Infrared drying system and method for electrode plate coating

Abstract

The invention relates to the technical field of batteries, in particular to an infrared drying system and method for an electrode plate coating. An infrared drying system for an electrode slice coating comprises at least one drying unit, and each drying unit comprises a drying box body, a first drying part, a second drying part and an electrode slice material belt supporting device, the first drying part and the second drying part are oppositely arranged; the supporting device is located between the first drying part and the second drying part, and an air inlet part and an air exhaust part are arranged on the drying box body. According to the infrared drying system for the electrode plate coating, through cooperation of all the devices, the drying rate of the electrode plate coating can be increased, the bonding force of the coating is improved, the manufacturing takt is improved, the problem of appearance cracking is solved, and equipment operation energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to an infrared drying system and method for electrode sheet coating. Background Art

[0002] The manufacturing equipment technology of lithium-ion batteries in the new energy industry and the application of advanced processes are key technologies for the development of electric vehicles; the oven drying method, drying efficiency and temperature control technology of the coating machine for the production of electrode membranes of lithium batteries are one of the most advanced lithium-ion battery equipment manufacturing technologies; among them, the thick lithium iron phosphate electrode in the industry is prone to cracking after being coated into a membrane. The cracking mechanism is: first, the particle size of the main material of lithium iron phosphate is small, the specific surface area is large, and it is easy to agglomerate. The water vapor and water molecules are not easy to float and volatilize during the evaporation and drying process. The main reason is that the industry is currently hot air drying, and the surface drying membrane causes the surface wet membrane to solidify. The internal membrane moisture is dried and floated, and then the surface layer is broken, causing the membrane to crack in appearance; at the same time, the coating speed is low and the adhesion is low. The drying rate, product characteristics, process characteristics, and drying effect in the oven are the core focus and one of the difficulties in the manufacture of lithium-ion batteries; the existing equipment and application processes have obvious defects, such as high equipment energy consumption; severe membrane cracking during the drying process, decreased membrane adhesion, powder loss, and material loss.

[0003] The existing lithium-ion battery diaphragm manufacturing equipment and the oven drying method of the coating machine for diaphragm coating are to heat the return air through a heat exchanger, and the heat is blown into the oven for heat drying. The heat source is thermal oil, electric heating, or steam. The heat conversion efficiency is low at only 70%, and the energy consumption is high. The lithium battery product model and process window compatibility are poor, the manufacturing quality is low, and there are many appearance defects. When producing lithium iron phosphate thick electrode high surface density diaphragms, the appearance is prone to cracking, the adhesion is reduced, and the production speed needs to be reduced, resulting in a low manufacturing cycle.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] One object of the present invention is to provide an infrared drying system for electrode sheet coating to solve the above-mentioned technical problems. The infrared drying system of the present invention can increase the drying rate of electrode sheet coating, ensure the coating quality, enhance the coating adhesion, and reduce the energy consumption of equipment operation.

[0006] Another object of the present invention is to provide an infrared drying method for the electrode sheet coating, which can ensure the coating quality, improve the adhesion performance of the coating, and enhance the drying effect through the coordination of various steps.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] An infrared drying system for electrode sheet coatings comprises at least one drying unit, each of the drying units comprising a drying box and a first drying section, a second drying section and an electrode sheet strip supporting device arranged inside the drying box; the first drying section and the second drying section are arranged opposite to each other; the supporting device is located between the first drying section and the second drying section, and is used to support a wet electrode sheet strip and enable it to run; an air inlet and an air outlet are arranged on the drying box; the first drying section comprises a first drying air chamber, and the first drying air chamber is provided with a plurality of first infrared devices and a first air outlet matching therewith along the running direction of the wet electrode sheet strip; the second drying section comprises a second drying air chamber, and the second drying air chamber is provided with a plurality of second infrared devices and a second air outlet matching therewith along the running direction of the wet electrode sheet strip; the air inlet is connected to the first drying air chamber and the second drying air chamber respectively.

[0009] In some embodiments, the running speed of the wet electrode sheet is 75-85 m / min.

