Disclosure of Invention
Aiming at the defects of the current lithium ion battery thermal protection technology, the invention provides a thermal protection material for a lithium ion battery and a preparation method thereof, wherein the thermal protection material is low-temperature heat-conducting high-temperature ceramic heat-insulating.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows.
The thermal protection material for the lithium ion battery comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 20-70 parts of white carbon black, 5-10 parts of KH-550, 0.5-10 parts of peroxide vulcanizing agent, 2-8 parts of anti-aging agent, 0.2-5 parts of accelerator, 5-15 parts of boron nitride nanoparticles, 15-40 parts of silica aerogel and 20-80 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 60-70 parts of white carbon black, 8-10 parts of KH-550, 9-10 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4-5 parts of accelerator, 12-15 parts of boron nitride nanoparticles, 30-40 parts of silica aerogel and 60-80 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 20 parts of white carbon black, KH-5505 parts, 0.5 part of peroxide vulcanizing agent, 2 parts of anti-aging agent, 0.2 part of accelerator, 5 parts of boron nitride nanoparticles, 15 parts of silica aerogel and 20 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 70 parts of white carbon black, 10 parts of KH-55010 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 5 parts of accelerator, 15 parts of boron nitride nanoparticles, 40 parts of silica aerogel and 80 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 70 parts of white carbon black, 10 parts of KH-55010 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 5 parts of accelerator, 15 parts of boron nitride nanoparticles, 40 parts of silica aerogel and 80 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4 parts of accelerator, 12 parts of boron nitride nanoparticles, 30 parts of silica aerogel and 60 parts of porcelain forming filler;
preferably, the thermal protection material comprises the following components in parts by weight: 100 parts of ethylene propylene diene monomer, 45 parts of white carbon black, KH-5508 parts, 6 parts of peroxide vulcanizing agent, 4 parts of anti-aging agent, 2 parts of accelerator, 10 parts of boron nitride nanoparticles, 25 parts of silica aerogel and 50 parts of porcelain forming filler;
preferably, in the thermal protection material, the peroxide vulcanizing agent is one or a mixture of DCP, DTBP and BPMC; more preferably DCP;
preferably, in the thermal protection material, the accelerator is one or a mixture of several of PDM, TAIC and TAC; more preferably PDM;
preferably, in the thermal protection material, the porcelain forming filler is a mixture of APP, zinc borate, silica, montmorillonite and mica;
more preferably, in the porcelain forming filler, the mass ratio of silica, mica and montmorillonite is 50: (10-30): (40-20); further preferably 50:20-30:20-30, still further preferably 50:30:20 or 50:20: 30;
further preferably, in the porcelain forming filler, the APP accounts for 5-15% of the total mass of the silica, the mica and the montmorillonite; further preferably 12% to 15%, still further preferably 12% or 15%;
still further preferably, in the porcelain forming filler, the mass of the zinc borate is 10-20% of the total mass of the silica, the mica and the montmorillonite; further preferably 15% to 20%, still further preferably 15% or 20%;
preferably, the anti-aging agent in the thermal protection material is MMBZ;
preferably, the propylene content of the EPDM in the thermal protection material is 30-50 wt%;
a method of making a thermal protective material for a lithium ion battery, wherein the method comprises the steps of:
(1) adding APP, zinc borate, silicon dioxide, montmorillonite and mica into a high-speed mixer, mixing for 10min at the rotating speed of 800-;
(2) mixing Ethylene Propylene Diene Monomer (EPDM), white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 at 20-50 ℃ for 5-8min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(3) mixing the first mixed rubber obtained in the step (2) with the product obtained in the step (1), an accelerator and a peroxide vulcanizing agent at 40-60 ℃ for 3-5min, thinly passing through a lower sheet, and cooling to obtain a second mixed rubber;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (5) placing the product obtained in the step (4) into microwave vulcanization equipment for microwave vulcanization to obtain the thermal protection material for the lithium battery.
Preferably, in the step (5), the temperature of the microwave vulcanization is 110-130 ℃, and the time of the microwave vulcanization is 4-12 min.
The invention also provides a lithium ion battery pack, which comprises a plurality of batteries arranged together, wherein adjacent batteries of the battery pack are separated by the thermal protection material provided by the invention.
The beneficial effects of the invention at least comprise the following aspects:
in a high-temperature or open-fire ablation environment, eutectic melting and eutectic reaction can occur among the ceramic forming fillers in the thermal protection material, so that a compact ceramic body with certain strength is formed, the ceramic body has certain supporting capacity, the complete shape can be still maintained even in an explosion and high-temperature combustion environment, and the flame retardant property and smoke suppression property of the material are improved.
