Ultrathin composite heat insulation plate for new energy battery

Abstract

The invention discloses an ultrathin composite heat insulation plate for a new energy battery, and belongs to the technical field of heat insulation materials for new energy automobiles. The invention aims to solve the problem that an existing new energy battery thermal insulation material cannot give consideration to thermal insulation, flame retardance, low density and low thickness. The ultrathin composite heat insulation plate for the new energy battery is composed of a heat absorption plate and a fiber reinforced aerogel plate. The ultrathin composite heat insulation plate is used for the new energy battery.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal insulation materials for new energy vehicles. Background Art

[0002] New energy vehicles are one of the emerging industries, and the new energy vehicle market has achieved rapid growth. Among them, power batteries are the core components of new energy vehicles. At present, lithium-ion batteries have become the mainstream batteries for new energy vehicles due to their advantages such as high specific energy and long cycle life. Due to the high energy density of lithium-ion batteries, batteries are prone to safety hazards such as thermal runaway under extreme conditions of battery charging and discharging, collision or external environment. Therefore, it is extremely necessary to add heat-insulating and flame-retardant materials between the cells of lithium battery packs. And as the energy density of lithium batteries becomes higher and higher, the heat-insulating and flame-retardant materials between the cells must be as thin as possible while ensuring the safety of the battery module.

[0003] At present, commonly used thermal insulation and flame retardant materials include foam, aerogel, ultrafine glass wool, high silica wool, vacuum insulation board, etc. However, if commonly used thermal insulation and flame retardant materials want to meet the "Safety Requirements for Power Batteries for Electric Vehicles" and the requirement that the battery system will not catch fire or explode within 5 minutes, the thickness of the material needs to be increased. Therefore, the characteristics of thermal insulation and flame retardancy and low density and low thickness cannot be taken into account at the same time. Summary of the invention

[0004] The present invention aims to solve the problem that existing new energy battery insulation materials cannot take into account both heat insulation and flame retardancy as well as low density and low thickness, and further provide an ultra-thin composite insulation board for new energy batteries.

[0005] An ultra-thin composite heat insulation board for new energy batteries, which consists of a heat absorbing board and a fiber-reinforced aerogel board, specifically, the heat absorbing board and the fiber-reinforced aerogel board are packaged or glued from bottom to top, or the fiber-reinforced aerogel board, the heat absorbing board and the fiber-reinforced aerogel board are packaged or glued from bottom to top;

[0006] The heat absorbing plate is an inorganic plate or a phase change plate; the thickness of the heat absorbing plate is 2 mm to 4 mm, and the thickness of the fiber reinforced aerogel plate is 1 mm to 4 mm.

[0007] The beneficial effects of the present invention are:

[0008] 1. The inorganic board described in the present invention is a calcium sulfate board or a magnesium oxychloride cement board, which contains a large amount of crystal water and can lose the crystal water when the temperature reaches 100°C. In this process, a large amount of heat will be absorbed to ensure temperature stability for a period of time; the phase change board described in the present invention is a fiber-reinforced aerogel board impregnated with a phase change material. The phase change material will absorb a large amount of latent heat during the melting process to slow down the temperature increase rate.

[0009] 2. The fiber-reinforced aerogel board of the present invention has a thermal conductivity of less than 0.04 W / (m·K) and excellent thermal insulation performance.

[0010] 3. The trigger temperature of battery thermal runaway is within 200°C, and the use of fiber-reinforced aerogel boards as insulation boards cannot meet the insulation requirements. The ultra-thin composite insulation board prepared by the present invention has low density and low thickness, and when battery thermal runaway occurs, the fiber-reinforced aerogel board first isolates the heat and delays the temperature rise. As the insulation board reaches 100°C, the inorganic board begins to gradually lose crystalline water, so that the temperature of the insulation board remains stable for a period of time. When all the crystalline water in the inorganic board is lost, the temperature of the insulation board continues to rise. When the temperature reaches the temperature at which the phase change material begins to undergo a phase change, the phase change material gradually melts, allowing the insulation board to remain stable again. After the phase change material is completely melted, the temperature of the insulation board continues to rise. Due to the action of the crystalline water and the phase change material in the insulation board, a buffer period is generated during the temperature rise process, which avoids a sharp increase in temperature, thereby further reducing the risk of battery thermal runaway.

