WO2023115431A1 - 二次电池 - Google Patents

二次电池 Download PDF

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Publication number
WO2023115431A1
WO2023115431A1 PCT/CN2021/140679 CN2021140679W WO2023115431A1 WO 2023115431 A1 WO2023115431 A1 WO 2023115431A1 CN 2021140679 W CN2021140679 W CN 2021140679W WO 2023115431 A1 WO2023115431 A1 WO 2023115431A1
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Prior art keywords
negative electrode
secondary battery
metal ion
layer
electrolyte
Prior art date
Application number
PCT/CN2021/140679
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English (en)
French (fr)
Inventor
黄玉平
林明峰
马云建
甄晓枫
胡洋
赵海坤
马亚林
童星
Original Assignee
宁德时代新能源科技股份有限公司
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to EP21965849.9A priority Critical patent/EP4243144A4/en
Priority to PCT/CN2021/140679 priority patent/WO2023115431A1/zh
Priority to CN202180094889.2A priority patent/CN116888792A/zh
Priority to US18/323,407 priority patent/US20230299303A1/en
Publication of WO2023115431A1 publication Critical patent/WO2023115431A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the battery field, in particular to a secondary battery, a battery module, a battery pack and an electrical device.
  • secondary batteries have been widely used in energy storage power systems such as hydraulic, thermal, wind and solar power stations, as well as electric tools, electric bicycles, electric motorcycles, electric vehicles , military equipment, aerospace and other fields. Due to the great development of secondary batteries, higher requirements have been put forward for their cycle performance and rate performance.
  • the present application is made in view of the above problems, and its purpose is to provide a secondary battery with better cycle performance and rate performance.
  • the present application provides the following secondary battery, a battery module including the secondary battery, a battery pack including the battery module, and an electrical device.
  • the first aspect of the present application provides a secondary battery, including a negative electrode sheet and an electrolyte
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer sequentially arranged on at least one surface of the negative electrode current collector , a first metal oxide layer and a second metal ion adsorption layer
  • the first metal oxide is at least one selected from manganese dioxide, molybdenum oxide, magnesium oxide, aluminum oxide and phosphorus pentoxide, optional is manganese dioxide
  • the electrolyte contains second metal ions.
  • the present application arranges the first metal oxide layer on the surface of the negative electrode active material layer, and utilizes its strong adsorption of metal ions to make the second metal ions adhere to the surface of the negative electrode to form a natural protective layer to prevent further reduction of the electrolyte.
  • the SEI film is thinner and denser, improving cycle performance and rate performance.
  • the ionic radius of the second metal ion is less than or equal to 0.92 nm.
  • the second metal ion can be easily attached to the surface of the negative electrode and function as a protective layer.
  • the second metal ion is at least one selected from Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ , and may be Li + , Cr 3+ , Mo 6+ and Fe 2+ at least one.
  • the second metal ion is the above-mentioned metal ion, it can be easily attached to the surface of the negative electrode, forming a natural protective layer, preventing the electrolyte from penetrating, reducing and decomposing, forming a thick SEI film, and preventing the consumption of ions in the electrolyte. Performance deteriorates.
  • the second metal ion Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ with smaller ion radius, it can be more easily attached to the surface of the negative electrode and better protect The role of layers.
  • the thickness of the first metal oxide layer is 0.1 nm-10 nm, optionally 0.5 nm-5 nm, 0.7 nm-3 nm, 0.9 nm-1.5 nm.
  • the transport of lithium ions is not hindered, and the function of adsorbing lithium ions of the second metal can be exerted.
  • the second metal ion is provided by at least one salt selected from LiCl, CrCl 3 , CaCl 2 , KCl, NaCl, MoCl 6 and FeCl 2 .
  • the concentration of the second metal ion in the electrolyte is lower than 0.1mol/L, optionally lower than 0.05mol/L, lower than 0.01mol/L, 0.001mol/L-0.01mol /L.
  • a protective layer can be formed without negatively affecting the performance of the battery.
  • the thickness of the solid electrolyte interfacial film (SEI film) formed on the surface of the negative electrode material of the battery is less than 40nm, and may be 10nm-35nm, 12nm-20nm, 14nm-16nm.
  • the SEI film formed on the surface of the negative electrode can be made thinner and denser. Thereby, cycle performance and rate performance are improved.
  • the first metal oxide layer is formed by atomic layer deposition (ALD).
  • ALD atomic layer deposition
  • the second aspect of the present application also provides a battery module including the secondary battery of the first aspect of the present application.
  • a third aspect of the present application provides a battery pack, including the battery module of the second aspect of the present application.
  • the fourth aspect of the present application provides an electrical device, including at least one selected from the secondary battery of the first aspect of the present application, the battery module of the second aspect of the present application, or the battery pack of the third aspect of the present application. kind.
  • the secondary battery of the present invention it is possible to suppress the decomposition of the electrolytic solution and improve the cycle performance.
  • the kinetic performance of the battery can be improved, and the rate performance can be improved.
  • FIG. 1 is a schematic diagram of a negative electrode sheet of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an electron micrograph of a negative electrode of a secondary battery according to an embodiment of the present application, wherein (a) is a transmission electron microscope (TEM) photo of the microscopic layer structure of the negative electrode, and (b) is an electron image of the surface of the negative electrode.
  • TEM transmission electron microscope
  • FIG. 3 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack according to one embodiment of the present application shown in FIG. 6 .
  • FIG. 8 is a schematic diagram of an electrical device in which a secondary battery is used as a power source according to an embodiment of the present application.
  • ranges disclosed herein are defined in terms of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit that define the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, ie any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are contemplated. Additionally, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all expected: 1-3, 1-4, 1-5, 2- 3, 2-4 and 2-5.
  • the numerical range "a-b” represents an abbreviated representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article, and "0-5" is only an abbreviated representation of the combination of these values.
  • a certain parameter is an integer ⁇ 2
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed in sequence, and may also include steps (b) and (a) performed in sequence.
  • step (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c) , may also include steps (a), (c) and (b), may also include steps (c), (a) and (b) and so on.
  • the "comprising” and “comprising” mentioned in this application represent an open type or a closed type.
