Method for solving wrinkling of pole piece in coating process by approaching zero tension control

Abstract

The invention relates to the technical field of lithium battery production, in particular to a method for solving wrinkling of a pole piece in the coating process by approaching zero tension control, which comprises the following steps: S1, unwinding the pole piece, and coating one surface of the pole piece; s2, winding the coated pole piece on a heating roller, carrying out a baking process, monitoring the tension F1 of the pole piece between the coating process and the heating roller in real time by adopting a first tension sensor, and controlling the linear speed M1 of the heating roller through a control system and a first servo motor; and S3, the baked pole piece is pulled through a pulling roller, the tension F2 between the heating roller and the pulling roller is monitored in real time through a second tension sensor, and the linear speed M2 of the pulling roller is controlled through a control system and a second servo motor. The lithium battery pole piece baking device has the effects of improving the pole piece baking quality and the production efficiency and improving the performance of the lithium battery.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery production, and in particular to a method for solving the wrinkling of pole pieces in a coating process by using near-zero tension control. Background Art

[0002] Pole baking is a key process in the production of lithium-ion batteries. It is mainly used to remove moisture and solvents from the pole pieces to ensure battery performance and safety. In the pole piece baking process, compared with the traditional oven, the roller pole piece baking process continuously conveys the pole pieces through the roller system, which has higher baking efficiency, shorter process, better continuity and uniformity, and is suitable for large-scale production.

[0003] In the existing roller-type electrode baking process, when the electrode passes through the heating roller, it is easy to stretch in the width direction due to heat (thermal expansion), and wrinkles will appear due to the inability to fully unfold, which will lead to a series of problems such as uneven coating thickness on the surface of the electrode and poor baking quality, which ultimately affect the performance of the lithium battery and need to be solved urgently. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present application provides a method for solving the wrinkling of the electrode during the coating process by using near-zero tension control.

[0005] The above invention objectives of the present application are achieved through the following technical solutions:

[0006] A method for solving the wrinkling of the electrode during the coating process by close to zero tension control comprises the following steps:

[0007] S1, unwinding the electrode sheet and performing a coating process on one surface of the electrode sheet;

[0008] S2, the coated electrode is wound around the heating roller for baking, and the first tension sensor is used to monitor the tension F between the electrode and the heating roller in real time. 1 The heating roller is controlled by the control system and the first servo motor to have a linear speed M 1 The control of the tension F 1 <F a +T increases M 1 , under tension F 1 >F a +T, reduce M 1 , where F a F is the preset tension between the electrode and the heating roller during the coating process. x is the limit tension of the electrode sheet that produces wrinkles between the coating process and the heating roller, T is the allowable fluctuation range, F a <<F x ;

[0009] S3, the baked electrode is pulled by the pulling roller, and the tension F between the heating roller and the pulling roller is monitored in real time by the second tension sensor 2 The control system and the second servo motor control the linear speed M of the traction roller. 2 The control of the tension F 2 <F b +T increases M 2 , under tension F 2 >F b +T, reduce M 2 , where F b F is the preset tension of the pole piece between the heating roller and the pulling roller, y is the limit tension of the electrode sheet when it is wrinkled between the heating roller and the pulling roller, T is the allowable fluctuation range, F b <<F y .

[0010] By adopting the above technical scheme, under the closed-loop control between the first tension sensor, the control system and the first servo motor, and between the second tension sensor, the control system and the second servo motor, by dynamically adjusting the linear speeds of the heating roller and the traction roller, the pole piece can respectively achieve precise adjustment of the tension between the coating process and the heating roller (baking process), and between the heating roller (baking process) and the traction roller, to ensure that the pole piece is always in the optimal tension range during the baking process, so that the pole piece can expand and contract freely between the cold state and the hot state, avoiding stress concentration and wrinkling caused by thermal expansion and contraction, and can improve the uniformity of the pole piece coating, improve the pole piece baking quality and production efficiency, and improve the performance of the lithium battery.

[0011] In a preferred example, the present application can be further configured as follows: the coating process is performed by roller coating with a coating roller.

[0012] By adopting the above technical solution and using a coating roller to carry out the coating process, the uniformity and consistency of the electrode coating can be improved. Combined with the tension sensor, control system and servo motor's tension control function, the production quality and production efficiency of the electrode can be significantly improved.

[0013] In a preferred example, the present application can be further configured as follows: tension-breaking rollers are rotatably arranged at both the coating roller and the traction roller, and when the pole piece is wound around the coating roller or the traction roller, the corresponding tension-breaking roller is used to press the pole piece against the coating roller or the traction roller.

