Separator, manufacturing method thereof, and secondary battery, battery module, battery pack, and power consumption device using the same

Abstract

The present application provides a separator, comprising a base film and a coating disposed on the base film, the coating comprising a ceramic layer partially embedded in the base film and a pseudo-boehmite layer disposed on the ceramic layer. The separator described in the present application can effectively consume lithium dendrites to prevent them from breaking through the separator, and has low internal resistance. The present application further provides a method for manufacturing the separator, and a secondary battery, a battery module, a battery pack and a power consuming device using the separator.

Description

[Technical Field]

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

[0002] In recent years, the range of applications for lithium-ion batteries has become increasingly broad. They have been widely used in energy storage systems, such as wind, thermal, hydroelectric, and solar power plants, as well as in various fields, including power tools and electric bicycles. A lithium-ion battery typically includes positive and negative electrodes, an electrolyte, and a separator between the positive and negative electrodes. The separator is primarily used to prevent short circuits between the positive and negative electrodes and allow ions to pass freely through the electrodes. Most separators used in conventional technologies are polyolefin films. However, lithium dendrites generated during battery use can penetrate the separator, causing short circuits and posing a safety risk.

[0003] To solve this problem, engineers typically apply an inorganic coating to the separator to prevent lithium dendrites from penetrating through the separator, but applying an inorganic coating often requires a large amount of adhesive, which increases the internal resistance of the separator.

[0004] As can be seen, how to develop a separator that has both good safety performance and low internal resistance is still a problem that researchers need to solve urgently. Summary of the Invention

[0005] The present application has been made in view of the above-mentioned problems, and its object is to provide a separator that can effectively prevent lithium dendrites from breaking through the base film and has low internal resistance.

[0006] A first aspect of the present application provides a separator, the separator comprising: a base film; above and a coating located at the base film, the coating comprising a ceramic layer partially embedded in the base film and a ceramic layer above and a pseudoboehmite layer located at

[0007] The separator described in this application contains a ceramic layer and a pseudo-boehmite layer, which can effectively consume lithium dendrites generated during use of the secondary battery, preventing them from piercing the separator, and improving the safety performance of the corresponding secondary battery. More importantly, by creatively partially embedding the ceramic layer in the base film, the use of a large amount of adhesive can be avoided, thereby effectively reducing the internal resistance of the separator.

[0008] In any embodiment, optionally, the portion of the ceramic layer embedded in the base film comprises 5-100%, optionally 10-100%, and further optionally 50-100% of the total thickness of the ceramic layer.

[0009] When the proportion of the portion of the ceramic layer embedded in the base film to the total thickness of the ceramic layer is within the above range, the molten interface of the base film itself is utilized to effectively bond the ceramic particles, reducing the amount of adhesive used and advantageously reducing the internal resistance of the separator.

[0010] In either embodiment, optionally, the coating further comprises a thermally conductive layer located on a surface of the pseudo-boehmite layer remote from the base film.

[0011] The presence of the thermally conductive layer is advantageous to reduce the occurrence of lithium dendrites at the source and further improve the safety performance of the separator.

[0012] In any embodiment, optionally, the separator comprises: (1) the thickness of the ceramic layer is 0.5 to 10 μm, optionally 2 to 7 μm; (2) the thickness of the base film is 4 to 20 μm, optionally 5 to 12 μm; (3) the thickness of the pseudo-boehmite layer is 0.5 to 10 μm, optionally 2 to 7 μm; (4) The thickness of the heat conduction layer is 0.5 to 2 μm, and optionally 0.5 to 1 μm.

[0013] If the separator satisfies one or more of the above conditions, it is advantageous to further improve the safety performance of the separator and reduce the internal resistance of the separator.

[0014] In any of the embodiments, optionally, the ceramic is selected from one or more of an oxide, nitride, fluoride, or oxyacid salt of Al, Fe, Ti, Co, Zn, Cu, Ni, Mn, or Sn; Optionally, the ceramic is selected from one or more of an oxide of Fe, an oxyacid salt of Fe, an oxide of Ti, an oxyacid salt of Ti, an oxide of Zn, NiO, CuO, or SnO; Further optionally, the ceramic is Fe2O3, FePO4, TiO2, ZnO, Li4Ti5O 12 , NiO, CuO or SnO2.

[0015] In any of the embodiments, optionally, the ceramic is ceramic particles, and the volume average particle size Dv50 of the ceramic particles is ≧100 nm, optionally 100 nm to 5 μm, and further optionally 200 nm to 2 μm.

[0016] When the volume average particle size of the ceramic particles is within the above range, it is advantageous to improve the safety performance of the separator and reduce the internal resistance of the separator.

[0017] In any embodiment, optionally, the pseudo-boehmite layer is selected from one or more of boehmite, alumina, zirconia, or magnesia.

[0018] In any embodiment, optionally, the thermal conductivity of the thermally conductive layer is ≧20 W / (m.K); Optionally, said thermally conductive layer is selected from one or more of boron nitride, tungsten nitride, silicon carbide or aluminum nitride.

[0019] When the heat conductive layer in the separator satisfies the above conditions, it is advantageous to further improve the safety performance of the separator and reduce the internal resistance of the separator.

[0020] In any of the embodiments, optionally, the base film is selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, or natural fibers; Optionally, the base film is selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, or polytetrafluoroethylene.

[0021] A second aspect of the present application provides a method for producing the separator according to the first aspect of the present application, the method comprising: Step 1) melt-processing a mixture containing a separator base film material and a pore-forming agent and extruding it to form a base film A; Step 2) uniformly dispersing ceramic particles on one surface of the base film A to obtain a composite base film; and step 3) uniformly applying pseudoboehmite particles and an optional thermally conductive material to the composite base film obtained in step 2).

[0022] In any embodiment, optionally, the mass ratio of the separator base film material to the pore-forming agent in the mixture in step 1) is 0.1-0.7:1.

[0023] In either embodiment, optionally, step 1) further comprises passing through a cast chill roll after extrusion.

[0024] In any embodiment, optionally, step 2) is performed synchronously with the step of passing through the cast chill roll; or After step 1) is performed, step 2) is performed within 10 seconds to 1 hour, optionally within 1 to 30 minutes, and further optionally immediately.

