Gas prevention sodium-ion battery pouch cell manufacturing process

Abstract

The application discloses a kind of processes for manufacturing sodium-ion battery soft package battery cell to prevent gas swelling;Belongs to sodium-ion battery manufacturing process;Its process includes: (1) the treatment of positive and negative electrodes;After slurry preparation and coating, the positive and negative electrode sheets are obtained, and then baked in a vacuum heating oven, then rolled, die cut, and the electrode sheet is baked after slicing;(2) welding and packaging: the positive and negative electrode sheets are stacked and welded with tabs to form a bare battery cell, and the bare battery cell is packaged in an aluminum-plastic film;The packaged battery cell is baked after being pasted with a bar code, vacuum injection, edge sealing, battery formation, pumping, and the battery cell is stored after being separated and stored;The battery cell is tightly assembled before storage to obtain a sodium-ion battery soft package battery cell;All processes before packaging are carried out in a dew point room.The sodium-ion battery soft package battery cell manufacturing process can better prevent the battery cell from swelling and improve the service life of the battery cell.

Description

Manufacturing process for sodium-ion battery pouch cells to prevent gas buildup Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, specifically relating to a manufacturing process for sodium-ion battery pouch cells that prevents gas expansion. Background Technology

[0002] Currently, the mass production of sodium-ion batteries has begun, with sodium and lithium batteries developing in tandem, complementing and reinforcing each other, and potentially becoming a future trend in new energy applications. Sodium-ion batteries are currently used in electric bicycles, boasting a significantly higher energy density than lead-acid batteries and a price advantage over lithium batteries. For users prioritizing cost-effectiveness, the application prospects of sodium-ion batteries in electric bicycles are very broad, with enormous development potential.

[0003] As sodium-ion battery technology matures, manufacturing processes are increasingly moving away from lithium-ion batteries, leading to more independent innovations. With the accumulation of test data for pouch cells, the problem of gas buildup has become a common challenge in the sodium battery industry. Some pouch cells in the same batch can cycle for 2000 cycles, while others develop gas after only 200 cycles, severely limiting their lifespan. Reported data indicates that sodium battery technology has reached high-performance requirements; however, mass production of sodium batteries is still in its early stages and cannot yet fully control the potential gas buildup problem in every cell. Therefore, developing a sodium-ion battery cell manufacturing process suitable for mass production and preventing gas buildup is urgently needed. Summary of the Invention

[0004] In order to solve the technical problems mentioned in the prior art, the purpose of this invention is to provide a sodium-ion battery cell manufacturing process that is suitable for mass production of soft-pack batteries and prevents gas expansion.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A manufacturing process for sodium-ion battery pouch cells to prevent gas expansion, the process comprising:

[0007] (1) Processing of positive and negative electrodes: positive and negative electrode sheets are prepared by pulping and coating, then baked, then rolled, die-cut, sliced ​​and baked;

[0008] (2) Welding and Packaging: The positive and negative electrode sheets are stacked and welded to the tabs to form a bare cell. The bare cell is packaged in an aluminum-plastic film. After packaging, the cell is labeled with a barcode and then baked, vacuum-filled, and edge-sealed. The cell is then formed, evacuated, and before storage after capacity testing, the cell is tightly assembled to obtain a sodium-ion battery soft-pack cell.

[0009] All processes prior to packaging are performed in a dew point room;

[0010] The baking process parameters for the above-mentioned positive electrode sheet are set as follows: temperature 130-150℃, specifically preferably 130℃, 131℃, 132℃, 133℃, 134℃, 135℃, 136℃, 137℃, 138℃, 139℃, 140℃, 141℃, 142℃, 143℃, 144℃, 145℃, 146℃, 147℃, 148℃, 149℃, and 150℃; vacuum degree -100kPa to -85kPa, specifically preferably -100kPa, -99kPa, -98kPa, -97kPa, -96kPa, and -95kPa. The vacuum pressure is -94 kPa, -93 kPa, -92 kPa, -91 kPa, -90 kPa, -89 kPa, -88 kPa, -87 kPa, -86 kPa, and -85 kPa; the vacuum time is 130-170 min, preferably 130 min, 135 min, 140 min, 145 min, 150 min, 155 min, 160 min, 165 min, and 170 min; the drying time is 25-45 min; the number of cycles is 3-6, preferably 3, 4, 5, and 6; and the total time is 10-14 hours. Using the sodium-ion battery soft-pack cell manufacturing process of this invention, each cell generally avoids gas expansion, thereby preventing the loosening or shedding of active materials caused by gas expansion, shortening battery life, increasing the service life of each cell, and improving the consistency of cell performance.

