Phase-change gel-state thermal runaway protection material for lithium battery and preparation method of phase-change gel-state thermal runaway protection material

Abstract

The invention relates to the technical field of lithium batteries, in particular to a preparation method of a phase-change gel-state thermal runaway protection material for a lithium battery, which comprises the following steps: coating a phase-change material on a rolled mica sheet with the thickness of 0.2 mm; covering the phase change material with a coiled mica sheet with the thickness of 0.2 mm; the surface flatness of the material in the second step is adjusted through a pressing roller, and size cutting is conducted; the periphery of the material cut in the third step is sealed with a glass fabric adhesive tape; putting the material subjected to edge sealing in the step 4 into a drying oven at 60 DEG C to obtain a semi-finished product; vacuumizing and sealing the cut semi-finished product by using an aluminum plastic film sealing bag with proper specification and size; the periphery of the sealed aluminum-plastic film product is folded by a folding and pressing machine, and then the edge is sealed by a polyimide adhesive tape to improve the sealing property. Thermal runaway protection based on the phase change material is adopted, high-temperature flames are blocked through the fireproof aluminum-plastic film layer, and heat is absorbed through the high-latent-heat phase change material to protect the battery cell from being damaged by high-temperature impact.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a phase change gel thermal runaway protection material for lithium batteries and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are widely used in power battery packs due to their high specific energy, high power, long life, low self-discharge rate and other advantages. The performance of lithium-ion batteries is very sensitive to temperature. If the temperature of the battery is too high, too low or the temperature difference is large, the battery is prone to aging, performance degradation and capacity loss. When lithium-ion batteries are subjected to electrical abuse, mechanical abuse and thermal abuse, high temperature will be caused due to the accumulation of internal heat, leading to thermal runaway, and then causing fire and explosion accidents. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a phase change gel thermal runaway protection material for lithium batteries to solve the above problems.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: a phase change gel thermal runaway protection material for lithium batteries, including a phase change material layer, mica sheets are connected to both sides of the phase change material layer, and an aluminum-plastic film is coated on the outside of the mica sheets; The phase change material includes the following components in parts by weight: Silica sol 6 - 12 parts Deionized water 2 - 12 parts N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane 5 - 18 parts Melamine 0.5 - 3.5 parts Nanoscale silicon powder 0.5 - 2.0 parts Ethylene glycol 4 - 8 parts Hydrotalcite 18 - 26 parts Aluminum hydroxide 3 - 16 parts Mica powder 4 - 12 parts Magnesium hydroxide 5 - 9 parts Paraffin wax 6 - 10 parts.

[0005] As a further aspect of the present invention, the phase change material layer and the mica sheets are in a sandwich structure.

[0006] As a further aspect of the present invention, the preparation method of the phase change material is specifically as follows: Step 1, weigh silica sol, paraffin wax, deionized water, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane in parts by weight, and stir and disperse; Step 2, gradually add nanoscale silicon powder and melamine powder in parts by weight, and stir and disperse at high speed; Step 3: Stand still and cool down. When the material temperature is lower than 30°C, gradually add hydrotalcite powder, aluminum hydroxide powder, magnesium hydroxide powder, and mica powder by weight, and stir and disperse. Step 4: Stand still and cool down. When the material temperature is lower than 30°C, put the cooled mixture into a defoaming machine for low-pressure vacuum defoaming for 20 minutes to obtain a phase change material.

[0007] As a further solution of the present invention, the stirring speed in Step 1 is 600 - 800 rpm, and the dispersion time is 12 - 15 minutes.

[0008] As a further solution of the present invention, the stirring speed in Step 2 is 1200 - 1500 rpm, and the dispersion time is 20 - 25 minutes; the stirring speed in Step 3 is 1500 - 2000 rpm, and the dispersion time is 20 - 25 minutes.

[0009] As a further solution of the present invention, the particle size fineness of the phase change material is less than 100 μm, and the viscosity is 2000 - 6000 mPa·s.

[0010] A preparation method of a phase change gel thermal runaway protection material for lithium batteries, the specific steps are as follows: Step 1: Coating a phase change material on a 0.2 mm thick rolled mica sheet. Step 2: Covering a 0.2 mm thick rolled mica sheet on the phase change material. Step 3: Adjusting the surface flatness of the material in Step 2 through a pressure roller and performing size cutting. Step 4: Sealing the edges of the material cut in Step 3 with a fiberglass cloth tape. Step 5: Putting the material with sealed edges in Step 4 into an oven at 60°C to obtain a semi-finished product. Step 6: Vacuum-sealing the cut semi-finished product with an aluminum-plastic film sealing bag of a suitable specification size.

[0011] As a further solution of the present invention, the preparation method further includes folding the edges of the sealed aluminum-plastic film product around with a folder, and then sealing the edges with a polyimide tape to improve the sealing performance.

