Coated separator, manufacturing method of coated separator, and battery

Abstract

The present invention provides a coated separator, a method for producing the coated separator, and a battery, the coated separator includes a base membrane and a coating layer structure provided on the base membrane, the coating layer structure includes multiple material layers, and the coating layer structure includes one-dimensional nano materials and ceramic particles, and the average length of the one-dimensional nano materials in each material layer is shortened in the direction away from the base membrane. Since the average length of the one-dimensional nano materials in each material layer is shortened in each layer, the formation of large voids that may be caused by the irregular distribution of the one-dimensional nano materials can be avoided. In addition, the coating layer structure can be mixed with the ceramic particles to avoid the stacking density of the one-dimensional nano materials being too large, thereby forming a more effective lithium ion conducting channel, thereby improving the conductivity of lithium ions and effectively improving the performance of the separator and the battery.

Description

[Technical Field]

[0001] The present invention relates to the field of battery separator technology, and more particularly to coated separators, methods for manufacturing coated separators, and batteries. [Background technology]

[0002] The separator is one of the main components of a lithium battery, and its performance has a significant impact on the overall performance of the battery, making it one of the key technologies that restrict the development of lithium batteries. As the application fields of lithium batteries continue to expand and the impact of lithium battery products on people's lives continues to become more profound, people's requirements for the performance of lithium batteries are also increasing. To meet the development requirements of lithium batteries, the separator, as an important component of lithium batteries, not only must have good chemical stability and low manufacturing costs, but further improving the safety performance of lithium-ion batteries is also an important trend in the current development of lithium batteries.

[0003] In conventional related art, a coated separator may include a base membrane and a coating layer coated on at least one surface of the base membrane, and the coating layer may include a one-dimensional nanomaterial. However, the deposition manner of the one-dimensional nanomaterial is disordered and irregular, which is prone to problems such as too many voids and few contact points, thereby affecting the thermal stability of the separator. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a coated separator, a method for manufacturing the coated separator, and a battery in order to improve the performance of the separator. [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided a coated separator comprising a base membrane and a coating layer structure formed on at least one surface of the base membrane, wherein the coating layer structure comprises multiple material layers, the coating layer structure comprises one-dimensional nanomaterials and ceramic particles, and the average length of the one-dimensional nanomaterials in each material layer decreases with each layer along a direction away from the base membrane.

[0006] Alternatively, the thickness of the coating layer in which the ceramic particles are distributed accounts for 80% or more, preferably 90% or more, and more preferably 100% of the total thickness of the coating layer structure.

[0007] Optionally, the mass ratio of the one-dimensional nanomaterial to the ceramic particles in the coating layer structure is 1:1 to 1:14.

[0008] Optionally, the ceramic particles include first ceramic particles and second ceramic particles, wherein the particle diameter of the second ceramic particles is larger than the particle diameter of the first ceramic particles, and the particle diameter of the second ceramic particles is larger than the diameter of the one-dimensional nanomaterial; Furthermore, the particle diameter of the second ceramic particles is at least twice the diameter of the one-dimensional nanomaterial, Furthermore, the particle size of the second ceramic particles and the direct contact of the one-dimensional nanomaterial are diameter and front The first ceramic particles At least one of the particle sizes and One digit End There is a difference between Furthermore, the one-dimensional nanomaterial has a diameter of 5 to 50 nm, the first ceramic particles have an average particle size of 10 to 60 nm, and the second ceramic particles have an average particle size of 100 to 600 nm.

[0009] Optionally, in the coating layer structure, the mass ratio of the first ceramic particles to the second ceramic particles is 5:1 to 1:5.

[0010] Optionally, the first ceramic particles and Before The second ceramic particles At least one of is an inorganic substance that has a melting point of 200°C or higher, is electrically insulating, and is electrochemically stable within the range of use of lithium batteries.

[0011] Optionally, lithium ion conductive functional groups are grafted onto the surfaces of the first ceramic particles; Furthermore, the lithium ion conductive functional group includes any one of hydroxyl (-OH), carbonyl (-C=O), fluorine (-F), and carboxyl (-COOH).

[0012] Optionally, the coating separator comprises at least: a) Puncture resistance of the coating layer force ≧7N, b) ionic conductivity ≥ 0.8; c) Capacity maintenance rate ≧90%, d) Thermal shrinkage at 180℃ / h ≦4%; Satisfy one of the following conditions.

[0013] According to a second aspect of the present invention, there is provided a method for manufacturing a coated separator according to the first aspect and its alternative solution, the method comprising the steps of: particle the dispersion of one-dimensional nanomaterials, the preparation of a paste by mixing, and the formation of a film by coating; ceramics particle In the dispersion of the ceramic particles, the ceramic particles are dispersed in a first solvent. particle A dispersion is obtained, In dispersing one-dimensional nanomaterials, one-dimensional nanomaterials of different lengths are dispersed in the same or different dispersants to obtain at least one one-dimensional nanomaterial dispersion; In the production of paste by mixing, the ceramic particle dispersion liquid and The one-dimensional nanomaterial dispersion by preparing a mixed solution containing , forming at least one corresponding paste; In the film formation by coating, the at least one paste is coated onto at least one surface of the base film, and then dried to obtain the coated separator.

[0014] Optionally, ceramics particle Before dispersion, ceramics particle The method further comprises the step of selecting ceramics particle In the selection step, first ceramic particles and second ceramic particles having different particle sizes are selected, wherein the first ceramic particles have an average particle size of 10 to 60 nm and the second ceramic particles have an average particle size of 100 to 600 nm; Furthermore, ceramics particle The method further comprises the steps of pre-treating the ceramics particle In the pretreatment, the first ceramic particles are added to a second solvent and then placed in a reaction vessel, and a grafting target is added to carry out a grafting reaction, thereby grafting lithium ion conductive functional groups onto the surfaces of the first ceramic particles.

[0015] Optionally, the grafting object includes any one of polycarbonate, polylactic acid, polyurethane, perfluoropropyl vinyl ether, and methyl isopropyl ketone.