  • the “comprising” and “comprising” may mean that other components not listed may be included or included, or only listed components may be included or included.
  • the term "or” is inclusive unless otherwise stated.
  • the phrase "A or B” means “A, B, or both A and B.” More specifically, the condition "A or B” is satisfied by either of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists) ; or both A and B are true (or exist).
  • a secondary battery is provided.
  • a secondary battery typically includes a positive pole piece, a negative pole piece, an electrolyte, and a separator.
  • active ions are intercalated and extracted back and forth between the positive electrode and the negative electrode.
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the separator is arranged between the positive pole piece and the negative pole piece, which mainly plays a role in preventing the short circuit of the positive and negative poles, and at the same time allows ions to pass through.
  • the negative electrode sheet of the secondary battery of the present application includes a negative electrode current collector and a negative electrode active material layer, a first metal oxide layer, and a second metal ion adsorption layer that are sequentially arranged on at least one surface of the negative electrode current collector, that is, on the negative electrode
  • the surface of the active material layer opposite to the negative electrode current collector side is provided with a first metal oxide layer, and the first metal oxide layer is located between the negative electrode active material layer and the second metal ion adsorption layer.
  • a second metal ion adsorption layer is formed on the surface of the layer opposite to the negative electrode current collector side.
  • the electrolyte contains a second metal ion, and the first metal oxide is selected from manganese dioxide, molybdenum oxide, and magnesium oxide. , at least one of aluminum oxide and phosphorus pentoxide, optionally manganese dioxide.
  • the carbonate solution When manufacturing a secondary battery, the carbonate solution will be reduced and decomposed during formation, and lithium methoxide (CH 3 OLi) will be mainly formed on the surface of the negative electrode. Since dilithium carbonate is porous, it can be permeated by the electrolyte, thereby Intensify the reduction and decomposition of the electrolyte, form a thick SEI film, and reduce the kinetic performance of the battery.
  • the first metal oxide layer is arranged on the surface of the negative electrode active material layer, and the second metal ion is attached to the surface of the negative electrode by utilizing its strong adsorption of metal ions to form a natural protective layer to prevent further reduction and co-intercalation of the electrolyte. , making the SEI film thinner and denser, improving cycle performance and rate performance.
  • the SEI film solid electrolyte interphase
  • the SEI film refers to a layer covering the electrode material when the electrode material and the electrolyte react at the solid-liquid phase interface during the first charging and discharging process of the liquid lithium-ion battery.
  • surface passivation layer is an interfacial layer, which has the characteristics of a solid electrolyte, is an electronic insulator but is an excellent conductor of Li + , and Li + can be freely inserted and extracted through the passivation layer.
  • the SEI membrane has a porous texture, and the electrolyte is easily permeable.
  • the second metal ion is at least one selected from Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ , and may be Li + , Cr 3+ , Mo 6+ and Fe 2+ , and at least one of Li + and Cr 3+ can be selected.
  • the second metal ion being at least one of the above-mentioned metal ions, it can be easily attached to the surface of the negative electrode to form a natural protective layer, prevent electrolyte penetration, reduction and decomposition, form a thick SEI film, and prevent consumption of the electrolyte. ions, resulting in poor battery performance.
  • the second metal ions are attracted to attach to its surface.
  • the second metal ions can be directly adsorbed on the first metal oxide layer through the pores in the SEI film.
  • the surface of the SEI film is adsorbed on the surface of the SEI film where there are no pores, thereby filling the loose pores of the SEI film and covering the surface of the pole piece, thereby being able to play the role of a protective layer to prevent electrolyte penetration, specifically
  • the protective layer plays the role of preventing the electrolyte from continuing to oxidize and decompose, producing by-products, and thickening the SEI.
  • the second metal ion By making the second metal ion have a smaller ionic radius, preferably a metal ion with an ionic radius less than or equal to 0.92nm, for example, it can be Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ , can more easily fill the voids and attach to the surface of the negative electrode, and better play the role of the protective layer.
  • the second metal ion is not limited to the above-mentioned metal ions, as long as it can play the role of forming a protective layer.
  • the thickness of the first metal oxide layer is 0.1 nm-10 nm, optionally 0.5 nm-5 nm, 0.7 nm-3 nm, 0.9 nm-1.5 nm, for example, 1 nm.
  • the transport of lithium ions is not hindered, and the function of adsorbing lithium ions of the second metal can be exerted.
  • the second metal ion is provided by at least one salt selected from LiCl, CrCl 3 , CaCl 2 , KCl, NaCl, MoCl 6 , and FeCl 2 .
  • the production cost can be reduced without causing damage to the electrode.
  • the provision of the second metal ion is not limited to the above-mentioned chloride salts, and can also be salts such as carbonates and nitrates that are easily separated from metal ions. As long as they can provide ions and can not cause damage to the electrode, all salts can be used.
  • the concentration of the second metal ion in the electrolyte is lower than 0.1mol/L, optionally lower than 0.05mol/L, lower than 0.01mol/L, 0.001mol/L-0.01mol/L, for example It can be 0.01mol/L.
  • the concentration of the second metal ion in the electrolyte refers to the concentration after the second metal ion adsorption layer is formed, not the initial added concentration.
  • a protective layer can be formed without negatively affecting the performance of the battery.
  • the concentration of the second metal ion in the electrolyte can also be lower than the detection limit.
  • the thickness of the solid electrolyte interfacial film (SEI film) formed on the surface of the negative electrode is less than 40nm, and may be 10nm-35nm, 12nm-20nm, or 14nm-16nm.
  • the charge and discharge of the battery are completed through the deintercalation process of active ions in the negative electrode. Since the intercalation process of active ions must pass through the SEI film covering the negative electrode active material, the characteristics of the SEI film determine the deintercalation process. The kinetics of the intercalation of active ions and the stability of the negative electrode active material interface also determine the performance of the entire battery, such as cycle life, self-discharge, rated rate, and low-temperature performance of the battery.
  • the SEI film of the present invention can be thinner and denser, thereby improving cycle performance and rate performance.
  • the first metal oxide layer is formed by atomic layer deposition (ALD).
