Two-way humidity control material for lithium battery pack of new energy vehicle and preparation method and application of two-way humidity control material

Abstract

The invention relates to a bidirectional humidity control material for a lithium battery pack of a new energy vehicle as well as a preparation method and application of the bidirectional humidity control material. The preparation method comprises the following steps: firstly, carrying out polymerization reaction on sodium salt, chlorine salt and a hyperbranched hydrophilic polymer in a solvent; dip-coating a base material in the reaction mixture, and drying to obtain the moisture absorption cotton; the preparation method comprises the following steps: mixing and banburying non-vulcanized rubber, a water-absorbing polymer, a thermoplastic elastomer, a polyether ester plasticizer, stearic acid, carbon black and titanium dioxide to obtain a water-absorbing expansion polymer synthetic body; calendaring the water-swelling polymer synthesis body to obtain a water storage sheet; and finally, sequentially overlapping the microporous permeable membrane, the moisture absorption cotton, the water storage sheet, the moisture absorption cotton and the microporous permeable membrane, and carrying out hot pressing. Compared with the prior art, the humidity-controlling material prepared by the invention has the advantages that the hyperbranched hydrophilic polymer has a spatial network structure and is provided with a large number of hydrophilic groups, the super absorbent polymer has excellent porosity and has long-term moisture absorption capacity, and the water storage layer has excellent water absorption, water storage and water locking capacity.

Description

Technical Field

[0001] This invention belongs to the field of humidity-regulating materials technology, and relates to a bidirectional humidity-regulating material for lithium battery packs of new energy vehicles, its preparation method and application. Background Technology

[0002] Traditional humidity-regulating materials include natural, organic polymers, and inorganic minerals. Natural and inorganic minerals exhibit significant fluctuations in their moisture absorption and release capabilities, resulting in unsatisfactory performance. Organic polymers are complex to prepare and lack sufficient research depth, hindering large-scale application. Furthermore, existing evaluation standards for humidity-regulating materials primarily focus on moisture absorption performance, lacking effective methods for controlling the stable release of absorbed moisture. Most products experience water leakage during use, potentially leading to short circuits or even damage to electrical components. For example, in low-humidity environments, condensation can easily form on the battery packs of new energy vehicles when the vehicle is stationary or the cooling system is running, increasing the risk of electrical short circuits and potentially causing fires or explosions. Additionally, operating the battery pack in a high-temperature, dry environment at low humidity levels also increases the probability of thermal runaway.

[0003] In other words, existing humidity-regulating materials are prone to moisture leakage under long-term use, which can easily cause short circuits in electronic devices, and their effective range is limited. Therefore, how to achieve effective humidity control over long periods and distances remains a technical challenge that urgently needs to be overcome. Summary of the Invention

[0004] The purpose of this invention is to provide a bidirectional humidity regulating material for lithium battery packs of new energy vehicles that controls humidity changes and prevents condensation, as well as its preparation method and application, to solve the technical problems of existing bidirectional humidity regulating materials being unable to achieve water storage and waterproofing during long-term use, and the difficulty of long-term humidity regulation.

[0005] The objective of this invention can be achieved through the following technical solutions: The first aspect of the present invention provides a method for preparing a bidirectional humidity-regulating material, comprising the following steps: S1: Sodium salt, chloride salt and hyperbranched hydrophilic polymer are polymerized in a solvent to obtain a modified hyperbranched hydrophilic wetting agent; the substrate is dipped into the modified hyperbranched hydrophilic wetting agent and dried to obtain absorbent cotton; Non-vulcanized rubber, water-absorbing polymer, thermoplastic elastomer, polyether ester plasticizer, stearic acid, carbon black, and titanium dioxide are mixed and kneaded to obtain a water-absorbing and swelling polymer composite; the water-absorbing and swelling polymer composite is calendered to obtain a water storage sheet; S2: The microporous permeable membrane, absorbent cotton, water storage sheet, absorbent cotton and microporous permeable membrane are stacked in sequence and hot-pressed to obtain the product.

[0006] In some specific embodiments, step S1, the method for preparing the hyperbranched hydrophilic polymer includes: 1) Polyacrylamide, styrene-maleic anhydride copolymer, catalyst, and α-1,4 glycosidic glucose were stirred and reacted in a reaction solvent. 2) Add glycerol, hydroxy-modified dimethylsiloxane, and bis(3-alkoxysilylpropyl)amine and stir to react, and obtain the desired product.

[0007] In some specific embodiments, in step 1), the mass ratio of the polyacrylamide, styrene-maleic anhydride copolymer, catalyst, and α-1,4 glycosidic linked glucose is 17-25:1-5:2-5:8-22. The catalyst is selected from at least one of ammonium chloride, ammonium sulfate, and ammonium nitrate; In the stirring reaction, the reaction temperature is 40-60℃ and the reaction time is 6-8h; In step 2), the bis(3-alkoxysilylpropyl)amine is selected from bis(3-trimethoxysilylpropyl)amine and bis(3-triethoxysilylpropyl)amine; The mass ratio of glycerol, hydroxy-modified dimethylsiloxane, bis(3-alkoxysilylpropyl)amine to polyacrylamide is 5-10:0.4-0.5:0.01-0.03:17-25. In the stirring reaction, the reaction temperature is 60-70℃ and the reaction time is 3-8h.

