WO2021136245A1 - 一种用于电池的负极活性材料及其制备方法 - Google Patents

一种用于电池的负极活性材料及其制备方法 Download PDF

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WO2021136245A1
WO2021136245A1 PCT/CN2020/140717 CN2020140717W WO2021136245A1 WO 2021136245 A1 WO2021136245 A1 WO 2021136245A1 CN 2020140717 W CN2020140717 W CN 2020140717W WO 2021136245 A1 WO2021136245 A1 WO 2021136245A1
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silicon
lithium
active material
metal
negative electrode
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PCT/CN2020/140717
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English (en)
French (fr)
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罗姝
李喆
查道松
汪芳
王岑
张和宝
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安普瑞斯（南京）有限公司
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Priority claimed from CN201911412337.2A external-priority patent/CN111162269B/zh
Priority claimed from CN201911406235.XA external-priority patent/CN111180692B/zh
Application filed by 安普瑞斯（南京）有限公司 filed Critical 安普瑞斯（南京）有限公司
Priority to JP2022539340A priority Critical patent/JP7410301B2/ja
Priority to EP20908784.0A priority patent/EP4064388A1/en
Priority to US17/788,446 priority patent/US20230034396A1/en
Priority to KR1020227022651A priority patent/KR20220107281A/ko
Publication of WO2021136245A1 publication Critical patent/WO2021136245A1/zh

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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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • 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
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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

Definitions

  • the invention relates to the field of batteries, in particular to a negative electrode active material for batteries and a preparation method thereof.
  • the negative electrode material of commercial lithium-ion batteries is mainly graphite, but due to the low theoretical capacity (372mAh/g), it limits the further improvement of battery energy density.
  • the elemental silicon anode material has a very high capacity advantage (li 15 Si 4 in the lithium insertion state at room temperature, and the theoretical lithium storage capacity is about 3600mAh/g), which is about 10 times the theoretical capacity of the current commercial graphite anode materials, and has other anodes.
  • silicon anode materials there are three main types of silicon anode materials.
  • One is elemental silicon (including nano silicon, porous silicon, amorphous silicon, etc.) and its composite materials with carbon materials; the other is silicon and other metals (such as iron, manganese, nickel, etc.). , Chromium, cadmium, tin, copper, etc.), non-metallic (carbon, nitrogen, phosphorus, boron, etc.) composition alloy materials; the third is silicon-oxygen compound and its composite materials with carbon materials.
  • the theoretical capacity of elemental silicon material is the highest, so the theoretical energy density is also the highest.
  • the elemental silicon anode material has a serious volume effect in the process of lithium insertion and removal, and the volume change rate is about 300%, which will cause powdering of the electrode material and separation of the electrode material from the current collector.
  • the new SEI film will be formed when the fresh interface is exposed to the electrolyte, which will continue to consume the electrolyte and reduce the cycle performance of the electrode material.
  • Silicon-oxygen compounds have more inactive materials, resulting in lower capacity than elemental silicon anode materials; however, at the same time, due to the presence of these inactive components, the expansion of silicon during the cycle is effectively inhibited by the inactive phase, so its Cycle stability has obvious advantages. Compared with elemental silicon, silicon-oxygen compounds are easier to achieve industrial applications.
  • silicon-oxygen compounds also have their specific problems.
  • the surface of the particles tends to form a thicker SEI film due to more side reactions with the electrolyte; at the same time, lithium silicate and lithium oxide are generated inside the particles, which can cause irreversible delithiation. Irreversible loss of lithium ions in the battery.
  • the above two types of irreversible reactions lead to low coulombic efficiency of lithium-ion batteries containing silicon-oxygen compound negative electrodes for the first time, thereby limiting the improvement of the energy density of the whole battery.
  • silicon-oxygen compounds also have problems such as low ion and electronic conductivity, and low coulombic efficiency during battery cycling. Based on the above problems, researchers have made the following improvements.
  • silicon-oxygen compounds can be pre-doped with lithium, including high-temperature mixing of silicon-oxygen compounds and lithium metal, or electrochemical methods to pre-charge lithium on the silicon oxide compound anode, or use high-energy machinery The mixing makes the silicon-oxygen compound and the metal lithium or organic lithium compound as the lithiation agent react in situ at the same time, or the lithium-containing compound and the silicon-oxygen compound react at a high temperature to realize the pre-charge of lithium for the silicon-oxygen compound .
  • the Chinese patent with application publication number CN107710466A discloses a lithium silicon-oxygen compound negative electrode material and a manufacturing method thereof.
  • the surface of the siloxylithium compound is provided with a composite layer composed of an amorphous metal oxide and a metal hydroxide, which improves the stability of the negative electrode material to aqueous homogenate.
  • a composite layer composed of an amorphous metal oxide and a metal hydroxide, which improves the stability of the negative electrode material to aqueous homogenate.
  • the aqueous homogenate system based on the material structure is still not stable enough.
  • One of the objectives of the present invention is to provide a negative electrode active material with high capacity, high coulombic efficiency, long cycle life, strong water resistance, water-based homogenization system, and its scale for use in the deficiencies of the prior art. Method of chemical preparation.
  • the present invention proposes a negative electrode active material for a battery, which has negative electrode active material particles, and the negative electrode active material particles contain a silicon oxide compound;
  • the negative electrode active material particles include lithium element and non-lithium doped metal, wherein:
  • the non-lithium-doped metal includes metal M1, the metal M1 includes one or more of titanium, magnesium, zirconium, zinc, aluminum, yttrium, and calcium, and the non-lithium-doped metal accounts for the negative electrode active material.
  • the content of is 0.01-20wt%, preferably 0.05-15wt%, further preferably 0.1-10wt%, more preferably 0.1-5wt%.
  • non-lithium doped metal further includes metal M2, and the metal M2 includes one or more of copper, nickel, iron, manganese, cobalt, and chromium.
  • the content of the metal M1 and the metal M2 in the negative electrode active material is 0.01-25 wt%, preferably 0.05-15 wt%, further preferably 0.1-10 wt%, more preferably 0.1-5 wt%.
  • the content of the metal M2 in the negative electrode active material is 0.01-25wt%, preferably 0.01-20wt%, more preferably 0.05-15wt%, further preferably 0.1-10wt%, more preferably 0.1-5wt% .
  • the metal M1 is present in the negative active material in the form of an oxygen-containing compound
  • the oxygen-containing compound of the non-lithium-doped metal includes a metal oxide, a metal silicate, and a lithium-containing composite metal silicate. (Such as lithium magnesium silicate) and a composite oxide of lithium and non-lithium-doped metal (such as lithium zirconate).
  • oxygen-containing compound of the metal M1 may be distributed in the entire silicon-oxygen compound in a dispersed manner.
  • the oxygen-containing compound of the metal M1 may be enriched in the surface layer of the silicon-oxygen compound, and the concentration of the oxygen-containing compound may specifically decrease from the surface layer to the inside of the silicon-oxygen compound.
  • part of the oxygen-containing compound of the metal M1 may remain on the surface of the silicon-oxygen compound to form a coating structure, while the remaining part diffuses into the silicon-oxygen compound particles.
  • the metal M2 is present in the negative electrode active material in the form of an elemental metal or a silicon-containing alloy phase.
  • the lithium content in the negative electrode active material particles is 0.1-20 wt%, preferably 2-18 wt%, and more preferably 4-15 wt%.
  • the negative electrode active material particles include at least one lithium-containing compound selected from Li 4 SiO 4 , Li 2 SiO 3 , Li 6 Si 2 O 7 , Li 8 SiO 6 and Li 2 Si 2 O 5.
  • the median diameter of the negative electrode active material particles is between 0.2-20 ⁇ m, preferably between 1-15 ⁇ m, and more preferably between 2-10 ⁇ m.
  • the negative electrode active material particles further comprise elemental silicon nanoparticles, which may be uniformly dispersed in the negative electrode active material particles, wherein the median diameter of the elemental silicon nanoparticles is between 0.1-35 nm , Preferably 0.5-20nm, more preferably 1-15nm.
  • the content of silicon in the negative electrode active material particles is 30-80 wt%, preferably 35-65 wt%, and more preferably 40-65 wt%, so the material has a high reversible capacity.
  • the surface of the negative electrode active material particles is also coated with a carbon film layer, the carbon film layer covers the surface of the silicon oxide compound, and the thickness of the carbon film layer is between 0.001-5 ⁇ m, preferably 0.005-2 ⁇ m It is more preferably between 0.01 and 1 ⁇ m.
  • the weight ratio of the carbon film layer to the silicon-oxygen compound is 0.01:100-20:100, preferably 0.1:100-15:100, and more preferably 1:100-12:100.
  • the present invention also provides an electrode, which includes the negative active material as described above.
  • the present invention also proposes a pole piece or battery including any of the foregoing negative active materials.
  • the present invention also proposes a method for preparing the negative electrode active material as described above, and the method includes:
  • silicon-oxygen compound particles and dope lithium and non-lithium metal elements into the silicon-oxygen compound particles wherein the stoichiometric ratio of silicon and oxygen in the silicon-oxygen compound particles is 1:0.4-1:2, preferably 1. :0.6-1:1.5, more preferably 1:0.8-1:1.2.
  • non-lithium metal elements include metal M1 and metal M2.
  • the metal M1 includes one or more of titanium, magnesium, zirconium, zinc, aluminum, yttrium, and calcium; and the metal M2 includes copper, nickel, and iron.
  • One or more of, manganese, cobalt, and chromium are examples of metal M1 and metal M2.
  • the doping source of the metal M1 may be a metal element or compound of M1, preferably a compound containing metal M1, more preferably a non-reducing compound containing metal M1, and more preferably a metal M1 containing compound.
  • Compounds with oxygen elements (VIA group) or halogen elements (VIIA group) are more preferably compounds containing metal M1 and oxygen, such as oxides containing metal M1, oxygen-containing inorganic or organic compounds, etc.; the metal The doping source of M2 may be a metal element or compound of M2, preferably a compound containing metal M2.
  • the median diameter of the silicon-oxygen compound particles is between 0.2-20 ⁇ m, preferably 1-15 ⁇ m, and more preferably 2-10 ⁇ m.
  • the doping temperature of the non-lithium doped metal element may be 400-1100°C, preferably 600-1000°C.
  • the doping temperature of lithium element may be 400-900°C, preferably 550-850°C.
  • the silicon-oxygen compound particles may be particles that are completely coated, partially coated, or not coated with a carbon film layer.
  • the silicon-oxygen compound may be an undisproportionated silicon-oxygen compound or a silicon-oxygen compound that has undergone disproportionation heat treatment, wherein the disproportionation heat treatment temperature is 600-1100°C, preferably 700-1000°C.
  • the carbonization temperature of the coating is 600-1100°C, preferably 700-1000°C.
  • the preparation of the silicon oxide compound particles containing non-lithium metal doping can be combined with the lithium doping modification in one step, that is: the silicon oxide compound particles and the non-lithium metal doping
  • the substance and the lithium-containing compound are mixed uniformly at the same time, and then heat-treated in a non-oxidizing atmosphere.
  • the temperature of the heat treatment may be 400-900°C, preferably 550-850°C, the holding time is 0.1-12 hours, and the heating rate is greater than 0.1°C per minute and less than 20°C per minute.
  • the non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • the lithium element is further doped.
  • the silicon-oxygen compound when coating the carbon film layer, can also be doped with non-lithium metal elements at the same time.
  • the step of coating the surface of the silicon-oxygen compound with a carbon film layer and the step of doping the silicon-oxygen compound with a non-lithium metal can also be switched back and forth.
  • the doping sequence of the metal M1 and the metal M2 can also be exchanged.
  • the present invention has the following advantages:
  • the negative electrode active material in the present invention has a dense oxygen-containing compound structure formed by non-lithium-doped metal M1.
  • the dense oxygen-containing compound phase of the non-lithium-doped metal can greatly improve the stability of the lithium-containing silicon-oxygen compound, effectively block the contact between the inside of the particle and the outside water, and avoid the reaction of the material and the water during the water system homogenization process to cause active ingredients
  • the dense oxygen-containing compound phase of the non-lithium-doped metal can inhibit the alkaline release of lithium-containing silicon oxygen compounds, reduce the pH value of the material, and improve the stability of the aqueous slurry, thus effectively avoiding coating
  • the pole piece quality problems such as pinholes, pits, uneven surface density, poor adhesion, etc. caused by the deterioration of gas production, slurry rheology and stability.
  • the dense oxygen-containing compound phase of the non-lithium-doped metal can also isolate the silicon nanoparticles inside the silicon-oxygen compound from the external electrolyte, reducing its side reactions with the electrolyte, and at the same time, it can form a more stable SEI film. Improve the coulombic efficiency and capacity stability of the material during the battery charge and discharge cycle.
  • the negative electrode active material in the present invention also contains a simple metal phase or a silicon-containing alloy phase of the non-lithium-doped metal M2.
  • the single metal phase or silicon-containing alloy phase doped with metal M2 can effectively improve the conductivity inside the negative electrode active material particles, and at the same time improve the structural stability of the negative electrode active material, which is beneficial to improve the coulombic efficiency and cycle stability of the material .
  • the negative electrode active material of the present invention has both an oxygen-containing compound formed by non-lithium-doped metal M1 and a single-metal phase or silicon-containing alloy phase of non-lithium-doped metal M2.
  • the two can play a synergistic effect and greatly enhance the material.
  • the stability of the material can inhibit the release of alkalinity of the material, and significantly improve the water resistance of the material; at the same time, the synergy can greatly improve the coulombic efficiency and capacity stability of the material during the battery charge and discharge cycle.
  • lithium-containing silicon-oxygen compounds such as high coulombic efficiency, high reversible capacity, good cycle retention, low cycle expansion, and other electrochemical characteristics, are also perfectly retained in the material structure of the present invention.
  • the lithium ion secondary battery prepared by using this material also has the advantages of high energy density, good cycle stability, and low swelling.
  • the silicon nanocrystalline particles inside the lithium-containing silicon-oxygen compound particles are small in size, and are uniformly dispersed and fixed in the lithium silicate compound or the silicon-oxygen compound matrix.
  • the matrix can effectively inhibit and buffer the expansion of the silicon nano-particles and prevent
  • the silicon particles gradually melt and merge into larger-size particles during the charging and discharging process to prevent the large-size silicon particles from causing greater expansion and failure of some silicon materials after the fusion. Therefore, the lithium ion secondary battery prepared by using the material has the advantages of small cycle expansion, good cycle stability, and high energy density.
  • the negative electrode active material of the present invention has the electrochemical characteristics of high capacity, high coulombic efficiency and good cycle performance when used as a battery negative electrode.
  • the battery prepared by the negative active material has the characteristics of high energy density, good cycle stability, and low expansion.
  • the negative electrode active material has simple preparation method, low cost, good repeatability, simple equipment required, large-scale industrial production, and the material has good water resistance and can be directly applied to the aqueous negative electrode homogenization process system commonly used in the industry , Can truly realize the large-scale application of silicon-containing anode in the field of secondary batteries.
  • Figure 1 is a scanning electron microscope view of the product of Example 1;
  • Example 2 is a graph of the cycle performance of the silicon-containing negative electrode full battery prepared in Example 1;
  • Figure 3 is a scanning electron microscope view of the product of Example 2.
  • Figure 4 is a scanning electron microscope view of the product of Example 16.
  • Fig. 5 is an X-ray diffraction analysis chart of comparative example 5 silicon negative electrode active material.
  • One of the objectives of the present invention is to provide a negative electrode active material with high capacity, high coulombic efficiency, long cycle life, strong water resistance, water-based homogenization system, and its scale for use in the deficiencies of the prior art. Method of chemical preparation.
  • the present invention proposes a negative electrode active material for a battery, which has negative electrode active material particles containing a silicon oxide compound,
  • the negative electrode active material particles include lithium element and non-lithium doped metal, wherein:
  • the non-lithium-doped metal includes metal M1, the metal M1 includes one or more of titanium, magnesium, zirconium, zinc, aluminum, yttrium, and calcium, and the non-lithium-doped metal accounts for the negative electrode active material.
  • the content of is 0.01-20wt%, preferably 0.05-15wt%, further preferably 0.1-10wt%, more preferably 0.1-5wt%.
  • the non-lithium-doped metal is in a proper range, which can avoid the negative impact of the doped metal on the capacity of the negative electrode active material, and at the same time play a sufficient stabilizing and protective effect on the lithium-containing silicon oxygen compound, so that the mixed cost
  • the aqueous slurry made of the negative electrode active material of the invention is more stable.
  • non-lithium doped metal further includes metal M2, and the metal M2 includes one or more of copper, nickel, iron, manganese, cobalt, and chromium.
  • the content of the metal M1 and the metal M2 in the negative electrode active material is 0.01-25 wt%, preferably 0.05-15 wt%, further preferably 0.1-10 wt%, more preferably 0.1-5 wt%.
  • the content of the metal M2 in the negative electrode active material is 0.01-25wt%, preferably 0.01-20wt%, more preferably 0.05-15wt%, further preferably 0.1-10wt%, more preferably 0.1-5wt% .
  • the metal M1 may mainly be present in the negative electrode active material in the form of oxygen-containing compounds, and the oxygen-containing compounds include metal oxides, metal silicates, lithium-containing composite metal silicates (such as silicic acid). One or more of magnesium lithium) and composite oxides of lithium and non-lithium-doped metals (such as lithium zirconate).
  • the oxygen-containing compound doped with metal M1 is uniformly dispersed or locally enriched in the negative electrode active material particles, and forms a dense protective structure.
  • the oxygen-containing compound of non-lithium metal M1 is insoluble in water, its compact structure can greatly improve the stability of lithium-containing silicon-oxygen compound, effectively blocking the contact between the inside of the particle and the external moisture or electrolyte, and avoiding the material and the electrolyte in the water homogenization process.
  • the water reaction causes the loss of active components, and at the same time reduces the side reaction between the electrolyte and the silicon compound, which is beneficial to improve the first coulombic efficiency of the negative electrode active material.
  • the dense oxygen-containing compound phase of the non-lithium-doped metal M1 can also inhibit the alkaline release of lithium-containing silicon oxygen compounds, reduce the pH value of the material, and improve the stability of the aqueous slurry, thus effectively avoiding the coating process In the middle of the pole piece quality problems such as pinholes, pits, uneven surface density, poor adhesion, etc. caused by gas production, slurry rheology and stability deterioration.
  • oxygen-containing compound of the metal M1 may be distributed in the entire silicon-oxygen compound in a dispersed manner to form a dense protective structure.
  • the oxygen-containing compound of the metal M1 may be enriched in the surface layer of the silicon-oxygen compound to form a dense protective shell layer, and the concentration of the oxygen-containing compound may specifically range from the surface layer to the silicon-oxygen compound. Decrease internally.
  • part of the oxygen-containing compound of the non-lithium-doped metal M1 may remain on the surface of the silicon-oxygen compound to form a coating structure, while the remaining part diffuses into the silicon-oxygen compound particles.
