Method for thinning battery pole piece at high speed by laser shaping beam

Abstract

The invention relates to the technical field of battery pole pieces, and particularly discloses a method for thinning a battery pole piece at a high speed by using a laser shaping beam, which comprises the following steps of: dividing a coating layer area on the surface of the battery pole piece to obtain a target point set, scanning the surface of an electrode by using a laser confocal sensor, and calculating the thickness value of the target point set on the target surface of the battery pole piece, a thinning area is determined; performing sub-region division on the thinned region to obtain a length value and a width value of each sub-region; traversing and calculating a laser power value required for thinning each sub-region; calculating to obtain the distance between the micro lens array and the cylindrical micro lens array when the laser beam passes through the beam shaping module and the beam focusing module to be thinned; the coating layer in each sub-area on the battery pole piece is traversed and thinned, square light spots act on the surface of a battery pole piece material through laser shaping, the effect is stable, a base material cannot be damaged, the position size of the cleaned area is controllable, the method is suitable for battery pole piece products of different sizes and specifications, the cost is lower, and the yield is higher.

Description

Technical Field

[0001] The invention relates to the technical field of battery pole pieces, and in particular to a method for high-speed thinning of battery pole pieces using a laser beam shaping method. Background Art

[0002] With the upgrade and iteration of new energy power battery technology, the improvement of battery life means that the battery needs a higher energy density: an important manufacturing process of current technology is to thin the battery pole piece, the main purpose of which is to improve the performance and safety of the battery. By thinning the edge of the pole piece, the performance of the battery during the cycle charge and discharge process can be effectively improved. The specific thinning of the pole piece has the following functions: Including: reducing edge effects, improving battery energy density and cycle life, solving the problem of thick edges of pole pieces and improving safety; Existing thinning methods for battery pole pieces 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 through rollers and pressure during the coating process to form a gradient distribution structure, but the position and size of the thinning area cannot be controlled, which is easy to produce unevenness and 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 generate 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; but it requires the use of specific chemical substances, which is more expensive, and the volatility of the agent may cause harm to the human body, and it takes a long time to act on the surface of the material, which is not conducive to adapting to the automated production line; Therefore, the present invention overcomes the deficiencies of the prior art and provides a contactless processing method with high stability, good precision, and compatibility with a battery pole sheet thinning method of different positions and sizes. Summary of the invention

[0003] The object of the present invention is to provide a method for high-speed thinning of battery pole pieces using a laser beam shaping method to solve the above-mentioned background problems.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for high-speed thinning of battery pole pieces by laser beam shaping comprises the following steps: 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 ; Step 4: Traverse the coating layer in each sub-area on the battery electrode and thin it.

[0005] As a further solution of the present invention: the process of determining the thinning area is: 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）} .

[0006] As a further solution of the present invention: 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） .

[0007] As a further solution of the present invention: the process of binary marking the target point is: 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.

[0008] As a further solution of the present invention: 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.

[0009] As a further solution of the present invention: in the process of dividing the sub-regions, the area of ​​the sub-regions is within Aa×Bb, 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.

[0010] As a further solution of the present invention: in the process of dividing the sub-regions, the thickness deviation value Dn in the sub-region n is cz Less than the sub-region thickness deviation extreme value Dj; Among them, the thickness deviation value Dn cz The calculation method is: .

[0011] As a further solution of the present invention: the beam shaping module comprises: 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; 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, and k is the sub-unit aperture size of the microlens array.

[0012] 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.

[0013] As a further solution of the present invention: In the 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, the laser power is adjusted 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 S1n , and then the coating layer on the sub-region n is laser thinned.

