High-strength fast-rebound 3D printing battery elastic pad and preparation method thereof

Abstract

The application provides a high-strength fast-rebound 3D printing battery elastic pad and a preparation method thereof, and relates to the technical field of 3D printing. The 3D printing battery elastic pad of the application selects flexible chain polyglycol and rigid chain isocyanate, forms polyurethane prepolymer through molecular structure design, and the high-elastic flexible chain structure and high-strength rigid chain structure are staggered in the main chain of the polyurethane prepolymer, which endows the polyurethane prepolymer material with mechanical properties like a'spring' supported by a rigid structure. Meanwhile, the application adopts a regular dodecahedron with high symmetry as a basic lattice unit for three-dimensional space filling, and the unique gentle force-deformation curve feature makes the stress increase amplitude stable in a large deformation range. This feature can effectively buffer the dynamic stress generated in the process of charging and discharging cycles or mechanical vibration of the battery, avoid the damage of the battery structure caused by stress concentration, and thus significantly improve the safety performance and service life of the battery system.

Description

Technical Field

[0001] The present invention relates to the field of 3D printing technology, and in particular to a high-strength, fast-rebound 3D printed battery elastic pad and a preparation method thereof. Background Art

[0002] With the rapid development of 3D printing technology, its application in the field of energy storage is becoming increasingly widespread, especially in flexible electronic devices and wearable devices. The demand for high-performance battery buffer materials has increased significantly. Traditional battery elastic pads are mostly made of foam materials or silicone. For example, patent CN 115476524 A discloses a preparation process for a buffer insulation pad for new energy vehicles. Although it has certain buffering properties, it has deficiencies in high strength, fast rebound and long-term cycle stability, and it is difficult to meet the use requirements of high-energy density batteries under dynamic conditions. In addition, the traditional manufacturing process is complex and it is difficult to achieve integrated molding of complex structures, which limits its adaptability in customized battery systems. Therefore, there is an urgent need to develop an elastic pad material that has high strength, fast rebound characteristics and can be 3D printed to improve the mechanical stability and durability of the battery system.

[0003] At present, research on elastic materials based on 3D printing is mostly focused on photocuring or thermoplastic polyurethane systems, but their rebound speed and resistance to permanent compression deformation are poor, and they are prone to plastic deformation after long-term use. Although some studies have attempted to improve the mechanical properties by modifying nanofillers (such as carbon nanotubes and graphene), they still face the problem of balancing printing accuracy and material properties. In addition, the pore structure design of existing elastic pads is single, making it difficult to simultaneously optimize stress distribution and ion transmission efficiency. Therefore, the development of a new type of 3D printing compatible material, combined with multi-scale structural design to achieve the unity of high strength, fast rebound and battery environmental adaptability, has become an important breakthrough direction in this field. Summary of the Invention

[0004] The present invention aims to provide a high-strength, fast-rebound 3D-printed battery elastic pad and its preparation method. A polyurethane prepolymer is formed by molecularly designing a flexible-chain polyglycol and a rigid-chain isocyanate. The highly elastic flexible chain structure and the high-strength rigid chain structure are interlaced within the polyurethane prepolymer's backbone, endowing the material with mechanical properties similar to a "spring" supported by a rigid structure. Furthermore, a lattice design was performed on the printed material, using the highly symmetrical regular dodecahedron as the basic lattice unit for filling three-dimensional space. The regular dodecahedron, a Platonic solid, consists of 12 identical regular pentagonal faces. Based on this polyhedral unit, a rectangular test model measuring 50 mm × 50 mm × 7.5 mm was designed. Precise calculations determined a uniform lattice distribution of 10 × 10 × 2. This distribution ensures that the lattice units are evenly spaced 5 mm in the xy plane and 3.75 mm apart in the z-axis, effectively filling the entire model space.

