Diaphragm and battery comprising same

Abstract

The utility model relates to the technical field of batteries, and discloses a diaphragm and a battery comprising the diaphragm. The diaphragm comprises a base material layer, a first coating and a second coating, the first coating is coated on one surface of the base material layer; the second coating is coated on one surface, deviating from the base material layer, of the first coating, and the ductility of the second coating is greater than that of the first coating; according to the diaphragm provided by the utility model, the first coating is coated on one surface of the base material layer, the second coating is coated on one surface, deviating from the base material layer, of the first coating, and the ductility of the second coating is limited to be greater than that of the first coating, so that when a needling needle penetrates through a battery, the second coating can be used for needling the battery by virtue of the higher ductility of the second coating; the diaphragm is bent downwards along with the pricking needle to separate the positive electrode from the negative electrode, and the positive electrode and the negative electrode of the battery are prevented from being communicated, so that the passing rate of a battery acupuncture experiment can be improved, and the safety performance of the battery in various application scenes can be enhanced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of battery, especially to a diaphragm and a battery comprising the diaphragm. BACKGROUND

[0002] With the rapid development of portable electronic devices, electric vehicles and other fields, the demand for high-performance and high-safety secondary batteries is increasing; lithium ion batteries are widely used in the above-mentioned fields due to their high energy density and long cycle life; however, the internal short circuit problem of the battery is one of the important factors affecting the safety of lithium ion batteries, among which the battery diaphragm as a key component to prevent the direct contact of the positive and negative electrodes plays a crucial role in ensuring the safety of the battery.

[0003] At present, there are various types of diaphragm materials and technologies on the market, but most diaphragms still show certain limitations when facing severe mechanical impact; specifically, when performing a needle puncture test, i.e. using a sharp needle to penetrate the battery to simulate the physical damage that may occur in actual use, ordinary diaphragms are difficult to maintain sufficient structural stability to prevent the direct contact of the positive and negative electrodes; this not only reduces the probability of passing the needle puncture test, but also limits the safety guarantee of the battery in various application scenarios. SUMMARY

[0004] The utility model aims at at least solving one of the technical problems existing in the prior art, and provides a diaphragm and a battery comprising the diaphragm, which can improve the passing rate of the battery needle puncture test and help to enhance the safety performance of the battery in various application scenarios.

[0005] To achieve the above-mentioned purpose, the utility model provides a diaphragm, comprising a substrate layer, a first coating layer and a second coating layer; the first coating layer is coated on one side of the substrate layer; the second coating layer is coated on the side of the first coating layer away from the substrate layer, and the ductility of the second coating layer is greater than that of the first coating layer.

[0006] In some embodiments, the first coating layer is a particle coating layer.

[0007] In some embodiments, the second coating layer is a polymer coating layer.

[0008] In some embodiments, the thickness of the first coating layer is A, and the thickness of the second coating layer is B, which satisfies: 3 μm≤A≤4 μm, 0.5 μm≤B≤1 μm.

[0009] In some embodiments, the separator further comprises a third coating layer coated on a side of the substrate layer away from the first coating layer, and a fourth coating layer coated on a side of the third coating layer away from the substrate layer, the fourth coating layer having a ductility greater than that of the third coating layer.

[0010] In some embodiments, the third coating layer is a particulate coating layer.

[0011] In some embodiments, the fourth coating layer is a polymer coating layer.

[0012] In some embodiments, the third coating layer has a thickness C, and the second coating layer has a thickness D, satisfying: 3 μm≤C≤4 μm, and 0.5 μm≤D≤1 μm.

[0013] The utility model also provides a kind of battery, the battery includes the separator according to any one of the above.

[0014] The utility model embodiment a kind of separator compared with prior art, its beneficial effect lies in: substrate layer can provide the basic support structure for entire separator, guarantee the basic physical form and mechanical strength of separator;First coating layer is coated on one side of substrate layer, second coating layer is coated on a side of first coating layer away from substrate layer, and the ductility of second coating layer is greater than that of first coating layer, since second coating layer has higher ductility, when facing such extreme situation of needle test, when needle penetrates battery, second coating layer can bend with higher ductility, so that separator is bent with needle to separate positive electrode and negative electrode, and the positive electrode and negative electrode of battery are blocked to be connected, so it can improve the pass rate of battery needle test, help to enhance the safety performance of battery in various application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is the structure schematic diagram of a kind of separator provided in the utility model embodiment.

