Wire-clip structure electrode, device for preparing wire-clip structure electrode and application thereof

Abstract

The present invention provides a wire-sandwich structure electrode, a device for preparing the wire-sandwich structure electrode, and an application thereof, wherein the wire-sandwich structure electrode comprises at least two layers of stacked mesh current collectors and an electrode active material disposed inside and / or on the surface of the mesh current collector. The wire-sandwich structure electrode of the present invention improves electrical conductivity, electrolyte wettability, peel strength, and surface density, and further improves the energy density of the electrochemical device.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries and relates to a wire-clamped structure electrode, a device for preparing the wire-clamped structure electrode and applications. Background Art

[0002] Lithium-ion batteries are widely used in various mobile or fixed energy storage scenarios such as new energy vehicles, consumer electronics, and energy storage. As people's requirements for the energy density of lithium-ion batteries continue to increase, the material system and cell design of the battery are facing huge challenges. Under a specific material system, if the battery energy density needs to be further improved, it is necessary to increase the compaction density of the pole piece and the surface density of the active material dressing. However, excessive pole piece thickness and compaction density will lead to excessive obstacles such as electron conduction and ion diffusion in the electrolyte, resulting in uneven lithium extraction and extraction of active materials at different positions of the pole piece, affecting capacity utilization and cycle performance, and even leading to lithium precipitation, causing a series of battery performance problems. These problems restrict the further improvement of battery energy density.

[0003] In the existing technology, the research on improving the energy density of electrochemical devices mainly focuses on optimizing the material system, and the research on the optimization of the battery cell electrode structure and the production equipment is still relatively small. Therefore, optimizing the electrode structure and developing efficient production equipment are of great significance to the further development of electrochemical devices. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a wire-sandwich structure electrode, a device for preparing a wire-sandwich structure electrode and its application. The wire-sandwich structure electrode of the present invention comprises at least two layers of stacked mesh current collectors and an electrode active material arranged inside and / or on the surface of the mesh current collector. The wire-sandwich structure electrode improves the transmission performance of electrons and lithium ions, enhances the peeling strength of the electrode, improves the wettability of the electrolyte, improves the surface density of the electrode, and further improves the energy density of the electrochemical device.

[0005] In the present invention, the mesh current collector refers to a current collector having evenly distributed mesh holes on its surface, and the mesh holes may be in any shape of polygonal or circular holes.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a wire-sandwich structure electrode, which includes at least two stacked mesh current collectors and an electrode active material disposed inside and / or on the surface of the mesh current collector.

[0008] In the present invention, the number of layers of the mesh current collector is at least 2, for example, it can be 2, 3, 4, 2, 3, 4, 6, 10, 15, 20, 25, 50 or 100 layers.

[0009] The wire-sandwich structure electrode of the present invention comprises at least two layers of stacked mesh current collectors and electrode active materials arranged inside and / or on the surface of the mesh current collectors, and the mesh current collectors are interspersed inside the active layer formed by the electrode active materials to form a wire-sandwich structure; the wire-sandwich structure electrode improves the transmission performance of electrons and lithium ions, enhances the peeling strength of the electrode, improves the wettability of the electrolyte, improves the surface density of the electrode, and further improves the energy density of the electrochemical device. The technical principle of the present invention is as follows:

[0010] First, the at least two-layer mesh current collector has the function of a conventional current collector, and can cooperate with each other between the multiple layers, act as a conductive agent, dispersed in the wire structure electrode, promote the transmission of electrons between layers, improve electronic conductivity, reduce the amount of conductive agent, and improve the diffusion performance of ions. Taking lithium-ion batteries as an example, it can enhance the diffusion uniformity of lithium ions in the battery, which is beneficial to reduce the internal resistance of the battery; second, the multi-layer mesh current collector can act as the skeleton of the electrode, interspersed in the electrode active material, and can form a strong bond with the electrode active material, significantly enhance the peel strength, further reduce the lower limit of the amount of binder used, improve the kinetic performance of the lithium ion transmission interface, and reduce the impedance of the battery; third, the traditional electrode is limited by the current collector. The electrolyte can only diffuse downward from the top of the current collector or diffuse in parallel to the current collector, but cannot pass through the current collector. The electrode based on the multi-layer mesh current collector proposed in the present invention allows the electrolyte to diffuse from any direction without being hindered, greatly enhancing the consistency of electrolyte diffusion, improving the wettability of the electrolyte, enhancing the consistency of lithium ion concentration, increasing the liquid retention rate, and further improving the battery performance; Fourth, the multi-layer mesh current collector of the present invention occupies a small space, and the multiple layers act synergistically with each other, which is conducive to reducing internal resistance, enhancing peel strength and electrolyte wettability, and increasing surface density. Even when the electrode plate is thicker, it can still maintain good electrochemical performance, thereby improving the design upper limit of the electrochemical device and obtaining an electrochemical device with higher energy density.

