High safety differentiated pore separator and battery

Abstract

The application provides a high-safety differential porosity diaphragm and a battery, wherein the high-safety differential porosity diaphragm comprises a base film, and the base film has a first base layer and a second base layer which are stacked; the first base layer is used for facing the negative plate side of the battery; the second base layer is used for facing the negative plate side of the battery, and the second base layer is stacked with the first base layer; and the porosity density parameter of the first base layer is greater than that of the second base layer. In the high-safety differential porosity diaphragm provided by the application, the base film adopts a double-layer structure, which can effectively improve the structural strength of the base film, and the base film is not easy to be punctured in the process of manufacturing the diaphragm by coating a coating layer and the like and in the use process. The porosity density parameters of the first base layer and the second base layer are different, the diaphragm is not easy to be punctured when the diaphragm is manufactured in the case that the environmental cleanliness is relatively low, and the ability of the diaphragm to keep electrolyte is guaranteed, so that the product yield of the diaphragm is ensured.

Description

Technical Field

[0001] This application relates to the field of battery separator technology, specifically to a high-safety differentiated pore separator and battery. Background Technology

[0002] In related technologies, for batteries such as lithium-ion batteries, a separator is used to separate the positive and negative electrodes, serving both to isolate them and to wet and retain the electrolyte. The separator consists of a base film and a coating applied to its surface. Because the separator needs to provide insulation between the positive and negative electrodes, dust in the environment can easily puncture the separator during the hot-pressing process of the coating onto the base film, leading to insulation failure. Simultaneously, dust can easily clog the micropores on the base film. These micropores are used to retain the electrolyte during battery use; micropore blockage can cause problems such as reduced battery rate performance. In actual production, the separator manufacturing process often requires extremely high environmental cleanliness. Insufficient environmental cleanliness significantly impacts the separator's production yield. Utility Model Content

[0003] The embodiments of this application provide a highly safe differentiated pore membrane and battery, which can improve the technical problem that the yield of membrane production is greatly affected by environmental cleanliness.

[0004] In a first aspect, embodiments of this application provide a highly secure differentiated porous membrane, comprising:

[0005] A base film having a first base layer and a second base layer stacked together; the first base layer is used to cover the negative electrode side of the battery; the second base layer is used to cover the negative electrode side of the battery, and the second base layer is stacked with the first base layer.

[0006] The pore density parameter of the first base layer is greater than that of the second base layer.

[0007] The high-safety differentiated porous separator provided in this application employs a double-layer structure for the base membrane. Compared to the single-layer base membrane solution in related technologies, this effectively improves the structural strength of the base membrane, making it less prone to puncture during the coating and other processes used to manufacture the battery separator, as well as during use. Furthermore, this structural improvement reduces the requirements for cleanliness in the manufacturing environment. Additionally, the pore density parameters of the first and second base layers differ; for example, the pore density of the first base layer can be increased, thereby accommodating more electrolyte and preventing dust from completely clogging the micropores on the base membrane. Therefore, this solution is less prone to puncture even when manufacturing battery separators in environments with relatively low cleanliness, and it ensures the battery separator's ability to retain electrolyte, thus guaranteeing the product yield of the battery separator.

[0008] In one embodiment, the pore density parameter includes at least one of porosity and average micropore diameter. That is, in practical applications, the retention effect of the base film on the electrolyte can be controlled by controlling at least one of the porosity and average micropore diameter of the first and second base layers.

[0009] In one embodiment, the ratio of the porosity of the first base layer to that of the second base layer ranges from 1.1 to 1.8;

[0010] The ratio of the average pore size of the micropores in the first base layer to that in the second base layer ranges from 1 to 8.

[0011] By limiting the ratio of porosity and average micropore diameter of the first and second base layers to a reasonable range, the base film can have higher porosity and pore diameter on the side near the negative electrode of the battery, thereby increasing the electrolyte retention, shortening the lithium ion migration path, and reducing internal resistance. At the same time, the porosity and pore diameter on the side near the positive electrode of the battery are not too small, and the base film can also retain sufficient electrolyte on the side near the positive electrode of the battery, ensuring that the negative electrode of the battery is also fully wetted by the electrolyte.

