Lithium battery diaphragm composite coating based on glass fibers and preparation method thereof

Abstract

The invention discloses a lithium battery diaphragm composite coating based on glass fiber and a preparation method thereof, the lithium battery diaphragm composite coating is prepared by compounding glass fiber and high-component fiber on a common lithium battery diaphragm, the gram weight is 8-16g, the thickness is 10-80mu m, and the porosity is gt; 70%. The glass fibers and the high-component fibers are introduced to a common lithium battery diaphragm, so that the interface reaction between a lithium metal negative electrode and an electrolyte can be effectively inhibited, the generation of an unstable SEI membrane is inhibited, the generation of lithium dendrites in the circulation process is prevented, and the relatively high porosity provides an enough buffer space for the volume expansion of the lithium metal negative electrode, so that the lithium battery diaphragm has the advantages of high stability and high reliability. The cycle performance and the service life of the high-energy-density lithium battery can be improved; the glass fibers and the high-component fibers are compounded, so that the pore size distribution can be effectively controlled, a gain effect on the effects is achieved, and the strength of the composite coating and the binding force of the composite coating and a common lithium battery diaphragm are also improved; and the preparation process is efficient and beneficial to large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery separators, and in particular relates to a glass fiber-based lithium battery separator composite coating and a preparation method thereof. Background Art

[0002] Lithium metal anode is the key research direction of high energy density lithium battery. At present, there are the following main problems: high reaction activity, which easily leads to the formation of unstable SEI film with electrolyte; easy volume expansion during the cycle; easy to produce lithium dendrites. As a result, the cycle life of batteries made of lithium metal is poor, which limits its actual commercial application.

[0003] The current solutions include improving the composition of the electrolyte, using solid electrolytes, designing three-dimensional current collectors, and performing surface modification on the lithium negative electrode. However, these solutions cannot completely solve the above problems.

[0004] Studies have shown that SiO 2 Oxide components such as glass fiber have a good effect in inhibiting the formation of unstable SEI film and lithium dendrites, but due to the characteristics of the fiber itself and the molding process, it is very challenging to prepare a separate and ultra-thin glass fiber film for use in lithium metal negative electrodes. Summary of the invention

[0005] In order to solve the technical problems existing in the prior art, the purpose of the present invention is to provide a glass fiber-based lithium battery separator composite coating and a preparation method thereof.

[0006] In order to achieve the above purpose and the above technical effect, the technical solution adopted by the present invention is:

[0007] A glass fiber-based lithium battery separator composite coating is prepared by compounding glass fiber and high-component fiber on an ordinary lithium battery separator, with a gram weight of 8 to 16 g, a thickness of 10 to 80 μm, and a porosity of >70%.

[0008] Furthermore, the high-component fiber is one or a combination of PP fiber, PE fiber, and PET fiber.

[0009] Furthermore, the mass ratio of the glass fiber to the high-component fiber is 70-90:10-30.

[0010] The present invention also discloses a method for preparing a glass fiber-based lithium battery separator composite coating, comprising the following steps:

[0011] Step 1: Weigh 70-90% of glass fiber and 10-30% of high-component fiber by mass percentage and set aside;

[0012] Step 2: Add the glass fiber and high-component fiber obtained in step 1 into a pulper, mix them evenly, then add an organic solvent, stir and disperse them at a high speed in the pulper to obtain mixed pulp fiber;

[0013] Step 3: Place the common lithium battery separator on the filtration bottom layer, and soak the common lithium battery separator with an organic solvent to make the common lithium battery separator and the filtration bottom layer completely fit together;

[0014] Step 4: pour the mixed slurry fiber obtained in step 2 onto a common lithium battery separator for suction filtration and molding;

[0015] Step 5: Dry the lithium battery separator composite coating obtained by filtration in step 4 to remove the organic solvent.

[0016] Furthermore, in step 2, the dispersion time is 1 to 10 minutes.

