Separators, secondary batteries and power consumption devices

Abstract

The present application provides a separator, a secondary battery, and a power consumption device, the separator comprising a first base film, a second base film, and an adhesive layer, the adhesive layer being disposed between the first base film and the second base film, the melting point of the second base film being higher than the melting point of the first base film, and the flexibility of the first base film being greater than the flexibility of the second base film.

Description

[Technical Field]

[0001] The present application relates to a separator, a secondary battery and a power consuming device. [Background technology]

[0002] In recent years, secondary batteries have been widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power plants, as well as in multiple fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. With the application and widespread use of secondary batteries, the requirements for their reliability are becoming increasingly stringent. Summary of the Invention

[0003] The present application aims to provide a separator, a secondary battery and a power consuming device, which improves the reliability of the secondary battery and extends the cycle life of the secondary battery.

[0004] A first aspect of the present application provides a separator, which includes a first base film, a second base film, and an adhesive layer, the adhesive layer being disposed between the first base film and the second base film, the melting point of the second base film being higher than the melting point of the first base film, and the flexibility of the first base film being greater than the flexibility of the second base film.

[0005] In the separator according to the embodiment of the present application, the first base film having a low melting point has a relatively large degree of flexibility, which on the one hand reduces the probability that the first base film will shrink when subjected to heat, thereby reducing the thermal shrinkage rate of the separator and improving the reliability of the secondary battery, and on the other hand allows the first base film to have a relatively long ion transport path, so that when the first base film of the separator faces the negative electrode, lithium ions have difficulty passing through the first base film, which slows down the speed at which the lithium ions reach the negative electrode and further slows down the growth of lithium dendrites. In addition, in the separator according to the embodiment of the present application, the second base film with a high melting point has a relatively small degree of flexure, which can complement the first base film and provide the separator with good breathability, thereby providing the separator with good ion conductivity and further improving the electrochemical performance and rate performance of the secondary battery. On the other hand, because the second base film has a high melting point and a relatively small degree of flexure, the base film shrinks less when heated, thereby allowing the separator to maintain good heat resistance and further improving the reliability of the secondary battery. Furthermore, the separator according to the embodiment of the present application can also provide layer-by-layer protection against lithium dendrites due to its base film-adhesive layer-base film structure. This effectively slows the continuous growth of lithium dendrites and reduces the physical pressure exerted by lithium dendrites on the separator, thereby reducing the risk of the separator being punctured and causing a short circuit between the positive and negative electrodes, thereby extending the cycle life of the secondary battery. Therefore, the separator according to the embodiment of the present application can improve the reliability of the secondary battery and further extend the cycle life of the secondary battery.

[0006] In any embodiment of the present application, the ratio of the flexural degree of the second base film to the flexural degree of the first base film is greater than 1.02, and optionally 1.05-4.

[0007] By adjusting the ratio of the degree of bending of the first base film to the degree of bending of the second base film within the above-mentioned appropriate range, it is advantageous to better complement the performance of the first base film and the second base film, thereby further improving the heat resistance of the separator and imparting good breathability to the separator, which is advantageous to improving the reliability and cycle life of the secondary battery.

[0008] In any embodiment of the present application, the flexural index of the first base film is 1-6, and optionally 1.5-5.5.

[0009] In any embodiment of the present application, the degree of tortuosity of the second base film is 0.3-4, and optionally 0.5-3.5.

[0010] This is advantageous in improving the ionic conductivity of the separator, which in turn is advantageous in further improving the rate performance of the secondary battery and extending the cycle life of the secondary battery.

[0011] In any embodiment of the present application, the ratio of the conductivity of the first base film to the conductivity of the second base film is less than 1, and optionally 0.4-0.8.

[0012] By adjusting the ratio of the electrical conductivity of the first base film to the electrical conductivity of the second base film within the above-mentioned appropriate range, it is possible to adjust the ratio of the degree of bending of the first base film to the degree of bending of the second base film within the appropriate range, and also to reduce the ionic resistance of the separator, which is advantageous for application to secondary batteries, and further for providing the secondary batteries with appropriate internal resistance, thereby providing the secondary batteries with both high reliability and good long-term cycle performance.

[0013] In any embodiment of the present application, the conductivity of the first base film is 0.2ms / cm-2.0ms / cm, and optionally 0.6ms / cm-1.5ms / cm.

[0014] In any embodiment of the present application, the conductivity of the second base film is 0.4ms / cm-2.0ms / cm, and optionally 0.8ms / cm-1.5ms / cm.

[0015] This not only makes it possible to adjust the degree of bending of the first base film, the second base film, and the separator, but also makes it possible to better complement the performance of the first base film and the second base film, giving the separator good heat resistance and relatively high ionic conductivity, thereby not only improving the reliability of the secondary battery, but also improving the long-term cycle capacity retention rate of the secondary battery.

[0016] In any embodiment of the present application, the ratio of the porosity of the first base film to the porosity of the second base film is 0.4-0.9, optionally 0.45-0.65.

[0017] By adjusting the ratio of the porosity of the first base film to the porosity of the second base film within the above-mentioned appropriate range, the ratio of the flexural modulus of the first base film to the flexural modulus of the second base film can be adjusted within the above-mentioned appropriate range, which is advantageous for further improving the reliability and long-term cycle performance of the secondary battery. Furthermore, by adjusting the ratio of the porosity of the first base film to the porosity of the second base film within the above-mentioned appropriate range, the active ion transport performance of the separator can be further improved, thereby further extending the cycle life of the secondary battery.

[0018] In any embodiment of the present application, the porosity of the first base film is 30%-60%, optionally 35%-50%.

[0019] In any embodiment of the present application, the porosity of the second base film is 25%-85%, optionally 40%-80%.

[0020] By adjusting the porosity of the first base film and / or the porosity of the second base film to fall within the above-described appropriate range, the active ion transport performance of the separator can be further improved, and the separator can be given high ionic conductivity, which is advantageous in further extending the cycle life of the secondary battery.

[0021] In any embodiment of the present application, the ratio of the thickness of the first base film to the thickness of the second base film is 0.5-3.5, and optionally 1.2-2.5.

[0022] By adjusting the ratio of the thickness of the first base film to the thickness of the second base film within the above appropriate range, the ratio of the bending degree of the first base film to the bending degree of the second base film can be adjusted within the appropriate range, and at the same time, the separator can have an appropriate thickness and relatively high mechanical strength. The separator has an appropriate thickness, which is advantageous for the secondary battery to maintain a relatively high energy density. The separator has relatively high mechanical strength, which is advantageous for improving the separator's puncture resistance, thereby improving the separator's durability, and further providing high reliability to the secondary battery.

[0023] In any embodiment of the present application, the thickness of the first base film is 10 μm or less, and optionally 2 μm-7 μm.

[0024] In any embodiment of the present application, the thickness of the second base film is 12 μm or less, and optionally 1 μm-6 μm.

[0025] Adjusting the thickness of the first base film and / or the second base film within the above ranges not only allows for adjustment of the flexibility and mechanical strength of the first base film, the second base film, and the separator, but also favors a high energy density of the secondary battery. Adjusting the thickness of the first base film and / or the second base film within the above ranges also favors improving the puncture resistance and tensile strength of the first base film and / or the second base film. This allows the first base film and / or the second base film to act as a shield and buffer during the lithium dendrite growth process, reducing the physical pressure exerted by lithium dendrites on the separator and reducing the risk of the separator being punctured, resulting in a short circuit between the positive and negative electrodes, thereby further improving the reliability of the secondary battery.

[0026] In any embodiment of the present application, the ratio of the melting point of the first base film to the melting point of the second base film is 0.3-0.85, optionally 0.4-0.7.

