A method for high-speed thinning of battery electrode sheets with a laser-shaped beam

Abstract

The present invention relates to the technical field of battery electrode sheets, and specifically discloses a method for high-speed thinning of battery electrode sheets by a laser shaping beam, including: dividing the coated layer area on the surface of the battery electrode sheet to obtain a target point set, scanning the surface of the electrode with a laser confocal sensor, calculating the thickness values of the target point set on the target surface of the battery electrode sheet, and determining the thinning area; dividing the thinning area into sub-areas to obtain the length value and width value of each sub-area; traversing and calculating the laser power value required for thinning each sub-area; calculating the distance between the microlens array and the cylindrical microlens array when the laser beam passes through the beam shaping module and the beam focusing module for thinning; traversing the coated layer in each sub-area on the battery electrode sheet for thinning. The laser shaping square spot acts on the surface of the battery electrode sheet material, with stable effect, no damage to the substrate, controllable position and size of the cleaned area, adaptable to battery electrode sheet products of different size specifications, lower cost and higher yield.

Description

Technical Field

[0001] The present invention relates to the technical field of battery electrodes, and specifically relates to a method for high-speed thinning of battery electrodes by a laser shaping beam. Background Art

[0002] With the upgrading and iteration of new energy power battery technology, the improvement of battery life means that the battery requires a higher energy density: an important manufacturing process in current technology is to thin the battery electrode, and its main purpose is to improve the performance and safety of the battery. By thinning the edge of the electrode, the performance of the battery during cyclic charge and discharge can be effectively improved. The specific functions of thinning the electrode are as follows:

[0003] Including: reducing edge effects, increasing the energy density and cycle life of the battery, solving the problem of thick edges of the electrode and enhancing safety;

[0004] The existing methods for thinning battery electrodes all use mechanical thinning or chemical thinning. Among them, mechanical thinning is to form some protrusions and depressions on the surface of the positive and negative electrode materials by means of rollers and pressure in the coating process to form a gradient distribution structure, but the position and size of the thinning area cannot be controlled, resulting in non-uniformity and easy damage to the coating layer, and the mass production yield is low; chemical thinning is to add some specific chemical substances to the positive and negative electrode materials, so that these chemical substances can react and form a locally thinned structure during the coating process; compared with mechanical thinning, chemical thinning can accurately control the position and size of the thinning area; however, specific chemical substances need to be used, the cost is high, and the volatility of the agent may cause harm to the human body, and it takes a long time to act on the material surface, which is not conducive to adapting to the automated production line;

[0005] Therefore, the present invention overcomes the deficiencies of the prior art and provides a non-contact processing method for thinning battery electrodes with high stability, good accuracy, and compatibility with different positions and sizes. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for high-speed thinning of battery electrodes by a laser shaping beam to solve the problems in the above background.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A method for high-speed thinning of battery electrodes by a laser shaping beam includes the following steps:

[0009] Step 1: Divide the coating layer area on the surface of the battery electrode to obtain a target point set, scan the surface of the electrode using a laser confocal sensor, calculate the thickness values of the target point set on the target surface of the battery electrode, and determine the thinning area;

[0010] Step 2: Divide the thinned area into sub-areas, and label the sub-areas as n, where n is 1, 2, 3…, to obtain the length value L of each sub-area n and the width value H n ; Traverse and calculate the laser power value P required for thinning each sub-area n ;

[0011] Step 3: Based on the length value L n and the width value H n of the coating layer in each sub-area of the thinned area, calculate the distance S1 between the microlens array f and the cylindrical microlens array F1 when the laser beam passes through the beam shaping module and the beam focusing module for thinning n ;

[0012] Step 4: Traverse the coating layer in each sub-area on the battery electrode and perform thinning.

[0013] As a further solution of the present invention: The determination process of the thinned area is as follows:

[0014] A1: Establish a coordinate system with the x-axis horizontal and the y-axis vertical at intervals of unit length r for the coating layer area on the surface of the battery electrode to obtain a set of target points, and mark each target point as (x, y);

[0015] A2: Measure and calculate the thickness value D of each target point (x, y) （x，y） ;

[0016] A3: Perform binary labeling on the target points to obtain the thinned area D {（x，y）} .

