Electrolyte-resistant enhanced new energy battery spacer tape and preparation method thereof

Abstract

The application provides an electrolyte-resistant enhanced new energy battery spacing adhesive tape and a preparation method thereof, and belongs to the field of high polymer materials. The adhesive tape comprises a release layer, a substrate layer and an adhesive layer in sequence. The adhesive layer is formed by coating and curing fluorine-containing modified acrylate copolymer, a crosslinking agent with specific dynamic covalent bonds, an oxygen-containing heterocyclic vinyl monomer modifier, a surface organic modified layered two-dimensional nano barrier filler and an organic solvent, and can have a local spaced coating structure. By constructing a micro interpenetrating polymer network and dispersing layered particles in situ, the application realizes physical and chemical synergistic barrier, so that the adhesive tape has excellent bonding durability and engineering applicability in a high-temperature electrolyte environment.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, and particularly relates to an electrolyte-resistant reinforced spacer tape for new energy batteries and its preparation method. Background Technology

[0002] With the rapid development of the global new energy vehicle and energy storage industries, increasingly stringent requirements are being placed on power batteries and energy storage batteries for long cycle life, high energy density, and safety under extreme operating conditions. In the manufacturing and assembly processes of new energy lithium-ion batteries, spacer tape, as a key auxiliary and insulating material, is widely used for the outer coating of battery cells, insulation protection of positive and negative electrode tabs, fixing and connecting battery modules, and isolating and protecting various sensitive electrical components inside the battery pack. Because this type of tape needs to remain permanently within the closed and complex chemical system inside the battery after the electrolyte injection process, its performance directly affects the long-term reliability and intrinsic safety of the entire battery system.

[0003] In existing technologies, pressure-sensitive adhesive tapes used in the aforementioned scenarios are typically based on acrylic-based pressure-sensitive adhesives, such as the traditional acrylic pressure-sensitive adhesive tapes disclosed in relevant patent documents. These tapes exhibit good initial tack, peel strength, and film-forming properties under normal temperature and physical conditions. However, when applied inside new energy batteries, they generally exhibit a severe deficiency in resistance to electrolyte chemical corrosion during actual service. The electrolyte system inside lithium-ion batteries typically uses lithium hexafluorophosphate (LiPF6) as the conductive lithium salt and highly polar organic carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) as mixed solvents. Existing acrylic-based pressure-sensitive adhesive tapes, when immersed in such highly polar organic solvents for extended periods, are prone to significant physical swelling and chemical degradation of their adhesive layers. This leads to a sharp decline in the interfacial adhesion between the tape and the substrate or cell surface, and may even cause complete loss of adhesion, arching, detachment, or delamination of the adhesive layer.

[0004] More seriously, during long-term charge-discharge cycles, the accumulation of heat and side reactions caused by trace amounts of moisture inevitably lead to the hydrolysis of LiPF6 in the electrolyte, producing highly corrosive acidic active substances such as hydrofluoric acid (HF). These chemical reactions are further exacerbated by high temperatures. Under the synergistic effect of these highly reactive chemicals and high temperatures, the low molecular weight components, incompletely cross-linked oligomers, or unstable ester bonds within the traditional pressure-sensitive adhesive layer are highly susceptible to chain breakage and dissolution. The precipitated substances diffuse into the electrolyte, inducing a deterioration of the battery's internal chemical environment, and even carbonization and discoloration at localized high temperatures. Particularly in processes involving localized bonding of narrow adhesive edges, delicate areas, or edges, the edge effect allows the electrolyte to more easily penetrate laterally from the adhesive tape edges, causing rapid failure of small bonded areas. This results in significant safety hazards such as electrode tab insulation failure and cell detachment, severely impacting the cycle life and overall quality of new energy batteries.

[0005] The fundamental reason for the aforementioned technological deficiencies lies in the fact that the backbone molecular structure of traditional acrylate polymers is mainly composed of copolymers of conventional alkyl acrylate monomers. The cohesive energy density of their macromolecular chain segments is highly similar to the solubility parameters of carbonate organic solvents, resulting in thermodynamically high miscibility and swelling. Simultaneously, their main and side chain structures exhibit poor chemical stability in strongly polar solvents and strongly acidic chemical environments, making them highly susceptible to penetration by small-molecule solvents, which can disrupt their physical and chemical cross-linking networks. Although those skilled in the art have attempted to increase the cross-linking density of the adhesive layer by simply increasing the amount of cross-linking agent, or by introducing conventional hard monomers to suppress swelling, they have encountered insurmountable technical bottlenecks in actual research and development: blindly increasing the cross-linking density hinders the movement of macromolecular chain segments, significantly reducing the wettability, initial tack, and high-temperature viscoelasticity of the pressure-sensitive adhesive, making it highly prone to substrate warping in the initial bonding stage; while introducing conventional hard monomers often increases the complexity of the process and cannot fundamentally prevent capillary penetration of strongly polar solvents at the interface.

