CN118104025A

CN118104025A - Separator and preparation method thereof, secondary battery, battery module, battery pack and power utilization device

Info

Publication number: CN118104025A
Application number: CN202280014291.2A
Authority: CN
Inventors: 朱翠翠; 张继君; 王少飞; 魏奕民; 李杨
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2022-09-27
Filing date: 2022-09-27
Publication date: 2024-05-28
Also published as: WO2024065151A1

Abstract

The application provides a separation film and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electric device. The isolating film comprises an isolating film base material layer and a solid electrolyte layer positioned on at least one surface of the isolating film base material layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX_a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P.

Description

Separator and preparation method thereof, secondary battery, battery module, battery pack and power utilization device

Technical Field

The application relates to the field of secondary batteries, in particular to a separation film and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electric device.

Background

With the continuous development of secondary battery technology, consumers have made higher demands on the performance of secondary batteries. Wherein, increasing the charge voltage of the battery is an effective way to increase the charge-discharge capacity of the battery. However, as the charging voltage increases, it is difficult for the conventional secondary battery to maintain stable performance, and even there is a problem in that a high voltage causes battery damage.

Disclosure of Invention

Based on the above problems, the present application provides a separator, a method for manufacturing the separator, a secondary battery, a battery module, a battery pack, and an electric device, which can effectively improve the stability of the secondary battery during high-voltage charging.

In order to achieve the above object, a first aspect of the present application provides a separator comprising a separator substrate layer and a solid electrolyte layer located on at least one surface of the separator substrate layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P.

In some of these embodiments, M is a +3 valent cation.

In some of these embodiments, M comprises one or more of Al ³⁺、Ga ³⁺、In ³⁺、Y ³⁺、Zr ³⁺、Nb ³⁺、Sc ³⁺、Ti ³⁺、Mn ³⁺、Er ³⁺、Tb ³⁺、Yb ³⁺、Lu ³⁺、La ³⁺ and Ho ³⁺.

In some of these embodiments, X comprises one or more of F ^-、Cl ^-、Br ^-、I ^-、S ^2-、O ^2- and PO ₄ ^-.

In some of these embodiments, the solid state electrolyte layer includes at least one of Li ₃InCl ₆、Li ₃MnCl ₆、Li ₃ScCl ₆、Li ₃ZrCl ₆、Li ₃YCl ₆、Li ₃InF ₆.

In some of these embodiments, the solid state electrolyte layer has a thickness of 5nm to 1000nm; optionally 50nm to 100nm;

in some of these embodiments, the electrochemical window of the solid state electrolyte layer is ≡4.2V.

In some embodiments, the solid electrolyte layer has an ionic conductivity of 10 ^-3 S/cm or greater.

In a second aspect, the present application also provides a method for preparing a separation membrane, comprising the steps of:

Preparing a solid electrolyte target;

Sputtering the solid electrolyte target material on at least one surface of the isolating film substrate layer by adopting a magnetron sputtering method to form an isolating film,

The isolating film comprises an isolating film base material layer and a solid electrolyte layer positioned on at least one surface of the isolating film base material layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P.

In some of these embodiments, the sputtering power is 150W to 200W.

In some of these embodiments, the sputtering vacuum is 10 ^-1Pa～10 ^-2 Pa.

In some embodiments, the temperature of the barrier film substrate layer is controlled to be less than or equal to 100 ℃ during the sputtering.

In a third aspect, the present application also provides a secondary battery comprising the separator of the first aspect or the separator prepared according to the preparation method of the second aspect.

In a fourth aspect, the present application also provides a battery module including the secondary battery of the third aspect.

In a fifth aspect, the present application also provides a battery pack including the secondary battery of the third aspect or the battery module of the fourth aspect.

In a sixth aspect, the present application also provides an electric device including at least one of the secondary battery of the third aspect, the battery module of the fourth aspect, and the battery pack of the fifth aspect.

Drawings

In order to more clearly illustrate the technical solution of the present application, the following description will briefly explain the drawings used in the present application. It is apparent that the drawings described below are only some embodiments of the present application, and that other drawings may be obtained from the drawings without inventive work for those skilled in the art.

Fig. 1 is a schematic view of a secondary battery according to an embodiment of the present application.

Fig. 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in fig. 1.

Fig. 3 is a schematic view of a battery module according to an embodiment of the present application.

Fig. 4 is a schematic view of a battery pack according to an embodiment of the present application.

Fig. 5 is an exploded view of the battery pack of the embodiment of the present application shown in fig. 4.

Fig. 6 is a schematic view of an electric device in which a secondary battery according to an embodiment of the present application is used as a power source.

Fig. 7 is a Scanning Electron Microscope (SEM) image of the base material layer of the separator in example 1 of the present application.

Fig. 8 is a Scanning Electron Microscope (SEM) picture of the separator in example 1 of the present application.

Fig. 9 is a graph showing ac impedance test results of the symmetrical batteries assembled in examples 1 to 3 and comparative examples 1 to 2 according to the present application.

Reference numerals illustrate:

1. a battery pack; 2. an upper case; 3. a lower box body; 4. a battery module; 5. a secondary battery; 51. a housing; 52. an electrode assembly; 53. a cover plate; 6. and (5) an electric device.

