Pole piece baking device and feedback control process thereof

Abstract

The invention belongs to the technical field of lithium ion battery manufacturing, and particularly relates to a pole piece baking device which comprises an oven, a plurality of sets of water spraying devices are arranged in the oven, a humidifying device is arranged at a discharging opening of the oven, and the water spraying devices and the humidifying device are synchronously adjusted through a feedback control system. The feedback control system comprises a PLC and humidity sensors electrically connected with the PLC, the PLC is electrically connected with the water spraying device and the humidifying device, and the humidity sensors are arranged in the oven and the discharging port. The invention further relates to a feedback control process suitable for the pole piece baking device. By improving humidity control in the oven and optimizing equipment configuration, the problem of baking crack of the pole piece is effectively solved, the rework and rejection rate caused by baking crack in the production process is greatly reduced, the humidity uniformity and thermal stress balance of the pole piece in the high-temperature baking process are ensured, and the quality of the pole piece is improved. And the quality consistency and reliability of the finished battery are obviously improved. The production cost is effectively reduced, and the production efficiency and the equipment utilization rate are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery manufacturing, and in particular relates to a pole piece baking device and a feedback control process thereof. Background Art

[0002] In the manufacturing process of modern mobile phone batteries, lithium-ion batteries are widely used due to their high energy density and long life. However, as the requirements for battery energy density continue to increase, the battery manufacturing process is also facing higher challenges. Especially in the baking process of the negative electrode, due to the increase in the thickness of the electrode and the different thermal expansion coefficients of the materials, the electrode is prone to cracking under high temperature conditions.

[0003] The cracking phenomenon not only affects the mechanical strength and electrochemical properties of the negative electrode, but also leads to consistency and stability problems in the finished battery. Specifically, in the production of mobile phone batteries, the negative electrode needs to be baked at high temperature to remove the solvent and solidify the binder after coating, cutting and lamination. Due to the uneven temperature distribution during the baking process, the thermal expansion of the electrode material varies greatly, resulting in uneven distribution of humidity and thermal stress at the edge and middle of the electrode, which ultimately leads to warping and cracks at the edge of the electrode.

[0004] The current industry mainly attempts to improve the cracking problem by adjusting the oven temperature curve, increasing the tolerance of the electrode thickness, and reducing the number of electrodes in the oven, but these methods have limited effects and cannot fundamentally solve the problem. Therefore, a new technical means is urgently needed to effectively reduce or eliminate the cracking of negative electrode electrodes, especially in the production of mobile phone batteries with high load and high energy density. Summary of the invention

[0005] The purpose of the present invention is to provide a pole piece baking device and its feedback control process to address the deficiencies of the prior art, thereby effectively reducing or eliminating the problem of cracking of the negative pole piece and significantly improving product quality and production efficiency by controlling the humidity environment in the oven, optimizing the oven equipment structure, and introducing an innovative humidification and water spraying system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A pole piece baking device comprises an oven, wherein a plurality of water spray devices are arranged inside the oven, a humidifying device is arranged at the discharge port of the oven, the water spray devices and the humidifying device are synchronously adjusted by a feedback control system, the feedback control system comprises a PLC and a humidity sensor electrically connected thereto, the PLC is electrically connected to the water spray device and the humidifying device respectively, and the humidity sensor is arranged inside the oven and at the discharge port.

[0008] Preferably, the interior of the oven is divided into a plurality of working sections, and the water spray devices are arranged at equal intervals from the middle section to the end of the oven.

[0009] Preferably, the interior of the oven is divided into ten or more working sections, and the water spraying devices are arranged equidistantly from one-half of all the working sections to the end of the oven, and one water spraying device (2) is provided on each of the working sections (11) starting from the one-half.

[0010] Preferably, a single group of the water spray device includes an atomizing nozzle, a pole piece to be baked is provided in the oven, and one or more atomizing nozzles are provided on the left and right edges of the pole piece, and the atomizing nozzles are arranged on the upper surface and / or lower surface of the pole piece.

[0011] Preferably, the humidifying device comprises two symmetrically arranged humidifiers, and the humidifiers are fixedly connected to the left and right ends of the discharge port of the oven.

