Diaphragm, battery and electronic device

Abstract

The utility model discloses a diaphragm, battery and electronic equipment relates to battery technical field, diaphragm includes: a plurality of base membrane, a plurality of base membrane along the thickness direction of diaphragm overlaid, along the thickness direction of diaphragm, diaphragm has opposite first side and second side, the first side is the positive pole side of diaphragm, the second side is the negative pole side of diaphragm, the first side is the positive pole side of diaphragm, and the second side is the negative pole side of diaphragm. From the positive electrode side to the negative electrode side, the tortuosity of the plurality of base films increases in sequence. Therefore, the tortuosity of the plurality of base membranes is sequentially increased from the positive electrode side to the negative electrode side, so that the tortuosity of the base membrane close to the positive electrode side is relatively small, rapid deintercalation of ions is facilitated, the tortuosity of the base membrane close to the negative electrode side is relatively large, and the safe puncture performance of the diaphragm is improved; therefore, the quick charging capacity of the battery can be improved and the risk that dendritic crystals pierce the diaphragm is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field especially is related to a diaphragm, battery and electronic equipment. BACKGROUND

[0002] In the related art, the user's requirement for the battery fast charging is higher and higher, therefore, the diaphragm needs to be made thinner and thinner, but the thinner the thickness of the diaphragm is, the greater the risk of dendrite puncturing the diaphragm is, and the dendrite puncturing the diaphragm will cause the battery short circuit, seriously affecting the use safety of the battery, therefore, how to improve the diaphragm to improve the battery fast charging ability and reduce the risk of dendrite puncturing the diaphragm has become a technical problem to be solved at present. SUMMARY

[0003] The utility model aims at at least one of the technical problems existing in the prior art. To this end, one purpose of the utility model is to provide a diaphragm, which can improve the battery fast charging ability and reduce the risk of dendrite puncturing the diaphragm.

[0004] The utility model further provides a battery.

[0005] The utility model further provides an electronic equipment.

[0006] According to the diaphragm of the utility model, the tortuosity of the plurality of base films is sequentially increased from the positive electrode side to the negative electrode side, so that the tortuosity of the base film close to the positive electrode side is relatively small, which is beneficial to the rapid de-embedding of ions, and the tortuosity of the base film close to the negative electrode side is relatively large, which is beneficial to improving the safe puncture performance of the diaphragm, so that the battery fast charging ability can be improved and the risk of dendrite puncturing the diaphragm can be reduced.

[0007] According to the diaphragm of the utility model, the tortuosity of the plurality of base films is sequentially increased from the positive electrode side to the negative electrode side, so that the tortuosity of the base film close to the positive electrode side is relatively small, which is beneficial to the rapid de-embedding of ions, and the tortuosity of the base film close to the negative electrode side is relatively large, which is beneficial to improving the safe puncture performance of the diaphragm, so that the battery fast charging ability can be improved and the risk of dendrite puncturing the diaphragm can be reduced.

[0008] In some examples of the utility model, the tortuosity of the plurality of base films is increased in equal difference or non-equal difference from the positive electrode side to the negative electrode side.

[0009] In some examples of the utility model, the plurality of base films are divided into a first group of films and a second group of films, the first group of films and the second group of films are stacked along the thickness direction of the diaphragm and each include at least one base film, wherein the side of the first group of films away from the second group of films is the positive electrode side, the side of the second group of films away from the first group of films is the negative electrode side, the tortuosity of the base film of the first group of films is A, and the relationship formula 1≤A≤8 is met.

[0010] In some examples of the present application, the tortuosity of the base film of the second group of film groups is B, satisfying the relationship: 1 < B ≤ 20.

[0011] In some examples of the present application, the molecular weight of the plurality of base films decreases in turn from the positive electrode side to the negative electrode side, so that the tortuosity of the plurality of base films increases in turn.

[0012] In some examples of the present application, the thickness of the base film is C, satisfying the relationship: 0.1 μm ≤ C ≤ 20 μm; and / or, the material of the base film is PP or PE.

