COMPOSITE SEPARATOR CONTAINING AROMATIC POLYAMIDE AND MANUFACTURING METHOD THEREOF, AND SECONDARY BATTERY

Abstract

The application relates to an aromatic polyamide composite separator, a method for preparing the same, and a secondary battery having the same. The aromatic polyamide composite separator includes glass fiber and an aromatic polyamide. The composite separator has a thermal shrinkage percentage of less than 3% at 300 C. A method for preparing the aromatic polyamide composite separator is also provided. The composite separator of the application exhibits excellent mechanical performance and heat resistance, which is especially applicable to secondary batteries.

Claims

1. An aromatic polyamide composite separator, comprising glass fiber and aromatic polyamide, a thermal shrinkage percentage of the composite separator is less than 3% or less than 1% at 300 C.; and/or the thermal shrinkage percentage of the composite separator is less than 5% or less than 3% or less than 1% at 500 C.

2. (canceled)

3. The aromatic polyamide composite separator of claim 1, wherein an air permeability of the composite separator is in a range of 50-500 s/100 cc or 80-300 s/100 cc or 90-200 s/100 cc; a thickness of the composite separator is in a range of 12-40 m or 15-30 m or 18-25 m; and/or a tensile strength of the composite separator is 50-300 MPa or 80-250 MPa or 100-200 MPa.

4. (canceled)

5. (canceled)

6. The aromatic polyamide composite separator of claim 1, wherein the aromatic polyamide is at least one selected from the group consisting of poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide), poly(p-benzamide) and polysulfone amide; a porosity of the aromatic polyamide is in a range of 40-80% or 45-75% or 50-70%; and/or a content of the aromatic polyamide is in a range of 10-60 wt % or 20-50 wt %.

7. (canceled)

8. (canceled)

9. The aromatic polyamide composite separator of claim 1, wherein the glass fiber is fiberglass fabric; a thickness of the fiberglass fabric is in a range of 8-50 m or 10-30 m or 12-30 m; and/or a diameter of monofilament glass fiber in the fiberglass fabric is less than or equals to 15 m, or less than or equals to 8 m, or less than or equals to 5 m.

10. (canceled)

11. (canceled)

12. A method for preparing the aromatic polyamide composite separator of claim 1, comprising the following steps: (1) providing at least one ionic liquid, at least one aromatic polyamide and at least one solvent, mixing the ionic liquid, the aromatic polyamide and the solvent to form a mixed solution; (2) immersing glass fiber into the mixed solution to form glass fibers immersed with the mixed solution, or coating the mixed solution onto surfaces of the glass fibers to form glass fibers coated with the mixed solution, and then leading the glass fibers immersed or coated with the mixed solution into a coagulation bath to form a membrane therein; (3) extracting the membrane with an extractant to remove the ionic liquid and solvents therein, and then drying the membrane to yield the composite separator.

13. The method of claim 12, wherein step (3) comprises extracting the membrane with an extractant to remove the ionic liquid and the solvents, drying the membrane, and treating the membrane under high-temperature to form the composite separator; a temperature for treating the membrane under high-temperature is in a range of 200-350 C., preferably 250-300 C.; a time for treating the membrane under high-temperature is in a range of 5-40 minutes, preferably 10-20 minutes; and/or the treating the membrane under high-temperature is hot air heating and/or infrared heating.

14. (canceled)

15. (canceled)

16. (canceled)

17. The method of claim 12, wherein the ionic liquid is at least one selected from the group consisting of quaternary ammonium salt, quaternary phosphonium salt, imidazolium onium salt, pyridinium onium salt, piperidinium salt and pyrrolidine salt.

18. The method of claim 12, wherein the aromatic polyamide is at least one selected from the group consisting of poly(p-phenylene terephthalamide), poly(m-phenylene isophthalamide), poly(p-benzamide) and polysulfone amide; the aromatic polyamide is aromatic polyamide fiber.

19. (canceled)

20. The method of claim 12, wherein a mass ratio of the ionic liquid to the aromatic polyamide is in a range from 2:1 to 10:1, or from 3:1 to 9:1 or from 3:1 to 6:1.

21. The method of claim 12, wherein forming a mixed solution in step (1) is implemented by at least one of the following: mixing an ionic liquid with a first solvent to form an ionic liquid solution; mixing an aromatic polyamide with a second solvent to form an aromatic polyamide solution; and mixing the ionic liquid solution with the aromatic polyamide solution to obtain the mixed solution; or mixing an ionic liquid with a first solvent to form an ionic liquid solution; forming an aromatic polyamide solution by polymerization, wherein a second solvent is applied in the polymerization; and mixing the ionic liquid solution with the aromatic polyamide solution to obtain the mixed solution; or mixing the ionic liquid, the aromatic polyamide and a third solvent to form the mixed solution.

