WO2025137948A1 - 含锂材料、制备方法、正极极片、二次电池及用电装置 - Google Patents

含锂材料、制备方法、正极极片、二次电池及用电装置 Download PDF

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Publication number
WO2025137948A1
WO2025137948A1 PCT/CN2023/142459 CN2023142459W WO2025137948A1 WO 2025137948 A1 WO2025137948 A1 WO 2025137948A1 CN 2023142459 W CN2023142459 W CN 2023142459W WO 2025137948 A1 WO2025137948 A1 WO 2025137948A1
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Prior art keywords
lithium
containing material
positive electrode
preparation
battery
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PCT/CN2023/142459
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English (en)
French (fr)
Inventor
景二东
谢浩添
张楠楠
董康宇
陈晓
孙信
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to PCT/CN2023/142459 priority Critical patent/WO2025137948A1/zh
Priority to CN202380097512.1A priority patent/CN121127986A/zh
Publication of WO2025137948A1 publication Critical patent/WO2025137948A1/zh
Anticipated expiration legal-status Critical
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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
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • 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
    • 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
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • 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

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a lithium-containing material, a preparation method, a positive electrode sheet, a secondary battery and an electrical device.
  • secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a lithium-containing material having a low decomposition voltage, which can effectively improve the cycle stability of the secondary battery when added to the secondary battery as a lithium supplement.
  • the first aspect of the present application provides a lithium-containing material, wherein the lithium-containing material comprises a component as shown in Formula I,
  • M includes one or more of nickel, cobalt, manganese, iron, sodium, potassium, vanadium, titanium, copper, tungsten, zirconium and molybdenum;
  • Y includes one or more of oxalate, squarate and carbonate; 1 ⁇ a ⁇ 2, 0.01 ⁇ b ⁇ 0.2.
  • the M element in the lithium-containing material has the ability to regulate electrons, thereby improving the electrochemical reaction activity of the lithium-containing material, reducing its decomposition potential, improving the lithium replenishment effect of the lithium-containing material within the voltage window of the secondary battery, and improving the cycle stability of the battery.
  • the lithium-containing material achieves a catalytic
  • the uniform mixing of the agent and the lithium supplement agent at the atomic level can more effectively reduce the decomposition potential of lithium-containing materials and enhance the improvement effect of battery cycle stability.
  • Lithium-containing materials with a and b within a suitable range can exert a good catalytic effect, effectively reduce the decomposition voltage of the lithium-containing materials, and improve the cycle stability of the battery.
  • the lithium-containing material is a eutectic material of a lithium salt and a catalyst salt
  • the lithium salt and the catalyst salt have the same anion Y
  • the cation of the catalyst salt includes an M element.
  • Lithium salts and catalyst salts with the same anion Y may have similar lattice structures, making it easy for the M element in the catalyst salt to enter the lithium salt, forming a eutectic material of the lithium salt and the catalyst salt, thereby improving the catalytic effect of the M element on the decomposition of the lithium salt during the electrochemical process, making the lithium-containing material have a low decomposition potential, and improving its lithium replenishment effect and the cycle stability of the battery.
  • the lithium-containing material is spherical or spherical in shape.
  • Spherical or quasi-spherical lithium supplement materials can easily form a close stack with the active material in the electrode, which is beneficial to maintaining and improving the compaction density of the electrode.
  • the lithium-containing material continues to decompose and lithium ions are continuously released, the volume of the lithium-containing material continues to shrink, and gaps appear between the lithium-containing material and other parts of the positive electrode sheet.
  • the lithium-containing material is isolated in the conductive network of the positive electrode sheet, which greatly reduces its electrochemical decomposition efficiency and even forms an "island" in the positive electrode sheet, making it difficult to improve the cycle stability of the battery.
  • the hollow granular lithium-containing material provided in the embodiment of the present application can effectively improve the utilization rate of the lithium-containing material, so that the addition of a small amount of lithium-containing material in the positive electrode sheet can effectively improve the cycle stability of the secondary battery.
  • the volume distribution particle size Dv50 of the lithium-containing material particles satisfies: 0.1 ⁇ m ⁇ Dv50 ⁇ 10 ⁇ m, optionally, 1 ⁇ m ⁇ Dv50 ⁇ 10 ⁇ m.
  • Lithium-containing materials with a volume distribution particle size Dv50 within a suitable range have good kinetic properties and low decomposition potential, which helps to improve the cycle stability of the battery.
  • the ratio s of the shell wall thickness of the hollow particle to the diameter of the hollow particle satisfies 10:100 ⁇ s ⁇ 30:100.
  • the ratio s of the shell wall thickness of the hollow particles to the diameter of the hollow particles is within an appropriate range, which is beneficial to improving the decomposition rate of the lithium-containing material, reducing production costs, and improving production efficiency.
  • the lithium-containing material further includes a conductive material.
  • the conductive material includes at least one of graphene, carbon nanotubes, carbon nanofibers, acetylene black, super carbon black, and Ketjen black.
  • Including conductive materials in lithium-containing materials can improve the conductivity of the lithium-containing materials, further reduce the decomposition potential of the lithium-containing materials, improve the decomposition efficiency of lithium salts, and be beneficial to further improve the cycle stability of secondary batteries.
  • the mass proportion of the conductive material is 1%-10%, and optionally 1%-5%.
  • the mass proportion of conductive materials is within an appropriate range, and the lithium-containing materials have both good kinetic properties and lithium capacity, which can not only effectively reduce the decomposition potential of lithium-containing materials, but also effectively improve the lithium replenishment efficiency, further improving the cycle stability of secondary batteries.
  • the decomposition voltage of the lithium-containing material is 3.8V-4.5V, and optionally 4.0V-4.48V.
  • the lithium-containing material has a lower decomposition voltage, which is conducive to fully exerting the lithium supplement effect and further improving the cycle stability of the secondary battery.
  • the second aspect of the present application provides an application of a lithium-containing material as a lithium supplement in a secondary battery.
  • the third aspect of the present application provides a method for preparing a lithium-containing material, the preparation method comprising: preparing the lithium-containing material by crystallization, the lithium-containing material comprising a component of a general formula such as Formula I,
  • the lithium-containing material of the present application is prepared by crystallization, and the transition metal element or the alkali metal element other than the lithium element replaces the lithium element during the co-crystallization process, so that the catalytic element and the lithium element are evenly mixed at the atomic level to form a solid solution phase effect, thereby effectively enhancing the catalytic ability of the catalytic element; compared with the physical mixing of the catalyst and the lithium supplement, the decomposition potential of the lithium-containing material can be more effectively reduced, which is beneficial to further improve the cycle stability of the battery.
  • the preparation method specifically comprises: crystallizing the mixed solution to prepare a lithium-containing The material, the mixed solution includes a lithium salt and a catalyst salt, the lithium salt and the catalyst salt have the same anion, the anion includes one or more of oxalate, squarate, and carbonate, and the cation of the catalyst salt includes the M element.
  • Catalyst salts with the same anions have similar crystal structures as lithium salts.
  • the cations of the catalyst salts easily replace lithium ions to form a solid solution phase effect, thereby improving the catalytic efficiency of the M element, effectively reducing the decomposition voltage of the lithium salt, and reducing the introduction of other impurity ions during the preparation of lithium-containing materials, thereby comprehensively improving the cycle stability of the battery.
  • the mixed liquid further includes a conductive material.
  • the conductive material includes a conductive carbon material.
  • the crystallization is performed using spray drying.
  • the crystallization by spray drying can adjust the particle size of lithium-containing material particles by adjusting the spray pressure, air inlet temperature, air outlet temperature and other process conditions of spray drying, thereby improving the controllability of product preparation.