[0027] By adjusting the ratio of the melting point of the first base film to the melting point of the second base film within the above-mentioned appropriate range, it is advantageous to better complement the performance of the first base film and the second base film, thereby effectively improving the heat resistance performance of the separator, and thereby further improving the reliability of the secondary battery.

[0028] In any embodiment of the present application, the melting point of the first base film is 120°C or higher, optionally 125°C-260°C.

[0029] In any embodiment of the present application, the melting point of the second base film is 150°C or higher, optionally 160°C-350°C.

[0030] By adjusting the melting point of the first base film and / or the melting point of the second base film within the above range, it is possible to adjust the degree of flexibility of the first base film, the second base film, and the separator, and further to impart good pore-closing properties to the separator, which not only provides good ion conductivity when the secondary battery is operating normally, but also allows the separator to close pores in a timely manner when the secondary battery experiences thermal runaway, thereby cutting off current conduction, thereby achieving both good cycle performance and high reliability for the secondary battery.

[0031] In any embodiment of the present application, the material of the first base film includes one or more of polyolefins and derivatives thereof, halogenated polyolefins and derivatives thereof, polyethers and derivatives thereof, polyetheretherketones and derivatives thereof, polyesters and derivatives thereof, polyimides and derivatives thereof, and polyvinyl alcohols and derivatives thereof.

[0032] In any embodiment of the present application, the material of the second base film includes one or more of polyolefins and derivatives thereof, halogenated polyolefins and derivatives thereof, polyethers and derivatives thereof, polyetheretherketones and derivatives thereof, polyesters and derivatives thereof, polyimides and derivatives thereof, and polyvinyl alcohols and derivatives thereof.

[0033] In any embodiment of the present application, the adhesive layer comprises an adhesive. Optionally, the adhesive layer comprises an adhesive and a filler.

[0034] In any embodiment of the present application, the adhesive comprises one or more of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, starch, cyanoethyl amylopectin.

[0035] In any embodiment of the present application, the filler includes at least one of inorganic particles, organic particles, and organic-metallic framework materials.

[0036] Optionally, the inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or greater, inorganic particles that are ionically conductive but do not store ions, and inorganic particles that are capable of generating an electrochemical reaction.

[0037] Optionally, the organic particles comprise one or more of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifiers, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamideimide, polyaramid, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, copolymer of butyl acrylate and ethyl methacrylate.

[0038] Optionally, the organic-metal framework material comprises one or more of a nitrogen-containing heterocyclic ligand-based structure, an organic carboxylic acid-based ligand-based structure, and a nitrogen-containing oxygen gas mixture-based ligand-based structure.

[0039] In any embodiment of the present application, the thickness of the adhesive layer is 0.3 μm or more, and optionally 0.5 μm-2 μm.

[0040] In any embodiment of the present application, the adhesive strength between the adhesive layer and the first base film is ≧3 N / m, optionally 4 N / m-15 N / m.

[0041] In any embodiment of the present application, the adhesive strength between the adhesive layer and the second base film is ≧3 N / m, optionally 4 N / m-15 N / m.

[0042] In any embodiment of the present application, the content of the adhesive is ≧10%, and optionally 30% to 50%, based on the total weight of the adhesive layer.

[0043] In any embodiment of the present application, the content of the filler is 40%-90%, optionally 60%-80%, based on the total weight of the adhesive layer.

[0044] In any embodiment of the present application, the volume distribution particle size Dv50 of the filler is 1 μm or less, and optionally 0.3 μm-0.6 μm.

[0045] In any embodiment of the present application, the tortuosity of the separator is 1-15, optionally 2-10.

[0046] Optionally, the porosity of the separator is 65% or less, optionally 35%-55%.

[0047] When the tortuosity and / or porosity of the separator satisfy the above appropriate range, the separator can have good heat resistance and ion conductivity, thereby improving the reliability and electrochemical performance of the secondary battery.

[0048] Optionally, the separator has a transverse heat shrinkage at 250° C. for 1 hour of ≦1.5%, optionally ≦1%.

[0049] Optionally, the separator has a longitudinal heat shrinkage at 250° C. for 1 hour of ≦1.5%, and optionally ≦1%.

[0050] When the transverse heat shrinkage rate and / or the longitudinal heat shrinkage rate of the separator satisfy a given range, the separator can have good heat resistance, thereby improving the reliability of the secondary battery and reducing the probability of safety accidents such as fire and explosion occurring in the secondary battery.

[0051] A second aspect of the present application provides a secondary battery including the separator of the first aspect of the present application.

[0052] In any embodiment of the present application, the secondary battery includes a positive electrode plate and a negative electrode plate, a separator is disposed between the positive electrode plate and the negative electrode plate, and a first base film of the separator faces the negative electrode plate and a second base film faces the positive electrode plate.

[0053] A third aspect of the present application provides a power consuming device including the secondary battery of the second aspect of the present application.

[0054] The power consuming device of the present application includes a secondary battery according to the present application, and therefore has at least the same advantages as said secondary battery. [Brief explanation of the drawings]

[0055] In order to more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings that need to be used in the embodiments of the present application. It is obvious that the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without any creative efforts. [Figure 1] 1 is a schematic diagram of one embodiment of a secondary battery according to the present application. [Figure 2] 1 is an exploded schematic view of an embodiment of a secondary battery according to the present application. [Figure 3] 1 is a schematic diagram of one embodiment of a battery module according to the present application. [Figure 4] 1 is a schematic diagram of one embodiment of a battery pack according to the present application. [Figure 5]FIG. 5 is an exploded schematic view of the embodiment of the battery pack shown in FIG. 4. [Figure 6] 1 is a schematic diagram of one embodiment including a secondary battery-powered power consuming device according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0056] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the separator and manufacturing method thereof, secondary battery, and power consumption device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or repeated description of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0057] The "ranges" disclosed in this application are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the following ranges are also contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. Unless otherwise specified, the numerical range "ab" in this application is a shorthand notation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" represents that the specification has already listed all real numbers between "0-5," and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0059] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present application.

[0060] Unless otherwise specified, all steps in this application may be performed in order or randomly, preferably in order. For example, a description of a method including steps (a) and (b) means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, a description of a method that may further include step (c) means that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0061] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0062] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0063] Unless otherwise stated, in this application, the terms "first," "second," etc. are not intended to describe a particular order or hierarchy, but rather to distinguish between different objects.

[0064] In this application, the terms "plurality," "various," and the like refer to two or more.

[0065] Unless otherwise specified, terms used in this application have the known meanings commonly understood by those skilled in the art.

[0066] Unless otherwise specified, the numerical values ​​of each parameter mentioned in this application can be measured using various test methods commonly used in the art, for example, according to the test methods given in the examples of this application. Unless otherwise specified, the test temperature for each parameter is 25°C.

[0067] Unless otherwise specified, all ratio parameters in this application are compared when the units are the same. For example, if the thickness of A and B is 1.2:1, then the thickness units of A and B are the same.

[0068] Separator Generally, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is installed between the positive electrode plate and the negative electrode plate and mainly serves to prevent short circuits between the positive electrode and the negative electrode.

[0069] A separator according to an embodiment of the present application includes a first base film, a second base film, and an adhesive layer, the adhesive layer being disposed between the first base film and the second base film, the melting point of the second base film being higher than the melting point of the first base film, and the degree of bending of the first base film being greater than the degree of bending of the second base film.

[0070] Currently, separators used in commercial secondary batteries are generally polyolefin porous membranes, which have relatively poor heat resistance and undergo significant thermal shrinkage when heated, resulting in direct contact between the positive and negative electrodes inside the battery, leading to internal short circuits and increased safety risks for the secondary battery. To address these issues, the current approach is to coat a heat-resistant inorganic ceramic layer on the polyolefin porous membrane. However, the inorganic ceramic layer's effectiveness in improving the separator's heat resistance is limited, and the inorganic ceramic layer's poor adhesion makes it prone to powder shedding. This reduces the reliability of the secondary battery.

