Multifunctional thermal protection composite coating and preparation method and application thereof

Abstract

The present application relates to the technical field of commercial lithium ion battery safety protection, in particular to a multifunctional thermal protection composite coating and a preparation method and application thereof, which is composed of an organic-inorganic hybrid coating and an inorganic ceramic material coating arranged on the surface of a substrate in sequence, the preparation raw materials of the organic-inorganic hybrid coating at least include a high molecular compound, an inorganic filler and a solvent, and the preparation raw materials of the inorganic ceramic material coating at least include an aqueous emulsion, a silicate and an inorganic compound, the composite coating can form a composite coating structure of a controllable heat conduction weakening layer, an air layer and a heat convection weakening layer during the fire process, the three-layer composite structure design can effectively weaken the heat conduction and heat convection while ensuring that the overall coating thickness is relatively thin to meet the actual needs of the battery aluminum shell, and the high-temperature resistance, flame resistance and heat insulation effects are fully played.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of safety protection of commercial lithium ion batteries, in particular to a multifunctional thermal protection composite coating and a preparation method and application thereof. BACKGROUND

[0002] In recent years, the popularity of new energy vehicles has led to a sharp increase in the use of lithium ion batteries, and battery fire and explosion accidents have become increasingly frequent. The main cause of battery fire and explosion is the thermal runaway of single cells in the battery pack, and the heat will uncontrollably pass through the aluminum shell of the battery cell to the surrounding single cells, causing thermal runaway and fire and explosion of the entire battery pack. Research shows that coating a layer of thermal protection coating on the aluminum shell of each single cell will be an effective strategy to delay battery fire and explosion.

[0003] As we all know, there are three forms of heat transfer, namely thermal radiation, thermal convection and thermal conduction. If you want to prevent heat diffusion, you need to inhibit or delay these three forms of heat transfer. A single inhibition of heat transfer is not very ideal, so researchers have proposed the design concept of composite thermal protection coating and conducted a lot of exploration. For example, Chinese invention patent application (publication number CN115849958A) discloses a preparation method and application of a ceramic-based thermal protection coating, which combines the functions of sealing, oxidation resistance, heat insulation and ablation resistance by constructing a composite thermal protection coating of sealing layer, silicon-based oxidation resistance layer and heat insulation and ablation resistance layer, and plays their respective advantages to form a three-layer composite system to improve the temperature resistance effect. Chinese invention patent application (authorized publication number CN113800955B) provides a multi-layer ceramic-based composite thermal protection coating and its preparation method and application, which uses chemical vapor deposition method to prepare a composite coating including buffer layer, strong self-healing oxidation resistance layer, intermediate chemical barrier layer, ceramic heat insulation layer and reinforced isolation layer from inside to outside, to improve the service life of the material under high temperature chemical oxidation and corrosion conditions. Chinese invention patent application (authorized publication number CN103847189B) applies for a thermal protection coating for launch pad, which is composed of an organic bottom layer and an organic-inorganic composite surface layer, and can withstand gas flow erosion, so that the temperature of the metal back surface does not exceed 200℃. Although various composite thermal protection coatings have been developed, the technical difficulty is great, the preparation conditions are complex, and the coating is thick, which makes it difficult to apply these composite coatings to battery aluminum shell thermal protection. Therefore, it is still of great significance to continue to develop a simple and efficient method to prepare an ultra-thin multifunctional thermal protection composite coating for battery aluminum shell. SUMMARY

[0004] In order to solve the above problems, the application provides a design and preparation of a multifunctional thermal protection composite coating, which can form a composite coating structure of a controllable heat conduction weakening layer, an air layer and a heat convection weakening layer during a fire process, can effectively weaken heat conduction and heat convection by the three-layer composite structure design, and can fully play the roles of high-temperature resistance, fire resistance and heat insulation while ensuring that the overall coating thickness is thin to meet the actual needs of the battery aluminum shell.

[0005] The application provides a multifunctional thermal protection composite coating, which is composed of an organic-inorganic hybrid coating and an inorganic ceramic material coating arranged on the surface of a substrate in sequence, and the preparation raw materials of the organic-inorganic hybrid coating at least include a high polymer compound, an inorganic filler and a solvent, and the preparation raw materials of the inorganic ceramic material coating at least include an aqueous emulsion, a silicate and an inorganic compound.