[0011] The mesh current collector in the wire-sandwich structure electrode of the present invention cannot be set with only one layer, because the single-layer mesh current collector cannot meet the requirements of high dressing surface density using the coating equipment of the present invention. Even if the surface density is high, its electronic conductivity will be worse than that of the multi-layer mesh wire-sandwich current collector recommended by the present invention.

[0012] Preferably, the number of layers of the mesh current collector is 2 to 50, and a suitable range of layers can achieve better electronic conduction performance and electrode structure support function.

[0013] Preferably, the mesh current collector includes any one of nickel mesh, aluminum mesh or copper mesh, or a combination of at least two of them, for example, it can be a combination of nickel mesh and aluminum mesh, a combination of nickel mesh and copper mesh, a combination of aluminum mesh and copper mesh, or a combination of nickel mesh, aluminum mesh and copper mesh, etc.

[0014] Preferably, the mesh current collector has a thickness of 5 μm to 300 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm or 300 μm, etc.

[0015] Preferably, the thickness of the mesh current collector is 8 μm to 100 μm. Within this range, the multi-layer mesh current collectors have a better coordination effect, which is more conducive to achieving good conductivity and electrolyte infiltration performance, and the prepared wire-structured electrode has better electrochemical performance.

[0016] As a preferred technical solution for the wire-structured electrode of the present invention, the porosity of the mesh current collector is 0% to 98%, and does not include 0%, for example, it can be 0.01%, 0.1%, 1%, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 98%, etc.

[0017] In the present invention, the porosity refers to the ratio of the area of ​​the mesh holes uniformly distributed on the surface of the mesh current collector to the overall area of ​​the mesh current collector. The shape of the holes is not limited and can be any polygon or circle.

[0018] Preferably, the porosity of the mesh current collector is 40% to 98%.

[0019] In the present invention, selecting a current collector with a suitable porosity is beneficial to achieving both high energy density and high electronic conductivity.

[0020] Preferably, the thickness of the wire structure electrode is 80 μm to 3000 μm, for example, it can be 80 μm, 100 μm, 120 μm, 150 μm, 200 μm, 300 μm, 400 μm, 500 μm, 800 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm or 3000 μm.

[0021] Preferably, the thickness of the wire-sandwich structure electrode is 80 μm to 1000 μm.

[0022] In the present invention, in order to better meet the electrochemical performance requirements of the electrode sheet, the porosity of the mesh current collector should match the thickness of the wire-sandwich structure electrode; when the wire-sandwich structure electrode is thicker, the porosity of the mesh current collector should be appropriately reduced to reduce the impedance while ensuring the energy requirements of the battery; conversely, when the wire-sandwich structure electrode is thinner, the porosity of the mesh current collector should be appropriately increased to increase the content of active substances in the electrode, thereby improving the energy density of the electrode, so that the wire-sandwich structure electrode has both higher energy density and smaller impedance.

[0023] In a second aspect, the present invention provides an electrochemical device, wherein the electrochemical device comprises the wire-sandwich structure electrode according to the first aspect.

[0024] In the electrochemical device of the present invention, there is no limitation on the application of the wire structure electrode to the positive electrode and / or the negative electrode. The positive electrode in the electrochemical device may be the wire structure electrode, the negative electrode in the electrochemical device may be the wire structure electrode, or both the positive electrode and the negative electrode in the electrochemical device may be the wire structure electrode.

[0025] The electrochemical device of the present invention has lower internal resistance and higher energy density.