  • the metal M2 is present in the negative electrode active material in the form of an elemental metal or a silicon-containing alloy phase.
  • the non-lithium-doped metal M2 is uniformly dispersed or locally enriched in the negative electrode active material particles, and can mainly form a single metal phase or a silicon-containing alloy phase doped with the metal M2.
  • the single metal phase or silicon-containing alloy phase doped with metal M2 effectively improves the internal conductivity of the negative electrode active material particles, and at the same time improves the structural stability of the material, which is beneficial to the coulombic efficiency and cycle stability of the negative electrode active material The promotion.
  • the oxygen-containing compound formed by the non-lithium-doped metal M1 and the elemental metal phase or the silicon-containing alloy phase of the non-lithium-doped metal M2 can have a synergistic effect and play a "1+1>
  • the 2" effect greatly enhances the stability of the material, inhibits the release of alkalinity of the material, and significantly improves the water resistance of the material; at the same time, the synergy can greatly improve the coulombic efficiency and capacity stability of the material during the battery charge and discharge cycle. Sex.
  • the lithium content in the negative electrode active material particles is 0.1-20 wt%, preferably 2-18 wt%, and more preferably 4-15 wt%.
  • the negative electrode active material particles include at least one lithium-containing compound selected from Li 4 SiO 4 , Li 2 SiO 3 , Li 6 Si 2 O 7 , Li 8 SiO 6 and Li 2 Si 2 O 5.
  • the first coulombic efficiency and cycle retention rate of the lithium-containing silicon-oxygen compound are significantly improved.
  • the median diameter of the negative electrode active material particles is between 0.2-20 ⁇ m, preferably between 1-15 ⁇ m, and more preferably between 2-10 ⁇ m.
  • the negative electrode active material particles further comprise elemental silicon nanoparticles, which may be uniformly dispersed in the negative electrode active material particles, wherein the median diameter of the elemental silicon nanoparticles is between 0.1-35 nm , Preferably 0.5-20nm, more preferably 1-15nm.
  • the particles undergo a cycle of insertion and extraction of lithium ions, the particles expand less and are not easily broken, so that the lithium ion secondary battery using the material has a small cyclic expansion and stable cycle.
  • the content of silicon in the negative electrode active material particles is 30-80 wt%, preferably 35-65 wt%, and more preferably 40-65 wt%, so the material has a high reversible capacity.
  • the surface of the negative electrode active material particles is also coated with a carbon film layer, the carbon film layer covers the surface of the silicon oxide compound, and the thickness of the carbon film layer is between 0.001-5 ⁇ m, preferably 0.005-2 ⁇ m It is more preferably between 0.01 and 1 ⁇ m.
  • the coating means that the carbon film layer completely or partially covers the surface of the particles.
  • the weight ratio of the carbon film layer to the silicon-oxygen compound is 0.01:100-20:100, preferably 0.1:100-15:100, and more preferably 1:100-12:100.
  • the present invention also provides an electrode, which includes the negative active material as described above.
  • the present invention also proposes a pole piece or battery including any of the foregoing negative active materials.
  • the present invention also proposes a method for preparing the negative electrode active material as described above, and the method includes:
  • silicon-oxygen compound particles and dope lithium and non-lithium metal elements into the silicon-oxygen compound particles wherein the stoichiometric ratio of silicon and oxygen in the silicon-oxygen compound particles is 1:0.4-1:2, preferably 1. :0.6-1:1.5, more preferably 1:0.8-1:1.2.
  • non-lithium metal elements include metal M1 and metal M2.
  • the metal M1 includes one or more of titanium, magnesium, zirconium, zinc, aluminum, yttrium, and calcium; and the metal M2 includes copper, nickel, and iron.
  • One or more of, manganese, cobalt, and chromium are examples of metal M1 and metal M2.
  • the median diameter of the silicon oxide compound particles is between 0.2-20 ⁇ m, preferably 1-15 ⁇ m, more preferably 2-10 ⁇ m.
  • the doping temperature of the non-lithium metal element may be 400-1100°C, preferably 600-1000°C.
  • the doping temperature of lithium element may be 400-900°C, preferably 550-850°C.
  • the silicon-oxygen compound particles may be particles that are completely coated, partially coated, or not coated with a carbon film layer.
  • the silicon-oxygen compound may be an undisproportionated silicon-oxygen compound or a silicon-oxygen compound that has undergone disproportionation heat treatment, wherein the disproportionation heat treatment temperature is 600-1100°C, preferably 700-1000°C.
  • the carbonization temperature of the coating is 600-1100°C, preferably 700-1000°C.
  • the preparation of the silicon oxide compound particles containing non-lithium metal doping can be combined with the lithium doping modification in one step, that is: the silicon oxide compound particles and the non-lithium metal doping
  • the substance and the lithium-containing compound are mixed uniformly at the same time, and then heat-treated in a non-oxidizing atmosphere.
  • the temperature of the heat treatment may be 400-900°C, preferably 550-850°C, the holding time is 0.1-12 hours, and the heating rate is greater than 0.1°C per minute and less than 20°C per minute.
  • the non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • the lithium element is further doped.
  • the lithium doping step is performed after the non-lithium doping, which can inhibit the growth of silicon crystal grains in the silicon-oxygen compound during the heat treatment.
  • the nano-scale elemental silicon particles are uniformly dispersed and fixed in the lithium silicate compound or the silicon-oxygen compound matrix, which can effectively inhibit the expansion of silicon nanoparticles and prevent the silicon particles from gradually fusing to become larger during charging and discharging.
  • the size of the particles reduces the expansion and deformation of the battery during the cycle and reduces the electrical failure of the silicon material, so that the lithium ion secondary battery using the material has small cycle expansion and stable cycle.
  • the silicon-oxygen compound when coating the carbon film layer, can also be doped with non-lithium metal elements at the same time.
  • the step of coating the surface of the silicon-oxygen compound with a carbon film layer and the step of doping the silicon-oxygen compound with a non-lithium metal can also be switched back and forth. The doping sequence of the metal M1 and the metal M2 can also be exchanged.
  • the lithium element doping step is performed after the coating of the carbon film layer and the non-lithium element doping, which can inhibit the growth of silicon crystal grains in the silicon-oxygen compound during the heat treatment.
  • the nano-scale elemental silicon particles are uniformly dispersed and fixed in the lithium silicate compound or the silicon-oxygen compound matrix, which can effectively inhibit the expansion of silicon nanoparticles and prevent the silicon particles from gradually fusing to become larger during charging and discharging.
  • the size of the particles reduces the expansion and deformation of the battery during the cycle and reduces the electrical failure of the silicon material, so that the lithium ion secondary battery using the material has small cycle expansion and stable cycle.
  • the step of coating the carbon film layer is performed before the lithium element doping, which is beneficial to obtain a carbon film layer with better quality and more complete coating.
  • the carbon film layer coated on the surface of the silicon-oxygen compound particles can be realized in the following manner:
  • the carbon film layer can be directly obtained by chemical vapor deposition (CVD), the carbon source used in CVD is hydrocarbon gas, and the decomposition temperature of the hydrocarbon gas may be 600-1100°C, preferably 750- 950°C.
  • the carbon film layer can also be obtained by first performing carbon reaction coating and then performing heat treatment and carbonization in a non-oxidizing atmosphere.
  • the carbon reaction coating method can adopt any one of mechanical fusion machine, VC mixer, coating kettle, spray drying, sand mill or high-speed dispersing machine, and the selected solvents for coating are water, methanol, ethanol, Isopropanol, n-butanol, ethylene glycol, ether, acetone, N-methylpyrrolidone, methyl butanone, tetrahydrofuran, benzene, toluene, xylene, N,N-dimethylformamide, N,N- A combination of one or more of dimethylacetamide and chloroform.
  • the selected solvents for coating are water, methanol, ethanol, Isopropanol, n-butanol, ethylene glycol, ether, acetone, N-methylpyrrolidone, methyl butanone, tetrahydrofuran, benzene, toluene, xylene, N,N-dimethylformamide, N,N-
  • the carbon reaction source may be one or more of coal tar pitch, petroleum pitch, polyvinyl alcohol, epoxy resin, polyacrylonitrile, polymethylmethacrylate, glucose, sucrose, polyacrylic acid, and polyvinylpyrrolidone combination.
  • the equipment used for the heat treatment and carbonization can be any one of a rotary furnace, a ladle furnace, a roller kiln, a pusher kiln, an atmosphere box furnace or a tube furnace.
  • the heat treatment carbonization temperature may be 600-1100°C, preferably 700-1000°C, and the holding time may be 0.5-24 hours.
  • the non-oxidizing atmosphere may be provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • the doping of the non-lithium metal element may be that the silicon-oxygen compound particles and the non-lithium metal doping material are uniformly mixed and then heat-treated and doped in a non-oxidizing atmosphere, wherein the doping material includes a doping element.
  • the simple substance or compound powder of is preferably a compound containing a doping element.
  • metal oxides, metal salts including nitrate, nitrite, sulfate, sulfite, hydrogen sulfate, hydrogen phosphate, dihydrogen phosphate, halogen salt and other inorganic metal salts, and acetate , Oxalate, citrate and other organic metal salts
  • the above-mentioned mixing method may adopt any one of a high-speed dispersing machine, spray drying, a high-speed stirring mill, a ball mill, a cone mixer, a screw mixer, a stirring mixer or a VC mixer.
  • the equipment used for the heat treatment doping includes any one of a rotary furnace, a ladle furnace, a roller kiln, a pusher kiln, an atmosphere box furnace or a tube furnace.
  • the heat treatment doping temperature can be 400-1100°C, preferably 600-1000°C
  • the holding time is 0.1-12 hours, preferably 1-4 hours
  • the heating rate is greater than 1°C per minute and less than 100°C per minute.
  • the aforementioned non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • lithium doping modification methods include electrochemical methods, liquid phase doping methods, thermal doping methods, high-temperature mixing methods, high-energy mechanical methods, and the like.
  • electrochemical method, a liquid phase doping method, and a thermal doping method are preferred.
  • an electrochemical cell which contains four parts: a bath, anode electrode, cathode electrode and power source, and the anode electrode and cathode electrode are respectively connected to the two ends of the power source.
  • the anode electrode is connected to the lithium source
  • the cathode electrode is connected to the container containing the silicon oxide compound particles.
  • the bath is filled with an organic solvent, and the lithium source (anode electrode) and the container (cathode electrode) containing the silicon-oxygen compound particles are immersed in the organic solvent.
  • the above organic solvent can be ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl acetate, propyl acetate, ethyl propionate Solvents such as esters, propyl propionate, and dimethyl sulfoxide.
  • the organic solvent also contains electrolyte lithium salt, and lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), etc. can be used.
  • the above-mentioned lithium source (anode electrode) can be a lithium foil or a lithium compound, such as lithium carbonate, lithium oxide, lithium hydroxide, lithium cobaltate, lithium iron phosphate, lithium manganate, lithium vanadium phosphate, lithium nickelate, and the like.
  • the liquid phase doping method can also be used to modify the silicon-oxygen compound by lithium doping.
  • the metal lithium, the electron transfer catalyst, and the silicon-oxygen compound particles are added to the ether-based solvent, and the mixture is continuously stirred and heated in a non-oxidizing atmosphere to maintain a constant temperature reaction until the metal lithium in the solution completely disappears.
  • metal lithium can be dissolved in ether-based solvents and form coordination compounds of lithium ions. It has a lower reduction potential, so it can react with silicon-oxygen compounds, and lithium ions enter the silicon-oxygen compound structure.
  • the electron transfer catalyst includes biphenyl, naphthalene and the like.
  • the ether-based solvent includes methyl butyl ether, ethylene glycol butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, and the like.
  • the constant temperature reaction temperature is 25-200°C.
  • the non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • the thermal doping method can also be used to modify the silicon-oxygen compound by lithium doping.
  • the silicon-oxygen compound particles and the lithium-containing compound are uniformly mixed, and then heat-treated in a non-oxidizing atmosphere.
  • the lithium-containing compound includes lithium hydroxide, lithium carbonate, lithium oxide, lithium peroxide, lithium hydride, lithium nitrate, lithium acetate, lithium oxalate, and the like.
  • the mixing method adopts any one of a high-speed disperser, a high-speed stirring mill, a ball mill, a cone mixer, a screw mixer, a stirring mixer or a VC mixer.
  • the equipment used for the heat treatment is any one of rotary furnace, ladle furnace, liner furnace, roller kiln, pusher kiln, atmosphere box furnace or tube furnace.
  • the temperature of the heat treatment is 400-900°C, preferably 550-850°C, the holding time is 0.1-12 hours, and the heating rate is greater than 0.1°C per minute and less than 20°C per minute.
  • the non-oxidizing atmosphere is provided by at least one of the following gases: nitrogen, argon, hydrogen or helium.
  • the powder obtained was placed in a tube furnace and heat-treated in an argon atmosphere at a temperature of 10°C/ The temperature rise rate of min is raised to 550°C and kept for 3 hours. After natural cooling, lithium-doped silicon oxide compound powder can be obtained.
  • the above-mentioned silica compound particles are mixed with deionized water, and the pH value of the dispersion can be measured to be 10.7 by using a precision pH tester from Ohaus Instruments (Shanghai) Co., Ltd.
  • the crystallite size corresponding to the silicon (111) crystal plane of the silicon-oxygen compound is 1.2 nm.
  • silicon-oxygen compound material Take 12 parts of the above-mentioned silicon-oxygen compound material, 83 parts of artificial graphite, 2.5 parts of conductive additives, 2.5 parts of binder, homogenize in an aqueous system, take part of the aqueous homogenate slurry for water resistance and stability test, other slurries Used for coating, then drying and rolling to obtain silicon-containing negative pole piece.
  • Evaluation of the stability of the aqueous slurry containing the above-mentioned siloxane compound material Take 30 g of the above-mentioned aqueous homogenized slurry and store it in an environment of 65°C, and confirm when the above-mentioned slurry starts to generate gas under this condition. Under these harsh conditions, the slurry can last for more than a week without producing gas. In the conventional water system homogenization process, the slurry temperature is generally maintained at 25-30°C. Therefore, the method for evaluating the stability of the slurry used in this patent is far more stringent than the actual water-based homogenate coating production process. Under this evaluation method, if the slurry can persist for 24 hours without producing gas, it can be considered that the silicon oxide material in the slurry has strong water resistance and good stability, and can be used for large-scale water system homogenization.
  • Half-cell evaluation stack the above-mentioned silicon-containing negative pole piece with the diaphragm, lithium sheet, and stainless steel gasket in sequence, add 200 ⁇ L of electrolyte and seal to make a 2016-type lithium-ion half-cell.
  • FIG. 2 is a graph of the cycle performance of the silicon-containing negative electrode full battery prepared in Example 1.
  • FIG. The expansion rate of the above-mentioned full battery after 500 cycles of charging and discharging is 11% with respect to the battery after initial volume division.
  • Example 2 Compared with Example 1, in Example 2, the silicon-oxygen compound particles are coated with a carbon film by chemical vapor deposition, and acetylene is used as a carbon source. The coating reaction is carried out at 900°C for 3 hours to obtain a complete carbon film. Layer of silicon oxide particles. Subsequently, 11.4g of nano-alumina was uniformly coated on the surface of 1000g of the above particles by dry coating, and the temperature was kept at 800°C for 3 hours in a nitrogen atmosphere to obtain a coated complete carbon film layer doped with aluminum. ⁇ siloxane compound. Scanning electron microscopy results show that there is no aluminum-containing compound remaining on the surface of the particles, indicating that the aluminum has been completely doped into the silicon-oxygen compound ( Figure 3). Next, the above-mentioned silicon-oxygen compound is doped with lithium metal by the same process as in Example 1, to obtain a lithium-containing silicon-oxygen compound doped with aluminum and coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material is 10.9, and the crystallite size corresponding to the silicon (111) crystal plane is 2.3nm.
  • the water-based homogenate slurry containing this material can last for more than a week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 546.6 mAh/g, and the first charge-discharge efficiency was 88.5%.
  • the measured volume energy density of the whole battery reached 774.2Wh/L, the capacity retention rate after 500 charge-discharge cycles was 88.7%, and the battery expansion rate after 500 cycles was 10.5%.
  • Example 3 Compared with Example 1, in Example 3, 49.8g of nano-zinc oxide was uniformly coated on the surface of 1000g of silicon-oxygen compound particles by a dry coating method, and the temperature was maintained at 1000°C for 1 hour under a nitrogen atmosphere to obtain the doped Silicon oxide powder with zinc-free carbon film. Scanning electron microscopy results show that there is no zinc-containing compound remaining on the surface of the particles, indicating that all zinc has been doped into the silicon oxide compound. At the same time, the results of X-ray energy spectrum analysis showed that the zinc content on the surface of the particles was as high as 4.1%, which was close to the content of zinc actually doped in the silicon-oxygen compound, indicating that zinc was not enriched on the surface of the particles. Subsequently, the above-mentioned silicon-oxygen compound is doped with lithium metal by an electrochemical pre-lithium method to obtain a lithium-containing silicon-oxygen compound doped with zinc.
  • the pH of the obtained silicon negative electrode active material is 10.1, and the crystallite size corresponding to the silicon (111) crystal plane is 3.2nm.
  • the water-based homogenate slurry containing this material can last for more than a week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 542.3mAh/g, and the first charge-discharge efficiency was 87.6%.
  • the measured volume energy density of the whole battery reached 764.3 Wh/L, the capacity retention rate after 500 charge and discharge cycles was 84%, and the battery expansion rate after 500 cycles was 11.3%.
  • Example 4 adopts the same zinc doping method and heat treatment process, but reduces the coating amount of nano zinc oxide to 12.5 g to obtain silicon oxide compound particles doped with zinc. Subsequently, a carbon film layer was coated on the surface of the above particles by chemical vapor deposition, and acetylene was used as a carbon source, and the coating reaction was carried out at 1000°C for 3 hours to obtain a zinc-doped silicon oxide coated with a complete carbon film layer. Compound particles. The following lithium metal doping process is the same as that in Example 3, and a lithium-containing silicon-oxygen compound doped with a zinc element coated carbon film is obtained.
  • the pH of the obtained silicon negative electrode active material is 10.4, and the crystallite size corresponding to the silicon (111) crystal plane is 3.2nm.
  • the water-based homogenate slurry containing this material can last for more than a week without gas production under the accelerated experiment at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 543 mAh/g, and the first charge-discharge efficiency is 88%.
  • the measured volume energy density of the whole battery reached 768.1Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 87.1%, and the battery expansion rate after 500 cycles was 10.3%.
