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, the diaphragm comprises a base material layer and a ceramic layer arranged on at least one surface of the base material layer, the ceramic layer comprises a ceramic base material and an additive, and the additive comprises an alkaline metal oxide. The battery cell of the lithium ion battery is not easy to lose efficacy and has good cycle performance.

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, lithium tends to deposit and accumulate at the negative electrode during use, forming lithium dendrites. The presence of lithium dendrites can cause short circuits between the positive and negative electrodes, leading to cell failure and reduced cycle performance. Methods exist to apply a protective coating composed of lithium-intercalating materials to the surface of the separator near the negative electrode to absorb lithium dendrites generated during lithium deposition on the negative electrode surface. However, the effect on reducing cell failure and improving cycle performance is limited. Summary of the Invention

[0005] To achieve the above objectives, this application provides a lithium-ion battery that reduces cell failure and improves cycle performance, a method for preparing the same, and an electrical device comprising 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, and a ceramic layer disposed on at least one surface of the substrate layer, the ceramic layer including a ceramic substrate and an additive, the additive including an alkaline metal oxide.

[0007] In the separator of the aforementioned lithium-ion battery, an alkaline metal oxide is added to the ceramic layer. The alkaline metal oxide has a strong oxidizing effect on elemental lithium and can react with elemental lithium to generate lithium oxide. This reduces the accumulation of lithium on the negative electrode and thus reduces the formation of lithium dendrites. Furthermore, research has found that the alkaline metal oxide can be stably distributed in the ceramic substrate and effectively act on lithium dendrites, thereby effectively reducing the possibility of lithium dendrites piercing the separator and causing a short circuit between the positive and negative electrodes of the battery, and improving the cycle performance of the battery.

[0008] In some embodiments, the alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate. Selecting specific alkaline metal oxides can reduce side reactions between additives and electrolytes, electrode materials, etc., protect battery characteristics during lithium dendrite formation, and improve battery safety performance.

[0009] In some embodiments, the alkali metal oxide is 2% to 100% by mass, based on the total mass of the ceramic filler and the alkali metal oxide in the ceramic substrate.

[0010] In some embodiments, when the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate, the additive further includes a capsule shell comprising an organic polymer, and the alkaline metal oxide is disposed within the capsule shell to form capsule microparticles. For one or more alkaline metal oxides of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate, a suitable particle size allows for their introduction into the ceramic layer in the form of capsule microparticles, resulting in a more stable distribution within the ceramic layer.

[0011] In some embodiments, the organic polymer includes one or at least two graft copolymers of polyurea, polyurethane, polyethylene, polycarbonate, diethyl terephthalate, polytetrafluoroethylene, toluene diisocyanate, polymethylene polyphenyl isocyanate, polymethylene polyphenyl isocyanate, cyanate trimer, polyoxyethylene ether, polyvinylidene fluoride, polyfluoroethylene carbonate, polyvinyl chloride, and polyacrylic acid resin.

[0012] In some embodiments, the capsule microparticles have one or more of the following characteristics:

[0013] (1) The volumetric particle size Dv50 of the capsule microparticles is 2μm~12μm;

[0014] (2) The thickness of the capsule shell is 0.1 μm to 9 μm;

[0015] (3) The mass ratio of the capsule shell to the alkaline metal oxide is (1~4):1;

[0016] (4) In the ceramic layer, the mass percentage of the capsule microparticles is 6% to 15%.

[0017] In some embodiments, the ceramic substrate further includes a dispersant, a first binder, and a wetting agent.

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

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

[0020] (2) The first adhesive includes one or more of acrylates, acrylics, and polyvinylidene fluoride;

[0021] (3) The wetting agent includes one or more of alkyl xanthate alkali metal salts and trithiocarbonate alkali metal salts.

[0022] In some embodiments, the ceramic substrate has one or more of the following features:

[0023] (1) In the ceramic substrate, the dispersant has a mass percentage of 1.5% to 8%;

[0024] (2) In the ceramic substrate, the mass percentage of the first adhesive is 10% to 40%;

[0025] (3) In the ceramic substrate, the wetting agent has a mass percentage of 1% to 5%.

[0026] In some embodiments, the surface of the ceramic layer is provided with an adhesive layer.