22. (canceled)

23. (canceled)

24. The method of claim 21, wherein the first solvent is at least one selected from the group consisting of water, ethanol, propanol, isopropanol, glycerol, tetrahydrofuran, pyridine, dichloromethane, tri-chloromethane, ethyl acetate, N,N-dimethyl formamide, N,N-dimethyl acetamide, N-methyl pyrrolidone and polyethylene glycol; and/or a mass ratio of the first solvent to the ionic liquid is in a range from 0.05:1 to 0.8:1, or from 0.1:1 to 0.5:1.

25. The method of claim 21, wherein the second solvent is at least one selected from the group consisting of N-methyl pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide and tri-ethyl phosphate; and/or a mass ratio of the second solvent to the aromatic polyamide is in a range from 4:1 to 15:1, or from 5:1 to 10:1.

26. (canceled)

27. (canceled)

28. The method of claim 21, wherein the third solvent is at least one selected from the following: N-methyl pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide and dimethyl sulfoxide; a mass fraction of the third solvent in the mixed solution is 20-80% or 40-70%.

29. (canceled)

30. The method of claim 12, wherein the coagulation bath comprises a first component; and the first component is water or dichloromethane.

31. The method of claim 30, wherein the coagulation bath further comprises a second component; and the second component is at least one selected from the group consisting of N-methyl pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, dimethyl sulfoxide and triethyl phosphate.

32. The method of claim 30, wherein a mass fraction of water or dichloromethane in the coagulation bath is in a range of 10-99.9% or 20-80% or 30-60%; and/or a temperature of the coagulation bath is in a range of 0-80 C. or 20-60 C.

33. (canceled)

34. The method of claim 12, wherein a time for forming the membrane in step (2) is in a range of 10-250 seconds or 20-150 seconds.

35. The method of claim 12, wherein the extractant is at least one selected from the group consisting of water, dichloromethane, trichloromethane and ethanol; a temperature of the extractant is in a range of 20-100 C. or 30-80 C.

36. (canceled)

37. The method of claim 12, wherein the drying is infrared drying and/or hot air drying; a drying temperature is in a range of 50-150 C. or 80-120 C.

38. (canceled)

39. A secondary battery, comprising the aromatic polyamide composite separator of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 shows an SEM photograph of surfaces of the aromatic polyamide composite separator prepared in embodiment 1.

[0051] FIG. 2 shows an SEM photograph of a cross-section of the aromatic polyamide composite separator prepared in embodiment 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0052] The present disclosure will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed.

[0053] In the present disclosure, thermal shrinkage percentage test, air permeability test, tensile strength test and porosity test are conducted to the separators prepared in embodiments 1, 4, 6, 8 and 10, and results obtained are listed in table 2; further, thermal shrinkage percentage test is also conducted to polyolefin separator, aluminum oxide coating polyolefin separator and aluminum oxide coating PET separator, wherein PET is an abbreviation of poly(ethylene terephthalate); results are listed in table 1. Specific methods for the tests above are described as below:

[0054] Thermal shrinkage percentage test: first, measuring a length A1 and a width B1 of a separator separately; next, placing the measured separator into an oven with certain temperature and heating it for an hour; and then, taking out the separator from the oven and cool it to room temperature; finally, measuring the length A2 and width B2 of the separator for the second time. An MD thermal shrinkage percentage of the separator equals to (1A2/A1)100%; and a TD thermal shrinkage percentage of the separator equals to (1B2/B1)100%.

[0055] Air permeability test: Detecting a time needed for 100 cc airflow to pass through a separator at stable pressure by a gas transmission rate tester, wherein a size of the separator is 60 mm100 mm, and the gas transmission rate tester is Gurley-4320-controller digital timer/auto counter (matching with Gurley-4110) importing from the US.

[0056] Tensile strength test: detecting a tensile strength of a separator at a speed of 20 mm/min by an electronic universal tester QJ210C, wherein a size of the separator is 150 mm25 mm, and the electronic universal tester is produced by Shanghai Qingji Instrumentation Science &Technology Co., LTD.

