Negative active material as well as preparation method and application thereof

Abstract

The invention provides a negative electrode active material and a preparation method and application thereof, the negative electrode active material comprises: an active substrate, the active substrate comprising germanium particles; the coating layer is arranged on at least part of the surface of the active matrix, and the coating layer is a carbon-doped titanium-tin bimetallic oxide; the coating layer is obtained by forming a titanium-tin bimetal organic framework compound and then carbonizing an organic ligand in the titanium-tin bimetal organic framework compound. According to the negative electrode active material as well as the preparation method and the application thereof provided by the invention, the transmission of electrons and ions can be promoted while the volume expansion of the germanium particles is inhibited, so that the electrochemical performance of the negative electrode active material is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion batteries, in particular to a negative electrode active material and a preparation method and application thereof. BACKGROUND

[0002] With the acceleration of industrialization and the increase of energy demand, it is urgent to develop and promote green renewable energy. Among them, rechargeable lithium ion batteries gradually occupy the main market of current energy storage equipment due to their large capacity, long cycle life, high rate capability and other advantages. Lithium ion batteries are mainly composed of positive electrode material, negative electrode material, electrolyte and separator, etc., and the negative electrode material is a key factor affecting the performance of the battery.

[0003] The current mainstream graphite negative electrode material cannot meet the needs of the development of lithium ion batteries due to its limited theoretical specific capacity. Germanium-based materials are considered as one of the next ideal negative electrode materials for lithium batteries due to their high specific capacity, moderate lithium intercalation and deintercalation voltage, abundant natural reserves, low price, high safety and environmental protection. However, the volume expansion of germanium metal during lithium extraction and intercalation exceeds 300%, which leads to the crushing of germanium particles, the disconnection of the conductive path, the increase of impedance, the powdering and falling off, the poor cycle performance and the rapid decay of specific capacity. Through carbon coating and nanocrystallization, the expansion is partially alleviated, but the conductivity and interface stability are insufficient. Through metal alloying germanium material, the expansion is improved, but there is a problem of phase separation. SUMMARY

[0004] The present application provides a negative electrode active material and a preparation method and application thereof, which can inhibit the volume expansion of germanium particles while promoting the transmission of electrons and ions, thereby improving the electrochemical performance of the negative electrode active material.

[0005] To solve the above technical problems, the present application is realized by the following technical scheme.

[0006] The present application provides a negative electrode active material, which comprises:

[0007] An active substrate, wherein the active substrate comprises germanium particles;

[0008] A coating layer is arranged on at least part of the surface of the active substrate, and the coating layer is a carbon-doped titanium-tin bimetallic oxide; the coating layer is obtained by carbonizing organic ligands in a titanium-tin bimetallic organic framework compound after forming the titanium-tin bimetallic organic framework compound.

[0009] In an embodiment of the present application, the mass ratio of the active substrate and the coating layer is 3:1-1:2.

[0010] In an embodiment of the present application, in the coating layer, the molar ratio of titanium element to tin element is 1:1-1:3.

[0011] In an embodiment of the present application, the carbon content in the negative electrode active material is 10wt%-40wt%.

[0012] The present application also provides a preparation method of the negative electrode active material, comprising:

[0013] adding a titanium source precursor and a tin source precursor into a solvent, then adding an organic ligand and a pH regulator, reacting at a preset pH value and a preset temperature for a preset time, filtering and drying to obtain a titanium-tin bimetallic organic framework compound;

[0014] immersing the titanium-tin bimetallic organic framework compound into a germanium solution, adding a reducing agent to react at a reaction temperature, forming germanium particles in the titanium-tin bimetallic organic framework compound, filtering and drying to obtain an intermediate product;

[0015] under an inert gas atmosphere, performing step-by-step calcination on the intermediate product, then performing cleaning and drying to obtain the negative electrode active material.

[0016] In an embodiment of the present application, the titanium source precursor comprises at least one of titanium tetrachloride, titanium trichloride, titanyl sulfate or tetraisopropyl titanate, and the tin source precursor comprises at least one of tin dichloride, tin acetate, tin oxalate or tin dioxide;

[0017] and / or, the solvent comprises at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide or ethyl acetate;

[0018] and / or, the organic ligand comprises at least one of terephthalic acid, 2-amino terephthalic acid, 2-hydroxy terephthalic acid, phthalic acid, isophthalic acid, dodecylbenzoic acid or fumaric acid;

[0019] and / or, the pH regulator comprises at least one of hydrochloric acid, nitric acid, sulfurous acid, dilute sulfuric acid, acetic acid, phytic acid, citric acid, succinic acid or tartaric acid;

[0020] and / or, the reducing agent comprises at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate or ammonia water;

[0021] and / or, the solute in the germanium solution comprises at least one of germanium tetrachloride, germanium dichloride, germanium sulfide or germanium disulfide, and the solvent in the germanium solution comprises at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide or ethyl acetate.

[0022] In an embodiment of the present application, the molar ratio of titanium element in the titanium source precursor to tin element in the tin source precursor is 1:1-1:3;

[0023] And / or, the total molar amount of the titanium source precursor and the tin source precursor and the molar ratio of the organic ligand are 2:3-4:3;

[0024] And / or, the preset pH range is 2.5-4.5, the preset temperature is 110℃-140℃, and the preset time is 10h-16h;

[0025] And / or, the mass ratio of the titanium-tin bimetallic organic framework compound to the solute in the germanium solution is 1:2.5-1:17;

[0026] And / or, the concentration of the germanium solution is 0.25 mol / L to 1.5 mol / L;

[0027] And / or, the molar ratio of the solute to the reducing agent in the germanium solution is greater than 1:1.33.

[0028] And / or, the reaction temperature is 50℃-70℃.

