A method for three-dimensionally rolling a surface of a current collector foil

Abstract

The application provides a surface three-dimensional rolling method of a current collector foil, comprising the following steps: step 100, two rollers with smooth surfaces are respectively arranged on a numerical control lathe, the laser frequency is controlled according to the roller circumference and the rotating speed, the roller circumference is proportionally divided along the circumferential direction, the moving speed of the laser head along the axial direction of the roller is controlled, the roller surface length is divided according to the interval distance, and finally the roughening protrusions with the predetermined size and distribution position are processed on the roller surface, so that the roughening protrusions on the surfaces of the two rollers can be engaged with each other in a staggered mode; and step 200, the prepared roller pair is assembled on a rolling mill, the foil is passed through the gap between the two rollers, and the rolling force is applied on any surface of the foil to form a surface three-dimensional structure composed of staggered concave-convex structures. The foil rolled by the method provided by the application has improved surface roughness and roughening structure connectivity, reduced elastic modulus, and solves the problem that the surface three-dimensional structure of the foil prepared by the roughening rolling method is not complete.

Description

Technical Field

[0001] This invention relates to the field of electrochemical energy storage, and in particular to a method for three-dimensional surface rolling of current collector foil. Background Technology

[0002] In electrochemical energy storage devices, active materials are coated onto the surface of current collector foil to form electrodes. The foil serves to carry the electrode material and transport electrons. The electrical contact performance between the electrode layer and the current collector foil affects the device's internal resistance, which in turn affects the device's high-rate performance and cycle capacity retention. Therefore, modification of the current collector is necessary.

[0003] To improve the energy density of electrochemical energy storage devices, current collector foils are being developed towards ultrathin designs. There is a need to investigate a surface modification method for current collector foils that can both increase the specific surface area of ​​the foil and improve the adhesion between the active layer and the foil, while also reducing the constraint of the current collector foil on the volume change of the electrode layer and controlling the electrode stress.

[0004] Existing texturing rolling methods produce foils with obvious uneven textures parallel to the rolling direction. The three-dimensionality of the foil surface is incomplete, which is not conducive to controlling the elastic modulus of the foil and also reduces the connectivity of the texturing structure on the aluminum foil surface. Summary of the Invention

[0005] This invention provides a method for three-dimensional rolling of current collector foil, which improves the surface roughness and connectivity of the roughened structure of the rolled foil, reduces the elastic modulus, and solves the problem of incomplete three-dimensional surface formation of foil prepared by the roughening rolling method.

[0006] A method for three-dimensional rolling of a current collector foil includes the following steps:

[0007] Step 100: Place two smooth rolls on a CNC lathe. Based on the roll circumference and rotation speed, control the laser frequency and divide the roll circumference proportionally along the roll circumference. At the same time, control the laser head's movement speed along the roll axial direction and divide the roll surface length according to the interval distance. Finally, process roughened protrusions of predetermined size and distribution position on the roll surface so that the roughened protrusions on the two roll surfaces can be staggered and interlocked.

[0008] The texturing protrusion is formed by providing one or more independent protrusions on the edge of the texturing pit, thus creating an integrated structure with a non-smooth surface.

[0009] Step 200: Assemble the prepared roll pair on the rolling mill, pass the foil through the gap between the two rolls, adjust the relative position of the two rolls, and apply rolling force to form a three-dimensional surface structure composed of staggered pits and peaks on any surface of the foil.

[0010] Furthermore, the distribution pattern A of the texturing protrusions on the circumferential position of the roll surface is such that the interval between adjacent texturing protrusions is divisible by the circumference of the roll in which they are located.

[0011] Furthermore, the distribution pattern B of the texturing protrusions on the circumferential position of the roll surface is as follows: the interval between adjacent texturing protrusions is divided by the circumference of the roll in which they are located, and the remainder is half of the interval between adjacent texturing protrusions.

[0012] Furthermore, the axial texturing protrusions on the surfaces of the two rolls are distributed along a spiral line. When the circumferential texturing protrusions on the surfaces of the two rolls are distributed in the same way as distribution mode B, the spiral lines on the surfaces of the two rolls are in opposite directions. When the circumferential texturing protrusions on the surfaces of the two rolls are distributed in other ways, the spiral lines on the surfaces of the two rolls are not required to be in the same direction.

