High-safety lithium battery diaphragm

Abstract

The utility model discloses a lithium battery diaphragm with high safety, which relates to the technical field of lithium battery diaphragms and comprises a first base membrane and a silicon dioxide layer, a polyethylene layer is arranged at the lower end of the first base membrane, the silicon dioxide layer is arranged at the lower end of the polyethylene layer, and a high-strength conducting layer is arranged at the lower end of the silicon dioxide layer. Meanwhile, a polypropylene layer is arranged at the lower end of the high-strength conductive layer, a second base film is adhered to the lower end of the polypropylene layer, the outer side of the first base film is flush with the outer side of the polyethylene layer, and the outer side of the first base film is tightly adhered to the outer side of the polyethylene layer. According to the high-safety lithium battery diaphragm, the overall thickness of the diaphragm can be increased in the using process, the silicon dioxide layer and the high-strength conductive layer are matched to improve the safety of the diaphragm in the using process, the lithium battery diaphragm is prevented from being punctured by pole piece burrs or lithium dendrites in the using process, and the overall service life of the lithium battery diaphragm is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery diaphragms, and specifically relates to a high-safety lithium battery diaphragm. Background Technique

[0002] In the structure of a lithium battery, the diaphragm is one of the key inner components. The performance of the diaphragm determines the interface structure, internal resistance, etc. of the battery, and directly affects the characteristics such as the capacity, cycle, and safety performance of the battery. A diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery. The main function of the diaphragm is to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short-circuiting. In addition, it also has the function of allowing electrolyte ions to pass through. The diaphragm material is non-conductive, and its physical and chemical properties have a great impact on the performance of the battery. In order to improve the service life of lithium batteries, a lithium battery diaphragm is required. However, the existing lithium battery diaphragms still have the following deficiencies:

[0003] For example, the utility model with the application number 201922474594.0 discloses a lithium battery diaphragm. The lithium battery diaphragm of this utility model has a high porosity, good air permeability, good liquid absorption, good electrolyte retention, significantly improves the long cycle of the battery, has instant liquid absorption, and can activate the battery 10 s after injecting the liquid; it has good electrolyte infiltration performance, can shorten the standing time of the battery cell after injecting the liquid, and its good thermal dimensional stability can shorten the baking time of the diaphragm. However, for comparative documents similar to the above application, when the existing lithium battery diaphragms are in use, since most lithium battery diaphragms are relatively thin as a whole, the lithium battery diaphragms are easily pierced by the burrs of the electrode plates or lithium dendrites during use, resulting in easy short-circuiting of the diaphragms, affecting the use safety, and causing the problems of reduced practicability and use efficiency of the lithium battery diaphragms.

[0004] Therefore, in view of this, research and improvement are carried out on the existing structure and deficiencies, and a high-safety lithium battery diaphragm is proposed. Content of the Utility Model

[0005] The purpose of the utility model is to provide a high-safety lithium battery diaphragm to solve the problems raised in the above background technique.

[0006] To achieve the above purpose, the utility model provides the following technical solution: A high-safety lithium battery diaphragm includes a first base film and a silica layer. A polyethylene layer is arranged at the lower end of the first base film, a silica layer is arranged at the lower end of the polyethylene layer, a high-strength conductive layer is arranged at the lower end of the silica layer, a polypropylene layer is arranged at the lower end of the high-strength conductive layer, and a second base film is adhesively connected to the lower end of the polypropylene layer.

[0007] Furthermore, the outer side of the first base film is flush with the outer side of the polyethylene layer, and the outer side of the first base film is tightly adhesively connected to the outer side of the polyethylene layer.

[0008] Furthermore, on the upper and lower sides of the polyethylene layer are a first base film and a silica layer respectively, and the polyethylene layer is confined between the first base film and the silica layer.

[0009] Furthermore, the outer sides of the silica layer and the high-strength conductive layer are flush with each other, and the outer sides of the silica layer and the high-strength conductive layer are closely attached to each other.

[0010] Furthermore, on the upper and lower sides of the high-strength conductive layer are a silica layer and a polypropylene layer respectively, and the high-strength conductive layer is confined between the silica layer and the polypropylene layer.