[0029] In one embodiment of the present invention, the segmented calcination includes:

[0030] The intermediate product is heated from room temperature to a first temperature at a first heating rate, and held at that temperature for a first time; and

[0031] The first temperature is raised to the second temperature at a second heating rate, and the temperature is maintained for a second time.

[0032] In one embodiment of the present invention, the first heating rate is 1℃ / min-10℃ / min, the first temperature is 250℃-350℃, and the first time is 1h-1.5h;

[0033] The second heating rate is 1℃ / min-10℃ / min, the second temperature is 500℃-700℃, and the second time is 1.5h-3h.

[0034] The present invention also provides a lithium-ion battery comprising the negative electrode active material described above or comprising the negative electrode active material obtained by the preparation method described above.

[0035] In summary, this invention proposes an anode active material, its preparation method, and its application. By setting a carbon-doped titanium-tin bimetallic oxide coating layer on germanium particles, the expansion stress of the active substrate can be buffered, and the tin element can improve conductivity. Through the synergistic effect of the titanium-tin bimetallic oxide, the electrochemical activity can be significantly enhanced. While suppressing the volume expansion of germanium particles, it promotes the transport of electrons and ions, thereby improving the electrochemical performance of the anode active material. Specifically, the carbon in the coating layer possesses the three-dimensional structure of organic ligands in the MOF structure, and the tin oxide and titanium oxide occupy the positions of metal nodes in the MOF. That is, the coating layer possesses the highly stable stacking and porous structure of the MOF structure, thus forming a three-dimensional network buffer layer on the surface of the active substrate. This buffers the expansion stress of the active substrate and improves the stability and conductivity of the anode active material. The anode active material exhibits high reversible capacity and excellent charge-discharge kinetics performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is an ideal structural diagram of the intermediate product in one embodiment. Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0039] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0040] The technical solution of the present invention will be further described in detail below with reference to several embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention proposes a negative electrode active material, and a positive electrode active material comprising an active substrate and a coating layer. The active substrate comprises germanium particles, and the coating layer is disposed on at least a portion of the surface of the active substrate. The coating layer is a carbon-doped titanium-tin bimetallic oxide, obtained by forming a titanium-tin bimetallic organic framework compound (TiSn-MOF) and then carbonizing the organic ligands in the compound. This gives the coating layer a three-dimensional structure similar to that of a MOF material, which can buffer the expansion stress of the active substrate. Furthermore, the tin element enhances conductivity. Through the synergistic effect of the titanium-tin bimetallic oxide, electrochemical activity is significantly enhanced. While suppressing the volume expansion of the germanium particles, it promotes electron and ion transport, thereby improving the electrochemical performance of the negative electrode active material.

[0042] In one embodiment of the present invention, the coating layer includes carbon, tin oxide (SnO2), and titanium oxide (TiO2), etc., with carbon occupying the positions of organic ligands in the MOF, meaning that carbon possesses the three-dimensional structure of organic ligands in the MOF structure. Tin oxide and titanium oxide occupy the positions of metal nodes in the MOF, meaning that the coating layer possesses the highly stable stacking and porous structure of the MOF structure, thereby forming a three-dimensional network buffer layer on the surface of the active substrate, which can buffer the expansion stress of the active substrate and promote the transport capacity of electrons and ions. It should be noted that the organic ligands in the MOF structure are carbonized to form a carbon skeleton, and no organic ligands remain in the coating layer, thereby stabilizing the MOF structure and preventing the coating layer from collapsing due to the shedding of remaining organic ligands during use, thus improving the stability and conductivity of the coating layer, and thus improving the stability and conductivity of the negative electrode active material.

[0043] In one embodiment of the present invention, the mass ratio of the active substrate to the coating layer is, for example, 3:1 to 1:2. By controlling the mass ratio of the active substrate to the coating layer, the energy density of the negative electrode active material is ensured while suppressing the expansion of the negative electrode active material.

[0044] In one embodiment of the present invention, the molar ratio of titanium oxide to tin oxide in the coating layer is, for example, 1:1 to 1:3, that is, the molar ratio of titanium to tin is 1:1 to 1:3. Titanium oxide possesses extremely high structural stability and porosity, ensuring the stability of the coating layer within the MOF material framework. Tin oxide, while possessing high electronic and ionic conductivity, also provides capacity for the active material, acting as a capacity reserve in addition to the germanium particles. Through synergistic action, titanium oxide and tin oxide buffer the volume change of the entire negative electrode active material. By controlling the molar ratio of titanium oxide and tin oxide, the excellent synergistic effect of titanium oxide and tin oxide is achieved, resulting in a three-dimensional network buffer layer with high structural stability and high lithium-ion transport capability.

[0045] In one embodiment of the present invention, the carbon content in the negative electrode active material is, for example, 10wt%-40wt%. By controlling the carbon content, the stability and conductivity of the coating layer are improved, thereby enhancing the performance of the negative electrode active material.

[0046] In one embodiment of the present invention, the coating coverage of the coating layer is, for example, 60% or more, or, for example, 65%-75%, 70%-80%, or 80%-90%. The coating coverage is the percentage of the surface area of ​​the active substrate covered by the coating layer. By controlling the coating coverage, a continuous three-dimensional network is formed, which suppresses volume changes in the active substrate during cycling while ensuring rapid lithium ion transport through the gaps in the three-dimensional network.

[0047] This invention also proposes a method for preparing a negative electrode active material. The method involves: adding a titanium source precursor and a tin source precursor to a solvent, then adding an organic ligand and a pH adjuster; reacting at a preset pH value, preset temperature, and preset time; filtering and drying to obtain a titanium-tin bimetallic organic framework compound; immersing the titanium-tin bimetallic organic framework compound in a germanium solution, adding a reducing agent, and reacting at a reaction temperature to form germanium particles within the compound; filtering and drying to obtain an intermediate product; and then, under an inert gas atmosphere, calcining the intermediate product in stages, followed by washing and drying to obtain the negative electrode active material.