[0010] In some embodiments, the air inlet temperature of the air inlet portion in the first drying air chamber is set to 90-103°C, the power opening of the first infrared device is 45%-60%, and the fan frequency of the first infrared device is 35-45Hz; the air inlet temperature of the air inlet portion in the second drying air chamber is set to 86-93°C, the power opening of the second infrared device is 45%-95%, and the fan frequency of the second infrared device is 35-45Hz; the exhaust frequency of the exhaust device is 22-27Hz.

[0011] In some embodiments, a plurality of the drying units are sequentially connected and arranged along the running direction of the wet electrode sheet material belt; each of the drying units is provided with a feed port and a discharge port.

[0012] In some embodiments, the number of the drying units is 11-14.

[0013] In some embodiments, the first infrared device and the first air outlet are fixed and connected to form an integrated whole through a first lamp tube bracket, and the first lamp tube bracket is connected to the first drying air chamber.

[0014] In some embodiments, the second infrared device and the second air outlet are fixed and connected as one body via a second lamp bracket, and the second lamp bracket is connected to the second drying air chamber.

[0015] In some implementations, the number of the first infrared devices in each of the first drying chambers is 6 to 9; the number of the second infrared devices in each of the second drying chambers is 6 to 9.

[0016] In some embodiments, the air inlet portion includes an air inlet and an air inlet device disposed on the drying box body; the air exhaust portion includes an air exhaust port and an air exhaust device disposed on the drying box body.

[0017] In some embodiments, the supporting device includes a plurality of supporting rollers, and the supporting rollers are arranged in sequence along the running direction of the wet electrode sheet material belt.

[0018] An infrared drying method for electrode sheet coating, using the infrared drying system, comprises the following steps:

[0019] The wet electrode sheet strip that has completed coating enters the infrared drying system and operates under the action of the supporting device. The first infrared device of the first drying section performs the first infrared drying on the upper surface of the wet electrode sheet strip, and the second infrared device of the second drying section performs the second infrared drying on the lower surface of the wet electrode sheet strip. At the same time, the air inlet section transports dry air to the first drying air chamber and the second drying air chamber, performs the first blowing treatment through the first air outlet, and performs the second blowing treatment through the second air outlet. The exhaust section discharges the saturated moisture generated by the first infrared drying and the second infrared drying to the outside of the drying box to obtain the dried electrode sheet strip.

[0020] In some embodiments, the peeling force of the electrode sheet material strip after drying is 250-280 N / m, and the moisture content is 250-330 ppm.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The infrared drying system for electrode sheet coating of the present invention can improve the drying rate of electrode sheet coating, enhance the adhesion of coating, improve the manufacturing cycle, solve the problem of appearance cracking, and reduce the energy consumption of equipment operation through the coordination of various devices.

[0023] (2) The method of the present invention performs infrared drying and blowing treatment on the upper and lower surfaces of the wet electrode sheet material strip by the first drying section and the second drying section. Infrared irradiation removes moisture in the wet film sheet, causing the moisture in the film sheet to evaporate and vaporize. The blowing treatment blows away the evaporated and vaporized gas, so that the wet electrode sheet material strip is fully dried and a high-quality coating is formed, thereby improving the mechanical properties of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 Schematic diagram of the infrared drying system for the electrode sheet coating of the present invention.

[0026] Reference numerals:

[0027] 1-drying box, 2-first drying air chamber, 3-first infrared device, 4-support device, 5-second drying air chamber, 6-second infrared device, 7-wet electrode sheet material belt, 8-air inlet, 9-exhaust part, 10-first air outlet, 11-second air outlet. DETAILED DESCRIPTION

[0028] The embodiments of the present invention will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. If no specific conditions are specified in the examples, the conditions are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0029] According to one aspect of the present invention, the present invention relates to an infrared drying system for electrode sheet coating, comprising at least one drying unit, each of the drying units comprising a drying box body and a first drying section, a second drying section and an electrode sheet strip supporting device arranged inside the drying box body; the first drying section and the second drying section are arranged opposite to each other; the supporting device is located between the first drying section and the second drying section, and is used to support the wet electrode sheet strip and enable it to run; the drying box body is provided with an air inlet and an air outlet; the first drying section comprises a first drying air chamber, and the first drying air chamber is provided with a plurality of first infrared devices and a first air outlet matching therewith along the running direction of the wet electrode sheet strip; the second drying section comprises a second drying air chamber, and the second drying air chamber is provided with a plurality of second infrared devices and a second air outlet matching therewith along the running direction of the wet electrode sheet strip; the air inlet is respectively connected to the first drying air chamber and the second drying air chamber.

