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CN118299549A - Negative electrode material and battery - Google Patents

Negative electrode material and battery Download PDF

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Publication number
CN118299549A
CN118299549A CN202410720666.8A CN202410720666A CN118299549A CN 118299549 A CN118299549 A CN 118299549A CN 202410720666 A CN202410720666 A CN 202410720666A CN 118299549 A CN118299549 A CN 118299549A
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anode material
negative electrode
metal
electrode material
anode
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CN118299549B (en
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梁腾宇
庞春雷
石晓太
任建国
贺雪琴
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Shenzhen Dingyuan New Materials Technology Co ltd
BTR New Material Group Co Ltd
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Shenzhen Dingyuan New Materials Technology Co ltd
BTR New Material Group Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application provides a negative electrode material and a battery, wherein the negative electrode material comprises an active substance, the active substance comprises Si element, O element and metal M element, and the metal M is at least one of metals with electronegativity of < 1.8; firing 1g of anode material to constant weight at 750-1000 ℃ under oxygen-containing atmosphere, and then carrying out dissolution treatment by using 100mL of mixed acid to obtain a first digestion solution of the anode material; testing the mass content M 1 of the M element in the first digestion liquid by adopting an electrically coupled plasma atomic emission spectrum; washing 100g of anode material with 1mol/L hydrochloric acid for 2h, drying the separated solid, taking 1g of dried solid, burning the solid to constant weight at 750 ℃ in an oxygen-containing atmosphere, and carrying out dissolution treatment by using 100mL mixed acid to obtain a second digestion solution of the anode material; and testing the mass content M 2,0.8≤m2/m1 of M element in the digestion solution to be less than or equal to 1. The negative electrode material and the battery provided by the application can reduce the volume expansion of the negative electrode material and improve the rate capability and the cycle stability of the negative electrode material.

Description

Negative electrode material and battery
Technical Field
The application relates to the technical field of negative electrode materials, in particular to a negative electrode material and a battery.
Background
The electric new energy automobile is a future development direction of the automobile market, and the core component of the electric new energy automobile is a lithium ion battery. With the development of the market, the demand for high-capacity density batteries is higher and higher, and the adoption of novel high-specific-volume anode and cathode materials is one of important methods for improving the energy density of the batteries.
New materials such as metals, oxides, and metal alloys are increasingly used as active materials for negative electrode materials to search for various ways of increasing the energy density of batteries. Taking a silicon-based anode material as an example, the silicon-based anode material is taken as one of the active materials, is generally regarded as an anode material of the next generation, has the advantages of ultrahigh theoretical specific capacity (4200 mAh/g) and lower lithium removal potential (< 0.5V), and silicon has a voltage platform slightly higher than that of graphite, is difficult to cause surface lithium precipitation during charging, has better safety performance and the like, and is worthy of favor. However, the silicon cathode has a severe volume expansion effect in the circulation process, so that the material is pulverized and crushed, and the circulation attenuation of the battery is rapid. The silicon oxygen material has a structure that Si is dispersed in a SiO 4 framework, so that the volume expansion effect of the silicon oxygen material is improved compared with that of silicon. However, when the silicon oxide material is used for inserting lithium for the first time, oxygen in the silicon oxide material can be separated from active lithium ions in the electrolyte to form a solid electrolyte membrane, so that irreversible loss of the active lithium ions is caused, larger irreversible capacity is formed, and the first coulomb efficiency of the anode material is reduced.
Disclosure of Invention
The application provides the anode material and the battery, which can comprehensively improve the first coulomb efficiency and the cycle stability of the anode material and reduce the volume expansion of the anode material.
In a first aspect, the present application provides a negative electrode material, the negative electrode material including an active material including an Si element, an O element, and a metal M element, the metal M being selected from at least one of metals having electronegativity < 1.8;
Burning 1g of the anode material to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, dissolving 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in a volume ratio of 1:1:3 until bubbles are not generated in the solution, and carrying out solid-liquid separation to obtain a first digestion solution of the anode material; testing the mass content M 1 of the M element in the first digestion liquid by adopting an electrically coupled plasma atomic emission spectrum;
Washing 100g of the anode material with 100mL of hydrochloric acid with the concentration of 1mol/L for 2 hours, drying the separated solid, taking 1g of dried solid, burning the solid to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, and carrying out dissolution treatment by using 100mL mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 with the volume ratio of 1:1:3 until bubbles are not generated in the solution, so as to obtain a second digestion solution of the anode material after solid-liquid separation; and testing the mass content M 2,0.8≤m2/ m1 of the M element in the second digestion liquid by adopting an electric coupling plasma atomic emission spectrum to be less than or equal to 1.
In some embodiments, 50000ppm or less m 1 or less 200000ppm; and/or 40000ppm or less m 2 or less 160000ppm.
In some embodiments, a scanning electron microscope and an energy dispersion spectrometer are used for scanning and testing particle sections of the anode material, 10 anode material particles are randomly selected, each particle section is selected for testing Si element, O element and metal M element, the mass percentage P M% of the metal M element in each particle is measured, the variation coefficient c=sigma/mu of P M is calculated, the sigma is the standard deviation of P M of 10 particles, the mu is the average value of P M of 10 particles, and the variation coefficient c is less than 0.5.
In some embodiments, 100g of the negative electrode material is added to 1000g of water, and the viscosity of the resulting mixed solution after stirring for 30 minutes is <50cps.
In some embodiments, the negative electrode material comprises at least one of a M 2SiO3 characteristic peak, a MSiO 3 characteristic peak, a M 2(SiO3)3 characteristic peak, and a M (SiO 3)2 characteristic peak) using X-ray diffraction analysis.
In some embodiments, the metal M is selected from at least one of Li, K, na, mg, ca, al, la, zn, ti and Mn.
In some embodiments, the metal M comprises Mg.
In some embodiments, in the anode material, the Si is present in a form including at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, a composite of crystalline silicon and amorphous silicon.
