Composite temperature measuring film, and preparation method and application thereof
By designing a composite temperature-sensing film and utilizing a combination of thermocouple arrays and specific materials, the problem of full coverage of temperature sensors in lithium-ion battery thermal runaway testing was solved, enabling stable monitoring and data acquisition in high-temperature environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SVOLT ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2023-08-31
- Publication Date
- 2026-06-09
Smart Images
Figure CN117162536B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery technology, and more specifically, to a composite temperature-sensing thin film, its preparation method, and its application. Background Technology
[0002] New energy vehicles powered by lithium-ion batteries have become a hot topic in the industry, and major international automakers have made large-scale investments in this area. However, safety remains a major obstacle to the application of high-capacity lithium-ion batteries in electric vehicles, energy storage power stations, and other new energy technologies. Essentially, the safety issue of lithium-ion batteries is a thermal issue. Improper use or manufacturing defects can lead to an increase in internal temperature during use and storage. High temperatures trigger a series of exothermic reactions, and the heat generated further exacerbates these reactions, accelerating their rate and ultimately leading to thermal runaway.
[0003] The root cause of thermal runaway is mostly the propagation of thermal runaway from a single cell, leading to severe damage to the entire battery system. This propagation is not accidental; because lithium-ion batteries currently have low thermal stability and are somewhat flammable, the enormous heat released by a single cell's thermal runaway can easily spread between cells, ultimately affecting the entire battery system. To solve the thermal runaway problem of battery modules or battery systems, it is necessary to start with the propagation patterns of thermal runaway to guide the safety design of battery modules and systems. Currently, thermal runaway testing of modules cannot achieve full coverage of surface contact temperature monitoring between batteries. Generally, only a few temperature sensors are used, and there are also issues such as the battery insulation film breaking down as the temperature rises, causing the thermocouple attached between two batteries to become a conductor, triggering unexpected battery short circuits and leading to verification failure. Alternatively, as thermal runaway progresses, the temperature rises and the battery undergoes irregular deformation, causing the contact area between the thermocouple attached to the battery surface and the temperature measuring surface to decrease sharply, or even detach prematurely. This directly results in the inability to effectively monitor the characteristic temperature during thermal runaway, leading to distorted data curves. Moreover, traditional temperature sensors cannot withstand the contact burning of flames during thermal runaway. At this time, the sensor fails, the temperature cannot be collected, and the process monitoring is terminated prematurely.
[0004] In view of this, the present invention is hereby proposed. Summary of the Invention
[0005] One objective of this invention is to provide a composite temperature sensing film that can achieve full coverage of the temperature sensor on each cell contact surface when used for battery thermal runaway testing; it has good flame retardant properties, suitable compression deformation, and good thermal conductivity, thus solving the problem of traditional sensors being prone to failure.
[0006] Another objective of this invention is to provide a method for preparing the composite temperature-sensing film, which, through the coordination of each step, yields a composite temperature-sensing film with good flame retardant properties, good thermal conductivity, and stable structure, and can achieve full coverage of the temperature sensor on each cell contact surface during thermal runaway testing.
[0007] Another object of the present invention is to provide an application of the aforementioned composite temperature-sensing film in battery testing.
[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:
[0009] A composite temperature-sensing film includes a first film layer, a temperature-sensing arrangement layer, and a second film layer, wherein the temperature-sensing arrangement layer is located between the first film layer and the second film layer; the temperature-sensing arrangement layer includes a plurality of thermocouples, wherein the temperature-sensing elements of the plurality of thermocouples are arranged in an array.
[0010] Both the first and second film layers comprise polymer thermally conductive materials, inorganic thermally conductive fillers, and flame-retardant materials, with the mass ratio of the polymer thermally conductive materials, inorganic thermally conductive fillers, and flame-retardant materials being (30-45):(20-40):(2-5).
[0011] In one embodiment, the polymer thermally conductive material includes at least one selected from polyurethane resin, epoxy resin, polyaniline, polyvinylidene fluoride, polystyrene, polypropylene, and polyimide.
[0012] In one embodiment, the inorganic thermally conductive filler includes at least one of alumina, magnesium oxide, zinc oxide, aluminum nitride, and silicon carbide.
[0013] In one embodiment, the flame retardant material includes at least one of organophosphorus flame retardant additives, nitrogen-containing compound flame retardant additives, halogenated carbonate flame retardant additives, silicon-based flame retardant additives, and composite flame retardant additives.
[0014] In one embodiment, the first film layer and the second film layer have the same composition, and the mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler and the flame-retardant material is the same.
[0015] In one embodiment, the thickness of both the first film layer and the second film layer is 0.5 to 10 mm.
[0016] In one embodiment, the temperature sensing wires of the thermocouples are not connected to each other; one end of the temperature sensing wire away from the temperature sensing element extends to the outside of the first film layer and the first film layer.
[0017] In one embodiment, the thermocouple includes at least one of type K, type S, type E, type N, type J, type T, type R and type B.
[0018] The method for preparing the composite temperature-sensing thin film includes the following steps:
[0019] (a) The first mixture system is sprayed onto the substrate and then dried to form a first film layer;
[0020] (b) A plurality of temperature measuring points are pre-set on the surface of the first film layer in an array, a plurality of thermocouples are laid on the surface of the first film layer, and the temperature sensing element of each thermocouple is respectively connected to the temperature measuring point to form a temperature sensing arrangement layer.
