Composite diaphragm and battery

Abstract

The utility model relates to the technical field of batteries, in particular to a composite diaphragm and a battery. The composite diaphragm comprises a base material layer, an aramid fiber layer, a heat-resistant layer and an organic bonding layer, the heat-resistant layer is arranged on the surface of one side of the base material layer, and the aramid fiber layer is arranged on the surface of the other side of the base material layer; the organic bonding layer is arranged on the surface, far away from the base material layer, of the aramid fiber layer; and the organic bonding layer is a discontinuous point-shaped coating. In the composite diaphragm, the aramid fiber layer can increase the overall diaphragm rupture temperature of the diaphragm and can store more electrolyte; the heat-resistant layer can improve the heat resistance of the diaphragm, ensures that the diaphragm is not easy to shrink at high temperature, and improves the safety; the organic bonding layers are distributed in a dotted manner, so that the bonding property with the pole piece is realized, and more gap spaces can be generated for the diaphragm and the pole piece; through cooperation of all the layers, the composite diaphragm has the properties of high heat resistance, high diaphragm rupture, high liquid storage and high adhesion, and is beneficial to improvement of the cycle performance and safety performance of the battery.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field, specifically, relate to a kind of composite diaphragm and battery. BACKGROUND

[0002] Diaphragm is as the four big component modules of battery, cathode and anode are isolated, prevent two poles contact and short circuit, diaphragm is as its important component part, its overall performance affects the overall performance of battery cell, such as diaphragm heat resistance affects the safety of battery cell, diaphragm and the adhesion of pole piece affect the overall hardness of battery cell, therefore the performance of diaphragm is related to the good and bad of battery cell performance.The modification of prior art to diaphragm is single, and the comprehensive performance of the composite diaphragm obtained is not ideal.Therefore, a multifunctional coating diaphragm needs to be developed to improve the shortcomings of bare film.

[0003] Therefore, the utility model is proposed. UTILITY MODEL CONTENT

[0004] One purpose of the utility model is to provide a kind of composite diaphragm, it has high heat resistance, high membrane breaking, high liquid storage and high adhesion, and good comprehensive performance.

[0005] Another purpose of the utility model is to provide a kind of battery, which has excellent cycle stability and safety performance.

[0006] In order to achieve the above purposes of the utility model, the following technical solutions are adopted:

[0007] A kind of composite diaphragm, including substrate layer, aramid layer, heat-resistant layer and organic adhesive layer;The heat-resistant layer is arranged on one side surface of the substrate layer, and the aramid layer is arranged on the other side surface of the substrate layer;The organic adhesive layer is arranged on the surface of the aramid layer away from the substrate layer;The organic adhesive layer is non-continuous point coating.

[0008] In some embodiments, the coverage of the organic adhesive layer on the surface of the aramid layer is 15% to 35%.

[0009] In some embodiments, the coverage of the organic adhesive layer on the surface of the aramid layer is 20% to 30%.

[0010] In some embodiments, the shape of the non-continuous point coating includes a circle.

[0011] In some embodiments, the diameter of the non-continuous point coating is 100 to 500 μm.

[0012] In some embodiments, the thickness of the non-continuous point coating is 4 to 10 μm.

[0013] In some embodiments, the non-continuous point-like coating has a diameter of 200-400 μm; and the non-continuous point-like coating has a thickness of 5-9 μm.

[0014] In some embodiments, the aramid layer has a thickness of 0.5-3 μm.

[0015] In some embodiments, the aramid layer has a porosity of 50-70%.

[0016] In some embodiments, the aramid layer has an average pore size of 0.05-0.5 μm.

[0017] In some embodiments, the aramid layer has a thickness of 1-2 μm.

[0018] In some embodiments, the aramid layer has a porosity of 60-65%; and the aramid layer has an average pore size of 0.1-0.4 μm.

[0019] In some embodiments, the heat-resistant layer has a thickness of 1-4 μm.

[0020] In some embodiments, the heat-resistant layer is an inorganic ceramic layer.

[0021] In some embodiments, the substrate layer has a thickness of 4-12 μm.