[0012] In one embodiment, the porosity of the first base layer ranges from 45% to 55%.

[0013] And / or, the average pore size of the micropores in the first substrate ranges from 0.2 μm to 0.8 μm;

[0014] And / or, the porosity of the second base layer ranges from 30% to 40%;

[0015] And / or, the average pore size of the micropores in the second base layer is less than 0.2 μm.

[0016] By specifically defining the porosity and average pore size of the first base layer, the first base layer can retain a larger amount of electrolyte while ensuring sufficient structural strength. Furthermore, by specifically defining the porosity and average pore size of the second base layer, the contact area between the electrolyte and the battery's high-voltage positive electrode is limited, suppressing interfacial side reactions and extending the battery's lifespan under cycle use. The second base layer can also be used to strengthen the structural strength of the first base layer and reduce the possibility of puncture during battery separator manufacturing.

[0017] In one embodiment, the overlapping area is defined on one side where the first base layer and the second base layer are stacked together;

[0018] The thickness of the entire structure formed by the first base layer and the second base layer is defined as the film thickness;

[0019] Wherein, the pore density parameter at the overlapping region is between the pore density parameter of the second base layer on the side away from the first base layer and the pore density parameter of the first base layer on the side away from the second base layer;

[0020] The ratio of the thickness of the overlapping region to the thickness of the film layer is less than or equal to 30%.

[0021] In practical applications, there is an overlapping area between the first and second base layers, which enhances the bonding force at the interface between the first and second base layers, resulting in a tighter connection between them and further reducing the possibility of the battery separator being punctured. This arrangement allows the pore density parameter of the base film to exhibit a gradient-like change in the direction of the stacking of the first and second base layers, avoiding problems such as high ion migration resistance caused by pore density parameters, and ensuring that the battery has good performance, including rate capability.

[0022] In one embodiment, the difference between the thickness of the first base layer and the thickness of the second base layer ranges from 1 μm to 3 μm.

[0023] This design allows the thickness of the first layer to be slightly greater than that of the second layer during the manufacturing process of the base film. While ensuring that the second layer can provide sufficient structural strength for the base film itself, it also enables the base film to have relatively high porosity, average pore size, and other parameters, thereby improving the rate performance of the battery.

[0024] In one embodiment, the high-safety differentiated porosity membrane further includes:

[0025] A coating layered on top of the base film is used to bond the base film to the positive or negative electrode of the battery.

[0026] Multiple connecting particles are protruding and disposed on the surface of the coating away from the base film.

[0027] By adopting the above scheme, based on the coating, after the battery separator is bonded to the positive or negative electrode, the connecting particles can be nested with the battery electrode, thereby improving the connection strength between the battery separator and the battery electrode.

[0028] In one embodiment, the connecting particles are configured as at least partially protruding adhesive polymer protrusions from the coating. This configuration, while the adhesive polymer protrusions are nested within the battery electrode, also utilizes the adhesion between the adhesive polymer protrusions and the battery electrode to further enhance the connection strength between the battery separator and the battery electrode.

[0029] In one embodiment, at least a portion of the connecting particles is embedded within the coating;

[0030] The ratio of the depth of the connecting particles embedded in the coating to the particle size of the connecting particles ranges from 10% to 50%.

[0031] And / or, the particle size of the connecting particles ranges from 0.3 μm to 30 μm;

[0032] And / or, the thickness of the coating is greater than or equal to 1 μm;

[0033] And / or, the ratio of the particle size of the connecting particles to the thickness of the coating ranges from 1.2 to 15.

[0034] The nested arrangement of the connecting particles and the coating helps to ensure the connection strength between the two. On this basis, the size restrictions on the connecting particles themselves, as well as the size restrictions on the matching dimensions of the connecting particles and the coating, help to ensure that there is a good connection effect between the connecting particles and the coating, as well as between the connecting particles and the battery electrodes.

[0035] Secondly, embodiments of this application provide a battery including a highly safe differentiated porous membrane as described above.