[0021] (c) The second mixture system is sprayed onto the surface of the temperature-sensitive arrangement layer and the first film layer, and then dried in the second stage to form the second film layer;
[0022] Both the first and second mixed systems include polymer thermally conductive materials, inorganic thermally conductive fillers, flame-retardant materials, and polar solvents.
[0023] In one embodiment, the preparation method of the first mixed system and the second mixed system specifically includes: performing a first mixing treatment on a polymer thermally conductive material and a first polar solvent to obtain a first material; performing a second mixing treatment on an inorganic thermally conductive filler and a second polar solvent to obtain a second material; mixing the first material and the second material to obtain a third material; adding a flame retardant and a third polar solvent to the third material, and then performing a third mixing treatment to obtain a fourth material, wherein a portion of the fourth material is used as the first mixed system and a portion of the fourth material is used as the second mixed system.
[0024] In one embodiment, by mass parts, the polymer thermally conductive material is 30-45 parts, the inorganic thermally conductive filler is 20-40 parts, the flame retardant material is 2-5 parts, the first polar solvent is 10-20 parts, the second polar solvent is 10-15 parts, and the third polar solvent is 3-5 parts.
[0025] In one embodiment, the first polar solvent, the second polar solvent, and the third polar solvent each include at least one of acetonitrile, tetrahydrofuran, ethanol, toluene, acetone, isopropanol, and dimethyl sulfoxide.
[0026] In one embodiment, the stirring speed of the first mixing process is 1000-3000 rpm, the linear velocity is 2.6-8 m / s, the stirring temperature is 25-60℃, and the stirring time is 1-4 h.
[0027] In one embodiment, the stirring speed of the second mixing process is 2000-4500 rpm, the linear velocity is 5-12 m / s, the stirring temperature is 25-60℃, and the stirring time is 0.5-1.5 h.
[0028] In one embodiment, the stirring speed of the third mixing process is 1000-4500 rpm, the linear velocity is 2.6-12 m / s, the stirring temperature is 25-60℃, and the stirring time is 0.5-1 h.
[0029] In one embodiment, the vacuum degree of both the first drying and the second drying is 13-26 Pa, the temperature is 50-80°C, and the time is 0.5-2 h.
[0030] In one embodiment, the composite temperature-sensing film is used in battery testing.
[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0032] (1) The present invention combines a thermocouple with a specific first film layer and a second film layer to obtain a composite temperature measuring film. When the composite film is used for battery thermal runaway testing, the temperature sensor can fully cover each cell contact surface. It has good flame retardant properties, suitable compression deformation, and good thermal conductivity, which can solve the problem of traditional sensors being prone to failure. It can ensure the integrity of structure and function during severe thermal runaway testing.
[0033] (2) The preparation method of the composite temperature measuring film of the present invention is beneficial to ensure the structural stability, thermal conductivity and flame retardant properties of the composite temperature measuring film. It can achieve full coverage of the battery temperature sensor on each cell contact surface during thermal runaway testing, which can overcome the problem of traditional sensors being prone to failure. It provides a feasible experimental solution for developing a method to obtain comprehensive temperature monitoring data of the battery when thermal runaway occurs.
[0034] (3) The composite temperature-measuring film of the present invention can be applied to battery testing, such as thermal runaway testing. It can achieve full coverage of surface contact temperature monitoring between batteries during thermal runaway testing of battery modules or battery systems. Moreover, it can avoid sensor failure. By observing the state changes of the sample during the test process and analyzing the obtained data, a complete understanding of the changes of the power battery in each stage of thermal runaway can be formed, which can improve the evaluation method of power batteries. At the same time, it can also be extended to other tests with similar surface temperature measurement requirements. Attached Figure Description
[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0036] Figure 1This is a schematic diagram of the composite temperature-sensing film of the present invention;
[0037] Figure 2 This is a schematic diagram of the temperature sensing line distribution in the temperature sensing arrangement layer of the composite temperature measuring film of the present invention;
[0038] Figure 3 This is a schematic diagram of the connection of the test platform of the present invention.
[0039] Figure label:
[0040] 100-Composite temperature measuring film, 200-Single battery cell, 300-Heat insulation component, 400-Test fixture, 1-First film layer, 2-Temperature sensing arrangement layer, 202-Temperature sensing line, 201-Temperature sensing element, 3-Second film layer. Detailed Implementation
[0041] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0042] According to one aspect of the present invention, the present invention relates to a composite temperature sensing film, comprising a first film layer, a temperature sensing arrangement layer, and a second film layer, wherein the temperature sensing arrangement layer is located between the first film layer and the second film layer; the temperature sensing arrangement layer comprises a plurality of thermocouples, wherein the temperature sensing elements of the plurality of thermocouples are arranged in an array.
[0043] Both the first and second film layers comprise polymer thermally conductive materials, inorganic thermally conductive fillers, and flame-retardant materials, with the mass ratio of the polymer thermally conductive materials, inorganic thermally conductive fillers, and flame-retardant materials being (30-45):(20-40):(2-5).
[0044] This invention combines a thermocouple with specific first and second film layers to obtain a composite temperature-sensing film. This composite film, when used for battery thermal runaway testing, ensures full coverage of the temperature sensor at each cell contact surface. It maintains structural and functional integrity during severe thermal runaway testing, exhibits good flame retardancy, suitable compression deformation, and good thermal conductivity, thus solving the problem of traditional sensors being prone to failure. This invention measures its thermal conductivity, flame retardancy rating, and compression deformation; by converting the thermal conductivity to temperature, the actual surface temperature of the battery can be obtained.