  • the spray drying method is low-cost and suitable for industrial production. During the spray drying process, the solution is first atomized into small droplets and then dried instantly under high temperature conditions, making it easier for the catalyst salt to form a solid solution phase in the lithium salt lattice before self-crystallization to produce a eutectic.
  • the air inlet temperature of the spray drying is 170° C.-230° C.
  • the air outlet temperature is 100° C.-140° C.
  • the preparation method specifically includes: mixing a solution containing a lithium salt with a solution containing a catalyst salt to obtain a first mixed solution; mixing the first mixed solution with a solution containing a conductive material to obtain a second mixed solution; and spray drying the second mixed solution to prepare a lithium-containing material.
  • the fourth aspect of the present application provides a positive electrode plate, which includes a current collector and a positive electrode film layer arranged on at least one side of the current collector, the positive electrode film layer includes a lithium supplement, and the lithium supplement includes the lithium-containing material of the first aspect or the lithium-containing material prepared by the preparation method of the third aspect.
  • the mass proportion of the lithium supplement agent is 0.5% to 20%, and can be optionally 1% to 10%.
  • the mass proportion of the lithium supplement in the positive electrode film layer is within an appropriate range, the cycle stability and capacity of the battery can be effectively improved simultaneously.
  • the positive electrode film layer includes a positive electrode active material.
  • the positive electrode active material includes a lithium-containing phosphate, a lithium transition metal oxide and their respective modified materials; further optionally, the positive electrode active material includes a lithium-containing phosphate and its modified materials.
  • the upper limit voltage of the voltage window of lithium-containing phosphate is relatively low, so conventional lithium supplements with higher decomposition voltage cannot be applied to pole pieces containing lithium-containing phosphate.
  • the lithium-containing material of the present application has a low decomposition voltage and can be decomposed within the voltage window of lithium-containing phosphate to supplement active lithium, thereby improving the cycle stability of the battery and matching the requirements of the battery with lithium-containing phosphate as the positive electrode active material for cycle stability and life.
  • the average particle size of the lithium-containing material is greater than the average particle size of the positive electrode active material.
  • the fifth aspect of the present application provides a secondary battery, comprising the positive electrode sheet of the fourth aspect.
  • a sixth aspect of the present application provides an electrical device comprising the secondary battery of the fifth aspect.
  • FIG1 is a scanning electron microscope image of a lithium-containing material according to an embodiment of the present application.
  • FIG2 is a cross-sectional view of a positive electrode sheet according to an embodiment of the present application.
  • FIG3 is a constant current charging curve of the battery of Example 1 of the present application at a rate of 0.1C;
  • FIG4 is a constant current charging curve of the battery of Comparative Example 1 of the present application at a rate of 0.1C;
  • FIG5 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG6 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG5 ;
  • FIG7 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG8 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG9 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG8 ;
  • FIG. 10 is a schematic diagram of an electric device using a secondary battery according to an embodiment of the present application as a power source.
  • FIG. 11 is an X-ray diffraction diagram of a lithium-containing material according to an embodiment of the present application.
  • “Scope” disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope limited in this way can be including end values or not including end values, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), wherein The method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may include step (c), which indicates that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application are open-ended or closed-ended.
  • the “include” and “comprising” may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • a is 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or any value therebetween.
  • a eutectic is a trace component incorporated into a solid phase crystal that is considered soluble.
  • the eutectic is a substitutional solid solution.
  • a substitutional solid solution is a substance formed by the ions, molecules or small lattice units of a trace substance replacing the corresponding ions, molecules or small lattice units in the lattice of a constant substance.
  • Lithium salts and catalyst salts with the same anion Y may have similar lattice structures, making it easy for the M element in the catalyst salt to enter the lithium salt, forming a eutectic material of the lithium salt and the catalyst salt, thereby improving the catalytic effect of the M element on the decomposition of the lithium salt during the electrochemical process, making the lithium-containing material have a low decomposition potential, and improving its lithium replenishment effect and the cycle stability of the battery.
  • the lithium-containing material is spherical or spherical in shape.
  • the surface morphology of the lithium-containing material is shown in Figure 1, showing a spherical or quasi-spherical shape.
  • the spherical or quasi-spherical lithium-supplementing material is easy to form a close stack with the active material in the pole piece, which is beneficial to maintain and improve the compaction density of the pole piece.
  • the lithium-containing material is a hollow particle having a cavity inside the shell.
  • the lithium-containing material continues to decompose and lithium ions are continuously released, the volume of the lithium-containing material continues to shrink, and gaps appear between the lithium-containing material and other parts of the positive electrode sheet.
  • the lithium-containing material is isolated in the conductive network of the positive electrode sheet, which greatly reduces its electrochemical decomposition efficiency and even forms an "island" in the positive electrode sheet, making it difficult to improve the cycle stability of the battery.
  • the hollow granular lithium-containing material provided in the embodiment of the present application can effectively improve the utilization rate of the lithium-containing material, so that The addition of a small amount of lithium-containing material to the positive electrode can effectively improve the cycle stability of the secondary battery.
  • the volume distribution particle size Dv50 of the lithium-containing material satisfies: 0.1 ⁇ m ⁇ Dv50 ⁇ 10 ⁇ m.
  • the volume distribution particle size Dv50 of the lithium-containing material satisfies: 1 ⁇ m ⁇ Dv50 ⁇ 10 ⁇ m.
  • Dv50 refers to the particle size corresponding to the cumulative volume distribution number of particles reaching 50% in a particle size distribution curve.
  • Dv50 can be tested by methods known in the art.
  • the measurement can be performed using a laser particle size analyzer such as the Mastersizer 2000E produced by Malvern Instruments Ltd., UK.
  • Lithium-containing materials with a volume distribution particle size Dv50 within a suitable range have good kinetic properties and low decomposition potential, which helps to improve the cycle stability of the battery.
  • the ratio s of the shell wall thickness of the hollow particle to the diameter of the hollow particle satisfies 10:100 ⁇ s ⁇ 30:100.
  • the ratio of the shell wall thickness of the hollow particles to the diameter of the hollow particles can be measured by scanning electron microscopy.
  • the pole piece is cut perpendicularly to the large surface of the positive pole piece by an argon ion beam to expose the cross section of the lithium-containing material, and the ratio of the shell wall thickness of the hollow particles to the diameter of the hollow particles is measured by scanning electron microscopy.
  • the longest distance of the hollow particles is measured in five directions, and the average value is taken as the diameter of the hollow particles; the shell wall thickness of the hollow particles is measured at 5 random locations in the cross section of the hollow particles, and the average value of the 5 measurement results is taken as the shell wall thickness of the hollow particles.
  • the ratio of the average value of the shell wall thickness of the same hollow particle to the average value of the diameter of the same hollow particle is used as the ratio s of the shell wall thickness of the hollow particles to the diameter of the hollow particles.
  • the ratio s of the shell wall thickness of the hollow particle to the diameter of the hollow particle is 10:100, 12:100, 14:100, 16:100, 18:100, 20:100, 22:100, 24:100, 26:100, 28:100, 30:100 or any value therebetween.
  • the ratio s of the shell wall thickness of the hollow particle to the diameter of the hollow particle is within a suitable range. It is beneficial to improve the decomposition rate of lithium-containing materials, reduce production costs and improve production efficiency.
  • the lithium-containing material further includes a conductive material.
  • the conductive material includes carbon nanotubes.
  • the mass proportion of the conductive material is 1%-5%.
  • the lithium-containing material has both good kinetic properties and lithium capacity, which can not only effectively reduce the decomposition potential of the lithium-containing material, but also effectively improve the lithium replenishment efficiency, further improving the cycle stability of the secondary battery.
  • the decomposition voltage of the lithium-containing material is 3.8V-4.5V, optionally 4.0V-4.48V.