[0006] As a preferred technical solution, the thickness of the multifunctional thermal protection composite coating is 1-1000 microns.

[0007] As a preferred technical solution, the high polymer compound is at least one selected from organic silicon resin, epoxy resin and polyurethane, and preferably is organic silicon resin.

[0008] As a preferred technical solution, the solid content of the organic silicon resin is 50-60 wt%, and preferably is 50±2 wt%. Preferably, the organic silicon resin is at least one selected from CFS18050, CFS18250, CFS18350, CFS18450, CFS18550, CFS18650, CFS15030, CFS16030, CFS7060W, CFS7030W and CFS6020W. Preferably, the organic silicon resin is CFS18350, which is from Weifang Fule New Material Co., Ltd.

[0009] As a preferred technical solution, the inorganic filler is at least one selected from zirconium compound, silicon compound, titanium compound, aluminum compound and magnesium compound. Preferably, the inorganic filler is at least one selected from zirconium oxide, silicon oxide, potassium silicate, sodium silicate, magnesium oxide and aluminum oxide. Preferably, the inorganic filler is a combination of silicon dioxide and potassium silicate or a combination of aluminum oxide, silicon dioxide and potassium silicate.

[0010] Preferably, the particle size of the silicon dioxide is 20-50 nm, and the ignition loss (950 DEG C, 2h) is less than or equal to 8%. Preferably, the particle size of the silicon dioxide is 30±10 nm, and the ignition loss (950 DEG C, 2h) is less than or equal to 6%. The model of the silicon dioxide is VK-SP30T, which is from Jingrui.

[0011] As a preferred technical solution, the solvent is at least one of propylene glycol methyl ether and ethylene glycol.

[0012] As a preferred technical solution, the water-based emulsion is YF6189 from Shanghai Chaozhan Industrial Development Co., Ltd.

[0013] As a preferred technical solution, the silicate is at least one of sodium silicate and potassium silicate, preferably potassium silicate.

[0014] As a preferred technical solution, the inorganic compound is at least one of silicon oxide, titanium oxide, zirconium oxide, aluminum oxide, aluminum hydroxide, and magnesium hydroxide, preferably aluminum oxide. Preferably, the specific surface area of the aluminum oxide is 9-11 m 2 / g, and the aluminum oxide is SAO-020 from Guocui.

[0015] Another aspect of the present application provides a preparation method of a multifunctional thermal protection composite coating, comprising at least the following steps:

[0016] S1: adding a polymer compound and an inorganic filler into a solvent according to a mass ratio, and obtaining an organic-inorganic hybrid coating after ultrasonic and stirring;

[0017] S2: adding an inorganic compound and a silicate into a water-based emulsion according to a mass ratio, and obtaining an inorganic ceramic material coating after ultrasonic and stirring;

[0018] S3: pretreating a commercial lithium ion battery shell aluminum plate to obtain a pretreated aluminum plate;

[0019] S4: spraying the organic-inorganic hybrid coating to the surface of the pretreated aluminum plate, and obtaining a single-layer coating film after drying, and repeating the same steps to obtain an organic-inorganic hybrid coating;

[0020] S5: spraying the inorganic ceramic material coating to the surface of the organic-inorganic hybrid coating, and obtaining a single-layer coating film after drying, and repeating the same steps to obtain an inorganic ceramic material coating.

[0021] As a preferred technical solution, the mass ratio of the polymer compound and the inorganic filler is 5:(5-15); preferably, the mass ratio of the organosilicon resin, silicon oxide or a combination of silicon oxide and aluminum oxide, and potassium silicate is 5:(5-10):1.

[0022] As a preferred technical solution, the mass ratio of the organosilicon resin in the organic-inorganic hybrid coating is 50-60wt%, preferably 50±2wt%.

[0023] As a preferred technical solution, the mass ratio of the inorganic compound and the silicate is (10-15):1.

[0024] As a preferred technical solution, the inorganic compound in the inorganic ceramic material coating accounts for 50-70wt%, preferably 70±2wt%.

[0025] As a preferred technical solution, the ultrasonic is specifically 20-60min, preferably 30min, in an ultrasonic cleaner with a power of 180W.

[0026] As a preferred technical solution, the stirring is specifically 0.5-1.5h at a stirring speed of 600-1000r / min on a magnetic stirrer.