[0045] This invention utilizes a suitable ratio of polymer thermally conductive material, inorganic thermally conductive filler, and flame-retardant material to further enhance the thermal conductivity, overall structural stability, and flame-retardant properties of the temperature-sensing film. In one embodiment, the mass ratio of the polymer thermally conductive material, inorganic thermally conductive filler, and flame-retardant material includes, but is not limited to, 30:20:2, 35:25:2, 40:35:3, and 45:40:5.
[0046] In one embodiment, the polymer thermally conductive material includes at least one selected from polyurethane resin, epoxy resin, polyaniline, polyvinylidene fluoride, polystyrene, polypropylene, and polyimide. The present invention employs any one or at least two of the above-mentioned polymer thermally conductive materials, such as a combination of polyurethane resin and epoxy resin, or a combination of polyvinylidene fluoride and polystyrene.
[0047] In one embodiment, the inorganic thermally conductive filler includes at least one selected from alumina, magnesium oxide, zinc oxide, aluminum nitride, and silicon carbide. This invention employs any one or at least two of the above-mentioned inorganic thermally conductive fillers. In one embodiment, the inorganic thermally conductive filler comprises 60%–80% of a first filler and 20%–40% of a second filler, wherein the first filler is silicon carbide, and the second filler is at least one selected from alumina, magnesium oxide, zinc oxide, and aluminum nitride. This invention, through the combination of the above-mentioned inorganic thermally conductive fillers, can improve the thermal conductivity and mechanical properties of the composite film.
[0048] In one embodiment, the flame-retardant material includes at least one of organophosphorus flame-retardant additives, nitrogen-containing compound flame-retardant additives, halogenated carbonate flame-retardant additives, silicon-based flame-retardant additives, and composite flame-retardant additives. Adding an appropriate amount of the above-mentioned thermally conductive flame-retardant agent in this invention helps to ensure the flame-retardant effect of the composite temperature-sensing film. In one embodiment, the organophosphorus flame-retardant additive includes at least one of phosphate esters, phosphites, ammonium polyphosphate, phosphatidyl phosphate, and tricresyl phosphate. The nitrogen-containing compound flame-retardant additive includes at least one of melamine, dicyandiamide, guanidine salts, and their derivatives. The halogenated carbonate flame-retardant additive includes at least one of brominated carbonates, fluorocarbonates, brominated epoxy resins, and chlorinated paraffins. The silicon-based flame-retardant additive includes at least one of polysiloxanes, organosilicon epoxy resins, and methylphenyl dimethyldiethoxysilane (MPBMDS).
[0049] In one embodiment, the first film layer and the second film layer have the same composition, and the mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler and the flame-retardant material is the same.
[0050] In one embodiment, the thickness of both the first film layer and the second film layer is 0.5 to 10 mm; in another embodiment, the thickness of the first film layer is 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc., and the thickness of the second film layer is 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm, etc.
[0051] In one embodiment, the temperature sensing wires of the thermocouples are not overlapped; the end of the temperature sensing wire away from the temperature sensing element extends to the outside of the first film layer and is connected to the temperature sampling device. This invention aims to minimize unnecessary overlap between the temperature sensing wires, i.e., ensuring that the thermocouple wires are not overlapped to prevent uneven or excessively thick temperature sensing film thickness. This, in turn, allows the composite temperature sensing film to possess better mechanical properties, thermal conductivity, and flame retardant properties, resulting in better monitoring performance in battery testing.
[0052] In one embodiment, the thermocouple includes at least one of type K (nickel-silicon or nickel-aluminum), type S (platinum-rhodium 10%-platinum), type E (nickel-chromium-copper-nickel), type N (nickel-chromium-silicon-nickel-silicon), type J (iron-copper-nickel), type T (copper-copper-nickel), type R (platinum-rhodium 13%-platinum), and type B (platinum-rhodium 30%-platinum-rhodium 6%).
[0053] According to another aspect of the present invention, the present invention also relates to a method for preparing the aforementioned composite temperature-sensing thin film, comprising the following steps:
[0054] (a) The first mixture system is sprayed onto the substrate, and then dried and cured to form a first film layer;
[0055] (b) A plurality of temperature measuring points are pre-set on the surface of the first film layer in an array, a plurality of thermocouples are laid on the surface of the first film layer, and the temperature sensing element of each thermocouple is respectively connected to the temperature measuring point to form a temperature sensing arrangement layer.
[0056] (c) The second mixture system is sprayed onto the surface of the temperature-sensitive arrangement layer and the first film layer, and then dried and cured to form the second film layer;
[0057] Both the first and second mixed systems include polymer thermally conductive materials, inorganic thermally conductive fillers, flame-retardant materials, and polar solvents.
[0058] The present invention uses the above method to prepare a composite temperature sensing film, which is beneficial to ensuring the structural stability, thermal conductivity and flame retardant properties of the composite temperature sensing film. It can achieve full coverage of the battery temperature sensor on each cell contact surface during thermal runaway testing, which can overcome the problem of traditional sensors being prone to failure. It provides a feasible experimental solution for developing a method to obtain comprehensive temperature monitoring data of the battery during thermal runaway.
