A lithium battery diaphragm drying system

Abstract

The present invention discloses a lithium battery diaphragm drying system, which relates to the technical field of lithium battery diaphragms. The lithium battery diaphragm drying system comprises: a drying box, a U-shaped drying chamber, an exhaust chamber, a hot air blower, a drying roller, an air supply port structure, and a first temperature sensor and a second temperature sensor. The U-shaped drying chamber comprises a first cavity, a second cavity and a third cavity, and the exhaust chamber is formed in the drying box; the drying process of the lithium battery diaphragm drying system comprises the following steps: introducing hot air into the first cavity and the second cavity respectively through the air supply port structure; obtaining temperature data collected by the first temperature sensor and the second temperature sensor; when the difference between the temperature data in the exhaust chamber and the average value of the temperature data in several air supply port structures is less than or equal to the first threshold value, the lithium battery semi-finished diaphragm is input into the first cavity for drying. The lithium battery diaphragm drying system of the present invention can improve the drying uniformity and yield rate of lithium battery semi-finished diaphragms.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery diaphragm drying, and in particular to a lithium battery diaphragm drying system. Background Art

[0002] Lithium battery separator is one of the key components inside lithium batteries. Lithium battery separator is usually made of polymer materials, such as polyethylene (PE), polypropylene (PP), etc. These polymers can be made into non-woven fabric structures, or their performance can be enhanced by coating technology. The main function of lithium battery separator is to separate the positive and negative electrodes of the battery to prevent the two electrodes from directly contacting each other and causing a short circuit, while allowing ions to conduct between the positive and negative electrodes to maintain the battery's charge and discharge process. In addition, it can also absorb a certain amount of electrolyte to keep the electrolyte inside the battery evenly distributed, thereby maintaining the stability of the electrolyte.

[0003] At present, in the process of preparing lithium battery separators, a certain amount of solvent still remains inside the lithium battery separator after solvent extraction. At this time, a drying process is generally used to remove these solvents.

[0004] In the existing related technology, the drying process is generally carried out in a drying room or a drying box, which uses hot air to dry the semi-finished lithium battery diaphragm. However, it has the following problems:

[0005] First, the existing drying room or drying box cannot effectively process the gas after drying, and cannot quickly restore the dry environment or maintain the dry environment, which will affect the drying uniformity of the semi-finished lithium battery diaphragm and the yield rate is not high.

[0006] Second, after being preheated to the drying temperature, the drying temperature in the existing drying room or drying box will fluctuate due to the opening of the sealing mechanism to facilitate the input of the semi-finished lithium battery diaphragm, or the activation of the exhaust and dehumidification functions, which may easily lead to the semi-finished lithium battery diaphragm that first enters the drying room or drying box not being fully dried, and will also affect the drying uniformity of the semi-finished lithium battery diaphragm, thereby resulting in a low yield rate.

[0007] Third, the temperature distribution in the existing drying room or drying box is uneven, and there is often a large temperature difference between the hot air inlet and the hot air outlet. This uneven temperature distribution will further aggravate the problem of poor drying uniformity of the semi-finished lithium battery diaphragm. Summary of the invention

[0008] The purpose of the present invention is to solve the above technical problems and provide a lithium battery diaphragm drying system.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A lithium battery diaphragm drying system is used for the drying process in the lithium battery diaphragm manufacturing process, comprising:

[0011] After the semi-finished lithium battery diaphragm is extracted, the semi-finished lithium battery diaphragm is input into the lithium battery diaphragm drying system for drying;

[0012] The lithium battery diaphragm drying system comprises:

[0013] A drying box, a U-shaped drying chamber, an exhaust chamber, a plurality of hot air blowers, a plurality of pairs of drying rollers, a plurality of pairs of air outlet structures, a first temperature sensor and a plurality of second temperature sensors, wherein the U-shaped drying chamber is formed in the drying box, the U-shaped drying chamber comprises a first cavity and a second cavity which are arranged opposite to each other, and a third cavity connected between the first cavity and the second cavity, one end of the first cavity and the second cavity which are away from the third cavity respectively extend to one end surface of the drying box so that one end of the first cavity and the second cavity is open, the third cavity is formed into a curved tubular structure, the exhaust chamber is formed in the drying box, one end of the exhaust chamber The first cavity and the second cavity are configured to be symmetrical about the exhaust cavity, and the end of the exhaust cavity away from the third cavity extends to the other end surface of the drying box so that one end of the exhaust cavity is open; a plurality of pairs of drying rollers are respectively arranged in the U-shaped drying cavity at intervals; a plurality of pairs of air supply port structures are respectively arranged in the drying box and are respectively connected to the first cavity or the second cavity, and a plurality of hot air blowers are respectively connected to a plurality of pairs of air supply port structures in a one-to-one correspondence; the first temperature sensor is arranged in the exhaust cavity, and a plurality of the second temperature sensors are respectively arranged in a plurality of pairs of air supply port structures;