For a better description and illustration of embodiments and/or examples of those inventions disclosed herein, reference may be made to one or more of the accompanying drawings. Additional details or examples used to describe the drawings should not be construed as limiting the scope of the disclosed invention, the presently described embodiments and/or examples, and any of the presently understood modes of carrying out the invention.

Detailed Description

In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

The "range" disclosed herein is defined in terms of lower and upper limits, with the given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3,2 to 4 and 2 to 5. In the present application, unless otherwise indicated, the numerical ranges "a-b" represent a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is only a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2,3, 4,5, 6, 7, 8, 9, 10, 11, 12 or the like.

All embodiments of the application and alternative embodiments may be combined with each other to form new solutions, unless otherwise specified.

All technical features and optional technical features of the application may be combined with each other to form new technical solutions, unless specified otherwise.

All the steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise specified. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

The terms "comprising" and "including" as used herein mean open ended or closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

Unless otherwise indicated, terms used in the present application have well-known meanings commonly understood by those skilled in the art. Unless otherwise indicated, the numerical values of the parameters set forth in the present application may be measured by various measurement methods commonly used in the art (e.g., may be tested according to the methods set forth in the examples of the present application).

With the continuous development of secondary battery technology, consumers have made higher demands on the performance of secondary batteries. Wherein, increasing the charge voltage of the battery is an effective way to increase the charge-discharge capacity of the battery. And when the secondary battery is charged at a higher voltage, the stability of the separator has an important influence on the stability of the battery during charging. The traditional isolating film adopts a plurality of polyethylene, polypropylene and other hydrocarbon materials, and the materials have the advantages of low cost, excellent mechanical property, good thermal closed pore performance and the like, but the materials are easy to generate oxidative denaturation under the high-voltage condition, and lose the effects of ion conduction and anode and cathode isolation.

The application provides a separation film and a preparation method thereof, a secondary battery, a battery module, a battery pack and an electric device. Wherein the isolating film comprises an isolating film substrate layer and a solid electrolyte layer positioned on at least one surface of the isolating film substrate layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following: halogen, S, O and P.

In the isolating film provided by the application, the solid electrolyte layer is formed on at least one surface of the base material layer of the isolating film, so that the stability of the isolating film can be improved, the oxidation resistance of the isolating film during high-voltage charging (for example, the charging voltage is more than or equal to 4.5V) is improved, the voltage window of the secondary battery is further improved, the battery can maintain better stability during high-voltage charging, and the battery can still maintain good cycle performance under the high-voltage condition.

In addition, the high-voltage stability of the isolating film is improved, so that the isolating film can be enabled to have a higher voltage window when the battery is charged, further, the charge and discharge capacity of the battery can be improved, and a foundation is provided for the development of the high-capacity battery.

Meanwhile, in the charge and discharge process of the secondary battery, a certain amount of transition metal ions are inevitably generated by the positive electrode active material, and the presence of the transition metal ions can restrict the improvement of the lithium ion conductivity. In the isolating film, the solid electrolyte layer can reduce the content of transition metal ions through chemical reaction or adsorption reaction, for example, the content of transition metal ions in the battery is reduced through complexation with the transition metal ions, so that the isolating film has good lithium ion conductivity, and the capacity retention rate of the secondary battery is improved. In addition, the isolating film has better wettability to electrolyte, and can further improve the conductivity of lithium ions. Furthermore, the isolating film has better blocking capability to the transition metal ions, and can effectively avoid adverse effects on the battery caused by transfer of the transition metal ions to the surface of the negative electrode.

In one embodiment, 2.ltoreq.a.ltoreq.4. Alternatively, a=3. In addition, a may represent an integer or a non-integer. As some alternative examples of a, a may be 1, 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, etc. It will be appreciated that a may be chosen in other ways within the range of 2 to 6 values.

In one embodiment, M is a +3 valent cation. For example, M comprises a +3 cation of Al ³⁺、Ga ³⁺、In ³⁺、Y ³⁺、Zr ³⁺、Nb ³⁺、Sc ³⁺、Ti ³⁺、Mn ³⁺、La series elements. Optionally, M comprises one or more of Al ³⁺、Ga ³⁺、In ³⁺、Y ³⁺、Zr ³⁺、Nb ³⁺、Sc ³⁺、Ti ³⁺、Mn ³⁺、Er ³⁺、Tb ³⁺、Yb ³⁺、Lu ³⁺、La ³⁺ and Ho ³⁺. Additionally, as an alternative example of X, X includes one or more of F ^-、Cl ^-、Br ^-、I ^-、S ^2-、O ^2- and PO ₄ ^-. Alternatively, li _aMX _a+3 includes Li ₃InCl ₆、Li ₃MnCl ₆、Li ₃ScCl ₆、Li ₃ZrCl ₆、Li ₃YCl ₆、Li ₃InF ₆、Li ₃YCl ₆、Li ₃ScF ₆.

In one embodiment, the solid state electrolyte layer includes at least one of Li ₃InCl ₆、Li ₃MnCl ₆、Li ₃ScCl ₆、Li ₃ZrCl ₆、Li ₃YCl ₆、Li ₃InF ₆、Li ₃YCl ₆ and Li ₃ScF ₆.