[0059] In one embodiment, the preparation method of the first mixed system and the second mixed system specifically includes: performing a first mixing treatment on a polymer thermally conductive material and a first polar solvent to obtain a first material; performing a second mixing treatment on an inorganic thermally conductive filler and a second polar solvent to obtain a second material; mixing the first material and the second material to obtain a third material; adding a flame retardant and a third polar solvent to the third material, and then performing a third mixing treatment to obtain a fourth material, wherein a portion of the fourth material is used as the first mixed system and a portion of the fourth material is used as the second mixed system.
[0060] By using the specific feeding sequence described above, the present invention can make the first and second mixing systems more uniform and stable, which is more conducive to ensuring the mechanical properties, flame retardant properties, and thermal conductivity of the composite temperature measuring film.
[0061] In one embodiment, by mass parts, the polymer thermally conductive material is 30-45 parts, for example 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 45 parts, etc.; the inorganic thermally conductive filler is 20-40 parts, for example 20 parts, 25 parts, 28 parts, 30 parts, 35 parts, or 40 parts, etc.; the flame retardant material is 2-5 parts, for example 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts; the first polar solvent is 10-20 parts, for example 12 parts, 15 parts, 18 parts, or 20 parts, etc.; the second polar solvent is 10-15 parts, for example 12 parts, 14 parts, etc.; and the third polar solvent is 3-5 parts, for example 3 parts, 3.5 parts, 4 parts, 4.5 parts, etc.
[0062] In one embodiment, the first polar solvent, the second polar solvent, and the third polar solvent include at least one of acetonitrile, tetrahydrofuran, ethanol, toluene, acetone, isopropanol, and dimethyl sulfoxide.
[0063] In one embodiment, the stirring speed of the first mixing process is 1000-3000 rpm, such as 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, etc., the linear velocity is 2.6-8 m / s, such as 2.6 m / s, 3 m / s, 4 m / s, 5 m / s, 8 m / s, etc., the stirring temperature is 25-60℃, such as 25℃, 30℃, 40℃, 50℃, 60℃, etc., and the stirring time is 1-4 h, such as 1 h, 2 h, 3 h, 4 h, etc.
[0064] In one embodiment, the stirring speed of the second mixing process is 2000-4500 rpm, such as 2000 rpm, 2500 rpm, 3000 rpm, etc., the linear velocity is 5-12 m / s, such as 6 m / s, 8 m / s, 10 m / s, 12 m / s, etc., the stirring temperature is 25-60℃, such as 25℃, 30℃, 40℃, 50℃, 60℃, etc., and the stirring time is 0.5-1.5h, such as 0.8h, 1h, 1.5h, etc.
[0065] In one embodiment, the stirring speed of the third mixing process is 1000-4500 rpm, such as 2000 rpm, 2500 rpm, 3000 rpm, etc., the linear velocity is 2.6-12 m / s, such as 2.6 m / s, 3 m / s, 4 m / s, 5 m / s, 8 m / s, etc., the stirring temperature is 25-60℃, such as 25℃, 30℃, 40℃, 50℃, 60℃, etc., and the stirring time is 0.5-1h, such as 0.5h, 0.8h, 1h, etc.
[0066] The present invention, through the first, second, and third mixing treatments under the aforementioned suitable conditions, can ensure the material properties of the first and second mixing systems, thereby ensuring the physicochemical properties of the first and second film layers. It can better cooperate with the temperature sensing layer, so that the final composite side-mounted thin film has better structural stability, thermal conductivity, and flame retardant properties. Furthermore, it can better achieve full coverage of the battery temperature sensor on each cell contact surface during thermal runaway testing, avoiding sensor failure.
[0067] In one embodiment, the vacuum degree of both the first drying and the second drying is 13–26 Pa, for example 15 Pa, 18 Pa, 20 Pa, 22 Pa, 25 Pa, etc., the temperature is 50–80 °C, for example 50 °C, 55 °C, 60 °C, 70 °C, 75 °C, or 80 °C, etc., and the time is 0.5–2 h, for example 0.5 h, 1 h, 1.5 h, or 2 h, etc. This invention employs suitable first and second drying conditions to ensure the mechanical properties of the composite temperature-sensing film.
[0068] According to another aspect of the invention, the invention also relates to the application of the composite temperature-sensing film in battery testing. The application may include thermal runaway testing, which employs a test platform comprising a test fixture 400, the composite temperature-sensing film 100, a single battery cell 200, and a thermal insulation component 300. The thermal insulation component 300 includes a heat-insulating plate or a cold plate.
[0069] In one embodiment, the composite temperature-sensing film obtained above is assembled during the battery cell assembly process according to the temperature sampling requirements of the test. The connection relationship can be referred to... Figure 3 The diagram shows the connection of the test platform. The parameters of the heat insulation component 300 need to be selected based on specific test requirements. Test fixture 4... 00 Adapted to the size and series / parallel connection quantity of a single 200-cell battery, the preload force originates from the pressure experienced during actual module assembly. The desired thermal runaway triggering method is selected, the test is initiated, and the temperature sensing wire is connected to the temperature acquisition equipment for process temperature monitoring. The thermal conductivity of the composite temperature-sensing film is used to collect data and convert it to the actual temperature. Then, by monitoring the characteristic temperatures and rate of change of the battery at various points, surfaces, and directions during the test, corresponding cutoff conditions are set, and the equipment's linkage strategy is used to control the test progress.
