Separator and its manufacturing method, battery cell, battery and power consumption device

Abstract

This application discloses a separator and a method for manufacturing the same, a battery cell, a battery, and a power consumption device, wherein the separator comprises at least two base films and a functional layer interposed between two adjacent base films, and the base films comprise at least two components. One technical solution of this application provides a base film with a film layer composed of multiple components, the content of which can be controlled, thereby enabling performance control of the base film and, consequently, the separator.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to the Chinese patent application filed on May 26, 2023, with application number 202310611765.8, the entirety of which is incorporated into this application by reference.

[0002] Technical field This application relates to the technical field of lithium-ion batteries, and more particularly to separators and methods for manufacturing the same, battery cells, batteries, and power consumption devices. [Background technology]

[0003] Background technology In related technologies, multilayer composite separators cannot achieve various functions and adapt to the needs of different batteries. Therefore, there is a strong demand for separators that can meet the needs of different batteries. [Overview of the project] [Means for solving the problem]

[0004] Application details The main objective of this application is to provide a separator that satisfies design requirements for the base film and, consequently, the separator's performance, through a controllable design of the component content in the base film.

[0005] To achieve the above objective, this application provides a separator comprising at least two base films and a functional layer interposed between two adjacent base films, wherein the base films comprise at least two components.

[0006] In one or more embodiments of this application, the performance of the base film and, consequently, the separator is controlled by providing a base film with multiple components whose content can be controlled, and by providing a corresponding functional layer interposed between two adjacent base films. The base film contains at least two components, whose content is controllable, and the performance of the base film is controllable by the controllability of the component content.

[0007] In some embodiments of this application, the base film comprises at least two film layers, and each film layer comprises at least two components.

[0008] In one or more embodiments of this application, by compounding film layers with controllable components and determined structures, the performance of the base film is complementary to the components and structure of the film layers, and the performance is controllable by the controllability of the component content. For example, by providing two film layers, each film layer contains two components, polyethylene and polypropylene, and the synthesized base film combines the performance of the two polymers, polyethylene and polypropylene, i.e., the high melting point and high stability of polypropylene are combined with the good hydrophilicity of polyethylene, and by controlling the content of polyethylene and polypropylene, controllable performance and customized design can be achieved. That is, increasing the percentage of polypropylene content can improve the melting point and stability of the corresponding film layer, and increasing the percentage of polyethylene content can increase the hydrophilicity of the corresponding film layer. Because the structures of the two film layers are different, the final performance of the separator formed by the two film layers, such as melting point, stability and hydrophilicity, is further affected by the combined effect of the two film layer structures. The functional layer may be designed according to actual needs, and exemplary, the functional layer can be used to improve the thermal insulation and / or chemical stability of the separator and / or improve the hydrophilicity of the separator.

[0009] In some embodiments of the present application, the number of the film layers is from 2 to 4, and each of the film layers contains from 2 to 4 components.

[0010] In one or more embodiments of the present application, when the number of the film layers is from 2 to 4, for example, it may be 2, 3, or 4, the thermal shrinkage of the base film can be kept within an appropriate range, and the internal resistance of the electrode assembly is not too large due to the excessive thickness of the base film, thereby reducing the occurrence of the situation that affects the mass transfer of Li + . Each of the film layers contains from 2 to 4 components. For example, when it may be 2, 3, or 4, by controlling the content of the components in the film layer and combining the film layers with different structures, the accurate control of the separator performance can be realized.

[0011] In some embodiments of the present application, the thickness of the base film is from 3 μm to 15 μm.

[0012] In one or more embodiments of the present application, when the thickness of the base film is from 3 μm to 15 μm, for example, it may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm. It can not only reduce the excessive thermal shrinkage of the base film due to the too thin base film, but also reduce the occurrence of the situation that the internal resistance of the electrode assembly is too large due to the too thick base film, thereby affecting the mass transfer of Li + .

[0013] In some embodiments of the present application, the porosity of the base film is from 30% to 70%, and / or the pore diameter of the base film is from 100 nm to 800 nm, and / or the areal density of the base film is from 2 g / m 2 to 10 g / m 2 .

[0014] In one or more embodiments of the present application, the porosity of the base film is from 30% to 70%, and may be, for example, 30%, 40%, 50%, 60%, 70%, and / or the pore diameter of the base film is from 100 nm to 800 nm, and may be, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, and / or the areal density of the base film is from 2 g / m 2 to 10 g / m 2 and may be, for example, 2 g / m 2 , 3 g / m 2 , 4 g / m 2 , 5 g / m 2 , 6 g / m 2 , 7 g / m 2 , 8 g / m 2 , 9 g / m 2 , 10 g / m 2 . When the porosity of the base film is from 30% to 70%, not only can the increase in the thermal shrinkage of the base film be reduced due to too many voids causing the base film to be too thin, but also the mass transfer of the electrolyte can be inhibited due to too few voids, and further the degree of reduction in the mass transfer efficiency of Li + can be reduced. When the pore diameter of the base film is from 100 nm to 800 nm, not only can the increase in the thermal shrinkage of the base film be reduced because some positions of the base film are too thin due to too large voids, but also the mass transfer of the electrolyte can be inhibited due to too small voids, and further the degree of reduction in the mass transfer efficiency of Li + can be reduced. When the areal density of the base film is from 2 g / m 2 to 10 g / m 2 , not only can the increase in the thermal shrinkage of the base film be reduced because the base film is too thin due to too small areal density, but also the mass transfer of the electrolyte can be inhibited due to too large areal density, and further the degree of reduction in the mass transfer efficiency of Li + can be reduced.