[0011] The invention is used for an ultra-thin composite heat insulation board for a new energy battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a temperature comparison diagram of the back temperature surface of the heat insulation board prepared in Examples 1 to 2 and Experiments 1 to 2 in a 650°C heating test;

[0013] Figure 2 This is a comparison chart of the back temperature surface temperature of the insulation board prepared in Examples 1 to 2 and Comparative Experiments 1 to 2 in the open flame heating test. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any combination of the specific implementation modes.

[0015] Specific implementation method 1: This implementation method is an ultra-thin composite heat insulation board for new energy batteries, which is composed of a heat absorbing board and a fiber-reinforced aerogel board, specifically, the heat absorbing board and the fiber-reinforced aerogel board are packaged or glued from bottom to top, or the fiber-reinforced aerogel board, the heat absorbing board and the fiber-reinforced aerogel board are packaged or glued from bottom to top;

[0016] The heat absorbing plate is an inorganic plate or a phase change plate; the thickness of the heat absorbing plate is 2 mm to 4 mm, and the thickness of the fiber reinforced aerogel plate is 1 mm to 4 mm.

[0017] The beneficial effects of this embodiment are:

[0018] 1. The inorganic board described in this embodiment is a calcium sulfate board or a magnesium oxychloride cement board, which contains a large amount of crystallization water and can lose the crystallization water when the temperature reaches 100°C. In this process, it will absorb a large amount of heat to ensure temperature stability for a period of time; the phase change board described in this embodiment is a fiber-reinforced aerogel board impregnated with a phase change material. The phase change material will absorb a large amount of latent heat during the melting process to slow down the temperature increase rate.

[0019] 2. The fiber-reinforced aerogel board described in this embodiment has a thermal conductivity of less than 0.04 W / (m·K) and excellent thermal insulation performance.

[0020] 3. The trigger temperature of battery thermal runaway is within 200°C, and the use of fiber-reinforced aerogel boards as insulation boards cannot meet the insulation requirements. The ultra-thin composite insulation board prepared in this embodiment has low density and low thickness, and when battery thermal runaway occurs, the fiber-reinforced aerogel board first isolates the heat and delays the temperature rise. As the insulation board reaches 100°C, the inorganic board begins to gradually lose crystalline water, so that the temperature of the insulation board remains stable for a period of time. When all the crystalline water in the inorganic board is lost, the temperature of the insulation board continues to rise. When the temperature reaches the temperature at which the phase change material begins to undergo a phase change, the phase change material gradually melts, causing the insulation board to remain stable again. After the phase change material is completely melted, the temperature of the insulation board continues to rise. Due to the action of the crystalline water and the phase change material in the insulation board, a buffer period is generated during the temperature rise process, which avoids a sharp increase in temperature, thereby further reducing the risk of battery thermal runaway.

[0021] Specific implementation method 2: This implementation method is different from the specific implementation method 1 in that the inorganic board is a calcium sulfate board or a magnesium oxychloride cement board. The rest is the same as the specific implementation method 1.

