Lithium-containing composite material and preparation method and application thereof

Abstract

The invention discloses a lithium-containing composite material as well as a preparation method and application thereof. The lithium-containing composite material comprises a core as well as a metal doping layer, a metal coating layer and a carbon coating layer which are sequentially arranged outside the core, the core contains a lithium-containing compound; the metal doped layer contains a metal doped compound, and the metal doped compound is formed by doping a metal element into a lithium-containing compound; the metal coating layer contains a metal material; metal elements in the metal doped compound and metal elements in the metal material independently comprise at least one of Al, Ti or Mg. The metal doping layer and the metal coating layer are arranged outside the core, so that residual alkali on the surface of the material is reduced, and the surface structure of the material is stabilized; the carbon coating layer is arranged, so that the electronic conductivity of the material is improved; through specific structural design, the lithium-containing composite material is low in residual alkali on the surface and high in ion and electron transmission rate, and can be used for preparing a positive electrode lithium supplement agent and a lithium ion battery with excellent performance.

Description

Technical Field

[0001] This invention belongs to the field of functional materials and energy storage technology, and particularly relates to a lithium-containing composite material, its preparation method and application. Background Technology

[0002] With the continuous development of lithium-ion battery technology, its application in consumer electronics, electric vehicles, and energy storage systems is becoming increasingly widespread. However, lithium-ion batteries suffer from irreversible capacity loss during charge and discharge, which limits the actual energy density and cycle life of the battery. Positive electrode lithium replenishment agents, as an effective solution, can compensate for the lithium-ion loss during the first charge and discharge process, improving the overall performance of the battery. Li5FeO4, as a typical positive electrode lithium replenishment additive, has been widely used in the lithium battery field, but it still suffers from problems such as high residual alkali, air sensitivity, large particle size, gas generation, and difficulty in fully utilizing its capacity, which greatly limits its widespread application in high-performance lithium-ion batteries.

[0003] Existing technologies increase the electron and ion transport rates of lithium-rich additives by constructing a conductive carbon layer and a transition metal oxide layer on the surface of the material and controlling the particle size. While this multi-layer coating can increase the ion and electron transport rates, the preparation method is complex. It requires first preparing a carbon-coated iron oxide layer, then wet mixing to prepare a carbon-coated Li5FeO4, and finally mixing it with a transition metal ion salt solution and an ammonium hydroxide solution, followed by high-temperature sintering to obtain the additive. Notably, during the liquid-phase wet coating process, this lithium-rich, strongly alkaline material is prone to Li-oxidation. + The release of metal leads to the destruction of the material structure; in addition, using ammonium hydroxide to adjust the pH in the salt solution to promote metal precipitation makes it difficult to ensure that the metal precipitates and coats the surface of the lithium replenishing agent material, ultimately making it difficult to achieve effective coating under liquid phase conditions.

[0004] Another existing technology involves coating the material surface with a layer of zirconium dioxide to suppress side reactions and reduce residual alkali effects. While this method can isolate the material surface from side reactions with the electrolyte to some extent, the simple zirconium oxide coating is insufficient to address the slow ion and electron transport rates of the material itself. Furthermore, this simple solid-phase mixing method makes it difficult to form a uniform coating layer on the material surface; the actual distribution of the coating agent is "island-like," making it difficult to achieve an effective isolation effect. Summary of the Invention

[0005] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a lithium-containing composite material having a uniform coating layer, low surface alkali residue, and high ion and electron transport rates.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned lithium-containing composite material.

[0007] The third objective of this invention is to provide a positive electrode lithium replenishing agent.

[0008] The fourth objective of this invention is to provide a lithium-ion battery.

[0009] The fifth objective of this invention is to provide a vehicle.

[0010] The sixth objective of this invention is to provide an electrical device.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a lithium-containing composite material comprising a core and a metal-doped layer, a metal cladding layer, and a carbon cladding layer sequentially disposed outside the core; the core contains a lithium-containing compound; the metal-doped layer contains a metal-doped compound formed by doping a metal element into the lithium-containing compound; the metal cladding layer contains a metal material; and the metal element in the metal-doped compound and the metal element in the metal material each independently include at least one of Al, Ti, or Mg.

[0012] The lithium-containing composite material according to the first aspect of the present invention has at least the following beneficial effects: This invention reduces residual alkali on the material surface and stabilizes the material surface structure by setting a metal doping layer and a metal coating layer on the outside of the core; while setting a carbon coating layer improves the electronic conductivity of the material; through specific structural design, the resulting lithium-containing composite material has high stability to air and water, good processing performance, and high ion and electron transport rates.

[0013] In some embodiments of the present invention, the average particle size of the core is 5~20 μm.

[0014] In some embodiments of the present invention, the average thickness of the metal doped layer is 1~8 μm.

[0015] In some embodiments of the present invention, the average thickness of the metal cladding layer is 10~30 nm.

[0016] In some embodiments of the present invention, the average thickness of the carbon coating layer is 20-40 nm.

[0017] The lithium-containing composite material of the present invention has good coating uniformity in its metal coating layer and carbon coating layer, and its thickness is maintained within a certain range. Compared with the "island-like" coating of the coating agent in the prior art, the lithium-containing composite material of the present invention has better structural stability.

[0018] In some embodiments of the present invention, the lithium-containing compound includes at least one of Li5FeO4, Li5Fe5O8, Li2NiO2, Li6CoO4, Li4V3O8, Li2MoO3, or lithium-rich manganese-based materials.

[0019] In some embodiments of the present invention, the metal elements in the metal doping compound and the metal elements in the metal material both include Al and Ti.

[0020] Through the synergistic effect of aluminum and titanium at the atomic, structural, and interface levels, better doping and coating effects can be achieved, resulting in lithium-containing composite materials with superior performance.