[0012] As a further solution of the present invention, the thickness of the phase change material is 0.2 - 2.0 mm.

[0013] As a further solution of the present invention, the particle size fineness of the phase change material is less than 100 μm, and the viscosity of the phase change material is 2000 - 6000 mPa·s.

[0014] Since the present invention adopts the above technical solutions, the advantages and positive effects of the present invention are: 1. A high latent heat gel - state phase - change material formula can meet the protection of adjacent battery cells after the thermal runaway of the battery cell. 2. The overall structure has the characteristics of fire - resistance, heat - insulation, and heat - absorption. After the thermal runaway of a ternary lithium battery, the temperature can reach 800 °C and high - temperature flames erupt. The materials of the present invention can be used for the protection against the thermal runaway of lithium batteries. 3. Adapted to the coating process, with high production efficiency, and the product can be cut into appropriate sizes according to the requirements of the application scenario. 4. The present invention adopts thermal runaway protection based on phase - change materials. The high - temperature flame is blocked by a fire - resistant aluminum - plastic film layer, and the heat is absorbed by the high - latent - heat phase - change material to protect the battery cell from high - temperature impact damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of a phase - change gel - state thermal runaway protection material for a lithium battery according to the present invention.

[0016] Figure 2 It is a preparation flow chart of the phase - change material.

[0017] Figure 3 It is a preparation flow chart of a phase - change gel - state thermal runaway protection material for a lithium battery according to the present invention.

[0018] Figure 4 It is a curve graph of the hot - surface and cold - surface temperatures of Example 1.

[0019] Figure 5 It is a curve graph of the hot - surface and cold - surface temperatures of Example 2.

[0020] Figure 6 It is a curve graph of the hot - surface and cold - surface temperatures of Example 3.

[0021] In the figure: 1 is the phase - change material layer, 2 is the mica sheet, and 3 is the aluminum - plastic film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0023] As Figure 1 shown, a phase - change gel - state thermal runaway protection material for a lithium battery according to the present invention includes a phase - change material layer 1. Mica sheets 2 are connected to both sides of the phase - change material layer 1, and an aluminum - plastic film 3 is coated outside the mica sheets 2; the phase - change material layer 1 and the mica sheets 2 form a sandwich structure.

[0024] Example 1 The phase - change material includes the following components in parts by weight: Silica sol 6 parts Deionized water 2 parts N-(β - aminoethyl)-γ - aminopropyltrimethoxysilane 5 parts Melamine 0.5 parts Nano-silicon powder 0.5 parts Ethylene glycol 4 parts Hydrotalcite 18 parts Aluminum hydroxide 3 parts Mica powder 4 parts Magnesium hydroxide 5 parts Paraffin wax 6 parts; As Figure 2 shown, the preparation method of the phase change material is as follows: Weigh silica sol, paraffin wax, deionized water, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and disperse at a stirring speed of 600 rpm for 12 min; gradually add nano-silicon powder and melamine powder, and disperse at a high speed of 1200 rpm for 20 min; let it stand and cool until the material temperature is below 30°C, and gradually add hydrotalcite powder, aluminum hydroxide powder, magnesium hydroxide powder, and mica powder, and disperse at a stirring speed of 1500 rpm for 20 min; let it stand and cool until the material temperature is below 30°C, put the cooled mixture into a defoaming machine for low-pressure vacuum defoaming for 20 min to obtain a phase change material sample. Take a sample and test the fineness of the sample with a scraper, the particle size fineness of the sample <100um, take a sample and test the viscosity with a rotary viscometer, and the viscosity of the sample is 2000 mPa▪s.

[0025] As Figure 3 shown, a preparation method of a phase change gel thermal runaway protection material for a lithium battery is as follows: Step 1, coat a phase change material with a thickness of 0.2 mm on a 0.2 mm thick rolled mica sheet; Step 2, cover the 0.2 mm thick rolled mica sheet on the phase change material; Step 3, adjust the surface flatness of the material in Step 2 through a pressure roller and perform size cutting; Step 4, seal the four sides of the material cut in Step 3 with a fiberglass cloth tape; Step 5, put the material sealed in Step 4 into an oven at 60°C to obtain a semi-finished product; Step 6, vacuum-seal the cut semi-finished product with an aluminum-plastic film seal bag of a suitable specification; Step 7, fold the four sides of the sealed aluminum-plastic film product with a folder, and then seal the edges with a polyimide tape to improve the sealing performance; The particle size fineness of the phase change material <100um, and the viscosity of the phase change material is 2000 mPa▪s.