[0057] Porosity test: the porosity values are calculated by the formula below, (1(WL1L2K)/1/(L1L2DL1L2K/2))100%, wherein W represents for quality of a sample (g); K represents for basis weight of the fiberglass fabric (g/cm.sup.2); 1 represents for density of the aromatic polyamide (g/cm.sup.3); 2 represents for density of the glass fiber (g/cm.sup.3); L1 represents for length of the sample (mm); L2 represents for width of the sample (mm); and D represents for thickness of the sample (mm).

Embodiment 1

[0058] First, polymerizing in a reaction tank to obtain a poly (m-phenylene isophthalamide) solution 4500 g, wherein DMAC acting as the solvent, and a mass percentage concentration of the poly (m-phenylene isophthalamide) is 9%. Second, mixing 2300 g of N-methyl-N-propyl pyrrolidinium tetrafluoroborate with 700 g of anhydrous ethanol in a stirred tank to obtain an ionic liquid solution. Third, injecting the poly (m-phenylene isophthalamide) solution into the stirred tank to mix with the ionic liquid solution therein uniformly to obtain a uniformly mixed solution. Fourth, injecting the uniformly mixed solution into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 12 m and a monofilament diameter thereof is 4.5 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is a mixed solvent of water and DMAC, a mass fraction of water is 50%, a temperature of the coagulation bath is 60 C. and a gel time thereof is 20 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 90 C., wherein the coated-membrane is extracted with water to remove the solvents therein, in this way, the coated poly (m-phenylene isophthalamide) membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, drying the porous-structured composite membrane with hot air at a drying temperature of 120 C., and heat-treating in a hot air oven at 250 C. for 40 minutes to yield the aromatic polyamide composite separator.

[0059] FIG. 1 shows an SEM photograph of surfaces of the aromatic polyamide composite separator prepared in embodiment 1 and FIG. 2 shows an SEM photograph of a cross-section of the aromatic polyamide composite separator prepared in embodiment 1.

[0060] Thermal shrinkage percentage tests are conducted to the composite separator prepared in embodiment 1 and other commercial separators separately. To be specific, other commercial separators refer to an aluminum oxide coating PET separator, an aluminum oxide coating polyolefin separator and a polyolefin separator. Results are listed in Table 1, wherein TD represents for the TD thermal shrinkage percentage, MD represents for an MD thermal shrinkage percentage, and PET is an abbreviation of polyethylene terephthalate. As shown in Table 1, the heat shrinkage rate of the composite separator prepared in embodiment 1 is still less than 2% even at 600 C. In contrast, the aluminum oxide coating PET separator has already cracked at 300 C. and is not suitable to be tested at 300 C. or higher temperature; further, even tested under 300 C., the thermal shrinkage percentage of the aluminum oxide coating PET separator is higher than that of the composite separator prepared in embodiment 1. Meanwhile, both the aluminum oxide coating polyolefin separator and polyolefin separator have also cracked or shrunk into a mass at 200 C., not suitable to be tested at 200 C. or above; further, their thermal shrinkage percentage at 120 C. is far higher than that of the composite separator prepared in embodiment 1. In conclusion, the composite separator of the present disclosure has excellent thermal stability performance.

Embodiment 2

[0061] Embodiment 2 is similar with embodiment 1, and the differences lie in that, 230 g of deionized water is mixed with 2300 g of N-methyl-N-propyl pyrrolidinium tetrafluoroborate uniformly at the stirred tank to obtain an ionic liquid solution.

Embodiment 3

[0062] Embodiment 3 is similar with embodiment 2, and the differences lie in that, the coagulation bath is water, the temperature of the coagulation bath is 80 C., and the gel time thereof is 10 seconds, the drying temperature is 150 C.

Embodiment 4

[0063] First, polymerizing in a reaction tank to obtain 2670 g of polysulfone amide solution, wherein NMP acting as a solvent, and a mass percentage concentration of polysulfone amide is 10%. Second, mixing 800 g of 1-methyl-3-propyl imidazolium acetate and 40 g of ethyl acetate uniformly in a stirred tank to obtain an ionic liquid solution. Third, injecting the-polysulfone amide solution into the stirred tank to mix with the ionic liquid solution therein uniformly to obtain a uniform mixed solution. Fourth, injecting the uniform mixed solution into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 14 m and a monofilament diameter of the fiberglass fabric is 5 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is mixed solvents of water and NMP, a mass fraction of water is 30%, a temperature of the coagulation bath is 50 C. and a gel time thereof is 100 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 80 C., wherein the coated-membrane is extracted with water to remove the solvents therein, in this way, the coated-polysulfone amide membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, drying the porous-structured composite membrane with infrared rays at a drying temperature of 120 C., and heat-treating in a hot air oven at 200 C. for 40 minutes to yield the aromatic polyamide composite separator.