[0013] In some examples of the present application, the molecular weight of the base film is D, satisfying the relationship: 500,000 ≤ D ≤ 1,000,000; and / or, the gel particle melt index of the base film is E, satisfying the relationship: 0.1 g / 10 min ≤ E ≤ 5.0 g / 10 min.

[0014] In some examples of the present application, the pore size of the base film is F, satisfying the relationship: 20 nm ≤ F ≤ 200 nm; and / or, the number of the base films is G, satisfying the relationship: 2 ≤ G ≤ 10; and / or, the thickness of the separator is H, satisfying the relationship: 3 μm ≤ H ≤ 20 μm.

[0015] The battery according to the present application comprises an electrode assembly, wherein the electrode assembly comprises a first electrode sheet, a separator and a second electrode sheet, the separator is the above-mentioned separator, and the first electrode sheet, the separator and the second electrode sheet are cooperatively assembled to form the electrode assembly.

[0016] The electronic device according to the present application comprises the above-mentioned battery.

[0017] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, taken in conjunction with the accompanying drawings, in which:

[0019] Figure 1 is a schematic view of the separator according to the embodiments of the present application.

[0020] REFERENCE NUMERALS

[0021] Separator 100;

[0022] Base film 10;

[0023] First side 20; positive electrode side 21;

[0024] second side 30; negative electrode side 31;

[0025] first group of membrane groups 40; second group of membrane groups 50. DETAILED DESCRIPTION

[0026] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numbers represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0027] Reference will be made to Figure 1 The membrane 100 according to the embodiments of the present application is described below.

[0028] As shown in Figure 1 The membrane 100 according to the embodiments of the present application comprises a plurality of base films 10.

[0029] Among them, along the thickness direction of the membrane 100 (i.e. Figure 1 Z direction shown in the figure), the plurality of base films 10 are stacked, and along the thickness direction of the membrane 100 (i.e. Figure 1 Z direction shown in the figure), the membrane 100 has opposite first side 20 and second side 30, wherein the first side 20 is the positive electrode side 21 of the membrane 100, and the second side 30 is the negative electrode side 31 of the membrane 100, specifically, the first side 20 is the side of the membrane 100 close to the positive electrode tab, and the second side 30 is the side of the membrane 100 close to the negative electrode tab.

[0030] Along the thickness direction of the membrane 100 (i.e. Figure 1 Z direction shown in the figure), and from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the plurality of base films 10 increases in turn. The tortuosity is the ratio of the average length of the effective capillary in the membrane 100 (i.e. the actual path of ion transmission) to the thickness of the membrane 100. The tortuosity can be used to characterize the micro-pore structure of the porous material such as the membrane 100, which can reflect the permeability of the membrane 100, and be used to describe the difficulty of ion transmission through the membrane 100.

[0031] It should be noted that when assembling the membrane 100 proposed in the present application with the tab, the first side 20 of the membrane 100 is arranged towards the positive electrode tab, and the second side 30 of the membrane 100 is arranged towards the negative electrode tab, and since along the thickness direction of the membrane 100 (i.e. Figure 1As shown in the Z direction), and from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the plurality of base films 10 is sequentially increased, so that the tortuosity of the base film 10 closer to the first side 20 is smaller, and the base film 10 closer to the first side 20 is more easily penetrated by ions, which is beneficial to the rapid disengagement of ions, can improve the fast charging capability of the battery, and the tortuosity of the base film 10 closer to the second side 30 is larger, so that the base film 10 closer to the second side 30 is less likely to be pierced by dendrites, which is beneficial to improve the safety piercing performance of the diaphragm 100.

[0032] Therefore, by sequentially increasing the tortuosity of the plurality of base films 10 from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the base film 10 close to the positive electrode side 21 is relatively small, which is beneficial to the rapid disengagement of ions, and the tortuosity of the base film 10 close to the negative electrode side 31 is relatively large, which is beneficial to improve the safety piercing performance of the diaphragm 100, thereby improving the fast charging capability of the battery and reducing the risk of dendrite piercing the diaphragm 100.

