Preparation method of lightweight high-temperature-resistant high-ionic-conductivity lithium battery diaphragm

Abstract

The invention relates to the technical field of lithium batteries, and provides a preparation method of a lightweight high-temperature-resistant high-ionic-conductivity lithium battery diaphragm, which comprises the following steps: S1, slurry preparation: mixing aluminum oxide, water and a dispersant to obtain a mixed solution, adding an adhesive into the mixed solution, and mixing again to prepare slurry; s2, coating: coating a base membrane with the slurry, and drying to obtain a diaphragm; the aluminum oxide comprises small-particle-size porous aluminum oxide and large-particle-size porous aluminum oxide; d50 of the small-particle-size porous alumina is 0.1-0.3 [mu] m, D90 is 0.6-0.8 [mu] m, and the specific surface area is 10-20 m < 2 > / g; d50 of the large-particle-size porous alumina is 0.8-1.0 [mu] m, D90 is 2.0-3.0 [mu] m, and the specific surface area is 40-60 m < 2 > / g. According to the technical scheme, the problem of poor heat resistance of the lithium battery diaphragm in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium - ion batteries, and specifically, to a preparation method of a lightweight, high - temperature - resistant and high - ion - conductivity lithium - battery separator. Background Art

[0002] With the rapid progress of modern society and the remarkable improvement of living quality, people have put forward more stringent requirements for the performance of lithium batteries, especially placing high hopes on the fast - charging ability, cycle stability and safety reliability of lithium - ion batteries. By delving into the working principle of lithium batteries, it is not difficult to find that lithium ions (Li+) in the electrolyte need to shuttle back and forth between the positive and negative electrodes through the separator under the drive of the electrode potential to complete a complete charge - discharge cycle. As the medium for lithium - ion migration, the sufficiency of the electrolyte directly affects the wetting effect between the positive and negative electrodes and the separator. Once the amount of electrolyte is insufficient, it will seriously hinder the de - intercalation process of lithium ions from the positive electrode and their efficiency of passing through the separator to reach the negative electrode, ultimately leading to a decline in the overall performance of the battery.

[0003] Traditionally, the polyolefin separator used is prone to structural damage in a high - temperature environment, which may lead to a short - circuit phenomenon inside the battery. This is undoubtedly a major hidden danger for the safe use of lithium - ion batteries, and in severe cases, it may even cause battery explosion accidents. Therefore, improving the heat - resistant performance of the separator is of great significance for fully exerting the electrical performance potential of lithium - ion batteries and ensuring their safety during use. Summary of the Invention

[0004] The present invention provides a preparation method of a lightweight, high - temperature - resistant and high - ion - conductivity lithium - battery separator, which solves the problem of poor heat resistance of lithium - battery separators in related technologies.

[0005] The technical solution of the present invention is as follows: The present invention provides a preparation method of a lightweight, high - temperature - resistant and high - ion - conductivity lithium - battery separator, comprising the following steps: S1. Slurry preparation: Mix alumina, water and a dispersant to obtain a mixed solution, and then add an adhesive to the mixed solution and mix again to form a slurry; S2. Coating: Coat the slurry on a base film and dry it to obtain a separator; The alumina includes small - particle - size porous alumina and large - particle - size porous alumina; The D50 of the small - particle - size porous alumina is 0.1 - 0.3 μm, the D90 is 0.6 - 0.8 μm, and the specific surface area is 10 - 20 m 2 / g; the D50 of the large - particle - size porous alumina is 0.8 - 1.0 μm, the D90 is 2.0 - 3.0 μm, and the specific surface area is 40 - 60 m 2 / g.

[0006] As a further technical solution, the mass ratio of the small-particle-size porous alumina to the large-particle-size porous alumina is 1:1 to 6.

