Lithium ion battery, preparation method thereof and power utilization device

Abstract

The invention provides a lithium ion battery, a preparation method thereof and a power utilization device. The lithium ion battery comprises a diaphragm, wherein the diaphragm comprises a base material layer, a ceramic layer arranged on at least one surface of the base material layer and a binder layer arranged on the surface of the ceramic layer; the ceramic layer comprises a first additive, the first additive comprises a first transition metal ion capturing agent, the binder layer comprises a second additive and a second binder, and the second additive comprises a second transition metal ion capturing agent; the first transition metal ion trapping agent and the second transition metal ion trapping agent respectively and independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanurate and trithiol tetrabutylammonium salt. The diaphragm in the lithium ion battery can effectively reduce transition metal ions in the charging and discharging process of a battery cell, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a lithium-ion battery and its preparation method and power application device. Background Technology

[0002] The statements herein are provided only as background information in connection with this application and do not necessarily constitute prior art.

[0003] In recent years, the application of secondary batteries such as lithium-ion batteries has become increasingly widespread. They are now widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles and electric vehicles.

[0004] However, in traditional lithium-ion batteries, during the charging and discharging process of the cell, such as Cu... 2+ Mn 2+ Mn 3+ Cr 3+ Transition metal ions are prone to precipitation, affecting the cycle life of the battery. One method involves introducing metal ion trapping agents into the ceramic layer to capture the precipitated transition metal ions; however, this method has low ion trapping efficiency and is difficult to effectively improve cycle life. Summary of the Invention

[0005] To achieve the above objectives, this application provides a lithium-ion battery and its preparation method that can improve the capture efficiency of transition metal ions during the charging and discharging process of the battery cell and improve the cycle life of the battery, as well as an electrical device containing the lithium-ion battery.

[0006] A first aspect of this application provides a lithium-ion battery, the lithium-ion battery including a separator, the separator including a substrate layer, a ceramic layer disposed on at least one surface of the substrate layer, and an adhesive layer disposed on the surface of the ceramic layer;

[0007] The ceramic layer contains a first additive, which includes a first transition metal ion scavenger; the binder layer contains a second additive and a second binder, which includes a second transition metal ion scavenger.

[0008] The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate, and tetrabutylammonium trithiolate.

[0009] The aforementioned lithium-ion battery incorporates transition metal ion scavengers in both the ceramic layer and the binder layer, which improves the scavenging efficiency of transition metal ions and the battery cycle life.

[0010] In some embodiments, the first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of thiocarbamate and trisodium trithiocyanate.

[0011] In some embodiments, the sum of the thicknesses of the ceramic layer and the adhesive layer is 0.5 μm to 4 μm.

[0012] In some embodiments, the thickness of the ceramic layer is 0.25 μm to 2 μm; and / or, the thickness of the adhesive layer is 0.25 μm to 2 μm.

[0013] In some embodiments, the mass percentage of the first transition metal ion scavenger in the ceramic layer is 5% to 25%.

[0014] In some embodiments, the second transition metal ion scavenger accounts for 5% to 40% by mass in the adhesive layer.

[0015] In some embodiments, the adhesive layer covers 20% to 60% of the surface area of ​​the ceramic layer.

[0016] In some embodiments, the adhesive layer covers 30% to 40% of the surface area of ​​the ceramic layer.

[0017] In some embodiments, the ceramic layer further comprises a dispersant, a ceramic filler, a thickener, a first binder, and a wetting agent.

[0018] In some embodiments, the ceramic layer has one or more of the following characteristics:

[0019] (1) The dispersant includes one or more of organic sulfonates, sulfonated fatty alcohols, polypropylene ethers and polyethylene glycol;

[0020] (2) The ceramic filler includes one or more of the following: boehmite, alumina, magnesium oxide, barium sulfate, and magnesium hydroxide;

[0021] (3) The thickener includes one or more of sodium carboxymethyl cellulose and sodium carboxymethyl acrylate;

[0022] (4) The first adhesive includes one or more of acrylates, acrylics, and polyvinylidene fluoride;

[0023] (5) The wetting agent includes one or more of fatty acid sulfates, fatty acid ester sulfates, carboxylic acid soaps and phosphate esters.

[0024] In some embodiments, the first additive further includes a first capsule shell comprising a first organic polymer, the first transition metal ion scavenger being disposed within the first capsule shell to form first capsule particles; and / or

[0025] The second additive also includes a second capsule shell, the second capsule shell comprising a second organic polymer, and the second transition metal ion scavenger disposed within the second capsule shell to form second capsule microparticles;

[0026] Both the first organic polymer and the second organic polymer have swelling properties.

[0027] In some embodiments, the first organic polymer and the second organic polymer each independently comprise a graft copolymer of one or at least two of polyurea, polyurea-polyurethane, polyethylene, polycarbonate, diethyl terephthalate, polytetrafluoroethylene, and polyacrylic acid resin.

[0028] In some embodiments, the lithium-ion battery has one or more of the following features:

[0029] (1) The volumetric particle size Dv50 of the first capsule microparticle and / or the second capsule microparticle is 2μm to 10μm;

[0030] (2) The thickness of the first capsule shell and / or the second capsule shell is 0.1 μm to 8 μm;

[0031] (3) The mass ratio of the first capsule shell to the first transition metal ion scavenger is (1-15):1;

[0032] (4) The mass ratio of the second capsule shell to the second transition metal ion scavenger is (1-15):1.