[0008] In some specific embodiments, in step S1, the sodium salt is selected from one or a combination of two of sodium formate or sodium propionate; The chloride salt is selected from at least one of sodium chloride, magnesium chloride, or calcium chloride; The mass ratio of the sodium salt, chloride salt and hyperbranched hydrophilic polymer is 10-25:1-15:2.5-3.5; The solvent is selected from at least one of ethanol, water, Span 60 or Span 80; In the polymerization reaction, the reaction temperature is 40-60℃ and the reaction time is 4-8h; The substrate is polyester fiber; preferably, the polyester fiber is selected from at least one of the following: The mass ratio of the hyperbranched hydrophilic polymer to the substrate is 2.5-3:20-50; In the dip coating process, the dip coating time is 5-20 seconds; in the drying process, the drying temperature is 75-95℃ and the drying time is 5-15 minutes.

[0009] In some specific embodiments, in step S1, the mass ratio of the non-vulcanized rubber, water-absorbing polymer, thermoplastic elastomer, and additive is 10-50:8-75:1.8-5:5-20. The thermoplastic elastomer is selected from at least one of styrene-based elastomers, olefin-based elastomers, polyamide-based elastomers, urethane-based elastomers, polyester-based elastomers, and vinyl chloride-based elastomers. The non-vulcanized rubber is selected from at least one of chloroprene rubber, butyl rubber, ethylene propylene rubber, styrene butadiene rubber, acrylic rubber, butadiene rubber, and isoprene rubber; The additive is selected from at least one of plasticizers, lubricants, colorants, or fillers; The plasticizer is a polyether ester plasticizer; The lubricant is stearic acid; preferably, it is powdered stearic acid. The colorant is selected from one or a combination of two of carbon black and titanium dioxide; The mass ratio of the non-vulcanized rubber, polyether ester plasticizer, stearic acid, carbon black, and titanium dioxide is 15-45:5.7-17:0.2-2.7:0.01-0.03:0.18-0.68; preferably, the mass ratio of the acrylic rubber, water-absorbing polymer, polyester elastomer, polyether ester plasticizer, stearic acid, carbon black, and titanium dioxide is 10-25:30-70:5-15:8-30:1-5:0.1-0.5:2-8. During the mixing process, the mixing temperature is 100-120℃ and the mixing time is 60-80 minutes.

[0010] In some specific embodiments, in step S1, the method for preparing the water-absorbing polymer includes: preparing a mixed solution of sodium hydroxide and acrylic acid; adding a reaction solvent, N,N-methylene polyacrylamide, and potassium persulfide, and stirring to react to obtain the polymer.

[0011] In some specific embodiments, the mass ratio of sodium hydroxide to acrylic acid is 23:65-85; preferably, the degree of neutralization of the acrylic acid reaches 60-95%. The reaction solvent is selected from at least one of cyclohexane, heptane, and water; The mass ratio of acrylic acid, N,N-methylene polyacrylamide, and potassium persulfide is 50:10-15:1.2-3.5. In the stirring reaction, the reaction temperature is 65-85℃ and the reaction time is 2-6h.

[0012] In some specific embodiments, in step S2, the microporous permeable membrane is a hydrophobic organic permeable membrane; preferably, the microporous permeable membrane is selected from polyethylene terephthalate (PET), cellulose acetate (CA), polyethersulfone (PES), or polytetrafluoroethylene (PTFE). In the hot pressing process, the hot pressing temperature is 100-120℃ and the hot pressing pressure is 3-5MPa.

[0013] A second aspect of the present invention provides a bidirectional humidity regulating material, comprising an upper microporous permeable membrane, a moisture-absorbing layer, a water-storing layer, a moisture-absorbing layer, and a lower microporous permeable membrane stacked sequentially.

[0014] The thickness of the microporous permeable membrane is 0.10-0.25 mm; The thickness of the absorbent layer is 0.5-2.0 mm; preferably, the absorbent layer comprises 1-3 layers of absorbent cotton. The thickness of the water storage layer is 0.8-4 mm; preferably, the water storage layer is composed of 1-2 layers of water-absorbing and swelling polymer composite with a thickness of 0.8-2.0 mm. The thickness of the lower microporous permeable membrane is 0.10-0.25 mm.

[0015] The bidirectional humidity regulating material has a humidity regulating accuracy of ≤5% within the humidity regulating range, a saturated moisture absorption rate of ≥250%, and a waterproof leakage rate of 100%.

[0016] A third aspect of the present invention provides an application of the bidirectional humidity regulating material as described above, wherein the bidirectional humidity regulating material is used in a lithium battery pack for a new energy vehicle.