[0005] The present invention provides a method for preparing a high-strength, fast-rebound 3D-printed battery elastic pad, which specifically includes:

[0006] Step 1: Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), 4,4'-diisocyanato-3,3'-dimethylbiphenyl, a catalyst, and a solvent are added to a reactor for reaction to obtain an isocyanate-terminated oligomer represented by Formula I;

[0007] Formula I;

[0008] In formula I, x=1~25, y=1~25, z=1~25;

[0009] Step 2: Under a nitrogen atmosphere, dissolving the isocyanate-terminated oligomer of formula I obtained in step 1 and tert-butylaminoethyl methacrylate in a solvent in a reaction vessel, heating and reacting to obtain a methacrylate-terminated polyurethane prepolymer of formula II;

[0010] Formula II;

[0011] In formula II, x=1~25, y=1~25, z=1~25;

[0012] Step 3: Component A is composed of a polyurethane prepolymer modified with a methacrylate end group, a reactive diluent, and a photoinitiator, and 3,3'-dimethylbenzidine is used as component B. Components A and B are uniformly mixed to obtain a photosensitive resin;

[0013] Step 4: Before 3D printing, a lattice design is performed on the shape of the material to be printed to form a T-lattice. The T-lattice uses a regular dodecahedron as the basic lattice unit and a 50mm×50mm×7.5mm cuboid as the test model. The lattice distribution scheme is a uniform distribution of 10×10×2. The lattice units are arranged at an equal interval of 5mm in the xy plane and at intervals of 3.75mm in the z-axis direction.

[0014] Step 5: Transfer the designed T lattice to the 3D printer, inject the photosensitive resin into the molding tank of the 3D printer for curing, and obtain the 3D printed battery elastic pad.

[0015] Preferably, in step 1, the molar ratio of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) to 4,4'-diisocyanato-3,3'-dimethylbiphenyl is 1:2.

[0016] Preferably, the amount of the catalyst added in step 1 is 0.1 wt% to 1 wt% of the total mass of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) and 4,4'-diisocyanato-3,3'-dimethylbiphenyl.

[0017] Preferably, the catalyst in step 1 is dibutyltin dilaurate, and the solvent is toluene.

[0018] Preferably, the reaction temperature in step 1 is 60-80° C., and the reaction time is 2-4 hours.

[0019] Preferably, in step 2, the molar ratio of the isocyanate-terminated oligomer to tert-butylaminoethyl methacrylate is 1:(2-2.5).

[0020] Preferably, the reaction temperature in step 2 is 60-80° C., and the reaction time is 4-6 hours.

[0021] Preferably, the reactive diluent in step three is dipropylene glycol diacrylate, and the photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide.

[0022] Preferably, in step 3, the mass ratio of the methacrylate end-group modified polyurethane prepolymer, the reactive diluent, the photoinitiator and 3,3'-dimethylbenzidine is (50-70): (25-40): (1-5): (5-15).

[0023] The present invention also provides a 3D printed battery elastic pad obtained by the above preparation method.

[0024] Beneficial effects of the present invention

[0025] The present invention provides a high-strength, fast-rebound 3D-printed battery elastic pad and a preparation method thereof. At the material level, the present invention creatively uses polyglycol flexible chain segments and isocyanate rigid chain segments for molecular assembly, and synthesizes a polyurethane prepolymer with a specific sequence structure through precise control. The highly elastic flexible chain structure and the high-strength rigid chain structure are staggered in the main chain of the polyurethane prepolymer, which gives the polyurethane prepolymer material mechanical properties like a "spring" supported by a rigid structure, and achieves synergistic optimization of strength and toughness at the molecular scale, so that the material has both excellent mechanical strength and good toughness. In terms of structural design, the present invention has made a breakthrough in using a regular dodecahedron as the basic lattice unit to construct a T lattice structure. This design significantly improves the spatial utilization of the mechanical properties of the material through optimized spatial topological configuration. The uniform lattice distribution scheme based on computational simulation ensures the material's three-dimensional isotropic mechanical response. Its uniquely flat force-deformation curve maintains a stable stress increase over a wide deformation range. This property effectively buffers the dynamic stress generated by the battery during charge-discharge cycles or mechanical vibration, preventing structural damage due to stress concentration, thereby significantly improving the safety and service life of the battery system. These technical features make it particularly suitable for applications such as electric vehicle power batteries and large-scale energy storage systems, which require stringent reliability, space efficiency, and cost-effectiveness, and have broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the NMR spectrum of the methacrylate end-group modified polyurethane prepolymer prepared in Example 1 of the present invention;

[0027] Figure 2 This is a physical picture of the 3D printed battery elastic pad prepared in Example 1 of the present invention;