[0033] In some embodiments of the present application, along the thickness direction of the diaphragm 100 (i.e. Figure 1 the Z direction shown), and from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the plurality of base films 10 is increased in an arithmetic progression. For the tortuosity of the plurality of base films 10 to increase in an arithmetic progression, it can be understood that from the positive electrode side 21 to the negative electrode side 31, each base film 10 is increased by the same tortuosity compared to the previous one. Such a setting can make the tortuosity of the plurality of base films 10 increase regularly, which can improve the fast charging capability of the battery and reduce the risk of dendrite piercing the diaphragm 100.

[0034] Alternatively, along the thickness direction of the diaphragm 100 (i.e. Figure 1 the Z direction shown), and from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the plurality of base films 10 is increased in a non-arithmetic progression. For the tortuosity of the plurality of base films 10 to increase in a non-arithmetic progression, it can be understood that from the positive electrode side 21 to the negative electrode side 31, each base film 10 is increased by an irregular tortuosity compared to the previous one. Such a setting can improve the fast charging capability of the battery and reduce the risk of dendrite piercing the diaphragm 100, and is beneficial to reduce the manufacturing difficulty of the diaphragm 100.

[0035] In some embodiments of the present application, as shown in Figure 1 the plurality of base films 10 are divided into a first group of films 40 and a second group of films 50, the first group of films 40 and the second group of films 50 are stacked along the thickness direction of the diaphragm 100 (i.e. Figure 1 the Z direction shown), and the first group of films 40 includes at least one base film 10, that is, the first group of films 40 can include one base film 10, or the first group of films 40 can also include a plurality of base films 10, and the second group of films 50 includes at least one base film 10, that is, the second group of films 50 can include one base film 10, or the second group of films 50 can also include a plurality of base films 10.

[0036] The side of the first group of membrane groups 40 away from the second group of membrane groups 50 is the positive electrode side 21, that is, the side of the first group of membrane groups 40 away from the second group of membrane groups is the first side 20, and the side of the second group of membrane groups 50 away from the first group of membrane groups 40 is the negative electrode side 31, that is, the side of the second group of membrane groups 50 away from the first group of membrane groups 40 is the second side 30.

[0037] The tortuosity of the base film 10 of the first group of membrane groups 40 is A, which can satisfy the relationship 1≤A≤8, that is, the tortuosity A of the base film 10 of the first group of membrane groups 40 can be any value between 1 and 8, for example, but not limited to, 1, 4, 8, etc. Such a setting can make the tortuosity of the base film 10 of the first group of membrane groups 40 reasonable, and can make the tortuosity of the base film 10 of the first group of membrane groups 40 relatively small, so that the base film 10 of the first group of membrane groups 40 can be more easily penetrated by ions, which is beneficial to the rapid disinsertion of ions and can improve the fast charging capability of the battery.

[0038] In some embodiments of the present application, the tortuosity of the base film 10 of the second group of membrane groups 50 is B, which can satisfy the relationship 1

[0039] In some embodiments of the present application, along the thickness direction (i.e. the Z direction shown in the figure) of the diaphragm 100, and from the positive electrode side 21 to the negative electrode side 31, the molecular weight of the plurality of base films 10 decreases in turn, so that the tortuosity of the plurality of base films 10 increases in turn. It should be noted that the tortuosity of the base film 10 can be controlled by the molecular weight of the base film 10, specifically, the molecular weight of the plurality of base films 10 is set to decrease in turn from the positive electrode side 21 to the negative electrode side 31, and at the same stretching ratio, the base film 10 with a larger molecular weight has a lower tortuosity, and the base film 10 with a smaller molecular weight has a higher tortuosity. Figure 1 By setting the plurality of base films 10 to decrease in turn from the positive electrode side 21 to the negative electrode side 31, the molecular weight of the plurality of base films 10 can be reliably controlled, so that the diaphragm 100 meeting the requirements can be reliably produced, which is beneficial to reducing the production difficulty of the diaphragm 100 and improving the yield.

[0040] By setting the plurality of base films 10 to decrease in turn from the positive electrode side 21 to the negative electrode side 31, the molecular weight of the plurality of base films 10 can be reliably controlled, so that the diaphragm 100 meeting the requirements can be reliably produced, which is beneficial to reducing the production difficulty of the diaphragm 100 and improving the yield.