[0006] Furthermore, with the upgrading of automated assembly processes, battery manufacturing has placed special construction requirements on the spacer tape, including the use of local structural designs such as "transparent windows." This allows online visual inspection systems to monitor the condition of critical processes such as ultrasonic welding of the electrode tabs, further increasing the difficulty of overall tape structural design and interfacial stress balance. Therefore, significantly improving the chemical stability, swelling resistance, interfacial integrity, and long-term electrical insulation retention of the pressure-sensitive adhesive in high-temperature electrolyte environments while maintaining excellent initial tack, film-forming workability, and specific local structures is a pressing and highly challenging technical problem that needs to be solved in the current new energy battery manufacturing field. Summary of the Invention

[0007] The first objective of this invention is to provide an electrolyte-resistant reinforced spacer tape for new energy batteries, comprising a release layer, a substrate layer, and an adhesive layer, wherein the adhesive layer is coated on one side of the substrate layer, and the release layer covers the outer surface of the adhesive layer. The adhesive layer is formed by coating and curing an electrolyte-resistant reinforced pressure-sensitive adhesive composition, which comprises the following components by weight: Fluorine-modified acrylate copolymer: 80-120 parts; Crosslinking agent: 0.5–5 parts; Oxygen-containing heterocyclic vinyl monomer modifier: 1-8 parts; Two-dimensional nano barrier filler: 0.5–6 parts; Organic solvent: 50-100 parts; The crosslinking agent includes a first thermal crosslinking agent and a second network precursor containing dynamic covalent bonds; after curing, the electrolyte-resistant reinforced pressure-sensitive adhesive composition forms an interpenetrating polymer network structure consisting of a main polymer network composed of the fluorinated modified acrylate copolymer and the first thermal crosslinking agent, and an elastic second network composed of the second network precursor. The two-dimensional nano barrier filler is a layered microparticle with surface organic modification, and is dispersed in situ in the interpenetrating polymer network structure.

[0008] Preferably, the adhesive layer is applied in a partially spaced manner on the substrate layer, forming adhesive-backed areas and non-adhesive-backed areas on the surface of the substrate layer. The non-adhesive area forms a transparent window on the tape.

[0009] The localized intermittent coating specifically includes any of the following structures: First spaced structure: The adhesive layer is divided into two parallel and continuous adhesive backing areas, located on both sides of the substrate layer, with a gap in the middle as a non-adhesive backing area. Second spaced structure: The adhesive layer is located only in the middle area of ​​the substrate layer, with the two side edges left empty as non-adhesive areas; The third type of spaced structure: the adhesive layer is a single adhesive-backed area located at a local edge position on one side of the substrate layer, with the remaining area left empty as a non-adhesive-backed area.

[0010] Preferably, by mass parts, the fluorinated modified acrylate copolymer is polymerized from the following monomers under the action of an initiator: Fluorinated acrylate monomer: 10-30 parts, wherein the fluorinated acrylate monomer is selected from at least one of trifluoroethyl acrylate, hexafluorobutyl methacrylate, and dodecafluoroheptyl acrylate; Soft monomer: 40-70 parts, wherein the soft monomer is selected from at least one of butyl acrylate and isooctyl acrylate; Hard monomer: 10-30 parts, wherein the hard monomer is selected from at least one of methyl acrylate, methyl methacrylate, and isobornyl acrylate; Functional monomer: 1 to 10 parts, wherein the functional monomer is selected from at least one of hydroxyethyl acrylate, acrylic acid, and glycidyl methacrylate.

[0011] Preferably, the oxygen-containing heterocyclic vinyl monomer modifier is selected from at least one vinyl monomer containing an epoxy group, a dioxane group, or a tetrahydrofuran group; The release layer is a non-silicone release agent layer with a release force of 25-80g / 25mm; The substrate layer is selected from polyethylene terephthalate film, polypropylene film or polyimide film, and has a thickness of 0.010 to 0.050 mm.

[0012] Preferably, the tape retains ≥90% of its peel strength after being immersed in lithium battery electrolyte containing lithium hexafluorophosphate at 85°C for 72 hours.

[0013] The second objective of this invention is to provide a method for preparing the aforementioned electrolyte-resistant reinforced spacer tape for new energy batteries, comprising the following steps: Step 1: Mix the fluorinated acrylate monomer, soft monomer, hard monomer and functional monomer, add part of the organic solvent and part of the initiator, and carry out a prepolymerization reaction under heating and an inert gas atmosphere; then add the remaining organic solvent and initiator to carry out the reaction at a constant temperature, and after the reaction is completed, cool down and discharge the material to obtain a copolymer solution; Step 2: Add the first thermal crosslinking agent, the second network precursor, the oxygen-containing heterocyclic vinyl monomer modifier, and the two-dimensional nano barrier filler to the copolymer solution obtained in Step 1, mix evenly, and obtain a pressure-sensitive adhesive composition. Step 3: Apply the pressure-sensitive adhesive composition to one side of the substrate layer; apply a non-silicone release agent to the other side of the substrate layer; dry and cure the coated substrate layer, and then roll it up and slit it to obtain the finished product.

[0014] Preferably, in step 2, the two-dimensional nano barrier filler is first dispersed in the second network precursor and subjected to high-shear stirring or ultrasonic exfoliation treatment before being added to form a pre-intercalated structure slurry, and then mixed with the copolymer solution.

[0015] Preferably, in step 3, the surface pretreatment of the substrate layer is corona treatment, and the surface tension of the treated substrate layer is ≥42dyn / cm.