The ceramic layer generated by the thermal protection material burning at high temperature or open fire can effectively obstruct the heat transmission, and effectively reduce the peripheral temperature of adjacent lithium ion batteries, thereby improving the safety performance and playing a good thermal runaway protection role.
Furthermore, in the formula design of the thermal protection material, the silicon dioxide aerogel particles are connected through the boron nitride nanoparticles to form a heat conduction network, so that the heat conduction coefficient of Ethylene Propylene Diene Monomer (EPDM) under the normal temperature condition is effectively improved; and when the boron nitride nanoparticles are in a high-temperature environment, the crystal form of the boron nitride nanoparticles is changed, and the EPDM thermal decomposition product gas damages a heat conduction network, so that the heat conductivity coefficient is reduced under the high-temperature condition, and the flame retardance and the thermal protection performance of the material are not influenced.
Detailed Description
The invention is illustrated below with reference to specific examples. It will be understood by those skilled in the art that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention in any way.
The raw materials and reagents used in the following examples are all commercially available products unless otherwise specified. Wherein, the purchase conditions of part of the reagents are as follows:
white carbon black: chemical Limited, Kathon, Jinan;
boron nitride nanoparticles: chemical products, Inc. of Jixin, Henan;
silica aerogel: changsha fudakang chemical Co., Ltd;
APP (ammonium polyphosphate): shandong Yunjing chemical Co., Ltd;
zinc borate: henan Shengkun chemical products, Inc.;
montmorillonite: shandong Xiang constant chemical industry Co., Ltd;
mica: guangzhou Jiaqi biotechnology limited;
ethylene propylene diene monomer: mitsui chemical (shanghai) limited.
Example 1
The thermal protection material for the lithium battery is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 20 parts of white carbon black, KH-5505 parts, 0.5 part of peroxide vulcanizing agent, 2 parts of anti-aging agent, 0.2 part of accelerator, 5 parts of boron nitride nanoparticles, 15 parts of silica aerogel and 20 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass ratio of the silicon dioxide, the mica and the montmorillonite is 50: 10: 40;
wherein the mass of the APP is 5 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 10 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material for the lithium battery in the embodiment comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 800r/min, and then discharged for later use;
(2) mixing Ethylene Propylene Diene Monomer (EPDM), white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 at 20 ℃ for 5min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 40 ℃ for 3min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (4) placing the product obtained in the step (4) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 110 ℃, and the vulcanization time is 4 min. And obtaining the thermal protection material for the lithium battery.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Example 2
The thermal protection material for the lithium battery is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 30 parts of white carbon black, KH-5507 parts, 3 parts of peroxide vulcanizing agent, 3 parts of anti-aging agent, 1 part of accelerator, 8 parts of boron nitride nanoparticles, 20 parts of silica aerogel and 30 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass ratio of the silicon dioxide, the mica and the montmorillonite is 50:20:30, of a nitrogen-containing gas;
wherein the mass of the APP is 8 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 13 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material for the lithium battery in the embodiment comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 1000r/min, and then discharged for later use;
(2) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 for 5min at the temperature of 30 ℃, thinly passing through a lower sheet, and cooling to obtain a first rubber compound;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 45 ℃ for 3min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (4) placing the product obtained in the step (4) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 115 ℃, and the vulcanization time is 6 min. And obtaining the thermal protection material for the lithium battery.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Example 3
The thermal protection material for the lithium battery is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 40 parts of white carbon black, KH-5507 parts, 5 parts of peroxide vulcanizing agent, 4 parts of anti-aging agent, 2 parts of accelerator, 10 parts of boron nitride nanoparticles, 25 parts of silica aerogel and 40 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass ratio of the silicon dioxide, the mica and the montmorillonite is 50: 25: 25;
wherein the mass of the APP is 10 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 15 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material for the lithium battery in the embodiment comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 1500r/min, and then discharged for later use;
(2) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 at 50 ℃ for 6min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 50 ℃ for 4min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (4) placing the product obtained in the step (4) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 120 ℃, and the vulcanization time is 8 min. And obtaining the thermal protection material for the lithium battery.
Wherein the peroxide vulcanizing agent is DTBP;
the accelerator is TAIC;
the anti-aging agent is MMBZ.
Example 4
The thermal protection material for the lithium battery is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 70 parts of white carbon black, 10 parts of KH-55010 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 5 parts of accelerator, 15 parts of boron nitride nanoparticles, 40 parts of silica aerogel and 80 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass ratio of the silicon dioxide, the mica and the montmorillonite is 50:30: 20;
wherein the mass of the APP is 15 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 20 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material for the lithium battery in the embodiment comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 1500r/min, and then discharged for later use;
(2) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 at 50 ℃ for 8min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 60 ℃ for 5min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (4) placing the product obtained in the step (4) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 130 ℃, and the vulcanization time is 12 min. And obtaining the thermal protection material for the lithium battery.