[0041] In some embodiments of the present application, as shown in Figure 1 The thickness of the base film 10 is C, which satisfies the relationship: 0.1 μm≤C≤20 μm, and / or the material of the base film 10 is PP or PE.

[0042] The thickness C of the base film 10 can satisfy the relationship: 0.1 μm≤C≤20 μm, that is, the thickness C of the base film 10 can be any value between 0.1 μm and 20 μm, for example, the thickness C of the base film 10 can be but not limited to 0.1 μm, 1 μm, 5 μm, 10 μm, 20 μm, etc. Such a setting can make the thickness C of the base film 10 reasonable, can take into account the charging rate and use safety, and can make the diaphragm 100 thinner, which will not occupy too much space, and is conducive to improving the capacity of the battery.

[0043] The material of the base film 10 can be PP, which is a kind of non-toxic, odorless, tasteless, milky white high crystalline polymer. The PP material has high high-temperature resistance, low density, high melting point and closed pore temperature, good chemical stability, thermal stability and mechanical stability. By configuring the material of the base film 10 as PP material, higher safety and stability can be provided, and at the same time the weight of the battery can be reduced.

[0044] Alternatively, the material of the base film 10 can be PE, which is a kind of thermoplastic resin prepared by polymerization of ethylene monomer. The PE material has good mechanical strength and good chemical stability, and the cost of the PE material is relatively low and the processing range is relatively wide. By configuring the material of the base film 10 as PE material, the cost can be reduced while having reliable safety and stability.

[0045] In some embodiments of the present application, the molecular weight of the base film 10 is D, which satisfies the relationship: 500,000≤D≤1,000,000; and / or the gel particle melt index of the base film 10 is E, which satisfies the relationship: 0.1 g / 10 min≤E≤5.0 g / 10 min.

[0046] The molecular weight D of the base film 10 can satisfy the relationship: 500,000≤D≤1,000,000, that is, the molecular weight D of the base film 10 can be any value between 500,000 and 1,000,000, for example, the molecular weight D of the base film 10 can be but not limited to 500,000, 750,000, 1,000,000, etc. Such a setting can make the molecular weight D of the base film 10 reasonable, can make the diaphragm 100 have stable physical and chemical properties, and can provide better battery safety, cycle performance and charge-discharge efficiency.

[0047] The gel particle melt index E of the base film 10 can satisfy the relationship: 0.1 g / 10 min≤E≤5.0 g / 10 min, that is, the gel particle melt index E of the base film 10 can be any value between 0.1 g / 10 min and 5.0 g / 10 min, for example, the gel particle melt index E of the base film 10 can be, but is not limited to, 0.1 g / 10 min, 1 g / 10 min, 3.0 g / 10 min, 5.0 g / 10 min, etc. Such setting can make the gel particle melt index E of the base film 10 reasonable, and can make the separator 100 have good fluidity and processability during processing.

[0048] In some embodiments of the utility model, the pore size of the base film 10 is F, which satisfies the relationship: 20 nm≤F≤200 nm; and / or, the number of the base film 10 is G, which satisfies the relationship: 2≤G≤10; and / or, the thickness of the separator 100 is H, which satisfies the relationship: 3 μm≤H≤20 μm.

[0049] The pore size F of the base film 10 can satisfy the relationship: 20 nm≤F≤200 nm, that is, the pore size F of the base film 10 can be any value between 20 nm and 200 nm, for example, the pore size F of the base film 10 can be, but is not limited to, 20 nm, 50 nm, 100 nm, 200 nm, etc. Such setting can make the pore size F of the base film 10 reasonable, can reliably reduce the risk of short circuit of the positive and negative electrodes of the battery, and can improve the voltage consistency of the battery.

[0050] The number G of the base film 10 can satisfy the relationship: 2≤G≤10, that is, the number G of the base film 10 can be any value between 2 and 10, for example, the number G of the base film 10 can be, but is not limited to, 2, 5, 10, etc. Such setting can make the number of the base film 10 reasonable, can take into account the fast charging capability and safety puncture performance of the battery, and can make the separator 100 have a reasonable thickness, which can reduce the production difficulty of the separator 100.