[0048] In one embodiment of the present invention, the titanium source precursor includes at least one of titanium tetrachloride (TiCl4), titanium trichloride (TiCl3), titanium oxysulfate (TiOSO4), or tetraisopropyl titanate (TIPT), and the tin source precursor includes at least one of tin dichloride (SnCl2), tin(II) acetate, or tin oxalate (C2O4Sn). The solvent includes at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide, or ethyl acetate. Preferably, the solvent is at least one of dimethylformamide, ethanol, isopropanol, or ethyl acetate; more preferably, the solvent is at least one of dimethylformamide or ethanol. In the solvent, the titanium source precursor is added at a concentration of 0.1 mol / L to 0.3 mol / L, and the tin source precursor is added at a concentration of 0.1 mol / L to 0.3 mol / L, and the molar ratio of titanium in the titanium source precursor to tin in the tin source precursor is, for example, 1:1 to 1:3.

[0049] In one embodiment of the present invention, the organic ligand includes at least one selected from p-phthalic acid (PTA), 2-aminoterephthalic acid (2-Aminoterephthalic acid), 2-hydroxyterephthalic acid (2-HBT), phthalic acid (PA), isophthalic acid (IPA), dodecyl benzoate, or fumaric acid. The total molar ratio of the titanium-source precursor to the tin-source precursor and the molar ratio of the organic ligand are 2:3 to 4:3.

[0050] In one embodiment of the present invention, the pH adjuster includes at least one of hydrochloric acid, nitric acid, sulfurous acid, dilute sulfuric acid, acetic acid, phytic acid, citric acid, succinic acid, or tartaric acid. Preferably, the pH adjuster includes at least one of hydrochloric acid or acetic acid with a mass fraction of 2%-20%. The pH of the reaction system is adjusted to a preset range using the pH adjuster, and the reaction is carried out at a preset temperature for a preset time. The preset pH range is, for example, 2.5-4.5, to inhibit Sn. 2+ Hydrolysis is performed at a preset temperature of, for example, 110℃-140℃, and for a preset time of, for example, 10h-16h. After the reaction, a titanium-tin bimetallic organic framework compound precipitate is obtained. This precipitate is then obtained through steps such as filtration and drying. The filtration and drying can be performed using one or more methods, such as vacuum drying, spray drying, freeze drying, or filtration drying, preferably a combination of filtration drying and vacuum drying. In this embodiment, the titanium-tin bimetallic organic framework compound precipitate is obtained by filtration, washed 2-3 times with pure solvent, and then soaked in solvent for 12h-24h to remove impurities adsorbed on the surface of the precipitate. It is then filtered again and vacuum dried at 50℃-70℃ for 10h-20h to obtain an octahedral TiSn-MOF.

[0051] In one embodiment of the present invention, after obtaining the titanium-tin bimetallic organic framework compound, the compound is immersed in a germanium solution and uniformly dispersed at room temperature for 20-60 minutes to promote the diffusion of germanium ions into the pores of the TiSn-MOF. The room temperature is, for example, 25°C-30°C, and the dispersion method is, for example, at least one of ultrasonication and stirring. A reducing agent is added and reduction is carried out at the reaction temperature for 5-10 hours, resulting in the in-situ formation of germanium particles within the titanium-tin bimetallic organic framework compound. The reaction temperature is, for example, 50℃-70℃; the concentration of the germanium solution is, for example, 0.25mol / L-1.5mol / L; the solute in the germanium solution includes, for example, at least one of germanium tetrachloride, germanium dichloride, germanium sulfide, or germanium disulfide; the solvent in the germanium solution includes, for example, at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide, or ethyl acetate; preferably, the solvent is, for example, at least one of dimethylformamide, ethanol, isopropanol, or ethyl acetate; more preferably, the solvent is, for example, at least one of dimethylformamide or ethanol. The reducing agent includes, for example, at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, or ammonia water; preferably, the reducing agent is, for example, ammonia water with a mass fraction of 10%-50%. In this case, the mass ratio of the titanium-tin bimetallic organic framework compound to the solute in the germanium solution is, for example, 1:2.5-1:17, and the molar ratio of the solute to the reducing agent in the germanium solution is greater than 1:1.33, so as to ensure that the number of electrons provided by the reducing agent is greater than the number of electrons required for germanium to be reduced to elemental form.

[0052] In one embodiment of the present invention, after reduction, germanium is formed in situ within the titanium-tin bimetallic organic framework compound, thus obtaining Ge@TiSn-MOF precipitate. The Ge@TiSn-MOF precipitate is filtered and dried to obtain an intermediate product. In this embodiment, the solid precipitate is collected, for example, by centrifugation, and washed three or more times with anhydrous ethanol. It is then vacuum dried at 50°C-70°C for 10-30 minutes to obtain the intermediate, namely Ge@TiSn-MOF.

[0053] In one embodiment of the present invention, the intermediate product is subjected to segmented calcination under an inert gas atmosphere. The segmented calcination includes: heating the intermediate product from room temperature to a first temperature at a first heating rate and holding it at that temperature for a first time; and heating the first temperature to a second temperature at a second heating rate and holding it at that temperature for a second time. The first heating rate is, for example, 1°C / min-10°C / min, the first temperature is, for example, 250°C-350°C, and the first time is, for example, 1h-1.5h; the second heating rate is, for example, 1°C / min-10°C / min, the second temperature is, for example, 500°C-700°C, and the second time is, for example, 1.5h-3h. The inert gas is, for example, at least one of helium, argon, or krypton, preferably argon.

[0054] In one embodiment of the present invention, at a first preset temperature, the organic ligand undergoes a decarboxylation reaction, initially forming a carbon framework. At a second preset temperature, the tin nucleus and titanium atoms react with the active oxygen atoms released from the organic ligand to form tin oxide and titanium oxide, forming a coating layer. The organic ligand within the coating layer is completely carbonized to form carbon, and the coating layer retains the MOF structure. In this embodiment, the degree of carbonization of the organic ligand is controlled by controlling the conditions of segmented calcination.

