Lithium-containing material and preparation method therefor, positive electrode sheet, secondary battery and power-consuming device

Abstract

Provided are a lithium-containing material and a preparation method therefor, a positive electrode sheet, a secondary battery and a power-consuming device. The lithium-containing material comprises a component as shown in formula I, wherein M includes one or more of nickel, cobalt, manganese, iron, sodium, potassium, vanadium, titanium, copper, tungsten, zirconium and molybdenum; and Y includes one or more of oxalate anions, squarate anions and carbonate anions; 1≤a＜2, and 0.01≤b≤0.2. The lithium-containing material has a low decomposition voltage, and as a lithium supplementing agent, facilitates the improvement of the cycling stability of a battery.

Description

Lithium-containing material, preparation method, positive electrode sheet, secondary battery and electrical device Technical Field

[0001] 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. Background Art

[0002] In recent years, as the application scope of secondary batteries has become increasingly wider, secondary batteries have been widely used in energy storage power 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.

[0003] As the battery life requirements of electrical devices continue to increase, the industry has also put forward higher requirements for the cycle life of secondary batteries.

[0004] Summary of the Invention

[0005] 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. When added as a lithium supplement to a secondary battery, the lithium-containing material can effectively improve the cycle stability of the secondary battery.

[0006] The first aspect of the present application provides a lithium-containing material, which includes a component as shown in Formula I.

[0007] Li a M b Y Formula I

[0008] Wherein, 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.

[0009] In the embodiments of this application, the M element in the lithium-containing material's ability to regulate electrons enhances the material's electrochemical activity, lowers its decomposition potential, and enhances the lithium replenishment effect of the lithium-containing material within the secondary battery's voltage window, thereby improving the battery's cycling stability. Compared to adding a catalyst and a lithium replenisher simultaneously to the positive electrode, this lithium-containing material achieves a uniform mixing of the catalyst and the lithium replenisher at the atomic level, more effectively lowering the decomposition potential of the lithium-containing material and enhancing the battery's cycling stability.

[0010] In any embodiment, 1.6≤a<2, 0.01≤b≤0.1.

[0011] 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.

[0012] In any embodiment, 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, and the cation of the catalyst salt includes an M element.

[0013] 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.

[0014] In any embodiment, the lithium-containing material is spherical or spherical-like.

[0015] 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.

[0016] In any embodiment, the lithium-containing material particles are hollow particles having a cavity inside the shell.

[0017] As the lithium-containing material continues to decompose and release lithium ions, the volume of the lithium-containing material continues to shrink, and gaps appear between it and the rest 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 "islands" in the positive electrode sheet, making it difficult to improve the battery's cycle stability. The hollow granular lithium-containing material provided in the embodiments 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 sheet can effectively improve the cycle stability of the secondary battery.

[0018] In any embodiment, the volume distribution particle size Dv50 of the lithium-containing material particles satisfies: 0.1 μm≤Dv50≤10 μm, optionally, 1 μm≤Dv50≤10 μm.

[0019] 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.

[0020] In any embodiment, 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.

[0021] 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.

[0022] In any embodiment, the lithium-containing material further includes a conductive material. Optionally, the conductive material includes at least one of graphene, carbon nanotubes, carbon nanofibers, acetylene black, super carbon black, and Ketjen black.

[0023] Including a conductive material in the lithium-containing material can improve the conductivity of the lithium-containing material, further reduce the decomposition potential of the lithium-containing material, and improve the decomposition efficiency of the lithium salt, which is conducive to further improvement of the cycle stability of the secondary battery.

[0024] In any embodiment, based on the total mass of the lithium-containing material, the mass proportion of the conductive material is 1%-10%, optionally 1%-5%.

[0025] The mass proportion of the conductive material is within an appropriate range, and 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.

[0026] In any embodiment, the decomposition voltage of the lithium-containing material is 3.8V-4.5V, optionally 4.0V-4.48V.

[0027] The lithium-containing material has a low decomposition voltage, which is conducive to fully exerting the lithium replenishment 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 replenisher in a secondary battery.

[0028] The third aspect of the present application provides a method for preparing a lithium-containing material, the method comprising: preparing the lithium-containing material by crystallization, wherein the lithium-containing material comprises a component of the general formula I,

[0029] Li a M b Y Formula I

[0030] Wherein, 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.