In some embodiments, in the anode material, the metal M is present in a form including at least one of a silicate of M, an oxide of M.
In some embodiments, the active material includes silicon oxide, the silicon oxide includes silicon element and oxygen element, and an atomic ratio of the silicon element to the oxygen element is 0 to 2, and does not include 0.
In some embodiments, the anode material further comprises a carbon material, the surface of the active material and/or between the active material particles having the carbon material.
In some embodiments, the mass content of the carbon element in the anode material is 1% -40%.
In some embodiments, the mass content of oxygen element in the anode material is 10% -35%.
In some embodiments, the specific surface area of the negative electrode material is less than or equal to 20m 2/g.
In some embodiments, the median particle diameter D 50 of the negative electrode material is 1 μm to 20 μm.
In some embodiments, the pH of the negative electrode material satisfies: the pH value is more than or equal to 8 and less than or equal to 10.
In a third aspect, the present application provides a battery comprising the anode material as described in the first aspect or the anode material as described in the second aspect.
The technical scheme of the application has at least the following beneficial effects:
Firstly, the active substance of the anode material provided by the application comprises Si element, O element and metal M element. The content of M element in the digestion liquid of the anode material after mixed acid pickling is M 1, the content of M element in the digestion liquid after 1mol/L hydrochloric acid pickling is controlled within the range, the ratio of M element in the digestion liquid after mixed acid pickling is M 2,0.8≤m2/ m1≤1,m2/ m1, therefore, the metal element M in the anode material before and after hydrochloric acid pickling is not dissolved out in a large amount, the overall density of the anode material is high, silicon oxide and silicate in the anode material are uniformly distributed, the surface of the anode material is not provided with a plurality of M silicate for dissolution, the overall density of active substances of the anode material is high, even a small amount of holes formed on the surface after dissolution are extremely small, hydrochloric acid is difficult to permeate into the active substances and dissolve the M silicate in the particles, the metal M silicate is dispersed and distributed in the silicon oxide, the compound of the metal M can be embedded on silicon oxide particles or between the silicon oxide particles, the uniform doping of the metal M in the active substances can be realized, the density of the active substances is effectively improved, the metal in the anode material is hardly dissolved out in the process of charge and discharge, the gas production is reduced, the initial stability of the anode material and the volume of the anode material are comprehensively improved, and the volume of the anode material is reduced.
Drawings
Fig. 1 is a schematic partial structure of a device for preparing a negative electrode material according to an embodiment of the present application.
Fig. 2 is an XRD pattern of the negative electrode material prepared in example 1 of the present application.
Detailed Description
The following description is of the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, it is possible to make several improvements and modifications without departing from the principle of the embodiments of the present application, and these improvements and modifications are also considered as the protection scope of the embodiments of the present application.
In a first aspect, the present application provides a negative electrode material, the negative electrode material comprising an active material, the active material comprising an element Si, an element O and an element M, the metal M being selected from at least one of metals having an electronegativity of < 1.8;
Burning 1g of anode material to constant weight at 750-1000 ℃ under oxygen-containing atmosphere, dissolving with 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in a volume ratio of 1:1:3 until bubbles are not generated in the solution, and carrying out solid-liquid separation to obtain a first digestion solution of the anode material; testing the mass content M 1 of the M element in the first digestion liquid by adopting an electrically coupled plasma atomic emission spectrum;
Washing 100g of the anode material with 100mL of hydrochloric acid with the concentration of 1mol/L for 2 hours, drying the separated solid, taking 1g of dried solid, burning the solid to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, and carrying out dissolution treatment by using 100mL mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 with the volume ratio of 1:1:3 until bubbles are not generated in the solution, so as to obtain a second digestion solution of the anode material after solid-liquid separation; and testing the mass content M 2,0.8≤m2/ m1 of the M element in the second digestion liquid by adopting an electric coupling plasma atomic emission spectrum to be less than or equal to 1.
The active substances of the anode material comprise Si element, O element and metal M element. The content of M element in the digestion liquid of the anode material after mixed acid pickling is M 1, the content of M element in the digestion liquid after 1mol/L hydrochloric acid pickling is controlled within the range, the ratio of M element in the digestion liquid after mixed acid pickling is M 2,0.8≤m2/ m1≤1,m2/ m1, therefore, the metal element M in the anode material before and after hydrochloric acid pickling is not dissolved out in a large amount, the overall density of the anode material is high, silicon oxide and silicate in the anode material are uniformly distributed, the surface of the anode material is not provided with a plurality of M silicate for dissolution, the overall density of active substances of the anode material is high, even a small amount of holes formed on the surface after dissolution are extremely small, hydrochloric acid is difficult to permeate into the active substances and dissolve the M silicate in the particles, the metal M silicate is dispersed and distributed in the silicon oxide, the compound of the metal M can be embedded on silicon oxide particles or between the silicon oxide particles, the uniform doping of the metal M in the active substances can be realized, the density of the active substances is effectively improved, the metal in the anode material is hardly dissolved out in the process of charge and discharge, the gas production is reduced, the initial stability of the anode material and the volume of the anode material are comprehensively improved, and the volume of the anode material is reduced. It will be appreciated that the dissolution process described above may be repeated with the mixed acid until the solution no longer produces bubbles.
In some embodiments, 0.8.ltoreq.m 2/ m1≤1,m2/ m1 may be specifically 0.8, 0.82, 0.83, 0.84, 0.85, 0.88, 0.9, 0.91, 0.92, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or 1, etc., but may also be other values within the above range, and is not limited thereto. When the number of M elements in the negative electrode material is plural, the mass content of the fully dissolved M element in the negative electrode material is the sum of the mass contents of the plural M elements. When M 2/ m1 is less than 0.8, the compound of the metal M in the anode material is easy to be washed out, the compound of the metal M is mainly distributed on the surface of the anode material particles, or the compound of the metal M is partially clustered together and is not uniformly dispersed with silicon oxide, a relatively large pore canal is left after the compound of the metal M on the surface is washed out, and acid enters the anode material particles along the pore canal and dissolves the compound of the metal M partially positioned in the particles. Namely, the distribution of the metal M compound and Si in the anode material is not uniform enough, the metal dissolution is increased and the gas production is increased in the charge and discharge process. Preferably, 0.9.ltoreq.m 2/ m1.ltoreq.0.99.