[0028] Figure 3 This is the tensile strength curve of the 3D printed battery elastic pad prepared in Example 1 of the present invention;

[0029] Figure 4 This is the tensile strength curve of the 3D printed battery elastic pad prepared in Example 2 of the present invention;

[0030] Figure 5 This is the tensile strength curve of the 3D printed battery elastic pad prepared in Example 3 of the present invention;

[0031] Figure 6 This is the tensile strength curve of the 3D printed battery elastic pad prepared in Comparative Example 1;

[0032] Figure 7 This is a T lattice compression curve of the 3D printed battery elastic pad prepared in Example 1 of the present invention;

[0033] Figure 8 This is a compression curve diagram of the 3D printed battery elastic pad prepared in Comparative Example 1;

[0034] Figure 9 This is the T lattice model diagram of the present invention. DETAILED DESCRIPTION

[0035] The present invention provides a method for preparing a high-strength, fast-rebound 3D-printed battery elastic pad, which specifically includes:

[0036] Step 1: Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), 4,4'-diisocyanato-3,3'-dimethylbiphenyl, a catalyst and a solvent are added to a reactor for reaction. The reaction is preferably performed by gradually heating the system to a reaction temperature range of 60-80°C in a programmed temperature rising manner, and maintaining a constant reaction temperature for 2-4 hours. After the reaction is completed, the reaction system is allowed to cool naturally to room temperature, and the solvent is then removed by reduced pressure distillation to obtain the isocyanate shown in Formula I. Ester-terminated oligomer; the catalyst is preferably dibutyltin dilaurate, the solvent is preferably toluene, the molar ratio of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) to 4,4'-diisocyanato-3,3'-dimethylbiphenyl is preferably 1:2; the amount of the catalyst dibutyltin dilaurate is 0.1wt% to 1wt% of the total mass of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) and 4,4'-diisocyanato-3,3'-dimethylbiphenyl. The reaction process is as follows:

[0037]

[0038] Step 2: Under a nitrogen atmosphere, dissolve the isocyanate-terminated oligomer of Formula I obtained in Step 1 and the isocyanate blocking agent, tert-butylaminoethyl methacrylate, in a solvent, preferably N,N-dimethylformamide, in a reaction vessel, and then react. The reaction temperature is preferably 60-80°C, and the reaction time is preferably 4-6 hours. After the reaction is completed, pour the mixed solution into n-hexane to precipitate the product. After collecting the solid by suction filtration, repeatedly wash and purify it with n-hexane, and finally dry it to obtain the methacrylate-terminated polyurethane prepolymer of Formula II. The molar ratio of the isocyanate-terminated oligomer to tert-butylaminoethyl methacrylate is preferably 1:(2-2.5). The reaction process is as follows:

[0039]

[0040] Step 3: Component A is composed of a polyurethane prepolymer modified with a methacrylate end group, a reactive diluent, and a photoinitiator, and 3,3'-dimethylbenzidine is used as component B. Components A and B are uniformly mixed to obtain a photosensitive resin; the reactive diluent is preferably dipropylene glycol diacrylate, and the photoinitiator is preferably diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide; the mass ratio of the polyurethane prepolymer modified with a methacrylate end group, the reactive diluent, the photoinitiator, and 3,3'-dimethylbenzidine is preferably (50-70): (25-40): (1-5): (5-15).

[0041] Step 4: Before 3D printing, the shape of the material to be printed is designed for lattice design. The highly symmetrical regular dodecahedron is used as the basic lattice unit to fill the three-dimensional space to form a T lattice. The regular dodecahedron is a Platonic solid composed of 12 identical regular pentagonal faces. The T lattice uses the regular dodecahedron as the basic lattice unit and uses a 50mm×50mm×7.5mm rectangular parallelepiped as the test model. The lattice distribution scheme is a uniform distribution of 10×10×2. The lattice units are arranged at an equal interval of 5mm in the xy plane and at intervals of 3.75mm in the z-axis direction. The T lattice model is shown in the figure below. Figure 9 As shown;

[0042] Step 5: Transfer the designed T lattice to the 3D printer, inject the photosensitive resin into the molding tank of the 3D printer and perform light curing to obtain a light-cured 3D printed battery elastic pad. The light curing preferably uses a 405nm wavelength ultraviolet light source to irradiate layer by layer, thereby triggering a photopolymerization reaction and obtaining a light-cured product. The light curing reaction process of photosensitive resin 3D printing is as follows:

[0043]

[0044] To complete the photocuring process, the 3D printed battery elastic pad must first be preheated in an 80°C environment for 0.5-2 hours, then the temperature is raised to 140-150°C and maintained for 2 hours to achieve complete thermal curing. During this high-temperature thermal curing process, due to the weak thermal stability of the urea bond formed by the reaction of secondary amine and isocyanate, it will partially thermally decompose and reform into an isocyanate prepolymer (Reaction A). The newly formed isocyanate prepolymer can continue the chain extension reaction with 3,3'-dimethylbenzidine in component B (Reaction B), and finally obtain a 3D printed battery elastic pad sample. The thermal curing reaction process of the battery elastic pad is as follows:

[0045] Reaction A

[0046]

[0047] Reaction B

[0048]

[0049] The present invention also provides a 3D printed battery elastic pad obtained by the above preparation method.

[0050] The present invention is further described in detail below with reference to specific examples, in which the raw materials involved are all commercially available.

[0051] Example 1

[0052] 1) Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (16.30 g, 10 mmol, molecular structure: x=10, y=10, z=10), 4,4'-diisocyanato-3,3'-dimethylbiphenyl (5.28 g, 20 mmol), dibutyltin dilaurate (0.12 g) as a catalyst, and toluene solvent (150 mL) were added to a reactor for polymerization. The system was gradually heated to 70°C using a temperature-programmed method and maintained at this temperature for 4 hours. After the reaction, the reaction system was allowed to cool naturally to room temperature, and the toluene solvent was removed by vacuum distillation to obtain the target isocyanate-terminated oligomer.

[0053] 2) Under nitrogen atmosphere, the isocyanate-terminated oligomer obtained above (10.79 g, 5 mmol) and tert-butylaminoethyl methacrylate (1.85 g, 10 mmol) were dissolved in N,N-dimethylformamide (30 mL) and placed in a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser. The reaction system was heated to 75°C and kept stirring at a constant temperature for 5 hours. After the reaction was completed, the mixed solution was poured into n-hexane to precipitate the product. After the solid was collected by filtration, it was repeatedly washed and purified with n-hexane, and finally dried to obtain a methacrylate end-group modified polyurethane prepolymer. The H NMR spectrum is shown in Figure 2. Figure 1 shown.

[0054] 3) The methacrylate end-group modified polyurethane prepolymer (65.00 g) in component A, the reactive diluent dipropylene glycol diacrylate (25.00 g) and the photoinitiator diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (1.00 g) were uniformly mixed with 3,3'-dimethylbenzidine (12.00 g) in component B to obtain a photosensitive resin solution.

[0055] 4) Before 3D printing, a special lattice design was performed on the shape of the material to be printed. The highly symmetrical regular dodecahedron was used as the basic lattice unit to fill the three-dimensional space, forming a T-lattice. The T-lattice uses the regular dodecahedron as the basic lattice unit. A 50mm×50mm×7.5mm rectangular parallelepiped was used as the test model. The lattice distribution scheme was a uniform distribution of 10×10×2. The lattice units were arranged at an equal interval of 5mm in the xy plane and at intervals of 3.75mm in the z-axis direction.

[0056] 5) The designed T-lattice is transferred to an ultra-high-speed, high-precision 3D printer. Photosensitive resin is injected into the printer's molding chamber. A 405nm UV light source is used to irradiate each layer, triggering a photopolymerization reaction and producing a preliminary photocured product.

[0057] The initially formed photocured product needs to be preheated at 80°C for 1 hour, then the temperature is raised to 145°C and maintained for 2 hours to achieve complete thermal curing. During this high-temperature curing process, due to the weak thermal stability of the urea bond formed by the reaction of secondary amine and isocyanate, partial thermal cracking occurs and the isocyanate prepolymer is reformed. The newly formed isocyanate prepolymer can continue the chain extension reaction with 3,3'-dimethylbenzidine in component B, ultimately obtaining a complete 3D printed battery elastic pad.