[0017] As a further solution of the present invention: The calculation method of the thickness value D （x，y） of the target point (x, y) is as follows:

[0018] Obtain the phase shift amount of the target point (x, y) through the phase shifter, denoted as φ （x，y） , and at the same time obtain the sensor incident angle θ and the laser wavelength λ;

[0019] Through Calculate to obtain the thickness value D （x，y） of the target point (x, y).

[0020] As a further solution of the present invention: The process of binary labeling the target points is as follows:

[0021] Compare the thickness value D （x，y） with the thickness threshold Dtar; If the thickness value D （x，y） is greater than the thickness threshold Dtar, mark the target point (x, y) as 1;

[0022] If the thickness value D（x，y） Less than or equal to the thickness threshold Dtar, mark the target point (x, y) as 0.

[0023] As a further solution of the present invention: the laser power value P n is calculated as follows:

[0024] Obtain the thickness values at all target points within each sub-region n, take the maximum and minimum thickness values on the target points within the sub-region, and mark them as Dn max and Dn min ;

[0025] Through calculate to obtain the target thinning thickness value M of the sub-region n ;

[0026] Obtain the laser action time t for laser thinning processing;

[0027] Through calculate to obtain the laser power value P required for the sub-region n during laser thinning n ; where η is the energy absorption efficiency of the coating material.

[0028] As a further solution of the present invention: during the division process of the sub-regions, the area of the sub-region is within Aa × Bb, Aa is the maximum value of the spot length after the incident light beam is collimated, and Bb is the maximum value of the spot width after the incident light beam is collimated.

[0029] As a further solution of the present invention: during the division process of the sub-regions, the thickness deviation value Dn within the sub-region n cz is less than the extreme value Dj of the thickness deviation of the sub-region;

[0030] where the thickness deviation value Dn cz is calculated as follows: .

[0031] As a further solution of the present invention: the beam shaping module includes: a microlens array f, a cylindrical microlens array F1, and a cylindrical microlens array F2;

[0032] The beam focusing module includes a compound focusing lens group F;

[0033] The distance between the microlens array f and the cylindrical microlens array F1 is S1;

[0034] Through calculate to obtain the distance S1 between the microlens array f and the cylindrical microlens array F1 n ;

[0035] where f weit is the focal length of the microlens array, Fone is the focal length of the cylindrical microlens array F1, F zu is the focal length of the compound focusing lens group F, and k is the aperture size of the sub-units of the microlens array.

[0036] As a further solution of the present invention: the distance between the cylindrical microlens array F1 and the cylindrical microlens array F2 is S2, and the distance between the microlens array f and the cylindrical microlens array F2 is S3 and remains unchanged.

[0037] As a further solution of the present invention: in the fourth step, when traversing the coating layer in each sub-region on the battery electrode sheet and performing thinning, the specific process is as follows: based on each sub-region n, adjust the laser power to P n At the same time, adjust the cylindrical microlens array F1 to make the distance between the adjusted cylindrical microlens array F1 and the microlens array f be S1 n Then, perform laser thinning on the coating layer in the sub-region n.

[0038] Advantages of the present invention:

[0039] By identifying the thickness of the coating layer on the battery electrode sheet to obtain the target thinning area, then based on the target thinning thickness value of the target thinning area, calculate the laser power value required for the laser beam when irradiating this area, and the distance between the microlens array and the cylindrical microlens array that needs to be adjusted when irradiating this area. The laser-shaped square light spot (uniform light field energy distribution) acts on the surface of the battery electrode sheet material, with stable effects, no damage to the base material, controllable position and size of the cleaned area, and adaptation to battery electrode sheet products of different size specifications; the laser beam can ensure continuous light output in a fixed mode state, which can meet the requirements of high-speed cleaning of the assembly line, with lower cost, higher yield, and lower later maintenance cost, solving the problems of the conventional mechanical chemical thinning scheme, such as inability to control the position and size of the thinning area, easy generation of thinning non-uniformity, low stability, easy damage to the coating layer, low mass production yield, and difficulty in setting up an automatic line.