[0017] Furthermore, in step 2 and step 3, the organic solvent is one or a combination of anhydrous ethanol, N-methylpyrrolidone, and isopropanol.

[0018] Furthermore, in step 4, the filtration time is 2 to 8 minutes, and the filtration vacuum pressure is -50 to -70 kPa.

[0019] Furthermore, in step five, the drying temperature is 70-120° C., and the drying time is 10-20 min.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The invention discloses a glass fiber-based lithium battery separator composite coating and a preparation method thereof. The lithium battery separator composite coating is prepared by compounding glass fiber and high-component fiber on an ordinary lithium battery separator, has a gram weight of 8 to 16 g, a thickness of 10 to 80 μm, and a porosity of >70%. The coating can effectively inhibit the interface reaction between a lithium metal negative electrode and an electrolyte, inhibit the formation of an unstable SEI film, and prevent the formation of lithium dendrites during the cycle. At the same time, the higher porosity provides sufficient buffer space for the volume expansion of the lithium metal negative electrode, which is beneficial to improving the cycle performance and life of a high-energy density lithium battery. The glass fiber and the high-component fiber are compounded, and the pore size distribution can be effectively controlled by adding the high-component fiber, so as to achieve a gain effect on the above effects, and also improve the strength of the composite coating and the bonding force with the ordinary lithium battery separator. The preparation process is efficient and beneficial to large-scale production. DETAILED DESCRIPTION

[0022] The present invention is described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0023] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0024] The invention discloses a glass fiber-based lithium battery separator composite coating, which is prepared by composite glass fiber and high-component fiber on a common lithium battery separator, has a gram weight of 8 to 16 g, a thickness of 10 to 80 μm, and a porosity of >70%.

[0025] The present invention also discloses a method for preparing a glass fiber-based lithium battery separator composite coating, comprising the following steps:

[0026] Step 1: Weigh 70-90% of glass fiber and 10-30% of high-component fiber by mass percentage and set aside;

[0027] Step 2: Add the glass fiber and high-component fiber obtained in step 1 into a pulper, mix them evenly, then add an organic solvent, stir and disperse them at high speed in the pulper for 1 to 10 minutes to obtain mixed pulp fiber;

[0028] Step 3: Place the common lithium battery separator on the filtration bottom layer, and soak the common lithium battery separator with an organic solvent to make the common lithium battery separator and the filtration bottom layer completely fit together;

[0029] Step 4: pour the mixed slurry fiber obtained in step 2 onto a common lithium battery separator for suction filtration and forming. Shake the mixed slurry fiber evenly during pouring to make the mixed slurry fiber evenly dispersed. The suction filtration time is 2 to 8 minutes, and the suction filtration vacuum pressure is -50 to -70 kPa;

[0030] Step 5: Dry the filtered lithium battery separator composite coating obtained in step 4 to remove the organic solvent. In order to ensure that the glass fiber and the high-component fiber are bonded together, the drying temperature is controlled at 70-120° C. and the drying time is controlled at 10-20 minutes.

[0031] Based on the melting point characteristics of high-component fibers, selecting an appropriate drying temperature can prevent the fibers from melting or deforming during drying, and can also ensure that the solvent in the composite coating is completely dried, thereby improving the bonding effect between the fiber and the diaphragm. If the drying temperature is lowered and the processing time is shortened, the solvent in the composite coating may not be completely removed, which will significantly reduce the bonding strength between the fiber and the diaphragm. If the drying temperature is too high or the processing time is too long, the fiber will melt, deform or degrade, which will also reduce the bonding quality.

[0032] In step 1, the high-component fiber is one or a combination of PP fiber, PE fiber, and PET fiber.

[0033] In step 2 and step 3, the organic solvent is one or a combination of anhydrous ethanol, N-methylpyrrolidone, and isopropanol.