[0071] Without intending to be limited by any theory or explanation, when a separator includes the above-mentioned first base film, second base film, and adhesive layer positioned therebetween, the separator can have both good heat resistance and appropriate breathability, thereby improving the reliability of secondary batteries and further extending the cycle life of secondary batteries.

[0072] Specifically, when the melting point of the base film is low, adjusting the base film to have a relatively small degree of bending can improve the breathability of the base film, but when heated, the filaments of the base film will undergo significant thermal shrinkage, which will increase the thermal shrinkage rate of the separator, increase the probability of short-circuiting between the positive and negative electrodes, and reduce the reliability of the secondary battery. In the separator according to the embodiment of the present application, the first base film with a low melting point has a relatively large degree of bending, which, on the one hand, can reduce the probability of the first base film shrinking when heated, thereby reducing the thermal shrinkage rate of the separator and improving the reliability of the secondary battery. On the other hand, it can provide the first base film with a relatively long ion transport path, so that when the first base film of the separator faces the negative electrode, lithium ions have difficulty passing through the first base film, which can slow the rate at which the lithium ions reach the negative electrode and further slow the growth of lithium dendrites. Furthermore, in the separator according to the embodiments of the present application, the second base film with a high melting point has a relatively small degree of bending, which on the one hand can complement the first base film and provide the separator with good breathability, thereby providing the separator with good ion conductivity performance, and further improving the electrochemical performance and rate performance of the secondary battery; on the other hand, because the second base film has a high melting point, when its degree of bending is relatively small, the degree to which the base film shrinks when exposed to heat is also relatively small, which allows the separator to maintain good heat resistance performance, and further improving the reliability of the secondary battery.

[0073] Furthermore, the separator according to the embodiment of the present application can also provide layer-by-layer protection against lithium dendrites due to its base film-adhesive layer-base film structure, which can effectively slow the continuous growth of lithium dendrites and reduce the physical pressure that lithium dendrites exert on the separator, thereby reducing the risk of the separator being punctured and causing a short circuit between the positive and negative electrodes, and extending the cycle life of the secondary battery.

[0074] Therefore, the separator according to the embodiment of the present application can improve the reliability of the secondary battery and further extend the cycle life of the secondary battery.

[0075] In some embodiments, the ratio of the flexure of the first base film to the flexure of the second base film may be 1.02 or greater.

[0076] For example, the ratio of the flexural modulus of the first base film to the flexural modulus of the second base film may be 1.02, 1.05, 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or may be a range consisting of any two of the foregoing values.

[0077] Optionally, in some embodiments, the ratio of the degree of flexion of the first base film to the degree of flexion of the second base film can be 1.05-4, 1.5-4, 2-4, 2.5-4, 3-4, 3.5-4, 1.05-3.5, 1.5-3.5, 2-3.5, 2.5-3.5, 3-3.5, 1.05-3, 1.5-3, 2-3, 2.5-3, 1.05-2.5, 1.5-2.5, 2-2.5, 1.05-2, 1.5-2, or 1.05-1.5.

[0078] Without intending to be limited by any theory or interpretation, adjusting the ratio of the degree of bending of the first base film to the degree of bending of the second base film within the above appropriate range is advantageous in better complementing the performance of the first base film and the second base film, thereby further improving the heat resistance of the separator and imparting good breathability to the separator, which is advantageous in improving the reliability and cycle life of the secondary battery.

[0079] In some embodiments, the flexion degree of the first base film can be 1-6, such as 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or a range consisting of any two of the foregoing values.

[0080] Optionally, in some embodiments, the flexion degree of the first base film may be 1.5-5.5, such as 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, or a range consisting of any two of the foregoing values.

[0081] In some embodiments, the flexure of the second base film can be 0.3-4, such as 0.3, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, or a range consisting of any two of the foregoing values.

[0082] Optionally, in some embodiments, the flexural index of the second base film may be 0.5-3.5, such as 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, or a range consisting of any two of the foregoing values.

[0083] Without intending to be limited by any theory or interpretation, when the ratio of the degree of bending of the first base film to the degree of bending of the second base film is within an appropriate range, adjusting the degree of bending of the first base film and / or the degree of bending of the second base film within the appropriate range is advantageous for improving the ionic conductivity of the separator, thereby further improving the rate performance of the secondary battery and extending the cycle life of the secondary battery.

[0084] The bending degree of the base film has a meaning known in the art and can be tested using known equipment and methods. For example, the bending degree calculation formula τ=(R ion *ε) / R EL The bending degree τ of the base film can be calculated based on the above formula: ε represents the porosity of the base film, which can be measured using a mercury porosimeter with reference to GB / T 21650.1-2008.

[0085] R ionrepresents the ionic resistance of the base film, measured in Ω. It can be obtained by testing a symmetrical battery using electrochemical impedance spectroscopy (EIS) using an electrochemical workstation (e.g., VMP3B electrochemical workstation). Specifically, the base film is punched into a sample sheet of a certain size (e.g., 45.3 mm x 33.7 mm). The thickness of the sample sheet is denoted as I, and its area is denoted as S. A test sample is produced by stacking a lithium sheet, the sample sheet, and another lithium sheet in that order. The test sample is then placed in a case and injected with electrolyte to obtain a symmetrical battery. To improve accuracy, the ionic resistance of base films with different numbers of layers, N, is tested. The resulting ionic resistance values ​​are plotted against the number of base film layers, N, and the resulting slope is used to determine the ionic resistance, R, of the base film. ion The test voltage may be from -1 V to 1 V, and the frequency of the AC signal may be from 1 MHz to 1 KHz.

[0086] R EL represents the ionic resistance of the electrolyte at 25°C, which can be calculated based on the formula REL=I / (σ*S), the unit of measurement is Ω, I represents the thickness of the base film sample sheet used in the symmetric battery (here, it refers to the thickness of the single-layer base film sample sheet), the unit of measurement is μm, and S represents the area of ​​the base film sample used in the symmetric battery, the unit of measurement is mm 2 σ represents the conductivity of the electrolyte used in the symmetric battery, and the unit of measurement is ms / cm. The conductivity can be tested using a conductivity tester in accordance with 7SJ / T 11723-2018 (the test temperature is 25°C).

[0087] The degree of bending of the first base film and / or the second base film can be obtained by adjusting the intrinsic parameters of the base film (e.g., one or more of the composition, average filament diameter, porosity, thickness, air permeability, density, etc.) and / or the manufacturing process parameters of the first base film (e.g., one or more of the stretching parameters, heat setting parameters, etc.). For example, if other conditions remain unchanged, the greater the average filament diameter, the greater the degree of bending; the greater the thickness, the greater the degree of bending; the greater the air permeability, the smaller the degree of bending; the greater the porosity, the smaller the degree of bending; the greater the density, the greater the degree of bending; and the greater the stretch ratio during manufacturing, the smaller the degree of bending. A person skilled in the art can obtain a base film with a desired degree of bending through a limited number of tests.

[0088] In some embodiments, the ratio of the conductivity of the first base film to the conductivity of the second base film may be less than one.

[0089] For example, the ratio of the conductivity of the first base film to the conductivity of the second base film may be 0.99, 0.95, 0.9, 0.85, 0.8, 0.75, 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, or a range consisting of any two of the foregoing values.

[0090] Optionally, in some embodiments, the ratio of the conductivity of the first base film to the conductivity of the second base film may be 0.4-0.8, 0.5-0.8, 0.6-0.8, 0.7-0.8, 0.4-0.7, 0.5-0.7, 0.6-0.7, 0.4-0.6, 0.5-0.6, 0.4-0.5.