[0025] In either embodiment, optionally, step 2) further comprises passing through a hot composite roll or drying in an oven.

[0026] In any embodiment, optionally, step 2) comprises: (1) the temperature of the thermal composite roll is 80 to 190°C, optionally 100 to 180°C; (2) The pressure of the thermal composite roll is 5 to 100 MPa, and optionally 10 to 50 MPa.

[0027] In either embodiment, optionally, after performing step 2) and before performing step 3), the method further includes the step of stretching the composite base film.

[0028] In any embodiment, optionally, the method further includes extracting the pore-forming agent in the composite base film after stretching the composite base film.

[0029] A third aspect of the present application provides a secondary battery, the 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.

[0030] A fourth aspect of the present application provides a battery module, the battery module including the secondary battery of the third aspect of the present application.

[0031] A fifth aspect of the present application provides a battery pack, the battery pack including at least one of the secondary battery of the third aspect of the present application or the battery module of the fourth aspect of the present application.

[0032] A sixth aspect of the present application provides a power consumption device, the power consumption device including at least one of the secondary battery of the third aspect of the present application, the battery module of the fourth aspect of the present application, or the battery pack of the fifth aspect of the present application.

[0033] [Beneficial effects]

[0034] The separator described in this application includes a ceramic layer partially embedded in a base film. The ceramic layer effectively consumes lithium dendrites generated during battery use, such as those generated by lithium deposition or accumulation on the negative electrode surface, preventing the lithium dendrites from penetrating the separator and improving safety. At the same time, the ceramic layer is creatively partially embedded in the base film, utilizing the adhesion of the molten interface of the separator's base film itself to bind the ceramic particles, thereby significantly reducing the use of adhesives and preventing a significant increase in the separator's internal resistance.

[0035] The separator described in the present application is above The pseudo-boehmite layer has good thermal stability and can, on the one hand, prevent further growth of lithium dendrites, and, on the other hand, can prevent the reaction between the ceramic and metallic lithium on the electrode surface before lithium dendrites are generated, thereby avoiding excessive loss of lithium in the battery. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a schematic diagram of a separator of the present application. [Figure 2] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 3] FIG. 3 is an exploded view of the secondary battery shown in FIG. 2 according to the embodiment of the present application. [Figure 4] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 5] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 6] FIG. 6 is an exploded view of the battery pack shown in FIG. 5 according to an embodiment of the present application. [Figure 7] 1 is a schematic diagram of a power consumption device in which a secondary battery according to an embodiment of the present application is used as a power source; DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, embodiments specifically disclosing a separator, a manufacturing method thereof, and a secondary battery, a battery module, a battery pack, and a power consumption device using the separator according to 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 redundant description of actually identical structures may be omitted. This is to avoid unnecessarily lengthening 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.

[0038] The "ranges" disclosed herein 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 that define the boundaries of the particular range. Such defined ranges may or may not include the end values, and may be arbitrarily combined; i.e., any lower limit and any upper limit may be combined to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values ​​of 1 and 2 and maximum range values ​​of 3, 4, and 5 are recited, the following ranges are also contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand expression representing all combinations of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed herein, with "0-5" merely being a shorthand notation for combinations of these numbers. Also, describing a parameter as 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.

[0039] Unless otherwise stated, all embodiments and optional embodiments in the present application may be combined with each other to form a new technical solution.

[0040] Unless otherwise stated, all technical features and optional technical features in the present application may be combined with each other to form a new technical solution.

[0041] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, a description of a method including steps (a) and (b) means that the method may include sequential steps (a) and (b), or sequential steps (b) and (a). For example, a description of a method mentioned above that may further include step (c) means that step (c) may be added to the method in any order; for example, 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.

[0042] 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 further include or include other components not listed, or may include or include only the listed components.

[0043] It should be noted that in this application, not all of the ceramic particles embedded in the base film are physically connected to each other and are formed in a continuous state; the ceramic particles may be in a discrete state. The term "ceramic layer" refers to a layer statistically formed from ceramic particles, and is used merely for ease of explanation in contrast to the boehmite layer and the thermally conductive layer. In this application, it is ideal for the ceramic particles to be connected to each other and form a continuous state, which is highly effective in consuming lithium dendrites.

[0044] 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, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0045] In practical work, the inventors discovered that in conventional technologies, inorganic coatings are generally applied to the surface of polyolefin films to prevent lithium dendrites from penetrating the separator and causing further safety risks. However, to prevent the inorganic particles from "falling off," a large amount of adhesive is often used, which leads to a significant increase in the internal resistance of the separator.

[0046] After much research, the inventors have invented a method for partially embedding ceramic particles in a polyolefin-based film and coating a pseudo-boehmite layer on the ceramic particles, which effectively prevents lithium dendrites from penetrating the separator and reduces the internal resistance of the separator. Furthermore, the performance of the separator can be further improved by further controlling the thickness of the ceramic layer and the pseudo-boehmite layer and further modifying the separator with a thermally conductive layer.

[0047] [Separator]

[0048] A first aspect of the present application provides a separator, the separator comprising: a base film; above the coating includes a ceramic layer partially embedded in the base film and a coating located on the base film. above and a pseudoboehmite layer located at

[0049] The separator described in this application includes a ceramic layer partially embedded in a base film. The ceramic layer effectively consumes lithium dendrites generated during battery use, such as those generated by lithium deposition or accumulation on the negative electrode surface, preventing the lithium dendrites from penetrating the separator and improving safety. At the same time, ceramic particles are creatively partially embedded in the base film, utilizing the adhesion of the fusion interface of the separator's base film itself to bind the ceramic particles, significantly reducing the use of adhesives and preventing a significant increase in the separator's internal resistance. Furthermore, the ceramic particles contain many groups that are compatible with the electrolyte, reducing the contact angle with the electrolyte and improving the affinity of the base film for the electrolyte, further improving the electrolyte's infiltration into the base film. Furthermore, ceramics have excellent thermal stability, and combining ceramics with a base film effectively improves the thermal stability of the separator.

[0050] The separator described in the present application is above The pseudo-boehmite layer has good thermal stability and can, on the one hand, prevent further growth of lithium dendrites, and, on the other hand, can prevent the reaction between the ceramic and metallic lithium on the electrode surface before lithium dendrites are generated, thereby avoiding excessive loss of lithium in the battery.