[0015] In some embodiments of this application, the component comprises at least one of polyolefins, polyethers, polyetheretherketones, polyimides, polyethylene-propylene copolymers, polyvinylidene chloride, and fluorocarbon compounds.

[0016] In one or more embodiments of this application, the above components all possess the characteristics of high temperature resistance, corrosion resistance, and good electrical insulation properties, and can therefore be used as a base film material or film layer material for a separator.

[0017] In some embodiments of this application, the fluorocarbon compound comprises at least one of polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polyvinylidene fluoride.

[0018] In one or more embodiments of this application, the fluorocarbon compound material is characterized by high temperature resistance, corrosion resistance, and good electrical insulation properties, and due to the high polarity and high dielectric constant of the material, it contributes to the ionization of lithium salts and can swell in an electrolyte.

[0019] In some embodiments of this application, the functional layer comprises at least one of an inorganic functional material and / or an organic functional material.

[0020] In one or more embodiments of this application, the functional layer comprises at least one of an inorganic functional material and / or an organic functional material, and the function of the functional material is not limited and may be a material suitable for interposition between base films in the prior art.

[0021] In some embodiments of this application, the inorganic functional material includes, but is not limited to, at least one of Al2O3, AlO(OH), SiO2, TiO2, MgO, CaO, BaSO4, Mg(OH)2, SnO2, ZnO, ZrO2, Y2O3, NiO, CeO2, SrTiO3, BaTiO3, and MgF2.

[0022] In one or more embodiments of this application, the inorganic functional material has the characteristic of having a low heat transfer coefficient, which can limit the expansion of the thermal runaway point in the battery, and can extend the lifespan of the battery by absorbing trace amounts of water in the electrolyte. Other inorganic functional materials can also be used for modification. For example, LiNbO3 and CdS, which generate their own power fields through pressure polarization or electric field polarization, can further improve the ionic conductivity of the separator.

[0023] In some embodiments of this application, the separator further includes an adhesive layer for bonding the functional layer to the base film.

[0024] In one or more embodiments of this application, the presence of an adhesive layer is to make the functional layer less likely to detach from the base film.

[0025] In some embodiments of this application, the weight content of the inorganic functional material is 30% to 50%, and Dv 50 The thickness is between 0.2 μm and 1.2 μm, and the weight content of the adhesive layer is between 10% and 20%.

[0026] In one or more embodiments of this application, the weight content of the inorganic functional material is 30% to 50%, and may be, for example, 30%, 40%, or 50%. 50 The thickness of the adhesive layer is between 0.2 μm and 1.2 μm, and may be, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, or 1.2 μm. The weight content of the adhesive layer is between 10% and 20%, and may be, for example, 10%, 15%, or 20%. The functional layer performs its corresponding function while simultaneously reducing the shedding of the functional material on the functional layer, allowing the separator to maintain performance stability during long-term cycle charge-discharge processes.

[0027] In some embodiments of this application, the organic functional material comprises at least one of cellulose and its derivatives, polyolefins, polyamides, polyethylene terephthalate, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and polyethylene oxide.

[0028] In one or more embodiments of this application, cellulose and its derivatives are used to improve the thermal stability of the separator; polyolefins, polyethylene terephthalate, and polymethyl methacrylate are used to improve the chemical stability of the separator; polyacrylonitrile and polyamide are used to improve the chemical and thermal stability of the separator; polyvinylidene fluoride is used to improve the thermal and chemical stability of the separator and can also improve the ionic conductivity of the separator after pressure polarization or field polarization; and polyethylene oxide is used to improve the hydrophilicity of the separator. In addition, other organic functional materials in the prior art, such as polyvinyl chloride, can also be used for modification.

[0029] In some embodiments of this application, the thickness of the separator is 5 μm to 30 μm.

[0030] In one or more embodiments of this application, the thickness of the separator is 5 μm to 30 μm, for example 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, and the strength of the separator can meet the actual usage requirements, and the separator is not too thick, which would hinder the mass transfer of the electrolyte, and further Li + This can further reduce the degree to which the mass transfer efficiency is reduced.

[0031] In some embodiments of this application, the method for manufacturing the separator includes the steps of electrospinning by at least two extrusion structures to obtain the base film, laminating a functional layer to the surface of the base film, and compounding it with another base film by pressurizing.

[0032] In one or more embodiments of this application, the discharge structure is used to eject electrospun fibers and includes, but is not limited to, a needle or a discharge head. Using the electrospinning method, a polymer solution or melt can be charged under a high-pressure electric field to form droplets, from forming a Taylor cone under the action of an electric field to forming a jet. The jet dries as it is ejected to a collector (i.e., base) and then falls onto the collector to form a base film. A separator is formed when the functional layer and the base film are pressurized and bonded together.