[0027] 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:

[0028] A ceramic layer is prepared on at least one surface of a substrate layer, the ceramic layer comprising a ceramic substrate and additives, the additives including alkali metal oxides.

[0029] In some embodiments, the alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate.

[0030] The step of preparing a ceramic layer on at least one surface of a substrate layer includes:

[0031] The ceramic substrate is mixed with the additive to prepare a mixture;

[0032] The mixture is applied to at least one surface of the substrate layer to prepare a ceramic layer.

[0033] In some embodiments, the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate; the preparation method further includes:

[0034] At least a portion of the alkaline metal oxide is microencapsulated to prepare capsule microparticles with an inner core comprising the alkaline metal oxide and a capsule shell comprising an organic polymer;

[0035] The step of preparing a ceramic layer on at least one surface of a substrate layer includes:

[0036] The ceramic substrate is mixed with the capsule microparticles to prepare a mixture; the mixture is applied to at least one surface of the substrate layer to prepare a ceramic layer.

[0037] Alternatively, the step of preparing a ceramic layer on at least one surface of the substrate layer includes:

[0038] The ceramic substrate is applied to at least one surface of the substrate layer to prepare a ceramic base layer;

[0039] After the capsule microparticles are applied to the surface of the ceramic substrate, a pressing process is performed to embed the capsule microparticles at least partially into the ceramic substrate, thereby preparing the ceramic layer.

[0040] 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

[0041] 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:

[0042] Figure 1 This is a schematic diagram of a lithium-ion battery according to one embodiment of this application.

[0043] Figure 2 for Figure 1 An exploded view of a lithium-ion battery according to an embodiment of this application is shown.

[0044] 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.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. Lithium-ion battery; 11. Casing; 12. Electrode assembly; 13. Cover plate; 2. Electrical device. Detailed Implementation

[0047] 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.

[0048] 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.

[0049] 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 a particular range. Ranges defined in this way can include or exclude endpoints. Any endpoint can be independently included or excluded, 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.

[0050] 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.

[0051] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0052] 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.

[0053] 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.

[0054] 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."

[0055] 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.

[0056] 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.

[0057] Traditional methods involve applying a protective coating composed of lithium-intercalating materials to the surface of the separator near the negative electrode. While this theoretically reduces lithium dendrite formation to some extent, its effectiveness in reducing cell failure and improving cycle performance in practical applications is not ideal. Research suggests that this may be because these lithium-intercalating materials are unstable in their distribution on the separator surface, making it difficult for them to effectively inhibit lithium dendrite formation.

[0058] Some embodiments of this application provide a lithium-ion battery, the lithium-ion battery including a separator, the separator including a substrate layer, and a ceramic layer disposed on at least one surface of the substrate layer, the ceramic layer including a ceramic substrate and additives, the additives including alkaline metal oxides.

[0059] In the aforementioned lithium-ion battery separator, an alkaline metal oxide is added to the ceramic substrate of the ceramic layer. The alkaline metal oxide has a strong oxidizing effect on elemental lithium and can react with elemental lithium to generate lithium oxide. This reduces the accumulation of lithium on the negative electrode, thereby reducing the formation of lithium dendrites. Furthermore, research has found that the alkaline metal oxide can be stably distributed in the ceramic substrate and effectively act on lithium dendrites, thereby effectively reducing the possibility of lithium dendrites piercing the separator and causing a short circuit between the positive and negative electrodes of the battery, and improving the cycle performance of the battery.

[0060] Without limitation, the ceramic layer may be disposed on one side of the substrate layer or on both sides of the substrate layer.

[0061] In some embodiments, the alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate. Selecting specific alkaline metal oxides can reduce side reactions between additives and electrolytes, electrode materials, etc., protect battery characteristics during lithium dendrite formation, and improve battery safety performance.

