Separator and manufacturing method thereof, secondary battery and power consumption device

Abstract

The present application provides a separator, a method for manufacturing the separator, a secondary battery, and a power consuming device. The separator includes a first substrate layer, a mixed material layer, and a second substrate layer, the mixed material layer being disposed between the first substrate layer and the second substrate layer, and the mixed material layer includes an inorganic material and a dispersant. Here, the electronic conductivity σ of the separator is 1×10 -13 mS / cm<σ<1×10 -1 mS / cm. The separator of the present application can delay the occurrence of a situation in which lithium dendrites or sodium dendrites break through the separator, delay the occurrence of a short circuit in the battery, extend the service life of the battery, improve the wettability of the separator to the electrolyte, improve the charge / discharge rate of the battery, improve the thermal shrinkage performance of the battery, improve the safety of the battery, and improve the initial coulombic efficiency of the battery.

Description

[Technical field]

[0001] The present application relates to the field of battery technology, and in particular to a separator, a method for manufacturing the separator, a secondary battery, and a power consuming device. [Background technology]

[0002] In recent years, as the application scope of batteries becomes wider and wider, batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, as well as in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As batteries have made great developments, the requirements for energy density, cycle performance, safety performance, and the like are also increasing. Currently, the separators used in batteries are easily broken through by lithium dendrites or sodium dendrites on the negative electrode plate, which causes short circuit problems in the battery and seriously affects the service life of the battery. In addition, the wettability of the electrolyte of the conventional separator is poor, and the conduction rate of lithium ions or sodium ions is low, which affects the charge and discharge rate of the battery. In addition, the conventional separator is easily subject to significant shrinkage due to heat, which is prone to causing serious safety problems. Summary of the Invention

[0003] The present application has been made in view of the above problems, and aims to provide a separator, a method for manufacturing the separator, a secondary battery, and a power consumption device. By adopting the separator of the present application, it is possible to delay the occurrence of the phenomenon in which lithium dendrites or sodium dendrites break through the separator. This delays the occurrence of short circuits in the battery, and extends the service life of the battery. By adopting the separator of the present application, it is possible to improve the wettability of the separator to the electrolyte, improve the transmission rate of sodium ions or lithium ions, and improve the charge / discharge rate of the battery. The separator of the present application can improve the thermal contraction performance of the battery, and improve the safety of the battery. In addition, the separator of the present application can avoid the consumption of lithium or sodium metal due to the reaction between the inorganic material and the negative electrode, and can improve the initial coulombic efficiency of the battery.

[0004] In order to achieve the above object, a first aspect of the present application provides a separator including a first substrate layer, a mixed material layer, and a second substrate layer. The mixed material layer is provided between the first substrate layer and the second substrate layer, and includes an inorganic material and a dispersant. Here, the electronic conductivity σ of the separator is 1×10 -13 mS / cm<σ<1×10 -1 Meets mS / cm.

[0005] Under the action of an electric field, holes and electrons in the inorganic material undergo orientational movement, making the inorganic material electronically conductive. Inorganic materials have different crystal forms in their structure. Different crystal forms have different effects on electronic conductivity. This allows the same type of inorganic material to exhibit a larger span of electronic conductivity distribution due to differences in structure. When the separator contains an inorganic material, the electronic conductivity of the separator will vary over a wider range as well.

[0006] Thus, the present application adopts a separator that meets a certain electronic conductivity to make the inorganic material in the mixed material layer react with the lithium dendrites or sodium dendrites on the negative electrode plate. This can delay the occurrence of the phenomenon that the lithium dendrites or sodium dendrites break through the separator, delay the occurrence of the internal short circuit of the battery, extend the service life of the battery, and reduce the accumulation of lithium ions on the surface of the separator. This reduces the occurrence of self-discharge and internal short circuit inside the battery. The present application improves the wettability of the separator to the electrolyte by the mixed material layer, improves the transmission rate of sodium ions or lithium ions, and improves the charge and discharge rate of the battery. The present application improves the thermal contraction performance of the battery by adopting the mixed material layer, and improves the safety of the battery. Furthermore, when the negative electrode is lithium metal or sodium metal, the present application separates the mixed material layer and the negative electrode from each other by the first substrate layer or the second substrate layer. This avoids the premature consumption of lithium or sodium metal due to the reaction between the mixed material layer and the negative electrode, and ensures the initial coulombic efficiency of the battery.

[0007] In any embodiment, the inorganic material is selected from one or more of the following (1) to (3). (1) Silicon element, (2) Oxides, nitrides, and fluorides of one or more elements selected from the group consisting of silicon, aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper; (3) Phosphates of one or more elements selected from the group consisting of aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper.

[0008] In any embodiment, the inorganic material is one or more selected from the group consisting of silicon dioxide, silicon oxide, silicon, zinc oxide, tin oxide, copper oxide, iron phosphate, barium titanate, cobalt oxide, manganese oxide, iron oxide, copper nitride, and lithium titanium aluminum phosphate.

[0009] The mixed material layer using the above inorganic material can react with lithium dendrites or sodium dendrites, and can delay the occurrence of the phenomenon in which lithium dendrites or sodium dendrites break through the separator, delay the occurrence of short circuit in the battery, and extend the service life of the battery. The mixed material layer using the above inorganic material can further improve the wettability of the separator to the electrolyte, improve the transmission speed of sodium ions or lithium ions, and increase the charge and discharge rate of the battery. The mixed material layer containing the above inorganic material can further improve the thermal shrinkage performance of the battery, and improve the safety of the battery.