[0033] In some embodiments of this application, in the step of performing electrospinning by at least two dispensing structures, the electrospinning apparatus employed includes one of the following: a two-needle electrospinning apparatus, a multi-needle electrospinning apparatus, a rotary disc electrospinning apparatus, a conjugated electrospinning apparatus, or a needleless electrospinning apparatus.

[0034] In one or more embodiments of this application, two-needle electrospinning machines, multi-needle electrospinning machines, rotary disc electrospinning machines, and conjugated electrospinning machines all belong to the category of needle-type electrospinning machines. Their spinning jet shape is controllable, and the resulting spun film material exhibits relatively good uniformity and uniform thickness. In the rotary disc electrospinning method, consistency can be achieved in the spun film obtained by rotating the base. Conjugated electrospinning enables controllable production of spun film components and structure by installing an outer layer electrospinning solution and an inner layer electrospinning solution. Needleless electrospinning machines have the characteristics of high fiber yield, a simple machine structure, resistance to clogging, and ease of cleaning.

[0035] In some embodiments of this application, electrospinning is performed by at least two dispensing structures, and the step of obtaining the base film includes introducing an electrospinning solution into the dispensing structure, wherein the supply method is top-down or lateral supply, collecting electrospinned fibers on a base, and then removing the base to form the base film.

[0036] In one or more embodiments of this application, by employing a top-to-bottom liquid supply method or a lateral liquid supply method, the problem of bubble generation caused by bottom-to-top liquid supply in conventional spinning machines can be reduced. Methods for removing the base include, but are not limited to, alkaline washing, peeling, or extraction.

[0037] In some embodiments of this application, the spinning speed of the electrospinning machine is 0.5 ml / h to 2 ml / h, the ambient humidity is ≤30%, and the voltage is 15 kV to 20 kV.

[0038] In one or more embodiments of this application, the spinning rate is 0.5 ml / h to 2 ml / h, and may be, for example, 0.5 ml / h, 1.0 ml / h, 1.5 ml / h, or 2.0 ml / h, which not only makes the value at which spun fibers are ejected from the jet outlet (e.g., needle) sufficient for a continuous jet, but also reduces the occurrence of situations where the jet is ejected to the collector before it has completely dried, thereby causing the formation of bead-like or strip-like fibers. The ambient humidity is ≤30%, and may be, for example, ≤10%, ≤20%, or ≤30%, which can reduce the occurrence of situations where the jet is ejected to the collector before it has completely dried. When the voltage is 15 kV to 20 kV, if the voltage is too low, bead-like defects are less likely to occur, and if the voltage is too high, the jet flow rate increases, the jet velocity becomes faster, and the tension and splitting of the jet becomes more difficult, resulting in a relatively larger fiber diameter and relatively poor uniformity, thereby making bead-like defects less likely to occur.

[0039] In some embodiments of this application, in the step of laminating a functional layer to the surface of a base film and compounding it with another base film by pressurizing, the method of pressurizing is hot pressing or cold pressing, and / or the method of laminating the functional layer to the surface of the base film includes coating, electrospinning, or directly coating the surface of the base film with a film-like functional layer.

[0040] In the above-described technical proposal of this application, the method of laminating the functional layer to the surface of the base film includes coating, electrospinning, or directly coating the surface of the base film with a film-like functional layer. The coating method includes gravure or microgravure coating. The electrospinning method includes single-needle electrospinning, double-needle electrospinning, multi-needle electrospinning, rotary disc type electrospinning, conjugated type electrospinning, or needleless type electrospinning. After laminating the functional layer to the surface of one base film, the functional layer is interposed between the two base films, and a separator having the functional layer is manufactured using a hot press or cold press method.

[0041] This application further provides a battery cell including the separator described in the above-mentioned technical proposal.

[0042] This application further provides a battery including the battery cell described in the above-mentioned technical proposal.

[0043] This application further provides a power consumption device including the battery described in the above-mentioned technical proposal.

[0044] One beneficial effect of this invention is to enable performance control of the base film and, consequently, the separator, by providing a film layer on the base film composed of multiple components and in which the content of these components can be controlled. [Modes for carrying out the invention]

[0045] The following clearly and completely describes the technical concepts in the embodiments of this application, and it is clear that the embodiments described are only a subset of the embodiments of this application, not all of them. All other embodiments derived from the embodiments of this application without the creative effort of a person skilled in the art are all within the scope of protection of this application.

[0046] Furthermore, while the technical proposals between each embodiment can be combined with each other, this must be based on the premise that they can be realized by a person skilled in the art. If a combination of technical proposals results in a contradiction or is not feasible, such a combination of technical proposals should be considered nonexistent and not within the scope of protection required by this application.

[0047] The following describes and specifically discloses embodiments of the separator, electrode assembly, battery cell, battery and power consumption device of this application. However, unnecessary details may be omitted. For example, detailed explanations of well-known matters and repeated explanations of structures that are actually the same may be omitted. This is to avoid the following description becoming unnecessarily verbose and to make it easily understandable to those skilled in the art. The drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the topics described in the claims.