  • ALD atomic layer deposition
  • the atomic layer deposition (ALD) method for example, can be carried out by using the open sample loading atomic deposition (ALD) equipment of Oxford OpAL, UK.
  • the positive pole piece includes a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector.
  • the positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposing surfaces of the positive electrode current collector.
  • the positive electrode current collector can be a metal foil or a composite current collector.
  • aluminum foil can be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming metal materials (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene glycol ester
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • positive active materials known in the art for batteries can be used in the positive active material layer.
  • the positive active material may include at least one of the following materials: olivine-structured lithium-containing phosphate, lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials of batteries can also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to, lithium cobalt oxides (such as LiCoO 2 ), lithium nickel oxides (such as LiNiO 2 ), lithium manganese oxides (such as LiMnO 2 , LiMn 2 O 4 ), lithium Nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1/3 Co 1/3 Mn 1/3 O 2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (also abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also abbreviated as NCM 622 ), LiNi At least one of 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi
  • the olivine structure contains Examples of lithium phosphates may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), lithium manganese phosphate and carbon At least one of a composite material, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also may be abbreviated as LFP)
  • composite materials of lithium iron phosphate and carbon such as LiMnPO 4
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive active material layer may optionally further include a binder.
  • the binder may include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene At least one of ethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • the positive active material layer optionally further includes a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, are dispersed in a solvent (such as N -methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N -methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector, a negative electrode active material layer, a first metal oxide layer and a second metal ion adsorption layer, and has a negative electrode active material layer, a first metal oxide layer and a negative electrode active material layer on at least one surface of the negative electrode current collector.
  • the second metal ion adsorption layer is not limited to a negative electrode current collector, a negative electrode active material layer, a first metal oxide layer and a second metal ion adsorption layer.
  • the negative electrode current collector has two opposite surfaces in its own thickness direction, and the negative electrode active material layer is arranged on any one or both of the two opposite surfaces of the negative electrode current collector, and on the surface of the negative electrode active material layer and A first metal oxide layer is provided on the surface opposite to the negative electrode current collector side, and a second metal ion adsorption layer is formed on the surface of the first metal oxide layer opposite to the negative electrode active material layer, that is, the first metal oxide layer.
  • the material layer is located between the negative electrode active material layer and the second metal ion adsorption layer, and the specific positional relationship can be referred to FIG. 1 .
  • the negative electrode current collector can use a metal foil or a composite current collector.
  • copper foil can be used as the metal foil.
  • the composite current collector may include a base layer of polymer material and a metal layer formed on at least one surface of the base material of polymer material.
  • Composite current collectors can be formed by metal materials (copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on polymer material substrates (such as polypropylene (PP), polyethylene terephthalic acid It is formed on substrates such as ethylene glycol ester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • negative electrode active materials known in the art for batteries can be used in the negative electrode active material.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, lithium titanate, and the like.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of simple tin, tin oxide compounds and tin alloys.
  • the present application is not limited to these materials, and other conventional materials that can be used as the active material of the negative electrode of the battery can also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative active material layer may further optionally include a binder.
  • the binding agent can be a binding agent commonly used in the battery field without special limitation, and the binding agent can be selected from styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide ( PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS), polyvinylidene fluoride, acryl-based polymers, diene-based polymers At least one of materials and natural rubber.
  • polystyrene-acrylate emulsion binders can be used.
  • the negative active material layer may optionally further include a conductive agent.
  • the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a dispersant may also be used when preparing the negative active material layer.
  • the dispersant is used to improve dispersion uniformity and coating property, and may be a dispersant commonly used in the battery field, such as a polymer dispersant.
  • polyvinyl alcohol modified polyvinyl alcohol having functional groups other than hydroxyl group such as acetyl group, sulfo group, carboxyl group, carbonyl group, amino group, modified by various salts, others modified by anion or cation, by Acetal-modified polyvinyl alcohol-based resins, various (meth)acrylic polymers, polymers derived from ethylenically unsaturated hydrocarbons, various cellulose-based resins, etc., or copolymers of these , but are not limited to these.
  • the polymer dispersants may be used alone or in combination of two or more.
  • the negative electrode active material layer may optionally include other additives, such as thickeners (such as sodium carboxymethylcellulose (CMC-Na)) and the like.
  • thickeners such as sodium carboxymethylcellulose (CMC-Na)
  • the first metal oxide layer may be formed using at least one material selected from manganese dioxide, molybdenum oxide, magnesium oxide, aluminum oxide, and phosphorus pentoxide.
  • the second metal ion is at least one selected from Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ .
  • the second metal ion may be provided by at least one salt selected from LiCl, CrCl 3 , CaCl 2 , KCl, NaCl, MoCl 6 and FeCl 2 .
  • the second metal ion adsorption layer is formed by the second metal ions entering the pores of the SEI film and the second metal ions adsorbed on the surface of the SEI film, that is, the second metal ion adsorption layer is The second metal ion is formed by adsorption on the surface of the anode pole piece.
  • the negative electrode sheet can be prepared in the following manner: the above-mentioned components used to prepare the negative electrode sheet, such as negative electrode active material, conductive agent, binder and any other components, are dispersed in a solvent (such as deionized water) to form the negative electrode active material layer slurry; after the negative electrode slurry is coated on the negative electrode current collector and dried, the surface is coated with the first metal oxide by the ALD method; In the welded state, add the required amount of the second metal ion salt into the liquid injection port, and then perform aging and other processes to form the second metal ion adsorption layer, and then the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive pole piece and the negative pole piece.
  • the electrolyte is an electrolytic solution.
  • the electrolyte solution includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, trifluoromethane At least one of lithium sulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium difluorooxalate borate, lithium difluorodifluorooxalatephosphate and lithium tetrafluorooxalatephosphate.
  • the solvent may be selected from ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, 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 At least one of ester, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the electrolyte contains a second metal ion
  • the concentration of the second metal ion in the electrolyte is lower than 0.1mol/L, optionally lower than 0.05mol/L, lower than 0.01mol/L L, 0.001mol/L-0.01mol/L, can also be 0.
  • the second metal ion is at least one selected from Li + , Cr 3+ , Ca 2+ , K + , Na + , Mo 6+ and Fe 2+ , and may be Li + , Cr At least one of 3+ , Mo 6+ and Fe 2+ .