In some embodiments, 1g of anode material is burned to constant weight at 750-1000 ℃ in oxygen-containing atmosphere, and then 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 with the volume ratio of 1:1:3 is used for dissolution treatment until the solution does not generate bubbles any more, and the digestion solution of the anode material is obtained after solid-liquid separation; adopting an electric coupling plasma atomic emission spectrum to test the mass content M 1,50000ppm≤m1 of M element in the digestion liquid to be less than or equal to 200000ppm; specifically, 50000ppm, 70000ppm, 80000ppm, 90000ppm, 100000ppm, 120000ppm, 150000ppm, 180000ppm, 190000ppm, 200000ppm, or the like may be used, and other values within the above range are not limited thereto.
In some embodiments, after 100g of anode material is pickled with 100mL of 1mol/L hydrochloric acid for 2 hours, drying the separated solid, taking 1g of dried solid, burning to constant weight at 750-1000 ℃ in oxygen-containing atmosphere, dissolving with 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in volume ratio of 1:1:3 until the solution does not generate bubbles any more, repeatedly adding one time of mixed acid until the solution still has no bubbles, and obtaining digestion solution of the anode material after solid-liquid separation; adopting an electrically coupled plasma atomic emission spectrum to test the mass content M 2,50000ppm≤m2 of M element in the digestion liquid to be less than or equal to 160000ppm; specifically, 50000ppm, 70000ppm, 80000ppm, 90000ppm, 100000ppm, 120000ppm, 150000ppm, 155000ppm, 160000ppm, or the like may be used, and other values within the above range are not limited thereto.
It can be understood that after the mass content M 1 of the M element in the digestion solution of the anode material subjected to mixed acid pickling and hydrochloric acid pickling, the difference between the mass content M 2,m2、m1 of the M element in the digestion solution of the anode material subjected to mixed acid pickling is smaller, so that the overall density of the anode material is high, and the anode material is not corroded to form pores even if subjected to hydrochloric acid pickling, thereby increasing the dissolution amount of the M element. In the application, M 2/ m1 is controlled within the range, the uniform distribution of M, si and O in the active substances of the anode material is ensured, the presence of the metal M element can reduce the release of oxygen in silicon oxide, reduce irreversible capacity attenuation of the anode material, improve the first coulomb efficiency of the anode material and improve the circulation stability of the anode material.
In some embodiments, a scanning electron microscope and an energy dispersion spectrometer are used for scanning and testing particle sections of the anode material, 10 anode material particles are randomly selected, each particle section is selected for testing Si element, O element and metal M element, the mass percentage P M% of the metal M element in each particle is measured, the variation coefficient c=sigma/mu of P M is calculated, the sigma is the standard deviation of P M of 10 particles, the mu is the average value of P M of 10 particles, and the variation coefficient c is less than 0.5.
In the scheme, the mass percentages of Si element, O element and metal M element in each anode material particle obtained through the calibration of the energy dispersion spectrometer, as the variation coefficient c of P M is smaller than 0.5, the distribution uniformity degree of the metal M element in each anode material particle in the anode material particle is close, the metal M element in the anode material is uniformly doped in an active substance, the oxygen extraction in silicon oxide can be reduced due to the existence of the metal M element, the irreversible capacity attenuation of the anode material is reduced, and the first coulomb efficiency of the anode material is improved; in addition, the variation coefficient can also show the density of the active substance, and in the range, the overall density of the anode material is high, so that the cycling stability of the anode material is improved, and the volume expansion of the anode material is reduced. When the number of M elements in the anode material is plural, the mass percentage of the metal M element in the anode material particles is the sum of the mass percentages of the plural M elements, that is, P M is the total mass percentage of the plural metal M elements, and the calculation is also performed based on the total mass percentage when calculating the coefficient of variation c.
In some embodiments, 100g of the negative electrode material is added to 1000g of water, and after stirring for 30 minutes, the viscosity of the solid-liquid separated liquid is <50cps. The viscosity of the solution was low because the amount of dissolved metal M element in the anode material was extremely small, and it was found that the degree of densification of the anode material was high.
In some embodiments, the negative electrode material comprises at least one of a characteristic peak of M 2SiO3, a characteristic peak of MSiO 3, a characteristic peak of M 2(SiO3)3, and a characteristic peak of M (SiO 3)2) wherein the characteristic peak of M 2SiO3 is a silicate of a monovalent metal M, such as a silicate of Li, K, na.
In some embodiments, the metal M comprises at least one of Li, K, na, mg, ca, al, la, zn, ti and Mn.
In some embodiments, in the anode material, the compound of the metal M includes at least one of a silicate of M, an oxide of M.
In some embodiments, the metal M comprises magnesium and the magnesium-containing compound comprises MgO, mgSiO 3, and Mg 2SiO4.
In some embodiments, the silicon oxide includes a mass of a silicon element and a mass of an oxygen element, and an atomic ratio of the mass of the silicon element to the mass of the oxygen element is 0 to 2, and does not include 0. The atomic ratio of the mass of the silicon element to the mass of the oxygen element may be 0.05、0.11、0.21、0.26、0.31、0.41、0.51、0.59、0.61、0.69、0.71、0.74、0.76、0.79、0.89、0.99、1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9, 2, or the like, and is not limited herein. Preferably, the atomic ratio of the mass of the silicon element to the mass of the oxygen element is 0 to 1, and 0 is not included.