  • the decomposition voltage of the lithium-containing material may be selected as 3.8V, 3.85V, 3.9V, 3.95V, 4.0V, 4.05V, 4.1V, 4.15V, 4.2V, 4.25V, 4.3V, 4.35V, 4.4V, 4.45V, 4.48V, 4.5V or any range therebetween.
  • the decomposition voltage of the lithium supplement can be tested by any known method in the art.
  • the lithium supplement is added as an additive to the positive electrode plate, assembled into a lithium battery, and the capacity (Q) of the lithium battery in the range of 3.65V-4.5V is tested when the lithium battery is charged for the first time.
  • the voltage data V is used as the horizontal axis and the corresponding dQ/dV is used as the vertical axis to plot the dQ/dV curve that changes with V.
  • the voltage value corresponding to the peak position of the curve in the range of 3.65V-4.5V is the decomposition voltage of the lithium-containing material.
  • the decomposition voltage of the lithium-containing material is measured in the range of 3.65V-4.5V.
  • the battery is charged at a low rate, such as 0.05C.
  • a second aspect of the present application provides an application of a lithium-containing material as a lithium supplement in a secondary battery.
  • the third aspect of the present application provides a method for preparing a lithium-containing material, the preparation method comprising: preparing the lithium-containing material by crystallization, the lithium-containing material comprising a component of a general formula such as Formula I,
  • M includes one or more of nickel, cobalt, manganese, iron, sodium, potassium, vanadium, titanium, copper, tungsten, zirconium and molybdenum;
  • Y includes one or more of oxalate, squarate and carbonate; 1 ⁇ a ⁇ 2, 0.01 ⁇ b ⁇ 0.2.
  • spray drying refers to a granulation method in which a slurry or solution is sprayed into a granulation tower, and the slurry or solution is dried under the action of spray hot air to obtain spherical granules.
  • the material particles prepared by this method have high precision and uniform size.
  • the crystallization by spray drying method can adjust the particle size of lithium-containing materials by adjusting the spray pressure, air inlet temperature, air outlet temperature and other process conditions of spray drying, thereby improving the controllability of product preparation.
  • the spray drying method is low in cost and suitable for industrial production.
  • the solution is first atomized into small droplets and then dried instantly under high temperature conditions, making it easier for the catalyst salt to form a solid solution phase in the lithium salt lattice before self-crystallization.
  • the inlet air temperature of the spray drying is 170°C-230°C, and/or the outlet air temperature is 100°C-140°C.
  • the inlet air temperature for spray drying can be selected to be 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C or any range therebetween.
  • the preparation method specifically includes: mixing a solution containing a lithium salt with a solution containing a catalyst salt to obtain a first mixed solution; mixing the first mixed solution with a solution containing a conductive material to obtain a second mixed solution; and spray drying the second mixed solution to prepare a lithium-containing material.
  • a complexing agent is included in the solution comprising the catalyst salt.
  • the complexing agent includes one or more of ammonia, ethanolamine, sodium nitrilotriacetate, diethylenetriamine pentacarboxylate, tartaric acid, heptonic acid salt, sodium gluconate, sodium alginate, and polyacrylic acid.
  • a secondary battery is provided.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode film layer includes a lithium supplement
  • the lithium supplement includes the lithium-containing material of the first aspect or the lithium-containing material prepared by the preparation method of the third aspect.
  • the mass proportion of the lithium supplement agent is 0.5% to 20%.
  • the mass proportion of the lithium supplement agent is 1% to 10%.
  • the mass proportion of the lithium supplement in the positive electrode film layer is within an appropriate range, the cycle stability and capacity of the battery can be effectively improved simultaneously.
  • the cathode film layer includes a cathode active material.
  • the positive electrode active material may be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a 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 for batteries may also be used.
  • These positive electrode active materials may be used alone, or two or more may be used in combination.
  • lithium transition metal oxides include, but are not limited to, lithium cobalt oxide (such as LiCoO 2 ), lithium nickel oxide (such as LiNiO 2 ), lithium manganese oxide (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 referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ), and LiNi 0.8 Co 0.1 Mn 0.1 O 2 (also referred to as NCM 811 ).
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode active material includes a lithium-containing phosphate.
  • the upper limit voltage of the voltage window of lithium-containing phosphate is relatively low, so conventional lithium supplements with higher decomposition voltage cannot be applied to pole pieces containing lithium-containing phosphate.
  • the lithium-containing material of the present application has a low decomposition voltage and can decompose and supplement active lithium within the voltage window of lithium-containing phosphate, thereby improving the cycle stability of the battery and matching the requirements of the battery with lithium-containing phosphate as the positive electrode active material for cycle stability and life.
  • the average particle size of the lithium-containing material is greater than the average particle size of the positive electrode active material.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • the metal foil aluminum foil may be used.
  • 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 may 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 (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • a metal material aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.
  • a polymer material substrate such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • VDF polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, 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 components for preparing the positive electrode sheet, such as the positive electrode active material, the lithium supplement, the conductive agent, the 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 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 and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may 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.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • FIG5 is a secondary battery 5 of a square structure as an example.
  • FIG8 and FIG9 are battery packs 1 as an example.
  • 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, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical 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 for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • Fig. 10 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • the lithium-containing material, lithium iron phosphate material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) obtained above were mixed in a N-methylpyrrolidone (NMP) solvent system at a weight ratio of 5:92:1:2 to obtain a positive electrode slurry; the positive electrode slurry was then evenly coated on the positive electrode current collector, and then dried, cold pressed, and cut to obtain a positive electrode sheet.
  • NMP N-methylpyrrolidone
  • the Dv50 of lithium iron phosphate is 1.5 ⁇ m.
  • Active material artificial graphite, conductive agent carbon black, binder styrene butadiene rubber (SBR), thickener sodium carboxymethyl cellulose (CMC) are dissolved in solvent deionized water according to a weight ratio of 96.2:0.8:0.8:1.2, and mixed evenly to prepare negative electrode slurry; the negative electrode slurry is once or more It is evenly coated on the negative electrode current collector copper foil, and then dried, cold pressed and cut to obtain the negative electrode sheet.
  • Polypropylene film is used as the isolation film.
  • the positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrodes to play an isolating role, and then the bare cell is wound, the pole ear is welded to the bare cell, and the bare cell is placed in an aluminum shell, and baked at 80°C to remove water, and then the electrolyte is injected and sealed to obtain an uncharged battery. The uncharged battery is then placed, hot and cold pressed in turn.
  • the formation treatment is carried out, first charging at a constant current of 0.1C for 10 minutes, then charging at a constant current of 1/3C to 3.65V, and then charging at a constant voltage of 3.65V to 0.05C, leaving it for 5 minutes, and finally charging at a constant current of 0.05C to the upper limit voltage of 4.5V. Then after shaping, capacity testing and other processes, a lithium-ion battery product is obtained.
  • Example 2-9 The preparation methods of Examples 2-9 are substantially the same as those of Example 1, except that the type of catalyst salt or lithium salt, or the molar ratio of catalyst salt to lithium salt is adjusted.
  • Example 10 The preparation method of Example 10 is substantially the same as that of Example 1, except that CNT is not added during the preparation of the lithium supplement.
  • Comparative Example 1 The preparation method of Comparative Example 1 is substantially the same as that of Example 1, except that nickel oxalate and CNT are not added during the preparation of the lithium supplement.
  • the preparation method of the battery in Comparative Example 2 is substantially the same as that in Example 1, except that the preparation method of the lithium supplement agent in Comparative Example 2 is:
  • Nickel oxalate and lithium oxalate materials were weighed in a molar ratio of 3:100, and the two were evenly mixed by ball milling to obtain a composite material.
  • An X-ray diffractometer is used to detect lithium-containing materials and raw materials to obtain X-ray diffraction patterns.
  • the decomposition voltage of the lithium supplement is measured during the battery cell formation process.
