Corrosion roller, corrosion equipment, metal layer and processing method thereof, current collector, pole piece, electrode assembly, secondary battery and electric device

Abstract

The invention relates to a corrosion roller, corrosion equipment, a metal layer, a processing method of the metal layer, a current collector, a pole piece, an electrode assembly, a secondary battery and an electric device, a conveying channel is arranged in a roller body in an extending mode in the axis direction, and corrosion liquid in the conveying channel is conveyed into a corrosion part through a discharge hole; and then the corrosion roller is discharged from the corrosion part to the outside of the corrosion roller. Therefore, when the metal layer is corroded and the corrosion part is in contact with the metal layer, corrosive liquid can be output to the metal layer, so that the surface of the metal layer is effectively corroded. Due to the fact that the corrosive liquid is output from the inside of the corrosion roller to the outside and is finally output on the corrosion part, fixed-point corrosion is achieved, the liquid outlet amount can be conveniently and accurately controlled, corrosion on the metal layer is more uniform and reliable, the corrosion effect is improved, the binding force on the metal layer is improved, and the reliability of the battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery preparation, and particularly to a corrosion roller, a corrosion device, a metal layer and a processing method thereof, a current collector, a pole piece, an electrode assembly, a secondary battery and an electrical device. Background Art

[0002] Lithium-ion batteries are widely used in electric vehicles and consumer electronic products due to their characteristics of large energy density, high output power, long cycle life and low environmental pollution. As a main component of a lithium-ion battery, a pole piece generally includes a current collector and an active layer provided on a metal layer of the current collector. In order to make the metal layer and the active layer combine, the surface of the metal layer is roughened. However, due to the design of the structure of traditional roughening equipment, the bonding force between the active layer and the metal layer is insufficient, affecting the reliability of the battery. Summary of the Invention

[0003] Based on this, it is necessary to provide a corrosion roller, a corrosion device, a metal layer and a processing method thereof, a current collector, a pole piece, an electrode assembly, a secondary battery and an electrical device, which can improve the corrosion effect, enhance the bonding force on the metal layer, and thus enhance the reliability of the battery.

[0004] In a first aspect, the present application provides a corrosion roller, which includes: a roller body, along which a conveying channel extends in the axial direction; a corrosion part, provided on the roller body, a discharge hole is provided on the inner wall of the conveying channel, the discharge hole extends to the corrosion part and is used to communicate with the outside of the corrosion roller on the corrosion part.

[0005] For the above corrosion roller, a conveying channel is arranged to extend in the axial direction inside the roller body, and the corrosion liquid in the conveying channel is conveyed to the corrosion part through the discharge hole; and then discharged from the corrosion part to the outside of the corrosion roller. In this way, when corroding the metal layer, the corrosion part can output the corrosion liquid to the metal layer when contacting it, so as to effectively corrode the surface of the metal layer. Since the corrosion liquid is output from the inside to the outside of the corrosion roller and finally output on the corrosion part, not only fixed-point corrosion is realized, but also the liquid discharge amount can be accurately controlled, making the corrosion on the metal layer more uniform and reliable, improving the corrosion effect, being beneficial to enhancing the bonding force on the metal layer, and thus enhancing the reliability of the battery.

[0006] In some embodiments, the hole area of the discharge hole is denoted as S1, where 1 mm 2 ≤ S1 ≤ 10 mm 2 . With such a design, by controlling the hole area S1 between 1 mm 2 and 10 mm 2 , on the premise of achieving effective roughness, the smoothness of liquid discharge and the corrosion cost can be effectively balanced.

[0007] In some embodiments, the pore area S1 further satisfies the condition that: 3mm 2 ≤S1≤7mm 2 .

[0008] In some embodiments, the roller body has a roller surface circumferentially arranged around its own axis, and at least part of the corrosion part is arranged on the roller surface; and / or, at least part of the corrosion part is arranged inside the roller body, and the end far from the conveying channel is not lower than the roller surface. With such a design, the corrosion part is reasonably arranged on the roller body, which is convenient for the corrosion part to effectively corrode on the metal layer, increase the roughness of the metal layer, and improve the bonding force on the metal layer.

[0009] In some embodiments, the corrosion part includes a groove, the groove is arranged inside the roller body, and the end far from the conveying channel is not lower than the roller surface, and the discharge hole communicates with the outside of the corrosion roller through the groove. With such a design, the corrosion liquid is designed into the structure of the groove, which is convenient for effectively corroding the surface of the metal layer and improving the roughness of the metal layer.

[0010] In some embodiments, the dimension of the end of the groove far from the conveying channel in the axial direction is smaller than the dimension of the end of the groove close to the conveying channel in the axial direction. With such a design, it is convenient to concentrate and output the corrosion liquid outward, achieve better fixed-point corrosion, and improve the corrosion effect.

[0011] In some embodiments, the dimension of the end of the groove far from the conveying channel in the axial direction is denoted as L1, where 0.5mm ≤ L1 ≤ 1.5mm. With such a design, the dimension L1 is controlled between 0.5mm and 1.5mm, which is convenient for reasonably controlling the liquid output of the corrosion liquid while achieving an effective corrosion effect.

[0012] In some embodiments, the dimension L1 further satisfies the condition that: 0.8mm ≤ L1 ≤ 1.2mm.

[0013] In some embodiments, the dimension of the end of the groove close to the conveying channel in the axial direction is denoted as L2, where 2mm ≤ L2 ≤ 5mm. With such a design, the dimension L2 is controlled between 2mm and 5mm, which can effectively balance the corrosion efficiency and structural strength of the corrosion roller.

[0014] In some embodiments, the dimension L2 further satisfies the condition that: 2.5mm ≤ L2 ≤ 4mm.

[0015] In some embodiments, the depth of the groove is denoted as h1, where 1mm ≤ h1 ≤ 5mm. With such a design, the dimension h1 is controlled between 1mm and 5mm, which can effectively balance the corrosion efficiency and structural strength of the corrosion roller.

[0016] In some embodiments, the dimension h1 further satisfies the condition that: 2mm ≤ h1 ≤ 4mm.

[0017] In some embodiments, the grooving includes a plurality of grooves, and at least part of the grooves extend and intersect on the roll surface to enclose and form a number of grids. With such a design, a number of grids are formed on the roll surface through the intersecting grooves, facilitating the formation of convex structures on the metal layer during the corrosion process and increasing the roughness of the metal layer.

[0018] In some embodiments, the area of the grid is denoted as S2, where 1 mm 2 ≤ S2 ≤ 50 mm 2 . With such a design, by controlling the area S2 of the grid between 1 mm 2 and 50 mm 2 , the size of the protrusions on the metal layer during corrosion is better, thereby making the roughness of the metal layer higher.

[0019] In some embodiments, the area S2 further satisfies the condition: 5 mm 2 ≤ S2 ≤ 30 mm 2 .

[0020] In some embodiments, the corrosion part includes a protrusion part, which is arranged on the roll surface, and one end of the discharge hole extends to the surface of the protrusion part. With such a design, the corrosion part is designed as a protrusion part, so that indentations are formed on the surface of the metal layer during the corrosion process, accelerating the corrosion of the metal layer and increasing the surface roughness.

[0021] In some embodiments, the height by which the protrusion part protrudes from the roll surface is denoted as h2, where 1 mm ≤ h2 ≤ 5 mm. With such a design, by controlling the height by which the protrusion part protrudes from the roll surface between 1 mm and 5 mm, the probability of corrosion liquid overflow can be effectively reduced; at the same time, the probability of the metal layer wrinkling during embossing is also effectively reduced, improving the corrosion effect.

[0022] In some embodiments, the size h2 further satisfies the condition: 2 mm ≤ h2 ≤ 4 mm.

[0023] In some embodiments, the corrosion part includes a recessed part, which is arranged on the roll surface and recesses toward the conveying channel side, and one end of the discharge hole extends into the recessed part. With such a design, the corrosion part is designed as a recessed part to corrode the surface of the metal layer in a surface corrosion manner to obtain a higher roughness.

[0024] In some embodiments, the depth of the recess of the recessed part is denoted as h3, where 1 mm ≤ h3 ≤ 5 mm. With such a design, by controlling the depth of the recess of the recessed part between 1 mm and 5 mm, the probability of corrosion liquid overflow can be effectively reduced; at the same time, the probability of the metal layer wrinkling during embossing is also effectively reduced, improving the corrosion effect.

[0025] In some embodiments, the size h3 further satisfies the condition: 2 mm ≤ h3 ≤ 4 mm.

[0026] In a second aspect, the present application provides an etching device, which includes: a back roller; an etching roller as described in any one of the above, and a metal layer is adapted to pass between the etching roller and the back roller. With such a design, by using the above etching roller, not only fixed-point etching is achieved, but also the liquid output can be accurately controlled, making the etching on the metal layer more uniform and reliable, improving the etching effect, being beneficial to enhancing the bonding force on the metal layer, and thus enhancing the reliability of the battery.

[0027] In some embodiments, the etching device further includes a heater, which is used to heat the back roller and / or the etching roller. With such a design, by introducing the heater, it can increase the etching uniformity and keep the etching solution warm, greatly enhancing the surface roughness of the metal layer.

[0028] In some embodiments, the etching device further includes a collection tank, which is used to recover the etching solution on the etching roller. With such a design, by setting the collection tank to collect the etching solution flowing out during the etching process, it is not only beneficial to the recycling of the etching solution, but also beneficial to improving the working environment.

[0029] In a third aspect, the present application provides a processing method for a metal layer. Using the etching device described in any one of the above, the processing method for the metal layer includes the following steps: introducing an etching solution into the conveying channel, and driving the etching roller to rotate around its own axis; cleaning and drying the metal layer passing through the etching roller. With such a design, by using the etching device to etch the metal layer, it is convenient to accurately control the liquid output, making the etching on the metal layer more uniform and reliable, improving the etching effect, being beneficial to enhancing the bonding force on the metal layer, and thus enhancing the reliability of the battery.

[0030] In some embodiments, the parameters of the etching solution include at least one of the following:

[0031] The temperature of the etching solution is 25°C to 80°C;

[0032] The concentration of the etching solution is 80 g / L to 120 g / L. With such a design, controlling the temperature of the etching solution between 25°C and 80°C; and / or controlling the concentration of the etching solution between 80 g / L and 120 g / L is convenient for accelerating the etching efficiency and improving the etching effect.