Examples of some parameters for the solid state electrolyte layer. The thickness of the solid electrolyte layer is 5nm to 1000nm. Within this thickness range, the solid electrolyte layer can provide the separator with good high voltage stability, while allowing the secondary battery to have low ohmic resistance. Alternatively, the thickness of the solid electrolyte layer may be, but is not limited to, 10nm, 15nm, 20nm, 50nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm. It will be appreciated that the thickness of the solid electrolyte layer may be chosen in the range of 10nm to 1000nm. Further alternatively, the thickness of the solid electrolyte layer is 50nm to 100nm.

Alternatively, the electrochemical window of the solid electrolyte layer is greater than or equal to 4.2V. The solid electrolyte layer has a higher electrochemical window, and can further improve the high-voltage stability of the isolating film, so that the battery can keep the performance stability during high-voltage charging, and further the capacity of the battery is improved. Further alternatively, the electrochemical window of the solid electrolyte layer is greater than or equal to 4.4V.

It can be understood that the electrochemical window is tested by adopting an electrochemical workstation linear voltammetric test module, the solid electrolyte and the binder PVDF are mixed and dripped on the surface of the glassy carbon electrode in a mass ratio of 95:5 to form a working electrode, 1M LiPF ₆ is used as a solution, a lithium sheet is used as a counter electrode for carrying out voltammetric curve test, the voltage range is 2.5-5V, the sweeping speed is 0.5mV/s, and the oxidation potential is recorded to be the electrochemical window.

In one embodiment, the solid electrolyte layer has an ionic conductivity of 10 ^-3 S/cm or more. At this time, the conductivity of lithium ions can be further improved, and the cycle performance of the battery can be improved.

It can be appreciated that the ion conductivity measurement method: the alternating current impedance test adopts an electrochemical workstation impedance test module, a voltage disturbance mode PEIS, a disturbance voltage of 5mV and a frequency range of 200 kHZ-30 mHZ, the impedance test is carried out on the solid electrolyte sheet, and the ion conductivity of the electrolyte sheet is calculated.

Specifically, the solid electrolyte is an ion conductor and is not conductive to electrons, so before impedance testing, it is necessary to connect blocking Ag electrodes on both sides of the solid electrolyte sheet: polishing two sides of the sintered solid electrolyte to a certain thickness, coating silver paste to lead out Ag wires, and performing Ag burning treatment in a muffle furnace to enable the Ag electrode to be in close contact with the surface of the electrolyte. The resistance r=h/(ρs) is measured, and the ion conductivity σ is solved, where σ=1/ρ.

It is understood that the separator substrate layer has two surfaces opposite in the thickness direction thereof, and the solid electrolyte layer is located on at least one surface of the separator substrate layer. In this case, the solid electrolyte layer may be provided on both surfaces of the separator substrate layer, or the solid electrolyte layer may be provided on any one surface of the separator substrate layer. Alternatively, the solid electrolyte layer is positioned on one surface of the base material layer of the isolating film, so that the ohmic resistance of the battery can be better considered on the basis of improving the high-voltage stability of the isolating film.

It is also understood that the type of the separator substrate layer is not particularly limited, and any known porous separator substrate layer having good chemical stability and mechanical stability may be used. Optionally, the material of the base material layer of the isolating film may be at least one selected from glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of the respective layers may be the same or different, and are not particularly limited.

The application also provides a preparation method of the isolating film. The preparation method of the isolating film comprises the following steps: a solid electrolyte layer is formed on at least one surface of the separator substrate layer. The isolating film with good high-pressure stability can be prepared by the method.

As a method of forming the solid electrolyte layer on at least one surface of the separator substrate layer, a coating method, a lamination method, or the like can be used. Alternatively, the material of the solid electrolyte layer may be prepared as a solid electrolyte slurry, and then the solid electrolyte slurry is coated on at least one surface of the separator substrate layer by means of coating. The solid electrolyte layer may be formed on at least one surface of the separator substrate layer by bonding between layers.

In one embodiment, a solid electrolyte containing a material having a chemical composition of Li _aMX _a+3 is transferred to at least one surface of the separator substrate layer to form a solid electrolyte layer. Wherein, as described above with respect to the chemical composition Li _aMX _a+3, 1.ltoreq.a.ltoreq.6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P. Wherein, a, M and X can be selected from the corresponding listed values, elements and ions.

Alternatively, when a solid electrolyte containing a material having a chemical composition of Li _aMX _a+3 is transferred to at least one surface of the separator substrate layer, the transfer may be performed by a deposition method. Further alternatively, the transfer is by physical vapor deposition. Still further alternatively, the transfer is by sputtering. Still further alternatively, the transfer is by magnetron sputtering.

In one embodiment, the method of preparing the release film includes the steps of: preparing a solid electrolyte target; sputtering a solid electrolyte target on at least one surface of a base material layer of the isolating film by adopting a magnetron sputtering method to form the isolating film, wherein the isolating film comprises the base material layer of the isolating film and the solid electrolyte layer positioned on at least one surface of the base material layer of the isolating film; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P. Compared with the traditional coating mode, the solid electrolyte layer with smaller thickness can be prepared on at least one surface of the base material layer of the isolating film by the mode of preparing the solid electrolyte target and sputtering, meanwhile, the thickness of the solid electrolyte layer is convenient to accurately control, and the solid electrolyte layer with smaller thickness is beneficial to improving the lithium ion conductivity and reducing the battery impedance, so that the performance of the isolating film can be further improved. For example, conventional coating methods can generally provide solid electrolyte layers having a thickness on the order of microns. And a solid electrolyte layer with the thickness of nanometer grade can be obtained by adopting a sputtering mode. Specifically, a solid electrolyte layer having a thickness of 5nm to 1000nm can be obtained by sputtering. In addition, a solid electrolyte layer with better uniformity can be obtained by adopting a sputtering mode, and the solid electrolyte layer with better uniformity can further improve the stability of the isolating film.