[0027] As a preferred technical solution, the pretreatment is specifically as follows: taking a commercial lithium ion battery shell aluminum plate, cleaning it with acetone and ethanol for 30min respectively, and then drying it completely in a 60℃ air drying oven. Then, use 180-mesh corundum sand for sandblasting treatment, and clean the sandblasted aluminum plate with ethanol until no particles are attached to the surface of the aluminum plate, and then dry the aluminum plate in a 60℃ air drying oven to obtain a pretreated aluminum plate.

[0028] As a preferred technical solution, the drying in step S4 is specifically 10-12h at 20-30℃, and then 0.5-2h at 60-80℃. Preferably, the drying in step S4 is specifically 12h at 25±2℃, and then 1h at 70±2℃.

[0029] As a preferred technical solution, the thickness of the single-layer coating film in step S4 is 80-100μm, and the thickness of the organic-inorganic hybrid coating is 80-200μm.

[0030] As a preferred technical solution, the drying in step S5 is specifically 10-12h at 20-30℃. Preferably, the drying in step S5 is specifically 12h at 25±2℃.

[0031] As a preferred technical solution, the thickness of the single-layer coating film in step S5 is 80-100μm, and the thickness of the inorganic ceramic material coating is 300-420μm.

[0032] The present application aims to provide a kind of ultra-thin thermal protection coating for battery aluminum shell, and the inventor finds that by pretreating the aluminum plate of commercial lithium ion battery shell, cooperating with specific organic-inorganic hybrid coating, especially optimizing the mass ratio of high molecular compound and inorganic filler in organic-inorganic hybrid coating, the provided organic-inorganic hybrid coating meets the process requirements of spraying, and the formed organic-inorganic hybrid coating has strong bonding effect with the pretreated aluminum plate, avoiding the problem of peeling of composite coating after fire.Further, by using organic silicon resin CFS18350 with solid content of 50±2wt%, cooperating with silicon dioxide and potassium silicate or alumina, silicon dioxide and potassium silicate, the provided organic-inorganic hybrid coating has strong adhesion and small volume change after fire.But when the heat insulation performance test is carried out, it is found that the heat insulation effect needs to be further improved.

[0033] The inventor further matches the inorganic ceramic material coating, forms a multifunctional thermal protection composite coating of organic-inorganic hybrid coating and inorganic ceramic material coating by spraying organic-inorganic hybrid coating and inorganic ceramic material coating on the surface of the aluminum plate of commercial lithium ion battery shell in sequence, especially controls the thickness of the organic-inorganic hybrid coating and the inorganic ceramic material coating, realizes excellent heat insulation effect under the thickness of the ultra-thin composite coating, meets the fireproof and heat insulation requirements of commercial lithium ion battery, and has low cost and simple implementation method, which can be applied to large-scale industrial production and application.Further, by controlling the mass ratio of alumina and silicate in the inorganic ceramic material coating, the provided composite coating generates a large amount of bubbles during the fire process, forms rich air cavities in the layer, and part of the top layer and the bottom layer are separated to form a large number of air layers, finally forms a composite coating structure of heat conduction weakening layer, air layer and heat convection weakening layer, which can fully play the roles of high temperature resistance, flame retardation and heat insulation while ensuring that the overall coating thickness is thin to meet the actual needs.

[0034] The present application optimizes the design of composite coating to reduce the influence of external heat on the internal cell of aluminum shell from two aspects of weakening heat conduction and heat convection, and greatly improves the safety of commercial lithium ion battery.

[0035] The third aspect of the present application provides an application of the multifunctional thermal protection composite coating on the surface of the aluminum shell of commercial lithium ion battery.

[0036] Advantages

[0037] 1、The present application provides a design and preparation of a multifunctional thermal protection composite coating, which can form a composite coating structure of heat conduction weakening layer, air layer and heat convection weakening layer during the fire process, and the three-layer composite structure design can effectively weaken heat conduction and heat convection, fully play the roles of high temperature resistance, flame retardation and heat insulation while ensuring that the overall coating thickness is thin to meet the actual needs of battery aluminum shell.

[0038] 2、The present application is to provide a multifunctional thermal protection composite coating for commercial lithium ion battery shell, which comprises the following steps of: pretreating an aluminum plate of a commercial lithium ion battery shell, and then spraying an organic-inorganic hybrid coating on the surface of the pretreated aluminum plate, wherein the mass ratio of a high molecular compound and an inorganic filler in the organic-inorganic hybrid coating is optimized.