[0033] In some embodiments, the components of the etching solution include at least one of sodium hydroxide, potassium hydroxide, phosphoric acid, acetic acid, nitric acid, and sulfuric acid; or, the components of the etching solution include a ferric ion-containing compound. With such a design, the components of the etching solution are reasonably set to achieve an effective etching effect.

[0034] In some embodiments, the steps of cleaning and drying the metal layer passing through the etching roller include: washing and squeezing the metal layer; cleaning the squeezed metal layer with a brightening solution; and sequentially washing, squeezing and drying the cleaned metal layer. With such a design, through washing and cleaning with the brightening solution, not only the residual etching solution can be removed, but also the brightness of the metal layer can be improved, making the quality of the obtained metal layer higher.

[0035] In some embodiments, the composition of the brightening solution includes nitric acid, wherein the concentration of nitric acid is 300 mL / L to 500 mL / L. With such a design, controlling the concentration of nitric acid within 300 mL / L to 500 mL / L is beneficial to improving the brightening effect of the metal layer.

[0036] Fourthly, the present application proposes a metal layer, which is etched by any one of the above etching devices; or, the metal layer is processed by any one of the above processing methods of the metal layer, and the surface of the metal layer has etching recesses. With such a setting, etching recesses are formed on the metal layer, which can increase the roughness of the metal layer, thereby enhancing the adhesion on the metal layer.

[0037] In some embodiments, the thickness of the metal layer is denoted as h4, and the depth of the etching recess is denoted as h5, wherein 0.1 ≤ h5 / h4 ≤ 0.5. With such a design, controlling the ratio of the depth of the etching recess to the thickness of the metal layer between 0.1 and 0.5 can not only meet the etching effect of increasing roughness, but also prevent the increase of the sheet resistance of the metal layer and the reduction of the mechanical properties of the current collector due to excessive etching.

[0038] In some embodiments, the condition satisfied by the thickness h4 is: 0.7 μm ≤ h4 ≤ 2 μm. With such a design, controlling the thickness of the metal layer between 0.7 μm and 2 μm can not only meet the requirements of high energy density of the secondary battery, but also meet the roughening design of the metal layer surface.

[0039] In some embodiments, the condition further satisfied by the thickness h4 is: 1 μm ≤ h4 ≤ 1.5 μm.

[0040] In some embodiments, the area of the etching recess is denoted as S3, wherein 1 mm 2 ≤ S3 ≤ 50 mm 2 . With such a design, controlling the area of the etching recess between 1 mm 2 and 50 mm 2 enables the metal layer to have good electrical conductivity and structural mechanical properties while having a high roughness.

[0041] In some embodiments, the condition further satisfied by the area S3 is: 5 mm 2 ≤ S3 ≤ 30 mm 2 .

[0042] In some embodiments, the surface roughness of the metal layer having the corrosion recesses satisfies at least one of the following conditions:

[0043] 0.2 μm ≤ Ra ≤ 1 μm;

[0044] 1 μm ≤ Rz ≤ 3 μm, where Ra refers to the average surface roughness of the metal layer and Rz refers to the overall surface roughness of the metal layer. With such a design, the metal layer has a relatively high roughness, enhancing the bonding force on the metal layer, thereby facilitating the improvement of the reliability of the secondary battery.

[0045] In a fifth aspect, the present application provides a current collector, which includes the metal layer of any one of the above.

[0046] In some embodiments, the current collector further includes a substrate layer, the metal layer is disposed on at least one side surface of the substrate layer, and the corrosion recesses are disposed on the side of the metal layer facing away from the substrate layer. With such a design, by using the above metal layer, which has a higher surface roughness, it is beneficial to enhance the bonding force on the metal layer, thereby improving the reliability of the battery.

[0047] In a sixth aspect, the present application provides an electrode tab, which includes the current collector above.

[0048] In a seventh aspect, the present application provides an electrode assembly, which includes the electrode tab above.

[0049] In an eighth aspect, the present application provides a secondary battery, which includes the electrode assembly above.

[0050] In a ninth aspect, the present application provides an electrical device, which includes the secondary battery above. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0053] Figure 1 It is a schematic structural diagram of a vehicle provided for some embodiments of the present application.

[0054] Figure 2 It is a schematic exploded view of a secondary battery provided for some embodiments of the present application.

[0055] Figure 3 Schematic structural diagram of an etching roller with grooves provided for some embodiments of the present application.

[0056] Figure 4 For Figure 3 Shown is a cross-sectional structural view of the etching roller.

[0057] Figure 5 Schematic structural diagram of an etching roller with a convex portion or a concave portion provided for some embodiments of the present application.

[0058] Figure 6 Cross-sectional structural view of an etching roller with a convex portion provided for some embodiments of the present application.

[0059] Figure 7 Cross-sectional structural view of an etching roller with a concave portion provided for some embodiments of the present application.

[0060] Figure 8 Schematic structural diagram of an etching roller having both a convex portion or a concave portion and grooves provided for some embodiments of the present application.

[0061] Figure 9 Schematic structural diagram of an etching device provided for some embodiments of the present application.

[0062] Figure 10 Schematic flow chart of a processing method for a metal layer provided for some embodiments of the present application Figure 1 .

[0063] Figure 11 Schematic flow chart of a processing method for a metal layer provided for some embodiments of the present application Figure 2 .

[0064] Figure 12 Schematic diagram of the structure of the surface of a metal layer provided for some embodiments of the present application Figure 1 .

[0065] Figure 13 Schematic diagram of the structure of the surface of a metal layer provided for some embodiments of the present application Figure 2 .

[0066] Figure 14 Cross-sectional structural view of a metal layer provided for some embodiments of the present application.

[0067] Figure 15 Cross-sectional structural view of a composite current collector provided for some embodiments of the present application.

[0068] 100. Corrosion roller; 10. Roller body; 11. Conveyor channel; 12. Discharge hole; 13. Axis; 14. Roller surface; 20. Corrosion part; 21. Groove; 211. First groove wall; 212. Second groove wall; 22. Grid; 23. Protrusion; 24. Depression; 200. Backup roller; 300. Collection tank; 400. Electrical device; 40. Controller; 41. Secondary battery; 42. Motor; 411. End cap; 412. Electrode terminal; 413. Electrode assembly; 414. Housing; 415. Metal layer; 416. Corrosion recess; 500. Current collector; 510. Substrate layer. Detailed implementation manners

[0069] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe in detail the specific implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0070] At present, from the perspective of the development of the market situation, the application of power batteries is becoming more and more extensive. Power batteries are not only applied to energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely applied to electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application fields of power batteries, the market demand is also continuously increasing.

[0071] As a main component in a lithium-ion battery, a pole piece generally includes a current collector and an active layer, and the active layer is usually disposed on the metal layer of the current collector. In order to make the active layer and the metal layer combine, the surface of the metal layer is generally roughened. The roughening methods are usually physical methods and electrochemical methods. For example, when roughening, an indentation treatment roller is used to form indentations to increase the surface roughness of the metal layer; or, an electrochemical device is used to corrode the surface of the metal layer by means of corrosion.

[0072] However, the above roughening methods all have problems such as low roughness of the metal layer and uneven roughness, resulting in insufficient bonding force between the active layer and the metal layer, easy delamination under high pressure and tightness, or delamination during long-term cycling of the battery, leading to a drop in the battery core and affecting the reliability of the battery.

[0073] Based on this, in view of the problem of insufficient bonding force on the metal layer in the above-mentioned traditional roughening, the present application proposes a corrosion roller. A conveying channel is arranged inside the roller body and extends along the axial direction. The corrosive liquid in the conveying channel is conveyed to the corrosion part through the discharge holes, and then discharged from the corrosion part to the outside of the corrosion roller. In this way, when corroding the metal layer, the corrosion part can output the corrosive liquid to the metal layer when it contacts the metal layer, so as to effectively corrode the surface of the metal layer. Since the corrosive liquid is output from the inside to the outside of the corrosion roller and finally output on the corrosion part, not only fixed-point corrosion is achieved, but also the liquid output amount can be accurately controlled, making the corrosion on the metal layer more uniform and reliable, improving the corrosion effect, being beneficial to enhancing the bonding force on the metal layer, and thus enhancing the reliability of the battery.

[0074] In addition, when the corrosion work is not performed, cleaning liquid can be introduced into the conveying channel to clean the corrosion part, which can play a role in cleaning and preventing precipitation.

[0075] The corrosion roller proposed in the present application is not only applicable to the bonding process between the metal layer and the active layer, but also applicable to the bonding process between the metal layer and other substances. For example, in a composite current collector, the bonding between the metal layer and the substrate layer, etc.

[0076] The secondary battery disclosed in the embodiments of the present application can be but is not limited to being used in power-consuming devices such as vehicles, ships or aircraft. The power system of the power-consuming device can be composed of the battery monomers, batteries, etc. disclosed in the present application. In this way, it is beneficial to relieve and automatically adjust the deterioration of the expansion force of the battery core, supplement the consumption of the electrolyte, and improve the stability of the battery performance and the battery life.

[0077] The embodiments of the present application provide a power-consuming device using a secondary battery as a power source. The power-consuming device can be but is not limited to mobile phones, tablets, laptop computers, electric toys, electric tools, battery cars, electric vehicles, ships, spacecraft, etc. Among them, the electric toys can include fixed or mobile electric toys. For example, game consoles, electric vehicle toys, electric ship toys, electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles, spaceships, etc.

[0078] For the convenience of description, the following embodiments take a vehicle as an example of a power-consuming device according to an embodiment of the present application for illustration.

[0079] Please refer to Figure 1 , Figure 1Schematic structural diagram of a vehicle provided by some embodiments of the present application. The vehicle can be a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle, an extended-range vehicle, etc. A battery is disposed inside the vehicle, and the battery can be disposed at the bottom, the head, or the tail of the vehicle. The battery can be used for power supply of the vehicle. For example, the battery can be used as the operating power source of the vehicle. The vehicle may further include a controller 40 and a motor 42. The controller 40 is used to control the battery to supply power to the motor 42. For example, it is used for the working power requirements during starting, navigation, and driving of the vehicle.

[0080] In some embodiments of the present application, the secondary battery 41 can not only be used as the operating power source of the vehicle, but also as the driving power source of the vehicle, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle.

