Separator for digital battery and method for manufacturing same

Abstract

A separator for a digital battery and a method for making the same are provided. The separator of the digital battery comprises a base film (1) and a polymer coating layer (2) applied to at least one surface of the base film (1). The separator has a thickness of 3 to 10 μm and an ionic conductivity of 0.70 to 4.70 mS·cm. -1 This results in a battery separator that is thinner, safer, has lower resistance, better porosity and breathability, and better heat resistance, which solves the problems of conventional ultra-thin separators, such as unsafety, high resistance, low porosity, poor breathability, and poor heat resistance.

Description

[Technical Field]

[0001] The present invention relates to the technical field of separator production, and in particular to a separator for digital batteries and a method for making the same. [Background technology]

[0002] Lithium-ion batteries are composed of four key materials: a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte material. In the structure of a lithium battery, the separator is one of the important inner layer assemblies, primarily functioning to separate the positive and negative electrodes of the battery, preventing contact and short-circuiting between the two electrodes, while allowing lithium ions to pass through. Separator performance directly determines the battery's service life, safety in use, discharge rate, internal resistance, porosity, electrolyte uptake, and battery capacity, and thus plays a crucial role in improving the overall performance of the battery. The thickness of battery separators is one of the main factors affecting battery performance and has been a hot topic of investigation.

[0003] In the separator market, as digital products continue to be upgraded, there is a demand for even thinner separators, and the heat resistance and thermal shrinkage performance of these separators are also becoming more stringent. Summary of the Invention

[0004] The present invention aims to provide an ultra-thin separator for digital batteries that has good heat resistance and high ionic conductivity. In order to achieve the above object, the technical solution of the present invention is as follows.

[0005] A separator for a digital battery comprising a base film and a polymer coating applied to at least one surface of the base film, the separator having a thickness of 3 to 10 μm and an ionic conductivity of 0.70 to 4.70 mS·cm. -1 A separator for a digital battery, characterized in that The present invention has the following beneficial effects over the prior art.

[0006] The separator of the digital battery according to the present invention is thinner than commercial separators, occupies less space, has better heat resistance, and can maintain a lower thermal shrinkage rate at high temperatures, providing excellent safety and effectively preventing dangerous accidents such as short circuits inside the battery caused by the separator being punctured by high-temperature thermal shrinkage.

[0007] Another object of the present invention is to provide a method for manufacturing the separator of the digital battery. In order to achieve the above object, the technical solution of the present invention is a method for manufacturing a separator of a digital battery, comprising: Step S1: obtaining and preparing a finished slurry by mixing the organic and inorganic polymers, dispersants, and adhesives;

[0008] A method for producing a separator for a digital battery, comprising: a step S2 of obtaining a separator product by applying the finished slurry to the surface of a base film at a temperature of T1 and with an application tension speed difference of 0.1% to 10%, then rewinding at an unwinding temperature of T2 and with a winding / unwinding tension during application of 1 to 20 N, and finally dividing at a division winding / unwinding tension of 0.5 to 30 N and a contact pressure of 0.01 to 0.2 N, and obtaining a separator for a digital battery after the division is completed. The present invention has the following beneficial effects over the prior art.

[0009] The separator of the digital battery fabricated by the method of the present invention is thinner than the separators currently in use in the industry, and improves the porosity and breathability of the separator, while also contributing to reducing the battery resistance and the resistance of the separator itself, thereby effectively improving the ionic conductivity of the battery, as well as the battery capacity, rate performance, and service life of the battery. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a structural schematic diagram of the separator of the digital battery according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the separator of the digital battery according to the present invention will be provided. Example 1 As shown in FIG. 1, the separator of the digital battery according to the present invention comprises a base film 1 and a polymer coating layer 2 applied to one surface of the base film 1 . The method for producing the separator of the digital battery is as follows:

[0012] Step S1: Prepare a finished slurry having a particle size of 2 Nm by mixing an organic / inorganic polymer having a mass fraction of 99%, a dispersant having a mass fraction of 0.5%, and an adhesive having a mass fraction of 0.5% at a speed of 800 rpm for 1 hour.

[0013] and step S2, in which the finished slurry is applied to the surface of a base film at a temperature of T1 (50°C) and an application tension speed difference of 5% to obtain a separator product, which is then dried at 50°C, then unwound at an unwinding temperature of T2 (75°C) and a winding / unwinding tension of 10 N, and finally, divided at a division winding / unwinding tension of 0.5 N and a contact pressure of 0.01 N, and after the division is completed, a separator for a digital battery according to the present invention is obtained.