[0014] By adopting the above technical solution, the two tension blocking rollers can respectively block the tensions at two locations before the coating process and after the baking process, so as to isolate the tension fluctuations between different processes, ensure that the tension of the electrode in each process is independently controllable, and maintain stable tension.

[0015] In a preferred example, the present application can be further configured as follows: x and F y The values ​​of are obtained through repeated actual measurements, the specific method is as follows:

[0016] (1) The electrode is baked to continuously improve M 1 When the pole piece is wrinkled, the tension F is recorded by the first tension sensor. max1 , continue to improve M 2 When the pole piece is wrinkled, the tension F is recorded by the second tension sensor. max2 ;

[0017] (2) Maintaining the same environment, equipment and other conditions, replacing the electrode with the same material and thickness, completing the same coating process, and performing the same baking process (heating temperature is consistent), continuously improve M 1 When the pole piece is wrinkled, the tension F is recorded by the first tension sensor. max1 , continue to improve M 2 When the pole piece is wrinkled, the tension F is recorded by the second tension sensor. max2 ;

[0018] (3) Repeat step (2) several times to obtain a certain tension F max1 and some tension F max2 , calculate several tensions F max1 The average value and some tension F max2 The average value of x and F y .

[0019] By adopting the above technical solution, we can preliminarily obtain the ultimate tension of wrinkling produced by electrodes of the same material and thickness between the coating process and the heating roller (baking process), and between the heating roller (baking process) and the pulling roller under the same environment, equipment and other conditions, which is adapted to production needs.

[0020] In a preferred example, the present application can be further configured as follows: the value of T is 0.01N.

[0021] In a preferred example, the present application can be further configured as follows: a The value range is 0.01F x -0.99F x , F b The value range is 0.01F y -0.99F y .

[0022] In summary, the present application includes at least one of the following beneficial technical effects:

[0023] 1. Under the closed-loop control between the first tension sensor, the control system and the first servo motor, and between the second tension sensor, the control system and the second servo motor, by dynamically adjusting the linear speeds of the heating roller and the traction roller, the pole piece can respectively realize precise adjustment of the tension between the coating process and the heating roller (baking process), and between the heating roller (baking process) and the traction roller, to ensure that the pole piece is always in the optimal tension range during the baking process, so that the pole piece can expand and contract freely between the cold state and the hot state, avoiding stress concentration and wrinkling caused by thermal expansion and contraction, and can improve the uniformity of the pole piece coating, improve the pole piece baking quality and production efficiency, and improve the performance of the lithium battery.

[0024] 2. The two tension blocking rollers can respectively block the tensions before the coating process and after the baking process to isolate the tension fluctuations between different processes, ensuring that the tension of the electrode in each process is independently controllable and maintains stable tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic cross-sectional view of part of the equipment used in the method of solving the wrinkling of the electrode during the coating process by approaching zero tension control in this application;

[0026] Figure 2 This is a control flow chart of a method for solving electrode wrinkling during a coating process by using near-zero tension control in this application.

[0027] Reference numerals: 1. pole piece; 2. heating roller; 3. first tension sensor; 4. traction roller; 5. second tension sensor; 6. coating roller; 7. tension blocking roller. DETAILED DESCRIPTION

[0028] The following is a description of exemplary embodiments of the present application in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0029] It should be noted that the terms "first", "second", etc. in the present invention are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure.

[0030] In addition, the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article, unless otherwise specified, generally means that the associated objects before and after are in an "or" relationship.

[0031] The following describes a method of the present application for solving electrode wrinkling during the coating process by using near-zero tension control with reference to the accompanying drawings.

[0032] like Figure 1 As shown, a method for solving the wrinkling of the electrode during the coating process by close to zero tension control includes the following steps:

[0033] S1, unwinding the pole piece 1, and performing a coating process on one surface of the pole piece 1;

[0034] S2, the coated electrode 1 is wound around the heating roller 2 for a baking process, and the first tension sensor 3 is used to monitor the tension F between the electrode 1 and the heating roller 2 in real time. 1 The heating roller 2 is controlled by the control system and the first servo motor to have a linear speed M 1 The control of the tension F 1 <F a +T increases M 1 , under tension F 1 >F a +T, reduce M 1 , where F a is the preset tension between the electrode 1 and the heating roller 2 during the coating process, F x is the limit tension of the electrode 1 that causes wrinkles between the coating process and the heating roller 2, T is the allowable fluctuation range, and F a <<F x ;

[0035] S3, the baked electrode 1 is pulled by the pulling roller 4, and the tension F between the heating roller 2 and the pulling roller 4 is monitored in real time by the second tension sensor 5 2 The control system and the second servo motor control the linear speed M of the traction roller 4. 2 The control of the tension F 2 <F b +T increases M 2 , under tension F 2 >F b +T, reduce M 2 , where F b is the preset tension of the pole piece 1 between the heating roller 2 and the pulling roller 4, F yis the limit tension of the electrode 1 when it is wrinkled between the heating roller 2 and the pulling roller 4, T is the allowable fluctuation range, F b <<F y .