[0081] In the battery system, there can be multiple secondary batteries 41. The multiple secondary batteries 41 can be connected in series, in parallel, or in a series-parallel combination. A series-parallel combination means that there are both series and parallel connections among the multiple secondary batteries 41. The multiple secondary batteries 41 can be directly connected in series, in parallel, or in a series-parallel combination, and then the whole formed by the multiple secondary batteries 41 is accommodated in a box body. Of course, the battery can also be in the form that multiple secondary batteries 41 are first connected in series, in parallel, or in a series-parallel combination to form battery modules, and then the multiple battery modules are connected in series, in parallel, or in a series-parallel combination to form a whole and are accommodated in a box body. The battery may further include other structures. For example, the battery may further include a busbar component for realizing electrical connection among the multiple secondary batteries 41. Among them, the secondary battery 41 can be in a cylindrical shape, a flat shape, a cuboid shape, or other shapes, etc.

[0082] Please refer to Figure 2 , Figure 2 Schematic exploded view of the secondary battery 41 provided by some embodiments of the present application. The secondary battery 41 refers to the smallest unit that makes up the battery. As Figure 2 , the secondary battery 41 includes an end cap 411, a housing 414, an electrode assembly 413, and other functional components.

[0083] The end cap 411 refers to a component that covers the opening of the housing 414 to isolate the internal environment of the secondary battery 41 from the external environment. Without limitation, the shape of the end cap 411 can be adapted to the shape of the housing 414 to fit the housing 414. Optionally, the end cap 411 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 411 is not easily deformed when subjected to extrusion and collision, enabling the secondary battery 41 to have higher structural strength and improved safety performance. Functional components such as electrode terminals 412 can be provided on the end cap 411. The electrode terminals 412 can be used to electrically connect to the electrode assembly 413 for outputting or inputting the electrical energy of the secondary battery 41. In some embodiments, a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the secondary battery 41 reaches a threshold can also be provided on the end cap 411. The material of the end cap 411 can also be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations on this. In some embodiments, an insulating member can also be provided on the inner side of the end cap 411, and the insulating member can be used to isolate the electrical connection components in the housing 414 from the end cap 411 to reduce the risk of short circuit. Exemplarily, the insulating member can be plastic, rubber, etc.

[0084] The housing 414 is a component used to cooperate with the end cap 411 to form the internal environment of the secondary battery 41, wherein the formed internal environment can be used to accommodate the electrode assembly 413, the electrolyte, and other components. The housing 414 and the end cap 411 can be independent components. An opening can be provided on the housing 414, and the end cap 411 is covered on the opening to form the internal environment of the secondary battery 41. Without limitation, the end cap 411 and the housing 414 can also be integrated. Specifically, the end cap 411 and the housing 414 can first form a common connection surface before other components are put into the housing. When it is necessary to encapsulate the inside of the housing 414, the end cap 411 is then covered on the housing 414. The housing 414 can be of various shapes and sizes, such as rectangular parallelepiped shape, cylindrical shape, hexagonal prism shape, etc. Specifically, the shape of the housing 414 can be determined according to the specific shape and size of the electrode assembly 413. The material of the housing 414 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not make special limitations on this.

[0085] The electrode assembly 413 is a component in the secondary battery 41 where an electrochemical reaction occurs. One or more electrode assemblies 413 can be contained within the housing 414. The electrode assembly 413 is mainly formed by winding or laminating a positive electrode sheet and a negative electrode sheet, and generally, a separator is provided between the positive electrode sheet and the negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly 413, and the portions of the positive electrode sheet and the negative electrode sheet without active materials respectively constitute the electrode tabs. The positive electrode tab and the negative electrode tab can be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the electrode tabs are connected to the electrode terminals 412 to form a current loop.

[0086] According to some embodiments of the present application, please refer to Figure 3 With Figure 4 , the present application provides a corrosion roller 100, which includes: a roller body 10 and a corrosion part 20. The roller body 10 is provided with a conveying channel 11 extending along the direction of its own axis 13, and the corrosion part 20 is provided on the roller body 10. A discharge hole 12 is provided on the inner wall of the conveying channel 11, and the discharge hole 12 extends to the corrosion part 20 and is used to communicate with the outside of the corrosion roller 100 on the corrosion part 20.

[0087] The roller body 10 refers to a structure that presents or approximately presents a cylindrical shape. When corroding the surface of the metal layer 415, the roller body 10 can roll-press the surface of the metal layer 415 around its own axis 13. Among them, the metal layer 415 refers to a component on the current collector 500 that can carry active materials and output the current generated by the active materials to the outside. In the positive electrode plate, the metal layer 415 can be, but is not limited to, aluminum, nickel, etc. In the negative electrode plate, the metal layer 415 can be, but is not limited to, copper, etc.

[0088] The conveying channel 11 refers to a flow channel structure inside the roller body 10, and a corrosion medium, such as a corrosion liquid, can be introduced into the conveying channel 11. At the same time, the discharge hole 12 is provided on the inner wall of the conveying channel 11 and is connected to the conveying channel 11, so that the corrosion liquid in the conveying channel 11 can enter the discharge hole 12.

[0089] Since the discharge hole 12 extends to the corrosion part 20 and the part on the corrosion part 20 communicates with the outside, therefore, the corrosion liquid in the discharge hole 12 will flow into the corrosion part 20 and be output to the outside of the corrosion roller 100 through the corrosion part 20.

[0090] Optionally, the shape of the discharge hole 12 can have various designs, as long as it can discharge the corrosion liquid in the conveying channel 11. For example: the shape of the discharge hole 12 can be, but is not limited to, square, circular, oval, pentagonal, etc.

[0091] The corrosion part 20 refers to the part on the roller body 10 that can corrode the metal layer 415. The corrosion part 20 can have various designs. For example, the corrosion part 20 can be designed into a convex structure, or it can be designed into a concave or groove structure. When the corrosion part 20 is designed into a convex structure, in order to enable the discharge hole 12 to communicate with the outside on the corrosion part 20, one end of the discharge hole 12 can be extended to the outside of the corrosion part 20, so that one end of the discharge hole 12 is connected to the outside. When the corrosion part 20 is designed into a concave or groove structure, when one end of the discharge hole 12 extends to the corrosion part 20, it can be connected to the outside through the corrosion part 20.

[0092] The number of the corrosion part 20 and the discharge hole 12 can both be set to multiple. At the same time, the quantity correspondence relationship between the corrosion part 20 and the discharge hole 12 can be set one-to-one; it can also be set one-to-many, that is, one end of multiple discharge holes 12 all extends to the corrosion part 20.

[0093] With such a design, not only fixed-point corrosion is achieved, but also the liquid discharge amount can be accurately controlled, making the corrosion on the metal layer 415 more uniform and reliable, improving the corrosion effect, being beneficial to enhancing the bonding force on the metal layer 415, and thus enhancing the reliability of the battery.

[0094] According to some embodiments of the present application, optionally, please refer to Figure 4 , the hole area of the discharge hole 12 is denoted as S1, where 1mm 2 ≤S1≤10mm 2 .

[0095] The area of the discharge hole 12 can affect the amount of the corrosion liquid output by the corrosion part 20. If the hole area is too small, it will not only affect the liquid discharge amount of the corrosion liquid, but also be prone to blockage; if the hole area is too large, it will not only affect the structural strength of the corrosion roller 100, but also result in excessive liquid discharge, increasing the corrosion cost.

[0096] Therefore, the hole area S1 is controlled between 1mm 2 ~10mm 2 . For example: the hole area S1 can be, but is not limited to, 1mm 2 , 2mm 2 , 3mm 2 , 4mm 2 , 5mm 2 , 6mm 2 , 7mm 2 , 8mm 2 , 9mm 2 , 10mm 2 etc.

[0097] Of course, in some other embodiments, the condition that the hole area S1 also satisfies is: 3mm 2 ≤S1≤7mm 2. For example, the hole area S1 can be but is not limited to 3 mm 2 , 3.5 mm 2 , 4 mm 2 , 4.5 mm 2 , 5 mm 2 , 5.5 mm 2 , 6 mm 2 , 6.5 mm 2 , 7 mm 2 etc.

[0098] With such a design, the hole area S1 is controlled between 1 mm 2 ~10 mm 2 . On the premise of achieving effective roughness, the smoothness of liquid discharge and corrosion cost can be effectively balanced.

[0099] According to some embodiments of the present application, optionally, the roller body 10 has a roller surface 14 circumferentially arranged around its own axis 13, and at least part of the corrosion part 20 is arranged on the roller surface 14; and / or, at least part of the corrosion part 20 is arranged inside the roller body 10, and the end far from the conveying channel 11 is not lower than the roller surface 14.

[0100] The corrosion part 20 can be arranged on the roller surface 14, or can be arranged inside the roller body 10 and extend out of the roller surface 14 or be flush with the roller surface 14. Of course, in some embodiments, a part of the corrosion part 20 is arranged on the roller surface 14, and the other part is arranged inside the roller body 10 and extends to be flush with the roller surface 14 or beyond the roller surface 14.

[0101] With such a design, the corrosion part 20 is reasonably arranged on the roller body 10, which is convenient for the corrosion part 20 to effectively corrode on the metal layer 415, increase the roughness of the metal layer 415, and improve the bonding force on the metal layer 415.

[0102] According to some embodiments of the present application, optionally, please refer to Figure 4 , the corrosion part 20 includes a groove 21. The groove 21 is arranged inside the roller body 10, and the end far from the conveying channel 11 is not lower than the roller surface 14. The discharge hole 12 communicates with the outside of the corrosion roller 100 through the groove 21.

[0103] The groove 21 refers to a structure with a certain space. When the corrosion liquid flows into the groove 21 from the discharge hole 12, the corrosion liquid can be discharged from the end of the groove 21 far from the conveying channel 11 to the outside of the corrosion roller 100. Among them, one or more notches can be arranged at the end of the groove 21 far from the conveying channel 11 so that the corrosion liquid can be discharged to the surface of the metal layer 415.

[0104] One end of the groove 21 can be flush with the roller surface 14 or can extend beyond the roller surface 14. When one end of the groove 21 extends beyond the roller surface 14, the groove wall enclosing the groove 21 can protrude beyond the roller surface 14. At this time, when the metal layer 415 is corroded, the groove 21 can form an indentation on the surface of the metal layer 415, facilitating the acceleration of corrosion.

[0105] Optionally, the shape of the groove 21 in its own depth direction can be various, for example: the shape of the groove 21 in its own depth direction can be trapezoidal, square, oval, etc.