[0033] A second aspect of this application provides a method for preparing a lithium-ion battery, including a separator preparation step, wherein the separator preparation step includes:

[0034] A ceramic layer is prepared on the surface of a substrate layer, the ceramic layer comprising a first additive, the first additive comprising a first transition metal ion scavenger;

[0035] An adhesive layer is prepared on the surface of the ceramic layer to prepare an intermediate component. The adhesive layer contains a second additive and a second adhesive, wherein the second additive contains a second transition metal ion scavenger.

[0036] The intermediate components are press-fitted.

[0037] The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate, and tetrabutylammonium trithiolate.

[0038] A third aspect of this application provides an electrical device comprising at least one of the lithium-ion batteries described in the first aspect and the lithium-ion batteries prepared by the preparation method described in the second aspect. Attached Figure Description

[0039] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0040] Figure 1 This is a schematic diagram of a lithium-ion battery according to one embodiment of this application.

[0041] Figure 2 for Figure 1 An exploded view of a lithium-ion battery according to an embodiment of this application is shown.

[0042] Figure 3 This is a schematic diagram of an electrical device that uses a lithium-ion battery as a power source according to one embodiment of this application.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1. Lithium-ion battery; 11. Casing; 12. Electrode assembly; 13. Cover plate; 2. Electrical device. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0046] Unless otherwise defined, 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 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.

[0047] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the specific range. Ranges defined in this way can include or exclude endpoints. Any endpoint can be included or excluded independently, and they can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are also listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0" and "5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer ≥ 2, it is equivalent to listing integers such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, when a parameter is described as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0048] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

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

[0050] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "implementation" as used herein has a similar understanding.

[0051] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0052] In this application, open-ended technical features or solutions described using terms such as "containing," "including," or "comprising" do not exclude additional members beyond those listed unless otherwise specified. They can be considered as providing both closed-ended features or solutions comprised of the listed members and open-ended features or solutions that include additional members beyond the listed members. For example, if A includes a1, a2, and a3, it may also include other members or exclude additional members unless otherwise specified. This can be considered as providing both the feature or solution that "A consists of a1, a2, and a3" and the feature or solution that "A includes not only a1, a2, and a3, but also other members."

[0053] In this application, unless otherwise specified, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0054] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0055] Traditional methods introduce metal ion scavengers into the ceramic layer to capture deposited transition metal ions. However, this method suffers from low ion capture efficiency, making it difficult to effectively improve cycle life. Increasing the amount of transition metal ion scavenger can improve the capture efficiency, but it also increases the thickness of the ceramic layer, hindering its ion transport properties. To avoid affecting the ion transport performance of the ceramic layer itself, the amount of transition metal ion scavenger introduced into the ceramic layer using traditional methods is very limited. Therefore, the capture efficiency of transition metal ions during battery cycling is low, and it is difficult to effectively improve cycle life.

[0056] Based on this, this application provides a lithium-ion battery, the lithium-ion battery including a separator, the separator including a substrate layer, a ceramic layer disposed on at least one surface of the substrate layer, and an adhesive layer disposed on the surface of the ceramic layer; the ceramic layer includes a first additive, the first additive including a first transition metal ion scavenger, the adhesive layer including a second additive and a second adhesive, the second additive including a second transition metal ion scavenger; the first transition metal ion scavenger and the second transition metal ion scavenger each independently include one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate and tetrabutylammonium trithiolate.

[0057] The aforementioned lithium-ion battery incorporates transition metal ion scavengers in both the ceramic and binder layers, increasing the amount of these scavengers. Furthermore, the selection of specific types of transition metal ion scavengers ensures compatibility with both the ceramic and binder layers, resulting in good dispersion and reducing issues such as membrane delamination. During cycling, the transition metal ion scavengers effectively filter transition metal ions, significantly enhancing their scavenging efficiency. Moreover, the binder layer thins during subsequent cell lamination and may even partially fuse into the ceramic layer, minimizing its impact on the separator's ion transport characteristics. In short, while improving transition metal ion scavenging efficiency and battery cycle life, the battery also exhibits excellent ion transport properties.

[0058] Without limitation, the ceramic layer may be disposed on one side or both sides of the substrate layer. Furthermore, without limitation, the substrate layer may be one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0059] In some embodiments, the first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of thiocarbamate and trisodium trithiocyanate. Using a suitable transition metal ion scavenger can better enhance the scavenging effect of transition metal ions and improve cycle performance.

[0060] In some embodiments, the sum of the thicknesses of the ceramic layer and the adhesive layer is 0.5 μm to 4 μm. By providing transition metal ion scavengers in both the ceramic layer and the adhesive layer, the total thickness of the ceramic layer and the adhesive layer can be minimized while increasing the amount of transition metal ion scavenger added, thereby improving ion transport performance. Specifically, the sum of the thicknesses of the ceramic layer and the adhesive layer includes, but is not limited to, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, or any range between the foregoing. Without limitation, the thickness of the ceramic layer is 0.25 μm to 2 μm; the thickness of the adhesive layer is 0.25 μm to 2 μm.