[0026] Example 2 The phase change material of the present invention comprises the following components in parts by weight: Silica sol 9 parts Deionized water 7 parts 11 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane 3 parts of melamine 1.2 parts of nanoscale silicon powder 6 parts of ethylene glycol 22 parts of hydrotalcite 9 parts of aluminum hydroxide 8 parts of mica powder 7 parts of magnesium hydroxide 8 parts of paraffin wax.

[0027] The preparation method of the phase change material is as follows: Weigh silica sol, paraffin wax, deionized water, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and disperse them at a stirring speed of 700 rpm for 14 min; gradually add nanoscale silicon powder and melamine powder, and disperse them at a high speed of 1350 rpm for 23 min; let it stand and cool until the material temperature is below 30°C, then gradually add hydrotalcite powder, aluminum hydroxide powder, magnesium hydroxide powder, and mica powder, and disperse them at a stirring speed of 1800 rpm for 23 min; let it stand and cool until the material temperature is below 30°C, and put the cooled mixture into a defoaming machine for low-pressure vacuum defoaming for 20 min to obtain a phase change material sample. Take a sample and test the fineness of the sample with a scraper, the particle size fineness of the sample is <100 um, take a sample and test the viscosity with a rotary viscometer, and the viscosity of the sample is 4000 mPa·s.

[0028] The preparation method of a phase change gel thermal runaway protection material for a lithium battery is as follows: Step 1, coat a phase change material with a thickness of 1.1 mm on a 0.2-mm-thick rolled mica sheet; Step 2, cover the phase change material with a 0.2-mm-thick rolled mica sheet; Step 3, adjust the surface flatness of the material in Step 2 through a pressure roller and perform size cutting; Step 4, seal the four sides of the material cut in Step 3 with a fiberglass cloth tape; Step 5, put the material sealed in Step 4 into an oven at 60°C to obtain a semi-finished product; Step 6, vacuum-seal the cut semi-finished product with an aluminum-plastic film seal bag of the appropriate specification size; Step 7, fold the four sides of the sealed aluminum-plastic film product with a folder, and then seal the edges with a polyimide tape to improve the sealing performance; The particle size fineness of the phase change material is <100 um, and the viscosity of the phase change material is 4000 mPa·s.

[0029] Example 3 The phase change material of the present invention comprises the following components in parts by weight: 12 parts of silica sol 12 parts of deionized water 18 parts of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane 3.5 parts of melamine 2.0 parts of nanoscale silicon powder 8 parts of ethylene glycol 26 parts of hydrotalcite 16 parts of aluminum hydroxide 12 parts of mica powder 9 parts of magnesium hydroxide 10 parts of paraffin wax; The preparation method of the phase change material is as follows: Weigh silica sol, paraffin wax, deionized water, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, and disperse them at a stirring speed of 800 rpm for 15 minutes; gradually add nanoscale silicon powder and melamine powder, and disperse them at a high speed of 1500 rpm for 25 minutes; let it stand and cool until the material temperature is below 30°C, then gradually add hydrotalcite powder, aluminum hydroxide powder, magnesium hydroxide powder, and mica powder, and disperse them at a stirring speed of 2000 rpm for 25 minutes; let it stand and cool until the material temperature is below 30°C, and put the cooled mixture into a defoaming machine for low-pressure vacuum defoaming for 20 minutes to obtain a phase change material sample. Take a sample and test the fineness of the sample with a scraper. The particle size fineness of the sample is <100um. Take a sample and test the viscosity with a rotary viscometer. The viscosity of the sample is 6000 mPa·s.

[0030] The preparation method of a phase change gel thermal runaway protection material for lithium batteries is as follows: Step 1, coat a phase change material with a thickness of 2.0 mm on a 0.2-mm-thick rolled mica sheet; Step 2, cover the 0.2-mm-thick rolled mica sheet on the phase change material; Step 3, adjust the surface flatness of the material in Step 2 through a pressure roller and perform size cutting; Step 4, seal the four sides of the material cut in Step 3 with a fiberglass cloth tape; Step 5, put the material with sealed sides in Step 4 into an oven at 60°C to obtain a semi-finished product; Step 6, seal the cut semi-finished product in a suitable-sized aluminum-plastic film sealed bag under vacuum; Step 7, fold the four sides of the sealed aluminum-plastic film product with a folder, and then seal the edges with a polyimide tape to improve the sealing performance; The particle size fineness of the phase change material is <100um, and the viscosity of the phase change material is 2000 - 6000 mPa·s.

[0031] Test data The outer layer of the test tooling is fixed and clamped with an iron plate and nuts; the battery cell is adjacent to the heat insulation material, with a cold surface probe arranged on the heat insulation material and a hot surface probe arranged on the battery cell; the temperature detection device is connected to the mobile power supply to start temperature detection; a hole is opened in the iron plate on the puncture surface, and an iron nail is punctured into the battery cell to trigger thermal runaway.