[0016] In the drawing, 1, substrate layer;2, first coating layer;3, second coating layer;4, third coating layer;5, fourth coating layer. DETAILED DESCRIPTION

[0017] The specific embodiments of the utility model are described in further detail below in conjunction with the drawings and examples. The following examples are used to illustrate the utility model, but not to limit the scope of the utility model.

[0018] In the description of the utility model, it is understood that the directions or position relations indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the directions or position relations shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and are not intended to indicate or imply that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the utility model.

[0019] The terms "first", "second", "third", etc. are used only for descriptive purposes and should not be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, the features defined with "first", "second", etc. can explicitly or implicitly include one or more of the features.

[0020] In the utility model, unless otherwise expressly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication or interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0021] In the utility model, unless otherwise expressly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "upper" and "upper" of the first feature to the second feature include that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "below" and "below" of the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0022] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by a person skilled in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application; the terms "include" and "have" in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0023] Reference to an "example" in this application means that a particular feature, structure, or characteristic described in connection with the example can be included in at least one example of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same example, nor are they necessarily mutually exclusive or alternative examples.

[0024] As Figure 1 The utility model discloses an embodiment preferably a diaphragm, including substrate layer 1, first coating 2 and second coating 3, first coating 2 is coated on one side of substrate layer 1, second coating 3 is coated on the side of first coating 2 away from substrate layer 1, and the ductility of second coating 3 is greater than the ductility of first coating 2.

[0025] Based on the technical solution, the substrate layer 1 can provide a basic support structure for the entire diaphragm, ensuring the basic physical form and mechanical strength of the diaphragm. By coating the first coating 2 on one side of the substrate layer 1, coating the second coating 3 on the side of the first coating 2 away from the substrate layer 1, and limiting the ductility of the second coating 3 to be greater than the ductility of the first coating 2, since the second coating 3 has high ductility, when facing such extreme conditions as needle puncture experiments, when the needle penetrates the battery, the second coating 3 can bend with the needle to separate the positive and negative electrodes, thereby blocking the connection between the positive and negative electrodes of the battery, thereby improving the pass rate of the battery needle puncture experiment and enhancing the safety performance of the battery in various application scenarios.

[0026] Preferably, the first coating 2 is a particle coating. The first coating 2 as a particle coating can greatly increase the contact area of the diaphragm with the electrolyte. The presence of particles forms more micro-pores and channels, allowing the electrolyte to fully infiltrate the diaphragm, thereby significantly improving the transmission efficiency of ions in the diaphragm, which helps to speed up the charging and discharging speed of the battery and improve the overall power performance of the battery, meeting the demand for fast charging and discharging of the battery in different application scenarios. At the same time, the particle coating can also enhance the mechanical strength of the diaphragm. The particles in the particle coating act as support points, distributed between the substrate layer 1 and the second coating 3. When the diaphragm is subjected to external force, the particles can disperse stress and reduce the risk of damage caused by local stress concentration. Furthermore, the particle coating forms an anchoring effect between the substrate layer 1 and the second coating 3, making the combination between the three layers more compact and less likely to delaminate, thereby improving the stability of the diaphragm under complex working conditions of the battery.

[0027] Optionally, the first coating 2 can be a particle coating including but not limited to ceramic particles, solid-state electrolyte particles, a mixed coating of ceramic particles and solid-state electrolyte particles.

[0028] Preferably, the second coating layer 3 is a polymer coating layer. The polymer coating layer has good flexibility and ductility, which enables the second coating layer 3 to effectively play a barrier role when the separator is faced with extreme conditions such as needle puncture; when the needle puncture needle penetrates the battery, the second coating layer 3 can bend downward with the needle puncture needle, isolating the positive electrode from the negative electrode and blocking the communication between the positive and negative electrodes, greatly improving the passing rate of the needle puncture experiment, significantly reducing the risk of thermal runaway of the battery, enhancing the safety performance of the battery when subjected to external force damage, and providing more reliable protection for the safe use of the battery.

[0029] Optionally, the second coating layer 3 can be a polymer coating layer including but not limited to a polyvinylidene fluoride polymer coating layer, a polyacrylate polymer coating layer, a polyimide polymer coating layer, a polyvinyl alcohol polymer coating layer, a polyethylene oxide polymer coating layer, a polyacrylonitrile polymer coating layer, a polybenzimidazole polymer coating layer, a polytetrafluoroethylene polymer coating layer, and a polyurethane polymer coating layer.