[0026] In a third aspect, the present invention provides an electronic device, comprising the electrochemical device described in the second aspect.

[0027] In a fourth aspect, the present invention provides a device for preparing the wire-structured electrode described in the first aspect, the device comprising an unwinding device, a coating device, a drying device, a rolling device and a winding device arranged in sequence, at least two unwinding devices are provided, and a guide roller group is provided between the coating device and the drying device.

[0028] The device for preparing a wire-sandwich structure electrode of the present invention comprises a plurality of unwinding devices, a coating device, a drying device, a rolling device and a winding device which are arranged in sequence. A plurality of mesh current collectors can enter the coating device through different unwinding devices to be soaked in slurry for coating, and enter the drying device and the rolling device through the guide roller group for subsequent drying and rolling, and finally winding. The device of the present invention is provided with a plurality of unwinding devices, which can adjust the number of layers of the mesh current collector and the surface density of the wire-sandwich structure electrode, can efficiently and continuously produce high surface density electrodes, and is conducive to the industrial production of high surface density and high energy density electrodes.

[0029] Preferably, the guide roller set is used to stack at least two layers of coated mesh current collectors together.

[0030] The guide roller group in the present invention is used to stack at least two layers of coated mesh current collectors together. Exemplarily, the guide roller group may include multiple rollers, and the multiple rollers guide the stacking of multiple layers of mesh current collectors to achieve a continuous separation-merging coating method. A certain distance may be left between the multiple layers of mesh current collectors, which can prevent the loss of the slurry coated on the mesh current collector and ensure a high surface density, while also preventing the surface density of the electrode from being reduced after the mesh current collector accounts for too large a proportion.

[0031] Preferably, an ultrasonic device is provided in the coating device, which is conducive to quickly filling the coated slurry into the mesh current collector.

[0032] Preferably, the drying device comprises a floating material removing device and a heating device.

[0033] In the present invention, when at least two layers of coated mesh current collectors are stacked and enter a drying device, a floating material removal device in the drying device can not only remove excess slurry adhered to the surface of the mesh current collector, but also control the total thickness of the mesh current collector coated with the slurry before drying. Subsequently, the coated mesh current collector enters a heating device for drying. Through continuous separation-combination coating and subsequent drying and rolling processes, the multi-layer mesh current collector is produced as a wire-structured electrode. The thickness of the electrode can be controlled between 80 μm and 3000 μm, and the production efficiency is relatively high.

[0034] Exemplarily, the floating material removal device may be two scrapers with adjustable spacing, a length greater than the length of the current collector, and both being parallel to the current collector.

[0035] The temperature of the heating device in the present invention can be adjusted according to demand. Exemplarily, the temperature of the heating device is 25°C to 200°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 50°C, 60°C, 70°C, 80°C, 100°C, 150°C or 200°C, etc.

[0036] As a preferred technical solution of the device described in the present invention, conveying devices are arranged on both sides of the rolling device, and the radius of the conveying device is 0.5m to 5m, for example, it can be 0.5m, 0.8m, 1m, 1.5m, 2m, 2.5m, 3m, 4m, 4.5m or 5m, etc.

[0037] The radius of the transmission device of the present invention refers to the distance from the edge of the transmission device to the axis.

[0038] The conveying device in the present invention has a relatively large radius (≥0.5 m), which can reduce the bending stress between the interlayers of the multi-layer mesh current collector.

[0039] When the device of the present invention is in use, the theoretical coating surface density of the wire-structured electrode can be calculated by recording the number of layers of the mesh current collector, the thickness of the electrode sheet before drying, and the solid content of the slurry, and the surface density can be controlled by adjusting the thickness of the floating material removed by the floating material removal device and the gap between the multi-layer mesh current collectors controlled by the guide roller group.

[0040] In a fifth aspect, the present invention provides a method for preparing a wire-structured electrode using the device described in the fourth aspect, the method comprising:

[0041] (1) passing at least two layers of mesh current collectors through unwinding devices respectively, and immersing them in the electrode active material slurry in the coating device, and then laminating the at least two layers of coated mesh current collectors through a guide roller group and entering a drying device, scraping off the excess slurry on the surface of the mesh current collector through a floating material removal device, and controlling the thickness of the mesh current collector to be 80 μm to 3000 μm, adjusting the temperature of the heating device to be 25° C. to 200° C., and drying;

[0042] (2) The product after drying in step (1) is passed through a conveying device with a radius of 0.5 m to 5 m into a rolling device for rolling, and then passed through the conveying device and then into a winding device for winding, thereby obtaining the wire-clamped structure electrode.