[0014] Beneficial effects of the present invention: By identifying the thickness of the coating layer on the battery pole piece, the target thinning area is obtained, and then based on the target thinning thickness value of the target thinning area, the laser power value required for the laser beam to irradiate the area and the distance between the microlens array and the cylindrical microlens array that needs to be adjusted when irradiating the area are calculated. The surface of the battery pole piece material is acted on by a laser-shaped square spot (even light field energy distribution) with stable effect, without damaging the substrate, and the position and size of the cleaned area are controllable to adapt to battery pole piece products of different sizes and specifications; the laser beam can ensure continuous light emission in a fixed mode state, which can meet the requirements of high-speed cleaning of the assembly line, and has lower cost, higher yield, and low later maintenance cost. It solves the problems of conventional mechanical and chemical thinning solutions, which cannot control the position and size of the thinning area, are prone to uneven thinning, have low stability, are prone to damage to the coating layer, have low mass production yield, and are difficult to set up automatic lines.

[0015] By adopting the optical path system combination, a pulsed laser is used to emit a laser beam through the beam shaping module, and finally the shape of the focused light spot is changed (adjustable rectangular focused light spot) to act on the surface of the pole piece material to clean away the excess coating material. In the battery pole piece cleaning system, the combination 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 a good application in the application of automated equipment for cleaning and thinning power battery pole pieces. The overall system control has high integration, simple operation, compact overall equipment structure, and is easier to adapt to the automated line. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings.

[0017] Figure 1 It is a schematic flow chart of the method of the present invention; Figure 2 It is a schematic diagram of the structure of the skiving system in the present invention; Figure 3 It is a schematic diagram of the laser shaping module and the beam focusing module in the present invention; Figure 4 It is a schematic diagram of the adjustment method of the beam shaping module in the present invention; Figure 5 It is a schematic diagram of a square beam state after the focused beam passes through the shaping module in the present invention; Figure 6 This is a schematic diagram of the light field distribution after the focused light beam passes through the shaping module in the present invention. Figure 1 ; Figure 7This is a schematic diagram of the light field distribution after the focused light beam passes through the shaping module in the present invention. Figure 2 ; Figure 8 This is a schematic diagram of the light field distribution after the focused light beam passes through the shaping module in the present invention. Figure 3 ; Fig. 9 It is a schematic diagram of the defects of mechanical thinning compared in the present invention; Fig.10 This is a diagram showing the effect of thinning the battery pole piece in the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] See also Figure 1 As shown, the present invention is a method for high-speed thinning of battery pole pieces using laser beam shaping, comprising the following steps: Embodiment 1: Step 1: Divide the coating layer area on the surface of the battery pole piece 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 pole piece, and determine the thinning area; 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） ; Specifically: The phase shift of the target point (x, y) is obtained through the phase shifter, 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） ; A3: Binarize the target points to obtain the thinning area D {（x，y）} ; Set the thickness value D （x，y） Compare with the thickness threshold Dtar; it should be noted that the thickness threshold Dtar is the process requirement value of the battery pole piece during the production process, which is set by the technicians based on the processing requirements of the battery pole piece; 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; Connect the target points with a value of 1 to obtain the thinning area D {（x，y）} ; 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 ; Among them, the area of ​​the sub-region is within Aa×Bb, 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; In addition, the thickness deviation value Dn in each sub-area n cz It should be smaller than the sub-region thickness deviation extreme value Dj; Thickness deviation value Dn in sub-area n cz The calculation method is as follows: obtain 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 max and Dn min ; pass Calculate the thickness deviation value Dn in sub-area n cz ; It should be noted that the sub-region thickness deviation extreme value is also a preset value. In order to ensure the accuracy of the laser beam thinning the excess thickness of the coating layer on the battery pole piece, it is necessary to ensure the consistency of the coating thickness in each sub-region. In this way, during the thinning process, after the laser beam optimizes the energy, it can thin the sub-region at one time, while ensuring the accuracy and stability of the thinning. Traverse and calculate the laser power value P required for thinning each sub-area n ; Specific: Laser power value P n The calculation method is: pass Calculate the target thinning thickness value M of the sub-area n ; 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 pole piece, and is usually pre-set by the technician; 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; 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 ; Among them, reference Figure 3 As shown, the beam shaping module includes in sequence: 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; 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, ; Specific: Through 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; Calculate the distance S1 between the microlens array f and the cylindrical microlens array F1 n In the steps, the adjustment method of the shaped light beam with a single side of 0.5 mm and a long side of 1-5 mm is taken as an example. During the adjustment process, the cylindrical microlens array F1 in the middle is moved; For example, Figure 4 As shown, the two adjustment conditions of the cylindrical microlens array F1 are: (1) When S1 is 42 mm, S2 is 48 mm, and the beam focus spot size is 0.5 mm × 5 mm; (2) When the distance of S1 is adjusted to 70mm, S2 is 20mm, and the beam focus spot is 0.5mm×1mm, and the working distance and unilateral energy distribution will not change; Therefore, when traversing the sub-region on the thinned battery electrode coating layer, the distance S1 between the cylindrical micro-lens array F1 and the micro-lens array f can be variably adjusted; Step 4: Traverse the coating layer in each sub-region on the battery electrode and thin it. During the thinning process, adjust the laser power to P based on each sub-region n.n , and adjust the cylindrical microlens array F1 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.