[0070] The composite temperature-sensing film can also be used for other safety and performance tests of batteries.
[0071] The following explanation, combined with specific embodiments and comparative examples, further illustrates the point.
[0072] Schematic diagrams of the composite temperature-sensing film in various embodiments of the present invention are shown below. Figure 1 As shown in the diagram, the structural schematic of the temperature sensing line distribution in the temperature sensing layer of the composite temperature sensing film is as follows: Figure 2 As shown.
[0073] Example 1
[0074] A composite temperature-sensing film 100 includes a first film layer 1, a temperature-sensing arrangement layer 2, and a second film layer 3. The temperature-sensing arrangement layer 2 is located between the first film layer 1 and the second film layer 3. The temperature-sensing arrangement layer 2 includes multiple thermocouples, and the multiple thermocouple temperature-sensing elements 201 are arranged in an array. The temperature-sensing wires 202 of the multiple thermocouples do not overlap. Both the first film layer 1 and the second film layer 3 include a polymer thermally conductive material, an inorganic thermally conductive filler, and a flame-retardant material. The mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler, and the flame-retardant material is 45:20:2. The polymer thermally conductive material is polyurethane resin, the inorganic thermally conductive filler is aluminum nitride, and the flame-retardant material is dimethyl (2-methoxyethoxy) phosphate methyl ester. The total thickness of the composite temperature-sensing film 100 is 20 mm.
[0075] The method for preparing the composite temperature-sensing film in this embodiment includes the following steps:
[0076] (1) 45 parts by mass of polyurethane resin and 20 parts by mass of acetonitrile were mixed and pre-dispersed using a high-speed mixer at 2500 rpm, a linear velocity of 4 m / s, a stirring temperature of 35°C, and a stirring time of 2.5 h to obtain the first material; 20 parts by mass of aluminum nitride and 10 parts by mass of acetonitrile were mixed and pre-dispersed using a high-speed mixer at 3000 rpm, a linear velocity of 6 m / s, a stirring temperature of 35°C, and a stirring time of 1 h to obtain the second material; the first material and the second material were mixed to obtain the third material; 2 parts by mass of organophosphorus flame retardant additive and 3 parts by mass of acetonitrile were added to the third material in batches using a high-speed mixer at 3000 rpm, a linear velocity of 6 m / s, a stirring temperature of 35°C, and a stirring time of 0.6 h to obtain a functional high thermal conductivity polymer solution, part of which was used as the first mixing system to prepare the first film layer 1, and part of which was used as the second mixing system to prepare the second film layer 3.
[0077] (2) The first mixed system is sprayed onto the substrate and then dried for a vacuum of 18 Pa, a drying temperature of 65 °C and a time of 1 h to form a first film layer 1.
[0078] (3) Multiple temperature measuring points are pre-set on the surface of the first film layer 1 in an array, multiple thermocouples are laid on the surface of the first film layer 1, and the temperature sensing element 201 of each thermocouple is connected to the temperature measuring point respectively to form a temperature sensing arrangement layer 2.
[0079] (4) The second mixing system is sprayed onto the surface of the temperature-sensitive arrangement layer 2 and the first film layer 1, and then dried in the second drying process. The vacuum degree is 18 Pa, the drying temperature is 65 °C, and the time is 1 h, and the second film layer 3 is formed by curing.
[0080] Example 2
[0081] A composite temperature-sensing film 100, except that the mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler and the flame-retardant material is 30:35:5, the polymer thermally conductive material is polyimide and the inorganic thermally conductive filler is alumina, and other conditions are the same as in Example 1.
[0082] The method for preparing the composite temperature-sensing film in this embodiment includes the following steps:
[0083] (1) Mix and pre-disperse 30 parts by mass of polyimide and 10 parts by mass of acetone using a high-speed mixer at 2500 rpm, a linear velocity of 5 m / s, a stirring temperature of 35°C, and a stirring time of 2.5 h to obtain the first material; mix and pre-disperse 35 parts by mass of alumina and 15 parts by mass of acetone using a high-speed mixer at 3000 rpm, a linear velocity of 6 m / s, a stirring temperature of 35°C, and a stirring time of 1 h to obtain the second material; mix the first material and the second material obtained above to obtain the third material; add 5 parts by mass of nitrogen-containing flame retardant additive and 5 parts by mass of acetone to the third material obtained above in batches using a high-speed mixer at 3000 rpm, a linear velocity of 6 m / s, a stirring temperature of 35°C, and a stirring time of 0.6 h to obtain a functional high thermal conductivity polymer solution, part of which is used as the first mixing system to prepare the first film layer 1, and part of which is used as the second mixing system to prepare the second film layer 3.
[0084] (2) The first mixed system is sprayed onto the substrate and then dried for a vacuum of 18 Pa, a drying temperature of 65 °C and a time of 1 h to form a first film layer 1.
[0085] (3) Multiple temperature measuring points are pre-set on the surface of the first film layer 1 in an array, multiple thermocouples are laid on the surface of the first film layer 1, and the temperature sensing element 201 of each thermocouple is connected to the temperature measuring point respectively to form a temperature sensing arrangement layer 2.
[0086] (4) The second mixing system is sprayed onto the surface of the temperature-sensitive arrangement layer 2 and the first film layer 1, and then dried in the second drying process. The vacuum degree is 18 Pa, the drying temperature is 65 °C, and the time is 1 h, and the second film layer 3 is formed by curing.