  • Example 5 the silicon-oxygen compound particles are coated with the carbon precursor in a liquid-phase coating method. After 1000 g of silicon oxide compound particles and 50 g of low-temperature coal pitch powder are uniformly mixed in the coating kettle by dry method, 2000 g of dimethylformamide is added while stirring, and the mixed powder is uniformly dispersed in the dimethylformamide. Subsequently, the coating kettle is heated to 140°C and kept at a constant temperature for 3 hours, and finally heated to 160°C and kept at a constant temperature until the dimethylformamide is evaporated to dryness to obtain a coal pitch-coated silicon oxide compound material. The above-mentioned material was heated to 950°C under a nitrogen atmosphere and kept for 3 hours to carbonize the coal pitch.
  • the material obtained after cooling is passed through a 500-mesh screen to obtain a carbon film-coated silicon oxide compound powder.
  • the doping source tetrabutyl titanate
  • 22g magnesium acetate tetrahydrate was replaced with 22g magnesium acetate tetrahydrate
  • the powder obtained by spray drying was changed to a heat treatment process of heating at 750°C for 3 hours.
  • the silicon oxide compound particles doped with the magnesium element coated with the carbon film are obtained. Scanning electron microscopy results showed that no magnesium-containing compounds remained on the surface of the particles, indicating that all magnesium had been doped into the silicon-oxygen compound.
  • the thermal doping method is used for lithium metal doping. Specifically, 500 grams of the above particles are mixed with 28.5 grams of lithium hydride, and the mixed powder is placed in a tube furnace and heat-treated in an argon atmosphere at a temperature of 10°C/ The heating rate of min was raised to 550°C and kept for 6 hours. After natural cooling, the material was taken out from the tube furnace and passed through a 500-mesh screen to obtain a lithium-containing silicon-oxygen compound doped with a magnesium-coated carbon film.
  • the pH of the obtained silicon negative electrode active material is 9.3, and the crystallite size corresponding to the silicon (111) crystal plane is 2.7nm.
  • the water-based homogenate slurry containing this material can last for more than a week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 560.7mAh/g, and the first charge-discharge efficiency was 86.1%.
  • the measured volume energy density of the whole battery reached 758.8Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 89%, and the battery expansion rate after 500 cycles was 9.7%.
  • Example 6 adopts a similar process of coating the carbon film. Only the heat treatment process is adjusted to 1000°C for 2.5 hours, and the same spray drying process as in Example 5 is used, but the doping source is Replaced with 13.9 g of aluminum nitrate nonahydrate, and the powder obtained by spray drying is changed to a heat treatment process of heating at 600° C. for 2 hours to obtain silicon oxide compound particles doped with aluminum and coated with a carbon film. Next, the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 51.3g, and the heat treatment process is adjusted to 575°C for 6 hours to obtain a lithium-containing coated carbon film doped with aluminum. Siloxane.
  • the pH of the obtained silicon negative electrode active material is 10.9, and the crystallite size corresponding to the silicon (111) crystal plane is 3.1nm.
  • the aqueous homogenate slurry containing this material can last for 72 hours without gas production under the accelerated test at 65°C. .
  • the final measurement of the half-cell containing the silicon negative electrode has a specific capacity of 536.9mAh/g for the first lithium insertion, and a first charge-discharge efficiency of 89.1%.
  • the measured volume energy density of the whole battery reached 778.2Wh/L, the capacity retention rate after 500 charge and discharge cycles was 87.2%, and the battery expansion rate after 500 cycles was 10.8%.
  • Example 7 silicon oxide particles with a median diameter of 1 ⁇ m were used instead, and a similar carbon coating process was adopted. Only the heat treatment process was adjusted to 700°C for 6 hours, and the The same spray drying process as in Example 5, but the addition amount of magnesium acetate tetrahydrate was adjusted to 220g, and the powder obtained by spray drying was changed to a heat treatment process of heating at 700°C for 6 hours to obtain a coating doped with magnesium Silicon oxide particles of carbon film. Next, the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 74.1g, and the heat treatment process is adjusted to 650°C for 5 hours to obtain a lithium-containing coated carbon film doped with magnesium. Siloxane.
  • the pH of the obtained silicon negative electrode active material is 10.9, and the crystallite size corresponding to the silicon (111) crystal plane is 4.1nm.
  • the aqueous homogenate slurry containing this material can last for more than one week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 524.2mAh/g, and the first charge-discharge efficiency was 89.8%.
  • the measured volumetric energy density of the whole battery reached 777.2Wh/L, the capacity retention rate after 500 charge-discharge cycles was 83.1%, and the battery expansion rate after 500 cycles was 10.8%.
  • Example 8 uses silicon-oxygen compound particles with a median diameter of 9 ⁇ m, and uses the same coating carbon film layer and spray drying process, but the doping source is changed to 71.1 g titanate Butyl ester and 44 g of magnesium acetate tetrahydrate, and the spray-dried powder is changed to a heat treatment process of heating at 900° C. for 3 hours to obtain silicon oxide compound particles doped with titanium and magnesium elements coated with a carbon film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 45.6g, and the heat treatment process is adjusted to 700°C for 5 hours to obtain a coated carbon film doped with titanium and magnesium. Lithium-containing silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material is 10, and the crystallite size corresponding to the silicon (111) crystal plane is 3.7nm.
  • the aqueous homogenate slurry containing this material can last for more than one week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 528mAh/g, and the first charge-discharge efficiency is 90.9%.
  • the measured volume energy density of the whole battery reached 787.1Wh/L, the capacity retention rate after 500 charge and discharge cycles was 86.4%, and the battery expansion rate after 500 cycles was 11.9%.
  • Example 9 silicon oxide compound particles with a median particle diameter of 15 ⁇ m are used, and the same process of coating the carbon film layer is adopted to obtain silicon oxide compound powder coated with the carbon film layer. Subsequently, 27g of nano-zirconia was uniformly coated on the surface of the above particles by dry coating, and kept at 1000°C for 2 hours in a nitrogen atmosphere to obtain silicon oxide compound powder doped with zirconium-coated carbon film . Next, the same lithium metal doping process is used to obtain a lithium-containing silicon-oxygen compound doped with zirconium-coated carbon film.
  • the pH of the obtained silicon negative electrode active material is 9.9, and the crystallite size corresponding to the silicon (111) crystal plane is 3.8nm.
  • the aqueous homogenate slurry containing this material can last for more than a week without gas production under the accelerated experiment at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 527mAh/g, and the first charge-discharge efficiency is 91.1%.
  • the measured volume energy density of the whole battery reached 788.4Wh/L, the capacity retention rate after 500 charge and discharge cycles was 82.1%, and the battery expansion rate after 500 cycles was 12.5%.
  • Example 10 Compared with Example 6, in Example 10, a similar process of coating the carbon film layer was adopted, only the addition amount of pitch was adjusted to 70g, and the same spray drying process as in Example 6 was used, but the doping source was replaced with 11.4 g zinc nitrate hexahydrate and 34.7 g aluminum nitrate nonahydrate, and the powder obtained by spray drying is changed to a heat treatment process of heating at 700° C. for 3 hours to obtain silicon oxide compound particles doped with zinc and aluminum elements coated with a carbon film. Next, the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 57g, and the heat treatment process is adjusted to 600°C for 6 hours to obtain the content of the coated carbon film doped with zinc and aluminum. Lithium silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material is 10.7, and the crystallite size corresponding to the silicon (111) crystal plane is 3.2nm.
  • the aqueous homogenate slurry containing this material can last for more than a week without gas production under the accelerated experiment at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 530.4 mAh/g, and the first charge-discharge efficiency is 89.9%.
  • the measured volume energy density of the whole battery reached 781.9Wh/L, the capacity retention rate after 500 charge-discharge cycles was 86.8%, and the battery expansion rate after 500 cycles was 11.1%.
  • Example 11 Compared with Example 10, in Example 11, a similar carbon coating process was used, only the amount of pitch added was adjusted to 100g, and the same spray drying process as in Example 10 was used, but the doping source was replaced with 208.4 g Aluminum nitrate nonahydrate, and the powder obtained by spray drying is changed to a heat treatment process of heating at 900° C. for 2 hours to obtain silicon oxide compound particles doped with aluminum and coated with a carbon film. Next, a similar thermal doping method is used for lithium metal doping, and the heat treatment process is adjusted to 700° C. for 6 hours to obtain a lithium-containing silicon-oxygen compound doped with aluminum and coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material is 10.2, and the crystallite size corresponding to the silicon (111) crystal plane is 4.2nm.
  • the aqueous homogenate slurry containing this material can last for more than a week without gas generation under the accelerated test at 65°C. .
  • the final measurement of the half-cell containing the silicon anode has a first lithium insertion specific capacity of 521.3mAh/g, and a first charge-discharge efficiency of 91.4%. It is measured that the volumetric energy density of the whole battery reaches 793.5Wh/L, the capacity retention rate after 500 charge-discharge cycles is 86.1%, and the battery expansion rate after 500 cycles is 11.9%.
  • Example 6 Compared with Example 6, the same carbon coating and spray drying process is used in Example 12, but the doping source is replaced with 353g magnesium acetate tetrahydrate and 182g zinc nitrate hexahydrate, and the powder obtained by spray drying A heat treatment process of heating at 1000°C for 3 hours is used to obtain silicon-oxygen compound particles doped with magnesium and zinc elements coated with a carbon film. Next, the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 34.3g, and the heat treatment process is adjusted to 850°C for 2 hours to obtain a coated carbon film doped with magnesium and zinc. Lithium-containing silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material is 8.7, and the crystallite size corresponding to the silicon (111) crystal plane is 10.2nm.
  • the water-based homogenate slurry containing this material can last for more than a week without gas production under the accelerated experiment at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 486mAh/g, and the first charge-discharge efficiency is 92%.
  • the measured volume energy density of the whole battery reached 765.3Wh/L, the capacity retention rate after 500 charge-discharge cycles was 82.1%, and the battery expansion rate after 500 cycles was 13.5%.
  • Example 13 Compared with Example 12, the same carbon coating, spray drying doping and lithium metal doping process were used in Example 13, and only the doping source was replaced with 706g magnesium acetate tetrahydrate and 364g zinc nitrate hexahydrate to obtain Lithium-containing silicon-oxygen compound doped with magnesium and zinc elements to coat a carbon film.
  • the pH of the obtained silicon negative electrode active material is 8.5, and the crystallite size corresponding to the silicon (111) crystal plane is 16 nm.
  • the aqueous homogenate slurry containing this material can last for more than one week without gas generation under the accelerated experiment at 65°C.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 452mAh/g, and the first charge-discharge efficiency was 92%.
  • the measured volumetric energy density of the whole battery reached 739.3Wh/L, the capacity retention rate after 500 charge and discharge cycles was 80.5%, and the battery expansion rate after 500 cycles was 15%.
  • Example 14 Compared with Example 5, in Example 14, the same carbon coating, spray drying doping and lithium metal doping processes are used, and only the doping source is replaced with 4.4g magnesium acetate tetrahydrate, and the result is doped with magnesium. Lithium-containing silicon-oxygen compound coated with carbon film.
  • the pH of the obtained silicon negative electrode active material is 9.5, and the crystallite size corresponding to the silicon (111) crystal plane is 2.7nm.
  • the aqueous homogenate slurry containing this material can persist for 24 hours without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 562mAh/g, and the first charge-discharge efficiency was 86.1%.
  • the measured volume energy density of the whole battery reached 758.8Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 89%, and the battery expansion rate after 500 cycles was 9.7%.
  • silicon-oxygen compound particles Take 1000 grams of silicon-oxygen compound particles with a median particle size of 4 ⁇ m (silicon-oxygen ratio of 1:1) and mix with 100 grams of lithium hydride, and use the thermal doping method for lithium metal doping.
  • the heat treatment process is 800 °C for 2 hours to obtain Lithium-containing silicon oxygen compound.
  • 500 g of the above particles were mixed with 25 g of metallic magnesium powder, and the temperature was maintained at 850° C. for 1.5 hours in an argon atmosphere to obtain lithium-containing silicon-oxygen compound particles doped with magnesium.
  • a carbon film layer was coated on the surface of the particles by chemical vapor deposition method, and acetylene was used as a carbon source, and the coating reaction was carried out at 850°C for 1 hour to obtain a lithium-containing silicon-oxygen compound doped with magnesium to coat the carbon film. Particles.
  • the pH of the obtained silicon negative electrode active material is 9.5, and the crystallite size corresponding to the silicon (111) crystal plane is 26nm.
  • the aqueous homogenate slurry containing this material can last for more than one week without gas generation under the accelerated experiment at 65°C.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 462.6mAh/g, and the first charge-discharge efficiency was 92.6%.
  • the measured volume energy density of the whole battery reached 730.8Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 76.1%, and the battery expansion rate after 500 cycles was 17.8%.
  • the coating kettle After mixing 1000g of silicon-oxygen compound particles with a median diameter of 5 ⁇ m (the silicon-oxygen atomic ratio is 1:1), 10g of nano-zirconia and 70g of low-temperature coal pitch powder in the coating kettle, add 2000g while stirring. Dimethylformamide, disperse the mixed powder evenly in dimethylformamide. Subsequently, the coating kettle is heated to 140°C and kept at a constant temperature for 3 hours, and finally heated to 160°C and kept at a constant temperature until the dimethylformamide is evaporated to dryness to obtain a coal pitch-coated silicon oxide compound material. The above-mentioned material was heated to 900° C. under a nitrogen atmosphere and kept for 4 hours to carbonize the coal pitch.
  • the material obtained after cooling was passed through a 500-mesh sieve. According to the results of scanning electron microscope and X-ray energy spectroscopy (EDS), it was proved that a silicon oxide compound powder with a complete carbon film coating and uniformly doped with zirconium was obtained. The particle surface No zirconium-containing compound remains, indicating that zirconium has been doped into the silicon-oxygen compound. At the same time, the results of X-ray energy spectrum analysis (EDS) showed that the zirconium content on the surface of the particles was as high as 2.5 wt%, which was significantly higher than the actual doped zirconium content in the silicon-oxygen compound, indicating that the zirconium element was enriched on the surface of the particles.
  • EDS X-ray energy spectrum analysis
  • the powder obtained was placed in a tube furnace and heat-treated in an argon atmosphere at a temperature of 10°C/ The temperature rise rate of min is raised to 550°C and kept for 3 hours. After natural cooling, lithium-doped silicon oxide compound powder can be obtained.
  • the above-mentioned silicon oxide compound particles are mixed with deionized water, and the pH value of the dispersion liquid can be measured to be 10.9 by using a precision pH tester from Ohaus Instruments (Shanghai) Co., Ltd.
  • a powder resistance meter is used to test the resistivity of the lithium-containing silicon oxygen compound particles, and the resistivity value of the powder material under a pressure of 20 MPa can be measured as 24 ⁇ *cm.
  • the silicon-oxygen compound contains a small amount of zirconium silicate phase and copper-silicon alloy phase at the same time.
  • the crystallite size corresponding to the silicon (111) crystal plane of the silicon-oxygen compound is 2.3 nm.
  • silicon-oxygen compound material Take 12 parts of the above-mentioned silicon-oxygen compound material, 83 parts of artificial graphite, 2.5 parts of conductive additives, 2.5 parts of binder, homogenize in an aqueous system, take part of the aqueous homogenate slurry for water resistance and stability test, other slurries Used for coating, then drying and rolling to obtain silicon-containing negative pole piece.
  • Stability evaluation of the aqueous slurry containing the above-mentioned siloxane compound material Take 30 g of the above-mentioned aqueous homogenized slurry and store it at 65°C, and confirm when the above-mentioned slurry starts to generate gas under this condition. Under these harsh conditions, the slurry can last for more than a week without producing gas. In the conventional water system homogenization process, the slurry temperature is generally maintained at 25-30°C. Therefore, the method for evaluating the stability of the slurry used in this patent is far more stringent than the actual water-based homogenate coating production process. Under this evaluation method, if the slurry can persist for 24 hours without generating gas, it can be considered that the silicon oxide material in the slurry has strong water resistance and good stability, and can be used for large-scale water system homogenization.
  • Half-cell evaluation stack the above-mentioned silicon-containing negative pole piece with the diaphragm, lithium sheet, and stainless steel gasket in sequence, add 200 ⁇ L of electrolyte and seal to make a 2016-type lithium-ion half-cell.
  • the silicon oxide compound of Example 17 is not coated with a carbon film layer, and 20 g nano zinc oxide and 25.5 g nano nickel oxide are uniformly coated on the surface of 1000 g silicon oxide compound particles directly by dry coating. In a nitrogen atmosphere, heat preservation is performed at 950°C for 3 hours to obtain a silicon-oxygen compound doped with zinc and nickel. Next, the above-mentioned silicon-oxygen compound is doped with lithium metal by an electrochemical pre-lithium method to obtain a lithium-containing silicon-oxygen compound doped with zinc and nickel.
  • the obtained silicon negative electrode active material contains zinc silicate phase and nickel-silicon alloy phase respectively.
  • the pH of the material is 10.2, and the crystallite size corresponding to the silicon (111) crystal plane is 2.7 nm.
  • the aqueous homogenate containing the material Under the accelerated experiment at 65°C, the material can last for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 542.3mAh/g, and the first charge-discharge efficiency was 87.6%.
  • the measured volume energy density of the whole battery reached 764.3Wh/L, the capacity retention rate after 500 charge and discharge cycles was 84%, and the battery expansion rate after 500 cycles was 11.3%.
  • Example 18 Compared with Example 16, in Example 18, the pitch content is reduced to 50 g, and the heat treatment process of the coated carbon film layer is adjusted to 1000° C. for 2 hours to obtain silicon oxide compound particles coated with the carbon film layer. Subsequently, 1.9g of nano alumina and 1.3g of nanomanganese oxide were uniformly coated on the surface of 1000g of the above particles by dry coating, and the temperature was kept at 700°C for 3 hours in a nitrogen atmosphere to obtain doped aluminum and manganese. The element of the silicon-oxygen compound that covers the carbon film. Next, the thermal doping method is used for lithium metal doping.
  • 500 grams of the above particles are mixed with 57 grams of lithium hydride, and the mixed powder is placed in a tube furnace and heat-treated in an argon atmosphere at a temperature of 10°C/ The heating rate of min is raised to 600°C and kept for 6 hours. After natural cooling, the material is taken out of the tube furnace and passed through a 500-mesh screen to obtain a lithium-containing silicon-oxygen compound doped with aluminum and manganese elements coated carbon film .
  • the pH of the obtained silicon negative electrode active material is 10.8, and the crystallite size corresponding to the silicon (111) crystal plane is 3.2nm.
  • the water-based homogenate slurry containing this material can last for more than one week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 534 mAh/g, and the first charge-discharge efficiency is 89.9%.
  • the measured volume energy density of the whole battery reached 781Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 86.8%, and the battery expansion rate after 500 cycles was 11.1%.
  • Example 19 silicon oxide particles with a median particle size of 1 ⁇ m were used.
  • the carbon film coating process similar to that in Example 1 was used to reduce the pitch content to 50 g and the carbon coating
  • the heat treatment process of the film layer is adjusted to 950° C. for 3 hours to obtain silicon oxide compound particles covering the carbon film layer.