[0014] The drying process of the lithium battery diaphragm drying system comprises the following steps:

[0015] Step S1: start a plurality of hot air blowers respectively, and introduce hot air into the first cavity and the second cavity respectively through a plurality of pairs of air supply outlet structures;

[0016] Step S2: Acquire temperature data collected by the first temperature sensor and the second temperature sensor;

[0017] When the difference between the temperature data in the exhaust cavity and the average value of the temperature data in the plurality of air supply outlet structures is less than or equal to the first threshold, the process proceeds to step S3;

[0018] Step S3: The semi-finished lithium battery diaphragm after extraction is input from the first cavity through a plurality of pairs of drying rollers. The semi-finished lithium battery diaphragm will pass through the first cavity, the third cavity and the second cavity in sequence under the drive of the plurality of pairs of drying rollers, and be output from the second cavity;

[0019] Among them, when the semi-finished lithium battery diaphragm passes through the U-shaped drying chamber, the air supply outlet structure arranged in the first cavity is configured so that the temperature of the hot air output by the corresponding air supply outlet structure gradually increases in the direction from the first cavity to the third cavity; at the same time, the air supply outlet structure arranged in the second cavity is configured so that the temperature of the hot air output by the corresponding air supply outlet structure gradually increases in the direction from the second cavity to the third cavity.

[0020] Optionally, the air outlet structures arranged in the first cavity are arranged at equal intervals and the interval between each two adjacent air outlet structures is L, and the hot air temperatures corresponding to the air outlet structures output in the direction from the first cavity to the third cavity are respectively , , , …, ,in,

[0021] The hot air temperature outputted by several air outlet structures satisfies:

[0022]

[0023] In the formula, , is the distance-to-temperature coefficient, is the hot air temperature output by the air outlet structure closest to the third cavity, is the glass transition temperature of the material corresponding to the semi-finished lithium battery diaphragm, is the hot air temperature output by the air outlet structure farthest from the third cavity, is the boiling point of the solvent used for extraction.

[0024] Optionally, in step S3, during the process of the semi-finished lithium battery separator passing through the U-shaped drying chamber, The hot air temperature output by the air outlet structure satisfy:

[0025]

[0026] In the formula, and are the temperature variation amplitude constants, and is the temperature change rate constant, is a natural constant, is the drying time in minutes, is the time point when the heating rate starts to slow down. is the time point when the cooling rate starts to increase, and .

[0027] Optionally, during the process of the semi-finished lithium battery separator passing through the U-shaped drying chamber, The hot air temperature output by the air outlet structure satisfy:

[0028]

[0029] In the formula, is a natural constant, is the drying time and is expressed in minutes.

[0030] Optionally, each pair of air outlet structures is arranged corresponding to each two adjacent pairs of drying rollers, and the two air outlet structures corresponding to each pair of air outlet structures are respectively located at the top and bottom of the first cavity or the second cavity, so as to supply hot air to the upper and lower surfaces of the semi-finished lithium battery diaphragm respectively;

[0031] Among them, the air supply outlet structure includes an air inlet section and an air guide section which are connected in sequence, the air inlet section is connected to the hot air blower at one end away from the air guide section, the air guide section includes an air guide surface which can produce a Coanda effect, so that the air guide surface can guide the hot air passing through, and the extension line of the curvature direction of the air guide surface passes through the symmetry center of each adjacent pair of drying rollers.

[0032] Optionally, the air supply outlet structure also includes a guide section connected between the air inlet section and the air guide section, the guide section includes a first part and a second part that are connected to each other, the first part is connected to the air inlet section at one end away from the second part, the second part extends axially along the first cavity or the second cavity and the second part is connected to the air guide section at one end away from the first part, wherein the second part is formed with a guide slope for guiding the hot air to the air guide surface, and the guide slope is arranged opposite to the air guide surface so that the hot air flowing out of the second part can flow to the air guide surface.

[0033] Optionally, one end of the air guide section away from the air inlet section is flush with an inner wall of the first cavity or the second cavity.

[0034] Optionally, the wind guide section comprises a wind guide wall and an enlarged wall, the wind guide surface is formed on the wind guide wall, the enlarged wall and the wind guide wall are arranged opposite to each other and the two together enclose to form the wind guide section;

[0035] Wherein, the second temperature sensor is arranged in the air guide section and close to the expansion wall; or,

[0036] The second temperature sensor is disposed in the air guiding section and installed on the enlarged wall.