[0061] In some embodiments, the mass percentage of the first transition metal ion scavenger in the ceramic layer is 5% to 25%. This achieves effective capture of transition metal ions while obtaining good ion transport characteristics. Specifically, the mass percentage of the first transition metal ion scavenger includes, but is not limited to: 5%, 10%, 15%, 20%, 25%, or any range between the foregoing.

[0062] In some embodiments, the second transition metal ion scavenger comprises 5% to 40% by mass in the adhesive layer. This achieves effective capture of transition metal ions while obtaining good ion transport characteristics. Specifically, the mass percentage of the second transition metal ion scavenger includes, but is not limited to: 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range between the foregoing.

[0063] In some embodiments, the adhesive layer covers a portion of the surface of the ceramic layer. Further, in some embodiments, the area coverage of the adhesive layer on the surface of the ceramic layer is 20% to 60%. The second transition metal ion trapping agent, covered by the adhesive layer on the surface of the ceramic layer, has a certain impact on the ion transport performance of the membrane. Further reasonable control of this coverage can achieve effective trapping of transition metal ions while obtaining better ion transport characteristics. Specifically, the area coverage of the adhesive layer on the surface of the ceramic layer includes, but is not limited to: 20%, 25%, 30%, 35%, 40%, 55%, 60%, 65%, 60%, or any range between the foregoing. Further, the area coverage of the adhesive layer on the surface of the ceramic layer is 30% to 40%.

[0064] Furthermore, without limitation, the second adhesive includes one or more of acrylates, acrylics, and polyvinylidene fluoride (PVDF). In some embodiments, the second adhesive comprises 60% to 95% by mass in the adhesive layer.

[0065] In some embodiments, the ceramic layer further comprises a dispersant, a ceramic filler, a thickener, a first binder, and a wetting agent.

[0066] In some embodiments, the ceramic layer further comprises a dispersant, a ceramic filler, a thickener, and a first binder; optionally, it also includes a wetting agent. By rationally compounding the components of the ceramic layer, particularly by using a combination of dispersants and thickeners, it is beneficial to obtain a thinner and more controllable ceramic layer, further reducing the impact of the introduction of transition metal ion scavengers on the ion transport performance of the ceramic layer itself, and facilitating construction with good process consistency.

[0067] Further, the dispersant includes one or more of organic sulfonates, sulfonated fatty alcohols, polypropylene ethers, and polyethylene glycol. In some embodiments, the mass percentage of the dispersant in the ceramic layer is 2% to 4%. Specifically, the mass percentage of the dispersant includes, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, or any range between the foregoing.

[0068] Further, the ceramic filler comprises one or more of bauxite, alumina, magnesium oxide, barium sulfate, and magnesium hydroxide. In some embodiments, the dispersant in the ceramic layer comprises 50% to 95% by mass. Specifically, the mass percentage of the dispersant includes, but is not limited to, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or any range between the foregoing.

[0069] Further, the thickener includes one or more of sodium carboxymethyl cellulose and sodium carboxymethyl acrylate. In some embodiments, the mass percentage of the thickener in the ceramic layer is 0.1% to 1%. Specifically, the mass percentage of the thickener includes, but is not limited to: 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or a range between any two of the foregoing.

[0070] Further, the first adhesive comprises one or more of acrylates, acrylics, and polyvinylidene fluoride (PVDF). In some embodiments, the mass percentage of the first adhesive in the ceramic layer is 1% to 10%. Specifically, the mass percentage of the first adhesive includes, but is not limited to: 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any range between the foregoing.

[0071] Further, the wetting agent includes one or more of fatty acid sulfates, fatty acid ester sulfates, carboxylic acid soaps, and phosphate esters. In some embodiments, the wetting agent constitutes 0.5% to 1.5% by mass in the ceramic layer. Specifically, the mass percentage of the wetting agent includes, but is not limited to, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, or any range between the foregoing.

[0072] In other embodiments, the first additive further includes a first capsule shell comprising a first organic polymer, wherein the first alkaline metal oxide is disposed within the first capsule shell to form first capsule particles; and / or

[0073] The second additive also includes a second capsule shell, the second capsule shell comprising a second organic polymer, and the second alkaline metal oxide disposed within the second capsule shell to form second capsule microparticles;

[0074] Both the first organic polymer and the second organic polymer have swelling properties.

[0075] In the early stages of cell cycling, transition metal ions aggregate and remain stably present in the capsule microparticles. The nanochannels present in the organic polymer can conduct electrolyte and metal ions, reducing the impact on ion transport characteristics. As the cycling time progresses, the organic polymer with swelling properties gradually swells in the electrolyte and expands the nanochannels. The transition metal ion capture agent in the core is gradually released, effectively capturing the generated transition metal ions.

[0076] In some embodiments, the swelling rates of the first organic polymer and the second organic polymer after immersion in an electrolyte at 60°C for 14 days are each independently 10% to 20%. Reasonable control of this swelling rate is beneficial for the sustained release of the transition metal ion scavenger, resulting in better transition metal ion scavenging effect. Specifically, the swelling rate includes, but is not limited to: 10%, 11%, 12%, 13%, 14%, 15%, 18%, 20%, or any range between the foregoing. It is understood that the electrolyte is a lithium-ion electrolyte. In some embodiments, the solvent of the electrolyte includes carbonate solvents. Specifically, the solvent of the electrolyte includes ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 1:1:1.