[0106] With such a design, the corrosive liquid is designed into the structure of the groove 21, which facilitates the effective corrosion of the surface of the metal layer 415 and improves the roughness of the metal layer 415.

[0107] According to some embodiments of the present application, optionally, please refer to Figure 4 , the dimension of the end of the groove 21 far from the conveying channel 11 in the direction of the axis 13 is smaller than the dimension of the end of the groove 21 close to the conveying channel 11 in the direction of the axis 13.

[0108] Among the two ends of the groove 21, the dimension of the end close to the conveying channel 11 is larger than the dimension of the end far from the conveying channel 11, which indicates that the space for the output of the corrosive liquid can be smaller than the space for the input of the corrosive liquid, facilitating the concentrated outward output of the corrosive liquid and achieving better fixed-point corrosion.

[0109] Specifically in some embodiments, please refer to Figure 4 , the groove wall of the groove 21 includes a first groove wall 211 and a second groove wall 212 that are spaced apart along the direction of the axis 13, and the distance between the first groove wall 211 and the second groove wall 212 gradually decreases from the end of the groove 21 close to the conveying channel 11 to the end of the groove 21 far from the conveying channel 11.

[0110] With such a design, it is convenient to concentrate the outward output of the corrosive liquid, achieve better fixed-point corrosion, and improve the corrosion effect.

[0111] According to some embodiments of the present application, optionally, please refer to Figure 4 , the dimension of the end of the groove 21 far from the conveying channel 11 in the direction of the axis 13 is denoted as L1, where 0.5 mm ≤ L1 ≤ 1.5 mm.

[0112] The selection of the dimension L1 can affect the liquid output amount of the groove 21 outward. For example: if the dimension L1 is too small, the liquid output amount of the corrosive liquid is reduced, affecting the corrosion effect; if the dimension L1 is too large, the liquid output amount is too large, resulting in excessive corrosion on the metal layer 415, not only reducing the structural strength of the metal layer 415, but also increasing the sheet resistance of the metal layer 415.

[0113] For this reason, the dimension L1 can take values between 0.5 mm and 1.5 mm, for example: it can be but not limited to 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc. In some other embodiments, the condition that the dimension L1 also satisfies is: 0.8 mm ≤ L1 ≤ 1.2 mm, for example: it can be but not limited to 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, etc.

[0114] With such a design, by controlling the dimension L1 between 0.5 mm and 1.5 mm, while achieving an effective corrosion effect, it is convenient to reasonably control the liquid output volume of the corrosion liquid.

[0115] According to some embodiments of the present application, optionally, please refer to Figure 4 , the dimension of the end of the groove 21 close to the conveying channel 11 in the direction of the axis 13 is denoted as L2, where 2 mm ≤ L2 ≤ 5 mm.

[0116] The selection of the dimension L2 can affect the amount of corrosion liquid entering the groove 21; at the same time, it also affects the strength of the structure of the roller body 10 itself. For example: if the dimension L2 is too small, the amount of corrosion liquid entering will decrease, reducing the corrosion efficiency; if the dimension L2 is too large, it will cause the structural strength of the roller body 10 to decrease.

[0117] For this reason, the dimension L2 can take values between 2 mm and 5 mm, for example: it can be but not limited to 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. In some other embodiments, the condition that the dimension L2 also satisfies is: 2.5 mm ≤ L2 ≤ 4 mm. For example: it can be but not limited to 2.5 mm, 2.7 mm, 2.9 mm, 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, etc.

[0118] With such a design, by controlling the dimension L2 between 2 mm and 5 mm, the corrosion efficiency and structural strength of the corrosion roller 100 can be effectively balanced.

[0119] According to some embodiments of the present application, please refer to Figure 4 , optionally, the depth of the groove 21 is denoted as h1, where 1 mm ≤ h1 ≤ 5 mm.

[0120] Similarly, the depth of the groove 21 can also affect the liquid output volume of the corrosion liquid output from the groove 21 and affect the corrosion efficiency. At the same time, if the depth of the groove 21 is too large, it will also weaken the structural strength of the roller body 10.

[0121] For this purpose, the depth h1 of the groove 21 is controlled to take values between 1 mm and 5 mm. For example, it can be, but is not limited to, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. In some other embodiments, the condition that the dimension h1 also satisfies is: 2 mm ≤ h1 ≤ 4 mm. For example, it can be, but is not limited to, 2 mm, 2.2 mm, 2.6 mm, 2.8 mm, 3 mm, 3.2 mm, 3.6 mm, 3.8 mm, 4 mm, etc.

[0122] With such a design, the dimension h1 is controlled between 1 mm and 5 mm, which can effectively balance the corrosion efficiency and structural strength of the corrosion roller 100.

[0123] According to some embodiments of the present application, optionally, please refer to Figure 3 , the groove 21 includes a plurality of grooves, and at least part of the grooves 21 extend and intersect on the roller surface 14 to enclose a number of meshes 22.

[0124] The extending direction of the groove 21 on the roller surface 14 may not be limited, as long as at least part of the grooves 21 can intersect with each other to enclose the mesh 22. Among them, the shape of the mesh 22 can have various designs. For example, it can be, but is not limited to, triangular, square, pentagonal, hexagonal, etc. Of course, it can also be irregular.

[0125] When corroding the metal layer 415, the groove 21 forms a concave corrosion structure on the surface of the metal layer 415. At this time, a convex corrosion structure is formed on the surface of the metal layer 415 corresponding to the mesh 22. This makes the metal layer 415 have a concave-convex structure, thereby making it have a higher roughness.

[0126] In addition, when one end of the groove 21 protrudes outside the roller surface 14, the formed mesh 22 presents a concave or grooved structure, so that during the corrosion process, the part on the metal layer 415 is more likely to bulge at the mesh 22, increasing the concave-convex roughness on the metal layer 415.

[0127] With such a design, through the intersecting grooves 21, a number of meshes 22 are formed on the roller surface 14, which is convenient for the metal layer 415 to form a convex structure during the corrosion process and improves the roughness of the metal layer 415.

[0128] According to some embodiments of the present application, optionally, the area of the mesh 22 is denoted as S2, where 1 mm 2 ≤ S2 ≤ 50 mm 2 .

[0129] The area S2 of the mesh 22 can take values between 1 mm 2 ~50 mm 2 For example, the area S2 can be, but is not limited to, 1 mm 2, 5 mm 2 , 10 mm 2 , 20 mm 2 , 30 mm 2 , 40 mm 2 , 50 mm 2 etc.

[0130] In some other embodiments, the condition that the area S2 also satisfies is: 5 mm 2 ≤ S2 ≤ 30 mm 2 , for example: the area S2 can be but is not limited to 5 mm 2 , 10 mm 2 , 15 mm 2 , 20 mm 2 , 25 mm 2 , 30 mm 2 etc.

[0131] With such a design, the area S2 of the grid 22 is controlled between 1 mm 2 ~50 mm 2 , so that the size of the protrusions on the metal layer 415 during corrosion is better, and thus the roughness on the metal layer 415 is higher.

[0132] According to some embodiments of the present application, optionally, please refer to Figure 5 and Figure 6 , the corrosion part 20 includes a protrusion part 23, the protrusion part 23 is arranged on the roller surface 14, and one end of the discharge hole 12 extends to the surface of the protrusion part 23.

[0133] The protrusion part 23 refers to the structure protruding from the roller surface 14. During the corrosion process, the protrusion part 23 can form indentations on the metal layer 415; at the same time, the corrosion liquid is output from the surface of the protrusion part 23 to the indentations, making the concave structure more prominent.

[0134] The protrusion part 23 can be installed on the roller surface 14 in a combined manner, such as: bonding, welding, threaded connection, etc. It can also be connected in an integrally formed manner, such as: injection molding, extrusion, 3D printing, etc. At the same time, the number of the protrusion parts 23 can be designed as multiple, and all the protrusion parts 23 can be regularly arranged on the roller surface 14, such as: matrix distribution, circular ring interval distribution, etc.; it can also be irregularly arranged, etc.

[0135] In addition, the convex portion 23 and the groove 21 can be provided on the etching roller 100 simultaneously. In this way, the metal layer 415 can form both the etching marks formed by the convex portion 23 and the etching marks formed by the groove 21, further increasing the roughness of the metal layer 415. At the same time, there are various distributions of the convex portion 23 and the groove 21 on the etching roller 100. For example, the convex portion 23 is provided in a part of the area, and the groove 21 is provided in another part of the area; or, the convex portion 23 and the groove 21 can be distributed in an interlaced manner. For example, please refer to Figure 8 and the convex portion 23 is provided in the grid 22 formed between the grooves 21. When the convex portion 23 and the groove 21 are provided on the etching roller 100 simultaneously, the height of the convex portion 23 protruding from the roller surface 14 can be set to be the same as or approximately the same as the height of the groove 21 protruding from the roller surface 14.

[0136] With such a design, the etching portion 20 is designed as the convex portion 23, so that indentations are formed on the surface of the metal layer 415 during the etching process, accelerating the etching of the metal layer 415 and increasing the surface roughness.

[0137] According to some embodiments of the present application, optionally, please refer to Figure 6 and the height of the convex portion 23 protruding from the roller surface 14 is denoted as h2, where 1 mm ≤ h2 ≤ 5 mm.

[0138] The height of the convex portion 23 protruding from the roller surface 14 can affect the etching effect on the metal layer 415. If the height is too low, the etching solution is likely to overflow onto the roller surface 14, resulting in trailing during etching and etching the non-etched metal surface together; if the height is too high, during embossing, the excessive height is likely to cause the metal layer 415 to wrinkle.

[0139] Therefore, the height of the convex portion 23 protruding from the roller surface 14 is controlled between 1 mm and 5 mm. For example, the height h2 can be but is not limited to 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. In some other embodiments, the condition that the dimension h2 also satisfies is: 2 mm ≤ h2 ≤ 4 mm. For example, the height h2 can be but is not limited to 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.4 mm, 3.8 mm, 4 mm, etc.

[0140] With such a design, controlling the height of the convex portion 23 protruding from the roller surface 14 between 1 mm and 5 mm can effectively reduce the occurrence probability of the etching solution overflowing; at the same time, it also effectively reduces the probability of the metal layer 415 wrinkling during embossing, improving the etching effect.

