WO2022052054A1 - 硅基储锂材料及其制备方法 - Google Patents

硅基储锂材料及其制备方法 Download PDF

Info

Publication number
WO2022052054A1
WO2022052054A1 PCT/CN2020/114849 CN2020114849W WO2022052054A1 WO 2022052054 A1 WO2022052054 A1 WO 2022052054A1 CN 2020114849 W CN2020114849 W CN 2020114849W WO 2022052054 A1 WO2022052054 A1 WO 2022052054A1
Authority
WO
WIPO (PCT)
Prior art keywords
silicon
layer
storage material
lithium storage
based lithium
Prior art date
Application number
PCT/CN2020/114849
Other languages
English (en)
French (fr)
Inventor
马飞
刘冬冬
吴志红
李凤凤
Original Assignee
上海杉杉科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 上海杉杉科技有限公司 filed Critical 上海杉杉科技有限公司
Priority to PCT/CN2020/114849 priority Critical patent/WO2022052054A1/zh
Priority to EP20952842.1A priority patent/EP4231382A1/en
Priority to US18/044,953 priority patent/US20230361279A1/en
Priority to CN202080001969.4A priority patent/CN112219295B/zh
Publication of WO2022052054A1 publication Critical patent/WO2022052054A1/zh

Links

Images

Classifications

    • 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
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/049—Manufacturing of an active layer by chemical means
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/5835—Comprising fluorine or fluoride salts
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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
    • 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 present application relates to the field of lithium ion batteries, and in particular, to a silicon-based lithium storage material and a preparation method thereof.
  • the SEI film formed on the surface of the lithium electrode itself in the electrolyte is unstable, and its mechanical modulus and ionic conductivity cannot meet the requirements, resulting in a rapid decline in the cycle performance of lithium batteries. .
  • Another study discloses a lithium-ion battery anode SEI film and a preparation method for its segmented formation.
  • parameters such as formation temperature, current density, cut-off voltage, baking pressure, baking time and baking temperature.
  • this method requires pre-rolling or laminating the cathode sheet, anode sheet and separator to form a bare cell, then putting it into a packaging shell, injecting electrolyte after baking, and making different types through a complex chemical process.
  • the present application provides a new silicon-based lithium storage material and a preparation method thereof, which can improve the characteristics of the silicon-based lithium storage material as an active material of a lithium ion secondary battery under high temperature storage conditions, and at the same time improve the cycle characteristics of the secondary battery and initial charge-discharge Coulomb efficiency.
  • a silicon-based lithium storage material including: an inner core, the inner core includes silicon element with a valence of 0 to 4; and a first shell layer, the first shell layer coats or partially coats the inner core , the first shell layer includes a fluorocarbon layer, and the fluorocarbon layer includes a fluorocarbon.
  • the first shell layer further includes a carbon material layer, the carbon material layer is located between the inner core and the fluorocarbon layer, and the carbon material layer includes a carbon material.
  • NF is the mole number of fluorine in the first shell layer
  • NC is the mole number of carbon element in the first shell layer
  • the carbon material includes at least one of amorphous carbon or graphitized carbon.
  • the mass of the first shell layer accounts for 0.5% to 10% of the total mass of the silicon-based lithium storage material.
  • the thickness of the first shell layer is 1 nm ⁇ 50 nm.
  • the inner core further includes a doping element R
  • the doping element R includes at least one of the elements of the main group I to VI, wherein 0 ⁇ N R /N Si(0 ⁇ 4) ⁇ 1.5, NR is the number of moles of the doping element R, and N Si (0-4) is the number of moles of the silicon element with a valence of 0 to 4.
  • the doping element R includes at least one of O, N, C, Li, Mg, Ca, Al, P and Be.
  • the silicon-based lithium storage material further includes: a second shell layer, the second shell layer covers or partially covers the first shell layer, and the second shell layer includes fluorine Lithium compound.
  • the mass of the second shell layer accounts for 0.1% to 2% of the total mass of the silicon-based lithium storage material.
  • Another aspect of the present application also provides a method for preparing a silicon-based lithium storage material, including: providing a core material, the core material comprising silicon elements with a valence of 0 to 4; and depositing a carbon material on the surface of the core material to form carbon material layer; the carbon material layer is subjected to fluorination treatment to convert all or part of the carbon material layer into a fluorocarbon layer to form a first shell layer.
  • the carbon material layer is fluorinated by using a fluorine-containing gas, and 0 ⁇ N F /N C ⁇ 1.5, where NF is the number of moles of fluorine in the fluorine-containing gas, and N c is the mole number of carbon element in the carbon material layer.
  • the fluorine-containing gas includes at least one of F 2 , NF 3 and ClF 3 .
  • the temperature of the fluorination treatment is 20°C to 600°C.
  • the preparation method of the silicon-based lithium storage material further includes: placing the inner core material coated with the first shell layer in a lithium solution; After the material adsorbs the lithium solution, the solvent of the lithium solution is removed; heat treatment makes the lithium in the lithium solution react with the core material, and a lithium compound is attached to the surface of the first shell layer; cooled to a specific temperature, The lithium compound is subjected to a fluorination treatment to convert the lithium compound into a lithium fluoride compound, and a second shell layer is formed on the surface of the first shell layer.
  • the solvent of the lithium solution includes at least one of naphthalene, anthracene, tetrahydrofuran and N-methylpyrrolidone.
  • the temperature of the heat treatment ranges from 400°C to 600°C.
  • the lithium reacts with the core material to form lithium silicate, and the lithium compound attached to the surface of the first shell layer includes at least one of lithium hydroxide and lithium carbonate kind.
  • the core material further includes a doping element R
  • the doping element R includes at least one element of the main group I to VI, where 0 ⁇ N R /N Si (0 to 4) ⁇ 1.5, NR is the number of moles of the doping element R, and N Si (0-4) is the number of moles of the silicon element with a valence of 0-4.
  • the doping element R includes at least one of O, N, C, Li, Mg, Ca, Al, P and Be.
  • the carbon material includes at least one of amorphous carbon or graphitized carbon.
  • the silicon-based lithium storage material of the technical solution of the present application includes an inner core and a first shell layer, the first shell layer covers or partially covers the first shell layer, and the first shell layer includes a fluorocarbon compound, so The fluorocarbon will react with lithium during the first cycle, and the potential to lithium (vs. Li + /Li) of this reaction is significantly higher than that of ordinary graphite materials. Therefore, after the battery is assembled, the fluorocarbon will preferentially react with lithium. The lithium salt in the electrolyte reacts at a high potential, which can better adapt to the high voltage system.
  • the fluorocarbon reacts with lithium to form fluorine-containing inorganic substances attached to the surface of the silicon-based lithium storage material.
  • the fluorine-containing inorganic substances have ceramic properties and a high Young's modulus, which not only can It can effectively improve the side reactions of the surface layer during high-temperature cycling, and can ensure that after the core expands and contracts, there is still a part of the conductive lithium ion medium, thereby effectively improving the high-temperature characteristics of the battery; at the same time, it can also prevent the high-rate charge and discharge process.
  • the risk of penetration of lithium dendrites with low Young's modulus caused by lithium can avoid safety accidents.
  • the fluorocarbon layer has higher molecular interlayer spacing and ion diffusivity, thereby facilitating the insertion and extraction of lithium ions, reducing the resistance of the material, and effectively improving the kinetics and stability of the battery.
  • the first shell layer further includes a carbon material layer, and the carbon material layer is located between the inner core and the fluorocarbon layer.
  • the carbon material layer is located between the inner core and the fluorocarbon layer.
  • the surface of the first shell layer coats or partially coats a second shell layer
  • the second shell layer includes a lithium fluoride compound, and fluorinated components in the first shell layer and the second shell layer
  • the silicon-based lithium storage material obtain a higher first Coulomb efficiency, but also a better water-system homogenization stability can be obtained, which solves the problem that the existing lithiation technology is easy to generate active substances in the surface layer and is difficult to homogenize.
  • FIG. 1 is a schematic structural diagram of a silicon-based lithium storage material according to an embodiment of the application.
  • FIG. 2 is a schematic structural diagram of another silicon-based lithium storage material according to an embodiment of the application.
  • FIG. 3 is a schematic structural diagram of another silicon-based lithium storage material according to an embodiment of the application.
  • FIG. 4 is a schematic structural diagram of another silicon-based lithium storage material according to an embodiment of the application.
  • FIG. 6 is the first-week battery cyclic voltammetry curves of Example 1 and Comparative Example 1 of the present application;
  • FIG. 7 is the cyclic voltammetry curve of the battery in the first week of Example 7 of the present application.
  • an embodiment of the present application provides a silicon-based lithium storage material
  • the silicon-based lithium storage material includes: an inner core 1 , the inner core includes silicon elements with valences of 0 to 4; a first shell layer 2 , the first shell layer 2 A shell layer 2 wraps or partially wraps the inner core 1 , the first shell layer 2 includes a fluorocarbon layer 21 , and the fluorocarbon layer 21 includes a fluorocarbon compound.
  • the silicon element with a valence of 0 to 4 may exist as elemental silicon, or as silicon oxide (SiOx, 0 ⁇ x ⁇ 2), or as silicic acid It exists in the form of salt (M y SiO 3 , 1 ⁇ y ⁇ 2; M is an element of main group I, II, III, such as Li, Na, Mg, Ca or Al, etc.).
  • N Si(1 ⁇ 4) /N Si(0) 0 ⁇ N Si(1 ⁇ 4) /N Si(0) ⁇ 1
  • the N Si(1 ⁇ 4) is the mole number of silicon with a valence between 1 and 4
  • the N Si(0 ) refers to the number of moles of silicon with a valence of 0 that exists in elemental form
  • N Si(1-4) /N Si(0) is the molar ratio between silicon with a valence of 1-4 and elemental silicon.