[0022] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that: the inorganic plate is prepared according to the following steps:

[0023] 1. Weigh 80 to 100 parts of calcium sulfate dihydrate powder, 0.5 to 1 part of toughening agent, 0.5 to 1 part of hardening agent, 0.1 to 0.5 part of retarder and 40 to 60 parts of water by mass, and then mix them to obtain calcium sulfate slurry;

[0024] Or weigh 80 to 100 parts of magnesium oxide, 20 to 30 parts of anhydrous magnesium chloride, 2 to 3 parts of toughening agent, 1 to 2 parts of hardening agent, 0.3 to 0.5 parts of retarder and 50 to 60 parts of water by mass, and then mix them to obtain magnesium oxychloride cement slurry;

[0025] 2. Place the calcium sulfate slurry or magnesium oxychloride cement slurry in a mold, solidify and shape it for 6 hours to 10 hours at room temperature, and finally dry it for 4 hours to 10 hours at a temperature of 40° C. to 80° C. to obtain a calcium sulfate board or magnesium oxychloride cement board. Others are the same as the first or second specific implementation.

[0026] Specific embodiment 4: This embodiment is different from one of specific embodiments 1 to 3 in that: the toughening agent described in step 1 is one of glass fiber, ceramic fiber and wood fiber or a combination of several thereof; the hardening agent described in step 1 is one of quartz powder, borax and sodium silicate or a combination of several thereof; the retarder described in step 1 is one of citric acid, sodium hexametaphosphate and sodium polyphosphate or a combination of several thereof. Others are the same as specific embodiments 1 to 3.

[0027] Specific implementation example 5: This implementation example is different from specific implementation examples 1 to 4 in that: the phase change plate is made of a fiber-reinforced aerogel plate impregnated with a phase change material; the phase change material is paraffin or calcium chloride hexahydrate. The rest is the same as specific implementation example 4.

[0028] Specific implementation method 6: This implementation method is different from the specific implementation methods 1 to 5 in that: the phase change plate is prepared according to the following steps:

[0029] The phase change material is heated and melted, and at the phase change temperature, the fiber-reinforced aerogel plate is immersed in the heated and molten phase change material for 2h to 4h, the immersed fiber-reinforced aerogel plate is taken out, and dried for 3h to 6h at a temperature of 30°C to 60°C, and finally cured at room temperature for 6h to 12h to obtain a phase change plate;

[0030] The fiber-reinforced aerogel board is an aerogel-impregnated glass fiber board or an aerogel-impregnated ceramic fiber board. The rest is the same as the specific embodiments 1 to 5.

[0031] Specific embodiment 7: This embodiment is different from specific embodiments 1 to 6 in that the fiber-reinforced aerogel board is an aerogel-impregnated glass fiber board or an aerogel-impregnated ceramic fiber board. The rest is the same as specific embodiments 1 to 6.

[0032] Specific embodiment 8: This embodiment is different from any one of specific embodiments 1 to 7 in that: the fiber-reinforced aerogel plate is prepared according to the following steps:

[0033] 1. Weigh 80 to 120 parts of silica sol, 3 to 5 parts of inorganic additives, 1 to 2 parts of coupling agent and 200 to 300 parts of deionized water according to the mass ratio;

[0034] 2. Add the weighed inorganic additive into deionized water and stir until it is evenly dissolved to obtain an inorganic additive solution;

[0035] 3. adding the weighed silica sol and coupling agent into the inorganic additive solution and stirring to obtain a mixed sol;

[0036] 4. Impregnate the inorganic fiber felt in the mixed sol, vacuum impregnate for 2h to 4h at room temperature and a vacuum degree of 0.05MPa to 0.1MPa, take out the impregnated inorganic fiber felt, and age the gel at a temperature of 40°C to 80°C for 12h to 48h to obtain a fiber-reinforced aerogel;

[0037] 5. Under the conditions of a temperature of 40° C. to 50° C. and a pressure of 6 MPa to 10 MPa, the fiber-reinforced aerogel is supercritically dried for 12 h to 24 h to obtain a fiber-reinforced aerogel plate. The rest is the same as in Specific Embodiments 1 to 7.

