A battery and an electric device

Abstract

The application relates to the technical field of batteries, in particular to a battery and a power utilization device; the battery comprises an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode sheet, a separator and a negative electrode sheet which are sequentially stacked; the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer arranged on at least one side surface of the positive electrode current collector in the thickness direction; the positive electrode active material layer comprises a positive electrode active material; the electrolyte comprises 1,3-propane sulfone lactone; the Co content on the surface of the positive electrode active material is a%; the charge transfer impedance of the positive electrode active material layer is b mOmega; the content of 1,3-propane sulfone lactone in the electrolyte is c wt%; the battery satisfies 30 <= a * b / c <= 120000. The battery controls the Co content on the surface of the positive electrode active material, the charge transfer impedance and the content of the additive in the electrolyte in a comprehensive manner, builds a synergistic relationship, improves the interface charge exchange efficiency of the positive electrode material, and thus the storage performance and the cycle life of the battery are improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a battery and an electrical device. Background Technology

[0002] Currently, lithium-ion batteries are widely used in portable electronics, transportation, and large-scale energy storage due to their advantages such as high energy density and long cycle life, especially in the field of electric vehicles. The cathode material has a crucial impact on the performance of lithium-ion batteries. In recent years, with the continuous improvement and optimization of the structure and performance of ternary cathode materials, they have gradually become the most widely used cathode material in lithium-ion batteries.

[0003] Although ternary cathode materials have advantages such as high energy density, high discharge capacity, and high discharge voltage, they still face the technical challenge of low interfacial charge exchange efficiency. In particular, when the surface of ternary cathode material particles comes into contact with the electrolyte, the interfacial impedance is high, which limits the migration rate of lithium ions and electrons, adversely affecting the battery's storage performance and cycle performance. Summary of the Invention

[0004] In view of this, the present invention aims to at least partially solve one of the technical problems in the related art. To this end, the present invention provides a battery and an electrical device that, by comprehensively controlling the Co content on the surface of the positive electrode active material, the charge transfer impedance, and the additive content in the electrolyte, establishes a synergistic relationship to improve the charge exchange efficiency at the interface of the positive electrode material, thereby achieving the effect of improving battery storage performance and cycle life.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows: According to one aspect of the present invention, a battery is provided, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode, a separator, and a negative electrode stacked sequentially; the positive electrode comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector along its thickness direction; the positive active material layer comprises a positive active material; the electrolyte comprises 1,3-propanesulfonate lactone. The surface Co content of the positive electrode active material is a%; the charge transfer impedance of the positive electrode active material layer is b mΩ; the content of 1,3-propanesulfonate lactone in the electrolyte is c wt% The battery satisfies: 30≤a×b / c≤120000.

[0006] In some of these embodiments, the battery satisfies: 625 ≤ a × b / c ≤ 7500.

[0007] In some of these embodiments, a = 1 to 20; preferably, a = 5 to 10.

[0008] In some embodiments, b = 30~600; preferably, b = 100~300.

[0009] In some of these embodiments, c = 0.1 to 1; preferably, c = 0.4 to 0.8.

[0010] In some of these embodiments, the positive electrode active material includes at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, and nickel-cobalt-manganese-aluminum quaternary materials.

[0011] In some of these embodiments, the positive electrode active material is a single crystal particle.

[0012] In some of these embodiments, the D50 of the single crystal particles is 1 μm to 10 μm, preferably 2 μm to 4 μm.

[0013] In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent.

[0014] In some embodiments, the positive electrode binder includes at least one of styrene-butadiene rubber, waterborne acrylic resin, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-vinyl acetate copolymer, polyacrylic acid, carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl butyral.

[0015] In some embodiments, the positive electrode conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P, graphene, and carbon nanofibers.

[0016] In some embodiments, the thickness of the positive electrode active material layer is 50 μm to 200 μm.

[0017] In some embodiments, the compaction density of the positive electrode active material layer is 2 g / cm³. 3 ~5g / cm 3 .

[0018] In some embodiments, the negative electrode sheet includes a negative current collector and a layer of negative active material disposed on at least one side surface of the negative current collector along the thickness direction.