[0016] Preferably, in step 3, the gradient oven is a multi-zone gradient oven, and the curing parameters of each zone of the oven satisfy the following: Low-temperature pre-drying zone: temperature 55-70℃, drying time 10-30s; Medium-temperature and medium-solid drying zone: temperature 75-125℃, drying time 10-30s; High-temperature deep-curing zone: temperature 125~140℃, drying time 30~60s; Stress relief zone: temperature 90-110℃, drying time 10-20s.

[0017] The present invention has the following beneficial effects: (1) Excellent resistance to electrolyte chemical stability and adhesion durability This invention introduces a specific fluorinated macromolecular structure into the pressure-sensitive adhesive composition, combined with an interpenetrating polymer network structure formed by multiple components, exhibiting extremely high chemical inertness and cohesive stress dissipation capability under extreme working conditions. This composite network effectively inhibits the penetration and swelling of highly polar organic carbonate solvents both thermodynamically and kinetically. Combined with the synergistic spatial barrier effect of surface-modified layered microparticles, the diffusion channels of small molecule active substances within the adhesive layer and at the bonding interface are blocked. Therefore, the tape maintains an extremely high peel strength retention rate even after long-term immersion in a high-temperature electrolyte environment, eliminating the risks of edge arching, loosening, and delamination.

[0018] (2) Unique macrostructure and applicability to engineering construction The uniquely designed localized, spaced coating structure of the product creates functionally partitioned adhesive-backed areas and adhesive-free transparent windows on the tape surface. This versatile, patterned design not only provides excellent visual observability at specific workstations, facilitating precise online inspection, but also optimizes stress distribution at the bonding edges without sacrificing core corrosion resistance and insulation performance, thus balancing interfacial peeling stress in automated assembly processes.

[0019] (3) Good process adaptability and stable film quality The preparation method employs stepwise polymerization, pre-intercalation hybridization, and multi-zone gradient temperature-controlled curing processes. By controlling the composition and regulating temperature and humidity stress at specific reaction stages, a high degree of synergistic coexistence between the organic polymer network and inorganic layered microparticles in the matrix is ​​achieved. This ensures deep cross-linking of the adhesive layer molecular network and efficient construction of interfacial bonding, resulting in a finished tape with excellent comprehensive viscoelasticity and electrical insulation. Attached Figure Description

[0020] Figure 1 The results are those of the spacer tape prepared in Example 1 of this invention, which was soaked in electrolyte for 24, 72, 120, and 192 hours and then baked in an oven at 85°C. Detailed Implementation

[0021] To better understand the present invention, the present invention will be further described below with reference to specific serial numbers. The terminology used in the serial numbers is for describing specific embodiments and does not constitute a limitation on the scope of protection of the present invention.

[0022] In the specific implementation methods, unless otherwise specified, the experimental methods used are all conventional methods, and the materials and reagents used are all commercially available unless otherwise specified.

[0023] Example 1 I. Experimental Materials and Proportions 1. Monomers for synthesizing fluorinated modified acrylate copolymers (by parts by mass): Hexafluorobutyl methacrylate: 15 parts; Butyl acrylate: 50 parts; Isooctyl acrylate: 10 parts; Methyl acrylate: 15 parts; Isoborneol acrylate: 5 parts; Hydroxyethyl acrylate: 3 parts; Acrylic acid: 2 parts.

[0024] 2. Electrolyte-resistant reinforced pressure-sensitive adhesive composition formulation (by parts by weight): The above-mentioned fluorinated modified acrylate copolymer (based on solid content): 100 parts; Hexamethylene diisocyanate trimer: 2.5 parts; A mixture of hydroxyl-terminated polydimethylsiloxane and long-chain polyols: 1.5 parts; Glycidyl methacrylate: 4 parts; Organically modified montmorillonite (surface modified with silane coupling agent): 3 parts; Ethyl acetate: 100 parts; Azobisisobutyronitrile (AIBN): 0.45 parts.

[0025] II. Preparation Steps The specific preparation process of the spacer tape described in this embodiment is as follows: Step 1: Preparation of fluorine-modified acrylate copolymer solution 15 parts of hexafluorobutyl methacrylate, 50 parts of butyl acrylate, 10 parts of isooctyl acrylate, 15 parts of methyl acrylate, 5 parts of isobornyl acrylate, 3 parts of hydroxyethyl acrylate, and 2 parts of acrylic acid were mixed evenly. Ethyl acetate (55 parts by mass) and initiator AIBN (0.20 parts by mass) were added, accounting for 55% of the total mass. The mixture was then heated to 75°C under a nitrogen atmosphere for a prepolymerization reaction for 3 hours.

[0026] Subsequently, the remaining 45 parts of ethyl acetate and 0.25 parts of initiator AIBN were slowly added to the reaction system, and the temperature was raised to 85 °C and the reaction was continued for 2.5 hours to ensure complete reaction.

[0027] After the reaction is complete, the temperature is lowered to below 40°C and the material is discharged to obtain a fluorinated modified acrylate copolymer solution with a solid content of approximately 35%.

[0028] Step 2: Formulate an electrolyte-resistant reinforced pressure-sensitive adhesive composition Weigh 3 parts of the surface-modified layered organic montmorillonite microparticles and add them to 1.5 parts of the second network precursor. Use a high-shear mixer to stir at 3000 r / min for 40 minutes, and then perform ultrasonic exfoliation treatment for 30 minutes to fully swell and exfoliate the layered microparticles to form a uniformly dispersed pre-intercalated structure slurry.