[0062] In some embodiments, the mass percentage of the alkali metal oxide is 2% to 100% of the total mass of the ceramic filler and the alkali metal oxide in the ceramic substrate. It is understood that the alkali metal oxide can be introduced as an additive or used directly as a ceramic filler in the ceramic layer. When the mass percentage of the alkali metal oxide is 100%, it indicates that no ceramic filler is used in the ceramic substrate. Specifically, the mass percentage of the alkali metal oxide includes, but is not limited to: 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 9%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any range between the foregoing. Furthermore, when the alkali metal oxide includes titanium dioxide, the mass percentage of the alkali metal oxide in the ceramic filler is 2% to 5%; when the alkali metal oxide includes nickel oxide, the mass percentage is 8% to 12%; when the alkali metal oxide includes ferrous oxide and / or ferric oxide, the mass percentage is 50% to 100%; and when the alkali metal oxide includes ferric phosphate and / or trisodium ferric phosphate, the mass percentage is 20% to 40%. By rationally controlling the mass percentage of different alkali metal oxides in the ceramic layer, it is possible to improve the cycle performance of the battery while obtaining better ion transport characteristics.

[0063] Furthermore, for one or more alkaline metal oxides selected from ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate, which have a suitable particle size, they can be introduced into the ceramic layer in the form of encapsulated microparticles, thus resulting in a more stable distribution within the ceramic layer. Therefore, in some embodiments, when the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate, the additive further includes a capsule shell comprising an organic polymer, and the alkaline metal oxide is disposed within the capsule shell to form encapsulated microparticles.

[0064] In some embodiments, the organic polymer includes one or more graft copolymers of polyurea, polyurethane, polyethylene, polycarbonate, diethyl terephthalate, polytetrafluoroethylene, toluene diisocyanate, polymethylene polyphenyl isocyanate, polymethylene polyphenyl isocyanate, cyanate trimer, polyoxyethylene ether, polyvinylidene fluoride, polyfluoroethylene carbonate, polyvinyl chloride, and polyacrylic acid resin. Using specific organic polymers in combination can reduce the dissolution of alkaline metal oxides in the core, while the formed lithium dendrites can insert into the core through the outer shell and react with the alkaline metal oxides for passivation. Furthermore, this effect can be optimized by controlling the volumetric particle size Dv50 of the capsule microparticles, the thickness of the outer shell, and the ratio of the outer shell to the core, resulting in better lithium dendrite passivation, reduced cell failure, and improved cycle performance.

[0065] In some embodiments, the volumetric particle size Dv50 of the capsule microparticles is 2 μm to 12 μm. Specifically, the volumetric particle size Dv50 of the capsule microparticles includes, but is not limited to: 2 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 10 μm, 12 μm, or any range between the foregoing. Further, the volumetric particle size Dv50 of the capsule microparticles is 5 μm to 8 μm.

[0066] In some embodiments, the thickness of the capsule shell is 0.1 μm to 9 μm. Specifically, the thickness of the capsule shell includes, but is not limited to, 0.1 μm, 1 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 6 μm, 9 μm, or any combination thereof. Further, the thickness of the capsule shell is 2 μm to 4 μm.

[0067] In some embodiments, the mass ratio of the capsule shell to the alkali metal oxide is (1~4):1. Specifically, the mass ratio of the capsule shell to the alkali metal oxide includes, but is not limited to: 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or any range between the two aforementioned.

[0068] In some embodiments, the mass percentage of the encapsulated microparticles in the ceramic layer is 6% to 15%. Reasonably controlling their mass percentage in the ceramic layer can improve the cycle performance of the battery while obtaining better ion transport characteristics. Specifically, the mass percentage of the encapsulated microparticles includes, but is not limited to: 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any range between the foregoing.

[0069] In some embodiments, the ceramic layer includes a dispersant, a ceramic filler, and a first binder; optionally, it also includes a wetting agent. By rationally compounding the components of the ceramic layer, it is beneficial to obtain a thinner ceramic layer, further reducing the impact of the introduction of the first alkali metal oxide on the ion transport performance of the ceramic layer itself.

[0070] Further, the dispersant includes one or more of sulfonated fatty alcohols, polypropylene ethers, and polyethylene glycol. In some embodiments, the mass percentage of the dispersant in the ceramic substrate is 1.5% to 8%. Specifically, the mass percentage of the dispersant includes, but is not limited to: 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, or any range between the foregoing.

[0071] Further, the ceramic filler includes one or more of bauxite, alumina, magnesium oxide, barium sulfate, and magnesium hydroxide. In some embodiments, the ceramic filler comprises 40% to 94% by mass in the ceramic substrate. Specifically, the mass percentage of the ceramic filler includes, but is not limited to: 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 94%, or any range between the foregoing.