  • a spray drying process similar to that in Example 1 was used, but the doping source was replaced with 284.4g of tetrabutyl titanate and 289.4g of ferric nitrate nonahydrate, and the spray-dried powder was heated at 800°C for 6 hours of heat treatment. Process to obtain silicon-oxygen compound particles doped with titanium and iron elements coated with a carbon film.
  • the thermal doping method is used for lithium metal doping. Specifically, 500 grams of the above particles are mixed with 74.1 grams of lithium hydride, and the mixed powder is placed in a tube furnace and heat-treated in an argon atmosphere at a temperature of 10°C/ The heating rate of min is raised to 650°C and kept for 5 hours. After natural cooling, the material is taken out of the tube furnace and passed through a 500-mesh screen to obtain a lithium-containing silicon-oxygen compound doped with titanium and iron-coated carbon film .
  • the pH of the obtained silicon negative electrode active material was 10.3, the powder resistivity was 1 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane was 4.6nm.
  • the aqueous homogenate slurry containing the material was subjected to accelerated experiments at 65°C. , Can persist for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 500.1 mAh/g, and the first charge-discharge efficiency is 90.2%.
  • the measured volumetric energy density of the whole battery reached 768.4Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 82.3%, and the battery expansion rate after 500 cycles was 11.8%.
  • Example 20 silicon oxide compound particles with a median diameter of 5 ⁇ m were used instead, and the same carbon coating and spray drying process as in Example 19 was used, but the doping source was replaced with 8.8g Magnesium acetate tetrahydrate and 108.5g ferric nitrate nonahydrate, and the powder obtained by spray drying is changed to a heat treatment process of heating at 900°C for 3 hours to obtain silicon oxide compound particles doped with magnesium and iron elements coated with a carbon film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 51.3g, and the heat treatment process is adjusted to 575°C for 6 hours to obtain a coated carbon film doped with magnesium and iron. Lithium-containing silicon oxygen compound.
  • the pH of the obtained silicon anode active material was 10.8, the powder resistivity was 8 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane was 3.1nm.
  • the aqueous homogenate slurry containing this material was subjected to accelerated experiments at 65°C. , Can persist for more than a week without gas production.
  • the final measurement of the half-cell containing the silicon negative electrode has a specific capacity of 533.2mAh/g for the first lithium insertion, and a first charge-discharge efficiency of 89.3%.
  • the measured volumetric energy density of the whole battery reached 775.3Wh/L, the capacity retention rate after 500 charge and discharge cycles was 87.2%, and the battery expansion rate after 500 cycles was 10.8%.
  • Example 21 uses a similar process of coating the carbon film, only adjusts the heat treatment process to 800°C for 2 hours, and uses the same spray drying process as Example 20, but replaces the doping source It is 13.2g magnesium acetate tetrahydrate and 22g copper acetate monohydrate, and the powder obtained by spray drying is changed to a heat treatment process of heating at 800°C for 3 hours to obtain silicon oxide compound particles doped with magnesium and copper elements coated with carbon film . Scanning electron microscopy results show that there is no magnesium or copper-containing material remaining on the surface of the particles, indicating that all magnesium and copper elements have been doped into the silicon-oxygen compound.
  • the results of X-ray energy spectrum analysis showed that the magnesium content on the surface of the particles was 0.2%, and the copper content was 0.7%, which is close to the actual doped magnesium and copper content in the silicon-oxygen compound, indicating that there is no magnesium and copper. Enriched in the surface layer of the particles.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 28.5g, and the heat treatment process is adjusted to 550°C for 6 hours to obtain a coated carbon film doped with magnesium and copper. Lithium-containing silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material is 9.3, the powder resistivity is 20 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane is 1.2nm.
  • the aqueous homogenate slurry containing this material is subjected to an accelerated experiment at 65°C. , Can persist for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 564.7mAh/g, and the first charge-discharge efficiency was 85.8%.
  • the measured volume energy density of the whole battery reached 757.8Wh/L, the capacity retention rate after 500 charge-discharge cycles was 89%, and the battery expansion rate after 500 cycles was 9.7%.
  • Example 22 uses silicon-oxygen compound particles with a median particle size of 9 ⁇ m.
  • the carbon film coating process is the same as that of Example 20, and then 9.5 g nanometers are coated by dry coating.
  • Alumina and 18.8g of nano-copper oxide are uniformly coated on the surface of 1000g of the above-mentioned particles, and the temperature is maintained at 900°C for 3 hours in a nitrogen atmosphere to obtain a silicon-oxygen compound doped with aluminum and copper to coat the carbon film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 57g, and the heat treatment process is adjusted to 700°C for 5 hours to obtain the content of the coated carbon film doped with aluminum and copper.
  • Lithium silicon oxygen compound is used for lithium metal doping, but the amount of lithium hydride is adjusted to 57g, and the heat treatment process is adjusted to 700°C for 5 hours to obtain the content of the coated carbon film doped with aluminum and copper.
  • the pH of the obtained silicon negative electrode active material was 10.2, the powder resistivity was 7 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane was 4.2nm.
  • the aqueous homogenate slurry containing this material was subjected to accelerated experiments at 65°C. , Can persist for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 521.3 mAh/g, and the first charge-discharge efficiency was 91.6%.
  • the measured volume energy density of the whole battery reached 793.2Wh/L, the capacity retention rate after 500 charge and discharge cycles was 86.5%, and the battery expansion rate after 500 cycles was 12.1%.
  • Example 23 uses a similar process of coating the carbon film layer, only adjusts the heat treatment process to 1000°C for 2.5 hours, and uses the same spray drying process as Example 20, but replaces the doping source 166.7g of aluminum nitrate nonahydrate, 4.3g of yttrium nitrate hexahydrate and 223g of manganese acetate tetrahydrate, and the spray-dried powder is heated at 850°C for 6 hours to obtain a heat treatment process doped with aluminum, yttrium and manganese Silicon oxide compound particles coated with carbon film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 45.6g, and the heat treatment process is adjusted to 700°C for 5 hours to obtain coated carbon doped with aluminum, yttrium and manganese. Lithium-containing silicon-oxygen compound of the film.
  • the pH of the obtained silicon negative electrode active material is 9.8, the powder resistivity is 0.1 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane is 4.2nm.
  • the aqueous homogenate slurry containing this material is accelerated at 65°C. It can be maintained for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 511 mAh/g, and the first charge-discharge efficiency is 91.1%.
  • the measured volumetric energy density of the whole battery reached 781.2Wh/L, the capacity retention rate after 500 charge-discharge cycles was 86.6%, and the battery expansion rate after 500 cycles was 11.9%.
  • Example 24 uses the same carbon coating and spray drying process, but replaces the doping source with 264g magnesium acetate tetrahydrate and 339.2g nickel acetate tetrahydrate, and spray-dried the powder obtained
  • a heat treatment process of heating at 800°C for 8 hours is used to obtain silicon-oxygen compound particles doped with magnesium and nickel elements coated with a carbon film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 57g, and the heat treatment process is adjusted to 600°C for 6 hours to obtain the content of the coated carbon film doped with magnesium and nickel. Lithium silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material is 10, the powder resistivity is 0.01 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane is 4.3nm.
  • the aqueous homogenate slurry containing this material is accelerated at 65°C. It can be maintained for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 492.4mAh/g, and the first charge-discharge efficiency was 90.3%.
  • the measured volume energy density of the whole battery reached 765.9Wh/L, the capacity retention rate after 500 charge and discharge cycles was 87%, and the battery expansion rate after 500 cycles was 12%.
  • Example 25 uses silicon-oxygen compound particles with a median particle size of 15 ⁇ m.
  • the carbon film coating process is the same as that of Example 18, and then 8.35g nanometers are coated by dry coating. Titanium oxide, 13.3g nano-alumina and 38.25g nano-nickel oxide are uniformly coated on the surface of 1000g of the above-mentioned particles, and are kept at 900°C for 2 hours in a nitrogen atmosphere to obtain coated carbon doped with titanium, aluminum and nickel. Silicon oxide particles of the film.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 34.3g, and the heat treatment process is adjusted to 850°C for 2 hours to obtain coated carbon doped with titanium, aluminum and nickel. Lithium-containing silicon-oxygen compound of the film.
  • the pH of the obtained silicon negative electrode active material is 9.3, the powder resistivity is 1 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane is 10.2nm.
  • the aqueous homogenate slurry containing this material is subjected to accelerated experiments at 65°C. , Can persist for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 498 mAh/g, and the first charge and discharge efficiency is 92.5%.
  • the measured volume energy density of the whole battery reached 768.4Wh/L, the capacity retention rate after 500 charge-discharge cycles was 80.4%, and the battery expansion rate after 500 cycles was 14.3%.
  • Example 26 uses silicon-oxygen compound particles with a median particle size of 5 ⁇ m, and uses the same coating carbon film layer, spray-drying doping and lithium metal doping process as in Example 19.
  • the doping source was replaced with 568.8 g of tetrabutyl titanate and 578.7 g of nonahydrate iron nitrate to obtain a lithium-containing silicon-oxygen compound doped with titanium and iron elements on the coated carbon film.
  • the pH of the obtained silicon negative electrode active material is 9, the powder resistivity is 0.05 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane is 5.6nm.
  • the aqueous homogenate slurry containing this material is accelerated at 65°C. It can be maintained for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 470mAh/g, and the first charge-discharge efficiency is 91.6%.
  • the measured volume energy density of the whole battery reached 766.8Wh/L, the capacity retention rate after 500 charge and discharge cycles was 85.8%, and the battery expansion rate after 500 cycles was 12.7%.
  • Example 27 uses the same carbon coating and spray drying doping process, only adjusting the doping source to 4.4g magnesium acetate tetrahydrate and 1.57g copper acetate monohydrate to obtain doped The silicon oxide compound particles of the carbon film coated with magnesium and copper elements.
  • the thermal doping method is used for lithium metal doping, but the amount of lithium hydride is adjusted to 57g, and the heat treatment process is adjusted to 600°C for 6 hours to obtain the content of the coated carbon film doped with magnesium and copper. Lithium silicon oxygen compound.
  • the pH of the obtained silicon negative electrode active material was 10.8, the powder resistivity was 30 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane was 1.9nm.
  • the aqueous homogenate slurry containing this material was subjected to accelerated experiments at 65°C. , Can persist for more than a week without gas production.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 545mAh/g, and the first charge-discharge efficiency was 89.6%.
  • the measured volume energy density of the whole battery reached 783.2Wh/L, the capacity retention rate after 500 charge and discharge cycles was 87.4%, and the battery expansion rate after 500 cycles was 10.6%.
  • Example 28 uses a similar carbon coating process, but the heat treatment process is adjusted to 1000° C. for 2.5 hours to obtain a silicon oxide compound coating the carbon film. Subsequently, the same spray drying process as in Example 12 was used, and the doping source was replaced with 30.8 g magnesium acetate tetrahydrate and 15.6 g manganese acetate tetrahydrate to obtain silicon oxide compound particles doped with magnesium and manganese. . Next, the same lithium metal doping process as in Example 12 is used to obtain a lithium-containing silicon-oxygen compound doped with magnesium and manganese in the coated carbon film.
  • the pH of the obtained silicon negative electrode active material is 10.6, and the crystallite size corresponding to the silicon (111) crystal plane is 3.2nm.
  • the aqueous homogenate slurry containing this material can last for more than a week without gas production under the accelerated test at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 532mAh/g, and the first charge-discharge efficiency is 89.9%. It is measured that the volumetric energy density of the whole battery reaches 780Wh/L, the capacity retention rate after 500 charge-discharge cycles is 86.8%, and the battery expansion rate after 500 cycles is 11.1%.
  • the doping source is replaced with only 8.8g magnesium acetate tetrahydrate, so the product is a lithium-containing silicon oxide compound doped with a single magnesium element and coated with a carbon film.
  • the pH of the obtained silicon anode active material was 10.8, the powder resistivity was 46 ⁇ *cm, and the crystallite size corresponding to the silicon (111) crystal plane was 1.9nm.
  • the aqueous homogenate slurry containing this material was subjected to accelerated experiments at 65°C. , Can persist for 72 hours without gas production. Finally, it is measured that the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 545 mAh/g, and the first charge-discharge efficiency is 89%.
  • the measured volume energy density of the whole battery reached 779Wh/L, the capacity retention rate after 500 charge and discharge cycles was 86.4%, and the battery expansion rate after 500 cycles was 10.6%.
  • silicon-oxygen compound particles with a median diameter of 5 ⁇ m (silicon-oxygen ratio of 1:1) and mix with 100 grams of lithium hydride, and use the thermal doping method for lithium metal doping.
  • the heat treatment process is 800 °C for 2 hours to obtain Lithium-containing silicon oxygen compound.
  • 500 g of the above particles were uniformly mixed with 25 g of metallic magnesium powder and 9.4 g of nano-copper oxide, and the temperature was maintained at 850° C. for 1.5 hours in an argon atmosphere to obtain lithium-containing silicon-oxygen compound particles doped with magnesium and copper.
  • a carbon film layer was coated on the surface of the particles by chemical vapor deposition method, and acetylene was used as a carbon source, and the coating reaction was carried out at 850°C for 1 hour to obtain a carbon film-coated lithium-containing silicon doped with magnesium and copper. Oxygen compound particles.
  • the pH of the obtained silicon negative electrode active material is 9.5, and the crystallite size corresponding to the silicon (111) crystal plane is 26nm.
  • the aqueous homogenate slurry containing this material can last for more than one week without gas generation under the accelerated experiment at 65°C.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 461.6 mAh/g, and the first charge and discharge efficiency is 92.8%.
  • the measured volume energy density of the whole battery reached 726.8Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 76.1%, and the battery expansion rate after 500 cycles was 17.8%.
  • the difference is that there is no subsequent spray drying and lithium doping process, so the product is a silicon-oxygen compound coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material is 7.4, and the crystallite size corresponding to the silicon (111) crystal plane is 2.7nm.
  • the aqueous homogenate slurry containing this material can last for more than a week without gas production under the accelerated experiment at 65°C. .
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was 580.5 mAh/g, and the first charge-discharge efficiency was 83%.
  • the measured volume energy density of the whole battery reaches 723Wh/L, the capacity retention rate after 500 cycles of charge and discharge is 90%, and the battery expansion rate after 500 cycles is 9.5%.
  • the difference is that there is no process of spray drying and corresponding heat treatment to dope the magnesium element, so the product is a lithium-containing silicon-oxygen compound coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material is 9.5, and the crystallite size corresponding to the silicon (111) crystal plane is 2.7nm.
  • the water-based homogenate slurry containing this material has been significantly produced within 1 hour under the accelerated test at 65°C. gas.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode was measured to be 562mAh/g, and the first charge-discharge efficiency was 86.1%. Due to the poor stability of the slurry, the problems of gas production and poor rheology occurred during the homogenization coating process.
  • the quality of the coated pole pieces was poor, and there were many pits, poor adhesion, and powder falling. , which greatly affects the performance of the full battery.
  • the actual measured volume energy density of the whole battery is 728.9Wh/L, the capacity retention rate after 500 charge-discharge cycles is 79%, and the battery expansion rate after 500 cycles is 15.2%.
  • the difference is that during the lithium doping process, the amount of lithium hydride is adjusted to 148.2 g, and the product is a lithium-containing silicon-oxygen compound doped with aluminum and coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material was 12.5, and the crystallite size corresponding to the silicon (111) crystal plane was 18 nm.
  • the water-based homogenate slurry containing the material was subjected to an accelerated experiment at 65° C., gas production occurred within 12 hours.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 429 mAh/g, and the first charge-discharge efficiency is 93.4%.
  • the measured volume energy density of the whole battery reached 733.1Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 76%, and the battery expansion rate after 500 cycles was 13%.
  • the difference is that during the process of lithium doping, the amount of lithium hydride is adjusted to 125.4 g, and the product is a lithium-containing silicon-oxygen compound doped with aluminum, yttrium, and manganese elements coated with a carbon film.
  • the pH of the obtained silicon negative electrode active material was 12.5, and the crystallite size corresponding to the silicon (111) crystal plane was 17 nm.
  • the water-based homogenate slurry containing the material was subjected to an accelerated experiment at 65° C., gas production occurred within 12 hours.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 417mAh/g, and the first charge-discharge efficiency is 93.4%. It is measured that the volumetric energy density of the whole battery reaches 728Wh/L, the capacity retention rate after 500 cycles of charge and discharge is 76%, and the battery expansion rate after 500 cycles is 13%.
  • the material obtained after cooling is crushed and passed through a 500-mesh screen to obtain silicon oxide compound powder coated with a carbon film/Ketjen black composite film layer.
  • the coarse lithium aluminum hydride powder is crushed by a planetary ball mill and then passed through a 500-mesh screen to obtain the lithium aluminum hydride fine powder.
  • the sieved lithium aluminum hydride fine powder Take 150 g of the sieved lithium aluminum hydride fine powder, and mix 500 g of the silicon oxide compound powder coated with the carbon film/Ketjen black composite film layer in a VC mixer at high speed for 20 minutes.
  • the material is removed from the tube Take it out of the furnace and pass it through a 500-mesh screen to obtain a lithium-containing silicon-oxygen compound doped with aluminum.
  • a lithium-containing silicon-oxygen compound doped with aluminum Through X-ray diffraction analysis, there is a significant metallic aluminum phase in the silicon anode active material obtained at this time (as shown in Figure 5), indicating that the aluminum doping source and doping process used in this comparative example are easier to obtain
  • the reduced metal is doped with aluminum, instead of doped with oxygen-containing compounds of aluminum. Since the metallic phase of aluminum cannot effectively protect the lithium-containing silicon-oxygen material, and even promotes the gas-generating reaction between water and the material, the water-based homogenate slurry containing the material generates gas rapidly within 1 hour under the accelerated experiment at 65°C.
  • the silicon (111) crystal plane of this material has two crystal grain sizes, one is 5.4nm and the other is as high as 71nm, indicating that the presence of metal aluminum promotes the localization of silicon crystal grains. grow up.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 432 mAh/g, and the first charge and discharge efficiency is 87%.
  • the measured volume energy density of the full battery reaches 702.3Wh/L. Due to the excessive gas production of the slurry and the poor quality of the pole pieces, the capacity retention rate of the full battery containing the silicon negative electrode after 500 charge and discharge cycles was 68%, and the battery expansion rate after 500 cycles was 21%.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 485mAh/g, and the first charge-discharge efficiency is 89%.
  • the measured volumetric energy density of the whole battery reached 749Wh/L, the capacity retention rate after 500 cycles of charge and discharge was 73.2%, and the battery expansion rate after 500 cycles was 19%.
  • the crystallite size corresponding to the silicon (111) crystal plane of the obtained silicon negative electrode active material was 9 nm, and the water-based homogenate slurry containing the material was subjected to an accelerated experiment at 65° C., gas production occurred within 2 hours.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 502 mAh/g, and the first charge-discharge efficiency is 88.7%. It is measured that the volumetric energy density of the whole battery reaches 752Wh/L, the capacity retention rate after 500 charge-discharge cycles is 76.5%, and the battery expansion rate after 500 cycles is 16.8%.