[0013] Furthermore, the axial spacing between adjacent texturing protrusions on the surface of each roll is 1.25-2.5 times the diameter of the texturing protrusion.

[0014] Furthermore, the roughened protrusions on the surfaces of the two rolls are staggered circumferentially, or axially, or both circumferentially and axially.

[0015] Furthermore, the textured protrusions are structured such that one or more independent protrusions are provided at the edge of the textured pit, including single protrusions, double protrusions, and triple protrusions.

[0016] Furthermore, within a single texturing protrusion, the projected area of ​​the texturing pit is greater than the projected area of ​​each individual protrusion; the diameter of the texturing protrusion is the diameter of the texturing pit; the height of the texturing protrusion is the height of the highest protrusion among all the individual protrusions; and the spacing between adjacent texturing protrusions is the spacing between adjacent texturing pits.

[0017] Furthermore, the diameter of the texturing protrusion is 60–120 μm, and the height of the texturing protrusion is 1.5–4.0 times the thickness of the foil.

[0018] Furthermore, the thickness of the foil is 3–20 μm.

[0019] Furthermore, the surface roughness Ra of the foil with a three-dimensional structure after rolling is 1.5 to 3.0 μm, and the profile value is 1.5 to 4.0 times that of the base foil;

[0020] Among them, compared with the base foil, the elastic modulus decreases by 10-20%, the tensile strength decreases by less than 10%, and the elongation decreases by less than 20%.

[0021] Compared with the prior art, the present invention has the following beneficial effects: By improving the texturing technology, the present invention adds a convex structure to the edge of the texturing pit to form a texturing protrusion. A three-dimensional surface structure composed of pits and peaks can be formed at each embossing point on the upper and lower surfaces of the foil. This rolling method can thoroughly modify the foil in three dimensions, ensuring that the foil has high surface roughness and high surface structure connectivity, reducing the elastic modulus of the foil, reducing the constraint of the current collector on the volume change of the electrode layer, regulating the electrode stress, and ensuring the basic mechanical properties (tensile strength and elongation) of the foil, thus meeting the requirements of the electrode preparation process. Attached Figure Description

[0022] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of the rolling method in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the textured protrusion structure in an embodiment of the present invention, wherein I is a schematic diagram of a textured protrusion structure with a single protrusion, II is a schematic diagram of a textured protrusion structure with two protrusions, and III is a schematic diagram of a textured protrusion structure with three protrusions.

[0025] Figure 3 This is a schematic diagram of the foil rolling process according to the first embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the distribution of pits and peaks on the surface of the foil prepared in the first embodiment of the present invention;

[0027] Figure 5 This is a photograph of the foil surface according to the first embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the foil rolling process according to the second embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the distribution of pits and peaks on the surface of the foil prepared in the second embodiment of the present invention;

[0030] Figure 8 This is a photograph of the foil surface according to the second embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of the foil rolling process according to the third embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of the distribution of pits and peaks on the surface of the foil prepared in the third embodiment of the present invention;

[0033] Figure 11 This is a photograph of the foil surface according to the third embodiment of the present invention;

[0034] The characters in the image represent:

[0035] b is the texturing pit, c is the independent convex point, d is the diameter of the texturing pit, I is the texturing protrusion with a single convex point, II is the texturing protrusion with two convex points, III is the texturing protrusion with three convex points, s is the circumferential spacing distance, sl is the helix, h is the lead of the helix sl, i.e., the axial spacing distance, and t is the thickness of the foil.

[0036] 1 and 2 are rollers, 3 is foil, 3-1 is the pit and reverse convex peak formed by roller 1 on one surface of foil 3, and 3-2 is the pit and reverse convex peak formed by roller 2 on the other surface of foil 3. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, a method for three-dimensional surface rolling of a current collector foil includes the following steps:

[0039] Step 100: Place two smooth rolls on a CNC lathe. Based on the roll circumference and rotation speed, control the laser frequency and divide the roll circumference proportionally along the roll circumference. Simultaneously, control the laser head's movement speed along the roll axial direction and divide the roll surface length according to the interval distance. Finally, process roughened protrusions of predetermined size and distribution position on the roll surface so that the roughened protrusions on the two roll surfaces can be staggered and interlocked. The roughened protrusions are formed by setting one or more independent protrusions on the edge of the roughened pit, forming an integrated structure with a non-smooth surface.