[0016] According to a third aspect of the present invention, there is provided a battery comprising a coated separator according to the first aspect and its alternative solutions, or a coated separator manufactured by the method for manufacturing a coated separator according to the second aspect and its alternative solutions, Furthermore, the battery is a lithium battery. [Effects of the Invention]

[0017] In the coated separator, the manufacturing method for the coated separator, and the battery provided by the present invention, the one-dimensional nanomaterials in each material layer have an average length that decreases with each layer and are regularly distributed, thereby avoiding the formation of large voids that can occur due to the disordered and irregular distribution of the one-dimensional nanomaterials. Meanwhile, to prevent the stacking density of the one-dimensional nanomaterials from being too high and affecting lithium ion conduction, the present invention adds ceramic particles to the coating layer structure, resulting in a coating layer structure that is a mixture of one-dimensional nanomaterials and ceramic particles. The addition of ceramic particles prevents the stacking density of the one-dimensional nanomaterials from being too high, thereby forming effective lithium ion conduction channels and thereby improving the lithium ion conductivity and the performance of the separator and battery. [Brief explanation of the drawings]

[0018] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the drawings that need to be used in the description of the embodiments or the prior art will be briefly described below. Of course, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative efforts. [Figure 1] FIG. 2 is a schematic diagram of the local structure of a coating separator in one embodiment of the present invention. [Figure 2] 1 is a flowchart of a method for manufacturing a coated separator in one embodiment of the present invention. [Figure 3] FIG. 1 is a schematic diagram showing a case where the length value of l50 of a material layer varies according to the position of the coating layer in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings according to the embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments thereof. Based on the embodiments of the present invention, all other embodiments that a person skilled in the art can derive without any creative effort shall fall within the scope of protection of the present invention.

[0020] It should be understood that in the description of the present invention, the orientations or positional relationships indicated by the terms "upper", "lower", "upper end", "lower end", "lower surface", "upper surface", etc. are orientations or positional relationships shown based on the drawings, and are intended merely to facilitate and simplify the description of the present invention, and do not indicate or imply that the devices or elements shown must have a specific direction or be configured and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0021] In describing the present specification, it is to be understood that the terms "first" and "second" are for descriptive purposes only and do not indicate or imply the relative importance or number of the technical features indicated, whereby a feature qualified by "first" or "second" may explicitly or implicitly include one or more of the said features.

[0022] In describing the present invention, "plurality" means a large number, for example, two, three, four, etc., unless otherwise specified.

[0023] In the description of the present invention, the term "connection" and the like should be understood in a broad sense unless otherwise clearly specified or limited, and may mean, for example, a fixed connection, a detachable connection, or an integrated structure, a mechanical connection, an electrical connection, or a structure capable of communicating with each other, a direct connection, an indirect connection via an intermediate medium, internal communication between two elements, or an interactive relationship between two elements. Those skilled in the art will be able to understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0024] The technical solutions of the present invention will be described in detail below using specific examples, which can be combined with each other, and the same or similar concepts or processes may be omitted in some examples.

[0025] Before proposing the present invention, the applicant conducted a series of studies and experiments on conventional separators. To solve the problems that the deposition method of one-dimensional nanomaterials in the coating layer is messy and irregular, which is likely to cause too many voids and few contact points, the applicant provides a corresponding solution, in which the length of the one-dimensional nanomaterials is gradually decreased with each coating layer (embodied in the gradual decrease in the length description value of the one-dimensional nanomaterials in each material layer). Because the voids formed by the long nanomaterials are large, the lower the layer, the larger the voids become, and the shorter nanomaterials in the upper layer can fill these voids to a certain extent. When deposited layer by layer, there are not so many voids inside the coating layer, and the number of contact points increases. Therefore, when exposed to heat, the dense structure of the coating layer can suppress the occurrence of thermal deformation of the separator, thereby improving the heat resistance of the coated separator. Regarding this solution, the applicant has also proposed a patent application (application number: PCT / CN2022 / 077087, filing date: 2022.02.21), and this application hereby incorporates the entire contents of PCT / CN2022 / 077087, i.e., the entire contents of PCT / CN2022 / 077087 can be used as support for this application.

[0026] However, in further research, the applicant found that although the above solution can improve the heat resistance of the separator compared to the method in which one-dimensional nanomaterials are randomly arranged, the overall performance of the separator is still not ideal. Length They discovered that a deposition method in which the density of the nanofibers gradually decreases with each layer results in the highest density of the coating layer and the greatest contact between the nanofibers. However, if the deposition density of the one-dimensional nanofibers is too high, it will block the lithium ion conduction channels, affecting the lithium ion conductivity and limiting the separator's performance.

[0027] Based on this discovery, the applicant has obtained the technical solution of the present application through a series of research, testing and verification. Since the regular arrangement of one-dimensional nanofibers is the applicant's main technological innovation, the problems further researched and the solution obtained based on the regular arrangement are also main technological innovations, and the entire research process should be an inseparable part of the solution and should be considered as a whole when assessing the inventive step of the present application.

[0028] Referring to FIG. 1, an embodiment of the present invention provides a coated separator 1, which includes a base film 11 and a At least one surface of and a coating layer structure 12 provided on the base film, the coating layer structure 12 including multiple material layers, one-dimensional nanomaterials and ceramic particles 13 distributed in the coating layer structure 12, the average length of the one-dimensional nanomaterials in each material layer becoming shorter with each layer along the direction away from the base film, and correspondingly, the average size of the voids in the one-dimensional nanomaterials in each material layer also gradually becoming smaller.

[0029] In the present embodiment, the ion conduction rate can be effectively improved by introducing ceramic particles, considering the problem that if the coating layer of one-dimensional nanomaterial is too dense, the voids become too small, resulting in a low ion conduction rate. However, if the one-dimensional nanomaterial is distributed irregularly, , Se Lamix particles Add more When ceramic particles are introduced, they are likely to cause irregular mixing, resulting in small lithium ion conduction channels in some regions and large lithium ion conduction channels in other regions, which leads to a large difference in the conduction speed of lithium ions in different regions, which is likely to cause problems in the growth and development of lithium dendrites (which are likely to cause self-discharge), and further leads to battery capacity degradation and safety issues. In this application, ceramic particles are mixed into the one-dimensional nanomaterial to shorten the average length of the one-dimensional nanomaterial in each material layer, and the use of ceramic particles can prevent the stacking density of the one-dimensional nanomaterial from being too high, thereby forming more effective lithium ion conduction channels, thereby improving the conductivity of lithium ions and effectively improving the performance of the separator and battery.

[0030] In a preferred embodiment, the mass ratio of the one-dimensional nanomaterial to the ceramic particles in the coating layer structure 12 is 1:1 to 1:14. Specifically, the mass ratio of the one-dimensional nanomaterial to the ceramic particles in the coating layer structure 12 may be, for example, any one of 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, or 1:14, or a range between any two of these. Naturally, the mass ratio of the one-dimensional nanomaterial to the ceramic particles in the coating layer structure 12 may be other values, and the specific values ​​are not intended to limit the present invention. Any ratio between 1:1 and 1:14 is considered within the scope of the present invention.

[0031] In a preferred embodiment, the ceramic particles in the coating layer structure 12 include first ceramic particles and second ceramic particles, wherein the particle diameter of the first ceramic particles corresponds to the diameter of the one-dimensional nanomaterial, and the particle diameter of the second ceramic particles is much larger than the diameter of the one-dimensional nanomaterial.