In some embodiments, the silicon oxide has a chemical formula of SiO x, wherein 0< x.ltoreq.2, x may be 0.05、0.11、0.21、0.26、0.31、0.41、0.51、0.59、0.61、0.69、0.71、0.74、0.76、0.79、0.89、0.99、1、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9, 2, etc., and is not limited herein. Preferably 0< x <1. The silicon oxygen material may be a material in which silicon particles are dispersed in SiO 2, or a material having a tetrahedral structural unit in which silicon atoms are located at the center of the tetrahedral structural unit and silicon atoms and/or oxygen atoms are located at the four vertices of the tetrahedral structural unit.
In some embodiments, the anode material further comprises a carbon material, with the surface of the active material and/or between the active material particles having the carbon material. The active substances are dispersed in the carbon material, and the carbon material constructs a conductive network for the active substances, so that the defect of poor conductivity of the active substances (such as a silicon oxide material SiO x) is overcome, and the capacity exertion and the circulation stability of the active substances are facilitated. Specifically, the carbon material may be located on the surface of the active material, may be located between the active material particles, or may be formed by secondary granulation and coating of primary particles of the active material.
In some embodiments, the carbon material is a non-graphitic carbon material, such as may be amorphous carbon, carbon nanoparticles, and the like. In other embodiments, the carbon material may also be a graphite-based carbon material, such as graphene, natural graphite, artificial graphite, graphite oxide, or the like. Optionally, the non-graphitic carbon material is at least partially on the surface of the active material and forms a carbon layer.
In some embodiments, the thickness of the carbon layer is 1nm to 1000nm, specifically, 1nm, 5nm, 10nm, 15nm, 20nm, 50nm, 80nm, 100nm, 150nm, 200nm, 400nm, 500nm, 700nm, 800nm, 900nm, 1000nm, etc., and is not limited thereto. The carbon layer is too thick, the carbon ratio is too high, and the negative electrode material with high specific capacity is not easy to obtain; the carbon layer is too thin, which is unfavorable for increasing the conductivity of the anode material and has weaker volume expansion inhibition performance on the material, resulting in poorer long-cycle performance. Preferably, the thickness of the carbon layer is 50 nm-800 nm; more preferably, the thickness of the carbon layer is 100nm to 500nm.
In some embodiments, the mass content of carbon element in the anode material is 1% -40%; specifically, the content may be 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 35% or 40%, or the like, and other values within the above range are also possible, and the present invention is not limited thereto.
In some embodiments, the mass content of oxygen element in the anode material is 10% -35%; specifically, 10%, 12%, 15%, 18%, 20%, 25%, 28%, 35%, or the like may be used, and other values within the above range may be used, without limitation.
In some embodiments, the specific surface area of the negative electrode material is less than or equal to 20m 2/g; specifically, 1.0 m2/g、1.5 m2/g、1.8 m2/g、2.0 m2/g、2.5 m2/g、3.0 m2/g、3.6 m2/g、4.0m2/g、5 m2/g、5.5 m2/g、6.0m2/g、7.0 m2/g、8.0 m2/g、8.5 m2/g、10.0 m2/g、12.0 m2/g、15.0 m2/g、18.0 m2/g or 20.0 m 2/g may be used, but the present invention is not limited to the values listed, and other values not listed in the range are equally applicable. The specific surface area of the anode material is controlled within the above range, which is advantageous for improving the first coulombic efficiency of the anode material. When the specific surface area of the anode material is too large, side reactions between the anode material and the electrolyte are increased, more active lithium ions are consumed, and the initial coulomb efficiency of the anode material is reduced. Preferably, the specific surface area of the negative electrode material is 10m 2/g or less.
In some embodiments, the pH of the negative electrode material satisfies: the pH value is 8.ltoreq.10, and may be specifically 8, 8.5, 9, 9.5, 9.8 or 10, etc., without limitation.
In some embodiments, the median particle diameter D 50 of the negative electrode material is 1 μm to 20 μm, specifically 1 μm, 2 μm, 2.5 μm, 3.5 μm, 4 μm, 6 μm, 8 μm, 9.5 μm, 10 μm, 12.5 μm, 15 μm, or 20 μm, etc., but not limited to the recited values, and other non-recited values within the range of values are equally applicable. The median diameter D 50 of the anode material is controlled in the range, which is favorable for improving the lithium ion diffusion efficiency of the anode material and comprehensively improving the multiplying power performance of the anode material.
In a second aspect, the present application provides a method for preparing a negative electrode material, comprising the steps of:
S100, respectively placing the raw materials of the metal M and the silicon oxygen material into two cavities of a vacuum furnace, vacuumizing the two cavities to less than 1Pa, and heating.
In some embodiments, as shown in fig. 1, two chambers 10 and an air outlet 20 are arranged in a T shape, each chamber has two oppositely arranged outlets 11, and the outlets 11 and the air outlets 20 of the two chambers are all provided with valves and are in a closed state. And stopping heating when the pressure in the cavity exceeds 1Pa in the heating process, and opening the corresponding air outlet valve. And if the air outlet valves of the two chambers are opened, opening the valve of the air outlet.
It will be appreciated that both chambers are heated to a temperature suitable for evaporation, and when gas is generated, the gases are mixed and deposited after being mixed uniformly. Because the outlets 11 of the two chambers are opposite and are arranged in a staggered manner, gas can be subjected to front convection and uniformly mixed at different positions of the chamber, and then enters the cooling area through the air outlet 20 after front convection, so that the mixing is more uniform, and M, si and O elements in the active substances obtained through cooling can be uniformly dispersed and distributed, and the M is uniformly doped with the active substances.
In some embodiments, the starting material for preparing the silicone material comprises at least one of Si, a mixture of SiO x and SiO 2, a mixture of SiO x and Si, and a mixture of Si and SiO 2, wherein 0 < x < 2.
In some embodiments, the metal M feedstock is selected from at least one of elemental metal, metal oxide.
In some embodiments, the metal M is selected from at least one of Li, K, na, mg, ca, al, la, zn, ti and Mn.
In some embodiments, the mass ratio of the metal M feedstock to the feedstock of the silicon oxygen material is 1: (5-10), specifically, may be 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, etc., but of course, other values within the above range may be used, and the present invention is not limited thereto.