[0036] The beneficial effects of the embodiments of this application are as follows:

[0037] In the embodiments of this application, the high-safety differentiated porous separator provided features a double-layer base membrane structure. Compared to the single-layer base membrane solution in related technologies, this effectively improves the structural strength of the base membrane, making it less prone to puncture during the coating and other processes used to manufacture the battery separator, as well as during use. Furthermore, this structural improvement reduces the requirements for cleanliness in the manufacturing environment. Additionally, the pore density parameters of the first and second base layers differ; for example, the pore density of the first base layer can be increased, thereby accommodating more electrolyte and preventing dust from completely clogging the micropores on the base membrane. Therefore, this solution is less prone to puncture even when manufacturing battery separators in environments with relatively low cleanliness, and ensures the battery separator's ability to retain electrolyte, thus guaranteeing the product yield of the battery separator. This addresses the technical problem that separator production yield is significantly affected by environmental cleanliness. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the base film provided in the first embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the base film provided in the second embodiment of this application;

[0041] Figure 3 This is a schematic diagram of the high-safety differentiated pore membrane provided in the first embodiment of this application;

[0042] Figure 4 yes Figure 3 The diagram shows the connection relationship between the high-safety differentiated porous membrane and the electrode.

[0043] Figure 5 This is a schematic diagram of a high-safety differentiated porous membrane provided in the second embodiment of this application.

[0044] Explanation of reference numerals in the attached figures:

[0045] 10. High-safety differentiated porous membrane; 11. Coating; 12. Connecting particles;

[0046] 100. Base film; 110. First layer; 120. Second layer;

[0047] 200, Electrode;

[0048] A. Overlapping area; a. Thickness of the first base layer; b. Thickness of the second base layer; c. Film thickness; d. Depth of the connecting particles embedded in the coating; e. Coating thickness; f. Thickness of the overlapping area. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0050] Reference Figures 1 to 5 As shown, the high-safety differentiated pore membrane 10 provided in the first aspect of this application can be used in conjunction with the positive and negative electrode plates of a battery, thereby enabling its integration into the battery for use. Specifically, refer to... Figure 1As shown, the high-safety differentiated porous membrane 10 includes a base film 100, which includes a first base layer 110 and a second base layer 120 stacked together. The first base layer 110 covers the negative electrode side of the battery. The second base layer 120 covers the positive electrode side of the battery. The negative electrode side of the battery mentioned in this application refers to the side of the stacked structure closest to the negative electrode in a battery integrating the high-safety differentiated porous membrane 10, where the positive electrode, the high-safety differentiated porous membrane 10, and the negative electrode are stacked together. The first base layer 110, when integrated into the battery, is located on the side of the base film 100 closest to the negative electrode, and its projection overlaps with the negative electrode in the stacking direction of the stacked structure; that is, the first base layer 110 covers the negative electrode side mentioned in this application. Similarly, the positive electrode side of the battery refers to the side of the stacked structure closest to the positive electrode. When integrated into a battery, the second base layer 120 is located on the side of the base film 100 close to the positive electrode sheet, and there is a portion of its projection that overlaps with the positive electrode sheet in the stacking direction of the stacked structure, that is, the second base layer 120 mentioned in this application covers the positive electrode sheet side.

[0051] Compared to the single-layer structure in the base film 100, the double-layer structure composed of the first base layer 110 and the second base layer 120 increases the amount of material used in the base film 100, which can improve the structural strength of the base film 100 itself.

[0052] The pore density parameter of the first base layer 110 is greater than that of the second base layer 120. This makes the parameters related to micropores (such as the number of pores and pore size) on the first base layer 110 and the second base layer 120 different. Consequently, the first base layer 110 and the second base layer 120 have different abilities to contain and retain electrolyte when used in a battery.

[0053] Compared to the single-layer base membrane approach used in related technologies, the above solution effectively improves the structural strength of the base membrane 100. The base membrane 100 is less prone to puncture during the coating and other processes used to manufacture the high-safety differentiated porous membrane 10, and during use, thus improving safety. Furthermore, this structural improvement reduces the requirements for cleanliness in the manufacturing environment. Additionally, the pore density parameters of the first base layer 110 and the second base layer 120 differ, resulting in differences in pore size. For example, this can increase the pore density of the first base layer 110, allowing it to hold more electrolyte, and preventing dust from completely clogging the micropores on the base membrane 100. Therefore, even in environments with relatively low cleanliness, the above solution is less prone to puncture when manufacturing the high-safety differentiated porous membrane 10, and ensures the high-safety differentiated porous membrane 10's ability to retain electrolyte, thereby guaranteeing the product yield of the high-safety differentiated porous membrane 10.