[0021] In some embodiments of the present invention, the atomic ratio of Al to Ti in the metal-doped compound is 0.1 to 6; the atomic ratio of Al to Ti in the metal material is 0.1 to 6.

[0022] A second aspect of the present invention provides a method for preparing a lithium-containing composite material, comprising the following steps: mixing a lithium-containing compound with a solution containing an organometallic salt, performing a coating treatment to obtain a coated material; and performing a sintering treatment on the coated material to obtain the lithium-containing composite material as described in the first aspect of the present invention; wherein the metal cation in the organometallic salt includes at least one of aluminum ions, titanium ions, or magnesium ions.

[0023] The method for preparing lithium-containing composite materials according to the second aspect of the present invention has at least the following beneficial effects: This invention employs a liquid-phase coating method, using a solution containing organometallic salts as the coating material. The organometallic salts can rapidly form a uniform coating on the surface of lithium-containing compounds through electrostatic attraction or adsorption precipitation. Specifically, due to electrostatic attraction or residual alkaline substances on the surface of the lithium-containing compound, aluminum and / or titanium ions in the organometallic salts rapidly aggregate and precipitate on the surface of the lithium-containing compound particles, while the organic chains are dispersed in the outer layer. Subsequently, through sintering, the metal ions bound to the surface of the lithium-containing compound can be doped into the micro-surface of the lithium-containing compound, thereby forming a shallow metal-doped layer and an outer metal coating layer on the surface of the lithium-containing compound. The outer organic chains carbonize at high temperature, forming a uniform carbon coating layer, thus enhancing the electron transport performance of the material. Furthermore, the preparation method of this invention is simple and easy to implement, and can form an effective doped layer and coating layer on the material surface.

[0024] In some embodiments of the present invention, the organic anion in the organometallic salt includes at least one of polyacrylate, polystyrene-based anion, cellulose-based anion, chitosan-based anion, C1-C10 alkylcarboxylate, C1-C10 alkoxy anion, or C1-C10 alkylamine anion.

[0025] In some embodiments of the present invention, the mass concentration of the solution containing the organometallic salt is 0.05~50%.

[0026] In some embodiments of the present invention, the mass ratio of the lithium-containing compound to the solution containing the organometallic salt is (0.05~5):1.

[0027] In some embodiments of the present invention, the sintering process includes sequentially performing a first-stage sintering and a second-stage sintering; the sintering temperature of the first-stage sintering is 200~400℃; and the sintering temperature of the second-stage sintering is 380~820℃.

[0028] By adjusting the sintering temperature, the surface coating or micro-doping effect of the material can be adjusted. Increasing the sintering temperature will promote the migration of metal ions to the core phase and increase the thickness of the metal doped layer. Using a suitable sintering temperature can achieve a more suitable doping and coating effect, thereby enabling the material to obtain better conductivity and higher initial charge specific capacity.

[0029] In some embodiments of the present invention, the holding time for the first sintering stage is 1 to 4 hours.

[0030] In some embodiments of the present invention, the holding time for the two-stage sintering is 3 to 18 hours.

[0031] By adjusting the sintering time, the surface coating or micro-doping effect of the material can also be adjusted. Extending the sintering time will promote the migration of metal ions to the core phase and increase the thickness of the metal doped layer. Using an appropriate sintering time can also achieve a more suitable doping and coating effect, thereby enabling the material to obtain better conductivity and higher first charge specific capacity.

[0032] In some embodiments of the present invention, the heating rate of the sintering section is 1~8℃ / min.

[0033] In some embodiments of the present invention, the heating rate of the two-stage sintering is 1~8℃ / min.

[0034] A third aspect of the present invention provides a positive electrode lithium replenishing agent, which includes the lithium-containing composite material described in the first aspect of the present invention, or the lithium-containing composite material prepared by the preparation method described in the second aspect of the present invention.

[0035] The positive electrode lithium replenishing agent according to the third aspect of the present invention has at least the following beneficial effects: The lithium-containing composite material involved in this invention is used to prepare a positive electrode lithium supplement, which has the advantages of uniform surface coating, low residual alkali content, good stability in air and water, good processing performance, and high ion and electron transport rate.

[0036] A fourth aspect of the present invention provides a lithium-ion battery, wherein the positive electrode of the lithium-ion battery contains a positive electrode lithium replenishing agent as described in the third aspect of the present invention.

[0037] The lithium-ion battery according to the fourth aspect of the present invention has at least the following beneficial effects: The lithium-ion battery made using the positive electrode lithium replenishing agent of this invention can achieve a good lithium replenishment effect, effectively replenish the lithium-ion loss during the first charge and discharge process, improve the overall performance of the battery, and in particular enable the lithium-ion battery to have a high first charge specific capacity.

[0038] A fifth aspect of the present invention provides a vehicle comprising the lithium-ion battery described in the fourth aspect of the present invention.

[0039] A sixth aspect of the present invention provides an electrical device comprising the lithium-ion battery described in the fourth aspect of the present invention. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the lithium-containing composite material in Example 1 before and after secondary sintering.

[0041] Figure 2 The images shown are scanning electron microscope (SEM) images of Example 1 and Comparative Examples 1-2.

[0042] Figure labels: 1-core, 2-metal doped layer, 3-metal coating layer, 4-carbon coating layer. Detailed Implementation

[0043] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The term "comprising" and other equivalent descriptive methods used in the specification and claims of this application are intended to cover a non-exclusive inclusion, which includes both the contents explicitly described in the specification and claims and steps or units that are not described in the specification and claims but are inherent in the product, method, or structure.

[0044] A first aspect of the present invention provides a lithium-containing composite material, the lithium-containing composite material comprising a core and a metal doping layer, a metal cladding layer and a carbon cladding layer sequentially disposed outside the core; the core contains a lithium-containing compound; the metal doping layer contains a metal doping compound, the metal doping compound being formed by doping a metal element into the lithium-containing compound; the metal cladding layer contains a metal material; the metal element in the metal doping compound and the metal element in the metal material each independently include at least one of Al, Ti or Mg.