And S200, raising the temperature of the two chambers to above 1400 ℃, and opening three valves to enable the gas to be rapidly discharged and deposited, so as to obtain an intermediate.
In some embodiments, the temperature of the elevated temperature treatment is greater than or equal to 1400 ℃, specifically 1400 ℃, 1500 ℃, 1550 ℃, 1575 ℃, 1600 ℃, 1650 ℃, 1700 ℃, 1800 ℃, 1900 ℃, or 2000 ℃. It is understood that the above temperatures are not limited to the recited values, and that other non-recited values within the range of values are equally applicable.
In the technical scheme, after the two chambers are guaranteed to generate steam, the temperature is raised to more than 1400 ℃, so that the steam generation efficiency is improved, the gas is deposited after being mixed by rapid convection, and the uniformity of the deposition is improved.
And step S300, adjusting the particle size of the intermediate until the median particle size D 50 of the intermediate is less than 10 mu m, and obtaining the active substance.
In some embodiments, the median particle diameter D 50 of the intermediate may be adjusted by jet milling, mechanical disruption, or the like.
And step S400, performing carbon coating treatment on the active material to obtain the anode material.
It will be appreciated that during the carbon coating process, the metal M element reacts with the silicon oxide to obtain oxygen evolved from the silicon oxide, producing SiO y and a silicate of metal M, where 0< y <1. So that the first coulombic efficiency of the anode material can be improved.
In one embodiment, the carbon coating treatment is specifically at least one of solid phase carbon coating, liquid phase carbon coating and gas phase carbon coating.
Specifically, the step of carbon coating treatment specifically includes: and heating the active material obtained by cooling treatment, and then introducing protective gas and carbon source gas, and carrying out thermal cracking on the carbon source gas to obtain the anode material.
In some embodiments, the carbon source gas used for the vapor phase carbon coating comprises hydrocarbons.
In some embodiments, the carbon source gas comprises at least one of methane, acetylene, ethylene, ethane, propane, propylene, propyne, acetone, and benzene.
In some embodiments, the chemical vapor deposition apparatus comprises at least one of a rotary chemical vapor deposition reactor, a plasma enhanced chemical vapor deposition reactor, a chemical vapor deposition tube furnace, and a fluidized bed. Specifically, the chemical vapor deposition apparatus is at least one of a rotary kiln and a box-type furnace.
In some embodiments, the temperature of thermal cracking is 600 ℃ to 1000 ℃ and the time of thermal cracking is 2 hours to 20 hours.
In some embodiments, the carbon source gas is vented under a protective gas.
In some embodiments, the protective gas comprises at least one of nitrogen, helium, neon, argon, krypton, and xenon.
In some embodiments, the step of carbon coating treatment specifically includes: and (3) carbonizing the mixture obtained by mixing the active material obtained by the cooling treatment with the solid-phase carbon source to obtain the anode material.
In some embodiments, the solid phase carbon source comprises at least one of a saccharide, an ester, a hydrocarbon, an organic acid, and a high molecular polymer. Specifically, the resin composition can be at least one of polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, polyacrylic acid, polyethylene glycol, polypyrrole, polyaniline, sucrose, glucose, maltose, citric acid, asphalt, furfural resin, epoxy resin and phenolic resin.
In some embodiments, the cooled product may be mixed with the carbon source in a manner such as VC mixing, fusion, ball milling, three-dimensional mixing, fluidized bed mixing, and the like.
In some embodiments, the mixing is performed in a fusion machine with a fusion time of 0.5h-2h and a fusion machine speed of 500 r/min-5000 r/min.
In some embodiments, the mass ratio of solid phase carbon source to active material is 5: (5-95).
In some embodiments, the carbonization treatment is at a temperature of 500 ℃ to 1000 ℃ for a time of 2 hours to 20 hours.
In some embodiments, the apparatus used for solid-phase carbon coating is at least one of a rotary kiln, a box furnace, a roller kiln, a tunnel kiln, and a pusher kiln.
In some embodiments, the protective gas may be at least one of nitrogen, argon, helium, neon, krypton, and xenon.
The liquid-phase carbon coating process comprises the steps of uniformly mixing a cooled product with a carbon source, then placing the mixture in a furnace, introducing protective gas, and carrying out heat treatment to crack and coat the carbon source on the surface of the cooled product.
In some embodiments, the carbon source used for the liquid phase carbon coating is an organic carbon source, and specifically may be low temperature liquid phase pitch, furfuryl alcohol, glycidyl methacrylate, triethylene glycol dimethacrylate, and the like.
In some embodiments, the protective gas may be at least one of nitrogen, argon, helium, neon, krypton, and xenon.
In some embodiments, the heat treatment temperature is 600 ℃ to 1000 ℃.
Further, the method further comprises: and screening and demagnetizing the carbonized material to obtain the cathode material.
In some embodiments, the screening mode is any one of a fixed screen, a roller screen, a resonance screen, a roller screen, a vibrating screen and a chain screen, the screening mesh number is 100-500 meshes, specifically, the screening mesh number can be 100 meshes, 200 meshes, 250 meshes, 325 meshes, 400 meshes, 500 meshes and the like, preferably, the screening mesh number is 250 meshes, and the median particle diameter of the anode material is controlled within the range, so that the improvement of the processing performance of the anode material is facilitated.
In some embodiments, the device for removing magnetism is any one of a permanent magnet cylinder type magnetic separator, an electromagnetic iron removing machine and a pulsating high gradient magnetic separator, and the purpose of removing magnetism is to finally control the content of magnetic substances in the cathode material, so that the discharge effect of the magnetic substances on the lithium ion battery and the safety of the battery in the use process are avoided.
The embodiment of the application also provides a battery, and the negative electrode material provided by the embodiment of the application or the negative electrode material prepared by the preparation method of the negative electrode material provided by the embodiment of the application is adopted. The battery can be a lithium ion battery or a sodium ion battery, and the battery provided by the embodiment of the application has the advantages of excellent rate performance and low expansion.