[0037] The beneficial effects of the present invention include:

[0038] 1. First, when the lithium battery diaphragm drying system of the present invention is performing the drying process in the lithium battery diaphragm manufacturing process, hot air enters the first cavity and the second cavity from several pairs of air supply port structures respectively, and then is discharged through the third cavity and the exhaust cavity. In this way, the gas carrying the solvent after drying can also be quickly discharged through the third cavity and the exhaust cavity, that is, the gas carrying the solvent after drying stays or retains in the U-shaped drying cavity for a very short time, which can make the U-shaped drying cavity always maintain a dry environment, can effectively improve the drying uniformity of the semi-finished lithium battery diaphragm, and thus is conducive to improving the yield rate of the semi-finished lithium battery diaphragm.

[0039] Second, in the present invention, before drying, the drying environment will be detected. Specifically, in step S2 of the present invention, the difference between the temperature data collected by the first temperature sensor and the average temperature data collected by the second temperature sensor, that is, the difference between the temperature at the outlet and the average temperature in the U-shaped drying chamber, is calculated. When the temperature at the outlet is consistent with the average temperature in the U-shaped drying chamber, the semi-finished lithium battery diaphragm will be input into the drying box for drying. In this way, the temperature fluctuation generated when the semi-finished lithium battery diaphragm is input can be effectively avoided, and it can also be ensured that all parts of the semi-finished lithium battery diaphragm can be fully and relatively uniformly dried, which is beneficial to improve the drying uniformity of the semi-finished lithium battery diaphragm, and further improve the yield rate to a certain extent.

[0040] Third, when the lithium battery diaphragm drying system of the present invention performs the drying process in the lithium battery diaphragm manufacturing process, the temperature of the hot air output by the air outlet structure gradually increases in the direction of air intake and exhaust, so that the phenomenon of excessive temperature difference between the hot air inlet and the hot air outlet can be effectively alleviated, so that the temperature in the entire U-shaped drying chamber tends to be consistent, which can effectively ensure the drying uniformity of the semi-finished lithium battery diaphragm.

[0041] Other beneficial effects or advantages of the present invention will be described in detail in the specification in conjunction with specific implementations. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the proportional relationship of the various components in the drawings of this specification does not represent the proportional relationship in actual material selection and design, which is only a schematic diagram of the structure or position, wherein:

[0043] Figure 1 It is a schematic flow chart of the steps of the drying process of the lithium battery diaphragm drying system of the present invention;

[0044] Figure 2 It is a schematic diagram of the layout of the lithium battery diaphragm drying system of the present invention;

[0045] Figure 3 yes Figure 2 A schematic diagram of the enlarged local structure at point A in the middle.

[0046] Description of the reference numerals in the accompanying drawings:

[0047] 100-lithium battery diaphragm drying system; 200-lithium battery semi-finished diaphragm; 1-drying box; 2-U-shaped drying chamber; 21-first chamber; 22-second chamber; 23-third chamber; 3-exhaust chamber; 5-drying roller; 6-air supply port structure; 61-air inlet section; 62-air guide section; 621-air guide surface; 622-air guide wall; 623-expansion wall; 63-guide section; 631-first part; 632-second part; 6321-guide slope; 71-first temperature sensor; 72-second temperature sensor. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0049] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0050] Example 1

[0051] like Figure 1 and Figure 2 As shown, the present invention provides a lithium battery diaphragm drying system 100, which is used in a drying process in a lithium battery diaphragm manufacturing process, comprising:

[0052] After the semi-finished lithium battery diaphragm 200 is extracted, the semi-finished lithium battery diaphragm 200 is input into the lithium battery diaphragm drying system 100 for drying;

[0053] The lithium battery diaphragm drying system 100 comprises:

[0054] A drying box 1, a U-shaped drying chamber 2, an exhaust chamber 3, a plurality of hot air blowers, a plurality of pairs of drying rollers 5, a plurality of pairs of air outlet structures 6, a first temperature sensor 71 and a plurality of second temperature sensors 72, wherein the U-shaped drying chamber 2 is formed in the drying box 1, the U-shaped drying chamber 2 comprises a first cavity 21 and a second cavity 22 which are arranged opposite to each other, and a third cavity 23 which is connected between the first cavity 21 and the second cavity 22, the ends of the first cavity 21 and the second cavity 22 which are away from the third cavity 23 respectively extend to an end surface of the drying box 1 so that one end of the first cavity 21 and the second cavity 22 is open, the third cavity 23 is formed into a curved tubular structure, and the exhaust chamber 3 is formed in the drying box 1. In the drying box 1, one end of the exhaust cavity 3 is connected to the middle of the third cavity 23, and the first cavity 21 and the second cavity 22 are configured to be symmetrical about the exhaust cavity 3, and one end of the exhaust cavity 3 away from the third cavity 23 extends to the other end surface of the drying box 1 so that one end of the exhaust cavity 3 is open; a plurality of pairs of drying rollers 5 are respectively arranged in the U-shaped drying cavity 2 at intervals; a plurality of pairs of air supply port structures 6 are respectively arranged in the drying box 1 and are respectively connected to the first cavity 21 or the second cavity 22, and a plurality of hot air blowers are respectively connected to the plurality of pairs of air supply port structures 6 in a one-to-one correspondence; a first temperature sensor 71 is arranged in the exhaust cavity 3, and a plurality of second temperature sensors 72 are respectively arranged in the plurality of pairs of air supply port structures 6;