[0029] The pre-intercalated structure slurry prepared above was poured into the copolymer solution obtained in step 1, and then 2.5 parts of hexamethylene diisocyanate trimer and 4 parts of glycidyl methacrylate were added in sequence. The mixture was stirred continuously at room temperature until homogeneous to obtain an electrolyte-resistant reinforced pressure-sensitive adhesive composition.

[0030] Step 3: Coating and Curing A 0.025 mm thick polyethylene terephthalate (PET) film was selected as the substrate layer. First, the adhesive-coated surface of the substrate layer underwent online corona pretreatment to control the surface tension of the treated substrate layer to reach 52 dyn / cm.

[0031] Using a slit coating die with a preset spacing pattern, the pressure-sensitive adhesive composition prepared in step 2 is locally coated onto one side of the corona-treated substrate layer, with the wet film thickness controlled at 0.050 mm. The slit coating die forms a first-spaced structure (i.e., a hollowed-out type: the central 40% width area is a non-adhesive area to form a transparent window, and the two 30% width areas on each side are adhesive areas). Simultaneously, a non-silicone release agent is coated onto the other side of the substrate layer using a gravure coating method.

[0032] The coated continuous film is directly fed into a multi-zone (seven-zone) gradient oven for drying and in-situ interpenetrating network crosslinking and curing. The curing parameters for each zone of the oven are precisely controlled as follows: Low-temperature pre-drying zone: Zone 1 60℃×15s, Zone 2 80℃×15s; Medium temperature and medium solid load zone: Zone 3, 120℃ × 15s; High-temperature deep solidification zone: Zone 4 130℃×15s, Zone 5 130℃×15s, Zone 6 130℃×15s; Stress relief zone: Zone 7, 100℃ × 15s.

[0033] After drying and curing, the tape is cooled and continuously wound to obtain a master roll, which is then cut according to the battery process specifications to obtain the finished new energy battery spacer tape with a partially glue-free viewing window in the middle.

[0034] Example 2 I. Experimental Materials and Proportions 1. Monomers for synthesizing fluorinated modified acrylate copolymers (by parts by mass): Trifluoroethyl acrylate: 10 parts; Butyl acrylate: 70 parts; Methyl methacrylate: 19 parts; Glycidyl methacrylate: 1 part.

[0035] 2. Electrolyte-resistant reinforced pressure-sensitive adhesive composition formulation (by parts by weight): The above-mentioned fluorinated modified acrylate copolymer (based on solid content): 80 parts; Hexamethylene diisocyanate trimer: 0.5 parts; Elastic polyurethane oligomer containing hindered urea bonds: 0.5 parts; Acrylate monomers containing dioxane groups: 1 part; Organically modified layered double hydroxide (modified with silane coupling agent): 0.5 parts Ethyl acetate and toluene mixed solvent (1:1 mixture, organic solvent): 50 parts; Azobisisobutyronitrile (initiator): 0.2 parts.

[0036] II. Preparation Steps Step 1: Preparation of fluorine-modified acrylate copolymer solution Mix 10 parts of trifluoroethyl acrylate, 70 parts of butyl acrylate, 19 parts of methyl methacrylate, and 1 part of glycidyl methacrylate according to the formula until homogeneous. Add 25 parts of mixed solvent (50% by mass) and 0.08 parts of initiator (40% by mass) according to the total mass. Perform a prepolymerization reaction at 70°C for 4 hours in a carbon dioxide atmosphere.

[0037] Subsequently, the remaining 25 parts of mixed solvent and 0.12 parts of initiator were added to the reaction system, and the temperature was raised to 80°C and the reaction was continued for 3 hours. After the reaction was completed, the mixture was cooled and discharged to obtain a copolymer solution.

[0038] Step 2: Formulate an electrolyte-resistant reinforced pressure-sensitive adhesive composition 0.5 parts of surface-organically modified layered double hydroxide microparticles were added to 0.5 parts of elastic polyurethane oligomer containing hindered urea bonds and stirred under high shear at 4000 r / min for 30 minutes, followed by ultrasonic exfoliation for 25 minutes to form a uniformly dispersed pre-intercalated slurry.

[0039] The slurry was poured into the copolymer solution obtained in step 1, and then 0.5 parts of hexamethylene diisocyanate trimer and 1 part of acrylate monomer containing dioxane group were added. The mixture was stirred continuously and mixed evenly to obtain a pressure-sensitive adhesive composition.

[0040] Step 3: Coating and Curing A 0.015 mm thick polyimide (PI) film was selected as the substrate layer, and its adhesive surface was subjected to online corona pretreatment to achieve a surface tension of 45 dyn / cm.

[0041] Using a slit coating die, the pressure-sensitive adhesive composition is locally applied to one side of the substrate layer, controlling the wet film thickness to be 0.025 mm. The die is pre-patterned to form a second-spaced structure (i.e., a center-backed adhesive type: the central 60% width area is the adhesive area, and the two side edges are left empty as non-adhesive areas to form a transparent window). Simultaneously, a non-silicone release agent (with a release force of 30 g / 25 mm after curing) is applied to the other side of the substrate layer.