[0045] This invention reduces residual alkali on the material surface and stabilizes the material surface structure by setting a metal doping layer and a metal coating layer on the outside of the core; while setting a carbon coating layer improves the electronic conductivity of the material; through specific structural design, the resulting lithium-containing composite material has high stability to air and water, good processing performance, and high ion and electron transport rates.

[0046] In some embodiments of the present invention, both the metal elements in the metal doping compound and the metal elements in the metal material include Al and Ti. Through the synergistic effect of aluminum and titanium at the atomic, structural, and interface levels, better doping and coating effects can be achieved, resulting in lithium-containing composite materials with superior performance.

[0047] In some embodiments of the present invention, the average particle size of the core is 5 to 20 μm; non-limiting specific examples include any value of 5 μm, 8 μm, 10 μm, 12 μm, 15 μm or 20 μm or a range between any two; in some embodiments of the present invention, the average particle size of the core is 8 to 15 μm.

[0048] In some embodiments of the present invention, the average thickness of the metal-doped layer is 1 to 8 μm; non-limiting specific examples include any value or a range between 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8 μm; in some embodiments of the present invention, the average thickness of the metal-doped layer is 2 to 5 μm.

[0049] In some embodiments of the present invention, the average thickness of the metal cladding layer is 10-30 nm; non-limiting specific examples include any value or a range between 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm or 30 nm; in some embodiments of the present invention, the average thickness of the metal cladding layer is 15-25 nm.

[0050] In some embodiments of the present invention, the average thickness of the carbon coating layer is 20-40 nm; non-limiting specific examples include any value or a range between 20 nm, 22 nm, 25 nm, 28 nm, 30 nm, 32 nm, 35 nm, 38 nm or 40 nm; in some embodiments of the present invention, the average thickness of the carbon coating layer is 25-35 nm.

[0051] The lithium-containing composite material of the present invention has good coating uniformity in its metal coating layer and carbon coating layer, and its thickness is maintained within a certain range. Compared with the "island-like" coating of the coating agent in the prior art, the lithium-containing composite material of the present invention has better structural stability.

[0052] In some embodiments of the present invention, the lithium-containing compound includes at least one of Li5FeO4, Li5Fe5O8, Li2NiO2, Li6CoO4, Li4V3O8, Li2MoO3, or lithium-rich manganese-based material (LRM); the lithium-rich manganese-based material (LRM) is a composite material based on Li2MnO3, with the chemical formula xLi2MnO3·(1-x)LiMO2, where M is at least one of Ni, Co, and Mn, and 0 < x < 1; specifically, it can be 0.3Li2MnO3·0.7LiNi 0.5 Mn 0.5 O2, 0.7Li2MnO3·0.3LiNi 0.5 Co 0.5 O2, etc.; In some specific embodiments of the present invention, the lithium-containing compound includes Li5FeO4, Li5Fe5O8 or a combination thereof; In some examples of the present invention, the lithium-containing compound is selected from Li5FeO4.

[0053] In some embodiments of the present invention, the lithium-containing compound is prepared by a method comprising the following steps: mixing a lithium source and a transition metal source and performing solid-state sintering to obtain a lithium-containing compound; the transition metal source includes at least one of an iron source, a nickel source, a cobalt source, a vanadium source, a molybdenum source, or a manganese source.

[0054] In some embodiments of the present invention, in the method for preparing the lithium-containing compound, the ratio of the lithium source to the transition metal source is determined according to the composition of the lithium-containing compound; for example, when the lithium-containing compound is selected from Li5FeO4, the transition metal source is an iron source, and the molar ratio of the lithium source to the transition metal source is (5~5.1):1, specifically any value or a range between 5:1, 5.02:1, 5.05:1, 5.08:1, or 5.1:1. Further, the iron source can be at least one of iron oxide, ferric oxalate, ferric chloride, or ferric sulfate.

[0055] In some embodiments of the present invention, in the method for preparing lithium-containing compounds, the lithium source includes at least one of lithium carbonate, lithium hydroxide, or lithium oxide.

[0056] In some embodiments of the present invention, in the method for preparing lithium-containing compounds, the method of mixing the lithium source and the transition metal source is selected from ball milling; specifically, it can be wet ball milling; in some specific embodiments of the present invention, the ball milling time is 2 to 8 hours; non-limiting specific examples include any value of 2 hours, 4 hours, 6 hours or 8 hours or any range between two.

[0057] In some embodiments of the present invention, in the method for preparing lithium-containing compounds, solid-state sintering is carried out in a protective gas atmosphere; in some specific embodiments of the present invention, the protective gas used for solid-state sintering includes at least one of nitrogen, argon or helium.

[0058] In some embodiments of the present invention, the solid-state sintering in the method for preparing the lithium-containing compound includes a first sintering, a second sintering, and a third sintering performed sequentially; the sintering temperature of the first sintering is 220~360℃; the sintering temperature of the second sintering is 450~620℃; and the sintering temperature of the third sintering is 720~950℃. Non-limiting specific examples include: the sintering temperature of the first sintering can be any value or a range between 220℃, 250℃, 300℃, 330℃, or 360℃; the sintering temperature of the second sintering can be any value or a range between 450℃, 500℃, 550℃, 600℃, or 620℃; and the sintering temperature of the third sintering can be any value or a range between 720℃, 750℃, 800℃, 850℃, 900℃, or 950℃. In some embodiments of the present invention, in the method for preparing lithium-containing compounds, the holding time for the first sintering is 2 to 6 hours; non-limiting specific examples include any value of 2 hours, 3 hours, 4 hours, 5 hours or 6 hours or a range between any two.