[0011] According to another aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the water content of the positive electrode sheet does not exceed 100 ppm.

[0012] According to one aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the baking process parameters for the negative electrode sheet are set as follows: temperature is 120-140℃, specifically preferably 120℃, 121℃, 122℃, 123℃, 124℃, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, 133℃, 134℃, 135℃, 136℃, 137℃, 138℃, 139℃, or 140℃; vacuum degree is -100kPa to -85kPa, specifically preferably -100kPa, -99kPa, -98kPa, -97kPa, or -95kPa. The vacuum pressure is 6 kPa, -95 kPa, -94 kPa, -93 kPa, -92 kPa, -91 kPa, -90 kPa, -89 kPa, -88 kPa, -87 kPa, -86 kPa, and -85 kPa; the vacuum time is 120-160 min, preferably 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, 150 min, 155 min, and 160 min; the drying time is 25-45 min; the number of cycles is 3-6, preferably 3, 4, 5, and 6; and the total drying time is 10-14 h.

[0013] According to another aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the water content of the negative electrode sheet does not exceed 300 ppm.

[0014] According to one aspect of the sodium-ion battery pouch cell manufacturing process of the present invention, the operating temperature of the dew point chamber is 20-30°C, and the dew point is higher than -30°C.

[0015] According to one aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the rolling speed of the positive electrode sheet is 0.1-5 m / min; specifically preferably 0.1 m / min, 0.15 m / min, 0.2 m / min, 0.25 m / min, 0.3 m / min, 0.35 m / min, 0.4 m / min, 0.45 m / min, 0.5 m / min, 0.55 m / min, 0.6 m / min, 0.65 m / min, 0.75 m / min, 0.8 m / min, 0.85 m / min, 0.9 m / min, 1 m / min, 1.5 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min, and 5 m / min.

[0016] According to one aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the rolling speed of the negative electrode sheet is 0.1-5 m / min; specifically preferred are 0.1 m / min, 0.15 m / min, 0.2 m / min, 0.25 m / min, 0.3 m / min, 0.35 m / min, 0.4 m / min, 0.45 m / min, 0.5 m / min, 0.55 m / min, 0.6 m / min, 0.65 m / min, 0.75 m / min, 0.8 m / min, 0.85 m / min, 0.9 m / min, 1 m / min, 1.5 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, 4 m / min, 4.5 m / min, and 5 m / min.

[0017] According to one aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, when welding the tabs, the exposed height of the tab adhesive is 1.5-2.0 mm.

[0018] According to one aspect of the manufacturing process of sodium-ion battery soft-pack cells of the present invention, the pitting depth of the aluminum-plastic film is: the thickness of the bare cell × 1 / 2 - a; where a is 0.5 mm to 1 mm.

[0019] According to one aspect of the sodium-ion battery pouch cell manufacturing process of the present invention, the packaged cell is baked after being labeled with a barcode, wherein the baking parameters are set as follows: temperature is 75-90℃, specifically preferably 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, or 90℃; vacuum degree is -100kPa to -85kPa, specifically preferably -100kPa, -99kPa, -98kPa, -97kPa, -96kPa, -95kPa, or -94kPa. Pa, -93kPa, -92kPa, -91kPa, -90kPa, -89kPa, -88kPa, -87kPa, -86kPa, -85kPa; vacuum time is 120-160min, preferably 120min, 125min, 130min, 135min, 140min, 145min, 150min, 155min, 160min; drying time is 25-45min; number of cycles is 3-6, preferably 3, 4, 5, 6; time is 10-14h.

[0020] According to one aspect of the sodium-ion battery pouch cell manufacturing process of the present invention, the cell formation heating temperature is 30-35°C and the pressure is 1500-1600 kgf.

[0021] According to one aspect of the sodium-ion battery soft-pack cell manufacturing process of the present invention, the process parameters for cell formation are set as follows: mainly divided into 3 steps, first charging at 0.1-0.2C for 1-2 hours, then charging at 0.15-0.25C for 1-2 hours, and then charging at 0.2-0.3C to 4V voltage, followed by resting to complete the process.