[0043] Preferably, an ultrasonic device is provided in the coating device.

[0044] Preferably, when at least two layers of coated mesh current collectors are stacked through a guide roller group and enter the drying device, at least two layers of coated mesh current collectors are stacked with a certain distance between them and enter the drying device. The reason for maintaining a certain distance is to prevent the loss of the slurry coated on the mesh current collector and ensure a high surface density, while also preventing the mesh current collector from accounting for too large a proportion and causing the weight of the electrode to account for a high proportion.

[0045] Preferably, when at least two layers of coated mesh collectors are stacked through a guide roller group and enter the drying device, at least two layers of coated mesh collectors enter the drying device in a direction perpendicular to the ground plane. The reason for entering perpendicular to the ground plane is to prevent the slurry from flowing through the mesh holes in a direction perpendicular to the collector before drying.

[0046] Exemplarily, the at least two layers of coated mesh current collector enter the drying device in a direction perpendicular to the ground plane, and the method of entering perpendicular to the ground plane is to set the drying device perpendicular to the ground plane.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The wire-sandwich structure electrode of the present invention comprises an electrode active material and at least two layers of mesh current collectors interspersed therein. The wire-sandwich structure electrode improves the transmission performance of electrons and lithium ions, enhances the peeling strength of the electrode, improves the wettability of the electrolyte, and improves the surface density of the electrode, thereby further improving the energy density of the electrochemical device.

[0049] (2) The device for preparing the wire-sandwich structure electrode of the present invention comprises a plurality of unwinding devices, coating devices, drying devices, rolling devices and winding devices arranged in sequence. A plurality of mesh current collectors can enter the coating device through different unwinding devices to be soaked in slurry for coating, and then be stacked together through a guide roller group for subsequent drying, rolling and winding. The device of the present invention is provided with a plurality of unwinding devices, which can adjust the number of layers of the mesh current collector and the surface density of the wire-sandwich structure electrode, and can efficiently and continuously produce high surface density electrodes, which is conducive to the industrial production of high surface density and high energy density electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of a wire-clamped structure electrode in a specific embodiment of the present invention.

[0051] Figure 2 It is a cross-sectional view of a wire-sandwich structure electrode in a specific embodiment of the present invention.

[0052] Figure 3 It is a schematic structural diagram of a device for preparing a wire-structured electrode in a specific embodiment of the present invention.

[0053] Among them, 1-net-shaped current collector 1; 2-electrode active material; 3-unwinding device; 4-coating device; 5-guide roller group; 6-drying device; 7-transmission device; 8-rolling device; 9-winding device. DETAILED DESCRIPTION

[0054] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0055] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0056] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0057] In a specific embodiment, the present invention provides a wire-clamped structure electrode, the structural schematic diagram of which is as follows: Figure 1 As shown, the wire-sandwich structure electrode includes at least two stacked layers of mesh current collectors 1 and an electrode active material 2 arranged inside and / or on the surface of the mesh current collector 1 .

[0058] The wire-sandwich structure electrode of the present invention comprises at least two layers of stacked mesh current collectors 1 and an electrode active material 2 arranged inside and / or on the surface of the mesh current collector 1. The cross-sectional view thereof is as follows: Figure 2 As shown, electrons (e) can be conducted up and down through the multi-layer mesh current collector 1. This wire-structured electrode improves the transmission performance of electrons and lithium ions, enhances the peeling strength of the electrode, and the electrolyte can diffuse in all directions through the mesh current collector 1 to improve the wettability of the electrolyte, increase the surface density of the electrode, and further improve the energy density of the electrochemical device.

[0059] In the present invention, there is no limitation on using the wire-sandwich structure electrode as the positive electrode and / or the negative electrode.