Sputtering is understood to mean that electrons ionize under the action of an electric field to produce Ar positive ions and bombard the target surface with high energy. In sputtered particles, target atoms or molecules are deposited on a substrate to form a film, and a deposited layer with a thickness of several atoms is formed to realize uniform coating. The application adopts a sputtering mode, and can form a solid electrolyte layer with small thickness, easy control of thickness and uniform thickness on at least one surface of the membrane substrate layer.

As an example of preparing a solid electrolyte target, preparing a solid electrolyte target includes the steps of: mixing the solid electrolyte with a binder to prepare a mixture; compacting the mixture to prepare a compacted material; and calcining the compacted material.

Optionally, the binder comprises at least one of polyvinyl alcohol and polyvinylidene fluoride. The mass ratio of the solid electrolyte to the binder is (45-50): 1. Further alternatively, the mass ratio of the solid electrolyte to the binder is (48-49): 1. For example, the mass ratio of solid electrolyte to binder may be, but is not limited to, 45:1, 46:1, 47:1, 48:1, 49:1, 50:1, etc.

In one embodiment, mixing the solid electrolyte with the binder includes the steps of: the solid electrolyte and the binder are mixed in a dispersion medium, and then the dispersion medium is removed. At this time, the solid electrolyte and the binder with better mixing uniformity can be obtained, namely, the mixture with better mixing uniformity is prepared. Optionally, the dispersion medium is at least one of ethanol and ethylene glycol. Alternatively, the removal of the dispersion medium may take place in a dry manner. Specifically, the drying temperature is 85-95 ℃. It is understood that in order to enhance the removal effect of the dispersion medium, a forced air drying method may be employed in the drying.

In one embodiment, the particle size of the mixture is controlled to be 0.1 μm to 100 μm when the mixture is compacted. Within this particle size range, a better compaction effect can be obtained. Alternatively, the particle size of the mixture may be controlled by grinding as the mixture is compacted. Alternatively, when the mixture is subjected to the compacting treatment, the particle diameter of the mixture may be controlled to be 0.5 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or the like.

As an example of partial parameter selection for the compacting treatment, the pressure of the compacting treatment is 150MPa to 250MPa. For example, the compaction process may be performed at a pressure of, but not limited to, 150MPa, 180MPa, 200MPa, 220MPa, 250MPa, etc. In the compacting treatment, a proper compacting treatment time may be selected depending on the compacting effect, for example, the dwell time of the compacting treatment is 1 to 5 hours. Alternatively, the dwell time of the compaction process may be, but is not limited to, 1.5h, 2h, 3h, 4h, etc. It is understood that as one specific way of compacting, the compacting is a cold pressing.

In one embodiment, the temperature of the calcination treatment is 700-800 ℃ when the compacted material is subjected to the calcination treatment. Alternatively, the temperature of the calcination treatment is 700 ℃, 720 ℃, 750 ℃, 780 ℃, 800 ℃, etc. In the calcination treatment, the calcination treatment time is 5-15 hours. For example, the calcination treatment is performed for 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, or the like.

In one embodiment, the solid state electrolyte further comprises, prior to mixing with the binder: the solid electrolyte is subjected to a pre-calcination treatment. Alternatively, when the solid electrolyte is subjected to the pre-calcination treatment, the temperature of the pre-calcination treatment is 700 to 800 ℃. For example, the temperature of the preliminary calcination treatment is 700 ℃, 720 ℃, 750 ℃, 780 ℃, 800 ℃, etc. In the pre-calcination treatment, the pre-calcination treatment time is 1-4 hours. Alternatively, the time of the pre-calcination treatment may be, but is not limited to, 1h, 2h, 2.5h, 3h, 3.5h, etc.

In one embodiment, when the solid electrolyte target is sputtered on at least one surface of the base material layer of the isolating film to form the isolating film, the sputtering power is 150W-200W. Alternatively, the power of sputtering is 150W, 160W, 170W, 180W, 190W, 200W, etc. The vacuum degree of sputtering was 10 ^-1Pa～10 ^-2 Pa. Optionally, during sputtering, the voltage is 1000V-1500V and the current is 300 mA-500 mA. For example, the voltage may be 1100V, 1200V, 1300V, 1400V, etc. The current may be 350mA, 400mA, 450mA, 500mA, etc.

In one embodiment, the temperature of the barrier film substrate layer is controlled to be less than or equal to 100 ℃ during sputtering. This can avoid damage to the separator substrate due to excessive temperature during sputtering. Alternatively, as an example of a mode of controlling the temperature of the base material layer of the separation film, a sample stage carrying the base material layer of the separation film may be connected to a cooling medium pipe, and the sample stage may be cooled by a cooling medium in the cooling medium pipe, thereby controlling the temperature of the base material layer of the separation film to be less than or equal to 100 ℃. Optionally, the cooling medium comprises water.

The application also provides a secondary battery. The secondary battery includes the separator provided by the present application or the separator prepared according to the preparation method provided by the present application.