[0059] In some embodiments of the present invention, in the method for preparing lithium-containing compounds, the holding time for the second sintering is 4 to 10 hours; non-limiting specific examples include any value of 4 hours, 6 hours, 8 hours or 10 hours or a range between any two.

[0060] In some embodiments of the present invention, in the method for preparing lithium-containing compounds, the holding time of the third sintering is 12 to 36 hours; non-limiting specific examples include any value of 12 hours, 18 hours, 24 hours, 30 hours or 36 hours or a range between any two.

[0061] In some embodiments of the present invention, in the method for preparing the lithium-containing compound, the heating rate of the first sintering, the heating rate of the second sintering, and the heating rate of the third sintering are each independently 1~8 °C / min; non-limiting specific examples include each independently being any value or a range between any two of 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, or 8 °C / min; in some specific embodiments of the present invention, in the method for preparing the lithium-containing compound, the heating rate of the first sintering, the heating rate of the second sintering, and the heating rate of the third sintering are each independently 2~5 °C / min.

[0062] In some embodiments of the present invention, in the preparation method of lithium-containing compounds, cooling is performed after solid-state sintering; the cooling method may be furnace cooling.

[0063] In some embodiments of the present invention, both the metal elements in the metal doping compound and the metal elements in the metal material include Al and Ti. Through the synergistic effect of aluminum and titanium at the atomic, structural, and interface levels, better doping and coating effects can be achieved, resulting in lithium-containing composite materials with superior performance.

[0064] In some embodiments of the present invention, the atomic ratio of Al to Ti in the metal-doped compound is 0.1 to 6; non-limiting specific examples include any value or a range between any two of 0.1, 0.2, 0.25, 0.5, 1, 2, 3, 4, 5 or 6; in some specific embodiments of the present invention, the atomic ratio of Al to Ti in the metal-doped compound is 0.2 to 5; in some examples of the present invention, the atomic ratio of Al to Ti in the metal-doped compound is 0.25 to 4.

[0065] In some embodiments of the present invention, the atomic ratio of Al to Ti in the metallic material is 0.1 to 6; non-limiting specific examples include any value or a range between any two of 0.1, 0.2, 0.25, 0.5, 1, 2, 3, 4, 5 or 6; in some specific embodiments of the present invention, the atomic ratio of Al to Ti in the metallic material is 0.2 to 5; in some examples of the present invention, the atomic ratio of Al to Ti in the metallic material is 0.25 to 4.

[0066] In some embodiments of the present invention, the powder conductivity of the lithium-containing composite material is ≤15 Ω·cm; specifically, it can be 1~15 Ω·cm; for example, it can be any value or a range between any two of 1 Ω·cm, 2 Ω·cm, 3 Ω·cm, 5 Ω·cm, 7 Ω·cm, 8 Ω·cm, 10 Ω·cm, 12 Ω·cm or 15 Ω·cm; in some specific embodiments of the present invention, the powder conductivity of the lithium-containing composite material is 2~8 Ω·cm; in some examples of the present invention, the powder conductivity of the lithium-containing composite material is 3~7 Ω·cm.

[0067] A second aspect of the present invention provides a method for preparing a lithium-containing composite material, comprising the following steps: mixing a lithium-containing compound with a solution containing an organometallic salt, performing a coating treatment to obtain a coated material; and performing a sintering treatment on the coated material to obtain the lithium-containing composite material as described in the first aspect of the present invention; wherein the metal cation in the organometallic salt includes at least one of aluminum ions, titanium ions, or magnesium ions.

[0068] This invention employs a liquid-phase coating method, using a solution containing organometallic salts as the coating material. The organometallic salts can rapidly form a uniform coating on the surface of lithium-containing compounds through electrostatic attraction or adsorption precipitation. Specifically, due to electrostatic attraction or residual alkaline substances on the surface of the lithium-containing compound, aluminum and / or titanium ions in the organometallic salts rapidly aggregate and precipitate on the surface of the lithium-containing compound particles, while the organic chains are dispersed in the outer layer. Subsequently, through sintering, the metal ions bound to the surface of the lithium-containing compound can be doped into the micro-surface of the lithium-containing compound, thereby forming a shallow metal-doped layer and an outer metal coating layer on the surface of the lithium-containing compound. The outer organic chains carbonize at high temperature, forming a uniform carbon coating layer, thus enhancing the electron transport performance of the material. Furthermore, the preparation method of this invention is simple and easy to implement, and can form an effective doped layer and coating layer on the material surface.

[0069] In some embodiments of the present invention, the metal cations in the organometal salt include aluminum ions and / or titanium ions; in some specific embodiments of the present invention, the metal cations in the organometal salt include aluminum ions and titanium ions. Aluminum ions and titanium ions exhibit good adsorption effects on the surface of lithium-containing compounds, achieving good coating effects. Furthermore, through the synergistic effect of aluminum and titanium at the atomic, structural, and interface levels, better doping and coating effects can be achieved, resulting in lithium-containing composite materials with superior performance.

[0070] In some embodiments of the present invention, the molar ratio of aluminum ions to titanium ions in the metal cation of the organometallic salt is 0.1 to 6; non-limiting specific examples include any value or a range between any two of 0.1, 0.2, 0.25, 0.5, 1, 2, 3, 4, 5 or 6; in some specific embodiments of the present invention, the molar ratio of aluminum ions to titanium ions in the metal cation of the organometallic salt is 0.2 to 5; in some examples of the present invention, the molar ratio of aluminum ions to titanium ions in the metal cation of the organometallic salt is 0.25 to 4.

[0071] In some embodiments of the present invention, the organic anion in the organometallic salt includes at least one selected from polyacrylate, polystyrene-based anion, cellulose-based anion, chitosan-based anion, C1-C10 alkylcarboxylate, C1-C10 alkoxy anion, or C1-C10 alkylamine anion; in some specific embodiments of the present invention, the organic anion in the organometallic salt includes at least one selected from polyacrylate, polystyrene-based anion, cellulose-based anion, or chitosan-based anion; in some examples of the present invention, the organic anion in the organometallic salt is selected from polyacrylate.