  • the coating kettle After mixing 1000g of silicon-oxygen compound particles with a median diameter of 6 ⁇ m (the silicon-oxygen atomic ratio is 1:1) and 65g of low-temperature coal tar pitch powder in the coating kettle, add 2000g of dimethylformamide while stirring. , Disperse the mixed powder evenly in dimethylformamide. Subsequently, the coating kettle is heated to 140°C and kept at a constant temperature for 3 hours, and finally heated to 160°C and kept at a constant temperature until the dimethylformamide is evaporated to dryness to obtain a coal pitch-coated silicon oxide compound material. The above-mentioned material is heated to 900° C.
  • the coarse lithium hydride powder is crushed by a planetary ball mill and passed through a 600-mesh screen to obtain a fine lithium hydride powder whose maximum particle size is approximately equal to 23 ⁇ m.
  • Put the above-mentioned mixed powder into a tube furnace carry out a lithium-doped heat treatment in an argon atmosphere, raise the temperature to 750°C at a heating rate of 10°C/min, and then keep it for 60 minutes. After natural cooling, the material is taken out of the tube furnace and Go through a 500-mesh screen to obtain the final silicon-based composite product.
  • the crystallite size corresponding to the silicon (111) crystal plane of the obtained silicon negative electrode active material was 6.5 nm, and the water-based homogenate slurry containing the material had obvious gas production within 1 hour under the accelerated experiment at 65°C.
  • the first lithium insertion specific capacity of the half-cell containing the silicon negative electrode is 508 mAh/g, and the first charge-discharge efficiency is 88%.
  • the measured volume energy density of the whole battery reaches 753.1Wh/L, the capacity retention rate after 500 cycles of charge and discharge is 76.2%, and the battery expansion rate after 500 cycles is 16.1%.

Abstract

本发明涉及一种用于电池的负极活性材料，其具有负极活性物质颗粒，所述负极活性物质颗粒含有硅氧化合物，其特征在于，所述负极活性物质颗粒包括锂元素以及非锂掺杂金属，其中，所述非锂掺杂金属包括金属M1，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种，所述非锂掺杂金属占所述负极活性材料的含量为0.01-20wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。本发明的负极活性材料耐水性强，利用本发明的负极活性材料制备的二次电池具有容量高、库伦效率高、循环寿命长的优势。

Description

一种用于电池的负极活性材料及其制备方法 技术领域
本发明涉及电池领域，特别涉及一种用于电池的负极活性材料及其制备方法。
背景技术
近年来，随着各种便携式电子装置和电动汽车的不断发展，其对于能量密度高、循环寿命长的电池的需求日益迫切。目前商业化的锂离子电池的负极材料主要为石墨，但由于理论容量低(372mAh/g)，限制了电池能量密度的进一步提高。而单质硅负极材料则具有很高的容量优势(室温下嵌锂态为Li 15Si 4，理论储锂容量约3600mAh/g)，是目前商业石墨负极材料理论容量的10倍左右，具有其它负极材料无法匹敌的高容量优势，因此成为了学术界和产业界多年来的研发热点，并逐渐从实验室研发走向商业应用。目前针对硅负极材料的开发主要有三种，一是单质硅(包括纳米硅、多孔硅、非晶硅等)及其同碳材料的复合材料；二是硅与其它金属(如铁、锰、镍、铬、镉、锡、铜等)、非金属(碳、氮、磷、硼等)成分组合而成的合金材料；三是硅氧化合物及其同碳材料的复合材料。以上三种结构中，单质硅材料的理论容量最高，因此理论能量密度也最高。然而，单质硅负极材料在嵌脱锂过程中存在严重的体积效应，体积变化率约为300％，会造成电极材料粉化以及电极材料与集流体分离。另外，由于硅负极材料在电池充放电过程中不断地膨胀收缩而持续破裂，产生的新鲜界面暴露于电解液中会形成新的SEI膜，从而持续消耗电解液，降低了电极材料的循环性能。上述缺陷严重限制了单质硅负极的商业化应用。
硅氧化合物由于具有较多的非活性物质，导致其容量低于单质硅负极材料；然而同时，由于这些非活性组分的存在，硅在循环过程中的膨胀被非活性相有效抑制，因此其循环稳定性具有明显优势。相比单质硅而言，硅氧化合物更易实现工业化应用。
然而，硅氧化合物也存在其特定的问题。该材料在首次嵌锂时，颗粒表面由于与电解液发生较多副反应，往往会生成较厚的SEI膜；同时，颗粒内部会生成硅酸锂和氧化锂等无法可逆脱锂的物质，造成电池内锂离子的不可逆损失。上述两类不可逆反应导致含硅氧化合物负极的锂离子电池首次库伦效率较低，从而限制了全电池能量密度的提升。此外，硅氧化合物还存在离子和电子导电率较低、电池循环过程中库伦效率较低等问题。基于上述问题，科研人员进行了以下方面的改进。
具体而言，为了改善硅氧化合物的导电性，以获得高容量和更好的循环保持率，可在硅氧化合物表层包覆碳膜等导电材料。为了提高首次充放电效率，可对硅氧化合物进行预掺杂锂，包括将硅氧化合物与锂金属进行高温混炼，或使用电化学方法对硅氧化合负极进行预充锂，或利用高能机械混合使得硅氧化合物与作为锂化剂的金属锂或有机锂化合物混合的同时原位发生反应，亦或是使含锂化合物与硅氧化合物高温下发生反应，实现对硅氧化合物的预充锂。由于含锂化合物的存在，该类材料往往呈现较强的碱性，导致材料的耐水性较低。因此，在实际电池生产的水系匀浆过程中，若使用含有此类含硅氧锂化合物的负极材料，则浆 料由于材料碱性较高容易发生变性；同时，由于含硅氧锂化合物的耐水性较差，容易与水发生反应，导致浆料涂布时的质量较差和成品率较低。
申请公布号为CN107710466A的中国专利公开了一种硅氧锂化合物负极材料及其制造方法。该硅氧锂化合物表面有一层非晶质的金属氧化物和金属氢氧化物所构成的复合层，提高了该负极材料对于水系匀浆的稳定性。但由于非晶质复合层结构较为疏松，不够致密，因此，基于该材料结构的水系匀浆体系仍然不够稳定。
发明内容
本发明的目的之一是针对现有技术的不足，提供一种用于电池的容量高、库伦效率高、循环寿命长、耐水性强、可采用水系匀浆体系的负极活性材料及其可规模化制备的方法。
具体地，本发明提出了一种用于电池的负极活性材料，其具有负极活性物质颗粒，所述负极活性物质颗粒含有硅氧化合物；
所述负极活性物质颗粒包括锂元素以及非锂掺杂金属，其中，
所述非锂掺杂金属包括金属M1，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种，所述非锂掺杂金属占所述负极活性材料的含量为0.01-20wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
进一步地，所述非锂掺杂金属还包括金属M2，所述金属M2包括铜、镍、铁、锰、钴、铬中的一种或多种。
进一步地，所述金属M1和所述金属M2占所述负极活性材料的含量为0.01-25wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
进一步地，所述金属M2占所述负极活性材料的含量为0.01-25wt％，优选0.01-20wt％，再优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
具体地，所述金属M1以含氧化合物的形式存在于所述负极活性材料中，所述非锂掺杂金属的含氧化合物包括金属氧化物、金属硅酸盐、含锂复合金属硅酸盐(如硅酸镁锂)以及锂与非锂掺杂金属的复合氧化物(如锆酸锂)中的一种或多种。
进一步地，所述金属M1的含氧化合物可以是以分散的方式分布于整个硅氧化合物中。
进一步地，所述金属M1的含氧化合物可以是富集于所述硅氧化合物的表层，含氧化合物的浓度具体地可以由所述表层至所述硅氧化合物的内部递减。
进一步地，所述金属M1的含氧化合物可以部分留在所述硅氧化合物的表面，形成包覆结构，其余部分则扩散进入所述硅氧化合物颗粒内。
进一步地，所述金属M2以单质金属或含硅合金相的形式存在于所述负极活性材料中。
具体地，所述负极活性物质颗粒中的锂含量为0.1-20wt％，优选为2-18wt％，进一步优选为4-15wt％。
具体地，所述负极活性物质颗粒包含有Li 4SiO 4、Li 2SiO 3、Li 6Si 2O 7、Li 8SiO 6及Li 2Si 2O 5中的至少一种含锂化合物。
进一步地，所述负极活性物质颗粒的中值粒径在0.2-20μm之间，优选为1-15μm之间，更优选为2-10μm。
进一步地，所述负极活性物质颗粒还包含有单质硅纳米颗粒，其可以是均匀分散于所述负极活性物质颗粒内，其中，所述单质硅纳米颗粒的中值粒径在0.1-35nm之间，优选为0.5-20nm，更优选为1-15nm。
具体地，所述负极活性物质颗粒中的硅元素含量为30-80wt％，优选为35-65wt％，进一步优选为40-65wt％，因此该材料具有很高的可逆容量。
进一步地，所述负极活性物质颗粒表面还包覆有碳膜层，所述碳膜层覆盖所述硅氧化合物的表面，所述碳膜层厚度在0.001-5μm之间，优选为0.005-2μm之间，进一步优选为0.01-1μm之间。
具体地，所述碳膜层与所述硅氧化合物的重量之比为0.01:100-20:100，优选为0.1:100-15:100，进一步优选为1:100-12:100。
本发明还提出了一种电极，其包括如前任一所述的负极活性材料。
本发明还提出了包括如前任一所述负极活性材料的极片或电池。
本发明还提出了包括如前任一所述的负极活性材料的制备方法，该方法包括：
取硅氧化合物颗粒，将锂元素以及非锂金属元素掺杂至硅氧化合物颗粒；其中，所述硅氧化合物颗粒中硅和氧元素化学计量比为1:0.4-1:2，优选为1:0.6-1:1.5，进一步优选为1:0.8-1:1.2。
具体地，非锂金属元素包括金属M1和金属M2，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种；所述金属M2包括铜、镍、铁、锰、钴、铬中的一种或多种。
进一步地，该方法中，所述金属M1的掺杂源可以为M1的金属单质或化合物，优选为含有金属M1的化合物，进一步优选为含有金属M1的非还原性化合物，更优选为含有金属M1与氧族元素(VIA族)或卤族元素(VIIA族)的化合物，更进一步优选为含有金属M1和氧的化合物，例如含有金属M1的氧化物、含氧无机或有机化合物等；所述金属M2的掺杂源可以为M2的金属单质或化合物，优选为含有金属M2的化合物。
进一步地，所述硅氧化合物颗粒的中值粒径为0.2-20μm之间，优选为1-15μm，进一步优选为2-10μm。非锂掺杂金属元素的掺杂温度可以是400-1100℃，优选为600-1000℃。锂元素的掺杂温度可以是400-900℃，优选为550-850℃。
进一步地，所述硅氧化合物颗粒可以是完全包覆、部分包覆或者不包覆有碳膜层的颗粒。该硅氧化合物可以为未经歧化的硅氧化合物，也可以为经过歧化热处理的硅氧化合物，其中所述歧化热处理温度为600-1100℃，优选为700-1000℃。所述包覆的碳化温度在600-1100℃，优选为700-1000℃。
进一步地，在前述负极活性材料的制备方法中，制备含有非锂金属掺杂的硅氧化合物颗粒可以和锂掺杂改性合并为一步进行，即：将硅氧化合物颗粒和非锂金属掺杂物质及含锂化合物同时混合均匀，随后在非氧化气氛中进行热处理。所述热处理的温度可以为400-900℃，优选为550-850℃，保温时间为0.1-12小时，升温速度大于0.1℃每分钟，小于20℃每分钟。所述非氧化性气氛由至少下述一种气体提供：氮气、氩气、氢气或氦气。
优选地，在前述负极活性材料的制备方法中，在将所述非锂金属元素掺杂入硅氧化合物颗粒、和/或包覆碳膜之后，再掺杂所述锂元素。
进一步地，在包覆碳膜层时，也可以同时对硅氧化合物进行非锂金属元素掺杂。此外，在硅氧化合物表面包覆碳膜层的步骤和对硅氧化合物进行非锂金属掺杂的步骤也可以前后调换。所述金属M1和金属M2的掺杂顺序也可以调换。
本发明与现有技术相比，具有如下优点：
本发明中的负极活性材料具有非锂掺杂金属M1形成的致密含氧化合物结构。所述非锂掺杂金属的致密含氧化合物相可大大提高含锂硅氧化合物的稳定性，有效阻隔颗粒内部与外界水分的接触，避免了水系匀浆过程中材料与水发生反应造成活性成分的损失；同时，所述非锂掺杂金属的致密含氧化合物相可以抑制含锂 硅氧化合物碱性的释放，降低材料的pH值，提高水系浆料的稳定性，因此有效避免了涂布过程中因产气、浆料流变性和稳定性恶化造成的极片针孔、凹坑、面密度不均、粘接差等极片质量问题。
上述非锂掺杂金属的致密含氧化合物相还能将硅氧化合物内部的硅纳米颗粒与外界电解液隔绝，减少其与电解液发生的副反应，同时能形成更加稳定的SEI膜，极大提高材料在电池充放电循环过程中的库伦效率和容量稳定性。
本发明中的负极活性材料中还含有非锂掺杂金属M2的单质金属相或含硅合金相。所述掺杂金属M2的单质金属相或含硅合金相可以有效提高负极活性物质颗粒内部的导电性，同时提高该负极活性材料的结构稳定性，有利于提高该材料的库伦效率和循环稳定性。
本发明中的负极活性材料同时具有非锂掺杂金属M1形成的含氧化合物和非锂掺杂金属M2的单质金属相或含硅合金相，两者之间可以起到协同作用，大大增强材料的稳定性，抑制材料碱性的释放，显著提高材料的耐水性；同时，该协同作用还能极大地提高材料在电池充放电循环过程中的库伦效率和容量稳定性。
含锂硅氧化合物的特性，如高库伦效率、高可逆容量、良好的循环保持率、循环膨胀小等电化学特性，在本发明的材料结构中亦得到完美的保留。而使用该材料所制备的锂离子二次电池，亦具有能量密度高、循环稳定性好、膨胀低等优点。
含锂硅氧化合物颗粒内部的硅纳米晶粒尺寸小，且均匀分散并被固定在硅酸锂系化合物或者硅氧化合物基体内，所述基体可以有效抑制和缓冲硅纳米颗粒的膨胀，并阻止硅颗粒在充放电过程中逐渐融并成更大尺寸的颗粒，防止融并后的大尺寸硅颗粒造成更大的膨胀和部分硅材料的失效。因此使用该材料所制备的锂离子二次电池，具有循环膨胀小、循环稳定性好、能量密度高等优点。
综上，本发明的负极活性材料作为电池负极使用时具有容量高、库伦效率高、循环性能好的电化学特性。所述负极活性材料制备的电池具有能量密度高、循环稳定性好、膨胀低的特性。所述负极活性材料的制备方法简单、成本低、重复性好，所需设备简单，可大规模工业化生产，且该材料耐水性好，能直接应用于工业界普遍采用的水系负极匀浆工艺体系，能够真正实现含硅负极在二次电池领域的规模化应用。
附图说明
图1是实施例1产品扫描电子显微镜图；
图2是实施例1制备的含硅负极全电池的循环性能图；
图3是实施例2产品扫描电子显微镜图；
图4是实施例16产品扫描电子显微镜图；
图5是对比例5硅负极活性材料X射线衍射分析图。
具体实施方式
以下结合实施例，对本发明的具体实施方式进行更加详细的说明，以便能够更好地理解本发明的方案以及其各个方面的优点。然而，以下描述的具体实施方式和实施例仅是说明的目的，而不是对本发明的限制。
本发明的目的之一是针对现有技术的不足，提供一种用于电池的容量高、库伦效率高、循环寿命长、耐水性强、可采用水系匀浆体系的负极活性材料及其可规模化制备的方法。
具体地，本发明提出了一种用于电池的负极活性材料，其具有负极活性物质 颗粒，所述负极活性物质颗粒含有硅氧化合物，
所述负极活性物质颗粒包括锂元素以及非锂掺杂金属，其中，
所述非锂掺杂金属包括金属M1，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种，所述非锂掺杂金属占所述负极活性材料的含量为0.01-20wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。保证非锂掺杂金属在合适的范围内，可避免掺杂金属对所述负极活性材料的容量产生负面影响，同时对所述含锂硅氧化合物起到足够的稳定和保护作用，使得混合本发明的负极活性材料而成的水系浆料更加稳定。
进一步地，所述非锂掺杂金属还包括金属M2，所述金属M2包括铜、镍、铁、锰、钴、铬中的一种或多种。
进一步地，所述金属M1和所述金属M2占所述负极活性材料的含量为0.01-25wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
进一步地，所述金属M2占所述负极活性材料的含量为0.01-25wt％，优选0.01-20wt％，再优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
进一步地，所述金属M1可主要以含氧化合物的形式存在于所述负极活性材料中，所述含氧化合物包括金属氧化物、金属硅酸盐、含锂复合金属硅酸盐(如硅酸镁锂)以及锂与非锂掺杂金属的复合氧化物(如锆酸锂)中的一种或多种。所述掺杂金属M1的含氧化合物均匀分散或局部富集于负极活性物质颗粒中，并形成致密的保护结构。由于非锂金属M1的含氧化合物不溶于水，其致密结构可大大提高含锂硅氧化合物的稳定性，有效阻隔颗粒内部与外界水分或电解液的接触，避免了水系匀浆过程中材料与水发生反应造成活性成分的损失，同时减少电解液与硅化合物的副反应，有利于提高负极活性材料的首次库伦效率。
此外，所述非锂掺杂金属M1的致密含氧化合物相还可以抑制含锂硅氧化合物碱性的释放，降低材料的pH值，提高水系浆料的稳定性，因此有效避免了涂布过程中因产气、浆料流变性和稳定性恶化造成的极片针孔、凹坑、面密度不均、粘接差等极片质量问题。
进一步地，所述金属M1的含氧化合物可以是以分散的方式分布于整个硅氧化合物中，形成致密的保护结构。