[0017] This invention relates to a bidirectional humidity-regulating material, an environmentally friendly material made from a fiber matrix and a modified hyperbranched hydrophilic polymer. Unlike traditional granular or powdered desiccants, this material can automatically perform a bidirectional reversible process of moisture absorption and release in a sealed environment, efficiently regulating ambient humidity and preventing fogging and condensation. Its moisture-absorbing fiber skeleton acts as a moisture transport channel, combined with a water-absorbing and swelling polymer made from non-vulcanized rubber and a water-absorbing polymer, safely and securely storing any unreleased moisture inside the rubber, ensuring material safety against leakage during long-term use.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1) The humidity-regulating material prepared by the present invention has a spatial network structure and a large number of hydrophilic groups in its hyperbranched hydrophilic polymer, and the superabsorbent polymer has excellent porosity and long-term water absorption capacity. The water storage layer 3 has excellent water absorption, water storage and water locking capacity. 2) This invention utilizes the hydrophilic groups of the absorbent cotton and the water storage layer to enable water molecules to migrate rapidly between the two contact interfaces. At the same time, the solvated ions occupy a portion of the area, which can lock in some water molecules, hindering their evaporation and absorption, thereby improving the bidirectional humidity control efficiency of the humidity control material. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a bidirectional moisture-regulating material for a lithium battery pack in a new energy vehicle, as shown in the comparative example. Figure 2 This is a schematic diagram of the structure of a bidirectional humidity-regulating material for lithium battery packs in new energy vehicles according to the present invention; Figure 3 The morphology of a bidirectional humidity-regulating material for a new energy vehicle lithium battery pack, as characterized under an optical microscope in Example 4; Figure 4 The morphology of a bidirectional humidity-regulating material for a new energy vehicle lithium battery pack, as characterized under an optical microscope in Example 4; Figure 5 This is a schematic diagram of the humidity deviation testing device; Figure 6 A photograph of the actual aquifer; Figure 7 A photograph of the aquifer after it absorbs water and expands. Explanation of markings in the diagram: 1-Upper microporous permeable membrane, 2-Moisture-absorbing layer, 3-Water storage layer, 4-Lower microporous permeable membrane, 5-Thermometer and hygrometer, 6-Humidity conditioning material, 7-Container. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0021] The following are more detailed implementation examples, which further illustrate the technical solution of the present invention and the technical effects that can be obtained.

[0022] In the following embodiments, unless otherwise specified, the raw materials, reagents or processing techniques are all conventional commercial products or conventional processing techniques in the art.

[0023] It should be noted that, in order to facilitate comparison and explanation of the humidity control performance of the bidirectional humidity control material for lithium battery packs of new energy vehicles, the bidirectional humidity control materials for lithium battery packs of new energy vehicles prepared in the following comparative examples and embodiments have the same thickness for the upper microporous permeable membrane 1, the moisture-absorbing layer 2, and the lower encapsulation layer, but different thicknesses for the water storage layer 3. The thickness of the upper microporous permeable membrane 1 is 0.13 mm, the thickness of each layer of moisture-absorbing cotton in the moisture-absorbing layer 2 is 1.1 mm, and the thickness of the lower microporous permeable membrane 4 is 0.10 mm.

[0024] The polyethylene terephthalate (PET) permeable membrane was purchased from Xiamen Jindewei Packaging Co., Ltd., with a density of 1.4 g / cm³. 3 (thickness 23μm) The polyester fiber was purchased from Qidong Xintianding Materials Technology Co., Ltd., model: PES1010; Polyacrylamide was purchased from China National Pharmaceutical Group Co., Ltd., model: Acros-178040050; Styrene-maleic anhydride copolymer (Sinopharm Group, molar ratio 3:1, molecular weight approximately 28,000) α-1,4-glycosidic linkage to glucose (Sinopharm Group 50U / mg, molecular weight: 1~2×10) 5 ) Hydroxyl-modified dimethylsiloxane was purchased from Zhejiang Runhe Organosilicon New Materials Co., Ltd., model: RH102; The polyethersulfone (PES) permeation membrane was purchased from Mabrui Biomembrane Technology Co., Ltd. Its 0.1μm bubble point is 0.60-0.75MPa, and its water flow rate (10psi) is 10-13mL / min / cm. 2 .

[0025] N,N-methylene polyacrylamide was purchased from China National Pharmaceutical Group Co., Ltd. (model Acros-163800025) The polyester elastomer was purchased from BGI Genomics Co., Ltd., and its main properties are shown in the table below: Table 1 The polyether ester plasticizer was purchased from Shanzhen Industrial (Shanghai) Co., Ltd., model: RS735; The acrylic rubber was purchased from Zeon Corporation of Japan, model number: RH71; The polyimide (PI) permeation membrane was purchased from Suzhou Yingchuan New Material Technology Co., Ltd., model: 6051 polyimide insulating film; The base material is a piece of absorbent cotton measuring 88×128×1.5mm, made by Nangong Xingcan Felt Co., Ltd., with a thickness of 3mm and a material of polypropylene.

[0026] Comparative Example 1 A bidirectional moisture-regulating material for lithium battery packs in new energy vehicles, such as Figure 1 As shown, it includes an upper microporous permeable membrane 1, a moisture-absorbing layer 2, and a lower microporous permeable membrane 4: both the upper microporous permeable membrane 1 and the lower microporous permeable membrane 4 are hydrophobic organic permeable membranes, specifically polyethylene terephthalate permeable membranes; the moisture-absorbing layer 2 is composed of 3 layers of moisture-absorbing cotton, specifically composed of a substrate and a hyperbranched hydrophilic wetting agent (hyperbranched hydrophilic polymer), the substrate being polyester fiber.