[0048] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the limit value, and any combination is possible, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that the ranges 60 to 110 and 80 to 120 can also be assumed. Furthermore, if 1 and 2 are listed as the minimum range values ​​and 3, 4, and 5 are listed as the maximum range values, then ranges such as 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 can all be assumed. In this application, unless otherwise specified, the numerical range “a to b” represents an abbreviated expression of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply a shortened expression for combinations of these numbers. Also, expressing a parameter as an integer ≥ 2 is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0049] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0050] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0051] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, the fact that the method includes steps (a) and (b) means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, the fact that the method mentioned above 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 steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0052] The batteries mentioned in this field include lithium-ion batteries. Lithium-ion batteries are currently widely used in all-electric vehicles and hybrid vehicles.

[0053] A battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. Lithium-ion battery cells operate primarily by relying on the movement of lithium ions between the positive and negative electrode plates.

[0054] The secondary battery electrode plate undergoes slurry coating, drying, and roll pressing to form a current collector and a multilayer composite structure coated on at least one surface of the current collector.

[0055] A separator is a material that isolates the positive and negative electrodes of a battery, and its purpose is to prevent short circuits in the battery.

[0056] A battery cell is a basic unit that enables the interconversion of chemical energy and electrical energy, and includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0057] The film layer is a film substrate having a specific structure composed of multiple components that make up the base film.

[0058] A base film is a film composed of one or more film layers to form a specific structure.

[0059] The separator is a film made of a base film, which may include a functional layer, which may be interposed between the base films or coated onto the surface of the base films.

[0060] In related technologies, multilayer composite separators cannot achieve customized base film components and various functions to suit the diverse application scenarios required to meet the demands of different batteries. Therefore, there is a strong need for separators that can meet the adaptation requirements for different batteries.

[0061] The main objective of this application is to provide a separator that satisfies design requirements for the final performance of the base film and, consequently, the separator, by designing the base film to allow control over the content of its components.

[0062] To achieve the above objective, this application provides a separator comprising at least two base films and a functional layer interposed between two adjacent base films, wherein the base films comprise at least two components.

[0063] In one or more embodiments of this application, the performance of the base film and, consequently, the separator is controlled by providing a base film with multiple components whose content can be controlled, and by providing a corresponding functional layer interposed between two adjacent base films. Because the components in the base film are different and their content can be controlled, the performance of each component in the base film can be made complementary, and the performance can be controlled by the controllability of the content. The functional layer may be designed according to actual needs, and exemplary, the functional layer can be used to improve thermal insulation and / or the chemical stability of the separator and / or the hydrophilicity of the separator.

[0064] In some embodiments of this application, the base film comprises at least two film layers, and each film layer comprises at least two components.

[0065] In one or more embodiments of this application, by compounding film layers with controllable components and determined structures, the performance of the base film is complementary to the components and structure of the film layers, and the performance is controllable by the controllability of the component content. For example, by providing two film layers, each film layer contains two components, polyethylene and polypropylene, and the synthesized base film combines the performance of the two polymers, polyethylene and polypropylene, i.e., the high melting point and high stability of polypropylene are combined with the good hydrophilicity of polyethylene, and by controlling the content of polyethylene and polypropylene, controllable performance and customized design can be achieved. That is, increasing the percentage of polypropylene content can improve the melting point and stability of the corresponding film layer, and increasing the percentage of polyethylene content can increase the hydrophilicity of the corresponding film layer. Because the structures of the two film layers are different, the final performance of the separator formed by the two film layers, such as melting point, stability and hydrophilicity, is further affected by the combined effect of the two film layer structures. The functional layer may be designed according to actual needs, and exemplary, the functional layer can be used to improve the thermal insulation and / or chemical stability of the separator and / or improve the hydrophilicity of the separator.

[0066] In some embodiments of this application, the film layers consist of two to four components, and each film layer comprises two to four components.

[0067] In one or more embodiments of this application, the number of film layers is two to four, for example, two, three, or four, and the thermal shrinkage of the base film is kept within an appropriate range, and the internal resistance of the electrode assembly is not too high due to the base film being too thick, Li + This can reduce the occurrence of situations that affect mass transfer. Each film layer may contain two to four components, for example, two, three, or four. By controlling the content of the components in the film layers and combining film layers with different structures, precise control of separator performance can be achieved.

[0068] In some embodiments of this application, the thickness of the base film is between 3 μm and 15 μm.

[0069] In one or more embodiments of this application, the thickness of the base film is 3 μm to 15 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm. Since the thickness of the base film is sufficient, the thermal shrinkage of the base film due to a base film that is too thin increases, and the risk of causing a short circuit in the electrode assembly is reduced. Furthermore, the internal resistance of the electrode assembly due to a base film that is too thick is too high, Li + This can also reduce the occurrence of situations that affect mass transfer. For example, when using two or more base films, a functional layer may be provided between two adjacent base films to give the separator functions such as thermal stability, chemical stability, and piezoelectric properties.

[0070] In some embodiments of this application, the porosity of the base film is 30% to 70%, and / or the pore size of the base film is 100 nm to 800 nm, and / or the surface density of the base film is 2 g / m². 2 From 10g / m 2 That is the case.