[0042] The coated film is then placed in a multi-zone gradient oven for drying and curing, with each zone meeting the following parameters: Low-temperature pre-drying zone: 55℃×30s; Medium temperature and medium solid temperature zone: 75℃×30s; High-temperature deep solidification zone: 125℃×30s; Stress relief zone: 90℃×20s.

[0043] After curing, the product is obtained by winding and slitting.

[0044] Example 3 I. Experimental Materials and Proportions 1. Monomers for synthesizing fluorinated modified acrylate copolymers (by parts by mass): Dodecafluoroheptyl acrylate: 30 parts; Isooctyl acrylate: 40 parts; Isoborneol acrylate: 20 parts; Acrylic acid: 10 parts.

[0045] 2. Electrolyte-resistant reinforced pressure-sensitive adhesive composition formulation (by parts by weight): The above-mentioned fluorinated modified acrylate copolymer (based on solid content): 120 parts; Polyethylene glycol diglycidyl ether: 5 parts; Oligomer precursors containing disulfide bonds: 5 parts; Vinyl monomers containing tetrahydrofuran groups: 8 parts; Organically modified montmorillonite: 6 parts; Ethyl acetate: 100 parts; Benzoyl peroxide (BPO, initiator): 0.8 parts.

[0046] II. Preparation Steps Step 1: Preparation of fluorine-modified acrylate copolymer solution Mix 30 parts of dodecafluoroheptyl acrylate, 40 parts of isooctyl acrylate, 20 parts of isobornyl acrylate and 10 parts of acrylic acid evenly, and add 60 parts of ethyl acetate (60% of the total mass) and 0.4 parts of initiator BPO (50% of the total mass).

[0047] The prepolymerization reaction was carried out at 85°C for 2 hours under an argon atmosphere. Then, the remaining 40 parts of ethyl acetate and 0.4 parts of initiator BPO were added to the reaction system, and the temperature was raised to 90°C for another 2 hours. After the reaction was completed, the mixture was cooled and discharged to obtain the copolymer solution.

[0048] Step 2: Formulate an electrolyte-resistant reinforced pressure-sensitive adhesive composition Six parts of surface-modified organic montmorillonite microparticles were added to five parts of an oligomeric polymer precursor containing disulfide bonds. The mixture was stirred under high shear at 5000 r / min for 50 minutes, followed by ultrasonic exfoliation for 40 minutes to form a uniformly dispersed pre-intercalated slurry.

[0049] The slurry was poured into the copolymer solution obtained in step 1, and then 5 parts of polyethylene glycol diglycidyl ether and 8 parts of vinyl monomers containing tetrahydrofuran groups were added. The mixture was stirred and mixed evenly to obtain a pressure-sensitive adhesive composition.

[0050] Step 3: Coating and Curing A 0.040 mm thick polypropylene (PP) film was selected as the substrate layer, and its adhesive surface was subjected to online corona pretreatment to achieve a surface tension of 42 dyn / cm.

[0051] The pressure-sensitive adhesive composition is locally coated onto one side of the substrate layer using a slit coating die, and the wet film thickness is controlled to be 0.075 mm. The die is pre-patterned to form a third-interval structure (i.e., single-sided adhesive type: 75% of the width of one side is the adhesive area, and the remaining 25% of the width is left empty as a non-adhesive area to form a transparent window).

[0052] Meanwhile, a non-silicone release agent is applied to the other side of the substrate layer (the release force after curing is 75°g / 25mm).

[0053] The coated film is then placed in a multi-zone gradient oven for drying and curing, with each zone meeting the following parameters: Low-temperature pre-drying zone: 70℃×10s; Medium temperature and medium solid temperature zone: 125℃×10s; High-temperature deep solidification zone: 140℃×40s; Stress relief zone: 110℃×15s.

[0054] After curing, the product is obtained by winding and slitting.

[0055] Example 4 I. Experimental Materials and Proportions 1. Monomers for synthesizing fluorinated modified acrylate copolymers (by parts by mass): Hexafluorobutyl methacrylate: 20 parts; Butyl acrylate: 30 parts; Isooctyl acrylate: 20 parts; Methyl methacrylate: 15 parts; Isoborneol acrylate: 10 parts; Hydroxyethyl acrylate: 5 parts.

[0056] 2. Electrolyte-resistant reinforced pressure-sensitive adhesive composition formulation (by parts by weight): The above-mentioned fluorinated modified acrylate copolymer (based on solid content): 100 parts; Mixture of epoxy crosslinking agent and isocyanate crosslinking agent: 2.0 parts; Oligomeric siloxane diols containing reversible disulfide bonds: 2.0 parts; Glycidyl methacrylate: 5 parts; Organically modified layered kaolin microparticles: 3.5 parts; Ethyl acetate (organic solvent): 80 parts; Azobisisobutyronitrile (initiator): 0.5 parts.

[0057] II. Preparation Steps Step 1: Preparation of fluorine-modified acrylate copolymer solution Mix all comonomers in the specified amounts thoroughly, then add 50 parts ethyl acetate and 0.2 parts initiator. Prepolymerize at 80°C for 3 hours under a nitrogen atmosphere. Then add the remaining 30 parts ethyl acetate and 0.3 parts initiator, and continue the reaction at 85°C for another 3 hours.