[0077] In some embodiments, the first organic polymer and the second organic polymer each independently comprise a graft copolymer of one or at least two of polyurea, polyurea-polyurethane, polyethylene, polycarbonate, diethyl terephthalate, polytetrafluoroethylene, and polyacrylic acid resin.

[0078] Furthermore, the sustained release of transition metal ion scavengers can be controlled by adjusting the particle size Dv50 of the capsule microparticles, the thickness of the capsule shell, and the ratio of the capsule shell to the transition metal ion scavenger, thereby achieving a better transition metal ion scavenging effect.

[0079] In some embodiments, the volumetric particle size Dv50 of the first and / or second capsule particles is 2 μm to 10 μm. Specifically, the volumetric particle size Dv50 includes, but is not limited to, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any range between the two aforementioned.

[0080] In some embodiments, the thickness of the first capsule shell and / or the second capsule shell is 0.1 μm to 8 μm. Specifically, the thickness includes, but is not limited to: 0.1 μm, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, or any range between the foregoing.

[0081] In some embodiments, the mass ratio of the first capsule shell to the first transition metal ion scavenger is (1 to 15):1. Specifically, the mass ratio includes, but is not limited to: 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, or any range between the two aforementioned.

[0082] In some embodiments, the mass ratio of the second capsule shell to the second transition metal ion scavenger is (1 to 15):1. Specifically, the mass ratio includes, but is not limited to: 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, or any range between the two aforementioned.

[0083] In other embodiments of this application, a method for preparing a lithium-ion battery is provided, including a separator preparation step, wherein the separator preparation step includes:

[0084] A ceramic layer is prepared on the surface of a substrate layer, the ceramic layer comprising a first additive, the first additive comprising a first transition metal ion scavenger;

[0085] An adhesive layer is prepared on the surface of the ceramic layer to prepare an intermediate component. The adhesive layer contains a second additive and a second adhesive, wherein the second additive contains a second transition metal ion scavenger.

[0086] The intermediate components are press-fitted.

[0087] The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate, and tetrabutylammonium trithiolate.

[0088] Understandably, the technical solutions for the ceramic layer and binder layer are the same as those for lithium-ion batteries, and will not be elaborated here.

[0089] Understandably, in embodiments comprising the first capsule microparticles and / or the second capsule microparticles, a step of microencapsulating the first transition metal ion scavenger and / or the second transition metal ion scavenger is further included. Specifically, the preparation step of the first capsule microparticles includes: mixing, emulsifying, and spray-drying the first transition metal ion scavenger with the first organic polymer to prepare first capsule microparticles with the first organic polymer as the capsule shell and the first transition metal ion scavenger as the inner core. The preparation step of the second capsule microparticles is similar and will not be described in detail here.

[0090] In other embodiments of this application, an electrical device is provided, comprising at least one of the lithium-ion battery described above and the lithium-ion battery prepared by the preparation method described above.

[0091] The lithium-ion battery and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0092] Typically, a lithium-ion battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During charging and discharging, active ions move back and forth between the positive and negative electrodes, inserting and extracting. The electrolyte acts as a conductor between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, primarily prevents short circuits while allowing ions to pass through.

[0093] Specifically, the diaphragm in some embodiments of this application is as described above.

[0094] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0095] As a non-limiting example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0096] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be obtained by forming a metal material on the polymer material substrate. Non-limiting examples of the metal material in the positive electrode current collector may include one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymer material substrate in the positive electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0097] In some embodiments, the positive electrode active material may be a known positive electrode active material for batteries. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, one or more of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides, lithium manganese oxides, lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, lithium nickel cobalt aluminum oxides, and their modified compounds. Non-limiting examples of lithium-containing phosphates with an olivine structure include, but are not limited to, one or more of lithium iron phosphate, lithium iron phosphate and carbon composites, lithium manganese phosphate, lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium manganese iron phosphate and carbon composites. Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 Examples of lithium nickel cobalt aluminum oxides include LiNi, etc. 0.8 Co 0.15 Al 0.05 O2.

[0098] In some embodiments, the positive electrode active material layer may optionally include a binder. As a non-limiting example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0099] In some embodiments, the positive electrode active material layer may optionally include a conductive agent. As a non-limiting example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0100] In some embodiments, the positive electrode sheet can be prepared by dispersing the components used to prepare the positive electrode sheet, such as the positive electrode active material, conductive agent, binder, and any other components, in a solvent to form a positive electrode slurry; coating the positive electrode slurry onto at least one surface of the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing, and other processes. The solvent can be selected from, but is not limited to, any of the solvents described in the foregoing embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode current collector coated with the positive electrode slurry can be a single surface or both surfaces of the positive electrode current collector. The solid content of the positive electrode slurry can be 40 wt% to 80 wt%. The viscosity of the positive electrode slurry at room temperature can be adjusted to 5000 mPa·s to 25000 mPa·s. When coating the positive electrode slurry, the coating areal density per unit area, based on dry weight (excluding solvent), can be 15 mg / cm³. 2 ~35mg / cm 2 The compaction density of the positive electrode sheet can be 3.0 g / cm³. 3 ~3.6g / cm 33.3g / cm³ is an option. 3 ~3.5g / cm 3 .

[0101] The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one surface of the negative current collector, wherein the negative active material layer includes a negative active material.