  • the value of N Si( 1 ⁇ 4) /N Si(0) can be achieved by adjusting the content among silicon, silicon oxide and silicate contained in the inner core 1 .
  • the value of N Si(1 ⁇ 4 ) /N Si(0) is, for example, 0, 0.2, 0.5, 0.8, or 1.
  • the inner core 1 may also include a doping element R, and the doping element R includes at least one of main group elements I to VI, for example, the The doping element R includes at least one of O, N, C, Li, Mg, Ca, Al, P, and Be.
  • the doping element R can exist in an atomic state or an ionic state in the inner core 1, and atoms of the doping element R can combine with each other to form an ionic state, for example, the doping element can exist in Mg elemental substance, Ca element or Al element, or exists in metal oxides, metal salts, such as MgO, CaO, Mg 3 (PO 4 ) 2 and the like.
  • the doping element R can also be combined with silicon element to form silicon oxide, silicate, etc., for example, MgSiO 3 , CaSiO 3 or Li 2 SiO 3 and the like.
  • the doping element R has the ability to accept electrons, so that the material can be neutralized. By adjusting the doping amount of the doping element R, the overall cycle performance and the first Coulomb efficiency of the battery can be changed.
  • 0 ⁇ N R /N Si(0-4) ⁇ 1.5 wherein the NR is the mole number of the doping element R, and N Si(0-4) is the valence of 0-4.
  • the number of moles of silicon element, N R /N Si (0-4) is the molar ratio between the doping element R and the silicon element with a valence of 0-4.
  • the silicon-based lithium storage material of the embodiment of the present application further includes a first shell layer 2, and the first shell layer 2 partially coats or completely coats the inner core 1.
  • the degree of coating also varies, and Fig. 1 schematically shows the situation of complete coating.
  • the first shell layer 2 does not necessarily have the right annular cladding structure as shown in FIG. 1 , but the cladding thickness of the first shell layer 2 on the surface of the inner core 1 is approximately approximated.
  • the mass of the first shell layer 2 accounts for 0.5% to 10% of the total mass of the silicon-based lithium storage material, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7% %, 8% or 9% etc.
  • the thickness of the first shell layer 2 is, for example, 1 nm to 50 nm.
  • the first shell layer 2 includes a fluorocarbon layer 21, and the fluorocarbon layer 21 includes a fluorocarbon.
  • the surface of the first shell layer 2 is coated with a fluorocarbon, so that a directional reaction will occur during the first cycle of the battery: CF x +xLi ⁇ C+xLiF, the reaction's potential to lithium (vs.Li + / Li) is significantly higher than that of ordinary graphite materials, so after the battery is assembled, the fluorocarbon will preferentially react with the lithium salt in the electrolyte at a high potential, which can better adapt to the high voltage system, and the surface layer of the silicon-based lithium storage material A fluorine-containing inorganic substance is generated.
  • the fluorine-containing inorganic substance has ceramic properties and a high Young's modulus, which can not only effectively improve the side reactions of the surface layer during high temperature cycling, but also ensure that after the inner core 1 expands and contracts, there is still Partially conductive lithium ion medium, thereby effectively improving the high-temperature characteristics of the battery; at the same time, it can also prevent the penetration risk of lithium dendrites with low Young's modulus caused by the precipitation of lithium during the high-rate charge and discharge process, and avoid safety accidents. If there is no fluorocarbon on the surface of the inner core, the materials on the inner core will react at a lower potential to generate organic components, such as ROCO 2 Li, ROLi, (ROCO 2 Li) 2 and the like.
  • the silicon-based lithium storage material of the embodiment of the present application has the advantage of directionally generating lithium fluoride on the surface of the fluorocarbon layer 21 , which is equivalent to regulating the SEI film formed by the silicon-based lithium storage material as an electrode material during the first cycle of the battery.
  • composition and because the original layer (fluorocarbon layer 21) has a high molecular interlayer spacing, it still has a good ion diffusion channel after film formation, so it forms a stable and low resistance SEI film, which significantly improves the material. impedance, cycling and high temperature performance.
  • the first shell layer 2 not only includes a fluorocarbon layer 21, but also includes a carbon material layer 22, and the carbon material layer 22 is located between the inner core 1 and the between the fluorocarbon layers 21 .
  • the NF is the number of moles of fluorine in the first shell layer 2 , that is, the fluorine in the fluorocarbon layer 21
  • the number of moles of elements, the NC is the number of moles of carbon elements in the first shell layer 2, that is, the total number of moles of carbon elements in the fluorocarbon layer 21 and the carbon material layer 22, so
  • the NF / NC is the molar ratio of fluorine to carbon in the first shell layer 2 .
  • the organic SEI film is the main component, and the condition 0.3 ⁇ M inorganic SEI film /M organic SEI film ⁇ 2 is met; while the inorganic SEI film is the main component near the coating side, and the condition 1.5 ⁇ M inorganic SEI film /M organic SEI film ⁇ 7, where M inorganic SEI film represents the quality of the inorganic SEI film, M organic SEI film represents the quality of the organic SEI film, M inorganic SEI film /M organic SEI film represents the organic SEI film and the inorganic SEI film Mass ratio of SEI film.
  • the maximum potential of dQ/dV at the end of the lithium intercalation material can be adjusted to 0.25V ⁇ 2.5V, and the SEI film can also be changed. composition and structure, thereby significantly improving the high temperature and cycling stability of silicon-based materials.
  • the carbon material layer 22 includes a carbon material including at least one of amorphous carbon or graphitized carbon.
  • the carbon material layer 22 includes at least one of an amorphous carbon layer or a graphitized carbon layer. That is to say, the surface of the first shell layer 2 may include an amorphous carbon layer or a graphitized carbon layer or both an amorphous carbon layer and a graphitized carbon layer.
  • the amorphous carbon layer is directly coated on the surface of the first shell layer 2, and the graphitized carbon layer is then coated on the surface of the amorphous carbon layer.
  • the graphitized carbon layer is directly coated on the surface of the first shell layer 2, and the amorphous carbon layer is then coated on the surface of the graphitized carbon layer.
  • more than one amorphous carbon layer and more than one graphitized carbon layer are alternately arranged.
  • the "coating" described in the embodiments of the present application may be partial coating or complete coating. Depending on the manufacturing process of the silicon-based lithium storage material, the coating degree is also different.
  • the amorphous carbon layer Since the amorphous carbon layer is a loose amorphous carbon structure, it plays a buffer role in the lithium insertion expansion of the silicon-based lithium storage material, while the graphitized carbon layer is a crystalline carbon structure with a high degree of graphitization.
  • the lithium intercalation expansion of the lithium storage material plays a certain restraint role, preventing the cracking of the carbon material layer and the deactivation of the active material during the lithium deintercalation process of the silicon-based lithium storage material. Therefore, the alternately arranged amorphous carbon layers And the graphitized carbon layer can better adjust the charge-discharge performance of the silicon-based lithium storage material and improve the cycle life of the battery.
  • the fluorocarbon layer 21 of the fluorinated part has higher molecular interlayer spacing and ion diffusivity, which is conducive to the insertion and extraction of lithium ions and reduces the material
  • the impedance of the battery is effectively improved, and the kinetics and stability of the battery are effectively improved; the carbon material layer 22 of the non-fluorinated part ensures the electrical conductivity and reduces the polarization problem at high rates.
  • the silicon-based lithium storage material may further include a second shell layer 3 , and the second shell layer 3 covers or partially covers the first shell Layer 2, the second shell layer 3 includes a lithium fluoride compound.
  • the mass of the second shell layer 3 accounts for 0.1%-2% of the total mass of the silicon-based lithium storage material, for example, 0.1%, 0.2%, 0.3%, 0.5%, 1%, 1.5% or 2%.
  • the lithium fluoride compound is, for example, lithium fluoride.
  • the fluorinated components in the first shell layer 2 and the second shell layer 3 can not only enable the silicon-based lithium storage material to obtain a higher first Coulomb efficiency, but also obtain a better stability of the water system homogenate, which is a better solution.
  • the problem that the existing lithiation technology is easy to generate active material in the surface layer and difficult to homogenize is solved.
  • Embodiments of the present application also provide a method for preparing a silicon-based lithium storage material, including:
  • Step S1 providing a core material, the core material includes silicon element with a valence of 0 to 4;
  • the silicon element with 0-4 valence may exist in the form of elemental silicon, such as polycrystalline silicon; or in the form of +4 oxidation state of silicon, such as silicon dioxide, including
  • the raw material of silica is, for example, quartz, and specifically, ⁇ -type quartz can be selected.
  • the +4 oxidation state of silicon can also be a silicate, such as a compound of the general formula My SiO 3 , wherein 1 ⁇ y ⁇ 2 , M is an element of the main group I, II, III, such as Li, Na, Mg, Ca or Al etc.
  • the core material includes both elemental silicon and a silicon-containing compound.
  • N Si(1 ⁇ 4) /N Si(0) 0 ⁇ N Si(1 ⁇ 4) /N Si(0) ⁇ 1
  • the N Si(1 ⁇ 4) is the mole number of silicon with a valence between 1 and 4
  • the N Si(0 ) refers to the number of moles of silicon with a valence of 0 that exists in elemental form
  • N Si(1-4) /N Si(0) is the molar ratio between silicon with a valence of 1-4 and elemental silicon.
  • the core material may further include a doping element R, and the doping element R includes at least one of the main group elements I to VI, for example, the doping element R includes O, N, C, Li, Mg, At least one of Ca, Al, P, Be.