[0141] According to some embodiments of the present application, optionally, please refer to Figure 7, the etching part 20 includes a recessed part 24 which is arranged on the roller surface 14 and recesses towards the conveying channel 11, and one end of the discharge hole 12 extends into the recessed part 24.

[0142] The recessed part 24 refers to a structure formed by the inner concave of the roller surface 14 towards the conveying channel 11. The recessed part 24 is lower than the roller surface 14. At this time, the etching liquid in the discharge hole 12 will flow into the recessed part 24. When the metal layer 415 is etched, the recessed part 24 contacts the surface of the metal layer 415, and the etching liquid in the recessed part 24 adheres to the surface of the metal layer 415 for etching to form an etched concave structure. That is, the etching of the metal layer 415 by the recessed part 24 is surface etching. Of course, the etching of the metal layer 415 by the protruding part 23 is also surface etching.

[0143] To make the metal layer 415 etch uniformly, the number of the recessed parts 24 can be set to be multiple, and all the recessed parts 24 are distributed at intervals on the roller surface 14. Among them, there can be various designs for the specific distribution mode of the recessed parts 24, such as: being distributed in a matrix; being distributed at intervals in a ring, etc. At the same time, the shape and size of the recessed part 24 can be determined according to actual needs.

[0144] In addition, the recessed part 24 and the grooving 21 can be arranged on the etching roller 100 at the same time, so that the metal layer 415 can form both the etching marks formed by the recessed part 24 and the etching marks formed by the grooving 21, further improving the roughness on the metal layer 415. At the same time, there can be various distributions of the recessed part 24 and the grooving 21 on the etching roller 100, such as: arranging the recessed part 24 in one part of the area and arranging the grooving 21 in the other part of the area; or, the recessed part 24 and the grooving 21 can be distributed in an interlaced manner, such as: please refer to Figure 8 , the recessed part 24 is arranged in the grid 22 formed between the groovings 21, etc. In addition, since the recessed part 24 is arranged lower than the roller surface 14, therefore, to make the etching depth on the metal layer 415 relatively consistent, the end of the grooving 21 far from the conveying channel 11 can be kept flush or approximately flush with the roller surface 14.

[0145] With such a design, the etching part 20 is designed as the recessed part 24 to etch the surface of the metal layer 415 in a surface etching manner to obtain a higher roughness.

[0146] According to some embodiments of the present application, optionally, please refer to Figure 7 , the depth of the recess of the recessed part 24 is denoted as h3, where 1 mm ≤ h3 ≤ 5 mm.

[0147] The depth of the recess 24 can affect the corrosion effect on the metal layer 415. If the depth is too shallow, the etching solution is likely to overflow onto the roller surface 14, resulting in trailing during corrosion and etching the non-corroded metal surface as well. If the depth is too deep, it means that the surrounding protrusions of the recess 24 are relatively high, and in this case, wrinkles are likely to occur on the metal layer 415 during embossing.

[0148] The depth of the recess 24 of the recess portion 24 can be controlled between 1 mm and 5 mm. For example, the depth h3 can be, but is not limited to, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc. In some other embodiments, the condition that the dimension h3 also satisfies is: 2 mm ≤ h3 ≤ 4 mm. For example, the depth h3 can be, but is not limited to, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, 3.4 mm, 3.8 mm, 4 mm, etc.

[0149] With such a design, controlling the depth of the recess 24 of the recess portion 24 between 1 mm and 5 mm can effectively reduce the occurrence probability of the etching solution overflowing; at the same time, it also effectively reduces the probability of wrinkles occurring on the metal layer 415 during embossing, improving the corrosion effect.

[0150] According to some embodiments of the present application, please refer to Figure 9 , the present application provides an etching device, which includes: a back roller 200 and an etching roller 100 as described in any one of the above. A metal layer 415 is adapted to pass between the etching roller 100 and the back roller 200.

[0151] The back roller 200 refers to a structure that is opposite to the etching roller 100 and forms a gap for the metal layer 415 to pass through. When the metal layer 415 passes between the back roller 200 and the etching roller 100, there will be a certain extrusion force on the metal layer 415 between the etching roller 100 and the back roller 200, enabling the etching roller 100 to better etch the surface of the metal layer 415.

[0152] When both surfaces of the metal layer 415 need to be etched, the back roller 200 can also be designed with the structure of the etching roller 100, that is, the back roller 200 can also be provided with an etching portion 20, so that both surfaces of the metal layer 415 can be etched synchronously.

[0153] With such a design, by using the above-mentioned etching roller 100, not only fixed-point etching is achieved, but also the liquid output can be accurately controlled, making the etching on the metal layer 415 more uniform and reliable, improving the corrosion effect, being beneficial to enhancing the bonding force on the metal layer 415, and thus enhancing the reliability of the battery.

[0154] According to some embodiments of the present application, optionally, the etching device further includes a heater. The heater is used to heat the back roller 200 and / or the etching roller 100.

[0155] A heater refers to a device that can heat the back roller 200 and / or the etching roller 100. For example, it can be, but is not limited to, an electric heating device, a device providing a heat transfer medium, etc. Among them, the device providing a heat transfer medium can supply a high-temperature heat transfer medium, such as heat-conducting oil or hot water, etc., into the back roller 200 and / or the etching roller 100. At this time, the back roller 200 can be designed as a hollow roller.

[0156] When the heater can introduce a heat transfer medium into the back roller 200 or the etching roller 100, the heat transfer medium has a certain pressure inside the back roller 200 or the etching roller 100, and its pressure value can be determined according to the actual product. For example, the pressure can be greater than or equal to 10 N and less than or equal to 20 N, etc.

[0157] With such a design, introducing the heater can increase the corrosion uniformity and keep the etching solution warm, greatly improving the surface roughness of the metal layer 415.

[0158] According to some embodiments of the present application, optionally, please refer to Figure 9 , the etching device further includes a collection tank 300, and the collection tank 300 is used to recover the etching solution on the etching roller 100.

[0159] The collection tank 300 refers to a device that can collect the etching solution flowing out of the etching roller 100, and it can be arranged directly below the etching roller 100.

[0160] With such a design, setting the collection tank 300 to collect the etching solution flowing out during the etching process is not only beneficial to the recycling of the etching solution, but also beneficial to improving the working environment.

[0161] According to some embodiments of the present application, please refer to Figure 10 , the present application proposes a processing method for a metal layer. Using the etching device of any one of the above, the processing method for the metal layer includes the following steps:

[0162] S100. Introduce an etching solution into the conveying channel 11 and drive the etching roller 100 to rotate around its own axis 13;

[0163] S200. Clean and dry the metal layer 415 passing through the etching roller 100.

[0164] In step S100, after the etching solution is input into the conveying channel 11, the etching solution can flow into the etching part 20 through the discharge holes 12 and flow from the etching part 20 to the metal surface to achieve surface etching. Among them, when the etching part 20 is the groove 21, the groove 21 can not only form indentations on the surface of the metal layer 415, but also output the etching solution to the surface of the metal layer 415 through one end of the groove 21; when the etching part 20 is the protrusion 23, the protrusion 23 presses on the surface of the metal layer 415 and outputs the etching solution to the metal layer 415 through the surface of the protrusion 23; when the etching part 20 is the recess 24, the recess 24 abuts against the surface of the metal layer 415, and the etching solution in the recess 24 adheres to the metal layer 415.

[0165] In step S200, the metal layer 415 is cleaned, and the purpose is to remove the residual etching solution on the metal layer 415. And the metal layer 415 is dried, and the purpose is to keep the surface of the metal layer 415 dry and facilitate participation in subsequent operations.

[0166] Designed in this way, using the etching equipment to etch the metal layer 415 is convenient for accurately controlling the liquid output volume, making the etching on the metal layer 415 more uniform and reliable, improving the etching effect, being beneficial to enhancing the bonding force on the metal layer 415, and thus enhancing the reliability of the battery.

[0167] According to some embodiments of the present application, optionally, the parameters of the etching solution include at least one of the following:

[0168] The temperature of the etching solution is 25°C to 80°C;

[0169] The concentration of the etching solution is 80 g / L to 120 g / L.

[0170] The temperature of the etching solution can be within the range of 25°C to 80°C. For example: the temperature of the etching solution can be, but is not limited to, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 70°C, 80°C, etc.

[0171] The concentration of the etching solution can be within the range of 80 g / L to 120 g / L. For example: the concentration of the etching solution can be, but is not limited to, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, etc.

[0172] In addition, after the metal layer 415 passes through the etching roller 100, its etching time can be adjusted according to actual needs. For example: the etching time can be, but is not limited to, 1 s to 30 s.

[0173] Designed in this way, the temperature of the etching solution is controlled between 25°C and 80°C; and / or, the concentration of the etching solution is controlled between 80 g / L and 120 g / L, which is convenient for accelerating the etching efficiency and improving the etching effect.

[0174] According to some embodiments of the present application, optionally, the components of the etching solution include at least one of sodium hydroxide, potassium hydroxide, phosphoric acid, acetic acid, nitric acid, and sulfuric acid; or, the components of the etching solution include a ferric ion compound.

[0175] When the metal layer 415 is a structure in the positive electrode tab, the components of the etching solution may include one or more of sodium hydroxide, potassium hydroxide, phosphoric acid, acetic acid, nitric acid, sulfuric acid, etc. When the metal layer 415 is a structure in the negative electrode tab, the components of the etching solution may include a ferric ion compound, such as: FeCl3, FeNO3, etc.

[0176] Designed in this way, the components of the etching solution are reasonably set to achieve an effective etching effect.

[0177] According to some embodiments of the present application, optionally, please refer to Figure 11 , S200, the step of cleaning and drying the metal layer 415 passing through the etching roller 100, includes:

[0178] S210, washing and squeezing the metal layer 415;

[0179] S220, cleaning the squeezed metal layer 415 with a brightening solution;

[0180] S230, sequentially washing, squeezing and drying the cleaned metal layer 415.

[0181] In step S210, there are various ways to wash the metal layer 415, such as: soaking, spraying, flushing, etc. Among them, washing can remove the residual etching solution on the metal layer 415. At the same time, there are also various ways to squeeze the metal layer 415, such as: squeezing through a squeezing roller, etc.

[0182] In step S220, the brightening solution refers to a solvent that can brighten the metal layer 415.

[0183] Designed in this way, through washing and cleaning with the brightening solution, not only the residual etching solution is removed; but also the brightness of the metal layer 415 can be improved, making the quality of the obtained metal layer 415 higher.