[0060] In one embodiment, the wire-sandwich structure electrode is used as the positive electrode, and the electrode active material 2 includes any one of lithium iron phosphate (LFP), lithium manganese oxide (LMO), lithium nickel oxide (LNO), nickel-cobalt-manganese ternary material (NCM), nickel-cobalt-aluminum ternary material (NCA) or nickel-cobalt-manganese-aluminum quaternary material (NCMA) or a combination of at least two thereof.

[0061] In one embodiment, the wire-sandwich structure electrode is used as the negative electrode, and the electrode active material 2 includes graphite, hard carbon, soft carbon, lithium titanate (LTO), Si, SiO x Or any one of Sn or a combination of at least two of them.

[0062] Furthermore, the number of layers of the mesh current collector 1 is 2 to 50.

[0063] Furthermore, the mesh current collector 1 includes any one of a nickel mesh, an aluminum mesh or a copper mesh, or a combination of at least two of them.

[0064] Furthermore, the mesh current collector 1 has a thickness of 5 μm to 300 μm.

[0065] Furthermore, the mesh current collector 1 has a thickness of 8 μm to 100 μm.

[0066] Furthermore, the porosity of the mesh current collector 1 is 0% to 98%, excluding 0%.

[0067] Furthermore, the porosity of the mesh current collector 1 is 40% to 98%.

[0068] Furthermore, the thickness of the wire-sandwich structure electrode is 80 μm to 3000 μm.

[0069] Furthermore, the thickness of the wire-sandwich structure electrode is 80 μm to 150 μm.

[0070] In a specific embodiment, the present invention also provides a device for preparing a wire-clamped structure electrode, the structural schematic diagram of which is as follows: Figure 3 As shown, the device includes an unwinding device 3, a coating device 4, a drying device 6, a rolling device 8 and a winding device 9 which are arranged in sequence, at least two unwinding devices 3 are provided, and a guide roller group 5 is provided between the coating device 4 and the drying device 6.

[0071] The device for preparing a wire-sandwich structure electrode of the present invention comprises a plurality of unwinding devices 3, a coating device 4, a drying device 6, a rolling device 8 and a winding device 9 which are arranged in sequence. A plurality of mesh current collectors 1 can enter the coating device 4 through different unwinding devices 3 to be soaked in slurry for coating, and enter the drying device 6 and the rolling device 8 through a guide roller group 5 for subsequent drying and rolling, and finally winding. The device of the present invention is provided with a plurality of unwinding devices 3, which can adjust the number of layers of the mesh current collector 1 and the surface density of the wire-sandwich structure electrode, can efficiently and continuously produce high surface density electrodes, and is conducive to the industrial production of high surface density and high energy density electrodes.

[0072] Furthermore, the guide roller set 5 is used to stack the coated mesh current collectors 1 together.

[0073] Furthermore, an ultrasonic coating device is provided in the coating device 4 .

[0074] Furthermore, the drying device 6 includes a floating material removing device and a heating device.

[0075] Furthermore, conveying devices 7 are provided on both sides of the rolling device 8, and the radius of the conveying device 7 is 0.5m to 5m.

[0076] In another specific embodiment, a method for using the above-mentioned device for preparing a wire-structured electrode is provided, and the method for using the device comprises:

[0077] (1) at least two layers of mesh current collector 1 are respectively passed through an unwinding device 3 and immersed in a slurry of an electrode active material 2 in a coating device 4, wherein an ultrasonic device is provided in the coating device 4, and then stacked at a certain interval through a guide roller group 5 into a drying device 6, and the excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device, and the thickness thereof is controlled to be 80 μm to 3000 μm, and the temperature of the heating device is adjusted to be 25° C. to 200° C., and then dried;

[0078] (2) The product after drying in step (2) is passed through a conveying device 7 with a radius of 0.5 m to 5 m and enters a rolling device 8 for rolling. After being transmitted through the conveying device 7, it enters a winding device 9 for winding, thereby obtaining the wire-clamped structure electrode.

[0079] Example 1

[0080] This embodiment provides a method for preparing a wire-sandwich structure electrode for a positive electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0081] (1) Three layers of mesh current collectors 1 are respectively passed through an unwinding device 3 and immersed in the electrode active material 2 slurry (the active material is NCM ternary material) in a coating device 4. The mesh current collector 1 is an aluminum mesh with a thickness of 20 μm and a porosity of 80%. The transmission rate is 20 m / min. The coating device 4 is provided with an ultrasonic device. Then, the mesh current collectors 1 are stacked at a certain distance through a guide roller group 5 and enter a drying device 6. The excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device. The temperature of the heating device is adjusted to 100° C. and the mesh current collectors are dried.