[0022] In some embodiments, the heat-resistant layer has a thickness of 2-3 μm.

[0023] A battery comprising the composite separator, a positive electrode sheet and a negative electrode sheet; the composite separator is located between the positive electrode sheet and the negative electrode sheet, the heat-resistant layer is adjacent to the positive electrode sheet, and the organic adhesive layer is adjacent to the negative electrode sheet.

[0024] Compared with the prior art, the composite separator has the advantages that:

[0025] (1) The aramid layer in the composite separator can improve the overall membrane breaking temperature of the separator, the reticular aramid layer has a high porosity and can store more electrolyte, thereby improving the capacity retention rate of the battery and the cycle performance of the battery; the heat-resistant layer can improve the heat resistance of the separator, so that the separator is not easy to shrink at high temperature, thereby improving the safety; the organic adhesive layer is distributed in a point-like manner, which can improve the adhesion with the electrode sheet and provide more gap space between the separator and the electrode sheet, thereby improving the capacity retention rate of the battery cell.

[0026] (2) The battery, the heat-resistant layer corresponds to the positive plate, the organic adhesive layer and the aramid layer correspond to the negative plate, the aramid layer and the organic adhesive layer can be avoided to be oxidized by high potential, thereby prolonging the service life of the diaphragm; the battery has excellent cycle stability and safety performance. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0028] Figure 1 It is a whole structure schematic view of the composite diaphragm in the present application.

[0029] Figure 2 It is a top view structure schematic view of the composite diaphragm in the present application.

[0030] Reference signs:

[0031] 1 - substrate layer, 2 - aramid layer, 3 - heat-resistant layer, 4 - organic adhesive layer. DETAILED DESCRIPTION

[0032] In the description of the present application, it should be explained that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly used when the product of the present application is used, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements must have a particular orientation, structure and operation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only used for differentiation, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present application, it should also be explained that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] In one aspect, the utility model relates to a kind of composite diaphragm, including substrate layer, aramid layer, heat-resistant layer and organic adhesive layer;The surface of one side of the substrate layer is provided with the heat-resistant layer, the surface of another side of the substrate layer is provided with the aramid layer;The surface of the aramid layer away from the substrate layer is provided with the organic adhesive layer;The organic adhesive layer is non-continuous point coating.

[0035] Aramid layer can improve the overall membrane breaking temperature of diaphragm, the aramid layer with mesh has the performance of high porosity, can store more electrolyte, improve the capacity retention rate of battery, to improve the cycle performance of battery;Heat-resistant layer can improve the heat resistance of diaphragm, ensure that diaphragm is not easy to shrink at high temperature, improve safety;Organic adhesive layer is distributed in point, play the adhesion with pole piece, and can also produce more gap space for diaphragm and pole piece, improve the capacity retention rate of battery. Through the cooperation of each layer, the composite diaphragm of the utility model has the performance of high heat resistance, high membrane breaking, high liquid storage and high adhesion, which is beneficial to improve the cycle performance and safety performance of battery.

[0036] In some embodiments, the coverage of the organic adhesive layer on the surface of the aramid layer is 15% to 35%, for example, 15%, 18%, 20%, 25%, 30%, 35%, or any range between any two of them. Preferably, the coverage of the organic adhesive layer on the surface of the aramid layer is 20% to 30%. In some embodiments, the shape of the non-continuous point coating includes a circle; the diameter of the non-continuous point coating is 100 to 500 μm, including but not limited to 100 μm, 150 μm, 200 μm, 300 μm, 350 μm, 400 μm, 450 μm or 500 μm, or any range between any two of them. Preferably, the diameter of the non-continuous point coating is 200 to 400 μm. In some embodiments, the thickness of the non-continuous point coating is 4 to 10 μm, for example, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, or any range between any two of them. Preferably, the thickness of the non-continuous point coating is 5 to 9 μm. The appropriate coverage, diameter and thickness of the point coating of the organic adhesive layer are more conducive to ensuring the adhesion with the pole piece, while producing more gap space for the diaphragm and the pole piece, improving the capacity retention rate of the battery.