[0032] Specifically, the diameter of the one-dimensional nanomaterial is 5 to 50 nm, the average particle size of the first ceramic particles is 10 to 60 nm, and the average particle size of the second ceramic particles is 100 to 600 nm.

[0033] In an embodiment of the present invention, a layered distribution of one-dimensional nanomaterials and multi-sized ceramic particles is mixed, so that the one-dimensional nanomaterials at the bottom are long and the one-dimensional nanomaterials at the top are short. In the same material layer, Uniformly distributed and different areas Length By reducing the difference between the sizes of the nanofibers, the introduced multi-sized ceramics can sufficiently accelerate the conduction of lithium ions. Here, the layering refers to layers formed by a significant change in the size of the nanofibers in the thickness direction, and may be a plurality of substantially separable layers, or may be an artificial layering based on a significant change in size (for example, a layer may be defined as 10% of the total thickness of the coating layer, or 20%, 30%, 40%, etc. of the total thickness of the coating layer, and the layering may be defined based on the interface where the size change in the structure is significant, but is not specifically limited here).

[0034] In a preferred embodiment, the thickness of the coating layer in which the ceramic particles 13 are distributed in the coating layer structure 12 accounts for 80% or more, preferably 90% or more, and more preferably 100% of the total thickness of the entire coating layer structure, thereby allowing the ceramic particles to be dispersed relatively uniformly in the coating layer structure and more effectively preventing the stacking density of the one-dimensional nanomaterial from being too high, thereby forming more effective lithium ion conduction channels, thereby improving the lithium ion conductivity and effectively improving the performance of the separator and battery.In an even more preferred embodiment, when the coating layer structure has distinct layers, each layer contains ceramic particles, thereby further improving the lithium ion conductivity and improving the performance of the separator and battery.

[0035] By setting the average particle size (D50) of the first ceramic particles to a value equivalent to the diameter of the one-dimensional nanomaterial, the first ceramic particles can expand the voids between the one-dimensional nanomaterial, improving lithium ion conductivity. By setting the average particle size (D50) of the second ceramic particles to be significantly larger than the average particle size of the first ceramic particles and the diameter of the one-dimensional nanomaterial, the coating layer's resistance to external punctures can be improved. Here, "significantly larger" means more than twice as large. As demonstrated by the applicant's research, if the average particle size of the first ceramic particles is too small, they will aggregate excessively, thereby reducing the lithium ion conductivity of the coating. If the average particle size of the first ceramic particles is too large, the voids in the one-dimensional nanomaterial will not be fully filled. If the average particle size of the second ceramic particles is too small, the puncture resistance will be reduced, while if the average particle size of the second ceramic particles is too large, the heat resistance of the coating layer will be sacrificed. Therefore, the average particle size of the first ceramic particles proposed in the present application, which is 10 to 60 nm, and the average particle size of the second ceramic particles, which is 100 to 600 nm, are verified as preferable values.

[0036] In a specific embodiment, the average particle size of the first ceramic particles may be, for example, any one of 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, and 60 nm, or a range between any two of these. The average particle size of the second ceramic particles may be, for example, any one of 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 375 nm, 400 nm, 450 nm, 500 nm, 550 nm, and 600 nm, or a range between any two of these. Of course, the average particle size of the first ceramic particles and the average particle size of the second ceramic particles may be other values, and the specific values ​​do not limit the present invention. As long as the average particle size of the first ceramic particles is 10-60 nm and the average particle size of the second ceramic particles is 100-600 nm, both are considered to be within the scope of the present invention. As those skilled in the art will understand, if the diameter of the one-dimensional nanomaterial changes, the average particle size of the first ceramic particles and the average particle size of the second ceramic particles will also change accordingly. As long as the particle size of the first ceramic particles corresponds to the diameter of the one-dimensional nanomaterial and the particle size of the second ceramic particles is much larger than the diameter of the one-dimensional nanomaterial, neither will deviate from the scope of the present invention.

[0037] In a more preferred embodiment, the mass ratio of the first ceramic particles to the second ceramic particles in the coating layer structure is 5:1 to 1:5, which can further improve the ionic conductivity of the coating layer and the puncture resistance of the coating layer (puncture resistance of the coating layer). force≧7N) and thermal shrinkage performance (180°C / 1h≦4%) can be more effectively ensured. The applicant has found through research that too many first ceramic particles result in poor puncture resistance, while too few first ceramic particles result in limited expansion and reduced lithium ion conductivity, while too many second ceramic particles result in reduced heat resistance, and too few second ceramic particles result in reduced puncture resistance. Therefore, a mass ratio of 5:1 to 1:5 between the first and second ceramic particles in the coating layer structure provided herein has been verified as a preferred value.

[0038] Specifically, the mass ratio of the first ceramic particles to the second ceramic particles in the coating layer structure may be, for example, any one of 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, and 1:5, or a range between any two of these. Naturally, the mass ratio of the first ceramic particles to the second ceramic particles in the coating layer structure may be other values, and the specific numerical values ​​do not limit the present invention, and any ratio between 5:1 and 1:5 is considered to be within the scope of protection of the present invention.

[0039] In a more preferred embodiment, lithium ion conductive functional groups are grafted onto the surface of the first ceramic particles. Specifically, the lithium ion conductive functional groups are introduced onto the surface of the first ceramic particles by a grafting reaction. The lithium ion conductive functional groups contained in large quantities on the surface of the first ceramic particles can significantly improve the lithium ion conductivity. The grafted functional groups are particle It can only act on the surface of the second ceramic Particle Ceramics with the largest particle size Particle Because the particle size is larger, the gaps formed are large. Lithium ion conductive functional group The first ceramic Particle The small particle size results in small gaps, resulting in lithium ion conductivity. functional group The effect of the above is better exhibited, and the lithium ion conductivity is improved.

[0040] The manner in which the length of the one-dimensional nanomaterial in the embodiment of the present invention gradually decreases from layer to layer along the coating layer will be described in more detail as follows.

[0041] Here, the coating layer has three material layers as shown in Figure 1 (here, the layering is defined based on the interface where dimensional change is significant in the coating layer structure), where the one-dimensional nanomaterial in the bottom layer has a longer average length than the one-dimensional nanomaterial in the middle layer, which in turn has a longer average length than the one-dimensional nanomaterial in the top layer. The difference in average length between the one-dimensional nanomaterials in each layer can be set arbitrarily, and the lengths of the one-dimensional nanomaterials in the same layer may be the same or different. In one embodiment, the one-dimensional nanomaterial may be at least one of nanocellulose, aramid nanofiber, and polyimide nanofiber. The material selection of the one-dimensional nanomaterial in the embodiments of the present invention is not limited to the above examples.