[0027] The preparation method of the bidirectional humidity-regulating material for lithium battery packs in new energy vehicles includes the following steps: Step 1: Immerse 3 kg of hyperbranched hydrophilic polymer in 30 kg of cyclohexane and polymerize at 75 °C and 200 RPM for 4 h; Step 2: Dip the substrate into the mixture obtained in Step 1 for 5 seconds, then remove it and dry it at 75°C for 15 minutes to obtain the absorbent cotton.

[0028] Step 3: Die-cut the absorbent cotton into sheets of 88×128×1.5mm.

[0029] Step 4: Stack the upper microporous permeable membrane 1, the 3 layers of absorbent cotton and the lower microporous permeable membrane 4 in sequence, and press the upper microporous permeable membrane 1 and the lower microporous permeable membrane 4 together using a hot pressing process (120℃, 3.6MPa) to obtain a bidirectional moisture-regulating material for lithium battery packs of new energy vehicles.

[0030] The preparation method of hyperbranched hydrophilic polymers includes the following steps: Step 1: Add 100 kg of deionized water to a glass reaction vessel, then add 17 kg of polyacrylamide, 1 kg of styrene-maleic anhydride copolymer, 2 kg of ammonium chloride catalyst, and then add 13 kg of α-1,4 glycosidic linked glucose. Stir at 40°C for 6 hours and cool the reaction system to room temperature. Step 2: Add 5 kg glycerol, 0.5 kg hydroxy-modified dimethylsiloxane, and 0.01 kg bis(3-trimethoxysilylpropyl)amine, and stir at 60°C for 3 h; filter under reduced pressure and wash with water and methanol, and vacuum dry the solid product at 30°C for 6 h to obtain the hyperbranched hydrophilic polymer.

[0031] Example 1 A bidirectional moisture-regulating material for lithium battery packs in new energy vehicles, such as Figure 2 As shown, it includes an upper microporous permeable membrane 1, a moisture-absorbing layer 2, a water-storage layer 3, and a lower microporous permeable membrane 4: both the upper and lower microporous permeable membranes 4 are hydrophobic organic permeable membranes, specifically polyethersulfone permeable membranes; the water-storage layer 3 is a single-layer water-absorbing and swelling polymer composite, specifically composed of non-vulcanized rubber and water-absorbing polymer; the moisture-absorbing layer 2 consists of two layers of moisture-absorbing cotton, specifically composed of a substrate and a modified hyperbranched hydrophilic wetting agent, the substrate being polyester fiber.

[0032] The preparation method of the bidirectional humidity-regulating material for lithium battery packs in new energy vehicles includes the following steps: Step 1: Dissolve 15 kg of sodium formate and 5 kg of sodium chloride in 30 kg of deionized water. Then immerse 3 kg of hyperbranched hydrophilic polymer in the above solution and polymerize at 75°C and a dispersion rate of 120 rpm for 4 hours to ensure that the two composite salts are uniformly coated on the polymer surface.

[0033] Step 2: Dip the substrate into the above mixture for 5 seconds, then remove it and dry it at 75°C for 15 minutes to obtain the absorbent cotton.

[0034] Step 3: Die-cut the absorbent cotton into sheets measuring 88×128×2mm.

[0035] Step 4: Mix 45kg of acrylic rubber, 42.5kg of water-absorbing polymer, 1.8kg of polyester elastomer, 8.7kg of polyether ester plasticizer, 0.2kg of stearic acid, 0.01kg of carbon black, and 0.18kg of titanium dioxide in a intensive mixing process at 120°C for 60 minutes. Then, calender the mixture to obtain a 0.8mm thick water-retaining layer 3, which is then die-cut to the same size as the absorbent cotton. The calendering process includes: temperature 100°C, roller spacing 0.7mm, roller speed 80rpm, and calendering time 30 seconds. Fold the sheet in half and calender again using the same parameters, repeating the above process three times. Step 5: Stack the upper microporous permeable membrane 1, moisture-absorbing cotton, water storage layer 3, moisture-absorbing cotton and lower microporous permeable membrane 4 in sequence, and press the upper microporous permeable membrane 1 and lower microporous permeable membrane 4 together using a hot pressing process (120°C, 3.6MPa) to obtain a bidirectional moisture-regulating material for lithium battery packs of new energy vehicles.

[0036] The preparation method of the hyperbranched hydrophilic polymer includes the following steps: Step 1: Add 100 kg of deionized water to a glass reaction vessel, then add 17 kg of polyacrylamide, 1 kg of styrene-maleic anhydride copolymer, 2 kg of ammonium chloride catalyst, and then add 13 kg of α-1,4 glycosidic linked glucose. Stir at 40°C for 6 hours and cool the reaction system to room temperature. Step 2: Add 5 kg glycerol, 0.5 kg hydroxy-modified dimethylsiloxane, and 0.01 kg bis(3-trimethoxysilylpropyl)amine, and stir at 60°C for 3 h; filter under reduced pressure and wash with water and methanol, and vacuum dry the solid product at 30°C for 6 h to obtain the hyperbranched hydrophilic polymer.