[0037] In some embodiments, the material of the organic adhesive layer is a conventional adhesive material, such as polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polyacrylonitrile, polyacrylate or butadiene styrene rubber, or PVDF and PMMA.

[0038] In some embodiments, the particle size D50 of the binder material in the organic adhesive layer is 1-8 μm, and the D10 is greater than 0.5 μm. In some embodiments, the particle size D50 of the PVDF is 3-8 μm, and the D10 is greater than 1.0 μm. In some embodiments, the particle size D50 of the PMMA is 1-5 μm, and the D10 is greater than 0.5 μm. The binder material in the organic adhesive layer has a suitable particle size, which can avoid a large amount of organic adhesive from entering the pores of the aramid coating layer, blocking the pores of the aramid coating layer, and reducing the porosity of the aramid coating layer, thereby ensuring high liquid storage while ensuring adhesion to the pole piece.

[0039] In some embodiments, the thickness of the aramid layer is 0.5-3 μm, including but not limited to 0.5 μm, 1 μm, 1.5 μm, 2 μm, 3.5 μm, or 3 μm, or any range between any two of them. Preferably, the thickness of the aramid layer is 1-2 μm. In some embodiments, the porosity of the aramid layer is 50%-70%, including but not limited to 50%, 55%, 60%, 65%, 70%, or any range between any two of them. Preferably, the porosity of the aramid layer is 60%-65%. In some embodiments, the average pore size of the aramid layer is 0.05-0.5 μm, including but not limited to 0.05 μm, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, or 0.5 μm, or any range between any two of them. Preferably, the average pore size of the aramid layer is 0.1-0.4 μm, more preferably 0.3-0.3 μm. The aramid layer has a suitable porosity, average pore size, and thickness, which is more conducive to improving the overall membrane rupture temperature of the separator, ensuring the storage of more electrolyte, and better cooperating with other layer structures to improve the capacity retention rate of the battery.

[0040] In some embodiments, the material of the aramid layer is a conventional aramid material, such as para-aramid, meta-aramid, or bio-aramid.

[0041] In some embodiments, the thickness of the heat-resistant layer is 1-4 μm, such as 1 μm, 1.5 μm, 2 μm, 3 μm, 4 μm, or any range between any two of them. Preferably, the thickness of the heat-resistant layer is 2-3 μm. In some embodiments, the heat-resistant layer is a conventional inorganic ceramic layer, such as alumina, boehmite, zirconia, magnesium hydroxide, or a solid-state electrolyte. In some embodiments, the heat-resistant layer also contains glue (such as polyacrylic acid, polyacrylate, or styrene butadiene rubber) and a wetting agent.

[0042] In some embodiments, the substrate layer includes a PP, PE, or PP / PE composite film. The thickness of the substrate layer is 4-12 μm, such as 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or the like.

[0043] In some embodiments, the thermal shrinkage rate of the composite diaphragm at 150°C / h is less than 3% in both the MD and TD directions, for example, 1%, 1.5%, 2%, 2.5%, etc.

[0044] In some embodiments, the TMA rupture temperature of the composite diaphragm is greater than 220°C, such as 225°C, 230°C, 240°C, 250°C, etc.

[0045] In some embodiments, the method for preparing the composite diaphragm includes: coating one side of a substrate layer with an oily aramid material to obtain an aramid layer; coating the other side of the substrate layer with a heat-resistant material to obtain a heat-resistant layer; and coating the surface of the aramid layer with an organic adhesive material to obtain an organic adhesive layer. The coating process uses conventional operations, as long as the corresponding coating is obtained.

[0046] In another aspect, this utility model also relates to a battery, including the aforementioned composite separator, positive electrode, and negative electrode; the composite separator is located between the positive electrode and the negative electrode, the heat-resistant layer is adjacent to the positive electrode, and the organic adhesive layer is adjacent to the negative electrode.

[0047] In this battery, the heat-resistant layer corresponds to the positive electrode, and the organic binder layer and aramid layer correspond to the negative electrode. This can prevent the aramid layer and organic binder layer from being oxidized by high potential, thereby extending the service life of the separator.

[0048] The following explanation, in conjunction with specific embodiments, further clarifies the situation.