[0184] According to some embodiments of the present application, optionally, the components of the brightening solution include nitric acid, wherein the concentration of nitric acid is 300 mL / L to 500 mL / L.

[0185] The concentration of nitric acid can be in the range of 300 mL / L to 500 mL / L. For example, the concentration of nitric acid can be, but is not limited to, 300 mL / L, 350 mL / L, 400 mL / L, 450 mL / L, 500 mL / L, etc. Among them, the nitric acid can be, but is not limited to, 68% nitric acid.

[0186] With such a design, controlling the concentration of nitric acid within 300 mL / L to 500 mL / L is beneficial to improving the light extraction effect of the metal layer 415.

[0187] According to some embodiments of the present application, please refer to Figure 12 and Figure 13 , the present application provides a metal layer 415, and the metal layer 415 is etched using any one of the above etching devices; alternatively, the metal layer 415 is processed using any one of the above processing methods for the metal layer. The surface of the metal layer 415 has etching recesses 416.

[0188] The etching recess 416 refers to a structure formed after the etching part 20 outputs the etching solution to the surface of the metal layer 415 during the etching process. Its shape can be various, for example: it can be, but is not limited to, a mesh shape, a rhombus shape, a circular shape, etc. Of course, the shape of the etching recess 416 can be a single pattern or a combination of multiple patterns.

[0189] The area of the etching recess 416 can be determined according to actual needs. For example, the area of the etching recess 416 can be 1 mm 2 to 50 mm 2 .

[0190] With such a setting, forming the etching recess 416 on the metal layer 415 can increase the roughness of the metal layer 415, thereby improving the adhesion on the metal layer 415.

[0191] According to some embodiments of the present application, optionally, please refer to Figure 14 , the thickness of the metal layer 415 is denoted as h4, and the depth of the etching recess 416 is denoted as h5. Among them, 0.1 ≤ h5 / h4 ≤ 0.5.

[0192] The depth of the etching recess 416 can affect the roughness of the metal layer 415, but its depth should not be too deep. If it is too deep, the sheet resistance at local positions on the metal layer 415 will be too large, thereby affecting the conductivity of the current collector 500. For example: the etching recess 416 is not provided to penetrate the metal layer 415.

[0193] Therefore, the ratio of the depth of the etching recess 416 to the thickness of the metal layer 415 is controlled between 0.1 and 0.5. For example: it can be, but is not limited to, 0.1, 0.2, 0.3, 0.4, 0.5, etc.

[0194] With such a design, the ratio of the depth of the corrosion recess 416 to the thickness of the metal layer 415 is controlled between 0.1 and 0.5, which can not only meet the corrosion effect of improving the roughness, but also prevent the increase of the sheet resistance of the metal layer 415 and the reduction of the mechanical properties of the current collector 500 due to excessive corrosion.

[0195] According to some embodiments of the present application, optionally, the condition satisfied by the thickness h4 is: 0.7 μm ≤ h4 ≤ 2 μm.

[0196] When designing the thickness of the metal layer 415, if it is too large, it will affect the energy density of the secondary battery 41; if it is too small, it will not only affect the overall structural strength of the current collector 500, but also increase the difficulty of roughening the surface of the metal layer 415.

[0197] Therefore, the thickness of the metal layer 415 is controlled between 0.7 μm and 2 μm. For example, the thickness of the metal layer 415 can be, but is not limited to, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, etc. Of course, in some other embodiments, the condition satisfied by the thickness h4 is also: 1 μm ≤ h4 ≤ 1.5 μm. For example: 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, etc.

[0198] With such a design, the thickness of the metal layer 415 is controlled between 0.7 μm and 2 μm, which can not only meet the requirements of high energy density of the secondary battery 41, but also meet the roughening design of the surface of the metal layer 415.

[0199] According to some embodiments of the present application, optionally, the area of the corrosion recess 416 is denoted as S3, where 1 mm 2 ≤ S3 ≤ 50 mm 2 .

[0200] If the area of the corrosion recess 416 is too small, the corrosion effect is not obvious and the roughness is low; if it is too large, it will lead to excessive corrosion of the metal layer 415, resulting in an increase in sheet resistance and a reduction in electrical conductivity; at the same time, it will also weaken the structural mechanical properties of the metal layer 415.

[0201] Therefore, the area of the corrosion recess 416 can be between 1 mm 2 and 50 mm 2 . For example, the area S3 can be, but is not limited to, 1 mm 2 , 5 mm 2 , 10 mm 2 , 20 mm 2 , 30 mm 2 , 40 mm 2 , 50 mm 2 etc. In some other embodiments, the area S3 also satisfies the condition: 5 mm2 ≤S3≤30 mm 2 , for example: the area S3 can be but is not limited to 5 mm 2 , 10 mm 2 , 15 mm 2 , 20 mm 2 , 25 mm 2 , 30 mm 2 and so on.

[0202] It should also be noted that, in order to control the area of the corrosion recess 416 within 1 mm 2 ~50 mm 2 , the corrosion part 20 on the corrosion roller 100 can be designed as a convex part 23 or a concave part 24.

[0203] With such a design, the area of the corrosion recess 416 is controlled within 1 mm 2 ~50 mm 2 , so that while the metal layer 415 has a relatively high roughness, it can also have good electrical conductivity and structural mechanical properties.

[0204] According to some embodiments of the present application, optionally, the roughness of the surface of the metal layer 415 having the corrosion recess 416 satisfies at least one of the following conditions:

[0205] 0.2 μm ≤ Ra ≤ 1 μm;

[0206] 1 μm ≤ Rz ≤ 3 μm, where Ra refers to the average surface roughness of the metal layer 415, and Rz refers to the overall surface roughness of the metal layer 415.

[0207] The roughnesses Ra and Rz respectively refer to two parameters used to characterize the surface roughness. Among them, Ra refers to the average surface roughness of the metal layer 415, that is, the arithmetic mean of the absolute values of the profile offsets within the sampling length. Rz refers to the overall surface roughness of the metal layer 415, that is, the average of the undulations of the surface within adjacent sampling lengths.

[0208] The roughness Ra can be but is not limited to 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, etc. The roughness Rz can be but is not limited to 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, etc.

[0209] With such a design, the metal layer 415 has a relatively high roughness, improving the bonding force on the metal layer 415, thereby being beneficial to improving the reliability of the secondary battery 41.

[0210] According to some embodiments of the present application, the present application provides a current collector 500, and the current collector 500 includes the metal layer 415 of any one of the above.

[0211] Among them, the current collector 500 can be a common current collector 500, that is, only the metal layer 415; or it can be a composite current collector 500, which may include the metal layer 415 and the substrate layer 510.

[0212] With such a design, by using the above metal layer 415, it has a higher surface roughness, which is beneficial to improving the adhesion on the metal layer 415, thereby improving the reliability of the battery.

[0213] According to some embodiments of the present application, optionally, please refer to Figure 15 , the current collector 500 further includes a substrate layer 510, the metal layer 415 is disposed on at least one side surface of the substrate layer 510, and the corrosion recess 416 is disposed on the side of the metal layer 415 facing away from the substrate layer 510.

[0214] The substrate layer 510 refers to the supporting structure in the composite current collector 500, and its material can be selected from at least one of organic polymer insulating materials, inorganic insulating materials, and composite materials. Among them, the organic polymer insulating material is preferably at least one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylenediamine terephthalate), polypropylene, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyvinylidene fluoride, silicone rubber, and polycarbonate. The inorganic insulating material is preferably at least one of alumina, silicon carbide, and silicon dioxide. The composite material is preferably at least one of epoxy resin glass fiber reinforced composite material and polyester resin glass fiber reinforced composite material.

[0215] At the same time, the combination between the substrate layer 510 and the metal layer 415 can be, but is not limited to, evaporation plating, electroplating, electroless plating, glue bonding, etc.

[0216] With such a design, by using the above metal layer 415, the combination between the current collector 500 and the active layer is made closer, which is beneficial to improving the reliability of the secondary battery 41.

[0217] According to some embodiments of the present application, the present application provides a pole piece, and the pole piece includes the above current collector 500.

[0218] According to some embodiments of the present application, the present application provides an electrode assembly 413, and the electrode assembly 413 includes the above pole piece.

[0219] According to some embodiments of the present application, the present application provides a secondary battery 41, and the secondary battery 41 includes the above electrode assembly 413.

[0220] According to some embodiments of the present application, the present application provides an electrical device 400, and the electrical device 400 includes the above secondary battery 41.

[0221] According to some embodiments of the present application, please refer to Figures 1 to 15 , the present application provides an etching roller 100 and a metal layer 415. The etching roller 100 has a conveying channel 11 inside, and discharge holes 12 are provided on the inner wall of the conveying channel 11. At the same time, the etching roller 100 has an etching portion 20, and the discharge holes 12 extend into the etching portion 20 for communicating with the outside of the etching roller 100. Among them, the etching portion 20 may include one of a groove 21, a protrusion 23, and a recess 24. In addition, for the metal layer 415 formed by etching, the etching recess 416 formed on its surface has a depth-to-thickness ratio of the metal layer 415 controlled to be 0.1 to 0.5.

[0222] In order to make the purpose, technical solutions and advantages of the present application more concise and clear, the present application is described by the following specific embodiments, but the present application is by no means limited to these embodiments. The following described embodiments are only the preferred embodiments of the present application and can be used to describe the present application, and should not be construed as a limitation on the scope of the present application. It should be noted that any modifications, equivalent replacements, and improvements made within the spirit and principle of the present application should be included in the protection scope of the present application.

[0223] To better illustrate the present application, the content of the present application will be further described below in conjunction with embodiments. The following are specific embodiments.

[0224] Embodiment 1

[0225] Etching on the surface of the metal layer 415

[0226] The material of the metal layer 415 is aluminum and its thickness is 1 μm; at the same time, the etching solution is composed of sodium hydroxide with a concentration of 100 g / L, and the brightening solution is 68% nitric acid with a concentration of 400 mL / L. In addition, the etching roller 100 is provided with a groove 21. The groove 21 is trapezoidal along the depth direction. The dimension L1 of the end far from the conveying channel 11 in the axis 13 direction is 1 mm, the dimension L2 of the end far from the conveying channel 11 in the axis 13 direction is 3 mm, and its depth h1 is 3 mm; and the height of one end of the groove 21 protruding from the roller surface 14 is recorded as 3 mm, and the hole area S1 of the discharge hole 12 is 5 mm 2 , and the area of the grid 22 formed by the groove 21 is 10 mm 2 .