The application also provides a battery module. The battery module comprises the secondary battery provided by the application.

The application also provides a battery pack. The battery pack includes the secondary battery or the battery module provided by the application.

The application also provides an electric device. The power utilization device comprises at least one of the secondary battery, the battery module and the battery pack. The secondary battery, the battery module, or the battery pack may be used as a power source of the electric device, or may be used as an energy storage unit of the electric device. The power utilization device may include, but is not limited to, mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, and the like. As the electricity consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirements thereof.

The secondary battery, the battery module, the battery pack, and the electric device of the present application will be described below with reference to the accompanying drawings as appropriate.

In general, a secondary battery includes a positive electrode tab, a negative electrode tab, an electrolyte, and a separator. During the charge and discharge of the battery, active ions are inserted and extracted back and forth between the positive electrode plate and the negative electrode plate. The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The isolating film is arranged between the positive pole piece and the negative pole piece, and mainly plays a role in preventing the positive pole piece and the negative pole piece from being short-circuited, and meanwhile ions can pass through the isolating film.

In one embodiment the separator is selected from the group of separators provided by the present application.

Positive electrode plate

The positive pole piece comprises a positive current collector and a positive film layer arranged on at least one surface of the positive current collector, wherein the positive film layer comprises a positive active material.

As an example, the positive electrode current collector has two surfaces opposing in its own thickness direction, and the positive electrode active material layer is provided on either one or both of the two surfaces opposing the positive electrode current collector.

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

As an example, the positive electrode active material may include a positive electrode active material for a battery, which is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: olivine structured lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive electrode active material may be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (e.g., liCoO ₂), lithium nickel oxide (e.g., liNiO ₂), lithium manganese oxide (e.g., liMnO ₂、LiMn ₂O ₄), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., liNi _1/3Co _1/3Mn _1/3O ₂) (which may also be abbreviated as NCM ₃₃₃)、LiNi _0.5Co _0.2Mn _0.3O ₂ (which may also be abbreviated as NCM ₅₂₃)、LiNi _0.5Co _0.25Mn _0.25O ₂ (which may also be abbreviated as NCM ₂₁₁)、LiNi _0.6Co _0.2Mn _0.2O ₂ (which may also be abbreviated as NCM ₆₂₂)、LiNi _0.8Co _0.1Mn _0.1O ₂ (which may also be abbreviated as NCM ₈₁₁)), At least one of lithium nickel cobalt aluminum oxide (such as LiNi _0.85Co _0.15Al _0.05O ₂) and modified compounds thereof, and the like. Examples of olivine structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO ₄ (which may also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO ₄), a composite of lithium manganese phosphate and carbon, lithium manganese phosphate, a composite of lithium manganese phosphate and carbon. The weight ratio of the positive electrode active material in the positive electrode film layer is 80-100 wt%, based on the total weight of the positive electrode film layer.

In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluoroacrylate resin. The weight ratio of the binder in the positive electrode film layer is 0-20% by weight based on the total weight of the positive electrode film layer.

In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. The weight ratio of the conductive agent in the positive electrode film layer is 0-20% by weight based on the total weight of the positive electrode film layer.

In some embodiments, the positive electrode sheet may be prepared by: dispersing the components for preparing the positive electrode plate, such as the positive electrode active material, the conductive agent, the binder and any other components, in a solvent (such as N-methyl pyrrolidone) to form positive electrode slurry, wherein the solid content of the positive electrode slurry is 40-80 wt%, the viscosity of the positive electrode slurry at room temperature is adjusted to 5000-25000 mPa.s, the positive electrode slurry is coated on the surface of a positive electrode current collector, and the positive electrode slurry is formed after being dried and cold-pressed by a cold rolling mill; the unit surface density of the positive electrode powder coating is 150-350mg/m ², the compacted density of the positive electrode plate is 3.0-3.6g/cm ³, and the compacted density of the positive electrode plate is 3.3-3.5g/cm ³. The calculation formula of the compaction density is as follows: compacted density = coated area density/(post-extrusion pole piece thickness-current collector thickness).

Negative pole piece

The negative electrode plate comprises a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer comprises a negative electrode active material.

As an example, the anode current collector has two surfaces opposing in its own thickness direction, and the anode film layer is provided on either one or both of the two surfaces opposing the anode current collector.

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

In some embodiments, the anode active material may employ an anode active material for a battery, which is well known in the art. As an example, the anode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, and the like. The silicon-based material may be at least one selected from elemental silicon, silicon oxygen compounds, silicon carbon composites, silicon nitrogen composites, and silicon alloys. The tin-based material may be at least one selected from elemental tin, tin oxide, and tin alloys. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery anode active material may be used. These negative electrode active materials may be used alone or in combination of two or more. The weight ratio of the negative electrode active material in the negative electrode film layer is 70-100% by weight based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode film layer further optionally includes a binder. The binder may be at least one selected from Styrene Butadiene Rubber (SBR), polyacrylic acid (PAA), sodium Polyacrylate (PAAs), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium Alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS). The weight ratio of the binder in the negative electrode film layer is 0 to 30% by weight based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode film layer further optionally includes a conductive agent. The conductive agent is at least one selected from superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. The weight ratio of the conductive agent in the negative electrode film layer is 0-20% by weight based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode film layer may optionally further include other adjuvants, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)), and the like. The weight ratio of the other auxiliary agents in the negative electrode film layer is 0-15% by weight based on the total weight of the negative electrode film layer.