[0022] According to one aspect of the manufacturing process of sodium-ion battery pouch cells of the present invention, the parameters for evacuation are set as follows: vacuum degree of -100kPa to -85kPa, and time of 20-40s.

[0023] According to one aspect of the sodium-ion battery soft-pack cell manufacturing process of the present invention, the steps of the tight assembly operation are as follows: prepare an empty groove with its upper, lower and front sides open, the rear panel is attached to the cell, the left and right sides embrace the cell and open the groove, and the front panel passes through the groove from bottom to top and is attached to the cell. Through this snap-fit ​​connection method, the tight assembly of each cell is achieved.

[0024] According to another aspect of the sodium-ion battery soft-pack cell manufacturing process of the present invention, a slot for tight assembly of the cell is realized. The material can be ABS, PP, or other tough materials. The thickness of the front and rear panels is 0.5-2mm. The grooves on the left and right sides are located in the recesses on both sides of the cell, without occupying additional space in the electrode group thickness direction.

[0025] The beneficial effects of this invention in the process of preparing sodium-ion battery pouch cells are as follows:

[0026] (1) The reasonable baking process ensures that the moisture content of the battery cell does not exceed the standard, and will not cause the electrolyte to decompose prematurely and generate gas; the battery cell packaging quality is guaranteed, and will not cause damage to the aluminum-plastic film due to the packaging process, so that water vapor enters the battery cell and damages it; the reasonable rolling process makes the electrode thickness rebound stress small, and prevents the assembly loosening caused by the thickness deformation of the electrode.

[0027] (2) Reasonable formation and degassing processes ensure complete gas generation and thorough degassing of the battery cell, and the SEI film is stable and will not decompose and generate gas during its lifespan.

[0028] (3) Appropriate rolling of the battery cell ensures that the surface of the battery cell is flat and wrinkle-free. Combined with tight assembly process, it ensures that the battery cell will not bulge during its lifespan.

[0029] Through the above manufacturing process, this invention generally avoids gas expansion in each battery cell, thereby preventing the loosening or shedding of active materials caused by gas expansion, shortening battery life, increasing the service life of each battery cell, and improving the consistency of battery cell performance. Attached Figure Description

[0030] Figure 1 shows the packaged appearance of a sodium-ion battery pouch cell;

[0031] Figure 2 is a schematic diagram of the tight assembly operation of a sodium-ion battery soft-pack cell;

[0032] Figure 3 is a comparison of the cycling performance of sodium-ion battery pouch cells in Examples 1, 2 and 3. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Experimental methods not specifically described in the embodiments are all conventional methods in the prior art; those without specific conditions are performed according to conventional conditions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0034] This invention also specifically provides a manufacturing process for sodium-ion battery pouch cells to prevent gas expansion, the process comprising:

[0035] The operating temperature of the dew point room is 20-30℃, and the dew point is above -30℃.

[0036] (1) Processing of positive and negative electrodes: Positive and negative electrode rolls are obtained by pulping and coating, and then placed in a vacuum heating oven for baking; the moisture content of the electrode rolls is tested and the content is not more than 1000ppm before rolling. The rolling speed of the electrode rolls is set to 0.1-5m / min; after rolling, the electrode rolls are die-cut and then baked; the baking process parameters of the positive electrode are set as follows: temperature is 130-150℃, vacuum degree is -100kPa to -85kPa, vacuum time is 130-170min, drying time is 25-45min, number of cycles is 3-6, and time is 10-14h; the baking process parameters of the negative electrode are set as follows: temperature is 120-140℃, vacuum degree is -100kPa to -85kPa, vacuum time is 120-160min, drying time is 25-45min, number of cycles is 3-6, and time is 10-14h.

