Heating film composite air bag for improving performance of new energy battery and preparation method and application of heating film composite air bag

Abstract

The invention discloses a heating film composite air bag for improving the performance of a new energy battery and a preparation method and application of the heating film composite air bag, and belongs to the technical field of new energy battery preparation. The composite air bag is integrally formed by modified TPU composite cloth, a modified TPU / PET / TPU film and an embedded heating film tool through high-frequency welding; the heating film tool comprises a polyurethane conductive heating film, conductive silver paste layers coated at two ends of the polyurethane conductive heating film, and copper wire electrodes connected with the polyurethane conductive heating film; the air bag keeps a low leakage rate under high pressure, and the temperature is evenly increased after the air bag is powered on. Through the three-layer composite structure design and the high-frequency welding process, the leakage rate of the air bag is remarkably superior to the industrial standard; the embedded heating film is rapidly and uniformly heated, so that the problems of slow thermal response and non-uniform temperature of a traditional metal tray are solved, and the wettability of a battery electrolyte is improved, thereby improving the battery performance; and the production cost is greatly reduced and the production efficiency is greatly improved through the integrated forming process.

Description

TECHNICAL FIELD

[0001] The application relates to a heating film composite air bag for improving the performance of a new energy battery and a preparation method and application thereof, and belongs to the technical field of new energy battery preparation. BACKGROUND

[0002] In the baking and resting process of new energy batteries, the metal heating plate used in traditional constraint trays has a series of technical defects that need to be solved urgently. These problems not only affect the efficiency and quality of battery production, but also pose a potential threat to the safety and stability of the final product. Specifically, the metal heating plate has limitations due to its material's inherent thermal conductivity characteristics. During the heating process, significant temperature distribution unevenness occurs, with a temperature difference of more than 10°C between the center and edge of the heating plate. This temperature gradient can cause uneven heating of the battery electrode during the baking process, leading to local overheating or insufficient heating. The electrode material is therefore prone to irregular thermal deformation, which can affect the adhesion between electrode layers, or even cause active material to fall off or the separator to break, creating a short circuit hazard for the battery's subsequent charge and discharge cycle. At the same time, the inherent high thermal conductivity and large heat capacity of metal materials require a large amount of energy to maintain the operating temperature during the entire heating system operation, increasing the production energy consumption cost and prolonging the production cycle of single batch batteries due to slow heating and cooling processes, severely restricting the efficiency of large-scale production. Especially when dealing with high-porosity electrode materials such as silicon-carbon negative electrodes, the material needs to be baked for more than 36 hours to completely remove the water, electrolyte volatiles, and other impurities in the pores. The thermal inertia of the metal tray is extremely large, and the large metal base needs to absorb a large amount of heat energy during the heating stage, resulting in a slow heating rate. It often takes longer than the theoretical value to reach the set baking temperature, further lengthening the production process. More importantly, the pressure exerted by traditional metal trays on the electrode is completely dependent on rigid mechanical structures, which cannot flexibly adapt to the small size tolerance between different batteries. Even a deviation of ±0.1mm can cause significant differences in pressure distribution. Excessive pressure in some areas may cause the electrode to crack due to excessive compaction, while insufficient pressure in some areas may cause the electrode to rebound or wrinkle after baking, severely damaging the consistency of the electrode structure and ultimately affecting the energy density and cycle life of the battery.To address these issues, the industry has attempted to use silicone heating pads as an alternative. Their flexible material can adhere well to the electrode surface, improving the uneven temperature distribution to some extent. However, new drawbacks have emerged: silicone has extremely poor pressure resistance, rupturing when the ambient pressure exceeds 200 kPa. Since the baking process for new energy batteries typically requires a vacuum environment, the internal pressure often far exceeds this threshold. If the heating pad ruptures, it not only interrupts the heating process but may also cause product scrap due to silicone fragments contaminating the electrodes. Furthermore, the airtightness of silicone heating pads is insufficient for production requirements, with a leakage rate exceeding 1 kPa / h. During prolonged vacuum baking, this leakage continuously disrupts the vacuum environment, causing a gradual decrease in vacuum level. Moisture and impurities cannot be completely removed, leading to secondary contamination of the electrodes and ultimately affecting the battery's storage life and safety. Therefore, this solution still cannot meet the stringent requirements for high-quality production of new energy batteries. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a heating film composite airbag for improving the performance of new energy batteries. It is integrally formed by high-frequency welding of a modified TPU composite fabric (101), a modified TPU / PET / TPU film (102), and an embedded heating film fixture (103). The heating film fixture (103) includes a polyurethane conductive heating film (103a), conductive silver paste layers coated at both ends (103b), and connected copper wire electrodes (103c). The airbag exhibits a leakage rate ≤0.2 kPa / h after being pressurized at 300 kPa for 48 hours, and uniformly heats from room temperature to 55℃ ± 2℃ within 1-2 minutes after being powered on.