[0040] Adopt an optical path system combination, use a pulsed laser to emit a laser beam through a beam shaping module, and finally change the shape of the focused light spot (adjustable rectangular focused light spot) to act on the surface of the electrode sheet material to wash away the excess coating layer material. In this battery electrode sheet cleaning system, the matching of the optical path system shaping lens group and the focusing lens group is used to make the rectangular focused light beam act on the material surface, which can be adapted to the automated production line and has good application in the automated equipment for cleaning and thinning power battery electrode sheets. The overall control integration degree of the system is high, the operation is simple, the overall structure of the equipment is compact, and it is easier to adapt to the automated line body. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below with reference to the accompanying drawings.

[0042] Figure 1 is a schematic flow chart of the method of the present invention;

[0043] Figure 2 is a schematic structural diagram of the thinning system in the present invention;

[0044] Figure 3 is a schematic diagram of the laser shaping module and the beam focusing module in the present invention;

[0045] Figure 4 is a schematic diagram of the adjustment method of the beam shaping module in the present invention;

[0046] Figure 5 is a schematic diagram of the state of the square beam after the focused beam passes through the shaping module in the present invention;

[0047] Figure 6 is a schematic diagram of the light field distribution after the focused beam passes through the shaping module in the present invention Figure 1 ;

[0048] Figure 7 is a schematic diagram of the light field distribution after the focused beam passes through the shaping module in the present invention Figure 2 ;

[0049] Figure 8 is a schematic diagram of the light field distribution after the focused beam passes through the shaping module in the present invention Figure 3 ;

[0050] Figure 9 is a schematic diagram of the defects of the mechanical thinning for comparison in the present invention;

[0051] Figure 10 is the effect diagram of the battery electrode sheet after thinning in the present invention. Specific embodiments

[0052] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0053] Please refer to Figure 1 as shown, the present invention is a method for laser shaping beam to high-speed thin battery electrode sheets, including the following steps:

[0054] Embodiment 1: Step 1: Divide the coating layer area on the surface of the battery electrode sheet to obtain a target point set, scan the surface of the electrode using a laser confocal sensor, calculate the thickness values of the target point set on the target surface of the battery electrode sheet, and determine the thinning area;

[0055] The determination process of the thinning area is as follows:

[0056] A1: Establish a coordinate system with the x-axis horizontal and the y-axis vertical at intervals of unit length r for the coating layer area on the surface of the battery electrode sheet, obtain the target point set, and mark each target point as (x, y);

[0057] A2: Measure and calculate the thickness value D of each target point (x, y) （x，y） ;

[0058] Specifically: Obtain the phase shift amount of the target point (x, y) through a phase shifter, denoted as φ （x，y） , and at the same time obtain the sensor incident angle θ and the laser wavelength λ;

[0059] Through Calculate to obtain the thickness value D of the target point (x, y) （x，y） ;

[0060] A3: Perform binary marking on the target points to obtain the thinning area D {（x，y）} ;

[0061] Compare the thickness value D （x，y） with the thickness threshold Dtar; It should be noted that the thickness threshold Dtar is the process requirement value during the production and processing of the battery electrode sheet, and is set by technicians based on the processing process requirements of the battery electrode sheet;

[0062] If the thickness value D （x，y） is greater than the thickness threshold Dtar, mark the target point (x, y) as 1;

[0063] If the thickness value D （x，y） is less than or equal to the thickness threshold Dtar, mark the target point (x, y) as 0;

[0064] Connect the target points with a value of 1 to obtain the thinning area D {（x，y）} ;

[0065] Step 2: Divide the thinning area into sub-regions, and mark the sub-regions as n, where n is 1, 2, 3..., to obtain the length value L n and the width value H n ; Traverse and calculate the laser power value P required for thinning each sub-region n ;