[0055] The drying process of the lithium battery diaphragm drying system 100 includes the following steps:

[0056] Step S1: start a plurality of hot air blowers respectively, and introduce hot air into the first cavity 21 and the second cavity 22 respectively through a plurality of pairs of air supply outlet structures 6;

[0057] Step S2: Acquire temperature data collected by the first temperature sensor 71 and the second temperature sensor 72;

[0058] When the difference between the temperature data in the exhaust cavity 3 and the average value of the temperature data in the plurality of air supply outlet structures 6 is less than or equal to the first threshold, the process proceeds to step S3;

[0059] Step S3: The semi-finished lithium battery diaphragm 200 after extraction is input from the first cavity 21 through a plurality of pairs of drying rollers 5. The semi-finished lithium battery diaphragm 200 will pass through the first cavity 21, the third cavity 23 and the second cavity 22 in sequence under the drive of the plurality of pairs of drying rollers 5, and be output from the second cavity 22;

[0060] Among them, when the lithium battery semi-finished product diaphragm 200 passes through the U-shaped drying chamber 2, the air supply outlet structure 6 arranged in the first cavity 21 is configured so that the temperature of the hot air output by the corresponding air supply outlet structure 6 gradually increases in the direction from the first cavity 21 to the third cavity 23; at the same time, the air supply outlet structure 6 arranged in the second cavity 22 is configured so that the temperature of the hot air output by the corresponding air supply outlet structure 6 gradually increases in the direction from the second cavity 22 to the third cavity 23.

[0061] Through the above technical scheme, first, when the lithium battery diaphragm drying system 100 of the present invention is performing the drying process in the lithium battery diaphragm manufacturing process, hot air enters the first cavity 21 and the second cavity 22 from several pairs of air supply port structures 6 respectively, and then is discharged through the third cavity 23 and the exhaust cavity 3. In this way, the gas carrying the solvent after drying can also be quickly discharged through the third cavity 23 and the exhaust cavity, that is, the gas carrying the solvent after drying stays or retains in the U-shaped drying cavity 2 for a very short time, which can make the U-shaped drying cavity 2 always maintain a dry environment, and can effectively improve the drying uniformity of the lithium battery semi-finished diaphragm 200, which is beneficial to improve the yield rate of the lithium battery semi-finished diaphragm 200.

[0062] Second, in the present invention, before drying, the drying environment is detected. Specifically, in step S2 of the present invention, the difference between the temperature data collected by the first temperature sensor 71 and the average temperature data collected by the second temperature sensor 72 is first calculated, that is, the difference between the temperature at the outlet (the temperature data collected by the first temperature sensor 71) and the average temperature in the U-shaped drying chamber 2 (the average temperature data collected by the second temperature sensor 72). When the temperature at the outlet is consistent with the average temperature in the U-shaped drying chamber 2 (that is, the difference between the two is less than or equal to the first threshold value), the semi-finished lithium battery diaphragm 200 will be input into the drying box 1 for drying. In this way, the temperature fluctuation generated when the semi-finished lithium battery diaphragm 200 is input can be effectively avoided, and it can also be ensured that all parts of the semi-finished lithium battery diaphragm 200 can be fully and relatively uniformly dried, which is beneficial to improve the drying uniformity of the semi-finished lithium battery diaphragm 200, and further improve the yield rate to a certain extent.

[0063] Third, when the lithium battery diaphragm drying system 100 of the present invention is performing the drying process in the lithium battery diaphragm manufacturing process, the temperature of the hot air output by the air supply port structure 6 in the direction of air intake and exhaust (i.e., in the direction from the first cavity 21 to the third cavity 23, or in the direction from the second cavity 22 to the third cavity 23) gradually increases. In this way, the phenomenon of excessive temperature difference between the hot air inlet and the hot air outlet can be effectively alleviated, so that the temperature in the entire U-shaped drying chamber 2 tends to be consistent, which can effectively ensure the drying uniformity of the lithium battery semi-finished diaphragm 200.

[0064] In this embodiment, it should be noted that, first, since other processes or equipment in the lithium battery separator manufacturing process, such as raw material processing, extrusion, cooling and solidification, longitudinal drawing, transverse stretching and extraction, are widely used in the existing related technologies, they will not be described in detail in the present invention. The present invention is mainly used in the drying process after extraction.