  • the raw material for providing the doping element R can be metal elemental Mg, or can be metal oxides, metal hydroxides, or metal salts, such as MgO, CaO, Mg 3 (PO 4 ) 2 , MgSO 3 , LiOH, Li 2 CO 3 , MgSiO 3 , CaSiO 3 or Li 2 SiO 3 etc.
  • the core material may be prepared by providing a first mixture including at least an elemental state of silicon, a +4 oxidation state of silicon, and a dopant element R, such as the first mixture
  • a mixture may include polysilicon, beta - quartz, and Li2CO3, or the first mixture may include polysilicon, beta-quartz, and LiOH , or polysilicon, beta-quartz, and MgCO3 , and adjust the first mixture
  • the composition ratio of each raw material in a mixture is such that 0 ⁇ NR /NSi (0 ⁇ 4) ⁇ 1.5, wherein NR is the mole number of doping element R, and NSi(0 ⁇ 4) is the valence between 0 ⁇ 4 4 moles of silicon element; then, the first mixture is heated to a molten state under the protection of a non-oxidizing gas, and then lowered to room temperature at a cooling rate of 5°C/S ⁇ 30°C/S, and the
  • the non-oxidizing gas can be an inert gas, such as helium
  • Step S2 is performed, and carbon material is deposited on the surface of the core material to form a carbon material layer.
  • the method of depositing carbon material can include:
  • the carbon source material is passed through the pre-decomposition zone to form a decomposition product, wherein the carbon source material includes one or more of gaseous carbon source material, vaporized carbon source material or atomized carbon source material.
  • the flow velocity V G of the decomposition product entering the reaction chamber of the deposition coating zone and the molar flow rate of the decomposition product and the mass ratio Mc/M of the inner core material are regulated, so that the inner core material and the decomposition product occur in the deposition coating zone.
  • a deposition coating reaction is performed to form a carbon material layer on the surface of the core material
  • the carbon material layer may include an amorphous carbon layer or a graphitized carbon layer or a composite layer including an amorphous carbon layer and a graphitized carbon layer, wherein 0.01 ⁇ V G ⁇ 100, 0.001 ⁇ Mc/M ⁇ 1, the unit of V G is m/min, the unit of M C is mol/min, in terms of carbon atoms, M is the mass of the core material, the unit is kg.
  • the thickness of the carbon material layer is controlled by adjusting the ratio of Mc/M.
  • the gas providing the non-oxidizing atmosphere includes, for example, any one or more of hydrogen, nitrogen or inert gas, which are used as protective gas, carrier gas and diluent gas for the reaction in the pre-decomposition zone.
  • the gaseous carbon source material includes hydrocarbons that are gaseous at room temperature and aldehydes that are gaseous at room temperature, the gaseous carbon source material includes methane, ethane, ethylene, acetylene, propane, and propylene, and the vaporized carbon source material is room temperature. It is a liquid carbonaceous material above room temperature but lower than the temperature of the pre-decomposition zone, and the vaporized carbon source material includes n-hexane, ethanol and benzene.
  • the atomized carbon source material is a material that is difficult to evaporate by heating, and can be made into small droplets through an atomization device, for example, a material that is liquid when the temperature is lower than the pre-decomposition zone.
  • the atomized carbon source material includes polyethylene and polypropylene.
  • a nitrogen-containing substance in the process of the deposition coating reaction, may also be introduced, and the nitrogen-containing substance includes one or more of NH 3 , acetonitrile, aniline or butylamine .
  • the nitrogen-containing substance includes one or more of NH 3 , acetonitrile, aniline or butylamine .
  • Step S3 is performed, and the carbon material layer is subjected to fluorination treatment to convert all or part of the carbon material layer into a fluorocarbon layer to form a first shell layer.
  • a fluorine-containing gas may be used to react with the material of the carbon material layer, so that the material of the carbon material layer is fully or partially fluorinated into a fluorocarbon compound.
  • the fluorine-containing gas may include at least one of F 2 , NF 3 and ClF 3 .
  • the fluorination treatment can be carried out in any one of a fluidized bed reactor, a rotary furnace, a vertical moving bed reactor, a tunnel furnace, a batch furnace or a rotary kiln.
  • the temperature of the fluorination treatment is 20°C to 600°C, for example, 20°C, 50°C, 100°C, 150°C, 200°C, 300°C, 400°C or 500°C, etc.
  • the degree of fluorination is controlled by adjusting the molar ratio between the fluorine element in the fluorine-containing gas and the carbon element in the carbon material layer. If the number of moles of fluorine in the fluorine -containing gas (NF) and the number of moles of carbon in the carbon material layer ( NC ) are in an equivalent ratio, or when NF is in excess relative to NC , the carbon material All the carbon elements in the layer are combined with the fluorine element in the fluorine-containing gas to form a fluorocarbon compound, that is, the carbon material layer is completely converted into a fluorocarbon compound layer, that is, the first shell layer formed is fluorocarbon layer; if NF is a small amount relative to NC , the fluorine element in the fluorine-containing gas and part of the carbon element in the carbon material layer combine to form a fluorocarbon compound, that is, the There are still some carbon elements in the carbon material layer that do not participate in the reaction.
  • NF moles of fluorine in the flu
  • the formed first shell layer includes fluorine.
  • the fluorinated fluorocarbon layer and the unfluorinated carbon material layer Since the fluorine element gradually enters the interior of the carbon material layer from the surface of the carbon material layer when the fluorine-containing gas treats the carbon material layer, the surface of the carbon material layer is first fluorinated, and then the surface of the carbon material layer is fluorinated.
  • the fluorination is carried out inward sequentially, so when NF is a small amount relative to NC , the fluorocarbon layer formed by fluorination is located on the surface of the unfluorinated carbon material layer, that is, the unfluorinated carbon material layer is located on the surface of the non-fluorinated carbon material layer. between the fluorocarbon layer and the core material.
  • the non-fluorinated carbon material layer has an isolation function, preventing the direct contact of the fluorocarbon layer with the core material.
  • the performance of the battery is the best, where M (fluorine-containing inorganic film) represents the quality of the fluorine-containing inorganic film, and M (organic composition film) represents the quality of the organic composition film.
  • the inorganic SEI and The mass ratio of the organic SEI for example, 0 ⁇ N F /N C ⁇ 1.5.
  • the ratio of the number of moles of fluorine in the fluorine-containing gas (NF ) to the number of moles of carbon in the carbon material layer (N C ) can be adjusted by adding The amount of the fluorine-containing gas is controlled. For example, within a certain period of time, by adjusting the flow rate of the fluorine-containing gas, and then adjusting the amount of the fluorine-containing gas, or, under a fixed flow rate, by adjusting the inflow time of the fluorine-containing gas, all the the amount of fluorine-containing gas.
  • the mass of the first shell layer that is, the total mass of the fluorinated fluorocarbon layer and the non-fluorinated carbon material layer accounts for 0.5% to 0.5% of the total mass of the silicon-based lithium storage material. 10%.
  • the silicon-based lithium storage material obtained through the above preparation process has good interfacial stability during charging and discharging.
  • the following steps can also be performed:
  • the core material coated with the first shell layer is placed in a lithium solution.
  • the solvent of the lithium solution may include at least one of naphthalene, anthracene, tetrahydrofuran, N-methylpyrrolidone, or other solvents that can disperse lithium.
  • the solvent of the lithium solution is removed, and the solvent removal method may be a common drying method, such as vacuum drying.
  • the purpose of adsorbing lithium solution is to adsorb lithium on the surface of the first shell layer.
  • Lithium plays a crucial role in improving the first coulombic efficiency.
  • the amount of adsorbed lithium will directly affect the improvement effect of the first coulombic efficiency.
  • the concentration of lithium solution can be adjusted by adjusting the lithium solution. or immersion time to control the amount of adsorbed lithium.
  • the heat treatment is performed to make the lithium in the lithium solution react with the core material, and a lithium compound is attached to the surface of the first shell layer.
  • the purpose of the heat treatment is to make the adsorbed lithium enter the surface of the core material and react with the core material: SiOx+Li ⁇ LiSiOy, to convert the silicon oxide compound in the core material into an irreversible lithium silicate, thereby Improved the first coulomb efficiency.
  • the temperature of the heat treatment ranges from 400°C to 600°C, such as 400°C, 500°C, 550°C, and the like.
  • the lithium compound may include at least one of lithium hydroxide and lithium carbonate.
  • the heat treatment After the heat treatment, it is cooled to a specific temperature, eg, room temperature, and then the lithium compound is subjected to a fluorination treatment.
  • a fluorination treatment the material cooled to room temperature can be immersed in hydrofluoric acid.
  • the hydrofluoric acid reacts with the lithium compound (LiOH, Li 2 CO 3 ): LiOH+HF ⁇ LiF+H 2 O; Li 2 CO 3 +2HF ⁇ 2LiF+CO 2 ⁇ +H 2 O, the lithium compound is converted into a lithium fluoride compound, and a second shell layer is formed on the surface of the first shell layer.
  • the mass of the second shell layer accounts for 0.1%-2% of the total mass of the silicon-based lithium storage material.
  • the silicon-based lithium storage materials formed by the methods described in the embodiments of the present application and having a first shell layer (including a carbon material layer and a fluorocarbon layer) and a second shell layer are tested, and the results are as follows:
  • FIG. 5 is an XRD pattern of a silicon-based lithium storage material.
  • the diffraction angle 2 ⁇ shows the height A1 of the peak attributed to Li 2 SiO 3 in the range of 26.5° to 27.2°, and the diffraction angle 2 ⁇ shows in the range of 44.5° to 45.0°.