进一步地，所述金属M1的含氧化合物可以是富集于所述硅氧化合物的表层，形成致密的保护壳层，含氧化合物的浓度具体地可以由所述表层至所述硅氧化合物的内部递减。
上述负极活性物质颗粒中，非锂掺杂金属M1的含氧化合物可以部分留在所述硅氧化合物的表面，形成包覆结构，其余部分则扩散进入所述硅氧化合物颗粒内。
进一步地，所述金属M2以单质金属或含硅合金相的形式存在于所述负极活性材料中。
所述非锂掺杂金属M2均匀分散或局部富集于负极活性物质颗粒中，可主要形成掺杂金属M2的单质金属相或含硅合金相。所述掺杂金属M2的单质金属相或含硅合金相有效提高了负极活性物质颗粒的内部导电性，同时提高了该材料的结构稳定性，有利于该负极活性材料的库伦效率和循环稳定性的提升。
具体地，所述非锂掺杂金属M1形成的含氧化合物和所述非锂掺杂金属M2的单质金属相或含硅合金相之间，可以起到协同作用，起到”1+1>2”的效果，大大增强材料的稳定性，抑制材料碱性的释放，显著提高材料的耐水性；同时，该协同作用还能极大地提高材料在电池充放电循环过程中的库伦效率和容量稳定性。
具体地，所述负极活性物质颗粒中的锂含量为0.1-20wt％，优选为2-18wt％，进一步优选为4-15wt％。
具体地，所述负极活性物质颗粒包含有Li 4SiO 4、Li 2SiO 3、Li 6Si 2O 7、Li 8SiO 6及Li 2Si 2O 5中的至少一种含锂化合物。通过向所述硅氧化合物预嵌入锂离子，其与传统的硅氧化合物负极材料相比，含锂硅氧化合物的首次库伦效率和循环保持率得到明显的提高。
进一步地，所述负极活性物质颗粒的中值粒径在0.2-20μm之间，优选为1-15μm之间，进一步优选为2-10μm。
进一步地，所述负极活性物质颗粒还包含有单质硅纳米颗粒，其可以是均匀分散于所述负极活性物质颗粒内，其中，所述单质硅纳米颗粒的中值粒径在0.1-35nm之间，优选为0.5-20nm，进一步优选为1-15nm。该颗粒在经历锂离子嵌入脱出的循环时，颗粒发生的膨胀较小且不易破裂，使得使用该材料的锂离子二次电池的循环膨胀小且循环稳定。
具体地，所述负极活性物质颗粒中的硅元素含量为30-80wt％，优选为35-65wt％，进一步优选为40-65wt％，因此该材料具有很高的可逆容量。
进一步地，所述负极活性物质颗粒表面还包覆有碳膜层，所述碳膜层覆盖所述硅氧化合物的表面，所述碳膜层厚度在0.001-5μm之间，优选为0.005-2μm之间，进一步优选为0.01-1μm之间。其中，所述包覆是指碳膜层完全覆盖或部分覆盖在颗粒表面。碳膜层的存在可以有效提高颗粒的电导率，降低负极极片中颗粒之间、负极极片和集流体的接触电阻，从而提高材料的脱嵌锂效率，降低锂离子电池的极化并促进其循环稳定性。
具体地，所述碳膜层与所述硅氧化合物的重量之比为0.01:100-20:100，优选为0.1:100-15:100，进一步优选为1:100-12:100。
本发明还提出了一种电极，其包括如前任一所述的负极活性材料。
本发明还提出了包括如前任一所述负极活性材料的极片或电池。
本发明还提出了包括如前任一所述的负极活性材料的制备方法，该方法包括：
取硅氧化合物颗粒，将锂元素以及非锂金属元素掺杂至硅氧化合物颗粒；其中，所述硅氧化合物颗粒中硅和氧元素化学计量比为1:0.4-1:2，优选为1:0.6-1:1.5，进一步优选为1:0.8-1:1.2。
具体地，非锂金属元素包括金属M1和金属M2，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种；所述金属M2包括铜、镍、铁、锰、钴、铬中的一种或多种。
进一步地，所述硅氧化合物颗粒的中值粒径为0.2-20μm之间，优选为1-15μm，更优选为2-10μm。非锂金属元素的掺杂温度分别可以是400-1100℃，优选为600-1000℃。锂元素的掺杂温度可以是400-900℃，优选为550-850℃。
进一步地，所述硅氧化合物颗粒可以是完全包覆、部分包覆或者不包覆有碳膜层的颗粒。该硅氧化合物可以为未经歧化的硅氧化合物，也可以为经过歧化热处理的硅氧化合物，其中所述歧化热处理温度为600-1100℃，优选为700-1000℃。所述包覆的碳化温度在600-1100℃，优选为700-1000℃。
进一步地，在前述负极活性材料的制备方法中，制备含有非锂金属掺杂的硅氧化合物颗粒可以和锂掺杂改性合并为一步进行，即：将硅氧化合物颗粒和非锂金属掺杂物质及含锂化合物同时混合均匀，随后在非氧化气氛中进行热处理。所述热处理的温度可以为400-900℃，优选为550-850℃，保温时间为0.1-12小时，升温速度大于0.1℃每分钟，小于20℃每分钟。所述非氧化性气氛由至少下述一种气体提供：氮气、氩气、氢气或氦气。
优选地，在前述负极活性材料的制备方法中，在将所述非锂金属元素掺杂入硅氧化合物颗粒、和/或包覆碳膜之后，再掺杂所述锂元素。锂元素掺杂的步骤在 非锂元素掺杂之后进行，可以抑制热处理过程中硅氧化合物内硅晶粒的长大。由此，纳米级的单质硅颗粒均匀分散并被固定在硅酸锂化合物或者硅氧化合物基体内，可以有效抑制硅纳米颗粒的膨胀，并阻止硅颗粒在充放电过程中逐渐融并成更大尺寸的颗粒，从而降低电池在循环过程中的膨胀变形和减少硅材料的电学失效，使得使用该材料的锂离子二次电池的循环膨胀小且循环稳定。进一步地，在包覆碳膜层时，也可以同时对硅氧化合物进行非锂金属元素掺杂。此外，在硅氧化合物表面包覆碳膜层的步骤和对硅氧化合物进行非锂金属掺杂的步骤也可以前后调换。所述金属M1和金属M2金属的掺杂顺序也可以调换。
锂元素掺杂的步骤在包覆碳膜层和非锂元素掺杂之后进行，可以抑制热处理过程中硅氧化合物内硅晶粒的长大。由此，纳米级的单质硅颗粒均匀分散并被固定在硅酸锂化合物或者硅氧化合物基体内，可以有效抑制硅纳米颗粒的膨胀，并阻止硅颗粒在充放电过程中逐渐融并成更大尺寸的颗粒，从而降低电池在循环过程中的膨胀变形和减少硅材料的电学失效，使得使用该材料的锂离子二次电池的循环膨胀小且循环稳定。此外，包覆碳膜层的步骤在锂元素掺杂之前进行，有利于得到质量更好、包覆更完整的碳膜层。
上述硅氧化合物颗粒表面包覆的碳膜层可通过下述方式实现：
所述碳膜层可通过化学气相沉积(CVD)的方式直接得到，CVD所采用的碳源为碳氢化合物气体，所述碳氢化合物气体的分解温度可以为600-1100℃，优选为750-950℃。所述碳膜层也可以通过先进行碳反应包覆再在非氧化气氛中进行热处理碳化的方式得到。所述碳反应包覆方法可以采用机械融合机、VC混合机、包覆釜、喷雾干燥、砂磨机或高速分散机中的任意一种，包覆时选用的溶剂是水、甲醇、乙醇、异丙醇、正丁醇、乙二醇、乙醚、丙酮、N-甲基吡咯烷酮、甲基丁酮、四氢呋喃、苯、甲苯、二甲苯、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺、三氯甲烷中的一种或多种的组合。所述碳反应源可以是煤沥青、石油沥青、聚乙烯醇、环氧树脂、聚丙烯腈、聚甲基丙烯酸甲酯、葡萄糖、蔗糖、聚丙烯酸、聚乙烯吡咯烷酮中的一种或多种的组合。所述热处理碳化所用设备可以为回转炉、钢包炉、辊道窑、推板窑、气氛箱式炉或管式炉中的任意一种。所述热处理碳化的温度可以为600-1100℃，优选为700-1000℃，保温时间为0.5-24小时。所述非氧化气氛可以由下述至少一种气体提供：氮气、氩气、氢气或氦气。
具体地，所述非锂金属元素的掺杂可以是硅氧化合物颗粒同非锂金属掺杂物质进行均匀混合后在非氧化气氛中进行热处理掺杂，其中所述掺杂物质包括含有掺杂元素的单质或化合物粉末，优选为含有掺杂元素的化合物。例如可以是：金属氧化物，金属盐(包括硝酸盐、亚硝酸盐、硫酸盐、亚硫酸盐、硫酸氢盐、磷酸氢盐、磷酸二氢盐、卤素盐等无机金属盐，以及乙酸盐、草酸盐、柠檬酸盐等有机金属盐)等。
具体地，上述混合方法可以采用高速分散机、喷雾干燥、高速搅拌磨、球磨机、锥形混合机，螺旋混合机，搅拌式混合机或VC混合机中的任意一种。上述热处理掺杂所用设备包括回转炉、钢包炉、辊道窑、推板窑、气氛箱式炉或管式炉中的任意一种。上述热处理掺杂的温度可以是400-1100℃，优选为600-1000℃，保温时间为0.1-12小时，优选为1-4h，升温速度大于1℃每分钟，小于100℃每分钟。上述非氧化性气氛由至少下述一种气体提供：氮气、氩气、氢气或氦气。
具体地，锂掺杂改性方法包括电化学方法、液相掺杂法、热掺杂法、高温混炼法、高能机械法等。其中，优选电化学方法、液相掺杂法和热掺杂法。
使用电化学方法进行锂掺杂改性时，需要提供一个电化学池，其中包含浴槽、阳极电极、阴极电极和电源四个部件，而阳极电极和阴极电极分别连接电源的两 端。同时，阳极电极接通锂源，而阴极电极接通包含有硅氧化合物颗粒的容器。在浴槽中填充满有机溶剂，使锂源(阳极电极)和包含有硅氧化合物颗粒的容器(阴极电极)浸没于有机溶剂中。接通电源后，由于电化学反应的发生，锂离子嵌入硅氧化合物结构中，得到锂掺杂改性的硅氧化合物颗粒。上述有机溶剂可采用碳酸乙烯酯、碳酸丙烯酯、碳酸丁烯酯、氟代碳酸乙烯酯、碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯、乙酸乙酯、乙酸丙酯、丙酸乙酯、丙酸丙酯、二甲基亚砜等溶剂。另外，该有机溶剂中还含有电解质锂盐，可采用六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、高氯酸锂(LiClO4)等。上述锂源(阳极电极)可采用锂箔，或锂化合物，如碳酸锂、氧化锂、氢氧化锂、钴酸锂、磷酸铁锂、锰酸锂、磷酸钒锂、镍酸锂等。
另外，还可采用液相掺杂法对硅氧化合物进行锂掺杂改性。具体实施时，将金属锂、电子转移催化剂、硅氧化合物颗粒加入醚基溶剂中，在非氧化气氛中持续搅拌并加热保持恒温反应，直至溶液中的金属锂完全消失。在电子转移催化剂的作用下，金属锂可以溶解于醚基溶剂中，并形成锂离子的配位化合物，具有较低的还原电势，因此可与硅氧化合物发生反应，锂离子进入硅氧化合物结构中。所述电子转移催化剂包括联苯、萘等。所述醚基溶剂包括甲基丁基醚、乙二醇丁醚、四氢呋喃、乙二醇二甲醚等。所述恒温反应温度为25-200℃。所述非氧化性气氛由下述至少一种气体提供：氮气、氩气、氢气或氦气。
另外，还可采用热掺杂法对硅氧化合物进行锂掺杂改性。具体实施时，将硅氧化合物颗粒与含锂化合物均匀混合，然后在非氧化气氛中进行热处理。所述含锂化合物包括氢氧化锂、碳酸锂、氧化锂、过氧化锂、氢化锂、硝酸锂、醋酸锂、草酸锂等。所述混合方法采用高速分散机、高速搅拌磨、球磨机、锥形混合机，螺旋混合机，搅拌式混合机或VC混合机中的任意一种。所述热处理所用设备为回转炉、钢包炉、内胆炉、辊道窑、推板窑、气氛箱式炉或管式炉中的任意一种。所述热处理的温度为400-900℃，优选为550-850℃，保温时间为0.1-12小时，升温速度大于0.1℃每分钟，小于20℃每分钟。所述非氧化性气氛由下述至少一种气体提供：氮气、氩气、氢气或氦气。
实施例1
将1000g中值粒径为4μm的硅氧化合物颗粒(硅氧原子比为1:1)、213.3g钛酸四丁酯和25克聚乙烯吡咯烷酮(PVP)在3000g去离子水中高速分散后，将浆料进行喷雾干燥处理。随后将得到的粉末在氮气氛围下，850℃加热3小时后进行气流破碎，根据扫描电子显微镜和X射线能谱分析(EDS)的结果证明，得到掺杂有钛元素的部分包覆有碳膜层的硅氧化合物粉末。颗粒表面有很少量的含钛化合物的残留，形成点状包覆结构，而绝大部分的钛则掺杂到硅氧化合物颗粒内部(如图1)。同时X射线能谱分析的结果表明钛元素在硅氧化合物颗粒上的分布基本均匀。
在相对湿度低于30％的干燥间内，将500克上述步骤得到的粉末、45克金属锂带、10克联苯加入一个可密封玻璃容器中，然后加入1000克甲基丁基醚和一个大号搅拌磁子。此时，将容器内充入氩气后密封，并将容器放置在磁力搅拌器上进行搅拌，转速设置为200r/min。70℃恒温反应5小时后，将容器内的甲基丁基醚蒸发或过滤去除后，烘干，随后将得到的粉末放置于管式炉中，在氩气氛围下进行热处理，以10℃/min的升温速率升温至550℃后保持3小时，自然冷却后可得到锂掺杂的硅氧化合物粉末。
将上述硅氧化合物颗粒与去离子水混合，使用奥豪斯仪器(上海)有限公司的精密pH测试仪，可测得该分散液的pH值为10.7。
此外，基于X射线衍射法得到的硅(111)晶面的衍射峰半高宽及Scherrer公式，可以得到上述硅氧化合物的硅(111)晶面对应的微晶尺寸是1.2nm。
取上述硅氧化合物材料12份，人造石墨83份，导电添加剂2.5份，粘结剂2.5份，在水性体系下匀浆，取部分水系匀浆浆料做耐水性和稳定性测试，其他浆料用于涂布，然后烘干、碾压，得到含硅负极极片。
含有上述硅氧化合物材料的水系浆料稳定性评估：取30g上述水系匀浆浆料保存于65℃环境中，并确认上述浆料在此条件下何时开始产气。在此苛刻条件下，上述浆料可坚持一周以上不产气。在常规水系匀浆过程中，浆料温度一般维持在25-30℃。因此，本专利所采用的浆料稳定性的评测方法，严苛程度已远超越实际水系匀浆涂布生产过程的条件。在本评测方法下，若浆料可坚持24小时不产气，则可认为该浆料中的硅氧化合物材料耐水性强，稳定性好，可用于大规模的水系匀浆。
半电池评估：将上述含硅负极极片与隔膜、锂片、不锈钢垫片依次叠放并滴加200μL电解液后封口制成2016式锂离子半电池。用武汉市蓝电电子股份有限公司的小(微)电流量程设备测试容量及放电效率。测得含硅负极的半电池的首圈嵌锂比容量为550.7mAh/g，首次充放电效率(脱锂截止电位0.8V)为88％。
全电池评估：上述含硅负极极片经过分切、真空烘烤、与配对的正极片和隔膜一起进行卷绕并装进相应大小的铝塑壳中后，注入一定量电解液并除气封口，化成后即得到一个约3.2Ah的含硅负极锂离子全电池。用深圳市新威尔电子有限公司的电池测试仪测试该全电池在0.2C下的容量、平均电压，并在0.7C倍率下充放电循环500次的得到容量保持率数据。由此得到全电池的体积能量密度为771.5Wh/L，500次充放电循环后的容量保持率为85.4％。图2是实施例1制备的含硅负极全电池的循环性能图。上述全电池在经过500圈循环充放电后相对于初始分容后的电池膨胀率为11％。
实施例2
相比实施例1，实施例2中对硅氧化合物颗粒采用化学气相沉积法包覆碳膜层，以乙炔为碳源，在900℃下进行3小时包覆反应，得到包覆有完整碳膜层的硅氧化合物颗粒。随后，通过干法包覆的方式将11.4g纳米氧化铝均匀包覆在1000g上述颗粒表面，并在氮气气氛下，进行800℃保温3小时，得到掺杂有铝元素的包覆完整碳膜层的硅氧化合物。扫描电镜的结果显示，颗粒表面没有含铝化合物残留，说明铝已全部掺杂到硅氧化合物内(图3)。接着，采用与实施例1相同的工艺对上述硅氧化合物掺杂锂金属，得到掺杂有铝元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.9，硅(111)晶面对应的微晶尺寸是2.3nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为546.6mAh/g，首次充放电效率88.5％。测得全电池的体积能量密度达到774.2Wh/L，500次充放电循环后的容量保持率为88.7％，500圈后的电池膨胀率为10.5％。
实施例3
相比实施例1，实施例3中采用干法包覆的方式将49.8g纳米氧化锌均匀包覆在1000g硅氧化合物颗粒表面，并在氮气气氛下，进行1000℃保温1小时，得到掺杂有锌元素的无碳膜的硅氧化合物粉末。扫描电镜的结果显示，颗粒表面没有含锌化合物残留，说明锌已全部掺杂到硅氧化合物内。同时X射线能谱分析的结果显示，颗粒表面的锌含量高达4.1％，和该硅氧化合物内实际掺杂的锌元素含量接近，说明锌元素没有在颗粒表层富集。随后采用电化学预锂的方法对上述硅氧化合物进行锂金属掺杂，得到掺杂有锌元素的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.1，硅(111)晶面对应的微晶尺寸是3.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为542.3mAh/g，首次充放电效率87.6％。测得全电池的体积能量密度达到764.3Wh/L，500次充放电循环后的容量保持率为84％，500圈后的 电池膨胀率为11.3％。
实施例4
相比实施例3，实施例4采用相同的掺杂锌元素的方法和热处理工艺，但将纳米氧化锌的包覆量降至12.5g，得到掺杂有锌元素的硅氧化合物颗粒。随后采用化学气相沉积的方式在上述颗粒表面包覆碳膜层，以乙炔为碳源，在1000℃下进行3小时包覆反应，得到包覆有完整碳膜层的掺有锌元素的硅氧化合物颗粒。接下来采用的锂金属掺杂工艺与实施例3相同，得到掺杂有锌元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.4，硅(111)晶面对应的微晶尺寸是3.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为543mAh/g，首次充放电效率88％。测得全电池的体积能量密度达到768.1Wh/L，500次充放电循环后的容量保持率为87.1％，500圈后的电池膨胀率为10.3％。
实施例5
相比实施例1，实施例5中对硅氧化合物颗粒采用液相包覆的方式包覆碳前驱体。将1000g硅氧化合物颗粒和50g低温煤沥青粉末在包覆釜内干法混合均匀后，边搅拌边加入2000g二甲基甲酰胺，将混合粉末在二甲基甲酰胺中分散均匀。随后加热包覆釜至140℃并保持恒温搅拌3小时，最终再加热至160℃并恒温直至将二甲基甲酰胺蒸干，得到煤沥青包覆的硅氧化合物材料。将上述材料在氮气氛围下加热至950℃并保持3小时使煤沥青碳化。将冷却后得到的材料过500目筛网，得到碳膜包覆的硅氧化合物粉末。随后采用与实施例1相同的喷雾干燥工艺，但将掺杂源(钛酸四丁酯)替换为22g四水合醋酸镁，并将喷雾干燥得到的粉末改用750℃加热3小时的热处理工艺，得到掺杂有镁元素的包覆碳膜的硅氧化合物颗粒。扫描电镜的结果显示，颗粒表面没有含镁化合物残留，说明镁已全部掺杂到硅氧化合物内。同时X射线能谱分析的结果显示，颗粒表面的镁含量高达1％，远远高于该硅氧化合物内实际掺杂的镁元素含量，说明镁元素在颗粒表层富集。接下来采用热掺杂法进行锂金属掺杂，具体而言：取500克上述颗粒混合28.5克氢化锂，将混合粉末放置于管式炉中，在氩气氛围下进行热处理，以10℃/min的升温速率升温至550℃后保持6小时，自然冷却后将材料从管式炉中取出并过500目筛网，得到掺杂有镁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.3，硅(111)晶面对应的微晶尺寸是2.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为560.7mAh/g，首次充放电效率86.1％。测得全电池的体积能量密度达到758.8Wh/L，500次充放电循环后的容量保持率为89％，500圈后的电池膨胀率为9.7％。
实施例6
相比实施例5，实施例6中采用相似的包覆碳膜层的工艺，仅将热处理工艺调整为1000℃保温2.5小时，并采用与实施例5相同的喷雾干燥工艺，但将掺杂源替换为13.9g九水合硝酸铝，并将喷雾干燥得到的粉末改用600℃加热2小时的热处理工艺，得到掺杂有铝元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为51.3g，并将热处理工艺调整为575℃保温6小时，得到掺杂有铝元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.9，硅(111)晶面对应的微晶尺寸是3.1nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持72小时不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为536.9mAh/g，首次充放电效率89.1％。测得全电池的体积能量密度达到778.2Wh/L，500次充放电循环后的容量保持率为87.2％，500圈后的电池膨胀率为10.8％。
实施例7