[0058] After the reaction is complete, the material is cooled and discharged to obtain a copolymer solution.

[0059] Step 2: Formulate an electrolyte-resistant reinforced pressure-sensitive adhesive composition 3.5 parts of organically modified layered kaolin microparticles were added to 2.0 parts of oligomeric siloxane diol containing reversible disulfide bonds and stirred under high shear at 3500 r / min for 45 minutes, followed by ultrasonic exfoliation for 30 minutes to form a pre-intercalated slurry.

[0060] The slurry was poured into the copolymer solution, followed by the addition of 2.0 parts of the first thermal crosslinking agent and 5 parts of glycidyl methacrylate. The mixture was stirred continuously until homogeneous to obtain the pressure-sensitive adhesive composition.

[0061] Step 3: Coating and Curing A 0.030 mm thick polyethylene terephthalate (PET) film was selected as the substrate layer, and the adhesive surface was corona treated to achieve a surface tension of 48 dyn / cm.

[0062] The pressure-sensitive adhesive composition is locally applied to one side of the substrate surface using a slit coating die (adopting the first spaced structure as in Example 1), with the wet film thickness controlled at 0.045 mm. Simultaneously, a non-silicone release agent (with a release force of 45 g / 25 mm after curing) is applied to the other side of the substrate surface.

[0063] The coated film is then placed in a multi-zone gradient oven for drying and curing, with each zone meeting the following parameters: Low-temperature pre-drying zone: 65℃ × 20s; Medium temperature and medium solid temperature zone: 100℃ × 20s; High-temperature deep solidification zone: 130℃×45s; Stress relief zone: 100℃ × 15s.

[0064] After curing, the product is obtained by winding and slitting.

[0065] Comparative Example 1 This comparative example provides a new energy battery spacer tape as a control group. Its formula and process are exactly the same as those in Example 1. The main difference is that two-dimensional nano barrier filler is not introduced (i.e., the mass fraction of two-dimensional nano barrier filler in the formula is 0 parts).

[0066] Preparation steps Step 1: Preparation of fluorine-modified acrylate copolymer solution The process parameters, such as monomer ratio, solvent and initiator feeding ratio, two-step reaction temperature and time, are exactly the same as step 1 of Example 1. After cooling and discharging, a fluorinated modified acrylate copolymer solution with a solid content of about 35% is obtained.

[0067] Step 2: Prepare the pressure-sensitive adhesive composition Since no two-dimensional nano-barrier filler is added, the high-shear stirring and ultrasonic stripping of the slurry are omitted in this step. 1.5 parts of the second network precursor, 2.5 parts of hexamethylene diisocyanate trimer (first thermal crosslinking agent) and 4 parts of glycidyl methacrylate (oxygen-containing heterocyclic vinyl monomer modifier) ​​are directly weighed and poured into the copolymer solution obtained in step 1. The mixture is stirred continuously at room temperature until homogeneous to obtain the pressure-sensitive adhesive composition.

[0068] Step 3: Coating and Curing The selection of the substrate (PET film with a thickness of 0.025 mm), the online corona pretreatment parameters (surface tension 52 dyn / cm), the slit coating pattern and wet film thickness (0.050 mm) of the first spaced structure (hollowed-out type), the coating of the non-silicone release agent on the back side, and the temperature control curing parameters of the multi-zone (seven-zone) gradient oven are all exactly the same as step 3 of Example 1.

[0069] After drying, curing, winding, and slitting, the control group tape product is obtained.

[0070] Comparative Example 2 This comparative example provides a new energy battery spacer tape as a control group. Its formula and process are basically the same as those in Example 1. The main difference is that a second network precursor containing dynamic covalent bonds is not introduced (i.e., the mass fraction of the second network precursor in the formula is 0 parts), so it is impossible to construct an interpenetrating polymer network structure.

[0071] Preparation steps Step 1: Preparation of fluorine-modified acrylate copolymer solution The monomer ratio and reaction polymerization process are exactly the same as step 1 of Example 1. After cooling and discharging, a fluorinated modified acrylate copolymer solution with a solid content of about 35% is obtained.

[0072] Step 2: Prepare the pressure-sensitive adhesive composition Since no second network precursor is added, in this step, 3 parts of organically modified montmorillonite (two-dimensional nano barrier filler) are directly added to part of the ethyl acetate solvent for high-shear stirring (3000 r / min, 40 minutes) and ultrasonic exfoliation treatment (30 minutes) to prepare filler dispersion slurry.

[0073] The filler dispersion slurry was then poured into the copolymer solution obtained in step 1, and 2.5 parts of hexamethylene diisocyanate trimer (first thermal crosslinking agent) and 4 parts of glycidyl methacrylate (oxygen-containing heterocyclic vinyl monomer modifier) ​​were added in sequence. The mixture was stirred and mixed evenly to obtain a pressure-sensitive adhesive composition with a conventional single chemical crosslinking network.

[0074] Step 3: Coating and Curing The substrate layer specifications and corona treatment parameters, the interval coating method and geometric pattern design, and the temperature and time control parameters of the multi-zone (seven-zone) gradient oven are all exactly the same as step 3 of Example 1.

[0075] Due to the lack of a second network precursor, the curing reaction is only a single thermal crosslinking reaction between the main fluorinated modified acrylate copolymer and the first thermal crosslinking agent.