[0087] Example 3
[0088] A composite temperature-sensing film 100 includes a first film layer 1, a temperature-sensing arrangement layer 2, and a second film layer 3. The temperature-sensing arrangement layer 2 is located between the first film layer 1 and the second film layer 3. The temperature-sensing arrangement layer 2 includes multiple thermocouples, and the multiple thermocouple temperature-sensing elements 201 are arranged in an array. The temperature-sensing wires 202 of the multiple thermocouples do not overlap. Both the first film layer 1 and the second film layer 3 include a polymer thermally conductive material, an inorganic thermally conductive filler, and a flame-retardant material. The mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler, and the flame-retardant material is 30:35:5. The polymer thermally conductive material is polyimide, the inorganic thermally conductive filler is aluminum nitride, and the flame-retardant material is melamine. The total thickness of the composite temperature-sensing film 100 is 15 mm.
[0089] The method for preparing the composite temperature-sensing film in this embodiment includes the following steps:
[0090] (1) 30 parts by mass of polyimide and 10 parts by mass of acetone were mixed and pre-dispersed using a high-speed mixer at 2000 rpm, a linear velocity of 5 m / s, a stirring temperature of 45°C, and a stirring time of 2 h to obtain the first material; 35 parts by mass of aluminum nitride and 15 parts by mass of acetone were mixed and pre-dispersed using a high-speed mixer at 3500 rpm, a linear velocity of 8 m / s, a stirring temperature of 45°C, and a stirring time of 0.5 h to obtain the second material; the first material and the second material were mixed and stirred to obtain the third material; 5 parts by mass of nitrogen-containing flame retardant additive and 5 parts by mass of acetone were added to the third material in batches using a high-speed mixer at 4000 rpm, a linear velocity of 8 m / s, a stirring temperature of 45°C, and a stirring time of 0.5 h to obtain a functional high thermal conductivity polymer solution, part of which was used as the first mixing system to prepare the first film layer 1 and part of which was used as the second mixing system to prepare the second film layer 3;
[0091] (2) The first mixed system is sprayed onto the substrate and then dried for a vacuum of 18 Pa, a drying temperature of 65 °C and a time of 1 h to form a first film layer 1.
[0092] (3) Multiple temperature measuring points are pre-set on the surface of the first film layer 1 in an array, multiple thermocouples are laid on the surface of the first film layer 1, and the temperature sensing element 201 of each thermocouple is connected to the temperature measuring point respectively to form a temperature sensing arrangement layer 2.
[0093] (4) The second mixing system is sprayed onto the surface of the temperature-sensitive arrangement layer 2 and the first film layer 1, and then dried in the second drying process. The vacuum degree is 18 Pa, the drying temperature is 65 °C, and the time is 1 h, and the second film layer 3 is formed by curing.
[0094] Example 4
[0095] A composite temperature-sensing film 100 includes a first film layer 1, a temperature-sensing arrangement layer 2, and a second film layer 3. The temperature-sensing arrangement layer 2 is located between the first film layer 1 and the second film layer 3. The temperature-sensing arrangement layer 2 includes multiple thermocouples, and the multiple thermocouple temperature-sensing elements 201 are arranged in an array. The temperature-sensing wires 202 of the multiple thermocouples do not overlap. Both the first film layer 1 and the second film layer 3 include a polymer thermally conductive material, an inorganic thermally conductive filler, and a flame-retardant material. The mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler, and the flame-retardant material is 35:30:3. The polymer thermally conductive material is epoxy resin, the inorganic thermally conductive filler is alumina, and the flame-retardant material is melamine. The total thickness of the composite temperature-sensing film 100 is 18 mm.
[0096] The method for preparing the composite temperature-sensing film in this embodiment includes the following steps:
[0097] (1) 35 parts by mass of epoxy resin and 15 parts by mass of tetrahydrofuran were mixed and pre-dispersed. The mixture was stirred in a high-speed mixer at 3000 rpm, 2.6 m / s, 25°C, for 4 h to obtain the first material. 30 parts by mass of alumina and 12 parts by mass of tetrahydrofuran were mixed and pre-dispersed. The mixture was stirred in a high-speed mixer at 4500 rpm, 12 m / s, 60°C, for 0.5 h to obtain the second material. The first and second materials were stirred and mixed to obtain the third material. 3 parts by mass of nitrogen-containing flame retardant additive and 5 parts by mass of tetrahydrofuran were added to the third material in batches. The mixture was stirred in a high-speed mixer at 4500 rpm, 12 m / s, 60°C, for 0.5 h to obtain a functional high thermal conductivity polymer solution. Part of the solution was used as the first mixing system to prepare the first film layer 1, and part of the solution was used as the second mixing system to prepare the second film layer 3.
[0098] (2) The first mixed system is sprayed onto the substrate and then dried for a vacuum of 18 Pa, a drying temperature of 65 °C and a time of 1 h to form a first film layer 1.
[0099] (3) Multiple temperature measuring points are pre-set on the surface of the first film layer 1 in an array, multiple thermocouples are laid on the surface of the first film layer 1, and the temperature sensing element 201 of each thermocouple is connected to the temperature measuring point respectively to form a temperature sensing arrangement layer 2.