[0091] Without intending to be limited by any theory or interpretation, it is believed that adjusting the ratio of the electrical conductivity of the first base film to the electrical conductivity of the second base film within the above-mentioned appropriate range not only allows the ratio of the degree of bending of the first base film to the degree of bending of the second base film to be adjusted within an appropriate range, but also reduces the ionic resistance of the separator, which is advantageous for the application of the separator of the present application to secondary batteries, thereby providing the secondary batteries with appropriate internal resistance and thereby providing both high reliability and good long-term cycle performance.

[0092] In some embodiments, the conductivity of the first base film can be 0.2 ms / cm-2.0 ms / cm, such as 0.2 ms / cm, 0.5 ms / cm, 0.8 ms / cm, 1.0 ms / cm, 1.2 ms / cm, 1.5 ms / cm, 1.8 ms / cm, 2.0 ms / cm, or a range consisting of any two of the foregoing values.

[0093] Optionally, in some embodiments, the conductivity of the first base film may be 0.6 ms / cm-1.5 ms / cm, such as 0.6 ms / cm, 0.7 ms / cm, 0.8 ms / cm, 0.9 ms / cm, 1.0 ms / cm, 1.1 ms / cm, 1.2 ms / cm, 1.3 ms / cm, 1.4 ms / cm, 1.5 ms / cm, or a range consisting of any two of the foregoing values.

[0094] In some embodiments, the conductivity of the second base film can be 0.4 ms / cm-2.0 ms / cm, such as 0.4 ms / cm, 0.8 ms / cm, 1.0 ms / cm, 1.2 ms / cm, 1.5 ms / cm, 1.8 ms / cm, 2.0 ms / cm, or a range consisting of any two of the foregoing values.

[0095] Optionally, in some embodiments, the conductivity of the second base film may be 0.8 ms / cm-1.5 ms / cm, such as 0.8 ms / cm, 0.9 ms / cm, 1.0 ms / cm, 1.1 ms / cm, 1.2 ms / cm, 1.3 ms / cm, 1.4 ms / cm, 1.5 ms / cm, or a range consisting of any two of the foregoing values.

[0096] Without intending to be limited by any theory or interpretation, it is believed that by adjusting the conductivity of the first base film and / or the conductivity of the second base film within the above range, the degree of flexibility of the first base film, the second base film, and the separator can be adjusted, and the performance of the first base film and the second base film can be better complemented, giving the separator good heat resistance and relatively high ionic conductivity, thereby not only improving the reliability of the secondary battery but also improving the long-term cycle capacity retention rate of the secondary battery.

[0097] The electrical conductivity of the first base film and the second base film has a meaning known in the art and can be tested using equipment and methods known in the art, for example, using an AC impedance meter in accordance with NB-T 10827-2021.

[0098] In some embodiments, the ratio of the porosity of the first base film to the porosity of the second base film may be 0.4-0.9, such as 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or a range consisting of any two of the foregoing values.

[0099] Optionally, in some embodiments, the ratio of the porosity of the first base film to the porosity of the second base film may be 0.45-0.65, 0.5-0.65, 0.55-0.65, 0.6-0.65, 0.45-0.6, 0.5-0.6, 0.55-0.6, 0.45-0.55, 0.5-0.55, or 0.45-0.5.

[0100] Without intending to be limited by any theory or interpretation, adjusting the ratio of the porosity of the first base film to the porosity of the second base film within the above-mentioned appropriate range allows the ratio of the flexural modulus of the first base film to the flexural modulus of the second base film to be adjusted within an appropriate range. This is advantageous for further improving the reliability and long-term cycle performance of the secondary battery. Furthermore, adjusting the ratio of the porosity of the first base film to the porosity of the second base film within the above-mentioned appropriate range further improves the active ion transport performance of the separator, thereby further extending the cycle life of the secondary battery.

[0101] In some embodiments, the porosity of the first base film may be 30%-60%, such as 30%, 35%, 40%, 45%, 50%, 55%, 60%, or a range consisting of any two of the foregoing values.

[0102] Optionally, in some embodiments, the porosity of the first base film may be 35%-50%, such as 35%, 38%, 40%, 42%, 45%, 48%, 50%, or a range consisting of any two of the foregoing values.

[0103] In some embodiments, the porosity of the second base film may be 25%-85%, for example, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or a range consisting of any two of the foregoing values.

[0104] Optionally, in some embodiments, the porosity of the second base film may be 40%-80%, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or a range consisting of any two of the foregoing values.

[0105] Without intending to be limited by any theory or interpretation, it is believed that adjusting the porosity of the first base film and / or the porosity of the second base film to fall within the above-mentioned appropriate ranges can further improve the active ion transport performance of the separator and provide the separator with high ionic conductivity, which is advantageous in further extending the cycle life of the secondary battery.

[0106] The porosity of the first base film and the second base film has a meaning known in the art and can be measured using instruments and methods known in the art, for example, a mercury porosimeter test can be performed in accordance with GB / T 21650.1-2008.

[0107] In some embodiments, the ratio of the thickness of the first base film to the thickness of the second base film may be 0.5-3.5, such as 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, 3.2, 3.5, or a range consisting of any two of the foregoing values.

[0108] Optionally, in some embodiments, the ratio of the thickness of the first base film to the thickness of the second base film can be 1.2-2.5, 1.5-2.5, 1.8-2.5, 2.0-2.5, 2.2-2.5, 1.2-2.2, 1.5-2.2, 1.8-2.2, 2.0-2.2, 1.2-2.0, 1.5-2.0, 1.8-2.0, 1.2-1.8, 1.5-1.8, or 1.2-1.5.

[0109] Without intending to be limited by any theory or interpretation, adjusting the ratio of the thickness of the first base film to the thickness of the second base film within the above appropriate range allows the ratio of the flexural degree of the first base film to the flexural degree of the second base film to be adjusted within the appropriate range, while at the same time providing the separator with an appropriate thickness and relatively high mechanical strength. The separator has an appropriate thickness, which is advantageous for the secondary battery to maintain a relatively high energy density. The separator has relatively high mechanical strength, which is advantageous for improving the separator's puncture resistance, thereby improving the separator's durability, and further providing the secondary battery with high reliability.

[0110] In some embodiments, the thickness of the first base film can be 10 μm or less, such as 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, or a range consisting of any two of the foregoing values.

[0111] Optionally, in some embodiments, the thickness of the first base film may be 2 μm-7 μm, such as 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, or a range consisting of any two of the foregoing values.

[0112] In some embodiments, the thickness of the second base film can be 12 μm or less, such as 12 μm, 11 μm, 10 μm, 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, or a range consisting of any two of the foregoing values.

[0113] Optionally, in some embodiments, the thickness of the second base film can be 1 μm-6 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, or a range consisting of any two of the foregoing values.

[0114] Without intending to be limited by any theory or interpretation, adjusting the thickness of the first base film and / or the second base film within the above ranges not only allows for adjustment of the flexibility and mechanical strength of the first base film, the second base film, and the separator, but also favors a high energy density of the secondary battery. Adjusting the thickness of the first base film and / or the second base film within the above ranges also favors improving the puncture resistance and tensile strength of the first base film and / or the second base film. As a result, during the lithium dendrite growth process, the first base film and / or the second base film can act as a shield and buffer, reducing the physical pressure exerted by lithium dendrites on the separator and reducing the risk of the separator being punctured, resulting in a short circuit between the positive and negative electrodes, thereby further improving the reliability of the secondary battery.

[0115] The thickness of the first base film and the second base film has a meaning known in the art and can be measured using instruments and methods known in the art. For example, six sets of parallel samples are taken, and the thickness of each set of samples is measured at different positions using a multimeter thickness meter, and each set of samples is measured at at least 20 positions, and the average thickness of the six sets of samples is the thickness of the sample.