[0054] Understandably, this application matches the relative positions between the base film 100 and the battery electrode, limiting the pore density parameter of the base film 100 to be greater on the side closer to the negative electrode than on the side closer to the positive electrode. This adapts to the characteristic of ions migrating from the positive electrode to the negative electrode during battery use. On the side closer to the negative electrode, the electrolyte retention can be increased, the lithium ion migration path can be shortened, and the internal resistance can be reduced; while on the side closer to the positive electrode, the contact area between the electrolyte and the high-voltage positive electrode can be reduced, suppressing interfacial side reactions and extending the battery's lifespan under cycle use.

[0055] Furthermore, the method of combining the first base layer 110 and the second base layer 120 in a stacked manner is simpler in terms of process implementation compared to the scheme of configuring different pore density parameters on both sides of a single membrane layer, thus ensuring product yield.

[0056] The pore density parameters mentioned in this application refer to parameters in the base membrane 100 used to characterize the micropore size, which have a certain impact on the ability of the base membrane 100 to retain electrolyte. Specifically, the pore density parameters include at least one of porosity and average micropore diameter. That is, in practical applications, the electrolyte retention effect of the base membrane 100 can be controlled by controlling at least one of the porosity and average micropore diameter of the first base layer 110 and the second base layer 120.

[0057] By associating specific values ​​of some pore density parameters of the first base layer 110 and the second base layer 120, the base membrane 100 can achieve better performance. In one embodiment, the ratio of the porosity of the first base layer 110 to the second base layer 120 ranges from 1.1 to 1.8, and the ratio of the average pore size of the micropores of the first base layer 110 to the second base layer 120 ranges from 1 to 8.

[0058] Specifically, the porosity ratio of the first base layer 110 to the second base layer 120 ranges from, for example, 1.1 to 1.2, 1.2 to 1.3, 1.3 to 1.4, 1.4 to 1.5, 1.5 to 1.6, 1.6 to 1.7, and 1.7 to 1.8. The average pore size ratio of the first base layer 110 to the second base layer 120 ranges from, for example, 1 to 2, 2 to 3, 3 to 4, 4 to 5, 5 to 6, 6 to 7, and 7 to 8.

[0059] Understandably, if the porosity difference between the first base layer 110 and the second base layer 120 is small, the structural adaptation of the base film 100 on the side near the positive electrode and the side near the negative electrode can be almost ignored, and the change in the pore density parameters on both sides of the base film 100 has little impact on the battery performance. If the porosity or average pore size difference between the first base layer 110 and the second base layer 120 is too large, it is easy to cause insufficient structural strength of the first base layer 110 due to too many micropores or too large average pore size, or the second base layer 120 may have too few micropores or too small average pore size, thus limiting the battery rate performance.

[0060] By adopting the above scheme, by limiting the ratio of porosity and average micropore diameter of the first base layer 110 and the second base layer 120 to a reasonable range, the base film 100 can have a higher porosity and pore diameter on the side near the negative electrode of the battery, so as to increase the electrolyte retention, shorten the lithium ion migration path and reduce the internal resistance. At the same time, the porosity and pore diameter of the base film 100 on the side near the positive electrode of the battery are not too small, and the base film 100 on the side near the positive electrode of the battery can also maintain sufficient electrolyte, so as to ensure that the negative electrode of the battery can also be fully wetted by electrolyte.

[0061] In a more specific embodiment, the porosity of the first base layer 110 ranges from 45% to 55%, and the average pore size of the micropores in the first base layer 110 ranges from 0.2 μm to 0.8 μm. By specifically defining the porosity and average pore size of the first base layer 110, while ensuring sufficient structural strength, the first base layer 110 can retain more electrolyte, thereby improving the wetting effect of the negative electrode adjacent to the first base layer 110.