[0100] (4) The second mixing system is sprayed onto the surface of the temperature-sensitive arrangement layer 2 and the first film layer 1, and then dried in the second drying process. The vacuum degree is 18 Pa, the drying temperature is 65 °C, and the time is 1 h, and the second film layer 3 is formed by curing.
[0101] Example 5
[0102] A composite temperature-sensing film 100, except that the mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler and the flame-retardant material is 40:30:4, the polymer thermally conductive material is epoxy resin, polyimide and polyaniline, the mass ratio of epoxy resin, polyimide and polyaniline is 2:1:1, the inorganic thermally conductive filler is 30% alumina and 70% silicon carbide by mass percentage, and the flame-retardant material is 10% dimethyl (2-methoxyethoxy) methyl phosphate, 70% melamine and 20% polysiloxane by mass percentage, and other conditions are the same as in Example 3.
[0103] The method for preparing the composite temperature-sensing film in this embodiment includes the following steps:
[0104] (1) 20 parts by weight of epoxy resin, 10 parts by weight of polyimide, and 10 parts by weight of polyaniline were sequentially added to 18 parts by weight of tetrahydrofuran and pre-dispersed using a high-speed mixer at 3000 rpm, a linear velocity of 2.6 m / s, a stirring temperature of 25°C, and a stirring time of 4 h to obtain the first material; 9 parts by weight of alumina and 21 parts by weight of silicon carbide were sequentially added to 12 parts by weight of tetrahydrofuran and pre-dispersed using a high-speed mixer at 4500 rpm, a linear velocity of 12 m / s, a stirring temperature of 60°C, and a stirring time of 0.5 h to obtain... The first and second materials are stirred and mixed to obtain the third material. 10 parts by mass of an organophosphorus flame retardant additive, 70 parts by mass of a nitrogen-containing flame retardant additive, 20 parts by mass of a silicon-based flame retardant additive, and 5 parts by mass of tetrahydrofuran are added to the third material in batches. A high-speed mixer is used with a speed of 4500 rpm, a linear velocity of 12 m / s, a stirring temperature of 60°C, and a stirring time of 0.5 h to obtain a functional high thermal conductivity polymer solution. Part of this solution is used as the first mixing system to prepare the first film layer 1, and part is used as the second mixing system to prepare the second film layer 3.
[0105] (2) The first mixed system is sprayed onto the substrate and then dried for a vacuum of 22 Pa, a drying temperature of 70 °C and a time of 0.5 h to form the first film layer 1.
[0106] (3) Multiple temperature measuring points are pre-set on the surface of the first film layer 1 in an array, multiple thermocouples are laid on the surface of the first film layer 1, and the temperature sensing element 201 of each thermocouple is connected to the temperature measuring point respectively to form a temperature sensing arrangement layer 2.
[0107] (4) The second mixing system is sprayed onto the surface of the temperature-sensitive arrangement layer 2 and the first film layer 1, and then dried in the second drying process. The vacuum degree is 22 Pa, the drying temperature is 70 °C, and the time is 0.5 h, and the second film layer 3 is formed by curing.
[0108] Comparative Example 1
[0109] A composite temperature-measuring film, wherein the mass ratio of the polymer thermally conductive material, the inorganic thermally conductive filler and the flame-retardant material is 50:18:1, and other conditions are the same as in Example 3.
[0110] The preparation method of the composite temperature-sensing film is the same as in Example 3, except that the polymer thermally conductive material is 50 parts by mass, the inorganic thermally conductive filler is 18 parts by mass, and the flame-retardant material is 1 part by mass.
[0111] Comparative Example 2
[0112] A method for preparing a composite temperature-sensing thin film includes the following steps:
[0113] 30 parts by weight of polyimide, 35 parts by weight of aluminum nitride, 5 parts by weight of nitrogen-containing flame retardant additive, and 30 parts by weight of acetone were directly mixed at 4000 rpm, a linear velocity of 8 m / s, a stirring temperature of 45°C, and a stirring time of 0.5 h to obtain a polymer solution. Part of the solution was used as the first mixing system to prepare the first film layer 1, and part of the solution was used as the second mixing system to prepare the second film layer 3. Other operating steps were the same as in Example 3.
[0114] Comparative Example 3
[0115] A method for preparing a composite temperature-sensing film, except for step (1): the first material is prepared at a rotation speed of 800 rpm, a linear velocity parameter of 2 m / s, and a stirring temperature of 15°C; the second material is prepared at a rotation speed of 1500 rpm, a linear velocity parameter of 4 m / s, and a stirring temperature of 15°C; the third material is prepared using a high-speed mixer at a rotation speed of 500 rpm, a linear velocity parameter of 2 m / s, and a stirring temperature of 15°C to obtain a polymer solution, part of which is used as the first mixing system to prepare the first film layer 1, and part of which is used as the second mixing system to prepare the second film layer 3; other conditions are the same as in Example 3.
[0116] Experimental Example
[0117] The composite temperature sensing films in the examples and comparative examples were subjected to performance tests, and their thermal conductivity, flame retardancy rating, and compression deformation were measured. The thermal conductivity was measured using Hotdisk; the flame retardancy rating was referenced to UL94; the compression deformation was directly measured by applying a force of 5000N to the composite temperature sensing film before and after compression, and the change in thickness of the composite temperature sensing film before and after compression was observed. The compression deformation was calculated as (thickness of the composite temperature sensing film before compression - thickness of the composite temperature sensing film after compression) / thickness of the composite temperature sensing film before compression.