[0042] In one embodiment, the same second target occupancy of the one-dimensional nanomaterial in the different material layers results in different length description values; The length description of the one-dimensional nanomaterial in the layer of material is When the number of one-dimensional nanomaterials in the material layer structure is accumulated in order of length from shortest to longest, the ratio of the accumulated number to the total number of one-dimensional nanomaterials in the material layer reaches the second target occupancy ratio, and accordingly, the length of the one-dimensional nanomaterial in the corresponding material layer is smaller than the corresponding length description value. Length The occupancy ratio of one-dimensional nanomaterials can reach the target occupancy ratio, and the above explanation shows the statistical meaning of the length description value of one-dimensional nanomaterials. When actually trying to determine the length description value, the actual calculation method can be processed based on common sense in this field.

[0043] In one example, the second target occupancy ratio is in the range of 5% to 40% or in the range of 60% to 99%. For example, it may be any one of 5%, 10%, 20%, 40%, 60%, 70%, 80%, 90%, and 99%, or a range between any two of these.

[0044] In one embodiment, along a direction away from the base film, for the same second target occupancy ratio, the length description value of the one-dimensional nanomaterial of each layer of material becomes gradually smaller. Length It is possible to form a tendency for the thickness to decrease with each layer.

[0045] Furthermore, with regard to the length description value of the corresponding material layer, the meaning of the length description value is defined above by accumulating and determining the length description value based on the accumulation result, but this does not indicate that this statistical process is necessarily included in the actual manufacturing and acceptance process. In an actual solution, if the length description value rule obtained after stating the one-dimensional nanomaterials in the material layer with numerical values ​​of the same statistical meaning for any product satisfies the above description, it does not deviate from the scope of protection of the embodiment. In some solutions, the satisfaction of the above length rule can be guaranteed by selecting the length of the one-dimensional nanomaterial in advance or manufacturing it according to the length of the one-dimensional nanomaterial.

[0046] where: For the length description values ​​of one-dimensional nanomaterials in a material layer, e.g. The term "l10" refers to the length of the one-dimensional nanomaterial in the material layer, where the ratio of the number of one-dimensional nanomaterials of each length in the corresponding material layer, calculated in order from shortest to longest, to the total number of one-dimensional nanomaterials in the corresponding material layer reaches 10%; The l50 of the one-dimensional nanomaterial in the material layer means the length of the one-dimensional nanomaterial when the ratio of the number obtained by sequentially accumulating the number of one-dimensional nanomaterials of each length in the corresponding material layer in order of shortest length to the total number of one-dimensional nanomaterials in the corresponding material layer reaches 50%, and the l50 can be understood to some extent as indicating the average length of the corresponding material layer. The l90 of a one-dimensional nanomaterial in the material layer means the length of the one-dimensional nanomaterial when the ratio of the number obtained by sequentially adding up the number of one-dimensional nanomaterials of each length in the corresponding material layer in order of shortest length to the total number of one-dimensional nanomaterials in the corresponding material layer reaches 90%.

[0047] When a reduction in l50 (ie, average length) is achieved, a reduction in one or more other length descriptors (eg, l90 and / or l10) may also be achieved.

[0048] In one embodiment, The length value L10 of the one-dimensional nanomaterial in the coating layer structure is between 100 and 300 nm; The length value of L50 of the one-dimensional nanomaterial in the coating layer structure is between 250 and 400 nm; The L90 length value of the one-dimensional nanomaterial in the coating layer structure is between 350 and 900 nm; where: L10 of the one-dimensional nanomaterial in the coating layer structure represents a length description value of the one-dimensional nanomaterial in the coating layer structure when 10% is a first target occupancy ratio; L50 of the one-dimensional nanomaterials in the coating layer structure refers to a length description value of the one-dimensional nanomaterials in the coating layer structure when the first target occupancy ratio is 50%, and may be understood as the average length of the one-dimensional nanomaterials in the coating layer structure; L90 of the one-dimensional nanomaterial in the coating layer structure represents a length description value of the one-dimensional nanomaterial in the coating layer structure when 90% is a first target occupancy ratio; The length description value of the one-dimensional nanomaterial in the coating layer structure is the length of the one-dimensional nanomaterial corresponding to the ratio of the number obtained by sequentially accumulating the number of one-dimensional nanomaterials in the coating layer structure in order of shortest length to the total number of one-dimensional nanomaterials in the coating layer structure reaches the first target occupancy ratio; and the one-dimensional nanomaterial in the coating layer structure satisfies L50 / L10>1.3 and L90 / L50>1.3; L10 of the one-dimensional nanomaterial in the coating layer structure means the length description value of the one-dimensional nanomaterial in the coating layer structure when 10% is the first target occupancy ratio; L50 of the one-dimensional nanomaterial in the coating layer structure means the length description value of the one-dimensional nanomaterial in the coating layer structure when 50% is the first target occupancy ratio; L90 of the one-dimensional nanomaterial in the coating layer structure means the length description value of the one-dimensional nanomaterial in the coating layer structure when 90% is the first target occupancy ratio; The above explanation shows the statistical meaning of the length description value of the coating layer structure, and when actually determining the length description value, the actual calculation method can be handled according to common knowledge in the art.

[0049] Furthermore, with regard to the length description value of the coating layer structure, the meaning of the length description value is defined above by accumulating and determining the length description value based on the accumulation result, but this does not indicate that this statistical process is necessarily included in the actual manufacturing and acceptance process. In an actual solution, if the length description value rule obtained after stating the one-dimensional nanomaterials in the material layer with numerical values ​​of the same statistical meaning for any product satisfies the above description, it does not deviate from the scope of protection of the embodiment. In some solutions, the satisfaction of the above length rule can be ensured by selecting the length of the one-dimensional nanomaterial in advance or manufacturing it according to the length of the one-dimensional nanomaterial.

[0050] In one example, for the one-dimensional nanomaterials in the coating layer structure, L10=110 nm, L50=310 nm, and L90=850 nm.

[0051] The fitting results of the relationship between the l50 length value of the one-dimensional nanomaterial in each material layer and the position in the coating layer where the material layer is located (position in the thickness direction of the coating layer) in the direction away from the base film can be understood by referring to curves 1, 2a, and 2b in Figure 3, and furthermore, in the curves, this l50 length value gradually becomes smaller as the thickness increases (i.e., as the distance between the position in the coating layer where the material layer is located and the base film increases).

[0052] In Figure 3, the position of the coating layer on the horizontal axis indicates the position of the coating layer where the material layer is located in the coating layer structure along the thickness direction, and when expressed as a percentage, it can indicate the percentage of the distance between the position of the coating layer where the material layer is located and the base film in the thickness of the entire coating layer structure, for example, 10% here indicates that the distance between the position of the coating layer and the base film accounts for 10% of the thickness of the entire coating layer structure.