[0037] (2) Welding and Packaging: After the electrode moisture content is tested and found to be qualified, the electrodes are stacked and the tabs are welded; the bare cells are top-side sealed, with the top sealing temperature being 180-220℃ and the side sealing temperature being 170-200℃; the tab adhesive protrusion height is 1.8mm, and the appearance of the cell after packaging is shown in Figure 1; the depth of the aluminum-plastic film punching is half the thickness of the bare cell minus 0.5-1mm; after packaging, the cell is labeled with a barcode and then baked, with the baking parameters set as follows: temperature 75-90℃, vacuum degree -100kPa to -85kPa, vacuum time 120-160min, drying time 25-45min, and total time 10-14h; the moisture content of the positive and negative electrodes does not exceed 100ppm and 300ppm respectively, and vacuum liquid injection and one-time edge sealing are performed; after high-temperature wetting, the cells are formed and heated to 30-35℃ and pressurized to 150℃. The process involves multi-step low-current formation at 0-1600 kgf followed by high-temperature resting to ensure complete gas generation and SEI film stability. The formation process parameters are set in three main steps: first, charging at 0.1-0.2C for 1-2 hours, then charging at 0.15-0.25C for 1-2 hours, followed by charging at 0.2-0.3C to 4V, and then resting. Before evacuation, the cells are flattened twice using forward and reverse rollers. The actual vacuum level during evacuation is -100 to -100 kPa, and the time is 20-40 seconds to ensure thorough evacuation. After evacuation, the cells are sealed twice. Then, capacity testing is performed. Before storage after capacity testing, the cells are tightly assembled. An empty slot is prepared with its top, bottom, and front sides open. The rear panel is pressed against the cell, and the left and right sides embrace the cell and open the grooves, as shown in the upper part of Figure 2. The front panel passes through the grooves from bottom to top and is pressed against the cell, as shown in the lower part of Figure 2. This snap-fit ​​connection method enables tight assembly of each cell, with an assembly pressure of 25 kgf, thus producing a soft-pack sodium-ion battery cell.

[0038] It should be noted that the aluminum-plastic film used in this invention is a commonly used aluminum-plastic film material in the art, and its material is PE.

[0039] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings:

[0040] Example 1:

[0041] A manufacturing process for sodium-ion battery pouch cells to prevent gas expansion, the process comprising:

[0042] The dew point room operates at a temperature of 25℃±3℃, with a dew point of -25℃.

[0043] (1) Processing of positive and negative electrodes: Positive and negative electrode rolls are obtained by pulping and coating, and then placed in a vacuum heating oven for baking. The moisture content of the electrode rolls is tested and can only be rolled if the content does not exceed 1000ppm. The rolling speed of positive and negative electrodes is set to 5m / min. After rolling, the electrodes are die-cut and then baked. The baking process parameters of positive electrode are set as follows: temperature 140℃, vacuum degree -95kPa, vacuum 150min, drying 30min, cycle 4 times, for a total of 12h. The baking process parameters of negative electrode are set as follows: temperature 120℃, vacuum degree -95kPa, vacuum 120min, drying 30min, cycle 4 times, for a total of 10h.

[0044] (2) Welding and Packaging: After the electrode moisture content is tested and found to be qualified, the electrodes are stacked and the tabs are welded; the bare cells are top-side sealed, the top sealing temperature is 200℃ and the side sealing temperature is 190℃; the tab adhesive protrusion height is 1.8mm, and the appearance of the cell after packaging is shown in Figure 1; the depth of the aluminum-plastic film punching is half the thickness of the bare cell minus 0.5mm; after the packaged cells are labeled with barcodes, they are baked. The cell baking parameters are set as follows: temperature 85℃, vacuum degree -95kPa, vacuum 120min, drying 30min, cycle 4 times, for a total of 10h, the moisture content of the positive and negative electrodes does not exceed 100ppm and 300ppm respectively, and vacuum liquid injection and one-time edge sealing are performed; after high-temperature wetting, formation is carried out, and the cells are heated to 33℃ and pressurized to 1530kPa. The process involves multi-step, low-current formation followed by high-temperature resting to ensure complete gas generation and SEI film stability. The formation process parameters are set in three main steps: first, charging at 0.1C for 1 hour, then at 0.2C for 1 hour, followed by charging at 0.25C to 4V, and then resting. Before evacuation, the cells are flattened twice using forward and reverse rollers. The actual vacuum level during evacuation is -95kPa, and the time is 35s to ensure thorough evacuation. After evacuation, the cells are resealed. Then, capacity testing is performed. Before storage after capacity testing, the cells are tightly assembled. An empty slot is prepared with its top, bottom, and front sides open. The rear panel is pressed tightly against the cell, and the left and right sides embrace the cell and open the grooves, as shown in the upper part of Figure 2. The front panel passes through the grooves from bottom to top and is pressed tightly against the cell, as shown in the lower part of Figure 2. This snap-fit ​​connection method achieves tight assembly of each cell at an assembly pressure of 25kgf, resulting in a sodium-ion battery soft-pack cell.