[0116] In some embodiments, the ratio of the melting point of the first base film to the melting point of the second base film may be 0.3-0.85, such as 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, or a range consisting of any two of the foregoing values.

[0117] Optionally, in some embodiments, the ratio of the melting point of the first base film to the melting point of the second base film can be 0.4-0.7, 0.5-0.7, 0.55-0.7, 0.6-0.7, 0.65-0.7, 0.4-0.65, 0.45-0.65, 0.5-0.65, 0.55-0.65, 0.6-0.65, 0.4-0.6, 0.45-0.6, 0.5-0.6, 0.55-0.6, 0.4-0.55, 0.45-0.55, 0.5-0.55, 0.4-0.5, 0.45-0.5, or 0.4-0.45.

[0118] Without intending to be limited by any theory or interpretation, adjusting the ratio of the melting point of the first base film to the melting point of the second base film to fall within the above-mentioned appropriate range is advantageous in better complementing the performance of the first base film and the second base film, thereby effectively improving the heat resistance performance of the separator and thereby further improving the reliability of the secondary battery.

[0119] In some embodiments, the melting point of the first base film may be 120°C or greater, such as 120°C, 130°C, 135°C, 140°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 200°C, 220°C, 240°C, 260°C, or a range consisting of any two of the foregoing values.

[0120] Optionally, in some embodiments, the melting point of the first base film may be 125°C-260°C, 130°C-260°C, 140°C-260°C, 150°C-260°C, 160°C-260°C, 170°C-260°C, 125°C-200°C, 130°C-200°C, 140°C-200°C, 150°C-200°C, 160°C-200°C, 125°C-180°C, 130°C-180°C, 140°C-180°C, 150°C-180°C, 125°C-150°C, 130°C-150°C, or 140°C-150°C.

[0121] In some embodiments, the melting point of the second base film can be 150°C or greater, such as 150°C, 160°C, 165°C, 170°C, 180°C, 190°C, 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 330°C, 350°C, or a range consisting of any two of the foregoing values.

[0122] Optionally, in some embodiments, the melting point of the second base film may be 160°C-350°C, 170°C-350°C, 180°C-350°C, 200°C-350°C, 160°C-320°C, 170°C-320°C, 180°C-320°C, 200°C-320°C, 160°C-300°C, 180°C-300°C, or 200°C-300°C.

[0123] Without intending to be limited by any theory or interpretation, adjusting the melting point of the first base film and / or the melting point of the second base film within the above ranges makes it possible to adjust the degree of flexibility of the first base film, the second base film, and the separator, and further to impart good pore-closing properties to the separator, which not only allows the separator to have good ion conductivity when the secondary battery is operating normally, but also allows the separator to close pores in a timely manner when the secondary battery experiences thermal runaway, thereby cutting off current conduction, thereby enabling the secondary battery to have both good cycle performance and high reliability.

[0124] The melting points of the first and second base films have meanings known in the art and can be measured using known instruments and methods. For example, they can be measured using differential scanning calorimetry. For details, see standard GB / T 19466.3-2004. For example, they can be measured as follows: a 4 mg-6 mg sample is placed in the sample chamber of a differential scanning calorimeter, and the temperature is increased from 25°C to 400°C at a heating rate of 10°C / min. A melting endothermic curve of the sample is obtained, and the temperature corresponding to the peak of the curve is the melting point of the sample.

[0125] In some embodiments, the first base film and the second base film may each independently comprise one or more selected from polyolefins and their derivatives, halogenated polyolefins and their derivatives, polyethers and their derivatives, polyetheretherketones and their derivatives, polyesters and their derivatives, polyimides and their derivatives, and polyvinyl alcohols and their derivatives.

[0126] Optionally, the halogenated polyolefin and its derivatives may include one or more selected from polytetrafluoroethylene (PTFE) and its derivatives, polyvinyl fluoride and its derivatives, and polyvinylidene fluoride and its derivatives.

[0127] Optionally, the polyester and its derivatives may include one or more of polyethylene terephthalate and its derivatives, polybutylene terephthalate and its derivatives.

[0128] A derivative generally refers to a product derived from a polymer by replacing a hydrogen atom or atomic group with another atom or atomic group.

[0129] In some embodiments, the adhesive layer may include an adhesive that can ensure the adhesive strength and uniformity of the first and second base films, and can also impart good heat resistance to the separator, improving the reliability of the secondary battery.

[0130] In some examples, the adhesive may include one or more of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, starch, and cyanoethyl amylopectin.

[0131] In some embodiments, the adhesive layer may include an adhesive and a filler. The filler can further improve the heat resistance and physical properties (e.g., tensile strength, puncture strength, etc.) of the separator, thereby improving the reliability of the secondary battery. By interposing the filler between the first base film and the second base film, the occurrence of powder shedding problems can also be avoided.

[0132] By way of example, in some embodiments, the filler may include at least one of inorganic particles, organic particles, and organic-metallic framework materials.

[0133] Optionally, the inorganic particles may include one or more of inorganic particles having a dielectric constant of 5 or greater, inorganic particles that are ionically conductive but do not store ions, and inorganic particles that are capable of generating an electrochemical reaction.

[0134] Optionally, the organic particles may comprise one or more of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifiers (e.g., carboxymethyl cellulose), melamine resin, phenolic resin, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), silicone resin, polyimide, polyamideimide, polyaramid, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, copolymer of butyl acrylate and ethyl methacrylate (crosslinked polymer of butyl acrylate and ethyl methacrylate).

[0135] Optionally, the organic-metal framework material may include one or more of a nitrogen-containing heterocyclic ligand-based structure, an organic carboxylic acid-based ligand-based structure, and a nitrogen-containing oxygen gas mixture-based ligand-based structure.

[0136] In some embodiments, the adhesive content may be 10% or more, and optionally 10%-30%, based on the total weight of the adhesive layer.

[0137] In some embodiments, the filler content may be 40%-90%, optionally 60%-80%, 65%-80%, 70%-80%, 75%-80%, 60%-75%, 65%-75%, 70%-75%, 60%-70%, 65%-70%, or 60%-65%, based on the total weight of the adhesive layer.

[0138] In some embodiments, the adhesive layer may further include a dispersant, such as carboxymethyl cellulose, which can adjust the viscosity of the adhesive layer slurry and improve the quality and uniformity of the membrane layer.

[0139] In some embodiments, the thickness of the adhesive layer may be 0.3 μm or more, and optionally 0.5-2 μm. When the thickness of the adhesive layer is within the above range, the separator can have an appropriate thickness, and the separator can have good heat resistance and physical properties, thereby improving the reliability of the secondary battery.

[0140] The test method for the thickness of the adhesive layer can be referred to the test method for the thickness of the first base film and the second base film.

[0141] In some embodiments, the adhesive strength between the adhesive layer and the first base film may be 3 N / m or more, optionally 4 N / m-15 N / m.

[0142] In some embodiments, the adhesive strength between the adhesive layer and the second base film may be 3 N / m or more, optionally 4 N / m-15 N / m.

[0143] In some embodiments, the volume distribution particle size Dv50 of the filler may be 1 μm or less, optionally 0.3 μm-0.6 μm, 0.35 μm-0.55 μm, 0.4 μm-0.5 μm, or 0.45 μm-0.5 μm.

[0144] In some embodiments, the separator's tortuosity may be 1-15, such as 1, 3, 5, 7, 9, 11, 13, 15, or any range consisting of any two of the foregoing. Optionally, the separator's tortuosity may be 2-10, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, or any range consisting of any two of the foregoing.

[0145] In some embodiments, the porosity of the separator may be up to 65%, and optionally 35%-55%.