[0010] In any embodiment, based on the total mass of the mixed material layer, the mass content of the inorganic material is 75% to 99.7%, and the mass content of the dispersant is 0.1% to 15%, optionally 0.1% to 5%.

[0011] The above mass content can promote the reaction between the mixed material layer and lithium dendrites or sodium dendrites, and further delay the occurrence of the lithium dendrites or sodium dendrites breaking through the separator, thereby delaying the occurrence of short circuit in the battery and prolonging the service life of the battery, while at the same time keeping the inorganic material uniformly dispersed in the mixed material layer, and ensuring the normal function of the mixed material layer.

[0012] In any embodiment, the particle size D of the inorganic material v 50 and the average pore size of the first base layer is 1:1 to 243:1, and / or the particle size D v The ratio of the pore size of the second base material layer to the average pore size of the second base material layer is 1:1 to 243:1.

[0013] The above range is favorable for the contact of the lithium dendrites or sodium dendrites with the inorganic material particles after the lithium dendrites or sodium dendrites pierce the substrate layer, and is also favorable for the reaction kinetics between the mixed material layer and the lithium dendrites or sodium dendrites. Furthermore, the above range reduces clogging of the ducts on the substrate layer by the inorganic material particles.

[0014] In any embodiment, the dispersing agent is selected from one or more of sodium polyacrylate, ammonium polyacrylate, sodium hexafluorophosphate, sodium carboxymethylcellulose, hydrolyzed polymaleic anhydride, acrylic acid block polymers, polyester block polymers, polyethylene glycol type polyols, polyvinyl alcohol, and polyethyleneimine derivatives.

[0015] This is advantageous for the inorganic material to be uniformly distributed in the mixed material layer, and also facilitates the normal reaction between the mixed material layer and the lithium dendrites or sodium dendrites, and further delays the penetration of the lithium dendrites or sodium dendrites into the separator, delaying the occurrence of battery short circuit caused by lithium or sodium precipitation, and prolonging the service life of the battery.

[0016] In any embodiment, the thickness of the mixed material layer is between 0.5 and 10 μm.

[0017] Optionally, the separator has a thickness of 11 to 24 μm.

[0018] By adopting the above thickness of the mixed material layer and the separator, on the one hand, the mixed material layer can react with the lithium dendrite or sodium dendrite on the negative electrode plate, which can delay the occurrence of the situation where the lithium dendrite or sodium dendrite breaks through the separator, and can delay the occurrence of the battery short circuit caused by lithium deposition or sodium deposition, and on the other hand, the volume occupied by the separator can be reduced, improving the energy density of the core.

[0019] In any embodiment, the mixed material layer further comprises a polymer selected from one or more of styrene butadiene rubber (SBR), water-based acrylic, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0020] Optionally, the weight content of the polymer is 0.1-20%, based on the total weight of the mixed material layer.

[0021] The polymer helps the components in the mixed material layer adhere to each other.

[0022] In any embodiment, a protective layer is further provided on the surface of the first base layer away from the mixed material layer and / or the surface of the second base layer away from the mixed material layer. Optionally, the protective layer contains one or more selected from alumina and boehmite. This can further improve the wettability of the separator to the electrolyte and the high pressure resistance of the separator.

[0023] A second aspect of the present application further provides a method for producing a separator, the method comprising the steps of: coating a first substrate layer with a slurry containing an inorganic material, a dispersant, and an optional polymer to obtain a first substrate layer provided with a mixed material layer; and compounding a second substrate layer on a surface of the mixed material layer remote from the first substrate layer to obtain a separator. The separator comprises a first substrate layer, a mixed material layer, and a second substrate layer, and the mixed material layer is provided between the first substrate layer and the second substrate layer. The mixed material layer comprises an inorganic material, a dispersant, and an optional polymer, and the electronic conductivity σ of the separator is 1×10 -13 mS / cm<σ<1×10 -1 mS / cm. The inorganic material, the dispersant and the polymer are as defined in the first aspect of the present application.

[0024] Thus, the present application allows the mixed material layer to react with the lithium dendrites or sodium dendrites on the negative electrode plate, thereby delaying the occurrence of the phenomenon in which the lithium dendrites or sodium dendrites break through the separator, delaying the occurrence of short circuits in the battery, extending the service life of the battery, and reducing the amount of lithium ions deposited on the separator surface. This reduces the occurrence of self-discharge and internal short circuits inside the battery. The present application uses the mixed material layer to improve the wettability of the separator to the electrolyte, improves the transmission speed of sodium ions or lithium ions, and improves the charge and discharge rate of the battery. The present application uses the mixed material layer to improve the thermal contraction performance of the battery and improves the safety of the battery. Furthermore, when the negative electrode is lithium metal or sodium metal, the present application separates the mixed material layer and the negative electrode from each other by the first substrate layer or the second substrate layer, avoiding the reaction between the mixed material layer and the negative electrode and premature consumption of lithium or sodium metal, and ensuring the initial coulombic efficiency of the battery.

[0025] A third aspect of the present application provides a secondary battery comprising the separator of the first aspect of the present application, or a separator produced by the method of the second aspect of the present application.