[0082] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 0.5 m to a rolling device 8 for rolling. After being transmitted through the conveying device 7, it is passed through a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 150 μm.

[0083] This embodiment also provides a method for preparing a wire-sandwich structure electrode for a negative electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0084] (1) The two layers of mesh current collectors 1 are respectively passed through the unwinding device 3 and immersed in the electrode active material 2 slurry (active material is graphite / SiO x The mesh current collector 1 is a copper mesh with a thickness of 20 μm and a porosity of 80%. The transmission rate is 20 m / min. The coating device 4 is provided with an ultrasonic device. Then, the mesh current collector 1 is stacked at a certain distance through the guide roller group 5 and enters the drying device 6. The excess slurry on the surface of the mesh current collector 1 is scraped off by the floating material removal device. The temperature of the heating device is adjusted to 80° C. and dried.

[0085] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 0.5 m to a rolling device 8 for rolling. After being transmitted through the conveying device 7, it is passed through a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 100 μm.

[0086] Example 2

[0087] This embodiment provides a method for preparing a wire-sandwich structure electrode for a positive electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0088] (1) Passing 5 layers of mesh current collector 1 through unwinding device 3, respectively, and immersing them in the electrode active material 2 slurry (active material is NCM ternary material) in coating device 4. The mesh current collector 1 is an aluminum mesh with a thickness of 40 μm and a porosity of 90%. The transmission rate is 10 m / min. The coating device 4 is provided with an ultrasonic device. Then, the mesh current collector 1 is stacked at a certain distance through guide roller group 5 and enters drying device 6. The excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device. The temperature of the heating device is adjusted to 110° C. and dried.

[0089] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 1.0 m to a rolling device 8 for rolling, and then passed through the conveying device 7 to a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 400 μm.

[0090] This embodiment also provides a method for preparing a wire-sandwich structure electrode for a negative electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0091] (1) Five layers of mesh current collector 1 are respectively passed through unwinding device 3 and immersed in the electrode active material 2 slurry (active material is graphite) in coating device 4. The mesh current collector 1 is a copper mesh with a thickness of 40 μm and a porosity of 90%. The transmission rate is 10 m / min. The coating device 4 is provided with an ultrasonic device. Then, the five layers of mesh current collector 1 are stacked at a certain distance through guide roller group 5 and enter drying device 6. The excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device. The temperature of the heating device is adjusted to 90° C. and the mesh current collector 1 is dried.

[0092] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 1.0 m to a rolling device 8 for rolling. After being transmitted through the conveying device 7, it is passed through a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 300 μm.

[0093] Example 3

[0094] This embodiment provides a method for preparing a wire-sandwich structure electrode for a positive electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0095] (1) 10 layers of mesh current collector 1 are respectively passed through unwinding device 3 and immersed in the electrode active material 2 slurry (active material is NCM ternary material) in coating device 4. The mesh current collector 1 is an aluminum mesh with a thickness of 70 μm and a porosity of 70%. The transmission rate is 5 m / min. The coating device 4 is provided with an ultrasonic device. Then, the mesh current collector 1 is stacked at a certain distance through a guide roller group 5 and enters a drying device 6. The excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device. The temperature of the heating device is adjusted to 100° C. and dried.

[0096] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 2.0 m to a rolling device 8 for rolling. After being transmitted through the conveying device 7, it is passed through a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 1200 μm.

[0097] This embodiment also provides a method for preparing a wire-sandwich structure electrode for a negative electrode, based on a device for preparing a wire-sandwich structure electrode provided in a specific embodiment, the structural schematic diagram is as follows Figure 3 As shown, the preparation method comprises:

[0098] (1) Eight layers of mesh current collectors 1 are respectively passed through an unwinding device 3 and immersed in the electrode active material 2 slurry (active material is SiOx) in a coating device 4. The mesh current collector 1 is a copper mesh with a thickness of 70 μm and a porosity of 70%. The transmission rate is 5 m / min. The coating device 4 is provided with an ultrasonic device. Then, the mesh current collectors 1 are stacked at a certain distance through a guide roller group 5 and enter a drying device 6. The excess slurry adhered to the surface of the mesh current collector 1 is scraped off by a floating material removal device. The temperature of the heating device is adjusted to 60° C. and the mesh current collectors are dried.