[0038] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the density of the silica sol described in step 1 is 1.2 g / cm 3 ~1.3g / cm 3 , the mass percentage of silicon dioxide in the silica sol is greater than 30%; the inorganic additive in step 1 is one of lithium silicate, sodium silicate and sodium phosphate or a combination of several thereof; the coupling agent in step 1 is one of KH550, KH560 and KH792 or a combination of several thereof; the inorganic fiber felt in step 4 is glass fiber felt, alumina ceramic fiber felt or aluminum silicate ceramic fiber felt; the thickness of the inorganic fiber felt in step 4 is 4mm to 6mm. Others are the same as those in specific embodiments 1 to 8.

[0039] Specific embodiment 10: This embodiment differs from the specific embodiments 1 to 9 in that: when encapsulation is adopted, the encapsulation process is specifically carried out according to the following steps:

[0040] 1. Stacking in order from bottom to top: a polyimide film, a heat absorbing plate, a fiber-reinforced aerogel plate, and a polyimide film, or stacking in order from bottom to top: a polyimide film, a fiber-reinforced aerogel plate, a heat absorbing plate, a fiber-reinforced aerogel plate, and a polyimide film, to obtain a stacked piece; the thickness of the polyimide film is 0.1 mm to 0.25 mm;

[0041] 2. Place the stacked parts on an ultrasonic welding machine for ultrasonic welding. Other steps are the same as those in the first to ninth embodiments.

[0042] The polyimide film of this specific embodiment has high mechanical strength and good solvent resistance, and can ensure the compatibility and stability of the composite thermal insulation board.

[0043] The following examples are used to verify the beneficial effects of the present invention:

[0044] Embodiment 1:

[0045] An ultra-thin composite heat insulation board for new energy batteries, which consists of a heat absorbing board and a fiber-reinforced aerogel board; specifically, the heat absorbing board and the fiber-reinforced aerogel board are packaged from bottom to top;

[0046] The heat absorbing plate is an inorganic plate; the thickness of the heat absorbing plate is 2 mm, and the thickness of the fiber reinforced aerogel plate is 2 mm;

[0047] The inorganic board is a calcium sulfate board; the inorganic board is specifically prepared according to the following steps:

[0048] 1. Weigh 100 parts of calcium sulfate dihydrate powder, 0.5 parts of toughening agent, 0.5 parts of hardening agent, 0.1 parts of retarder and 60 parts of water by mass, and then mix them to obtain calcium sulfate slurry;

[0049] The toughening agent is glass fiber; the hardening agent is quartz powder; the retarder is citric acid;

[0050] 2. Place the calcium sulfate slurry in a mold, solidify it at room temperature for 7 hours, and finally dry it at 60°C for 5 hours to obtain a calcium sulfate board.

[0051] The fiber-reinforced aerogel board is an aerogel-impregnated ceramic fiber board; the fiber-reinforced aerogel board is specifically prepared according to the following steps:

[0052] 1. Weigh 100 parts of silica sol, 3 parts of inorganic additives, 1 part of coupling agent and 300 parts of deionized water according to the mass proportions;

[0053] The density of the silica sol is 1.2 g / cm 3 , the mass percentage of silicon dioxide in the silica sol is 32%; the inorganic additive is sodium silicate; the coupling agent is silane coupling agent KH560;

[0054] 2. Add the weighed inorganic additive into deionized water and stir until it is evenly dissolved to obtain an inorganic additive solution;

[0055] 3. adding the weighed silica sol and coupling agent into the inorganic additive solution and stirring to obtain a mixed sol;

[0056] Fourth, the inorganic fiber felt is impregnated in the mixed sol, vacuum impregnated for 2 hours at room temperature and a vacuum degree of 0.08 MPa, the impregnated inorganic fiber felt is taken out, and the gel is aged for 24 hours at a temperature of 40°C to obtain a fiber-reinforced aerogel;

[0057] The inorganic fiber felt is aluminum silicate ceramic fiber felt, and the manufacturer is Zhejiang Aoka Refractory Materials Co., Ltd.; the inorganic fiber felt is dense and uniform inside, and has a thickness of 5 mm;

[0058] 5. Under the conditions of temperature of 43°C and pressure of 9.0 MPa, the fiber-reinforced aerogel was supercritically dried for 24 hours to obtain a fiber-reinforced aerogel plate.