[0065] Second, the third cavity 23 of the present invention is formed into a curved tubular structure in order to ensure the normal passage of the semi-finished lithium battery diaphragm 200, and to collect and export the hot air transmitted from the first cavity 21 and the second cavity 22. In addition, the third cavity 23 configured in this way can also effectively reduce the flow rate of the hot air, so that the hot air can fully stay in the U-shaped drying chamber 2 and continuously release heat to the semi-finished lithium battery diaphragm 200, so as to improve the volatilization efficiency of the solvent, which is also conducive to improving the drying efficiency. At the same time, the third cavity 23 configured in this way can also prevent the hot air from entering the first cavity 21 or the second cavity 22 from the air supply port and then being directly discharged into the exhaust cavity 3 through the third cavity 23, which can effectively avoid the waste of energy.

[0066] Third, the several second temperature sensors 72 of the present invention are arranged in the air supply port structure 6 connected to the U-shaped drying chamber 2, which can not only accurately obtain the actual temperature in the U-shaped drying chamber 2, but also effectively avoid spatial interference with the semi-finished lithium battery diaphragm 200 during the drying process, thereby avoiding damage to the semi-finished lithium battery diaphragm 200.

[0067] Fourth, through the U-shaped drying chamber 2 provided in the present invention, the semi-finished lithium battery diaphragm 200 is input from the first cavity 21, and output from the second cavity 22 after passing through the third cavity 23. The entire semi-finished lithium battery diaphragm 200 is transported in a U-shaped drying route during the drying process. Compared with the linearly arranged drying equipment in the prior art (that is, the semi-finished lithium battery diaphragm 200 is input from one end and output from the other end, and the semi-finished lithium battery diaphragm 200 is transported in a linear drying route during the drying process), it can not only effectively reduce the overall volume and floor space of the drying equipment, but also effectively ensure that both sides of the semi-finished lithium battery diaphragm 200 can be fully and evenly dried, and can effectively ensure the yield rate.

[0068] In one embodiment of the present invention, the air outlet structures 6 arranged in the first cavity 21 (or the second cavity 22) of the present invention are arranged at equal intervals and the interval between each two adjacent air outlet structures 6 is L, and the hot air temperatures corresponding to the output of the air outlet structures 6 in the direction from the first cavity 21 (or the second cavity 22) to the third cavity 23 are respectively , , , …, ,in,

[0069] The hot air temperature outputted by the plurality of air outlet structures 6 satisfies:

[0070]

[0071] In the formula, , is the distance-to-temperature coefficient, is the temperature of the hot air output by the air outlet structure 6 closest to the third cavity 23, is the glass transition temperature of the material corresponding to the semi-finished lithium battery separator 200, is the temperature of the hot air outputted by the air outlet structure 6 farthest from the third cavity 23, is the boiling point of the solvent used for extraction.

[0072] In this way, through the above-mentioned technical scheme, the temperature of the hot air output by the air supply outlet structure 6 that is closer to the exhaust chamber 3 can be higher, which is beneficial to making the temperature distribution in the entire U-shaped drying chamber 2 tend to be consistent, making the drying process of the semi-finished lithium battery diaphragm 200 in the U-shaped drying chamber 2 more balanced, and making the semi-finished lithium battery diaphragm 200 fully and relatively uniformly dried, which is beneficial to improving the drying uniformity of the semi-finished lithium battery diaphragm 200, and thus can further improve the yield rate to a certain extent.

[0073] In this embodiment, it can be understood that The specific value of can be selected after comprehensive consideration of the setting spacing, the required drying temperature and the temperature distribution, and the present invention does not make any specific limitation on this.

[0074] In the existing related technology, drying is generally performed at a constant temperature. However, in this case, the semi-finished lithium battery diaphragm 200 may have uneven internal stress, which may easily cause cracks or holes in the semi-finished lithium battery diaphragm 200.

[0075] In view of this, in one embodiment of the present invention, in step S3 of the present invention, during the process of the lithium battery semi-finished diaphragm 200 passing through the U-shaped drying chamber 2, The hot air temperature output by the air outlet structure 6 satisfy:

[0076]

[0077] In the formula, and are the temperature variation amplitude constants, and is the temperature change rate constant, is a natural constant, is the drying time in minutes, is the time point when the heating rate starts to slow down. is the time point when the cooling rate starts to increase, and .

[0078] In this embodiment, the The temperature of the hot air output by the air outlet structure 6 will change with the drying time. The growth of first gradually increases, then gradually decreases, and finally approaches a certain value. Specifically, In the process, the value of hot air temperature gradually increases. When During the process, the temperature is still kept rising, but the rate of heating is gradually reduced and gradually turns into cooling. When the temperature drops, the cooling rate starts to increase, and the hot air temperature gradually decreases. Finally, as the drying time increases, As the temperature increases, it gradually approaches a certain value.