[0227] In addition, the depth h5 of the etching recess 416 on the metal layer 415 is 0.1 μm, and the ratio of the depth of the etching recess 416 to the thickness of the metal layer 415 is 0.1.

[0228] The specific etching steps are as follows:

[0229] (1) First, in the liquid preparation tank, sodium hydroxide and deionized water are mixed at a ratio of 100 g of sodium hydroxide to 1 L of water to prepare sodium hydroxide with a concentration of 100 g / L. The liquid preparation tank has a heating function, and the solution temperature is heated to 35°C. The higher the temperature, the faster the corrosion rate. For every 10°C increase in temperature, the corrosion rate doubles.

[0230] (2) The prepared corrosion liquid is pumped into the conveying channel 11 of the corrosion roller 100 through a pump. Through flow adjustment, it is ensured that the liquid outlet holes of the corrosion roller 100 can just soak the engraved grooves 21. At the same time, heat-conducting oil is introduced into the back roller 200, the temperature is set to 35°C, and the pressure is set to 15 N, which plays a role in keeping the corrosion liquid coming out of the engraved grooves 21 of the corrosion roller 100 warm.

[0231] (3) Place the composite current collector 500 at the unwinding position, thread the tape, and use the front part of the sample before formal embossing as the machine-adjusting material. After the sample passes through the roller grid 22-shaped engraved grooves 21 and is embossed by the corrosion roller 100, the reaction time is 3 s. After passing through a section of idler rollers, it passes through spray water to wash away the residual sodium hydroxide. After passing through the squeezing roller, it is then subjected to brightening and cleaning with 68% nitric acid. After cleaning, it passes through water spray again, and then through the squeezing roller to squeeze out the residual moisture. Finally, it is dried in an oven at 80°C and then wound up to obtain the composite aluminum current collector 500 with surface grid 22 and engraved grooves 21.

[0232] (4) When the concentration of the corrosion liquid is constant, the depth of the corrosion engraved grooves 21 is controlled by the time and reaction temperature.

[0233] Preparation of the composite current collector 500

[0234] The material of the base layer 510 is PET with a thickness of 8 μm. The above metal layer 415 and the base layer 510 are combined by means of adhesive coating.

[0235] Preparation of the electrode sheet

[0236] Through the conventional battery coating process, the positive active material LiNi0.8Co0.1Mn0.1O2, conductive carbon black SP, and binder PVDF are dispersed in the solvent NMP in a weight ratio of 98:1:1 and mixed evenly to obtain the positive electrode slurry. The positive electrode slurry is coated on the surface of the above composite current collector 500 and dried at 100°C to obtain the positive electrode sheet. Based on the battery design requirements, different widths of the current collector 500 regions are reserved on both sides of the electrode sheet for welding metal tabs; the active material layer on the surface of the electrode sheet is compacted through the conventional battery cold pressing process, and the compaction density of the positive electrode sheet is set to 3.4 g / cm 3 , and the compaction density of the negative electrode sheet is set to 1.6 g / cm 3 .

[0237] Example 2

[0238] Basically the same as Example 1, except that: the reaction time of etching is 6S, and the depth h5 of the etched recess 416 is 0.2μm.

[0239] Example 3

[0240] Basically the same as Example 1, except that: the reaction time of etching is 10S, and the depth h5 of the etched recess 416 is 0.3μm.

[0241] Example 4

[0242] Basically the same as Example 1, except that: the reaction time of etching is 15S, and the depth h5 of the etched recess 416 is 0.4μm.

[0243] Example 5

[0244] Basically the same as Example 1, except that: the reaction time of etching is 25S, and the depth h5 of the etched recess 416 is 0.5μm.

[0245] Comparative Example 1

[0246] Basically the same as Example 1, except that: the reaction time of etching is 1S, and the depth h5 of the etched recess 416 is 0.09μm.

[0247] Comparative Example 2

[0248] Basically the same as Example 1, except that: the reaction time of etching is 33S, and the depth h5 of the etched recess 416 is 0.6μm.

[0249] Comparative Example 3

[0250] Basically the same as Example 1, except that: the metal layer 415 is not etched by the etching roller 100.

[0251] Example 6

[0252] Basically the same as Example 1, except that: the reaction time of etching is 10S, the depth h5 of the etched recess 416 is 0.3μm, and the area of the grid 22 is 1mm 2 。

[0253] Example 7

[0254] Basically the same as Example 6, except that: the area of the grid 22 is 5mm 2 。

[0255] Example 8

[0256] Basically the same as Example 6, except that: the area of the grid 22 is 20mm 2 。

[0257] Example 9

[0258] It is basically the same as Example 6, except that the area of the grid 22 is 30 mm 2 .

[0259] Example 10

[0260] It is basically the same as Example 6, except that the area of the grid 22 is 50 mm 2 .

[0261] Comparative Example 4

[0262] It is basically the same as Example 6, except that the area of the grid 22 is 0.9 mm 2 .

[0263] Comparative Example 5

[0264] It is basically the same as Example 6, except that the area of the grid 22 is 55 mm 2 .

[0265] Example 11

[0266] It is basically the same as Example 3, except that the corrosion roller 100 has a convex portion 23, the height of the convex portion 23 protruding from the roller surface 14 is 3 mm, and after the metal layer 415 is corroded, the corrosion area of the corrosion recess 416 is 1.0 mm 2 , where the corrosion area of the corrosion recess 416 is the area of the region formed by the corrosion of a single convex portion 23 on the metal layer 415.

[0267] Example 12

[0268] It is basically the same as Example 11, except that the corrosion area of the corrosion recess 416 is 5.0 mm 2 .

[0269] Example 13

[0270] It is basically the same as Example 11, except that the corrosion area of the corrosion recess 416 is 10.0 mm 2 .

[0271] Example 14

[0272] It is basically the same as Example 11, except that the corrosion area of the corrosion recess 416 is 30.0 mm 2 .

[0273] Example 15

[0274] It is basically the same as Example 11, except that the corrosion area of the corrosion recess 416 is 50 mm 2 .

[0275] Comparative Example 6

[0276] It is basically the same as Example 11, except that: the etched area of the etched recess 416 is 0.8 mm 2 .

[0277] Comparative Example 7

[0278] It is basically the same as Example 11, except that: the etched area of the etched recess 416 is 55 mm 2 .

[0279] In each of the examples and comparative examples, the sheet resistance, roughness, and surface dyne value of the metal layer 415 were tested; the strength and elongation of the composite current collector 500 were tested; and the bonding strength of the electrode sheet was tested. The specific test methods are as follows; meanwhile, the test results and related parameters can be referred to in Tables 1 and 2.

[0280] Test method for the sheet resistance of the surface of the metal layer 415: Use a four-probe sheet resistance tester to test the sheet resistance of the large surface of the sample metal layer 415. Randomly test 30 points, with the probes spanning the etched area and the unetched area, and take the average value of the sheet resistance of the 30 points.

[0281] Test method for the surface roughness of the metal layer 415: Use a roughness tester for testing, and take the Ra value and the Rz value.

[0282] Average Ra = sum of the Ra values of 10 test points / 10 units (μm)

[0283] Average Rz = sum of the Rz values of 10 test points / 10 units (μm)

[0284] Test method for the surface dyne value of the metal layer 415: Use a dyne pen with a number ≥ 38# to draw lines horizontally and vertically on the surface of the metal layer 415. Check if there are any breaks in the lines within 2S. If not, it is judged to be qualified.

[0285] Test method for the strength and elongation of the composite current collector 500: Use a standard sampler to cut the sample into 10 strips each 15 mm wide and 15 cm long along the MD / TD direction; fix the sample on the fixture of a tensile testing machine, set the speed at 50 mm / min, and the gauge length between the clips at 50 mm, and conduct a tensile test to obtain the maximum strength and elongation corresponding to the broken state.

[0286] Strength = sum of the maximum tensile strengths of 10 samples / 10 units (MPa);

[0287] Elongation = sum of the maximum tensile strengths of 10 samples / 10 units (%).

[0288] Pole piece adhesion test method: Stick 3M double-sided tape on a steel plate. The width of the tape is 20 mm and the length is 50 mm. Cut the pole piece into a width of 20 mm and a length of 150 mm and stick it on the tape. Use a high-speed tensile machine to measure the bonding force between the active material layer and the metal layer 415, and the tensile speed is 5 mm / min.

[0289] Average value of pole piece bonding force = sum of bonding force values of 10 samples / 10 unit (N / m).

[0290] Table 1

[0291]

[0292]

[0293] Table 2

[0294]

[0295]

[0296] It can be seen from this that in Examples 1 to 5 and Comparative Examples 1 to 3, when the type of the corrosion part 20 is the groove 21, when the depth of the groove 21 is less than 0.1 μm and the ratio A to the metal layer 415 is also less than 0.1, the corrosion of the groove 21 is not very helpful for improving the roughness. When the depth of the groove 21 is greater than 0.5 μm and the ratio A to the metal layer 415 is also greater than 0.5, although the Ra and Rz values of the roughness are greatly improved and the pole piece adhesion is also greatly improved, the excessive corrosion leads to an increase in the sheet resistance, a decrease in conductivity, and a serious decrease in the tensile mechanical properties, affecting the use. Therefore, it is recommended that the depth of the groove 21 be kept at 0.1 μm to 0.5 μm, and the ratio of the corrosion depth to the metal layer 415 be kept at 0.1 to 0.5.

[0297] It can be seen from Examples 3, 6 to 10 and Comparative Examples 4 to 5 that when the depth of the groove 21 is kept at 0.3 μm, the corrosion density of the groove 21 can be controlled by controlling the area of the grid 22. When the area of the grid 22 is less than 1 mm 2 When, almost all of the metal layer 415 of the composite current collector 500 is covered by the grid 22, the corrosion density is large, and the corrosion liquid is likely to overflow, corroding most of the surface metal layer 415. Therefore, the roughness is not greatly improved; at the same time, the pole piece adhesion also has no significant improvement effect. However, most of its metal layer 415 is corroded, resulting in a reduction in the thickness of the metal layer 415, an increase in the sheet resistance, and a decrease in the tensile mechanical properties. When the area of the grid 22 is greater than 50 mm 2 When, the corrosion density on the large surface of the metal layer 415 decreases, the range of roughness improvement is limited, and the overall pole piece adhesion is not effectively improved. Therefore, the area of the grid 22 is kept at 1 mm 2 ~50 mm 2, it can not only ensure the improvement of roughness but also not affect the sheet resistance conductivity and mechanical properties of the current collector 500.