[0031] The lithium-containing material of the present application is prepared by crystallization, and transition metal elements or alkali metal elements other than lithium replace lithium elements during the co-crystallization process, so that the catalytic elements and lithium elements are evenly mixed at the atomic level, forming a solid solution phase effect, thereby effectively enhancing the catalytic ability of the catalytic elements; compared with the physical mixing of the catalyst and the lithium supplement, it can more effectively reduce the decomposition potential of the lithium-containing material, which is beneficial to further improve the cycle stability of the battery.

[0032] In any embodiment, the preparation method specifically includes: crystallizing the mixed solution to prepare a lithium-containing 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 element M.

[0033] Catalyst salts with the same anions have similar crystal structures to lithium salts. During the crystallization of the mixed liquid, the cations of the catalyst salts easily replace lithium ions, forming a solid solution phase effect, 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.

[0034] In any embodiment, the mixed liquid further includes a conductive material. Optionally, the conductive material includes a conductive carbon material.

[0035] Adding conductive carbon during the preparation of lithium-containing materials is beneficial to forming lithium-containing materials with a conductive network, enhancing the conductive properties of lithium-containing materials, reducing the decomposition voltage of lithium salts in lithium-containing materials, and improving the cycle stability of batteries.

[0036] In any embodiment, the crystallization is performed using spray drying.

[0037] Spray drying crystallization allows the particle size of the lithium-containing material to be adjusted by adjusting process conditions such as spray pressure, inlet air temperature, and outlet air temperature, thereby improving the controllability of product preparation. Spray drying is also low-cost and suitable for industrial production. During the spray drying process, the solution is first atomized into small droplets and then dried instantaneously at high temperature. This allows the catalyst salt to more easily form a solid solution phase within the lithium salt lattice before self-crystallization, producing a eutectic.

[0038] In any embodiment, the air inlet temperature of the spray drying is 170° C.-230° C., and the air outlet temperature is 100° C.-140° C. The above conditions are conducive to achieving instant drying and are beneficial to the preparation of lithium-containing materials.

[0039] In any embodiment, 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.

[0040] 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.

[0041] In any embodiment, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 0.5% to 20%, and can be optionally 1% to 10%.

[0042] When 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.

[0043] In any embodiment, the positive electrode film layer includes a positive electrode active material. Optionally, the positive electrode active material includes lithium-containing phosphate, lithium transition metal oxide and their respective modified materials; further optionally, the positive electrode active material includes lithium-containing phosphate and its modified materials.

[0044] The upper limit of the voltage window of lithium-containing phosphates is relatively low, making conventional lithium replenishers with higher decomposition voltages unsuitable for use in electrodes containing lithium-containing phosphates. The lithium-containing material of the present application has a low decomposition voltage and can decompose and replenish active lithium within the voltage window of lithium-containing phosphates, thereby improving the battery's cycling stability and meeting the cycling stability and lifespan requirements of batteries using lithium-containing phosphates as positive electrode active materials.

[0045] In any embodiment, the average particle size of the lithium-containing material is greater than the average particle size of the positive electrode active material. A fifth aspect of the present application provides a secondary battery comprising the positive electrode sheet of the fourth aspect.

[0046] A sixth aspect of the present application provides an electrical device comprising the secondary battery of the fifth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG1 is a scanning electron microscope image of a lithium-containing material according to an embodiment of the present application;

[0048] FIG2 is a cross-sectional view of a positive electrode sheet according to an embodiment of the present application;

[0049] FIG3 is a constant current charging curve of the battery of Example 1 of the present application at a rate of 0.1C;

[0050] FIG4 is a constant current charging curve of the battery of Comparative Example 1 of the present application at a rate of 0.1C;

[0051] FIG5 is a schematic diagram of a secondary battery according to an embodiment of the present application;

[0052] FIG6 is an exploded view of the secondary battery according to one embodiment of the present application shown in FIG5 ;

[0053] FIG7 is a schematic diagram of a battery module according to an embodiment of the present application;

[0054] FIG8 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0055] FIG9 is an exploded view of the battery pack according to one embodiment of the present application shown in FIG8 ;

[0056] FIG. 10 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0057] FIG11 is an X-ray diffraction pattern of a lithium-containing material according to an embodiment of the present application.

[0058] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0059] Below, the embodiments of the lithium-containing material, preparation method, positive electrode sheet, secondary battery and electric device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0060] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and 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 special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this 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.

[0061] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0062] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0063] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, 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.

[0064] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0065] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: 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).