  • the second metal ion may be provided by at least one salt selected from LiCl, CrCl 3 , CaCl 2 , KCl, NaCl, MoCl 6 and FeCl 2 .
  • the electrolyte may optionally include additives.
  • additives can include negative film-forming additives, positive film-forming additives, and additives that can improve certain performances of the battery, such as additives that improve battery overcharge performance, additives that improve high-temperature or low-temperature performance of batteries, and the like.
  • a separator is further included in the secondary battery.
  • the present application has no particular limitation on the type of the isolation membrane, and any known porous structure isolation membrane with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the separator can be a single-layer film or a multi-layer composite film, without any particular limitation. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and there is no particular limitation.
  • the positive pole piece, the negative pole piece and the separator can be made into an electrode assembly through a winding process or a lamination process.
  • the secondary battery may include an outer package.
  • the outer package can be used to package the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the secondary battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the secondary battery may also be a soft bag, such as a bag-type soft bag.
  • the material of the soft case may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, polybutylene succinate, and the like.
  • Fig. 1 is a schematic diagram of the negative electrode sheet of the secondary battery according to one embodiment of the present application. In Fig. 1, only the sequentially stacked negative electrode active material layer 500, the first metal oxide layer 501, and the second metal ion in the negative electrode are shown. Adsorption layer 502.
  • FIG. 2 is an electron micrograph of a negative electrode of a secondary battery according to an embodiment of the present application, wherein (a) is a transmission electron microscope (TEM) photo of the microscopic layer structure of the negative electrode, and (b) is an electron image of the surface of the negative electrode.
  • the portion indicated by the arrow in (a) of FIG. 2 is the SEI film portion adsorbed with the second ionic metal, and the darker portion is the first metal oxide layer and the negative electrode active material layer (graphite).
  • (b) of FIG. 2 shows a top view of the SEI film adsorbed with the second ionic metal.
  • FIG. 3 shows a square-shaped secondary battery 5 as an example.
  • the outer package may include a housing 51 and a cover 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plates enclose to form an accommodating cavity.
  • the housing 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can cover the opening to close the accommodating cavity.
  • the positive pole piece, the negative pole piece and the separator can be formed into an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is packaged in the accommodating chamber. Electrolyte is infiltrated in the electrode assembly 52 .
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG. 5 is a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4 .
  • the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may also include a case having a housing space in which a plurality of secondary batteries 5 are accommodated.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3 , the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source of the electric device, and can also be used as an energy storage unit of the electric device.
  • the electric devices may include mobile devices (such as mobile phones, notebook computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.) , electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited thereto.
  • a secondary battery, a battery module or a battery pack can be selected according to its use requirements.
  • FIG. 8 is an example of an electrical device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • a device may be a cell phone, tablet, laptop, or the like.
  • the device is generally required to be light and thin, and a secondary battery can be used as a power source.
  • ultramicrotome Utilize ultramicrotome (ultramicrotome) to make an ultrathin section of about 50nm of the negative electrode sheet, observe the section with TEM (Transmission Electron Microscope), the obtained photo is shown in Figure 2, and use the obtained photo to measure the thickness of the SEI film.
  • the secondary battery prepared in each example and comparative example was charged and discharged for the first time at 25°C.
  • the charging capacity is the first charging capacity; stand still for 30 minutes, then discharge to 2.5V at a constant current of 4C rate, stand still for 30 minutes, record the discharge capacity at this time, which is the capacity at 4C rate.
  • the first metal oxide layer was formed with the film thickness shown in Table 1 and Table 2 by using the open sample loading atom deposition (ALD) equipment of Oxford OpAL, UK, according to the standard steps attached to the instrument.
  • ALD open sample loading atom deposition
  • ICP Inductively Coupled Plasma Spectrometer
  • ICP test method Scrape off the negative electrode powder for digestion, and then put it into the ICP (model: ICP-AES-OES) tester for testing.
  • Digestion reagents Use different digestion reagents for different materials. For lithium nickel cobalt manganese oxide, use 1+1 aqua regia, for lithium iron phosphate, use reverse aqua regia, for graphite materials and electrolytes, use concentrated nitric acid, for silicon carbon negative electrodes Materials, use concentrated nitric acid + hydrofluoric acid.
  • Digestion method plate/acid digestion/microwave digestion (high temperature and high pressure ⁇ 200°C), carbon-containing positive and negative electrode powder adopts microwave digestion method, and others adopt plate digestion method.
  • the element content in the pole piece is calculated according to the following formula, so that the existence of the second metal ion adsorption layer can be confirmed.
  • the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), conductive carbon black SP and binder polyvinylidene fluoride (PVDF) were dispersed in the solvent N-methylpyrrolidone (NMP) according to the mass ratio of 96:1.2:2.8 and mixed uniformly in the medium to obtain the positive electrode slurry; the positive electrode slurry was uniformly coated on the aluminum foil of the positive electrode current collector, and after drying, cold pressing, slitting, and cutting into pieces, the positive electrode sheet was obtained.
  • NMP N-methylpyrrolidone
  • a 7 ⁇ m polyethylene film was selected as the isolation film.
  • Preparation of the negative electrode sheet uniformly coat the slurry of the negative electrode active material layer on the copper foil of the negative electrode current collector, and after drying at 100° C. in an oven, take the anode sheet and apply 1 nm thick manganese dioxide ( MnO 2 ), after drying, cold pressing, slitting and cutting, the negative electrode sheet is obtained.
  • MnO 2 manganese dioxide
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • DMC dimethyl carbonate
  • the separator is between the positive pole piece and the negative pole piece to play an isolation role
  • the battery is prepared by winding, and the battery is placed outside after winding.
  • the tabs are flattened, the collector plate is welded, and the top cover is welded. Then, after drying, the electrolyte is injected, and after vacuum packaging, standing, and formation, after the completion of the formation, follow the electrolyte during the second rehydration.
  • the SEI film thickness, rate performance and capacity retention of the obtained secondary battery were measured, and are described in Table 1 below.