[0076] After drying, curing, winding, and slitting, the control group tape product is obtained.

[0077] Test Example 1 I. Specific Methods of Performance Testing 1. Initial 180° peel force test Test standard: Refer to GB / T2792 standard.

[0078] Test method: Under normal temperature conditions (23±2℃, relative humidity 50±5%), the finished tape to be tested is precisely cut into samples with a width of 25mm and a length of 200mm. A 2kg standard roller is used to repeatedly press and adhere the tape to a SUS304 stainless steel plate three times. After standing for 20 minutes, an electronic tensile testing machine is used to perform a 180° peel test at a speed of 300mm / min, and the initial peel force F0 (unit: N / 25mm) is recorded.

[0079] 2. Electrolyte resistance to long-term gradient immersion and appearance reliability test Test method: Each finished tape sample was neatly and flatly applied to the surface of a standard aluminum foil and compacted three times using a 2kg standard roller. Subsequently, the aluminum foil sample with the tape was completely immersed in a sealed bottle containing a standard electrolyte for new energy lithium batteries (electrolyte system: using 1mol / L LiPF6 as the conductive lithium salt, and a mixture of strongly polar organic carbonates in a mass ratio of EC / DEC / DMC of 1:1:1 as the solvent).

[0080] Gradient operation: The sealed bottles were placed in an 85°C constant temperature oven for high-temperature immersion accelerated aging test. The sealed bottles were removed from the oven in batches at four specific time points: 24 hours, 72 hours, 120 hours and 192 hours of immersion.

[0081] Data and Appearance Processing: Remove the sample and wipe the aluminum foil and tape surfaces dry with absorbent paper to remove any residual electrolyte. Let it stand at room temperature for 2 hours. First, visually observe and record whether there is swelling, discoloration, arching, or delamination at the adhesive layer and bonding interface. Then, measure the 180° peel force Ft again according to Test Method 1 (t is the corresponding immersion hours) and calculate the corresponding electrolyte peel force retention rate.

[0082] 3. Breakdown voltage (electrical insulation) test Test standard: Refer to GB / T1408.1 standard.

[0083] Test method: Using a withstand voltage tester, under the conditions of 60Hz AC power and continuous voltage increase rate of 100V / s, the breakdown voltage of the unsoaked finished tape and the finished tape after long-term immersion in 85℃ electrolyte were tested, and the limit voltage value (unit: KV) at which electrical breakdown occurred was recorded.

[0084] The results are shown in Tables 1 and 2.

[0085] Table 1

[0086] Table 2

[0087] The results of soaking the spacer tape prepared in Example 1 of this invention in electrolyte for 24, 72, 120, and 192 hours and then baking it in an oven at 85°C are as follows: Figure 1 As shown.

[0088] As shown in Tables 1 and 2, in the control group samples (Comparative Examples 1 and 2) without structural modification, the lack of effective spatial barrier and stress dissipation mechanisms during long-term immersion in high-temperature electrolyte allowed polar carbonate solvent molecules to easily penetrate and diffuse into the macromolecular linear chains or single cross-linked networks. This solvent intrusion triggered polymer swelling, leading to a decrease in the cohesive strength of the adhesive layer. Under high-temperature stress, this manifested macroscopically as edge arching, delamination, and even dissolution and detachment of the adhesive layer. Simultaneously, the polar conductive lithium salts introduced with the solvent disrupted the dielectric environment of the adhesive layer, resulting in a significant reduction in its breakdown voltage.

[0089] In contrast, the samples in the embodiments of the present invention exhibited stable chemical inertness and structural integrity during the extreme long-term immersion test of 192 hours. The mechanism of action is as follows: On the one hand, the interpenetrating polymer network (IPN) structure constructed after the composition is cured significantly improves the elastic recovery force and cohesive stress dissipation capacity of the adhesive layer through the microscopic topological entanglement of the two networks and the introduction of reversible dynamic covalent bonds, and inhibits the unrestricted swelling of macromolecular chain segments at the thermodynamic and kinetic levels. On the other hand, the in-situ exfoliated and dispersed two-dimensional nano barrier filler forms a rigid sheet array in the interpenetrating network structure, constructing a rigid physical barrier channel with high tortuosity inside the adhesive layer, which significantly prolongs the lateral capillary penetration path of small molecules and active ions of electrolyte solvent and delays electrochemical erosion at the interface.

[0090] In summary, this solid design, which combines a polymer topological network with inorganic nanosheets in situ, creates a complementary rigid-flexible effect at the microscopic level. This effect, in macroscopic testing, not only effectively prevents the degradation of interfacial adhesion by the high-temperature electrolyte, allowing the tape to maintain a high peel strength retention rate and a long-lasting stable appearance of "no discoloration, no arching, and no delamination" even under extreme working conditions of 192 hours, but also effectively maintains the electrical insulation integrity of the adhesive layer.