[0062] Specifically, the porosity of the first base layer 110 ranges from, for example, 45% to 46%, 46% to 47%, 47% to 48%, 48% to 49%, 49% to 50%, 51% to 52%, 52% to 53%, 53% to 54%, and 54% to 55%. The average pore size of the micropores in the first base layer 110 ranges from, for example, 0.2 μm to 0.3 μm, 0.3 μm to 0.4 μm, 0.4 μm to 0.5 μm, 0.5 μm to 0.6 μm, 0.6 μm to 0.7 μm, and 0.7 μm to 0.8 μm.

[0063] Accordingly, the porosity of the second base layer 120 can be specifically configured to range from 30% to 40%, and the average pore size of the micropores in the second base layer 120 is less than 0.2 μm. By specifically defining the porosity and average pore size of the second base layer 120, the contact area between the electrolyte and the battery positive electrode with a higher voltage is limited, interfacial side reactions are suppressed, and the battery life under cycle use is extended. Furthermore, the second base layer 120 can be used to strengthen the structural strength of the first base layer 110 and reduce the possibility of puncture during the manufacturing process of the high-safety differentiated porous membrane 10.

[0064] Specifically, the porosity range of the first base layer 110 is, for example, 30% to 31%, 31% to 32%, 32% to 33%, 33% to 34%, 34% to 35%, 35% to 36%, 36% to 37%, 37% to 38%, 38% to 39%, 39% to 40%, etc.

[0065] In some specific implementation plans, refer to Figure 1 As shown, the difference between the thickness 'a' of the first base layer and the thickness 'b' of the second base layer can be limited to a range of 1 μm to 3 μm. This configuration ensures that the thickness 'a' of the first base layer is slightly greater than that of the second base layer 120 during the manufacturing process of the base film 100. While ensuring that the second base layer 120 can provide sufficient structural strength for the base film 100 itself, this configuration also allows the base film 100 to have relatively high porosity, average pore size, and other parameters, thereby improving the rate performance of the battery.

[0066] Specifically, the range of the difference between the thickness 'a' of the first base layer and the thickness 'b' of the second base layer is, for example, 1μm to 1.2μm, 1.2μm to 1.4μm, 1.4μm to 1.6μm, 1.6μm to 1.8μm, 1.8μm to 2.0μm, 2.0μm to 2.2μm, 2.2μm to 2.4μm, 2.4μm to 2.6μm, 2.6μm to 2.8μm, 2.8μm to 3μm, etc.

[0067] Reference Figure 2As shown, in one embodiment, the overlapping area A is defined on one side where the first base layer 110 and the second base layer 120 are stacked. That is, when the first base layer 110 and the second base layer 120 are stacked, a force can be applied to the first base layer 110 and the second base layer 120 to allow the first base layer 110, which has a larger pore density parameter, and the second base layer 120, which has a smaller pore density parameter, to overlap each other in space, so that the first base layer 110 and the second base layer 120 are more tightly bonded. As an example, in a specific application, the material particles used to manufacture the first base layer 110 and the second base layer 120 can be formed into the first base layer 110 and the second base layer 120 respectively through processes such as melting, extrusion, heat treatment, and stretching. Then, the first base layer 110 and the second base layer 120 are stacked and pressed together at a hot press to form the aforementioned overlapping area A.

[0068] In practical applications, there is an overlapping area A between the first base layer 110 and the second base layer 120, which can enhance the magnitude of the interaction force between the first base layer 110 and the second base layer 120 and make the first base layer 110 and the second base layer 120 more tightly connected, further reducing the possibility of the high-safety differentiated porous membrane 10 being punctured.

[0069] Certain dimensional limitations on the overlapping region A also contribute to improving the performance of the base film 100. For example, refer to... Figure 2 As shown, the thickness of the whole formed by the first base layer 110 and the second base layer 120 can be defined as the film thickness c; wherein, the ratio of the thickness f of the overlapping area to the film thickness c is less than or equal to 30%.

