Ultrahigh molecular weight polyethylene composite diaphragm for high-performance lithium battery
By designing a multi-layer composite structure of ultra-high molecular polyethylene composite separator for lithium batteries, the problem of existing lithium battery separators being easily melted or broken at high temperatures is solved, and higher mechanical strength, thermal resistance and ion channel efficiency are achieved, which significantly improves the safety and stability of lithium batteries.
Patent Information
- Application Number
- CN202411822538.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-03-18
AI Technical Summary
The existing polyethylene separators for lithium batteries are easily melted or contracted at high temperatures, causing the separator to deform, have low mechanical strength, and are prone to rupture, affecting the stability and safety of the battery.
A high-performance ultra-high molecular polyethylene composite separator is designed, including coating, antibacterial layer, microporous layer No. 1, microporous layer No. 2, functional layer, reinforcement layer and polyvinyl film. Through the combination of these layers, a multi-layer composite structure is formed to enhance the strength and thermal resistance of the membrane.
The separator prevents heat conduction through the functional layer, the reinforcement layer improves mechanical strength, the nanoblock enhances tensile and impact resistance, the multi-layer microporous structure improves ion channels, and the antibacterial layer prevents corrosion, which significantly improves the safety, stability and overall performance of the lithium battery separator.
Smart Images
Figure CN119651060A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of polyethylene composite diaphragms, in particular to an ultra-high molecular polyethylene composite diaphragm for high-performance lithium batteries. Background Art
[0002] Lithium battery is a rechargeable battery with lithium metal or lithium compound as battery electrode material, which is widely used in mobile phones, electric vehicles, portable devices and other fields. Its main advantages are high energy density, long cycle life and light weight. Lithium battery is charged and discharged by the migration of lithium ions between positive and negative electrodes. In lithium battery, the positive electrode and negative electrode are separated by polyethylene composite diaphragm, while allowing lithium ions to pass freely during charging and discharging.
[0003] Since the structure of the existing polyethylene diaphragm for lithium batteries is relatively simple and the melting point of polyethylene is low, when the temperature inside the battery rises, the polyethylene diaphragm is prone to melt or shrink, causing the diaphragm to deform. The mechanical strength of polyethylene is low and it is easy to break, affecting the stability and safety of the battery.
[0004] Therefore, we proposed an ultra-high molecular weight polyethylene composite separator for high-performance lithium batteries. Summary of the invention
[0005] The purpose of the present invention is to provide an ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries to solve the problems of the polyethylene diaphragm for lithium batteries mentioned in the above background technology that is prone to melting or shrinkage, resulting in deformation of the diaphragm, and the mechanical strength of the polyethylene is low and easy to rupture.
[0006] To achieve the above object, the present invention provides the following technical solutions:
[0007] A high-performance ultra-high molecular polyethylene composite diaphragm for lithium batteries comprises a polymer diaphragm and No. 1 pores, wherein the polymer diaphragm comprises a coating, an antibacterial layer, a No. 1 microporous layer, a No. 2 microporous layer, a functional layer, a reinforcing layer, and a polyethylene-based film, wherein the inner surface of the coating is provided with an antibacterial layer, a No. 1 microporous layer is provided on a side of the antibacterial layer away from the coating, and the No. 1 pores are uniformly distributed on the inner side of the No. 1 microporous layer.
[0008] Preferably, a second microporous layer is provided on a side of the first microporous layer away from the antibacterial layer.
[0009] Preferably, a functional layer is disposed on a side of the second microporous layer away from the first microporous layer.
[0010] Preferably, a reinforcement layer is provided on a side of the functional layer away from the second microporous layer.
[0011] Preferably, a polyethylene-based film is provided on a side of the reinforcement layer away from the functional layer.
[0012] Preferably, the inner sides of the second microporous layer, the functional layer, the reinforcement layer, and the polyethylene-based film are all provided with through holes distributed at equal intervals.
[0013] Preferably, a membrane block penetrates the inner side of the through hole.
[0014] Preferably, a plurality of No. 2 pores are distributed in an annular shape on the inner side of the membrane block, and a plurality of nano blocks are provided on the surface of the reinforcement layer.