  • Example 6 the metal elements on the surface of the negative electrode of Example 6 were quantified through the above-mentioned elemental analysis-inductively coupled plasma emission spectrometry (ICP) analysis, and the results are as follows:
  • the surface of the negative electrode contains Cr element added as the second metal ion salt, and it can be seen that a second metal ion adsorption layer is formed on the surface of the negative electrode.
  • a secondary battery was prepared in the same manner as in Example 1 except that the reaction conditions were changed as shown in Table 2. Thereafter, the SEI film thickness, rate performance, and capacity retention of the obtained secondary battery were measured according to the above-mentioned measurement and test methods, and are described in Table 2 below.
  • Examples 1-19 exhibited good effects in terms of volumetric energy density and cycle life.
  • the SEI film thickness is thicker, and the capacity retention rate is also lower.
  • the present application is not limited to the above-mentioned embodiments.
  • the above-mentioned embodiments are merely examples, and within the scope of the technical solutions of the present application, embodiments that have substantially the same configuration as the technical idea and exert the same functions and effects are included in the technical scope of the present application.
  • various modifications conceivable by those skilled in the art are added to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application. .

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Abstract

本申请提供了一种二次电池，包括负极极片和电解液，负极极片包括负极集流体以及在负极集流体的至少一个表面上依次设置的负极活性物质层、第一金属氧化物层和第二金属离子吸附层，第一金属氧化物为选自二氧化锰、氧化钼、氧化镁、氧化铝和五氧化二磷中的至少一种，且电解液中含有第二金属离子。在本申请所提供的二次电池中，通过在负极极片上设置第一金属氧化物层，而在负极上形成第二金属离子吸附层作为保护层，由此抑制电解液分解，提高电芯循环性能和倍率性能。

Description

二次电池 技术领域
本发明涉及电池领域，尤其涉及二次电池、电池模块、电池包和用电装置。
背景技术
近年来，随着二次电池的应用范围越来越广泛，二次电池被广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于二次电池取得了极大的发展，因此对其循环性能和倍率性能等也提出了更高的要求。
发明内容
本申请是鉴于上述问题而进行的，其目的在于，提供一种具有较好的循环性能和倍率性能的二次电池。
为了达到上述目的，本申请提供了如下的二次电池以及包括该二次电池的电池模块、包括该电池模块的电池包、和用电装置。
本申请的第一方面提供了一种二次电池，包括负极极片和电解液，所述负极极片包括负极集流体以及在所述负极集流体的至少一个表面上依次设置的负极活性物质层、第一金属氧化物层和第二金属离子吸附层，所述第一金属氧化物为选自二氧化锰、氧化钼、氧化镁、氧化铝和五氧化二磷中的至少一种，可选为二氧化锰，且所述电解液中含有第二金属离子。
由此，本申请通过在负极活性物质层的表面设置第一金属氧化物层，利用其强吸附金属离子的作用，使第二金属离子附着在负极表面，形成天然保护层，防止电解液进一步还原以及共插入，使SEI膜薄且更致密，提高循环性能和倍率性能。
在任意实施方式中，所述第二金属离子的离子半径小于等于0.92nm。
通过使第二金属离子的离子半径的上限值为上述值，能够使第二 金属离子能够容易地附着在负极表面，发挥保护层的作用。
在任意实施方式中，所述第二金属离子为选自Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+中的至少一种，可选为Li +、Cr 3+、Mo 6+和Fe 2+中的至少一种。
通过第二金属离子为上述金属离子，能够容易地附着在负极表面，形成天然保护层，防止电解液渗透、发生还原分解、形成厚的SEI膜，而且可以防止消耗电解液中的离子，导致电池性能变差。通过使第二金属离子为离子半径较小的Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+，能够更容易附着在负极表面，更好地发挥保护层的作用。
在任意实施方式中，所述第一金属氧化物层的厚度为0.1nm-10nm，可选为0.5nm-5nm、0.7nm-3nm、0.9nm-1.5nm。
通过使第一金属氧化物层的厚度在上述范围，既不会妨碍锂离子的传输，又能够发挥吸附第二金属锂子的作用。
在任意实施方式中，由选自LiCl、CrCl 3、CaCl 2、KCl、NaCl、MoCl 6和FeCl 2中的至少一种盐提供所述第二金属离子。
通过使用上述这些盐来提供第二金属离子，能够降低生产成本，而且不会对电极造成损害。
在任意实施方式中，所述第二金属离子在所述电解液中的浓度低于0.1mol/L，可选低于0.05mol/L、低于0.01mol/L、0.001mol/L-0.01mol/L。
通过第二金属离子以上述浓度存在于电解液中，能够即形成保护层，又不会对电池性能造成负面影响。
在任意实施方式中，在电池的负极材料的表面所形成的固体电解质界面膜(SEI膜)的厚度小于40nm，可选为10nm-35nm、12nm-20nm、14nm-16nm。
