomenon is reduced, and the charging and discharging time of the battery is shortened. In addition, when the metal mesh is an electrode substrate, such a range of porosity also means that more active substances can be accommodated under the same volume or mass, thereby significantly improving the energy density of the battery. Specifically, the cross-sectional area of a single mesh hole 10 is 1.50x10 -6 ~ 3.50x10 -6 m 2 , for example, the cross-sectional area of a single mesh hole 10 is 2.60x10 -6 m 2 , and the volume of a single mesh hole 10 is 0.01-0.05m 3 ​For example, the volume of a single mesh 10 is 0.03 m 3 .

[0068] In some possible embodiments provided by the present application, the thickness d2 of the metal mesh is 0.1 mm-50 mm. The metal mesh with the thickness can improve the rate performance of the battery, i.e., the fast charging and discharging capability, and also help to reduce the concentration polarization. The metal mesh with the thickness can contain more active substances in unit area, which helps to improve the energy density of the electrode material and the entire battery. By controlling the thickness d2 of the metal mesh to be 0.1 mm-50 mm, a good balance between the mechanical strength, ion transmission efficiency and energy density can be achieved, avoiding problems such as insufficient capacity caused by too thin electrode or mass transfer blocked and polarization intensified caused by too thick electrode.

[0069] In any of the above embodiments, the specific surface area of the metal mesh is 0.1 m 2 / g-100 m 2 / g, specifically, the specific surface area of the metal mesh is 0.1 m 2 / g-5 m 2 / g, 5 m 2 / g-10 m 2 / g, 10 m 2 / g-25 m 2 / g, 25 m 2 / g-50 m 2 / g, 50 m 2 / g-75 m 2 / g or 75 m 2 / g-100 m 2 / g. It is found that the specific surface area in the range not only provides sufficient active sites for electrochemical reactions, improves the stability of the electrode material and increases the energy density of the battery, but also avoids the occurrence of side reactions caused by too high specific surface area.

[0070] Specifically, during the charging and discharging process of the battery, ions need to be inserted and extracted on the surface of the electrode material. The larger the specific surface area, the more active sites available for ion reaction, which in turn accelerates the ion transmission process, shortens the charging and discharging time of the battery and improves the power density of the battery. However, when there are too many active sites, unnecessary reduction or oxidation reactions of the electrolyte on the surface of the electrode will occur, generating byproducts, which will deteriorate the performance of the battery. At the same time, during the charging and discharging process of the battery, the electrode material will experience volume expansion and shrinkage. The specific surface area in the above range can disperse stress and reduce structural damage caused by volume change, i.e., improve the stability of the electrode material.

[0071] Further, when the metal mesh is used as an electrode substrate, a higher specific surface area helps to increase the energy density of the battery. This is because, at the same volume or mass, an electrode material with a larger specific surface area can accommodate more active material, and thus has a higher battery capacity. That is, at the same battery size, the battery can provide a longer endurance time or a greater energy output. At this time, the relationship between the battery capacity and the specific surface area is shown in Equation 1:

[0072] Q = kS α Equation 1

[0073] where Q represents the battery capacity, S represents the specific surface area of the metal mesh, and k and a are constants related to factors such as battery materials, structure, process, etc. Exemplarily, a is 0.5 to 1.5.

[0074] In the present embodiment, preferably, the thickness of the rolled metal foil 1 is 10 nm to 1000 nm, and the specific surface area of the honeycomb mesh is 0.2 m 2 / g to 50 m 2 / g. Further, when the rolled metal foil 1 is a copper foil, the thickness of the rolled metal foil 1 is 10 nm to 1000 nm, and the specific surface area of the honeycomb mesh is 0.22 m 2 / g to 22.4 m 2 / g; when the rolled metal foil 1 is an aluminum foil, the thickness of the rolled metal foil 1 is 75 nm to 150 nm, and the specific surface area of the aluminum honeycomb mesh is 5 m 2 / g to 10 m 2 / g; and when the rolled metal foil 1 is a steel foil, the thickness is 25 nm to 51 nm, and the specific surface area of the steel honeycomb mesh is 5 m 2 / g to 10 m 2 / g.