In some embodiments, the negative electrode sheet may be prepared by: dispersing the components for preparing the negative electrode plate, such as the negative electrode active material, the conductive agent, the binder and any other components, in a solvent (such as deionized water) to form a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70wt%, and the viscosity of the negative electrode slurry at room temperature is adjusted to 2000-10000 mPa.s; and (3) coating the obtained negative electrode slurry on a negative electrode current collector, and performing a drying procedure, cold pressing, such as a pair roller, to obtain a negative electrode plate. The unit area density of the negative electrode powder coating is 75-220 mg/m ², and the compacted density of the negative electrode plate is 1.2-2.0 g/m ³.

Electrolyte composition

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The application is not particularly limited in the kind of electrolyte, and may be selected according to the need. For example, the electrolyte may be liquid, gel, or all solid.

In some embodiments, the electrolyte is an electrolyte. The electrolyte includes an electrolyte salt and a solvent.

In some embodiments, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF ₆), lithium tetrafluoroborate (LiBF ₄), lithium perchlorate (LiClO ₄), lithium hexafluoroarsenate (LiAsF ₆), lithium bis-fluorosulfonimide (LiFSI), lithium bis-trifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalato borate (lipfob), lithium dioxaato borate (LiBOB), lithium difluorophosphate (LiPO ₂F ₂), lithium difluorodioxaato phosphate (LiDFOP), and lithium tetrafluorooxalato phosphate (LiTFOP). The concentration of the electrolyte salt is usually 0.5 to 5mol/L.

In some embodiments, the solvent may be selected from one or more of fluoroethylene carbonate (FEC), ethylene Carbonate (EC), propylene Carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl Propyl Carbonate (MPC), ethylene Propyl Carbonate (EPC), butylene Carbonate (BC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

In some embodiments, the electrolyte further optionally includes an additive. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives capable of improving certain properties of the battery, such as additives that improve the overcharge performance of the battery, additives that improve the high or low temperature performance of the battery, and the like.

In some embodiments, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into an electrode assembly through a winding process or a lamination process.

In some embodiments, the secondary battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and electrolyte described above.

In some embodiments, the outer package of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, or the like. The exterior package of the secondary battery may also be a pouch type pouch, for example. The material of the flexible bag may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate. The shape of the secondary battery is not particularly limited in the present application, and may be cylindrical, square, or any other shape. For example, fig. 1 is a secondary battery 5 of a square structure as one example.

In some embodiments, referring to fig. 2, the outer package may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate enclose a receiving chamber. The housing 51 has an opening communicating with the accommodation chamber, and the cover plate 53 can be provided to cover the opening to close the accommodation chamber. The positive electrode tab, the negative electrode tab, and the separator may be formed into the electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is enclosed in the accommodating chamber. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to specific practical requirements.

In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by one skilled in the art according to the application and capacity of the battery module.

Fig. 3 is a battery module 4 as an example. Referring to fig. 3, in the battery module 4, a plurality of secondary batteries 5 may be sequentially arranged in the longitudinal direction of the battery module 4. Of course, the arrangement may be performed in any other way. The plurality of secondary batteries 5 may be further fixed by fasteners.

Alternatively, the battery module 4 may further include a case having an accommodating space in which the plurality of secondary batteries 5 are accommodated.

In some embodiments, the above battery modules may be further assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and a specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.

Fig. 4 and 5 are battery packs 1 as an example. Referring to fig. 4 and 5, a battery case and a plurality of battery modules 4 disposed in the battery case may be included in the battery pack 1. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

In addition, the application also provides an electric device which comprises at least one of the secondary battery, the battery module or the battery pack. The secondary battery, the battery module, or the battery pack may be used as a power source of the power consumption device, and may also be used as an energy storage unit of the power consumption device. The power utilization device may include mobile devices (e.g., cell phones, notebook computers, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto. Such secondary batteries are suitable for various electric devices using batteries, such as cellular phones, portable devices, notebook computers, battery cars, electric toys, electric tools, electric automobiles, ships, and spacecraft, etc., including, for example, airplanes, rockets, space shuttles, and spacecraft, etc.

As the electricity consumption device, a secondary battery, a battery module, or a battery pack may be selected according to the use requirements thereof.

Fig. 6 is an electrical device as an example. The electric device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle or the like. In order to meet the high power and high energy density requirements of the secondary battery by the power consumption device, a battery pack or a battery module may be employed.

As another example, the device may be a cell phone, tablet computer, notebook computer, or the like. The device is generally required to be light and thin, and a secondary battery can be used as a power source.

Examples

In order to make the technical problems, technical schemes and beneficial effects solved by the application more clear, the application will be further described in detail below with reference to the embodiments and the accompanying drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses. All other embodiments, which can be made by a person skilled in the art based on the embodiments of the application without any inventive effort, are intended to fall within the scope of the application.