  • the prepared battery is first charged at a constant current of 0.1C for 10 minutes, then charged at a constant current of 1/3C to 3.65V, then charged at a constant voltage of 3.65V to 0.05C, left for 5 minutes, and finally charged at a constant current of 0.05C to an upper limit voltage of 4.5V.
  • the voltage (V) and capacity (Q) data obtained in the device are recorded, and the dQ/dV data is obtained through calculation and processing. With the voltage data V as the horizontal axis and the corresponding dQ/dV as the vertical axis, the dQ/dV curve that changes with V can be obtained.
  • the voltage value corresponding to the peak position of the curve in the range of 3.65V-4.5V is the decomposition voltage of the lithium supplement.
  • the prepared battery was charged to 3.65V at a constant current of 1/3C, then charged to 0.05C at a constant voltage of 3.65V, left for 5 minutes, and then discharged to 2.5V at 1/3C.
  • the obtained capacity was recorded as the initial capacity C0.
  • the cycle capacity retention rate i.e., the value of P100, was measured.
  • the batteries of the embodiments and comparative examples were prepared according to the above method, and various performance parameters were measured. The results are shown in Table 1.
  • Figure 11 is an X-ray diffraction spectrum of the lithium-containing material of the lithium supplement in Example 1 of the present application.
  • the X-ray diffraction peak of the lithium-containing material is basically consistent with that of lithium oxalate, and no obvious characteristic peak of nickel oxalate is shown, indicating that the lithium-containing material has a lattice structure of lithium oxalate and realizes the solid solution of nickel in lithium oxalate.
  • the positive electrode plates of Examples 1-10 all include lithium-containing materials of Li a M b Y, where M includes one or more of transition metal elements and alkali metal elements other than lithium; Y includes one or more of oxalate, squarate, and carbonate; 1 ⁇ a ⁇ 2, 0.01 ⁇ b ⁇ 0.2. From the comparison between the examples and the comparative examples, it can be seen that the lithium-containing materials of the present application have a lower decomposition voltage and can effectively improve the cycle life of the battery.
  • the lithium-containing material when the anion of the lithium-containing material is oxalate, squarate, or carbonate, the lithium-containing material has a low decomposition voltage and the battery has good cycle stability.
  • the anion of the lithium-containing material is squarate, the decomposition voltage of the lithium-containing material can be further reduced, and the cycle stability of the battery can be improved.

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Abstract

提供了一种含锂材料、制备方法、正极极片、二次电池及用电装置。该含锂材料包括式I所示的组分，其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a＜2、0.01≤b≤0.2。该含锂材料具有低的分解电压，作为补锂剂有利于提升电池的循环稳定性。

Description

含锂材料、制备方法、正极极片、二次电池及用电装置 技术领域
本申请涉及二次电池技术领域，尤其涉及一种含锂材料、制备方法、正极极片、二次电池及用电装置。
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。
随着用电装置续航要求的不断提高，业界对二次电池的循环寿命也提出了更高的要求。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种含锂材料，该含锂材料具有低的分解电压，作为补锂剂添加于二次电池中时，能够有效提升二次电池的循环稳定性。
本申请的第一方面提供了一种含锂材料，含锂材料包括通式如式I所示的组分，
LiaMbY  式I
其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a<2、0.01≤b≤0.2。
本申请实施例中通过含锂材料中的M元素对电子的调控能力，提升含锂材料的电化学反应活性，降低其分解电位，提高含锂材料在二次电池电压窗口内的补锂效果，改善电池的循环稳定性。相比于在正极极片中同时加入催化剂与补锂剂，该含锂材料实现了催化 剂与补锂剂在原子层级的均匀混合，能够更加有效地降低含锂材料的分解电位，提升电池循环稳定性的改善效果。
在任意实施方式中，1.6≤a<2，0.01≤b≤0.1。
a与b在合适范围内的含锂材料能够发挥良好的催化效果，有效降低含锂材料的分解电压，提升电池的循环稳定性。
在任意实施方式中，所述含锂材料为锂盐与催化剂盐的共晶材料，所述锂盐与所述催化剂盐具有相同的阴离子Y，所述催化剂盐的阳离子包括M元素。
具有相同阴离子Y的锂盐与催化剂盐可能具有相似的晶格结构，使得催化剂盐中的M元素易于进入锂盐中，形成锂盐与催化剂盐的共晶材料，提高电化学过程中M元素对于锂盐分解的催化作用，使得含锂材料具有低的分解电位，改善其补锂效果和电池的循环稳定性。
在任意实施方式中，所述含锂材料为球形或类球形。
球形或类球形的补锂材料易于在极片中与活性材料形成紧密堆积，利于极片压实密度的保持和提高。
在任意实施方式中，含锂材料颗粒为在外壳的内部具有空腔的空心颗粒。