[0146] The test methods for the bending degree and porosity of the separator can be referenced to the test methods for the bending degree and porosity of the first base film and the second base film.

[0147] When the tortuosity and / or porosity of the separator satisfy the above appropriate range, the separator can have good heat resistance and ion conductivity, thereby improving the reliability and electrochemical performance of the secondary battery.

[0148] In some embodiments, the separator may have a transverse heat shrinkage of 1.5% or less, and optionally 1% or less, at 250° C. for 1 hour.

[0149] In some embodiments, the separator may have a longitudinal heat shrinkage of 1.5% or less, and optionally 1% or less, at 250° C. for 1 hour.

[0150] When the transverse heat shrinkage rate and / or the longitudinal heat shrinkage rate of the separator satisfy a given range, the separator can have good heat resistance, thereby improving the reliability of the secondary battery and reducing the probability of safety accidents such as fire and explosion occurring in the secondary battery.

[0151] The thermal shrinkage rate in the transverse direction and the thermal shrinkage rate in the longitudinal direction of the separator both have meanings known in the art and can be measured using instruments and methods known in the art, for example, they can be tested in accordance with GB / T 36363-2018.

[0152] Manufacturing method The examples of the present application further provide methods used to manufacture separators according to the examples of the present application.

[0153] The method includes the following steps: providing a first base film and a second base film, the melting point of the second base film being higher than that of the first base film and the flexibility of the first base film being greater than that of the second base film; providing an adhesive layer slurry, the adhesive layer slurry including an adhesive; applying the adhesive layer slurry to the first base film and / or the second base film; and combining the first base film and the second base film to obtain a separator.

[0154] When the first base film and the second base film are combined using an adhesive layer slurry, the process is simple and the heat resistance and physical properties of the separator can be improved, thereby improving the reliability of the secondary battery. When the first base film and the second base film are combined using an adhesive layer slurry, process defects in the hot-pressing composite process can also be avoided. In the hot-pressing composite process, if the temperature is too high, the porosity of the separator will be small and the breathability will be poor, and if the temperature is too low, the adhesion between the first base film and the second base film will be unstable. Therefore, it is necessary to select an appropriate hot-pressing temperature.

[0155] In some embodiments, the adhesive layer slurry may further include a filler. Optionally, the filler may include at least one of inorganic particles, organic particles, and an organic-metallic framework material.

[0156] In some embodiments, the adhesive layer slurry may be applied by transfer coating, spin spray coating, dip coating, or the like, but the embodiments of the present application are not limited thereto.

[0157] Unless otherwise specified, each raw material used in the manufacturing method of the separator is commercially available.

[0158] secondary battery An embodiment of the present application further provides a secondary battery.

[0159] A secondary battery, also known as a rechargeable battery or storage battery, is a battery that can be continuously used by activating the active material through charging after discharging. Generally, a secondary battery includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate and mainly serves to prevent short circuits between the positive electrode and the negative electrode and allows active ions to pass through.

[0160] The present application is not particularly limited to the type of secondary battery, and for example, the secondary battery may be a lithium ion battery, a sodium ion battery, a lithium metal battery, a sodium metal battery, etc., and in particular, the secondary battery may be a lithium ion battery.

[0161] A secondary battery according to an embodiment of the present application includes the separator of the present application or a separator manufactured by the method of the present application, and the separator can improve the reliability of the secondary battery and further extend the cycle life of the secondary battery.

[0162] In some embodiments, the first base film of the separator faces (ie, is adjacent to) the negative electrode plate and the second base film faces (ie, is adjacent to) the positive electrode plate.

[0163] [Positive electrode plate] In some embodiments, the positive electrode plate may include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces facing each other in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on one or both of the two facing surfaces of the positive electrode current collector.

[0164] When the secondary battery is a lithium ion battery, the positive electrode active material may include, but is not limited to, at least one of lithium transition metal oxides, lithium-containing phosphates, and their respective modified compounds. Examples of lithium transition metal oxides may include, but are not limited to, at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds. Examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their respective modified compounds.

[0165] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium ion battery may include at least one of lithium transition metal oxides and their modified compounds with the general formula Li a Ni b Co c M d O e A f where 0.8 ≤ a ≤ 1.2, 0.5 ≤ b < 1, 0 < c < 1, 0 < d < 1, 1 ≤ e ≤ 2, 0 ≤ f ≤ 1, M is at least one selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is at least one selected from N, F, S, and Cl.

[0166] For example, the positive electrode active material used in the lithium ion battery may be LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6Co 0.2 Mn 0.2 O2(NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may contain at least one of O2, LiFePO4, and LiMnPO4.

[0167] When the secondary battery is a sodium ion battery, the positive electrode active material may include at least one of a sodium-containing transition metal oxide, a polyanion material (e.g., phosphate, fluorophosphate, pyrophosphate, sulfate, etc.), and a Prussian blue-based material, but is not limited thereto.

[0168] For example, the positive electrode active materials used in sodium ion batteries are NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, general formula X p M' q (PO4) r O x Y 3-x The compound may contain at least one of the substances represented by the general formula X p M' q (PO4) r O x Y 3-x In, 0 <p≦4、0<q≦2、1≦r≦3、0≦x≦2であり、Xは、H + , Li + , Na + , K. + and NH4 +wherein M' is a transition metal cation, optionally at least one of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn; and Y is a halogen anion, optionally at least one of F, Cl, and Br.

[0169] The modifying compounds for the positive electrode active material are used to modify the positive electrode active material by doping and / or surface coating.

[0170] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. The present application does not particularly limit the type of the positive electrode conductive agent, and examples of the positive electrode conductive agent include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0171] In some embodiments, the positive electrode membrane layer may further include a positive electrode adhesive. The present application is not particularly limited to the type of the positive electrode adhesive, and the positive electrode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0172] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet is aluminum foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0173] The positive electrode film layer is typically obtained by coating a positive electrode slurry on a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive, and any other optional components in a solvent and stirring the resulting mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP).

[0174] [Negative electrode plate] In some embodiments, the negative electrode plate may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces facing each other in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on one or both of the two facing surfaces of the negative electrode current collector.

[0175] The negative electrode active material may be any negative electrode active material for secondary batteries known in the art. For example, the negative electrode active material may include, but is not limited to, at least one of natural graphite, artificial graphite, soft carbon, hard carbon, a silicone-based material, a tin-based material, and lithium titanate. The silicone-based material may include at least one of a silicone element, a silicone oxide, a silicone carbon composite, a silicone nitrogen composite, and a silicone alloy material. The tin-based material may include at least one of a tin element, a tin oxide, and a tin alloy material.

[0176] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent, and the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0177] In some embodiments, the negative electrode film layer may further optionally include a negative electrode adhesive. The present application is not particularly limited to the type of negative electrode adhesive, and the negative electrode adhesive may include, for example, at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble acrylic acid-based resin (e.g., polyacrylic acid (PAA), polymethacrylic acid (PMAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0178] In some embodiments, the negative electrode membrane layer may further optionally include other additives, such as thickeners, e.g., sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.

[0179] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. An example of the metal foil sheet is copper foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. For example, the metal layer may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0180] The negative electrode film layer is typically obtained by coating a negative electrode slurry on a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing a negative electrode active material, an optional conductive agent, an optional adhesive, and other optional auxiliary agents in a solvent and stirring the resulting mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0181] The negative electrode plate does not exclude additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode plate further includes a conductive undercoating (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode plate of the present application further includes a protective layer covering the surface of the negative electrode film layer.

[0182] [Electrolyte] During the charge and discharge process of the secondary battery, active ions are absorbed and released by moving back and forth between the positive and negative electrodes, and the electrolyte serves to conduct the active ions between the positive and negative electrodes. The present application does not particularly limit the type of electrolyte, and it can be selected according to actual needs.