[0039] 3、The present application is to provide a multifunctional thermal protection composite coating for commercial lithium ion battery shell, which comprises the following steps of: pretreating an aluminum plate of a commercial lithium ion battery shell, and then spraying an organic-inorganic hybrid coating and an inorganic ceramic material coating on the surface of the pretreated aluminum plate in sequence to form a multifunctional thermal protection composite coating with an organic-inorganic hybrid coating and an inorganic ceramic material coating, wherein the thickness of the organic-inorganic hybrid coating and the inorganic ceramic material coating is controlled, so that excellent heat insulation effect is realized under the condition of an ultrathin composite coating thickness, the fireproof and heat insulation requirements of commercial lithium ion batteries are met, the cost is low, the implementation method is simple, and the multifunctional thermal protection composite coating can be applied to large-scale industrial production and application.

[0040] 4、The present application is to provide a multifunctional thermal protection composite coating for commercial lithium ion battery shell, which comprises the following steps of: pretreating an aluminum plate of a commercial lithium ion battery shell, and then spraying an organic-inorganic hybrid coating and an inorganic ceramic material coating on the surface of the pretreated aluminum plate in sequence to form a multifunctional thermal protection composite coating with an organic-inorganic hybrid coating and an inorganic ceramic material coating, wherein the mass ratio of alumina and silicate in the inorganic ceramic material coating is controlled, so that a large amount of bubbles is generated in the composite coating during the fire process, a large number of air layers are formed between the top layer and the bottom layer, and finally a composite coating structure of a heat conduction weakening layer, an air layer and a heat convection weakening layer is formed, so that the high-temperature resistance, the fire resistance and the heat insulation effect are fully exerted while the overall coating thickness is thin and meets the actual needs.

[0041] 5、The present application is to provide a multifunctional thermal protection composite coating for commercial lithium ion battery shell, which comprises the following steps of: pretreating an aluminum plate of a commercial lithium ion battery shell, and then spraying an organic-inorganic hybrid coating and an inorganic ceramic material coating on the surface of the pretreated aluminum plate in sequence to form a multifunctional thermal protection composite coating with an organic-inorganic hybrid coating and an inorganic ceramic material coating, wherein the thickness of the organic-inorganic hybrid coating and the inorganic ceramic material coating is controlled, so that excellent heat insulation effect is realized under the condition of an ultrathin composite coating thickness, the fireproof and heat insulation requirements of commercial lithium ion batteries are met, the cost is low, the implementation method is simple, and the multifunctional thermal protection composite coating can be applied to large-scale industrial production and application. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Optical photographs of the multifunctional thermal protection composite coating provided for Example 1 before the fire (a) and after the fire (b).

[0043] Figure 2 Scanning electron microscope (SEM) front view (a, b) and side view (c, d) of the top layer of the multifunctional thermal protection composite coating provided for Example 1 after the fire.

[0044] Figure 3 Comparison chart of the heat insulation performance test results of the blank control (a), Example 1 (b), Comparative Example 1 (c), and Comparative Example 2 (d). DETAILED DESCRIPTION

[0045] Example 1

[0046] The embodiment 1 of the present application provides a multifunctional thermal protection composite coating in one aspect, which is composed of an organic-inorganic hybrid coating and an inorganic ceramic material coating arranged on the surface of a substrate in sequence, the preparation raw materials of the organic-inorganic hybrid coating are composed of a polymer compound, an inorganic filler and a solvent, and the preparation raw materials of the inorganic ceramic material coating are composed of an aqueous emulsion, a silicate and an inorganic compound.

[0047] The polymer compound is an organic silicon resin, the solid content of the organic silicon resin is 50±2wt%, the model is CFS18350, and the source is Weifang Fule New Material Co., Ltd.

[0048] The inorganic filler is a combination of silicon dioxide and potassium silicate.

[0049] The particle size of the silicon dioxide is 30±10nm, and the ignition loss (950℃, 2h) is ≤6%. The model of the silicon dioxide is VK-SP30T, and the source is Jingrui.

[0050] The solvent is propylene glycol methyl ether.