[0045] Example 2:

[0046] A manufacturing process for a sodium-ion battery pouch cell that prevents gas buildup differs from Example 1 in that:

[0047] The production process of square aluminum-cased batteries, which follows conventional manufacturing processes, is described in "Principles and Applications of Lithium-ion Battery Manufacturing Processes": slurry preparation, coating, rolling, die cutting, stacking, tab welding, top and side sealing, baking, vacuum liquid injection, and first edge sealing; followed by high-temperature wetting, conventional formation and high-temperature resting, and a second sealing after evacuation; then capacity testing and storage.

[0048] Example 3:

[0049] A manufacturing process for a sodium-ion battery pouch cell that prevents gas buildup differs from Example 1 in that:

[0050] The operating temperature of the dew point room is 25℃±3℃, and the dew point is -20℃.

[0051] (1) Processing of positive and negative electrodes: Positive and negative electrode rolls are obtained by pulping and coating, and then placed in a vacuum heating oven for baking; the moisture content of the electrode rolls is tested and can only be rolled if the content does not exceed 1000ppm. The rolling speed of the electrode rolls is set to 4m / min; after rolling, the electrode rolls are die-cut and then baked; the baking process parameters of the positive electrode are set as follows: temperature 150℃, vacuum degree -90kPa, vacuum 150min, drying 30min, cycle 5 times, for a total of 12h; the baking process parameters of the negative electrode are set as follows: temperature 130℃, vacuum degree -90kPa, vacuum 130min, drying 30min, cycle 5 times, for a total of 10h.

[0052] (2) Welding and Packaging: After the electrode moisture content is tested and found to be qualified, the electrodes are stacked and the tabs are welded; the bare cells are top-side sealed, with the top sealing temperature being 210℃ and the side sealing temperature being 185℃; the exposed height of the tab adhesive is 2.0mm; the depth of the aluminum-plastic film pitting is half the thickness of the bare cell minus 0.5mm; after the packaged cells are labeled with barcodes, they are baked, and the baking parameters are set as follows: temperature 85℃, vacuum degree -95kPa, vacuum 120min, drying 30min, cycle 4 times, for a total of 10h, the moisture content of the positive and negative electrodes does not exceed 100ppm and 300ppm respectively, and vacuum liquid injection and one-time edge sealing are performed; after high-temperature wetting, the cells are formed and heated to 35℃ and pressurized to 1530kgf. The process involves low-current formation followed by high-temperature resting to ensure complete gas generation and SEI film stability. The formation process parameters are set in three main steps: first, charging at 0.15C for 1 hour, then at 0.2C for 1 hour, followed by charging at 0.25C to 4V, and then resting. Before evacuation, the cells are flattened twice using forward and reverse rollers. The evacuation process achieves an actual vacuum of 100kPa for 25 seconds to ensure thorough evacuation. After evacuation, the cells are resealed. Then, capacity testing is performed. Before storage after capacity testing, the cells are tightly assembled using a slot similar to a mobile phone case, with the top, bottom, and front sides open. The back panel is pressed against the cell, and the left and right sides embrace the cell and open their grooves. The front panel passes through the grooves from bottom to top and is pressed tightly against the cell. This snap-fit ​​connection method achieves tight assembly of each cell at a pressure of 25kgf.

[0053] Example 4:

[0054] A manufacturing process for a sodium-ion battery pouch cell that prevents gas buildup differs from Example 1 in that:

[0055] (1) Processing of positive and negative electrodes: Positive and negative electrode rolls are prepared by pulping and coating, and then placed in a vacuum heating oven for baking; the moisture content of the electrode rolls is tested and can only be rolled if the content does not exceed 1000ppm. The rolling speed of the electrode rolls is set to 8m / min; after rolling, the electrode rolls are die-cut and then baked; the baking process parameters of the positive electrode are set as follows: temperature 160℃, vacuum degree -80kPa, vacuum 120min, drying 20min, cycle 7 times, for a total of 15h; the baking process parameters of the negative electrode are set as follows: temperature 110℃, vacuum degree -80kPa, vacuum 110min, drying 20min, cycle 7 times, for a total of 8h.