[0102] As a non-limiting example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0103] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymeric material substrate and a metal layer formed on at least one surface of the polymeric material substrate. The composite current collector can be obtained by forming a metal material on the polymeric material substrate. Non-limiting examples of the metal material in the negative electrode current collector may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. Non-limiting examples of the polymeric material substrate in the negative electrode current collector may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0104] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As a non-limiting example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0105] In some embodiments, the negative electrode active material layer may optionally include a binder. The binder may include one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0106] In some embodiments, the negative electrode active material layer may optionally include a conductive agent. The conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0107] In some embodiments, the negative electrode active material layer may also optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0108] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder, and any other components, in a solvent (a non-limiting example of a solvent is deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto at least one surface of a negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing, and other processes. The surface of the negative electrode current collector coated with the negative electrode slurry can be a single surface of the negative electrode current collector or both surfaces of the negative electrode current collector. The solid content of the negative electrode slurry can be 40wt% to 60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000 mPa·s to 10000 mPa·s. When coating the negative electrode slurry, the coating unit areal density (dry weight, minus solvent) can be 75 g / m². 2 ~220g / m 2 The compaction density of the negative electrode sheet can be 1.0 g / cm³. 3 ~1.8g / cm 3 .

[0109] Electrolytes function to conduct ions between the positive and negative electrode plates. This application does not impose any particular restrictions on the type of electrolyte; it can be selected according to requirements. For example, the electrolyte can be liquid, gel, or completely solid.

[0110] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0111] In some embodiments, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0112] In some embodiments, the solvent may include ethylene carbonate (EC, ), propylene carbonate (PC, ), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butene carbonate Fluoroethylene carbonate (FEC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0113] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0114] In some embodiments, the additives in the electrolyte may include, but are not limited to, one or more of fluoroethylene carbonate (FEC), difluoroethylene carbonate (DFEC), trifluoromethyl ethylene carbonate (TFPC), etc.

[0115] In some embodiments, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding process or a stacking process.

[0116] In some embodiments, the lithium-ion battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0117] In some embodiments, the outer packaging of the lithium-ion battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the lithium-ion battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic; further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0118] A lithium-ion battery includes at least one battery cell. A lithium-ion battery may include one or more battery cells.

[0119] In this application, unless otherwise specified, "cell battery" refers to the basic unit capable of converting chemical energy into electrical energy, and generally includes at least a positive electrode, a negative electrode, and an electrolyte. During the charging and discharging process of the battery, active ions move back and forth between the positive and negative electrode plates, inserting and extracting. The electrolyte acts as a conductor for the active ions between the positive and negative electrode plates.

[0120] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 1 This is an example of a square-structured lithium-ion battery 1.

[0121] In some of these embodiments, reference is made to Figure 2 The outer packaging may include a housing 11 and a cover plate 13. The housing 11 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be placed over the opening to close the receiving cavity. Positive electrode sheets, negative electrode sheets, and a separator can be formed into an electrode assembly 12 via a winding process or a stacking process. The electrode assembly 12 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 12. The lithium-ion battery 1 may contain one or more electrode assemblies 12, which can be selected by those skilled in the art according to actual needs.

[0122] Lithium-ion batteries can be battery modules or battery packs.

[0123] A battery module includes at least one battery cell. The number of battery cells in a battery module can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module.

[0124] In a battery module, multiple battery cells can be arranged sequentially along the length of the module. Of course, they can also be arranged in any other manner. Furthermore, these battery cells can be secured using fasteners.

[0125] Optionally, the battery module may also include a housing with a receiving space in which multiple battery cells are housed.

[0126] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more. Those skilled in the art can select an appropriate number according to the application and capacity of the battery pack.

[0127] The battery pack may include a battery box and multiple battery modules disposed within the battery box. The battery box includes an upper body and a lower body, with the upper body covering the lower body to form a closed space for accommodating the battery modules. The multiple battery modules can be arranged in any manner within the battery box.

[0128] In addition, this application also provides an electrical device, which includes the lithium-ion battery provided in this application. The lithium-ion battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Among them, mobile devices may be, for example, mobile phones, laptops, etc.; electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to.

[0129] As an electrical device, lithium-ion batteries can be selected based on its usage requirements.

[0130] Figure 3 Here is an example of an electrical device 2. This electrical device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of lithium-ion batteries for this electrical device, a battery pack or battery module can be used.

[0131] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0132] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0133] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0134] Preparation Example 1

[0135] This embodiment provides a diaphragm, the structure of which includes a substrate layer (a PE polymer microporous film with a thickness of 7μm and an average pore size of 80nm (from Zhuogao Electronics Technology Co., Ltd.), a ceramic layer sequentially disposed on both sides of the substrate layer, and an adhesive layer. The preparation method is as follows:

[0136] (1) The transition metal ion scavenger trisodium trithiocyanate, the dispersant sulfonated fatty alcohol, the inorganic filler borosilicate, the thickener sodium carboxymethyl cellulose, the binder PVDF and the wetting agent fatty acid sulfide are mixed with water in a ratio of 25%:3%:64.5%:0.5%:6%:1% and stirred thoroughly to prepare a ceramic layer slurry; the ceramic layer slurry is scraped onto one side surface of the substrate layer and dried to obtain a ceramic layer with a thickness of 0.5 μm.