  • the height A2 of the peak attributed to LiF satisfies the following condition: 0 ⁇ A2/A1 ⁇ 0.45. Since the crystallinity of LiF should not be too high, if the crystallinity of LiF is high, the formed film will not be dense, which will affect the improvement effect of the first Coulomb efficiency, so the peak value of LiF should not be too strong.
  • the C1s electron binding energy appears at 288.4 ⁇ 0.2Ev (CF bond) and 283.5 ⁇ 0.2eV (amorphous CC bond) with broad peaks with intensities of I 288 and I 283 , where 0 ⁇ I 288 /I 283 ⁇ 0.3, indicating that the formed first shell includes CC bonds and CF bonds, corresponding to carbon materials and fluorocarbons in silicon-based lithium storage materials, respectively; and the F1s electron binding energy appears at 684-694 eV at least 2 There are two peaks, indicating that the formed silicon-based lithium storage material has two kinds of fluorine compounds, corresponding to the fluorocarbon compound and the fluorolithium compound in the silicon-based lithium storage material.
  • the inorganic SEI film on the surface of the silicon-based lithium storage material mainly includes Li 2 CO 3 , LiOH, LiF, Li 2 O, Li 2 CO 3
  • the organic SEI film mainly contains Li-OC compounds
  • the XPS spectrum of Li on the solvent side is in the 52-58 eV region.
  • the surface carbon-carbon layer spacing is in the range of 0.35-0.45nm and contains at least two kinds, wherein the maximum value-minimum value>0.05nm, indicating that the first shell layer formed includes at least two kinds
  • the carbon-carbon interlayer spacing which is due to the strong electronegativity of fluorine and the large atomic radius, makes the original carbon-carbon interlayer distance deviate from the original range, so there are at least two carbon-carbon interlayer distances.
  • the preparation method of the embodiment of the present application is simple in process and can be mass-produced, and the prepared silicon-based lithium storage material has good kinetic performance, high temperature and cycle stability, and the silicon-based lithium storage material includes a first shell layer and The second shell layer, and both the first shell layer and the second shell layer contain fluorine-containing components, so it has a high first Coulomb efficiency, and also has a high water system homogenization stability. Active substances are formed on the surface of the base lithium storage material, which leads to the problem of difficulty in homogenization, avoids additional processing procedures, and reduces costs.
  • the battery system made of the silicon-based lithium storage material of the embodiment of the present application can significantly reduce or avoid the addition of fluoroethylene carbonate, and is not only suitable for a positive electrode matching ternary battery system, but also suitable for a lithium cobalt oxide high voltage system.
  • the inner core material comprising silicon element with a valence of 0 to 4;
  • Amorphous carbon is deposited on the surface of the core material to form a carbon material layer, and the mass of the amorphous carbon accounts for 3% of the total mass of the silicon-based lithium storage material, denoted as Mc;
  • the prepared silicon-based lithium storage material was applied to the coin cell system, and the following tests were carried out:
  • Rate discharge (lithium intercalation): fixed at 0.1C charging (delithiation), and the capacity ratios of 0.5C, 1.5C, 3.0C, 5.0C and 0.1C charging (delithiation) respectively;
  • Rate charging fixed at 0.1C discharge (lithium intercalation), and discharge (lithium intercalation) capacity ratios at 0.5C, 1.0C, 3.0C, 5.0C and 0.1C respectively.
  • Example 1 for specific process description, and refer to Table 1 for specific process data and performance parameters of the formed silicon-based lithium storage material.
  • the inner core material comprising silicon element with a valence of 0 to 4;
  • Amorphous carbon is deposited on the surface of the core material to form a carbon material layer, and the mass of the amorphous carbon accounts for 3% of the total mass of the silicon-based lithium storage material, denoted as Mc;
  • the heat treatment causes lithium to enter into the core material and react with the core material, and a lithium compound is attached to the surface of the first shell layer;
  • the heat-treated material is immersed in a hydrofluoric acid solution for fluorination treatment, so that the lithium compound is converted into a lithium fluoride compound, and a second shell layer is formed on the surface of the first shell layer, wherein the lithium fluoride compound is formed.
  • the mass of the compound accounts for 0.2% of the total mass of the silicon-based lithium storage material, and is denoted as M LiF .
  • the prepared silicon-based lithium storage material was applied to a button battery system and tested.
  • the specific test method was shown in Example 1, and the specific process data and the performance parameters of the formed silicon-based lithium storage material were shown in Table 1. And tested the cyclic voltammetry curve of the battery in the first week, as shown in Figure 7.
  • the inner core material comprising silicon element with a valence of 0 to 4;
  • Amorphous carbon is deposited on the surface of the core material to form a carbon material layer, and the mass of the amorphous carbon accounts for 3% of the total mass of the silicon-based lithium storage material, which is denoted as Mc.
  • the prepared silicon-based lithium storage material was applied to a button battery system and tested.
  • the specific test method was shown in Example 1, and the specific process data and the performance parameters of the formed silicon-based lithium storage material were shown in Table 1. And tested the cyclic voltammetry curve of the battery in the first week, as shown in Figure 6.
  • lithium fluoride is dissolved in isopropanol to obtain solution A.
  • the material prepared in Comparative Example 1 was mixed with solution A to obtain a homogeneous system, which was dried in a vacuum dryer at 120° C. to remove isopropanol.
  • the prepared silicon-based lithium storage material was applied to a button battery system and tested.
  • the specific test method was referred to in Example 1, and the performance parameters of the formed silicon-based lithium storage material were shown in Table 1.
  • lithium fluoride, polyaniline and isopropanol being 1: 19: 120
  • lithium fluoride and polyaniline were sequentially added to isopropanol and mixed uniformly to obtain solution B.
  • the mass ratio of polyaniline and silicon oxide being 1:33
  • the silicon oxide and the solution B were mixed and stirred uniformly to obtain a uniform system.
  • the uniform system was dried in a vacuum dryer at 120°C to remove the isopropanol. After crushing again, a coating layer is formed on the surface of the silicon oxide, and the coating layer includes lithium fluoride and polyaniline, wherein the mass of lithium fluoride accounts for 5% of the total mass of the coating layer.
  • the prepared silicon-based lithium storage material was applied to a button battery system and tested.
  • the specific test method was referred to in Example 1, and the performance parameters of the formed silicon-based lithium storage material were shown in Table 1.
  • the secondary battery made of the silicon-based lithium storage material formed by the preparation method of the silicon-based lithium storage material described in the examples of the present application shows high delithiation capacity, high first coulombic efficiency and good cycle. performance.
  • Example 1 Compared the cyclic voltammetry curves of Example 1 and Comparative Example 1 in the first week, the SEI generation potential of Example 1 was increased to about 0.35V. It can be seen that the highest lithium intercalation potential is significantly increased to 2.3V. Therefore, the silicon-based lithium storage materials of the embodiments of the present application can significantly improve the electrochemical behavior of the early lithium intercalation process.
  • example embodiments with reference to idealized example cross-sectional and/or plan and/or perspective views. Accordingly, variations from the shapes illustrated are foreseeable due to, for example, manufacturing techniques and/or tolerances. Thus, example embodiments should not be construed as limited to the shapes of regions illustrated herein, but are to include deviations in shapes that result, for example, from manufacturing. For example, an etched area shown as a rectangle will typically have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device nor to limit the scope of example embodiments.