[0053] For curve 1, the l50 length value of the one-dimensional nanomaterial in the material layer changes linearly with the increase in the distance between the coating layer position where the material layer is located and the base film. Good In this case, the relationship between the length value x of l50 and the position Y of the coating layer can be expressed as, for example, Y=kx+b(k<0, b>0), For curve 2a, the l50 length value of the one-dimensional nanomaterial in the material layer can be seen to tend to change faster at first and then slower as the distance between the coating layer position where the material layer is located and the base film increases. For curve 2b, the length value l50 of the one-dimensional nanomaterial in the material layer can tend to change slowly at first and then quickly as the distance between the position of the coating layer where the material layer is located and the base film increases.

[0054] The linear change tendency, the tendency to change quickly at first and then change slowly, or the tendency to change slowly at first and then change quickly can be realized by setting the length of the one-dimensional nanomaterial in the coating layer structure. Furthermore, the length setting of the one-dimensional nanomaterial in the coating layer structure can be selected according to the required change tendency, for example, If it is necessary to realize a linear change (for example, as shown in curve 1), the length setting of the one-dimensional nanomaterial in the coating layer structure must satisfy 2≧L90 / L50>1.5; If it is necessary to realize an initial slow change followed by a fast change (e.g., as shown in curve 2b), the length setting of the one-dimensional nanomaterial in the coating layer structure must satisfy L50 / L10>2, 1.5≧L90 / L50≧1.3. If an initial fast change followed by a slow change (e.g., as shown in curve 2a) is required, the coating layer structure The length setting of the one-dimensional nanomaterial in the nanostructure must satisfy L90 / L50>2.

[0055] Since the prior art does not devise a method for forming a layered structure, the prior art cannot disclose or suggest how to set the length according to different change trends in the above solutions.

[0056] Furthermore, an embodiment of the present invention further provides a battery including a coated separator according to the above alternative solution.

[0057] Also, referring to FIG. 2, an embodiment of the present invention further provides a method for manufacturing a coated separator according to the first aspect and its optional solution, and the manufacturing method includes the following steps S1 to S4.

[0058] S1 Ceramics particle In the dispersion of the ceramic particles, the ceramic particles are dispersed in a first solvent. particle A dispersion is obtained.

[0059] Specifically, ceramic particles are dispersed in a first solvent to obtain a dispersion liquid. The medium , water, N-methylpyrrolidone, ethanol, acetone, etc. It is one of the choices from . ceramic particles The ceramic particles are dispersed uniformly in the solvent using high-speed stirring, high-pressure homogenization, sand mill dispersion, etc., and the mass concentration of the ceramic particles in the dispersion is 2% to 40%.

[0060] In the dispersion of one-dimensional nanomaterials in step S2, one-dimensional nanomaterials of different lengths are dispersed in the same or different dispersants to obtain at least one type of one-dimensional nanomaterial dispersion.

[0061] Specifically, one-dimensional nanomaterials of different lengths are dispersed in a dispersant to obtain a dispersion. The agent , water, N-methylpyrrolidone, ethanol, acetone, etc. It is one of the choices from . 1D nanomaterials The one-dimensional nanomaterials are uniformly dispersed in the dispersant using methods such as high-speed stirring, high-pressure homogenization, and sand mill dispersion, and the mass concentration of the one-dimensional nanomaterials in the dispersant is 2% to 30%.

[0062] Here, one-dimensional nanomaterials of at least partially different lengths are realized depending on the selection of raw materials for the one-dimensional nanomaterials; for example, when one-dimensional nanomaterials made of different materials are selected and used, one-dimensional nanomaterials of different lengths may be formed.

[0063] In another example, one-dimensional nanomaterials of different lengths may be formed by related technological means.

[0064] One-dimensional nanomaterials of at least partially different lengths can be formed by cutting a one-dimensional nanomaterial raw material or a cut one-dimensional nanomaterial one or more times.

[0065] Here, by cutting the one-dimensional nanomaterial, a short one-dimensional nanomaterial can be formed based on a raw material of one length of one-dimensional nanomaterial. For example, the one-dimensional nanomaterial can be cut in half of the raw material, or in other examples, it can be achieved without adopting the half-cutting method.

[0066] Any existing or improved means for achieving cutting of one-dimensional nanomaterials can be used as an embodiment of the present invention. In an embodiment, cutting can be achieved by etching the one-dimensional nanomaterial, for example, by etching the one-dimensional nanomaterial to half its original length.

[0067] Depending on the desired layering, a single cut or multiple cuts can be made to the raw material, for example, by first etching the one-dimensional nanomaterial to half the length of the raw material; Part Half-length one-dimensional nanomaterials are retained, and other portion The one-dimensional nanomaterial is cut to half its length to obtain a one-quarter of its length, at which point a three-layer structure can be formed; in other examples, a portion of the one-quarter of the length of the one-dimensional nanomaterial may be cut, and the number of cuts can be set as desired.

[0068] Naturally, One Other raw materials for 1D nanomaterials One 1D nanomaterial Joining to one end of the raw material, One of bonded one-dimensional nanomaterials, One 1D nanomaterial Joining to one end of the raw material, One Other applications of bonded 1D nanomaterials One At least one bonding step may be performed, whereby the bonded one-dimensional nanomaterial is bonded to one end thereof, and one or more bondings may be performed to form one-dimensional nanomaterials of at least partial different lengths.

[0069] In this way, the object of joining is One 1D nanomaterial One end of the raw material and the other One 1D nanomaterialIt may be a part of the raw material, One 1D nanomaterial It may be one end of a raw material and one end of a bonded one-dimensional nanomaterial, or one end of a bonded one-dimensional nanomaterial and one end of another bonded one-dimensional nanomaterial.

[0070] Here, by joining to the one-dimensional nanomaterial, a long one-dimensional nanomaterial can be formed based on one length of one-dimensional nanomaterial raw material, for example, two One-dimensional nanomaterials By joining the raw materials, one-dimensional nanomaterials of double length may be formed, and in other examples, different lengths may be formed. One-dimensional nanomaterials This may be achieved using raw materials (or grafted 1D nanomaterials).

[0071] Any existing or modified means capable of achieving the joining of one-dimensional nanomaterials may be embodied in an embodiment of the present invention.

[0072] For example, the conjugation of one-dimensional nanomaterials may be realized based on materials with a high content of hydroxyl functional groups (e.g. polyethylene glycol PEG), in which case the conjugation mentioned above can be achieved by Mixing the one-dimensional nanomaterial to be conjugated and a material containing a large amount of hydroxyl functional groups (e.g., PEG) in a solution; adding molecular sieve particles to the solution as a catalyst; heating and cooling the solution and filtering off the molecular sieves to obtain the grafted one-dimensional nanomaterial.