[0007] As a further technical solution, the small-particle-size porous alumina is 3-aminopropanesulfonic acid composite small-particle-size porous alumina; the large-particle-size porous alumina is 3-aminopropanesulfonic acid composite large-particle-size porous alumina; the raw materials of the 3-aminopropanesulfonic acid composite small-particle-size porous alumina include 3-aminopropanesulfonic acid and small-particle-size porous alumina; the raw materials of the 3-aminopropanesulfonic acid composite large-particle-size porous alumina include 3-aminopropanesulfonic acid and large-particle-size porous alumina.

[0008] In the present invention, by compounding 3-aminopropanesulfonic acid with small-particle-size porous alumina and large-particle-size porous alumina, the dispersibility of alumina is improved, a more favorable migration environment is provided for lithium ions, and the lithium ion mobility of the separator is further improved.

[0009] As a further technical solution, in the 3-aminopropanesulfonic acid composite small-particle-size porous alumina, the mass of 3-aminopropanesulfonic acid is 2% to 5% of the mass of the small-particle-size porous alumina; in the 3-aminopropanesulfonic acid composite large-particle-size porous alumina, the mass of 3-aminopropanesulfonic acid is 2% to 5% of the mass of the large-particle-size porous alumina.

[0010] In the present invention, by respectively limiting the mass of 3-aminopropanesulfonic acid to be 2% to 5% of the mass of the small-particle-size porous alumina or the large-particle-size porous alumina, the lithium ion mobility of the separator is further improved.

[0011] As a further technical solution, the preparation method of the 3-aminopropanesulfonic acid composite small-particle-size porous alumina includes the following steps: adding 3-aminopropanesulfonic acid and small-particle-size porous alumina into a first solvent for mixing, and obtaining the 3-aminopropanesulfonic acid composite small-particle-size porous alumina after drying; the preparation method of the 3-aminopropanesulfonic acid composite large-particle-size porous alumina includes the following steps: adding 3-aminopropanesulfonic acid and large-particle-size porous alumina into a second solvent for mixing, and obtaining the 3-aminopropanesulfonic acid composite large-particle-size porous alumina after drying.

[0012] As a further technical solution, the first solvent and the second solvent each independently include ethanol.

[0013] As a further technical solution, the temperature of the mixing is 35 °C and the time of the mixing is 1 h.

[0014] As a further technical solution, the raw materials of the slurry include the following components in parts by weight: 5-10 parts of small-particle-size porous alumina, 10-30 parts of large-particle-size porous alumina, 1-10 parts of adhesive, 0.1-1 part of dispersant, and 40-90 parts of water.

[0015] As a further technical solution, the adhesive is an acrylate copolymer solution.

[0016] As a further technical solution, the concentration of the acrylate copolymer solution is 20 wt%.

[0017] As a further technical solution, the dispersant is ammonium polyacrylate.

[0018] As a further technical solution, the mixing and re-mixing are carried out by mechanical stirring; the rotation speed of the mechanical stirring is 1000-3000 r / min, and the revolution speed is 30-60 r / min; the mixing time and the re-mixing time are each independently 30-60 min.

[0019] As a further technical solution, the coating speed is 10-30 m / min; the thickness of the coating after coating is 2-5 μm.

[0020] As a further technical solution, the base film is a PE film.

[0021] As a further technical solution, the slurry is coated on one side of the base film.

[0022] As a further technical solution, the drying temperature is 30-60 °C, and the drying time is 1-3 min.

[0023] The working principle and beneficial effects of the present invention are as follows: In the present invention, by adding two kinds of porous alumina with different particle sizes to the separator for compounding, this structure helps to improve the thermal stability of the separator, reduce heat shrinkage and deformation in a high-temperature environment. This separator can not only effectively prevent the problem of internal short circuit of the battery caused by high temperature, but also ensure that the battery can still operate stably under harsh conditions, greatly improving the overall safety of the lithium battery.