[0026] In any embodiment, in the battery, the positive electrode active material comprises one or more selected from the group consisting of lithium iron phosphate, nickel cobalt manganese ternary material, lithium manganate, lithium cobalt oxide, and lithium nickelate, and / or the negative electrode active material comprises one or more selected from the group consisting of graphite, silicon-carbon compounds, silicon oxide, and lithium metal.

[0027] A fourth aspect of the present application provides a power consuming device including the secondary battery of the third aspect of the present application. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Diagram 3] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Diagram 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consuming device in which a secondary battery according to an embodiment of the present application is used as a power source; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, embodiments specifically disclosing the separator and its manufacturing method, secondary battery, battery module, battery pack, and power consumption device of the present application will be described in detail with appropriate reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and duplicated description of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily long and to allow those skilled in the art to easily understand. Note that the drawings and the following description are provided to allow those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0030] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit. The selected lower and upper limits define the boundaries of a particular range. The ranges defined in this way may or may not include the end values, and any combination is possible. That is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is also possible to assume that the ranges are understood to be 60-110 and 80-120. Note that if 1 and 2 are listed as the minimum range values, and 3, 4, and 5 are listed as the maximum range values, the ranges 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5 are all possible. In this application, unless otherwise specified, a numerical range of "a to b" represents any combination of real numbers from a to b. Here, a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" represents combinations of these numerical values. Also, expressing that a parameter is an integer ≧2 is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] Unless otherwise stated, all the embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0032] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0033] Unless otherwise stated, all steps in this application may be performed in sequence, randomly, and preferably in sequence. For example, a method including steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method including a step (c) means that step (c) may be added to the method in any order. For example, the method may be in the order of steps (a), (b), and (c), or in the order of steps (a), (c), and (b), or in the order of steps (c), (a), and (b).

[0034] Unless otherwise stated, the terms "comprise" and "comprises" referred to in this application may be open ended or closed ended. For example, "comprise" and "comprises" may further include or include other ingredients not listed, or may include or include only the listed ingredients.

[0035] 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 in the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); and A and B are both true (or exist).

[0036] [Secondary battery] A secondary battery is also called a rechargeable battery or a storage battery, and refers to a battery that can be continuously used by activating the active material through a charging method after the battery is discharged.

[0037] A secondary battery generally includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. During charging and discharging of the battery, active ions (e.g., lithium ions, sodium ions) move between the positive electrode plate and the negative electrode plate to absorb and release ions. The separator is provided between the positive electrode plate and the negative electrode plate, and mainly serves to prevent short-circuiting between the positive and negative electrodes, while allowing the active ions to pass through. The electrolyte mainly serves to conduct the active ions between the positive and negative electrode plates.

[0038] [Separator] One embodiment of the present application provides a separator including a first substrate layer, a mixed material layer, and a second substrate layer, the mixed material layer being disposed between the first substrate layer and the second substrate layer, the mixed material layer including an inorganic material and a dispersant, wherein the electronic conductivity σ of the separator is 1×10 -13 mS / cm<σ<1×10 -1 mS / cm, and optionally 1×10 -11 mS / cm<σ<1×10 -3 mS / cm, and optionally, 1.5×10 -11 mS / cm<σ<9×10 -4 mS / cm, e.g., 10 -10 mS / cm, 10 -9 mS / cm, 10 -8 mS / cm, 10 -6 mS / cm, 10 -5 mS / cm, 10 -4 mS / cm and any two of the above values ​​as endpoints.

[0039] Under the action of an electric field, the holes and electrons in the inorganic material undergo orientational movement, making the inorganic material electronically conductive. Inorganic materials have different crystal forms in their structures, and different crystal forms have different effects on electronic conductivity. This means that the same type of inorganic material will exhibit a larger range of electronic conductivity distribution due to differences in structure, and when the separator contains an inorganic material, the electronic conductivity of the separator will also vary over a wider range.

[0040] Although the mechanism is not yet fully understood, the applicant has discovered that the end of the lithium dendrite or sodium dendrite on the negative electrode plate breaks through the first substrate layer or the second substrate layer and then contacts the mixed material layer, and the electronic conductivity σ of the separator becomes 1×10 -13 When the electrical conductivity is greater than mS / cm, it is favorable for the reaction between the inorganic material in the mixed material layer and the lithium dendrites or sodium dendrites, thereby delaying the time when the lithium dendrites or sodium dendrites break through the separator, delaying the occurrence of short circuits in the battery, and extending the service life of the battery. Furthermore, when the electronic conductivity σ of the separator is less than 1×10 -1 When the electrical conductivity is less than mS / cm, the amount of lithium ions deposited on the separator surface can be reduced. This reduces the occurrence of self-discharge and internal short circuit inside the battery. Next, the mixed material layer of the present application has a strong affinity for the electrolyte, improving the wettability of the separator to the electrolyte and improving the transmission rate of sodium ions or lithium ions. This improves the charge and discharge rate of the battery. The mixed material layer of the present application is not easily contracted even when heated, improving the thermal contraction performance of the battery and improving the safety of the battery. Furthermore, when the negative electrode is lithium metal or sodium metal, the first substrate layer or the second substrate layer separates the mixed material layer and the negative electrode from each other. This avoids the early consumption of lithium or sodium metal due to the reaction between the mixed material layer and the negative electrode, and ensures the initial coulombic efficiency of the battery.