[0037] The method for preparing the water-absorbing polymer includes the following steps: Step 1: At room temperature, neutralize 50 kg of acrylic acid to a final concentration of 85 wt% with a 23% sodium hydroxide solution. Step 2: Add 100 kg of cyclohexane, 10 kg of N,N-methylene polyacrylamide, and 3.5 kg of potassium persulfate to the acrylic acid solution, heat to 65°C, and stir the mixture using a disperser at a speed of 300 rpm for 4 hours. After air cooling, the reaction product is washed with ethanol to obtain the water-absorbing polymer.

[0038] Example 2 A bidirectional moisture-regulating material for lithium battery packs in new energy vehicles, such as Figure 2As shown, it includes an upper microporous permeable membrane 1, a moisture-absorbing layer 2, a water-storage layer 3, and a lower microporous permeable membrane 4; both the upper and lower microporous permeable membranes 4 are hydrophobic organic permeable membranes, specifically polyethersulfone permeable membranes; the water-storage layer 3 is a single-layer water-absorbing and swelling polymer composite, specifically composed of non-vulcanized rubber and water-absorbing polymer; the moisture-absorbing layer 2 consists of two layers of moisture-absorbing cotton, specifically composed of a substrate and a modified hyperbranched hydrophilic wetting agent, the substrate being polyester fiber.

[0039] The preparation method of the bidirectional humidity-regulating material for lithium battery packs in new energy vehicles includes the following steps: Step 1: Dissolve 20 kg of sodium formate and 3 kg of calcium chloride in 30 kg of deionized water. Then immerse 2.5 kg of hyperbranched hydrophilic polymer in the above solution and polymerize at 75°C and a dispersion rate of 120 rpm for 5 hours to ensure that the two composite salts are uniformly coated on the polymer surface.

[0040] Step 2: Dip the substrate into the above mixture for 9 seconds, then remove it and dry it at 85°C for 10 minutes to obtain the absorbent cotton.

[0041] Step 3: Die-cut the absorbent cotton into sheets of 88×128×1.5mm.

[0042] Step 4: Mix 35kg of acrylic rubber, 55kg of water-absorbing polymer, 2.8kg of polyester elastomer, 5.7kg of polyether ester plasticizer, 1.2kg of stearic acid, 0.03kg of carbon black, and 0.50kg of titanium dioxide in a intensive mixing process at 120°C for 60 minutes. Then, calender the mixture to obtain a 1.0mm thick water-retaining layer 3, which is then die-cut to the same size as the absorbent cotton. The calendering process includes: a temperature of 100°C, a roller spacing of 0.9mm, a roller speed of 80rpm, and a calendering time of 30 seconds. Fold the sheet in half and calender again using the same parameters, repeating the above process three times.

[0043] Step 5: Stack the upper microporous permeable membrane 1, moisture-absorbing cotton, water storage layer 3, moisture-absorbing cotton and lower microporous permeable membrane 4 in sequence, and press the upper microporous permeable membrane 1 and lower microporous permeable membrane 4 together using a hot pressing process (120°C, 3.6MPa) to obtain a bidirectional moisture-regulating material for lithium battery packs of new energy vehicles.

[0044] The preparation method of the hyperbranched hydrophilic polymer includes the following steps: Step 1: Add 100 kg of deionized water to a glass reaction vessel, then add 17 kg of polyacrylamide, 1 kg of styrene-maleic anhydride copolymer, 2 kg of ammonium chloride catalyst, and then add 13 kg of α-1,4 glycosidic linked glucose. Stir at 60°C for 6 hours and cool the reaction system to room temperature. Step 2: Add 5 kg glycerol, 0.5 kg hydroxy-modified dimethylsiloxane, and 0.01 kg bis(3-trimethoxysilylpropyl)amine, and stir at 60°C for 3 h; filter under reduced pressure and wash with water and methanol; dry the solid product under vacuum at 30°C for 6 h to obtain the hyperbranched hydrophilic polymer.

[0045] The method for preparing the water-absorbing polymer includes the following steps: Step 1: At room temperature, neutralize 50 kg of acrylic acid to a final concentration of 75 wt% with a 23% sodium hydroxide solution. Step 2: Add 200 kg heptane, 10 kg N,N-methylene polyacrylamide, and 5.5 kg potassium persulfate to 25 kg of acrylic acid solution, heat to 65°C, stir the mixture using a disperser at a speed of 200 rpm, and react for 3 hours. After air cooling, the reaction product is washed with ethanol to obtain the water-absorbing polymer.

[0046] Example 3 A bidirectional moisture-regulating material for lithium battery packs in new energy vehicles, such as Figure 2 As shown, it includes an upper microporous permeable membrane 1, a moisture-absorbing layer 2, a water-storage layer 3, and a lower microporous permeable membrane 4; both the upper and lower microporous permeable membranes 4 are hydrophobic organic permeable membranes, specifically polyethersulfone permeable membranes; the water-storage layer 3 is a single-layer water-absorbing and swelling polymer composite, specifically composed of non-vulcanized rubber and water-absorbing polymer; the moisture-absorbing layer 2 is composed of two layers of moisture-absorbing cotton, specifically composed of a substrate and a modified hyperbranched hydrophilic wetting agent, the substrate being polyester fiber.