[0059] The packaging process is specifically carried out in the following steps:

[0060] 1. Stacking the polyimide film, the heat absorbing plate, the fiber-reinforced aerogel plate and the polyimide film in order from bottom to top to obtain a stacked component; the thickness of the polyimide film is 0.125 mm;

[0061] 2. Place the stacked parts on an ultrasonic welding machine, and perform ultrasonic welding for 0.1s at room temperature and an ultrasonic frequency of 7KHz, with a delay time of 1.2s and a cooling time of 0.7s.

[0062] Embodiment 2: This embodiment is different from Embodiment 1 in that: the fiber-reinforced aerogel plate, the heat-absorbing plate and the fiber-reinforced aerogel plate are packaged from bottom to top; the thickness of the fiber-reinforced aerogel plate is 1 mm; the packaging process: the polyimide film, the fiber-reinforced aerogel plate, the heat-absorbing plate, the fiber-reinforced aerogel plate and the polyimide film are stacked in the order from bottom to top. The rest is the same as Embodiment 1.

[0063] Comparative Experiment 1: This comparative experiment is different from Example 1 in that the fiber-reinforced aerogel plate is omitted and the thickness of the heat absorbing plate is 4 mm. Other aspects are the same as Example 1.

[0064] Comparative Experiment 2: This comparative experiment is different from Example 1 in that the heat absorbing plate is omitted and the thickness of the fiber-reinforced aerogel plate is 4 mm. Others are the same as Example 1.

[0065] The insulation boards prepared in Examples 1 to 2 and Comparative Experiments 1 to 2 were tested on a 650°C heating table. The experimental samples included 2mm fiber reinforced aerogel board composite calcium sulfate board (Example 1, fiber board subjected to temperature), 2mm fiber reinforced aerogel board composite calcium sulfate board (Example 1, calcium sulfate board subjected to temperature), 1mm fiber reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber reinforced aerogel board (Example 2); 4mm calcium sulfate board (Comparative Experiment 1), 4mm fiber reinforced aerogel board (Comparative Experiment 2).

[0066] Figure 1The temperature comparison chart of the back surface of the insulation board prepared by Examples 1 to 2 and Comparative Experiments 1 to 2 in the 650°C heating test. As can be seen from the figure, when the 4mm fiber reinforced aerogel board is selected as the insulation board, the back temperature quickly reaches 200°C; when the calcium sulfate board and the composite insulation board (2mm inorganic board + 2mm fiber reinforced aerogel board) are selected and the calcium sulfate board is used as the fire-receiving surface, the back temperature is stabilized at 100°C for a period of time and then the back temperature rises rapidly. The composite insulation board (2mm inorganic board + 2mm fiber reinforced aerogel board) is selected and the fiber reinforced aerogel board is used as the fire-receiving surface. First, the fiberboard insulates most of the heat, and the inorganic board loses crystal water more slowly than directly contacting high temperature. The temperature on the back of the composite insulation board is maintained at 100°C for a long time, which delays the temperature rise on the back of the composite insulation board, and the time for the temperature on the back of the composite insulation board to reach 200°C is extended by about 3 times. Using 1mm fiber reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber reinforced aerogel board as the insulation board reduces the thickness of the fiber board on the temperature-bearing surface, but the time for the back temperature to reach 200°C is still extended by about 2.5 times compared with the 4mm fiber reinforced aerogel board. Since the insulation board is used for the interlayer of the battery pack, the 1mm fiber reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber reinforced aerogel board solution is more suitable for battery insulation boards.

[0067] According to the testing method of GB / T 10294-2008, the thermal conductivity of the fiber-reinforced aerogel plate prepared in Example 1 was measured to be 0.034 W / (m·K).