[0041] In some embodiments, the electronic conductivity σ of the separator can be measured by a conventional method in the art, such as by using lithium iron phosphate as the positive electrode, graphite as the negative electrode, and the intermediate layer as the separator to be measured, and using a thermo-barometer to perform impedance testing at a certain pressure and voltage, and measuring the resistance value R of the separator according to the test area S of the separator. The electronic conductivity σ of the separator is calculated according to the following formula: JPEG2025515798000002.jpg629 where JPEG2025515798000003.jpg54=H×(1-porosity), H is the initial thickness of the separator, JPEG2025515798000004.jpg54 is the corresponding thickness after the separator is subjected to the above pressure to remove the pores. The above porosity test method is to measure the thickness and area of ​​the separator, calculate the apparent volume V of the separator, measure the weight M of the separator, ρ indicates the theoretical density of the substrate in the separator, and calculate the porosity P of the separator according to the following formula. JPEG2025515798000005.jpg1351

[0042] In some embodiments, the inorganic material is selected from one or more of the following (1) to (3): (1) Silicon (2) Oxides, nitrides, and fluorides of one or more elements selected from the group consisting of silicon, aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper. (3) Phosphates of one or more elements selected from the group consisting of aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper.

[0043] In some embodiments, the inorganic material is one or more selected from the group consisting of silicon dioxide, silicon oxide, silicon, zinc oxide, tin oxide, copper oxide, iron phosphate, barium titanate, cobalt oxide, manganese oxide, iron oxide, copper nitride, and lithium titanium aluminum phosphate.

[0044] The mixed material layer using the above inorganic material can react with lithium dendrites or sodium dendrites, delaying the occurrence of the phenomenon that lithium dendrites or sodium dendrites break through the separator, delaying the occurrence of short circuit in the battery, and extending the service life of the battery. The mixed material layer using the above inorganic material further improves the wettability of the separator to the electrolyte, improves the transmission speed of sodium ions or lithium ions, and improves the charge and discharge rate of the battery. The mixed material layer containing the above inorganic material further improves the thermal shrinkage performance of the battery, improving the safety of the battery.

[0045] In some embodiments, the inorganic material has a mass content of 75% to 99.7%, e.g., 98.5%, 94%, 90%, 85%, 80%, 76%, based on the total mass of the mixed material layer, and the dispersant has a mass content of 0.1% to 15%, optionally 0.1% to 5%, e.g., 0.5%, 1%, 4%, 5%, and any two of these endpoints.

[0046] The above mass content can promote the reaction between the mixed material layer and lithium dendrites or sodium dendrites, and delay the occurrence of the lithium dendrites or sodium dendrites breaking through the separator, thereby delaying the occurrence of short circuit in the battery and extending the service life of the battery, while at the same time keeping the inorganic material uniformly dispersed in the mixed material layer, and ensuring the normal function of the mixed material layer.

[0047] In some embodiments, the particle size D of the inorganic material v The ratio of the average pore size of the inorganic material D50 to the average pore size of the first substrate layer is 1:1 to 243:1, for example, 4:1, 5:1, 8:1, 10:1, 11:1, 12:1, 14:1, 15:1, 16:1, 19:1, 20:1, 27:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, 220:1, and any two of these values ​​are end points of the range. And / or the particle size D of the inorganic material v The ratio of 50 to the average pore size of the second base material layer is 1:1 to 243:1, for example, 4:1, 5:1, 8:1, 10:1, 11:1, 12:1, 14:1, 15:1, 16:1, 19:1, 20:1, 27:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 100:1, 120:1, 140:1, 160:1, 180:1, 200:1, 220:1, and ranges formed by any two of these values ​​as endpoints.

[0048] The above range is favorable for the lithium dendrites or sodium dendrites to contact with the inorganic material particles after piercing the substrate layer, and is also favorable for the reaction kinetics between the mixed material layer and the lithium dendrites or sodium dendrites. Furthermore, the above range reduces clogging of the ducts on the substrate layer by the inorganic material particles.

[0049] In some embodiments, the dispersing agent is selected from one or more of sodium polyacrylate, ammonium polyacrylate, sodium hexafluorophosphate, sodium carboxymethylcellulose, hydrolyzed polymaleic anhydride, acrylic acid block polymers, polyester block polymers, polyethylene glycol type polyols, polyvinyl alcohol, and polyethyleneimine derivatives.

[0050] This is advantageous for the inorganic material to be uniformly distributed in the mixed material layer, which facilitates the normal reaction between the mixed material layer and the lithium or sodium dendrites, and delays the lithium or sodium dendrites from breaking through the separator, which delays the occurrence of battery short circuit caused by lithium or sodium precipitation, and extends the service life of the battery. Some of the above dispersants belong to polymers that meet the molecular weight size and distribution requirements of conventional polymer dispersants in the art.

[0051] In some embodiments, the mixed material layer has a thickness of 0.5 to 10 μm, for example, 3 μm.

[0052] Optionally, the thickness of the separator is between 11 and 24 μm, for example, 14 μm, 15 μm, 17 μm, 19 μm, and any two of these values ​​as endpoints.

[0053] By adopting the above-mentioned thickness of the mixed material layer and the separator thickness, on the one hand, the mixed material layer can react with the lithium dendrite or sodium dendrite on the negative electrode plate, which can delay the occurrence of the situation where the lithium dendrite or sodium dendrite breaks through the separator, and can delay the occurrence of the battery short circuit caused by lithium deposition or sodium deposition. On the other hand, the volume occupied by the separator is reduced, and the energy density of the core is improved.