[0020] The target thinning area is obtained by identifying the thickness of the coating layer on the battery pole piece, and then based on the target thinning thickness value of the target thinning area, the laser power value required for the laser beam to irradiate the area and the distance between the microlens array and the cylindrical microlens array that needs to be adjusted when irradiating the area are calculated. The surface of the battery pole piece material is acted on by a laser-shaped square spot (even light field energy distribution) with stable effect, without damaging the substrate, and the position and size of the cleaning area are controllable to adapt to battery pole piece products of different sizes and specifications; the laser beam can ensure continuous light emission in a fixed mode state, which can meet the requirements of high-speed cleaning of the assembly line, and has lower cost, higher yield and low later maintenance cost.

[0021] It solves the problems of conventional mechanical and chemical thinning solutions, such as the inability to control the position and size of the thinning area, easy to produce uneven thinning, low stability, easy to cause damage to the coating layer, low mass production yield, and difficulty in setting up automatic lines.

[0022] Specifically, the defects of conventional mechanical thinning, such as delamination, tailing and sawtooth, are Fig. 9 As shown, the effect of laser thinning is as follows: Fig.10 As shown, the thinning effect is uniform. The process parameters in the laser thinning process are shown in the following table: 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

[0023] Embodiment 2: Regarding the structural design of the beam shaping module and the beam focusing module, refer to Figure 3 As shown; in the application process, the beam shaping module is located above the beam focusing module, and together with the laser, optical path system, beam shaping module, beam focusing module, and transmission platform, constitutes the thinning system structure diagram, refer to Figure 2 As shown; Based on this, this solution provides a battery pole cleaning system, including: a laser, an optical path system, a beam shaping module and a beam focusing module; The laser emits laser light through the optical path system (transmitted from the optical fiber to the QBH amplified output), then through the collimating focusing head, i.e. the beam shaping module, including: microlens array and cylindrical lens array lens group (adjustable), and finally through the collimating focusing head, i.e. the focusing module, including: the composite focusing lens group F, and finally acts on the battery pole piece on the pole piece conveying device (adaptable to 1000mm / s line speed); Specifically, after the Gaussian beam is input, it passes through the beam shaping module and the beam focusing module, and the output adjustable square focusing spot is as follows: Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, Figure 6 and Figure 7 It refers to the spot width formed after the light beam passes through the beam shaping module and the beam focusing module. Figure 8 It refers to the temperature of the light spot formed after the light beam passes through the beam shaping module and the beam focusing module; By adopting the optical path system combination, a pulsed laser is used to emit a laser beam through the beam shaping module, and finally the shape of the focused light spot is changed (adjustable rectangular focused light spot) to act on the surface of the pole piece material to clean away the excess coating material. In the battery pole piece cleaning system, the combination 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 adapt to the high-speed requirements of the automated production line and has a good application in the application of automated equipment for cleaning and thinning power battery pole pieces. The overall system control has high integration, simple operation, compact overall equipment structure, and is easier to adapt to the automated line.

[0024] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage 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 ; 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 1, 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 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; 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, Fzu is the focal length of the composite focusing lens group F, and k is the sub-unit aperture size of the microlens array.

9. The method for high-speed thinning of battery pole pieces by laser beam shaping according to claim 8, 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.

10. 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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