[0019] In some embodiments, the negative electrode active material layer includes a negative electrode active material, a negative electrode binder, a negative electrode conductive agent, and a thickener; the negative electrode active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, and tin-based materials.

[0020] In some embodiments, the negative electrode binder includes at least one of polyacrylonitrile, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan.

[0021] In some embodiments, the negative electrode conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P, graphene, and carbon nanofibers.

[0022] In some of these embodiments, the thickener includes sodium carboxymethyl cellulose.

[0023] In some embodiments, the electrolyte further includes electrolyte salts, solvents, and additives.

[0024] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0025] In some embodiments, the solvent includes at least one selected from ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, 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.

[0026] In some of these embodiments, the additive includes vinylene carbonate.

[0027] In some embodiments, the content of vinylene carbonate in the electrolyte is 0.1 wt% to 1 wt% based on the total mass of the electrolyte.

[0028] According to another aspect of the present invention, an electrical device is provided, comprising the battery described in the above technical solution.

[0029] Implementing the technical solution of the present invention has at least the following beneficial effects: This invention establishes a synergistic relationship by comprehensively controlling the Co content on the surface of the positive electrode active material, the charge transfer impedance, and the additive content in the electrolyte: increasing the Co content on the surface of the positive electrode active material can improve the interfacial charge conversion efficiency, thereby improving the rate performance of the battery, but it is necessary to avoid the risk of Co dissolution caused by excessive Co content; by further controlling the charge transfer impedance, the interfacial charge exchange activity can be improved to reduce the Co content; at the same time, by increasing the content of specific additives in the electrolyte, the storage performance of the battery can be further improved, ultimately achieving the beneficial effects of improving battery storage performance and cycle life; on this basis, a comprehensive improvement in the overall electrical performance of the battery is achieved.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The accompanying drawings are incorporated in and form part of this specification, and together with the description, serve to explain the principles of the invention, which will be described in more detail later.

[0032] Figure 1 This is an EDS electron microscope image of the CP cross-section of the positive electrode active material provided in Example 1 of the present invention.

[0033] These accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by reference to specific embodiments. Detailed Implementation

[0034] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0035] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] In the description of this application, "same chemical composition" should be interpreted broadly, that is, the main components of the two have the same chemical composition, or the two have substantially the same chemical composition, but may have errors or impurities within the acceptable range that can be understood by those skilled in the art.

[0037] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0038] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0039] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0040] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0041] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may 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.

[0042] Currently, lithium-ion batteries are widely used in portable electronic products, transportation, and large-scale energy storage due to their advantages such as high energy density and long cycle life, especially in the field of electric vehicles. The cathode material has a crucial impact on the performance of lithium-ion batteries. In recent years, with the continuous improvement and optimization of the structure and performance of ternary cathode materials, they have gradually become the most widely used cathode material in lithium-ion batteries. During the research and development process, the inventors of this invention discovered that although ternary cathode materials have advantages such as high energy density, high discharge capacity, and high discharge voltage, they still face the technical challenge of low interfacial charge exchange efficiency. In particular, when the surface of the ternary cathode material particles comes into contact with the electrolyte, the interfacial impedance is high, which limits the migration rate of lithium ions and electrons, adversely affecting the battery's storage and cycle performance.

[0043] Based on this, the inventors of this invention have constructed a synergistic relationship by comprehensively controlling the Co content on the surface of the positive electrode active material, the charge transfer impedance, and the additive content in the electrolyte, thereby improving the charge exchange efficiency at the interface of the positive electrode material and thus enhancing the battery's storage performance and cycle life. Specifically, this invention adopts the following technical solution: According to one aspect of the present invention, a battery is provided, comprising an electrode assembly and an electrolyte; the electrode assembly comprises a positive electrode, a separator, and a negative electrode stacked sequentially; the positive electrode comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector along its thickness direction; the positive active material layer comprises a positive active material; the electrolyte comprises 1,3-propanesulfonate lactone. The surface Co content of the positive electrode active material is a%; the charge transfer impedance of the positive electrode active material layer is b mΩ; the content of 1,3-propanesulfonate lactone in the electrolyte is c wt% The battery satisfies: 30≤a×b / c≤120000.