[0056] Example 5:

[0057] A manufacturing process for a sodium-ion battery pouch cell that prevents gas buildup differs from Example 1 in that:

[0058] (2) Welding and Packaging: After the electrode moisture content is tested and found to be qualified, the electrodes are stacked and the tabs are welded; the bare cells are top-side sealed, with a top sealing temperature of 240℃ and a side sealing temperature of 210℃; the exposed height of the tab adhesive is 1.8mm; the depth of the aluminum-plastic film indentation is half the thickness of the bare cell minus 0.5mm; after the packaged cells are labeled with barcodes, they are baked. The baking parameters are set as follows: temperature 95℃, vacuum degree -80kPa, vacuum 150min, drying 50min, cycle 8 times, for a total of 15h. The moisture content of the positive and negative electrodes does not exceed 100ppm and 300ppm respectively. Vacuum liquid injection and one-time edge sealing are performed; after high-temperature wetting, formation is carried out. The process involves a multi-step, low-current formation process at 40°C and 1530 kgf, followed by high-temperature resting to ensure complete gas generation and SEI film stability. The formation process includes: charging to 4V at 0.2C, followed by resting; flattening with rollers twice (positive and negative) before evacuation; achieving a vacuum of -80 kPa for 45 seconds to ensure thorough evacuation; double sealing after evacuation; and then capacity testing. Before storage, the cells are tightly assembled using an open slot (top, bottom, and front). The rear panel is pressed against the cell, while the left and right panels embrace the cell and open their grooves. The front panel passes through the grooves from bottom to top and is pressed against the cell. This snap-fit ​​connection method achieves tight assembly of each cell at a pressure of 25 kgf, resulting in a sodium-ion battery pouch cell.

[0059] In order to further improve the anti-gas-expansion performance of sodium-ion battery soft-pack cells, the present invention modifies the surface of the aluminum-plastic film used. The preferred measures also include: using a modified coating liquid to modify the surface of the aluminum-plastic film, which may be able to absorb excess water and prevent water from entering the electrolyte and causing the electrolyte to decompose and generate gas. On the other hand, it can protect the aluminum-plastic film from corrosion, thereby preventing it from losing its water barrier function and thus causing gas expansion.

[0060] It should be noted that the main components of the modified coating solution include: organosilicon resin, organosiloxane, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester and solvent.

[0061] It should be noted that the weight ratio of organosilicon resin, organosiloxane, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester and solvent in the modified coating solution is 1-4:0.5-2.5:0.25-1.5:75-85.

[0062] It should be noted that the silicone resin is selected from polymethyl silicone resin or polyethyl silicone resin.

[0063] It should be noted that the organosiloxane is selected from dopamine-modified polysiloxane, which is prepared by conventional experimental methods in the existing technology (see: Han Rui. Preparation and performance study of dopamine-modified polysiloxane [D]. Shandong University, 2022).

[0064] The coating amount of the modified coating solution is 5-15 g / m². 2 .

[0065] The surface modification method for aluminum-plastic film is as follows: the modified coating liquid is evenly coated on the surface of the aluminum-plastic film and dried in an oven at 75-95℃ for 4-8 hours to obtain the surface-modified aluminum-plastic film.

[0066] Example 6:

[0067] A manufacturing process for sodium-ion battery pouch cells that prevents gas expansion differs from Example 1 in that the aluminum-plastic film in this example undergoes surface modification. The specific modification steps are as follows:

[0068] A modified coating solution was prepared by uniformly mixing polyethyl silicone resin, dopamine-modified polysiloxane, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester and ethanol in a weight ratio of 2:1.5:1:80.

[0069] The modified coating solution was evenly coated on the surface of the aluminum-plastic film and dried in an oven at 85°C for 6 hours to obtain a surface-modified aluminum-plastic film.

[0070] Example 7:

[0071] A manufacturing process for a sodium-ion battery soft-pack cell that prevents gas expansion differs from Example 6 in that the weight ratio of polyethyl silicone resin, dopamine-modified polysiloxane, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester and ethanol in the modified coating solution is 4:1:1.5:85.

[0072] Example 8:

[0073] A manufacturing process for a sodium-ion battery soft-pack cell that prevents gas expansion, differing from Example 6 in that N-(2,3-dihydroxypropyl)carbamate tert-butyl ester is not added to the modified coating solution.

[0074]

Experimental Example 1

[0075] Battery cells manufactured according to the manufacturing processes of Embodiments 1 and 3 of this invention, and battery cells manufactured according to the conventional process of Embodiment 2, were assembled into a 48V, 24Ah battery according to conventional dimensions and subjected to a 1C cycle test. The test method was as follows: after resting for 30 minutes, the battery was discharged at a constant current of 1C to 24V, then rested for 30 minutes, charged at 0.5C to 57V, and then charged at a constant voltage to a current of 0.05C. This cycle was repeated. The results of the cycle test are shown in Figure 3.