[0015] Preferably, an antibacterial sheet and an isolation belt are provided on the surface of the antibacterial layer, and the antibacterial sheet and the isolation belt are distributed in a transverse manner.
[0016] Preferably, the pore sizes of the No. 1 pores and the No. 2 microporous layer are both 0.2-0.4 μm, and the thicknesses of the isolation belt and the antibacterial sheet are both 2-12 μm.
[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: the ultra-high molecular polyethylene composite diaphragm for high-performance lithium batteries blocks heat conduction through the functional layer to form a safety buffer zone to prevent further diffusion of heat or current; the reinforcing layer has good strength and toughness to prevent the polyethylene diaphragm from rupturing when the lithium battery is overcharged or short-circuited; at the same time, the nanoblocks can enhance the tensile strength and impact resistance of the polymer diaphragm; and a multilayer composite structure is formed by setting the No. 1 microporous layer, the No. 2 microporous layer, the No. 2 pores and the No. 1 pores to provide a better ion channel for the lithium battery, which helps to improve the distribution and flow of the electrolyte; at the same time, the antibacterial layer can effectively prevent impurities, microorganisms or other corrosive substances in the electrolyte from invading the polyethylene diaphragm, thereby improving the overall performance of the polyethylene diaphragm for lithium batteries.
[0018] 1. The ultra-high molecular polyethylene composite diaphragm for high-performance lithium batteries is provided with a functional layer and a reinforcement layer. The functional layer is a thermally responsive material. When the temperature rises to a certain level, the functional layer can self-repair cracks or expand through a thermal reaction, close the surrounding pores, block the damaged parts, and prevent heat conduction. The functional layers are arranged on both sides of the polyethylene-based film and are located at the core of the polymer diaphragm to form a safety buffer zone to prevent further diffusion of heat or current. The reinforcement layer has good strength and toughness, which effectively prevents the polyethylene diaphragm from rupturing when the lithium battery is overcharged or short-circuited. At the same time, the nanoblocks can enhance the tensile strength and impact resistance of the polymer diaphragm, thereby improving the safety and stability of the polyethylene diaphragm for lithium batteries.
[0019] 2. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries has multiple microporous layers through the arrangement of the No. 1 microporous layer, the No. 2 microporous layer, the No. 2 pores and the No. 1 pores, so that the polyethylene diaphragm has multiple microporous layers to form a multi-layer composite structure, providing a better ion channel for the lithium battery, and through the additional arrangement of several membrane blocks, it is helpful to improve the distribution and flow of the electrolyte, making the ion conduction inside the lithium battery more efficient, and improving the overall performance of the polyethylene diaphragm for lithium batteries;
[0020] 3. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries is provided with an antibacterial layer, which can effectively prevent impurities, microorganisms or other corrosive substances in the electrolyte from invading the polyethylene diaphragm. Equally spaced antibacterial sheets are provided on the antibacterial layer, and the material of the antibacterial sheets is a copper-based film with strong antibacterial properties, which improves the practicality of the antibacterial layer. The equally spaced isolation zones can optimize the distribution of antibacterial components and limit excessive diffusion or loss of antibacterial components, making the antibacterial layer and antibacterial sheets more concentrated or durable, thereby improving the stability of the antibacterial function. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the three-dimensional structure of the polymer membrane of the present invention;
[0022] Figure 2 It is a schematic diagram of the three-dimensional decomposition structure of the present invention;
[0023] Figure 3 It is a schematic diagram of the three-dimensional structure of the functional layer of the present invention;
[0024] Figure 4 This is a schematic diagram of the three-dimensional structure of the polyethylene-based film of the present invention;
[0025] Figure 5 This is a schematic diagram of the three-dimensional structure of the reinforcement layer of the present invention;
[0026] Figure 6 It is a schematic diagram of the three-dimensional structure of the antibacterial layer of the present invention;
[0027] Figure 7 It is a schematic diagram of the three-dimensional structure of the membrane block of the present invention.