[0079] In this way, through the above-mentioned technical scheme, the temperature of the hot air output by the air outlet structure 6 can show a certain change, that is, it gradually increases in temperature first, then gradually decreases in temperature, and finally approaches a certain value. The lithium battery semi-finished diaphragm 200 can be initially dried at a slightly lower temperature, and then the temperature is gradually increased and then lowered to complete the entire drying process. It can effectively slow down the drying rate, which is beneficial to avoid the problem of cracks or holes in the diaphragm due to uneven internal stress.

[0080] In an exemplary embodiment of the present invention, during the process of the semi-finished lithium battery separator 200 passing through the U-shaped drying chamber 2, the first The hot air temperature output by the air outlet structure 6 satisfy:

[0081]

[0082] In the formula, is a natural constant, is the drying time and is expressed in minutes.

[0083] That is to say, Set to 5, Set to 3, and Both are set to 0.08. Set to 180 (i.e. 180 minutes), Set to 360 (i.e. 360 minutes). In this way, the temperature can be gradually increased in the first 180 minutes of the drying process, and the temperature can still be increased during the process from 180 minutes to 360 minutes, but the heating rate gradually decreases and gradually turns to cooling. After 360 minutes, the cooling rate begins to increase, and the value of the hot air temperature gradually decreases. Finally, as the drying time increases, its temperature gradually approaches a certain value. It can effectively slow down the drying rate and help avoid cracks or holes in the diaphragm due to uneven internal stress.

[0084] In one embodiment of the present invention, Figure 2 and Figure 3As shown, each pair of air outlet structures 6 of the present invention is arranged corresponding to each two adjacent pairs of drying rollers 5, and the two air outlet structures 6 corresponding to each pair of air outlet structures 6 are respectively located at the top and bottom of the first cavity 21 or the second cavity 22, so as to supply hot air to the upper and lower surfaces of the lithium battery semi-finished diaphragm 200 respectively; wherein, the air outlet structure 6 includes an air inlet section 61 and an air guide section 62 connected in sequence, and the end of the air inlet section 61 away from the air guide section 62 is connected to the hot air blower, and the air guide section 62 includes an air guide surface 621 that can produce a Coanda effect, so that the air guide surface 621 can guide the passing hot air, and the extension line of the curvature direction of the air guide surface 621 passes through the corresponding symmetry center of each two adjacent pairs of drying rollers 5.

[0085] In this embodiment, first, it should be noted that since the drying roller 5 is arranged in the U-shaped drying chamber 2 and is used to transport the semi-finished lithium battery diaphragm 200, it will inevitably hinder or interfere with the flow of hot air, which will affect the heat conduction between the hot air and the semi-finished lithium battery diaphragm 200, and will affect the drying effect of the semi-finished lithium battery diaphragm 200. Therefore, in the present invention, each pair of air supply port structures 6 is arranged corresponding to each two adjacent pairs of drying rollers 5, so that there is a pair of air supply port structures 6 between each two adjacent pairs of drying rollers 5, which can effectively ensure that the hot air can be in direct contact with the semi-finished lithium battery diaphragm 200 for heat exchange, thereby ensuring the drying effect of the semi-finished lithium battery diaphragm 200.

[0086] Second, the two air supply outlet structures 6 corresponding to each pair of air supply outlet structures 6 correspond to the upper and lower surfaces of the semi-finished lithium battery diaphragm 200 to supply hot air thereto respectively, so that the drying uniformity of the semi-finished lithium battery diaphragm 200 can be effectively ensured.

[0087] Third, the air outlet structure 6 guides the air through the air guide surface 621 that can produce the Coanda effect. In this way, on the one hand, it can effectively avoid setting an air outlet pipe in the U-shaped drying chamber 2 (in the existing related technologies, the air outlet pipe is arranged in the drying chamber to guide the hot air to the semi-finished lithium battery diaphragm 200), which can not only effectively reduce the difficulty of arrangement and processing complexity, but also avoid the spatial interference between the air outlet pipe and the semi-finished lithium battery diaphragm 200. On the other hand, since the air guide surface 621 guides the air by using the Coanda effect, the hot air velocity is relative to the hot air velocity of the direct blowing method. The flow rate of the hot air will be more gentle, which can effectively reduce the impact force of the hot air on the semi-finished lithium battery diaphragm 200, and can effectively improve the state stability of the semi-finished lithium battery diaphragm 200 during the drying process, and further effectively ensure the stability of the drying effect and the uniformity of the semi-finished lithium battery diaphragm 200.

[0088] In this embodiment, it should be noted that the Coanda effect means that the fluid tends to deviate from the original flow direction and flow along the surface of the protrusion. In other words, when there is surface friction between the hot air and the surface of the object it flows through, as long as the curvature is not large, the fluid will flow along the surface of the object.