[0058] The actual image of the 3D printed battery elastic pad prepared in Example 1 is shown in Figure 2. Figure 2 A in the middle is a top view of the 3D printed battery elastic pad. Figure 2 Middle B is a side view of the 3D printed battery elastic pad;

[0059] The tensile strength curve of the 3D printed battery elastic pad obtained in Example 1 is as follows: Figure 3 As shown in Figure 2, the tensile strength is 32.4 MPa and the elongation at break is 204%. This is due to the molecular structure design of the interlaced arrangement of the high elastic flexible chain structure and the high strength rigid chain structure in the main chain of the polyurethane prepolymer and the special lattice design, which makes the prepared material have both high strength and high toughness. The T lattice compression curve is shown in Figure 2. Figure 7 As shown in the figure, the unique flat force-deformation curve characteristic enables the stress increase to remain stable within a large deformation range. This characteristic can effectively buffer the dynamic stress generated by the battery during the charge and discharge cycle or mechanical vibration process, avoid battery structural damage caused by stress concentration, and thus significantly improve the safety performance and service life of the battery system.

[0060] Example 2

[0061] 1) Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (16.30 g, 10 mmol, x = 10, y = 10, z = 10 in its molecular structure), 4,4'-diisocyanato-3,3'-dimethylbiphenyl (5.28 g, 20 mmol), catalyst dibutyltin dilaurate (0.12 g), and toluene solvent (160 mL) were added to a reactor for polymerization. The system was gradually heated to 70 °C using a programmed temperature method, and kept constant at this temperature for 4 hours. After the reaction was completed, the reaction system was naturally cooled to room temperature, and the toluene solvent was removed by reduced pressure distillation, and finally the target product isocyanate-terminated oligomer was obtained.

[0062] 2) Under a nitrogen atmosphere, the isocyanate-terminated oligomer (10.79 g, 5 mmol) obtained above and tert-butylaminoethyl methacrylate (2.04 g, 11 mmol) were dissolved in solvent N,N-dimethylformamide (30 mL) to form a mixture, which was loaded into a three-necked flask equipped with a mechanical stirrer, a thermometer, and a reflux condenser. The reaction system was heated to 75 °C and kept constant temperature for 5 hours. After the reaction was completed, the mixture was poured into n-hexane to precipitate the product, and the solid was collected by suction filtration and repeatedly washed with n-hexane for purification, and finally the methacrylate end-modified polyurethane prepolymer was obtained by drying treatment.

[0063] 3) The methacrylate end-modified polyurethane prepolymer (55.00 g) in component A, active diluent dipropylene glycol diacrylate (30.00 g), and photoinitiator diphenyl-(2,4,6-trimethylbenzoyl) phosphine oxide (2.00 g) were uniformly mixed with 3,3'-dimethylbenzidine (10.00 g) in component B to obtain a photosensitive resin solution.

[0064] 4) Before 3D printing, the material shape to be printed was specially designed with a lattice, and a regular dodecahedron with high symmetry was used as a basic lattice unit for three-dimensional space filling to form a T lattice. The regular dodecahedron was used as a basic lattice unit, and a cuboid with a size of 50 mm x 50 mm x 7.5 mm was used as a test model. The lattice distribution scheme was uniform distribution with a size of 10 x 10 x 2, and the lattice units were arranged at an equal interval of 5 mm in the x-y plane and at an interval of 3.75 mm in the z-axis direction.

[0065] 5) The designed T lattice was transmitted to a super-high-speed and high-precision 3D printer, and photosensitive resin was injected into the forming groove of the 3D printer. A 405 nm wavelength ultraviolet light source was used for layer-by-layer irradiation to trigger the photopolymerization reaction and obtain a preliminary light-cured product.

[0066] The initially formed photocured product needs to be preheated at 80°C for 1 hour, then the temperature is raised to 145°C and maintained for 2 hours to achieve complete thermal curing. During this high-temperature curing process, due to the weak thermal stability of the urea bond formed by the reaction of secondary amine and isocyanate, partial thermal cracking occurs and the isocyanate prepolymer is reformed. The newly formed isocyanate prepolymer can continue the chain extension reaction with 3,3'-dimethylbenzidine in component B, ultimately obtaining a complete 3D printed battery elastic pad.

[0067] The tensile strength curve of the 3D printed battery elastic pad obtained in Example 2 is as follows: Figure 4 As shown, the tensile strength is 26.3 MPa and the elongation at break is 384%.