[0051] As shown in FIG. 1, the separator 100 can include a base film 10 and a plurality of microporous films 20. Figure 1 The thickness H of the separator 100 can satisfy the relationship: 3 μm≤H≤20 μm, that is, the thickness H of the separator 100 can be any value between 3 μm and 20 μm, for example, the thickness H of the separator 100 can be, but is not limited to, 3 μm, 10 μm, 20 μm, etc. Such setting can make the thickness of the separator 100 reasonable, can take into account the charging rate and use safety, and can make the separator 100 relatively thin, which will not occupy too much space, and is conducive to improving the capacity of the battery.

[0052] As some embodiments of the present application, the diaphragm 100 proposed in the present application can be made by the following steps: first step, flow casting film forming, including stirring raw materials with different molecular weights respectively, passing through different twin-screw extruders, co-extruding different melts by using a co-extrusion die to form a multi-layer structure melt, and drawing the multi-layer structure flow casting film at a preset flow casting speed (for example, 30 m / min-200 m / min) and a preset cooling temperature (for example, 40℃-120℃).

[0053] Second step, heat treatment, including making the multi-layer structure flow casting film obtained in the first step undergo heat treatment at a first preset temperature (for example, 120℃-150℃) for a first preset time (for example, 5 min-60 min), and cooling at room temperature for a second preset time (for example, more than one hour) after the reaction is completed.

[0054] Third step, asynchronous bidirectional stretching, first longitudinal and then transverse stretching, respectively stretching by a preset multiple (for example, 5 times-15 times) at a first preset temperature (for example, 50℃-130℃) between the first preset temperature, to obtain a stretched film (5μm-60μm).

[0055] Fourth step, heat setting, obtaining a multi-layer microporous film with high gas permeability by heat setting at a first preset temperature (for example, 100℃-150℃).

[0056] Fifth step, winding and slitting, obtaining a finished product by winding with a winding machine and slitting with a slitting machine.

[0057] Six embodiments (Embodiment 1 to Embodiment 6) of the diaphragm 100 are prepared in the present application, and the data are shown in the following table:

[0058]

[0059] Comparative Example 1 is a diaphragm 100 with the same thickness as Embodiment 2 and a base film 10 with only a single layer of PE, and the tortuosity is 3.4.

[0060] Comparative Example 2 is a diaphragm 100 with the same thickness as Embodiment 3 and a base film 10 with only a single layer of PE, and the tortuosity is 4.8.

[0061] Comparative Example 3 is a diaphragm 100 with the same thickness as Embodiment 5 and a base film 10 with only a single layer of PP, and the tortuosity is 2.4.

[0062] Comparative Examples 1-3 only differ from the above description, and other aspects are the same as the embodiments.

[0063] The above embodiments and comparative examples are tested, and the test results of the above embodiments and comparative examples are shown in the following table:

[0064]

[0065]

[0066] Therefore, by sequentially increasing the tortuosity of the plurality of base films 10 from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the base film 10 close to the positive electrode side 21 can be relatively small, which is beneficial to the relatively fast passing of ions and the fast deintercalation of ions, and the tortuosity of the base film 10 close to the negative electrode side 31 can be relatively large, which is beneficial to improving the safety puncture performance of the diaphragm 100, so as to improve the fast charging capability of the battery and reduce the risk of dendrite puncturing the diaphragm 100.

[0067] The battery according to the embodiment of the present application comprises an electrode assembly, and the electrode assembly comprises: a first electrode sheet, a diaphragm 100 and a second electrode sheet, the diaphragm 100 is the diaphragm 100 described above, and the first electrode sheet, the diaphragm 100 and the second electrode sheet are cooperatively assembled to form the electrode assembly. The first electrode sheet can be a positive electrode sheet, and the second electrode sheet can be a negative electrode sheet. By sequentially increasing the tortuosity of the plurality of base films 10 from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the base film 10 close to the positive electrode side 21 can be relatively small, which is beneficial to the fast deintercalation of ions, and the tortuosity of the base film 10 close to the negative electrode side 31 can be relatively large, which is beneficial to improving the safety puncture performance of the diaphragm 100, so as to improve the fast charging capability of the battery and reduce the risk of dendrite puncturing the diaphragm 100.