[0099] (2) The product after drying in step (1) is passed through a conveying device 7 with a radius of 2.0 m to a rolling device 8 for rolling. After being transmitted through the conveying device 7, it is passed through a winding device 9 for winding, thereby obtaining a wire-clamped structure electrode with a thickness of 800 μm.

[0100] The formulas of the electrolyte and the positive and negative electrode slurries in the present invention are as follows:

[0101] Electrolyte formula: main solvent: the mass ratio of ethyl cellulose (EC) and ethyl methyl carbonate (EMC) is 30:70; the concentration of LiPF6 is 1 mol / L; additives: the mass ratio of fluoroethylene carbonate (FEC), ethylene carbonate (VC) and difluorooxalyl boric acid (DFOB) is 10:1:1 (with the main solvent as 100%).

[0102] Positive electrode slurry formula: Positive electrode active material, polyvinylidene fluoride (PVDF), conductive carbon black (SP) and conductive carbon tube (CNT) are dissolved in N-methylpyrrolidone solvent (NMP) in a mass ratio of 95:3:1.5:0.5 to obtain positive electrode slurry.

[0103] Negative electrode slurry formula: negative electrode active material, sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), conductive carbon black (SP) and conductive carbon tube (CNT) are dissolved in deionized water in a mass ratio of 95:1.5:2:1:0.5 to obtain negative electrode slurry.

[0104] The test parameters of the electrochemical performance in the present invention are as follows: the battery performance test system (equipment model: BTS05 / 10C8D-HP) of Shenghong Electric Co., Ltd. is used to test the energy density and cycle performance of the electrochemical devices in the embodiments and comparative examples of the present invention, wherein:

[0105] Energy density test: 25℃, 0.5C charge to 4.25V, constant voltage to 0.05C; 0.2C discharge to 2.5V.

[0106] Cycle test: 25℃, 0.5C charge to 4.25V, constant voltage to 0.05C; 0.5C discharge to 2.5V.

[0107] The surface densities of the positive electrode sheets and the negative electrode sheets in Examples 1 to 9 and Comparative Examples 1 to 2, and the performance test results of lithium-ion batteries prepared using the electrode sheets in Examples 1 to 9 and Comparative Examples 1 to 2 are shown in Tables 1 to 5.

[0108] Table 1

[0109]

[0110] Examples 4 to 9 and Comparative Examples 1 to 2 are based on the steps of Example 1 with parameter changes. The specific changed parameters and test results are shown in Tables 2 to 5.

[0111] Table 2

[0112]

[0113] By comparing Example 1 and Examples 4 to 5 in Table 2, it can be seen that the thickness of the mesh current collector 1 of the present invention will affect the electrochemical properties of the prepared wire-structured electrode; when the thickness of the mesh current collector 1 is too high, the internal resistance and cycle are not significantly improved, but the energy density is sacrificed too much; when the thickness of the mesh current collector 1 is too thin, the internal resistance and cycle are both deteriorated, therefore, the energy density or cycle performance of Examples 4 to 5 is slightly worse than that of Example 1.

[0114] Table 3

[0115]

[0116] By comparing Example 1 and Examples 6 to 7 in Table 3, it can be seen that the porosity of the mesh current collector 1 of the present invention will affect the electrochemical properties of the prepared wire structure electrode; when the porosity of the mesh current collector 1 is high, the method cannot prepare the electrode sheet and the battery cell preparation cannot be completed due to the large porosity; when the porosity of the mesh current collector 1 is low, there is no obvious improvement in battery impedance and cycle, but the battery energy density is greatly sacrificed. Therefore, the processability function and energy density performance of Examples 6 to 7 are slightly worse than those of Example 1.