[0066] Among them, the area of the sub-region is within Aa×Bb, where Aa is the maximum value of the spot length after the incident light beam is collimated, and Bb is the maximum value of the spot width after the incident light beam is collimated;

[0067] In addition, the thickness deviation value Dn within each sub-region n czshould be less than the extreme value Dj of the thickness deviation of the sub-region;

[0068] The thickness deviation value Dn within the sub-region n cz is calculated as follows: Obtain the thickness values at all target points within each sub-region n, and take the maximum and minimum thickness values among the target points within the sub-region, which are respectively marked as Dn max and Dn min ;

[0069] Through calculate to obtain the thickness deviation value Dn within the sub-region n cz ;

[0070] It should be noted that the extreme value of the sub-region thickness deviation is also a preset value. To ensure the accuracy of laser beam thinning of the redundant thickness of the coating on the battery electrode, it is necessary to ensure the consistency of the coating thickness within each sub-region. In this way, during the thinning process, after optimizing the energy of the laser beam, the sub-region can be thinned at one time, while ensuring the accuracy and stability of the thinning;

[0071] Traverse and calculate the laser power value P required for thinning each sub-region n ;

[0072] Specifically: The calculation method of the laser power value P n is as follows:

[0073] Through calculate to obtain the target thinning thickness value M of the sub-region n ;

[0074] Obtain the laser action time t of the laser thinning process; the laser action time t in the laser thinning process is set based on the production line speed during the processing of the battery electrode, and is usually preset by technical personnel;

[0075] Through calculate to obtain the laser power value P required for the sub-region n during the laser thinning process n ; where η is the energy absorption efficiency of the coating material;

[0076] Step 3: Based on the length value L n and width value H n of the coating layer in each sub-region of the thinning area, calculate the distance S1 between the microlens array f and the cylindrical microlens array F1 when the laser beam passes through the beam shaping module and the beam focusing module for thinning n ;

[0077] Among them, as shown in reference Figure 3 the beam shaping module successively includes: a microlens array f, a cylindrical microlens array F1, and a cylindrical microlens array F2;

[0078] The beam focusing module includes a compound focusing lens group F;

[0079] Among them, the distance between the microlens array f and the cylindrical microlens array F1 is S1, the distance between the cylindrical microlens array F1 and the cylindrical microlens array F2 is S2, and the distance between the microlens array f and the cylindrical microlens array F2 is S3 and remains unchanged, that is

[0080] ;

[0081] Specifically: By calculating to obtain the distance S1 between the microlens array f and the cylindrical microlens array F1 n ;

[0082] Among them, f weit is the focal length of the microlens array, F one is the focal length of the cylindrical microlens array F1, F zu is the focal length of the compound focusing lens group F, and k is the aperture size of the sub-units of the microlens array;

[0083] In the step of calculating the distance S1 between the microlens array f and the cylindrical microlens array F1 n taking the adjustment method of a shaped beam with a single-sided 0.5 mm and a long side of 1 - 5 mm as an example, during the adjustment process, the middle cylindrical microlens array F1 moves;

[0084] Exemplarily, as Figure 4 shown, the two adjustment situations of the cylindrical microlens array F1 are respectively:

[0085] (1) When S1 is 42 mm and S2 is 48, the size of the beam focusing spot is 0.5 mm × 5 mm at this time;

[0086] (2) When the distance of S1 is adjusted to 70 mm, S2 is 20 mm, and at this time the beam focusing spot is 0.5 mm × 1 mm, and the working distance and the single-sided energy distribution will not change;

[0087] Therefore, when traversing the sub-regions on the coated layer of the battery electrode sheet, it is only necessary to variably adjust the distance S1 between the cylindrical microlens array F1 and the microlens array f;

[0088] Step Four: Traverse the coated layer in each sub-region on the battery electrode sheet and perform thinning. During the thinning process, based on each sub-region n, adjust the laser power to P n , and adjust the cylindrical microlens array F1 to make the distance between the adjusted cylindrical microlens array F1 and the microlens array f be S1 n , and then perform laser thinning on the coated layer of sub-region n.