[0049] Example 1

[0050] A composite membrane, such as Figure 1 and Figure 2 As shown, it includes a substrate layer 1, an aramid layer 2, a heat-resistant layer 3, and an organic adhesive layer 4; the heat-resistant layer 3 is disposed on one side surface of the substrate layer 1, and the aramid layer 2 is disposed on the other side surface of the substrate layer 1; the organic adhesive layer 4 is disposed on the surface of the aramid layer 2 away from the substrate layer 1; the organic adhesive layer 4 is a discontinuous dotted coating.

[0051] The organic binder layer 4 has a coverage of 25% on the surface of the aramid layer 2. The shape of the discontinuous dotted coating includes circles; the diameter of the discontinuous dotted coating is 300 μm; and the thickness of the discontinuous dotted coating is 6 μm. The organic binder in the organic binder layer 4 is PVDF with a particle size D50 of 5 μm and a D10 of 2 μm.

[0052] The aramid layer 2 has a thickness of 1.5 μm, a porosity of 60%, and an average pore size of 0.3 μm. The material in the aramid layer 2 is para-aramid.

[0053] The heat-resistant layer 3 is an aluminum oxide layer, and the thickness of the heat-resistant layer 3 is 2.5μm.

[0054] The substrate layer 1 is PE, and the thickness is 7 μm.

[0055] A battery includes the composite separator in the embodiment, a positive electrode sheet, and a negative electrode sheet; the composite separator is located between the positive electrode sheet and the negative electrode sheet, the heat-resistant layer 3 is adjacent to the positive electrode sheet, and the organic adhesive layer 4 is adjacent to the negative electrode sheet.

[0056] Embodiment 2

[0057] A composite separator includes a substrate layer 1, an aramid layer 2, a heat-resistant layer 3, and an organic adhesive layer 4; one side surface of the substrate layer 1 is provided with the heat-resistant layer 3, and the other side surface of the substrate layer 1 is provided with the aramid layer 2; the aramid layer 2 is provided with the organic adhesive layer 4 away from the surface of the substrate layer 1; and the organic adhesive layer 4 is a discontinuous point coating.

[0058] The coverage of the organic adhesive layer 4 on the surface of the aramid layer 2 is 25%. The shape of the discontinuous point coating includes a circular shape; the diameter of the discontinuous point coating is 300 μm; and the thickness of the discontinuous point coating is 6 μm. The organic adhesive in the organic adhesive layer 4 is PMMA, the particle size D50 is 4 μm, and the particle size D10 is 0.8 μm.

[0059] The thickness of the aramid layer 2 is 2 μm, the porosity of the aramid layer 2 is 65%, and the average pore size of the aramid layer 2 is 0.35 μm. The material in the aramid layer 2 is meta-aramid.

[0060] The heat-resistant layer 3 is a zirconium oxide layer, and the thickness of the heat-resistant layer 3 is 3 μm.

[0061] The substrate layer 1 is PP, and the thickness is 8 μm.

[0062] A battery, which is different from the battery in Embodiment 1, uses the composite separator in the embodiment.

[0063] Embodiment 3

[0064] A composite separator includes a substrate layer 1, an aramid layer 2, a heat-resistant layer 3, and an organic adhesive layer 4; one side surface of the substrate layer 1 is provided with the heat-resistant layer 3, and the other side surface of the substrate layer 1 is provided with the aramid layer 2; the aramid layer 2 is provided with the organic adhesive layer 4 away from the surface of the substrate layer 1; and the organic adhesive layer 4 is a discontinuous point coating.

[0065] The coverage of the organic adhesive layer 4 on the surface of the aramid layer 2 is 15%. The shape of the discontinuous point coating includes a circular shape; the diameter of the discontinuous point coating is 100 μm; and the thickness of the discontinuous point coating is 4 μm. The organic adhesive in the organic adhesive layer 4 is PVDF, the particle size D50 is 5 μm, and the particle size D10 is 2 μm.

[0066] The thickness of the aramid layer 2 is 0.5 μm, the porosity of the aramid layer 2 is 50%, and the average pore size of the aramid layer 2 is 0.1 μm. The material in the aramid layer 2 is para-aramid.