[0030] The infrared drying system for electrode sheet coating of the present invention can improve the drying rate of electrode sheet coating, enhance the adhesion of coating, improve the manufacturing cycle, solve the problem of appearance cracking, and reduce the energy consumption of equipment operation through the cooperation of various devices.

[0031] In some embodiments, the drying box includes an inner sealing plate, an insulation layer and an outer sealing plate which are arranged in sequence. The inner sealing plate is made of SUS304 material and is a stainless steel plate with a thickness of 0.8 to 1.2 mm; the outer sealing plate is made of SUS201 material and is a stainless steel plate with a thickness of 0.8 to 1.2 mm. The thickness of the insulation layer is 90 to 110 mm and is filled with nano-materials as the insulation layer, so that the inner and outer sealing plates are sealed as a whole.

[0032] In some embodiments, a plurality of drying units are sequentially connected and arranged along the running direction of the wet electrode sheet material belt. Each drying unit is provided with a feed port and a discharge port.

[0033] In some embodiments, the first drying air chamber and the second drying air chamber are each independently formed into a hollow cavity welded from a SUS304 stainless steel plate with a thickness of 0.8 to 1.2 mm. The first drying air chamber is used to connect the first air outlet and the first infrared heat device. Its main function and role is to act as a pressure-equalizing cavity to store and collect the dry air blown in through the air inlet through the air inlet, and then perform pressure-equalizing diversion, and blow it out from the first air outlet of each first infrared device, accompanied by the thermal radiation heating of the wet film by the first infrared heat device. The blown wind sweeps and transfers the evaporated moisture, and then the moisture is discharged through the first exhaust device through the exhaust port. The wind field in the entire drying box forms an in-and-out cycle to ensure that the pressure of the entire drying box is balanced, and the temperature and humidity are balanced, so as to achieve the purpose of drying the wet film after coating. The second drying air chamber is used to connect the second air outlet and the second infrared thermal device. Its main function and role is to serve as a pressure-equalizing cavity to store and collect the dry air blown in through the air inlet, and then to perform pressure-equalizing diversion and blow it out from the second air outlet of each second infrared device. Along with the thermal radiation heating of the wet film by the second infrared thermal device, the blown-out wind sweeps and transfers the evaporated moisture, and then the moisture is discharged through the discharge port through the second exhaust device. The wind field in the entire drying box forms an in-and-out cycle to ensure the pressure balance, temperature and humidity balance of the entire drying box, thereby achieving the purpose of drying the wet film after coating.

[0034] In some embodiments, the first infrared device and the second infrared device each independently include: a quartz glass lamp tube and a tungsten filament located inside the quartz glass lamp tube, the outer layer of the glass lamp tube is evenly coated with a gold-plated reflective layer; the quartz glass lamp tube is filled with an inert gas (e.g., at least one of Cl, Br, and I). After power is turned on, the tungsten filament is ionized to generate infrared rays. Different mechanisms can generate different rays. The generated rays are divided into short waves and medium waves, which are penetrating and absorbed and reflected by objects. The use of medium and short wave waveforms can make the coating absorb better and the penetrating heating rate stronger. The rays are reflected by the gold-plated layer and radiated onto the wet film to heat from the inside to the outside. The temperature can reach 600°C to 2500°C, and the water evaporates, achieving the effect of drying the electrode sheet.

[0035] In some embodiments, the first infrared device is integrated with the first air outlet by fixing and connecting it through a lamp bracket, and then integrated on the air outlet as a whole structure and integrated with the first drying air chamber. In some embodiments, the second external device is integrated with the second air outlet by fixing and connecting it through a lamp bracket, and then integrated on the air outlet as a whole structure and integrated with the second drying air chamber.