[0004] Preferably, the modified TPU composite fabric (101) is an 840D fabric coated with a two-component adhesive on both sides, dried at a gradient temperature of 40℃-160℃, and then laminated with a TPU cast film; the TPU cast film contains 5-8% flame retardant, 3-5% abrasion resistant agent and 2-4% electrolyte resistant additive by mass fraction.

[0005] Preferably, the PET layer of the modified TPU / PET / TPU film (102) has a thickness of 50±5μm, and the TPU layers on both sides have a thickness of 25±3μm.

[0006] Preferably, the heating film fixture (103) has a power of 34W±2W, an operating voltage of 48V DC, and is covered with an insulating layer (103d) with an edge flatness error of ≤0.1mm.

[0007] The present invention also provides a method for preparing the above-mentioned composite airbag, comprising the following steps:

[0008] (S1) Preparation of modified TPU composite fabric: 840D fabric is coated with two-component adhesive (solid content ≥60%), dried in a bridge oven at 40℃, 100℃, 160℃, 100℃, and 40℃, and then composited with a TPU cast film containing additives at a screw speed of 120±10r / min.

[0009] (S2) Preparation of modified TPU / PET / TPU film: PET film is cast and laminated with TPU on both sides, with interlayer bonding force ≥15N / cm;

[0010] (S3) Cutting: Cut the material obtained from S1 and S2 into pieces according to the airbag design dimensions;

[0011] (S4) Fabrication of heating film fixture: Cut the conductive heating film, coat both ends with conductive silver paste (thickness 20±5μm), spot weld copper wire electrodes, and cover the back with high temperature resistant adhesive (temperature resistance ≥150℃);

[0012] (S5) Composite: The S4 heating film fixture is attached to one side of the 840D fabric of the S1 TPU composite cloth, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0013] (S6) High-frequency welding: The layers are stacked in the order of “heating film / TPU composite cloth-TPU / PET / TPU film-TPU / PET / TPU film-heating film / TPU composite cloth”, with the outermost layer being the heating film. The edge is welded and sealed at a mold temperature of 180±5℃ and a frequency of 27.12MHz.

[0014] (S7) Trimming inspection: Remove rough edges and obtain the finished product after passing the airtightness test.

[0015] Preferably, the two-component adhesive in S1 is a polyurethane-based adhesive with a coating weight of 80±5 g / m³. 2 .

[0016] Preferably, the silver content of the conductive silver paste in S4 is ≥85%, and the sintering temperature is 150±10℃.

[0017] Preferably, the S6 welding pressure is 0.8±0.1MPa and the holding time is 10±1s.

[0018] Finally, the present invention also provides the application of the above-mentioned composite airbag in a new energy battery restraint tray, wherein the composite airbag is placed between the batteries (201), inflated and pressurized to 0.5-1.0MPa, and heated to 90-100℃ to achieve a baking process.

[0019] Preferably, the vacuum degree during the baking stage is ≤-95kPa, and the standard deviation of temperature uniformity is ≤2℃.