[0183] The electrolyte solution includes an electrolyte salt and a solvent, and the types of the electrolyte salt and the solvent are not specifically limited and can be selected according to actual needs.

[0184] When the secondary battery is a lithium-ion battery, for example, the electrolyte salt may include at least one of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorobis(oxalato)phosphate (LiDFOP), and lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0185] When the secondary battery is a sodium-ion battery, for example, the electrolyte salt may include at least one of sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium perchlorate (NaClO), sodium hexafluoroarsenate (NaAsF), sodium bisfluorosulfonylimide (NaFSI), sodium bistrifluoromethanesulfonylimide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoro(oxalato)borate (NaDFOB), sodium bis(oxalato)borate (NaBOB), sodium difluorophosphate (NaPOF), sodium difluorobis(oxalato)phosphate (NaDFOP), and sodium tetrafluoro(oxalato)phosphate (NaTFOP).

[0186] By way of example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0187] In some embodiments, the electrolyte solution may further optionally contain additives. For example, the additives may include a negative electrode film-forming additive, a positive electrode film-forming additive, and may further include additives that can improve some battery performance, such as an additive that improves the overcharge performance of the battery, an additive that improves the high-temperature performance of the battery, or an additive that improves the low-temperature power performance of the battery.

[0188] In some embodiments, the positive electrode plate, separator, and negative electrode plate may be fabricated into an electrode assembly by a winding process and / or a stacking process.

[0189] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0190] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0191] The present application does not particularly limit the shape of the secondary battery, and the secondary battery may be cylindrical, rectangular, or any other shape. Figure 1 shows an example of a secondary battery 5 having a rectangular structure.

[0192] In some embodiments, as shown in FIG. 2 , the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and side plates connected to the bottom plate, which together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 is used to cover the opening and seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process and / or a stacking process. The electrode assembly 52 is packaged in the accommodating cavity. An electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and can be adjusted as needed.

[0193] Methods for manufacturing secondary batteries are well known. In some embodiments, a secondary battery can be formed by assembling a positive electrode plate, a separator, a negative electrode plate, and an electrolyte. For example, the positive electrode plate, the separator, and the negative electrode plate can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly can be placed in an outer casing, dried, and then injected with an electrolyte. The secondary battery can be obtained through processes such as vacuum packaging, standing, chemical formation, and shaping.

[0194] In some embodiments, the secondary battery according to the present application can be assembled into a battery module, and the number of secondary batteries included in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0195] Fig. 3 is a schematic diagram of an example battery module 4. As shown in Fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0196] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0197] In some embodiments, the battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0198] 4 and 5 are schematic diagrams of an example battery pack 1. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0199] power consumption equipment An embodiment of the present application further provides a power consuming device, the power consuming device including at least one of a secondary battery, a battery module, or a battery pack according to the embodiment of the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobile device (e.g., a mobile phone, a laptop, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0200] The power consumption device may select a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0201] 6 is a schematic diagram of an example power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, that may employ a battery pack or battery module to meet the high power and high energy density demands of the power consuming device.

[0202] Other examples of power consuming devices include mobile phones, tablet computers, notebook computers, etc. These power consuming devices generally require a thin design and can employ secondary batteries as their power source. [Example]

[0203] The following examples will more specifically describe the contents disclosed in this application, and these examples are for illustrative purposes only, as various modifications and variations within the scope of the contents disclosed in this application will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are by weight, and all reagents used in the examples can be obtained commercially or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the examples can be obtained commercially.

[0204] Example 1 Separator manufacturing A first base film and a second base film are provided, the first base film having a flexural index of 1 and the second base film having a flexural index of 0.98.

[0205] Preparation of adhesive layer slurry: Boehmite, polyacrylate, and carboxymethyl cellulose were uniformly mixed in a mass ratio of 4:1:1 with an appropriate amount of deionized water as a solvent to prepare an adhesive layer slurry.

[0206] The adhesive layer slurry was applied to a first base film using an applicator, and another unwinding roll was a second base film, which was then bonded to the adhesive layer slurry surface of the first base film.The oven temperature was controlled to 35°C, the film was dried for 5 seconds, and the film was pressed at a pressure of 10 N to obtain a separator.

[0207] Positive electrode plate manufacturing Positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1O2 (NCM811), carbon black (Super P) as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive were uniformly mixed in an appropriate amount of solvent N-methylpyrrolidone (NMP) in a mass ratio of 96.2:2.7:1.1 to obtain a positive electrode slurry. The positive electrode slurry was then applied to a positive electrode current collector aluminum foil, and after processes such as drying, cold pressing, slitting, and cutting, a positive electrode plate was obtained.

[0208] Negative electrode plate manufacturing The negative electrode active material, artificial graphite, the conductive agent, carbon black (Super P), the adhesive, styrene butadiene rubber (SBR) and carboxymethyl cellulose sodium (CMC-Na), were uniformly mixed in a mass ratio of 96.4:0.7:1.8:1.1 in an appropriate amount of deionized water solvent to obtain a negative electrode slurry. The negative electrode slurry was then applied to a negative electrode current collector copper foil, and the mixture was dried, cold pressed, slit, and cut to obtain a negative electrode plate.

[0209] Electrolyte production Ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a mass ratio of 30:30:40 to obtain an organic solvent, and thoroughly dried LiPF6 was dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L.

[0210] Secondary battery manufacturing A positive electrode plate, a separator, and a negative electrode plate were stacked in this order and wound to obtain an electrode assembly. The electrode assembly was then placed in an outer casing, dried, and then an electrolyte was added. After undergoing processes such as vacuum packaging, standing, chemical conversion, and shaping, a secondary battery was obtained.

[0211] The secondary batteries of Examples 2-9 and Comparative Examples 1-3 are similar to Example 1, except that different separators are used. See Table 1 for details.

[0212] In the above examples and comparative examples, the melting points of the first base film and the second base film can be measured by the following method: a 4 mg-6 mg sample is taken and placed in the sample chamber of a differential scanning calorimeter. The temperature is increased from 25°C to 400°C at a heating rate of 10°C / min to obtain a melting endothermic curve of the sample. The temperature corresponding to the peak of the curve is the melting point of the sample.

[0213] In the above examples and comparative examples, the electrical conductivity of each of the first base film and the second base film can be tested using an AC impedance meter with reference to NB-T 10827-2021. The electrical conductivity of the first base film may be denoted as σ1, and the electrical conductivity of the second base film may be denoted as σ2.

[0214] The degree of bending of the separator may be denoted as τ0, the degree of bending of the first base film may be denoted as τ1, and the degree of bending of the second base film may be denoted as τ2.

[0215] Testing part (1) Separator heat shrinkage test Sample preparation: The separator prepared above was punched into samples with a width of 50 mm and a length of 100 mm using a press, and five parallel samples were taken and placed on a glass plate to fix them.

[0216] Sample test: Set the temperature of the blast oven to 250°C, and after the temperature reaches the set temperature and stabilizes for 60 minutes, place the glass plate in the blast oven and time it for 1 hour. After the time is up, measure the width of the separator and mark the value as a (unit: mm).

[0217] Calculation of heat shrinkage rate: transverse (TD) direction heat shrinkage rate = [(50-a) / 50] x 100%, the average value of five parallel samples is taken as the test result.

[0218] (2) Room temperature cycle performance test of secondary batteries After leaving the secondary battery at 25°C for 30 min, it was charged at a constant current of 1 C to 4.35 V, continued to be charged at a constant voltage until the current became ≦0.05 C, and then discharged at a constant current of 1 C to 2.8 V, and the discharge capacity C1 of the first cycle was recorded.