[0012] Preferably, the humidity sensors are arranged at equal intervals inside the oven, and a group of humidity sensors is also provided at the discharge port of the oven; a temperature sensor is also provided in the oven, and the temperature sensor is electrically connected to the PLC.

[0013] A feedback control process applicable to any of the above-mentioned electrode baking devices comprises the following steps:

[0014] Step 1: The electrode to be baked enters the oven and begins to be baked. The water spraying device located in the middle and rear section of the oven sprays water on the electrode to increase the humidity in the oven. The humidity in the box is 20%. The corresponding water spraying amount is controlled by adjusting the nozzle opening and air pressure of the water spraying device. The water spraying device is arranged on both sides of the edge of the electrode to prevent the edge of the electrode from being over-dried and cracked due to thermal stress concentration.

[0015] Step 2: The humidifying device provided at the discharge port of the oven performs secondary humidification treatment on the electrode piece that has completed baking. The humidifying device works synchronously with the oven. When the electrode piece flows out from the discharge port of the oven, the humidifying device sprays water mist on the electrode piece, and can automatically adjust the humidification amount according to the speed and temperature of the electrode piece leaving the oven, so as to ensure that the moisture content of the electrode piece edge is moderate when it passes through the roller after passing through the discharge port, and will not curl or crack;

[0016] Step 3: A feedback control system electrically connected to the water spray device and the humidifying device monitors the humidity and temperature changes inside the oven and at the discharge port in real time. The feedback control system collects data through a high-precision humidity sensor and a temperature sensor, and controls the water spray device and the humidifying device through a PLC to adjust the water spray humidification amount and humidification time in real time.

[0017] Preferably, in step 1, the installation position of the atomizing nozzle of the water spraying device is set according to the size of the electrode to be baked, the water spraying amount and water spraying time are adjusted in real time according to the thickness of the electrode, the coating material and the baking temperature, and the water spraying device in the oven increases its spraying humidity in sequence. It is generally set that the water spraying device is set at a position of 30° above the edge of the electrode, and its humidification amount is 14kg / h.

[0018] Preferably, in step 2, the humidifying device adopts ultrasonic atomization technology to quickly generate uniform water mist when the electrode piece passes at high speed, so that the humidity at the edge of the electrode piece can be replenished in time. The water mist flow rate and injection angle of the humidifying device are precisely adjusted according to the characteristics of different electrode pieces and the production rhythm to ensure the optimal humidification effect.

[0019] Preferably, in step 3, the feedback control system can automatically optimize the humidity curve according to the characteristics of different pole pieces and the baking process requirements, and control the spraying and humidifying effects of the water spray device and the humidifying device in real time to maintain the humidity uniformity and stability throughout the baking process.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the pole piece baking device and its feedback control process provided by the present invention effectively solve the problem of pole piece cracking by improving the humidity control in the oven and optimizing the equipment configuration, greatly reducing the rework and scrap rate caused by cracking in the production process, ensuring the humidity uniformity and thermal stress balance of the pole piece during high-temperature baking, and significantly improving the quality consistency and reliability of the finished battery. By reducing pole piece cracking and improving production yield, the present invention effectively reduces production costs and improves production efficiency and equipment utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0022] Figure 2 It is a structural schematic diagram of an embodiment of the present invention from another angle.

[0023] Figure 3 1 is a cathode temperature curve of each working section in the oven of the embodiment of the present invention.

[0024] Reference numerals:

[0025] 1. oven, 11. working section, 12. pole piece;

[0026] 2. Water spray device, 21. Atomizing nozzle;

[0027] 3. Humidification device, 31. Humidifier;

[0028] 4. Feedback control system, 41. PLC, 42. Humidity sensor, 43. Temperature sensor. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0030] like Figure 1 and Figure 2 As shown, the present invention provides an electrode baking device, including an oven 1 and a plurality of water spray devices 2 arranged therein, a humidifying device 3 is provided at the discharge port of the oven 1, the water spray device 2 and the humidifying device 3 are synchronously adjusted by a feedback control system 4, the feedback control system 4 includes a PLC 41 and a humidity sensor 42 electrically connected thereto, the PLC 41 is electrically connected to the water spray device 2 and the humidifying device 3 respectively, and the humidity sensor 42 is arranged inside the oven 1 and at the discharge port.