[0089] By identifying the thickness of the coating layer on the battery electrode, the target thinning area is obtained. Then, based on the target thinning thickness value of the target thinning area, the laser power value required for the laser beam to irradiate this area and the distance between the microlens array and the cylindrical microlens array that needs to be adjusted when irradiating this area are calculated. The battery electrode material surface is acted upon by the laser-shaped square light spot (with uniform light field energy distribution), with stable effects, no damage to the base material, controllable position and size of the cleaned area, and adaptation to battery electrode products of different size specifications; the laser beam can ensure continuous light output in a fixed mode state, meeting the requirements of high-speed cleaning on the production line, with lower costs, higher yield, and lower later maintenance costs.

[0090] It solves the problems of the conventional mechanical chemical thinning solution, which cannot control the position and size of the thinning area, is prone to thinning non-uniformity, has low stability, is likely to cause damage to the coating layer, has a low production yield, and is not easy to set up an automatic line.

[0091] Specifically, for the defect problems of conventional mechanical thinning, such as delamination, trailing, and serration, as Figure 9 shown, the effect after thinning using this laser thinning method is as Figure 10 shown, with uniform thinning effect. Regarding the process parameters during the laser thinning process, an example is as follows in the table:

[0092] Speed (mm / s) Power (W) Pulse width (ns) Frequency (KHZ) Spot spacing (um) Focus position (mm) Maximum single pulse energy (mj) Actual single pulse energy (mj) 1000 380 100 10 100 0 100 38

[0093] Example 2: Regarding the structural design of the beam shaping module and the beam focusing module, refer to Figure 3 shown; during application, the beam shaping module is located above the beam focusing module, and together with the laser, the optical path system, the beam shaping module, the beam focusing module, and the transfer platform, it constitutes the structure diagram of the thinning system, refer to Figure 2 shown;

[0094] Based on this, this solution provides a battery electrode cleaning system, including: a laser, an optical path system, a beam shaping module, and a beam focusing module;

[0095] The laser emits laser light, which passes through the optical path system (conducted by optical fiber to QBH for amplified output), and then passes through the collimating and focusing head, that is, the beam shaping module, which includes: a microlens array and a cylindrical lens array group (adjustable), and finally passes through the collimating and focusing head, that is, the focusing module, which includes: a composite focusing lens group F, and finally acts on the battery electrode on the electrode conveying device (which can adapt to a line speed of 1000 mm / s);

[0096] Specifically, after inputting the Gaussian beam and passing through the beam shaping module and the beam focusing module, the output adjustable square focusing light spot is as Figure 5 、 Figure 6 、Figure 7 and Figure 8 as shown, wherein Figure 6 and Figure 7 refer to the spot width formed after the light beam passes through the beam shaping module and the beam focusing module, Figure 8 refers to the temperature of the spot formed after the light beam passes through the beam shaping module and the beam focusing module;

[0097] An optical path system combination is adopted. A pulsed laser is used to emit a laser beam through the beam shaping module, and finally the shape of the focused spot (adjustable rectangular focused spot) is changed to act on the surface of the pole piece material to wash away the excess coating material. In this battery pole piece cleaning system, the combination of the optical path system shaping mirror group and the focusing mirror group is used to make the rectangular focused beam act on the material surface, which can meet the high-speed requirements of the automated production line. It has good application in the automated equipment for cleaning and thinning the power battery pole piece. The overall control integration of the system is high, the operation is simple, the overall structure of the equipment is compact, and it is easier to adapt to the automated line body.