[0219] The secondary battery was then cycled by charging at a constant current of 0.33 C₁ ... to 4.3 V, leaving it for 5 minutes, and then discharging at 1 C₁₁₁₁ to 3.3 V. The discharge capacity during the cycles was recorded. The capacity retention at the 700th cycle, P, was calculated as (discharge capacity at the 700th cycle / discharge capacity at the 1st cycle, C₁₁₁) × 100%. For accuracy, the average value of five parallel samples was taken as the test result.

[0220] [Table 1] JPEG2025539496000003.jpg245170

[0221] As can be seen from the test results in Table 1, when the degree of bending of the first base film is greater than the degree of bending of the second base film, the separator has a relatively small thermal shrinkage rate, which not only gives the secondary battery high thermal stability and higher reliability, but also improves the cycle capacity retention rate of the secondary battery and gives the secondary battery good long-term cycle performance.

[0222] The test results of Examples 1-9 show that adjusting the conductivity of the first and second base films allows the degree of bending of the first and second base films to be changed accordingly. By adjusting the conductivity of the first and second base films to satisfy an appropriate range, the ratio of the degree of bending of the first base film to the degree of bending of the second base film can be controlled within an appropriate range, which is advantageous for improving the stability, reliability, and long-term cycle performance of the secondary battery. Furthermore, as can be seen from the test results of Examples 8-9, using a second base film with a higher melting point and conductivity can further improve the heat resistance of the separator and the cycle capacity retention rate of the secondary battery.

[0223] In contrast, the separator of Comparative Example 1-3 does not satisfy the requirement of the present application that the degree of bending of the first base film is greater than the degree of bending of the second base film, and the heat resistance performance of the separator is significantly lower than that of Example 1-9, and the cycle capacity retention rate of the secondary battery is also unfavorable.

[0224] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods configured by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0225] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: cover plate.

Claims

1. A separator, a first base film; a second base film having a melting point higher than the melting point of the first base film; an adhesive layer disposed between the first base film and the second base film; A separator, wherein the first base film has a greater degree of flexibility than the second base film.

2. 10. The separator of claim 1, wherein the ratio of the flexural modulus of the second base film to the flexural modulus of the first base film is greater than 1.02, and optionally 1.05-4.

3. The flexural index of the first base film is 1-6, optionally 1.5-5.5; and / or The separator according to claim 1 or 2, wherein the flexural degree of the second base film is 0.3-4, and optionally 0.5-3.

5.

4. The separator according to any one of claims 1 to 3, wherein the ratio of the conductivity of the first base film to the conductivity of the second base film is less than 1, and optionally 0.4-0.

8.

5. the electrical conductivity of the first base film is 0.2 ms / cm to 2.0 ms / cm, optionally 0.6 ms / cm to 1.5 ms / cm; and / or The separator of any one of claims 1 to 4, wherein the conductivity of the second base film is 0.4ms / cm-2.0ms / cm, optionally 0.8ms / cm-1.5ms / cm.

6. 6. The separator according to claim 1, wherein the ratio of the porosity of the first base film to the porosity of the second base film is 0.4-0.9, and optionally 0.45-0.

65.

7. the porosity of the first base film is 30%-60%, optionally 35%-50%; and / or The separator according to any one of claims 1 to 6, wherein the porosity of the second base film is 25% to 85%, and optionally 40% to 80%.

8. The separator of any one of claims 1 to 7, wherein the ratio of the thickness of the first base film to the thickness of the second base film is 0.5-3.5, and optionally 1.2-2.

5.

9. the thickness of the first base film is 10 μm or less, optionally 2 μm-7 μm; and / or The separator according to any one of claims 1 to 8, wherein the thickness of the second base film is 12 μm or less, and optionally 1 μm-6 μm.

10. the ratio of the melting point of the first base film to the melting point of the second base film is 0.3-0.85, optionally 0.4-0.7; Optionally, the melting point of the first base film is 120°C or higher, and more preferably 125°C-260°C; Optionally, the melting point of the second base film is 150°C or higher, and further optionally 160°C-350°C.

11. The material of the first base film comprises one or more of polyolefins and derivatives thereof, halogenated polyolefins and derivatives thereof, polyethers and derivatives thereof, polyetheretherketones and derivatives thereof, polyesters and derivatives thereof, polyimides and derivatives thereof, polyvinyl alcohols and derivatives thereof; and / or 11. The separator according to claim 1, wherein the material of the second base film includes one or more of polyolefins and derivatives thereof, halogenated polyolefins and derivatives thereof, polyethers and derivatives thereof, polyetheretherketones and derivatives thereof, polyesters and derivatives thereof, polyimides and derivatives thereof, and polyvinyl alcohols and derivatives thereof.

12. The separator of claim 1 , wherein the adhesive layer comprises an adhesive, and optionally, the adhesive layer comprises an adhesive and a filler.

13. 13. The separator of claim 12, wherein the adhesive comprises one or more of polyacrylate, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-trichloroethylene copolymer, polyvinylpyrrolidone, polyvinyl acetate, ethylene-vinyl acetate copolymer, polyethylene oxide, polyarylate, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, polyacrylonitrile, polyvinyl alcohol, polyethylene, polypropylene, starch, and cyanoethyl amylopectin.

14. the filler comprises at least one of inorganic particles, organic particles, and an organic-metallic framework material; Optionally, the inorganic particles include one or more of inorganic particles having a dielectric constant of 5 or more, inorganic particles having ionic conductivity but not storing ions, and inorganic particles capable of generating an electrochemical reaction; Optionally, the organic particles comprise one or more of polycarbonate, polythiophene, polypyridine, polystyrene, polyacrylic wax, polyethylene, polypropylene, cellulose, cellulose modifier, melamine resin, phenolic resin, polyester, silicone resin, polyimide, polyamideimide, polyaramid, polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, polyaryletherketone, copolymer of butyl acrylate and ethyl methacrylate; Optionally, the organic-metal framework material comprises one or more of a nitrogen-containing heterocyclic ligand structure, an organic carboxylic acid ligand structure, and a nitrogen-containing oxygen gas mixture ligand structure.

15. the thickness of the adhesive layer is 0.3 μm or more, optionally 0.5 μm-2 μm; and / or The adhesive strength between the adhesive layer and the first base film is ≧3 N / m, optionally 4 N / m-15 N / m; and / or 15. The separator according to any one of claims 1 to 14, wherein the adhesive strength between the adhesive layer and the second base film is ≧3 N / m, optionally 4 N / m-15 N / m.

16. The content of the adhesive is ≧10%, optionally 30%-50%, based on the total weight of the adhesive layer; and / or The content of the filler is 40%-90%, optionally 60%-80%, based on the total weight of the adhesive layer; and / or The separator according to any one of claims 12 to 15, wherein the volume distribution particle size Dv50 of the filler is 1 µm or less, and optionally 0.3 µm-0.6 µm.

17. The separator satisfies the following conditions (1) to (4): (1) the separator has a flexural index of 1-15, optionally 2-10; (2) the porosity of the separator is 65% or less, and optionally 35%-55%; (3) The separator has a transverse heat shrinkage rate of ≦1.5%, optionally ≦1%, at 250° C. for 1 hour; (4) The separator according to any one of claims 1 to 16, wherein the separator has a longitudinal heat shrinkage rate of ≦1.5% at 250°C for 1 hour, and optionally ≦1%.

18. A secondary battery comprising the separator according to any one of claims 1 to 17.

19. 19. The secondary battery of claim 18, wherein the secondary battery includes a positive electrode plate and a negative electrode plate, the separator is disposed between the positive electrode plate and the negative electrode plate, and a first base film of the separator faces the negative electrode plate and a second base film faces the positive electrode plate.

20. A power consuming device comprising the secondary battery according to claim 18 or 19.

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