[0051] The model of the aqueous emulsion is YF6189, and the source is Shanghai Chaozhan Industrial Development Co., Ltd.

[0052] The silicate is potassium silicate.

[0053] The inorganic compound is alumina. The specific surface area of the alumina is 9-11m 2 / g, the model of the alumina is SAO-020, and the source is Guocui.

[0054] The embodiment 1 of the present application provides a preparation method of a multifunctional thermal protection composite coating in another aspect, which comprises the following steps:

[0055] S1, the polymer compound and the inorganic filler are added into the solvent according to the mass ratio, and the organic-inorganic hybrid coating is obtained after ultrasonic and stirring;

[0056] S2, the inorganic compound and the silicate are added into the aqueous emulsion according to the mass ratio, and the inorganic ceramic material coating is obtained after ultrasonic and stirring;

[0057] S3, the commercial lithium ion battery shell aluminum plate is pretreated to obtain a pretreated aluminum plate;

[0058] S4, the organic-inorganic hybrid coating is sprayed on the surface of the pretreated aluminum plate, and the single-layer coating film is obtained after drying, and the same step is repeated to obtain the organic-inorganic hybrid coating;

[0059] S5, the inorganic ceramic material coating is sprayed on the surface of the organic-inorganic hybrid coating, and the single-layer coating film is obtained after drying, and the same step is repeated to obtain the inorganic ceramic material coating.

[0060] The mass ratio of the organic silicon resin, silicon oxide and potassium silicate is 5:10:1.

[0061] The mass ratio of the organic silicon resin, silicon oxide and potassium silicate is 5:10:1.

[0062] The mass ratio of the inorganic compound and the silicate is 10:1.

[0063] The mass ratio of the inorganic compound and the silicate is 10:1.

[0064] The ultrasonic is specifically: ultrasonic for 30 min on an ultrasonic cleaner with a power of 180 W.

[0065] The stirring is specifically: stirring for 1 h on a magnetic stirrer at a stirring speed of 1000 r / min.

[0066] The pretreatment is specifically: taking a commercial lithium ion battery shell aluminum plate, ultrasonic cleaning with acetone and ethanol for 30 min respectively, and then drying completely in a 60℃ air drying oven. Then, sandblasting treatment is performed using 180-mesh corundum sand, and the aluminum plate after sandblasting treatment is ultrasonically cleaned with ethanol until no particles are attached to the surface of the aluminum plate, and then the aluminum plate is dried in a 60℃ air drying oven to obtain a pretreated aluminum plate.

[0067] The drying in step S4 is specifically: drying for 12 h at 25±2℃, and then drying for 1 h at 70±2℃.

[0068] The thickness of the single-layer coating film in step S4 is 100 μm, and the thickness of the organic-inorganic hybrid coating layer is 200 μm.

[0069] The drying in step S5 is specifically: drying for 12 h at 25±2℃.

[0070] The thickness of the single-layer coating film in step S5 is 100 μm, and the thickness of the inorganic ceramic material coating layer is 300 μm.

[0071] Example 2

[0072] Example 2 of the present application provides a multifunctional thermal protection composite coating and a preparation method thereof, and the specific implementation manner is the same as that of Example 1, except that the mass ratio of the organic silicon resin, silicon oxide and potassium silicate is 5:5:1.

[0073] Example 3

[0074] Embodiment 3 of the present application provides a multifunctional thermal protection composite coating and a preparation method thereof, the specific implementation of which is the same as that of Embodiment 1, except that the thickness of the single-layer coating film in step S4 is 100 μm, and the thickness of the organic-inorganic hybrid coating is 100 μm. The thickness of the single-layer coating film in step S5 is 100 μm, and the thickness of the organic-inorganic hybrid coating is 400 μm.

[0075] Embodiment 4

[0076] Embodiment 4 of the present application provides a multifunctional thermal protection composite coating and a preparation method thereof, the specific implementation of which is the same as that of Embodiment 1, except that the silicon oxide is replaced by a combination of aluminum oxide and silicon oxide, and the mass ratio of the aluminum oxide and the silicon oxide is 1:1.

[0077] Embodiment 5

[0078] Embodiment 5 of the present application provides a multifunctional thermal protection composite coating and a preparation method thereof, the specific implementation of which is the same as that of Embodiment 1, except that the mass ratio of the inorganic compound and the silicate is 15:1.