[0098] The above has described in detail an embodiment of the present invention, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. A method for high-speed thinning of battery pole pieces using laser beam shaping, characterized in that: The following steps are involved: Step 1: Divide the coating layer area on the surface of the battery electrode to obtain a target point set, use a laser confocal sensor to scan the electrode surface, calculate the thickness value of the target point set on the target surface of the battery electrode, and determine the thinning area; Step 2: Divide the thinned area into sub-areas and mark the sub-areas as n, where n is 1, 2, 3, etc., and obtain the length value L of each sub-area n and width value H n ; Calculate the laser power value P required for thinning each sub-area n ; Step 3: Based on the length value L of the coating layer in each sub-area in the thinning area n and width value H n , calculate and obtain the distance S1 between the microlens array f and the cylindrical microlens array F1 when the laser beam passes through the beam shaping module and the beam focusing module for thinning n ; The beam shaping module includes: a microlens array f, a cylindrical microlens array F1 and a cylindrical microlens array F2; The beam focusing module includes a composite focusing lens group F; The distance between the microlens array f and the cylindrical microlens array F1 is S1 n ; pass Calculate the distance S1 between the microlens array f and the cylindrical microlens array F1 n ; Among them, f weit is the focal length of the microlens array, F one is the focal length of the cylindrical microlens array F1, F zu is the focal length of the compound focusing lens group F, k is the sub-unit aperture size of the microlens array; Step 4: Traverse the coating layer in each sub-area on the battery electrode and thin it.

2. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 1, characterized in that: The process of determining the thinning area is as follows: A1: For the coating layer area on the surface of the battery electrode, a coordinate system is established with a unit length r as the interval, the horizontal axis is the x-axis, and the vertical axis is the y-axis to obtain a target point set, and each target point is recorded as (x, y); A2: Measure and calculate the thickness value D of each target point (x, y) （x，y） ; A3: Binarize the target points to obtain the thinning area D {（x，y）} .

3. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 2, characterized in that: The thickness value D of the target point (x, y) （x，y） The calculation method is: The phase shift of the target point (x, y) is obtained by the phase shifter, which is denoted as φ （x，y） , and simultaneously obtain the sensor incident angle θ and laser wavelength λ; pass Calculate the thickness value D of the target point (x, y) （x，y） .

4. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 2, characterized in that: The process of binary marking of the target point is as follows: Set the thickness value D （x，y） Compare with the thickness threshold Dtar; if the thickness value D （x，y） If it is greater than the thickness threshold Dtar, the target point (x, y) is recorded as 1; If the thickness value D （x，y） If the thickness is less than or equal to the thickness threshold Dtar, the target point (x, y) is recorded as 0.

5. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 4, characterized in that: The laser power value P n The calculation method is: Get the thickness values ​​at all target points in each sub-region n, take the maximum and minimum thickness values ​​at the target points in the sub-region, and mark them as Dn respectively. max and Dn min ; pass Calculate the target thinning thickness value M of the sub-area n ; Obtain the laser action time t of laser thinning processing; pass Calculate the laser power value P required for sub-area n during laser thinning n ; Wherein, η is the energy absorption efficiency of the coating material.

6. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 5, characterized in that: During the division of the sub-regions, the area of ​​the sub-regions is within Aa×Bb, where Aa is the maximum spot length of the incident light beam after collimation, and Bb is the maximum spot width of the incident light beam after collimation.

7. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 6, characterized in that: In the process of dividing the sub-regions, the thickness deviation value Dn in the sub-region n cz Less than the sub-region thickness deviation extreme value Dj; Among them, the thickness deviation value Dn cz The calculation method is: .

8. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 1, characterized in that: The distance between the cylindrical microlens array F1 and the cylindrical microlens array F2 is S2, and the distance between the microlens array F1 and the cylindrical microlens array F2 is S3 and remains unchanged.

9. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 1, characterized in that: In step 4, the specific process of traversing the coating layer in each sub-region on the battery electrode and thinning it is as follows: based on each sub-region n, adjust the laser power to P n , and adjust the cylindrical microlens array F1 at the same time, so that the distance between the cylindrical microlens array F1 and the microlens array f is S1 n , and then the coating layer on the sub-region n is laser thinned.

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