[0036] In some embodiments, the running speed of the wet electrode sheet material strip is 75 to 85 m / min, including but not limited to 75 m / min, 78 m / min, 80 m / min, 82 m / min or 85 m / min, or any range between the two. The infrared drying device of the present invention can further improve the running speed of the wet electrode sheet material strip and improve the preparation efficiency. The electrode sheet of the present invention adopts a suitable running speed to ensure both the preparation efficiency and the bonding performance of the electrode sheet coating.

[0037] In some embodiments, the support device includes a plurality of support rollers, which are arranged in sequence along the running direction of the wet electrode sheet. In some embodiments, the support roller is an aluminum roller with a diameter of 90 to 110 mm, the surface of which is polished and smooth after anodizing, and the aluminum roller is driven to rotate by the electrode to support and drive the wet film sheet forward.

[0038] In some embodiments, the air inlet includes an air inlet and an air inlet device provided on the drying box; the air exhaust includes an air outlet and an air exhaust device provided on the drying box. The air inlet is connected to the air duct as an air supply mechanism, and the air inlet is integrated with an opening adjustment grid plate for adjusting the cross-sectional area of ​​the air outlet, which can automatically adjust the size of the flow area, thereby controlling the size of the air volume; the debugging integrates a temperature and humidity detector to detect the temperature and humidity of the air at the air inlet online; the dry air delivered by the air inlet is delivered to the first drying air chamber and the second drying air chamber through the air inlet. The exhaust device discharges the saturated moisture generated in the box through the air outlet, and the air outlet is provided with a humidity sensor to detect the humidity online. At the same time, the opening (cross-sectional area) of the first exhaust outlet grid plate can be automatically adjusted according to the control requirements of the set value.

[0039] In some embodiments, the air inlet temperature of the air inlet portion in the first drying air chamber is set to 90-103°C (e.g., 90°C, 92°C, 95°C, 98°C, 99°C, 100°C, 103°C, etc.), the power opening of the first infrared device is 45%-60% (e.g., 45%, 50%, 55% or 60%, etc.), and the fan frequency of the first infrared device is 35-45 Hz (e.g.); the air inlet temperature of the air inlet portion in the second drying air chamber is set to 86-93°C ( For example, 86°C, 87°C, 88°C, 90°C, 91°C, 93°C, etc.), the power opening of the second infrared device is 45% to 95% (for example, 45%, 48%, 50%, 60%, 70%, 80% or 95%, etc.), and the fan frequency of the second infrared device is 35 to 45Hz (for example, 35Hz, 40Hz, 45Hz); the exhaust frequency of the exhaust device is 22 to 27Hz (for example, 22Hz, 23Hz, 25Hz, 27Hz, etc.). Among them, the greater the power opening, the greater the heating power of the infrared lamp tube, and the greater the heat generated by thermal radiation. The fan of the infrared device is used to cool the surface of the infrared lamp tube. The greater the fan power, the greater the air volume, and the setting rules are in direct proportion. The above-mentioned various parameter conditions of the present invention cooperate with each other to ensure the infrared drying effect of the electrode sheet coating, improve the drying rate, improve the adhesion performance of the coating, and improve the overall appearance quality and mechanical properties of the electrode sheet after drying.

[0040] In some embodiments, the number of drying units is 11-14, for example, 11, 12, 13 or 14.

[0041] In some embodiments, the number of first infrared devices in each first drying chamber is 6 to 9, such as 6, 7, 8 or 9. The number of second infrared devices in each second drying chamber is 6 to 9, such as 6, 7, 8 or 9.

[0042] In some embodiments, a discharge device, a coating device and a receiving device are also included. The discharge device provides a current collector strip, and a coating is applied in the coating device to obtain a wet electrode sheet strip. The electrode sheet strip enters an infrared drying system for drying, and the dried electrode sheet strip enters a receiving device for receiving processing.