[0118] The test results are shown in Table 1.
[0119] Table 1 Performance test results of the composite temperature-sensing film
[0120]
[0121] As shown in Table 1, the composite temperature-sensing films obtained in the various embodiments of the present invention, through appropriate raw material ratios and preparation step parameters, possess high thermal conductivity, good flame retardancy, and suitable compression deformation. When used for battery thermal runaway testing, this composite film can achieve full coverage of the temperature sensor on each cell contact surface, ensuring structural and functional integrity during severe thermal runaway testing. The composite temperature-sensing films in Comparative Examples 1-3 exhibit relatively poor thermal conductivity and flame retardancy.
[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A composite temperature-sensing film, characterized in that, It includes a first film layer, a temperature-sensing arrangement layer, and a second film layer, wherein the temperature-sensing arrangement layer is located between the first film layer and the second film layer; the temperature-sensing arrangement layer includes a plurality of thermocouples, wherein the temperature-sensing elements of the plurality of thermocouples are arranged in an array. The first film layer and the second film layer have the same composition. Both the first film layer and the second film layer are composed of polymer thermally conductive material, inorganic thermally conductive filler and flame retardant material. The mass ratio of the polymer thermally conductive material, inorganic thermally conductive filler and flame retardant material is (30~45):(20~40):(2~5).
2. The composite temperature-sensing film according to claim 1, characterized in that, It includes at least one of the following features (1) to (3): (1) The polymer thermally conductive material includes at least one of polyurethane resin, epoxy resin, polyaniline, polyvinylidene fluoride, polystyrene, polypropylene and polyimide; (2) The inorganic thermally conductive filler includes at least one of alumina, magnesium oxide, zinc oxide, aluminum nitride and silicon carbide; (3) The flame retardant material includes at least one of organophosphorus flame retardant additives, nitrogen-containing compound flame retardant additives, halogenated carbonate flame retardant additives, silicon-based flame retardant additives and composite flame retardant additives.
3. The composite temperature-sensing film according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The polymer thermally conductive material, the inorganic thermally conductive filler, and the flame-retardant material have the same mass ratio; (2) The thickness of the first film layer and the second film layer is 0.5~10mm.
4. The composite temperature-sensing film according to claim 1, characterized in that, The temperature sensing wires of the thermocouples are not connected to each other; the end of each temperature sensing wire away from the temperature sensing element extends to the outside of the first film layer.
5. The composite temperature-sensing film according to claim 1, characterized in that, The thermocouples include at least one of type K, type S, type E, type N, type J, type T, type R and type B.
6. The method for preparing the composite temperature-sensing thin film according to any one of claims 1 to 5, characterized in that, Includes the following steps: (a) The first mixture system is sprayed onto the substrate and then dried to form a first film layer; (b) A plurality of temperature measuring points are pre-set on the surface of the first film layer in an array, a plurality of thermocouples are laid on the surface of the first film layer, and the temperature sensing element of each thermocouple is respectively connected to the temperature measuring point to form a temperature sensing arrangement layer. (c) The second mixture system is sprayed onto the surface of the temperature-sensitive arrangement layer and the first film layer, and then dried in the second stage to form the second film layer; Both the first and second mixed systems include polymer thermally conductive materials, inorganic thermally conductive fillers, flame-retardant materials, and polar solvents.
7. The method for preparing the composite temperature-sensing thin film according to claim 6, characterized in that, The preparation methods of the first mixed system and the second mixed system specifically include: The polymer thermally conductive material is mixed with a first polar solvent to obtain a first material; The inorganic thermally conductive filler is mixed with a second polar solvent to obtain a second material. The first material and the second material are mixed to obtain a third material; a flame retardant and a third polar solvent are added to the third material, and then a third mixing treatment is performed to obtain a fourth material. Part of the fourth material is used as the first mixing system, and part of the fourth material is used as the second mixing system.
8. The method for preparing the composite temperature-sensing thin film according to claim 7, characterized in that, It includes at least one of the following features (1) to (5): (1) By mass parts, the polymer thermally conductive material is 30-45 parts, the inorganic thermally conductive filler is 20-40 parts, the flame retardant material is 2-5 parts, the first polar solvent is 10-20 parts, the second polar solvent is 10-15 parts, and the third polar solvent is 3-5 parts; (2) The first polar solvent, the second polar solvent and the third polar solvent each include at least one of acetonitrile, tetrahydrofuran, ethanol, toluene, acetone, isopropanol and dimethyl sulfoxide; (3) The stirring speed of the first mixing treatment is 1000~3000 rpm, the linear velocity is 2.6~8 m / s, the stirring temperature is 25~60℃, and the stirring time is 1~4h; (4) The stirring speed of the second mixing treatment is 2000~4500 rpm, the linear velocity is 5~12 m / s, the stirring temperature is 25~60℃, and the stirring time is 0.5~1.5 h; (5) The stirring speed of the third mixing treatment is 1000~4500 rpm, the linear velocity is 2.6~12 m / s, the stirring temperature is 25~60℃, and the stirring time is 0.5~1h.
9. The method for preparing the composite temperature-sensing thin film according to claim 6, characterized in that, The vacuum degree of both the first drying and the second drying is 13~26 Pa, the temperature is 50~80℃, and the time is 0.5~2h.
10. The application of the composite temperature-sensing film according to any one of claims 1 to 5 in battery testing.