[0079] Comparative Example 1

[0080] Comparative Example 1 of the present application provides an inorganic ceramic material coating and a preparation method thereof, the preparation raw material of the inorganic ceramic material coating is composed of an aqueous emulsion, a silicate, and an inorganic compound. The model of the aqueous emulsion is YF6189, and the source is Shanghai Chaozhan Industrial Development Co., Ltd.

[0081] The silicate is potassium silicate.

[0082] The inorganic compound is aluminum oxide. The specific surface area of the aluminum oxide is 9-11 m 2 / g, the model of the aluminum oxide is SAO-020, and the source is Guocui.

[0083] The preparation method of the inorganic ceramic material coating is

[0084] S1: The inorganic compound and the silicate are added to the aqueous emulsion according to the mass ratio, and after ultrasonic and stirring, the inorganic ceramic material coating is obtained;

[0085] S2: The commercial lithium ion battery shell aluminum plate is pretreated to obtain a pretreated aluminum plate;

[0086] S3: The inorganic ceramic material coating is sprayed to the surface of the pretreated aluminum plate, and after drying, a single-layer coating film is obtained. The same step is repeated to obtain an inorganic ceramic material coating.

[0087] The mass ratio of the inorganic compound and the silicate is 10:1.

[0088] The inorganic compound in the inorganic ceramic material coating accounts for 70wt% of the mass.

[0089] The ultrasonic treatment is specifically 30 minutes of ultrasonic treatment in an ultrasonic cleaning machine with a power of 180W.

[0090] The stirring is specifically 1 hour of stirring at a stirring speed of 1000r / min on a magnetic stirrer.

[0091] The pretreatment is specifically: taking a commercial lithium-ion battery shell aluminum plate, ultrasonic cleaning with acetone and ethanol for 30 minutes respectively, and then drying completely in a 60℃ air drying oven. Then, sandblasting treatment is performed using 180-mesh corundum sand, and the aluminum plate after sandblasting treatment is ultrasonic cleaned with ethanol until no particles are attached to the surface of the aluminum plate, and then the aluminum plate is dried in a 60℃ air drying oven to obtain a pretreated aluminum plate.

[0092] The drying is specifically 12 hours of drying under the condition of 25±2℃.

[0093] The thickness of the single-layer coating film is 100μm, and the thickness of the inorganic ceramic material coating is 500μm.

[0094] Comparative Example 2

[0095] Comparative Example 2 of the present application provides an organic-inorganic hybrid coating and a preparation method thereof. The preparation raw materials of the organic-inorganic hybrid coating consist of a high molecular compound, an inorganic filler, and a solvent. The high molecular compound is a silicone resin, the solid content of the silicone resin is 50±2wt%, the model is CFS18350, and the source is Weifang Fule New Material Co., Ltd.

[0096] The inorganic compound is a combination of silicon dioxide and potassium silicate.

[0097] The particle size of the silicon dioxide is 30±10nm, and the ignition loss (950℃, 2h) is ≤6%. The model of the silicon dioxide is VK-SP30T, and the source is Jingrui.

[0098] The solvent is propylene glycol methyl ether.

[0099] The preparation method of the organic-inorganic hybrid coating is:

[0100] S1: adding the high molecular compound and the inorganic filler into the solvent according to the mass ratio, and obtaining an organic-inorganic hybrid coating after ultrasonic treatment and stirring;

[0101] S2: pretreating a commercial lithium-ion battery shell aluminum plate to obtain a pretreated aluminum plate;

[0102] S3 sprays the organic-inorganic hybrid coating to the surface of the pretreated aluminum plate, and after drying, a single-layer coating film is obtained, and the same step is repeated to obtain an organic-inorganic hybrid coating layer;

[0103] The mass ratio of the organic silicon resin, silicon oxide and potassium silicate is 5:10:1.

[0104] The mass fraction of the organic silicon resin in the organic-inorganic hybrid coating is 50wt%.

[0105] The ultrasonic treatment is specifically 30min of ultrasonic treatment on an ultrasonic cleaner with a power of 180W.

[0106] The stirring is specifically 1h of stirring at a stirring speed of 1000r / min on a magnetic stirrer.