[0071] In one or more embodiments of this application, the porosity of the base film is 30% to 70%, for example 30%, 40%, 50%, 60%, and 70%; the pore size of the base film is 100nm to 800nm, for example 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, and 800nm; and the surface density of the base film is 2g / m². 2 From 10g / m 2 For example, 2g / m 2 , 3g / m 2 4g / m 2 5g / m 2 , 6g / m 2 7g / m2 , 8g / m 2 9g / m 2 10g / m 2 It may also be the case that, if the porosity of the base film is between 30% and 70%, it is possible to reduce the increase in thermal shrinkage of the base film due to too many voids making the base film too thin, as well as to reduce the degree to which the mass transfer of the electrolyte is inhibited and the mass transfer efficiency of Li+ is further reduced due to too few voids. If the pore size of the base film is between 100 nm and 800 nm, it is possible to reduce the increase in thermal shrinkage of the base film due to too many voids making some parts of the base film too thin, as well as to reduce the degree to which the mass transfer of the electrolyte is inhibited and the mass transfer efficiency of Li+ is further reduced due to too few voids. If the surface density of the base film is between 2 g / m2 and 10 g / m2, it is possible to reduce the increase in thermal shrinkage of the base film due to too few surface voids making the base film too thin, as well as to reduce the degree to which the mass transfer of the electrolyte is inhibited and the mass transfer efficiency of Li+ is further reduced due to too many surface voids.

[0072] In some embodiments of this application, the components include at least one of polyolefins, polyethers, polyetheretherketones, polyimides, polyethylene-propylene copolymers, polyvinylidene chloride, and fluorocarbon compounds.

[0073] In one or more embodiments of this application, the above components all possess the characteristics of high temperature resistance, corrosion resistance, and good electrical insulation properties, and can therefore be used as a base film material or film layer material for a separator.

[0074] In some embodiments of this application, the fluorocarbon compound comprises at least one of polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polyvinylidene fluoride.

[0075] In one or more embodiments of this application, the fluorocarbon compound material is characterized by high temperature resistance, corrosion resistance, and good electrical insulation properties, and due to the high polarity and high dielectric constant of the material, it contributes to the ionization of lithium salts and can swell in an electrolyte.

[0076] In some embodiments of this application, the functional layer comprises at least one of an inorganic functional material and / or an organic functional material.

[0077] In one or more embodiments of this application, the functional layer comprises at least one of an inorganic functional material and / or an organic functional material, and the function of the functional material is not limited and may be a material that improves the thermal stability of the separator, improves the chemical stability of the separator, and gives the separator piezoelectric properties, and a material suitable for interposition between base films in the prior art may be used.

[0078] In some embodiments of this application, the inorganic functional material includes, but is not limited to, at least one of Al2O3, AlO(OH), SiO2, TiO2, MgO, CaO, BaSO4, Mg(OH)2, SnO2, ZnO, ZrO2, Y2O3, NiO, CeO2, SrTiO3, BaTiO3, and MgF2.

[0079] In one or more embodiments of this application, the inorganic functional material has the characteristic of having a low heat transfer coefficient, which can limit the expansion of the thermal runaway point in the battery, and can extend the lifespan of the battery by absorbing trace amounts of water in the electrolyte. Other inorganic functional materials can also be used for modification. For example, LiNbO3 and CdS, which generate their own power fields through pressure polarization or electric field polarization, can further improve the ionic conductivity of the separator.

[0080] In some embodiments of this application, the separator further includes an adhesive layer that adheres the functional layer to the base film.

[0081] In one or more embodiments of this application, the presence of an adhesive layer is to adhere the functional layer to the base film, making it less likely to detach from the base film.

[0082] In some embodiments of this application, the weight content of the inorganic functional material is 30% to 50%, and Dv 50 The thickness is between 0.2 μm and 1.2 μm, and the weight content of the adhesive layer is between 10% and 20%.

[0083] In one or more embodiments of this application, the weight content of the inorganic functional material is 30% to 50%, and may be, for example, 30%, 40%, or 50%. 50 The particle size is 0.2 μm to 1.2 μm, and may be, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, or 1.2 μm. The weight content of the adhesive layer is 10% to 20%, and may be, for example, 10%, 15%, or 20%. This is because only inorganic functional materials with a weight content of 30% to 50% can exhibit the corresponding functions suitable for separators and electrode assemblies containing separators, battery cells, batteries, and power consumption devices. 50 This is because, only when the thickness is between 0.2 μm and 1.2 μm, the functional layer can perform its function while simultaneously reducing the shedding of functional material on the functional layer and providing a sufficiently large specific surface area for the inorganic functional material, thereby minimizing the weight content of the inorganic functional material. Only when the weight content of the adhesive layer is between 10% and 20% can the shedding of functional material on the functional layer during long-term cycle charge-discharge processes be reduced. With the above configuration, the separator can maintain performance stability during long-term cycle charge-discharge processes.

[0084] In some embodiments of this application, the organic functional material comprises at least one of cellulose and its derivatives, polyolefins, polyamides, polyethylene terephthalate, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and polyethylene oxide.