The testing method comprises the following steps:
1) Median diameter D 50 of anode material:
The particle size test method is described in GB/T19077-2016. The volume reference cumulative particle size distribution of the particles is measured by a laser diffraction method, and D 50 represents the particle size corresponding to the case that the volume cumulative particle size distribution percentage of the powder reaches 50%.
2) The method for testing the specific surface area of the anode material comprises the following steps:
After the adsorption amount of the gas on the solid surface at different relative pressures is measured at a constant temperature and a low temperature, the adsorption amount of the sample monolayer is obtained by the base Yu Bulang Noll-Ett-Taylor adsorption theory and a formula (BET formula) thereof, so that the specific surface area of the material is calculated.
3) The testing method for the mass content of the carbon element in the anode material comprises the following steps:
the mass content of amorphous carbon was tested using thermogravimetric analysis.
4) The testing method for the mass content of oxygen element in the anode material comprises the following steps:
The mass content of oxygen in the anode material was measured using an oxygen-nitrogen-hydrogen analyzer.
5) The testing method for the mass content of M element in the anode material comprises the following steps:
Burning 1g of anode material to constant weight at 750-1000 ℃ under oxygen-containing atmosphere, dissolving by using mixed acid consisting of concentrated HF (mass concentration is 40%), concentrated HCl (mass concentration is 38%) and concentrated HNO 3 (mass concentration is 68%) with volume ratio of 1:1:3 until the solution does not generate bubbles any more, repeatedly adding the mixed acid, and carrying out solid-liquid separation to obtain a first digestion solution of the anode material when the solution still does not generate bubbles; and testing the mass A 1 of the M element in the first digestion liquid by adopting an electrically coupled plasma atomic emission spectrum, wherein the mass content M 1（ppm）=A1/1 (total mass of the anode material) of the M element in the first digestion liquid is 1000000.
Washing 100g of a negative electrode material with 100mL of hydrochloric acid with the concentration of 1mol/L for 2 hours, drying the separated solid, taking 1g of the dried solid, burning the solid to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, and carrying out dissolution treatment by using 100mL mixed acid consisting of concentrated HF (with the mass concentration of 40%), concentrated HCl (with the mass concentration of 38%) and concentrated HNO 3 (with the mass concentration of 68%) with the volume ratio of 1:1:3 until bubbles are not generated in the solution any more, and carrying out solid-liquid separation to obtain a second digestion solution of the negative electrode material; and testing the mass A 2 of the M element in the second digestion liquid by adopting an electrically coupled plasma atomic emission spectrum, wherein the mass content M 2（ppm）=A2/1 (total mass of the anode material) of the M element in the second digestion liquid is 1000000.
6) The testing method of the variation coefficient of the metal M element in the anode material comprises the following steps:
And carrying out scanning test on particle sections of the anode material by using a scanning electron microscope and an energy dispersion spectrometer, randomly selecting 10 anode material particles, selecting and testing Si element, O element and metal M element on each particle section, measuring mass percent of the Si element, O element and mass percent P M% of the metal M element in each particle, and calculating variation coefficient c=sigma/mu of P M, wherein sigma is P M standard deviation of 10 particles, and mu is P M average value of 10 particles. When the number of M elements in the anode material is multiple, the mass percentage of the metal M elements in the anode material particles is the sum of the mass percentages of the multiple M elements, namely P M is the total mass percentage of the multiple metal M elements, and when the variation coefficient c is calculated, the calculation is also performed by taking the total mass percentage as a reference.
7) XRD test of the negative electrode material:
the negative electrode material was formed into a sheet, and the sheet was subjected to a test using an X-ray diffraction analyzer. Angular range: 10-90 °, scanning mode: step scan, select slit width 1.0, and set voltage 40kW, current 40mA. The measured data were analyzed using the Jade 6.5 software to confirm the material composition by aligning the PDF cards.
8) PH test of the negative electrode material:
Taking 10g anode material, adding 10g water, stirring 30min, and measuring the pH value of the liquid subjected to solid-liquid separation.
9) Button cell testing
The prepared anode material, conductive carbon black and polyacrylic acid binder are prepared according to the mass percentage of 75:15:10, dissolving the materials in a solvent, mixing, coating the mixture on a copper foil current collector, and vacuum drying to prepare a negative electrode plate; the lithium metal sheet was used as a counter electrode, and the button cell was assembled in a glove box filled with argon gas. And (3) carrying out charge and discharge test according to the charge and discharge interval of 0.01-1.5V at the current density of 0.1C.
10 Electrochemical performance test
Mixing the prepared anode material with graphite according to the mass ratio of 10:90, mixing the anode material with sodium carboxymethylcellulose CMC, a binder styrene-butadiene rubber SBR, a conductive agent Super-P and a conductive agent KS-6 according to the mass ratio of 92:2:2:2, preparing slurry, coating the slurry on copper foil, and carrying out vacuum drying and rolling to prepare an anode pole piece; and then, assembling a ternary positive electrode plate (nickel cobalt lithium manganate NCM 523), 1mol/L LiPF 6/ethylene carbonate+dimethyl carbonate+methyl ethyl carbonate (v/v=1:1:1) electrolyte, celgard2400 diaphragm and a shell prepared by the traditional mature process into the CR2016 simulated battery by adopting a conventional production process. The cycle performance test uses 30mA current to perform constant current charge and discharge experiment, and the charge and discharge voltage is limited to 0-1.5V. And testing by using a LAND battery testing system. At a current density of 0.1C, a charge-discharge test was performed at a charge-discharge interval of 0.005V-1.5V.
First coulombic efficiency = first-turn discharge capacity/first-turn charge capacity.
The cycle is repeated for 50 weeks, the thickness of the pole piece of the lithium ion battery is measured to be H1 by using a micrometer, and the expansion rate after 50 cycles is = (H1-H0)/H0 multiplied by 100%, wherein H0 is the initial thickness of the pole piece.