[0066] At present, lithium-supplementing materials have problems such as poor kinetic performance and high decomposition potential (the decomposition potential when directly added to the positive electrode is greater than 4.5V), which is not conducive to the effective delithiation of lithium ions within the working voltage range of the positive electrode. As a result, the lithium-supplementing agent cannot fully exert its lithium-supplementing efficiency and realize the full release of lithium ions in the secondary battery. In addition, under high potential, side reactions are prone to occur between the electrode and the electrolyte, which increases battery gas production and deteriorates the electrochemical performance of the battery during long-term cycling.

[0067] [Lithium-containing materials]

[0068] Based on this, the present application proposes a lithium-containing material, which includes a component of the general formula I,

[0069] Li a M b Y Formula I

[0070] Wherein, 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.

[0071] In this article, "oxalate" refers to the ion obtained by oxalic acid losing two hydrogen atoms (C2O4 2- ).

[0072] In this article, "squarate" refers to the ion obtained by squaraine losing two hydrogen atoms (C4O4 2- ).

[0073] In this article, "carbonate" refers to the ion obtained by losing two hydrogen atoms from carbonic acid (CO3 2- ).

[0074] The composition of the lithium-containing material in this application can be tested by any method known in the art. As an example, the composition of the lithium-containing material in this application can be determined by combining structural analysis and elemental analysis. The crystal structure of the lithium-containing material is determined by X-ray diffractometer (XRD), and the XRD spectrum is compared with the standard card of the material to analyze and obtain the main phase of the lithium-containing material. It can be understood that Y including one or more of oxalate, squarate, and carbonate does not represent a strict limitation on the ratio of carbon to oxygen in its anions; during the preparation and use process, the lithium-containing material may have defects such as oxygen vacancies, but this does not affect the judgment of its overall phase and composition. The content and ratio of lithium and M elements in the lithium-containing material can be obtained by referring to GB / T 30902-2014 method and tested using Thermo ICAP7400 inductively coupled plasma-optical emission spectrometer (ICP-OES). Alternatively, the metal element composition and ratio in the single crystal can be analyzed by transmission electron microscopy.

[0075] Lithium salts such as lithium oxalate, lithium carbonate, and lithium squarate have high theoretical capacity and good stability, making them suitable for addition to positive electrode plates as lithium supplements to provide active lithium. During the formation phase, they decompose to release active lithium and generate gas, which compensates for the irreversible consumption of active lithium by the battery's negative electrode, thereby increasing the battery's capacity. The generated gas is discharged during formation and does not affect battery performance. However, these lithium salts have high delithiation potentials. Delithiation at high potentials not only makes it difficult to fully realize their lithium supplementation efficiency, but also makes the plate susceptible to side reactions with the electrolyte at high potentials, deteriorating the battery's long-term cycling stability.

[0076] The lithium-containing material in the embodiment of the present application can more efficiently exert the M element's ability to regulate electrons, enhance the electrochemical reaction activity of the lithium-containing material, reduce its decomposition potential, improve the lithium replenishment effect of the lithium-containing material within the voltage window of the secondary battery, and improve the cycle stability of the battery.

[0077] Compared with adding a catalyst and a lithium replenisher to the positive electrode at the same time, this lithium-containing material achieves uniform mixing of the catalyst and the lithium replenisher at the atomic level, which can more effectively reduce the decomposition potential of the lithium-containing material and enhance the improvement effect of the battery cycle stability.

[0078] In some embodiments, 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.

[0079] In some embodiments, b is 0.01, 0.04, 0.07, 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, or any value therebetween.

[0080] In some embodiments, M comprises one or more of nickel, cobalt, manganese, iron, sodium, potassium, vanadium, titanium, copper, tungsten, zirconium, and molybdenum.

[0081] In some embodiments, M comprises one or more of nickel, cobalt, manganese, iron, sodium, and potassium.

[0082] In some embodiments, 1.6≤a<2, 0.01≤b≤0.1.

[0083] 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.

[0084] In some embodiments, the lithium-containing material is a eutectic material of a lithium salt and a catalyst salt, wherein the lithium salt and the catalyst salt have the same anion Y, and the cation of the catalyst salt includes an M element.

[0085] A eutectic is a substance in which a trace amount of a component is incorporated into a solid phase crystal that is otherwise soluble. In some embodiments, the eutectic is a substitutional solid solution. A substitutional solid solution is a substance formed when ions, molecules, or small lattice units of a trace amount of a substance replace corresponding ions, molecules, or small lattice units in the crystal lattice of the major substance.