[0044] This invention establishes a synergistic relationship by comprehensively regulating the Co content on the surface of the positive electrode active material, the charge transfer impedance, and the additive content in the electrolyte: increasing the Co content on the surface of the positive electrode active material can improve the interfacial charge conversion efficiency, thereby improving the rate performance of the battery, but it is necessary to avoid the risk of Co dissolution caused by excessive Co content; by further regulating the charge transfer impedance of the positive electrode active material layer, the interfacial charge exchange activity is improved, thereby reducing the Co content; at the same time, by increasing the content of specific additives in the electrolyte, the storage performance of the battery can be further improved, but the content of these additives needs to be controlled to avoid adverse effects on the performance of the electrolyte itself; based on this, this invention limits a×b / c within the above-mentioned suitable range, which can ultimately achieve the beneficial effects of improving battery storage performance and cycle life; on this basis, a comprehensive improvement in the overall electrical performance of the battery is achieved.

[0045] Specifically, the battery satisfies: 30 ≤ a × b / c ≤ 120000; specifically, it can be 30, 100, 500, 1000, 5000, 10000, 50000, 100000, 120000, or any value between the above two; preferably, the battery satisfies: 625 ≤ a × b / c ≤ 7500. In this invention, in the above formula: the Co content on the surface of the positive electrode active material is a%%; the charge transfer impedance of the positive electrode active material layer is b mΩ; the content of 1,3-propanesulfonate lactone in the electrolyte is cwt%; it should be noted that in the calculation of a × b / c, a, b, and c do not contain units.

[0046] This invention, by limiting the calculated value of a×b / c to the aforementioned range, can balance the cycle performance and storage performance of the battery. The specific analysis is as follows: By increasing the Co content on the surface of the positive electrode active material, the interfacial charge conversion efficiency of the positive electrode material is improved, addressing the shortcomings of traditional ternary positive electrode materials in this regard. Furthermore, adding a small amount of Co to the surface has advantages in cost and interface improvement compared to increasing the overall Co content of the positive electrode active material. Traditional techniques that increase the overall Co content of the positive electrode active material do not significantly improve the interfacial charge conversion efficiency; however, excessively high Co content on the surface of the positive electrode active material poses a risk of Co leaching. This can lead to increased side reactions and affect battery storage performance. By regulating the charge transfer impedance of the positive electrode active material layer and improving the interfacial charge exchange activity, the adverse effects of excessive Co content can be reduced. Simultaneously, increasing the content of 1,3-propanesulfonate lactone in the electrolyte can further improve battery storage performance, but the content of this additive must be controlled to avoid adverse effects on the electrolyte's performance. Based on this, the present invention limits a×b / c within the aforementioned suitable range, ultimately achieving the beneficial effects of improving battery storage and cycle performance. Furthermore, this results in a comprehensive improvement in the overall electrical performance of the battery. Therefore, the present invention, through comprehensive regulation of a, b, and c, can achieve the beneficial effects of improving battery cycle performance and kinetic performance.

[0047] In this invention, the method for testing the Co content on the surface of the positive electrode active material can be a CP electron microscope, which is well known to those skilled in the art, and can be used for EDS point scanning from the surface to the inside. According to common knowledge in the art, after EDS point scanning from the outer surface to the inside, the element type and content of each point can be obtained. The outermost edge point of the cross section is the test point for the Co content on the surface of the positive electrode active material of this invention. Point scanning at this point can obtain the mass percentage content of all elements. Further analysis of the spectrum at this point reveals the Co content, which is the Co content on the surface of the positive electrode active material, in % and a value of a.

[0048] In a specific embodiment of the present invention, a = 1~20, which can be 1, 5, 10, 15, 20, or any value between the two mentioned above; preferably, a = 5~10.

[0049] In this invention, the charge transfer impedance of the positive electrode active material layer can be tested by EIS decomposition test, which is well known to those skilled in the art; the charge transfer impedance of the positive electrode active material layer is obtained, with the unit being mΩ and the value being b.

[0050] In a specific embodiment of the present invention, b = 30~600, which can be 30, 100, 200, 300, 400, 500, 600, or any value between the above two; preferably, b = 100~300.

[0051] In this invention, the content of 1,3-propanesulfonate lactone in the electrolyte is expressed in wt% and in c.

[0052] In a specific embodiment of the present invention, c = 0.1~1 can specifically be: 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any value between the above two; preferably, c = 0.4~0.8.