Repeating the cycle for 100 weeks, and recording the discharge capacity as the residual capacity of the lithium ion battery; capacity retention = remaining capacity/initial capacity 100%.
The following examples are provided to further illustrate embodiments of the application. The embodiments of the present application are not limited to the following specific embodiments. The modification can be appropriately performed within the scope of the main claim.
Example 1
A preparation method of a negative electrode material comprises the following steps:
(1) 1kg of metal Na is placed in a cavity alpha and 9kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other and form a T shape with the air outlet, and the outlets of the two cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
(2) When the air pressure of the cavity is increased to above 1Pa, the temperature rise is suspended, and the corresponding air outlet valve is opened. After the gas outlet valves of the two cavities are opened, opening the gas outlet valve to lead the gas to the deposition area for deposition; both chambers were then set to 1400 ℃ for stable evaporation to give the intermediate.
(3) And (3) crushing the intermediate by using a jet mill until D 50 is less than 10 mu m, putting the crushed intermediate into a CVD furnace, introducing C 2H2 gas, and depositing for 10 hours at 1000 ℃ to obtain the anode material.
The anode material prepared by the embodiment of the application comprises an active substance and a carbon material positioned on at least part of the surface of the active substance, wherein the active substance comprises silicon oxide and sodium silicate. Fig. 2 shows XRD patterns of the negative electrode material prepared in example 1 of the present application, and other parameters of the negative electrode material are shown in table 1.
Example 2
A preparation method of a negative electrode material comprises the following steps:
(1) 0.1kg of metal Na and 0.9kg of metal Mg are placed in a cavity alpha and 9kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other, the outlets of the two cavities are T-shaped with the air outlet, and the outlets of the two cavities and the air outlet are provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
(2) When the air pressure of the cavity is increased to above 1Pa, the temperature rise is suspended, and the corresponding air outlet valve is opened. After the gas outlet valves of the two cavities are opened, opening the gas outlet valve to lead the gas to the deposition area for deposition; both chambers were then set to 1400 ℃ for stable evaporation to give the intermediate.
(3) And (3) crushing the intermediate by using a jet mill until D 50 is less than 10 mu m, putting the crushed intermediate into a CVD furnace, introducing C 2H2 gas, and depositing for 10 hours at 1000 ℃ to obtain the anode material.
The anode material prepared by the embodiment of the application comprises an active substance and a carbon material positioned on at least part of the surface of the active substance, wherein the active substance comprises silicon oxide, sodium silicate and magnesium silicate. Other parameters of the anode material are detailed in table 1.
Example 3
Unlike example 1, the following is:
(1) 1kg of metal Mg is placed in a cavity alpha and 9kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other and form a T shape with the air outlet, and the outlets of the two cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
Example 4
The difference from the embodiment 3 is that,
(1) 1Kg of metal Mg is placed in a cavity alpha and 19kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other and form a T shape with the air outlet, and the outlets of the two cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
Example 5
The difference from the embodiment 3 is that,
(1) 1Kg of metal Mg is placed in a cavity alpha and 4kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other and form a T shape with the air outlet, and the outlets of the two cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
Example 6
The difference from the embodiment 1 is that,
(3) And mixing the intermediate with asphalt, and performing heat treatment at 1000 ℃ for 10 hours to obtain the anode material.
Example 7
The difference from the embodiment 1 is that,
(1) And placing 0.1kg of metal Li and 0.9kg of metal Mg in a cavity alpha and 9kg of SiO in a cavity beta of the double-cavity vacuum furnace, wherein the outlets of the two cavities are opposite to each other, form a T shape with the air outlet, and the outlets of the double cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
Example 8
The difference from the embodiment 1 is that,
(1) 0.1Kg of metal Li and 0.9kg of metal Al are placed in a cavity alpha and 9kg of SiO in a double-cavity vacuum furnace, outlets of the two cavities are opposite to each other and form a T shape with an air outlet, and the outlets of the two cavities and the air outlet are both provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute. The temperature at which the cavity α stably evaporates is changed to 2400 ℃.
Comparative example 1
A preparation method of a negative electrode material comprises the following steps:
(1) 1kg of Na metal and 9kg of SiO were placed in a single-chamber vacuum furnace, and then heated to 1400℃at a rate of 5℃per minute for stable evaporation to give an intermediate.
(2) And (3) crushing the intermediate by using a jet mill until D 50 is less than 10 mu m, putting the crushed intermediate into a CVD furnace, introducing C 2H2 gas, and depositing for 10 hours at 1000 ℃ to obtain the anode material.
The anode material prepared by the embodiment of the application comprises an active substance and a carbon material positioned on at least part of the surface of the active substance, wherein the active substance comprises silicon oxide and sodium silicate. Other parameters of the anode material are detailed in table 1.
Comparative example 2
(1) 1Kg of metal Na is placed in a cavity alpha and 9kg of SiO in a cavity beta of the double-cavity vacuum furnace, the outlets of the two cavities are arranged in parallel, and the outlets and the air outlets of the double cavities are provided with valves and are in a closed state. The air pressure of the two cavities is pumped to be lower than 1Pa, and then the temperature is raised at the speed of 5 ℃ per minute.
(2) When the air pressure of the cavity is increased to above 1Pa, the temperature rise is suspended, and the corresponding air outlet valve is opened. After the gas outlet valves of the two cavities are opened, opening the gas outlet valve to lead the gas to the deposition area for deposition; both chambers were then set to 1400 ℃ for stable evaporation to give the intermediate.
(3) And (3) crushing the intermediate by using a jet mill until D 50 is less than 10 mu m, putting the crushed intermediate into a CVD furnace, introducing C 2H2 gas, and depositing for 10 hours at 1000 ℃ to obtain the anode material.
The anode material prepared by the embodiment of the application comprises an active substance and a carbon material positioned on at least part of the surface of the active substance, wherein the active substance comprises silicon oxide and silicate of metal sodium. Other parameters of the anode material are detailed in table 1.