[0075] In any of the above embodiments, the metal mesh has a tensile strength of 30-700 MPa, and further has a tensile strength of 120-350 MPa, and an elongation of less than 10%. The tensile strength of the metal mesh is mainly determined by the tensile strength of the rolled metal foil 1. Specifically, when the rolled metal foil 1 is a copper foil, the tensile strength of the rolled metal foil 1 is 200-350 MPa, and the metal mesh has a tensile strength of 200-350 MPa, and an elongation of less than 10%; when the rolled metal foil 1 is an aluminum foil, the tensile strength of the rolled metal foil 1 is 120-200 MPa, and the metal mesh has a tensile strength of 120-200 MPa, and an elongation of less than 5%; when the rolled metal foil is a lithium foil, the tensile strength of the rolled metal foil 1 is 30-100 MPa, and the metal mesh has a tensile strength of 30-100 MPa; when the rolled metal foil is a steel foil, an iron foil, or a nickel foil, the tensile strength of the rolled metal foil 1 is 400-700 MPa, and the metal mesh has a tensile strength of 400-700 MPa.

[0076] In a third aspect, the embodiments of the present application disclose a method for preparing a metal mesh, for preparing the metal mesh according to any of the embodiments of the first aspect or the second aspect, comprising the following steps:

[0077] Preparation of the stack: Referring to Figure 3 , a plurality of contact areas 11 are arranged on the surface of the rolled metal foil 1 with a thickness of 0.01-100 μm, and the plurality of rolled metal foils 1 are stacked along a first direction (for example, the x direction as shown in Figure 3 and Figure 4 ), and the adjacent rolled metal foils 1 are fixedly connected through the contact areas 11 to form a stack. The fixedly connected manner is adhesion or welding, which can be selected by the skilled person according to the actual needs.

[0078] Stretching: Referring to Figure 4 , the stack is stretched along the first direction (for example, the x direction as shown in Figure 3 and Figure 4 ) to form a metal mesh. Exemplarily, a planar mesh drawing machine can be used to stretch the stack along the first direction to form the metal mesh.

[0079] Exemplarily, in order to show the structure of the stack, referring to Figure 7 , Figure 7 , the structure of the stack formed by artificial stretching.

[0080] Specifically, the contact areas 11 are arranged on the surface of the rolled metal foil 1 with a uniform interval, and the plurality of rolled metal foils 1 are stacked along a first direction (for example, the x direction as shown in Figures 2-4After the stacking along the x direction shown, the adjacent rolled metal foils 1 are fixedly connected through the contact areas 11 to form a stack. Then, the stack is stretched along the first direction (for example Figures 2-4 the x direction shown) to make the adjacent rolled metal foils 1 form a spacing, which constitutes the mesh hole 10. That is, the adjacent rolled metal foils 1 are pulled apart during the stretching to form the mesh hole 10, which is regularly distributed in a plane parallel to the first direction (for example Figures 2-4 the x direction shown) and extends along the thickness direction of the metal mesh (for example Figure 2 and Figure 3 the y direction shown).

[0081] Therefore, the preparation method not only significantly improves the production efficiency of the metal mesh, but also makes the metal mesh have a larger specific surface area and excellent mechanical and electrical properties.

[0082] In some possible embodiments provided by the present application, the metal mesh is obtained by using a rolled metal foil 1 with a thickness of 0.01 μm to 100 μm in the preparation method of the honeycomb core. Specifically, first, a plurality of spaced contact areas 11 are formed on the surface of the rolled metal foil 1 with a thickness of 0.01 μm to 100 μm by a coater, and the contact areas 11 are coated with solder or glue, for example. When the contact areas 11 are coated with solder, the adjacent rolled metal foils 1 are welded through the contact areas 11 to be fixedly connected to form a stack; when the contact areas 11 are coated with glue, the adjacent rolled metal foils 1 are fixedly connected by heating the contact areas 11 to make the glue solidify. Then, the stack is stretched along the first direction (for example Figure 3 and Figure 4 the x direction shown) to form the metal mesh.

[0083] In a fourth aspect, the embodiments of the present application disclose an electrode material, which comprises the metal mesh in any one of the embodiments of the first aspect or the second aspect, or is prepared by the preparation method in any one of the embodiments of the third aspect.