[0068] The insulation boards prepared in Examples 1 to 2 and Comparative Experiments 1 to 2 were subjected to open flame heating tests. The experimental samples included 2mm fiber reinforced aerogel board composite calcium sulfate board (Example 1, fiber board subjected to temperature), 2mm fiber reinforced aerogel board composite calcium sulfate board (Example 1, calcium sulfate board subjected to temperature), 1mm fiber reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber reinforced aerogel board (Example 2); 4mm calcium sulfate board (Comparative Experiment 1), 4mm fiber reinforced aerogel board (Comparative Experiment 2).

[0069] Figure 2 This is a comparison chart of the back temperature surface temperature of the heat insulation board prepared in Examples 1 to 2 and Experiments 1 to 2 in the open flame heating test.

[0070] When 4mm fiber-reinforced aerogel board and composite insulation board (2mm inorganic board + 2mm fiber-reinforced aerogel board) were selected and calcium sulfate board was used as the fire-receiving surface for the experiment, the back temperature quickly reached 200℃; when calcium sulfate board was used, the back temperature was maintained at 100℃ for a period of time, and then the temperature continued to rise. The composite insulation board (2mm inorganic board + 2mm fiber-reinforced aerogel board) was selected and the fiber-reinforced aerogel board was used as the fire-receiving surface. First, the fiberboard insulated most of the heat, and the inorganic board lost its crystal water more slowly than directly contacting high temperature. The temperature on the back of the composite insulation board remained at 100℃ for a long time, delaying the temperature rise on the back of the composite insulation board, and the time for the temperature on the back of the composite insulation board to reach 200℃ was extended by about 5 times. Using 1mm fiber-reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber-reinforced aerogel board as the insulation board greatly extended the time for the back temperature to rise to 200℃. Since the thermal insulation board is used for the interlayer of the battery pack, the 1mm fiber reinforced aerogel board + 2mm calcium sulfate board + 1mm fiber reinforced aerogel board solution is more suitable for the battery thermal insulation board.

Claims

1. An ultra-thin composite heat insulation board for new energy batteries, characterized in that It consists of a heat absorbing plate and a fiber-reinforced aerogel plate, specifically, the heat absorbing plate and the fiber-reinforced aerogel plate are packaged or glued from bottom to top, or the fiber-reinforced aerogel plate, the heat absorbing plate and the fiber-reinforced aerogel plate are packaged or glued from bottom to top; The heat absorbing plate is an inorganic plate or a phase change plate; the thickness of the heat absorbing plate is 2 mm to 4 mm, and the thickness of the fiber reinforced aerogel plate is 1 mm to 4 mm.

2. The ultra-thin composite heat insulation board for new energy batteries according to claim 1, characterized in that The inorganic board is a calcium sulfate board or a magnesium oxychloride cement board.

3. The ultra-thin composite heat insulation board for new energy batteries according to claim 2, characterized in that The inorganic plate is specifically prepared according to the following steps:

1. Weigh 80 to 100 parts of calcium sulfate dihydrate powder, 0.5 to 1 part of toughening agent, 0.5 to 1 part of hardening agent, 0.1 to 0.5 part of retarder and 40 to 60 parts of water by mass, and then mix them to obtain calcium sulfate slurry; Or weigh 80 to 100 parts of magnesium oxide, 20 to 30 parts of anhydrous magnesium chloride, 2 to 3 parts of toughening agent, 1 to 2 parts of hardening agent, 0.3 to 0.5 parts of retarder and 50 to 60 parts of water by mass, and then mix them to obtain magnesium oxychloride cement slurry; 2. Place the calcium sulfate slurry or magnesium oxychloride cement slurry in a mold, solidify it at room temperature for 6 hours to 10 hours, and finally dry it at a temperature of 40°C to 80°C for 4 hours to 10 hours to obtain a calcium sulfate board or magnesium oxychloride cement board.