[0117] Table 4

[0118]

[0119] By comparing Example 1 with Examples 8 to 9 in Table 4, it can be seen that the thickness of the wire-sandwich structure electrode of the present invention will affect its electrochemical performance. The mesh current collector 1 contained in the wire-sandwich structure electrode remains unchanged. When the wire-sandwich structure electrode is thicker, the battery impedance increases significantly and the cycle attenuation deteriorates significantly. When the wire-sandwich structure electrode is thinner, the battery energy density is greatly sacrificed. Therefore, the solution of Example 1 is better, taking into account both the battery energy density and the cycle performance.

[0120] Table 5

[0121]

[0122]

[0123] By comparing Example 1 and Comparative Examples 1 to 2 in Table 5, it can be seen that the stacking of a suitable number of layers of the mesh current collector 1 in the present invention is more conducive to improving the electrochemical performance of the prepared wire structure electrode; when there is only one layer of the mesh current collector 1, the electrode surface density cannot reach a high level, and the battery energy density is not significantly improved; when the mesh current collector 1 is not used and a conventional current collector copper foil is used instead of the mesh current collector 1 copper mesh, the battery impedance increases significantly and the cycle deteriorates significantly. Therefore, the energy density and cycle performance of Comparative Examples 1 to 2 are worse than those of Example 1.

[0124] From the above Examples 1 to 9, it can be seen that the wire-structured electrode of the present invention comprises at least two stacked layers of mesh current collectors 1 and an electrode active material 2 arranged inside and / or on the surface of the mesh current collector 1. This wire-structured electrode improves the transmission performance of electrons and lithium ions, enhances the peeling strength of the electrode, improves the wettability of the electrolyte, improves the surface density of the electrode, and further improves the energy density of the electrochemical device.

[0125] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a wire-sandwich structure electrode, characterized in that: The wire-sandwich structure electrode comprises at least two layers of stacked mesh current collectors and an electrode active material arranged inside and / or on the surface of the mesh current collector; The porosity of the mesh current collector is 0% to 98%, excluding 0%; there is a gap between the mesh current collector layers; the thickness of the wire structure electrode is 80 μm to 3000 μm; The method adopts an electrode preparation device, which includes an unwinding device, a coating device, a drying device, a rolling device and a winding device arranged in sequence, wherein at least two unwinding devices are provided, and a guide roller group is provided between the coating device and the drying device; the drying device includes a floating material removal device and a heating device; The method comprises: (1) passing at least two layers of mesh current collectors through unwinding devices respectively, and immersing them in the electrode active material slurry in the coating device, and then stacking the at least two layers of coated mesh current collectors through a guide roller group and entering a drying device, leaving a gap between the mesh current collector layers, scraping off the excess slurry on the surface of the mesh current collector through a floating material removal device, and controlling the thickness of the mesh current collector to be 80 μm to 3000 μm, adjusting the temperature of the heating device to be 25° C. to 200° C., and drying; (2) The product after drying in step (1) is passed through a conveying device with a radius of 0.5 m to 5 m into a rolling device for rolling, and then passed through the conveying device and then into a winding device for winding, thereby obtaining the wire-clamped structure electrode.

2. The method according to claim 1, characterized in that The wire-clip structure electrode satisfies at least one of the following conditions (a) to (f): (a) The number of layers of the mesh current collector is 2 to 50; (b) the mesh current collector comprises any one of a nickel mesh, an aluminum mesh or a copper mesh, or a combination of at least two of them; (c) the thickness of the mesh current collector is 5 μm to 300 μm; (d) the thickness of the mesh current collector is 8 μm to 100 μm; (e) the porosity of the mesh current collector is 40% to 98%; (f) The thickness of the wire-sandwich structure electrode is 80 μm to 1000 μm.

3. An electrochemical device, characterized in that: The electrochemical device comprises a wire-sandwich structure electrode prepared according to the method of claim 1 or 2.

4. An electronic device, characterized in that: The electronic device comprises the electrochemical device according to claim 3.

5. The method according to claim 1, characterized in that The guide roller group is used to stack at least two layers of coated mesh current collectors together.

6. The method according to claim 1, characterized in that An ultrasonic device is arranged in the coating device.

7. The method according to claim 1, characterized in that Conveying devices are arranged on both sides of the rolling device, and the radius of the conveying devices is 0.5m to 5m.

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