[0072] 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 substrate is 10% to 40%. Specifically, the mass percentage of the first adhesive includes, but is not limited to: 10%, 15%, 20%, 25%, 30%, 35%, 40%, or any range between the foregoing.

[0073] Further, the wetting agent comprises one or more of alkyl xanthate alkali metal salts and trithiocarbonate alkali metal salts. In some embodiments, the wetting agent comprises 1% to 5% by mass in the ceramic substrate. Specifically, the mass percentage of the wetting agent includes, but is not limited to, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range between the foregoing.

[0074] In some embodiments, the thickness of the ceramic layer is 0.25 μm to 8 μm. Specifically, the thickness of the ceramic layer includes, but is not limited to: 0.25 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.

[0075] Additionally, it is understood that the surface of the ceramic layer is provided with an adhesive layer. Without limitation, the material of the adhesive layer includes one or more of acrylates, acrylics, and polyvinylidene fluoride (PVDF).

[0076] In addition, without limitation, the substrate layer may be one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0077] Other examples of this application provide a method for preparing a lithium-ion battery, including a separator preparation step, wherein the separator preparation step includes:

[0078] A ceramic layer is prepared on at least one surface of a substrate layer, the ceramic layer comprising a ceramic substrate and an additive, the additive comprising an alkaline metal oxide.

[0079] Understandably, the substrate layer, ceramic layer, alkaline metal oxide, etc. in the above preparation method have similar schemes and advantages to the lithium-ion battery described above, and will not be repeated here.

[0080] In some embodiments, the alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate.

[0081] The step of preparing a ceramic layer on at least one surface of a substrate layer includes:

[0082] The ceramic substrate is mixed with the additive to prepare a mixture;

[0083] The mixture is applied to at least one surface of the substrate layer to prepare a ceramic layer.

[0084] In some embodiments, the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate; the preparation method further includes:

[0085] At least a portion of the alkaline metal oxide is microencapsulated to prepare capsule microparticles with an inner core comprising the alkaline metal oxide and a capsule shell comprising an organic polymer;

[0086] The steps of preparing a ceramic layer on at least one surface of a substrate layer include the following two methods:

[0087] Method 1: Mix the ceramic substrate with the capsule microparticles to prepare a mixture; apply the mixture to at least one surface of the substrate layer to prepare a ceramic layer;

[0088] Method 2: The step of preparing a ceramic layer on at least one surface of the substrate layer includes:

[0089] The ceramic substrate is applied to at least one surface of the substrate layer to prepare a ceramic base layer;

[0090] After the capsule microparticles are applied to the surface of the ceramic substrate, a pressing process is performed to embed the capsule microparticles at least partially into the ceramic substrate, thereby preparing the ceramic layer. Understandably, in Method Two, the capsule microparticles are distributed on the surface layer of the ceramic substrate.

[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 a 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 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn0.2 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 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 40wt% to 80wt%. 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 (dry weight, minus 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 3 3.3g / 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%~60wt%. The viscosity of the negative electrode slurry at room temperature can be adjusted to 2000mPa·s~10000mPa·s. When coating the negative electrode slurry, the coating unit areal density (dry weight, deducting solvent) can be 75g / 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 ( One or more of the following: 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 2The 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.)) and ceramic layers disposed on both sides of the substrate layer. The preparation method is as follows:

[0136] The dispersant sulfonated fatty alcohol, inorganic filler boehmite and ferrous oxide, thickener sodium carboxymethyl cellulose, binder PVDF and wetting agent fatty acid sulfide were mixed in a ratio of 3%:89.5% (the mass ratio of inorganic filler boehmite to ferrous oxide was 10%:90%):0.5%:6%:1% to form a ceramic substrate. Water was added and stirred thoroughly to prepare a ceramic layer slurry. The ceramic layer slurry was coated onto one side of the substrate layer and dried to obtain a ceramic layer with a thickness of 4μm.