[0040] like Figure 2As shown, the textured protrusions have one or more independent protrusions at the edge of the textured pit, including single, double, and triple protrusions. By adjusting the laser texturing process, a single protrusion can be formed at the tail of the textured pit formed by the laser scanning roller, double protrusions can be formed on both sides of the textured pit, or a multi-protrusion structure such as triple protrusions can be formed simultaneously at the tail and both sides of the textured pit. The improved textured protrusion structure increases the protrusion height, enabling the formation of a three-dimensional surface structure composed of pits and peaks at each embossing point on the upper and lower surfaces of the foil.

[0041] In this embodiment, the projected area of ​​the fibrous pit is greater than the projected area of ​​each independent protrusion, the diameter of the fibrous protrusion is the diameter of the fibrous pit, the height of the fibrous protrusion is the height of the highest protrusion among all the independent protrusions, and the interval between adjacent fibrous protrusions is the interval between adjacent fibrous pits.

[0042] It should be noted that in this embodiment, the independent protrusions are located at the edge of the texturing pit in order to facilitate the overall size measurement of the texturing protrusion structure. The design of the surface three-dimensional structure in this invention is not limited to the texturing protrusion structure mentioned above, but also includes, but is not limited to, protrusion structures with protrusions located inside the texturing pit, protrusion structures with more than three protrusions, and structures with a total projected area of ​​protrusions that is less than or greater than the projected area of ​​the texturing pit.

[0043] Step 200: Assemble the prepared roll pair on the rolling mill, pass the foil through the gap between the two rolls, adjust the relative position of the two rolls, and apply rolling force to form a three-dimensional surface structure composed of staggered pits and peaks on any surface of the foil.

[0044] This invention provides a method for three-dimensional surface rolling of current collector foil, which can form a three-dimensional surface structure composed of non-penetrating pits and peaks on the upper and lower surfaces of the foil. Specifically, each embossed area on the same surface consists of a three-dimensional surface structure composed of pits and peaks. This rolling method can thoroughly modify the foil to three dimensions, solving the problem of incomplete three-dimensional surface modification in conventional texturing rolling methods.

[0045] In one embodiment, the distribution pattern A of the texturing protrusions on the circumferential position of the roll surface is such that the interval between adjacent texturing protrusions is divisible by the circumference of the roll in which they are located. For example, if the circumference of the roll is 314 mm, the interval between adjacent texturing protrusions is 0.157 mm.

[0046] In another embodiment, the distribution pattern B of the texturing protrusions on the circumferential position of the roll surface is as follows: the distance between adjacent texturing protrusions is divided by the circumference of the roll in which they are located, and the remainder is half of the distance between adjacent texturing protrusions. For example, if the circumference of the roll is 300.075 mm, the distance between adjacent texturing protrusions is 0.150 mm.

[0047] In this invention, the axially distributed texturing protrusions on the surfaces of the two rolls are respectively distributed along a spiral, and the lead of the spiral is the axial spacing between the texturing protrusions. The moving speed of the laser head along the axial direction of the roll is equal to the spiral lead multiplied by the roll rotation speed. The lead of the spiral of the texturing protrusions on the surface of each roll is 1.25-2.5 times the diameter of the texturing protrusion.

[0048] When the circumferential textured protrusions on the surfaces of the two rolls are distributed in the same pattern B, the spiral directions of the two roll surfaces are opposite. When the circumferential textured protrusions on the surfaces of the two rolls are distributed in other patterns, the spiral directions of the two roll surfaces are not required. The specific details are as follows:

[0049] When the distribution of the circumferential texturing protrusions on the surface of the rolls is either distribution pattern A or B, the circumferential spacing of the texturing protrusions is the same, and the axial spacing is the same. When the distribution pattern is B, the directions of the processing spirals are opposite, and the pits and peaks on the surface of the rolled foil are staggered along both the rolling direction and the transverse direction. When the distribution pattern is A, the directions of the processing spirals can be opposite or the same. When the directions of the processing spirals are opposite, the pits and peaks on the surface of the rolled foil are staggered along both the rolling direction and the transverse direction. When the directions of the processing spirals are the same, the pits and peaks on the surface of the rolled foil are completely staggered along the rolling direction and partially staggered along the transverse direction.