[0070] In this application, the concept related to "thickness" refers to the dimensions of each corresponding structure in the stacking direction (shown as the vertical direction in the accompanying drawings) of the first base layer 110 and the second base layer 120 after they are stacked. It is understood that when the ratio of the thickness f of the overlapping region to the film thickness c is small, the volume of the overlapping region A accounts for a small proportion of the overall volume formed by the first base layer 110 and the second base layer 120, and the presence of the overlapping region A has a small effect on improving the bonding force between the first base layer 110 and the second base layer 120. When the ratio of the thickness f of the overlapping region to the film thickness c is large, the volume of the overlapping region A accounts for a large proportion of the overall volume formed by the first base layer 110 and the second base layer 120, and the presence of the overlapping region A inevitably affects the variation trend of parameters such as porosity and average micropore diameter of the base film 100 from the side closer to the negative electrode to the side closer to the positive electrode, thus weakening the impact of the difference in pore density parameters between the first base film 100 and the second base film 100 on the overall performance of the base film 100. Therefore, by limiting the ratio of the thickness f of the overlapping area to the film thickness c, the base film 100 with the first base layer 110 and the second base layer 120 can better play its role in improving the rate performance of the battery while ensuring the connection strength between the first base layer 110 and the second base layer 120.

[0071] In a more specific embodiment, the pore density parameter at the overlapping region A can be limited to between the pore density parameter of the second base layer 120 on the side away from the first base layer 110 and the pore density parameter of the first base layer 110 on the side away from the second base layer 120. This arrangement allows the pore density parameter of the base film 100 to have a gradient-like change in the stacking direction of the first base layer 110 and the second base layer 120, avoiding problems such as high ion migration resistance caused by pore density parameter, and ensuring that the battery has good performance, including rate performance.

[0072] The materials of the first base layer 110 and the second base layer 120 are not specifically limited here. As an example, the materials of the first base layer 110 and the second base layer 120 may include at least one of polyethylene and polypropylene. The materials of the first base layer 110 and the second base layer 120 may be the same or different, and the manufacturing processes may be the same or different, as long as the pore density parameters of the first base layer 110 and the second base layer 120 meet the aforementioned limitations after the base film 100 is manufactured. For example, the same polyethylene particles can be melted, extruded, heat-treated, and stretched. By controlling parameters such as the air permeability during the process, first base layer 110 and second base layer 120 with different micropore sizes can be formed respectively. After stacking the first base layer 110 and the second base layer 120 and pressing them in a hot press, the base film 100 is obtained.

[0073] As a specific plan, refer to Figure 3 and Figure 4 As shown, the high-safety differentiated porous separator 10 further includes a coating 11 and connecting particles 12. The coating 11 is stacked on top of the base film 100 to bond the base film 100 to the electrode 200 of the battery (specifically, a positive or negative electrode). The coating 11 is made of, for example, an adhesive material, meaning the base film 100 can be bonded to the positive or negative electrode of the battery via the coating 11. More specifically, the coating 11 can be provided on one side surface of the base film 100 so that the base film 100 can be bonded to the positive or negative electrode. Alternatively, the coating 11 can be provided on both opposite sides of the base film 100, for example, on both the first base layer 110 and the second base layer 120, so that the first base layer 110 can be connected to the negative electrode through the coating 11 on its surface, and the second base layer 120 can be connected to the positive electrode through the coating 11 on its surface. The coating 11 can be primarily made of inorganic materials, such as at least one selected from SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, and SiC. It should be noted that, depending on specific application requirements, the coating 11 can also be primarily made of organic materials, or a mixture of organic and inorganic materials. The materials used in the coating 11 are not limited here.

[0074] Multiple connecting particles 12 protrude from the surface of the coating 11 on the side away from the base film 100, as shown in the figure. Figure 4 As shown, since the connecting particles 12 protrude from the coating 11, during the process of bonding the high-safety differentiated porous membrane 10 to the electrode 200, the connecting particles 12 can be at least partially embedded with the electrode 200 by applying pressure to the high-safety differentiated porous membrane 10 and the electrode.