[0053] In a specific embodiment of the present invention, the battery includes an electrode assembly and an electrolyte; wherein the electrode assembly includes a positive electrode sheet, a separator, and a negative electrode sheet stacked sequentially. Specifically, the electrode assembly is manufactured by a winding process or a stacking process from the positive electrode sheet, the separator, and the negative electrode sheet; the present invention does not impose any particular limitation on this.

[0054] In a specific embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector along the thickness direction. In the present invention, the positive current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with silver or carbon surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, or titanium, etc.; the foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc.; the composite current collector can include a polymer material base layer and a metal layer, and the composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0055] In a specific embodiment of the present invention, the positive electrode active material layer comprises a positive electrode active material; the positive electrode active material preferably comprises at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, and nickel-cobalt-manganese-aluminum quaternary materials, more preferably nickel-cobalt-manganese ternary materials, which have advantages such as high specific capacity, high voltage platform, and good cycle stability, and are widely used in the fields of power batteries and consumer electronics batteries. The present invention does not impose any special restrictions on the source of the positive electrode active material; commercially available products or self-made products well known to those skilled in the art can be used.

[0056] In a specific embodiment of the present invention, the positive electrode active material is preferably a single crystal particle; the D50 of the single crystal particle is preferably 1μm~10μm, specifically it can be: 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, or any value between the above two, more preferably 2μm~4μm.

[0057] The present invention uses the above-mentioned specific D50 positive electrode active material single crystal particles, which can ensure that the battery has excellent cycle performance.

[0058] In a specific embodiment of the present invention, in addition to the above-mentioned positive electrode active material, the positive electrode active material layer preferably also includes a positive electrode binder and a positive electrode conductive agent.

[0059] In a specific embodiment of the present invention, the positive electrode binder includes at least one selected from styrene-butadiene rubber (SBR), waterborne acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB); the positive electrode conductive agent includes at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. These materials are all commercially available.

[0060] In a specific embodiment of the present invention, the thickness of the positive electrode active material layer is preferably 50μm to 200μm, specifically 50μm, 100μm, 150μm, 200μm, or any value between the two, and more preferably 90μm to 110μm.

[0061] In a specific embodiment of the present invention, the compaction density of the positive electrode active material layer is preferably 2 g / cm³. 3 ~5g / cm 3 Specifically, it could be: 2g / cm 3 3g / cm 3 4g / cm 3 5g / cm 3 Or a value between any two of the above, more preferably 3 g / cm³ 3 ~4g / cm 3 .

[0062] In a specific embodiment of the present invention, the positive electrode sheet is prepared by a method well known to those skilled in the art, which involves mixing the raw material components in a certain proportion and then pressing the mixture onto a positive current collector to obtain the positive electrode sheet.

[0063] In a specific embodiment of the present invention, the separator is disposed between the positive electrode and the negative electrode, mainly to prevent short circuit between the positive and negative electrodes, while allowing ions to pass through; any separator well known to those skilled in the art for use in batteries can be used, such as polyethylene (PE) film, polypropylene (PP) film, etc., or a ceramic layer and / or adhesive layer can be disposed on the base film, and the present invention has no special limitations in this regard.

[0064] In a specific embodiment of the present invention, the negative electrode preferably includes a negative electrode current collector and a negative electrode active material layer disposed on at least one side surface of the negative electrode current collector along the thickness direction. The negative electrode current collector can be a metal foil or a composite current collector. For example, stainless steel foil or copper foil can 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 formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0065] In a specific embodiment of the present invention, the negative electrode active material layer preferably includes a negative electrode active material, a negative electrode binder, a negative electrode conductive agent, and a thickener.

[0066] In a specific embodiment of the present invention, the negative electrode active material preferably includes at least one selected from artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, and tin-based materials; wherein, the silicon-based material may be selected from at least one selected from elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys; and the tin-based material may be selected from at least one selected from elemental tin, tin oxide compounds, and tin alloys. These materials are all commercially available.

[0067] In a specific embodiment of the present invention, the negative electrode binder preferably includes at least one selected from polyacrylonitrile (PAN), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS); the negative electrode conductive agent preferably includes at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers; and the thickener preferably includes sodium carboxymethyl cellulose (CMC-Na). These materials are all commercially available.