[0086] 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.

[0087] In some embodiments, the lithium-containing material is spherical or spherical-like.

[0088] The surface morphology of the lithium-containing material is spherical or quasi-spherical, as shown in Figure 1. Spherical or quasi-spherical lithium-supplementing materials are easy to form a close stack with the active material in the electrode, which is beneficial to maintain and improve the compaction density of the electrode.

[0089] In some embodiments, the lithium-containing material is a hollow particle having a cavity inside the shell.

[0090] Lithium-containing material is added to the electrode, and the electrode is cut perpendicularly to the large surface of the electrode using an argon ion beam. The cross-section of the electrode is observed using a scanning electron microscope, and a cavity can be seen inside the lithium-containing material, as shown in Figure 2.

[0091] As the lithium-containing material continues to decompose and release lithium ions, the volume of the lithium-containing material continues to shrink, and gaps appear between it and the rest 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 "islands" in the positive electrode sheet, making it difficult to improve the battery's cycle stability. The hollow granular lithium-containing material provided in the embodiments 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 sheet can effectively improve the cycle stability of the secondary battery.

[0092] In some embodiments, the volume distribution particle size Dv50 of the lithium-containing material satisfies: 0.1 μm≤Dv50≤10 μm.

[0093] In some embodiments, the volume distribution particle size Dv50 of the lithium-containing material satisfies: 1 μm≤Dv50≤10 μm.

[0094] As used herein, the term "Dv50" refers to the particle size corresponding to the cumulative volume distribution number of particles reaching 50% in a particle size distribution curve.

[0095] In the present application, Dv50 can be tested by methods known in the art. As an example, referring to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, it is measured using a Mastersizer 2000E laser particle size analyzer produced by Malvern Instruments Ltd., UK.

[0096] In some embodiments, the volume distribution particle size Dv50 of the lithium-containing material is 0.1 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value therebetween.

[0097] 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.

[0098] In some embodiments, 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.

[0099] In the present application, the ratio of the shell wall thickness of the hollow particles to the diameter of the hollow particles can be measured using a scanning electron microscope. The electrode is cut perpendicularly to the large surface of the positive electrode 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 using a scanning electron microscope. The longest distance of the hollow particle is measured in five directions, and the average value is taken as the diameter of the hollow particle; the shell wall thickness of the hollow particle is measured at 5 random locations on the cross section of the hollow particle, and the average value of the 5 measurement results is taken as the shell wall thickness of the hollow particle. 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 shell wall thickness of the hollow particle to the diameter ratio s of the hollow particle.

[0100] In some embodiments, 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.

[0101] 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.

[0102] In some embodiments, the lithium-containing material further includes a conductive material.

[0103] In some embodiments, the conductive material comprises a conductive carbon material.

[0104] In some embodiments, the conductive material includes at least one of graphene, carbon nanotubes, carbon nanofibers, acetylene black, super carbon black (Super P), and Ketjen black.

[0105] In some embodiments, the conductive material comprises carbon nanotubes.

[0106] Including a conductive material in the lithium-containing material can enhance the conductivity of the lithium-containing material, further reduce the decomposition potential of the lithium-containing material, and improve the decomposition efficiency of the lithium-containing material, which is beneficial to further improve the cycle stability of the secondary battery.

[0107] In some embodiments, the conductive material accounts for 1% to 10% by weight based on the total weight of the lithium-containing material.

[0108] In some embodiments, the conductive material accounts for 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% by weight, or any value therebetween, based on the total weight of the lithium-containing material.

[0109] In some embodiments, the conductive material accounts for 1% to 5% by weight based on the total weight of the lithium-containing material.

[0110] When the mass proportion of the conductive material is within an appropriate range, 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.

[0111] In some embodiments, the decomposition voltage of the lithium-containing material is 3.8V-4.5V, optionally 4.0V-4.48V.

[0112] In some embodiments, the decomposition voltage of the lithium-containing material may be 3.8 V, 3.85 V, 3.9 V, 3.95 V, 4.0 V, 4.05 V, 4.1 V, 4.15 V, 4.2 V, 4.25 V, 4.3 V, 4.35 V, 4.4 V, 4.45 V, 4.48 V, 4.5 V, or any range therebetween.