[0047] The application scheme of the bidirectional moisture-regulating material for lithium battery packs in new energy vehicles includes the following steps: Step 1: Dissolve 20 kg of sodium propionate and 3 kg of magnesium chloride in 30 kg of deionized water. Then immerse 2.5 kg of hyperbranched hydrophilic polymer in the above solution and polymerize at 75°C and a dispersion rate of 120 rpm for 5 hours to ensure that the two composite salts are uniformly coated on the polymer surface.

[0048] Step 2: Dip the substrate into the above mixture for 9 seconds, then remove it and dry it at 85°C for 10 minutes to obtain the absorbent cotton.

[0049] Step 3: Die-cut the absorbent cotton into sheets of 88×128×1.5mm.

[0050] Step 4: Mix 25kg of acrylic rubber, 65kg of water-absorbing polymer, 2.8kg of polyester elastomer, 5.7kg of polyether ester plasticizer, 1.2kg of stearic acid, 0.03kg of carbon black, and 0.50kg of titanium dioxide in a intensive mixing process at 120°C for 60 minutes. Then, calender the mixture to obtain a 1.2mm thick water-retaining layer 3, which is then die-cut to the same size as the absorbent cotton. The calendering process is as follows: temperature 100°C, roller spacing 1.1mm, roller speed 80rpm, calendering time 30 seconds. Fold the sheet in half and calender again using the same parameters, repeating the above process 5 times.

[0051] Step 5: Stack the upper microporous permeable membrane 1, moisture-absorbing cotton, water storage layer 3, moisture-absorbing cotton and lower microporous permeable membrane 4 in sequence, and press the upper microporous permeable membrane 1 and lower microporous permeable membrane 4 together using a hot pressing process (120°C, 3.6MPa) to obtain a bidirectional moisture-regulating material for lithium battery packs of new energy vehicles.

[0052] The preparation method of the hyperbranched hydrophilic polymer includes the following steps: Step 1: Add 100 kg of deionized water to a glass reaction vessel, then add 17 kg of polyacrylamide, 1 kg of styrene-maleic anhydride copolymer, 2 kg of ammonium sulfate catalyst, and then add 13 kg of α-1,4 glycosidic linked glucose. Stir at 60°C for 6 hours and cool the reaction system to room temperature. Step 2: Add 9 kg glycerol, 0.4 kg hydroxy-modified dimethylsiloxane, and 0.03 kg bis(3-trimethoxysilylpropyl)amine, and stir at 70°C for 5 h; filter under reduced pressure and wash with water and methanol; dry the solid product under vacuum at 80°C for 8 h to obtain the hyperbranched hydrophilic polymer.

[0053] The method for preparing the water-absorbing polymer includes the following steps: Step 1: At room temperature, neutralize 50 kg of acrylic acid to a final concentration of 75 wt% with a 23% sodium hydroxide solution.

[0054] Step 2: Add 250 kg of deionized water, 15 kg of N,N-methylene polyacrylamide, and 1.5 kg of potassium persulfate to 25 kg of acrylic acid solution. Heat to 75°C and stir the mixture using a disperser at a speed of 150 rpm for 5 hours. After air cooling, wash the product with ethanol to obtain the water-absorbing polymer.

[0055] Example 4 A bidirectional moisture-regulating material for lithium battery packs in new energy vehicles, such as Figure 2As shown, it includes an upper microporous permeable membrane 1, a moisture-absorbing layer 2, a water-storage layer 3, and a lower microporous permeable membrane 4; both the upper and lower microporous permeable membranes 4 are hydrophobic organic permeable membranes, specifically polyimide permeable membranes; the water-storage layer 3 is a single-layer water-absorbing and swelling polymer composite, specifically composed of non-vulcanized rubber and water-absorbing polymer; the moisture-absorbing layer 2 consists of two layers of moisture-absorbing cotton, specifically composed of a substrate and a modified hyperbranched hydrophilic wetting agent, the substrate being polyester fiber.

[0056] The preparation method of the bidirectional humidity-regulating material for lithium battery packs in new energy vehicles includes the following steps: Step 1: Dissolve 25 kg of sodium propionate and 1 kg of calcium chloride in 50 kg of deionized water. Then immerse 3.5 kg of hyperbranched hydrophilic polymer in the above solution and polymerize at 75°C and a dispersion rate of 120 rpm for 8 hours to ensure that the two composite salts are uniformly coated on the polymer surface.

[0057] Step 2: Dip the substrate into the above mixture for 20 seconds, then remove it and dry it at 95°C for 15 minutes to obtain the absorbent cotton.

[0058] Step 3: Die-cut the absorbent cotton into sheets of 88×128×1.5mm.

[0059] Step 4: Mix 15kg of acrylic rubber, 60kg of water-absorbing polymer, 5kg of polyester elastomer, 17kg of polyether ester plasticizer, 2.7kg of stearic acid, 0.03kg of carbon black, and 0.68kg of titanium dioxide in a intensive mixing process at 120°C for 60 minutes. Then, calender the mixture to obtain a 1.5mm thick water-retaining layer 3, which is then die-cut to the same size as the absorbent cotton. The calendering process includes a temperature of 100°C, a roller spacing of 1.4mm, a roller speed of 80rpm, and a calendering time of 30 seconds. Fold the sheet in half and calender again using the same parameters, repeating this process 5 times.