[0014] Test results show that the separator of the finished digital battery of the present invention has a thickness of 7 μm, an air permeability of 200 s / 100 cc, a porosity of 30% or less, a thermal shrinkage rate of 8% or more at 200°C, a separator body resistance of 30 Ω or more, a battery resistance of 100 Ω or more, and an ionic conductivity of 0.70 to 1.70 mS·cm -1 is.

[0015] Example 2 The separator of the digital battery shown in FIG. 1 is produced according to the production method of Example 1. However, the difference between them is that In step S1, a separator product is obtained by applying the finished product slurry to the surface of a PE base film; and In step S2, the winding tension for division is 10N.

[0016] Test results show that the separator of the finished digital battery of the present invention has a thickness of 7 μm, an air permeability of 200 s / 100 cc, a porosity of 30-60%, a heat shrinkage rate of 3% or less at 200°C, a separator body resistance of 0.1-30 Ω or more, a battery resistance of 10-100 Ω or more, and an ionic conductivity of 2.10-4.70 mS·cm -1 is.

[0017] Example 3 The fabrication was carried out in accordance with the fabrication method of Example 1. However, the difference between them is that the winding tension for division in step S2 is 30 N in this example, while it is 0.5 N in Example 1.

[0018] Test results show that the separator of the finished digital battery of the present invention has a thickness of 7 μm, an air permeability of 200 s / 100 cc, a porosity of the resulting coating film of 30% or less, a thermal shrinkage rate of 8% or more at 200°C, a resistance of the separator body of 30 Ω or more, a battery resistance of 100 Ω or more, and an ionic conductivity of 0.70 to 1.70 mS·cm. -1 is.

[0019] Example 4 It is produced according to the production method of Example 1. However, the differences are as follows: In S2, the difference in application pulling speed is 10% and the contact pressure is 0.1N.

[0020] Test results show that the separator has a thickness of 3 μm, an air permeability of 300 s / 100 cc, a porosity of 30% or less, a thermal shrinkage rate of 8% or more at 200°C, a separator body resistance of 30 Ω or more, a battery resistance of 100 Ω or more, and an ionic conductivity of 0.70 to 1.70 mS·cm.-1 is.

[0021] Example 5 The fabrication method is the same as that of Example 1. However, the differences are as follows: In step S1, a slurry having a particle size of 0.1 Nm is obtained by stirring for 0.01 h at a stirring speed of 700 rpm in a coater; and

[0022] In step S2, the coating is performed at a coating temperature of T1 (70°C), a coating tension speed difference of 0.1%, and a winding / unwinding tension of 20N, and the coating is unwound at T2 (70°C).

[0023] Test results show that the separator of the finished digital battery of the present invention has a thickness of 10 μm, an air permeability of 80 s / 100 cc, a porosity of 30% or less, a thermal shrinkage rate of the separator at 200°C of 8% or more, a resistance of the separator body of 30 Ω or more, a battery resistance of 100 Ω or more, and an ionic conductivity of 0.70 to 1.70 mS·cm -1 is.

[0024] Example 6 It is produced according to the production method of Example 1. However, the differences are as follows: In step S1, the organic and inorganic polymers, dispersants, and adhesives are mixed in a coating machine at a stirring speed of 1300 rpm for 7 hours to obtain a slurry having a particle size of 10 Nm; In step S2, the finished slurry is applied to the PE base film at an application temperature of T1 (60°C), an application tension difference of 6%, and an application winding / unwinding tension of 1N, and then unwinding is performed at an unwinding temperature of T2 (100°C), and further dividing is performed at a division winding / unwinding tension of 5N and a contact pressure of 0.2N.

[0025] Test results show that the separator of the finished digital battery of the present invention has a thickness of 6 μm, an air permeability of 20 s / 100 cc, a porosity of the resulting coating film of 30-60%, a thermal shrinkage rate of the separator of 3% or less at 200°C, a resistance of the separator body of 0.1-30 Ω, a battery resistance of 10-100 Ω, and an ionic conductivity of 2.10-4.70 mS·cm. -1 is.

[0026] Example 7 It is produced according to the production method of Example 1. However, the differences are as follows: In S2, the coating is performed with a coating tension speed difference of 4%, and the winding and unwinding tension of the division is set to 15N.