[0113] The decomposition voltage of a lithium-containing material can be determined by any known method in the art. For example, a lithium-containing material is added as an additive to a positive electrode plate, assembled into a lithium battery, and the capacity (Q) of the lithium battery in the 3.65V-4.5V range during initial charging is measured. A graph is plotted with the voltage data V as the horizontal axis and the corresponding dQ / dV as the vertical axis to obtain a dQ / dV curve that varies with V. The voltage corresponding to the peak of the curve in the 3.65V-4.5V range is the decomposition voltage of the lithium-containing material. To reduce polarization and improve test accuracy, charging is performed at a low rate, such as 0.05C, in the 3.65V-4.5V range.

[0114] A second aspect of the present application provides an application of a lithium-containing material as a lithium supplement in a secondary battery.

[0115] The third aspect of the present application provides a method for preparing a lithium-containing material, the method comprising: preparing the lithium-containing material by crystallization, wherein the lithium-containing material comprises a component of the general formula I,

[0116] Li a M b Y Formula I

[0117] Wherein, 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.

[0118] Herein, crystallization refers to the process by which a solute precipitates to form crystals.

[0119] In some embodiments, during the crystallization process, trace ions, molecules, or small lattice units of a trace substance replace the constant substance on the precipitate lattice and enter the interior of the lattice, transferring from the liquid phase to the solid phase to form a eutectic. The lithium-containing material of the present application is prepared by a crystallization method. During the crystallization process, the M element enters the lithium-containing material, allowing the M element and the lithium element to achieve uniform mixing at the atomic level, forming a solid solution phase effect, thereby effectively enhancing the catalytic ability of the M element. Compared to the physical mixing of the catalyst and the lithium supplement, this can more effectively reduce the decomposition potential of the lithium-containing material, which is beneficial for further improving the cycle stability of the battery.

[0120] In some embodiments, the preparation method specifically includes: crystallizing a mixed solution to prepare a lithium-containing material, wherein 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.

[0121] Catalyst salts and lithium salts with the same anions may have similar crystal structures. During the crystallization process, the M element of the catalyst salt can easily enter the lithium salt 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.

[0122] In some embodiments, the mixed liquid further includes a conductive material. Optionally, the conductive material includes a conductive carbon material.

[0123] Adding conductive materials during the preparation of lithium-containing materials is beneficial to forming lithium-containing materials with a conductive network, enhancing the conductive properties of lithium-containing materials, reducing the decomposition voltage of lithium-containing materials, and improving the cycle stability of batteries.

[0124] In some embodiments, the crystallization is performed using spray drying.

[0125] In this article, "spray drying" refers to a granulation method in which a slurry or solution is sprayed into a granulation tower and dried under the action of a spray of hot air to produce spherical granules. This method produces particles with high precision and uniform size.

[0126] Spray drying crystallization allows the particle size of the lithium-containing material to be adjusted by adjusting process conditions such as spray pressure, inlet and outlet air temperatures, thereby improving the controllability of product preparation. Furthermore, spray drying is low-cost and suitable for industrial production.

[0127] 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.

[0128] In some embodiments, the inlet air temperature of the spray drying is 170°C-230°C, and / or the outlet air temperature is 100°C-140°C.

[0129] In some embodiments, 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.

[0130] In some embodiments, the outlet temperature of the spray drying can be 100° C., 110° C., 120° C., 130° C., 140° C., or any range therebetween. The above conditions are conducive to achieving instant drying and are beneficial to the preparation of lithium-containing materials.

[0131] In some embodiments, 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.

[0132] In some embodiments, a complexing agent is included in the solution comprising the catalyst salt.

[0133] In some embodiments, 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.

[0134] The complexing agent can complex with the cations in the catalyst salt to improve the solid solution effect of the M element in the lithium salt. The secondary battery, battery module, battery pack and electrical device of the present application are described below with appropriate reference to the accompanying drawings.

[0135] In one embodiment of the present application, a secondary battery is provided.

[0136] Typically, a secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0137] [Positive electrode]

[0138] The positive electrode sheet includes a positive electrode current collector and a positive electrode film disposed on at least one surface of the positive electrode current collector. As an example, the positive electrode current collector has two surfaces that are opposite to each other in its thickness direction, and the positive electrode film is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0139] In some embodiments, 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.

[0140] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 0.5% to 20%.

[0141] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% or any value therebetween.

[0142] In some embodiments, based on the total mass of the positive electrode film layer, the mass proportion of the lithium supplement agent is 1% to 10%.