[0043] According to another aspect of the present invention, the present invention also relates to an infrared drying method for electrode sheet coating, using the above-mentioned infrared drying system, comprising the following steps:

[0044] The wet electrode sheet strip that has completed coating enters the infrared drying system and operates under the action of the supporting device. The first infrared device of the first drying section performs the first infrared drying on the upper surface of the wet electrode sheet strip, and the second infrared device of the second drying section performs the second infrared drying on the lower surface of the wet electrode sheet strip. At the same time, the air inlet section transports dry air to the first drying air chamber and the second drying air chamber, performs the first blowing treatment through the first air outlet, and performs the second blowing treatment through the second air outlet. The exhaust section discharges the saturated moisture generated by the first infrared drying and the second infrared drying to the outside of the drying box to obtain the dried electrode sheet strip.

[0045] The method of the present invention performs infrared drying and blowing treatment on the upper and lower surfaces of the wet electrode sheet material strip through the first drying section and the second drying section, and infrared irradiation removes moisture in the wet film sheet, so that the moisture in the film sheet evaporates and vaporizes, and the blowing treatment blows away the evaporated and vaporized gas, so that the wet electrode sheet material strip is fully dried and a high-quality coating is formed, thereby improving the mechanical properties of the coating.

[0046] In some embodiments, the peeling force of the dried electrode sheet material is 250-280 N / m, and the moisture content is 250-330 ppm. The dried electrode sheet material obtained by the method of the present invention has a reduced moisture content and good adhesion performance of the coating.

[0047] In some embodiments, the wet electrode sheet strip includes a current collector and a material layer located on the surface of the current collector. The material layer includes, by mass percentage: 94% to 96.5% artificial graphite, 0.8% to 2% styrene-butadiene rubber (SBR), 0.5% to 1.5% conductive carbon black, 0.8% to 1.5% CMC glue, and 0.5% to 1% N-methylpyrrolidone (NMP).

[0048] The following is further explained in conjunction with specific embodiments and comparative examples.

[0049] Example 1

[0050] An infrared drying system for electrode sheet coating, comprising 12 drying units, each of which is sequentially connected and arranged along the running direction of a wet electrode sheet material belt 7; each drying unit is provided with a feed port and a discharge port; each drying unit comprises a drying box 1 and a first drying section, a second drying section and an electrode sheet material belt supporting device 4 arranged inside the drying box 1; the first drying section and the second drying section are arranged oppositely; the supporting device 4 is located between the first drying section and the second drying section, and is used to support the wet electrode sheet material belt 7 and enable it to run; the drying box 1 is provided with an air inlet 8 and an air exhaust 9;

[0051] The first drying section includes a first drying air chamber 2, which is provided with a plurality of first infrared devices 3 and first air outlets 10 matched therewith along the running direction of the wet electrode sheet material belt 7; the second drying section includes a second drying air chamber 5, which is provided with a plurality of second infrared devices 6 and second air outlets 11 matched therewith along the running direction of the wet electrode sheet material belt 7. The number of the first infrared devices 3 in each first drying air chamber 2 is 7; the number of the second infrared devices 6 in each second drying air chamber 5 is 7.

[0052] The air inlet 8 includes an air inlet and an air inlet device arranged on the drying box body 1, and the air inlet is connected to the first drying air chamber 2 and the second drying air chamber 5 through pipelines respectively; the air exhaust part 9 includes an air exhaust port and an air exhaust device arranged on the drying box body 1.

[0053] The supporting device 4 includes a plurality of supporting rollers, which are arranged in sequence along the running direction of the wet electrode sheet material belt 7 .

[0054] An infrared drying method for an electrode sheet coating comprises the following steps:

[0055] The coated wet electrode sheet strip 7 enters the infrared drying system and operates under the action of the supporting device 4. The first infrared device 3 of the first drying section performs the first infrared drying on the upper surface of the wet electrode sheet strip 7, and the second infrared device 6 of the second drying section performs the second infrared drying on the lower surface of the wet electrode sheet strip 7. At the same time, the air inlet 8 transports dry air to the first drying air chamber 2 and the second drying air chamber 5, performs the first blowing treatment through the first air outlet 10, and performs the second blowing treatment through the second air outlet 11. The exhaust part 9 discharges the saturated moisture generated by the first infrared drying and the second infrared drying to the outside of the drying box 1.

[0056] The running speed of the wet electrode sheet belt 7 is 80 m / min.