[0031] In this embodiment, by setting a continuously spaced water spray device 2 in the oven 1, water mist is sprayed on the pole piece 12 being baked in the oven 1 to adjust the humidity in the oven 1, prevent the edge of the pole piece from being over-dried and stress concentrated due to the high baking temperature, resulting in cracking or warping, and use the small-particle atomized water mist of the water spray device 2 to uniformly wet the edge of the pole piece, so that the pole piece 12 can be smoothly baked and flow out of the oven 1. The water spray device 2 is arranged at equal intervals in the oven 1 along the forward moving direction of the pole piece 12, and the water spray humidity is increased in sequence, so that the edge of the pole piece is gradually wetted to a suitable humidity, avoiding sudden humidification and producing a counter-effect. The water spray device 2 can adjust the water spraying amount and water spraying time in real time according to the thickness of the pole piece 12, the coating material and the baking temperature.

[0032] Furthermore, by further providing a humidifying device 3 at the discharge port of the oven 1, the electrode 12 that has completed baking is subjected to secondary humidification. The humidifying device 3 works synchronously with the water spraying device 2 in the oven 1, and can automatically adjust the humidification amount according to the speed and temperature of the electrode 12 flowing out of the oven 1, thereby ensuring that the moisture content of the electrode edge is moderate when passing through the tail roller of the machine, and will not curl or crack.

[0033] In order to optimize the use effect, the feedback control system 4 ( Figure 1 and Figure 2 The water spray device 2 and the humidification device 3 are connected in series, and the PLC 41 ( Figure 1 and Figure 2The feedback control system 4 can automatically optimize the humidity curve according to the characteristics of different pole pieces 12 and the baking process requirements to ensure the humidity uniformity and stability during the entire baking process. The system can also effectively reduce the quality fluctuations and production failures of the pole pieces 12 caused by improper humidity control.

[0034] Furthermore, the interior of the oven 1 is divided into a plurality of working sections 11, and the water spray devices 2 are arranged at equal intervals from the middle section to the end of the oven 1. After the pole piece 12 is baked and shaped in the front section in the oven 1, the water spray devices 2 in the middle and rear sections spray water to moisten the edge of the pole piece, and gradually increase the water spraying humidity to avoid cracking or warping caused by over-baking.

[0035] Furthermore, the interior of the oven 1 is divided into ten or more working sections 11, and the water spraying devices 2 are evenly arranged from the sixth working section 11 to the end of the oven 1, and a water spraying device 2 is arranged on each working section 11 from the sixth working section 11 onwards. In this embodiment, the interior of the oven 1 is evenly divided into 10 working sections 11, and high-precision water spraying devices 2 are installed at the 6th to 10th sections where the pole pieces 12 enter the oven 1, so as to gradually increase the humidity in the oven 1. Figure 3 As shown, at the same time, the negative electrode plate 12 can be appropriately and gradually cooled.

[0036] Furthermore, the single-group water spray device 2 includes an atomizing nozzle 21. The oven 1 is provided with a pole piece 12 to be baked. One or more atomizing nozzles 21 are provided on the left and right edges of the pole piece 12. The atomizing nozzle 21 is provided on the upper surface and / or lower surface of the pole piece 12. The atomizing nozzle 21 adopts a high-precision atomizing nozzle 21 to ensure that the water mist particle size is small and evenly distributed, and to avoid the warping and cracking of the pole piece caused by local over-wetting or over-drying. Moreover, the atomizing nozzle 21 is provided on both the front and back sides and the left and right sides of the pole piece 12, and is arranged in pairs of two above and below.

[0037] Furthermore, the humidifying device 3 includes two symmetrically arranged humidifiers 31, which are fixedly connected to the left and right ends of the discharge port of the unpacking. The humidifier 31 uses ultrasonic atomization technology to quickly generate uniform water mist when the pole piece 12 passes at high speed, so that the humidity at the edge of the pole piece is replenished in time. The water mist flow rate and injection angle of the humidifier 31 can be accurately adjusted according to the characteristics and production rhythm of different pole pieces 12 to ensure the optimal humidification effect.