[0032] Table 1 shows the performance test of the cold surface and the hot surface in Example 1 Table 2 shows the performance test of the cold surface and the hot surface in Example 2 Table 3 shows the performance test of the cold surface and the hot surface in Example 3 From Tables 1 - 3, Figure 4-5 it can be seen that the maximum hot surface temperatures in Examples 1 - 3 are 812 °C, 816 °C, and 817 °C respectively, and the maximum cold surface temperatures in Examples 1 - 3 are 173 °C, 168 °C, and 185 °C respectively, and the battery cells on the cold surface are not triggered; in summary, the present invention adopts thermal runaway protection based on phase change materials, blocks high-temperature flames through the refractory aluminum-plastic film layer, and absorbs heat through the high-latent heat phase change material to protect the battery cell from high-temperature impact damage.

[0033] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes or modifications can be made to these implementation manners without departing from the principles and essence of the present invention. The protection scope of the present invention is only defined by the appended claims.

Claims

1. A phase change gel-state thermal runaway protection material for lithium batteries, characterized in that: It includes a phase change material layer (1), mica sheets (2) are connected to both sides of the phase change material layer (1), and an aluminum-plastic film (3) is coated on the outside of the mica sheets (2); The phase change material includes the following components in parts by weight: Silica sol: 6 - 12 parts Deionized water: 2 - 12 parts N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane: 5 - 18 parts Melamine: 0.5 - 3.5 parts Nanoscale silicon powder: 0.5 - 2.0 parts Ethylene glycol: 4 - 8 parts Hydrotalcite: 18 - 26 parts Aluminum hydroxide: 3 - 16 parts Mica powder: 4 - 12 parts Magnesium hydroxide: 5 - 9 parts Paraffin wax: 6 - 10 parts.

2. The phase change gel thermal runaway protection material for a lithium battery according to claim 1, wherein: The phase change material layer (1) and the mica sheets (2) form a sandwich structure.

3. The phase change gel thermal runaway protection material for lithium batteries according to claim 1, characterized in that: The preparation method of the phase change material is as follows: Step 1, weigh silica sol, paraffin wax, deionized water, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane according to parts by weight, and stir and disperse them; Step 2, gradually add nanoscale silicon powder and melamine powder according to parts by weight, and stir and disperse them at high speed; Step 3, let it stand and cool, when the material temperature is lower than 30°C, gradually add hydrotalcite powder, aluminum hydroxide powder, magnesium hydroxide powder, and mica powder according to parts by weight, and stir and disperse them; Step 4, let it stand and cool, when the material temperature is lower than 30°C, put the cooled mixture into a defoaming machine and perform low-pressure vacuum defoaming for 20 min to obtain the phase change material.

4. The phase change gel thermal runaway protection material for lithium batteries according to claim 3, characterized in that: In Step 1, the stirring speed is 600 - 800 rpm, and the dispersion time is 12 - 15 min.

5. The phase change gel thermal runaway protection material for lithium batteries and its preparation method according to claim 3, characterized in that: In Step 2, the stirring speed is 1200 - 1500 rpm, and the dispersion time is 20 - 25 min; in Step 3, the stirring speed is 1500 - 2000 rpm, and the dispersion time is 20 - 25 min.

6. A phase change gel thermal runaway protection material for a lithium battery according to claim 3, characterized in that: The particle size fineness of the phase change material is less than 100 um, and the viscosity is 2000 - 6000 mPa·s.

7. A preparation method of a phase change gel thermal runaway protection material for a lithium battery according to any one of claims 1-6, characterized in that: Specific steps are as follows: Step 1, coat the phase change material on a 0.2-mm-thick rolled mica sheet; Step 2, cover the 0.2-mm-thick rolled mica sheet on the phase change material; Step 3, adjust the surface flatness of the material in Step 2 through a pressure roller and perform size cutting; Step 4, seal the four sides of the material cut in Step 3 with a fiberglass cloth tape; Step 5, put the material sealed on the four sides in Step 4 into an oven at 60°C to obtain a semi-finished product; Step 6, vacuum-seal the cut semi-finished product with a sealed bag made of an aluminum-plastic film of a suitable specification size.

8. The preparation method of a phase change gel thermal runaway protection material for a lithium battery according to claim 7, characterized in that: The preparation method also includes folding the four sides of the sealed aluminum-plastic film product with a folder, and then sealing the edges with a polyimide tape to improve the sealing performance.

9. The preparation method of a phase change gel-state thermal runaway protection material for a lithium battery according to claim 7, characterized in that: The thickness of the phase change material is 0.2 - 2.0 mm.

10. The preparation method of a phase change gel thermal runaway protection material for a lithium battery according to claim 9, characterized in that: The particle size fineness of the phase change material is less than 100 um, and the viscosity of the phase change material is 2000 - 6000 mPa·s.

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