[0072] In some embodiments of the present invention, the organometallic salt includes at least one of aluminum polyacrylate, titanium polyacrylate, aluminum polystyrene, titanium polystyrene, aluminum cellulose, titanium cellulose, aluminum chitosan, titanium chitosan, aluminum triformate, aluminum methacrylate, aluminum isopropoxide, tetramethyl titanate, aluminum dimethylamino, or titanium dimethylamino; in some specific embodiments of the present invention, the organometallic salt includes at least one of aluminum polyacrylate, titanium polyacrylate, aluminum polystyrene, titanium polystyrene, aluminum cellulose, titanium cellulose, aluminum chitosan, or titanium chitosan; in some examples of the present invention, the organometallic salt includes aluminum polyacrylate, titanium polyacrylate, or combinations thereof.

[0073] In some embodiments of the present invention, the mass concentration of the solution containing the organometallic salt is 0.05-50%; non-limiting specific examples include any value or a range between any two of 0.05%, 0.3%, 0.5%, 1%, 3%, 5%, 7%, 10%, 15%, 20%, 30%, 40%, or 50%; in some specific embodiments of the present invention, the mass concentration of the solution containing the organometallic salt is 0.3-30%; in some examples of the present invention, the mass concentration of the solution containing the organometallic salt is 0.5-20%.

[0074] In some embodiments of the present invention, the mass ratio of the lithium-containing compound to the solution containing the organometallic salt is (0.05~5):1; non-limiting specific examples include any value or a range between any two of 0.05:1, 0.12:1, 0.15:1, 0.2:1, 0.3:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, or 5:1; in some specific embodiments of the present invention, the mass ratio of the lithium-containing compound to the solution containing the organometallic salt is (0.12~3):1; in some examples of the present invention, the mass ratio of the lithium-containing compound to the solution containing the organometallic salt is (0.15~2):1.

[0075] In some embodiments of the present invention, the lithium-containing compound is a refined lithium-containing compound; in some specific embodiments of the present invention, the refining method includes crushing, pulverizing, or a combination thereof; in some examples of the present invention, the crushing method may include at least one of jaw crusher, roller crusher, or mechanical crusher; the pulverizing method may be air jet milling; in some specific examples of the present invention, the refining step specifically involves: subjecting the lithium-containing compound to jaw crusher, roller crusher, and mechanical crusher in sequence, and then subjecting it to air jet milling to obtain a refined lithium-containing compound.

[0076] In some embodiments of the present invention, the coating treatment temperature is 15~35°C; non-limiting specific examples include any value or a range between any two of 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, 32°C or 35°C; in some specific embodiments of the present invention, the coating treatment temperature is 20~30°C.

[0077] In some embodiments of the present invention, the coating process time is 0.1 to 40 min; non-limiting specific examples include any value or a range between any two of 0.1 min, 0.2 min, 1 min, 5 min, 10 min, 20 min, 30 min or 40 min; in some specific embodiments of the present invention, the coating process time is 0.2 to 30 min.

[0078] In some embodiments of the present invention, drying is performed after the coating process; in some specific embodiments of the present invention, the drying temperature can be 100~140℃, for example, any value or a range between 100℃, 110℃, 120℃, 130℃ or 140℃; the drying time can be 2~6h, for example, any value or a range between 2h, 3h, 4h, 5h or 6h. In some embodiments of the present invention, the sintering process is carried out in a protective gas atmosphere; in some specific embodiments of the present invention, the protective gas used in the sintering process includes at least one of nitrogen, argon or helium.

[0079] In some embodiments of the present invention, the sintering process includes sequential first-stage sintering and second-stage sintering; the sintering temperature of the first-stage sintering is 200~400℃; and the sintering temperature of the second-stage sintering is 380~820℃.

[0080] In some non-limiting specific examples of the present invention, the sintering temperature of a sintering stage can be any value or a range between any two of 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, or 400°C; in some embodiments of the present invention, the sintering temperature of a sintering stage is 220~380°C; in some specific embodiments of the present invention, the sintering temperature of a sintering stage is 240~340°C; in some examples of the present invention, the sintering temperature of a sintering stage is 260~300°C.

[0081] In some non-limiting specific examples of the present invention, the sintering temperature of the two-stage sintering can be any value or a range between any two of 380°C, 420°C, 450°C, 480°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 780°C, or 820°C; in some embodiments of the present invention, the sintering temperature of the two-stage sintering is 420~780°C; in some specific embodiments of the present invention, the sintering temperature of the two-stage sintering is 450~700°C; in some examples of the present invention, the sintering temperature of the two-stage sintering is 480~650°C.

[0082] By adjusting the sintering temperature, the surface coating or micro-doping effect of the material can be adjusted. Increasing the sintering temperature will promote the migration of metal ions to the core phase and increase the thickness of the metal doped layer. Using a suitable sintering temperature can achieve a more suitable doping and coating effect, thereby enabling the material to obtain better conductivity and higher initial charge specific capacity.

[0083] In some embodiments of the present invention, the holding time for a sintering stage is 1 to 4 hours; non-limiting specific examples include any value or a range between any two of 1 hour, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours; in some specific embodiments of the present invention, the holding time for a sintering stage is 1.5 to 3 hours; in some examples of the present invention, the holding time for a sintering stage is 1.8 to 2.5 hours.

[0084] In some embodiments of the present invention, the holding time for the two-stage sintering is 3 to 18 hours; non-limiting specific examples include any value or a range between any two of 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, 15 hours, or 18 hours; in some specific embodiments of the present invention, the holding time for the two-stage sintering is 5 to 15 hours; in some examples of the present invention, the holding time for the two-stage sintering is 6 to 12 hours.