[0057] The material layer on the surface of the wet electrode sheet strip includes, by mass percentage: 96.1% artificial graphite (material code MAN0133), 1.8% styrene-butadiene rubber (material code BD0083), 1% conductive carbon black (material code MCD0052), 1.1% CMC glue (material code BASL00001), and 0.8% NMP (material code MCD000180).

[0058] The drying conditions in this embodiment are shown in Table 1.

[0059] Table 1 Drying conditions in Example 1

[0060]

[0061] Example 2

[0062] An infrared drying method for an electrode sheet coating comprises the following steps:

[0063] The coated wet electrode sheet strip 7 enters the infrared drying system and operates under the action of the supporting device 4. The first infrared device 3 of the first drying section performs the first infrared drying on the upper surface of the wet electrode sheet strip 7, and the second infrared device 6 of the second drying section performs the second infrared drying on the lower surface of the wet electrode sheet strip 7. At the same time, the air inlet 8 transports dry air to the first drying air chamber 2 and the second drying air chamber 5, performs the first blowing treatment through the first air outlet 10, and performs the second blowing treatment through the second air outlet 11. The exhaust part 9 discharges the saturated moisture generated by the first infrared drying and the second infrared drying to the outside of the drying box 1.

[0064] The running speed of the wet electrode sheet belt 7 is 80 m / min.

[0065] The material layer on the surface of the wet electrode sheet strip includes, by mass percentage: 96.1% artificial graphite (material code MAN0133), 1.8% styrene-butadiene rubber (material code BD0083), 1% conductive carbon black (material code MCD0052), 1.1% CMC glue (material code BASL00001), and 0.8% NMP (material code MCD000180).

[0066] The drying conditions in this embodiment are shown in Table 2.

[0067] Table 2 Drying conditions in Example 3

[0068]

[0069]

[0070] Example 3

[0071] A method for drying an electrode sheet coating, which differs from Example 1 in that:

[0072] The coating rate was 60 m / min.

[0073] Example 4

[0074] A method for drying an electrode sheet coating, which differs from Example 1 in that:

[0075] The coating rate was 90 m / min.

[0076] Comparative Example 1

[0077] A method for drying an electrode sheet coating comprises the following steps:

[0078] Hot air drying is adopted, and the coating speed is 60m / min.

[0079] Experimental example

[0080] The performance of the electrode sheet coatings after drying in each embodiment and comparative example was tested, as shown in Table 3 below.

[0081] 1. Moisture test

[0082] Measuring instrument: Karl Fischer moisture tester.

[0083] Sampling standard: The infrared baked electrode is sampled using a 2.5 cm diameter punch sampler.

[0084] Test method: Put the sampled electrode into a glass bottle and insert the test head into the bottle mouth to seal it.

[0085] Test conditions: heating temperature 150℃, heating time 10min.

[0086] Test results: based on the data displayed by the Karl Fischer tester after the test is completed.

[0087] Test standard: QS-2001-SVOLT-18001 quality control enterprise standard.

[0088] 2. Peel force test

[0089] Sample pretreatment: (1) Tear off a 3M "tape" with a length of ≥100mm, and stick it flatly on the test electrode sample along the slurry coating direction. Manually peel off about 5mm of the electrode to separate it into two parts: foil and membrane surface (tape adhesion). The test speed is 300mm / min; (2) Fold the reserved tape in half (the adhesive surfaces of the tape are stuck together). After the tape is adhered, use a pressure wheel to roll it 5 times to make the attached tape and test sample flat; (3) Use ceramic scissors to remove excess material on both sides of the tape.

[0090] Test steps: (1) First, clamp the steel plate with the test electrode onto the fixture, clamp the fixtures on both sides, and keep the sample taut through the control panel of the test equipment; (2) Adjust the speed to 300 mm / min for testing.

[0091] Table 3 Performance test results

[0092]

[0093]

[0094] As shown in Table 1, the electrode sheet coating obtained by the infrared drying method of Examples 1 to 2 of the present invention has a qualified appearance, high peeling force, appropriate moisture content, and the speed increase ratio and peeling force increase ratio meet the requirements. The speed increase ratio of the infrared drying method in Example 3 is 0. Although the speed increase ratio of the infrared drying method in Example 4 is high, the peeling force is relatively reduced.