[0068] Example 3

[0069] 1) Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (16.30 g, 10 mmol, molecular structure: x=10, y=10, z=10), 4,4'-diisocyanato-3,3'-dimethylbiphenyl (5.28 g, 20 mmol), catalyst dibutyltin dilaurate (0.12 g), and toluene solvent (165 mL) were added to a reactor for polymerization. The system was gradually heated to 70°C using a temperature-programmed ramp and maintained at this temperature for 4 hours. After the reaction, the system was allowed to cool naturally to room temperature, and the toluene solvent was removed by vacuum distillation to obtain the target isocyanate-terminated oligomer.

[0070] 2) Under a nitrogen atmosphere, the isocyanate-terminated oligomer obtained above (10.79 g, 5 mmol) and tert-butylaminoethyl methacrylate (2.22 g, 12 mmol) were dissolved in N,N-dimethylformamide (30 mL) and placed in a three-necked flask equipped with a mechanical stirrer, thermometer, and reflux condenser. The reaction system was heated to 75°C and maintained at this temperature with stirring for 5 hours. After the reaction, the mixture was poured into n-hexane to precipitate the product. The solid was collected by filtration, repeatedly washed with n-hexane for purification, and finally dried to obtain a methacrylate-terminated polyurethane prepolymer.

[0071] 3) The methacrylate end-group modified polyurethane prepolymer (60.00 g) in component A, the reactive diluent dipropylene glycol diacrylate (30.00 g) and the photoinitiator diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (1.00 g) were uniformly mixed with 3,3'-dimethylbenzidine (8.00 g) in component B to obtain a photosensitive resin solution.

[0072] 4) Before 3D printing, a special lattice design was performed on the shape of the material to be printed. The highly symmetrical regular dodecahedron was used as the basic lattice unit to fill the three-dimensional space, forming a T-lattice. The T-lattice uses the regular dodecahedron as the basic lattice unit. A 50mm×50mm×7.5mm rectangular parallelepiped was used as the test model. The lattice distribution scheme was a uniform distribution of 10×10×2. The lattice units were arranged at an equal interval of 5mm in the xy plane and at intervals of 3.75mm in the z-axis direction.

[0073] 5) The designed T-lattice is transferred to an ultra-high-speed, high-precision 3D printer. Photosensitive resin is injected into the printer's molding chamber. A 405nm UV light source is used to irradiate each layer, triggering a photopolymerization reaction and producing a preliminary photocured product.

[0074] The initially formed photocured product needs to be preheated at 80°C for 1 hour, then the temperature is raised to 145°C and maintained for 2 hours to achieve complete thermal curing. During this high-temperature curing process, due to the weak thermal stability of the urea bond formed by the reaction of secondary amine and isocyanate, partial thermal cracking occurs and the isocyanate prepolymer is reformed. The newly formed isocyanate prepolymer can continue the chain extension reaction with 3,3'-dimethylbenzidine in component B, ultimately obtaining a complete 3D printed battery elastic pad.

[0075] The tensile strength curve of the 3D printed battery elastic pad obtained in Example 3 is as follows: Figure 5 As shown, the tensile strength is 30.9 MPa and the elongation at break is 234%.

[0076] Comparative Example 1

[0077] 1) Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) (16.30 g, 10 mmol, molecular structure: x=10, y=10, z=10), 4,4'-diisocyanato-3,3'-dimethylbiphenyl (5.28 g, 20 mmol), dibutyltin dilaurate (0.12 g) as a catalyst, and toluene solvent (150 mL) were added to a reactor for polymerization. The system was gradually heated to 70°C using a temperature-programmed method and maintained at this temperature for 4 hours. After the reaction, the reaction system was allowed to cool naturally to room temperature, and the toluene solvent was removed by vacuum distillation to obtain the target isocyanate-terminated oligomer.

[0078] 2) Under a nitrogen atmosphere, the isocyanate-terminated oligomer obtained above (10.79 g, 5 mmol) and tert-butylaminoethyl methacrylate (1.85 g, 10 mmol) were dissolved in N,N-dimethylformamide (61 mL) and placed in a three-necked flask equipped with a mechanical stirrer, thermometer, and reflux condenser. The reaction system was heated to 75°C and maintained with stirring for 5 hours. After the reaction, the mixture was poured into n-hexane to precipitate the product. The solid was collected by filtration, repeatedly washed with n-hexane for purification, and finally dried to obtain a methacrylate-terminated polyurethane prepolymer.