通过本发明的第一金属氧化物层和第二金属离子吸附层，能够使得形成在负极表面的SEI膜能够较薄且更致密。由此，提高了循环性能和倍率性能。
在任意实施方式中，所述第一金属氧化物层是通过原子层沉积(ALD)法形成的。
由此能够形成普通成膜方法难以实现的较薄的第一金属氧化物 层，更好地发挥第一金属氧化物层的吸附第二金属锂子的作用。
本申请的第二方面还提供一种电池模块，包括本申请的第一方面的二次电池。
本申请的第三方面提供一种电池包，包括本申请的第二方面的电池模块。
本申请的第四方面提供一种用电装置，包括选自本申请的第一方面的二次电池、本申请的第二方面的电池模块或本申请的第三方面的电池包中的至少一种。
本申请能够发挥如下的技术效果：
通过本发明的二次电池，能够抑制电解液分解，提高循环性能。
另外，通过本发明的二次电池，能够提高电池动力学性能，改善倍率性能。
附图说明
图1是本申请一实施方式的二次电池的负极极片的示意图。
图2是本申请一实施方式的二次电池的负极的电子显微镜照片，其中(a)是负极的微观层结构的透射电子显微镜(TEM)照片，(b)是负极的表面的电子图像。
图3是本申请一实施方式的二次电池的示意图。
图4是图3所示的本申请一实施方式的二次电池的分解图。
图5是本申请一实施方式的电池模块的示意图。
图6是本申请一实施方式的电池包的示意图。
图7是图6所示的本申请一实施方式的电池包的分解图。
图8是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
1电池包；2上箱体；3下箱体；4电池模块；5二次电池；51壳体；52电极组件；53顶盖组件；500负极活性物质层；501第一金属氧化物层；502第二金属离子吸附层。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的二次电池、电池模块、电池包和电学装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3、4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，可选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示 开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
本申请的二次电池的负极极片包括负极集流体以及在负极集流体的至少一个表面上依次设置的负极活性物质层、第一金属氧化物层和第二金属离子吸附层，即，在负极活性物质层的与负极集流体侧相反一侧的表面设置有第一金属氧化物层，第一金属氧化物层位于负极活性物质层与第二金属离子吸附层之间，在第一金属氧化物层的与负极集流体侧相反一侧的表面形成有第二金属离子吸附层，此外，在电解液中含有第二金属离子，第一金属氧化物为选自二氧化锰、氧化钼、氧化镁、氧化铝和五氧化二磷中的至少一种，可选为二氧化锰。
在制造二次电池时，在化成时，碳酸酯类溶液会还原分解，在负极表面主要形成甲氧基锂(CH 3OLi)，而由于碳酸二锂是多孔的，可被电解液渗透，从而加剧电解液的还原分解，形成厚的SEI膜，降低电池动力学性能。而本发明通过在负极活性物质层的表面设置第一金属氧化物层，利用其强吸附金属离子作用，使第二金属离子附着在负极表面，形成天然保护层，防止电解液进一步还原以及共插入，使SEI膜薄更致密，提高循环性能和倍率性能。
其中，SEI膜(solid electrolyte interphase)、即固体电解质界面膜是指在液态锂离子电池首次充放电过程中，电极材料与电解液在固液 相界面上发生反应，形成的一层覆盖于电极材料表面的钝化层。这种钝化层是一种界面层，具有固体电解质的特征，是电子绝缘体却是Li +的优良导体，Li +可以经过该钝化层自由地嵌入和脱出。SEI膜为有孔质地，电解液容易渗透。
在一些实施方式中，第二金属离子为选自Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+中的至少一种，可选为Li +、Cr 3+、Mo 6+和Fe 2+中的至少一种，进而可选为Li +和Cr 3+中的至少一种。
通过第二金属离子为上述金属离子中的至少一种，能够容易地附着在负极表面，形成天然保护层，防止电解液渗透、发生还原分解、形成厚的SEI膜，而且可以防止消耗电解液中的离子，导致电池性能变差。
通过第一金属氧化物层的吸附作用，吸引第二金属离子附着在其表面，在存在SEI膜的情况下，第二金属离子可以通过SEI膜中的空孔直接吸附在第一金属氧化物层的表面，在不存在空孔的地方吸附在SEI膜的表面，从而填补了SEI膜的疏松的空孔，而覆盖在极片的表面，从而能够发挥防止电解液渗透的保护层的作用，具体而言，该保护层发挥防止电解液继续氧化分解、产生副产物、使SEI变厚的作用。
通过使第二金属离子为离子半径较小，优选离子半径小于等于0.92nm的金属离子，例如可以为Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+，能够更容易填补空孔并附着在负极表面，更好地发挥保护层的作用。第二金属离子不限于上述金属离子，能够发挥形成保护层的作用即可。
在一些实施方式中，第一金属氧化物层的厚度为0.1nm-10nm，可选为0.5nm-5nm、0.7nm-3nm、0.9nm-1.5nm，例如可以为1nm。
通过使第一金属氧化物层的厚度在上述范围，既不会妨碍锂离子的传输，又能够发挥吸附第二金属锂子的作用。
在一些实施方式中，由选自LiCl、CrCl 3、CaCl 2、KCl、NaCl、MoCl 6和FeCl 2中的至少一种盐提供第二金属离子。
通过使用上述这些盐来提供第二金属离子，能够降低生产成本，而且不会对电极造成损害。提供第二金属离子不限于上述氯盐，也可以是碳酸盐、硝酸盐等金属离子易分离的盐等，只要能够发挥提供离 子，并且不会电极造成损害的盐均可以使用。
在一些实施方式中，第二金属离子在电解液中的浓度低于0.1mol/L，可选低于0.05mol/L、低于0.01mol/L、0.001mol/L-0.01mol/L，例如可以为0.01mol/L。
其中，第二金属离子在电解液中的浓度是指形成第二金属离子吸附层之后的浓度，并不是初始的添加浓度。通过第二金属离子以上述浓度存在于电解液中，能够既形成保护层，又不会对电池性能造成负面影响。当然只要能够形成第二金属离子吸附层即可，第二金属离子在电解液中的浓度也可以低于检测限。
在一些实施方式中，在负极表面所形成的固体电解质界面膜(SEI膜)的厚度小于40nm，可选为10nm-35nm、12nm-20nm、14nm-16nm。
在二次电池中，电池的充放电都是通过活性离子在负极脱嵌过程而完成的，由于活性离子的嵌入过程必然经由覆盖在负极活性材料上的SEI膜，因此SEI膜的特性决定了脱嵌活性离子以及负极活性材料界面稳定的动力学，也就决定了整个电池的性能，如循环寿命、自放电、额定速率以及电池的低温性能等。通过本发明的第一金属氧化物层和第二金属离子吸附层，本发明的SEI膜能够较薄且更致密，由此，提高了循环性能和倍率性能。
在一些实施方式中，第一金属氧化物层是通过原子层沉积(ALD)法形成的。当然只要能够形成第一金属氧化物层即可，并不限于该方法。
由此能够形成普通成膜方法难以实现的较薄的第一金属氧化物层，更好地发挥第一金属氧化物层的上述作用。
其中，原子层沉积(ALD)法例如可以采用英国Oxford OpAL开放式样品载入原子沉积(ALD)设备进行。
另外，以下适当参照附图对本申请的二次电池、电池模块、电池包和用电装置进行说明。