[0020] The beneficial effects of this invention are:

[0021] This invention achieves a leakage rate of ≤0.2kPa / h for the airbag under 300kPa high pressure for 48 hours through a three-layer composite structure design and high-frequency welding process, significantly outperforming industry standards. The embedded heating film achieves rapid and uniform heating in 1-2 minutes (temperature difference ≤2℃), solving the problems of slow thermal response (>30min) and uneven temperature of traditional metal trays. It effectively eliminates side reactions caused by residual solvents (such as NMP) on the electrode before electrolyte injection, and enhances capillary action and improves electrolyte wettability by expanding the electrode pores through heating. The modified TPU / PET / TPU film has excellent electrolyte resistance (no swelling after immersion in 6mol / L LiPF6 for 72 hours) and flame retardant properties (UL94V-0 rating), ensuring battery baking safety. The conformal airbag adapts to cell tolerances, improving pressure uniformity to over 95% and reducing electrode rebound rate to <0.1%. The integrated molding process reduces production costs and significantly improves production efficiency. Attached Figure Description

[0022] Figure 1 This invention provides a process flow diagram for a composite airbag for drying and heating film in new energy batteries.

[0023] Figure 2 This is a schematic diagram of a composite airbag structure for drying and heating film used in new energy batteries.

[0024] Figure 3 This is a schematic diagram of the basic structure of the embedded heating film tooling provided by the present invention. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0027] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0028] Example 1

[0029] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2The mixture was dried in a bridge oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) and then combined with a TPU cast film containing 6% phosphorus flame retardant, 4% nano silica wear resistant agent, and 3% fluorinated silane electrolyte resistant additive.

[0030] Step S2: 50μm PET film is cast and laminated on both sides with 25μm TPU (interlayer bonding force is approximately 18N / cm).

[0031] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0032] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 22μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0033] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0034] Step S6: After stacking the heating film / TPU composite fabric sheet + modified TPU / PET / TPU film sheet + modified TPU / PET / TPU film sheet + heating film / TPU composite fabric sheet, perform high-frequency welding on the edges using a mold. The parameters are 180℃, 0.8MPa, 27.12MHz, and welding for 10 seconds. Remove any burrs.

[0035] Example 2

[0036] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2 The mixture was subjected to a bridge-type oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) to be combined with a TPU cast film containing 8% phosphorus-nitrogen synergistic flame retardant, 4% nano silica wear resistant agent, and 3% fluorinated silane electrolyte resistant additive.

[0037] Step S2: 50μm PET film is cast and laminated on both sides with 25μm TPU (interlayer bonding force is approximately 18N / cm).

[0038] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0039] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 25μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0040] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0041] Step S6: After stacking the heating film / TPU composite fabric sheet + modified TPU / PET / TPU film sheet + modified TPU / PET / TPU film sheet + heating film / TPU composite fabric sheet, perform high-frequency welding on the edges using a mold. The parameters are 180℃, 0.8MPa, 27.12MHz, and welding for 10 seconds. Remove any burrs.

[0042] Example 3

[0043] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2 The mixture was dried in a bridge oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) and then combined with a TPU cast film containing 6% phosphorus flame retardant, 4% nano silica wear resistant agent, and 3% fluorinated silane electrolyte resistant additive.

[0044] Step S2: 60μm PET film is double-sided cast and laminated with 25μm TPU (interlayer bonding force is approximately 18N / cm).

[0045] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0046] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 20μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0047] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0048] Step S6: After stacking the heating film / TPU composite fabric sheet + modified TPU / PET / TPU film sheet + modified TPU / PET / TPU film sheet + heating film / TPU composite fabric sheet, use a mold for high-frequency welding to seal the edges. The parameters are 180℃, 1.0MPa, 27.12MHz, and welding for 10s. Remove the burrs.

[0049] Comparative Example 1 (without PET reinforcement layer)

[0050] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2 The mixture was dried in a bridge oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) and then combined with a TPU cast film containing 6% phosphorus flame retardant, 4% nano silica wear resistant agent, and 3% fluorinated silane electrolyte resistant additive.

[0051] Step S2: Take a 25μm thick TPU film.

[0052] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0053] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 22μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0054] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0055] Step S6: After stacking the heating film / TPU composite fabric sheet + TPU film sheet + TPU film sheet + heating film / TPU composite fabric sheet, use a mold to perform high-frequency welding integral forming process for edge sealing. The parameters are 180℃, 0.8MPa, 27.12MHz welding for 10s. Remove the burrs.