[0024] Porous alumina particles with different particle sizes can also form a more complex pore structure, which helps to improve the absorption rate and liquid retention capacity of the electrolyte, thereby shortening the transmission path of lithium ions (Li+) in the separator, enhancing the ionic conductivity of the separator, reducing the internal resistance of the lithium-ion battery, and enabling the battery to release a higher power density; larger particles can provide a support framework, while smaller particles fill in the gaps between the frameworks to form a denser and more uniform coating, thus improving the penetration and distribution of the electrolyte. Compared with conventional alumina, due to the rich pore structure of porous alumina, the surface density increment of its coating is lower at the same thickness. Detailed implementation manners

[0025] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0026] In the following embodiments and comparative examples: Porous alumina powder was purchased from Suzhou Jinyi New Material Technology Co., Ltd. Ammonium polyacrylate, MW: 1 million; acrylate copolymer, model: SF-1.

[0027] Example 1 A method for preparing a lightweight high-temperature resistant and high-ion conductivity lithium battery separator includes the following steps: S1. Slurry preparation: First, 0.5 part of ammonium polyacrylate, 40 parts of water, 10 parts of small-particle-size porous alumina (D50 = 0.292 μm, D90 = 0.657 μm, specific surface area: 16.62 m 2 / g), and 10 parts of large-particle-size porous alumina (D50 = 0.922 μm, D90 = 2.657 μm, specific surface area: 51.36 m 2 / g) were blended and stirred in a double planetary mixer for 60 min to obtain a mixed solution. The self-rotation speed of the stirring was 3000 r / min, and the revolution speed was 60 r / min; then 5 parts of acrylate copolymer solution were added to the mixed solution, and the blending and stirring were continued at a self-rotation speed of 3000 r / min and a revolution speed of 50 r / min for 60 min to prepare a slurry. S2. Coating: The PE film was placed on a coater, and the slurry was coated on one side of the PE film at a coating speed of 30 m / min and a coating thickness of 2 μm, and then it was put into a drying oven and dried at 60 °C for 1 min to obtain a separator.

[0028] Example 2 A preparation method of a lightweight high-temperature resistant and high ionic conductivity lithium battery separator, comprising the following steps: S1. Slurry preparation: First, 0.5 parts of ammonium polyacrylate, 64.5 parts of water, 10 parts of small-particle-size porous alumina (D50 = 0.269 μm, D90 = 0.698 μm, specific surface area: 16.25 m 2 / g), and 20 parts of large-particle-size porous alumina (D50 = 0.875 μm, D90 = 2.142 μm, specific surface area: 50.32 m 2 / g) are blended and stirred in a double planetary mixer for 40 min to obtain a mixed solution, with the self-rotation speed of stirring being 2000 r / min and the revolution speed being 40 r / min; then 10 parts of acrylate copolymer solution are added to the mixed solution, and blending and stirring are continued at a self-rotation speed of 2000 r / min and a revolution speed of 40 r / min for 50 min to prepare a slurry; S2. Coating: Place the PE film on a coater, coat the slurry on one side of the PE film, with the coating speed being 20 m / min and the coating thickness being 3 μm, and put it into a drying oven to dry at 40 °C for 2 min to obtain a separator.

[0029] Example 3 A preparation method of a lightweight high-temperature resistant and high ionic conductivity lithium battery separator, comprising the following steps: S1. Slurry preparation: First, 0.5 parts of ammonium polyacrylate, 79.5 parts of water, 5 parts of small-particle-size porous alumina (D50 = 0.201 μm, D90 = 0.715 μm, specific surface area: 17.66 m 2 / g), and 10 parts of large-particle-size porous alumina (D50 = 0.965 μm, D90 = 2.656 μm, specific surface area: 55.63 m 2 / g) are blended and stirred in a double planetary mixer for 30 min to obtain a mixed solution, with the self-rotation speed of stirring being 1000 r / min and the revolution speed being 30 r / min; then 5 parts of acrylate copolymer solution are added to the mixed solution, and blending and stirring are continued at a self-rotation speed of 1000 r / min and a revolution speed of 30 r / min for 30 min to prepare a slurry; S2. Coating: Place the PE film on a coater, coat the slurry on one side of the PE film, with the coating speed being 10 m / min and the coating thickness being 3 μm, and put it into a drying oven to dry at 30 °C for 3 min to obtain a separator.