相比实施例5，实施例7中改用中值粒径为1μm的硅氧化合物颗粒，并采用相似的包覆碳膜层的工艺，仅将热处理工艺调整为700℃保温6小时，并采用与实施例5相同的喷雾干燥工艺，但将四水合醋酸镁的添加量调整为220g，并将喷雾干燥得到的粉末改用700℃加热6小时的热处理工艺，得到掺杂有镁元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为74.1g，并将热处理工艺调整为650℃保温5小时，得到掺杂有镁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.9，硅(111)晶面对应的微晶尺寸是4.1nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为524.2mAh/g，首次充放电效率89.8％。测得全电池的体积能量密度达到777.2Wh/L，500次充放电循环后的容量保持率为83.1％，500圈后的电池膨胀率为10.8％。
实施例8
相比实施例5，实施例8中改用中值粒径为9μm的硅氧化合物颗粒，并采用相同的包覆碳膜层和喷雾干燥工艺，但将掺杂源改为71.1g钛酸四丁酯和44g四水合醋酸镁，并将喷雾干燥得到的粉末改用900℃加热3小时的热处理工艺，得到掺杂有钛和镁元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为45.6g，并将热处理工艺调整为700℃保温5小时，得到掺杂有钛和镁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10，硅(111)晶面对应的微晶尺寸是3.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为528mAh/g，首次充放电效率90.9％。测得全电池的体积能量密度达到787.1Wh/L，500次充放电循环后的容量保持率为86.4％，500圈后的电池膨胀率为11.9％。
实施例9
相比实施例8，实施例9中改用中值粒径为15μm的硅氧化合物颗粒，并采用相同的包覆碳膜层的工艺，得到包覆有碳膜层的硅氧化合物粉末。随后采用干法包覆的方式将27g纳米氧化锆均匀包覆在上述颗粒表面，并在氮气气氛下，进行1000℃保温2小时，得到掺杂有锆元素的包覆碳膜的硅氧化合物粉末。接下来采用相同的锂金属掺杂工艺，得到掺杂有锆元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.9，硅(111)晶面对应的微晶尺寸是3.8nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为527mAh/g，首次充放电效率91.1％。测得全电池的体积能量密度达到788.4Wh/L，500次充放电循环后的容量保持率为82.1％，500圈后的电池膨胀率为12.5％。
实施例10
相比实施例6，实施例10中采用相似的包覆碳膜层的工艺，仅将沥青添加量调整为70g，并采用与实施例6相同的喷雾干燥工艺，但将掺杂源替换为11.4g六水合硝酸锌和34.7g九水合硝酸铝，并将喷雾干燥得到的粉末改用700℃加热3小时的热处理工艺，得到掺杂有锌和铝元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为57g，并将热处理工艺调整为600℃保温6小时，得到掺杂有锌和铝元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.7，硅(111)晶面对应的微晶尺寸是3.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为530.4mAh/g，首次充放电效率89.9％。测得全电池 的体积能量密度达到781.9Wh/L，500次充放电循环后的容量保持率为86.8％，500圈后的电池膨胀率为11.1％。
实施例11
相比实施例10，实施例11中采用相似的包覆碳膜层的工艺，仅将沥青添加量调整为100g，并采用与实施例10相同的喷雾干燥工艺，但将掺杂源替换为208.4g九水合硝酸铝，并将喷雾干燥得到的粉末改用900℃加热2小时的热处理工艺，得到掺杂有铝元素的包覆碳膜的硅氧化合物颗粒。接下来采用相似的热掺杂法进行锂金属掺杂，将热处理工艺调整为700℃保温6小时，得到掺杂有铝元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.2，硅(111)晶面对应的微晶尺寸是4.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为521.3mAh/g，首次充放电效率91.4％。测得全电池的体积能量密度达到793.5Wh/L，500次充放电循环后的容量保持率为86.1％，500圈后的电池膨胀率为11.9％。
实施例12
相比实施例6，实施例12中采用相同的包覆碳膜层和喷雾干燥的工艺，但将掺杂源替换为353g四水合醋酸镁和182g六水合硝酸锌，并将喷雾干燥得到的粉末改用1000℃加热3小时的热处理工艺，得到掺杂有镁和锌元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为34.3g，并将热处理工艺调整为850℃保温2小时，得到掺杂有镁和锌元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为8.7，硅(111)晶面对应的微晶尺寸是10.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为486mAh/g，首次充放电效率92％。测得全电池的体积能量密度达到765.3Wh/L，500次充放电循环后的容量保持率为82.1％，500圈后的电池膨胀率为13.5％。
实施例13
相比实施例12，实施例13中采用相同的包覆碳膜层、喷雾干燥掺杂及锂金属掺杂工艺，仅将掺杂源替换为706g四水合醋酸镁和364g六水合硝酸锌，得到掺杂有镁和锌元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为8.5，硅(111)晶面对应的微晶尺寸是16nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为452mAh/g，首次充放电效率92％。测得全电池的体积能量密度达到739.3Wh/L，500次充放电循环后的容量保持率为80.5％，500圈后的电池膨胀率为15％。
实施例14
相比实施例5，实施例14中采用相同的包覆碳膜层、喷雾干燥掺杂及锂金属掺杂工艺，仅将掺杂源替换为4.4g四水合醋酸镁，得到掺杂有镁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.5，硅(111)晶面对应的微晶尺寸是2.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持24小时不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为562mAh/g，首次充放电效率86.1％。测得全电池的体积能量密度达到758.8Wh/L，500次充放电循环后的容量保持率为89％，500圈后的电池膨胀率为9.7％。
实施例15
取1000克中值粒径为4μm的硅氧化合物颗粒(硅氧比为1:1)混合100克氢化锂，采用热掺杂法进行锂金属掺杂，热处理工艺为800℃保温2小时，得到含锂硅氧化合物。 随后取500g上述颗粒混合25g金属镁粉，在氩气气氛下进行850℃保温1.5小时，得到掺杂有镁元素的含锂硅氧化合物颗粒。最后通过化学气相沉积法在上述颗粒表面包覆碳膜层，以乙炔为碳源，在850℃下进行1小时包覆反应，得到包覆碳膜的掺杂有镁元素的含锂硅氧化合物颗粒。
所得的硅负极活性材料的pH为9.5，硅(111)晶面对应的微晶尺寸是26nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为462.6mAh/g，首次充放电效率92.6％。测得全电池的体积能量密度达到730.8Wh/L，500次充放电循环后的容量保持率为76.1％，500圈后的电池膨胀率为17.8％。
实施例16
将1000g中值粒径为5μm的硅氧化合物颗粒(硅氧原子比为1:1)、10g纳米氧化锆和70g低温煤沥青粉末在包覆釜内干法混合均匀后，边搅拌边加入2000g二甲基甲酰胺，将混合粉末在二甲基甲酰胺中分散均匀。随后加热包覆釜至140℃并保持恒温搅拌3小时，最终再加热至160℃并恒温直至将二甲基甲酰胺蒸干，得到煤沥青包覆的硅氧化合物材料。将上述材料在氮气氛围下加热至900℃并保持4小时使煤沥青碳化。将冷却后得到的材料过500目筛网，根据扫描电子显微镜和X射线能谱分析(EDS)的结果证明，得到碳膜包覆完整且均匀掺杂有锆元素的硅氧化合物粉末，颗粒表面没有含锆化合物的残留，说明锆已掺杂到硅氧化合物内。同时，X射线能谱分析(EDS)的结果显示，颗粒表面的锆含量高达2.5wt％，明显高于该硅氧化合物内实际掺杂的锆含量，说明锆元素在颗粒表层富集。
将1000g上述步骤得到的粉末、15.7g一水合醋酸铜和25g聚乙烯吡咯烷酮(PVP)在3000g去离子水中高速分散后，将浆料进行喷雾干燥处理。随后将得到的粉末在氮气氛围下，800℃加热3小时后进行气流破碎，根据扫描电子显微镜和X射线能谱分析(EDS)的结果，得到掺杂有铜元素和锆元素的硅氧化合物(如图4)。
在相对湿度低于30％的干燥间内，将500克上述步骤得到的粉末、45克金属锂带、10克联苯加入一个可密封玻璃容器中，然后加入1000克甲基丁基醚和一个大号搅拌磁子。此时，将容器内充入氩气后密封，并将容器放置在磁力搅拌器上进行搅拌，转速设置为200r/min。70℃恒温反应5小时后，将容器内的甲基丁基醚蒸发或过滤去除后，烘干，随后将得到的粉末放置于管式炉中，在氩气氛围下进行热处理，以10℃/min的升温速率升温至550℃后保持3小时，自然冷却后可得到锂掺杂的硅氧化合物粉末。
将上述硅氧化合物颗粒与去离子水混合，使用奥豪斯仪器(上海)有限公司的精密pH测试仪，可测得该分散液的pH值为10.9。
使用粉末电阻仪测试上述含锂硅氧化合物颗粒的电阻率，可测得该粉末材料在20MPa的压力下的电阻率值为24Ω*cm。
此外，基于X射线衍射的结果可知，该硅氧化合物中同时具有少量的硅酸锆相和铜硅合金相。同时，基于X射线衍射法得到的硅(111)晶面的衍射峰半高宽及Scherrer公式，可以得到上述硅氧化合物的硅(111)晶面对应的微晶尺寸是2.3nm。
取上述硅氧化合物材料12份，人造石墨83份，导电添加剂2.5份，粘结剂2.5份，在水性体系下匀浆，取部分水系匀浆浆料做耐水性和稳定性测试，其他浆料用于涂布，然后烘干、碾压，得到含硅负极极片。
含有上述硅氧化合物材料的水系浆料稳定性评估：取30g上述水系匀浆浆料保存于65℃，并确认上述浆料在此条件下何时开始产气。在此苛刻条件下，上述浆料可坚持一周以上不产气。在常规水系匀浆过程中，浆料温度一般维持在25-30℃。因此，本专利所采用的浆料稳定性的评测方法，严苛程度已远超越实际水系匀浆涂布生产过程的条件。在本评测方法下，若浆料可坚持24小时不产气，则可认为该浆料中的硅氧化合物 材料耐水性强，稳定性好，可用于大规模的水系匀浆。
半电池评估：将上述含硅负极极片与隔膜、锂片、不锈钢垫片依次叠放并滴加200μL电解液后封口制成2016式锂离子半电池。用武汉市蓝电电子股份有限公司的小(微)电流量程设备测试容量及放电效率。测得含硅负极的半电池的首圈嵌锂比容量为546mAh/g，首次充放电效率(脱锂截止电位0.8V)为88.4％。
全电池评估：上述含硅负极极片经过分切、真空烘烤、与配对的正极片和隔膜一起进行卷绕并装进相应大小的铝塑壳中后，注入一定量电解液并除气封口，化成后即得到一个约3.2Ah的含硅负极锂离子全电池。用深圳市新威尔电子有限公司的电池测试仪测试该全电池在0.2C下的容量、平均电压，并在0.7C倍率下充放电循环500次的得到容量保持率数据。由此得到全电池的体积能量密度为773Wh/L，500次充放电循环后的容量保持率为88％。上述全电池在经过500圈循环充放电后相对于初始分容后的电池膨胀率为10.5％。
实施例17
相比实施例16，实施例17的硅氧化合物没有包覆碳膜层，直接通过干法包覆的方式将20g纳米氧化锌和25.5g纳米氧化镍均匀包覆在1000g硅氧化合物颗粒表面，并在氮气气氛下，进行950℃保温3小时，得到掺杂有锌元素和镍元素的硅氧化合物。接着，采用电化学预锂的方式对上述硅氧化合物掺杂锂金属，得到掺杂有锌元素和镍元素的含锂硅氧化合物。
所得的硅负极活性材料中分别有硅酸锌相和镍硅合金相，该材料的pH为10.2，硅(111)晶面对应的微晶尺寸是2.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为542.3mAh/g，首次充放电效率87.6％。测得全电池的体积能量密度达到764.3Wh/L，500次充放电循环后的容量保持率为84％，500圈后的电池膨胀率为11.3％。
实施例18
相比实施例16，实施例18中将沥青含量降至50g，并将包覆碳膜层的热处理工艺调整为1000℃保温2小时，得到包覆碳膜层的硅氧化合物颗粒。随后采用干法包覆的方式将1.9g纳米氧化铝和1.3g纳米氧化锰均匀包覆在1000g上述颗粒表面，并在氮气气氛下，进行700℃保温3小时，得到掺杂有铝元素和锰元素的包覆碳膜的硅氧化合物。接下来采用热掺杂法进行锂金属掺杂，具体而言：取500克上述颗粒混合57克氢化锂，将混合粉末放置于管式炉中，在氩气氛围下进行热处理，以10℃/min的升温速率升温至600℃后保持6小时，自然冷却后将材料从管式炉中取出并过500目筛网，得到掺杂有铝和锰元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.8，硅(111)晶面对应的微晶尺寸是3.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为534mAh/g，首次充放电效率89.9％。测得全电池的体积能量密度达到781Wh/L，500次充放电循环后的容量保持率为86.8％，500圈后的电池膨胀率为11.1％。
实施例19
相比实施例16，实施例19中改用中值粒径为1μm的硅氧化合物颗粒，采用与实施例1相似的包覆碳膜的工艺，将沥青含量降至50g，并将包覆碳膜层的热处理工艺调整为950℃保温3小时，得到包覆碳膜层的硅氧化合物颗粒。随后采用与实施例1相似的喷雾干燥工艺，但将掺杂源替换为284.4g钛酸四丁酯和289.4g九水合硝酸铁，并将喷雾干燥得到的粉末改用800℃加热6小时的热处理工艺，得到掺杂有钛和铁元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，具体而言：取500克上述颗粒混合74.1克氢化锂，将混合粉末放置于管式炉中，在氩气氛围下进行热处理， 以10℃/min的升温速率升温至650℃后保持5小时，自然冷却后将材料从管式炉中取出并过500目筛网，得到掺杂有钛和铁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.3，粉末电阻率为1Ω*cm，硅(111)晶面对应的微晶尺寸是4.6nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为500.1mAh/g，首次充放电效率90.2％。测得全电池的体积能量密度达到768.4Wh/L，500次充放电循环后的容量保持率为82.3％，500圈后的电池膨胀率为11.8％。
实施例20
相比实施例19，实施例20中改用中值粒径为5μm的硅氧化合物颗粒，采用与实施例19相同的包覆碳膜和喷雾干燥的工艺，但将掺杂源替换为8.8g四水合醋酸镁和108.5g九水合硝酸铁，并将喷雾干燥得到的粉末改用900℃加热3小时的热处理工艺，得到掺杂有镁和铁元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为51.3g，并将热处理工艺调整为575℃保温6小时，得到掺杂有镁和铁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.8，粉末电阻率为8Ω*cm，硅(111)晶面对应的微晶尺寸是3.1nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为533.2mAh/g，首次充放电效率89.3％。测得全电池的体积能量密度达到775.3Wh/L，500次充放电循环后的容量保持率为87.2％，500圈后的电池膨胀率为10.8％。
实施例21
相比实施例20，实施例21采用相似的包覆碳膜层的工艺，仅将热处理工艺调整为800℃保温2小时，并采用与实施例20相同的喷雾干燥工艺，但将掺杂源替换为13.2g四水合醋酸镁和22g一水合醋酸铜，并将喷雾干燥得到的粉末改用800℃加热3小时的热处理工艺，得到掺杂有镁和铜元素的包覆碳膜的硅氧化合物颗粒。扫描电镜的结果显示，颗粒表面没有含镁或含铜物质残留，说明镁和铜元素已全部掺杂到硅氧化合物内。同时X射线能谱分析的结果显示，颗粒表面的镁含量为0.2％，铜含量为0.7％，和该硅氧化合物内实际掺杂的镁元素和铜元素含量接近，说明镁元素和铜元素没有在颗粒表层富集。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为28.5g，并将热处理工艺调整为550℃保温6小时，得到掺杂有镁和铜元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.3，粉末电阻率为20Ω*cm，硅(111)晶面对应的微晶尺寸是1.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为564.7mAh/g，首次充放电效率85.8％。测得全电池的体积能量密度达到757.8Wh/L，500次充放电循环后的容量保持率为89％，500圈后的电池膨胀率为9.7％。
实施例22
相比实施例20，实施例22改用中值粒径为9μm的硅氧化合物颗粒，采用与实施例20相同的包覆碳膜层的工艺，随后采用干法包覆的方式将9.5g纳米氧化铝和18.8g纳米氧化铜均匀包覆在1000g上述颗粒表面，并在氮气气氛下，进行900℃保温3小时，得到掺杂有铝元素和铜元素的包覆碳膜的硅氧化合物。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为57g，并将热处理工艺调整为700℃保温5小时，得到掺杂有铝和铜元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.2，粉末电阻率为7Ω*cm，硅(111)晶面对应的微晶尺寸是4.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为521.3mAh/g，首次充放电效率91.6％。测得全电池的体积能量密度达到793.2Wh/L，500次充放电循环后的容量保 持率为86.5％，500圈后的电池膨胀率为12.1％。
实施例23
相比实施例20，实施例23采用相似的包覆碳膜层的工艺，仅将热处理工艺调整为1000℃保温2.5小时，并采用与实施例20相同的喷雾干燥工艺，但将掺杂源替换为166.7g九水合硝酸铝、4.3g六水合硝酸钇和223g四水合醋酸锰，并将喷雾干燥得到的粉末改用850℃加热6小时的热处理工艺，得到掺杂有铝、钇和锰元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为45.6g，并将热处理工艺调整为700℃保温5小时，得到掺杂有铝、钇和锰元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.8，粉末电阻率为0.1Ω*cm，硅(111)晶面对应的微晶尺寸是4.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为511mAh/g，首次充放电效率91.1％。测得全电池的体积能量密度达到781.2Wh/L，500次充放电循环后的容量保持率为86.6％，500圈后的电池膨胀率为11.9％。