[0137] The preparation methods for the diaphragms in Examples 2-4 are the same as in Example 1, with the main differences shown in Table 1:

[0138] Table 1

[0139]

[0140] Note: The mass percentage of alkaline metal oxides refers to the percentage of alkaline metal oxides in the total mass of inorganic filler borosilicate and alkaline metal oxides; in Examples 2 to 4, after the mass percentage of alkaline metal oxides is changed, the mass percentage of inorganic filler borosilicate is changed accordingly to meet 100%.

[0141] Preparation Example 5

[0142] 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.)) and ceramic layers disposed on both sides of the substrate layer. The preparation method is as follows:

[0143] (1) Preparation of capsule microparticles:

[0144] 2.1 Mix 12g of ferrous oxide core material with 2g of sodium carboxymethyl cellulose and 200g of water to form an aqueous phase;

[0145] 2.2 Mix and dissolve 100.0g toluene diisocyanate, 15.0g cyanate trimer, 136g polymethyl polyphenyl isocyanate, 25g Span emulsifier, 2.0g sodium polycarboxylate dispersant, and 1200g cyclohexane to form an oil phase;

[0146] 2.3 The aqueous phase from step 2.1 and the oil phase from step 2.2 were mixed and placed in a high-shear emulsifier at 3000 r / min for emulsification and dispersion to form a stable dispersion. Then, the stirring speed was adjusted to 1200 r / min, and triethylamine was added dropwise while stirring at room temperature to initiate interfacial polymerization. The dropping rate was controlled at 12.5 g / h, with a total of 50.0 g added. After the addition was complete, the reaction was continued for 4 h, and then the reaction was stopped. Capsules were formed, filtered, dried, and sieved. The capsules were washed repeatedly with cyclohexane 6 times, and dried at room temperature to remove solvent and water, yielding ferrous oxide capsule microparticles with a volumetric particle size Dv50 of 5 μm, a shell thickness of 3.2 μm, and a shell-to-core mass ratio of 3.11:1.

[0147] (2) Preparation of ceramic layer:

[0148] A ceramic substrate was prepared by mixing sulfonated fatty alcohol as a dispersant, boehmite as an inorganic filler, sodium carboxymethyl cellulose as a thickener, PVDF as a binder, and fatty acid sulfide as a wetting agent in a ratio of 3%:89.5%:0.5%:6%:1%. Simultaneously, iron oxide capsule particles were added at a mass percentage of 90% of the ceramic substrate and 10% of the iron oxide capsule particles, and water was added and stirred thoroughly to prepare a ceramic layer slurry. The ceramic layer slurry was then coated onto one side of the substrate layer and dried to obtain a ceramic layer with a thickness of 5.5 μm.

[0149] Preparation Example 6

[0150] This embodiment provides a diaphragm, which is prepared in the same way as in embodiment 5, except that ferrous oxide capsule particles are replaced with ferric phosphate capsule particles in equal mass percentage.

[0151] (1) Preparation of capsule microparticles:

[0152] The same as in Preparation Example 5, but with ferrous phosphate replaced by ferrous oxide by mass, the prepared ferric phosphate capsule microparticles had a volumetric particle size Dv50 of 4.5 μm, a shell thickness of 3.2 μm, and a shell-to-core mass ratio of 3.11:1.

[0153] (2) Preparation of ceramic layer:

[0154] Same as in Preparation Example 5, but with ferrous oxide capsule particles replaced by ferric phosphate capsule particles of equal mass percentage, and the thickness of the ceramic layer was 4.5 μm.

[0155] Preparation Example 7

[0156] This embodiment provides a diaphragm, which is prepared by the same method as in Embodiment 5, except that it is prepared by compression.

[0157] (1) Preparation of capsule microparticles:

[0158] Same as Example 5.

[0159] (2) Preparation of ceramic layer:

[0160] The dispersant sulfonated fatty alcohol, inorganic filler borosilicate, thickener sodium carboxymethyl cellulose, binder PVDF and wetting agent fatty acid sulfide were mixed in a ratio of 3%:89.5%:0.5%:6%:1% to prepare a ceramic substrate. Water was added and stirred thoroughly to prepare a ceramic base slurry. The ceramic base slurry was scraped onto one side of the substrate layer and dried to obtain a ceramic base layer. The ferrous oxide capsule particles prepared in step (1) were applied to the surface of the ceramic base layer according to a mass percentage of 90% ceramic substrate and 10% ferrous oxide capsule particles. Then, cold pressing was performed to embed the ferrous oxide capsule particles into the surface layer of the ceramic base layer to obtain a ceramic layer with a thickness of 6.5 μm.