[0030] Example 4 A preparation method of a lightweight high-temperature resistant and high ionic conductivity lithium battery separator, comprising the following steps: S1. Slurry preparation: First, 0.1 part of ammonium polyacrylate, 40 parts of water, 5 parts of small-particle-size porous alumina (D50 = 0.201 μm, D90 = 0.715 μm, specific surface area: 17.66 m 2 / g), and 20 parts of large-particle-size porous alumina (D50 = 0.965 μm, D90 = 2.656 μm, specific surface area: 55.63 m 2 / g) are blended and stirred in a double planetary mixer for 50 min to obtain a mixed solution. The self-rotation speed of stirring is 1000 r / min, and the revolution speed is 50 r / min. Then, 5 parts of acrylate copolymer solution are added to the mixed solution, and the blending and stirring continue at a self-rotation speed of 1000 r / min and a revolution speed of 50 r / min for 50 min to prepare the slurry; S2. Coating: Place the PE film on the coater, coat the slurry on one side of the PE film at a coating speed of 10 m / min and a coating thickness of 4 μm, and put it into the drying oven to dry at 50 °C for 1 min to obtain the separator.

[0031] Example 5 A preparation method of a lightweight high-temperature resistant and high ionic conductivity lithium battery separator, comprising the following steps: S1. Slurry preparation: First, 1 part of ammonium polyacrylate, 90 parts of water, 5 parts of small-particle-size porous alumina (D50 = 0.269 μm, D90 = 0.698 μm, specific surface area: 16.25 m 2 / g), and 30 parts of large-particle-size porous alumina (D50 = 0.875 μm, D90 = 2.142 μm, specific surface area: 50.32 m 2 / g) are blended and stirred in a double planetary mixer for 50 min to obtain a mixed solution. The self-rotation speed of stirring is 1000 r / min, and the revolution speed is 50 r / min. Then, 5 parts of acrylate copolymer solution are added to the mixed solution, and the blending and stirring continue at a self-rotation speed of 1000 r / min and a revolution speed of 50 r / min for 50 min to prepare the slurry; S2. Coating: Place the PE film on the coater, coat the slurry on one side of the PE film at a coating speed of 10 m / min and a coating thickness of 5 μm, and put it into the drying oven to dry at 50 °C for 1 min to obtain the separator.

[0032] Example 6 This example is different from Example 4 only in that the small-particle-size porous alumina is 3-aminopropanesulfonic acid composite small-particle-size porous alumina; the large-particle-size porous alumina is 3-aminopropanesulfonic acid composite large-particle-size porous alumina; Preparation method of 3-aminopropanesulfonic acid composite small-sized porous alumina, comprising the following steps: adding 5 parts of small-sized porous alumina (D50 = 0.201 μm, D90 = 0.715 μm, specific surface area: 17.66 m 2 / g) and 0.05 part of 3-aminopropanesulfonic acid into 15 parts of ethanol, heating to 35 °C and then mixing and stirring for 1 h, and drying to obtain 3-aminopropanesulfonic acid composite small-sized porous alumina; Preparation method of 3-aminopropanesulfonic acid composite large-sized porous alumina, comprising the following steps: adding 20 parts of large-sized porous alumina (D50 = 0.965 μm, D90 = 2.656 μm, specific surface area: 55.63 m 2 / g) and 0.2 part of 3-aminopropanesulfonic acid into 60 parts of ethanol, heating to 35 °C and then mixing and stirring for 1 h, and drying to obtain 3-aminopropanesulfonic acid composite large-sized porous alumina.