[0076] As can be seen from the comparison of the cycle test results in Figure 3, the cycle curve of the tightly assembled battery cells is stable and less prone to sudden and sharp decline. The tightly assembled cell process in Example 1 can ensure that the lifespan of each cell does not fail prematurely, improving battery life and cell consistency. Before the development of high-tech electrolytes that do not decompose and swell, this tightly assembled method is a relatively effective approach for soft-pack cells, achieving the safety, stability, and high-performance technical requirements of sodium-ion batteries, thereby meeting customers' urgent need for cost-effective and lightweight electric bicycle batteries.

[0077] The sodium-ion battery pouch cells from Examples 4 to 8 were tested again using the above testing method. The capacity retention rate of the sodium-ion battery pouch cells was measured after 600 cycles. The test results are shown in Table 1.

[0078] Table 1 Initial capacity retention rate of sodium-ion battery pouch cells

[0079]

[0080] As can be seen from Table 1, after 600 cycles, the initial capacity retention rate of the sodium-ion battery pouch cells in Examples 1 and 3 is still higher than 85%. Comparing Examples 1 with Examples 4 and 5, the initial capacity retention rate in Example 1 is higher than that in Examples 4 and 5. This indicates that the present invention, by employing reasonable rolling process, reasonable baking process, reasonable formation process, and tight assembly operation, can obtain high-performance sodium-ion battery pouch cells, ensuring that the cells will not swell during their lifespan and improving the service life of each cell.

[0081] Table 1 also shows that after 600 cycles, the initial capacity retention rate of the sodium-ion battery pouch cells in Examples 6 and 7 is still higher than 93%. Compared with Examples 1, 6, 7 and 8, the initial capacity retention rate of Examples 6 and 7 is higher than that of Examples 1 and 8. This indicates that surface modification of the aluminum-plastic film using a modified coating solution, and the addition of N-(2,3-dihydroxypropyl)carbamate tert-butyl ester to the modified coating solution, can further improve the anti-gas swelling performance of the sodium-ion battery pouch cells, giving them excellent charge and discharge performance.

[0082]

Experimental Example 2

[0083] Performance Study of Aluminum-Plastic Film Before and After Surface Modification

[0084] I. Barrier performance

[0085] The surface-modified aluminum-plastic film samples from Examples 6 (group a), 7 (group c), and 8 (group d) were made into bags, injected with electrolyte and sealed, and then soaked in water at 50°C for 10 days to test the moisture content in the electrolyte.

[0086] Table 2 Barrier properties of aluminum-plastic film

[0087]

[0088] As shown in Table 2, the moisture content in the electrolyte of Example Group b, Experimental Group c, and Experimental Group d is lower than that of Example Group a (unmodified aluminum-plastic film). Furthermore, the moisture content in the electrolyte of Example b and Experimental Group c is lower than that of Experimental Group d. This indicates that surface treatment of aluminum-plastic film with modified coating solution can improve the barrier performance of aluminum-plastic film. At the same time, the addition of N-(2,3-dihydroxypropyl)carbamate tert-butyl ester to the modified coating solution significantly improves the barrier performance of aluminum-plastic film.

[0089] II. Abrasion Resistance

[0090] The surface-modified aluminum-plastic film samples (cut to a width of 12 mm) from the unmodified aluminum-plastic film (referred to as experimental group a), Example 6 (referred to as experimental group b), Example 7 (referred to as experimental group c), and Example 8 (referred to as experimental group d) were immersed in an electrolyte at a temperature of 70°C for 10 days. The interlayer peel strength of the aluminum-plastic film was tested at a peel angle of 180° and a peel speed of 125 mm / min.

[0091] Table 3. Interlayer peel strength of aluminum-plastic film

[0092]

[0093] As shown in Table 3, the interlayer peel strength of the aluminum-plastic film in Example Group b, Experimental Group c, and Experimental Group d is higher than 10 N / 15 mm, which is higher than that in Example Group a (aluminum-plastic film without surface modification). Furthermore, the interlayer peel strength of the aluminum-plastic film in Example b and Experimental Group c is higher than that in Experimental Group d. This indicates that surface treatment of the aluminum-plastic film with a modified coating solution can improve its barrier properties. At the same time, the addition of N-(2,3-dihydroxypropyl)carbamate tert-butyl ester to the modified coating solution further improves the mechanical properties of the aluminum-plastic film, giving it excellent corrosion resistance and thus extending its service life.