[0073] In a specific example, nanocellulose is used as an example. S The end region has a significantly higher hydroxyl content than the middle region. The activity of hydroxyls can be fully utilized to increase the length of nanocellulose. (1) Nanocellulose is mixed with polyethylene glycol (PEG), and the molecular weight of PEG is 50,000 to 1,000,000 g / mol. PEG is the molecular weight of nanocellulose. Mass1% and thoroughly mix the two to form a corresponding solution. (2) adding 13A molecular sieve particles to the solution, the particle size being 1 mm to 10 mm, and the molecular sieve is a catalyst; (3) 80 over 1-2 hours ℃ to water bath Heat with (4) After cooling to room temperature and filtering out the 13A molecular sieve particles, the grafted nanocellulose is obtained.

[0074] In the above solution, nanocellulose can be crosslinked by adding a material containing a large amount of hydroxyl functional groups (e.g., PEG). The polymerization reaction between PEG and nanocellulose can be accelerated by using a molecular sieve (e.g., 13A molecular sieve) as a catalyst, ultimately forming a nanocellulose-PEG-nanocellulose structure. Depending on the desired layering, the raw material can be conjugated once or multiple times. For example, the raw material 1D nanomaterial can be conjugated twice as long as the raw material, and some of the double-length one-dimensional nanomaterials can be reserved. The other double-length one-dimensional nanomaterial can then be conjugated to the raw material or the double-length one-dimensional nanomaterial to obtain a triple- or quadruple-length one-dimensional nanomaterial, forming a three-layer structure. In other cases, further conjugation can be performed, and the number of conjugations can be freely selected as needed.

[0075] In one solution of step S2, one-dimensional nanomaterials of various lengths may be dispersed in the same dispersant, thereby realizing layering after coating based on pastes corresponding to the same dispersant; in another solution of step S2, different dispersants may be formed based on one-dimensional nanomaterials of different lengths (the lengths of the one-dimensional nanomaterials in different dispersants are different), thereby forming different dispersions and pastes, and during coating, different pastes may be coated layer by layer based on the length of the one-dimensional nanomaterials.

[0076] As an example, in step S2, one-dimensional nanomaterials of various lengths may be sufficiently dispersed in a dispersant, and the dispersion The agent , such as water, ethanol, methanol, etc. It is one of the choices from Dispersion methods include, for example, ultrasonic treatment, high-speed stirring, high-pressure homogenization, and sand mill dispersion. The distribution method is as follows. By adopting 1D nanomaterials Disperse evenly in the dispersant do. The concentration in the one-dimensional nanomaterial dispersion may range from 0.01 to 50 wt %.

[0077] In the preparation of a paste by mixing S3, particle dispersion liquid and The one-dimensional nanomaterial dispersion by preparing a mixed solution containing , forming at least one corresponding paste.

[0078] Specifically, the ceramics obtained in S1 particle The dispersion is mixed with the one-dimensional nanomaterial dispersion obtained in S2, using methods such as high-speed stirring, high-pressure homogenization, and sand mill dispersion. Next, an adhesive is added to the mixed solution. The adhesive is at least one of polyvinyl alcohol, polyacrylonitrile, polyacrylic acid, styrene butadiene rubber, carboxymethyl cellulose, polyvinylidene fluoride, polyvinylpyrrolidone, and polyimide. The adhesive is In a mixed solution of ceramic particle dispersion and one-dimensional nanomaterial dispersion It accounts for 1% to 10% of the solid mass.

[0079] In the film formation by coating in S4, the base film is coated with at least one paste, and the base film and the paste are dried to obtain the coated separator.

[0080] Specifically, the prepared paste is coated onto a base film and then dried to obtain a coated separator, which can be achieved by spray coating, dip coating, microgravure coating, print coating, press coating, or wire bar coating. EitherThe base film is, for example, a polyolefin base film, and has a thickness of 3 to 30 microns. The drying temperature is 40 to 130°C. ℃ The coating speed is 10 to 200 m / min.

[0081] Here, as a preferred embodiment, ceramics particle Before the dispersion, further includes S11 to S12, S11 Ceramics particle In the selection step, first ceramic particles and second ceramic particles having different particle sizes are selected, wherein the first ceramic particles have an average particle size of 10 to 60 nm and the second ceramic particles have an average particle size of 100 to 600 nm; S12 ceramics particle In the pretreatment, the first ceramic particles are added to a second solvent and then placed in a reaction vessel, and a grafting target is added to carry out a grafting reaction to graft lithium ion conductive functional groups onto the surfaces of the first ceramic particles. Specifically, the first ceramic particles are added to a second solvent, and then all of the solvents are placed in a reaction vessel, and the grafting target is added. The lithium ion conductive functional groups can be grafted onto the first ceramic particles at a certain reaction temperature, pressure, and time.

[0082] The first ceramic is not particularly limited, and is preferably a material having a melting point of 200°C or higher, high electrical insulation, and electrochemical stability within the range of use of a lithium battery. Examples include oxide ceramics such as alumina, silica, titanium oxide, zirconia, magnesia, ceria, yttria, and zinc oxide, nitride ceramics such as silicon nitride, titanium nitride, and boron nitride, silicon carbide, calcium carbonate, magnesium sulfate, aluminum sulfate, basic alumina (aluminum hydroxide oxide), potassium titanate, talc, kaolinite, kaolin, nacrite, halloysite, pyrophyllite, montmorillonite, sericite, mica, amesite, bentonite, asbestos, zeolite, calcium silicate, magnesium silicate, diatomaceous earth, and silica sand. These may be used alone or in combination.

[0083] Second ceramics particle The second solvent is not particularly limited, and is preferably a material having a melting point of 200°C or higher, high electrical insulation, and electrochemically stable within the range of use of a lithium battery, and may be the same or different inorganic material as the first ceramic. The second solvent may be water, ethanol, acetone, NMP, etc. Either The grafting target is polycarbonate, polylactic acid, polyurethane, perfluoropropyl vinyl ether, methyl isopropyl ketone, etc. Either The reaction temperature is 100-200°C, the reaction pressure is 0.1-0.5 MPa, and the reaction time is 10-50 min. After the reaction is completed, the liquid solvent is removed to leave a solid, which is then used as a lithium ion conductive material. functional group The first ceramic particles having the grafted thereon can be obtained.

[0084] Based on this, the ceramics in S1 particle Specifically, the variance of The first ceramic particles pretreated in S12 are mixed with the second ceramic particles and then dispersed in a first solvent to form a ceramic particle The aim is to obtain a dispersion.

[0085] The product performance of several embodiments of the present invention will be analyzed through experiments below.

[0086] Example 1 In this example, a coated separator is obtained by manufacturing in accordance with the following steps S1 to S5.

[0087] S1 Ceramics particle In the selection step, first ceramic particles and second ceramic particles having different particle sizes are selected, wherein the first ceramic particles have an average particle size of 40 nm and the second ceramic particles have an average particle size of 300 nm, and particle and second ceramics particle All were alumina.