实施例24
相比实施例23，实施例24采用相同的包覆碳膜层和喷雾干燥的工艺，但将掺杂源替换为264g四水合醋酸镁和339.2g四水合醋酸镍，并将喷雾干燥得到的粉末改用800℃加热8小时的热处理工艺，得到掺杂有镁和镍元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为57g，并将热处理工艺调整为600℃保温6小时，得到掺杂有镁和镍元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10，粉末电阻率为0.01Ω*cm，硅(111)晶面对应的微晶尺寸是4.3nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为492.4mAh/g，首次充放电效率90.3％。测得全电池的体积能量密度达到765.9Wh/L，500次充放电循环后的容量保持率为87％，500圈后的电池膨胀率为12％。
实施例25
相比实施例18，实施例25改用中值粒径为15μm的硅氧化合物颗粒，采用与实施例18相同的包覆碳膜层的工艺，随后采用干法包覆的方式将8.35g纳米氧化钛、13.3g纳米氧化铝和38.25g纳米氧化镍均匀包覆在1000g上述颗粒表面，并在氮气气氛下，进行900℃保温2小时，得到掺杂有钛、铝和镍元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为34.3g，并将热处理工艺调整为850℃保温2小时，得到掺杂有钛、铝和镍元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.3，粉末电阻率为1Ω*cm，硅(111)晶面对应的微晶尺寸是10.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为498mAh/g，首次充放电效率92.5％。测得全电池的体积能量密度达到768.4Wh/L，500次充放电循环后的容量保持率为80.4％，500圈后的电池膨胀率为14.3％。
实施例26
相比实施例19，实施例26改用中值粒径为5μm的硅氧化合物颗粒，并采用与实施例19相同的包覆碳膜层、喷雾干燥掺杂及锂金属掺杂工艺，仅将掺杂源替换为568.8g钛酸四丁酯和578.7g九水合硝酸铁，得到掺杂有钛和铁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9，粉末电阻率为0.05Ω*cm，硅(111)晶面对应的微晶尺寸是5.6nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为470mAh/g，首次充放电 效率91.6％。测得全电池的体积能量密度达到766.8Wh/L，500次充放电循环后的容量保持率为85.8％，500圈后的电池膨胀率为12.7％。
实施例27
相比实施例21，实施例27采用相同的包覆碳膜层和喷雾干燥掺杂的工艺，仅将掺杂源调整为4.4g四水合醋酸镁和1.57g一水合醋酸铜，得到掺杂有镁和铜元素的包覆碳膜的硅氧化合物颗粒。接下来采用热掺杂法进行锂金属掺杂，但将氢化锂的量调整为57g，并将热处理工艺调整为600℃保温6小时，得到掺杂有镁和铜元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.8，粉末电阻率为30Ω*cm，硅(111)晶面对应的微晶尺寸是1.9nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为545mAh/g，首次充放电效率89.6％。测得全电池的体积能量密度达到783.2Wh/L，500次充放电循环后的容量保持率为87.4％，500圈后的电池膨胀率为10.6％。
实施例28
相比实施例27，实施例28采用相似的包覆碳膜层的工艺，但将热处理工艺调整为1000℃保温2.5小时，得到包覆碳膜层的硅氧化合物。随后采用和实施例12相同的喷雾干燥工艺，将掺杂源替换为30.8g四水合醋酸镁和15.6g四水合醋酸锰，得到掺杂有镁和锰元素的包覆碳膜的硅氧化合物颗粒。接下来采用与实施例12相同的锂金属掺杂工艺，得到掺杂有镁和锰元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.6，硅(111)晶面对应的微晶尺寸是3.2nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为532mAh/g，首次充放电效率89.9％。测得全电池的体积能量密度达到780Wh/L，500次充放电循环后的容量保持率为86.8％，500圈后的电池膨胀率为11.1％。
实施例29
类似于实施例27，区别在于喷雾干燥的工艺过程中，将掺杂源替换为仅有8.8g四水合醋酸镁，因此产品为掺杂单一镁元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为10.8，粉末电阻率为46Ω*cm，硅(111)晶面对应的微晶尺寸是1.9nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持72小时不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为545mAh/g，首次充放电效率89％。测得全电池的体积能量密度达到779Wh/L，500次充放电循环后的容量保持率为86.4％，500圈后的电池膨胀率为10.6％。
实施例30
取1000克中值粒径为5μm的硅氧化合物颗粒(硅氧比为1:1)混合100克氢化锂，采用热掺杂法进行锂金属掺杂，热处理工艺为800℃保温2小时，得到含锂硅氧化合物。随后取500g上述颗粒均匀混合25g金属镁粉和9.4g纳米氧化铜，在氩气气氛下进行850℃保温1.5小时，得到掺杂有镁和铜元素的含锂硅氧化合物颗粒。最后通过化学气相沉积法在上述颗粒表面包覆碳膜层，以乙炔为碳源，在850℃下进行1小时包覆反应，得到包覆碳膜的掺杂有镁和铜元素的含锂硅氧化合物颗粒。
所得的硅负极活性材料的pH为9.5，硅(111)晶面对应的微晶尺寸是26nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为461.6mAh/g，首次充放电效率92.8％。测得全电池的体积能量密度达到726.8Wh/L，500次充放电循环后的容量保持率为76.1％，500圈后的电池膨胀率为17.8％。
对比例1
类似于实施例5，区别在于没有后续的喷雾干燥和锂掺杂的工艺过程，因此产品为包覆碳膜的硅氧化合物。
所得的硅负极活性材料的pH为7.4，硅(111)晶面对应的微晶尺寸是2.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，可坚持一周以上不产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为580.5mAh/g，首次充放电效率83％。测得全电池的体积能量密度达到723Wh/L，500次充放电循环后的容量保持率为90％，500圈后的电池膨胀率为9.5％。
对比例2
类似于实施例5，区别在于没有喷雾干燥及相应的热处理来掺杂镁元素的工艺过程，因此产品为包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为9.5，硅(111)晶面对应的微晶尺寸是2.7nm，含有该材料的水系匀浆浆料在65℃加速实验下，1小时内已发生明显产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为562mAh/g，首次充放电效率86.1％。由于浆料稳定性太差，导致匀浆涂布过程中出现产气和流变性变差的问题，涂布出来的极片质量较差，出现较多凹坑、粘接性差、掉粉等问题，大大影响了全电池的性能。实际测得全电池的体积能量密度为728.9Wh/L，500次充放电循环后的容量保持率为79％，500圈后的电池膨胀率为15.2％。
对比例3
类似于实施例11，区别在于锂掺杂的工艺过程中，氢化锂的量调整为148.2g，产品为掺有铝元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为12.5，硅(111)晶面对应的微晶尺寸是18nm，含有该材料的水系匀浆浆料在65℃加速实验下，12小时内出现产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为429mAh/g，首次充放电效率93.4％。测得全电池的体积能量密度达到733.1Wh/L，500次充放电循环后的容量保持率为76％，500圈后的电池膨胀率为13％。
对比例4
类似于实施例23，区别在于锂掺杂的工艺过程中，氢化锂的量调整为125.4g，产品为掺有铝、钇和锰元素的包覆碳膜的含锂硅氧化合物。
所得的硅负极活性材料的pH为12.5，硅(111)晶面对应的微晶尺寸是17nm，含有该材料的水系匀浆浆料在65℃加速实验下，12小时内出现产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为417mAh/g，首次充放电效率93.4％。测得全电池的体积能量密度达到728Wh/L，500次充放电循环后的容量保持率为76％，500圈后的电池膨胀率为13％。
对比例5
将1000g中值粒径为6μm的硅氧化合物颗粒(硅氧原子比为1:1)，65g低温煤沥青粉末，10g科琴黑粉末在包覆釜内干法混合均匀后，边搅拌边加入2000g二甲基甲酰胺，将混合粉末在二甲基甲酰胺中分散均匀。随后加热包覆釜至140℃并保持恒温搅拌3小时，最终再加热至160℃并恒温直至将二甲基甲酰胺蒸干，得到煤沥青和科琴黑共同包覆的硅氧化合物材料。将上述材料在氮气氛围下加热至1000℃并保持2小时使煤沥青碳化，同时硅氧化合物发生歧化反应。将冷却后得到的材料破碎并过500目筛网，得到碳膜/科琴黑复合膜层包覆的硅氧化合物粉末。
在相对湿度低于10％的干燥间内，采用行星式球磨机将氢化铝锂粗粉破碎后过500目筛网，得到的氢化铝锂细粉。取筛分后的氢化铝锂细粉150g，与上述碳膜/科琴黑复合膜层包覆的硅氧化合物粉末500g在VC混合机中高速混合20分钟。将上述混合粉末放入管式炉中，在氩气氛围下同时进行掺锂和掺铝热处理，以10℃/min的升温速率升 温至600℃后保持6小时，自然冷却后将材料从管式炉中取出并过500目筛网，得到掺有铝元素的含锂硅氧化合物。通过X射线衍射分析，此时所得的硅负极活性材料中出现了明显的金属铝相(如图5)，说明通过该对比例中所使用的铝元素掺杂源及掺杂工艺，更容易得到还原态的金属铝掺杂，而非铝的含氧化合物掺杂。由于铝的金属相无法有效地保护含锂硅氧材料，甚至会促进水与该材料的产气反应，因此含有该材料的水系匀浆浆料在65℃加速实验下1小时内急剧产气。同时，如图5所示，该材料的硅(111)晶面出现了两种晶粒尺寸，一种为5.4nm，另一种高达71nm，说明金属铝的存在促进了硅晶粒的局域长大。
最终测得含有该硅负极的半电池的首次嵌锂比容量为432mAh/g，首次充放电效率87％。测得全电池的体积能量密度达到702.3Wh/L。由于浆料产气过于严重，极片质量很差，最终含有该硅负极的全电池在500次充放电循环后的容量保持率为68％，500圈后的电池膨胀率为21％。
对比例6
类似于对比例5，区别在于锂和铝掺杂的工艺过程中，氢化铝锂的量调整为100克，同时将掺锂和掺铝的热处理工艺调整为770℃保温1h，得到掺有铝元素的含锂硅氧化合物。通过X射线衍射分析，此时所得的硅负极活性材料中仍然出现了明显的金属铝相，硅(111)晶面对应的微晶尺寸是26nm。含有该材料的水系匀浆浆料在65℃加速实验下，仍然在1小时内出现了显著产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为485mAh/g，首次充放电效率89％。测得全电池的体积能量密度达到749Wh/L，500次充放电循环后的容量保持率为73.2％，500圈后的电池膨胀率为19％。
对比例7
将1000g硅氧化合物颗粒、10g Super P粉末、203g柠檬酸铜和50g蔗糖在5000g去离子水中高速分散后将浆料进行喷雾干燥处理，随后将得到的粉末在氮气氛围下，900℃加热5小时后破碎并过500目筛网，得到的碳膜层/Super P复合膜层共包覆的铜掺杂硅氧化合物颗粒。取500克上述颗粒混合50克氢化锂，将混合粉末放置于管式炉中，在氩气氛围下进行热处理，以10℃/min的升温速率升温至750℃后保持1小时，自然冷却后将材料从管式炉中取出并过500目筛网，得到掺杂有铜元素的包覆碳膜/Super P复合膜层的含锂硅氧化合物。
所得的硅负极活性材料的硅(111)晶面对应的微晶尺寸是9nm，含有该材料的水系匀浆浆料在65℃加速实验下，2小时内出现产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为502mAh/g，首次充放电效率88.7％。测得全电池的体积能量密度达到752Wh/L，500次充放电循环后的容量保持率为76.5％，500圈后的电池膨胀率为16.8％。
对比例8
将1000g中值粒径为6μm的硅氧化合物颗粒(硅氧原子比为1:1)和65g低温煤沥青粉末在包覆釜内干法混合均匀后，边搅拌边加入2000g二甲基甲酰胺，将混合粉末在二甲基甲酰胺中分散均匀。随后加热包覆釜至140℃并保持恒温搅拌3小时，最终再加热至160℃并恒温直至将二甲基甲酰胺蒸干，得到煤沥青包覆的硅氧化合物材料。将上述材料在氮气氛围下加热至900℃并保持3小时使煤沥青碳化，同时硅氧化合物发生歧化反应。将冷却后得到的材料破碎并过500目筛网，得到碳膜包覆的硅氧化合物粉末。
在相对湿度低于30％的干燥间内，采用行星式球磨机将氢化锂粗粉破碎后过600目筛网，得到的氢化锂细粉，其最大颗粒尺寸约等于23μm。取筛分后的氢化锂细粉50g，与上述碳膜包覆的硅氧化合物粉末500g在VC混合机中高速混合20分钟。将上述混合粉末放入管式炉中，在氩气氛围下进行掺锂热处理，以10℃/min的升温速率升温至750℃后保持60分钟，自然冷却后将材料从管式炉中取出并过500目筛网，得到最终硅基复合材料产品。
所得的硅负极活性材料的硅(111)晶面对应的微晶尺寸是6.5nm，含有该材料的水系匀浆浆料在65℃加速实验下，1小时内已出现明显产气。最终测得含有该硅负极的半电池的首次嵌锂比容量为508mAh/g，首次充放电效率88％。测得全电池的体积能量密度达到753.1Wh/L，500次充放电循环后的容量保持率为76.2％，500圈后的电池膨胀率为16.1％。
以上所述，仅是本发明的较佳实施例，并非对本发明作任何形式上的限制，任何熟悉本专业的技术人员，在不脱离本发明技术方案范围内，依据本发明的技术实质，对以上实施例所作的任何简单的修改、等同替换与改进等，均仍属于本发明技术方案的保护范围之内。

Claims (21)

  1. 一种用于电池的负极活性材料，其具有负极活性物质颗粒，所述负极活性物质颗粒含有硅氧化合物，其特征在于，
    所述负极活性物质颗粒包括锂元素以及非锂掺杂金属，其中，
    所述非锂掺杂金属包括金属M1，所述金属M1包括钛、镁、锆、锌、铝、钇、钙中的一种或多种，所述非锂掺杂金属占所述负极活性材料的含量为0.01-20wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
  2. 根据权利要求1所述的负极活性材料，其特征在于，
    所述非锂掺杂金属还包括金属M2，所述金属M2包括铜、镍、铁、锰、钴、铬中的一种或多种。
  3. 根据权利要求2所述的负极活性材料，其特征在于，
    所述金属M2占所述负极活性材料的含量为0.01-20wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
  4. 根据权利要求2所述的负极活性材料，其特征在于，
    所述金属M1和所述金属M2占所述负极活性材料的含量为0.01-25wt％，优选为0.05-15wt％，进一步优选为0.1-10wt％，更优选为0.1-5wt％。
  5. 根据权利要求1所述的负极活性材料，其特征在于，
    所述金属M1以含氧化合物的形式存在于所述负极活性材料中，所述非锂掺杂金属的含氧化合物包括金属氧化物、金属硅酸盐、含锂复合金属硅酸盐以及锂与非锂掺杂金属的复合氧化物中的一种或多种。
  6. 根据权利要求1所述的负极活性材料，其特征在于，
    所述金属M1的含氧化合物以分散的方式分布于整个硅氧化合物中。
  7. 根据权利要求1所述的负极活性材料，其特征在于，
    所述金属M1的含氧化合物富集于所述硅氧化合物的表层，且浓度由所述表层至所述硅氧化合物的内部递减。
  8. 根据权利要求2所述的负极活性材料，其特征在于，
    所述金属M2以单质金属或含硅合金相的形式存在于所述负极活性材料中。
  9. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒中的锂含量为0.1-20wt％，优选为2-18wt％，进一步优选为4-15wt％。
  10. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒包括有Li 4SiO 4、Li 2SiO 3、Li 6Si 2O 7、Li 8SiO 6及Li 2Si 2O 5中的至少一种含锂化合物。
  11. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒的中值粒径在0.2-20μm之间，优选为1-15μm，更优选为2-10μm。
  12. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒还包含有单质硅纳米颗粒，分散于所述负极活性物质颗粒内的单质硅纳米颗粒的中值粒径在0.1-35nm之间，优选为0.5-20nm，更优选为1-15nm。
  13. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒中的硅元素含量为30-80wt％，优选为35-65wt％，进一步优选为40-65wt％。
  14. 根据权利要求1所述的负极活性材料，其特征在于，
    所述负极活性物质颗粒表面还包覆有碳膜层，所述碳膜层覆盖所述硅氧化合物的表面，所述碳膜层厚度在0.001-5μm之间，优选为0.005-2μm之间，进一步优选为0.01-1μm之间。
  15. 根据权利要求1所述的负极活性材料，其特征在于，
    所述碳膜层与所述硅氧化合物的重量之比为0.01:100-20:100，优选为0.1:100-15:100，进一步优选为1:100-12:100。
  16. 一种电极，其特征在于，包括权利要求1-15任一所述的负极活性材料。
  17. 包括权利要求1-15任一所述负极活性材料的极片或电池。
  18. 如权利要求1或2所述的负极活性材料的制备方法，其特征在于，包括：
    取硅氧化合物颗粒，将锂元素以及非锂掺杂金属掺杂至硅氧化合物颗粒；其中，所述硅氧化合物颗粒中硅和氧元素化学计量比为1:0.4-1:2，优选为1:0.6-1:1.5，进一步优选为1:0.8-1:1.2。
  19. 如权利要求18所述的制备方法，其特征在于，
    所述硅氧化合物颗粒的中值粒径为0.2-20μm之间，优选为1-15μm，进一步优选为2-10μm。
  20. 如权利要求18所述的制备方法，其特征在于，
    所述硅氧化合物颗粒为包覆有碳膜层的颗粒。
  21. 如权利要求18所述的制备方法，其特征在于，
    在将所述非锂掺杂金属掺杂入硅氧化合物颗粒之后，掺杂所述锂元素。
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