[0094]

Experimental Example 3

[0095] High-temperature stability performance of sodium-ion battery pouch cells

[0096] The sodium-ion battery pouch cells prepared in Examples 1-8 were stored at 75°C for 8 days to observe whether the sodium-ion battery pouch cells would swell.

[0097] Table 4 High-temperature stability of sodium-ion battery pouch cells

[0098]

[0099] As can be seen from Table 4, the sodium-ion battery pouch cells in Examples 1 and 3 did not swell after being stored at 75°C for 8 days, while the sodium-ion battery pouch cells in Examples 4 and 5 did swell. This indicates that by using reasonable rolling processes, reasonable baking processes, reasonable formation processes, and tight assembly operations, the present invention can obtain sodium-ion battery pouch cells with excellent performance and improve the service life of each cell.

[0100] It is understood that the above detailed description of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effects; as long as the usage requirements are met, they are all within the protection scope of the present invention.

Claims

1. A manufacturing process for sodium-ion battery pouch cells to prevent gas expansion, the process comprising: (1) Processing of positive and negative electrodes: positive and negative electrode sheets are prepared by pulping and coating, baked, then rolled, die-cut, sliced ​​and baked; (2) Welding and encapsulation: positive and negative electrode sheets are stacked and welded with tabs to form bare cells. The bare cells are encapsulated in aluminum-plastic film. After the cells are encapsulated, they are baked, vacuum injected, sealed, formed, evacuated, and before storage after capacity testing, the cells are tightly assembled to obtain sodium-ion battery soft-pack cells; all processes before encapsulation are carried out in a dew point room; the baking of the positive electrode sheet The process parameters are set as follows: temperature 130-150℃, vacuum degree -100kPa to -85kPa, vacuum time 130-170min, drying time 25-45min, number of cycles 3-6, and total time 10-14h; the baking process parameters for the negative electrode sheet are set as follows: temperature 120-140℃, vacuum degree -100kPa to -85kPa, vacuum time 120-140min, drying time 25-45min, number of cycles 3-6, and total time 1... 0-14h; After packaging, the battery cells are affixed with barcodes and then baked. The baking parameters are set as follows: temperature 75-90℃, vacuum degree -100kPa to -85kPa, vacuum time 120-160min, drying time 25-45min, number of cycles 3-6, and time 10-14h; The battery cell formation process parameters are set as follows: mainly divided into 3 steps, first charging at 0.1-0.2C for 1-2h, then charging at 0.15-0.25C for 1-2h, and then charging at 0.2-0.3C to 4 Voltage V, resting complete; the aluminum-plastic film undergoes surface modification by applying a modified coating solution to the surface of the aluminum-plastic film. The modified coating solution comprises: organosilicon resin, dopamine-modified polysiloxane, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester, and ethanol. The weight ratio of organosilicon resin, organosilicon, N-(2,3-dihydroxypropyl)carbamate tert-butyl ester, and ethanol in the modified coating solution is 1-4:0.5-2.5:0.25-1.5:75-85; the organosilicon resin is methyl silicone resin or ethyl silicone resin.

2. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The operating temperature of the dew point room is 20-30℃, and the dew point is higher than -30℃ and lower than -20℃.

3. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The rolling speed of the positive electrode sheet is 0.1-5 m / min.

4. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The rolling speed of the negative electrode sheet is 0.1-5 m / min.

5. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The depth of the perforation in the aluminum-plastic film is: the thickness of the bare battery cell × 1 / 2 - a; where a is 0.5mm to 1mm.

6. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The parameters for the pumping are set as follows: vacuum degree from -100 kPa to -85 kPa, and time from 20 to 40 seconds.

7. The manufacturing process for a sodium-ion battery soft-pack cell to prevent gas expansion according to claim 1, characterized in that: The steps of the tight assembly operation are as follows: prepare an empty slot with its top, bottom, and front sides open, the back panel is attached to the battery cell, the left and right sides embrace the battery cell and open the groove, and the front panel passes through the groove from bottom to top and is attached to the battery cell. Through this snap-fit ​​connection method, the tight assembly of each battery cell is achieved.

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