[0088] S2 Ceramics particle In the dispersion of the second ceramic particles and the first ceramic particles, the second ceramic particles and the first ceramic particles are mixed in a ratio of 1:1, and the mixture is uniformly dispersed in N-methylpyrrolidone by a high-speed stirring method. particle A dispersion liquid was obtained. Ceramics particle The mass concentration of in the dispersion was 20%.

[0089] In the dispersion of one-dimensional nanomaterials (S3), one-dimensional nanomaterials of different lengths were dispersed in a dispersant to obtain a dispersion. The dispersant was N-methylpyrrolidone, the dispersion method was high-speed stirring, and the mass concentration of the one-dimensional nanomaterials in the dispersant was 15%.

[0090] In the paste production by mixing S4, the ceramics obtained in S2 particle The dispersion is mixed with the one-dimensional nanomaterial dispersion obtained in S3, Form a mixed solution, The mixing method is high-speed stirring, and then the adhesive is added to the mixed solution. The adhesive is polyvinyl alcohol, and the adhesive is mixed solution It accounted for 8% of the solid mass in the mixture.

[0091] In the film formation by coating S5, the at least one paste is coated on a base film by coating method, and the base film and the paste are dried to obtain the coated separator. Here, the base film is a polyethylene base film, the thickness is 9 microns, and the drying temperature is 100 ℃ The coating speed was 100 m / min. The thickness of the resulting coating layer was 2 microns.

[0092] Here, the one-dimensional nanomaterial is , Be The nanomaterials are deposited on the surface of the base film, forming a layered structure (i.e., layered 1D nanomaterials of different lengths). During the process of deposition on the base film, due to the surface energy, the longest 1D nanomaterials (which have the largest surface energy, are the most unstable, and are most likely to adhere once they come into contact with an interface with a low surface energy) are deposited first, followed by the second longest, and finally the shortest. 1D nanomaterials was deposited last, and thus a layered structure was formed in which the layers were gradually deposited in order of length.

[0093] Examples 2 to 29 and Comparative Examples 1 to 5 were obtained using the same method, and the performance of the corresponding separators obtained in Examples 1 to 29 and Comparative Examples 1 to 5 is shown in Table 1. Except for the differences in the manufacturing parameters shown in Table 1, all Examples and Comparative Examples are identical to Example 1 in other respects, and therefore, the description is omitted.

[0094] However, Example 30 shown in Table 1 is S 1 Ceramics particle Before dispersion, ceramics particle The only difference from Example 1 is that the pretreatment step was performed. particleIn the pretreatment step, the first ceramic particles are added to the second solvent, and then the mixture is placed in a reactor. The grafting material is then added, and the reaction temperature, pressure, and time are maintained constant to graft the lithium ion conductive functional groups onto the first ceramic particles. The second solvent is acetone, and the grafting material is polycarbonate. The reaction temperature is 150°C, the reaction pressure is 0.3 MPa, and the reaction time is 20 minutes. After the reaction is complete, the liquid solvent is removed, leaving a solid, which is then used as a lithium ion conductive material. functional group The first ceramic particles having the grafted thereon can be obtained.

[0095] [Table 1-1] [Table 1-2] [Table 1-3]

[0096] As can be seen from Table 1, comparing Examples 1 to 8, when there was too much one-dimensional nanomaterial (Example 8), the lithium ion conductivity of the coated separator was much lower than other ratios, and when there was too much ceramic particles (Example 7), the battery capacity retention rate of the coated separator decreased and the thermal shrinkage decreased. When the ratio of one-dimensional nanomaterial to ceramic was (1:1 to 1:14), as the ceramic proportion increased, the battery capacity retention rate at high temperatures gradually decreased, the lithium ion conductivity gradually increased, the puncture resistance gradually improved, and the heat resistance gradually decreased. The main reason for this phenomenon is that as the ceramic particle proportion increased, coating The voids between the layers can be further expanded, further improving lithium ion conductivity, but larger voids result in stronger self-discharge and a decrease in high-temperature storage capacity. Furthermore, the expanded voids reduce contact between the coating layer materials, reducing heat resistance in a hot environment. Furthermore, the puncture resistance of ceramic particles is superior to that of one-dimensional nanomaterials, improving puncture resistance.

[0097] As can be seen from the comparison of Examples 9 to 14, in the ceramics, the second ceramic particles (submicron ceramics particle As the proportion of the first ceramic particles (nanoceramics) increased (Examples 9 to 13), the lithium ion conductivity of the coated separator gradually increased, the battery capacity retention rate gradually decreased, the puncture resistance gradually increased, and the heat resistance remained unchanged. However, particle When the content of ) is too high (Example 9), the lithium ion conductivity of the coated separator is low and the puncture resistance is poor. The first Lamix particle When the content of was too low (Example 14), the heat resistance of the coated separator increased. The main cause of this phenomenon is Second Se Lamix particle is advantageous to increase the large porosity of the coating layer, which can improve the conductivity of the lithium battery; and Particle size big Second Ceramic particles have excellent puncture resistance, but the voids are large. too much This increases self-discharge, causing a decrease in capacity when stored at high temperatures, and the coating layer in Material-to-material contact Number of points The problem is that the heat resistance in a hot environment decreases.

[0098] As can be seen from the comparison of Examples 15 to 27, 1st ceramic Particle When the particle size is too small (Example 24), the ionic conductivity of the coated separator becomes low, 1st ceramics Particle When the particle size is too large (Example 25), the battery capacity retention rate of the coated separator decreases. Second ceramics particle When the particle size is too small (Example 26), the ionic conductivity of the coated separator decreases and the puncture resistance decreases. Second ceramics particleWhen the particle size was too large (Example 27), the battery capacity retention rate of the coated separator decreased and the heat resistance also decreased. The main causes of this phenomenon are: 1st ceramics particle If the particle size of First ceramic particles The aggregation problem becomes more severe, the lithium ion conduction channel becomes narrower, and the ionic conductivity becomes lower. 1st ceramics particle If the particle size of the submicron ceramic is too large, the voids in the coating layer will become larger, further increasing self-discharge and reducing the battery capacity retention rate. If the particle size of the submicron ceramic is too small, the voids in the coating layer will become narrower, reducing ionic conductivity and reducing the ability to withstand external punctures due to the small size. If the particle size of the submicron ceramic is too large, the voids in the coating layer will increase rapidly, resulting in a reduction in the battery capacity retention rate. In addition, the voids will be too large, and the coating separator will When exposed to heat This makes it easier for voids to shrink, and on a macro level this is embodied in a decrease in heat resistance.