[0085] In one or more embodiments of this application, cellulose and its derivatives are used to improve the thermal stability of the separator; polyolefins, polyethylene terephthalate, and polymethyl methacrylate are used to improve the chemical stability of the separator; polyacrylonitrile and polyamide are used to improve the chemical and thermal stability of the separator; polyvinylidene fluoride is used to improve the thermal and chemical stability of the separator and can also improve the ionic conductivity of the separator after pressure polarization or field polarization; and polyethylene oxide is used to improve the hydrophilicity of the separator. In addition, other organic functional materials in the prior art, such as polyvinyl chloride, can also be used for modification.

[0086] In some embodiments of this application, the thickness of the separator is between 5 μm and 30 μm.

[0087] In one or more embodiments of this application, when the separator thickness is 5 μm to 30 μm, for example 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, and 30 μm, the strength of the separator can meet the actual usage requirements, and the mass transfer of the electrolyte is not inhibited by the separator being too thick, and further Li + This can further reduce the degree to which the mass transfer efficiency is reduced.

[0088] In some embodiments of this application, the method for manufacturing a separator includes the steps of electrospinning using at least two extrusion structures to obtain a base film, laminating a functional layer to the surface of the base film, and compounding it with another base film by pressurizing.

[0089] In one or more embodiments of this application, the discharge structure is used to eject electrospun fibers and includes, but is not limited to, a needle or a discharge head. Using the electrospinning method, a polymer solution or melt can be charged under the action of a high-pressure electric field to form droplets, from when polymer droplets form Taylor cones under the action of an electric field to when they form a jet. The jet dries as it is sprayed onto the collector (i.e., the base) and falls onto the collector to form a base film. A separator is formed when the functional layer and the base film are pressurized and compounded. Exemplarily, the following specific steps may be taken: an electrospinning solution is prepared; parameters including, but not limited to, voltage, spinning speed, jet outlet spacing, and distance from the jet outlet to the base are set in an electrospinning machine; and ambient humidity is set in the environment where the electrospinning machine is located; and the jet formed by the action of the voltage from the electrospinning solution falls onto the base via the jet outlet. The outlet of the discharge structure is a jet outlet, and the discharge structure includes a needle and a discharge head. If there are needles, the distance between the jet outlets is the distance between the needles, and the distance from the jet outlet to the base is the distance from the needle to the base. If there are no needles, the distance between the jet outlets is the distance between the jet heads, and the distance from the jet outlet to the base is the distance from the jet head to the base.

[0090] In some embodiments of this application, in the step of performing electrospinning by at least two dispensing structures, the electrospinning apparatus employed includes one of the following: a two-needle electrospinning apparatus, a multi-needle electrospinning apparatus, a rotary disc electrospinning apparatus, a conjugated electrospinning apparatus, or a needleless electrospinning apparatus.

[0091] In one or more embodiments of this application, two-needle electrospinning machines, multi-needle electrospinning machines, rotary disc electrospinning machines, and conjugated electrospinning machines all belong to the category of needle-type electrospinning machines. Their spinning jet shape is controllable, and the resulting spun film material exhibits relatively good uniformity and uniform thickness. In the rotary disc electrospinning method, consistency can be achieved in the spun film obtained by rotating the base. In the conjugated electrospinning method, controllable production of the spun film components and structure can be achieved by installing an outer layer electrospinning solution and an inner layer electrospinning solution. Needleless electrospinning machines have the characteristics of high fiber yield, a simple machine structure, resistance to clogging, and ease of cleaning.

[0092] In some embodiments of this application, the step of performing electrospinning by at least two dispensing structures to obtain a base film includes introducing an electrospinning solution into the dispensing structure, wherein the supply method is top-down or lateral supply, causing the electrospinned fibers to be collected on a base, and then removing the base to form a base film.

[0093] In one or more embodiments of this application, by employing a top-to-bottom liquid supply method or a lateral liquid supply method, the problem of bubble generation caused by bottom-to-top liquid supply in conventional spinning machines can be reduced. Methods for removing the base include, but are not limited to, alkaline washing, peeling, or extraction.

[0094] In some embodiments of this application, the spinning speed of the electrospinning machine is 0.5 ml / h to 2 ml / h, the ambient humidity is ≤30%, and the voltage is 15 kV to 20 kV, so that the electrospun fibers are collected on a base, and the base is removed by alkaline washing or stripping.

[0095] In one or more embodiments of this application, the spinning rate is 0.5 ml / h to 2 ml / h, and may be, for example, 0.5 ml / h, 1.0 ml / h, 1.5 ml / h, or 2.0 ml / h, which not only makes the value at which spun fibers are ejected from the jet outlet (e.g., needle) sufficient for a continuous jet, but also reduces the occurrence of situations where the jet is ejected to the collector before it has completely dried, thereby causing the formation of bead-like or strip-like fibers. The ambient humidity is ≤30%, and may be, for example, ≤10%, ≤20%, or ≤30%, which can reduce the occurrence of situations where the jet is ejected to the collector before it has completely dried. When the voltage is 15 kV to 20 kV, if the voltage is too low, bead-like defects are less likely to occur, and if the voltage is too high, the jet flow rate increases, the jet velocity becomes faster, and the tension and splitting of the jet becomes more difficult, resulting in a relatively larger fiber diameter and relatively poor uniformity, thereby making bead-like defects less likely to occur.