[0161] Comparative Example 1

[0162] The diaphragm in this comparative example is prepared similarly to that in Example 1, the main difference being that ferrous oxide was not added to the ceramic layer, and the mass percentage of the inorganic filler borosilicate was changed accordingly to meet 100%.

[0163] Comparative Example 2

[0164] The diaphragm in this comparative example is similar to that in Example 1, the main difference being that ferric phosphate is directly coated onto the surface of the ceramic layer.

[0165] (1) The dispersant sulfonated fatty alcohol, inorganic filler borosilicate, thickener sodium carboxymethyl cellulose, binder PVDF and wetting agent fatty acid sulfide are mixed in a ratio of 3%:89.5%:0.5%:6%:1% as ceramic substrate, and water is added and stirred thoroughly to prepare ceramic base slurry; the ceramic base slurry is scraped onto one side surface of the substrate layer and dried to obtain ceramic base layer;

[0166] (2) Disperse ferric phosphate in deionized water and then coat it onto the surface of the ceramic substrate using a transfer coating machine. Dry the coating to form a coating with a thickness of about 5±3μm.

[0167] Application Examples

[0168] 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:

[0169] 1) Preparation of positive electrode sheet

[0170] Polyvinylidene fluoride (PVDF), lithium iron phosphate (LFP), conductive agent carbon black, and N-methylpyrrolidone (NMP) were mixed thoroughly at a mass ratio of 1.2:58.38:0.42:40 to prepare a positive electrode slurry; the positive electrode slurry was then subjected to a 200 g / m³ concentration. 2 The loading is uniformly coated on the positive current collector aluminum foil, and then dried, cold-pressed and cut to obtain the positive electrode sheet.

[0171] 2) Preparation of negative electrode sheet

[0172] 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 and thoroughly 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 slit to obtain the negative electrode sheet.

[0173] 3) Diaphragm

[0174] One of the diaphragms in the preparation examples and comparative examples.

[0175] 4) Preparation of electrolyte

[0176] At 25°C, ethylene carbonate (EC), methyl ethyl 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.

[0177] 5) Battery manufacturing

[0178] 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.

[0179] Test example:

[0180] (1) Battery life:

[0181] Characterization was performed through an overcharge test at 25°C, with the following steps:

[0182] The battery cell was fully charged at 25°C, with the full charge cutoff voltage at 4V. Then, it was charged at 1C or 1.5C current, and the temperature and voltage changes were recorded until the battery exploded or caught fire.

[0183] (2) Capacity retention test:

[0184] 2.1 Initial capacity test:

[0185] 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.

[0186] 2.2 25℃, 1C / 1C Capacity Retention Performance Test: The battery cell was placed in a 25℃ environment and left to stand for 2 hours. After the battery temperature reached 25℃, the battery was charged to 4.2V at a constant current of 1C and constant voltage, and then charged at a constant voltage to the cutoff current of 0.05C. After resting for 5 minutes, it was discharged to 2.8V at 1C. The initial capacity Q0 was recorded, and the capacity after each cycle was recorded. The capacity of the previous discharge was taken as the battery capacity Q2, and the capacity retention rate (%) was calculated (the calculation formula is as follows: cycle capacity retention rate = Q2 / Q0 × 100%). The capacity retention rate of the battery cell after 1000 cycles was recorded.

[0187] 2.3 45℃, 1C / 1C Capacity Retention Performance Test:

[0188] 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.

[0189] The test results are shown in Table 2 below.

[0190] Table 2

[0191]

[0192] As can be seen, the embodiment can effectively reduce cell failure and improve cycle performance by directly mixing alkaline metal oxides into the ceramic layer.

[0193] 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.

[0194] 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 and a ceramic layer disposed on at least one surface of the substrate layer, the ceramic layer including a ceramic substrate and additives, the additives including alkali metal oxides.

2. The lithium-ion battery according to claim 1, characterized in that, The alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate.