[0051] In some embodiments, optionally, the ceramic layer is partially adhesive-free or adhesive-free.

[0052] In some embodiments, optionally, the amount of adhesive used is 0-10 wt % based on the total weight of the ceramic layer, for example, 0%, 3%, 5%, 7%, or 10%, and ranges consisting of any two of these.

[0053] In some embodiments, optionally, the portion of the ceramic layer embedded in the base film comprises 5-100%, optionally 10-100%, and even optionally 50-100% of the total thickness of the ceramic layer. For example, the thickness of the portion of the ceramic layer embedded in the base film comprises 5%, 10%, 50%, 70%, 80%, or 100% of the total thickness of the ceramic layer, and any two of these ranges.

[0054] When the portion of the ceramic layer embedded in the base film is within the above range, the molten interface of the base film itself is utilized to effectively bond the ceramic particles, which is advantageous in reducing the use of adhesive and reducing the internal resistance of the separator.

[0055] In some embodiments, optionally, the coating further comprises a thermally conductive layer located on a surface of the pseudo-boehmite layer remote from the base film.

[0056] The thermally conductive layer is a highly thermally conductive film, such as hexagonal boron nitride (h-BN), whose main effects are to provide a uniform thermal field environment, avoid localized hot spots, uniformly deposit / dissolve lithium ions, and reduce the occurrence of lithium dendrites. The thermally conductive layer can also reduce the occurrence of lithium dendrites by promoting the formation of an inorganic SEI (Solid Electrolyte Interface) film. At the same time, the thermally conductive layer is an insulator and does not consume active lithium.

[0057] In some embodiments, optionally, the separator comprises: (1) the thickness of the ceramic layer is 0.5 to 10 μm, optionally 2 to 7 μm; (2) the thickness of the base film is 4 to 20 μm, optionally 5 to 12 μm; (3) the thickness of the pseudo-boehmite layer is 0.5 to 10 μm, optionally 2 to 7 μm; (4) The thickness of the heat conductive layer is 0.5 to 2 μm, and optionally 0.5 to 1 μm.

[0058] If the separator satisfies one or more of the above conditions, it is advantageous to further improve the safety performance of the separator and reduce the internal resistance of the separator.

[0059] In some embodiments, optionally, the thickness ratio of the ceramic layer to the pseudo-boehmite layer is 0.05 to 20, optionally 0.28 to 3.5. For example, the ratio may be 5:1, 4:1, 3.5:1, 1:1, 1:3.5, 1:4, or 1:5, and ranges consisting of any two of these.

[0060] In some embodiments, optionally, the ratio of the thickness of the pseudo-boehmite layer to the thermally conductive layer is from 0.25 to 20, optionally from 2 to 14. By way of example, the ratio may be 0.5:1, 1:1, 2:1, 2:0.5, 7:1, or 10:1, and ranges consisting of any two of these.

[0061] When the thickness of the ceramic layer and the pseudo-boehmite layer or the pseudo-boehmite layer and the thermally conductive layer in the separator satisfies the above conditions, it is advantageous to further improve the safety performance of the separator and reduce the internal resistance of the separator.

[0062] In some embodiments, optionally, the ceramic is selected from one or more of an oxide, nitride, fluoride, or oxyacid salt of the elements Al, Fe, Ti, Co, Zn, Cu, Ni, Mn, or Sn; Optionally, the ceramic is selected from one or more of an oxide of Fe, an oxyacid salt of Fe, an oxide of Ti, an oxyacid salt of Ti, an oxide of Zn, NiO, CuO, or SnO; Further optionally, the ceramic is Fe2O3, FePO4, TiO2, ZnO, Li4Ti5O 12, NiO, CuO or SnO2.

[0063] During multiple charge / discharge cycles of a lithium metal battery, lithium dendrites inevitably form. If not controlled, the lithium dendrites will eventually come into contact with and penetrate the separator, causing contact between the positive and negative electrodes and resulting in safety issues. The components contained in the ceramic particles described in this application, such as silica, can induce a lithium absorption reaction and consume the generated lithium dendrites in a timely manner, thereby improving the safety performance of the corresponding battery.

[0064] The reaction mechanism by which the ceramic particles described in the present application consume lithium dendrites may be divided into an alloying reaction mechanism, an intercalation reaction mechanism, and an oxidation-reduction mechanism.

[0065] 1) Alloying reaction mechanism: Metal oxides react with lithium dendrites, resulting in the production of elemental metals. The elemental metals then undergo an alloying reaction to produce lithium alloys. The reaction equation is as follows: JPEG0007739588000001.jpg24100

[0066] For example, tin dioxide first generates elemental tin and Li2O during discharge, and then the elemental tin and Li + reacts with Li 4.4 Sn compounds are produced.

[0067] 2) Intercalation reaction mechanism: During the charge and discharge process, Li + can only be embedded in the gaps between the layers of the material, and the chemical reaction formula for the charge and discharge process is as follows: JPEG0007739588000002.jpg22105

[0068] Typical ceramic materials that use the intercalation reaction mechanism are mainly SiO2, TiO2, lithium titanate, etc.

[0069] 3) Reformation reaction mechanism: Metal oxides are Li + This reacts with LiO to produce elemental metal and Li2O, and the chemical reaction formula is as follows: JPEG0007739588000003.jpg25127

[0070] In some embodiments, optionally, the ceramic is ceramic particles, and the ceramic particles have a volume average particle size Dv50 of ≧100 nm, optionally 100 nm to 5 μm, and further optionally 200 nm to 2 μm.

[0071] If the particle size of the ceramic particles is too large, they may not be embedded in the base film well, which may result in "powder shedding."If the particle size of the ceramic particles is too small, they may clog the voids on the surface of the organic microporous material, reducing the air permeability of the separator and blocking the ion transmission channels, which is unfavorable for reducing the internal resistance of the separator.

[0072] In some embodiments, optionally, the pseudo-boehmite layer is selected from one or more of boehmite, alumina, zirconia, or magnesia.

[0073] In some embodiments, optionally, the thermal conductivity of the thermally conductive layer is ≧20 W / (m.K); Optionally, said thermally conductive layer is selected from one or more of boron nitride, tungsten nitride, silicon carbide or aluminum nitride.