[0054] In some embodiments, the mixed material layer further comprises a polymer selected from one or more of styrene butadiene rubber (SBR), water-based acrylic, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0055] Optionally, the polymer mass content is between 0.1% and 20%, based on the total mass of the mixed material layer, for example, 0.2%, 1%, 1.4%, 10%, and any two of these values ​​forming the endpoints of the range.

[0056] The polymer helps the components in the mixed material layer to adhere to each other. The above polymer meets the conventional requirements in the art for molecular weight and distribution of the polymer that performs the binding function. Optionally, the weight average molecular weight of the polymer is 300,000 to 10 million, for example 500,000.

[0057] In some embodiments, a protective layer is further provided on the surface of the first base layer away from the mixed material layer and / or the surface of the second base layer away from the mixed material layer. Optionally, the protective layer includes one or more selected from alumina and boehmite. This can further improve the wettability of the separator to the electrolyte and the high pressure resistance of the separator.

[0058] In some embodiments, the first substrate layer and the second substrate layer comprise a substrate independently selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fibers.

[0059] The substrate is advantageous in isolating the mixed material layer and the negative electrode from each other, thereby preventing the mixed material layer and the negative electrode from reacting with each other to prematurely consume lithium or sodium metal, thereby improving the initial coulombic efficiency of the battery.

[0060] [Separator manufacturing method] An embodiment of the present application is a method for manufacturing a separator, comprising the steps of: coating a slurry including an inorganic material, a dispersant, and an optional polymer onto a first substrate layer to obtain a first substrate layer having a mixed material layer thereon; and compounding a second substrate layer on a surface of the mixed material layer remote from the first substrate layer to obtain a separator. The separator includes a first substrate layer, a mixed material layer, and a second substrate layer. The mixed material layer is disposed between the first substrate layer and the second substrate layer. The mixed material layer includes an inorganic material, a dispersant, and an optional polymer. The electronic conductivity σ of the separator is 1×10 -13 mS / cm<σ<1×10 -1 mS / cm, and optionally 1×10 -11 mS / cm<σ<1×10 -3 mS / cm, and optionally, 1.5×10 -11 mS / cm<σ<9×10 -4 mS / cm, e.g., 10 -10 mS / cm, 10 -9 mS / cm, 10 -8 mS / cm, 10 -6 mS / cm, 10 -5 mS / cm, 10 -4 mS / cm, and any two of the ranges defined by the endpoints above. The inorganic material, dispersant, and polymer are as defined in [Separator].

[0061] As a result, the ends of the lithium dendrites or sodium dendrites on the negative electrode plate break through the first substrate layer or the second substrate layer and then come into contact with the mixed material layer. -13 When the electrical conductivity is greater than mS / cm, it is favorable for the reaction between the mixed material layer and lithium dendrites or sodium dendrites. This delays the time when the lithium dendrites or sodium dendrites break through the separator, delays the occurrence of short circuits in the battery, and extends the service life of the battery. The electronic conductivity σ of the separator is 1×10 -1 When the electrical conductivity is less than mS / cm, the amount of lithium ions deposited on the separator surface can be reduced, thereby reducing the occurrence of self-discharge and internal short circuit in the battery. The present application uses the mixed material layer to improve the wettability of the separator to the electrolyte, improve the transmission rate of sodium ions or lithium ions, and improve the charge / discharge rate of the battery, and employs the mixed material layer to improve the thermal contraction performance of the battery and improve the safety of the battery. Furthermore, when the negative electrode is lithium metal or sodium metal, the present application separates the mixed material layer and the negative electrode from each other by the first substrate layer or the second substrate layer, avoiding the reaction between the mixed material layer and the negative electrode and premature consumption of lithium or sodium metal, and ensuring the initial coulombic efficiency of the battery.

[0062] [Positive plate] A positive electrode plate generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0063] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of the positive electrode current collector, and a positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0064] In some embodiments, the positive electrode current collector may employ a metal foil sheet or a composite current collector. For example, an aluminum foil may be employed as the metal foil sheet. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymeric material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0065] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries that is well known in the art. For example, the positive electrode active material may include at least one material selected from the group consisting of lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and modified compounds thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of lithium transition metal oxides include lithium cobalt oxides (e.g., LiCoO 2 ), lithium nickel oxide (e.g., LiNiO 2 ), lithium manganese oxide (e.g., LiMnO 2 , LiMn 2 O 4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM 333 (may be abbreviated as "LiNi") 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523 (may be abbreviated as "LiNi") 0.5 Co 0.25Mn 0.25 O 2 (NCM 211 (may be abbreviated as "LiNi") 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622 (may be abbreviated as "LiNi") 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O 2 Examples of lithium-containing phosphates having an olivine structure include, but are not limited to, lithium iron phosphate (e.g., LiFePO 4 (which may be abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon, but are not limited thereto.

[0066] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive. For example, the adhesive may comprise at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin.

[0067] In some embodiments, the positive electrode membrane layer optionally further comprises a conductive agent. By way of example, the conductive agent may comprise at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0068] In some embodiments, the positive plate may be manufactured in the following manner: The above-mentioned components for manufacturing the positive plate, such as the positive active material, conductive agent, adhesive and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive slurry, and the positive slurry is applied to a positive current collector, followed by drying, cold pressing and other processes to obtain a positive plate.