[0089] It is understood that in the prior art, a "surface capable of producing a Coanda effect" is a well-known type of surface, near which a Coanda effect can be produced on a fluid, and the fluid tends to flow near the surface, and the fluid is almost "attached" or "wrapped" to the surface. The Coanda effect is a proven and practical method of fluid adhesion.

[0090] In one embodiment of the present invention, Figure 2 and Figure 3 As shown, the air supply outlet structure 6 of the present invention may also include a guide section 63 connected between the air inlet section 61 and the air guide section 62, the guide section 63 includes a first part 631 and a second part 632 that are connected to each other, the first part 631 is connected to the air inlet section 61 at one end away from the second part 632, the second part 632 extends axially along the first cavity 21 or the second cavity 22 and the second part 632 is connected to the air guide section 62 at one end away from the first part 631, wherein the second part 632 is formed with a guide slope 6321 for guiding the hot air to the air guide surface 621, and the guide slope 6321 is arranged opposite to the air guide surface 621 so that the hot air flowing out of the second part 632 can flow to the air guide surface 621.

[0091] In this way, first, the guide section 63 can guide the hot air in the air inlet section 61 at any position, so that in actual application, the setting position of the air inlet section 61 can be adjusted according to the actual equipment (to adapt to the drying box 1 and the hot air blower of different setting types or positions), which can effectively improve the versatility of the air supply port structure 6 of the present invention. Moreover, the guide section 63 set in this way can guide the hot air to flow to the air guide surface 621 in a more coordinated direction (that is, the axial direction of the first cavity 21 or the second cavity 22), which is more convenient to cooperate with the air guide surface 621 to achieve the hot air diversion.

[0092] Second, by providing the guiding slope 6321, the hot air output from the guiding section 63 can be guided toward the wind guide surface 621, which is also beneficial to prevent the hot air from being adsorbed by other surfaces, and can effectively ensure the wind guiding effect.

[0093] In one embodiment of the present invention, Figure 2 and Figure 3As shown, the end of the air guide section 62 of the present invention away from the air inlet section 61 is flush with the inner wall of the first cavity 21 or the second cavity 22. In this way, the air guide section 62 configured in this way will not extend into the U-shaped drying chamber 2, which can effectively avoid spatial interference between the air outlet structure 6 and the semi-finished lithium battery diaphragm 200.

[0094] In one embodiment of the present invention, Figure 3 As shown, the air guide section 62 of the present invention may include an air guide wall 622 and an expansion wall 623, the air guide surface 621 is formed on the air guide wall 622, the expansion wall 623 and the air guide wall 622 are relatively arranged and the two together enclose the air guide section 62; wherein the second temperature sensor 72 is arranged in the air guide section 62 and close to the expansion wall 623; or, the second temperature sensor 72 is arranged in the air guide section 62 and installed on the expansion wall 623.

[0095] In this way, the expansion wall 623 can avoid interfering with the hot air diversion process of the wind guide surface 621, so that the hot air can be accurately guided to the position in contact with the lithium battery semi-finished diaphragm 200. At the same time, the expansion wall 623 can also provide sufficient and convenient installation space for the installation of the second sensor.

[0096] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium battery diaphragm drying system, characterized in that: Drying process used in the manufacturing process of lithium battery separators, including: After the lithium battery semi-finished product diaphragm (200) is extracted, the lithium battery semi-finished product diaphragm (200) is input into a lithium battery diaphragm drying system for drying; The lithium battery diaphragm drying system comprises: A drying box (1), a U-shaped drying chamber (2), an exhaust chamber (3), a plurality of hot air blowers, a plurality of pairs of drying rollers (5), a plurality of pairs of air outlet structures (6), and a first temperature sensor (71) and a plurality of second temperature sensors (72), wherein the U-shaped drying chamber (2) is formed in the drying box (1), the U-shaped drying chamber (2) comprises a first cavity (21) and a second cavity (22) arranged opposite to each other, and a third cavity (23) connected between the first cavity (21) and the second cavity (22), one end of the first cavity (21) and the second cavity (22) away from the third cavity (23) respectively extending to one end surface of the drying box (1) so that one end of the first cavity (21) and the second cavity (22) is open, the third cavity (23) is formed as a curved tubular structure, and the exhaust chamber (3) is formed in the drying box (1). The first cavity (21) and the second cavity (22) are configured to be symmetrical with respect to the exhaust cavity (3); the end of the exhaust cavity (3) away from the third cavity (23) extends to the other end surface of the drying box (1) so that one end of the exhaust cavity (3) is open; a plurality of pairs of drying rollers (5) are arranged in the U-shaped drying cavity (2) at intervals; a plurality of pairs of air supply outlet structures (6) are arranged in the drying box (1) and are respectively connected to the first cavity (21) or the second cavity (22); a plurality of hot air blowers are respectively connected to the plurality of pairs of air supply outlet structures (6) in a one-to-one correspondence; the first temperature sensor (71) is arranged in the exhaust cavity (3); and a plurality of second temperature sensors (72) are respectively arranged in the plurality of pairs of air supply outlet structures (6); The semi-finished lithium battery diaphragm after extraction is input from the first cavity through several pairs of drying rollers. The semi-finished lithium battery diaphragm will pass through the first cavity, the third cavity and the second cavity in sequence under the drive of several pairs of drying rollers, and be output from the second cavity; Among them, when the semi-finished lithium battery diaphragm passes through the U-shaped drying chamber, the air supply outlet structure arranged in the first cavity is configured so that the temperature of the hot air output by the corresponding air supply outlet structure gradually increases in the direction from the first cavity to the third cavity; at the same time, the air supply outlet structure arranged in the second cavity is configured so that the temperature of the hot air output by the corresponding air supply outlet structure gradually increases in the direction from the second cavity to the third cavity.