[0038] Furthermore, humidity sensors 42 are arranged at equal intervals inside the oven 1, and a group of humidity sensors 42 are also arranged at the discharge port of the oven 1; a temperature sensor 43 is also arranged inside the oven 1, and the temperature sensor 43 is electrically connected to the PLC 41. Similarly, by detecting the temperature and humidity inside the oven 1, the water spray device 2 and the humidifying device 3 are adjusted in real time to achieve the best baking effect and obtain an overall flat and smooth electrode 12.

[0039] A feedback control process applicable to any of the above-mentioned electrode baking devices comprises the following steps:

[0040] Step 1: The electrode 12 to be baked enters the oven 1 and starts to be baked. The water spraying device 2 located in the middle and rear section of the oven 1 sprays water on the electrode 12 to increase the humidity in the oven 1. The humidity in the box is 20%. The corresponding water spraying amount is controlled by adjusting the nozzle opening and air pressure of the water spraying device. The water spraying device 2 is arranged on both sides of the edge of the electrode 12 to prevent the edge of the electrode from being over-dried and cracked due to thermal stress concentration;

[0041] Step 2: The humidifying device 3 provided at the discharge port of the oven 1 performs secondary humidification treatment on the electrode 12 that has completed baking. The humidifying device 3 works synchronously with the oven 1 and can automatically adjust the humidification amount according to the speed and temperature of the electrode 12 leaving the oven 1, so as to ensure that the moisture content of the electrode edge is moderate when it passes through the roller after passing through the discharge port, and will not curl or crack; specifically, the humidity is monitored in real time by the humidity sensor 42 inside the oven 1. When the humidity reaches the set value, a signal is given to the humidifier 31 for automatic humidification;

[0042] Step 3: The feedback control system 4 electrically connected to the water spray device 2 and the humidifying device 3 monitors the humidity and temperature changes inside the oven 1 and at the discharge port in real time. The feedback control system 4 collects data through a high-precision humidity sensor 42 and a temperature sensor 43, and controls the water spray device 2 and the humidifying device 3 through a PLC 41 to adjust the water spray device 2 and the humidifying device 3 in real time. Specifically, when the humidity sensor 42 detects that the humidity inside exceeds the range of 20%±2%, the automatic humidification operation is turned on or off.

[0043] Furthermore, in step 1, the installation position of the atomizing nozzle 21 of the water spray device 2 is set according to the size of the electrode 12, the water spraying amount and the water spraying time are adjusted in real time according to the thickness of the electrode 12, the coating material and the baking temperature, and the water spray device 2 in the oven 1 increases its spraying humidity sequentially.

[0044] Furthermore, in step 2, the humidifying device 3 uses ultrasonic atomization technology to quickly generate uniform water mist when the electrode 12 passes at high speed, so that the humidity at the edge of the electrode is replenished in time. The water mist flow rate and injection angle of the humidifying device 3 are precisely adjusted according to the characteristics and production rhythm of different electrode pieces 12 to ensure the optimal humidification effect.

[0045] Furthermore, in step 3, the feedback control system 4 can automatically optimize the humidity curve according to the characteristics of different pole pieces 12 and the baking process requirements, and control the spraying and humidifying effects of the water spray device 2 and the humidifying device 3 in real time to maintain the humidity uniformity and stability during the entire baking process.

[0046] In this embodiment, by performing corresponding improved production tests on the above scheme and comparing it with the products produced before the improvement, the following product defect rate data comparison is obtained. The defect rate data specifically refers to the actual production defect rate in the nine months before the improvement and the actual production defect rate in the three months after the improvement.

[0047]

[0048]

[0049] It can be seen from the above table that after the baking electrode is improved using the technical solution of the present invention, the product defect rate is significantly reduced. By adding a water spray device 2 in the oven 1 and a humidifying device 3 at the discharge port, and combining the feedback control system 4, the proportion of baking cracking abnormalities is greatly reduced to 0.21%-0.26%.

[0050] Before the improvement, the negative electrode plate was unevenly distributed in oven 1, causing the two sides of the plate to warp and the edges to crack, affecting the consistency and reliability of the battery. In actual production, the proportion of baking cracks reached 8.11%-9.81%.

[0051] By testing and analyzing the pole pieces of multiple production batches, the improved process significantly reduced the cracking of the pole pieces, and the edge cracking rate dropped from 9.81% to 0.21%. Data analysis shows that the effect of improving the cracking is obvious, and the overall quality and consistency of the pole pieces have been greatly improved. The present invention effectively solves the cracking problem of the negative pole pieces of mobile phone batteries, significantly reduces the edge cracks of the pole pieces, and significantly improves the overall quality and consistency, effectively improving product quality and production efficiency, and has a wide range of industrial application value.