Landscapes

  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Composite Materials (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Dispersion Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

本申请提供了一种硅基储锂材料及其制备方法，所述硅基储锂材料包括：内核，所述内核包括0～4价的硅元素；第一壳层，所述第一壳层包覆或者部分包覆所述内核，所述第一壳层包括氟碳化合物层，所述氟碳化合物层包括氟碳化合物。本申请技术方案的硅基储锂材料，能够改善所述硅基储锂材料作为锂离子二次电池活性物质在高温存储条件下的特性，同时提高二次电池的循环特性和初期充放电库伦效率。

Description

硅基储锂材料及其制备方法 技术领域
本申请涉及锂离子电池领域，尤其涉及一种硅基储锂材料及其制备方法。
背景技术
虽然硅基材料具有显著的储锂容量优势，但目前硅基材料的高温及安全特性还有待提高，因此目前的商业化应用仍然不多。固体界面电解质(SEI)膜在硅基材料中起着非常关键的作用，但是由于硅基材料的合金化反应所引起的体积膨胀和应力远高于现有商用石墨材料，这会导致其SEI膜不稳定而出现裂纹，进而导致锂枝晶生长。此外，未破碎的SEI自身性质也对硅基材料的整体性能产生影响。在高低温、高电流密度等极端情况下，锂电极表面自身在电解液中形成的SEI膜是不稳定的，其机械模量、离子导电率无法达到要求，从而导致锂电池的循环性能迅速下降。
目前，有研究公开了一种通过氟奎烷与锂硅合金反应形成人造SEI材料的制作方法。该方法由50nmSi出发，在200℃的条件下使纳米硅与锂箔反应生成Li xSi合金颗粒，然后转移至氟奎烷的环己烷溶液中搅拌，干燥后获得材料。此种方案存在以下缺陷：(1)纳米硅成本较高；(2)内核为Li xSi，具有较高的反应活性，虽然其表面增加了单一涂层，但其仍对湿度敏感(在10％的湿度下接触6小时即失20％以上克容量)，要求干燥的存 储条件且容易与潮湿空气反应燃烧；(3)由于活性原因，需要油系匀浆(PVDF+NMP)，制作成本高，环境不友好；(4)氟奎烷与锂硅合金反应后，所得颗粒发生显著团聚，表面SEI的裹附均匀性不佳。
还有研究公开了一种锂离子电池阳极SEI膜及其分段化成的制备方法，通过调节化成温度、电流密度、截止电压、烘烤压力、烘烤时间以及烘烤温度等参数，制备得到一种具有多层结构的锂离子电池阳极SEI膜。但是，这种方法需要预先将阴极片、阳极片以及隔离膜卷绕或者叠片组装成裸电芯，之后装入包装外壳中，烘烤后注入电解液，通过复杂的化成工序制成不同类别的SEI成分，不仅存在着化成、取出加压、高温化成、冷却、高温化成、冷却的复杂步骤，同时其完全依赖于外接电流、电位、环境温度的精准控制来调控SEI的生成，不仅对设备进度、操作工序要求较高，而且容易系统的极化而导致目标SEI成分偏离；而且该方法制成的材料SEI实际分布较难精准控制，不仅首次库伦效率由较大降低，而且对于循环性能的改善不明显；不同的正极、电解液、负极搭配方案，需要细致不同的化成程序，控制难度较高，普适性不佳，大批量生产的经济性不佳。
因此，需要提供一种新的硅基储锂材料及其制备方法。
发明内容
本申请提供一种新的硅基储锂材料及其制备方法，能够改善所述硅基储锂材料作为锂离子二次电池活性物质在高温存储条件下的特性，同时提高 二次电池的循环特性和初期充放电库伦效率。
本申请的一方面提供一种硅基储锂材料，包括：内核，所述内核包括0～4价的硅元素；第一壳层，所述第一壳层包覆或者部分包覆所述内核，所述第一壳层包括氟碳化合物层，所述氟碳化合物层包括氟碳化合物。
在本申请实施例中，所述第一壳层还包括碳材料层，所述碳材料层位于所述内核和所述氟碳化合物层之间，所述碳材料层包括碳材料。
在本申请实施例中，0＜N F/N C≤1.5，其中N F为所述第一壳层中氟元素的摩尔数，N C为所述第一壳层中碳元素的摩尔数。
在本申请实施例中，所述碳材料包括无定形碳或者石墨化碳中的至少一种。
在本申请实施例中，所述第一壳层的质量占所述硅基储锂材料总质量的0.5％～10％。
在本申请实施例中，所述第一壳层的厚度为1nm～50nm。
在本申请实施例中，所述内核还包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，其中0≤N R/N Si(0～4)≤1.5，N R为掺杂元素R的摩尔数，N Si(0～4)为0～4价的硅元素的摩尔数。
在本申请实施例中，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P及Be中的至少一种。
在本申请实施例中，所述的硅基储锂材料还包括：第二壳层，所述第二壳层包覆或者部分包覆所述第一壳层，所述第二壳层包括氟锂化合物。
在本申请实施例中，所述第二壳层的质量占所述硅基储锂材料总质量的0.1％～2％。
本申请的另一方面还提供一种硅基储锂材料的制备方法，包括：提供内 核材料，所述内核材料包括0～4价的硅元素；在所述内核材料表面沉积碳材料，形成碳材料层；将所述碳材料层进行氟化处理，使所述碳材料层全部或者部分转化成氟碳化合物层，形成第一壳层。
在本申请实施例中，采用含氟气体对所述碳材料层进行氟化处理，且0＜N F/N C≤1.5，其中N F为所述含氟气体中氟元素的摩尔数，N c为所述碳材料层中碳元素的摩尔数。
在本申请实施例中，所述含氟气体包括F 2，NF 3及ClF 3中的至少一种。
在本申请实施例中，所述氟化处理的温度为20℃～600℃。
在本申请实施例中，所述的硅基储锂材料的制备方法还包括：将包覆有第一壳层的内核材料置于锂溶液中；待所述包覆有第一壳层的内核材料吸附所述锂溶液后，去除所述锂溶液的溶剂；热处理，使所述锂溶液中的锂与所述内核材料反应，且所述第一壳层表面附着锂化合物；冷却至特定温度，对所述锂化合物进行氟化处理，使所述锂化合物转化成氟锂化合物，在所述第一壳层表面形成第二壳层。
在本申请实施例中，所述锂溶液的溶剂包括萘，蒽，四氢呋喃及N-甲基吡咯烷酮中的至少一种。
在本申请实施例中，所述热处理的温度为400℃～600℃。
在本申请实施例中，经所述热处理后，所述锂与所述内核材料反应生成锂硅酸盐，所述第一壳层表面附着的锂化合物包括氢氧化锂和碳酸锂中的至少一种。
在本申请实施例中，所述内核材料还包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，其中0≤N R/N Si(0～4)≤1.5，N R为掺杂元素R的摩尔数，N Si(0～4)为0～4价的硅元素的摩尔数。
在本申请实施例中，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P及Be中的至少一种。
在本申请实施例中，所述碳材料包括无定形碳或者石墨化碳中的至少一种。
本申请技术方案的硅基储锂材料，包括内核和第一壳层，所述第一壳层包覆或部分包覆所述第一壳层，所述第一壳层包括氟碳化合物，所述氟碳化合物在首周循环过程中会与锂发生反应，该反应的对锂电位(vs.Li +/Li)显著高于普通石墨材料，因而在组装成电池后，氟碳化合物会优先与电解液中的锂盐在高电位发生反应，能够较好的适应高电压体系。
在首周循环过程中，所述氟碳化合物与锂反应生成含氟的无机物附着在硅基储锂材料表层，所述含氟的无机物具有陶瓷性质，杨氏模量较高，不仅可有效改善高温循环过程中表层的副反应，而且可以保障在内核膨胀收缩后，仍有部分传导锂离子介质，从而效改善电池的高温特性；同时，还可以阻止大倍率充放电过程中，可能析锂而导致的杨氏模量较低的锂枝晶穿透风险，避免安全事故。
同时，所述氟碳化合物层具有较高的分子层间距和离子扩散率，从而有利于锂离子的嵌入与脱出，降低了材料的阻抗，有效地改善了电池的动力学和稳定性。
进一步地，所述第一壳层还包括碳材料层，所述碳材料层位于所述内核和氟碳化合物层之间，一方面可以避免碳氟化合物与内核直接接触；另一方面可以保障电导率，减小高倍率下的极化问题。
进一步地，所述第一壳层表面包覆或者部分包覆第二壳层，所述第二壳层包括氟锂化合物，所述第一壳层和所述第二壳层中的氟化成分不仅可以使硅 基储锂材料获得较高的首次库伦效率，还可以获得较好的水系匀浆稳定性，解决了现有的锂化技术容易在表层生成活性物质而难以匀浆的问题。
附图说明
以下附图详细描述了本申请中披露的示例性实施例。其中相同的附图标记在附图的若干视图中表示类似的结构。本领域的一般技术人员将理解这些实施例是非限制性的、示例性的实施例，附图仅用于说明和描述的目的，并不旨在限制本申请的范围，其他方式的实施例也可能同样的完成本申请中的发明意图。应当理解，附图未按比例绘制。其中：
图1为本申请实施例的一种硅基储锂材料的结构示意图；
图2为本申请实施例的另一种硅基储锂材料的结构示意图；
图3为本申请实施例的又一种硅基储锂材料的结构示意图；
图4为本申请实施例的另一种硅基储锂材料的结构示意图；
图5为本申请实施例的硅基储锂材料的制备方法获得的硅基储锂材料的XRD图谱；
图6为本申请实施例1和对比例1的首周电池循环伏安曲线；
图7为本申请实施例7的首周电池循环伏安曲线。
具体实施方式