[0074] When the heat conductive layer in the separator satisfies the above conditions, it is advantageous to further improve the safety performance of the separator and reduce the internal resistance of the separator.

[0075] In some embodiments, optionally, the base film is selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, or natural fibers; Optionally, the base film is selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, or polytetrafluoroethylene.

[0076] The separator described in the present application can be produced by a method commonly used in the art. For example, when a commercially available base film is used, the separator described in the present application can be produced by the following method.

[0077] 1) The separator base film is melt-processed and extruded to obtain base film A; 2) uniformly dispersing the ceramic particles on one surface of the base film A obtained in step 1) to obtain a composite base film; 3) Pseudoboehmite particles and an optional thermally conductive material are uniformly applied in order to the composite base film obtained in step 2).

[0078] It should be noted that the melting treatment in step 1) refers to heating the separator base film to 120-250°C to bring it into a molten state so that it can be extruded. The "sequentially" in step 3) refers to first applying a pseudo-boehmite layer, and then applying an optional thermally conductive material to the surface of the pseudo-boehmite away from the ceramic.

[0079] In some embodiments, optionally, after undergoing the melting treatment in step 1), the base film of the separator is in a thermally molten state.

[0080] In some embodiments, optionally in step 1), after melt processing, the separator base film in a molten state is continuously extruded through a co-extrusion system, such as a twin-screw extruder.

[0081] In some embodiments, optionally, the base film A obtained in step 1) is a cast base film in a hot-molten state.

[0082] In some embodiments, optionally, step 1) further comprises passing through a cast chill roll after extrusion.

[0083] In some embodiments, optionally, the temperature of the cast chill roll in step 1) is 90-25°C.

[0084] In some embodiments, step 2) is optionally performed synchronously with the step of passing through the cast chill roll; or After step 1) is performed, step 2) is performed within 10 seconds to 1 hour, optionally within 1 to 30 minutes, and further optionally immediately.

[0085] It should be noted that the term "synchronized" in step 2) means that step 2) is carried out synchronously with the passing of the casting cooling roll in step 1), i.e., sprinkling or spraying powder while forming a film.

[0086] In some embodiments, optionally, in step 2), the ceramic particles may be uniformly dispersed on one surface of the base film A obtained in step 1) by an in-line scattering or spray coating device.

[0087] In some embodiments, optionally, step 2) further comprises passing through a thermal composite roll or drying in an oven.

[0088] In some embodiments, optionally, the temperature of the heated composite roll or oven in step 2) is 80-190°C, optionally 100-180°C.

[0089] In some embodiments, optionally, the pressure of the thermal composite roll in step 2) is 5-100 Mpa, optionally 10-50 Mpa.

[0090] Therefore, in some embodiments, step 2) optionally comprises: (1) the temperature of the thermal composite roll is 80 to 190°C, optionally 100 to 180°C; (2) The pressure of the thermal composite roll is 5 to 100 MPa, and optionally 10 to 50 MPa.

[0091] In some embodiments, in step 2), ceramic particles may optionally be combined with the cast base film A obtained in step 1) by one or more of powder blade coating, sprinkling, solution coating, or high-speed powder spray coating before passing through the thermal composite roll.

[0092] In some embodiments, optionally, in step 3), the pseudo-boehmite particles and the thermally conductive material may be applied by gravure coating or wire bar coating.

[0093] In some embodiments, the ceramic layer optionally includes only a small amount of adhesive (typically a polymer). For example, the adhesive content may be 0 to 10 wt % based on the total weight of the ceramic layer. The adhesive may be selected from one or more materials including polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyacrylate, fluorine-containing acrylate, styrene butadiene rubber, sodium polyacrylate, polymethacrylic acid, polyacrylamide, polyvinyl alcohol, sodium alginate, carboxymethyl chitosan, and sodium carboxymethyl cellulose.

[0094] In some embodiments, optionally, the ceramic layer is adhesive-free.

[0095] For example, when using a polyolefin material, the separator described in the present application can be manufactured in the following manner.

[0096] 1) A mixture containing a separator base film material and a pore-forming agent is melt-processed and extruded to form a base film A; 2) The ceramic particles are uniformly dispersed on one surface of the base film A to obtain a composite base film; 3) Pseudoboehmite particles and an optional thermally conductive material are uniformly applied in order to the composite base film obtained in step 2).

[0097] In some embodiments, optionally, the melting treatment in step 1) refers to heating the separator base film to 120 to 250°C to bring it into a molten state so that it can be extruded. The "sequentially" in step 3) refers to first applying a pseudo-boehmite layer, and then applying an optional thermally conductive material to the surface of the pseudo-boehmite away from the ceramic.

[0098] In some embodiments, optionally, the mass ratio of the separator base film material to the pore-forming agent in the mixture in step 1) is 0.1-0.7:1.

[0099] In some embodiments, optionally, the base film A obtained in step 1) is a cast base film in a hot-molten state.

[0100] In some embodiments, optionally, step 1) further comprises passing through a cast chill roll after extrusion.

[0101] In some embodiments, optionally, the temperature of the cast chill roll in step 1) is 90-25°C.

[0102] In some embodiments, optionally, the pore-forming agent in step 1) may be selected from one or more of mineral oil, propylene carbonate (i.e., 1,2-propanediol carbonate), diethyl carbonate, or ethyl methyl carbonate.

[0103] In some embodiments, step 2) is optionally performed synchronously with the step of passing through the cast chill roll; or After step 1) is performed, step 2) is performed within 10 seconds to 1 hour, optionally within 1 to 30 minutes, and further optionally immediately.

[0104] In some embodiments, optionally, the term "synchronized" in step 2) means that step 2) is performed synchronously with the passing of the casting cooling roll in step 1), i.e., sprinkling or spraying powder while forming the film.

[0105] In some embodiments, optionally, in step 2), the ceramic particles may be uniformly dispersed on one surface of the base film A by an in-line scattering or spray coating device.

[0106] In some embodiments, optionally in step 2), the thermal composite speed of the in-line sprinkling or spray applicator is 0.5-5.0 m / min, optionally 0.5-2.0 m / min.

[0107] In some embodiments, optionally, step 2) further comprises passing through a thermal composite roll or drying in an oven.