伴随着含锂材料的不断分解以及锂离子的不断释放，含锂材料体积不断缩小，与正极极片的其它部分出现空隙，含锂材料孤立于正极极片的导电网络中，使得其电化学分解效率大幅度降低，甚至形成于正极极片中的“孤岛”，难以改善电池的循环稳定性。本申请实施例提供的空心颗粒状的含锂材料能够有效提高含锂材料的利用率，使得正极极片中少量含锂材料的添加就能有效改善二次电池的循环稳定性。
在任意实施方式中，含锂材料颗粒的体积分布粒径Dv50满足：0.1μm≤Dv50≤10μm，可选地，1μm≤Dv50≤10μm。
体积分布粒径Dv50在合适范围内的含锂材料具有良好的动力学性能和较低的分解电位，有助于提高电池的循环稳定性。
在任意实施方式中，空心颗粒的外壳壁厚与空心颗粒的直径比s满足10：100≤s≤30：100。
空心颗粒的外壳壁厚与空心颗粒的直径比s在合适的范围内，有利于提升含锂材料的分解率，降低生产成本，提高生产效益。
在任意实施方式中，含锂材料中还包括导电材料，可选地，导电材料包括石墨烯、碳纳米管、碳纳米纤维、乙炔黑、超级炭黑、科琴炭黑中的至少一种。
含锂材料中包括导电材料可以提升含锂材料的导电性，进一步降低含锂材料的分解电位，提升锂盐的分解效率，有利于二次电池循环稳定性的进一步改善。
在任意实施方式中，基于含锂材料的总质量计，导电材料的质量占比为1％-10％，可选为1％-5％。
导电材料的质量占比在合适的范围内，含锂材料兼具良好的动力学性能和锂容量，既能有效降低含锂材料的分解电位，又能有效提高补锂效率，进一步改善二次电池的循环稳定性。
在任意实施方式中，含锂材料的分解电压为3.8V-4.5V，可选为4.0V-4.48V。
含锂材料具有较低的分解电压，有利于充分发挥补锂效果，进一步改善二次电池的循环稳定性。本申请的第二方面提供一种含锂材料在二次电池中作为补锂剂的应用。
本申请的第三方面提供一种含锂材料的制备方法，制备方法包括：通过结晶制备含锂材料，含锂材料包括通式如式I的组分，
LiaMbY  式I
其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a<2、0.01≤b≤0.2。
通过结晶制备本申请的含锂材料，过渡金属元素或除锂元素外的碱金属元素在共结晶的过程中取代锂元素，使得催化元素与锂元素实现原子层级的均匀混合，形成固溶相效果，从而有效增强了催化元素的催化能力；相比于催化剂与补锂剂的物理混合，能够更加有效地降低含锂材料的分解电位，有利于进一步提高电池的循环稳定性。
在任意实施方式中，制备方法具体包括：将混合液结晶制备含锂 材料，混合液包括锂盐与催化剂盐，锂盐与催化剂盐具有相同的阴离子，阴离子包括草酸根、方酸根、碳酸根中的一种或多种，催化剂盐的阳离子包括M元素。
具有相同阴离子的催化剂盐与锂盐具有类似的晶体结构，在混合液结晶过程中催化剂盐的阳离子易于取代锂离子，形成固溶相效果，提升M元素的催化效率，有效降低锂盐的分解电压，且可以减少含锂材料制备过程中引入其它杂质离子，从而综合提升电池的循环稳定性。
在任意实施方式中，混合液中还包括导电材料，可选地，导电材料包括导电碳材料。
在含锂材料的制备过程中加入导电碳，有利于形成具有导电网络的含锂材料，增强含锂材料的导电性能，有利于降低含锂材料中锂盐的分解电压，提升电池的循环稳定性。
在任意实施方式中，采用喷雾干燥法进行结晶。
采用喷雾干燥法进行结晶，可以通过调节喷雾干燥的喷雾气压、进风温度、出风温度等工艺条件来调节含锂材料颗粒的颗粒尺寸，提高产品制备的可控性。且喷雾干燥法成本低，适用于工业化生产。在喷雾干燥过程中，溶液先被雾化成小液滴，然后在高温条件下瞬间干燥，使得催化剂盐在自结晶前，更易于在锂盐晶格中形成固溶相，产生共晶。
在任意实施方式中，喷雾干燥的进风温度为170℃-230℃，出风温度为100℃-140℃。上述条件利于实现瞬间干燥，有利于含锂材料的制备。
在任意实施方式中，制备方法具体包括：混合包含锂盐的溶液与包含催化剂盐的溶液，得到第一混合液；将第一混合液与包含导电材料的溶液混合后，得到第二混合液；喷雾干燥第二混合液制备含锂材料。
本申请的第四方面提供一种正极极片，正极极片包括集流体以及设置于集流体至少一侧的正极膜层，正极膜层包括补锂剂，补锂剂包括第一方面的含锂材料或第三方面的制备方法制备的含锂材料。
在任意实施方式中，基于正极膜层的总质量计，其中补锂剂的质量占比为0.5％～20％，可选为1％～10％。
补锂剂在正极膜层中的质量占比在合适的范围内，可以有效地同步提升电池的循环稳定性和容量。
在任意实施方式中，正极膜层包括正极活性材料，可选地，正极活性材料包括含锂磷酸盐、锂过渡金属氧化物及其各自的改性材料；进一步可选地，所述正极活性材料包括含锂磷酸盐及其改性材料。
含锂磷酸盐的电压窗口上限电压较低，使得分解电压较高的常规补锂剂无法应用于包含含锂磷酸盐的极片中。本申请的含锂材料具有低的分解电压，可以在含锂磷酸盐的电压窗口内进行分解补充活性锂，从而提升电池的循环稳定性，匹配以含锂磷酸盐作为正极活性材料的电池对循环稳定性和寿命的需求。
在任意实施方式中，含锂材料的平均粒径大于正极活性材料的平均粒径。本申请的第五方面提供一种二次电池，包括第四方面的正极极片。
本申请的第六方面提供一种用电装置，包括第五方面的二次电池。
附图说明
图1是本申请一实施方式的含锂材料的扫描电镜图；
图2是本申请一实施方式的正极极片的截面图；
图3是本申请实施例1的电池在0.1C倍率下的恒流充电曲线；
图4是本申请对比例1的电池在0.1C倍率下的恒流充电曲线；
图5是本申请一实施方式的二次电池的示意图；
图6是图5所示的本申请一实施方式的二次电池的分解图；
图7是本申请一实施方式的电池模块的示意图；
图8是本申请一实施方式的电池包的示意图；
图9是图8所示的本申请一实施方式的电池包的分解图；
图10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。
图11是本申请一实施方式的含锂材料的X射线衍射图。
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。
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含锂材料、制备方法、正极极片、二次电池及用电装置的实施方式。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，优选是顺序进行的。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)。
目前，补锂材料存在动力学性能较差、分解电位高(直接添加到正极中的分解电位大于4.5V)的问题，不利于锂离子在正极的工作电压范围内发生有效脱锂，使得补锂剂不能充分发挥补锂效能、实现锂离子在二次电池中的充分释放，且高电位下极片与电解液容易发生副反应，增加电池产气、恶化电池在长期循环过程中的电化学表现。
[含锂材料]
基于此，本申请提出了一种含锂材料，含锂材料包括通式如式I的组分，
LiaMbY  式I
其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a<2、0.01≤b≤0.2。
在本文中，“草酸根”是指草酸失去两个氢原子得到的离子(C2O4 2-)。
在本文中，“方酸根”是指方酸失去两个氢原子得到的离子(C4O4 2-)。
在本文中，“碳酸根”是指碳酸失去两个氢原子得到的离子(CO3 2-)。
本申请中含锂材料的组成可以通过本领域任意公知方法进行测试。作为示例，本申请中含锂材料的组成可以通过结构分析法和元素分析法结合加以确定。采用X射线衍射仪(XRD)测定含锂材料的晶体结构，将XRD谱图与物质的标准卡片对比，分析获知含锂材料的主要物相。可以理解，Y包括草酸根、方酸根、碳酸根中的一种或多种并不代表对其阴离子中碳元素与氧元素比例的严格限定；在制备及其使用过程中，含锂材料可能会出现氧空位等缺陷，但这并不影响对其整体物相和组成的判断。含锂材料中锂元素与M元素的含量及其比例可参照GB/T 30902-2014法，用Thermo ICAP7400电感耦合等离子体-发射光谱仪(ICP-OES)进行测试得到。或者可以通过透射电镜分析单晶中的金属元素组成及其比例。
草酸锂、碳酸锂、方酸锂这类锂盐具有高理论容量和良好的稳定性，适用于加入正极极片中作为提供活性锂的补锂剂，在化成阶段分解释放活性锂并产生气体，补足电池负极对活性锂的不可逆消耗，提升电池的容量，且生成的气体在化成时会排出，不影响电池的性能。然而此类锂盐具有较高的脱锂电位，高电位下的脱锂一方面不容易实现其补锂效能的充分发挥，另一方面使得极片易于在高电位下与电解液发生副反应恶化电池的长期循环稳定性。
本申请实施例中的含锂材料能够更高效地发挥M元素对电子的调控能力，提升含锂材料的电化学反应活性，降低其分解电位，提高含锂材料在二次电池电压窗口内的补锂效果，改善电池的循环稳定性。
相比于在正极极片中同时加入催化剂与补锂剂，该含锂材料实现了催化剂与补锂剂在原子层级的均匀混合，能够更加有效地降低含锂材料的分解电位，提升电池循环稳定性的改善效果。