[0084] By using the above technical solution, the electrode material uses the metal mesh with a honeycomb network structure, which not only significantly improves the specific surface area, ion transmission efficiency and energy density of the electrode material, but also optimizes the stability and mechanical properties of the electrode material.

[0085] In a fifth aspect, the embodiments of the present application further disclose a battery comprising the electrode material in the embodiments of the fourth aspect.

[0086] By adopting the above technical solution, since the electrode material adopts the metal mesh with the honeycomb network structure, the ion transmission efficiency of the battery is greatly improved. The metal mesh with the honeycomb network structure provides a large number of active sites and efficient electrolyte permeation channels, so that ions can quickly embed and extract on the electrode surface. This not only shortens the charging and discharging time of the battery, but also significantly improves the power density of the battery.

[0087] Secondly, the high specific surface area of the metal mesh enables the electrode material to accommodate more active substances and store more energy under the same volume or mass. This means that the battery can provide longer battery life or greater energy output under the same battery size.

[0088] In addition, the metal mesh with the honeycomb network structure can effectively buffer the volume change of the electrode material during the charging and discharging process, reducing the structural damage caused by stress concentration. This enables the battery to maintain stable performance during long-term use, prolongs the service life of the battery, and reduces the maintenance and replacement costs of the battery.

[0089] At the same time, the uniform structure and high mechanical strength of the metal mesh enable the electrode material to maintain good stability during battery operation, reducing the safety hazards caused by mechanical damage or structural damage. In addition, efficient ion transmission and uniform electrolyte distribution also reduce the risk of local overheating in the battery, further improving the safety of the battery.

[0090] It should be noted that according to the classification of electrolyte state, the battery of the present application includes solid-state battery, semi-solid-state battery and liquid-state battery. For example, the solid-state battery refers to the battery with solid-state electrolyte.

[0091] The following will be introduced through more specific embodiments.

[0092] Example 1

[0093] The preparation method of the metal mesh of Example 1 includes the following steps:

[0094] Preparation of the stack: a plurality of spaced contact areas 11 are arranged on the surface of the calendered metal foil 1 with a thickness of 0.01 μm, and a plurality of layers of calendered metal foils 1 are stacked along the first direction, and adjacent calendered metal foils 1 are fixedly connected through the contact areas 11 to form a stack. Among them, the calendered metal foil 1 is a copper foil.

[0095] Stretching: after stretching the stack along the first direction, a metal mesh is formed.

[0096] Among them, the specific surface area of the honeycomb mesh of Example 1 is 22.4 m 2The thickness of the metal mesh is 5 mm, the tensile strength of the metal mesh is 200-350 MPa, the thickness d1 of the hole wall of the mesh hole 10 is 0.01 μm, and the volume of the mesh hole 10 accounts for 99.9% of the volume of the metal mesh.

[0097] Example 2

[0098] The preparation method of the metal mesh in Example 2 comprises the following steps:

[0099] Preparation of the stack: a plurality of spaced contact areas 11 are arranged on the surface of the calendered metal foil 1 with a thickness of 0.075 μm, and a plurality of layers of calendered metal foils 1 are stacked along the first direction, and adjacent calendered metal foils 1 are fixedly connected through the contact areas 11 to form a stack. Among them, the calendered metal foil 1 is an aluminum foil.

[0100] Stretching: after stretching the stack along the first direction, a metal mesh is formed, and the obtained metal mesh is as shown in Figure 8 and Figure 9 .

[0101] The specific surface area of the metal mesh in Example 2 is 10 m 2 / g, the thickness of the metal mesh is 5 mm, the tensile strength of the metal mesh is 120-200 MPa, the thickness d1 of the hole wall of the mesh hole 10 is 0.075 μm, and the volume of the mesh hole 10 accounts for 99.9% of the volume of the metal mesh.

[0102] In order to facilitate the understanding of the present application, the following parameter test methods are described:

[0103] Test method of thickness (including test of thickness of calendered metal foil and test of thickness of metal mesh): different calendered metal foils or metal meshes of different materials are tested according to GBT22638.1-2016, GB T36146-2018, GB T5187-2021, GB T41608-2022 and GB T15077-2008, respectively, to detect the corresponding thickness.