Embodiment 5

[0064] First, polymerizing by twin-screw to obtain a poly (m-phenylene isophthalamide) solution 1000 g, wherein DMAC acting as a solvent, and a mass percentage concentration of the poly (m-phenylene isophthalamide) is 20%. Second, mixing 2000 g of methyl triethyl ammonium acetate with 200 g of deionized water uniformly in a stirred tank to obtain an ionic liquid solution, wherein the stirred tank being heated to 50 C. Third, injecting the obtained poly (m-phenylene isophthalamide) solution into the stirred tank to mix with the ionic liquid solution uniformly to obtain a uniform mixed solution. Fourth, injecting the uniform mixed solution into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 15 m and a monofilament diameter thereof is 5 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is mixed solvents of water and DMAC, a mass fraction of water is 20%, a temperature of the coagulation bath is 40 C. and a gel time thereof is 150 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 80 C., wherein the coated-membrane is extracted with water to remove the solvents therein, in this way, the coated poly (m-phenylene isophthalamide) membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, drying the porous-structured composite membrane with hot air at a drying temperature of 120 C., and heat-treating under an infrared lamp at 250 C. for 30 minutes to yield the aromatic polyamide composite separator.

Embodiment 6

[0065] First, polymerizing in a reaction tank to obtain a poly(p-phenylene terephthalamide) solution 2000 g, wherein DMF acting as a solvent, and a mass percentage concentration of poly(p-phenylene terephthalamide) is 6.25%. Second, mixing 800 g of 1-methyl-3-butyl imidazolium hydrochloride and 100 g of dichloromethane in a stirred tank uniformly to obtain an ionic liquid solution, wherein the stirred tank being heated to 50 C. Third, injecting the poly(p-phenylene terephthalamide) solution into the stirred tank to mix with the ionic liquid solution therein uniformly to obtain a uniform mixed solution. Fourth, injecting the uniformly mixed solution into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial uncoated fiberglass fabric is 12 m and a monofilament diameter thereof is 4.5 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is a mixed solvent of dichloromethane and DMF, a mass fraction of dichloromethane is 30%, a temperature of the coagulation bath is 20 C. and a gel time thereof is 150 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 30 C., wherein the coated-membrane is extracted with dichloromethane to remove the solvents therein, in this way, the coated poly(p-phenylene terephthalamide) membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, the porous-structured composite membrane undergoing a hot air drying at a drying temperature of 80 C., and heat-treating in a hot air oven at 350 C. for 10 minutes to yield the aromatic polyamide composite separator.

Embodiment 7

[0066] Embodiment 7 is similar to embodiment 6, and the differences lie in that, the coagulation bath is dichloromethane, and the temperature of the extraction tank is 20 C.

Embodiment 8

[0067] First, dissolving 200 g of poly (m-phenylene isophthalamide) spun into 1000 g of DMAC solvent to obtain a poly (m-phenylene isophthalamide) solution, wherein a mass percentage concentration of poly (m-phenylene isophthalamide) being 16.7%. Second, mixing 600 g of methyl tri-butyl ammonium hydrochloride with 300 g of deionized water in a stirred tank to obtain an ionic liquid solution, wherein the stirred tank being heated to 50 C. Third, injecting the obtained ionic liquid solution and the poly (m-phenylene isophthalamide) solution separately into a tri-screw extruder, and mixing the solutions uniformly therein to obtain a uniformly mixed solution. Fourth, injecting he uniformly mixed solution into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 15 m and a monofilament diameter thereof is 5 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is a mixed solvent of water and DMAC, a mass fraction of water is 30%, a temperature of the coagulation bath is 50 C., and a gel time thereof is 80 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 80 C., wherein the coated-membrane is extracted with water to remove the solvents therein, in this way, the old poly (m-phenylene isophthalamide) membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, drying the porous-structured composite membrane with infrared rays at a drying temperature of 120 C., and heat-treating under an infrared lamp at 250 C. for 15 minutes to yield the aromatic polyamide composite separator.