[0096] In some embodiments of this application, in the step of laminating a functional layer to the surface of a base film and compounding it with another base film by pressurizing, the method of pressurizing is hot pressing or cold pressing, and / or the method of laminating the functional layer to the surface of the base film includes coating, electrospinning, or directly coating the surface of the base film with a film-like functional layer.

[0097] In the above-described technical proposal of this application, the method of laminating the functional layer to the surface of the base film includes coating, electrospinning, or directly coating the surface of the base film with a film-like functional layer. The coating method includes gravure or microgravure coating. The electrospinning method includes single-needle electrospinning, double-needle electrospinning, multi-needle electrospinning, rotary disc type electrospinning, conjugated type electrospinning, or needleless type electrospinning. After laminating the functional layer to the surface of one base film, the functional layer is interposed between the two base films, and a separator having the functional layer is manufactured using a hot press or cold press method.

[0098] This application further provides a battery cell including a separator in the above-mentioned technical proposal.

[0099] Since the electrode assembly employs all the technical proposals of all the embodiments described above, it has at least all the beneficial effects of the technical proposals of the embodiments described above, and will not be described further here.

[0100] This application further provides a battery including the battery cell in the above-mentioned technical proposal.

[0101] Since the battery employs all the technical proposals of all the embodiments described above, it has at least all the beneficial effects of the technical proposals of the embodiments described above, and will not be explained further here.

[0102] This application further provides a power consumption device including a battery in the above-mentioned technical proposal.

[0103] Since the power-consuming equipment employs all the technical proposals of all the embodiments described above, it has at least all the beneficial effects of the technical proposals of the embodiments described above, and will not be explained further here.

[0104] One beneficial effect of this invention is to enable performance control of the base film and, consequently, the separator, by providing a film layer on the base film composed of multiple components and in which the content of these components can be controlled. [Examples]

[0105] Specific examples are as follows:

[0106] Example 1 (1) The separator is made by braiding polyethylene / polypropylene as the outer base film using multi-needle electrospinning and then compounding it (thickness 12 μm, surface density 4 g / m²). 2 , average pore size 400nm, porosity 30%).

[0107] (2) Production of electrospun base film: A powdered polymer mixture was dried in a ratio of 80% (polypropylene) / 20% (polyethylene), and then added to a polar solvent acetone:N,N-dimethylformamide (1:4 w / w) mixed solvent. Dissolved by magnetic stirring at 75°C for 6 hours at a stirring speed of 1000 r / min. The mixture was stirred to disperse thoroughly and an electrospun solution was obtained. The mass percentage of the solute was 12 wt%. Electrospinning was performed using a multi-needle rotary disk electrospinning machine to produce the electrospun film.

[0108] (3) Here, the multi-needle electrospinning machine adopted a two-needle rotating disc system and a top-to-bottom fluid supply system. The rotating disc was driven to receive the filaments of the two needles, and a consistent composite base film was obtained by rotation. The distance between the needles was 10 cm, and the distance between the needles and the base was 15 cm. The spinning speed was 1 ml / h, the ambient humidity was ≤30%, and the voltage was 15 kV. The fibers were collected by the rotating disc, and the base of the composite base film was removed by peeling. To remove the solvents acetone and DMF, the obtained film layer was placed in a 60°C vacuum oven for 12 hours, and the dried film layer was compacted with a hot press at 80°C and 1000 MPa, and placed in an 80°C oven for 10 minutes to obtain a PP / PE (0.8:0.2) composite base film.

[0109] (4) The production of the functional layer includes: a uniform mixture of aluminum oxide, polyacrylate, and carboxymethylcellulose in a solvent in a ratio of 3:3:1, where the weight content of aluminum oxide particles is 40%, the weight content of adhesive is 15%, and the average particle size Dv of the inorganic particles is 40%. 50 The thickness of the coating was 0.2 to 1.2 μm, and the thickness of the coating was 1 μm. The coating was applied to one side of the composite film layer manufactured in step (3), and simultaneously bonded to another composite base film via a roll to form a two-layer composite separator. The oven temperature was controlled to 65°C, dried for 5 minutes, and pressed at a pressure of 100 MPa to obtain the separator in one or more embodiments of this application.

[0110] The differences between Example 1 and the other examples and comparative examples are shown in Tables 1 and 2. Any information in the other examples and comparative examples not explicitly stated in Tables 1 and 2 is the same as in Example 1.

[0111] [Table 1-1] [Table 1-2]

[0112] [Table 2]

[0113] Comparative Examples 1-3 are conventional separators, all of which have a thickness of 12 μm and a porosity of 30%. Comparative Example 3 consists of a 7 μm PP separator and a 5 μm PE separator, and the manufacturing of the inorganic functional layer is the same as in Example 1.

[0114] As can be seen from the test results, electrospinning enables the design of the base film components, and the heat shrinkage rate of all examples is superior to that of PE separators. Furthermore, the intermediate aluminum oxide functional coating further improves the heat resistance of the separator, making the manufactured separator superior to that of PP separators. The reason why the heat resistance of the examples is better than that of Comparative Example 3 is that the improved base film components allow it to adapt to the heat resistance of aluminum oxide better than that of the PE base film during the heat absorption process.