2. A lithium battery diaphragm drying system according to claim 1, characterized in that: The air outlet structures arranged in the first cavity are arranged at equal intervals and the interval between each two adjacent air outlet structures is L. The hot air temperatures corresponding to the air outlet structures output in the direction from the first cavity to the third cavity are respectively , , , …, ,in, The hot air temperature outputted by several air outlet structures satisfies: In the formula, , is the distance-to-temperature coefficient, is the hot air temperature output by the air outlet structure closest to the third cavity, is the glass transition temperature of the material corresponding to the semi-finished lithium battery diaphragm, is the hot air temperature output by the air outlet structure farthest from the third cavity, is the boiling point of the solvent used for extraction.

3. A lithium battery diaphragm drying system according to claim 2, characterized in that: When the semi-finished lithium battery separator passes through the U-shaped drying chamber, The hot air temperature output by the air outlet structure satisfy: In the formula, and are the temperature variation amplitude constants, and is the temperature change rate constant, is a natural constant, is the drying time in minutes, is the time point when the heating rate starts to slow down. is the time point when the cooling rate starts to increase, and .

4. A lithium battery diaphragm drying system according to claim 2, characterized in that: When the semi-finished lithium battery separator passes through the U-shaped drying chamber, The hot air temperature output by the air outlet structure satisfy: In the formula, is a natural constant, is the drying time and is expressed in minutes.

5. A lithium battery diaphragm drying system according to any one of claims 1 to 4, characterized in that: Each pair of air supply outlet structures (6) is provided corresponding to each two adjacent pairs of drying rollers (5), and the two air supply outlet structures (6) corresponding to each pair of air supply outlet structures (6) are respectively located at the top and bottom of the first cavity (21) or the second cavity (22), so as to supply hot air to the upper and lower surfaces of the semi-finished lithium battery diaphragm (200) respectively; The air supply port structure (6) comprises an air inlet section (61) and an air guide section (62) which are connected in sequence, the air inlet section (61) being connected to the hot air blower at one end away from the air guide section (62), the air guide section (62) comprising an air guide surface (621) capable of generating a Coanda effect, so that the air guide surface (621) can guide the hot air passing through, and an extension line of the curvature direction of the air guide surface (621) passes through the symmetry center of each adjacent pair of drying rollers (5).

6. A lithium battery diaphragm drying system according to claim 5, characterized in that: The air supply port structure (6) further comprises a guide section (63) connected between the air inlet section (61) and the air guide section (62), the guide section (63) comprising a first part (631) and a second part (632) which are connected to each other, the first part (631) being connected to the air inlet section (61) at one end away from the second part (632), the second part (632) extending along the axial direction of the first cavity (21) or the second cavity (22), and the second part (632) being connected to the air guide section (62) at one end away from the first part (631), wherein the second part (632) is formed with a guide inclined surface (6321) for guiding hot air to the air guide surface (621), the guide inclined surface (6321) being arranged opposite to the air guide surface (621) so that the hot air flowing out of the second part (632) can flow to the air guide surface (621).

7. A lithium battery diaphragm drying system according to claim 5, characterized in that: One end of the air guide section (62) away from the air inlet section (61) is flush with the inner wall of the first cavity (21) or the second cavity (22).

8. A lithium battery diaphragm drying system according to claim 5, characterized in that: The wind guide section (62) comprises a wind guide wall (622) and an enlarged wall (623); the wind guide surface (621) is formed on the wind guide wall (622); the enlarged wall (623) and the wind guide wall (622) are arranged opposite to each other and the two together enclose each other to form the wind guide section (62); Wherein, the second temperature sensor (72) is arranged in the air guide section (62) and close to the expansion wall (623); or, the second temperature sensor (72) is arranged in the air guide section (62) and installed on the expansion wall (623).

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