[0050] When the distribution of the circumferentially textured protrusions on the surface of the roll is different, the circumferential spacing of the textured protrusions in distribution mode B is twice that of distribution mode A, the axial spacing of the textured protrusions in distribution mode B is half that of distribution mode A, the spiral direction of the processing spiral is the same, and the pits and peaks on the surface of the foil after rolling are completely staggered along the rolling direction and partially staggered along the transverse direction.

[0051] The positions of the texturing protrusions on the surfaces of the two rolls are staggered circumferentially, axially, or both, through a combination of circumferential and axial distribution. This ensures that the positions of the double-sided pits and peaks after foil rolling are staggered either along the rolling direction, laterally, or both, preventing the pits and peaks from overlapping on the upper and lower surfaces of the foil and causing abnormal local thinning, thus guaranteeing the mechanical properties of the foil.

[0052] At the same time, it can further ensure that the positions of the pits and peaks on the surface of the foil after rolling are regularly staggered, without parallel rolling direction of pits and peaks, and the surface roughening structure of the foil has good connectivity.

[0053] With the above settings, current collector foils with three-dimensional surface structures can be rolled. The rollable foil materials are common current collector materials, such as aluminum and copper, with a thickness of 3–20 μm, a roughened protrusion diameter of 60–120 μm, and a roughened protrusion height of 1.5–4.0 times the foil thickness. After rolling, the foil with a three-dimensional surface structure has a surface roughness Ra of 1.5–3.0 μm, a three-dimensional profile value of 1.5–4.0 times that of the base foil, and a 10–20% reduction in elastic modulus, a less than 10% decrease in tensile strength, and a less than 20% decrease in elongation compared to the base foil.

[0054] This invention designs the structure and distribution of the roughened protrusions on the surface of the rolls to ensure that the roughened protrusions on the surfaces of the two rolls are staggered and interlocked during the rolling process. This forms non-overlapping pits and peaks on the upper and lower surfaces of the foil, ensuring that the foil has high surface roughness and high surface structure connectivity. This reduces the elastic modulus of the foil, reduces the constraint of the current collector on the volume change of the electrode layer, regulates the electrode stress, and at the same time ensures the basic mechanical properties (tensile strength and elongation) of the foil, thus meeting the requirements of the electrode preparation process.

[0055] The above method will be specifically described below with reference to specific embodiments.

[0056] Example 1:

[0057] according to Figure 1 The steps shown involve first using a spindle encoder and software-controlled laser to emit light on a CNC lathe to roughen the rolls. Rolls 1 and 2 have circumferences of 250.125 mm, a roll rotation speed of 60 rpm, and a laser frequency of 1 kHz. This forms roughening protrusions I (e.g., roughening pits b and single-sided protrusions c) on the surfaces of rolls 1 and 2. Figure 2 As shown), the diameter d of the texturing pit b is 100 μm, and the height of the single-sided protrusion c is 15 μm. The circumferential positions of the texturing protrusions I are all distributed in distribution mode B, and the circumferential spacing s is the same. The texturing protrusions I are processed along the spiral sl, and the spiral directions are opposite, one is left-handed and the other is right-handed, with the same lead h. The processing rotation directions of rolls 1 and 2 are opposite, one is clockwise and the other is counterclockwise.

[0058] Then as Figure 3 As shown, rolls 1 and 2 are assembled into a roll pair on the rolling mill. The circumferential spacing s of the texturing protrusions I is 250 μm, and the lead h of the helix sl is 125 μm, forming a rhomboid distribution. An aluminum foil 3 with a thickness t of 10 μm is passed through the roll gap. After applying pressure, the foil surface is observed, and the relative positions of rolls 1 and 2 are adjusted to ensure that the texturing protrusions I on the surfaces of rolls 1 and 2 are staggered and interlocked with each other circumferentially and axially, respectively. Then, rolling begins.