[0107] The pretreatment is specifically that a commercial lithium ion battery shell aluminum plate is taken, ultrasonic cleaning is performed on the aluminum plate with acetone and ethanol for 30min respectively, and then the aluminum plate is dried in a 60℃ air drying oven until completely dry. Then, the aluminum plate is subjected to sand blasting treatment using 180-mesh corundum sand, and after ultrasonic cleaning of the aluminum plate with ethanol until no particles are attached to the surface of the aluminum plate, the aluminum plate is dried in a 60℃ air drying oven to obtain a pretreated aluminum plate.

[0108] The drying is specifically 12h of drying at 25±2℃, followed by 1h of drying at 70±2℃.

[0109] The thickness of the single-layer coating film in step S4 is 100μm, and the thickness of the organic-inorganic hybrid coating layer is 500μm.

[0110] Blank control

[0111] The blank control of the present application is the pretreated aluminum plate in Example 1.

[0112] Performance test method

[0113] 1. Optical photograph characterization: The optical photographs before and after the composite coating provided by Examples 1-5 are characterized to represent the appearance and heat resistance of the composite coating, and the results are shown in Table 1. The optical photographs before and after the composite coating provided by Example 1 are shown in Figure 1 .

[0114] 2. SEM characterization: The SEM front view and side view of the composite coating provided by Examples 1-5 after being subjected to fire are characterized to represent the structure of the composite coating, and the results are shown in Table 1. The scanning electron microscope (SEM) front view and side view of the composite coating provided by Example 1 after being subjected to fire are shown in Figure 2 .

[0115] 3. Heat insulation performance: The heat insulation effect of Examples 1-5, Comparative Examples 1 and 2, and the blank control was tested using a heat insulation test device (self-made), wherein the fire surface was the side with the coating, and the flame temperature was 800°C. The results are shown in Table 1, Figure 3 .

[0116] Table 1,

[0117]

[0118]

Claims

1. A multifunctional thermal protection composite coating, characterized in that, The organic-inorganic hybrid coating layer and the inorganic ceramic material coating layer are sequentially arranged on the surface of the substrate, the preparation raw materials of the organic-inorganic hybrid coating layer at least include a polymer compound, an inorganic filler and a solvent, and the preparation raw materials of the inorganic ceramic material coating layer at least include an aqueous emulsion, a silicate and an inorganic compound; the polymer compound is a silicone resin; the inorganic filler is a combination of silicon dioxide and potassium silicate or a combination of aluminum oxide, silicon dioxide and potassium silicate, the mass ratio of the silicone resin, silicon dioxide or the combination of silicon dioxide and aluminum oxide and potassium silicate is 5: (5-10): 1; the mass ratio of the inorganic compound and the silicate is (10-15): 1, the silicate is potassium silicate, and the inorganic compound is aluminum oxide; the type of the aqueous emulsion is YF6189; the thickness of the organic-inorganic hybrid coating layer is 80-200 microns; and the thickness of the inorganic ceramic material coating layer is 300-420 microns.

2. A method of producing a multifunctional thermal protection composite coating according to claim 1, characterized in that, At least the following steps are included: S1, a polymer compound and an inorganic filler are added to a solvent according to a mass ratio, and an organic-inorganic hybrid coating is obtained after ultrasonic and stirring; S2, an inorganic compound and a silicate are added to an aqueous emulsion according to a mass ratio, and an inorganic ceramic material coating is obtained after ultrasonic and stirring; S3, a commercial lithium ion battery shell aluminum plate is pretreated to obtain a pretreated aluminum plate; S4, the organic-inorganic hybrid coating is sprayed on the surface of the pretreated aluminum plate, and a single-layer coating film is obtained after drying, and the same step is repeated to obtain an organic-inorganic hybrid coating layer; S5, the inorganic ceramic material coating is sprayed on the surface of the organic-inorganic hybrid coating layer, and a single-layer coating film is obtained after drying, and the same step is repeated to obtain an inorganic ceramic material coating layer.

3. The method of claim 2, wherein the multi-functional thermal protection composite coating is prepared by a process comprising: The thickness of the single-layer coating film in the step S4 is 80-100 microns.

4. The method of claim 2, wherein the multi-functional thermal protection composite coating is prepared by a process comprising: The thickness of the single-layer coating film in the step S5 is 80-100 microns.

5. Application of the multifunctional thermal protection composite coating layer in claim 1 to the surface of a commercial lithium ion battery aluminum shell.

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