The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

Example 1:

preparation of a separation film:

The Li ₃InCl ₆ solid electrolyte is subjected to pre-calcination treatment, wherein the temperature of the pre-calcination treatment is 780 ℃, and the time of the pre-calcination treatment is 2 hours. Mixing the calcined Li ₃InCl ₆ solid electrolyte and a polyvinyl alcohol binder in ethanol, wherein the mass ratio of the Li ₃InCl ₆ solid electrolyte to the binder is 49:1. After mixing, ethanol was removed by air drying overnight at 90 ℃ to prepare a mixture. Grinding the mixture to a particle size of 10 mu m, and then cold-pressing and pressure maintaining for 1h under 200MPa to prepare a compacted material. And (3) calcining the compacted material, wherein the temperature of the calcining treatment is 780 ℃, and the calcining treatment time is 10 hours. And (5) obtaining the solid electrolyte target after calcination treatment.

The solid electrolyte target is subjected to sputtering treatment on a sputtering apparatus having a cooling function. A solid electrolyte layer is deposited on one surface of the polypropylene separator substrate layer. The sputtering conditions were: the sputtering power is 180W, the vacuum degree is 10 ^-1～10 ^-2 Pa, the sputtering time is 30min, the voltage is 1200V, and the current is 400mA. In the sputtering process, the temperature of the polypropylene isolating film substrate is controlled to be less than or equal to 100 ℃. A solid electrolyte layer having a thickness of 50nm was formed on one surface of the polypropylene separator base material layer by a sputtering process. The specific cooling mode is as follows: and connecting the sample table carrying the isolating film substrate layer with a cooling medium pipeline, and cooling the sample table through cooling in the cooling medium pipeline, so that the temperature of the isolating film substrate layer is controlled to be less than or equal to 100 ℃. The cooling medium is water.

The isolation film in this example was obtained after the sputtering treatment.

The SEM image of the polypropylene separator substrate layer is shown in fig. 7, and the SEM image of the separator obtained after the sputtering process is shown in fig. 8. As can be seen from fig. 7 and 8, after sputtering, a solid electrolyte layer having a uniform thickness is formed on the surface of the separator base material layer.

Preparing a positive electrode plate:

The preparation method comprises the following steps of mixing a Nickel Cobalt Manganese (NCM) ternary material, conductive agent carbon black, binder polyvinylidene fluoride (PVDF) and N-methyl pyrrolidone (NMP) according to a weight ratio of 97.34:28.86:2.7:1.1, stirring and mixing uniformly to obtain positive electrode slurry; and uniformly coating the positive electrode slurry on a positive electrode current collector, and drying, cold pressing and cutting to obtain the positive electrode plate.

Preparing a negative electrode plate:

The active material artificial graphite, conductive agent carbon black and binder polyvinylidene fluoride (PVDF) are mixed according to the weight ratio of 96.0:2.0:2.0, dissolving in deionized water serving as a solvent, and uniformly mixing to prepare negative electrode slurry; and uniformly coating the negative electrode slurry on a negative electrode current collector copper foil once or a plurality of times, and drying, cold pressing and cutting to obtain a negative electrode plate.

Preparation of electrolyte:

In an argon atmosphere glove box (H ₂O<0.1ppm,O ₂ <0.1 ppm), uniformly mixing an organic solvent of Ethylene Carbonate (EC)/ethylmethyl carbonate (EMC) according to a volume ratio of 3/7, adding 12.5% LiPF6 lithium salt for dispersion, and uniformly stirring to obtain an electrolyte.

Preparation of secondary battery:

and assembling the positive electrode plate, the isolating film and the negative electrode plate, injecting 120 mu L of electrolyte, compacting and standing for 2h.

Example 2

The present example was different from example 1 in that a solid electrolyte layer having a thickness of 10nm was formed on one surface of a polypropylene separator substrate layer by sputtering treatment.

Example 3

The present example was different from example 1 in that a solid electrolyte layer having a thickness of 1000nm was formed on one surface of a polypropylene separator substrate layer by sputtering treatment.

Example 4

The difference of this embodiment from embodiment 1 is that the sputtering power is 150W.

Example 5

The present embodiment is different from embodiment 1 in that the sputtering power is 200W.

Example 6

The present example was different from example 1 in that a solid electrolyte layer having a thickness of 100nm was formed on one surface of a polypropylene separator substrate layer by sputtering treatment.

Example 7

The present example was different from example 1 in that a solid electrolyte layer having a thickness of 5nm was formed on one surface of the polypropylene separator base material layer by sputtering treatment.

Example 8

The present embodiment is different from embodiment 1 in that the solid electrolyte is Li ₃MnCl ₆.

Example 9

The present embodiment is different from embodiment 1 in that the solid electrolyte is Li ₃ScCl ₆.

Example 10

The present embodiment is different from embodiment 1 in that the solid electrolyte is Li ₃ZrCl ₆.

Example 11

The present embodiment is different from embodiment 1 in that the solid electrolyte is Li ₃YCl ₆.

Example 12

The present embodiment is different from embodiment 1 in that the solid electrolyte is Li ₃InF ₆.

Example 13

The present example is different from example 1 in that a solid electrolyte layer is deposited on both surfaces of a polypropylene separator substrate layer. The solid electrolyte layer thickness of each side was 25nm.

Comparative example 1

The present comparative example is different from example 1 in that the separator is a polypropylene separator, and no solid electrolyte layer is formed on both surfaces of the polypropylene separator.

Comparative example 2

The difference of this comparative example from example 1 is that the temperature of the polypropylene separator substrate was not controlled during the sputtering process.