[0067] The heat-resistant layer 3 is a zirconium oxide layer, and the thickness of the heat-resistant layer 3 is 1 μm.

[0068] The substrate layer 1 is PE, and the thickness is 4 μm.

[0069] A battery, which is different from the battery of Embodiment 1 in that the composite separator in this embodiment is used.

[0070] Embodiment 4

[0071] A composite separator, which comprises a substrate layer 1, an aramid layer 2, a heat-resistant layer 3, and an organic adhesive layer 4; the substrate layer 1 is provided with the heat-resistant layer 3 on one side surface, and the substrate layer 1 is provided with the aramid layer 2 on the other side surface; the aramid layer 2 is provided with the organic adhesive layer 4 on the surface away from the substrate layer 1; and the organic adhesive layer 4 is a discontinuous dot-shaped coating.

[0072] The coverage of the organic adhesive layer 4 on the surface of the aramid layer 2 is 35%. The shape of the discontinuous dot-shaped coating comprises a circle; the diameter of the discontinuous dot-shaped coating is 500 μm; and the thickness of the discontinuous dot-shaped coating is 10 μm. The organic adhesive in the organic adhesive layer 4 is PVDF, the particle size D50 is 8 μm, and the particle size D10 is 2.5 μm.

[0073] The thickness of the aramid layer 2 is 3 μm, the porosity of the aramid layer 2 is 70%, and the average pore size of the aramid layer 2 is 0.4 μm. The material in the aramid layer 2 is para-aramid.

[0074] The heat-resistant layer 3 is a zirconium oxide layer, and the thickness of the heat-resistant layer 3 is 4 μm.

[0075] The substrate layer 1 is PE, and the thickness is 12 μm.

[0076] A battery, which is different from the battery of Embodiment 1 in that the composite separator in this embodiment is used.

[0077] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A composite separator, characterized by, The composite diaphragm comprises a substrate layer, an aramid layer, a heat-resistant layer and an organic adhesive layer; one side surface of the substrate layer is provided with the heat-resistant layer, and the other side surface of the substrate layer is provided with the aramid layer; the surface of the aramid layer away from the substrate layer is provided with the organic adhesive layer; and the organic adhesive layer is a discontinuous point coating.

2. The composite separator of claim 1, wherein The coverage of the organic adhesive layer on the surface of the aramid layer is 15% to 35%.

3. The composite separator of claim 2, wherein, The coverage of the organic adhesive layer on the surface of the aramid layer is 20% to 30%.

4. The composite separator of claim 1, wherein The shape of the discontinuous point coating comprises a circle. The diameter of the discontinuous point coating is 100 to 500 μm. The thickness of the discontinuous point coating is 4 to 10 μm.

5. The composite separator of claim 4, wherein, The diameter of the discontinuous point coating is 200 to 400 μm. The thickness of the discontinuous point coating is 5 to 9 μm.

6. The composite separator of claim 1, wherein The thickness of the aramid layer is 0.5 to 3 μm. The porosity of the aramid layer is 50% to 70%. The average pore size of the aramid layer is 0.05 to 0.5 μm.

7. The composite separator of claim 6, wherein The thickness of the aramid layer is 1 to 2 μm. The porosity of the aramid layer is 60% to 65%. The average pore size of the aramid layer is 0.1 to 0.4 μm.

8. The composite separator of claim 1, wherein The thickness of the heat-resistant layer is 1 to 4 μm. The heat-resistant layer is an inorganic ceramic layer. The thickness of the substrate layer is 4 to 12 μm.

9. The composite separator of claim 8, wherein, The thickness of the heat-resistant layer is 2 to 3 μm.

10. A battery, characterized by The composite diaphragm comprises a substrate layer, an aramid layer, a heat-resistant layer and an organic adhesive layer; one side surface of the substrate layer is provided with the heat-resistant layer, and the other side surface of the substrate layer is provided with the aramid layer; the surface of the aramid layer away from the substrate layer is provided with the organic adhesive layer; and the organic adhesive layer is a discontinuous point coating.

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