[0104] Test method of tensile strength: tensile test is carried out according to GB / T228-2010 metal material room temperature tensile test method to detect the tensile strength.

[0105] Test method of elongation: tensile test is carried out according to GB / T228-2010 metal material room temperature tensile test method to detect the elongation.

[0106] Test method of cross-sectional area and volume of mesh hole: test is carried out according to ISO 15901-2 to detect the cross-sectional area and volume of the mesh hole.

[0107] Method for testing the specific surface area: The metal mesh is tested according to ISO 9277 to determine the specific surface area of the metal mesh.

[0108] While the application has been illustrated and described in connection with certain preferred embodiments thereof, it will be readily apparent to those of ordinary skill in the art that numerous modifications, substitutions, and changes can be made thereto without departing from the spirit and scope of the application as set forth in the appended claims.

Claims

1. A metal mesh, characterized in that, The metal mesh serves as an electrode active material or electrode substrate in the battery. The metal mesh is a honeycomb-shaped grid structure formed by stacking, fixing and connecting and stretching multiple layers of rolled metal foil with a thickness of 0.01μm to 100μm in a first direction. The mesh openings of the metal mesh are through holes, and the mesh openings are formed by the spacing between adjacent rolled metal foils through stretching.

2. A metal mesh, characterized in that, The metal mesh serves as an electrode active material or electrode substrate in the battery. The mesh openings are through holes, and the mesh openings are arranged to form a honeycomb-like grid structure. The mesh openings are formed by the spacing between adjacent rolled metal foils in a multi-layer stacked rolled metal foil. The hole walls between adjacent mesh openings are the base layer of the rolled metal foil, and the thickness of the hole walls is 0.01 μm to 100 μm.

3. A metal mesh as described in claim 1 or 2, characterized in that, The specific surface area of ​​the metal mesh is 0.1 m². 2 / g~100m 2 / g.

4. A metal mesh as described in claim 1 or 2, characterized in that, The rolled metal foil is copper foil, aluminum foil, lithium foil, steel foil, iron foil, or nickel foil.

5. A metal mesh as described in claim 4, characterized in that, When the rolled metal foil is copper foil, the tensile strength of the rolled metal foil is 200-350 MPa; when the rolled metal foil is aluminum foil, the tensile strength of the rolled metal foil is 120-200 MPa; when the rolled metal foil is steel foil, iron foil, or nickel foil, the tensile strength of the rolled metal foil is 400-700 MPa; when the rolled metal foil is lithium foil, the tensile strength of the rolled metal foil is 30-100 MPa.

6. A metal mesh as described in claim 1 or 2, characterized in that, The surface roughness (Rz) of the rolled metal foil is 0.6 to 1.5 μm.

7. A metal mesh as described in claim 1 or 2, characterized in that, The cross-sectional shape of the mesh is quadrilateral or hexagonal.

8. A metal mesh as described in claim 1 or 2, characterized in that, The wall thickness of the mesh between adjacent mesh openings is 0.01 μm to 1 μm.

9. A metal mesh as described in claim 1 or 2, characterized in that, The volume of the plurality of mesh openings accounts for 75% to 99.994% of the volume of the metal mesh.

10. A metal mesh as described in claim 1 or 2, characterized in that, The thickness of the metal mesh is 0.1 mm to 50 mm.

11. A method for preparing a metal mesh, characterized in that, The method for preparing the metal mesh as described in any one of claims 1-10 comprises the following steps: Preparation of the stack: Multiple spaced contact areas are set on the surface of a rolled metal foil with a thickness of 0.01μm to 100μm. Multiple layers of the rolled metal foil are stacked along a first direction. Adjacent rolled metal foils are fixedly connected through the contact areas to form a stack. Stretching: The stack is stretched along the first direction to form the metal mesh.

12. The method for preparing a metal mesh as described in claim 11, characterized in that, The fixing method is adhesive bonding or welding.

13. An electrode material, characterized in that, It includes the metal mesh as described in any one of claims 1 to 10, or the metal mesh obtained by the preparation method as described in claim 11 or 12.

14. A battery, characterized in that, Includes the electrode material as described in claim 13.

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