[0115] The ion conductivity and air permeability of the composite separator manufactured by electrospinning are both superior to those of the comparative example. This is because the uniformity of the electrospinning film formation eliminates clogging caused by conventional casting crystallization, thereby resulting in superior ion conductivity and air permeability.

[0116] Heat shrinkage rate measurement: The separator was cut to the size of a circular sheet with a radius of R50, placed in an oven at 130°C / 1h, and the degree of diameter shrinkage of the separator was measured using calipers.

[0117] Air permeability test method: Air permeability (Gurley value) is measured according to JIS P 8117:2009, and the gas used when measuring air permeability is air.

[0118] Ionic conductivity test method: Constant voltage AC impedance spectroscopy was performed on the separator using a Bio-logic electrochemical workstation. The intercept where the impedance curve on the Nyquist plot intersects the real part was defined as Rs, and the ionic conductivity was obtained by comparing it with the Rs parameter of a known standard conductivity sample.

[0119] The above description is merely a preferred embodiment of the present application and does not limit the scope of the patent. Any equivalent structural transformations or direct / indirect applications in other related technical fields that utilize the present specification, based on the concept of the present application, are all included within the scope of the patent protection of this application.

Claims

1. A separator comprising at least two base films and a functional layer interposed between two adjacent base films, wherein the base films comprise at least two components.

2. The separator according to claim 1, wherein the base film comprises at least two film layers, and each film layer comprises at least two components.

3. The separator according to claim 2, wherein the film layers consist of two to four components, and each film layer comprises two to four components.

4. The separator according to any one of claims 1 to 3, wherein the thickness of the base film is 3 μm to 15 μm.

5. The porosity of the base film is 30% to 70%. and / or, the pore size of the base film is 100 nm to 800 nm. And / or, the surface density of the base film is 2 g / m². ２ From 10 g / m ２ The separator according to claim 4.

6. The separator according to any one of claims 1 to 5, wherein the component comprises at least one of polyolefin, polyether, polyetheretherketone, polyimide, polyethylene-propylene copolymer, polyvinylidene chloride, and fluorocarbon compound.

7. The separator according to claim 6, wherein the fluorocarbon compound comprises at least one of polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polyvinylidene fluoride.

8. The separator according to any one of claims 1 to 7, wherein the functional layer comprises at least one of an inorganic functional material and / or an organic functional material.

9. The inorganic functional material is Al ２ O ３ , AlO(OH), SiO ２ , TiO ２ , MgO, CaO, BaSO ４ , Mg(OH) ２ , SnO ２ , ZnO, ZrO ２ , Y ２ O ３ , NiO, CeO ２ , SrTiO ３ , BaTiO ３ , MgF ２ The separator according to claim 8, comprising at least one of the above.

10. The separator according to claim 9, further comprising an adhesive layer for bonding the functional layer and the base film.

11. The weight content of the inorganic functional material is 30% to 50%, and Dv ５０ The separator according to claim 10, wherein the thickness is 0.2 μm to 1.2 μm, and the weight content of the adhesive layer is 10% to 20%.

12. The separator according to claim 8, wherein the organic functional material comprises at least one of cellulose and its derivatives, polyolefins, polyamides, polyethylene terephthalate, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and polyethylene oxide.

13. The separator according to any one of claims 1 to 12, wherein the thickness of the separator is 5 μm to 30 μm.

14. A method for manufacturing a separator according to any one of claims 1 to 13, A method for manufacturing a separator, comprising the steps of performing electrospinning using at least two dispensing structures to obtain a base film, and interposing a functional layer between the two base films to obtain a separator.

15. A method for manufacturing a separator according to claim 14, wherein in the step of performing electrospinning by at least two discharge structures, the electrospinning equipment used includes one of a two-needle electrospinning equipment, a multi-needle electrospinning equipment, a rotary disc type electrospinning equipment, a conjugated type electrospinning equipment, and a needleless type electrospinning equipment.

16. The step of performing electrospinning using at least two dispensing structures to obtain the base film is: A method for manufacturing a separator according to claim 15, comprising introducing an electrospun solution into a dispensing structure, wherein the liquid supply method is from top to bottom or from side to side, collecting electrospun fibers on a base, and then removing the base to form the base film.

17. The method for manufacturing a separator according to claim 16, wherein the spinning speed of the electrospinning machine is 0.5 ml / h to 2 ml / h, the ambient humidity is ≤30%, and the voltage is 15 kV to 20 kV.

18. In the step of bonding the functional layer to the surface of the base film and compounding it with another base film by pressing, the pressing method is either hot pressing or cold pressing. The method for manufacturing a separator according to claim 14 or 15, wherein the method for laminating the functional layer to the surface of the base film includes coating, electrospinning, or directly covering the surface of the base film with a film-like functional layer.

19. A battery cell comprising a separator according to any one of claims 1 to 13.

20. A battery comprising the battery cell described in claim 19.

21. A power-consuming device comprising the battery described in claim 20.

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