[0059] like Figure 4As shown, the surface roughening protrusion I of the roll 1 is pressed into the aluminum foil 3 to form a pit and a reverse protrusion 3-1 (details of the pit and protrusion are not shown in the figure). The surface roughening protrusion I of the roll 2 is pressed into the other surface of the aluminum foil 3 to form a pit and a reverse protrusion 3-2. The pits and protrusions 3-1 and 3-2 on the two surfaces of the aluminum foil 3 do not overlap and are staggered from each other along the rolling direction and the transverse direction. Figure 5 This is a photograph of the surface of the rolled foil.

[0060] Example 2:

[0061] according to Figure 1 The steps shown involve first using a spindle encoder and software to control the laser emission on a CNC lathe to roughen the rolls. Rolls 1 and 2 have a circumference of 250 mm each, a roll rotation speed of 60 rpm, and a laser frequency of 1 kHz. This creates roughening protrusions (such as) I on the surfaces of rolls 1 and 2, consisting of roughening pits b and single-sided protrusions c. Figure 2 As shown, the diameter d of the texturing pit b is 100 μm, and the height of the single-sided protrusion c is 15 μm. The circumferential positions of the texturing protrusions I are all distributed in distribution pattern A, and the circumferential spacing s is the same. The texturing protrusions I are processed along the spiral sl, and the spiral directions are opposite, one is left-handed and the other is right-handed, with the same lead h. The processing rotation directions of rolls 1 and 2 are opposite, one is clockwise and the other is counterclockwise.

[0062] Then as Figure 6 As shown, rolls 1 and 2 are assembled into a roll pair on the rolling mill. The circumferential spacing s of the texturing protrusions I is 200 μm, and the lead h of the helix sl is 250 μm, forming a near-rectangular distribution. An aluminum foil 3 with a thickness t of 10 μm is passed through the roll gap. After applying pressure, the foil surface is observed, and the relative positions of rolls 1 and 2 are adjusted to ensure that the texturing protrusions I on the surfaces of rolls 1 and 2 are staggered and interlocked with each other circumferentially and axially, respectively. Then, rolling begins.

[0063] like Figure 7 As shown, the roughened protrusion I on the surface of the roll 1 is pressed into the aluminum foil 3 to form a pit and a reverse protrusion 3-1. The roughened protrusion I on the surface of the roll 2 is pressed into the other surface of the aluminum foil 3 to form a pit and a reverse protrusion 3-2. The pits and protrusions 3-1 and 3-2 on the two surfaces of the aluminum foil 3 do not overlap and are staggered from each other along the rolling direction and the transverse direction. Figure 8 This is a photograph of the surface of the rolled foil.

[0064] Example 3:

[0065] according to Figure 1The steps shown involve first using a spindle encoder and software to control the laser emission on a CNC lathe to roughen the rolls. Rolls 1 and 2 have a circumference of 250.25 mm, a roll rotation speed of 60 rpm, a laser frequency of 1.001 kHz for roll 1, and a laser frequency of 0.5 kHz for roll 2. This forms roughening protrusions (such as) I on the surfaces of rolls 1 and 2, consisting of roughening pits b and single-sided protrusions c. Figure 2 As shown, the diameter d of the texturing pit b is 100 μm, and the height of the single-sided protrusion c is 15 μm. The circumferential positions of the texturing protrusions I on the surface of roll 1 are distributed in pattern A, and the circumferential positions of the texturing protrusions I on the surface of roll 2 are distributed in pattern B. The circumferential spacing s2 of roll 2 is twice that of roll 1. The spiral direction of the processing spiral sl of the texturing protrusions I on the surfaces of rolls 1 and 2 is the same, and the lead h2 is half the lead h1. Rolls 1 and 2 rotate in opposite directions, one in the forward direction and the other in the reverse direction.

[0066] Then as Figure 9 As shown, rolls 1 and 2 are assembled into a roll pair on the rolling mill. The lead h1 of the processing spiral sl of roll 1 and the circumferential spacing s1 of the texturing protrusions are both 250 μm, forming a near-rectangular distribution. The lead h2 of the processing spiral sl of roll 2 is 125 μm, and the circumferential spacing s2 of the texturing protrusions is 500 μm, forming a near-rhomboid distribution. A 10 μm thick aluminum foil 3 is passed through the roll gap. After applying pressure, the foil surface is observed. The relative positions of rolls 1 and 2 are adjusted to ensure that the texturing protrusions I on the surfaces of rolls 1 and 2 are staggered and interlocked circumferentially, and then rolling begins.