以下描述提供了本申请的特定应用场景和要求，目的是使本领域技术人员能够制造和使用本申请中的内容。对于本领域技术人员来说，对所公开的实施例的各种局部修改是显而易见的，并且在不脱离本申请的精神和范围的情况下， 可以将这里定义的一般原理应用于其他实施例和应用。因此，本申请不限于所示的实施例，而是与权利要求一致的最宽范围。
下面结合实施例和附图对本发明技术方案进行详细说明。
参考图1，本申请实施例提供一种硅基储锂材料，所述硅基储锂材料包括：内核1，所述内核包括0～4价的硅元素；第一壳层2，所述第一壳层2包覆或者部分包覆所述内核1，所述第一壳层2包括氟碳化合物层21，所述氟碳化合物层21包括氟碳化合物。
在本申请的一些实施例中，所述0～4价的硅元素，可以是以单质态的硅存在，或者以硅氧化物(SiOx，0≤x≤2)存在，还可以是以硅酸盐(M ySiO 3，1≤y≤2；M为I，II，III主族元素，例如Li，Na，Mg，Ca或者Al等)的形式存在。进一步地，0≤N Si(1～4)/N Si(0)≤1，所述N Si(1～4)为化合价在1～4之间的硅的摩尔数，所述N Si(0)是指以单质形式存在，化合价为0的硅的摩尔数，N Si(1～4)/N Si(0)为化合价在1～4之间的硅与单质硅之间的摩尔比。所述N Si(1～4)/N Si(0)的值可以通过调整所述内核1中包含的硅、硅氧化硅以及硅酸盐之间的含量来实现。在一些实施例中，所述N Si(1～4)/N Si(0)的值例如为0，0.2，0.5，0.8或1等。
在本申请的一些实施例中，所述内核1中除了包括硅元素，还可以包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，例如，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P，Be中的至少一种。所述掺杂元素R在所述内核1中可以以原子态或离子态存在，所述掺杂元素R的原子之间可以相互结合形成离子态，例如所述掺杂元素可以存在于Mg单质，Ca单质或Al单质中，或者存在于金属氧化物、金属盐中，例如MgO，CaO，Mg 3(PO 4) 2等。所述掺杂元素R还可以与硅元素结合，形成硅氧化物、硅酸盐等，例如，MgSiO 3，CaSiO 3或Li 2SiO 3等。所述掺杂元素R具备接受电子 的能力，从而可以使材料呈中性，通过调控掺杂元素R的掺入量，可以改变电池整体循环性能和首次库伦效率。
在本申请实施例中，0≤N R/N Si(0～4)≤1.5，其中所述N R为掺杂元素R的摩尔数，N Si(0～4)为化合价在0～4价的硅元素的摩尔数，N R/N Si(0～4)为掺杂元素R与化合价在0～4价的硅元素之间的摩尔比。通过调节所述掺杂元素R与0～4价硅元素的添加比例，可以改变所述硅基储锂材料嵌入活性锂之后在高温存储条件下的特性并获得最佳结果。所述化合价在0～4价的硅元素和所述掺杂元素R在内核1中是均匀分布的，或者是大体上的均匀分布。
本申请实施例的硅基储锂材料还包括第一壳层2，所述第一壳层2部分包覆或者完全包覆所述内核1，依据所述硅基储锂材料的制作工艺不同，包覆程度也有所不同，图1示意性地表示出完全包覆的情形。所述第一壳层2不一定是图1所示的正圆环型包覆结构，只是大致实现内核1表面的第一壳层2的包覆厚度接近。所述第一壳层2的质量占所述硅基储锂材料总质量的0.5％～10％，例如为0.5％，1％，2％，3％，4％，5％，6％，7％，8％或者9％等。所述第一壳层2的厚度例如为1nm～50nm。
所述第一壳层2包括氟碳化合物层21，所述氟碳化合物层21包括氟碳化合物。所述第一壳层2的表面包覆氟碳化合物，使得在电池在首周循环过程中会发生定向反应：CF x+xLi→C+xLiF，该反应的对锂电位(vs.Li +/Li)显著高于普通石墨材料，因而在组装成电池后，氟碳化合物会优先与电解液中的锂盐在高电位发生反应，能够较好的适应高电压体系，在硅基储锂材料表层生成含氟的无机物，所述含氟的无机物具有陶瓷性质，杨氏模量较高，不仅可有效改善高温循环过程中表层的副反应，而且可以保障在内核1膨胀收缩后，仍有部分传导锂离子介质，从而效改善电池的高温特性；同时，还可以阻止大倍率 充放电过程中，可能析锂而导致的杨氏模量较低的锂枝晶穿透风险，避免安全事故。若内核表面不存在氟碳化合物时，则内核上的材料会在较低的电位反应，生成有机成分，例如ROCO 2Li、ROLi、(ROCO 2Li) 2等。
本申请实施例的硅基储锂材料具有在氟碳化合物层21表面定向生成氟化锂成分的优势，等同于调控了硅基储锂材料作为电极材料在电池首周循环过程中形成的SEI膜的成分，且由于原始层(氟碳化合物层21)具有较高的分子层间距，成膜后仍然具有较好的离子扩散通道，因而形成的是稳定而阻抗较小SEI膜，显著改善了材料的阻抗、循环和高温性能。
请参考图2，在本申请的一些实施例中，所述第一壳层2不仅包括氟碳化合物层21，还包括碳材料层22，所述碳材料层22位于所述内核1和所述氟碳化合物层21之间。
在所述第一壳层2中，0＜N F/N C≤1.5，所述N F为所述第一壳层2中氟元素的摩尔数，也即所述氟碳化合物层21中氟元素的摩尔数，所述N C为所述第一壳层2中碳元素的摩尔数，也即所述氟碳化合物层21和所述碳材料层22中的碳元素的总摩尔数，所述N F/N C为所述第一壳层2中氟元素与碳元素的摩尔比。使0＜N F/N C≤1.5，能够保证组装成扣式电池经首周循环后，在硅基储锂材料表面既包括有机SEI膜，也包括无机SEI膜。在靠近溶剂侧SEI膜成分中，以有机SEI膜为主，且符合条件0.3＜M 无机SEI膜/M 有机SEI膜＜2；而靠近涂层端以无机SEI膜为主，且符合条件1.5＜M 无机SEI膜/M 有机SEI膜＜7，其中M 无机SEI膜代表无机SEI膜的质量，M 有机SEI膜代表有机SEI膜的质量，M 无机SEI膜/M 有机SEI膜代表有机SEI膜与无机SEI膜的质量比。通过在0＜N F/N C≤1.5范围内调控氟元素与碳元素的摩尔比，进而可以将嵌锂材料端dQ/dV的最高电位调控至0.25V～2.5V，还能够改变SEI膜的成分和结构，从而显著改善硅基材料的高温和循环稳定性。
所述碳材料层22包括碳材料，所述碳材料包括无定形碳或者石墨化碳中的至少一种。在本申请的一些实施例中，所述碳材料层22包括无定形碳层或者石墨化碳层中的至少一种。也就是说，在所述第一壳层2表面可以包括无定形碳层或者石墨化碳层或者同时包括无定形碳层和石墨化碳层。例如，所述的无定形碳层直接包覆在所述第一壳层2表面，所述的石墨化碳层再包覆在所述无定形碳层表面。或者，所述石墨化碳层直接包覆在所述第一壳层2表面，所述无定形碳层再包覆在所述石墨化碳层表面。再或者，一层以上的无定形碳层和一层以上的石墨化碳层交替排布。本申请实施例所述的″包覆″可以是部分包覆，也可以是完全包覆，依据所述硅基储锂材料的制作工艺不同，所包覆程度也有所不同。
由于所述无定形碳层为疏松的无定型碳结构，在硅基储锂材料的嵌锂膨胀中起到缓冲作用，而石墨化碳层为高石墨化度的晶型碳结构，对硅基储锂材料的嵌锂膨胀起到一定的束缚作用，防止硅基储锂材料在脱嵌锂过程中碳材料层的开裂和活性物质的失活，因此，所述交替排布的无定形碳层和石墨化碳层能更好的调整所述硅基储锂材料的充放电性能，提高电池的循环寿命。
在所述氟碳化合物层21与内核1之间增加碳材料层22，不仅避免了碳氟化合物与内核1直接接触，而且还使所述第一壳层2同时兼具了氟化(氟碳化合物层21)和非氟化成分(碳材料层22)，氟化部分的氟碳化合物层21具有较高的分子层间距和离子扩散率，从而有利于锂离子的嵌入与脱出，降低了材料的阻抗，有效地改善了电池的动力学和稳定性；非氟化部分的碳材料层22保障了电导率，减小了高倍率下的极化问题。
参考图3和图4，在本申请的一些实施例中，所述硅基储锂材料还可以包括第二壳层3，所述第二壳层3包覆或者部分包覆所述第一壳层2，所述第 二壳层3包括氟锂化合物。所述第二壳层3的质量占所述硅基储锂材料总质量的0.1％～2％，例如为0.1％，0.2％，0.3％，0.5％，1％，1.5％或者2％。所述氟锂化合物例如为氟化锂。
所述第一壳层2和第二壳层3中的氟化成分不仅可以使硅基储锂材料获得较高的首次库伦效率，还可以获得较好的水系匀浆稳定性，较好的解决了现有的锂化技术容易在表层生成活性物质而难以匀浆的问题。
本申请实施例还提供一种硅基储锂材料的制备方法，包括：
步骤S1：提供内核材料，所述内核材料包括0～4价的硅元素；
在本申请实施例中，所述0～4价的硅元素，可以是以单质态的硅存在，例如为多晶硅；或者以硅的+4价氧化态的形式存在，例如为二氧化硅，包含二氧化硅的原料例如为石英，具体地，可以选择β-型石英。所述硅的+4价氧化态还可以是硅酸盐，例如通式为M ySiO 3的化合物，其中1≤y≤2，M为I，II，III主族元素，例如Li，Na，Mg，Ca或者Al等。或者，所述内核材料既包括单质态的硅又包括含硅的化合物。进一步地，0≤N Si(1～4)/N Si(0)≤1，所述N Si(1～4)为化合价在1～4之间的硅的摩尔数，所述N Si(0)是指以单质形式存在，化合价为0的硅的摩尔数，N Si(1～4)/N Si(0)为化合价在1～4之间的硅与单质硅之间的摩尔比。