[0034] Example 1

[0035] A glass fiber-based lithium battery separator composite coating is prepared by compounding glass fiber and PP fiber on an ordinary lithium battery separator, with a gram weight of 10 g, a thickness of 35 μm, and a porosity of 90% for the composite coating.

[0036] A method for preparing a glass fiber-based lithium battery separator composite coating comprises the following steps:

[0037] Step 1: Weigh 80% of glass fiber and 20% of PP fiber by mass and set aside;

[0038] Step 2: Add the glass fiber and PP fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0039] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0040] Step 4: pour the mixed slurry fiber obtained in step 2 onto a common lithium battery separator for suction filtration and forming. Shake well while pouring to make the mixed slurry fiber evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50kPa.

[0041] Step 5: Filter the formed composite coating, and then dry it at 85°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the PP fiber are bonded together, and finally the desired glass fiber-based lithium battery separator composite coating is obtained.

[0042] Example 2

[0043] A glass fiber-based lithium battery separator composite coating is prepared by compounding glass fiber and PET fiber on an ordinary lithium battery separator, with a gram weight of 14 g, a thickness of 50 μm, and a porosity of 90% for the composite coating.

[0044] A method for preparing a glass fiber-based lithium battery separator composite coating comprises the following steps:

[0045] Step 1: Weigh 90% of glass fiber and 10% of PET fiber by mass and set aside;

[0046] Step 2: Add the glass fiber and PET fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0047] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0048] Step 4: Pour the mixed slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake the mixed slurry fibers evenly during the pouring process to make the mixed slurry fibers evenly dispersed. The suction filtration time is 6 minutes and the suction filtration vacuum pressure is -50 kPa.

[0049] Step 5: Filter the formed composite coating, and then dry it at 85°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the PET fiber are bonded together, and finally the desired glass fiber-based lithium battery separator composite coating is obtained.

[0050] The rest is the same as in Example 1.

[0051] Comparative Example 1

[0052] The ordinary lithium battery separator purchased on the market does not contain glass fiber and high-component fiber, has a gram weight of 4g, a thickness of 7μm, and a porosity of 42%.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that this comparative example uses only glass fiber without using high-component fiber, has a gram weight of 16 g, a thickness of 100 μm, and a porosity of 80%.

[0055] The preparation method of the lithium battery separator composite coating of this comparative example comprises the following steps:

[0056] Step 1: Weigh 100% of the glass fiber by mass and set aside;

[0057] Step 2: Add the glass fiber obtained in step 1 into a pulper, add 1500 ml of anhydrous ethanol, and stir and disperse at high speed in the pulper for 2 minutes to obtain pulp fiber;

[0058] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0059] Step 4: Pour the slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake the slurry fibers evenly during the pouring process to make the slurry fibers evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50 kPa.

[0060] Step 5: Filter the formed composite coating, and then dry it at 85°C to remove the solvent. The drying time is controlled within 20 minutes to finally obtain a lithium battery separator composite coating.

[0061] The rest is the same as in Example 1.

[0062] Comparative Example 3

[0063] The difference between this comparative example and Example 1 is that the lithium battery separator composite coating of this comparative example is prepared by compounding 80% glass fiber and 20% wood pulp fiber on a common lithium battery separator, with a gram weight of 8 g and a thickness of 40 μm.

[0064] The preparation method of the lithium battery separator composite coating of this comparative example comprises the following steps:

[0065] Step 1: Weigh 80% of glass fiber and 20% of wood pulp fiber by mass and set aside;

[0066] Step 2: Add the glass fiber and wood pulp fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0067] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0068] Step 4: Pour the mixed slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake well while pouring to make the mixed slurry fibers evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50 kPa.

[0069] Step 5: Filter the formed composite coating, and then dry it at 85°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the wood pulp fiber are bonded together, and finally a lithium battery separator composite coating is obtained.

[0070] The rest is the same as in Example 1.