[0060] Step 5: Stack the upper microporous permeable membrane 1, moisture-absorbing cotton, water storage layer 3, moisture-absorbing cotton and lower microporous permeable membrane 4 in sequence, and press the upper microporous permeable membrane 1 and lower microporous permeable membrane 4 together using a hot pressing process (120°C, 3.6MPa) to obtain a bidirectional moisture-regulating material for lithium battery packs of new energy vehicles.

[0061] The application scheme of the hyperbranched hydrophilic polymer includes the following steps: Step 1: Add 200 kg of deionized water to a glass reaction vessel, then add 25 kg of polyacrylamide, 5 kg of styrene-maleic anhydride copolymer, 5 kg of ammonium sulfate catalyst, and then add 15 kg of α-1,4 glycosidic linked glucose. Stir at 60°C for 8 hours and cool the reaction system to room temperature. Step 2: Add 10 kg glycerol, 0.5 kg hydroxy-modified dimethylsiloxane, 0.015 kg bis(3-trimethoxysilylpropyl)amine, and 0.015 kg bis(3-triethoxysilylpropyl)amine, and stir at 70°C for 8 h; filter under reduced pressure and wash with water and methanol; dry the solid product under vacuum at 80°C for 8 h to obtain the hyperbranched hydrophilic polymer.

[0062] The method for preparing the water-absorbing polymer includes the following steps: Step 1: At room temperature, neutralize 50 kg of acrylic acid to a final concentration of 65 wt% with a 23% sodium hydroxide solution.

[0063] Step 2: Add 250 kg of cyclohexane, 12.5 kg of N,N-methylene polyacrylamide, and 1.2 kg of potassium persulfate to 25 kg of acrylic acid solution. Heat to 85°C and stir the mixture using a disperser at a speed of 350 rpm for 6 hours. After air cooling, wash the product with ethanol to obtain the water-absorbing polymer.

[0064] Application Examples Humidity deviation test: Using a programmable temperature and humidity chamber, such as... Figure 5 The container 7 shown (0.10m in diameter, 1.0m in length) has temperature and humidity monitored by thermometers and hygrometers 5 connected at its head, middle, and tail (every 0.4m apart). A humidity-regulating material 6 (92mm × 132mm × 5.5mm) prepared according to the comparative example and Examples 1-4 is placed at the head or tail of the container and placed in a constant temperature and humidity environment of 45℃ and 95% for 12 hours. The humidity values ​​at the three monitoring points are recorded, and the minimum value of the three monitoring points is subtracted from the minimum value to calculate the moisture absorption deviation of the humidity-regulating material in the container. The container is then placed in a constant temperature and humidity environment of 45℃ and 25% for 12 hours, and the humidity values ​​at the three monitoring points are recorded. The minimum humidity value of the three monitoring points is subtracted from the maximum value to calculate the moisture release deviation of the humidity-regulating material in the container.

[0065] Moisture absorption capacity test: The humidity-conditioning materials with dimensions of 92mm × 132mm × 5.5mm, prepared according to the comparative examples and Examples 1-4, were placed in a constant temperature and humidity chamber at 45℃ and 95% humidity. They were weighed every hour, and the moisture absorption rate of the humidity-conditioning materials was calculated using the formula: Moisture absorption rate = (Absorbed weight - Original weight) / Original weight. The final saturation moisture absorption rate of the humidity-conditioning material was recorded, which is the moisture absorption rate at which the weight of the humidity-conditioning material no longer increases under these environmental conditions.

[0066] Waterproof leak-proof capability test: The moisture-regulating materials with dimensions of 92mm×132mm×5.5mm prepared from the comparative examples and Examples 1-4 were labeled as C1, S1, S2, S3, and S4, respectively. They were placed in a constant temperature and humidity environment of 45℃ and 85% for long-term moisture absorption tests. During the test, they were weighed every 24 hours and the moisture absorption rate of each sample was calculated. When the moisture absorption rate reached 180%, the packaging was observed and shaken to check whether there was any flowing water deposited inside the breathable membrane.

[0067] Judgment criteria The sample is deemed "qualified" if its moisture absorption rate is ≥180% and ≤300%, and there is no flowing water in the breathable membrane. The sample has a moisture absorption rate of less than 180%, and flowing water appears in the breathable membrane, so it is judged as "unqualified".

[0068] The test results are shown in the table below: Table 2 The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a two-way humidity-regulating material, characterized in that, Includes the following steps: S1: Sodium salt, chloride salt and hyperbranched hydrophilic polymer are polymerized in a solvent to obtain a modified hyperbranched hydrophilic wetting agent; the substrate is dipped into the modified hyperbranched hydrophilic wetting agent and dried to obtain absorbent cotton; Non-vulcanized rubber, water-absorbing polymer, thermoplastic elastomer, polyether ester plasticizer, stearic acid, carbon black, and titanium dioxide are mixed and kneaded to obtain a water-absorbing and swelling polymer composite; the water-absorbing and swelling polymer composite is calendered to obtain a water storage sheet; S2: The microporous permeable membrane, absorbent cotton, water storage sheet, absorbent cotton and microporous permeable membrane are stacked in sequence and hot-pressed to obtain the product.