[0033] Example 7 Compared with Example 6, the difference in this example is only that the preparation method of 3-aminopropanesulfonic acid composite small-sized porous alumina comprises the following steps: adding 5 parts of small-sized porous alumina (D50 = 0.201 μm, D90 = 0.715 μm, specific surface area: 17.66 m 2 / g) and 0.5 part of 3-aminopropanesulfonic acid into 15 parts of ethanol, heating to 35 °C and then mixing and stirring for 1 h, and drying to obtain 3-aminopropanesulfonic acid composite small-sized porous alumina; The preparation method of 3-aminopropanesulfonic acid composite large-sized porous alumina comprises the following steps: adding 20 parts of large-sized porous alumina (D50 = 0.965 μm, D90 = 2.656 μm, specific surface area: 55.63 m 2 / g) and 2 parts of 3-aminopropanesulfonic acid into 60 parts of ethanol, heating to 35 °C and then mixing and stirring for 1 h, and drying to obtain 3-aminopropanesulfonic acid composite large-sized porous alumina.

[0034] Example 8 Compared with Example 6, the difference in this example is only that the preparation method of 3-aminopropanesulfonic acid composite small-sized porous alumina comprises the following steps: adding 5 parts of small-sized porous alumina (D50 = 0.201 μm, D90 = 0.715 μm, specific surface area: 17.66 m 2 / g) and 0.1 part of 3-aminopropanesulfonic acid into 15 parts of ethanol, heating to 35 °C and then mixing and stirring for 1 h, and drying to obtain 3-aminopropanesulfonic acid composite small-sized porous alumina; Preparation method of 3 - aminopropanesulfonic acid - composite large - particle - size porous alumina, comprising the following steps: adding 20 parts of large - particle - size porous alumina (D50 = 0.965μm, D90 = 2.656μm, specific surface area: 55.63m 2 / g) and 0.4 part of 3 - aminopropanesulfonic acid into 60 parts of ethanol, heating to 35°C and then mixing and stirring for 1 h, and drying to obtain 3 - aminopropanesulfonic acid - composite large - particle - size porous alumina.

[0035] Example 9 This example is different from Example 6 only in that the preparation method of 3 - aminopropanesulfonic acid - composite small - particle - size porous alumina comprises the following steps: adding 5 parts of small - particle - size porous alumina (D50 = 0.201μm, D90 = 0.715μm, specific surface area: 17.66m 2 / g) and 0.25 part of 3 - aminopropanesulfonic acid into 15 parts of ethanol, heating to 35°C and then mixing and stirring for 1 h, and drying to obtain 3 - aminopropanesulfonic acid - composite small - particle - size porous alumina; Preparation method of 3 - aminopropanesulfonic acid - composite large - particle - size porous alumina, comprising the following steps: adding 20 parts of large - particle - size porous alumina (D50 = 0.965μm, D90 = 2.656μm, specific surface area: 55.63m 2 / g) and 1 part of 3 - aminopropanesulfonic acid into 60 parts of ethanol, heating to 35°C and then mixing and stirring for 1 h, and drying to obtain 3 - aminopropanesulfonic acid - composite large - particle - size porous alumina.

[0036] Comparative Example 1 This comparative example is different from Example 1 only in that the large - particle - size porous alumina (D50 = 0.922μm, D90 = 2.657μm, specific surface area: 51.36m 2 / g) is replaced with an equal amount of small - particle - size porous alumina (D50 = 0.292μm, D90 = 0.657μm, specific surface area: 16.62m 2 / g).

[0037] Comparative Example 2 This comparative example is different from Example 1 only in that the small - particle - size porous alumina (D50 = 0.292μm, D90 = 0.657μm, specific surface area: 16.62m 2 / g) is replaced with an equal amount of large - particle - size porous alumina (D50 = 0.922μm, D90 = 2.657μm, specific surface area: 51.36m 2 / g).

[0038] Comparative Example 3 This comparative example is different from Example 1 only in that the large-particle-size porous alumina (D50 = 0.922 μm, D90 = 2.657 μm, specific surface area: 51.36 m 2 / g) is replaced with an equal amount of large-particle-size porous alumina (D50 = 0.602 μm, D90 = 1.598 μm, specific surface area: 43.41 m 2 / g).

[0039] Comparative Example 4 This comparative example is different from Example 1 only in that the large-particle-size porous alumina (D50 = 0.922 μm, D90 = 2.657 μm, specific surface area: 51.36 m 2 / g) is replaced with an equal amount of large-particle-size porous alumina (D50 = 1.042 μm, D90 = 2.408 μm, specific surface area: 55.38 m 2 / g).