[0143] When 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.

[0144] In some embodiments, the cathode film layer includes a cathode active material.

[0145] In some embodiments, the positive electrode active material includes lithium-containing phosphates, lithium transition metal oxides, and modified materials thereof.

[0146] The positive electrode active material may be a positive electrode active material for a battery that is well known in the art. As an example, the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), 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 O2 (also referred to as NCM 333 ), LiNi 0.5 Co0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0147] In some embodiments, the positive electrode active material includes a lithium-containing phosphate.

[0148] The voltage window upper limit of lithium-containing phosphates is relatively low, making conventional lithium replenishers with higher decomposition voltages unsuitable for use in electrodes containing lithium-containing phosphates. The lithium-containing material of this application has a low decomposition voltage and can decompose and replenish active lithium within the voltage window of lithium-containing phosphates, thereby improving the battery's cycling stability and meeting the cycling stability and lifespan requirements of batteries using lithium-containing phosphates as positive electrode active materials.

[0149] In some embodiments, the average particle size of the lithium-containing material is greater than the average particle size of the positive electrode active material. In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. 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.).

[0150] In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0151] In some embodiments, the positive electrode film layer may further include a conductive agent. For example, 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.

[0152] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, lithium supplement, 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.

[0153] [Negative electrode]

[0154] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0155] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0156] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0157] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxides, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0158] In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0159] In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0160] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0161] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0162] [Electrolytes]

[0163] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0164] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0165] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0166] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0167] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0168] [Isolation film]

[0169] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0170] In some embodiments, the material of the separator 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 particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0171] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0172] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0173] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0174] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. For example, FIG5 shows a secondary battery 5 having a square structure as an example.

[0175] In some embodiments, referring to Figure 6, the outer packaging may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The 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.

[0176] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0177] Figure 7 shows an example battery module 4. Referring to Figure 7 , within the battery module 4, multiple secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple secondary batteries 5 may be secured together using fasteners.

[0178] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0179] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0180] Figures 8 and 9 illustrate an example battery pack 1. Referring to Figures 8 and 9 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0181] In addition, 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 for the electric device, and can also be used as an energy storage unit for the electric device. The electric 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 is not limited thereto.

[0182] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0183] Figure 10 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0184] Another example device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is generally required to be lightweight and thin, and may use a secondary battery as a power source.

[0185] Example

[0186] Below, the embodiment of the present application is described. The embodiment described below is exemplary and is only used to explain the present application, and is not to be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0187] Preparation method

[0188] Example 1

[0189] (1) Preparation of lithium supplements

[0190] At 25°C, 0.03 mol of nickel oxalate was dissolved in 100 g of deionized water, 3.5 mL of ammonia water was added, the mixture was stirred for 20 min and then ultrasonically dispersed for 20 min to obtain a solution containing a catalyst salt; 1 mol of lithium oxalate was dissolved in 300 g of deionized water, the mixture was stirred for 20 min and then ultrasonically dispersed for 20 min to obtain a solution containing a lithium salt; a carbon nanotube (CNT) slurry with a mass concentration of 0.9% was added to 500 mL of deionized water and stirred for 60 min to obtain a solution containing a conductive material; the solution containing the catalyst salt was first added to the solution containing the lithium salt, stirred for 20 min to obtain a first mixed solution, and then the first mixed solution was added to the solution containing the conductive material to obtain a second mixed solution, stirred for 1 h and then ultrasonically dispersed for 1 h, and finally the obtained solution was spray dried, the inlet air temperature of the spray drying was 200°C, and the outlet air temperature of the spray drying was 120°C. During the spray drying process, a cocrystallization reaction occurred to obtain a lithium oxalate-nickel oxalate eutectic material with the general formula of Li 1.94 Ni 0.03 The invention relates to a lithium-containing material comprising C2O4, a Dv50 of 3 μm, a shell wall thickness and a hollow particle diameter ratio s of 20:100, and a carbon nanotube mass content of 3% in the lithium-containing material.

[0191] (2) Preparation of positive electrode sheet

[0192] The lithium-containing material, lithium iron phosphate material, conductive carbon black, and binder polyvinylidene fluoride (PVDF) were mixed thoroughly in an N-methylpyrrolidone (NMP) solvent system at a weight ratio of 5:92:1:2 to obtain a positive electrode slurry. The slurry was then evenly coated onto the positive electrode current collector. The cathode sheets were then dried, cold-pressed, and slit. The Dv50 of the lithium iron phosphate was 1.5 μm.