3. The lithium-ion battery according to claim 1 or 2, characterized in that, The mass percentage of the alkali metal oxide is 2% to 100% based on the total mass of the ceramic filler and the alkali metal oxide in the ceramic substrate.

4. The lithium-ion battery according to claim 1 or 2, characterized in that, When the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate, the additive also includes a capsule shell, the capsule shell comprising an organic polymer, and the alkaline metal oxide disposed within the capsule shell to form capsule microparticles.

5. The lithium-ion battery according to claim 4, characterized in that, The organic polymers include graft copolymers of one or at least two of the following: polyurea, polyurethane, polyethylene, polycarbonate, polyethyl terephthalate, polytetrafluoroethylene, toluene diisocyanate, polymethylene polyphenyl isocyanate, polymethylene polyphenyl isocyanate, cyanate trimer, polyoxyethylene ether, polyvinylidene fluoride, polyfluoroethylene carbonate, polyvinyl chloride, and polyacrylic acid resin.

6. The lithium-ion battery according to claim 4 or 5, characterized in that, The capsule microparticles have one or more of the following characteristics: (1) The volumetric particle size Dv50 of the capsule microparticles is 2μm~12μm; (2) The thickness of the capsule shell is 0.1 μm to 9 μm; (3) The mass ratio of the capsule shell to the alkaline metal oxide is (1~4):1; (4) In the ceramic layer, the mass percentage of the capsule microparticles is 6% to 15%.

7. The lithium-ion battery according to any one of claims 1 to 6, characterized in that, The ceramic substrate also includes a dispersant, a first binder, and a wetting agent.

8. The lithium-ion battery according to claim 7, characterized in that, The ceramic substrate has one or more of the following characteristics: (1) The dispersant includes one or more of sulfonated fatty alcohols, polypropylene ethers, and polyethylene glycol; (2) The first adhesive includes one or more of acrylates, acrylics, and polyvinylidene fluoride; (3) The wetting agent includes one or more of alkyl xanthate alkali metal salts and trithiocarbonate alkali metal salts.

9. The lithium-ion battery according to claim 7 or 8, characterized in that, The ceramic substrate has one or more of the following characteristics: (1) In the ceramic substrate, the dispersant has a mass percentage of 1.5% to 8%; (2) In the ceramic substrate, the mass percentage of the first adhesive is 10% to 40%; (3) In the ceramic substrate, the wetting agent has a mass percentage of 1% to 5%.

10. The lithium-ion battery according to any one of claims 1 to 9, characterized in that, An adhesive layer is provided on the surface of the ceramic layer.

11. 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 at least one surface of a substrate layer, the ceramic layer comprising a ceramic substrate and additives, the additives including alkali metal oxides.

12. The method for preparing a lithium-ion battery according to claim 11, characterized in that, The alkaline metal oxide includes one or more of titanium dioxide, nickel oxide, ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate. The step of preparing a ceramic layer on at least one surface of a substrate layer includes: The ceramic substrate is mixed with the additive to prepare a mixture; The mixture is applied to at least one surface of the substrate layer to prepare a ceramic layer.

13. The method for preparing a lithium-ion battery according to claim 11, characterized in that, When the alkaline metal oxide includes one or more of ferrous oxide, ferric oxide, ferric phosphate, and trisodium ferric phosphate; the preparation method further includes: At least a portion of the alkaline metal oxide is microencapsulated to prepare capsule microparticles with an inner core comprising the alkaline metal oxide and a capsule shell comprising an organic polymer; The step of preparing a ceramic layer on at least one surface of a substrate layer includes: The ceramic substrate is mixed with the capsule microparticles to prepare a mixture; the mixture is applied to at least one surface of the substrate layer to prepare a ceramic layer. Alternatively, the step of preparing a ceramic layer on at least one surface of the substrate layer includes: The ceramic substrate is applied to at least one surface of the substrate layer to prepare a ceramic base layer; After the capsule microparticles are applied to the surface of the ceramic substrate, a pressing process is performed to embed the capsule microparticles at least partially into the ceramic substrate, thereby preparing the ceramic layer.

14. An electrical appliance, characterized in that, It includes at least one of the lithium-ion batteries according to any one of claims 1 to 10 and lithium-ion batteries prepared by the preparation method according to any one of claims 11 to 13.

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