[0137] (2) The transition metal capture agent trisodium trithiocyanate and the binder PVDF are mixed in a ratio of 35%:65% and stirred thoroughly to prepare the binder layer slurry; the binder layer slurry is sprayed onto the surface of the ceramic layer and dried to obtain the binder layer. The coverage of the binder layer on the surface of the ceramic layer is 35% and the thickness is 0.5μm.

[0138] The preparation methods for the diaphragms in Examples 2-8 are the same as in Example 1, with the main differences shown in Table 1:

[0139] Table 1

[0140]

[0141] Note: In Examples 2-4, after the mass percentage of the scavenger in the ceramic layer is changed, the mass percentage of the inorganic filler borosilicate is changed accordingly to meet 100%. After the mass percentage of the scavenger in the binder layer is changed, the mass percentage of the binder PVDF is changed accordingly to meet 100%.

[0142] Preparation Example 8

[0143] The preparation method of the diaphragm in Example 8 is the same as that in Example 1, the main difference being that the transition metal ion scavenger in the binder layer is made into capsule microparticles.

[0144] (1) Preparation of capsule microparticles:

[0145] 2.1 Mix 10g of trisodium trithiocyanate core material with a water-ethanol (4:1) mixture;

[0146] 2.2 Add 50g of polytetrafluoroethylene emulsion (with a swelling rate of 15% after soaking in electrolyte at 60℃ for 14 days, see application examples for electrolyte) to an appropriate amount of deionized water and dilute to a solid content of 20%. Then add 10g of polyacrylic acid resin (with a swelling rate of 20% after soaking in electrolyte at 60℃ for 14 days, see application examples for electrolyte). Then add the mixture prepared in step 2.1 under stirring conditions and emulsify and disperse it in an emulsifier at 40℃ for 60 minutes at a speed of 3000r / min.

[0147] 2.3 The emulsified slurry from step 2.2 was spray-dried using a spray dryer at a temperature of 80°C. The atomized slurry droplets evaporated and dried instantly, and fluffy trisodium trithiocyanate capsules were collected. The volumetric particle size Dv50 was 3 μm, the capsule shell thickness was about 1 μm, and the mass ratio of the capsule shell to the inner core trisodium trithiocyanate was 2.5:1.

[0148] (2) Replace the trisodium trithiocyanate in the adhesive layer of Example 1 with the trisodium trithiocyanate capsule microparticles prepared in step (1), while keeping the proportion of trisodium trithiocyanate in the adhesive layer unchanged.

[0149] Preparation Example 9

[0150] The preparation method of the diaphragm in Example 9 is the same as that in Example 1, the main difference being that the transition metal ion scavenger in the ceramic layer is made into capsule microparticles.

[0151] (1) Preparation of capsule microparticles:

[0152] Same as in Preparation Example 8.

[0153] (2) Replace the trisodium trithiocyanate in the ceramic layer of Example 1 with the trisodium trithiocyanate capsule microparticles prepared in step (1), while keeping the proportion of trisodium trithiocyanate in the ceramic layer unchanged.

[0154] Preparation Example 10

[0155] The preparation method of the diaphragm in Example 10 is the same as that in Example 1, the main difference being that the transition metal ion scavenger in the binder layer and ceramic layer is made into capsule microparticles.

[0156] (1) Preparation of capsule microparticles:

[0157] Same as in Preparation Example 8.

[0158] (2) Replace the trisodium trithiocyanate in the adhesive layer of Example 1 with the trisodium trithiocyanate capsule microparticles prepared in step (1), while keeping the proportion of trisodium trithiocyanate in the adhesive layer unchanged. At the same time, replace the trisodium trithiocyanate in the ceramic layer of Example 1 with the trisodium trithiocyanate capsule microparticles prepared in step (1), while keeping the proportion of trisodium trithiocyanate in the ceramic layer unchanged.

[0159] Preparation of Comparative Example 1

[0160] The preparation method of the diaphragm in Comparative Example 1 is the same as that in Example 5, the main difference being that no transition metal scavenging agent, trisodium trithiocyanate, was added to either the binder layer or the ceramic layer.

[0161] Preparation of Comparative Example 2

[0162] The preparation method of the diaphragm in Comparative Example 2 is the same as that in Example 5, except that the transition metal scavenger trisodium trithiocyanate was not added to the binder layer.

[0163] Preparation of Comparative Example 3

[0164] The preparation method of the diaphragm in Comparative Example 3 is the same as that in Example 1, the main difference being that sodium ethylenediaminetetraacetate is used instead of trisodium trithiocyanate, the transition metal ion scavenger, in the ceramic layer and binder layer. In this example, the prepared ceramic layer suffers from significant detachment, making it difficult to complete the diaphragm preparation process.

[0165] Application Examples

[0166] The separators from the preparation examples and comparative examples were applied to lithium-ion batteries, and the preparation methods of these lithium-ion batteries are as follows:

[0167] 1) Preparation of positive electrode sheet

[0168] A positive electrode slurry was prepared by thoroughly mixing polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), conductive agent carbon black, and N-methylpyrrolidone (NMP) at a mass ratio of 1.2:58.38:0.42:40. The positive electrode slurry was then subjected to a 200 g / m³ concentration. 2 The loading amount is uniformly coated on the positive current collector aluminum foil, and then dried, cold pressed and cut to obtain the positive electrode sheet;

[0169] 2) Preparation of negative electrode sheet

[0170] Artificial graphite, conductive agent acetylene black, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were added to deionized water at a mass ratio of 96.2:1.0:1.6:1.2. The mixture was thoroughly stirred and mixed to prepare a negative electrode slurry (solid content 63%). This negative electrode slurry was then subjected to a concentration of 98 g / m³. 2 The loading amount is coated on the negative electrode current collector copper foil, and then dried, cold pressed and cut to obtain the negative electrode sheet;

[0171] 3) Diaphragm

[0172] One of the diaphragms in the preparation examples and comparative examples.