[0193] (3) Preparation of negative electrode sheet

[0194] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a weight ratio of 96.2:0.8:0.8:1.2, and mixed evenly to prepare a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0195] (4) Preparation of electrolyte

[0196] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7, 12.5% ​​LiPF6 lithium salt was added and dissolved in the organic solvent, and stirred uniformly to obtain an electrolyte.

[0197] (5) Isolation film

[0198] Polypropylene film is used as the isolation film.

[0199] (6) Preparation of lithium-ion batteries

[0200] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrodes to act as an insulator. The bare cell is then wound to obtain the bare cell. The tabs are welded to the bare cell and placed in an aluminum shell. The bare cell is then 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 left to stand, hot-pressed, and cold-pressed. It is then subjected to a formation treatment, first charging at a constant current of 0.1C for 10 minutes, then charging at a constant current of 1 / 3C to 3.65V, 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. After shaping and capacity testing, the lithium-ion battery product is obtained.

[0201] 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.

[0202] The preparation method of Example 10 is substantially the same as that of Example 1, except that no CNT is added during the preparation of the lithium supplement.

[0203] Comparative Example 1

[0204] 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.

[0205] Comparative Example 2

[0206] The preparation method of the battery in Comparative Example 2 is basically the same as that in Example 1, except that the preparation method of the lithium supplement agent in Comparative Example 2 is:

[0207] 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.

[0208] Performance Testing

[0209] (1) XRD detection

[0210] An X-ray diffractometer is used to detect lithium-containing materials and raw materials to obtain X-ray diffraction patterns.

[0211] (2) Lithium supplement decomposition voltage test

[0212] 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 at a constant current of 1 / 3C to 3.65V, then at a constant voltage of 3.65V to 0.05C, left for 5 minutes, and finally 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, a 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.

[0213] (3) Secondary battery cycle capacity retention test

[0214] At 60°C, 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 a constant current of 1 / 3C. The resulting capacity was recorded as the initial capacity C0. Repeat the above steps for the same battery and simultaneously record the discharge capacity Cn of the battery after the nth cycle. The battery capacity retention rate after each cycle is Pn = Cn / C0*100%. In this test process, the first cycle corresponds to n = 1, the second cycle corresponds to n = 2, ... the 100th cycle corresponds to n = 100. After 100 cycles under the above test conditions, the cycle capacity retention rate, i.e. the value of P100, is measured.

[0215] Result Analysis

[0216] Batteries of various examples and comparative examples were prepared according to the above methods, and various performance parameters were measured. The results are shown in Table 1.

[0217] Table 1

[0218] Figure 11 is an X-ray diffraction pattern of the lithium-containing material of the lithium supplement of Example 1 of the present application. As can be seen from the figure, the X-ray diffraction peaks of the lithium-containing material are essentially consistent with those of lithium oxalate, without exhibiting obvious peaks characteristic of nickel oxalate. This indicates that the lithium-containing material has the lattice structure of lithium oxalate and that nickel is solid-dissolved in the lithium oxalate.

[0219] Figure 3 shows the constant current charging curve of the battery of Example 1 of the present application at a rate of 0.1C; Figure 4 shows the constant current charging curve of the battery of Comparative Example 1 of the present application at a rate of 0.1C. As can be seen from the figures, the lithium-containing material provided by the present application can significantly increase the capacity of the battery.

[0220] The positive electrode sheets of Examples 1-10 all include Li a M bIn the lithium-containing material Y, M comprises one or more transition metal elements and alkali metal elements other than lithium; Y comprises one or more oxalate, squarate, and carbonate; and 1≤a≤2, 0.01≤b≤0.2. As can be seen from the comparison of the examples and comparative examples, the lithium-containing material of the present application has a lower decomposition voltage and can effectively improve the cycle life of the battery.

[0221] As can be seen from Examples 1-3, 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. When the anion of the lithium-containing material is squarate, the decomposition voltage of the lithium-containing material can be further reduced, thereby improving the cycle stability of the battery.

[0222] It can be seen from Examples 1 and 4-5 that when the metal ions of the catalyst salt are nickel, iron, and sodium, the lithium-containing material has a low decomposition voltage and the battery has good cycle stability. 1.94 Ni 0.03 C2O4 relative to Li 1.94 Fe 0.03 C2O4 and Li 1.94 Na 0.06 C2O4 has a lower decomposition voltage and improves the cycle stability of the battery.