[0056] Comparative Example 2 (Ordinary adhesive bonding instead of welding)

[0057] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2 The mixture was dried in a bridge oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) and then combined with a TPU cast film containing 6% phosphorus flame retardant, 4% nano silica wear resistant agent, and 3% fluorinated silane electrolyte resistant additive.

[0058] Step S2: 50μm PET film is cast and laminated on both sides with 25μm TPU (interlayer bonding force is approximately 18N / cm).

[0059] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0060] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 22μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0061] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0062] Step S6: Lay out the heating film / TPU composite fabric sheet + modified TPU / PET / TPU film sheet + modified TPU / PET / TPU film sheet + heating film / TPU composite fabric sheet, and bond them with polyurethane hot melt adhesive (adhesive application rate 100g / m). 2 (Cure at 120℃ for 30 seconds). Remove any rough edges.

[0063] Comparative Example 3 (Formula without additives)

[0064] Step S1: Apply polyurethane adhesive (65% solids content, 80g / m²) to the surface of 840D fabric. 2 The mixture was dried in a bridge oven at 40℃ (5 min), 100℃ (3 min), 160℃ (2 min), 100℃ (3 min), and 40℃ (5 min) and then laminated with TPU cast film.

[0065] Step S2: 50μm PET film is cast and laminated on both sides with 25μm TPU (interlayer bonding force is approximately 18N / cm).

[0066] Step S3: Cut the obtained modified TPU composite fabric and modified TPU / PET / TPU film into pieces according to the size specifications of the airbag.

[0067] Step S4: Cut the polyimide conductive film, coat both ends with silver paste (silver content 88%, thickness about 22μm), sinter at 150℃, spot weld copper electrodes, and cover with high-temperature resistant silicone (180℃).

[0068] Step S5: Attach the heating film fixture obtained in S4 to one side of the 840D fabric of the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth, to obtain the heating film / TPU composite cloth.

[0069] Step S6: After stacking the heating film / TPU composite fabric sheet + modified TPU / PET / TPU film sheet + modified TPU / PET / TPU film sheet + heating film / TPU composite fabric sheet, perform high-frequency welding on the edges using a mold. The parameters are 180℃, 0.8MPa, 27.12MHz, and welding for 10 seconds. Remove any burrs.

[0070] The performance of all the products obtained in the embodiments and comparative examples was tested according to the following methods, and the results are shown in Table 2.

[0071] Detection method:

[0072] Thickness / weight: Cut 5 samples according to the standard, measure 5 points with an electronic micrometer (±0.001mm) and take the average value; weigh 100cm³ with a grammage meter. 2 sample.

[0073] Fracture strength: Universal testing machine (INSTRON 3365), clamping distance 100mm, tensile speed 100mm / min.

[0074] Weld strength: T-type peel test, clamp separation speed 50mm / min, record the peak force of weld fracture.

[0075] Peel strength: 180° peel test, adhesive surface width 25mm, tensile speed 300mm / min.

[0076] Flame retardancy: Vertical burning test, flame applied for 10 seconds, self-extinguishing time and the ignition of cotton wadding by dripping material are recorded.

[0077] Leakage rate: The airbag was inflated to 300 kPa, and the pressure drop was recorded by a high-precision pressure sensor (±0.01 kPa) over 48 hours.

[0078] Temperature uniformity: After powering on, the infrared thermal imager scans the surface, and the standard deviation is calculated by taking the temperature at 9 points.

[0079] Electrolyte resistance: Immersed in 85℃ / 6M LiPF6 electrolyte (EC:DEC=1:1) for 72h, and the volume expansion rate was measured.