所述内核材料还可以包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，例如，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P，Be中的至少一种。提供所述掺杂元素R的原料可以是金属单质Mg，也可以是金属的氧化物，金属的氢氧化物，或者金属盐等，例如MgO，CaO，Mg 3(PO 4) 2，MgSO 3，LiOH，Li 2CO 3，MgSiO 3，CaSiO 3或Li 2SiO 3等。
在一些实施例中，所述内核材料可以通过如下工艺制备：提供第一混合物，所述第一混合物至少包括硅的单质态、硅的+4价氧化态及掺杂元素R，例如 所述第一混合物可以包括多晶硅，β-型石英以及Li 2CO 3，或者所述第一混合物可以包括多晶硅，β-型石英以及LiOH，或者包括多晶硅，β-型石英以及MgCO 3，并调整所述第一混合物中各原料的组分比，使0≤N R/N Si(0～4)≤1.5，其中N R为掺杂元素R的摩尔数，N Si(0～4)为化合价在0～4之间的硅元素的摩尔数；然后，将所述第一混合物在非氧化性气体保护下，加热至熔融态后以5℃/S～30℃/S的降温速率降至室温，所述的非氧化性气体可以是惰性气体，例如氦气，氖气，氩气等气体，所述加热至熔融态的温度为1500℃～3000℃，例如2000℃，2500℃等；加热至熔融态后以5℃/S～30℃/S(℃/S：摄氏度/秒)的降温速率快速降至室温，所述快速降温过程可以使所得材料制成电池后具有最佳的循环性能；之后进行粉化处理，获得本申请实施例所述的内核材料。
进行步骤S2，在所述内核材料表面沉积碳材料，形成碳材料层。在一些实施例中，沉积碳材料的方法可以包括：
在非氧化性氛围中，使碳源物质通过预分解区，形成分解产物，其中，所述碳源物质包括气体碳源物质，蒸汽化碳源物质或者雾化碳源物质中的一种以上。
调控所述分解产物进入沉积包覆区反应腔的流动速度V G以及分解产物摩尔流速与所述内核材料的质量比Mc/M，使所述内核材料与所述分解产物在沉积包覆区发生沉积包覆反应，在所述内核材料表面形成碳材料层，所述碳材料层可以包括无定形碳层或者石墨化碳层或者包括无定形碳层和石墨化碳层的复合层，其中，0.01≤V G≤100，0.001≤Mc/M≤1，V G单位为m/min，M C单位为mol/min，以碳原子计，M为内核材料质量，单位kg。通过调控Mc/M的比值来控制碳材料层的厚度。
提供所述非氧化性氛围的气体例如包括氢气、氮气或者惰性气体中的任 意一种或者多种，用于作为所述预分解区反应的保护气、载气和稀释气体。所述气体碳源物质包括室温为气态的烃类和室温为气态的醛类，所述气体碳源物质包括甲烷、乙烷、乙烯、乙炔、丙烷、丙烯，所述蒸汽化碳源物质为室温为液体，在室温以上，但低于预分解区温度时为气态的含碳物质，所述蒸汽化碳源物质包括正己烷、乙醇、苯。所述雾化碳源物质为难以通过加热蒸发的物质，可以经过雾化装置制为小液滴的物质，例如温度低于预分解区时为液态的物质。所述雾化碳源物质包括聚乙烯、聚丙烯。
在本申请的一些实施例中，发生所述沉积包覆反应的过程中，还可以通入含氮物质，所述含氮物质包括NH 3、乙腈、苯胺或者丁胺中的一种或者多种。通入所述含氮物质，可以得到掺杂有氮原子的无定形碳层和/或石墨化碳层。所述掺杂有氮原子的无定形碳层和/或石墨化碳层可以进一步提高所述硅基储锂材料的充放电能力。
进行步骤S3，将所述碳材料层进行氟化处理，使所述碳材料层全部或着部分转化成氟碳化合物层，形成第一壳层。本申请实施例所述的氟化处理，可以是采用含氟气体与所述碳材料层的材料发生反应，使所述碳材料层的材料被全部或部分氟化成为氟碳化合物。所述含氟气体可以包括F 2，NF 3及ClF 3中的至少一种。
所述氟化处理可以在流化床反应炉、回转炉、立式移动床反应炉、隧道炉、分批炉或回转窑中的任意一种反应装置中进行。所述氟化处理的温度为20℃～600℃，例如20℃，50℃，100℃，150℃，200℃，300℃，400℃或者500℃等。
在本申请的一些实施例中，通过调控所述含氟气体中氟元素和所述碳材料层中碳元素之间的摩尔比，进而控制氟化的程度。若含氟气体中氟元素的摩尔 数(N F)与所述碳材料层中碳元素的摩尔数(N C)为等当量比，或者N F相对于N C过量时，则所述碳材料层中的所有碳元素均与所述含氟气体中的氟元素结合，形成氟碳化合物，也就是说，所述碳材料层全部转化成氟碳化合物层，也即形成的第一壳层为氟碳化合物层；若N F相对于N C为少量时，则所述含氟气体中的氟元素和所述碳材料层中的部分碳元素结合，形成氟碳化合物，也就是说，所述碳材料层中还有部分碳元素未参与反应，因此，仅有部分所述碳材料层转化成氟碳化合物层，还剩余有部分碳材料层未被氟化，形成的第一壳层包括氟化后的氟碳化合物层和未被氟化的碳材料层。由于所述含氟气体处理所述碳材料层时，氟元素是自所述碳材料层的表面逐渐进入所述碳材料层的内部，因此，所述碳材料层的表面先被氟化，然后依次向内进行氟化，所以，当N F相对于N C为少量时，氟化形成的氟碳化合物层位于未被氟化的碳材料层的表面，即未被氟化的碳材料层位于氟碳化合物层和内核材料之间。所述未被氟化的碳材料层具有隔离作用，避免了氟碳化合物层与所述内核材料直接接触。
由于氟碳化合物层的存在，使得硅基储锂材料用作电极材料后，电池在首周过程中发生如下定向反应：CF x+xLi→C+xLiF，因此靠近涂层端以无机SEI为主，硅基储锂材料表面靠近溶剂侧以有机SEI为主。进一步地，靠近溶剂侧，0.3＜M (含氟无机膜)/M (有机成分膜)＜2；靠近涂层测，1.5＜M (含氟无机膜)/M (有机成分膜)＜7时，电池的性能最佳，其中M (含氟无机膜)代表含氟无机膜的质量，M (有机成 分膜)代表有机成分膜的质量。在本申请的一些实施例中，可以通过调节所述含氟气体中氟元素的摩尔数(N F)与所述碳材料层中碳元素的摩尔数(N C)的比值来调节无机SEI与有机SEI的质量比，例如0＜N F/N C≤1.5。
在本申请的一些实施例中，对所述含氟气体中氟元素的摩尔数(N F)与所述碳材料层中碳元素的摩尔数(N C)的比值的调节，可以通过通入所述含氟气 体的量来控制。例如，在一定时间内，通过调节所述含氟气体的流量，进而调节所述含氟气体的量，或者，在固定的流量下，通过调节所述含氟气体的通入时间，来调节所述含氟气体的量。
在一些实施例中，所述第一壳层的质量，即氟化后的氟碳化合物层和未被氟化的碳材料层的总质量占所述硅基储锂材料总质量的0.5％～10％。
经过上述制备过程得到的硅基储锂材料在充放电过程中具有较好的界面稳定性。非必须的，为了进一步提高首次库伦效率，还可以进行以下步骤：
将包覆有第一壳层的内核材料置于锂溶液中。所述锂溶液的溶剂可以包括萘、蒽、四氢呋喃、N-甲基吡咯烷酮中的至少一种，或是其他可以分散锂的溶剂即可。
待所述覆盖有第一壳层的内核材料吸附所述锂溶液后，去除所述锂溶液的溶剂，去除溶剂的方法可以是常见的干燥法，例如可以采用真空干燥。吸附锂溶液的目的在于，使第一壳层表面吸附锂，锂对提高首次库伦效率具有至关重要的作用，吸附锂的量会直接影响首次库伦效率的提高效果，可以通过调节锂溶液的浓度或浸渍时间来控制吸附锂的量。
进行热处理，使所述锂溶液中的锂与所述内核材料反应，且所述第一壳层表面附着锂化合物。所述热处理的目的在于，使吸附的锂进入到内核材料表面，并与所述内核材料发生反应：SiOx+Li→LiSiOy，将内核材料中的硅氧化合物转化为不可逆型锂硅酸盐，从而提升了首次库伦效率。在一些实施例中，所述热处理的温度为400℃～600℃，例如400℃，500℃，550℃等。同时，所述第一壳层表面会发生如下反应：Li ++OH -→LiOH；2LiOH+CO 2→Li 2CO 3+H 2O，因此，所述第一壳层表面会形成锂化合物，所述锂化合物可能包括氢氧化锂和碳酸锂中的至少一种。
热处理后，冷却至特定温度，如冷却至室温，然后对所述锂化合物进行氟化处理。进行氟化处理时，可以将冷却至室温的材料浸渍于氢氟酸中，在浸渍的过程中，所述氢氟酸与所述锂化合物(LiOH、Li 2CO 3)发生反应：LiOH+HF→LiF+H 2O；Li 2CO 3+2HF→2LiF+CO 2↑+H 2O，使所述锂化合物转化成氟锂化合物，在所述第一壳层表面形成第二壳层。所述第二壳层的质量占所述硅基储锂材料总质量的0.1％～2％。
对本申请实施例所述方法形成的具有第一壳层(包括碳材料层和氟碳化合物层)和第二壳层的硅基储锂材料进行检测，结果如下：
图5为硅基储锂材料的XRD图谱。经XRD分析，在使用CuKα射线的X射线衍射测定时，衍射角2θ显示在26.5°～27.2°范围的归属于Li 2SiO 3的峰的高度A1、衍射角2θ显示在44.5°～45.0°范围的归属于LiF的峰的高度A2，并且满足如下条件：0＜A2/A1＜0.45。由于LiF的结晶度不宜过高，若LiF的结晶度较高时，形成的膜不致密，影响首次库伦效率的提高效果，故LiF的峰值不宜过强。
经X射线光电子能谱检测分析，C1s电子结合能在288.4±0.2Ev(C-F键)和283.5±0.2eV(无定形C-C键)处出现强度为I 288和I 283宽峰，其中0＜I 288/I 283＜0.3，说明形成的第一壳层中包括C-C键和C-F键，分别对应于硅基储锂材料中的碳材料和氟碳化合物；而F1s电子结合能在684-694eV出现至少2个峰，说明形成的硅基储锂材料中具有两种氟的化合物，对应于硅基储锂材料中的氟碳化合物和氟锂化合物。同时，根据XPS深度分析测定，当硅基储锂材料组装成扣电池经首周循环后，硅基储锂材料表面的无机SEI膜主要包括Li 2CO 3，LiOH，LiF，Li 2O，Li 2CO 3，有机SEI膜主要包含Li-O-C化合物，溶剂侧Li的XPS谱图在52-58eV区段。