[0108] In some embodiments, optionally, the temperature of the heated composite roll or oven in step 2) is 80-190°C, optionally 100-180°C.

[0109] In some embodiments, optionally, the pressure of the thermal composite roll in step 2) is 5-100 Mpa, optionally 10-50 Mpa.

[0110] In some embodiments, optionally, after performing step 2) and before performing step 3), the method further comprises the step of stretching the composite base film.

[0111] In some embodiments, the stretching may optionally be one or more of biaxial asynchronous stretching, biaxial synchronous stretching.

[0112] In some embodiments, the base film may be optionally stretched depending on porosity and strength needs.

[0113] In some embodiments, optionally, the method further comprises extracting the pore-forming agent in the composite base film after stretching the composite base film.

[0114] In some embodiments, optionally, the extractant used is selected from one or more of methylene chloride, trimethyl phosphate, or triethyl phosphate.

[0115] In some embodiments, the pseudo-boehmite particles and thermally conductive material may optionally be applied by gravure coating or wire bar coating.

[0116] In some embodiments, optionally, the separator obtained in step 3) is wound up by a winding system.

[0117] It should be noted that in this application, various factors, such as the temperature of the thermal composite roll and the oven, the speed of passing through the composite roll, the time for coating the ceramic particles after forming the casting base film, the coating amount, or the particle size of the ceramic particles, all affect the embedding degree of the ceramic particles, of which the temperature of the thermal composite roll and the oven and the coating amount have a large effect on the embedding degree, while the influence of other factors is relatively small.

[0118] In some embodiments, the degree of embedding of the ceramic layer in the base film may be optionally adjusted by adjusting the temperature and coating weight of the thermal composite roll and oven.

[0119] [Secondary battery]

[0120] A second aspect of the present application provides a secondary battery, the secondary battery including the separator according to the first aspect of the present application. In general, in addition to the separator, the secondary battery further includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte.

[0121] In particular, the present application may be used in lithium metal batteries as a replacement for conventional separators. The negative electrode may be lithium metal or a lithium alloy, or there may be no negative electrode. Applicable positive electrode materials are as described above. For lithium metal batteries without a negative electrode, the positive electrode material must provide a lithium source.

[0122] The secondary battery may be manufactured by a method commonly used in the art. For example, a positive electrode plate, a negative electrode plate, and a separator may be manufactured as an electrode assembly by a winding process or a lamination process, and an electrolyte may be injected into the electrode assembly and sealed to manufacture the secondary battery.

[0123] It should be noted that the secondary battery described in this application includes a button battery. When the secondary battery is a button battery, the materials of the positive and negative plates may be the same or different. The button battery may be manufactured using a method commonly used by those skilled in the art. For example, the positive plate, separator, and negative plate may be assembled into an electrode assembly, and an electrolyte may be injected into the electrode assembly and sealed to manufacture the button battery.

[0124] The above-mentioned components of the secondary battery will be described below.

[0125] [Positive electrode]

[0126] The positive electrode plate includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. 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 provided on either or both of the two facing surfaces of the positive electrode current collector.

[0127] In some embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0128] In this application, the positive electrode material is Li+ It is a compound that can reversibly store and release

[0129] In some embodiments, the positive electrode active material may be a positive electrode active material for batteries well known in the art. For example, Li x MO2 or Li y Examples include lithium-containing composite oxides represented by MO (where M is a transition metal, 0≦x≦1, 0≦y≦2), spinel-like oxides, metal chalcogenides with layered structures, and olivine structures. For example, lithium cobalt oxides such as LiCoO, lithium manganese oxides such as LiMnO, lithium nickel oxides such as LiNiO, and Li 4 / 3 Ti 5 / 3 Examples include lithium titanium oxides such as O4, lithium manganese nickel composite oxides, lithium manganese nickel cobalt composite oxides, and materials with an olivine crystal structure such as LiMPO4 (M = Fe, Mn, Ni).

[0130] In some embodiments, the positive electrode active material is optionally a lithium-containing composite oxide having a layered structure or a spinel-like structure, such as LiCoO2, LiMn2O4, LiNiO2, LiNi 1 / 2 Mn 1 / 2 Lithium manganese nickel composite oxide, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiNi 0.6 Mn 0.2 Co 0.2 Lithium manganese nickel cobalt composite oxide, typically O2, or LiNi 1-x-y-z Co x Al y Mg z O2 (wherein 0≦x≦1, 0≦y≦0.1, 0≦z≦0.1, 0≦1−xyz≦1). Note that the scope of the present application also includes lithium-containing composite oxides in which some of the constituent elements of the lithium-containing composite oxides are substituted with additional elements such as Ge, Ti, Zr, Mg, Al, Mo, and Sn.

[0131] In addition to the above-mentioned positive electrode active material, other conventional materials that can be used as a positive electrode active material for a battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. For example, by using a lithium-containing composite oxide having a layered structure and a lithium-containing composite oxide having a spinel structure in combination, it is possible to achieve both an increase in capacity and improved safety.

[0132] In some embodiments, the positive electrode membrane layer optionally further comprises a conductive agent, which may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0133] In some embodiments, optionally, the conductive agent comprises 0.05 to 5% of the total weight of the positive electrode membrane layer, optionally 0.5 to 3%.

[0134] In some embodiments, the positive electrode membrane layer optionally further comprises an adhesive, such as an adhesive commonly used in the battery field, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, etc.

[0135] In some embodiments, optionally, the adhesive comprises 0.1 to 3.5%, optionally 0.5 to 2.5%, of the total weight of the positive electrode membrane layer.

[0136] In some embodiments, the positive electrode plate can be manufactured by the following method: The components for manufacturing the positive electrode plate, such as the positive electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied to a positive electrode current collector, followed by drying, cold pressing, and other processes to obtain the positive electrode plate.

[0137] [Negative electrode]

[0138] The negative electrode plate includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector. 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 provided on one or both of the two facing surfaces of the negative electrode current collector.

[0139] In some embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, a copper foil may be used as the metal foil sheet. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer 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, or silver alloy) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0140] In this application, the negative electrode material is lithium metal, a compound capable of absorbing and releasing lithium.