2. The method for preparing the bidirectional humidity-regulating material according to claim 1, characterized in that, In step S1, the preparation method of the hyperbranched hydrophilic polymer includes: 1) Polyacrylamide, styrene-maleic anhydride copolymer, catalyst, and α-1,4 glycosidic glucose were stirred and reacted in a reaction solvent. 2) Add glycerol, hydroxy-modified dimethylsiloxane, and bis(3-alkoxysilylpropyl)amine and stir to react, and obtain the desired product.

3. The method for preparing the bidirectional humidity-regulating material according to claim 2, characterized in that, In step 1), the mass ratio of polyacrylamide, styrene-maleic anhydride copolymer, catalyst, and α-1,4 glycosidic linked glucose is 17-25:1-5:2-5:8-22. The catalyst is selected from at least one of ammonium chloride, ammonium sulfate, and ammonium nitrate; In the stirring reaction, the reaction temperature is 40-60℃ and the reaction time is 6-8h; In step 2), the bis(3-alkoxysilylpropyl)amine is selected from bis(3-trimethoxysilylpropyl)amine and bis(3-triethoxysilylpropyl)amine; The mass ratio of glycerol, hydroxy-modified dimethylsiloxane, bis(3-alkoxysilylpropyl)amine to polyacrylamide is 5-10:0.4-0.5:0.01-0.03:17-25. In the stirring reaction, the reaction temperature is 60-70℃ and the reaction time is 3-8h.

4. The method for preparing the bidirectional humidity-regulating material according to claim 1, characterized in that, In step S1, the sodium salt is selected from one or a combination of two of sodium formate or sodium propionate; The chloride salt is selected from at least one of sodium chloride, magnesium chloride, or calcium chloride; The mass ratio of the sodium salt, chloride salt and hyperbranched hydrophilic polymer is 10-25:1-15:2.5-3.5; The solvent is selected from at least one of ethanol, water, Span 60 or Span 80; In the polymerization reaction, the reaction temperature is 40-60℃ and the reaction time is 4-8h; The substrate is polyester fiber; preferably, the polyester fiber is selected from at least one of the following: The mass ratio of the hyperbranched hydrophilic polymer to the substrate is 2.5-3:20-50.

5. The method for preparing the bidirectional humidity-regulating material according to claim 1, characterized in that, In step S1, the mass ratio of the non-vulcanized rubber, water-absorbing polymer, thermoplastic elastomer, and additive is 10-50:8-75:1.8-5:5-20. The thermoplastic elastomer is selected from at least one of styrene-based elastomers, olefin-based elastomers, polyamide-based elastomers, urethane-based elastomers, polyester-based elastomers, and vinyl chloride-based elastomers. The non-vulcanized rubber is selected from at least one of chloroprene rubber, butyl rubber, ethylene propylene rubber, styrene butadiene rubber, acrylic rubber, butadiene rubber, and isoprene rubber; The additive is selected from at least one of plasticizers, lubricants, colorants, or fillers; The plasticizer is a polyether ester plasticizer; The lubricant is stearic acid; The colorant is selected from one or a combination of two of carbon black and titanium dioxide; The mass ratio of the non-vulcanized rubber, polyether ester plasticizer, stearic acid, carbon black, and titanium dioxide is 15-45:5.7-17:0.2-2.7:0.01-0.03:0.18-0.

68. During the mixing process, the mixing temperature is 100-120℃ and the mixing time is 60-80 minutes.

6. The method for preparing the bidirectional humidity-regulating material according to claim 1, characterized in that, In step S1, the method for preparing the water-absorbing polymer includes: preparing a mixed solution of sodium hydroxide and acrylic acid; adding a reaction solvent, N,N-methylene polyacrylamide, and potassium persulfide, and stirring to react to obtain the polymer.

7. The method for preparing the bidirectional humidity-regulating material according to claim 6, characterized in that, The mass ratio of sodium hydroxide to acrylic acid is 23:65-85; The reaction solvent is selected from at least one of cyclohexane, heptane, and water; The mass ratio of acrylic acid, N,N-methylene polyacrylamide, and potassium persulfide is 50:10-15:1.2-3.

5. In the stirring reaction, the reaction temperature is 65-85℃ and the reaction time is 2-6h.

8. The method for preparing the bidirectional humidity-regulating material according to claim 1, characterized in that, In step S2, the microporous permeable membrane is a hydrophobic organic permeable membrane; preferably, the microporous permeable membrane is selected from one of polyethylene terephthalate, cellulose acetate, polyethersulfone, or polytetrafluoroethylene. In the hot pressing process, the hot pressing temperature is 100-120℃ and the hot pressing pressure is 3-5MPa.

9. A two-way humidity regulating material, characterized in that, It includes an upper microporous permeable membrane (1), a moisture-absorbing layer (2), a water storage layer (3), a moisture-absorbing layer (2), and a lower microporous permeable membrane (4) stacked in sequence. The thickness of the upper microporous permeable membrane (1) is 0.10-0.25 mm; The thickness of the moisture-absorbing layer (2) is 0.5-2.0 mm; The thickness of the water storage layer (3) is 0.8-4 mm; The thickness of the lower microporous permeable membrane (4) is 0.10-0.25 mm.

10. An application of the bidirectional humidity-regulating material as described in claim 9, characterized in that, The bidirectional humidity-regulating material is used in lithium battery packs for new energy vehicles.

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