[0068] The electronic device according to the embodiment of the present application comprises the battery described above, by sequentially increasing the tortuosity of the plurality of base films 10 from the positive electrode side 21 to the negative electrode side 31, the tortuosity of the base film 10 close to the positive electrode side 21 can be relatively small, which is beneficial to the relatively fast passing of ions, and the fast deintercalation of ions, and the tortuosity of the base film 10 close to the negative electrode side 31 can be relatively large, which is beneficial to improving the safety puncture performance of the diaphragm 100, so as to improve the fast charging capability of the battery and reduce the risk of dendrite puncturing the diaphragm 100.

[0069] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0070] In the description of the present application, "first feature" and "second feature" can include one or more features.

[0071] In the description of the present application, the meaning of "a plurality of" is two or more than two.

[0072] In the description of the present application, the first feature "above" or "below" the second feature can include that the first and second features are in direct contact, or can include that the first and second features are not in direct contact but are in contact through another feature between them.

[0073] In the description of the present application, the first feature "above", "above" and "above" the second feature includes 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.

[0074] In the description of the present application, the description of the reference terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0075] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A septum (100) characterized in that, The application relates to a diaphragm (100) and a battery. The diaphragm (100) comprises a plurality of base films (10), and the plurality of base films (10) are stacked along the thickness direction of the diaphragm (100), the diaphragm (100) has opposite first and second sides (20, 30), the first side (20) is a positive electrode side (21) of the diaphragm (100), the second side (30) is a negative electrode side (31) of the diaphragm (100), and the tortuosity of the plurality of base films (10) increases in turn from the positive electrode side (21) to the negative electrode side (31).

2. The diaphragm (100) according to claim 1, characterized in that The tortuosity of the plurality of base films (10) increases in an arithmetic progression or a non-arithmetic progression from the positive electrode side (21) to the negative electrode side (31).

3. The diaphragm (100) according to claim 1, characterized in that The plurality of base films (10) are divided into a first group of films (40) and a second group of films (50), the first group of films (40) and the second group of films (50) are stacked along the thickness direction of the diaphragm (100) and each comprises at least one base film (10), wherein the side of the first group of films (40) away from the second group of films (50) is the positive electrode side (21), the side of the second group of films (50) away from the first group of films (40) is the negative electrode side (31), the tortuosity of the base films (10) of the first group of films (40) is A, and the relationship 1<=A<=8 is satisfied.

4. The diaphragm (100) according to claim 3, characterized in that The tortuosity of the base films (10) of the second group of films (50) is B, and the relationship 1 5. The diaphragm (100) of claim 1, wherein, The molecular weight of the plurality of base films (10) decreases in turn from the positive electrode side (21) to the negative electrode side (31) so that the tortuosity of the plurality of base films (10) increases in turn.

6. The diaphragm (100) of claim 1, wherein, The thickness of the base film (10) is C, and the relationship 0.1 mu m<=C<=20 mu m is satisfied. The material of the base film (10) is PP or PE.

7. The septum (100) according to claim 1, characterized in that The molecular weight of the base film (10) is D, and the relationship 500,000<=D<=1,000,000 is satisfied. The gel particle melt index of the base film (10) is E, and the relationship 0.1 g / 10 min<=E<=5.0 g / 10 min is satisfied.

8. The septum (100) of claim 1, wherein, The pore size of the base film (10) is F, and the relationship 20 nm<=F<=200 nm is satisfied. The number of the base films (10) is G, and the relationship 2<=G<=10 is satisfied. The thickness of the diaphragm (100) is H, and the relationship 3 mu m<=H<=20 mu m is satisfied.

9. A battery, characterized by The application further relates to an electrode assembly comprising a first electrode tab, a diaphragm (100) and a second electrode tab, wherein the diaphragm (100) is the diaphragm (100) according to any one of claims 1-8, and the first electrode tab, the diaphragm (100) and the second electrode tab are assembled together to form the electrode assembly.

10. An electronic device, comprising: The application further relates to a battery comprising the diaphragm (100) according to claim 9.

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