[0141] In some embodiments, the negative electrode active material may be a battery negative electrode active material well known in the art. For example, various materials, such as alloys or oxides of aluminum, silicon, tin, etc., and carbon materials, may be used as the negative electrode active material. Optionally, the oxide may be titanium dioxide, etc., and the carbon material may be graphite, pyrolytic carbon, coke, glassy carbon, a calcined body of an organic polymer compound, mesocarbon microbeads, etc. The tin-based material may be selected from at least one of tin, tin oxide, and tin alloy. However, the present application is not limited to these materials, and other conventional materials usable as negative electrode active materials in batteries may also be used. These negative electrode active materials may be used alone or in combination.

[0142] In some embodiments, the negative electrode film layer optionally further comprises a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0143] In some embodiments, optionally, the conductive agent comprises 0.05 to 5% of the total weight of the negative electrode membrane layer, optionally 0.5 to 3%.

[0144] In some embodiments, the negative electrode membrane layer optionally further comprises an adhesive, such as an adhesive commonly used in the battery field, such as polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polyethylene oxide, etc.

[0145] In some embodiments, optionally, the adhesive comprises 0.1 to 3.5%, optionally 0.5 to 2.5%, of the total weight of the negative electrode membrane layer.

[0146] In some embodiments, the negative electrode membrane layer optionally further comprises other auxiliary agents, such as a thickener (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0147] In some embodiments, the negative electrode plate can be manufactured by the following method: The components for manufacturing the negative electrode plate, such as the negative electrode active material, conductive agent, adhesive, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry, which is then applied to a negative electrode current collector, followed by drying, cold pressing, and other processes to obtain the negative electrode plate.

[0148] [Electrolyte]

[0149] The electrolyte serves to conduct ions between the positive and negative electrodes. The present application does not specifically limit the type of electrolyte, and it can be selected according to needs. For example, the electrolyte may be liquid, gel, or all solid.

[0150] In some embodiments, the electrolyte employs an electrolytic solution, the electrolytic solution including an electrolyte salt and a solvent.

[0151] In some embodiments, a non-aqueous solvent (organic solvent) is used as the non-aqueous electrolyte. Non-aqueous solvents include carbonates, ethers, and the like.

[0152] In some embodiments, the carbonates include cyclic carbonates and chain carbonates. Examples of cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, and sulfur-based esters (ethylene glycol sulfide). Examples of chain carbonates include low-viscosity polar chain carbonates, such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and aliphatic branched carbonate compounds. A mixed solvent of a cyclic carbonate (particularly ethylene carbonate) and a chain carbonate is particularly preferred.

[0153] Examples of ethers include tetraethylene glycol dimethyl ether (TEGDME), ethylene glycol dimethyl ether (DME), and 1,3-dioxolane (DOL).

[0154] In addition to the non-aqueous solvents, other non-aqueous solvents (organic solvents) may be used, such as chain alkyl esters such as methyl propionate, chain phosphate triesters such as trimethyl phosphate, nitrile solvents such as 3-methoxypropionitrile, and branched compounds having an ether bond, typified by dendritic compounds.

[0155] A fluorine-based solvent may also be used.

[0156] Examples of fluorine-based solvents include H(CF2)2OCH3, C4F9OCH3, H(CF2)2OCH2CH3, H(CF2)2OCH2CF3, H(CF2)2CH2O(CF2)2H, etc., or linear (perfluoroalkyl) alkyl ethers such as CF3CHFCF2OCH3 and CF3CHFCF2OCH2CH3, for example, 2-trifluoromethylhexafluoropropyl methyl ether, 2-trifluoromethylhexafluoropropyl ethyl ether, 2-trifluoromethylhexafluoropropyl propyl ether, 3-trifluoromethyloctafluorobutyl methyl ether, 3-trifluoromethyloctafluorobutyl ethyl ether, 3-trifluoromethyloctafluorobutyl propyl ether, 4-trifluoromethyldecafluoropentyl methyl ether, ether, 4-trifluoromethyldecafluoropentyl ethyl ether, 4-trifluoromethyldecafluoropentyl propyl ether, 5-trifluoromethyldodecafluorohexyl methyl ether, 5-trifluoromethyldodecafluorohexyl ethyl ether, 5-trifluoromethyldodecafluorohexyl propyl ether, 6-trifluoromethyltetradecafluoroheptyl methyl ether, 6-trifluoromethyltetradecafluoroheptyl ethyl ether, 6-trifluoromethyltetradecafluoroheptyl propyl ether, 7-trifluoromethylhexadecafluorooctyl methyl ether, 7-trifluoromethylhexadecafluorooctyl ethyl ether, and 7-trifluoromethylhexadecafluorooctyl propyl ether.

[0157] The iso(perfluoroalkyl)alkyl ether may be used in combination with the linear (perfluoroalkyl)alkyl ether.

[0158] The electrolyte salt used in the non-aqueous electrolyte solution is preferably a lithium salt such as lithium perchlorate, organoboron lithium salt, lithium salt of a fluorine-containing compound, or lithium imide salt.

[0159] Examples of such electrolyte salts include LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiCF3SO3, LiCF3CO2, LiC2F4(SO3)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiC n F 2n+1 SO3(n≧2), LiN(R f OSO2)2 (where R f is a fluoroalkyl group). Of these lithium salts, fluorine-containing organic lithium salts are particularly preferred. Fluorine-containing organic lithium salts are highly anionic and easily separate into ions, and therefore are easily dissolved in non-aqueous electrolytes.

[0160] The concentration of the electrolyte lithium salt in the nonaqueous electrolyte solution is, for example, 0.3 mol / L (moles / liter) or more, optionally 0.7 mol / L or more, optionally 1.7 mol / L or less, and optionally 1.2 mol / L or less. If the concentration of the electrolyte lithium salt is too low, the ionic conductivity will be too low, and if it is too high, there is a concern that the electrolyte salt that has not completely dissolved will precipitate.

[0161] In some embodiments, the electrolyte solution optionally further contains additives, and the present application does not particularly limit the scope of the present invention. For example, the additives may include a negative electrode film-forming additive and 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 or an additive that improves the high-temperature or low-temperature performance of the battery.