[0055] In one embodiment of the present invention, after calcination and cooling to room temperature, the negative electrode active material is obtained through post-processing steps such as cleaning and drying. In this embodiment, for example, after removing free metals from the surface of the product with acid, the solvent is removed. The acid includes at least one of hydrochloric acid, nitric acid, sulfurous acid, dilute sulfuric acid, acetic acid, phytic acid, citric acid, succinic acid, or tartaric acid. Preferably, the acid is a volatile acid such as hydrochloric acid or acetic acid with a mass fraction of 2%-20%. After soaking the filtered product in acid for 1-2 hours, it is washed with deionized water until neutral, filtered again, and vacuum dried at 50°C-70°C for 1-3 hours to remove residual water from the surface. By first forming TiSn-MOF and then forming germanium in situ, TiSn-MOF coats the germanium particles, and then the organic ligands are carbonized, so that the coating layer has a MOF structure. This effectively suppresses the volume expansion of germanium particles, stabilizes the electrode structure, and improves charge conduction efficiency. The negative electrode active material has high reversible capacity and excellent charge-discharge kinetics performance.

[0056] This invention also proposes a lithium-ion battery, comprising a casing and an electrode assembly disposed within the casing. The electrode assembly includes a positive electrode, a separator, and a negative electrode. The negative electrode comprises the aforementioned negative electrode active material. The separator is placed between the positive and negative electrodes to prevent short circuits and allow lithium ions to pass through. The positive electrode, separator, and negative electrode are sequentially stacked to ensure that a separator is present between any positive and negative electrode. A multi-layered stack is obtained by winding or folding, and this stack is then incorporated into the battery casing as the electrode assembly. Finally, electrolyte is injected into the casing once or in multiple stages to completely immerse the electrode assembly in the electrolyte, thereby conducting ions between the positive and negative electrodes. In one embodiment of this invention, the lithium-ion battery is, for example, a secondary battery, which may be, for example, a pouch battery, a prismatic battery, or a cylindrical battery. This invention does not specifically limit the type of lithium-ion battery.

[0057] In one embodiment of the present invention, the negative electrode sheet includes, for example, a negative current collector and a negative active layer coated at least on one surface of the negative current collector. The negative current collector is selected from, for example, a copper foil current collector, a composite copper foil current collector, a carbon current collector, a foamed copper current collector, or a stainless steel current collector, and the thickness of the negative current collector is, for example, 6 μm-15 μm. In this embodiment, the negative current collector is, for example, copper foil, and the thickness of the copper foil is, for example, 8 μm.

[0058] In one embodiment of the present invention, the negative electrode active layer includes a negative electrode active material, a binder, and a thickener. The negative electrode active material is selected from the aforementioned negative electrode active materials. The binder is selected, for example, from at least one of the following: polymerized styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylic acid (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), or carboxymethyl chitosan (CMCS). The thickener is selected, for example, carboxymethyl cellulose sodium (CMC). The mass ratio of the negative electrode active material, binder, and thickener in the negative electrode active layer is, for example, (94-97):(2-4):(1-2).

[0059] In one embodiment of the present invention, the negative electrode active material is selected from the above-mentioned negative electrode active material. The thickener is selected from sodium carboxymethyl cellulose, and the binder is selected from styrene-butadiene rubber. In one embodiment of the present invention, the negative electrode active material, binder, and thickener are mixed in a mass ratio of 95:4:1, deionized water is added, and the mixture is stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry is coated onto a copper foil and dried in a vacuum drying oven at 110°C for 12 hours. After cold pressing, slitting, die-cutting, and other processes, a negative electrode sheet is obtained. In other embodiments, the negative electrode sheet can also be obtained by any other method of forming a negative electrode sheet.

[0060] In one embodiment of the present invention, the positive electrode sheet includes a positive current collector and a positive active layer coated on at least one surface of the positive current collector. The positive current collector is, for example, a foil formed by surface treatment of materials such as nickel, titanium, aluminum, silver, stainless steel, or carbon. Besides foil, the positive current collector can also be used in any one or more combinations of various forms such as film, mesh, porous, foam, or non-woven fabric. The thickness of the positive current collector is, for example, 8 μm-15 μm. In this embodiment, the positive current collector is, for example, an aluminum foil, and the thickness of the aluminum foil is, for example, 13 μm.

[0061] In one embodiment of the present invention, the positive electrode active layer includes a positive electrode active material, a binder, and a conductive agent. The positive electrode active material includes, for example, any one or a combination of at least two of lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, or lithium nickel cobalt aluminum oxide, to improve the energy density of the lithium-ion battery. The binder is selected from, for example, any one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinylidene fluoride-tetrafluoroethylene-propylene terpolymer (ETFE), ethylene-vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer (TFE-HFP-VDF), or tetrafluoroethylene-hexafluoropropylene copolymer (FEP). The conductive agent is selected from, for example, any one or more of conductive carbon black (SuperP), acetylene black, or Ketjen black. The mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode active layer is, for example, (90-97):(1-5):(2-5).

[0062] In one embodiment of the present invention, the positive electrode active material is, for example, LiNi. x Mn y Co z O2, 0.5≤x≤0.8, 0.1≤y≤0.25, 0.1≤z≤0.25, and for example, LiNi 0.6 Mn 0.2 Co 0.2O2, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride are used. The positive electrode active material, conductive agent, and binder are mixed in a mass ratio of 95:3:2, and an organic solvent is added. The mixture is stirred thoroughly to obtain a positive electrode slurry. The organic solvent is, for example, N-methylpyrrolidone (NMP). The positive electrode slurry is uniformly coated onto aluminum foil and dried in a vacuum drying oven at 110°C for 12 hours. The positive electrode sheet is then obtained through cold pressing, slitting, and die-cutting processes. This application does not limit the method of preparing the positive electrode sheet; in other embodiments, the positive electrode sheet can also be obtained by any other method of forming a positive electrode sheet.