[0068] In a specific embodiment of the present invention, the method for preparing the negative electrode sheet adopts a method well known to those skilled in the art: first, the raw materials are mixed in a solvent in a certain proportion to form a slurry, and then the negative electrode slurry is coated on the negative electrode current collector. After drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0069] In a specific embodiment of the present invention, the electrolyte includes 1,3-propanesulfonate lactone (SP), which can effectively improve the storage performance of the battery; in addition, the electrolyte preferably also includes electrolyte salt, solvent and additives.

[0070] In a specific embodiment of the present invention, the electrolyte salt preferably includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate, more preferably lithium hexafluorophosphate; the solvent preferably includes ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, and carbon. The additive comprises at least one of dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, 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, more preferably a mixed solvent of ethylene carbonate, methyl ethyl carbonate, and diethyl carbonate; the additive includes vinylene carbonate (VC). These materials are all commercially available.

[0071] In a specific embodiment of the present invention, the content of vinylene carbonate in the electrolyte is preferably 0.1wt% to 1wt%, more preferably 0.5wt% to 0.9wt%, based on the total mass of the electrolyte.

[0072] In summary, the present invention can obtain a positive electrode, a separator, a negative electrode, and an electrolyte. The present invention does not impose any special restrictions on the battery preparation method; the battery can be obtained by using assembly methods well known to those skilled in the art.

[0073] In a specific embodiment of the present invention, the outer packaging of the assembly can be a soft package, such as a pouch; the material of the soft package can be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate, which mainly serve a sealing function.

[0074] According to another aspect of the present invention, an electrical device is provided, comprising the battery described in the above-described technical solution. Thus, the electrical device possesses all the features and advantages of the battery described in the above-described technical solution, which will not be repeated here. Specifically, the lithium-ion battery can serve 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 (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.

[0075] The present application will be described in detail below with reference to the accompanying drawings and embodiments. However, the implementation and protection of the present invention are not limited thereto. The following embodiments are only some embodiments of the present application and are not intended to limit the present application. Where specific techniques or conditions are not specified in the embodiments, 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 conventional products that can be obtained commercially.

[0076] Example 1 Preparation of positive electrode active materials: Nickel salt (nickel sulfate hexahydrate NiSO4·6H2O), cobalt salt (cobalt sulfate heptahydrate CoSO4·7H2O), and manganese salt (manganese sulfate monohydrate MnSO4·H2O) were dissolved in deionized water and mixed in a molar ratio of Ni:Co:Mn of 80:10:10 to prepare a metal-soluble salt solution. The solution was then co-precipitated by stirring at 500 rpm (NaOH solution and / or ammonia were added to the co-precipitation reactor, and the pH was monitored to maintain a level of 12.1). After washing and drying at 110°C, a hydroxide precursor of M (M being one of the three metal elements mentioned above) was obtained. This precursor was then reacted with Co(NO3)2 at a concentration of 0.4 mol / L and EDT. A concentration of 0.2 mol / L was mixed and stirred at 60℃ for 2 h. After filtration and drying, LiOH was added according to the lithium metal element molar ratio Li:Mtotal = 1.05 and mixed and ground in a mixer. The mixture was then placed in a muffle furnace under an oxygen atmosphere and heated to 500℃ at a heating rate of 2℃ / min, held for 4 h, and then heated to 900℃ at a heating rate of 2℃ / min and held for 12 h. After that, it was cooled to 600℃ and held for 4 h, and then cooled to room temperature with the furnace. After that, it was crushed and sieved to obtain a sample with high particle size concentration. Finally, a positive electrode single crystal material with a D50 of 3.5 μm was obtained, with a Co coating on the surface and a coating layer thickness of 1 nm to 5 nm. The EDS electron microscope image of its CP section is shown below. Figure 1 As shown.

[0077] The obtained positive electrode active material was used to prepare a battery according to the following process steps, and then tested: (1) Preparation of the positive electrode sheet: The prepared positive electrode active material, conductive agent SP, SWCNT, and binder PVDF were mixed at a mass ratio of 97.8:0.6:0.6:1. NMP solvent was added, and the mixture was stirred under vacuum until homogeneous to obtain a positive electrode slurry. The obtained positive electrode slurry was uniformly coated onto both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, positive electrode sheets were obtained. The thickness of the positive electrode active material layer was 99–103 μm, and the compaction density was 3.4–3.56 g / cm³. 3 .