[0069] [Negative plate] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0070] For example, the negative electrode current collector has two surfaces that face each other in the thickness direction of the negative electrode current collector, and the negative electrode film layer is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0071] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, a copper foil may be employed as the metal foil sheet. The composite current collector may include a polymeric base layer and a metal layer formed on at least one surface of the polymeric substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymeric substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0072] In some embodiments, the negative electrode active material may be a negative electrode active material for batteries well known in the art. For example, the negative electrode active material may include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate. The silicon-based material may be selected from at least one of silicon elemental, silicon oxide, silicon carbon composite, silicon nitrogen composite, and silicon alloy. The tin-based material may be selected from at least one of tin elemental, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery may be used. These negative electrode active materials may be used alone or in combination of two or more.

[0073] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive. By way of example, the adhesive may be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0074] In some embodiments, the negative electrode membrane layer optionally further comprises a conductive agent. By way of example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0075] In some embodiments, the negative electrode membrane layer optionally further comprises other auxiliary agents, such as a thickening agent (eg, sodium carboxymethylcellulose (CMC-Na)).

[0076] In some embodiments, the negative plate may be manufactured in the following manner: The above-mentioned components for manufacturing the negative plate, such as the negative active material, the conductive agent, the adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative slurry, and the negative slurry is coated on a negative current collector, followed by drying, cold pressing, and other processes to obtain a negative plate.

[0077] [Electrolyte] The electrolyte serves to conduct ions between the positive and negative plates. The present application does not specifically limit the type of electrolyte, which can be selected according to need. For example, the electrolyte may be liquid, gel, or all solid.

[0078] In some embodiments, the electrolyte is a liquid and includes an electrolyte salt and a solvent.

[0079] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonate), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorobis(oxalato)phosphate, and lithium tetrafluoro(oxalato)phosphate.

[0080] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0081] In some embodiments, the electrolyte solution may further include an optional additive. For example, the additive may include a negative electrode film-forming additive and a positive electrode film-forming additive. The electrolyte solution may further include an additive that can improve some performance of the battery, such as an additive that improves the overcharge performance of the battery, an additive that improves the high temperature or low temperature characteristics of the battery, etc.

[0082] In some embodiments, the positive and negative plates and the separator may be fabricated into an electrode assembly by a winding or lamination process.

[0083] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0084] 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 polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0085] The present application is not particularly limited to the shape of the secondary battery, and the secondary battery may be cylindrical, rectangular, or any other shape. For example, FIG. 1 shows a secondary battery 5 having a rectangular structure as an example.

[0086] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround the bottom plate to form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided to cover the opening to close the receiving cavity. The positive electrode plate, the negative electrode plate and the separator can form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to actual specific needs.

[0087] The secondary battery includes a battery cell type, a battery module type, and a battery pack type. In some embodiments, the battery cells can be assembled into a battery module. The battery module can include one or more battery cells, which can be selected by one skilled in the art depending on the application and capacity of the battery module.

[0088] Fig. 3 shows an example of a battery module 4. As shown in Fig. 3, in the battery module 4, a plurality of battery cells 5 may be sequentially arranged in a row along the longitudinal direction of the battery module 4. Of course, the battery cells 5 may be arranged according to any other method. Furthermore, the plurality of battery cells 5 may be fixed by fasteners.

[0089] Optionally, the battery module 4 may further include a case having an accommodation space in which the plurality of battery cells 5 are accommodated.

[0090] In some embodiments, the battery modules may be further assembled into a battery pack. The number of battery modules included in the battery pack may be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0091] 4 and 5 show an example of a 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 is provided to cover the lower housing 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box according to any manner.

[0092] The present application further provides a power consuming device including the secondary battery provided by the present application. The secondary battery 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 include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships and satellites, energy storage systems, etc.

[0093] As the power consuming device, a secondary battery can be selected according to the usage demand.

[0094] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. A battery pack or a battery module can be adopted to meet the power consuming device's demand for high power and high energy density of secondary batteries.

[0095] [Example] The following describes the examples of the present application. The examples described below are illustrative and are only for interpreting the present application, and should not be understood as limitations on the present application. If no specific techniques or conditions are specified in the examples, they will be performed according to the techniques or conditions described in the literature in the field or the product instructions. For reagents or instruments used, those without the manufacturer's name are all common products that can be purchased commercially.

[0096] Example 1 1. Manufacturing of positive electrode plates The positive electrode active material lithium iron phosphate, adhesive polyvinylidene fluoride (PVDF), and conductive agent acetylene black were dissolved in the solvent N-methylpyrrolidone (NMP) in a mass ratio of 0.9:0.05:0.05, and thoroughly mixed to prepare a positive electrode slurry. The positive electrode slurry was uniformly applied to the positive electrode current collector aluminum foil, which was then dried, cold pressed, and cut to obtain a positive electrode plate.

[0097] 2. Manufacturing of negative electrode plates The negative electrode active material, artificial graphite, the conductive agent, acetylene black, the adhesive, styrene butadiene rubber (SBR), and the thickener, sodium carboxymethylcellulose (CMC-Na), were dissolved in deionized water in a mass ratio of 90%:5%:4%:1%, and thoroughly mixed to prepare a negative electrode slurry. The negative electrode slurry was applied to a negative electrode current collector copper foil, which was then dried, cold pressed, and cut to obtain a negative electrode plate.