Embodiment 9

[0068] First, dissolving 200 g of p-benzamide and polysulfone amide chopped fiber into 1000 g of DMAC solvent to obtain a polymer solution, wherein a mass percentage concentration of the polymer being 16.7%. Second, mixing 400 g of methyl tri-n-butyl phosphonium hydrochloride with 320 g of dichloromethane in a stirred tank to obtain an ionic liquid solution. Third, injecting the obtained ionic liquid solution and the p-benzamide and polysulfone amide chopped fiber polymer solution separately into a mixing tank, and stirring uniformly therein under negative pressure to obtain a uniform mixture. Fourth, injecting the uniform mixture into a coating tank. Fifth, immersing a fiberglass fabric into the mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 20 m and a monofilament diameter thereof is 6 m. Sixth, taking the coated fiberglass fabric out from the mixed solution, and then pressing-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is a mixed solvent of dichloromethane and DMAC, a mass fraction of dichloromethane is 10%, a temperature of the coagulation bath is 0 C. and a gel time thereof is 250 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 30 C., wherein the coated-membrane is extracted with dichloromethane to remove the solvents therein; in this way, the coated-membrane, i.e., the coated p-benzamide and polysulfone amide membrane, is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, hot air drying the porous-structured composite membrane at a drying temperature of 50 C., and heat-treating in a hot air oven at 300 C. for 8 minutes to yield the aromatic polyamide composite separator.

Embodiment 10

[0069] First, mixing 600 g of methyl tri-butyl ammonium hydrochloride with 2400 g of DMAC uniformly to form a first mixed solution. Second, adding 400 g of polysulfone amide spun into the first mixed solution above, heating to 80 C., and stirring uniformly under negative pressure to form a second mixed solution. Third, injecting the obtained second mixed solution into a coating tank. Fourth, immersing a fiberglass fabric into the second mixed solution in the coating tank to form a coated-fiberglass fabric, wherein a thickness of initial fiberglass fabric is 12 m and a monofilament diameter thereof is 4.5 m. Sixth, taking the coated fiberglass fabric out from the second mixed solution, and then press-rolling the coated fiberglass fabric to form a coated-membrane with uniform thickness. Seventh, putting the coated-membrane into a coagulation bath, wherein the coagulation bath is a mixed solvent of dichloromethane and DMAC, a mass fraction of dichloromethane is 20%, a temperature of the coagulation bath is 40 C. and a gel time thereof is 180 seconds. Eighth, pulling the coated-membrane into an extraction tank whose temperature is 30 C., wherein the coated-membrane is extracted with dichloromethane to remove the solvents therein, in this way, the coated-membrane, i.e., the coated polysulfone amide membrane is endowed with porous network structures, and turns to be a porous-structured composite membrane. Finally, hot air drying the porous-structured composite membrane at a drying temperature of 80 C., and heat-treating in a hot air oven at 280 C. for 20 minutes to yield the aromatic polyamide composite separator.

[0070] Test results on the performances of the composite separators prepared in embodiments 1, 4, 6, 8 and 10 are listed in table 2.

TABLE-US-00001 TABLE 1 aromatic polyamide Polyolefin- composite PET-coated coated separator aluminum aluminum prepared in oxide oxide Polyolefin embodiment 1 separator separator separator 120 C. TD 0.0% 0.0% 1.8% 6.0% MD 0.0% 0.6% 1.8% 3.0% 200 C. TD 0.0% 0.0% cracked shrunk MD 0.2% 0.7% 300 C. TD 0.3% cracked / / MD 0.3% / / 400 C. TD 0.5% / / / MD 0.5% / / / 500 C. TD 0.5% / / / MD 0.6% / / / 600 C. TD 0.8% / / / MD 1.2% / / /

TABLE-US-00002 TABLE 2 porosity of thermal shrinkage air aromatic tensile percentage thickness permeability polyamide strength (500 C., 1 h) (m) (s/100 CC) (%) (Mpa) TD (%) MD (%) Embodiment 1 23 136 61 130 0.3 0.5 Embodiment 4 22 120 65 153 0.2 0.6 Embodiment 6 25 160 58 160 0.2 0.3 Embodiment 8 20 87 70 125 0.4 0.7 Embodiment 10 20 83 68 128 0.3 0.6

[0071] While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.

INDUSTRIAL APPLICABILITY

[0072] The present disclosure provides an aromatic polyamide composite separator, which includes glass fiber and aromatic polyamide, a thermal shrinkage percentage of the composite separator is less than 3% at 300 C. Due to the good heat resistance of the glass fiber itself, heat resistance and stability of the prepared composite separator are greatly improved. Further, heat treatment makes the composite separator shrink at high temperature first, then shrink phenomenon would never occur later when used at high temperature. This greatly increases the safety of the lithium secondary battery. The composite separator of the present disclosure has excellent mechanical performance and heat resistance; hence, it is especially suitable to be used as secondary batteries, particularly, the separator of lithium ion power battery in electric vehicles.