[0162] [Battery modules, battery packs and power consumption devices]

[0163] A third aspect of the present application provides a battery module, the battery module including the secondary battery of the second aspect of the present application. The battery module may be manufactured using a method commonly used in the art.

[0164] A fourth aspect of the present application provides a battery pack, the battery pack including the battery module of the third aspect of the present application. The battery pack may be manufactured using a method commonly used in the art.

[0165] A fifth aspect of the present application provides a power consumption device, the power consumption device including at least one of the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, or the battery pack of the fourth aspect of the present application.

[0166] The secondary battery, battery module, battery pack, and power consumption device of the present application will be described below with appropriate reference to the drawings.

[0167] In some embodiments, the secondary battery may include an exterior packaging, which may be used to package the electrode assembly and electrolyte.

[0168] In some embodiments, the exterior of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The exterior of the secondary battery may be a flexible package, such as a bag-type flexible package. The flexible package may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0169] In the present application, there is no particular limitation on the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. For example, Fig. 2 shows an example of a secondary battery 5 having a rectangular structure.

[0170] In some embodiments, referring to FIG. 3 , the exterior may include a housing 51 and a cover plate 53. Here, the housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided to cover the opening and close the receiving cavity. The positive electrode plate, the negative electrode plate, and the separator can be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving 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 selected by those skilled in the art according to actual specific needs.

[0171] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0172] Fig. 4 shows an example of a battery module 3. Referring to Fig. 4, in the battery module 4, the secondary batteries 5 may be arranged in order along the vertical direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the secondary batteries 5 may be fastened with fasteners.

[0173] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in the accommodating space.

[0174] 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 one or more, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0175] 5 and 6 show an example of a battery pack 1. Referring to FIGS. 5 and 6, the battery pack 1 may include a battery case and a plurality of battery modules 4 installed in the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 is provided to cover the lower case 3 and can form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0176] The present application also 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 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 include, but is not limited to, mobile equipment (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.), electric trains, ships and satellites, energy storage systems, etc.

[0177] The power consumption device may be a secondary battery, a battery module, or a battery pack, depending on the requirements of the use.

[0178] 7 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. To meet the high power and high energy density requirements of the secondary battery of the power consuming device, a battery pack or a battery module can be adopted.

[0179] Other exemplary devices may be mobile phones, tablet computers, laptop computers, etc. Such devices are generally required to be lightweight and may employ secondary batteries as their power source.

[0180] Example

[0181] Examples of the present application are described below. The examples described below are illustrative and are used only to interpret the present application and should not be understood as limiting the present application. Unless specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in the technical literature or product instructions. Reagents or equipment used without a manufacturer's designation are all common products that can be purchased commercially. Unless otherwise specified, the masses of materials used in the examples do not include water of crystallization.

[0182] 1. Separator

[0183] Example 1 1) Polyethylene (purchased from Sigma-Aldrich, CAS No. 9002-88-4) and mineral oil (pore-forming agent) were uniformly mixed in a weight ratio of 1:10 and heated to 150°C to form a molten state. After die coextrusion, a cast cooling roll at 80°C was used to form a cast base film A with a thickness of 7 μm. 2) In the process of forming the casting base film A by the casting cooling roll in step 1), ZnO particles with a volume average particle diameter Dv50 of 100 nm are uniformly dispersed on one surface of the casting base film A by an in-line spray coating device, and the casting base film A and the ceramic are thermally combined by a thermal combining roll, at a thermal combining temperature of 170°C, a pressure of 10 MPa, and a speed of 1.5 m / min; 3) The composite base film is biaxially synchronously stretched by the stretching system; 4) Using methylene chloride as an extractant, the pore-forming agent in the base film is extracted to obtain a semi-finished composite separator; 5) Alumina (a mixture of alumina and adhesive (polyacrylate, number average molecular weight 9000) in a weight ratio of 0.91:0.04 in deionized water forms a slurry with a solid content of 35%) is uniformly dispersed on the ceramic layer using the wire bar coating method, and the coating thickness after drying is 2 μm. 6) Using the wire bar coating method, boron nitride (a mixture of boron nitride and adhesive (polyvinylidene fluoride, PVDF, number average molecular weight ~ 500,000) in a weight ratio of 0.91:0.04 forms a slurry with a solid content of 35% in deionized water) is uniformly dispersed on the alumina layer, and the coating thickness after drying is 1 μm. 7) Winded up by winding system.

[0184] Except for the following conditions, the production conditions of Examples 2-22 and Comparative Examples 1-3 were similar to those of Example 1, see Table 1 for details.

[0185] Here, the temperature / pressure of the thermal composite roll in Examples 7-9 are 110°C / 0.8MPa, 110°C / 5MPa, and 140°C / 7MPa, respectively.

[0186] 2. Button battery

[0187] Both the positive and negative electrodes used lithium sheets with a diameter (Φ) of 18 mm, and the thickness of the lithium sheets was 250 μm. The intermediate layer was the separator manufactured in the examples and comparative examples. An appropriate amount of electrolyte (enough to completely soak the electrode plates and separator) was then dripped onto the electrodes to assemble a 2430-type button battery. The electrolyte was prepared as follows: Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a 1:1 volume ratio, and LiPF6 was added and stirred until the LiPF6 concentration was 1 mol / L.

[0188] Test methods for relevant parameters

[0189] 1. Particle size test of ceramic particles

[0190] Particle size analysis Dv50: The particle size that occupies 50% of the total volume is larger than this value, and the particle size that occupies 50% of the total volume is smaller than this value. Dv50 represents the median particle size of the powder. When particles are irradiated with a laser beam, the angle of the scattered light is inversely proportional to the particle diameter, and the intensity of the scattered light decreases logarithmically with increasing angle. The energy distribution of the scattered light is directly related to the particle size distribution, and the particle size distribution characteristics can be obtained by accepting and measuring the energy distribution of the scattered light. The reference standard is GB / T19077.1-2009 Particle Size Distribution Laser Diffraction Method.

[0191] 2. Constant voltage test for button batteries

[0192] Test flow: 1mA / cm 2 The button battery was discharged at a constant current to 100 mV, allowed to rest for 10 minutes, and then held at a constant voltage of 100 mV for 5 days. The time during which a stable peak current of 200 to 600 mA was observed was recorded as the time during which the battery system was operating safely and normally, which is the time to short circuit occurrence in Table 1.