[0040] Comparative Example 5 This comparative example is different from Example 1 only in that the small-particle-size porous alumina (D50 = 0.292 μm, D90 = 0.657 μm, specific surface area: 16.62 m 2 / g) is replaced with an equal amount of small-particle-size porous alumina (D50 = 0.392 μm, D90 = 0.987 μm, specific surface area: 13.54 m 2 / g).

[0041] Comparative Example 6 This comparative example is different from Example 1 only in that the small-particle-size porous alumina (D50 = 0.292 μm, D90 = 0.657 μm, specific surface area: 16.62 m 2 / g) is replaced with an equal amount of small-particle-size porous alumina (D50 = 0.085 μm, D90 = 0.587 μm, specific surface area: 20.59 m 2 / g).

[0042] Comparative Example 7 This comparative example is different from Example 1 only in that 10 parts of small-particle-size porous alumina (D50 = 0.292 μm, D90 = 0.657 μm, specific surface area: 16.62 m 2 / g), 10 parts of large-particle-size porous alumina (D50 = 0.922 μm, D90 = 2.657 μm, specific surface area: 51.36 m 2 / g) are replaced with 20 parts of alumina (D50 = 0.742 μm, D90 = 1.556 μm, specific surface area: 7.62 m 2 / g).

[0043] Experimental Example 1 The diaphragms prepared in Examples 1 to 5 and Comparative Examples 1 to 7 were tested for shrinkage rate at 150 °C for 1 h according to the method in GB / T 36363-2018 "Polyolefin Diaphragms for Lithium-Ion Batteries". The test results are shown in Table 1.

[0044] Table 1 Test Results of Heat Resistance Performance of Diaphragms

[0045] Compared with Comparative Examples 1 to 7, the diaphragms prepared in Examples 1 to 5 had a lower shrinkage rate under the conditions of 150 °C for 1 h, indicating that the use of small particle size porous alumina (D50 = 0.1 - 0.3 μm, D90 = 0.6 - 0.8 μm, specific surface area of 10 - 20 m 2 / g) and large particle size porous alumina (D50 = 0.8 - 1.0 μm, D90 = 2.0 - 3.0 μm, specific surface area of 40 - 60 m 2 / g) for compounding can improve the heat resistance of the diaphragm.

[0046] Experimental Example 2 The diaphragms prepared in Examples 1 to 9 were tested for ionic conductivity according to the method in GB / T 36363-2018 "Polyolefin Diaphragms for Lithium-Ion Batteries". The test results are shown in Table 2.

[0047] Table 2 Test Results of Ionic Conductivity

[0048] As can be seen from Table 2, the ionic conductivity of the diaphragms prepared in Examples 6 to 9 was higher than that in Examples 1 to 5, indicating that the use of 3-aminopropanesulfonic acid for compounding with alumina of different particle sizes can improve the lithium ion mobility of the diaphragm, and when the mass of 3-aminopropanesulfonic acid is 2% - 5% of the sum of the masses of small particle size porous alumina and large particle size porous alumina, the lithium ion mobility of the diaphragm can be further improved.

[0049] Experimental Example 3 The diaphragms prepared in Examples 1 to 5 and Comparative Examples 1 to 7 were tested for air permeability according to the method in GB / T 36363-2018 "Polyolefin Diaphragms for Lithium-Ion Batteries"; the liquid absorption rate and liquid retention rate were tested according to the method in QB / T 2303.11-2008 "Battery Separating Paper Part 11: Determination of Liquid Absorption Rate"; surface density = diaphragm mass / diaphragm surface area; the test results are shown in Table 3.