[0085] By adjusting the sintering time, the surface coating or micro-doping effect of the material can also be adjusted. Extending the sintering time will promote the migration of metal ions to the core phase and increase the thickness of the metal doped layer. Using an appropriate sintering time can also achieve a more suitable doping and coating effect, thereby enabling the material to obtain better conductivity and higher first charge specific capacity.

[0086] In some embodiments of the present invention, the heating rate of a sintering stage is 1 to 8 °C / min; non-limiting specific examples include any value or a range between any two of 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, 7 °C / min, or 8 °C / min; in some specific embodiments of the present invention, the heating rate of a sintering stage is 2 to 5 °C / min.

[0087] In some embodiments of the present invention, the heating rate of the two-stage sintering is 1~8℃ / min; non-limiting specific examples include any value or a range between any two of 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min or 8℃ / min; in some specific embodiments of the present invention, the heating rate of the two-stage sintering is 2~5℃ / min.

[0088] In some embodiments of the present invention, cooling is performed after sintering; the cooling method may be furnace cooling.

[0089] A third aspect of the present invention provides a positive electrode lithium replenishing agent, which includes a lithium-containing composite material of the first aspect of the present invention, or a lithium-containing composite material prepared by the preparation method of the second aspect of the present invention.

[0090] The lithium-containing composite material involved in this invention is used to prepare a positive electrode lithium supplement, which has the advantages of uniform surface coating, low residual alkali content, good stability in air and water, good processing performance, and high ion and electron transport rate.

[0091] A fourth aspect of the present invention provides a lithium-ion battery in which the positive electrode contains a positive electrode lithium replenishing agent as described in the third aspect of the present invention.

[0092] The lithium-ion battery made using the positive electrode lithium replenishing agent of this invention can achieve a good lithium replenishment effect, effectively replenish the lithium-ion loss during the first charge and discharge process, improve the overall performance of the battery, and in particular enable the lithium-ion battery to have a high first charge specific capacity.

[0093] In some embodiments of the present invention, the initial charge specific capacity of the lithium-ion battery is ≥500mAh / g; specifically, it can be 500~1000mAh / g; for example, it can be any value or a range between any two of 500mAh / g, 550mAh / g, 600mAh / g, 680mAh / g, 700mAh / g, 760mAh / g, 800mAh / g, 850mAh / g, 900mAh / g, 950mAh / g, or 1000mAh / g. In some specific embodiments of the present invention, the initial charge specific capacity of the lithium-ion battery is 600~800mAh / g; in some examples of the present invention, the initial charge specific capacity of the lithium-ion battery is 680~760mAh / g.

[0094] A fifth aspect of the present invention provides a vehicle that includes a lithium-ion battery according to a fourth aspect of the present invention.

[0095] In some embodiments of the present invention, the vehicle can be a private car, such as a sedan, SUV, MPV, or pickup truck. The vehicle can also be a commercial vehicle, such as a van, bus, small truck, or large semi-trailer. The vehicle can be a gasoline-powered vehicle or a new energy vehicle. When the vehicle is a new energy vehicle, it can be a hybrid vehicle or a pure electric vehicle.

[0096] A sixth aspect of the present invention provides an electrical device that includes a lithium-ion battery according to a fourth aspect of the present invention.

[0097] In some embodiments of the present invention, the electrical device may be an electric vehicle, such as an electric car, electric bicycle, electric motorcycle, electric scooter, or electric wheelchair. The electrical device may also be other electrical devices such as energy storage systems, power tools, drones, and mobile devices such as wearable products, laptops, and mobile phones.

[0098] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0099] Example 1 A lithium-containing composite material, the specific preparation method of which is as follows: a) Ingredients: According to the molar ratio of Li to Fe of 5.05:1.0, accurately weigh the raw materials iron source iron oxide and lithium source lithium carbonate, add them to the ball mill jar, and wet grind for 2 hours; b) Single sintering: After drying the mixed material, a single sintering is performed using a programmed temperature rise strategy. Under a nitrogen atmosphere, the temperature is raised to 300℃ at a rate of 2℃ / min, held for 2 hours, then raised to 550℃ and held for 6 hours, followed by a further rise to 850℃ and held for 18 hours, and then cooled in the furnace; the material after single sintering is obtained, namely Li5FeO4. c) Crushing and pulverizing: The material after the first sintering is first coarsely crushed by jaw crusher, roller crusher, mechanical crusher and sieve in sequence, and then pulverized by air jet mill and sieved to obtain the pulverized material; d) Coating: Take raw material aluminum polyacrylate Al x (C3H3O2) m and titanium polyacrylate (Ti) y (C3H3O2) n The manufacturers were Anhui Zesheng Technology (reagent-grade product) and Hubei Qifei Pharmaceutical Chemical (purity >99%). A 1.8 wt% metal-organic composite flocculant solution was prepared with an Al to Ti atomic ratio of 2. At room temperature (25±5℃), the mixture was stirred at 200 rpm with a solute-to-solution weight ratio of 1:1. The pulverized material was slowly added to the solution, and the reaction coating time was controlled at 5 minutes. The solution was then immediately filtered off, and the mixture was dried in a vacuum drying oven at 120℃ for 4 hours. e) Secondary sintering: The dried material is subjected to secondary sintering using a programmed temperature rise strategy. Under a nitrogen atmosphere, the temperature is first raised to 280°C and held for 2 hours at a rate of 2°C / min to remove solvent moisture. Then, the temperature is raised to 550°C and held for 6 hours to allow metal ions to form a certain coating and doping layer on the material surface. After cooling in the furnace, the material is pulverized and sieved through a 200-mesh sieve to obtain the secondary sintered material, i.e., the lithium-containing composite material.