[0193] 3. Measurement of the percentage of the thickness of the ceramic layer embedded in the base film that accounts for the total thickness of the ceramic layer

[0194] The separator was quenched using liquid nitrogen to obtain a flat separator cross section, and the thickness of the ceramic layer was measured using a ZEISS sigma 300 scanning electron microscope according to standard JY / T010-1996. The percentage was calculated by dividing the thickness of the ceramic layer embedded in the base film by the total thickness of the ceramic layer and multiplying the result by 100%.

[0195] Other thicknesses in this application can be measured with reference to the above methods.

[0196] 4. Separator ionic conductivity test

[0197] Test procedure: A stacked symmetric battery including a separator was fabricated. The positive plate was a conventional graphite plate, a Cu sheet was used as the current collector, and the electrolyte was the same as that used in button batteries. The frequency range of the AC impedance spectrum test was 1 MHz to 1 kHz, and the amplitude was 5 mV. The separator ionic conductivity (mS / cm) was obtained based on the separator resistance R = ρL / S*n (L, S, and n are the separator thickness, area, and number of layers in the test, respectively).

[0198] [Table 1]

[0199] As can be seen from the results in Table 1, secondary batteries using the separators described herein have excellent safety performance and high ionic conductivity. Without being bound by any theory, the likely cause is that the separators described herein effectively consume lithium dendrites, preventing them from piercing the separator and causing a short circuit, thereby improving the safety performance of the separator. At the same time, high ionic conductivity indicates low internal resistance of the separator, which explains why the technical solution of the present application can simultaneously achieve low separator internal resistance. Furthermore, as can be seen from Table 1, by adjusting the type of ceramic particles and the thickness of each layer, the safety performance of the separator can be further improved and the internal resistance of the separator can be reduced.

[0200] 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 similar functions and effects within the scope of the technical solution of the present application is considered to be within the technical scope of the present application. Furthermore, various modifications that a person skilled in the art may make to the embodiments without departing from the spirit of the present application, and other forms constructed by combining some of the components of the embodiments are also considered to be within the scope of the present application. [Explanation of symbols]

[0201] 1 battery pack, 2 upper case, 3 lower case, 4 battery module, 5 secondary battery, 51 housing, 52 electrode assembly, 53 top cover assembly, 11 base film, 12 ceramic layer, 13 pseudo-boehmite layer, 14 thermally conductive layer

Claims

1. A separator comprising: a base film; and a coating disposed on the base film, the coating comprising a ceramic layer partially embedded in the base film; and a pseudo-boehmite layer disposed on the ceramic layer; the ceramic of the ceramic layer is selected from one or more of oxides of Fe, oxyacid salts of Fe, oxides of Ti, oxyacid salts of Ti, oxides of Zn, NiO, CuO, and SnO 2 ; The pseudo-boehmite layer is selected from one or more of boehmite, alumina, zirconia, or magnesia.

2. 2. The separator according to claim 1, wherein the portion of the ceramic layer embedded in the base film accounts for 5 to 100% of the total thickness of the ceramic layer.

3. 2. The separator of claim 1, wherein the coating further comprises a thermally conductive layer located on a surface of the pseudo-boehmite layer remote from the base film.

4. The separator is (1) The thickness of the ceramic layer is 0.5 to 10 μm; (2) The thickness of the base film is 4 to 20 μm; (3) The thickness of the pseudo-boehmite layer is 0.5 to 10 μm; (4) The separator according to claim 3, which satisfies at least one of the conditions above. (5) The thickness of the heat conductive layer is 0.5 to 2 μm.

5. The ceramics is Fe ２ O ３ , FePO ４ , TiO ２ , ZnO, Li ４ Ti ５ O １２ , NiO, CuO or SnO ２ The separator of claim 1 , wherein the separator is selected from one or more of:

6. 2. The separator according to claim 1, wherein the ceramic is ceramic particles, and the volume average particle diameter Dv50 of the ceramic particles is 100 nm or more.

7. 4. The separator of claim 3, wherein the thermal conductivity of the thermally conductive layer is ≥ 20 W / (m.K).

8. A separator as described in claim 3, wherein the thermally conductive layer is selected from one or more of boron nitride, tungsten nitride, silicon carbide or aluminum nitride.

9. 2. The separator of claim 1, wherein the base film is selected from one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, or natural fiber.

10. A method for producing the separator of claim 1, comprising: Step 1) melt-processing a mixture containing a separator base film material and a pore-forming agent and extruding it to form a base film A; Step 2) uniformly dispersing ceramic particles on one surface of the base film A to obtain a composite base film; and step 3) of uniformly applying pseudo-boehmite particles to the composite base film obtained in step 2), the ceramic particles are selected from one or more of oxides of Fe, oxyacid salts of Fe, oxides of Ti, oxyacid salts of Ti, oxides of Zn, NiO, CuO, or SnO 2 ; The method of claim 1, wherein the pseudo-boehmite particles are selected from one or more of boehmite, alumina, zirconia, or magnesia.

11. 11. The method according to claim 10, wherein the mass ratio of the separator base film material to the pore-forming agent in the mixture in step 1) is 0.1-0.7:

1.

12. 11. The method of claim 10, wherein step 1) further comprises passing the extruded mixture through a cast chill roll.

13. Step 2) is performed in synchronism with the step of passing through the casting chill roll according to claim 12; or The method according to claim 12, wherein step 2) is carried out within 10 seconds to 1 hour after step 1).

14. 11. The method of claim 10, wherein step 2) further comprises passing through a thermal composite roll or drying in an oven.

15. Step 2) is (1) The temperature of the thermal composite roll is 80 to 190°C; (2) The method according to claim 14, wherein the pressure of the thermal composite roll is 5 to 100 MPa.

16. The method of claim 10, further comprising the step of stretching the composite base film after performing step 2) and before performing step 3).

17. 17. The method of claim 16, further comprising extracting the pore-forming agent in the composite base film after stretching the composite base film.

18. A secondary battery comprising the separator according to claim 1.

19. A battery module comprising the secondary battery according to claim 18.

20. A battery pack comprising the secondary battery according to claim 18.

21. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 18, the battery module according to claim 19, and the battery pack according to claim 20.

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