[0028] In the figure: 1. polymer membrane; 2. coating; 3. antibacterial layer; 4. microporous layer No. 1; 5. microporous layer No. 2; 6. functional layer; 7. reinforcing layer; 8. polyethylene-based membrane; 9. pore No. 1; 10. membrane block; 11. through hole; 12. pore No. 2; 13. isolation zone; 14. antibacterial sheet; 15. nanoblock. DETAILED DESCRIPTION
[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0030] See also Figure 1-Figure 6 The present invention provides a technical solution: an ultra-high molecular polyethylene composite diaphragm for a high-performance lithium battery, comprising a polymer diaphragm 1 and a No. 1 pore 9, wherein the polymer diaphragm 1 comprises a coating 2, an antibacterial layer 3, a No. 1 microporous layer 4, a No. 2 microporous layer 5, a functional layer 6, a reinforcing layer 7, and a polyethylene base film 8, wherein the inner surface of the coating 2 is provided with an antibacterial layer 3, and a No. 1 microporous layer 4 is provided on a side of the antibacterial layer 3 away from the coating 2, and the No. 1 pores 9 are uniformly distributed on the inner side of the No. 1 microporous layer 4, and the No. 1 microporous layer A second microporous layer 5 is provided on the side away from the antibacterial layer 3, a functional layer 6 is provided on the side of the second microporous layer 5 away from the first microporous layer 4, a reinforcing layer 7 is provided on the side of the functional layer 6 away from the second microporous layer 5, a polyethylene-based film 8 is provided on the side of the reinforcing layer 7 away from the functional layer 6, a plurality of nano-blocks 15 are provided on the surface of the reinforcing layer 7, the material of the functional layer 6 is set to titanium oxide, the material of the reinforcing layer 7 is high-strength glass fiber or polymer composite material, and the material of the nano-blocks 15 is silicon nitride.
[0031] In specific implementation, since the structure of the existing polyethylene diaphragm for lithium batteries is relatively simple and the melting point of polyethylene is relatively low, when the temperature inside the battery rises, the polyethylene diaphragm is prone to melting or shrinking, causing deformation of the diaphragm. The mechanical strength of polyethylene is low and it is easy to break, affecting the stability and safety of the battery. By setting the functional layer 6 and the reinforcement layer 7, the functional layer 6 is a thermally responsive material. When the temperature rises to a certain level, the functional layer 6 will self-repair cracks or expand through a thermosensitive reaction, close the surrounding pores, block the damaged area, and prevent heat conduction. The functional layer 6 is arranged on both sides of the polyethylene base film 8, located at the core position of the polymer diaphragm 1, and can form a safety buffer zone to prevent further diffusion of heat or current. The reinforcement layer 7 has good strength and toughness, which effectively prevents the polyethylene diaphragm from breaking when the lithium battery is overcharged or short-circuited. At the same time, the nanoblocks 15 can enhance the tensile strength and impact resistance of the polymer diaphragm 1, thereby improving the safety and stability of the polyethylene diaphragm for lithium batteries.
[0032] See also Figure 1-Figure 4 and Figure 7The inner sides of the No. 2 microporous layer 5, the functional layer 6, the reinforcing layer 7, and the polyethylene-based film 8 are all provided with through holes 11 distributed at equal intervals, the inner side of the through holes 11 is penetrated by a membrane block 10, and the inner side of the membrane block 10 is provided with a plurality of No. 2 pores 12 distributed in an annular manner, and the pore diameters of the No. 1 pores 9 and the No. 2 microporous layer 5 are both 0.2-0.4 μm.
[0033] In specific implementation, by setting the No. 1 microporous layer 4, the No. 2 microporous layer 5, the No. 2 pore 12 and the No. 1 pore 9, the polyethylene membrane has multiple microporous layers to form a multi-layer composite structure, which provides a better ion channel for the lithium battery, and the additional arrangement of several membrane blocks 10 helps to improve the distribution and flow of the electrolyte, making the ion conduction inside the lithium battery more efficient, and can maintain a low internal resistance during the battery charging and discharging process, thereby improving the overall performance of the polyethylene membrane for lithium batteries, preventing safety accidents of lithium batteries in extreme environments, and thus extending the service life of lithium batteries.
[0034] See also Figure 1 , Figure 2 and Figure 6 An antibacterial sheet 14 and an isolation belt 13 are provided on the surface of the antibacterial layer 3, and the antibacterial sheet 14 and the isolation belt 13 are both distributed in a transverse interval, the thickness of the isolation belt 13 and the antibacterial sheet 14 are both 2-12 μm, and the isolation belt 13 is set to carbon fiber material.