[0173] 4) Preparation of electrolyte

[0174] At 25°C, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain a mixed solvent. LiPF6 is then dissolved in the above mixed solvent to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol / L.

[0175] 5) Battery manufacturing

[0176] The positive electrode, separator, and negative electrode are stacked, wound, and cold-pressed in sequence to obtain the battery cell. The battery cell is placed in an outer packaging, electrolyte is added, and after processes such as encapsulation, standing, formation, and aging, a lithium-ion battery is obtained.

[0177] Test case

[0178] (1) Transition metal ion capture effect:

[0179] 1.1 Preparation of the test stock solution:

[0180] Dissolve 0.056 g of organic manganese salt (manganese oxalate) in 40 mL of lithium-ion electrolyte (E151), shake well, place in a 45 °C oven for 40 min and let stand to obtain test stock solution 1 containing 1492 ppm manganese ions (measured value);

[0181] Dissolve 15.63g of organic copper salt (copper oxalate) in 40mL of lithium-ion electrolyte (E151), shake well and place in a 45℃ oven for 40min to stand, and you will get test stock solution 2 containing 328ppm copper ions (measured value).

[0182] Dissolve 0.04 g of organic chromium salt (chromium oxalate) in 40 mL of lithium-ion electrolyte (E151), shake well, place in a 45 °C oven for 40 min and let stand to obtain test stock solution 3 containing 104 ppm chromium ions (measured value).

[0183] 1.2 Sample Testing:

[0184] The diaphragms prepared in the above examples and comparative examples were cut into samples of 148.5 mm x 105 mm. The diaphragm samples were laid flat in a ceramic funnel with a diameter of 80 mm for testing. The original test solutions were poured into the ceramic funnel and allowed to stand for 10 hours to obtain the solution to be measured by ICP after diaphragm filtration. A sample of more than 10 mL was placed in a centrifuge tube for ICP (inductively coupled plasma atomic emission spectrometry) electrolyte element metal ion concentration determination. The determination method was as follows: the test solution was digested on a plate with concentrated nitric acid as the digestion reagent, and the spectroscopic determination was performed using an ICP device.

[0185] (2) Capacity retention test:

[0186] 2.1 Initial capacity test:

[0187] The cells fabricated from the corresponding samples were subjected to a 0.1C charge-discharge test at room temperature (25℃±5℃) using an electrochemical workstation (full charge voltage of 4V and minimum discharge voltage of 2V) to obtain the initial cell capacity value. The weight of active material per unit area was calculated, and the initial specific capacity was obtained by comparing the capacity with the weight.

[0188] 2.2 Charge retention capability test:

[0189] Before testing the capacity of the battery cells made from the corresponding samples, they were placed at room temperature (25℃±5℃) for 30 days and the remaining charge value was measured again. The comparison before and after is the charge retention capacity.

[0190] 2.3 Capacity recovery capability test:

[0191] Before testing the capacity of the battery cells made from the corresponding samples, the cells were charged and discharged 500 times at 1 / 3C conditions (full charge voltage of 4V and minimum discharge voltage of 2V) at room temperature (25℃±5℃). The capacity value that could be achieved after returning to the state before the test was recorded and compared with the initial value. This value is the capacity recovery capability.

[0192] 2.4 25℃, 1C / 1C Capacity Retention Performance Test: Place the battery cell in a 25℃ environment and let it stand for 2 hours. After the battery temperature reaches 25℃, charge the battery to 4.2V at a constant current of 1C and constant voltage, charge it to the cutoff current of 0.05C at constant voltage, let it rest for 5 minutes, and then discharge it to 2.8V at 1C. Record the initial capacity Q0 and the capacity after each cycle. Use the capacity of the previous discharge as the battery capacity Q2 and calculate the capacity retention rate (%) (the calculation formula is as follows: cycle capacity retention rate = Q2 / Q0 × 100%). Record the capacity retention rate of the battery cell after 1000 cycles.

[0193] 2.5 Capacity retention performance test at 45℃, 1C / 1C:

[0194] Place the battery cell in a 45℃ environment and let it stand for 2 hours. After the battery temperature reaches 45℃, conduct the test according to the "25℃, 1C / 1C capacity retention performance test" test procedure and calculate the capacity retention rate.

[0195] (3) Ionic conductivity test:

[0196] Preparation of the button cell for testing: In a vacuum glove box, place a lithium sheet into the negative electrode shell of the battery, add the specified electrolyte, then place the prepared separator in place to ensure it adheres tightly to the lithium sheet, add the specified electrolyte again, and finally place the positive electrode on top and seal it. Remove the assembled button cell from the vacuum glove box and let it stand for 24 hours for the next step of testing.