在一些实施方式中，a为1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9或其间的任意数值。
在一些实施方式中，b为0.01、0.04、0.07、0.1、0.12、0.14、0.16、0.18、0.2或其间的任意数值。
在一些实施方式中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种。
在一些实施方式中，M包括镍、钴、锰、铁、钠、钾中的一种或多种。
在一些实施方式中，1.6≤a<2，0.01≤b≤0.1。
a与b在合适范围内的含锂材料能够发挥良好的催化效果，有效降低含锂材料的分解电压，提升电池的循环稳定性。
在一些实施方式中，含锂材料为锂盐与催化剂盐的共晶材料，所述锂盐与所述催化剂盐具有相同的阴离子Y，所述催化剂盐的阳离子包括M元素。
共晶是指一种微量组分掺入到一种认为可溶的固相结晶中。在一些实施方式中，共晶为置换固溶体。置换固溶体是指微量物质的离子、分子或小的晶格单位取代常量物质晶格中相应的离子、分子或小的晶格单位形成的物质。
具有相同阴离子Y的锂盐与催化剂盐可能具有相似的晶格结构，使得催化剂盐中的M元素易于进入锂盐中，形成锂盐与催化剂盐的共晶材料，提高电化学过程中M元素对于锂盐分解的催化作用，使得含锂材料具有低的分解电位，改善其补锂效果和电池的循环稳定性。
在一些实施方式中，所述含锂材料为球形或类球形。
含锂材料的表面形貌如图1所示，呈现球形或类球形。球形或类球形的补锂材料易于在极片中与活性材料形成紧密堆积，利于极片压实密度的保持和提高。
在一些实施方式中，含锂材料为在外壳的内部具有空腔的空心颗粒。
将含锂材料添加到极片中，采用氩离子束垂直于极片大面将极片切口，采用扫描电镜观测极片的横截面，可以看到含锂材料的内部呈现空腔，如图2所示。
伴随着含锂材料的不断分解以及锂离子的不断释放，含锂材料体积不断缩小，与正极极片的其它部分出现空隙，含锂材料孤立于正极极片的导电网络中，使得其电化学分解效率大幅度降低，甚至形成于正极极片中的“孤岛”，难以改善电池的循环稳定性。本申请实施例提供的空心颗粒状的含锂材料能够有效提高含锂材料的利用率，使得 正极极片中少量含锂材料的添加就能有效改善二次电池的循环稳定性。
在一些实施方式中，含锂材料的体积分布粒径Dv50满足：0.1μm≤Dv50≤10μm。
在一些实施方式中，含锂材料的体积分布粒径Dv50满足：1μm≤Dv50≤10μm。
在本文中，术语“Dv50”指在粒度分布曲线中，颗粒的累计体积分布数达到50％时所对应的粒径。
本申请中，Dv50可以采用本领域已知的方法进行测试，作为示例，参照GB/T 19077-2016粒度分布激光衍射法，采用如英国马尔文仪器有限公司的Mastersizer 2000E型激光粒度分析仪进行测定。
在一些实施方式中，含锂材料的体积分布粒径Dv50为0.1μm、1μm、2μm、3μm、4μm、5μm、6μm、7μm、8μm、9μm、10μm或其间的任意数值。
体积分布粒径Dv50在合适范围内的含锂材料具有良好的动力学性能和较低的分解电位，有助于提高电池的循环稳定性。
在一些实施方式中，空心颗粒的外壳壁厚与空心颗粒的直径比s满足10：100≤s≤30：100。
本申请中，空心颗粒的外壳壁厚与空心颗粒的直径比可以采用扫面电镜进行测量。通过氩离子束垂直于正极极片大面切割极片，暴露出含锂材料的截面，采用扫描电镜测量空心颗粒的外壳壁厚与空心颗粒的直径比。在五个方向上测量空心颗粒的最长距离，取平均值，作为该空心颗粒的直径；在该空心颗粒截面随机取5处测量该空心颗粒的外壳壁厚，取5次测量结果的平均值作为该空心颗粒的外壳壁厚。通过同一空心颗粒的外壳壁厚的平均值与同一空心颗粒的直径的平均值的比值作为空心颗粒的外壳壁厚与空心颗粒的直径比s。
在一些实施方式中，空心颗粒的外壳壁厚与空心颗粒的直径比s为10：100、12：100、14：100、16：100、18：100、20：100、22：100、24：100、26：100、28：100、30：100或其间的任意数值。
空心颗粒的外壳壁厚与空心颗粒的直径比s在合适的范围内，有 利于提升含锂材料的分解率，降低生产成本，提高生产效益。
在一些实施方式中，含锂材料中还包括导电材料。
在一些实施方式中，导电材料包括导电碳材料。
在一些实施方式中，导电材料包括石墨烯、碳纳米管、碳纳米纤维、乙炔黑、超级炭黑(Super P)、科琴炭黑中的至少一种。
在一些实施方式中，导电材料包括碳纳米管。
含锂材料中包括导电材料可以提升含锂材料的导电性，进一步降低含锂材料的分解电位，提高含锂材料的分解效率，有利于二次电池循环稳定性的进一步改善。
在一些实施方式中，基于含锂材料的总质量计，导电材料的质量占比为1％-10％。
在一些实施方式中，基于含锂材料的总质量计，导电材料的质量占比为1％、2％、3％、4％、5％、6％、7％、8％、9％、10％或其间的任意数值。
在一些实施方式中，基于含锂材料的总质量计，导电材料的质量占比为1％-5％。
导电材料的质量占比在合适的范围内时，含锂材料兼具良好的动力学性能和锂容量，既能有效降低含锂材料的分解电位，又能有效提高补锂效率，进一步改善二次电池的循环稳定性。
在一些实施方式中，含锂材料的分解电压为3.8V-4.5V，可选为4.0V-4.48V。
在一些实施方式中，含锂材料的分解电压可选为3.8V、3.85V、3.9V、3.95V、4.0V、4.05V、4.1V、4.15V、4.2V、4.25V、4.3V、4.35V、4.4V、4.45V、4.48V、4.5V或任意二者间的数值范围。
补锂剂分解电压可以通过本领域任意公知方法测试得到。作为示例，将补锂剂作为添加剂加入正极极片中，装配成锂电池，测试锂电池首次充电时在3.65V-4.5V区间的容量(Q)，以电压数据V为横坐标轴，对应的dQ/dV作为纵坐标轴作图，即可得到随V变化的dQ/dV曲线，曲线在3.65V-4.5V区间内出峰的位置对应的电压值即为含锂材料的分解电压。为了减少极化，提高测试准确性，在3.65V-4.5V区 间以低倍率进行充电，例如0.05C。
本申请的第二方面提供一种含锂材料在二次电池中作为补锂剂的应用。
本申请的第三方面提供一种含锂材料的制备方法，制备方法包括：通过结晶制备含锂材料，含锂材料包括通式如式I的组分，
LiaMbY  式I
其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a≤2、0.01≤b≤0.2。
本文中，结晶是指溶质析出，形成晶体的方法。
在一些实施方式中，结晶过程中微量物质的离子、分子或小的晶格单位取代沉淀物晶格上的常量物质，并进入到晶格内部而从液相转移到固相形成共晶。采用结晶法制备本申请的含锂材料，M元素在结晶的过程中进入含锂材料中，使得M元素与锂元素实现原子层级的均匀混合，形成固溶相效果，从而有效增强了M元素的催化能力；相比于催化剂与补锂剂的物理混合，能够更加有效地降低含锂材料的分解电位，有利于进一步提高电池的循环稳定性。
在一些实施方式中，制备方法具体包括：将混合液结晶制备含锂材料，所述混合液包括锂盐与催化剂盐，所述锂盐与所述催化剂盐具有相同的阴离子，所述阴离子包括草酸根、方酸根、碳酸根中的一种或多种，所述催化剂盐的阳离子包括M元素。
具有相同阴离子的催化剂盐与锂盐可能具有类似的晶体结构，在结晶过程中催化剂盐的M元素易于进入锂盐中，形成固溶相效果，提升M元素的催化效率，有效降低锂盐的分解电压，且可以减少含锂材料制备过程中引入其它杂质离子，从而综合提升电池的循环稳定性。
在一些实施方式中，混合液中还包括导电材料，可选地，导电材料包括导电碳材料。
在含锂材料的制备过程中加入导电材料，有利于形成具有导电网络的含锂材料，增强含锂材料的导电性能，有利于降低含锂材料的分 解电压，提升电池的循环稳定性。
在一些实施方式中，采用喷雾干燥法进行所述结晶。
在本文中，“喷雾干燥法”是指将粉浆或溶液喷入造粒塔，在喷雾热风的作用下，粉浆或溶液干燥，从而得到球状团粒的造粒方法。该方法制备的材料颗粒精度高，尺寸均匀。
采用喷雾干燥法进行结晶，可以通过调节喷雾干燥的喷雾气压、进风温度、出风温度等工艺条件来调节含锂材料的颗粒尺寸，提高产品制备的可控性。且喷雾干燥法成本低，适用于工业化生产。
在喷雾干燥过程中，溶液先被雾化成小液滴，然后在高温条件下瞬间干燥，使得催化剂盐在自结晶前，更易于在锂盐晶格中形成固溶相。
在一些实施方式中，喷雾干燥的进风温度为170℃-230℃，和/或，出风温度为100℃-140℃。
在一些实施方式中，喷雾干燥的进风温度可选为170℃、180℃、190℃、200℃、210℃、220℃、230℃或任意二者间的数值范围。
在一些实施方式中，喷雾干燥的出风温度可选为100℃、110℃、120℃、130℃、140℃或任意二者间的数值范围。上述条件利于实现瞬间干燥，有利于含锂材料的制备。
在一些实施方式中，制备方法具体包括：混合包含锂盐的溶液与包含催化剂盐的溶液，得到第一混合液；将第一混合液与包含导电材料的溶液混合后，得到第二混合液；喷雾干燥第二混合液制备含锂材料。