[0075] By adopting the above scheme, based on the coating 11, after the high-safety differentiated porous membrane 10 is combined with the positive or negative electrode of the battery, the connecting particles 12 can be nested with the battery electrode, which improves the connection strength between the high-safety differentiated porous membrane 10 and the battery electrode. The improved connection strength also allows the electrode 200 to absorb the stress on the high-safety differentiated porous membrane 10, thereby reducing the possibility of the high-safety differentiated porous membrane 10 being punctured during use.

[0076] In one embodiment, reference is made to Figure 5 As shown, at least a portion of the connecting particle 12 is embedded within the coating 11, meaning that the connecting particle 12 is also nested within the coating 11. This nested arrangement of the connecting particle 12 and the coating 11 helps to ensure the connection strength between them.

[0077] Based on this, the size limitations of the connecting particle 12 itself, as well as the size limitations of the fit between the connecting particle 12 and the coating 11, help to ensure that there is a good connection effect between the connecting particle 12 and the coating 11, and between the connecting particle 12 and the battery electrode.

[0078] For example, the ratio of the depth d of the connecting particles embedded in the coating to the particle size of the connecting particles 12 can be limited to a range of 10% to 50%, such as 10% to 15%, 15% to 20%, 20% to 25%, 25% to 30%, 30% to 35%, 35% to 40%, 40% to 45%, 45% to 50%, etc. This arrangement ensures that the connecting particles 12 can protrude sufficiently from the coating 11 to connect with the battery electrode, while also ensuring that a sufficient portion of the connecting particles 12 is embedded within the coating 11, thereby comprehensively ensuring the connection strength between the high-safety differentiated porous membrane 10 and the electrode.

[0079] Considering that the thickness e of the coating is often matched with the thickness of the base film 100, i.e. the thickness e of the coating is limited, the particle size of the connecting particles 12 can be limited to a range of 0.3 μm to 30 μm, so that the connecting particles 12 can be partially embedded in the coating 11 and partially protrude from the coating 11.

[0080] As an example, refer to Figure 5 As shown, the coating thickness e is, for example, greater than or equal to 1 μm.

[0081] More specifically, the ratio of the particle size of the connecting particles 12 to the coating thickness e can be limited to a range of 1.2 to 15. For example, the ratio of the particle size of the connecting particles 12 to the coating thickness e can be 1.2 to 3, 3 to 5, 5 to 7, 7 to 9, 9 to 11, 11 to 13, 13 to 15, etc. This setting can avoid the connecting particles 12 from directly contacting the base film 100 due to excessively large connecting particles 12 and excessively thin coating 11, and prevent the connecting particles 12 from clogging or damaging the micropores on the base film 100.

[0082] As a specific example, refer to Figure 5 As shown, the connecting particles 12 are configured, for example, as adhesive polymer protrusions that at least partially protrude from the coating 11. This configuration, while the adhesive polymer protrusions are nested with the battery electrode, also utilizes the adhesion between the adhesive polymer protrusions and the battery electrode to further enhance the connection strength between the high-safety differentiated porous separator 10 and the battery electrode. As an example, the material of the adhesive polymer protrusions is, for example, at least one of ethylene polymers, propylene polymers, amide polymers, epoxy polymers, and cellulose polymers.

[0083] It is understood that the above is only an example of a specific implementation scheme for the connecting particle 12. In actual applications, the connecting particle 12 does not necessarily have to be adhesive. For example, the connecting particle 12 can be made of a non-adhesive polymer material. The non-adhesive polymer material can be at least one of vinyl monomer unit copolymers, alkenylamine monomer unit copolymers, acrylate monomer unit copolymers, methacrylate monomer unit copolymers, vinyl sulfonic acid monomer unit copolymers, and vinyl acetate monomer unit copolymers. In this case, the connecting particle 12, through its nesting arrangement with the battery electrode, also has the function of improving the connection strength between the electrode and the high-safety differentiated porous membrane 10.

[0084] For example, a scheme can be adopted in which some connecting particles 12 are adhesive polymer protrusions, and other connecting particles 12 are non-adhesive and embedded in the coating 11.