4. The ultra-thin composite heat insulation board for new energy batteries according to claim 3, characterized in that The toughening agent described in step one is one of glass fiber, ceramic fiber and wood fiber or a combination of several thereof; the hardening agent described in step one is one of quartz powder, borax and sodium silicate or a combination of several thereof; the retarder described in step one is one of citric acid, sodium hexametaphosphate and sodium polyphosphate or a combination of several thereof.

5. The ultra-thin composite heat insulation board for new energy batteries according to claim 1, characterized in that The phase change plate is prepared by impregnating a fiber-reinforced aerogel plate with a phase change material; the phase change material is paraffin or calcium chloride hexahydrate.

6. The ultra-thin composite heat insulation board for new energy batteries according to claim 5, characterized in that The phase change plate is specifically prepared according to the following steps: The phase change material is heated and melted, and at the phase change temperature, the fiber-reinforced aerogel plate is immersed in the heated and molten phase change material for 2h to 4h, the immersed fiber-reinforced aerogel plate is taken out, and dried for 3h to 6h at a temperature of 30°C to 60°C, and finally cured at room temperature for 6h to 12h to obtain a phase change plate; The fiber-reinforced aerogel board is an aerogel-impregnated glass fiber board or an aerogel-impregnated ceramic fiber board.

7. The ultra-thin composite heat insulation board for new energy batteries according to claim 1, characterized in that The fiber-reinforced aerogel board is an aerogel-impregnated glass fiber board or an aerogel-impregnated ceramic fiber board.

8. An ultra-thin composite heat insulation board for new energy batteries according to claim 6 or 7, characterized in that The fiber-reinforced aerogel plate is specifically prepared according to the following steps:

1. Weigh 80 to 120 parts of silica sol, 3 to 5 parts of inorganic additives, 1 to 2 parts of coupling agent and 200 to 300 parts of deionized water according to the mass ratio; 2. Add the weighed inorganic additive into deionized water and stir until it is evenly dissolved to obtain an inorganic additive solution; 3. adding the weighed silica sol and coupling agent into the inorganic additive solution and stirring to obtain a mixed sol; 4. Impregnate the inorganic fiber felt in the mixed sol, vacuum impregnate for 2h to 4h at room temperature and a vacuum degree of 0.05MPa to 0.1MPa, take out the impregnated inorganic fiber felt, and age the gel at a temperature of 40°C to 80°C for 12h to 48h to obtain a fiber-reinforced aerogel; 5. Under the conditions of a temperature of 40° C. to 50° C. and a pressure of 6 MPa to 10 MPa, the fiber-reinforced aerogel is supercritically dried for 12 h to 24 h to obtain a fiber-reinforced aerogel plate.

9. The ultra-thin composite heat insulation board for new energy batteries according to claim 8, characterized in that The density of the silica sol described in step 1 is 1.2 g / cm 3 ~1.3g / cm 3 The mass percentage of silicon dioxide in the silica sol is greater than 30%; the inorganic additive in step one is one of lithium silicate, sodium silicate and sodium phosphate or a combination of several thereof; the coupling agent in step one is one of KH550, KH560 and KH792 or a combination of several thereof; the inorganic fiber felt in step four is glass fiber felt, alumina ceramic fiber felt or aluminum silicate ceramic fiber felt; the thickness of the inorganic fiber felt in step four is 4 mm to 6 mm.

10. The ultra-thin composite heat insulation board for new energy batteries according to claim 1, characterized in that When encapsulation is used, the encapsulation process is specifically carried out in the following steps:

1. Stacking in order from bottom to top: a polyimide film, a heat absorbing plate, a fiber-reinforced aerogel plate, and a polyimide film, or stacking in order from bottom to top: a polyimide film, a fiber-reinforced aerogel plate, a heat absorbing plate, a fiber-reinforced aerogel plate, and a polyimide film, to obtain a stacked piece; the thickness of the polyimide film is 0.1 mm to 0.25 mm; 2. Place the stacked parts on an ultrasonic welding machine for ultrasonic welding.

Images