[0098] 3. Manufacturing of separators Particle size D v Silicon particles with a particle size of 1 μm, polyvinylidene fluoride (PVDF, weight average molecular weight 500,000), and polyvinyl alcohol as a dispersant were mixed in N-methylpyrrolidone at a mass ratio of 0.985:0.01:0.005 to obtain a mixed slurry with a solid mass content of 50%. The mixed slurry was drawn down onto the surface of a first substrate layer (PP material, average pore size 50 nm) with a thickness of 7 μm to obtain a mixed material layer to be placed on the first substrate layer. Before the mixed slurry was dried, the surface of the mixed material layer away from the first substrate layer and a second substrate layer (PP material, average pore size 50 nm) with a thickness of 7 μm were combined using a press roll method and dried to obtain a separator. Here, the thickness of the mixed material layer was 3 μm.

[0099] 4. Electrolyte production Ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and then LiPF 6The electrolyte solution was prepared by dissolving LiPF 6 The concentration was 1 mol / L.

[0100] 5. Secondary battery manufacturing The positive electrode plate, separator, and negative electrode plate are stacked in this order and wound to obtain an electrode assembly. The electrode assembly is placed in an outer casing, and the above-prepared electrolyte is added. A secondary battery is obtained through processes such as sealing, standing, chemical formation, and aging.

[0101] 6. Button cell battery manufacturing The positive and negative electrodes were made of lithium sheets with a diameter of 18 mm and a thickness of 500 μm, and the intermediate layer between the positive and negative electrodes was the separator described above. An electrolyte solution was dripped onto the electrodes, and 1 mol / L LiPF 6 A 2430-type button cell containing EC / DMC (the volume ratio of EC to DMC was 1:1) was assembled.

[0102] Examples 2 to 34 and Comparative Examples 1 to 5 were carried out in the same manner as Example 1. Parameters different from Example 1 are detailed in Table 1.

[0103] [Table 1] JPEG2025515798000007.jpg250162 JPEG2025515798000008.jpg250117

[0104] Material and battery performance testing (1) Measurement of separator electronic conductivity Measurement method: The positive electrode is a lithium iron phosphate plate (area density 0.025 g / cm 2 The negative electrode was a graphite plate (area density 0.012 g / cm 2 The intermediate layer was the separator to be measured. An impedance test was performed using a thermo-barometer to measure the resistance of the separator at a voltage of 200 V and a pressure of 600 kgf. The electronic conductivity σ of the separator was calculated according to the following formula: JPEG2025515798000009.jpg629 Here, R is the resistance value of the separator, and S is the test area of ​​the separator, i.e., the area of ​​a circle with a diameter of φ14 mm. JPEG2025515798000010.jpg54 = H × (1 - porosity), JPEG2025515798000011.jpg54 is the thickness of the separator after the pores are removed at a pressure of 600 kgf, and H is the initial thickness of the separator.

[0105] The above porosity test method The thickness of the separator was measured using a dial gauge, and the length and width of the separator were measured using a gauge to calculate the area of ​​the separator. Furthermore, the apparent volume V of the separator was calculated, and the weight M of the separator was measured using a balance with 1 / 1000th precision. ρ indicates the theoretical density of the substrate. The porosity P of the separator was calculated using the following formula. JPEG2025515798000012.jpg1351

[0106] (2) Particle size D v 50 measurements Measurement method: A certain amount of deionized water was added to the sample, and the sample was ultrasonicated for 10 minutes. After the sample was completely dispersed, the particle size D of the sample was measured using a laser particle sizer. v 50 was measured.

[0107] (3) Thickness measurement Measurement method: After flattening the sample, the thickness was measured at 10 or more different points with a dial gauge and averaged to obtain the sample thickness.

[0108] (4) Measurement of average pore size Measurement method: Mercury porosimetry was used to measure the average pore size by placing a certain amount of sample into a mercury porosimeter.

[0109] (5) Separator electrolyte absorption test Experimental method: The separator was baked at 100°C for more than 6 hours to thoroughly dry the sample, and the dried separator was cut into samples of a fixed size and their thickness (d) was measured. A capillary with a flat port was fixed to the sample stage and a specified height h of electrolyte (density ρ) was aspirated. The microscope was opened and the lens magnification was adjusted so that the capillary and sample could be clearly seen. The capillary port was brought into contact with the sample, and the capillary liquid level was lowered while measuring with a stopwatch. After the liquid level was lowered, the liquid absorption time t was read and the data was recorded. The average liquid absorption speed v of the separator was calculated according to the formula: JPEG2025515798000013.jpg1449

[0110] (6) Thermal shrinkage experiment of separator Experimental method: The separator was laid flat and cut into a sample of 100mm x 100mm size. The oven was set to 120°C and kept warm for 1 hour, then the sample was placed in and kept warm for 4 hours. The sample was then removed, cooled, and the size of the sample was measured. The thermal shrinkage rate in both directions was calculated, and the average value of both directions was then taken.

[0111] (7) Measurement of short circuit duration The button battery was subjected to a charge-discharge test using a Xinwei charge-discharge tester. First, the battery was left to stand for 10 minutes, and then charged at a current density of 4mA / cm. 2 Charge for 1 hour at 400 V, leave for 10 minutes, and then charge at a current density of 4 mA / cm 2 After discharging at 400 V for 1 hour, the above operation was repeated for multiple cycles. The normal voltage distribution was determined by subtracting the minimum voltage from the maximum voltage in the first charge / discharge process, and if the voltage distribution in the subsequent charge / discharge cycle (the voltage obtained by subtracting the minimum voltage from the maximum voltage in the same cycle) was <0.3 times the normal voltage distribution, the separator was determined to be in a short-circuit state and the cycle was stopped. The operating time at that time was recorded as the short-circuit time.