[正极极片]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极活性物质层。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面， 正极活性物质层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，正极活性物质层中可采用本领域公知的用于电池的正极活性物质。作为示例，正极活性物质可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性物质的传统材料。这些正极活性物质可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。
在一些实施方式中，正极活性物质层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。
在一些实施方式中，正极活性物质层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性物质、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。
[负极极片]
负极极片包括负极集流体、负极活性物质层、第一金属氧化物层和第二金属离子吸附层，在负极集流体的至少一个表面上依次具有负极活性物质层、第一金属氧化物层和第二金属离子吸附层。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极活性物质层设置在负极集流体相对的两个表面中的任意一者或两者上，而在负极活性物质层的与负极集流体侧相反一侧的表面设置有第一金属氧化物层，在第一金属氧化物层的与负极活性物质层相反一侧的表面形成有第二金属离子吸附层，即第一金属氧化物层位于负极活性物质层与第二金属离子吸附层之间，具体位置关系可以参见图1。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极活性物质中可采用本领域公知的用于电池的负极活性物质。作为示例，负极活性物质可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料， 还可以使用其他可被用作电池负极活性物质的传统材料。这些负极活性物质可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极活性物质层还可选地包括粘结剂。粘结剂可以是电池领域中常用的粘结剂，没有特别限定，所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)、聚偏氟乙烯、丙烯酰基系聚合物、二烯系聚合物、天然橡胶中的至少一种。特别可以使用聚苯乙烯-丙烯酸酯乳液粘结剂。
在一些实施方式中，负极活性物质层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，在制备负极活性物质层时还可以使用分散剂。分散剂用于提高分散均匀性和涂覆性，可以是电池领域中常用的分散剂，例如可以是聚合物分散剂。聚合物分散剂可以使用聚乙烯醇、具有羟基以外的官能团例如乙酰基、磺基、羧基、羰基、氨基的改性聚乙烯醇、通过各种盐改性、其他经阴离子或阳离子改性、通过醛类进行了缩醛改性的聚乙烯醇系树脂、或者各种(甲基)丙烯酸系聚合物、源于乙烯性不饱和烃的聚合物、各种纤维素系树脂等、或者这些的共聚物，但并不限定于这些。聚合物分散剂可单独使用一种，或者将两种以上组合使用。
在一些实施方式中，负极活性物质层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
在一些实施方式中，第一金属氧化物层可以采用选自二氧化锰、氧化钼、氧化镁、氧化铝和五氧化二磷中的至少一种材料形成。
在一些实施方式中，第二金属离子为选自Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+中的至少一种。
在一些实施方式中，可以由选自LiCl、CrCl 3、CaCl 2、KCl、NaCl、MoCl 6和FeCl 2中的至少一种盐提供第二金属离子。
在一些实施方式中，第二金属离子吸附层是由进入到SEI膜的空孔中的第二金属离子以及吸附在SEI膜表面的第二金属离子形成的， 即，第二金属离子吸附层是第二金属离子吸附在阳极极片表面而形成的。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性物质、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极活性物质层浆料；将负极浆料涂覆在负极集流体上烘干后，在其表面利用ALD法涂覆第一金属氧化物，在进行化成之后，在密封钉未被焊接的状态下，在注液口加入所需量的第二金属离子盐，之后进行老化等工序，形成第二金属离子吸附层，即可得到负极极片。
[电解质]
电解质在正极极片和负极极片之间起到传导离子的作用。在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。
在一些实施方式中，所述电解液包含第二金属离子，该第二金属离子在所述电解液中的浓度低于0.1mol/L，可选低于0.05mol/L、低于0.01mol/L、0.001mol/L-0.01mol/L，也可以为0。
在一些实施方式中，第二金属离子为选自Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+中的至少一种，可选为Li +、Cr 3+、Mo 6+和Fe 2+中的至少一种。
在一些实施方式中，可以由选自LiCl、CrCl 3、CaCl 2、KCl、NaCl、MoCl 6和FeCl 2中的至少一种盐提供第二金属离子。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加 剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
图1是本申请一实施方式的二次电池的负极极片的示意图，图1中仅表示了负极中的依次层叠的负极活性物质层500、第一金属氧化物层501、和第二金属离子吸附层502。
图2是本申请一实施方式的二次电池的负极的电子显微镜照片，其中(a)是负极的微观层结构的透射电子显微镜(TEM)照片，(b)是负极的表面的电子图像。图2的(a)中由箭头所示的部分为吸附有第二离子金属的SEI膜部分，较暗的部分为第一金属氧化物层以及负极活性物质层(石墨)。图2的(b)显示的是吸附有第二离子金属的SEI膜的俯视图。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形、罐形、袋形或其他任意的形状。例如，图3是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图4，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
图5是作为一个示例的电池模块4。参照图5，在电池模块4中，多个二次电池5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
图6和图7是作为一个示例的电池包1。参照图6和图7，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图8是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