[0085] Specifically, in the process of manufacturing the high-safety differentiated porous membrane 10, inorganic particles, viscous polymer particles, and non-viscous polymer particles are mixed and stirred with a solvent (e.g., water) to obtain a slurry. This slurry is then coated onto one side or opposite sides of the aforementioned base membrane 100, and after drying, the high-safety differentiated porous membrane 10 of this application is obtained. Taking the process of coating the slurry onto opposite sides of the aforementioned base membrane 100 as an example, after coating and drying the slurry on the surface of the base membrane 100, the formed membrane layer can be observed using a microscope or similar equipment. This ensures that at least some viscous polymer particles or some non-viscous polymer particles protrude from the surface of the formed coating, thus forming the aforementioned connecting particles 12. This allows for subsequent intercalation of the connecting particles 12 with the battery electrode, thereby improving the connection strength between the battery electrode and the high-safety differentiated porous membrane 10.

[0086] Secondly, embodiments of this application also provide a battery including the aforementioned high-safety differentiated pore membrane 10. This battery possesses the beneficial effects of the aforementioned high-safety differentiated pore membrane 10, which will not be elaborated further here.

[0087] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A high-safety differentiated porous membrane, characterized in that, include: A base film (100) has a first base layer (110) and a second base layer (120) stacked together; the first base layer (110) is used to cover the negative electrode side of the battery; the second base layer (120) is used to cover the negative electrode side of the battery, and the second base layer (120) is stacked with the first base layer (110). The pore density parameter of the first base layer (110) is greater than that of the second base layer (120).

2. The high-safety differentiated porous membrane according to claim 1, characterized in that, The pore density parameter includes at least one of porosity and average micropore diameter.

3. The high-safety differentiated porous membrane according to claim 2, characterized in that, The ratio of the porosity of the first base layer (110) to the second base layer (120) ranges from 1.1 to 1.8; The ratio of the average pore size of the micropores in the first base layer (110) to the average pore size in the second base layer (120) ranges from 1 to 8.

4. The high-safety differentiated porous membrane according to claim 3, characterized in that, The porosity of the first base layer (110) ranges from 45% to 55%. And / or, the average pore size of the micropores in the first base layer (110) ranges from 0.2 μm to 0.8 μm; And / or, the porosity of the second base layer (120) ranges from 30% to 40%; And / or, the average pore size of the micropores in the second base layer (120) is less than 0.2 μm.

5. The high-safety differentiated porous membrane according to any one of claims 1 to 4, characterized in that, The overlapping area (A) is defined on one side where the first base layer (110) and the second base layer (120) are stacked together; The thickness of the entire structure consisting of the first base layer (110) and the second base layer (120) is defined as the film thickness (c); The pore density parameter at the overlapping region (A) is between the pore density parameter of the second base layer (120) on the side away from the first base layer (110) and the pore density parameter of the first base layer (110) on the side away from the second base layer (120). The ratio of the thickness (f) of the overlapping region to the thickness (c) of the film layer is less than or equal to 30%.

6. The high-safety differentiated porous membrane according to any one of claims 1 to 4, characterized in that, The difference between the thickness (a) of the first base layer and the thickness (b) of the second base layer ranges from 1 μm to 3 μm.

7. The high-safety differentiated porous membrane according to any one of claims 1 to 4, characterized in that, Also includes: A coating (11) is stacked with the base film (100) to bond the base film (100) to the positive or negative electrode of the battery. Multiple connecting particles (12) are protruding from the surface of the coating (11) on the side away from the base film (100).

8. The high-safety differentiated porous membrane according to claim 7, characterized in that, The connecting particles (12) are configured as at least partially protruding from the adhesive polymer protrusions provided by the coating (11).

9. The high-safety differentiated porous membrane according to claim 7, characterized in that, At least a portion of the connecting particles (12) are embedded within the coating (11); The ratio of the depth of the connecting particle (12) embedded in the coating (11) to the particle size of the connecting particle (12) ranges from 10% to 50%. And / or, the particle size of the connecting particles (12) ranges from 0.3 μm to 30 μm; And / or, the thickness (e) of the coating is greater than or equal to 1 μm; And / or, the ratio of the particle size of the connecting particles (12) to the thickness (e) of the coating ranges from 1.2 to 15.

10. A battery, characterized in that, Including the high-safety differentiated porous membrane (10) as described in any one of claims 1 to 9.

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