[0112] The above results are shown in Table 2.

[0113] [Table 2]

[0114] As can be seen from the above results, compared with Comparative Examples 1 to 5, the separator of the present application delays the time when lithium dendrites break through the separator, delays the occurrence of short circuits in the secondary battery, and extends the service life of the battery. Compared with Comparative Examples 1 to 3, the present application improves the wettability of the separator to the electrolyte, improves the transport speed of lithium ions, improves the charge / discharge rate of the battery, improves the thermal shrinkage performance of the separator, and improves the safety of the secondary battery.

[0115] The present application is not limited to the above-mentioned embodiment. The above-mentioned embodiment is an example, and any embodiment having substantially the same configuration as the technical idea and having the same effect within the scope of the technical proposal of the present application is included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiment and other forms constructed by combining some of the components in the embodiment are also included in the scope of the present application, within the scope of the purpose of the present application. [Explanation of symbols]

[0116] 1 battery pack, 2 upper housing, 3 lower housing, 4 battery module, 5 secondary battery, 51 case, 52 electrode assembly, 53 top cover assembly

Claims

1. A separator, a first substrate layer, a mixed material layer, and a second substrate layer; the mixed material layer is provided between the first base layer and the second base layer, the mixed material layer includes an inorganic material and a dispersant; The electronic conductivity σ of the separator is 1×10 －１３ mS / cm<σ<1×10 －１ A separator that satisfies mS / cm.

2. The separator according to claim 1, wherein the inorganic material is one or more selected from the following (1) to (3): (1) silicon element, (2) Oxides, nitrides, and fluorides of one or more elements selected from the group consisting of silicon, aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper; (3) Phosphates of one or more elements selected from the group consisting of aluminum, iron, titanium, cobalt, nickel, manganese, tin, zinc, barium, and copper.

3. 3. The separator according to claim 1, wherein the inorganic material is at least one selected from the group consisting of silicon dioxide, silicon oxide, silicon, zinc oxide, tin oxide, copper oxide, iron phosphate, barium titanate, cobalt oxide, manganese oxide, iron oxide, copper nitride, and lithium titanium aluminum phosphate.

4. The separator according to any one of claims 1 to 3, wherein the mass content of the inorganic material is 75% to 99.7%, and the mass content of the dispersant is 0.1% to 15%, optionally 0.1% to 5%, based on the total mass of the mixed material layer.

5. The particle size D of the inorganic material ｖ and / or the ratio of the average pore size of the first substrate layer to the average pore size of the first substrate layer is from 1:1 to 243:1; and / or The particle size D of the inorganic material ｖ The separator according to any one of claims 1 to 4, wherein a ratio of the average pore size of the second substrate layer to the average pore size of the second substrate layer is 1:1 to 243:

1.

6. The separator according to any one of claims 1 to 5, wherein the dispersant is selected from one or more of sodium polyacrylate, ammonium polyacrylate, sodium hexafluorophosphate, sodium carboxymethylcellulose, hydrolyzed polymaleic anhydride, acrylic acid block polymer, polyester block polymer, polyethylene glycol type polyol, polyvinyl alcohol, and polyethyleneimine derivatives.

7. The thickness of the mixed material layer is 0.5 to 10 μm; Optionally, the separator has a thickness of 11 to 24 μm.

8. the mixed material layer further comprises a polymer selected from one or more of styrene butadiene rubber, water-based acrylic resin, polyvinylidene fluoride, polytetrafluoroethylene, ethylene vinyl acetate copolymer, polyacrylic acid, carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl butyral; Optionally, the mass content of the polymer is 0.1-20%, based on the total mass of the mixed material layer.

9. The separator according to any one of claims 1 to 8, further comprising a protective layer on a surface of the first base material layer remote from the mixed material layer and / or a surface of the second base material layer remote from the mixed material layer, and optionally, the protective layer comprises one or more selected from alumina and boehmite.

10. A method for producing a separator, comprising the steps of: coating a slurry comprising an inorganic material, a dispersant and an optional polymer onto a first substrate layer to obtain a first substrate layer provided with a mixed material layer; and compounding a second base layer on a surface of the mixed material layer away from the first base layer to obtain a separator. the separator includes the first substrate layer, the mixed material layer, and the second substrate layer; The mixed material layer is provided between the first base material layer and the second base material layer, the mixed material layer comprises the inorganic material, the dispersant, and optionally the polymer; The electronic conductivity σ of the separator is: 1×10 －１３ mS / cm<σ<1×10 －１ mS / cm is satisfied, Here, the inorganic material and the dispersant are as defined in any one of claims 1 to 9, and the polymer is as defined in claim 8.

11. A secondary battery comprising the separator according to any one of claims 1 to 9.

12. The positive electrode active material includes at least one selected from lithium iron phosphate, nickel-cobalt-manganese ternary material, lithium manganese oxide, lithium cobalt oxide, and lithium nickel oxide, and / or 12. The secondary battery according to claim 11, wherein the negative electrode active material comprises at least one selected from the group consisting of graphite, silicon-carbon compounds, silicon oxides, and lithium metal.

13. A power consuming device comprising the secondary battery according to claim 11 or 12.

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