Wherein the peroxide vulcanizing agent is BPMC;
the accelerator is TAC;
the anti-aging agent is MMBZ.
Example 5
The thermal protection material for the lithium battery is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4 parts of accelerator, 12 parts of boron nitride nanoparticles, 30 parts of silica aerogel and 60 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass part ratio of the silicon dioxide, the mica and the montmorillonite is 50:20:30, of a nitrogen-containing gas;
wherein the mass of the APP is 12 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 15 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material for the lithium battery in the embodiment comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 1200r/min, and then discharged for later use;
(2) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 for 8min at the temperature of 30 ℃, thinly passing through a lower sheet, and cooling to obtain a first rubber compound;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 40 ℃ for 5min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (5) placing the product obtained in the step (4) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 120 ℃, and the vulcanization time is 10 min. And obtaining the thermal protection material for the lithium battery.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Comparative example 1
The thermal protection material of the comparative example is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4 parts of accelerator, 12 parts of boron nitride nanoparticles and 30 parts of silica aerogel.
The preparation method of the thermal protection material of the comparative example comprises the following steps:
(1) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles, silica aerogel and KH-550 for 8min at the temperature of 30 ℃, thinly passing through a lower sheet, and cooling to obtain a first rubber compound;
(2) mixing an accelerator, a peroxide vulcanizing agent and the first mixed rubber obtained in the step (1) at 40 ℃ for 5min according to the mass parts, thinly passing through a lower sheet, and cooling to obtain a second mixed rubber;
(3) die pressing the second rubber compound obtained in the step (2) at normal temperature to obtain a die pressing product with a set shape and size;
(4) and (4) placing the product obtained in the step (3) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 120 ℃, and the vulcanization time is 10 min. Obtaining the thermal protection material.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Comparative example 2
The thermal protection material of the comparative example is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4 parts of accelerator and 12 parts of boron nitride nanoparticles.
The preparation method of the thermal protection material of the comparative example comprises the following steps:
(1) mixing EPDM, white carbon black, an anti-aging agent, boron nitride nanoparticles and KH-550 at 30 ℃ for 8min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(2) mixing an accelerator, a peroxide vulcanizing agent and the first mixed rubber obtained in the step (1) at 40 ℃ for 5min according to the mass parts, thinly passing through a lower sheet, and cooling to obtain a second mixed rubber;
(3) die pressing the second rubber compound obtained in the step (2) at normal temperature to obtain a die pressing product with a set shape and size;
(4) and (4) placing the product obtained in the step (3) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 120 ℃, and the vulcanization time is 10 min. Obtaining the thermal protection material.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Comparative example 3
The thermal protection material of the comparative example is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent and 4 parts of accelerator.
The preparation method of the thermal protection material of the comparative example comprises the following steps:
(1) mixing EPDM, white carbon black, an anti-aging agent and KH-550 for 8min at the temperature of 30 ℃, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(2) mixing an accelerator, a peroxide vulcanizing agent and the first mixed rubber obtained in the step (1) at 40 ℃ for 5min according to the mass parts, thinly passing through a lower sheet, and cooling to obtain a second mixed rubber;
(3) die pressing the second rubber compound obtained in the step (2) at normal temperature to obtain a die pressing product with a set shape and size;
(4) and (4) placing the product obtained in the step (3) in microwave vulcanization equipment for microwave vulcanization, wherein the microwave vulcanization temperature is 120 ℃, and the vulcanization time is 10 min. Obtaining the thermal protection material.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Comparative example 4
The thermal protection material of the comparative example is prepared from the following raw materials in parts by mass: 100 parts of ethylene propylene diene monomer, 60 parts of white carbon black, KH-5508 parts, 9 parts of peroxide vulcanizing agent, 8 parts of anti-aging agent, 4 parts of accelerator, 30 parts of silica aerogel and 60 parts of porcelain forming filler;
wherein the porcelain-forming filler is a mixture of APP, zinc borate, silicon dioxide, montmorillonite and mica;
wherein the mass ratio of the silicon dioxide, the mica and the montmorillonite is 50:20:30, of a nitrogen-containing gas;
wherein the mass of the APP is 12 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
wherein the mass of the zinc borate is 15 percent of the total mass of the silicon dioxide, the mica and the montmorillonite;
the preparation method of the thermal protection material applied to the lithium battery comprises the following steps:
(1) according to the mass parts, APP, zinc borate, silica, montmorillonite and mica are added into a high-speed mixer, mixed for 10min at the rotating speed of 1200r/min, and then discharged for later use;
(2) mixing EPDM, white carbon black, an anti-aging agent, silica aerogel and KH-550 at 30 ℃ for 8min, thinly passing through a lower sheet, and cooling to obtain a first mixed rubber;
(3) mixing an accelerator, a peroxide vulcanizing agent, the first rubber compound obtained in the step (2) and the product obtained in the step (1) at 40 ℃ for 5min, thinly passing through a lower sheet, and cooling to obtain a second rubber compound;
(4) die pressing the second rubber compound obtained in the step (3) at normal temperature to obtain a die pressing product with a set shape and size;
(5) and (5) placing the product obtained in the step (4) into microwave vulcanization equipment for microwave vulcanization, wherein the vulcanization temperature is 120 ℃, and the vulcanization time is 10 min. Obtaining the thermal protection material.