[0298] From Examples 11 to 15 and Comparative Examples 3, 6, and 7, it can be seen that when the type of the corrosion part 20 is the protrusion part 23 or the depression part 24, taking the protrusion part 23 as an example in this embodiment, when the corrosion depth is maintained at 0.3 μm, the ratio A is 0.3, and the corrosion area is less than 1 mm 2 , the improvement of roughness is not obvious, and at the same time, the adhesion of the electrode sheet is not much improved. When the corrosion area is greater than 50 mm 2 , the roughness is significantly improved, and the adhesion of the electrode sheet is also effectively improved. However, after the corrosion area increases, the thickness of the comprehensive metal layer 415 decreases and the sheet resistance increases; at the same time, the mechanical tensile property decreases significantly. Therefore, it is recommended that the corrosion area be maintained at 1 mm 2 ~50 mm 2 , it can not only ensure the improvement of roughness but also not affect the sheet resistance conductivity and mechanical properties of the current collector 500.

[0299] Generally speaking, at the same corrosion depth, the corrosion roller 100 scheme with the grooving 21 is more advantageous for improving roughness compared to the corrosion schemes of the protrusion part 23 or the depression part 24 because its grid 22 - shaped corrosion density is greater and the corrosion uniformity is better. However, because it belongs to line corrosion and mainly controls the grid 22 density, on the premise of ensuring basic mechanics and sheet resistance, its roughness improvement ability is greater than that of surface corrosion, and the corrosion uniformity of surface corrosion is worse than that of line corrosion.

[0300] In summary, the surface treatment device for the composite current collector 500 and the high - roughness composite current collector 500 after treatment disclosed in this patent can not only effectively improve the roughness of the composite current collector 500 but also not affect its basic mechanical properties and conductivity, greatly improve the bonding force between the current collector 500 and the active material layer, ensure the reliability of the battery cell during long - term cyclic storage, and at the same time has the advantage of cost reduction.

[0301] The technical features of the above - described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above - described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0302] The above - described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be subject to the appended claims.

[0303] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is 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 should not be construed as a limitation on the present invention.

[0304] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0305] In the present invention, unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0306] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0307] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this article are only for the purpose of illustration and do not represent the only implementation.

Claims

1. An etching roller, characterized in that, the etching roller comprises: a roller body (10) provided with a conveying channel (11) extending along its own axis (13); an etching part (20) provided on the roller body (10), a discharge hole (12) is provided on the inner wall of the conveying channel (11), the discharge hole (12) extends to the etching part (20) and is used to communicate with the outside of the etching roller on the etching part (20).

2. The etching roller according to claim 1, characterized in that, The hole area of the discharge hole (12) is denoted as S1, where 1 mm 2 ≤ S1 ≤ 10 mm 2 ; Optionally, the pore area S1 further satisfies the condition that: 3 mm 2 ≤ S1 ≤ 7 mm 2 .

3. The etching roller according to claim 1, characterized in that, the roller body (10) has a roller surface (14) circumferentially arranged around its own axis (13), at least part of the etching part (20) is provided on the roller surface (14); and / or, at least part of the etching part (20) is provided inside the roller body (10), and the end far from the conveying channel (11) is not lower than the roller surface (14).

4. The etching roller according to claim 3, characterized in that, the etching part (20) includes a groove (21), the groove (21) is provided inside the roller body (10), and the end far from the conveying channel (11) is not lower than the roller surface (14), and the discharge hole (12) communicates with the outside of the etching roller through the groove (21).

5. The etching roller according to claim 4, characterized in that, the dimension of the end of the groove (21) far from the conveying channel (11) in the direction of the axis (13) is smaller than the dimension of the end of the groove (21) close to the conveying channel (11) in the direction of the axis (13).

6. The etching roller according to claim 5, characterized in that, the dimension of the end of the groove (21) far from the conveying channel (11) in the direction of the axis (13) is denoted as L1, wherein, 0.5 mm ≤ L1 ≤ 1.5 mm; Optionally, the condition that the dimension L1 further satisfies is: 0.8 mm ≤ L1 ≤ 1.2 mm.

7. The etching roller according to claim 5, characterized in that, the dimension of the end of the groove (21) close to the conveying channel (11) in the direction of the axis (13) is denoted as L2, wherein, 2 mm ≤ L2 ≤ 5 mm; Optionally, the condition that the dimension L2 further satisfies is: 2.5 mm ≤ L2 ≤ 4 mm.

8. The etching roller according to claim 4, characterized in that, the depth of the groove (21) is denoted as h1, wherein, 1 mm ≤ h1 ≤ 5 mm; Optionally, the condition that the dimension h1 further satisfies is: 2 mm ≤ h1 ≤ 4 mm.

9. The etching roller according to claim 4, characterized in that, the groove (21) includes a plurality of grooves, at least part of the grooves (21) extend and intersect on the roller surface (14) to enclose a plurality of meshes (22).

10. The etching roller according to claim 9, characterized in that, The area of the grid (22) is denoted as S2, where 1 mm 2 ≤ S2 ≤ 50 mm 2 ; Optionally, the condition that the area S2 also satisfies is: 5 mm 2 ≤ S2 ≤ 30 mm 2 .

11. The etching roller according to any one of claims 3-10, characterized in that, The corrosion part (20) includes a convex part (23) which is arranged on the roller surface (14), and one end of the discharge hole (12) extends to the surface of the convex part (23).

12. The corrosion roller according to claim 11, wherein, the height by which the convex part (23) protrudes from the roller surface (14) is denoted as h2, where 1 mm ≤ h2 ≤ 5 mm; Optionally, the dimension h2 further satisfies the condition: 2 mm ≤ h2 ≤ 4 mm.

13. The corrosion roller according to any one of claims 3-10, wherein, the corrosion part (20) includes a concave part (24) which is arranged on the roller surface (14) and concaves towards the conveying channel (11), and one end of the discharge hole (12) extends into the concave part (24).

14. The corrosion roller according to claim 13, wherein, the depth of the concave part (24) is denoted as h3, where 1 mm ≤ h3 ≤ 5 mm; Optionally, the dimension h3 further satisfies the condition: 2 mm ≤ h3 ≤ 4 mm.

15. A corrosion device, wherein, the corrosion device includes: a back roller (200); a corrosion roller according to any one of claims 1-14, and a metal layer is adapted to pass between the corrosion roller and the back roller (200).

16. The corrosion device according to claim 15, wherein, the corrosion device further includes a heater for heating the back roller (200) and / or the corrosion roller.

17. The corrosion device according to claim 15 or 16, wherein, the corrosion device further includes a collection tank (300) for recovering the corrosion liquid on the corrosion roller.

18. A processing method for a metal layer, wherein, using the corrosion device according to any one of claims 15-17, the processing method for the metal layer includes the following steps: introducing a corrosion liquid into the conveying channel (11) and driving the corrosion roller to rotate around its own axis (13); cleaning and drying the metal layer passing through the corrosion roller.

19. The processing method for a metal layer according to claim 18, wherein, the parameters of the corrosion liquid include at least one of the following: the temperature of the corrosion liquid is 25°C to 80°C; the concentration of the corrosion liquid is 80 g / L to 120 g / L.

20. The processing method for a metal layer according to claim 18, wherein, the components of the corrosion liquid include at least one of sodium hydroxide, potassium hydroxide, phosphoric acid, acetic acid, nitric acid, and sulfuric acid; or, the components of the corrosion liquid include a ferric ion compound.

21. The processing method for a metal layer according to claim 20, wherein, the step of cleaning and drying the metal layer passing through the corrosion roller includes: washing and squeezing the metal layer; cleaning the squeezed metal layer with a brightening liquid; successively washing, squeezing, and drying the cleaned metal layer.

22. The processing method for a metal layer according to claim 21, It is characterized in that, the components of the light-emitting liquid include nitric acid, wherein the concentration of the nitric acid is 300 mL / L to 500 mL / L.

23. A metal layer, It is characterized in that, the metal layer is etched by the etching equipment described in any one of claims 15-17; or, the metal layer is processed by the processing method of the metal layer described in any one of claims 18-22, and the surface of the metal layer has etching recesses (416).

24. The metal layer according to claim 23, It is characterized in that, the thickness of the metal layer is denoted as h4, and the depth of the etching recesses (416) is denoted as h5, wherein 0.1 ≤ h5 / h4 ≤ 0.

5.

25. The metal layer according to claim 24, It is characterized in that, the condition satisfied by the thickness h4 is: 0.7 μm ≤ h4 ≤ 2 μm; Optionally, the condition further satisfied by the thickness h4 is: 1 μm ≤ h4 ≤ 1.5 μm.

26. The etching roller according to claim 23, It is characterized in that, The area of the corrosion recess (416) is denoted as S3, where 1 mm 2 ≤ S3 ≤ 50 mm 2 ; Optionally, the condition that the area S3 also satisfies is: 5 mm 2 ≤ S3 ≤ 30 mm 2 .

27. The metal layer according to any one of claims 23-26, It is characterized in that, the surface roughness of the surface of the metal layer having the etching recesses (416) satisfies at least one of the following conditions: 0.2 μm ≤ Ra ≤ 1 μm; 1 μm ≤ Rz ≤ 3 μm, wherein Ra refers to the surface average roughness of the metal layer, and Rz refers to the overall surface roughness of the metal layer.

28. A current collector, It is characterized in that, the current collector includes the metal layer according to any one of claims 23-27.

29. The current collector according to claim 28, It is characterized in that, the current collector further includes a substrate layer (510), the metal layer is provided on at least one side surface of the substrate layer (510), and the etching recesses (416) are provided on the side of the metal layer facing away from the substrate layer (510).

30. An electrode sheet, It is characterized in that, the electrode sheet includes the current collector according to claim 28 or 29.

31. An electrode assembly (413), It is characterized in that, the electrode assembly (413) includes the electrode sheet according to claim 30.

32. A secondary battery (41), It is characterized in that, the secondary battery (41) includes the electrode assembly (413) according to claim 31.

33. An electrical device (400), It is characterized in that, the electrical device (400) includes the secondary battery (41) according to claim 32.

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