[0095] The electrode sheet coating obtained by the method of Comparative Example 1 had cracks on its surface, relatively low peeling force, and high moisture content.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An infrared drying system for electrode sheet coating, characterized in that: It comprises at least one drying unit, each of which comprises a drying box body and a first drying part, a second drying part and an electrode sheet material strip supporting device arranged inside the drying box body; the first drying part and the second drying part are arranged opposite to each other; the supporting device is located between the first drying part and the second drying part, and is used to support the wet electrode sheet material strip and enable it to run; the drying box body is provided with an air inlet part and an air exhaust part; The first drying section comprises a first drying air chamber, wherein the first drying air chamber is provided with a plurality of first infrared devices and first air outlets matched therewith along the running direction of the wet electrode sheet material belt; The second drying section comprises a second drying air chamber, and the second drying air chamber is provided with a plurality of second infrared devices and second air outlets matched therewith along the running direction of the wet electrode sheet material belt; The air inlet is connected to the first drying air chamber and the second drying air chamber respectively.

2. The infrared drying system for electrode sheet coating according to claim 1, characterized in that: Contains at least one of the following features (1) to (2): (1) The running speed of the wet electrode sheet is 75-85 m / min; (2) The air inlet temperature of the air inlet part in the first drying air chamber is set to 90-103°C, the power opening of the first infrared device is 45%-60%, and the fan frequency of the first infrared device is 35-45Hz; the air inlet temperature of the air inlet part in the second drying air chamber is set to 86-93°C, the power opening of the second infrared device is 45%-95%, and the fan frequency of the second infrared device is 35-45Hz; the exhaust frequency of the exhaust device is 22-27Hz.

3. The infrared drying system for electrode sheet coating according to claim 2, characterized in that: A plurality of drying units are sequentially connected and arranged along the running direction of the wet electrode sheet strip; Each of the drying units is provided with a feed inlet and a discharge outlet.

4. The infrared drying system for electrode sheet coating according to claim 2, characterized in that: The number of the drying units is 11 to 14.

5. The infrared drying system for electrode sheet coating according to claim 1, characterized in that: The first infrared device and the first air outlet are fixed and connected as one body through a first lamp bracket, and the first lamp bracket is connected to the first drying air chamber; The second infrared device and the second air outlet are fixed and connected as one body through a second lamp tube bracket, and the second lamp tube bracket is connected to the second drying air chamber.

6. The infrared drying system for electrode sheet coating according to claim 1, characterized in that: The number of the first infrared devices in each of the first drying air chambers is 6 to 9; The number of the second infrared devices in each of the second drying air chambers is 6 to 9.

7. The infrared drying system for electrode sheet coating according to claim 1, characterized in that: The air inlet portion includes an air inlet and an air inlet device arranged on the drying box body; The exhaust part comprises an exhaust port and an exhaust device arranged on the drying box body.

8. The infrared drying system for electrode sheet coating according to claim 1, characterized in that: The supporting device comprises a plurality of supporting rollers, and the supporting rollers are arranged in sequence along the running direction of the wet electrode sheet material belt.

9. An infrared drying method for electrode sheet coating, characterized in that: The infrared drying system according to any one of claims 1 to 8 comprises the following steps: The wet electrode sheet strip that has completed coating enters the infrared drying system and operates under the action of the supporting device. The first infrared device of the first drying section performs the first infrared drying on the upper surface of the wet electrode sheet strip, and the second infrared device of the second drying section performs the second infrared drying on the lower surface of the wet electrode sheet strip. At the same time, the air inlet section transports dry air to the first drying air chamber and the second drying air chamber, performs the first blowing treatment through the first air outlet, and performs the second blowing treatment through the second air outlet. The exhaust section discharges the saturated moisture generated by the first infrared drying and the second infrared drying to the outside of the drying box to obtain the dried electrode sheet strip.

10. The infrared drying method for electrode sheet coating according to claim 9, characterized in that: The peeling force of the electrode sheet material strip after drying is 250-280 N / m, and the moisture content is 250-330 ppm.

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