在一些实施方式中，包含催化剂盐的溶液中包含络合剂。
在一些实施方式中，络合剂包括氨水、乙醇胺、氨三乙酸钠、二乙烯三胺五羧酸盐、酒石酸、庚糖酸盐、葡萄糖酸钠、海藻酸钠、聚丙烯酸中的一种或多种。
络合剂可以与催化剂盐中的阳离子络合，提高M元素在锂盐中的固溶效果。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。
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。
[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膜层。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，正极膜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，正极膜层包括补锂剂，补锂剂包括第一方面的含锂材料或第三方面的制备方法制备的含锂材料。
在一些实施方式中，基于正极膜层的总质量计，补锂剂的质量占比为0.5％～20％。
在一些实施方式中，基于正极膜层的总质量计，补锂剂的质量占比为0.5％、1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、11％、12％、13％、14％、15％、16％、17％、18％、19％、20％或其间的任意数值。
在一些实施方式中，基于正极膜层的总质量计，补锂剂的质量占比为1％～10％。
补锂剂在正极膜层中的质量占比在合适的范围内，可以有效地同步提升电池的循环稳定性和容量。
在一些实施方式中，正极膜层包括正极活性材料。
在一些实施方式中，正极活性材料包括含锂磷酸盐、锂过渡金属氧化物及其各自的改性材料。
正极活性材料可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料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材料的传统材料。这些正极活性材料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LiCoO2)、锂镍氧化物(如LiNiO2)、锂锰氧化物(如LiMnO2、LiMn2O4)、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LiNi1/3Co1/3Mn1/3O2(也可以简称为NCM333)、LiNi0.5Co0.2Mn0.3O2(也可以简称为NCM523)、LiNi0.5Co0.25Mn0.25O2(也可以简称为NCM211)、LiNi0.6Co0.2Mn0.2O2(也可以简称为NCM622)、LiNi0.8Co0.1Mn0.1O2(也可以简称为NCM811)、锂镍钴铝氧化物(如LiNi0.85Co0.15Al0.05O2)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LiFePO4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO4)、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，正极活性材料包括含锂磷酸盐。
含锂磷酸盐的电压窗口上限电压较低，使得分解电压较高的常规补锂剂无法应用于包含含锂磷酸盐的极片中。本申请的含锂材料具有低的分解电压，可以在含锂磷酸盐的电压窗口内分解补充活性锂，从而提升电池的循环稳定性，匹配以含锂磷酸盐作为正极活性材料的电池对循环稳定性和寿命的需求。
在一些实施方式中，含锂材料的平均粒径大于所述正极活性材料的平均粒径。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，正极膜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，正极膜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，例如正极活性材料、补锂剂、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以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。
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，负极膜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。
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，负极活性材料可采用本领域公知的用于电池的负极活性材料。作为示例，负极活性材料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材料的传统材料。这些负极活性材料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，负极膜层还可选地包括粘结剂。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)中的至少一种。
在一些实施方式中，负极膜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，负极膜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，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，例如负极活性材料、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，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，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。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
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。
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、方形或其他任意的形状。例如，图5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6，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7是作为一个示例的电池模块4。参照图7，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8和图9是作为一个示例的电池包1。参照图8和图9，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10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。
制备方法
实施例1
(1)补锂剂的制备
在25℃下，将0.03mol的草酸镍溶解于100g的去离子水中，加入3.5mL氨水，搅拌20min后再超声20min进一步分散，得到包含催化剂盐的溶液；将1mol的草酸锂溶解于300g的去离子水中，搅拌20min后再超声20min进一步分散，得到包含锂盐的溶液；将质量浓度为0.9％的碳纳米管(CNT)浆料加入500mL去离子水中后搅拌60min，得到包含导电材料的溶液；先将包含催化剂盐的溶液加入包含锂盐的溶液中，搅拌20min后得到第一混合液，然后将第一混合液加入包含导电材料的溶液中，得到第二混合液，搅拌1h后再超声1h，最后将得到的溶液喷雾干燥，喷雾干燥的进风温度为200℃，喷雾干燥的出风温度为120℃，在喷雾干燥过程中发生共结晶反应，即可得到草酸锂-草酸镍共晶材料，通式为Li1.94Ni0.03C2O4、Dv50为3um、外壳壁厚与空心颗粒的直径比s为20：100的含锂材料，含锂材料中碳纳米管的质量含量为3％。
(2)正极极片的制备
将上述得到的含锂材料、磷酸铁锂材料、导电剂碳黑、粘结剂聚偏二氟乙烯(PVDF)按重量比为5：92：1：2，在N-甲基吡咯烷酮(NMP)溶剂体系中充分搅拌混合均匀，得到正极浆料；之后将正极浆料均匀涂覆于正极集流体上，之后经过烘干、冷压、分切，得到正极极片。磷酸铁锂的Dv50为1.5μm。
(3)负极极片的制备
将活性物质人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按照重量比为96.2：0.8：0.8：1.2溶于溶剂去离子水中，混合均匀后制备成负极浆料；将负极浆料一次或多 次均匀涂覆在负极集流体铜箔上，经过烘干、冷压、分切得到负极极片。