[0080] Table 2 Performance Test Results

[0081]

[0082] According to the test results, high-frequency welding resulted in a weld strength (670-700 N / 25 mm) far exceeding that of the bonding scheme in Comparative Example 2 (95 N), proving the decisive strengthening of the interface by high-frequency energy melting; the PET reinforcement layer (missing in Comparative Example 1) increased the longitudinal breaking strength by 95% and blocked leakage; the electrolyte-resistant additive (missing in Comparative Example 3) completely suppressed swelling, while the lightweight design (0.75 mm) achieved a peel strength of 73 N / cm (3 times exceeding the national standard), meeting the requirement of "long-term crack-free operation"; crucially, the embedded... The thermal film ensures uniform heat distribution (temperature difference ≤1.8℃) and rapid heating (≤1.5min). Furthermore, Examples 2-3 achieve V-0 flame retardancy and 0.10kPa / h ultimate sealing through flame retardant optimization (8% phosphorus-nitrogen system) and PET thickening (60μm), respectively. This demonstrates that the parameter flexibility of the present invention can cover different battery process scenarios, and its comprehensive performance surpasses traditional solutions (such as traditional metal plate heating >30min / temperature difference >12℃), highlighting the irreplaceable synergistic value of the three-layer structure, high-frequency welding, and chemical modification.

[0083] Furthermore, this invention addresses the mechanisms and technological advantages of traditional metal trays in solving the problems of slow thermal response and uneven temperature distribution. Traditional metal trays suffer from two major defects in the baking process of new energy batteries: delayed thermal response and uneven temperature distribution. The high heat capacity and longitudinal thermal conductivity of metal materials require a large amount of heat energy to rise, resulting in a long measured time to reach the operating temperature. Moreover, due to edge heat dissipation, the temperature difference between the center and edge often exceeds 10°C. This non-uniform thermal field causes multiple problems. First, residual solvent side reactions are exacerbated. The N-methylpyrrolidone (NMP) solvent remaining after electrode coating undergoes a nucleophilic reaction with the electrolyte precursor during the slow heating process, generating byproducts such as ethylene carbonate derivatives, consuming the active lithium source, and increasing interfacial impedance. The embedded polyurethane conductive heating film of this invention, through the synergistic effect of planar heating and the insulation layer of the TPU composite cloth, achieves uniform heating to 55°C ± 2°C within 1-2 minutes. This rapidly overcomes the side reaction temperature zone, allowing the residual NMP on the electrode to volatilize efficiently before electrolyte injection, fundamentally inhibiting abnormal SEI film growth. Secondly, the activation of electrode pores and the enhancement of capillary effects are addressed. The slow heating of the metal tray causes the electrode surface to heat up before the interior, leading to uneven pore shrinkage and hindering electrolyte penetration. This invention utilizes the flexible pressure of an airbag to induce micro-strain in the electrode at a constant temperature, combined with the following mechanism to improve wettability: thermal expansion opening effect; the linear expansion coefficient of active materials (such as silicon-carbon anodes) can reach 8.5 × 10⁻⁶ at 55°C. -6 / K can increase the micropore diameter by 15-20% and reduce the electrolyte penetration resistance; the capillary action kinetics are optimized, the electrolyte viscosity is reduced by heating, and the surface tension is increased to enhance the capillary driving force, and the measured wetting time is significantly shortened; pressure-assisted penetration, the shape-conforming pressure of the airbag eliminates local pore collapse, and improves the uniformity of electrolyte penetration along the Z-axis, avoiding the edge "dry zone" caused by traditional rigid trays. Furthermore, the temperature uniformity of this invention also protects the electrode microstructure. The large temperature gradient of traditional metal trays causes regional glass transition of the electrode adhesive (such as PVDF), leading to local bonding failure. This solution solves the above problems through a three-layer composite structure. First, the isothermal design of the embedded heating film used in this invention reduces the end resistance of the copper wire electrode and the high silver content conductive paste. Combined with the flatness control of the surface insulation layer, it ensures a small temperature difference on the heating surface. Second, the thermal diffusion effect of the modified TPU / PET / TPU film is achieved. The longitudinal thermal conductivity of the middle PET layer is significantly lower than that of metal, but its lateral thermal diffusion ability is excellent. Combined with the elastic buffer of the TPU layers on both sides, the heat energy is quickly homogenized in the planar direction. Third, the sealing guarantee of high-frequency welding prevents edge heat dissipation caused by the flow of hot air through the dense fusion interface, maintaining a low standard deviation of temperature during the baking process.