[0071] Comparative Example 4

[0072] The difference between this comparative example and Example 1 is that the lithium battery separator composite coating of this comparative example is prepared by compounding 80% glass fiber and 20% PVA fiber on a common lithium battery separator, with a gram weight of 8 g and a thickness of 39 μm.

[0073] The preparation method of the lithium battery separator composite coating of this comparative example comprises the following steps:

[0074] Step 1: Weigh 80% of glass fiber and 20% of PVA fiber by mass and set aside;

[0075] Step 2: Add the glass fiber and PVA fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0076] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0077] Step 4: Pour the mixed slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake well while pouring to make the mixed slurry fibers evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50 kPa.

[0078] Step 5: Filter the formed composite coating, and then dry it at 85°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the PVA fiber are bonded together, and finally a lithium battery separator composite coating is obtained.

[0079] The rest is the same as in Example 1.

[0080] Comparative Example 5

[0081] The preparation method of the lithium battery separator composite coating of this comparative example comprises the following steps:

[0082] Step 1: Weigh 80% of glass fiber and 20% of PP fiber by mass and set aside;

[0083] Step 2: Add the glass fiber and PP fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0084] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0085] Step 4: Pour the mixed slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake well while pouring to make the mixed slurry fibers evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50 kPa.

[0086] Step 5: Filter the formed composite coating, and then dry it at 60°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the PP fiber are bonded together, and finally a lithium battery separator composite coating is obtained.

[0087] The rest is the same as in Example 1.

[0088] Comparative Example 6

[0089] The preparation method of the lithium battery separator composite coating of this comparative example comprises the following steps:

[0090] Step 1: Weigh 80% of glass fiber and 20% of PP fiber by mass and set aside;

[0091] Step 2: Add the glass fiber and PP fiber obtained in step 1 into a pulper, mix them evenly, then add 1500 ml of anhydrous ethanol, stir and disperse them at high speed in the pulper for 2 minutes to obtain mixed pulp fiber;

[0092] Step 3: Place the common lithium battery separator on the bottom layer of the filtration, and soak the common lithium battery separator with anhydrous ethanol to make the common lithium battery separator and the bottom layer of the filtration completely fit together;

[0093] Step 4: Pour the mixed slurry fibers obtained in step 2 onto the common lithium battery separator obtained in step 3 for suction filtration and forming. Shake well while pouring to make the mixed slurry fibers evenly dispersed. The suction filtration time is 3 minutes and the suction filtration vacuum pressure is -50 kPa.

[0094] Step 5: Filter the formed composite coating, and then dry it at 180°C to remove the solvent. The drying time is controlled within 20 minutes to ensure that the glass fiber and the PP fiber are bonded together, and finally a lithium battery separator composite coating is obtained.

[0095] The rest is the same as in Example 1.

[0096] Comparative Example 7

[0097] The difference between this comparative example and Example 1 is that the lithium battery separator composite coating of this comparative example has a gram weight of 20 g, a thickness of 115 μm, and a porosity of 91%.

[0098] The rest is the same as in Example 1.

[0099] The formulation compositions of the composite coatings of Examples 1-2 and Comparative Examples 1-7 are shown in Table 1.

[0100] Table 1

[0101] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Fiberglass 80 90 / 100 80 80 80 80 80 PP fiber 20 / / / / / 20 20 20 PET fiber / 10 / / / / / / / PVA fiber / / / / / 20 / / / Wood pulp fiber / / / / 20 / / / /

[0102] The properties of the composite coatings of Examples 1-2 and Comparative Examples 1-7 are shown in Table 2.