[0067] like Figure 10 As shown, the roughened protrusion I on the surface of the roll 1 is pressed into the aluminum foil 3 to form a pit and a reverse protrusion 3-1. The roughened protrusion I on the surface of the roll 2 is pressed into the other surface of the aluminum foil 3 to form a pit and a reverse protrusion 3-2. The pits and protrusions 3-1 and 3-2 on the two surfaces of the aluminum foil 3 do not overlap and are completely offset along the rolling direction and partially offset along the transverse direction. Figure 11 This is a photograph of the surface of the foil after rolling. Although this embodiment only involves complete misalignment in the rolling direction of the foil, the foil is subjected to an outward lateral force during rolling, resulting in a good surface profile.

[0068] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A surface three-dimensional rolling method of a current collector foil, characterized by, Includes the following steps: Step 100: Place two smooth rolls on a CNC lathe. Based on the roll circumference and rotation speed, control the laser frequency and divide the roll circumference proportionally along the roll circumference. At the same time, control the laser head's movement speed along the roll axial direction and divide the roll surface length according to the interval distance. Finally, process roughened protrusions of predetermined size and distribution position on the roll surface so that the roughened protrusions on the two roll surfaces can be staggered and interlocked. The texturing protrusion is formed by providing one or more independent protrusions inside the edge of the texturing pit, thus creating an integrated structure with a non-smooth surface. Step 200: Assemble the prepared roll pair on the rolling mill, pass the foil through the gap between the two rolls, adjust the relative position of the two rolls, and apply rolling force to form a three-dimensional surface structure composed of staggered pits and peaks on any surface of the foil. The distribution pattern B of the texturing protrusions on the circumferential position of the roll surface is as follows: the interval between adjacent texturing protrusions is divided by the circumference of the roll in which they are located, and the remainder is half of the interval between adjacent texturing protrusions. The axial texturing protrusions on the surfaces of the two rolls are distributed along a spiral line. When the circumferential texturing protrusions on the surfaces of the two rolls are distributed in the same way as distribution mode B, the spiral lines on the surfaces of the two rolls are in opposite directions. The roughened protrusions on the surfaces of the two rolls are staggered circumferentially, or axially, or both circumferentially and axially. The textured protrusions are structured such that one or more independent protrusions are provided on the edge of the textured pit, including single protrusions, double protrusions and triple protrusions. The projected area of ​​the textured pit is greater than the projected area of ​​each individual protrusion.

2. The surface three-dimensional rolling method according to claim 1, characterized in that, The distribution pattern A of the texturing protrusions on the circumferential position of the roll surface is such that the interval between adjacent texturing protrusions is divisible by the circumference of the roll in which they are located.

3. The surface three-dimensional rolling method according to claim 1, characterized in that, The axial spacing between adjacent texturing protrusions on the surface of each roll is 1.25-2.5 times the diameter of the texturing protrusion.

4. The surface three-dimensional rolling method according to claim 1, characterized in that, The diameter of the texturing protrusion is the same as the diameter of the texturing pit, and the height of the texturing protrusion is the highest protrusion height among all the individual protrusions. The interval between adjacent tufted protrusions is the same as the interval between adjacent tufted pits.

5. The surface three-dimensional rolling method according to claim 4, characterized in that, The diameter of the texturing protrusion is 60~120µm, and the height of the texturing protrusion is 1.5~4.0 times the thickness of the foil.

6. The surface three-dimensional rolling method according to claim 1, characterized in that, The thickness of the foil is 3~20µm.

7. The surface three-dimensional rolling method according to claim 1, characterized in that, The surface roughness Ra of the foil with a three-dimensional structure after rolling is 1.5~3.0µm, and the profile value is 1.5~4.0 times that of the base foil; Among them, compared with the base foil, the elastic modulus is reduced by 10~20%, the tensile strength decreases by less than 10%, and the elongation decreases by less than 20%.

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