[0091] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A electrolyte-resistant reinforced spacer tape for new energy batteries, characterized in that, It comprises a release layer, a substrate layer and an adhesive layer in sequence, wherein the adhesive layer is coated on one side of the substrate layer and the release layer covers the outer surface of the adhesive layer; The adhesive layer is formed by coating and curing an electrolyte-resistant reinforced pressure-sensitive adhesive composition, which comprises the following components by weight: Fluorine-modified acrylate copolymer: 80-120 parts; Crosslinking agent: 0.5–5 parts; Oxygen-containing heterocyclic vinyl monomer modifier: 1-8 parts; Two-dimensional nano barrier filler: 0.5–6 parts; Organic solvent: 50-100 parts; The crosslinking agent includes a first thermal crosslinking agent and a second network precursor containing dynamic covalent bonds; after curing, the electrolyte-resistant reinforced pressure-sensitive adhesive composition forms an interpenetrating polymer network structure consisting of a main polymer network composed of the fluorinated modified acrylate copolymer and the first thermal crosslinking agent, and an elastic second network composed of the second network precursor. The two-dimensional nano barrier filler is a layered microparticle with surface organic modification, and is dispersed in situ in the interpenetrating polymer network structure.

2. The electrolyte-resistant reinforced spacer tape for new energy batteries according to claim 1, characterized in that, The adhesive layer is applied in a partially spaced manner on the substrate layer, forming adhesive-backed areas and non-adhesive-backed areas on the surface of the substrate layer. The non-adhesive area forms a transparent window on the tape.

3. The electrolyte-resistant reinforced spacer tape for new energy batteries according to claim 2, characterized in that, The localized intermittent coating specifically includes any of the following structures: First spaced structure: The adhesive layer is divided into two parallel and continuous adhesive backing areas, located on both sides of the substrate layer, with a gap in the middle as a non-adhesive backing area. Second spaced structure: The adhesive layer is located only in the middle area of ​​the substrate layer, with the two side edges left empty as non-adhesive areas; The third type of spaced structure: the adhesive layer is a single adhesive-backed area located at a local edge position on one side of the substrate layer, with the remaining area left empty as a non-adhesive-backed area.

4. The electrolyte-resistant reinforced spacer tape for new energy batteries according to claim 1, characterized in that, By weight, the fluorinated modified acrylate copolymer is polymerized from the following monomers under the action of an initiator: Fluorinated acrylate monomer: 10-30 parts, wherein the fluorinated acrylate monomer is selected from at least one of trifluoroethyl acrylate, hexafluorobutyl methacrylate, and dodecafluoroheptyl acrylate; Soft monomer: 40-70 parts, wherein the soft monomer is selected from at least one of butyl acrylate and isooctyl acrylate; Hard monomer: 10-30 parts, wherein the hard monomer is selected from at least one of methyl acrylate, methyl methacrylate, and isobornyl acrylate; Functional monomer: 1 to 10 parts, wherein the functional monomer is selected from at least one of hydroxyethyl acrylate, acrylic acid, and glycidyl methacrylate.

5. The electrolyte-resistant reinforced spacer tape for new energy batteries according to claim 1, characterized in that, The oxygen-containing heterocyclic vinyl monomer modifier is selected from at least one vinyl monomer containing an epoxy group, a dioxane group, or a tetrahydrofuran group. The release layer is a non-silicone release agent layer with a release force of 25-80g / 25mm; The substrate layer is selected from polyethylene terephthalate film, polypropylene film or polyimide film, and has a thickness of 0.010 to 0.050 mm.

6. The electrolyte-resistant reinforced spacer tape for new energy batteries according to claim 1, characterized in that, The tape retains ≥90% of its peel strength after being immersed in lithium battery electrolyte containing lithium hexafluorophosphate at 85°C for 72 hours.

7. A method for preparing an electrolyte-resistant reinforced spacer tape for new energy batteries as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Mix the fluorinated acrylate monomer, soft monomer, hard monomer and functional monomer, add part of the organic solvent and part of the initiator, and carry out a prepolymerization reaction under heating and an inert gas atmosphere; then add the remaining organic solvent and initiator to carry out the reaction at a constant temperature, and after the reaction is completed, cool down and discharge the material to obtain a copolymer solution; Step 2: Add the first thermal crosslinking agent, the second network precursor, the oxygen-containing heterocyclic vinyl monomer modifier, and the two-dimensional nano barrier filler to the copolymer solution obtained in Step 1, mix evenly, and obtain a pressure-sensitive adhesive composition. Step 3: Apply the pressure-sensitive adhesive composition to one side of the substrate layer; apply a non-silicone release agent to the other side of the substrate layer; dry and cure the coated substrate layer, and then roll it up and slit it to obtain the finished product.

8. The preparation method according to claim 7, characterized in that, In step 2, the two-dimensional nano barrier filler needs to be dispersed in the second network precursor and subjected to high-shear stirring or ultrasonic exfoliation treatment before being added to form a pre-intercalated structure slurry, and then mixed with the copolymer solution.

9. The preparation method according to claim 7, characterized in that, In step 3, the surface pretreatment of the substrate layer is corona treatment, and the surface tension of the treated substrate layer is ≥42dyn / cm.

10. The preparation method according to claim 7, characterized in that, In step 3, the gradient oven is a multi-zone gradient oven, and the curing parameters of each zone of the oven satisfy the following: Low-temperature pre-drying zone: temperature 55-70℃, drying time 10-30s; Medium-temperature and medium-solid drying zone: temperature 75-125℃, drying time 10-30s; High-temperature deep-curing zone: temperature 125~140℃, drying time 30~60s; Stress relief zone: temperature 90-110℃, drying time 10-20s.

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