[0100] Figure 1 This is a schematic diagram of the lithium-containing composite material in Example 1 before and after secondary sintering. The left side shows the structure before secondary sintering, and the right side shows the structure after secondary sintering. In this schematic diagram, due to charge attraction or the residue of alkaline substances on the surface of Li5FeO4, aluminum ions and titanium ions in the metal-organic composite flocculant will rapidly aggregate and precipitate on the surface of Li5FeO4 particles, while the organic chains are dispersed in the outer layer (e.g., Figure 1 (As shown on the left in the image), a secondary sintering process is then performed, allowing the metal ions bound to the Li5FeO4 surface to be doped into the micro-surface of Li5FeO4. This results in the formation of a shallow metal-doped layer 2 and an outer metal coating layer 3 on the surface of Li5FeO4. The outer organic chains undergo carbonization at high temperature, forming a uniform carbon coating layer 4. The undoped Li5FeO4 then serves as the core 1 (as shown on the left in the image). Figure 1 (As shown on the right side of the image).

[0101] In Example 1, the average particle size of the core 1 is 10 μm, the average thickness of the metal doped layer 2 is 2 μm, the average thickness of the metal coating layer 3 is 20 nm, and the average thickness of the carbon coating layer 4 is 30 nm.

[0102] Example 2 A lithium-containing composite material differs from Example 1 in that the target temperature for secondary sintering in step e) is changed from 550°C to 400°C; other conditions are the same as in Example 1.

[0103] Example 3 A lithium-containing composite material differs from Example 1 in that the target temperature for secondary sintering in step e) is changed from 550°C to 800°C; other conditions are the same as in Example 1.

[0104] Example 4 A lithium-containing composite material differs from Example 1 in that the concentration of the metal-organic composite flocculant solution in step d) is 2 wt%, and the atomic ratio of Al to Ti is 0.25; and the holding time at 550°C in step e) is 8 h; other conditions are the same as in Example 1.

[0105] Example 5 A lithium-containing composite material differs from Example 4 in that the concentration of the metal-organic composite flocculant solution in step d) of this example is 1 wt%, and the atomic ratio of Al to Ti is maintained at 0.25; other conditions are the same as in Example 4.

[0106] Example 6 A lithium-containing composite material differs from Example 4 in that the concentration of the metal-organic composite flocculant solution in step d) of this example is 30 wt%, and the atomic ratio of Al to Ti is maintained at 0.25; other conditions are the same as in Example 4.

[0107] Example 7 A lithium-containing composite material differs from Example 4 in that the weight ratio of solute to solution in step d) of this example is 0.5:1; other conditions are the same as in Example 4.

[0108] Example 8 A lithium-containing composite material differs from Example 4 in that the weight ratio of solute to solution in step d) of this example is 0.1:1; other conditions are the same as in Example 4.

[0109] Example 9 A lithium-containing composite material differs from Example 4 in that the weight ratio of solute to solution in step d) of this example is 4:1; other conditions are the same as in Example 4.

[0110] Comparative Example 1 A lithium-containing composite material differs from Example 1 in that, in step d), the metal-organic composite flocculant solution is replaced with a single-component aluminum-based inorganic flocculant, namely polyaluminum chloride (PAC, Al2Cl(OH)5, analytical grade, Aladdin), while other conditions are the same as in Example 1.

[0111] Comparative Example 2 A lithium-containing composite material differs from Example 1 in that step d) in this example uses a similar traditional solid-phase coating method, specifically: the pulverized material obtained in step c) is simply mixed with alumina and titanium oxide in a solid phase, followed by secondary sintering in step e); other conditions are the same as in Example 1.

[0112] Comparative Example 3 A lithium-containing composite material differs from Example 1 in that, in step d), the metal-organic composite flocculant solution is replaced with an inorganic metal salt solution, namely a solution prepared from ferric sulfate and aluminum chloride, and the metal ion concentration is the same as in Example 1; other conditions are the same as in Example 1.

[0113] Performance testing The lithium-containing composite materials prepared in Examples 1-9 and Comparative Examples 1-3 were used as test samples, and the following performance tests were performed: 1) The elemental content of the test sample was analyzed by ICP to detect the content of Al, Ti and C elements in the entire bulk phase of the test sample; the specific surface area was determined by BET method, and the D10, D50 and D90 particle sizes were determined; and the morphology was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thickness of the metal coating layer and the carbon coating layer can be observed by TEM, and the uniformity of the coating can be observed. 2) Residual alkali content (free Li) + Test Method: The residual alkali content was determined according to standard GB / T 41704-2022 "Test Methods for Cathode Materials of Lithium-ion Batteries - Determination of Magnetic Foreign Matter Content and Residual Alkali Content" using potentiometric titration based on acid-base neutralization reaction. The test sample powder was weighed into a beaker, deionized water was added, and the residual alkali on the sample surface was dissolved by stirring. Then, the sample was titrated with standard hydrochloric acid (HCl) solution to neutralize the residual LiOH and Li₂CO₃ in the test sample. The titration endpoint was determined by the potential jump point, and the residual alkali content W was calculated based on the amount of hydrochloric acid consumed. The result was calculated using the formula W = 1.54 × W. LiOH +W Li2CO3 Calculate the free Li + The final content, of which W LiOH W refers to the mass fraction of residual LiOH in the sample. Li2CO3 This refers to the mass fraction of residual Li2CO3 in the sample.

[0114] 3) Test method for powder conductivity: The four-probe four-wire pressure test method is adopted. The equipment is ACCFILMPR510 with an inner diameter of 16mm. Specific steps: Weigh the test sample and put it into the mold cavity, connect the positive and negative electrodes, set the parameters to pressure 1000N and time 30s, and complete the test.

[0115] 4) First charge specific capacity test method: Prepare slurry according to the mass ratio of lithium-containing composite material:SP:PVDF=80:10:10, coat it into electrode sheets, roll press, cut and dry the sheets, assemble them into button batteries, and test them in the Blue Electric test system. The test rate is 0.1C and the test voltage is 2.0V-3.75V.