[0223] From the comparison between Example 1 and Example 10, it can be seen that including a conductive material in the lithium-containing material can further reduce the decomposition voltage of the lithium-containing material and improve the cycle stability of the battery.

[0224] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium-containing material, characterized in that, The lithium-containing material includes a component having a general formula such as Formula I, Li a M b Y Formula I Among them, 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.

2. The lithium-containing material according to claim 1, wherein 1.6 ≤ a < 2, 0.01 ≤ b ≤ 0.

1.

3. The lithium-containing material according to claim 1 or 2, wherein 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, and the cation of the catalyst salt includes element M.

4. The lithium-containing material according to any one of claims 1 to 3, wherein the lithium-containing material is spherical or quasi-spherical.

5. The lithium-containing material according to any one of claims 1 to 4, wherein the lithium-containing material is a hollow particle having a cavity inside a shell.

6. The lithium-containing material according to any one of claims 1 to 5, wherein the volume distribution particle size Dv50 of the lithium-containing material satisfies: 0.1 μm ≤ Dv50 ≤ 10 μm, optionally, 1 μm ≤ Dv50 ≤ 10 μm.

7. The lithium-containing material according to claim 5 or 6, wherein the ratio s of the wall thickness of the shell of the hollow particle to the diameter of the hollow particle satisfies 10:100 ≤ s ≤ 30:

100.

8. The lithium-containing material according to any one of claims 1 to 7, wherein the lithium-containing material further includes a conductive material, optionally, the conductive material includes at least one of graphene, carbon nanotubes, carbon nanofibers, acetylene black, super carbon black, and Ketjen black.

9. The lithium-containing material according to claim 8, wherein based on the total mass of the lithium-containing material, the mass ratio of the conductive material is 1% - 10%, optionally 1% - 5%.

10. The lithium-containing material according to any one of claims 1 to 9, wherein the decomposition voltage of the lithium-containing material is 3.8V - 4.5V, optionally 4.0V - 4.48V.

11. Application of the lithium-containing material according to any one of claims 1 to 10 as a lithium supplement agent in a secondary battery.

12. A method for preparing a lithium-containing material, characterized in that, The preparation method includes: preparing a lithium-containing material by crystallization, the lithium-containing material includes a component with a general formula as formula I, Li a M b Formula I of Y wherein, 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.

13. The preparation method according to claim 12, characterized in that, The specific preparation method includes: crystallizing a mixed solution to prepare a lithium-containing 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 element M.

14. The preparation method according to claim 12 or 13, characterized in that, The mixed solution further includes a conductive material, optionally, the conductive material includes a conductive carbon material.

15. The preparation method according to any one of claims 12 to 14, characterized in that, The crystallization is carried out by spray drying.

16. The preparation method according to claim 15, wherein The inlet air temperature of the spray drying is 170°C - 230°C, and / or the outlet air temperature is 100°C - 140°C.

17. The preparation method according to any one of claims 12 to 16, characterized in that, 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; After mixing the first mixed solution with the solution containing the conductive material, a second mixed solution is obtained; Spray drying the second mixed solution to prepare the lithium-containing material.

18. A positive electrode sheet, characterized in that, The positive electrode sheet includes a current collector and a positive electrode film layer provided on at least one side of the current collector. The positive electrode film layer includes a lithium supplement agent, and the lithium supplement agent includes the lithium-containing material according to any one of claims 1 to 9 or the lithium-containing material prepared by the preparation method according to any one of claims 11 to 17.

19. The positive electrode sheet according to claim 18, characterized in that, Based on the total mass of the positive electrode film layer, the mass ratio of the lithium supplement agent is 0.5% - 20%, and optionally 1% - 10%.

20. The positive electrode sheet according to claim 18 or 19, characterized in that, The positive electrode film layer includes a positive electrode active material; optionally, the positive electrode active material includes lithium-containing phosphate, lithium transition metal oxide, and their respective modified materials; further optionally, the positive electrode active material includes lithium-containing phosphate and its modified materials.

21. The positive electrode sheet according to claim 20, wherein The average particle size of the lithium-containing material is larger than the average particle size of the positive electrode active material.

22. A secondary battery, characterized in that, It includes the positive electrode sheet according to any one of claims 18 to 21.

23. An electrical device, characterized in that, It includes the secondary battery according to claim 22.

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