[0103] Table 2

[0104]

[0105] It can be seen from Table 1-2 that:

[0106] 1) Example 1 is compared with Comparative Example 2. Example 1 uses glass fiber and high-component fiber (PP fiber) in combination, while Comparative Example 2 uses only glass fiber without high-component fiber. The adhesion, tensile strength, cycle performance, and thermal stability of the lithium battery separator composite coating obtained in Example 1 are all higher than those in Comparative Example 2, and the composite coating is tightly bonded to the ordinary lithium battery separator and will not fall off. However, the coating obtained in Comparative Example 2 is easily detached from the surface of the ordinary lithium battery separator after molding and drying, and has poor adhesion, indicating that the high-component fiber has a very important influence on improving the adhesion of the lithium battery separator composite coating. The high-component fiber plays the role of an adhesive, ensuring that the fiber and the lithium battery separator have a strong bond and will not fall off; indicating that only by using the high-component fiber disclosed in the present invention and compounding the glass fiber can the glass fiber-based lithium battery separator composite coating required by the present invention be obtained, and compounding the glass fiber and the wood pulp fiber cannot obtain the glass fiber-based lithium battery separator composite coating required by the present invention;

[0107] 2) Comparing Example 1 with Comparative Example 1, Example 1 uses glass fiber and high-component fiber (PP fiber) compound, while Comparative Example 1 does not have glass fiber and high-component fiber. The adhesion, tensile strength, cycle performance and thermal stability of the lithium battery separator composite coating obtained in Example 1 are all higher than those in Comparative Example 1. This is because by introducing glass fiber and high-component fiber between the metal lithium negative electrode and the separator, SiO 2 It is the main component of glass fiber. It utilizes the interaction between the rich functional groups on the surface of glass fiber and lithium. It mainly utilizes the large number of Si-O and OH polar functional groups on the surface of glass fiber to promote the redistribution of lithium during the deposition process and achieve uniform deposition, thereby effectively inhibiting the formation and growth of lithium dendrites, thereby reducing the destruction and regrowth of SEI film, reducing the consumption of metal lithium and electrolyte, and effectively improving the cycle performance of metal lithium electrode batteries. The metal lithium electrode battery can increase from the original 20 cycles to 50 cycles, and its performance has been improved by 150%. In addition, glass fiber has the characteristics of high temperature resistance, heat insulation, high tensile strength, and good electrical insulation, which makes the lithium battery separator composite coating not easy to deform. Its thermal stability is much better than that of comparative example 1. The dimensional change is small at a temperature below the melting point, and it will not cause a short circuit between the positive and negative electrodes. At the same time, due to SiO 2 It is the main component of glass fiber, which can effectively improve the mechanical properties of polymer electrolytes. Glass fiber can also serve as a physical barrier to prevent thermal runaway caused by battery short circuit. It means that only by compounding the high-component fiber disclosed in the present invention with glass fiber can the glass fiber-based lithium battery separator composite coating required by the present invention be obtained. Compounding glass fiber with wood pulp fiber cannot obtain the glass fiber-based lithium battery separator composite coating required by the present invention.

[0108] 3) Comparing Example 1 with Comparative Example 3, Example 1 uses glass fiber and high-component fiber (PP fiber) compounded, while Comparative Example 3 uses glass fiber and wood pulp fiber. The bonding force, tensile strength, thermal stability and cycle performance of Comparative Example 3 are all lower than those of Example 1. This indicates that only by compounding the high-component fiber and glass fiber disclosed in the present invention can the glass fiber-based lithium battery separator composite coating required by the present invention be obtained, and compounding glass fiber and wood pulp fiber cannot obtain the glass fiber-based lithium battery separator composite coating required by the present invention;

[0109] 4) Comparing Example 1 with Comparative Example 4, Example 1 uses glass fiber and high-component fiber (PP fiber) compounded, while Comparative Example 4 uses glass fiber and PVA fiber. The addition of PVA fiber in Comparative Example 4 ensures that the fiber and the lithium battery separator are strongly combined and do not fall off, but the PVA fiber has poor heat resistance, and will shrink and deform significantly when the temperature exceeds 110-115°C, and the thermal stability is lower than that of Example 1. This shows that only by compounding the high-component fiber and glass fiber disclosed in the present invention can the glass fiber-based lithium battery separator composite coating required by the present invention be obtained, and compounding glass fiber and wood pulp fiber cannot obtain the glass fiber-based lithium battery separator composite coating required by the present invention;