[0197] Test method: The test was conducted within a specific frequency range on an electrochemical workstation to obtain the isolation membrane resistance Rb, and the ionic conductivity σ (unit: S·cm) was calculated using the following formula. -1 ):

[0198]

[0199] Where Rb is the bulk resistance of the diaphragm, and L and S are the thickness and area of ​​the diaphragm under test, respectively.

[0200] The test results are shown in Table 2 below.

[0201] Table 2

[0202]

[0203] Note: D represents the comparative example, and S represents the embodiment.

[0204] As can be seen, compared with the comparative example, the embodiment can effectively improve the capture effect and cycle performance of transition metal ions by introducing specific transition metal ion scavengers in both the ceramic layer and the binder layer, while having little impact on the ion transport characteristics of the membrane.

[0205] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0206] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A lithium-ion battery, the lithium-ion battery comprising a separator, characterized in that, The diaphragm includes a substrate layer, a ceramic layer disposed on at least one surface of the substrate layer, and an adhesive layer disposed on the surface of the ceramic layer; The ceramic layer contains a first additive, which includes a first transition metal ion scavenger; the binder layer contains a second additive and a second binder, which includes a second transition metal ion scavenger. The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate, and tetrabutylammonium trithiolate.

2. The lithium-ion battery according to claim 1, characterized in that, The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of thiocarbamate and trisodium trithiocyanate.

3. The lithium-ion battery according to claim 1 or 2, characterized in that, The sum of the thicknesses of the ceramic layer and the adhesive layer is 0.5 μm to 4 μm.

4. The lithium-ion battery according to claim 3, characterized in that, The thickness of the ceramic layer is 0.25 μm to 2 μm; and / or the thickness of the adhesive layer is 0.25 μm to 2 μm.

5. The lithium-ion battery according to any one of claims 1 to 4, characterized in that, In the ceramic layer, the mass percentage of the first transition metal ion scavenger is 5% to 25%.

6. The lithium-ion battery according to any one of claims 1 to 5, characterized in that, In the adhesive layer, the mass percentage of the second transition metal ion scavenger is 5% to 40%.

7. The lithium-ion battery according to any one of claims 1 to 6, characterized in that, The adhesive layer covers 20% to 60% of the surface area of ​​the ceramic layer.

8. The lithium-ion battery according to claim 7, characterized in that, The adhesive layer covers 30% to 40% of the surface area of ​​the ceramic layer.

9. The lithium-ion battery according to any one of claims 1 to 8, characterized in that, The ceramic layer also includes a dispersant, a ceramic filler, a thickener, a first binder, and a wetting agent.

10. The lithium-ion battery according to claim 9, characterized in that, The ceramic layer has one or more of the following characteristics: (1) The dispersant includes one or more of organic sulfonates, sulfonated fatty alcohols, polypropylene ethers and polyethylene glycol; (2) The ceramic filler includes one or more of the following: boehmite, alumina, magnesium oxide, barium sulfate, and magnesium hydroxide; (3) The thickener includes one or more of sodium carboxymethyl cellulose and sodium carboxymethyl acrylate; (4) The first adhesive includes one or more of acrylates, acrylics, and polyvinylidene fluoride; (5) The wetting agent includes one or more of fatty acid sulfates, fatty acid ester sulfates, carboxylic acid soaps and phosphate esters.

11. The lithium-ion battery according to any one of claims 1 to 10, characterized in that, The first additive further includes a first capsule shell comprising a first organic polymer, wherein the first transition metal ion scavenger is disposed within the first capsule shell to form first capsule microparticles; and / or The second additive also includes a second capsule shell, the second capsule shell comprising a second organic polymer, and the second transition metal ion scavenger disposed within the second capsule shell to form second capsule microparticles; Both the first organic polymer and the second organic polymer have swelling properties.

12. The lithium-ion battery according to claim 11, characterized in that, The first organic polymer and the second organic polymer each independently comprise one or at least two graft copolymers of polyurea, polyurea-polyurethane, polyethylene, polycarbonate, diethyl terephthalate, polytetrafluoroethylene, and polyacrylic acid resin.

13. The lithium-ion battery according to claim 11 or 12, characterized in that, It has one or more of the following characteristics: (1) The volumetric particle size Dv50 of the first capsule microparticle and / or the second capsule microparticle is 2μm to 10μm; (2) The thickness of the first capsule shell and / or the second capsule shell is 0.1 μm to 8 μm; (3) The mass ratio of the first capsule shell to the first transition metal ion scavenger is (1-15):1; (4) The mass ratio of the second capsule shell to the second transition metal ion scavenger is (1-15):

1.

14. A method for preparing a lithium-ion battery, comprising a separator preparation step, characterized in that, The preparation steps of the diaphragm include: A ceramic layer is prepared on the surface of a substrate layer, the ceramic layer comprising a first additive, the first additive comprising a first transition metal ion scavenger; An adhesive layer is prepared on the surface of the ceramic layer to prepare an intermediate component. The adhesive layer contains a second additive and a second adhesive, wherein the second additive contains a second transition metal ion scavenger. The intermediate components are then pressed together. The first transition metal ion scavenger and the second transition metal ion scavenger each independently comprise one or more of sodium xanthate, thiophosphate, thiocarbamate, trisodium trithiocyanate, and tetrabutylammonium trithiolate.

15. An electrical appliance, characterized in that, It includes at least one of the lithium-ion batteries according to any one of claims 1 to 13 and the lithium-ion batteries prepared by the preparation method according to claim 14.

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