[0030] Preferably, the thickness of the first coating layer 2 is A, and the thickness of the second coating layer 3 is B, which satisfies 3 μm≤A≤4 μm and 0.5 μm≤B≤1 μm. Limiting the thickness of the first coating layer 2 within the range of 3 μm-4 μm can not only ensure that the first coating layer 2 plays the role of enhancing electrolyte infiltration and improving mechanical strength brought by the particle coating, but also will not affect the flexibility and ion transmission efficiency of the entire separator due to excessive thickness. Limiting the thickness of the second coating layer 3 within the range of 0.5 μm-1 μm, the thickness of the second coating layer 3 is relatively thin compared to the first coating layer 2, which can fully play the advantages of high ductility and improved battery performance of the polymer coating layer without increasing the weight and cost of the entire separator.

[0031] In the present embodiment, the separator further comprises a third coating layer 4 and a fourth coating layer 5, the third coating layer 4 is coated on the side of the substrate layer 1 away from the first coating layer 2, and the fourth coating layer 5 is coated on the side of the third coating layer 4 away from the substrate layer 1, and the ductility of the fourth coating layer 5 is greater than that of the third coating layer 4.

[0032] By the third coating layer 4 and the fourth coating layer 5 and limiting the ductility of the fourth coating layer 5 to be greater than that of the third coating layer 4; when faced with extreme conditions such as needle puncture, not only the original second coating layer 3 can play a role in blocking the communication between the positive and negative electrodes, but also the fourth coating layer 5 can bend downward on the other side of the needle puncture needle due to its ductility, further blocking the possible contact path between the positive and negative electrodes, further improving the passing rate of the needle puncture experiment, and helping to further enhance the safety performance of the battery in various application scenarios.

[0033] Preferably, the third coating layer 4 is a particle coating layer.

[0034] Optionally, the third coating layer 4 can be a particle coating layer including but not limited to a ceramic particle coating layer, a solid-state electrolyte particle coating layer, and a mixed coating layer of ceramic particles and solid-state electrolyte particles.

[0035] Optionally, the material of the first coating 2 and the material of the third coating 4 can be the same or different.

[0036] Preferably, the fourth coating 5 is a polymer coating.

[0037] Optionally, the second coating 3 can be a polymer coating including but not limited to a polyvinylidene fluoride polymer coating, a polyacrylate polymer coating, a polyimide polymer coating, a polyvinyl alcohol polymer coating, a polyethylene oxide polymer coating, a polyacrylonitrile polymer coating, a polybenzimidazole polymer coating, a polytetrafluoroethylene polymer coating, a polyurethane polymer coating.

[0038] Optionally, the material of the second coating 3 and the material of the fourth coating 5 can be the same or different.

[0039] Preferably, the thickness of the third coating 4 is C, and the thickness of the second coating 3 is D, satisfying: 3 μm≤C≤4 μm, 0.5 μm≤D≤1 μm.

[0040] The utility model also provides a kind of battery, and the battery includes the separator according to any one of the above.

[0041] The above is only preferred embodiment of the utility model, it should be pointed out, for the ordinary skilled in the prior art, without departing from the technical principle of the utility model, under the premise, can make several improvements and replacement, these improvements and replacement also should be regarded as the protection range of the utility model.

Claims

1. A diaphragm, characterized by comprising: a substrate layer (1); a first coating layer (2) coated on one side of the substrate layer (1); a second coating layer (3) coated on the side of the first coating layer (2) facing away from the substrate layer (1), the second coating layer (3) having a ductility greater than that of the first coating layer (2).

2. The separator according to claim 1, characterized in that The first coating layer (2) is a particle coating layer.

3. The separator of claim 1, wherein The second coating layer (3) is a polymer coating layer.

4. The separator of claim 1, wherein The thickness of the first coating layer (2) is A and the thickness of the second coating layer (3) is B, satisfying: 3 μm≤A≤4 μm, 0.5 μm≤B≤1 μm.

5. The separator according to any one of claims 1 to 4, characterized in that further comprising a third coating layer (4) coated on the side of the substrate layer (1) facing away from the first coating layer (2) and a fourth coating layer (5) coated on the side of the third coating layer (4) facing away from the substrate layer (1), the fourth coating layer (5) having a ductility greater than that of the third coating layer (4).

6. The diaphragm of claim 5, wherein The third coating layer (4) is a particle coating layer.

7. The diaphragm of claim 5, wherein The fourth coating layer (5) is a polymer coating layer.

8. The diaphragm of claim 5, wherein, The thickness of the third coating layer (4) is C and the thickness of the second coating layer (3) is D, satisfying: 3 μm≤C≤4 μm, 0.5 μm≤D≤1 μm.

9. A battery, characterized by The diaphragm according to any one of claims 1-8. The diaphragm according to any one of claims 1-8.

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