Wherein the peroxide vulcanizing agent is DCP;
the accelerant is PDM;
the anti-aging agent is MMBZ.
Test example: performance testing
The thermal protective materials prepared in examples 1 to 5 and comparative examples 1 to 4 were subjected to performance tests:
(1) mechanical Property test
The dumbbell-shaped test sample is cut according to the national standard GB/T528-.
Table 1: mechanical property test results of thermal protective materials prepared in examples 1 to 5 and comparative examples 1 to 4
According to the test results in table 1, it can be seen that the thermal protection material prepared by the invention still maintains a certain mechanical property, and can meet the basic physical and mechanical property requirements of the battery pack protection material.
(2) Oxygen index test
The test is carried out according to the oxygen index test standard GB/T10707-. Sample size: 100mm long, 6.5mm wide and 3mm thick.
Table 2: oxygen index of thermal protective material prepared in examples 1 to 5 and comparative examples 1 to 4
According to the oxygen index test result shown in the table 2, the ceramic filler can effectively block the heat transmission in the combustion environment, and the flame retardant property of the thermal protection material is improved.
(3) Determination of thermal conductivity
The thermal conductivity of the material was tested by laser method according to ASTM E1461. The sample is cylindrical sheet, and the size is as follows: the diameter is 12.7 +/-0.1 mm, and the thickness is 0.5-4 mm.
Table 3: thermal conductivity of thermal protective material prepared in examples 1 to 5 and comparative examples 1 to 4
The test results in table 3 show that the heat conduction channel formed by the boron nitride and silica aerogel system designed by the invention can effectively improve the heat conductivity coefficient of EPDM, and the heat diffusion condition of the thermal protection material can be improved at normal temperature; in a high-temperature environment, the boron nitride and the ceramic filler are subjected to thermal reaction, the crystal form is transformed, and a ceramic body is formed, and the formed ceramic layer has a low heat conductivity coefficient, which shows that the formula of the invention does not influence the heat insulation performance of the thermal protection material at a high temperature.
(4) Test for vitrifying Properties
A sample with the size of 80mm multiplied by 10mm multiplied by 4mm is placed into a muffle furnace through cutting, the temperature is raised to 600 ℃ at the heating rate of 10 ℃/min and then is preserved for 1h, then the temperature is lowered to the room temperature, the sample is taken out, and the bending strength of the ceramic body is measured according to the GB/T14390-.
Table 4: properties of ceramicized products of thermal protective materials obtained in examples 1 to 5 and comparative examples 1 to 4
The test results in table 4 show that the formula designed by the invention can form a self-supporting compact ceramic body with certain strength, effectively block the transmission of heat between adjacent battery packs and improve the safety of the battery packs. FIG. 1 is an SEM image of a cross section of a ceramic body formed by the thermal protective material prepared in example 5 after being heated in a muffle furnace, and from a microscopic morphology, a sample forms a dense ceramic body in a high-temperature environment.
(5) Smoke Rate test
The characteristic signal transmittance of the thermal protection material at 800 ℃ is measured according to Q/AY69A-2003 coating layer smoke determination method-infrared, visible light and laser transmittance method.
Table 5: characteristic signal transmittance of thermal protective material obtained in examples 1 to 5 and comparative examples 1 to 4
The test results in table 5 show that the formation of the ceramic layer effectively reduces the gas generation amount, destroys and blocks the volatilization channel of the gas, reduces the smoke generation amount, and improves the transmittance of the characteristic signal.
Application experiment of thermal protective material
In the experiment, the heating rod is used as a heat source to trigger the battery to generate thermal runaway. A4 mm thick sheet of thermal protective material prepared in example 5 was placed between two 6A ternary lithium batteries, a heating rod was placed against one of the batteries, the heating rod, and the sheet were fixedly connected together in a wire-wound manner, and then heated.
As a result, the first battery started burning after 15min and 26s, then explosion occurred at 17min and 12s, the thermal protection material connected with the first battery started burning, flame gradually decreased after 19min and 26s, and flame extinguished after 22min and 45 s.