[0116] The test results are shown in Tables 1-4.

[0117] Table 1 Performance comparison between Example 1 and Comparative Examples 1-2

[0118] Figure 2 The images shown are scanning electron microscope (SEM) images of Example 1 and Comparative Examples 1-2; where a is Example 1; b is Comparative Example 1; and c is Comparative Example 2. (In conjunction with...) Figure 2As shown in Table 1, the material in Example 1 uses a special coating method, forming a uniform coating layer (including an in-situ carbonization layer) in situ after secondary sintering. The material surface coating is relatively uniform, with lower residual alkali, better conductivity, and higher initial charge specific capacity. TEM observation shows that the thickness of the metal coating layer 3 and the carbon coating layer 4 in Example 1 ranges from 2 to 20 nm, with relatively uniform surface coating. In contrast, Comparative Example 1 uses the same coating method but employs a single inorganic flocculant, resulting in a sample without a carbon layer coating and poorer properties. Comparative Example 2 uses a traditional solid-phase coating method, leading to agglomeration of the coating agent and very uneven coating, forming "island-like" coatings. Examples 2-9 also exhibit uniform and dense coating structures, with large specific surface areas and low residual alkali.

[0119] Table 2 Performance comparison of Examples 2-3 and Comparative Example 3

[0120] As can be seen from Tables 1 and 2, Example 1 used a more suitable secondary sintering temperature compared to Examples 2 and 3, resulting in better conductivity and higher initial charge specific capacity; Comparative Example 3 used a traditional metal salt aqueous solution, which could not accumulate on the material surface to form a coating structure, resulting in high residual alkali content and poor conductivity on its surface.

[0121] Table 3 Performance Comparison of Examples 4-6

[0122] As can be seen from Table 3, Example 4, compared with Examples 5-6, used a metal-organic composite flocculant solution of appropriate concentration, which has better conductivity and higher initial charge specific capacity. Table 4 Performance Comparison of Examples 7-9

[0123] As can be seen from Table 4, compared with Examples 8-9, Example 7, by using a suitable solute to solution weight ratio, can achieve a better coating effect, with better conductivity and higher initial charge specific capacity.

[0124] In summary, this invention, by setting a metal doping layer and a metal coating layer on the outside of the core, helps to reduce residual alkali on the material surface and stabilize the material surface structure; while setting a carbon coating layer helps to improve the electronic conductivity of the material; through specific structural design, the lithium-containing composite material has low residual alkali on the surface and high ion and electron transport rates, and can be used to prepare high-performance cathode lithium replenishment agents and lithium-ion batteries.

Claims

1. A lithium-containing composite material, characterized in that, The lithium-containing composite material includes a core and a metal-doped layer, a metal cladding layer, and a carbon cladding layer sequentially disposed outside the core; the core contains a lithium-containing compound; the metal-doped layer contains a metal-doped compound, which is formed by doping a metal element into the lithium-containing compound; the metal cladding layer contains a metal material; the metal element in the metal-doped compound and the metal element in the metal material each independently include at least one of Al, Ti, or Mg.

2. The lithium-containing composite material according to claim 1, characterized in that, The average particle size of the core is 5~20μm; And / or, the average thickness of the metal-doped layer is 1~8 μm; And / or, the average thickness of the metal cladding layer is 10~30nm; And / or, the average thickness of the carbon coating layer is 20~40 nm.

3. The lithium-containing composite material according to claim 1, characterized in that, The lithium-containing compound includes at least one of Li5FeO4, Li5Fe5O8, Li2NiO2, Li6CoO4, Li4V3O8, Li2MoO3, or lithium-rich manganese-based materials; And / or, the metal elements in the metal doping compound and the metal elements in the metal material both include Al and Ti; the atomic ratio of Al to Ti in the metal doping compound is 0.1 to 6; the atomic ratio of Al to Ti in the metal material is 0.1 to 6.

4. A method for preparing a lithium-containing composite material, characterized in that, Includes the following steps: A lithium-containing compound is mixed with a solution containing an organometal salt and then coated to obtain a coating material. The coating material is sintered to obtain a lithium-containing composite material as described in any one of claims 1 to 3; the metal cation in the organometallic salt includes at least one of aluminum ions, titanium ions, or magnesium ions.

5. The preparation method according to claim 4, characterized in that, The organic anions in the organometallic salt include at least one of polyacrylate, polystyrene-based anion, cellulose-based anion, chitosan-based anion, C1-C10 alkylcarboxylate, C1-C10 alkoxy anion, or C1-C10 alkylamine anion.

6. The preparation method according to claim 4, characterized in that, The mass concentration of the solution containing the organometal salt is 0.05~50%; And / or, the mass ratio of the lithium-containing compound to the solution containing the organometal salt is (0.05~5):

1.

7. The preparation method according to claim 4, characterized in that, The sintering process includes sequential first-stage sintering and second-stage sintering; the sintering temperature of the first-stage sintering is 200~400℃; and the sintering temperature of the second-stage sintering is 380~820℃.

8. The preparation method according to claim 7, characterized in that, The holding time for the first sintering stage is 1-4 hours; And / or, the holding time for the two-stage sintering is 3~18h; And / or, the heating rate of the sintering section is 1~8℃ / min; And / or, the heating rate of the two-stage sintering is 1~8℃ / min.

9. A positive electrode lithium replenishing agent, characterized in that, The positive electrode lithium supplement includes the lithium-containing composite material according to any one of claims 1 to 3, or the lithium-containing composite material prepared by the preparation method according to any one of claims 4 to 8.

10. A lithium-ion battery, characterized in that, The positive electrode of the lithium-ion battery contains the positive electrode lithium replenishing agent as described in claim 9.

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