[0035] In specific implementation, since the surface of the polyethylene diaphragm for lithium batteries in contact with the positive and negative electrodes is usually provided with an aluminum oxide coating, but the antibacterial property of the aluminum oxide coating is insufficient, an antibacterial layer 3 can be provided on one side of the coating 2 to effectively prevent impurities, microorganisms or other corrosive substances in the electrolyte from invading the polyethylene diaphragm, and equally spaced antibacterial sheets 14 are provided on the antibacterial layer 3, and the material of the antibacterial sheets 14 is a copper-based film with strong antibacterial properties, thereby improving the practicality of the antibacterial layer 3. The equally spaced isolation zones 13 can optimize the distribution of antibacterial components and limit excessive diffusion or loss of antibacterial components, thereby making the antibacterial layer 3 and the antibacterial sheet 14 more concentrated or durable, thereby improving the stability of the antibacterial function.
[0036] In summary, the functional layer 6 is arranged on both sides of the polyethylene-based film 8, located at the core position of the polymer diaphragm 1, which can form a safety buffer zone to prevent further diffusion of heat or current. The reinforcing layer 7 has good strength and toughness, which can effectively prevent the polyethylene diaphragm from rupturing when the lithium battery is overcharged or short-circuited. At the same time, the nanoblock 15 can enhance the tensile strength and impact resistance of the polymer diaphragm 1. The arrangement of the No. 1 microporous layer 4, the No. 2 microporous layer 5, the No. 2 pore 12 and the No. 1 pore 9 enables the polyethylene diaphragm to have multiple microporous layers to form a multi-layer composite structure, providing a better ion channel for the lithium battery, and the equally spaced isolation belts 13 can optimize the distribution of antibacterial components, and can limit the excessive diffusion or loss of antibacterial components, so that the antibacterial layer 3 and the antibacterial sheet 14 are more concentrated or durable, thereby improving the stability of the antibacterial function. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.
[0037] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. An ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries, comprising a polymer diaphragm (1) and a first pore (9), characterized in that: The polymer membrane (1) comprises a coating (2), an antibacterial layer (3), a first microporous layer (4), a second microporous layer (5), a functional layer (6), a reinforcing layer (7), and a polyethylene-based film (8); the inner surface of the coating (2) is provided with an antibacterial layer (3); a first microporous layer (4) is provided on a side of the antibacterial layer (3) away from the coating (2); and the first pores (9) are uniformly distributed on the inner side of the first microporous layer (4).
2. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries according to claim 1, characterized in that: A second microporous layer (5) is provided on the side of the first microporous layer (4) away from the antibacterial layer (3).
3. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries according to claim 2, characterized in that: A functional layer (6) is provided on the side of the second microporous layer (5) away from the first microporous layer (4).
4. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium batteries according to claim 3, characterized in that: A reinforcing layer (7) is provided on the side of the functional layer (6) away from the second microporous layer (5).
5. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 4, characterized in that: A polyethylene-based film (8) is provided on the side of the reinforcement layer (7) away from the functional layer (6).
6. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 5, characterized in that: The inner sides of the second microporous layer (5), the functional layer (6), the reinforcing layer (7), and the polyethylene-based film (8) are all provided with through holes (11) distributed at equal intervals.
7. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 6, characterized in that: A membrane block (10) penetrates the inner side of the through hole (11).
8. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 7, characterized in that: A plurality of No. 2 pores (12) are distributed in an annular manner on the inner side of the membrane block (10), and a plurality of nano blocks (15) are provided on the surface of the reinforcement layer (7).
9. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 1, characterized in that: An antibacterial sheet (14) and an isolation belt (13) are provided on the surface of the antibacterial layer (3), and the antibacterial sheet (14) and the isolation belt (13) are both distributed in a transversely spaced manner.
10. The ultra-high molecular weight polyethylene composite diaphragm for high-performance lithium battery according to claim 9, characterized in that: The pore sizes of the No. 1 pore (9) and the No. 2 microporous layer (5) are both 0.2-0.4 μm, and the thicknesses of the isolation zone (13) and the antibacterial sheet (14) are both 2-12 μm.