[0036] During operation, under the closed-loop control between the first tension sensor 3, the control system and the first servo motor, and between the second tension sensor 5, the control system and the second servo motor, by dynamically adjusting the linear speeds of the heating roller 2 and the pulling roller 4, the pole piece 1 can achieve precise adjustment of the tension between the coating process and the heating roller 2 (baking process), and between the heating roller 2 (baking process) and the pulling roller 4, respectively, to ensure that the pole piece 1 is always in the optimal tension range during the baking process, so that the pole piece 1 can expand and contract freely between the cold state and the hot state, avoiding stress concentration and wrinkling caused by thermal expansion and contraction, and can improve the uniformity of the coating of the pole piece 1, improve the baking quality and production efficiency of the pole piece 1, and improve the performance of the lithium battery.

[0037] It should be noted that the first tension sensor 3 and the second tension sensor 5 can both adopt conventional models on the market, such as BFZL-CZ, BFZL-ZT, etc.

[0038] The control system can use a PID controller to dynamically adjust according to the real-time situation of the tension sensor. Specifically, in S2, the tension F 1 With linear speed M 1 The feedback process is as follows: dynamically adjust the heating roller linear speed parameter array according to the real-time data of the first tension sensor:

[0039] The first tension sensor collects data: F 1 ={F 11 ,F 12 ,F 13 ,......,F 1n}

[0040] Heating roller linear speed adjustment formula: M 1 = k·{F 1max -F 1i}, where k is the empirical coefficient, and closed-loop control is achieved through the PID algorithm.

[0041] Specifically, the coating process is carried out by roller coating with a coating roller 6. By using the coating roller 6 to carry out the coating process, the uniformity and consistency of the coating of the electrode 1 can be improved. Combined with the tension sensor, control system and servo motor's tension control function, the production quality and production efficiency of the electrode 1 can be significantly improved.

[0042] It should be noted that, in actual operation, the three servo rollers, namely the coating roller 6, the heating roller 2 and the pulling roller 4, should be started at the same linear speed to reduce tension fluctuations between processes.

[0043] Furthermore, in S2 and S3, tension blocking rollers 7 are rotatably arranged at the coating roller 6 and the traction roller 4. When the pole piece 1 is wound around the coating roller 6 or the traction roller 4, the corresponding tension blocking roller 7 is used to press the pole piece 1 against the coating roller 6 or the traction roller 4. The two tension blocking rollers 7 can respectively block the tensions at two locations before the coating process and after the baking process is completed, so as to isolate the tension fluctuations between different processes, thereby ensuring that the tension of the pole piece 1 in each process is independently controllable and the tension is kept stable.

[0044] In addition, F x and F y The values ​​of are obtained through repeated actual measurements, the specific method is as follows:

[0045] (1) Pole 1 undergoes a baking process to continuously improve M 1 When the pole piece 1 is wrinkled, the tension F is recorded by the first tension sensor 3. max1 , continue to improve M 2 When the pole piece 1 is wrinkled, the tension F is recorded by the second tension sensor 5. max2 ;

[0046] (2) Maintaining the same environment, equipment and other conditions, replace the electrode 1 with the same material and thickness, complete the same coating process, and then perform the same baking process (heating temperature is consistent) to continuously improve M 1 When the pole piece 1 is wrinkled, the tension F is recorded by the first tension sensor 3. max1 , continue to improve M 2 When the pole piece 1 is wrinkled, the tension F is recorded by the second tension sensor 5. max2 ;

[0047] (3) Repeat step (2) several times to obtain a certain tension F max1 and some tension F max2 , calculate several tensions F max1 The average value and some tension F max2 The average value of x and F y It is preliminarily concluded that under the same environment, equipment and other conditions, the electrode 1 of the same material and thickness produces the ultimate tension of wrinkling between the coating process and the heating roller 2 (baking process), and between the heating roller 2 (baking process) and the pulling roller 4, which is suitable for production needs.