[0099] As can be seen from Comparative Examples 1 and 2, when only one-dimensional nanomaterials are present in the coating layer, the coated separator has excellent heat resistance but poor lithium ion conductivity and puncture resistance. When only nanoceramics are present in the coating layer, the coated separator has poor heat resistance and puncture resistance, but excellent lithium ion conductivity. When only submicron ceramics are present in the coating layer, the coated separator has significantly poorer heat resistance and lower lithium ion conductivity, but high puncture resistance. As can be seen from the comparison of Examples 1 to 8, the one-dimensional nanomaterials and ceramics particle When the ratio was greater than 1:1 (Example 8), the lithium ion conductivity and puncture resistance of the coated separator were not improved. particle When the ratio was lower than 1:14 (Example 7), the lithium ion conductivity and puncture resistance of the coated separator were significantly improved, but the heat resistance was clearly reduced. particleand second ceramics particle When the ratio exceeds 6:1 (Example 9), the coated separator has high heat resistance and lithium ion conductivity, but the puncture resistance is reduced. particle and second ceramics particle When the ratio was less than 1:6 (Example 13), the heat resistance and puncture resistance of the coated separator improved, but the lithium ion conductivity decreased. One-dimensional nanomaterial, first ceramic particles, and second ceramic particles of Between Only when the ratio is within a certain range, the coated separator shows the best overall performance in each index (Example 5).

[0100] As can be seen from a comparison of Examples 1, 2, and 5 and Comparative Examples 3 to 5, when the one-dimensional nanomaterial is not layered, the coated separator has low lithium conductivity and a reduced battery capacity retention rate. The main reason for this phenomenon is that when the one-dimensional nanomaterial is not layered, the aggregation phenomenon between the materials becomes very severe, and the aggregates block the pores of the base film, thereby causing a decrease in lithium ion conductivity and different void sizes, which exacerbates the self-discharge problem and further reduces the capacity retention rate.

[0101] In the description herein, the use of terms such as "one embodiment," "one example," "specific implementation process," and "one example" means that the specific features, structures, materials, or characteristics described with reference to the example or embodiment are included in at least one example or embodiment of the present invention. In the description herein, exemplary descriptions of the above terms do not necessarily refer to the same example or embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more examples or embodiments.

[0102] Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention, and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or make equivalent substitutions for part or all of the technical features thereof, and these modifications or substitutions will not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention. [Explanation of symbols]

[0103] 1-coating separator, 11-base membrane, 12-coating layer structure, 13-Ceramic particles

Claims

1. A coated separator comprising a base membrane and a coating layer structure provided on at least one surface of the base membrane, wherein the coating layer structure comprises multiple material layers, the coating layer structure comprises one-dimensional nanomaterials and ceramic particles, and along a direction away from the base membrane, the average length of the one-dimensional nanomaterials in each material layer becomes shorter with each layer, and the ceramic particles are distributed in each material layer of the coating layer structure.

2. 2. The coated separator according to claim 1, wherein the mass ratio of the one-dimensional nanomaterial to the ceramic particles in the coating layer structure is 1:1 to 1:

14.

3. The coated separator of claim 2, characterized in that the ceramic particles include first ceramic particles and second ceramic particles, wherein the average particle diameter (D50) of the second ceramic particles is larger than the average particle diameter (D50) of the first ceramic particles, and the average particle diameter (D50) of the second ceramic particles is at least twice the diameter of the one-dimensional nanomaterial.

4. 4. The coated separator of claim 3, wherein the average particle diameter (D50) of the second ceramic particles is 10 times or more the diameter of at least one of the one-dimensional nanomaterial and the average particle diameter (D50) of the first ceramic particles.

5. The coated separator of claim 4, wherein the one-dimensional nanomaterial has a diameter of 5 to 50 nm, the first ceramic particles have an average particle diameter (D50) of 10 to 60 nm, and the second ceramic particles have an average particle diameter (D50) of 100 to 600 nm.

6. 4. The coated separator according to claim 3, wherein in the coating layer structure, the mass ratio of the first ceramic particles to the second ceramic particles is 5:1 to 1:

5.

7. 4. The coated separator according to claim 3, wherein at least one of the first ceramic particles and the second ceramic particles is an inorganic material having a melting point of 200°C or higher, having electrical insulating properties, and being electrochemically stable within the range of use of a lithium battery.

8. lithium ion conductive functional groups are grafted onto the surfaces of the first ceramic particles; The coated separator according to claim 3, wherein the lithium ion conductive functional group further comprises any one of hydroxyl (-OH), carbonyl (-C=O), fluorine (-F), and carboxyl (-COOH).

9. The coating separator comprises at least a) the puncture resistance of the coating layer is ≥ 7 N; b) ionic conductivity ≥ 0.8; c) Capacity retention rate ≧90%, d) thermal shrinkage at 180 ° C / h ≦ 4%; 2. The coated separator according to claim 1, wherein the coated separator satisfies any one of the following conditions:

10. 2. A method for producing the coated separator according to claim 1, the method comprising the steps of dispersing ceramic particles, dispersing a one-dimensional nanomaterial, preparing a paste by mixing, and forming a film by coating; In dispersing ceramic particles, ceramic particles are dispersed in a first solvent to obtain a ceramic particle dispersion; In dispersing one-dimensional nanomaterials, one-dimensional nanomaterials of different lengths are dispersed in the same or different dispersants to obtain at least one one-dimensional nanomaterial dispersion; In the production of the paste by mixing, a mixed solution containing the ceramic particle dispersion and the one-dimensional nanomaterial dispersion is prepared to form at least one corresponding paste; In the film formation by coating, the method for producing a coated separator comprises coating at least one type of paste onto at least one surface of the base film, followed by drying to obtain the coated separator.

11. The method further comprises a step of sorting the ceramic particles prior to dispersing the ceramic particles; 11. The method for producing a coated separator according to claim 10, wherein the selection of ceramic particles includes selecting first ceramic particles and second ceramic particles having different particle sizes, wherein the first ceramic particles have an average particle size (D50) of 10 to 60 nm, and the second ceramic particles have an average particle size (D50) of 100 to 600 nm.

12. 12. The method for producing a coated separator according to claim 11, further comprising a step of pretreating ceramic particles, in which the first ceramic particles are added to a second solvent and then placed in a reaction vessel, and a grafting target is added to perform a grafting reaction, thereby grafting lithium ion conductive functional groups onto the surfaces of the first ceramic particles.

13. The method for producing a coated separator according to claim 12, wherein the grafting object includes any one of polycarbonate, polylactic acid, polyurethane, perfluoropropyl vinyl ether, and methyl isopropyl ketone.

14. Specifically, the dispersion of the ceramic particles is 13. The method for producing a coated separator according to claim 12, characterized in that the pretreated first ceramic particles and the second ceramic particles are mixed and then dispersed in the first solvent to obtain a ceramic particle dispersion.

15. A battery comprising the coated separator according to any one of claims 1 to 9 or the coated separator manufactured by the method for manufacturing the coated separator according to any one of claims 10 to 14, The battery is further characterized in that the battery is a lithium battery.

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