Comparative example 3

The present comparative example is different from example 1 in that a solid electrolyte layer was formed on one surface of a polypropylene separator substrate layer by coating by making the solid electrolyte into a slurry. The thickness of the solid electrolyte layer was 2000nm.

Test case

Battery capacity retention test: the batteries corresponding to examples and comparative examples were charged to 4.5V at a constant current of 1/3C, then charged to 0.05C at a constant voltage of 4.5V, left for 5min, then discharged to 2.8V at 1/3C, and the resulting capacity was designated as initial capacity C ₀. The above steps were repeated while recording the discharge capacity C _n of the battery after the nth cycle, and the battery capacity retention rate P _n＝C _n/C ₀ x 100% after each cycle. The capacity retention of the battery after 50 test cycles, i.e., the value of P ₅₀. The test results are shown in Table 1.

Testing the alternating current impedance of the battery: the positive electrode plates, the isolating films and the electrolyte 120uL in examples 1-3 and comparative examples 1-2 are assembled into a symmetrical battery of positive electrode, and the symmetrical battery is kept stand in an incubator at 25 ℃ for 2 hours to ensure the infiltration of the electrolyte. The alternating current impedance test adopts an electrochemical workstation impedance test module, a voltage disturbance mode PEIS, a disturbance voltage of 5mV, a frequency range of 200 kHZ-30 mHZ, a voltage range of 0-5V and a voltage protection of 0-5V, and the impedance spectrum in the figure 9 is obtained by drawing test data by taking the negative number (-Z ") of the imaginary part of the impedance as the ordinate and the real part Z as the abscissa.

Impedance test data fitting: impedance data of examples 1-3 and comparative examples 1-2 are subjected to data fitting by adopting Z-fit software, and a fitting circuit is selected to be R _s+C ₁/R _SEI+C ₂/R _ct +W, wherein R _s is ohmic impedance and is mainly related to the conductivity of the positive electrode material, and R _ct is charge transfer impedance and mainly reflects the deintercalation rate of lithium ions in the positive electrode material. The judgment basis of fitting requires: the error is less than 5% and the intersection with the real part should be <5% from the fitting to R _s. Fitting results meeting the above requirements can be selectively accepted, and R _ct and R _s in the fitting results are extracted and recorded in Table 1.

TABLE 1

As can be seen from table 1, the battery obtained in the example has better performance in cycle retention than the comparative example.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

Claims

A separator characterized by comprising a separator substrate layer and a solid electrolyte layer located on at least one surface of the separator substrate layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P.
The separator of claim 1, wherein M is a +3 cation.
The separator according to any one of claims 1-2, wherein M comprises one or more of Al ³⁺、Ga ³⁺、In ³⁺、Y ³⁺、Zr ³⁺、Nb ³⁺、Sc ³⁺、Ti ³⁺、Mn ³⁺、Er ³⁺、Tb ³⁺、Yb ³⁺、Lu ³⁺、La ³⁺ and Ho ³⁺.
A barrier film according to any one of claims 1 to 3, wherein X comprises one or more of F ^-、Cl ^-、Br ^-、I ^-、S ^2-、O ^2- and PO ₄ ^-.
The separator according to any one of claims 1 to 4, wherein the solid electrolyte layer comprises at least one of Li ₃InCl ₆、Li ₃MnCl ₆、Li ₃ScCl ₆、Li ₃ZrCl ₆、Li ₃YCl ₆、Li ₃InF ₆、Li ₃YCl ₆ and Li ₃ScF ₆.
The separator according to any one of claims 1 to 5, wherein the solid electrolyte layer satisfies at least one of the following characteristics:

(1) The thickness of the solid electrolyte layer is 5 nm-1000 nm; optionally 50nm to 100nm;

(2) The electrochemical window of the solid electrolyte layer is more than or equal to 4.2V;

(3) The ionic conductivity of the solid electrolyte layer is more than or equal to 10 ^-3 S/cm.
The preparation method of the isolating film is characterized by comprising the following steps:

Preparing a solid electrolyte target;

Sputtering the solid electrolyte target material on at least one surface of the isolating film substrate layer by adopting a magnetron sputtering method to form an isolating film,

The isolating film comprises an isolating film base material layer and a solid electrolyte layer positioned on at least one surface of the isolating film base material layer; the solid electrolyte layer comprises a material with a chemical composition of Li _aMX _a+3, wherein a is more than or equal to 1 and less than or equal to 6; m is selected from cations of one or more of the following elements: al, ga, in, Y, zr, nb, sc, ti, mn and an La series element; x is selected from anions containing one or more of the following elements: halogen, S, O and P.
The method of producing a separator according to claim 7, wherein the sputtering satisfies at least one of the following characteristics:

(1) The power of the sputtering is 150W-200W;

(2) The vacuum degree of the sputtering is 10 ^-1Pa～10 ^-2 Pa;

(3) And during sputtering, controlling the temperature of the base material layer of the isolating film to be less than or equal to 100 ℃.
A secondary battery comprising the separator according to any one of claims 1 to 6 or the separator produced according to the production method according to any one of claims 7 to 8.
A battery module comprising the secondary battery according to claim 9.
A battery pack comprising the secondary battery according to claim 9 or the battery module according to claim 10.
An electric device comprising at least one of the secondary battery according to claim 9, the battery module according to claim 10, and the battery pack according to claim 11.