[0063] In one embodiment of the present invention, the electrolyte includes, for example, an organic solvent, a lithium salt, and additives. The organic solvent is selected from one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or diethyl carbonate (DEC). The lithium salt is selected from, for example, one or more of the following: lithium bis(fluorosulfonyl)imide (LiFSi), lithium difluorophosphate (LiPO2F2), lithium hexafluorophosphate (LiPF6), or lithium tetrafluoroborate (LiBF4). In this embodiment, in an argon atmosphere glove box with a water content of less than 10 ppm, ethylene carbonate and diethyl carbonate are mixed, for example, at a mass ratio of 1:1. Thoroughly dried LiPF6 is dissolved in the mixed organic solvent, and after being mixed evenly, an electrolyte is obtained, wherein the content of LiPF6 is 1 mol / L.

[0064] In one embodiment of the present invention, the separator is, for example, a polyethylene (PE) membrane, a polypropylene (PP) membrane, a glass fiber membrane, or a composite membrane, and the thickness of the separator is, for example, 9 μm-30 μm. In another embodiment of the present invention, the separator is, for example, selected as an 8 μm-10 μm polyethylene base membrane, and a 2 μm-4 μm thick nano-alumina coating is coated on at least one side of the base membrane.

[0065] In one embodiment of the present invention, the above-mentioned positive electrode, separator, and negative electrode are placed sequentially, with the separator positioned between the positive and negative electrode to act as a separator. An electrode assembly is obtained by winding or stacking the electrodes. The electrode assembly is then installed in a housing, baked at 80°C-100°C to remove moisture, injected with electrolyte, and sealed. Following these processes, a lithium-ion battery is obtained through standing, hot and cold pressing, formation, clamping, and capacity testing.

[0066] The present invention will be explained in more detail below by referring to embodiments, which should not be construed as limiting. Appropriate modifications can be made within the scope of the present invention, and all such modifications fall within the technical scope of the present invention.

[0067] Example 1

[0068] Preparation of the negative electrode active material: TiCl4 and SnCl2 were dissolved in 40 mL of dimethylformamide, with TiCl4 concentration of 0.1 mol / L and SnCl2 concentration of 0.2 mol / L. Terephthalic acid was added as a ligand, with a concentration of 0.3 mol / L, and the pH was adjusted to 3.5 using acetic acid to obtain a mixed solution. The mixed solution was transferred to a 100 mL polytetrafluoroethylene reactor and reacted at 120 °C for 12 h. After naturally cooling to room temperature, the mixture was filtered, washed three times with dimethylformamide, and then soaked for 24 h. The mixture was then vacuum dried at 60 °C for 12 h to obtain an octahedral TiSn-MOF.

[0069] 1 g of TiSn-MOF was immersed in 50 mL of GeCl4 solution (0.5 mol / L) using dimethylformamide as the solvent. The mixture was stirred until homogeneous and dispersed for 30 min. Then, 25% ammonia solution was used to reduce GeCl4 to Ge at 60 °C. The molar ratio of GeCl4 to ammonia in the ammonia solution was 1:1.33. After the reaction was complete, the solid was collected by centrifugation and washed three times with ethanol to obtain Ge@TiSn-MOF.

[0070] Ge@TiSn-MOF was heated from room temperature to 300℃ at a rate of 2℃ / min and held for 1 h to decompose the organic ligands and form a carbon framework. The temperature was then increased from 300℃ to 600℃ at a rate of 5℃ / min and held for 2 h to generate titanium oxide and tin oxide, completing the carbonization of the organic ligands. The calcined product was soaked in a 10% hydrochloric acid solution for 2 h, then washed with deionized water until neutral, filtered, and vacuum dried at 60℃ to obtain the negative electrode active material. In the negative electrode active material, the molar ratio of titanium to tin was 1:2, the mass ratio of the active substrate to the coating layer was 1:1, and the carbon content was 25 wt%.

[0071] Preparation of negative electrode sheet: The above-mentioned negative electrode active material, SBR and CMC are mixed in a mass ratio of 95:4:1, deionized water is added, and the mixture is stirred and mixed evenly to obtain a negative electrode slurry. The negative electrode slurry is coated on copper foil and dried in a vacuum drying oven at 110°C for 12 hours. After cold pressing, slitting and die cutting, the negative electrode sheet is obtained.

[0072] Preparation of positive electrode: LiNi 0.6 Mn 0.2 Co 0.2 O2, acetylene black, and polyvinylidene fluoride were mixed in a mass ratio of 95:3:2, and NMP was added. The mixture was stirred thoroughly to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated onto aluminum foil and dried in a vacuum drying oven at 110°C for 12 hours. After cold pressing, slitting, and die-cutting processes, the positive electrode sheet was obtained.

[0073] Preparation of electrolyte: Ethyl carbonate and diethyl carbonate are mixed, for example, at a mass ratio of 1:1. Thoroughly dried LiPF6 is dissolved in the mixed organic solvent. After mixing evenly, the electrolyte is obtained, wherein the content of LiPF6 is 1 mol / L.

[0074] Membrane selection: Polypropylene membrane was selected as the diaphragm, and the model of the polypropylene membrane is Celgard 2400.

[0075] The fabrication of lithium-ion batteries involves stacking positive electrode sheets, separators, and negative electrode sheets in sequence, with the separator positioned between the positive and negative electrode sheets to provide insulation. This stacking process yields an electrode assembly. The electrode assembly is then installed in a casing, baked at 80°C to remove moisture, injected with electrolyte, and sealed. Following these processes, the battery undergoes settling, hot and cold pressing, formation, clamping, and capacity testing to obtain a lithium-ion battery.