[0078] (2) Preparation of negative electrode sheet: The negative electrode active material graphite, conductive agent acetylene black, thickener CMC-Na, and binder SBR were mixed in a mass ratio of 96.4:1:1.2:1.4. Deionized water was added as a solvent, and the mixture was stirred under vacuum until the system was homogeneous to obtain a negative electrode slurry. The obtained negative electrode slurry was uniformly coated on both surfaces of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet was obtained.

[0079] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 3:6:1 to form an organic solvent. Then, based on the total mass of the electrolyte, 14 wt% of lithium salt LiPF6, 0.8 wt% of additive vinylene carbonate (VC), and 0.6 wt% of additive 1,3-propanesulfonate lactone (PS) were added and dissolved in the mixed organic solvent to prepare the electrolyte.

[0080] (4) Battery fabrication: The positive electrode, separator (polyethylene film), and negative electrode are stacked in sequence, with the separator acting as a separator between the positive and negative electrodes. The cells are then wound to obtain a bare cell. The bare cell is placed in an outer packaging shell, dried, and then injected with electrolyte. After conventional processes such as vacuum sealing, settling, formation, and volume determination, a lithium-ion battery is obtained.

[0081] Performance and parameter testing: (1) Powder particle size test: Particle size distribution was tested using a laser particle size analyzer (MasterSizer 2000): 0.2g of positive electrode active material powder sample was added to a 100mL clean beaker, 50mL of ethanol was added, and then 2 to 3 drops of 1% surfactant were added to completely disperse the powder in water. The D50 of the positive electrode active material was tested after ultrasonic cleaning for 60 seconds in a 120W ultrasonic cleaner.

[0082] (2) Co content test: CP (argon ion polishing) sample preparation method: Take a sample of appropriate size (5mm×10mm), wrap the sample with copper tape, flatten it and cut a flat cross section with a blade; fix the sample on the baffle with copper tape, with the cross section cut by the blade facing upward, and control the protrusion of the sample on the baffle to be 50μm~100μm, place it on the sample holder, and align the scale side of the baffle with the scale on the sample holder; insert the sample holder into the sample base, ensuring that the hole on the sample holder is aligned with the protrusion on the worktable, and then put the cover back in place; evacuate, set the parameters to accelerate voltage 7.5KV, time 2h~4h, angle 30° for polishing sample preparation.

[0083] Testing Procedure: The target sample prepared by CP was photographed using SEM. The magnification was adjusted to allow viewing of a complete cross-section of the particle. EDS was then used to perform point scanning from the outer surface to the interior. (See [reference needed]). Figure 1 As shown, the type and content of elements at each point can be automatically analyzed (see Table 1 below, in wt%), where the outermost edge of the cross-section is the test point for Co (corresponding to the spectrum). Figure 1 (Spectra 9, Spectra 10, Spectra 18) By scanning the test points, the wt% content of all elements can be obtained. Further, the Co content can be found in the analytical spectrum of the test points, and the average value (the result is taken to one decimal place) is the Co content a on the surface of the positive electrode active material.

[0084] Table 1 (3) EIS decomposition test: Use Autolab PGSTAT302N to test EIS: constant temperature chamber controlled at 25±1℃, the battery needs to be left to stand at constant temperature for ≥12 hours, frequency range: usually 100kHz to 10mHz (or lower, such as 1mHz), AC amplitude: 5~10mV, draw Nyquist diagram based on test results, establish equivalent circuit diagram decomposition Rct.

[0085] (4) Capacity test: The assembled battery was charged and discharged on the Blue Electric Tester. The test temperature was 25℃. After standing for 30 minutes, it was discharged to 2.75V at a rate of 0.3 (C). The lithium-ion battery was charged to 4.4V at a constant current of 0.3C, and then charged to 0.05C at a constant voltage of 4.4V. The capacity obtained was the initial charging capacity. After standing for 5 minutes, it was discharged to 2.75V at 1C. The capacity obtained was the initial discharge capacity.