The negative electrode materials prepared in examples and comparative examples were subjected to performance tests, and the results of the above performance tests are shown in tables 1 to 2:
As can be seen from the data in table 1 and table 2, the anode materials of examples 1 to 8 include Si element, O element, and metal M element, and the metal M is at least one selected from metals having electronegativity < 1.8. The ratio of the mass content of M element in the digestion liquid of the anode material is 0.8-M2/M1-M1, and the metal element M in the anode material is not dissolved out in a large amount before and after the acid washing, so that the silicon oxide and silicate in the anode material are uniformly distributed, the density of the active substance of the anode material is higher, hydrochloric acid is difficult to permeate into the active substance and dissolve the silicate, the compound of the metal M is dispersed and distributed in the silicon oxide, the compound of the metal M can be embedded on silicon oxide particles or between the silicon oxide particles, the uniform doping of the metal M in the active substance can be realized, the density of the active substance is effectively improved, the metal dissolution in the charging and discharging process can be reduced, the gas production is reduced, the first coulombic efficiency and the circulating stability of the anode material are comprehensively improved, and the volume expansion of the anode material is reduced.
In comparative example 1, metal Na and SiO were placed in a single-chamber vacuum furnace, and the generated vapors were directly mixed, so that the uniformity of distribution of the metal element M in the anode material was reduced, and the metal element M partially exposed on the surface of the anode material particles affected the cycle stability of the anode material, and increased the volume expansion.
In the preparation process of comparative example 2, metal Na and SiO are respectively placed in the cavity α and the cavity β of the dual-cavity vacuum furnace, and since the outlets of the two cavities are arranged in parallel, that is, the vapor is introduced into the deposition area for mixing and depositing after coming out, the vapor is difficult to obtain sufficiently uniform mixing, the uniformity degree of the distribution of the metal element M in the anode material is reduced, and part of the metal element M exposed on the surface of the anode material particles affects the circulation stability of the anode material, thereby exacerbating the volume expansion.
While the application has been described in terms of the preferred embodiment, it is not intended to limit the scope of the claims, and any person skilled in the art can make many variations and modifications without departing from the spirit of the application, so that the scope of the application shall be defined by the claims.

Claims (10)

1. A negative electrode material, characterized in that the negative electrode material comprises an active substance, the active substance comprises an Si element, an O element and a metal M element, and the metal M is at least one selected from metals with electronegativity < 1.8;
Burning 1g of the anode material to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, dissolving 100mL of mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 in a volume ratio of 1:1:3 until bubbles are not generated in the solution, and carrying out solid-liquid separation to obtain a first digestion solution of the anode material; testing the mass content M 1 of the M element in the first digestion liquid by adopting an electrically coupled plasma atomic emission spectrum;
Washing 100g of the anode material with 100mL of hydrochloric acid with the concentration of 1mol/L for 2 hours, drying the separated solid, taking 1g of dried solid, burning the solid to constant weight at 750-1000 ℃ in an oxygen-containing atmosphere, and carrying out dissolution treatment by using 100mL mixed acid consisting of concentrated HF, concentrated HCl and concentrated HNO 3 with the volume ratio of 1:1:3 until bubbles are not generated in the solution, so as to obtain a second digestion solution of the anode material after solid-liquid separation; and testing the mass content M 2,0.8≤m2/ m1 of the M element in the second digestion liquid by adopting an electric coupling plasma atomic emission spectrum to be less than or equal to 1.
2. The anode material according to claim 1, wherein 50000ppm or less m 1 or less 200000ppm; and/or 40000ppm or less m 2 or less 160000ppm.
3. The anode material according to claim 1, wherein a scanning electron microscope and an energy dispersion spectrometer are used for scanning and testing particle sections of the anode material, 10 anode material particles are randomly selected, each particle section is selected for testing Si element, O element and metal M element, the mass percent P M% of the metal M element in each particle is measured, the variation coefficient c=σ/[ mu ] of P M is calculated, σ is the standard deviation of P M of 10 particles, [ mu ] is the average value of P M of 10 particles, and the variation coefficient c is less than 0.5.
4. The negative electrode material according to any one of claims 1 to 3, wherein 100g of the negative electrode material is added to 1000g of water, and the viscosity of the mixed solution obtained after stirring for 30 minutes is <50cps.
5. The negative electrode material according to any one of claims 1 to 3, wherein the negative electrode material comprises at least one of a M 2SiO3 characteristic peak, a MSiO 3 characteristic peak, a M 2(SiO3)3 characteristic peak, and a M (SiO 3)2 characteristic peak) by X-ray diffraction analysis.
6. The anode material according to any one of claims 1 to 3, wherein the anode material satisfies at least one of the following characteristics:
(1) The metal M comprises at least one of Li, K, na, mg, ca, al, la, zn, ti and Mn;
(2) The metal M comprises Mg;
(3) In the negative electrode material, the existence form of Si comprises at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, and a compound of crystalline silicon and amorphous silicon;
(4) In the negative electrode material, the metal M is present in at least one of a silicate of M and an oxide of M.
7. The anode material according to any one of claims 1 to 3, wherein the active material includes silicon oxide including silicon element and oxygen element, and an atomic ratio of the silicon element to the oxygen element is 0 to 2 and does not include 0.
8. A negative electrode material according to any one of claims 1 to 3, further comprising a carbon material, the surface of the active material and/or between the active material particles having the carbon material.
9. The anode material according to claim 8, wherein the anode material satisfies at least one of the following features (1) to (5):
(1) The mass content of carbon element in the anode material is 1% -40%;
(2) The mass content of oxygen in the anode material is 10% -35%;
(3) The specific surface area of the anode material is less than or equal to 20m 2/g;
(4) The median particle diameter D 50 of the negative electrode material is 1-20 mu m;
(5) The pH value of the negative electrode material meets the following conditions: the pH value is more than or equal to 8 and less than or equal to 10.
10. A battery comprising the anode material according to any one of claims 1 to 9.
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