[0076] Battery fabrication for testing: Using a lithium metal sheet as the counter electrode, the lithium metal sheet and the aforementioned negative electrode sheet are assembled into a coin cell. The separator and electrolyte are the same as those used in lithium-ion batteries.

[0077] Example 2

[0078] In preparing the negative electrode active material, the concentration of tin chloride was 0.1 mol / L, and the molar ratio of titanium to tin in the negative electrode active material was 1:1. Other operations were consistent with those in Example 1.

[0079] Example 3

[0080] In preparing the negative electrode active material, the concentration of tin chloride was 0.3 mol / L, and the molar ratio of titanium to tin in the negative electrode active material was 1:3. Other operations were consistent with those in Example 1.

[0081] Example 4

[0082] In preparing the negative electrode active material, the concentration of tin chloride was 0.4 mol / L, and the molar ratio of titanium to tin in the negative electrode active material was 1:4. Other operations were consistent with those in Example 1.

[0083] Example 5

[0084] In preparing the negative electrode active material, the concentration of tin chloride was 0.05 mol / L, and the molar ratio of titanium to tin in the negative electrode active material was 1:0.5. Other operations were consistent with those in Example 1.

[0085] Example 6

[0086] In preparing the negative electrode active material, the concentration of GeCl4 solution was 1.0 mol / L, the molar ratio of titanium to tin in the negative electrode active material was 1:2, the mass ratio of active substrate to coating layer was 2:1, and the carbon content in the negative electrode active material was 18 wt%. Other operations were consistent with those in Example 1.

[0087] Example 7

[0088] In preparing the negative electrode active material, the concentration of GeCl4 solution was 1.5 mol / L, the molar ratio of titanium to tin in the negative electrode active material was 1:2, the mass ratio of active substrate to coating layer was 3:1, and the carbon content in the negative electrode active material was 10 wt%. Other operations were consistent with those in Example 1.

[0089] Example 8

[0090] In preparing the negative electrode active material, the concentration of GeCl4 solution was 0.25 mol / L, the molar ratio of titanium to tin in the negative electrode active material was 1:2, the mass ratio of active substrate to coating layer was 1:2, and the carbon content in the negative electrode active material was 33 wt%. Other operations were consistent with those in Example 1.

[0091] Example 9

[0092] In preparing the negative electrode active material, the concentration of GeCl4 solution was 0.17 mol / L, the molar ratio of titanium to tin in the negative electrode active material was 1:2, the mass ratio of active substrate to coating layer was 1:3, and the carbon content in the negative electrode active material was 40 wt%. Other operations were consistent with those in Example 1.

[0093] Example 10

[0094] In preparing the negative electrode active material, Ge@TiSn-MOF was heated from room temperature to 300°C at a rate of 2°C / min and held for 1 hour to decompose the organic ligands and form a carbon skeleton. Then, the temperature was increased from 300°C to 600°C at a rate of 5°C / min and held for 1 hour. Other operations were consistent with those in Example 1.

[0095] Example 11

[0096] In preparing the negative electrode active material, Ge@TiSn-MOF was heated from room temperature to 300°C at a rate of 2°C / min and held for 1 hour to decompose the organic ligands and form a carbon skeleton. Then, the temperature was increased from 300°C to 500°C at a rate of 5°C / min and held for 2 hours. Other operations were consistent with those in Example 1.

[0097] Example 12

[0098] In preparing the negative electrode active material, Ge@TiSn-MOF was heated from room temperature to 600°C at a rate of 5°C / min and held at that temperature for 2 hours. Other operations were consistent with those in Example 1.

[0099] Comparative Example 1

[0100] When preparing the negative electrode active material, tin chloride was not added, and other operations were consistent with those in Example 1.

[0101] Comparative Example 2

[0102] In preparing the negative electrode active material, titanium tetrachloride was not added, and other operations were consistent with those in Example 1.

[0103] Comparative Example 3

[0104] The negative electrode active material is selected as pure germanium particles, and other operations are consistent with those in Example 1.

[0105] Comparative Example 4

[0106] In preparing the negative electrode active material, tin chloride was replaced with zinc chloride, and other operations remained the same as in Example 1.

[0107] Comparative Example 5

[0108] In preparing the negative electrode active material, after obtaining Ge@TiSn-MOF, segmented calcination was not performed, and other operations were consistent with those in Example 1.

[0109] In this invention, lithium-ion batteries were prepared using different positive electrode active materials in Examples 1-12 and Comparative Examples 1-5, and the performance of the lithium-ion batteries was tested. The test results are shown in Tables 1-2.

[0110] Please see Figure 1 As shown, Figure 1The ideal structural diagram of the intermediate product is shown in the figure. Through this application, a coating layer with MOF structure can be formed on the surface of germanium particles, thereby suppressing the expansion of germanium particles and improving the stability and electrochemical performance of the negative electrode active material.

[0111] In one embodiment of the present invention, in order to obtain the mass ratio of the active substrate to the coating layer, the germanium content in the negative electrode active material is obtained by inductively coupled plasma optical emission spectroscopy (ICP-OES), thereby obtaining the mass ratio of the active substrate to the coating layer.

[0112] In one embodiment of the present invention, the carbon material content is quantified by the ID / IG value of Raman spectroscopy. The ID / IG value is typically between 0.9 and 1.0, at which point the carbon skeleton exhibits sufficient conductivity and abundant defects, which is beneficial for electrolyte wetting and ion transport.

[0113] In one embodiment of the present invention, the coating rate can be determined using methods known in the art. As an example, the coating rate can be determined by first analyzing the negative electrode active material using energy-dispersive X-ray spectroscopy (TEM-EDX) with a transmission electron microscope. Specifically, elemental analysis is performed on the outer periphery of the negative electrode active material particles in the TEM image using EDX. For example, elemental analysis of titanium or tin is performed to determine the titanium oxide or tin oxide coating on the surface of the active substrate. The coating portion can be identified based on the distribution of titanium or tin elements. Based on the observed entire periphery of the active substrate, the proportion of the coating portion is calculated, thus obtaining the coating rate of the coating layer.