[0050] Table 3 Test Results of Diaphragm Performance

[0051] As can be seen from Table 3, the liquid absorption rate and liquid retention rate of the diaphragms prepared in Examples 1 to 5 are higher than those in Comparative Examples 1 to 7, indicating that the small particle size porous alumina (D50 = 0.1 - 0.3 μm, D90 = 0.6 - 0.8 μm, specific surface area is 10 - 20 m 2 / g) and the large particle size porous alumina (D50 = 0.8 - 1.0 μm, D90 = 2.0 - 3.0 μm, specific surface area is 40 - 60 m 2 / g) are compounded, which can also improve the absorption rate and liquid retention rate of the diaphragm for the electrolyte and improve the permeability of the electrolyte.

[0052] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator, characterized in that: The following steps are involved: S1. Slurry preparation: mixing alumina, water and a dispersant to obtain a mixed solution, adding an adhesive to the mixed solution and mixing again to obtain a slurry; S2, coating: coating the slurry on the base film, and drying to obtain a diaphragm; The alumina comprises small-particle porous alumina and large-particle porous alumina; the small-particle porous alumina has a D50 of 0.1-0.3 μm, a D90 of 0.6-0.8 μm, and a specific surface area of ​​10-20 m 2 / g; the large-particle porous alumina has a D50 of 0.8-1.0 μm, a D90 of 2.0-3.0 μm, and a specific surface area of ​​40-60 m 2 / g.

2. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 1, characterized in that: The mass ratio of the small-particle porous alumina to the large-particle porous alumina is 1:1-6.

3. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 1, characterized in that: The small-particle porous alumina is 3-aminopropane sulfonic acid composite small-particle porous alumina; the large-particle porous alumina is 3-aminopropane sulfonic acid composite large-particle porous alumina; the raw materials of the 3-aminopropane sulfonic acid composite small-particle porous alumina include 3-aminopropane sulfonic acid and small-particle porous alumina; the raw materials of the 3-aminopropane sulfonic acid composite large-particle porous alumina include 3-aminopropane sulfonic acid and large-particle porous alumina.

4. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 3, characterized in that: In the 3-aminopropane sulfonic acid composite small-particle porous alumina, the mass of 3-aminopropane sulfonic acid is 2% to 5% of the mass of the small-particle porous alumina; in the 3-aminopropane sulfonic acid composite large-particle porous alumina, the mass of 3-aminopropane sulfonic acid is 2% to 5% of the mass of the large-particle porous alumina.

5. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 3, characterized in that: The preparation method of the 3-aminopropane sulfonic acid composite small-particle porous alumina comprises the following steps: adding 3-aminopropane sulfonic acid and small-particle porous alumina into a first solvent for mixing, and drying to obtain the 3-aminopropane sulfonic acid composite small-particle porous alumina; the preparation method of the 3-aminopropane sulfonic acid composite large-particle porous alumina comprises the following steps: adding 3-aminopropane sulfonic acid and large-particle porous alumina into a second solvent for mixing, and drying to obtain the 3-aminopropane sulfonic acid composite large-particle porous alumina.

6. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 1, characterized in that: The raw materials of the slurry include the following components in parts by weight: 15-40 parts of aluminum oxide, 1-10 parts of adhesive, 0.1-1 parts of dispersant, and 40-90 parts of water.

7. The method for preparing a lightweight, high temperature resistant, high ionic conductivity lithium battery separator according to claim 1, characterized in that: The mixing and remixing are performed by mechanical stirring; the rotation speed of the mechanical stirring is 1000-3000 r / min, and the revolution speed is 30-60 r / min; the time of the mixing and remixing is independently 30-60 min.

8. The method for preparing a lightweight, high temperature resistant, high ion conductivity lithium battery separator according to claim 1, characterized in that: The slurry is coated on one side of the base film.

9. The method for preparing a lightweight, high temperature resistant, high ion conductivity lithium battery separator according to claim 1, characterized in that: The coating speed is 10-30 m / min; the thickness of the coating after coating is 2-5 μm.

10. The method for preparing a lightweight, high temperature resistant, high ion conductivity lithium battery separator according to claim 1, characterized in that: The drying temperature is 30-60° C., and the drying time is 1-3 min.

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