[0110] 5) Comparing Example 1 with Comparative Example 5, the drying temperature of Comparative Example 5 is low, which may result in the inability to completely remove the moisture in the composite coating, thereby significantly reducing the bonding strength between the fiber and the diaphragm. The bonding force, tensile strength, thermal stability and cycle performance of Comparative Example 5 are all lower than those of Example 1. The specification states that only by using the drying temperature disclosed in the present invention can the desired glass fiber-based lithium battery diaphragm composite coating be obtained. If the drying temperature is too low, the desired glass fiber-based lithium battery diaphragm composite coating cannot be obtained;

[0111] 6) Comparing Example 1 with Comparative Example 6, the drying temperature of Comparative Example 6 is too high, which causes the fiber to melt, deform or degrade, and also reduces the bonding quality. The adhesion, tensile strength, thermal stability and cycle performance of Comparative Example 6 are all lower than those of Example 1. The specification states that only by using the drying temperature disclosed in the present invention can the desired glass fiber-based lithium battery separator composite coating be obtained. If the drying temperature is too high, the desired glass fiber-based lithium battery separator composite coating cannot be obtained;

[0112] 7) Comparing Example 1 with Comparative Example 7, the total coating thickness of Comparative Example 7 is much greater than that of Example 1, but the adhesion and cycle performance of Comparative Example 7 are lower than those of Example 1. This indicates that only within the composite coating thickness range disclosed in the present invention can the desired glass fiber-based lithium battery separator composite coating be obtained.

[0113] Parts or structures not specifically described in the present invention may adopt existing technologies or existing products and will not be described in detail here.

[0114] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A glass fiber-based lithium battery separator composite coating, characterized in that: It is prepared by compounding glass fiber and high-component fiber on an ordinary lithium battery separator, with a gram weight of 8 to 16 g, a thickness of 10 to 80 μm, and a porosity of >70%.

2. The glass fiber-based lithium battery separator composite coating according to claim 1, characterized in that: The high-component fiber is one or a combination of PP fiber, PE fiber and PET fiber.

3. The glass fiber-based lithium battery separator composite coating according to claim 1, characterized in that: The mass ratio of the glass fiber to the high-component fiber is 70-90:10-30.

4. A method for preparing a glass fiber-based lithium battery separator composite coating according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Weigh 70-90% of glass fiber and 10-30% of high-component fiber by mass percentage and set aside; Step 2: Add the glass fiber and high-component fiber obtained in step 1 into a pulper, mix them evenly, then add an organic solvent, stir and disperse them at a high speed in the pulper to obtain mixed pulp fiber; Step 3: Place the common lithium battery separator on the filtration bottom layer, and soak the common lithium battery separator with an organic solvent to make the common lithium battery separator and the filtration bottom layer completely fit together; Step 4: pour the mixed slurry fiber obtained in step 2 onto a common lithium battery separator for suction filtration and molding; Step 5: Dry the lithium battery separator composite coating obtained by filtration in step 4 to remove the organic solvent.

5. The method for preparing a glass fiber-based lithium battery separator composite coating according to claim 4, characterized in that: In step 2, the dispersion time is 1 to 10 minutes.

6. The method for preparing a glass fiber-based lithium battery separator composite coating according to claim 4, characterized in that: In step 2 and step 3, the organic solvent is one or a combination of anhydrous ethanol, N-methylpyrrolidone, and isopropanol.

7. The method for preparing a glass fiber-based lithium battery separator composite coating according to claim 4, characterized in that: In step 4, the filtration time is 2 to 8 minutes, and the filtration vacuum pressure is -50 to -70 kPa.

8. The method for preparing a glass fiber-based lithium battery separator composite coating according to claim 4, characterized in that: In step 5, the drying temperature is 70-120° C. and the drying time is 10-20 min.

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