[0114] In one embodiment of the present invention, when obtaining the first coulombic efficiency, the test batteries prepared in the above embodiments and comparative examples are charged to 1.5V at a constant current of 0.1A / g, and then discharged to 0.01V at 0.1A / g. The first discharge specific capacity and the charge specific capacity of the test battery are recorded, and the ratio of the first discharge specific capacity to the charge specific capacity is the first coulombic efficiency.

[0115] In one embodiment of the present invention, the test batteries prepared in the above embodiments and comparative examples are subjected to charge-discharge cycle tests at a current of 0.5A / g within a voltage range of 0.01V-1.5V. The specific capacity of the first discharge and the specific capacity of the discharge in each cycle are recorded. The ratio of the specific capacity of the discharge in the 100th cycle to the specific capacity of the first discharge is recorded as the capacity retention rate after 100 cycles.

[0116] Table 1. Partial characteristics of the negative electrode active materials in Examples 1-9 and Comparative Examples 1-4, and performance test results of the test batteries.

[0117]

[0118] Please refer to Table 1. Comparing Examples 1-9 and Comparative Example 3, it can be seen that when a coating layer with a MOF structure is formed on the surface of germanium particles, the initial coulombic efficiency and capacity retention after 100 cycles of the battery are significantly improved, indicating that the conductivity and stability of the negative electrode active material obtained in this application are improved.

[0119] Please refer to Table 1. Comparing Examples 1-4, it can be seen that as the molar ratio of Ti to Sn in the negative electrode active material increases, the initial discharge specific capacity increases. However, the initial coulombic efficiency and the capacity after 100 cycles initially increase and then decrease. This indicates that controlling the molar ratio of Ti to Sn can effectively improve the discharge specific capacity of the negative electrode active material. However, excessive Sn addition can also lead to a decrease in the structural stability of the negative electrode active material, thereby significantly reducing the cycle capacity retention rate. Therefore, controlling the molar ratio of Ti to Sn is crucial to ensure a balance between battery capacity and cycle performance.

[0120] Please refer to Table 1. Comparing Examples 1 and 6-9, it can be seen that as the germanium content in the negative electrode active material increases, the content of the coating layer decreases, the carbon content in the negative electrode active material decreases, the initial discharge specific capacity of the battery increases, the initial coulombic efficiency of the battery first increases and then decreases, and the capacity retention rate decreases after 100 cycles. This is because as the germanium content increases, the battery capacity increases, but the coating layer content decreases, which is insufficient to suppress the volume expansion of germanium particles, resulting in a decrease in the stability and conductivity of the negative electrode active material. Therefore, controlling the mass ratio of the active substrate to the coating layer is crucial to suppressing the expansion of the negative electrode active material while ensuring its energy density.

[0121] Please refer to Table 1. Comparing Example 1 and Comparative Examples 1-2, it can be seen that when the coating layer of the negative electrode active material only includes TiO2 and SnO2, the initial coulombic efficiency and capacity retention rate after 100 cycles of the battery decrease. This indicates that the coating layer cannot form a three-dimensional network buffer layer with both high structural stability and high lithium-ion transport capability on the surface of germanium particles through the synergistic effect of TiO2 and SnO2, which will lead to a significant reduction in the performance of the negative electrode active material.

[0122] Please refer to Table 1. Comparing Example 1 and Comparative Example 4, it can be seen that when other metals are chosen to replace Sn, such as replacing tin oxide with zinc oxide in the coating layer of the negative electrode active material, the initial coulombic efficiency and capacity retention after 100 cycles of the battery decrease. This indicates that titanium oxide and tin oxide have excellent synergistic effects, forming a three-dimensional network buffer with high structural stability and high lithium-ion transport capability, thereby improving battery performance.

[0123] Table 2 shows the performance test results of the test batteries in Examples 1, 10-12, and Comparative Example 5.

[0124]

[0125] Please refer to Table 2. Comparing Examples 1, 10-12, and Comparative Example 5, it can be seen that without carbonization coating after forming Ge@TiSn-MOF, the initial discharge specific capacity and cycle performance of the battery deteriorate. This indicates that without carbon coating, the organic ligands dissolve in the electrolyte within the battery, causing the coating layer to collapse. This reduces the structural stability and conductivity of the negative electrode active material, resulting in poorer swelling suppression performance and consequently, poorer battery cycle performance.

[0126] Please refer to Table 2. Comparing Examples 1 and 10-11, it can be seen that when the second calcination temperature is too low or the calcination time is too short, the initial coulombic efficiency and capacity retention after 100 cycles of the battery decrease. This may be due to incomplete carbonization of the organic ligands, leaving some organic ligands in the negative electrode active material. During battery cycling, the coating layer collapses due to the shedding of the remaining organic ligands, resulting in poor structural stability of the negative electrode active material. Therefore, controlling the calcination temperature and time can improve the structural stability of the negative electrode active material, reduce impurities, and reduce side reactions in the battery, leading to better coulombic efficiency and capacity retention.

[0127] Please refer to Table 2. Comparing Examples 1 and 12, it can be seen that when the first calcination is omitted, the capacity retention rate of the battery decreases significantly after 100 cycles. This may be because, when the first calcination is omitted, the decarboxylation reaction of the organic ligands is insufficient, lacking the initial carbon skeleton formation step. At high temperatures, some organic ligands vaporize. After carbonization, the carbon cannot maintain the structure of the organic ligands in the MOF structure, weakening the ability to suppress expansion, thus leading to a decrease in the stability of the negative electrode active material.