[0027] Test results show that the separator of the finished digital battery of the present invention has a thickness of 8 μm, an air permeability of 200 s / 100 cc, a porosity of the resulting coating film of 30-60 s / 100 cc, a thermal shrinkage rate of the separator of 3% or less at 200°C, a resistance of the separator body in the range of 0.1-30 Ω, a battery resistance of 10-100 Ω, and an ionic conductivity of 2.10-4.70 mS·cm. -1 is.

[0028] Table 1 shows the data results of the heat shrinkage performance test, the bulk resistance and impedance test, the porosity and the ionic conductivity of the separator of the digital battery according to the present invention fabricated under different split tension conditions.

[0029] Table 2 shows the data results of the heat shrinkage performance test, the body resistance and impedance test, the porosity and the ionic conductivity of the separator of the digital battery according to the present invention, which was prepared under different conditions of the difference in the application tension speed.

[0030] Table 3 shows the data results of the heat shrinkage performance test, the body resistance and impedance test, the porosity and the ionic conductivity of the separator of the digital battery according to the present invention under different separator thickness conditions.

[0031] Table 4 shows the data results of the heat shrinkage performance test, body resistance and impedance test, porosity and ionic conductivity of the separator of the digital battery under different ventilation conditions.

[0032] Table 1 JPEG2023530910000002.jpg89170

[0033] Table 2 JPEG2023530910000003.jpg95170

[0034] Table 3 JPEG2023530910000004.jpg83170

[0035] Table 4 JPEG2023530910000005.jpg89170

[0036] As shown in Table 1, the battery resistance and main body resistance tests, porosity, and ionic conductivity data for the separator of the digital battery according to the present invention show that the separator's performance differs when the split tension is different. When the split tension is 0.5 N and 30 N, the separator has a heat shrinkage rate of 8% or more, a battery resistance of 100 Ω or more, a separator main body resistance of 30 Ω or more, a porosity of 30% or less, and an ionic conductivity of 0.70 to 1.70 mS cm. -1 The separator for digital batteries has a thermal shrinkage rate of 3% or less when the dividing tension is 10N, a battery resistance of 10 to 100Ω, a body resistance of 0.1 to 30Ω, a porosity of 30 to 60%, and an ionic conductivity of 2.10 to 4.70mS·cm. -1As can be seen from the above, the separator for digital batteries performs well when the splitting tension is 0.5 to 30 N. Here, when the splitting tension is 10 N, the separator for digital batteries has better resistance safety, insulation performance, and heat resistance performance, lower impedance, and higher ionic conductivity, and can avoid safety risks such as direct contact between the positive and negative electrodes or short circuits inside the battery due to the occurrence of thermal shrinkage of the separator or film destruction at high temperatures, and has good prospects for development.

[0037] As can be seen from the data results of the battery resistance and main body resistance tests, porosity, and ionic conductivity of the separator of the digital battery according to the present invention, the performance of the separator of the digital battery differs when the application tension speed difference is different, as shown in Table 2. When the application tension speed difference is 0.1% and 10%, the separator of the digital battery has a thermal shrinkage rate of 8% or more, a battery resistance of 100 Ω or more, a separator main body resistance of 30 Ω or more, a porosity of 30% or less, and an ionic conductivity of 0.70 to 1.70 mS cm -1 The separator for digital batteries has a thermal shrinkage rate of 3% or less when the application tension speed difference is 5%, a battery resistance of 10 to 100 Ω, a separator body resistance of 0.1 to 30 Ω, a porosity of 30 to 60%, and an ionic conductivity of 2.10 to 4.70 mS cm. -1 As can be seen from the above, the separator for a digital battery exhibits good performance when the application tensile speed difference is 0.1% to 10%. Here, when the application tensile speed difference is 5%, the separator for a digital battery exhibits better resistance safety, insulation performance, and heat resistance performance, lower impedance, and higher ionic conductivity, and can avoid safety risks such as direct contact between the positive and negative electrodes or short circuits inside the battery due to thermal shrinkage of the separator or film destruction at high temperatures, and has good prospects for development.