[0052] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A pole piece baking device, characterized in that: The invention comprises an oven (1), wherein a plurality of water spray devices (2) are arranged inside the oven (1), a humidifying device (3) is arranged at the discharge port of the oven (1), the water spray devices (2) and the humidifying device (3) are synchronously adjusted by a feedback control system (4), the feedback control system (4) comprises a PLC (41) and a humidity sensor (42) electrically connected thereto, the PLC (41) is electrically connected to the water spray devices (2) and the humidifying device (3) respectively, and the humidity sensor (42) is arranged inside the oven (1) and at the discharge port.

2. The electrode baking device according to claim 1, characterized in that: The interior of the oven (1) is divided into a plurality of working sections (11), and the water spray devices (2) are arranged at equal intervals from the middle section to the end of the oven (1).

3. The electrode baking device according to claim 2, characterized in that: The interior of the oven (1) is divided into ten or more working sections (11), and the water spraying devices (2) are arranged equidistantly from one half of all the working sections (11) to the end of the oven (1), and one water spraying device (2) is arranged on each of the working sections (11) starting from the one half.

4. The electrode baking device according to claim 1, characterized in that: A single group of the water spray device (2) comprises an atomizing nozzle (21), a pole piece (12) to be baked is provided in the oven (1), and one or more atomizing nozzles (21) are provided on both left and right edges of the pole piece (12), and the atomizing nozzles (21) are arranged on the upper surface and / or the lower surface of the pole piece (12).

5. The electrode baking device according to claim 1, characterized in that: The humidifying device (3) comprises two symmetrically arranged humidifiers (31), and the humidifiers (31) are fixedly connected to the left and right ends of the discharge port of the oven (1).

6. The electrode baking device according to claim 1, characterized in that: The humidity sensors (42) are arranged at equal intervals inside the oven (1), and a group of humidity sensors (42) are also provided at the discharge port of the oven (1); a temperature sensor (43) is also provided inside the oven (1), and the temperature sensor (43) is electrically connected to the PLC (41).

7. A feedback control process applicable to the electrode baking device according to any one of claims 1 to 6, characterized in that: The steps include: Step 1: The electrode piece (12) to be baked enters the oven (1) and begins to be baked. A water spraying device (2) located in the middle and rear section of the oven (1) sprays water on the electrode piece (12). The water spraying device (2) is arranged on both sides of the edge of the electrode piece (12); Step 2: a humidifying device (3) provided at the discharge port of the oven (1) performs secondary humidification treatment on the electrode piece (12) that has completed baking, wherein the humidifying device (3) and the oven (1) work synchronously, and when the electrode piece (12) flows out of the discharge port of the oven (1), the humidifying device (3) sprays water mist on the electrode piece (12); Step 3: A feedback control system (4) electrically connected to the water spray device (2) and the humidifying device (3) monitors the humidity and temperature changes inside the oven (1) and at the discharge port in real time. The feedback control system (4) collects data through a high-precision humidity sensor (42) and a temperature sensor (43), and controls the water spray device (2) and the humidifying device (3) to adjust the water spray humidification amount and humidification time in real time through a PLC (41).

8. The feedback control process according to claim 7, characterized in that: In the step 1, the installation position of the atomizing nozzle (21) of the water spraying device (2) is set according to the size of the electrode to be baked, the water spraying amount and the water spraying time are adjusted in real time according to the thickness of the electrode (12), the coating material and the baking temperature, and the water spraying device (2) in the oven (1) increases its spraying humidity in sequence.

9. The feedback control process according to claim 7, characterized in that: In step 2, the humidifying device (3) uses ultrasonic atomization technology to quickly generate uniform water mist when the pole piece (12) passes at high speed, so that the humidity at the edge of the pole piece can be replenished in time.

10. The feedback control process according to claim 7, characterized in that: In step 3, the feedback control system (4) can automatically optimize the humidity curve according to the characteristics of different pole pieces (12) and the baking process requirements, and control the spraying and humidification effects of the water spray device (2) and the humidification device (3) in real time.

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