测定以及试验方法：
(1)SEI膜厚度测定
利用超薄切片机(ultramicrotome)制作负极极片的约50nm左右的超薄切片，用TEM(透射电子显微镜)观察切片，所得到的照片见图2，利用所得到的照片测量SEI膜的厚度。
(2)循环性能测试
将各实施例和比较例制备得到的二次电池在25℃下进行第一次充电和放电，流程如下：25℃下，将二次电池静置30min后，以0.33C恒流充电至4.15V，继续恒压充电至电流≤0.05C；然后以1C恒流放电至2.5V，记录首次循环的放电容量C1。随后，将电池按照0.33C1/1C1，电压范围为2.40V-4.35V进行不断的充电和放电循环，记录循环过程中的放电容量。第1000次循环后的容量保持率＝(第1000次循环的放电容量/首次循环的放电容量)×100％。
(3)倍率性能测试
将各实施例和比较例的二次电池在25℃下，静置20min后，以0.33C倍率恒流充电至4.25V，再恒压充电至电流为0.05C，静置30min，记录此时的充电容量，即为首次充电容量；静置30min，再以4C倍率 恒流放电至2.5V，静置30min，记录此时的放电容量，即为4C倍率下的容量。
(4)第一金属氧化物层的形成
采用英国Oxford OpAL开放式样品载入原子沉积(ALD)设备按照仪器所附的标准步骤，以表1和表2所示的膜厚形成第一金属氧化物层。
(5)第二金属离子吸附层的确认
将二次电池拆解后，取负极极片送测ICP(电感耦合等离子光谱发生仪)，测极片成分。
ICP测试方法：将负极极片粉料刮下来进行消解，后放入ICP(型号：ICP-AES-OES)测试仪测试。
消解试剂：针对不用材料使用不同的消解试剂，对于镍钴锰酸锂，使用1+1王水，对于磷酸铁锂，使用逆王水，对于石墨材料和电解液使用浓硝酸，对于硅碳负极材料，使用浓硝酸+氢氟酸。
消解方式：平板/赶酸消解/微波消解(高温高压～200℃)，含碳正负极粉料采用微波消解法，其他采用平板消解法。
按照以下公式计算极片中的元素含量，由此能够确认第二金属离子吸附层的存在。
元素含量(质量分数w/w％)＝元素质量/(称样量-集流体质量)*100％。
实施例1
1、二次电池的制备
1)正极极片的制备：
将正极活性材料LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)、导电炭黑SP和粘结剂聚偏氟乙烯(PVDF)按照质量比96:1.2:2.8分散在溶剂N-甲基吡咯烷酮(NMP)中混合均匀，得到正极浆料；将正极浆料均匀涂覆在正极集流体铝箔上，经烘干、冷压、分条、裁片后，得到正极极片。
2)隔离膜的制备：
选用7μm聚乙烯膜作为隔离膜。
3)负极极片的制备：
负极极片的制备：将负极活性物质层的浆料均匀涂覆在负极集流体铜箔上，用烘箱100℃经烘干后，取阳极极片用ALD法涂覆1nm厚的二氧化锰(MnO 2)，经烘干、冷压、分条、裁切后，得到负极极片。
4)电解液的制备
将碳酸亚乙酯(EC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)按照按体积比1:1:1混合得到有机溶剂，接着将充分干燥的锂盐LiPF 6溶解于混合后的有机溶剂中，配制成浓度为1mol/L的电解液。
5)二次电池的制备：
将上述正极极片、隔离膜、负极极片按顺序层叠，使隔离膜处于正极极片与负极极片之间起到隔离作用，卷绕制备电芯，卷绕完成后将电芯置于外包装壳中，进行极耳揉平，集流盘焊接，顶盖焊接，然后，干燥后，注入电解液，经过真空封装、静置、化成，在化成完成后，在二次补液时跟电解液一起添加0.014mol/L的LiCl，使其在最终制成的电池的电解液中的含量为0.01mol/L(表1和表2中记载的“浓度”为最终制成的电池中的含量)，而后进行老化等工序做成获得二次电池。
2、二次电池的性能测试
按照上述记载，测定所得到的二次电池的SEI膜厚、倍率性能和容量保持率，记载于下述表1中。
实施例2～23
按照表1所示改变反应条件，除此以外，与实施例1同样进行，制备实施例2～23的二次电池。之后按照上述测定以及试验方法来测定所得到的二次电池的SEI膜厚、倍率性能和容量保持率，记载于下述表1中。
另外，对实施例6，通过上述元素分析-电感耦合等离子体发射光谱法(ICP)分析，对实施例6的负极表面的金属元素进行定量，结果如下表：
元素 含量(％(w/w))
Li 0.668
Ni 0.0036
Co 0.0011
Mn 0.0006
Cr 0.0008
可见负极表面包含作为第二金属离子盐添加的Cr元素，可知在负极表面形成有第二金属离子吸附层。
比较例1～2
按照表2所示改变反应条件，除此以外，与实施例1同样进行，制备二次电池。之后按照上述测定以及试验方法来测定所得到的二次电池的SEI膜厚、倍率性能和容量保持率，记载于下述表2中。
表1
Figure PCTCN2021140679-appb-000001
表2
Figure PCTCN2021140679-appb-000002
根据上述结果可知，实施例1～19在体积能量密度和循环寿命上均表现出了良好的效果。而不含第一金属氧化物层的比较例1、不添加第二金属离子盐的比较例2的SEI膜厚均较厚，容量保持率也较低。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、 发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (11)

  1. 一种二次电池，包括负极极片和电解液，
    所述负极极片包括负极集流体以及在所述负极集流体的至少一个表面上依次设置的负极活性物质层、第一金属氧化物层和第二金属离子吸附层；
    所述第一金属氧化物为选自二氧化锰、氧化钼、氧化镁、氧化铝和五氧化二磷中的至少一种；
    且所述电解液中含有第二金属离子。
  2. 根据权利要求1所述的二次电池，其中，
    所述第二金属离子的离子半径小于等于0.92nm。
  3. 根据权利要求1或2所述的二次电池，其中，
    所述第二金属离子选自Li +、Cr 3+、Ca 2+、K +、Na +、Mo 6+和Fe 2+中的至少一种，可选为Li +、Cr 3+、Mo 6+和Fe 2+中的至少一种。
  4. 根据权利要求1-3中任一项所述的二次电池，其中，
    所述第一金属氧化物层的厚度为0.1nm-10nm，可选为0.5nm-5nm。
  5. 根据权利要求1-4中任一项所述的二次电池，其中，
    由选自LiCl、CrCl 3、CaCl 2、KCl、NaCl、MoCl 6和FeCl 2中的至少一种盐提供所述第二金属离子。
  6. 根据权利要求1-5中任一项所述的二次电池，其中，
    所述第二金属离子在所述电解液中的浓度低于0.1mol/L，可选为低于0.05mol/L。
  7. 根据权利要求1-6中任一项所述的二次电池，其中，
    在负极的表面上所形成的固体电解质界面膜(SEI膜)的厚度小于40nm，可选为10nm-35nm。
  8. 根据权利要求1-7中任一项所述的二次电池，其中，
    所述第一金属氧化物层是通过原子层沉积(ALD)法形成的。
  9. 一种电池模块，其中，包括权利要求1-8中任一项所述的二次电池。
  10. 一种电池包，其中，包括权利要求9所述的电池模块。
  11. 一种用电装置，其中，包括选自权利要求1-8中任一项所述的二次电池、权利要求9所述的电池模块或权利要求10所述的电池包中的至少一种。
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