(4)电解液的制备
在氩气气氛手套箱中(H2O<0.1ppm，O2<0.1ppm)，将有机溶剂碳酸乙烯酯(EC)/碳酸甲乙酯(EMC)按照体积比3/7混合均匀，加入12.5％LiPF6锂盐溶解于有机溶剂中，搅拌均匀，得到电解液。
(5)隔离膜
以聚丙烯膜作为隔离膜。
(6)锂离子电池的制备
将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，然后卷绕得到裸电芯，给裸电芯焊接极耳，并将裸电芯装入铝壳中，并在80℃下烘烤除水，随即注入电解液并封口，得到不带电的电池。不带电的电池再依次经过静置、热冷压。并进行化成处理，先以0.1C恒流充电10min，再以1/3C恒流充电至3.65V，然后在3.65V恒压充电至0.05C，搁置5min，最后以0.05C恒流充电至截至上限电压4.5V。然后经过整形、容量测试等工序，获得锂离子电池产品。
实施例2-9的制备方法与实施例1基本相同，区别在于调整了催化剂盐或锂盐的种类，或催化剂盐与锂盐的摩尔比。
实施例10的制备方法与实施例1基本相同，区别在于在补锂剂制备过程中不加入CNT。
对比例1
对比例1的制备方法与实施例1基本相同，区别在于在补锂剂制备过程中不加入草酸镍和CNT。
对比例2
对比例2中电池的制备方法与实施例1基本相同，区别在于对比例2中补锂剂的制备方法为：
按照3：100的摩尔比称取草酸镍与草酸锂材料，通过球磨使二者混合均匀，得到复合材料。
性能测试
(1)XRD检测
采用X射线衍射仪对含锂材料以及原料进行检测，获得X射线衍射图谱。
(2)补锂剂分解电压测试
补锂剂分解电压在电芯化成过程中测得。将制备的电池，先以0.1C恒流充电10min，再以1/3C恒流充电至3.65V，然后在3.65V恒压充电至0.05C，搁置5min，最后以0.05C恒流充电至截至上限电压4.5V，记录设备中得到的电压(V)和容量(Q)数据，通过计算处理得到dQ/dV数据。以电压数据V为横坐标轴，对应的dQ/dV作为纵坐标轴作图，即可得到随V变化的dQ/dV曲线，曲线在3.65V-4.5V区间内出峰的位置对应的电压值即为补锂剂分解电压。
(3)二次电池循环容量保持率测试
在60℃下，将制备的电池，以1/3C恒流充电至3.65V，再以3.65V恒压充电至0.05C，搁置5min，再以1/3C放电至2.5V，所得容量记为初始容量C0。对上述同一个电池重复以上步骤，并同时记录循环第n次后电池的放电容量Cn，则每次循环后电池容量保持率Pn＝Cn/C0*100％。该测试过程中，第一次循环对应n＝1、第二次循环对应n＝2、……第100次循环对应n＝100。在上述测试条件下循环100次之后测得循环容量保持率，即P100的值。
结果分析
按照上述方法分别制备各实施例和对比例的电池，并测量各项性能参数，结果见表1。
表1

图11是本申请实施例1的补锂剂含锂材料的X射线衍射图谱。由图可见，含锂材料的X射线衍射峰与草酸锂基本一致，未表现出明显的草酸镍特征峰，说明含锂材料具有草酸锂的晶格结构，实现了镍在草酸锂中的固溶。
图3是本申请实施例1的电池在0.1C倍率下的恒流充电曲线；图4是本申请对比例1的电池在0.1C倍率下的恒流充电曲线。由图可见，本申请提供的含锂材料能够显著提高电池的容量。
实施例1-10的正极极片均包括LiaMbY的含锂材料，M包括过渡金属元素、除锂元素外的碱金属元素中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a≤2、0.01≤b≤0.2。由实施例和对比例的对比可见，本申请的含锂材料具有更低的分解电压，还能够有效提高电池的循环寿命。
由实施例1-3可见，含锂材料的阴离子为草酸根、方酸根、碳酸根时，含锂材料具有低的分解电压，电池具有良好的循环稳定性。含锂材料的阴离子为方酸根时，可以进一步降低含锂材料的分解电压，提升电池的循环稳定性。
由实施例1和实施例4-5可见，催化剂盐的金属离子为镍、铁、钠时，含锂材料具有低的分解电压，电池具有良好的循环稳定性。Li1.94Ni0.03C2O4相对于Li1.94Fe0.03C2O4和Li1.94Na0.06C2O4，具有更低的分解电压，提升电池的循环稳定性。
由实施例1和实施例10的对比可见，含锂材料中包括导电材料可以进一步降低含锂材料的分解电压，提升电池的循环稳定性。
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 (23)

  1. 一种含锂材料，其特征在于，所述含锂材料包括通式如式I的组分，
    LiaMbY  式I
    其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a<2、0.01≤b≤0.2。
  2. 根据权利要求1所述的含锂材料，其特征在于，
    1.6≤a<2，0.01≤b≤0.1。
  3. 根据权利要求1或2所述的含锂材料，其特征在于，
    所述含锂材料为锂盐与催化剂盐的共晶材料，所述锂盐与所述催化剂盐具有相同的阴离子Y，所述催化剂盐的阳离子包括M元素。
  4. 根据权利要求1至3中任一项所述的含锂材料，其特征在于，
    所述含锂材料为球形或类球形。
  5. 根据权利要求1至4中任一项所述的含锂材料，其特征在于，
    所述含锂材料为在外壳的内部具有空腔的空心颗粒。
  6. 根据权利要求1至5中任一项所述的含锂材料，其特征在于，
    所述含锂材料的体积分布粒径Dv50满足：0.1μm≤Dv50≤10μm，可选地，1μm≤Dv50≤10μm。
  7. 根据权利要求5或6所述的含锂材料，其特征在于，
    所述空心颗粒的外壳壁厚与所述空心颗粒的直径比s满足10：100≤s≤30：100。
  8. 根据权利要求1至7中任一项所述的含锂材料，其特征在于，
    所述含锂材料中还包括导电材料，可选地，所述导电材料包括石墨烯、碳纳米管、碳纳米纤维、乙炔黑、超级炭黑、科琴炭黑中的至少一种。
  9. 根据权利要求8所述的含锂材料，其特征在于，
    基于所述含锂材料的总质量计，所述导电材料的质量占比为1％-10％，可选为1％-5％。
  10. 根据权利要求1至9中任一项所述的含锂材料，其特征在于，
    所述含锂材料的分解电压为3.8V-4.5V，可选为4.0V-4.48V。
  11. 根据权利要求1至10中任一项所述的含锂材料在二次电池中作为补锂剂的应用。
  12. 一种含锂材料的制备方法，其特征在于，所述制备方法包括：
    通过结晶制备含锂材料，
    所述含锂材料包括通式如式I的组分，
    LiaMbY  式I
    其中，M包括镍、钴、锰、铁、钠、钾、钒、钛、铜、钨、锆、钼中的一种或多种；Y包括草酸根、方酸根、碳酸根中的一种或多种；1≤a≤2、0.01≤b≤0.2。
  13. 根据权利要求12所述的制备方法，其特征在于，所述制备方法具体包括：
    将混合液结晶制备含锂材料，所述混合液包括锂盐与催化剂盐，所述锂盐与所述催化剂盐具有相同的阴离子，所述阴离子包括草酸根、方酸根、碳酸根中的一种或多种，所述催化剂盐的阳离子包括M元素。
  14. 根据权利要求12或13所述的制备方法，其特征在于，所述混合液中还包括导电材料，可选地，导电材料包括导电碳材料。
  15. 根据权利要求12至14中任一项所述的制备方法，其特征在于，采用喷雾干燥法进行所述结晶。
  16. 根据权利要求15所述的制备方法，其特征在于，
    所述喷雾干燥的进风温度为170℃-230℃，和/或，出风温度为100℃-140℃。
  17. 根据权利要求12至16中任一项所述的制备方法，其特征在于，所述制备方法具体包括：
    混合包含锂盐的溶液与包含催化剂盐的溶液，得到第一混合液；
    将所述第一混合液与包含所述导电材料的溶液混合后，得到第二混合液；
    喷雾干燥所述第二混合液制备所述含锂材料。
  18. 一种正极极片，其特征在于，所述正极极片包括集流体以及设置于所述集流体至少一侧的正极膜层，所述正极膜层包括补锂剂，所述补锂剂包括权利要求1至9中任一项所述的含锂材料或权利要求11至17中任一项所述的制备方法制备的含锂材料。
  19. 根据权利要求18所述的正极极片，其特征在于，基于所述正极膜层的总质量计，所述补锂剂的质量占比为0.5％～20％，可选为1％～10％。
  20. 根据权利要求18或19所述的正极极片，其特征在于，所述正极膜层包括正极活性材料；可选地，所述正极活性材料包括含锂磷酸盐、锂过渡金属氧化物及其各自的改性材料；进一步可选地，所述正极活性材料包括含锂磷酸盐及其改性材料。
  21. 根据权利要求20所述的正极极片，其特征在于，
    所述含锂材料的平均粒径大于所述正极活性材料的平均粒径。
  22. 一种二次电池，其特征在于，包括权利要求18至21中任一项所述的正极极片。
  23. 一种用电装置，其特征在于，包括权利要求22所述的二次电池。
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