[0011] Furthermore, the outer side of the polypropylene layer is flush with the outer side of the second base film, and the outer side of the polypropylene layer is closely adhered to the outer side of the second base film.

[0012] The utility model provides a high-safety lithium battery separator, which has the following beneficial effects:

[0013] 1. Through the setting of the silica layer, when the high-safety lithium battery separator is in use, the first base film and the polyethylene layer can be closely adhered together by the PMMA adhesive, and the polyethylene layer and the silica layer can be adhered together with the cooperation of the PMMA adhesive. Due to the high specific surface area of the silica layer and its good wettability to the electrolyte, the lithium battery separator also exhibits a relatively high porosity and liquid absorption rate. The introduction of the silica layer not only greatly improves the thermal stability and mechanical properties of the lithium battery separator, but also enhances the absorption of the electrolyte, greatly increasing the safety during the use of the separator.

[0014] 2. Through the setting of the high-strength conductive layer, when the high-safety lithium battery separator is in use, the high-strength conductive layer can be arranged below the silica layer by the adhesive, and the polypropylene layer can be installed below the high-strength conductive layer with the cooperation of the adhesive. The high-strength conductive layer is formed by polymer adhesion of solid electrolyte particles, which can enhance the conductivity of lithium ions in the middle of the separator, improve the separator conductivity, and at the same time can effectively prevent the pole piece burrs or lithium dendrites from piercing the separator and causing a short circuit. The installation of the second base film is combined to form the overall lithium battery separator, further improving the safety during the use of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a three-dimensional structure diagram of a high-safety lithium battery separator of the utility model;

[0016] Figure 2 is a three-dimensional unfolded structure diagram of a high-safety lithium battery separator of the utility model;

[0017] Figure 3 is a three-dimensional cross-sectional structure diagram of a high-safety lithium battery separator of the utility model.

[0018] In the figure: 1. First base film; 2. Polyethylene layer; 3. Silicon dioxide layer; 4. High-strength conductive layer; 5. Polypropylene layer; 6. Second base film. Specific embodiments

[0019] The following further describes in detail the embodiments of the present utility model in conjunction with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present utility model, but cannot be used to limit the scope of the present utility model.

[0020] As Figures 1 to 3 shown, a high-safety lithium battery separator includes a first base film 1 and a silicon dioxide layer 3. A polyethylene layer 2 is provided at the lower end of the first base film 1, and a silicon dioxide layer 3 is provided at the lower end of the polyethylene layer 2. The outer sides of the first base film 1 and the polyethylene layer 2 are flush with each other, and the outer sides of the first base film 1 and the polyethylene layer 2 are tightly adhered. The upper and lower sides of the polyethylene layer 2 are the first base film 1 and the silicon dioxide layer 3 respectively, and the polyethylene layer 2 is restricted between the first base film 1 and the silicon dioxide layer 3. The first base film 1 and the polyethylene layer 2 are tightly adhered together through a PMMA adhesive, and the PMMA adhesive is used to bond the polyethylene layer 2 and the silicon dioxide layer 3. Due to the high specific surface area of the silicon dioxide layer 3 and its good wettability to the electrolyte, the lithium battery separator also exhibits a relatively high porosity and liquid absorption rate. The introduction of the silicon dioxide layer 3 not only greatly improves the thermal stability and mechanical properties of the lithium battery separator, but also enhances the absorption of the electrolyte, greatly increasing the safety during the use of the separator.

[0021] As Figures 1 to 3 shown, a high-strength conductive layer 4 is provided at the lower end of the silicon dioxide layer 3. At the same time, a polypropylene layer 5 is provided at the lower end of the high-strength conductive layer 4, and a second base film 6 is adhered to the lower end of the polypropylene layer 5. The outer sides of the silicon dioxide layer 3 and the high-strength conductive layer 4 are flush with each other, and the outer sides of the silicon dioxide layer 3 and the high-strength conductive layer 4 are tightly attached. The upper and lower sides of the high-strength conductive layer 4 are the silicon dioxide layer 3 and the polypropylene layer 5 respectively, and the high-strength conductive layer 4 is restricted between the silicon dioxide layer 3 and the polypropylene layer 5. The outer sides of the polypropylene layer 5 and the second base film 6 are flush with each other, and the outer sides of the polypropylene layer 5 and the second base film 6 are tightly adhered. The high-strength conductive layer 4 is formed by polymer adhesion of solid electrolyte particles, which can enhance the conductivity of lithium ions in the middle of the separator and improve the separator conductivity. At the same time, it can effectively prevent the burrs of the electrode sheet or lithium dendrites from piercing the separator and causing a short circuit. The installation of the second base film 6 constitutes the overall lithium battery separator, further enhancing the safety during the use of the battery.