[0128] This invention also provides an electronic device comprising at least one of the aforementioned lithium-ion batteries, which provides electrical energy. The electronic device can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, or power tool, etc. In one embodiment of this invention, the vehicle is, for example, a new energy vehicle, which can be a pure electric vehicle, a hybrid electric vehicle, or a range-extended electric vehicle, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. The electronic device includes the aforementioned lithium-ion battery, and therefore the advantages of including the aforementioned lithium-ion battery are not elaborated here.

[0129] In summary, this invention proposes an anode active material, its preparation method, and its application. By setting a carbon-doped titanium-tin bimetallic oxide coating layer on germanium particles, the expansion stress of the active substrate can be buffered, and the tin element can improve conductivity. Through the synergistic effect of the titanium-tin bimetallic oxide, the electrochemical activity can be significantly enhanced. While suppressing the volume expansion of germanium particles, it promotes electron and ion transport, thereby improving the electrochemical performance of the anode active material. Specifically, the carbon in the coating layer possesses the three-dimensional structure of organic ligands in the MOF structure, and tin oxide and titanium oxide occupy the metal node positions in the MOF. That is, the coating layer possesses the highly stable stacking and porous structure of the MOF structure, thus forming a three-dimensional network buffer layer on the surface of the active substrate. This buffers the expansion stress of the active substrate and improves the stability and conductivity of the anode active material. The anode active material exhibits high reversible capacity and excellent charge-discharge kinetics. By controlling the molar ratio of titanium oxide and tin oxide, the excellent synergistic effect of titanium oxide and tin oxide is achieved, and the resulting coating layer possesses a three-dimensional network buffer layer with high structural stability and high lithium-ion transport capacity. By first forming TiSn-MOF, then forming germanium in situ, and finally carbonizing the organic ligand, the coating layer is ensured to have a MOF structure.

[0130] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0131] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A negative electrode active material, characterized in that, include: An active substrate, wherein the active substrate comprises germanium particles; A coating layer is disposed on at least a portion of the surface of the active substrate, the coating layer being a carbon-doped titanium-tin bimetallic oxide; the coating layer is obtained by carbonizing the organic ligands in the titanium-tin bimetallic organic framework compound after forming the compound.

2. The negative electrode active material according to claim 1, characterized in that, The mass ratio of the active substrate to the coating layer is 3:1 to 1:

2.

3. The negative electrode active material according to claim 1, characterized in that, In the coating layer, the molar ratio of titanium to tin is 1:1 to 1:

3.

4. The negative electrode active material according to claim 1, characterized in that, The carbon content in the negative electrode active material is 10wt%-40wt%.

5. A method for preparing a negative electrode active material, characterized in that, include: Titanium source precursor and tin source precursor are added to solvent, then organic ligand and pH adjuster are added, and the reaction is carried out at preset pH value, preset temperature and preset time. After filtration and drying, titanium-tin bimetallic organic framework compound is obtained. The titanium-tin bimetallic organic framework compound was immersed in a germanium solution, a reducing agent was added and the reaction was carried out at the reaction temperature, germanium particles were formed in the titanium-tin bimetallic organic framework compound, and the mixture was filtered and dried to obtain an intermediate product. Under an inert gas atmosphere, the intermediate product is calcined in stages, then washed and dried to obtain the negative electrode active material.

6. The method for preparing the negative electrode active material according to claim 5, characterized in that, The titanium source precursor includes at least one of titanium tetrachloride, titanium trichloride, titanium oxysulfate, or tetraisopropyl titanate, and the tin source precursor includes at least one of tin dichloride, tin acetate, tin oxalate, or tin dioxide. And / or, the solvent includes at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide, or ethyl acetate; And / or, the organic ligand comprises at least one of terephthalic acid, 2-aminoterephthalic acid, 2-hydroxyterephthalic acid, phthalic acid, isophthalic acid, dodecylbenzoic acid, or fumaric acid; And / or, the pH adjuster includes at least one of hydrochloric acid, nitric acid, sulfurous acid, dilute sulfuric acid, acetic acid, phytic acid, citric acid, succinic acid, or tartaric acid; And / or, the reducing agent includes at least one of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, or ammonia water; And / or, the solute in the germanium solution includes at least one of germanium tetrachloride, germanium dichloride, germanium sulfide, or germanium disulfide, and the solvent in the germanium solution includes at least one of water, methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, acetone, dimethylformamide, dimethyl sulfoxide, or ethyl acetate.

7. The method for preparing the negative electrode active material according to claim 5, characterized in that, The molar ratio of titanium in the titanium source precursor to tin in the tin source precursor is 1:1 to 1:

3. And / or, the total molar amount of the titanium source precursor and the tin source precursor and the molar ratio of the organic ligand are 2:3-4:3; And / or, the preset pH range is 2.5-4.5, the preset temperature is 110℃-140℃, and the preset time is 10h-16h; And / or, the mass ratio of the titanium-tin bimetallic organic framework compound to the solute in the germanium solution is 1:2.5-1:17; And / or, the concentration of the germanium solution is 0.25 mol / L to 1.5 mol / L; And / or, the molar ratio of the solute to the reducing agent in the germanium solution is greater than 1:1.

33. And / or, the reaction temperature is 50℃-70℃.

8. The method for preparing the negative electrode active material according to claim 5, characterized in that, The segmented calcination includes: The intermediate product is heated from room temperature to a first temperature at a first heating rate, and held at that temperature for a first time; and The first temperature is raised to the second temperature at a second heating rate, and the temperature is maintained for a second time.

9. The method for preparing the negative electrode active material according to claim 8, characterized in that, The first heating rate is 1℃ / min-10℃ / min, the first temperature is 250℃-350℃, and the first time is 1h-1.5h; The second heating rate is 1℃ / min-10℃ / min, the second temperature is 500℃-700℃, and the second time is 1.5h-3h.

10. A lithium-ion battery, characterized in that, It includes the negative electrode active material according to any one of claims 1-4 or the negative electrode active material obtained by the preparation method according to any one of claims 5-9.

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