[0048] It should be noted that the ultimate tension of the electrode 1 when wrinkled is a complex parameter, which is affected by many factors, such as the material, thickness, coating surface density, compaction density, rolling process and equipment status of the electrode 1. In this embodiment, the initial ultimate tension is calculated by repeated actual measurement, so that the preset tension value is less than the initial ultimate tension, and then the actual tension F of the electrode 1 is ensured. 1 and tension F 2 Fluctuation within the preset tension value range, avoiding wrinkles and making the tension F 1 and tension F 2 As close as possible to the ultimate tension F x and F y , to ensure the flatness and conveying speed of the pole piece 1, which is suitable for the working conditions of this scheme.

[0049] It should also be noted that F x and F y The value of can also be obtained by constructing a tension parameter matrix through orthogonal test method. For example, a multi-factor test array (such as tension and speed) is designed. Here, factors such as baking temperature, pole piece material, thickness, etc. need to be kept the same. The optimal combination is selected through range analysis. The following Table 1 is an example test table:

[0050]

[0051] The data show that the wrinkle rate decreases significantly when the tension is reduced to 160N / m.

[0052] Table 1

[0053] In addition, in S2 and S3, the value of T is 0.01N, and F a The value range is 0.01F x -0.99F x , F b The value range is 0.01F y -0.99F y .

[0054]

[0055]

[0056] Table 2

[0057] In one embodiment, Table 2 is an experimental data table obtained by using a plurality of groups of electrode plates with different thicknesses and widths, under the same equipment environment and the same heating temperature conditions, using conventional tension method and the method of the present invention for drying. It can be concluded from Table 1 that compared with the traditional method, the method of the present invention basically does not cause wrinkles.

[0058] The above specific implementations do not constitute a limitation on the protection scope of this application. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A method for solving the wrinkling of the electrode during the coating process by close to zero tension control, characterized in that: The following steps are involved: S1, unwinding the electrode sheet and performing a coating process on one surface of the electrode sheet; S2, the coated electrode is wound around the heating roller for baking, the first tension sensor is used to monitor the tension F1 between the electrode and the heating roller in real time, and the control system and the first servo motor are used to control the linear speed M1 of the heating roller. a +T, increase M1, when tension F1>F a When +T, reduce M1, where F a F is the preset tension between the electrode and the heating roller during the coating process. x is the limit tension of the electrode sheet that produces wrinkles between the coating process and the heating roller, T is the allowable fluctuation range, F a <<F x ; S3, the baked electrode is pulled by the pulling roller, and the tension F2 between the heating roller and the pulling roller is monitored in real time by the second tension sensor, and the linear speed M2 of the pulling roller is controlled by the control system and the second servo motor. b +T, increase M2, when tension F2>F b +T, reduce M2, where F b F is the preset tension of the pole piece between the heating roller and the pulling roller, y is the limit tension of the electrode sheet when it is wrinkled between the heating roller and the pulling roller, T is the allowable fluctuation range, F b <<F y .

2. The method for solving electrode wrinkling in coating process by near-zero tension control as claimed in claim 1, characterized in that: The coating process is carried out by coating with a coating roller.

3. The method for solving electrode wrinkling in coating process by near-zero tension control as claimed in claim 2, characterized in that: Tension blocking rollers are rotatably arranged at both the coating roller and the traction roller. When the pole piece is wound around the coating roller or the traction roller, the corresponding tension blocking roller is used to press the pole piece against the coating roller or the traction roller.

4. The method for solving electrode wrinkling in coating process by near-zero tension control as claimed in claim 1, characterized in that: F x and F y The values ​​of are obtained through repeated actual measurements, the specific method is as follows: (1) The electrode is baked and M1 is continuously increased until wrinkles appear on the electrode. The tension F is recorded by the first tension sensor. max1 , continue to increase M2 until the pole piece is wrinkled, and record the tension F through the second tension sensor max2 ; (2) Maintaining the same environment, equipment and other conditions, replace the electrode with the same material and thickness, complete the same coating process, and then perform the same baking process (heating temperature is consistent). Continue to increase M1 until the electrode is wrinkled, and record the tension F through the first tension sensor. max1 , continue to increase M2 until the pole piece is wrinkled, and record the tension F through the second tension sensor max2 ; (3) Repeat step (2) several times to obtain a certain tension F max1 and some tension F max2 , calculate several tensions F max1 The average value and some tension F max2 The average value of x and F y .

5. The method for solving electrode wrinkling in coating process by near-zero tension control as claimed in claim 1, characterized in that: The value of T is 0.01N.

6. The method for solving electrode wrinkling during coating process by near-zero tension control as claimed in claim 1, characterized in that: F a The value range is 0.01F x -0.99F x , F b The value range is 0.01F y -0.99F y .

Images