[0038] As shown in Table 3, the performance of the separator for the digital battery according to the present invention, including the battery resistance and main body resistance tests, porosity, air permeability, and ionic conductivity, varies depending on the thickness of the separator. When the separator thickness is 3 μm or 10 μm, the separator for the digital battery has a heat shrinkage rate of 8% or more, a battery resistance of 100 Ω or more, a main body resistance of 30 Ω or more, a porosity of 30% or less, and an ionic conductivity of 0.70 to 1.70 mS·cm. -1 When the separator for a digital battery is applied with a thickness of 7 μm, the thermal shrinkage rate is 3% or less, the battery resistance is 10 to 100 Ω, the separator body resistance is 0.1 to 30 Ω, the porosity is 30 to 60%, and the ionic conductivity is 2.10 to 4.70 mS cm. -1 As can be seen from the above, the separator for digital batteries exhibits good performance when the separator thickness is 3 to 10 μm. Here, when the separator thickness is 7 μm, the separator for digital batteries exhibits better resistance safety, insulation performance, and heat resistance performance, lower impedance, and higher ionic conductivity, and can avoid safety risks such as direct contact between the positive and negative electrodes or short circuits inside the battery due to thermal shrinkage of the separator or film destruction at high temperatures, and has good prospects for development.

[0039] As can be seen from the data results of the battery resistance and main body resistance tests, porosity, and ionic conductivity of the separator of the digital battery according to the present invention, the performance of the separator of the digital battery differs when the air permeability value is different. When the air permeability value of the separator is 80s / 100cc and 300s / 100cc, the separator of the digital battery has a heat shrinkage rate of 8% or more, a battery resistance of 100Ω or more, a main body resistance of 30Ω or more, a porosity of 30% or less, and an ionic conductivity of 0.70 to 1.70 mS cm -1The separator for digital batteries has a heat shrinkage rate of 3% or less, a battery resistance of 10 to 100 Ω, a separator body resistance of 0.1 to 30 Ω, a porosity of 30 to 60%, and an ionic conductivity of 2.10 to 4.70 mS·cm when the separator has an air permeability of 200 s / 100 cc. -1 As can be seen from the above, the separator for a digital battery exhibits better performance when its air permeability is 80 to 300 s / 100 cc. Here, when the separator's air permeability is 200 s / 100 cc, the separator for a digital battery exhibits better resistance safety, insulation performance, and heat resistance performance, lower impedance, and higher ionic conductivity, and can avoid safety risks such as direct contact between the positive and negative electrodes or internal short circuits in the battery due to thermal shrinkage of the separator or film destruction at high temperatures, and has good prospects for development.

[0040] The above is only a preferred embodiment of the present invention, and those skilled in the art may further make some improvements and modifications without departing from the spirit of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention. [Explanation of symbols]

[0041] 1 base film 2 Polymer coating

Claims

1. A separator for a digital battery, comprising a base film and a polymer coating applied to at least one surface of the base film, The separator has a thickness of 3 to 10 μm and an ionic conductivity of 0.70 to 4.70 mS·cm －１ That is, A separator for a digital battery.

2. The separator has an air permeability of 80 to 300 s / 100 cc. The separator of the digital battery according to claim 1 .

3. The separator has a thickness of 6 to 8 μm and an ionic conductivity of 2.10 to 4.70 mS·cm －１ and the thermal shrinkage of the separator at 200°C is 3% or less. The separator of the digital battery according to claim 1 .

4. The separator has a body resistance of 0.1 to 30 Ω and a porosity of 30 to 60%. The separator of the digital battery according to claim 3 .

5. The mass fraction of each raw material in the polymer coating layer is 98% to 99.8% for organic / inorganic polymer, 0.1% to 1% for dispersant, and 0.1% to 1% for adhesive; The separator of the digital battery according to claim 1 .

6. A method for producing a separator for a digital battery according to any one of claims 1 to 5, Step S1: preparing a finished slurry by mixing the organic / inorganic polymer, dispersant, and adhesive; Step S2 includes applying the finished slurry to the surface of the base film at a temperature of T1 and an application tension speed difference of 0.1% to 10% to obtain a separator product, then unwinding at an unwinding temperature of T2 and a winding / unwinding tension during application of 1 to 20 N, and finally dividing at a division winding / unwinding tension of 0.5 to 30 N and a contact pressure of 0.01 to 0.2 N, and obtaining a separator for a digital battery after the division is completed. A method for producing a separator for a digital battery, comprising:

7. In step S1, the organic / inorganic polymer, dispersant, and adhesive are stirred at a speed of 700 to 1300 rpm for 0.01 to 7 hours to obtain a finished slurry having a particle size of 0.1 to 10 nm; In step S2, T1 is set to 50 to 70°C, and T2 is set to 70 to 100°C. The method for making a separator for a digital battery according to claim 6.

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