[0086] (5) Rate test: The assembled battery was charged and discharged on the Blue Electric Tester. The test temperature was 25℃. The lithium-ion battery was charged to 4.4V at a constant current and constant voltage of 0.3C rate (C), and then charged to 0.05C at a constant voltage of 4.4V until the current was less than or equal to 0.05C. After standing for 5 minutes, it was discharged to 2.75V at 5C. The charge and discharge capacity was recorded during the test, and the 5C discharge capacity retention rate was calculated.

[0087] (6) Cyclic test: The assembled battery was charged and discharged on the Blue Electric Tester. The test temperature was 45℃. The lithium-ion battery was charged at a constant current of 0.3 times (C) to 4.4V, and then charged at a constant voltage of 4.4V to a current less than or equal to 0.05C. After resting for 5 minutes, it was discharged at 1C to 2.75V. Then, 1000 cycles of 0.3C charging / 0.5C discharging were performed. The discharge capacity of the 1000th cycle was recorded. Cyclic capacity retention rate = (discharge capacity of the 1000th cycle / discharge capacity of the first cycle) × 100%.

[0088] Example 2 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.9 mol / L and EDTA at a concentration of 0.5 mol / L at 50℃ and stirred for 3 h. During the preparation of the electrolyte, 0.1 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0089] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0090] Example 3 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.5 mol / L and EDTA at a concentration of 0.3 mol / L at 55℃ and stirred for 2 h. During the preparation of the electrolyte, 0.4 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0091] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0092] Example 4 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.3 mol / L and EDTA at a concentration of 0.1 mol / L at 70℃ and stirred for 2 h. During the preparation of the electrolyte, 0.8 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0093] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0094] Example 5 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.1 mol / L and EDTA at a concentration of 0.1 mol / L, and stirred at 70℃ for 1 h. During the preparation of the electrolyte, 1.0 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0095] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0096] Example 6 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.6 mol / L and EDTA at a concentration of 0.2 mol / L at 70℃ and stirred for 2 h. During the preparation of the electrolyte, 0.2 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0097] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0098] Example 7 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 0.6 mol / L and EDTA at a concentration of 0.3 mol / L at 55℃ and stirred for 3 h. During the preparation of the electrolyte, 0.3 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0099] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0100] Example 8 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 1.0 mol / L and EDTA at a concentration of 0.1 mol / L at 70℃ and stirred for 1 h. During the preparation of the electrolyte, 1.5 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0101] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0102] Comparative Example 1 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with 0.1 mol / L Co(NO3)2 and 0.1 mol / L EDTA at 75℃ and stirred for 1 h. During the preparation of the electrolyte, 1.5 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0103] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0104] Comparative Example 2 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the obtained M hydroxide precursor was mixed with Co(NO3)2 at a concentration of 1.0 mol / L and EDTA at a concentration of 0.6 mol / L at 50℃ and stirred for 3 h. During the preparation of the electrolyte, 0.1 wt% of the additive 1,3-propanesulfonate lactone (PS) is added.

[0105] Based on this, the parameters of lithium-ion batteries are obtained differently, as shown in Table 2.

[0106] Example 9 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the mixture is placed in a muffle furnace and heated to 480°C in an oxygen atmosphere at a heating rate of 1.5°C / min, held for 4 hours, and then heated to 850°C at a heating rate of 1.5°C / min and held for 12 hours. After that, it is cooled to 600°C and held for 4 hours, and then cooled to room temperature with the furnace.

[0107] Based on this, in the preparation of the positive electrode active material, the corresponding positive electrode single crystal material with D50=4μm was finally obtained. Other parameters are shown in Table 2.

[0108] Example 10 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the positive electrode active material, the mixture is placed in a muffle furnace and heated to 520°C in an oxygen atmosphere at a heating rate of 2.5°C / min, held for 4 hours, and then heated to 950°C at a heating rate of 2.5°C / min and held for 12 hours. After that, it is cooled to 600°C and held for 4 hours, and then cooled to room temperature with the furnace.

[0109] Based on this, in the preparation of the positive electrode active material, the corresponding positive electrode single crystal material with D50=2μm was finally obtained. Other parameters are shown in Table 2.