[0079] 3) The methacrylate end-group modified polyurethane prepolymer (65.00 g) in component A, the reactive diluent dipropylene glycol diacrylate (25.00 g) and the photoinitiator diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide (1.00 g) were uniformly mixed with 3,3'-dimethylbenzidine (12.00 g) in component B to obtain a photosensitive resin solution.

[0080] 4) Inject photosensitive resin into the molding tank of the 3D printer. Irradiate each layer with a 405nm UV light source to trigger the photopolymerization reaction and obtain a preliminary photocured product.

[0081] 5) The initially formed photocured product needs to be preheated in an 80°C environment for 1 hour, and then the temperature is raised to 145°C and maintained for 2 hours to achieve complete thermal curing, and finally a complete 3D printed battery elastic pad is obtained.

[0082] The tensile strength curve of the 3D printed battery elastic pad obtained in Comparative Example 1 is as follows: Figure 6 As shown in the figure, the tensile strength is 20.9 MPa and the elongation at break is 165%. Figure 8 As shown, for the 3D printed battery elastic pad without designed T lattice, the force increases significantly with the increase of deformation.

Claims

1. A method for preparing a high-strength, fast-rebound 3D-printed battery elastic pad, characterized in that: Specifically include: Step 1: Under a nitrogen atmosphere, poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol), 4,4'-diisocyanato-3,3'-dimethylbiphenyl, a catalyst, and a solvent are added to a reactor for reaction to obtain an isocyanate-terminated oligomer represented by Formula I; Formula I; In formula I, x=1~25, y=1~25, z=1~25; Step 2: Under a nitrogen atmosphere, dissolving the isocyanate-terminated oligomer of formula I obtained in step 1 and tert-butylaminoethyl methacrylate in a solvent in a reaction vessel, heating and reacting to obtain a methacrylate-terminated polyurethane prepolymer of formula II; Formula II; In formula II, x=1~25, y=1~25, z=1~25; Step 3: Component A is composed of a polyurethane prepolymer modified with a methacrylate end group, a reactive diluent, and a photoinitiator, and 3,3'-dimethylbenzidine is used as component B. Components A and B are uniformly mixed to obtain a photosensitive resin; Step 4: Before 3D printing, a lattice design is performed on the shape of the material to be printed to form a T-lattice. The T-lattice uses a regular dodecahedron as the basic lattice unit and a 50mm×50mm×7.5mm cuboid as the test model. The lattice distribution scheme is a uniform distribution of 10×10×2. The lattice units are arranged at an equal interval of 5mm in the xy plane and at intervals of 3.75mm in the z-axis direction. Step 5: Transfer the designed T lattice to the 3D printer, inject the photosensitive resin into the molding tank of the 3D printer for curing, and obtain the 3D printed battery elastic pad.

2. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: In the step 1, the molar ratio of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) to 4,4'-diisocyanato-3,3'-dimethylbiphenyl is 1:

2.

3. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: In the step 1, the amount of the catalyst added is 0.1 wt% to 1 wt% of the total mass of the poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) and 4,4'-diisocyanato-3,3'-dimethylbiphenyl.

4. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: The catalyst in step 1 is dibutyltin dilaurate, and the solvent is toluene.

5. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: The reaction temperature of step 1 is 60-80°C, and the reaction time is 2-4 hours.

6. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: In the step 2, the molar ratio of the isocyanate-terminated oligomer to tert-butylaminoethyl methacrylate is 1:(2-2.5).

7. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: The reaction temperature of step 2 is 60-80°C and the reaction time is 4-6 hours.

8. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: The active diluent in step three is dipropylene glycol diacrylate, and the photoinitiator is diphenyl-(2,4,6-trimethylbenzoyl)phosphine oxide.

9. The method for preparing a high-strength, fast-rebound 3D printed battery elastic pad according to claim 1, characterized in that: In the step three, the mass ratio of the methacrylate end-group modified polyurethane prepolymer, the reactive diluent, the photoinitiator and the 3,3'-dimethylbenzidine is (50-70): (25-40): (1-5): (5-15).

10. The 3D printed battery elastic pad obtained by the preparation method according to claim 1.

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