[0084] Compared to traditional solutions, the composite airbag provided by this invention can significantly reduce the energy consumption of the baking process (metal trays require continuous heating to compensate for heat dissipation), while also greatly compressing the processing time per batch. More importantly, by eliminating temperature gradients and pressure unevenness, it can significantly reduce electrode rebound rate and electrode cracking rate in practice, directly improving battery cycle life. This technological breakthrough is particularly suitable for advanced battery systems with high wetting sensitivity, such as high-nickel ternary and silicon-based anodes, providing core process assurance for the mass production of high-energy-density batteries.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0086] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A heating film composite airbag for improving the performance of new energy batteries, characterized in that: The modified TPU composite cloth (101), the modified TPU / PET / TPU film (102), and the embedded heating film fixture (103) are integrally formed by high-frequency welding. The heating film fixture (103) includes a polyurethane conductive heating film (103a), a conductive silver paste layer coated on both ends of the film (103b), and a connected copper wire electrode (103c). The airbag has a leakage rate of ≤0.2kPa / h after being pressurized at 300kPa for 48h, and the temperature rises uniformly from room temperature to 55℃±2℃ within 1-2 minutes after being powered on.

2. The composite airbag as described in claim 1, characterized in that: The modified TPU composite fabric (101) is an 840D fabric coated with a two-component adhesive on both sides, dried at a gradient temperature of 40℃-160℃, and then laminated with a TPU cast film; the TPU cast film contains 5-8% flame retardant, 3-5% abrasion resistant agent and 2-4% electrolyte resistant additive by mass fraction.

3. The composite airbag as described in claim 1, characterized in that: The PET layer of the modified TPU / PET / TPU film (102) has a thickness of 50±5μm, and the TPU layers on both sides have a thickness of 25±3μm each.

4. The composite airbag as described in claim 1, characterized in that: The heating film fixture (103) has a power of 34W±2W, an operating voltage of 48V DC, and is covered with an insulating layer (103d) with an edge flatness error of ≤0.1mm.

5. A method for preparing the composite airbag according to any one of claims 1-4, characterized in that: Includes the following steps: (S1) Preparation of modified TPU composite fabric: 840D fabric is coated with two-component adhesive, dried in a bridge oven, and then compounded with TPU cast film containing additives by screw extrusion. (S2) Preparation of modified TPU / PET / TPU film: PET film is cast and laminated with TPU on both sides, with interlayer bonding force ≥15N / cm; (S3) Cutting: Cut the material obtained from S1 and S2 into pieces according to the airbag design dimensions; (S4) Fabrication of heating film fixture: Cut the conductive heating film, coat both ends with conductive silver paste, spot weld copper wire electrodes, and coat the back with high-temperature resistant adhesive. (S5) Composite: The heating film fixture obtained in S4 is bonded to the TPU composite cloth in S1, with the size being 5±0.5mm smaller than the edge of the composite cloth; (S6) High-frequency welding: Stack the layers in the order of "TPU composite cloth - heating film / TPU composite cloth - TPU / PET / TPU film - TPU / PET / TPU film - TPU composite cloth - heating film" and weld the edges.

6. The method as described in claim 5, characterized in that: The two-component adhesive described in S1 is a polyurethane-based adhesive with a coating weight of 80±5 g / m². 2 .

7. The method as described in claim 5, characterized in that: The silver content of the conductive silver paste in S4 is ≥85%, and the sintering temperature is 150±10℃.

8. The method as described in claim 5, characterized in that: The S6 welding pressure is 0.8±0.1MPa, and the holding time is 10±1s.

9. The application of the composite airbag as described in any one of claims 1-4 in a new energy battery restraint tray, characterized in that: The composite airbag is placed between the batteries (201), inflated and pressurized to 0.5-1.0 MPa, and heated to 90-100°C to achieve the baking process.

10. The application as described in claim 9, characterized in that: During the baking stage, the vacuum degree is ≤-95kPa and the standard deviation of temperature uniformity is ≤2℃.

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