[0110] Table 2 Example 11 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the electrolyte, 1 wt% of the additive vinylene carbonate (VC) is added.

[0111] Example 12 The lithium-ion battery was obtained using the preparation method provided in Example 1, with the following difference: In the preparation of the electrolyte, 0.1 wt% of the additive vinylene carbonate (VC) is added.

[0112] The test results are shown in Table 3.

[0113] Table 3 As shown in Table 3, the battery provided in this embodiment of the invention establishes a synergistic relationship by comprehensively regulating the Co content on the surface of the positive electrode active material, the charge transfer impedance, and the additive content in the electrolyte: increasing the Co content on the surface of the positive electrode active material can improve the interfacial charge conversion efficiency of the positive electrode active material, thereby improving the rate performance of the battery, but it is necessary to avoid the risk of Co dissolution caused by excessive Co content; by further regulating the charge transfer impedance, the interfacial charge exchange activity is improved to reduce the Co content; at the same time, by increasing the content of specific additives in the electrolyte, the storage performance of the battery can be further improved, but it is necessary to control the content of the additives to not be too high, so as to avoid adverse effects on the performance of the electrolyte itself; on this basis, the present invention limits a×b / c within the above-mentioned suitable range, which can ultimately achieve the beneficial effects of improving the battery storage performance and cycle life; on this basis, the overall electrical performance of the battery is comprehensively improved.

[0114] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0115] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0116] In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment is included in at least one embodiment of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Additionally, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery, characterized in that, The device includes an electrode assembly and an electrolyte; the electrode assembly includes a positive electrode, a separator, and a negative electrode stacked sequentially; the positive electrode includes a positive current collector and a positive active material layer disposed on at least one side surface of the positive current collector along the thickness direction; the positive active material layer includes a positive active material; the electrolyte includes 1,3-propanesulfonate lactone. The surface Co content of the positive electrode active material is a%; the charge transfer impedance of the positive electrode active material layer is b mΩ; the content of 1,3-propanesulfonate lactone in the electrolyte is c wt% The battery satisfies: 30≤a×b / c≤120000.

2. The battery according to claim 1, characterized in that, The battery satisfies: 625≤a×b / c≤7500.

3. The battery according to claim 1, characterized in that, The a = 1~20; and / or, The b = 30~600; and / or, The value of c is 0.1 to 1.

4. The battery according to claim 3, characterized in that, The a = 5~10; and / or, The b = 100~300; and / or, The value of c is 0.4 to 0.

8.

5. The battery according to claim 1, characterized in that, The positive electrode active material includes at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, and nickel-cobalt-manganese-aluminum quaternary materials.

6. The battery according to claim 1, characterized in that, The positive electrode active material is a single crystal particle; the D50 of the single crystal particle is 1μm~10μm.

7. The battery according to claim 1, characterized in that, The positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent; the positive electrode binder includes at least one of styrene-butadiene rubber, waterborne acrylic resin, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-vinyl acetate copolymer, polyacrylic acid, carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl butyral; the positive electrode conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P, graphene, and carbon nanofibers.

8. The battery according to claim 1, characterized in that, The thickness of the positive electrode active material layer is 50 μm to 200 μm; and / or, The compaction density of the positive electrode active material layer is 2 g / cm³. 3 ~5g / cm 3 .

9. The battery according to claim 1, characterized in that, The negative electrode sheet includes a negative current collector and a negative active material layer disposed on at least one side surface of the negative current collector along its thickness direction; the negative active material layer includes a negative active material, a negative binder, a negative conductive agent, and a thickener; the negative active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, and tin-based materials; the negative binder includes at least one of polyacrylonitrile, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan; the negative conductive agent includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P, graphene, and carbon nanofibers; the thickener includes sodium carboxymethyl cellulose.

10. The battery according to claim 1, characterized in that, The electrolyte further includes an electrolyte salt, a solvent, and additives; the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate; the solvent includes at least one of vinyl carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, 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; the additive includes vinyl carbonate.

11. The battery according to claim 10, characterized in that, Based on the total mass of the electrolyte, the content of vinylene carbonate in the electrolyte is 0.1wt%~1wt%.

12. An electrical appliance, characterized in that, Includes the battery as described in any one of claims 1 to 11.

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