[0022] In summary, for the high-safety lithium battery separator, during use, first, the first base film 1 and the polyethylene layer 2 are tightly bonded together through the PMMA adhesive, and the PMMA adhesive is used to bond the polyethylene layer 2 and the silica layer 3. Due to the high specific surface area of the silica layer 3 and its good wettability to the electrolyte, the lithium battery separator also exhibits a relatively high porosity and liquid absorption rate. The introduction of the silica layer 3 not only greatly improves the thermal stability and mechanical properties of the lithium battery separator, but also enhances the absorption of the electrolyte, greatly increasing the safety during the use of the separator. Next, the high-strength conductive layer 4 is disposed under the silica layer 3 through the adhesive, and the polypropylene layer 5 is installed under the high-strength conductive layer 4 through the adhesive. The high-strength conductive layer 4 is formed by polymer adhesion of solid electrolyte particles, which can enhance the conductivity of lithium ions in the separator and improve the separator conductivity. At the same time, it can effectively prevent the electrode tab burrs or lithium dendrites from piercing the separator and causing a short circuit. The installation of the second base film 6 is used to form the overall lithium battery separator, further enhancing the safety during the use of the battery. Finally, the polyethylene layer 2 and the polypropylene layer 5 increase the thickness of the lithium battery separator, greatly reducing the short circuit phenomenon generated during the manufacturing and use of the lithium battery, improving the self-discharge phenomenon of the lithium battery and reducing potential safety hazards.

[0023] The embodiments of the present invention are given for purposes of illustration and description, and are not exhaustive or limit the present invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are chosen and described in order to better explain the principles of the present invention and its practical applications, and to enable those of ordinary skill in the art to understand the present invention and design various embodiments with various modifications suitable for specific purposes.

Claims

1. A high-safety lithium battery separator, comprising a first base film (1) and a silicon dioxide layer (3), characterized in that: A polyethylene layer (2) is arranged at the lower end of the first base film (1), a silicon dioxide layer (3) is arranged at the lower end of the polyethylene layer (2), a high-strength conductive layer (4) is arranged at the lower end of the silicon dioxide layer (3), and a polypropylene layer (5) is arranged at the lower end of the high-strength conductive layer (4), and a second base film (6) is adhered to the lower end of the polypropylene layer (5).

2. A high-safety lithium battery separator according to claim 1, characterized in that: The outer side of the first base film (1) is flush with the outer side of the polyethylene layer (2), and the outer side of the first base film (1) is tightly adhered to the outer side of the polyethylene layer (2).

3. A high-safety lithium battery separator according to claim 1, characterized in that: The upper and lower sides of the polyethylene layer (2) are respectively the first base film (1) and the silicon dioxide layer (3), and the polyethylene layer (2) is confined between the first base film (1) and the silicon dioxide layer (3).

4. A high-safety lithium battery separator according to claim 1, characterized in that: The outer side of the silicon dioxide layer (3) is flush with the outer side of the high-strength conductive layer (4), and the outer side of the silicon dioxide layer (3) is tightly attached to the outer side of the high-strength conductive layer (4).

5. A high-safety lithium battery separator according to claim 1, characterized in that: The upper and lower sides of the high-strength conductive layer (4) are respectively a silicon dioxide layer (3) and a polypropylene layer (5), and the high-strength conductive layer (4) is confined between the silicon dioxide layer (3) and the polypropylene layer (5).

6. A high-safety lithium battery separator according to claim 1, characterized in that: The outer side of the polypropylene layer (5) is flush with the outer side of the second base film (6), and the outer side of the polypropylene layer (5) is tightly adhered to the outer side of the second base film (6).

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