经透射电子显微镜下的衍射环分析，表面碳-碳层间距在范围0.35～0.45nm之间至少包含两种，其中最大值-最小值＞0.05nm，说明形成的第一壳层包括至少两种碳-碳层间距，这是由于氟的电负性强，原子半径大，使得原始的碳-碳层间距偏离原始的范围，因此出现了至少两种碳-碳层间距。
本申请实施例的制备方法工艺简单，具有可量产性，制备的硅基储锂材料具有较好的动力学性能、高温和循环稳定性，所述硅基储锂材料包括第一壳层和第二壳层，且第一壳层和第二壳层均含有含氟成分，因此拥有较高的首次库伦效率，同时还具有较高的水系匀浆稳定性，解决了现有技术中因硅基储锂材料表面生成活性物质，导致难以匀浆的问题，避免了额外处理的工序，降低了成本。由本申请实施例的硅基储锂材料制成的电池体系可以显著减少或避免氟代碳酸乙烯酯的添加，不仅适用于正极匹配三元的电池体系，而且适用于钴酸锂高电压体系。
实施例1
提供内核材料，所述内核材料包括0～4价的硅元素；
在所述内核材料表面沉积无定形碳，形成碳材料层，所述无定形碳的质量占硅基储锂材料总质量的3％，记为Mc；
在100℃下，采用氟气对所述碳材料层进行氟化处理，使所述碳材料层部分转化成氟碳化合物层，形成第一壳层，且N F/N C＝0.05，其中N F为所述含氟气体中氟元素的摩尔数，N c为所述碳材料层中碳元素的摩尔数。
将制备的硅基储锂材料应用于扣电池体系，并进行以下测试：
25℃循环(0.1C)：0.1C充放循环，第50/100周可逆容量/初始充电(脱锂容量)；
45℃循环(0.1C)：0.1C充放循环，第50/100周可逆容量/初始充电(脱锂 容量)
倍率放电(嵌锂)：固定为0.1C充电(脱锂)，分别以0.5C，1.5C，3.0C，5.0C与0.1C充电(脱锂)容量比值；
倍率充电：固定为0.1C放电(嵌锂)，分别以0.5C，1.0C，3.0C，5.0C与0.1C放电(嵌锂)容量比值。
具体工艺数据以及形成的所述硅基储锂材料的性能参数参考表1所示。并测试了首周电池的循环伏安曲线，如图6所示。
实施例2～实施例6
具体工艺描述参考实施例1，具体工艺数据以及形成的所述硅基储锂材料的性能参数参考表1所示。
实施例7
提供内核材料，所述内核材料包括0～4价的硅元素；
在所述内核材料表面沉积无定形碳，形成碳材料层，所述无定形碳的质量占硅基储锂材料总质量的3％，记为Mc；
在100℃下，采用氟气对所述碳材料层进行氟化处理，使所述碳材料层部分转化成氟碳化合物层，形成第一壳层，且N F/N C＝0.1，其中N F为所述含氟气体中氟元素的摩尔数，N c为所述碳材料层中碳元素的摩尔数；
将包覆有第一壳层的内核材料置于锂的四氢呋喃溶液中；
待所述包覆有第一壳层的内核材料吸附锂的四氢呋喃溶液后，真空干燥去除所述四氢呋喃；
在400℃下，热处理使锂进入至内核材料并与内核材料反应，且在所述第一壳层表面附着锂化合物；
冷却至室温，将热处理后的材料浸入氢氟酸溶液中进行氟化处理，使所 述锂化合物转化成氟锂化合物，在所述第一壳层表面形成第二壳层，其中所述氟锂化合物的质量占硅基储锂材料总质量的0.2％，记为M LiF。
将制备的硅基储锂材料应用于扣电池体系，并进行测试，具体测试方法参考实施例1，具体工艺数据以及形成的所述硅基储锂材料的性能参数参考表1所示。并测试了首周电池循环伏安曲线，如图7所示。
对比例1
提供内核材料，所述内核材料包括0～4价的硅元素；
在所述内核材料表面沉积无定形碳，形成碳材料层，所述无定形碳的质量占硅基储锂材料总质量的3％，记为Mc。
将制备的硅基储锂材料应用于扣电池体系，并进行测试，具体测试方法参考实施例1，具体工艺数据以及形成的所述硅基储锂材料的性能参数参考表1所示。并测试了首周电池的循环伏安曲线，如图6所示。
对比例2～对比例6
具体工艺描述参考对比例1，具体工艺数据以及形成的所述硅基储锂材料的性能参数参考表1所示。
对比例7
按氟化锂与异丙醇的质量比为1∶10，将氟化锂溶解于异丙醇，获得溶液A。然后按N F/N C＝0.05的计量比，将对比例1制备的材料与溶液A混合，获得均匀体系，将该均匀体系在120℃的真空干燥机中干燥，去除异丙醇。
将制备的硅基储锂材料应用于扣电池体系，并进行测试，具体测试方法参考实施例1，形成的所述硅基储锂材料的性能参数参考表1所示。
对比例8
按氟化锂、聚苯胺及异丙醇的质量比为1∶19∶120，将氟化锂和聚苯胺依 次加入异丙醇中混合均匀，获得溶液B。按聚苯胺与氧化硅的质量比为1∶33，将氧化硅与溶液B混合并搅拌均匀，获得均匀体系，将该均匀体系在120℃的真空干燥机中干燥，去除异丙醇，所得物料经过再次粉碎，在所述氧化硅表面形成包覆层，所述包覆层包括氟化锂和聚苯胺，其中氟化锂的质量占所述包覆层总质量的5％。
将制备的硅基储锂材料应用于扣电池体系，并进行测试，具体测试方法参考实施例1，形成的所述硅基储锂材料的性能参数参考表1所示。
Figure PCTCN2020114849-appb-000001
由表1可知，采用本申请实施例所述的硅基储锂材料的制备方法形成的硅基储锂材料制成的二次电池，表现出高脱锂容量、高首次库伦效率和良好的循环性能。
参考图6和图7，对比实施例1和对比例1的首周电池循环伏安曲线，实施例1的SEI生成电位提高至约0.35V，根据实施例7的首周电池循环伏安曲线可以看到，最高嵌锂电位显著提升至2.3V，因此，本申请实施例的硅基储锂材料能够明显改善前期嵌锂过程的电化学行为。
综上所述，在阅读本申请内容之后，本领域技术人员可以明白，前述申请内容可以仅以示例的方式呈现，并且可以不是限制性的。尽管这里没有明确说 明，本领域技术人员可以理解本申请意图囊括对实施例的各种合理改变，改进和修改。这些改变，改进和修改都在本申请的示例性实施例的精神和范围内。
应当理解，本实施例使用的术语″和/或″包括相关联的列出项目中的一个或多个的任意或全部组合。应当理解，当一个元件被称作″连接″或″耦接″至另一个元件时，其可以直接地连接或耦接至另一个元件，或者也可以存在中间元件。
类似地，应当理解，当诸如层、区域或衬底之类的元件被称作在另一个元件″上″时，其可以直接在另一个元件上，或者也可以存在中间元件。与之相反，术语″直接地″表示没有中间元件。还应当理解，术语″包含″、″包含着″、″包括″或者″包括着″，在本申请文件中使用时，指明存在所记载的特征、整体、步骤、操作、元件和/或组件，但并不排除存在或附加一个或多个其他特征、整体、步骤、操作、元件、组件和/或它们的组。
还应当理解，尽管术语第一、第二、第三等可以在此用于描述各种元件，但是这些元件不应当被这些术语所限制。这些术语仅用于将一个元件与另一个元件区分开。因此，在没有脱离本申请的教导的情况下，在一些实施例中的第一元件在其他实施例中可以被称为第二元件。相同的参考标号或相同的参考标记符在整个说明书中表示相同的元件。
此外，本申请说明书通过参考理想化的示例性截面图和/或平面图和/或立体图来描述示例性实施例。因此，由于例如制造技术和/或容差导致的与图示的形状的不同是可预见的。因此，不应当将示例性实施例解释为限于在此所示出的区域的形状，而是应当包括由例如制造所导致的形状中的偏差。例如，被示出为矩形的蚀刻区域通常会具有圆形的或弯曲的特征。因此，在图中示出的区域实质上是示意性的，其形状不是为了示出器件的区域的实际形状也不是为了限 制示例性实施例的范围。

Claims (22)

  1. 一种硅基储锂材料，其特征在于，包括：
    内核，所述内核包括0～4价的硅元素；
    第一壳层，所述第一壳层包覆或者部分包覆所述内核，所述第一壳层包括氟碳化合物层，所述氟碳化合物层包括氟碳化合物。
  2. 根据权利要求1所述的硅基储锂材料，其特征在于，所述第一壳层还包括碳材料层，所述碳材料层位于所述内核和所述氟碳化合物层之间，所述碳材料层包括碳材料。
  3. 根据权利要求2所述的硅基储锂材料，其特征在于，0＜N F/N C≤1.5，其中N F为所述第一壳层中氟元素的摩尔数，N C为所述第一壳层中碳元素的摩尔数。
  4. 根据权利要求3所述的硅基储锂材料，其特征在于，所述碳材料包括无定形碳或者石墨化碳中的至少一种。
  5. 根据权利要求1所述的硅基储锂材料，其特征在于，所述第一壳层的质量占所述硅基储锂材料总质量的0.5％～10％。
  6. 根据权利要求1所述的硅基储锂材料，其特征在于，所述第一壳层的厚度为1nm～50nm。
  7. 根据权利要求1所述的硅基储锂材料，其特征在于，所述内核还包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，其中0≤N R/N Si(0～4) ≤1.5，N R为掺杂元素R的摩尔数，N Si(0～4)为0～4价的硅元素的摩尔数。
  8. 根据权利要求7所述的硅基储锂材料，其特征在于，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P及Be中的至少一种。
  9. 根据权利要求1所述的硅基储锂材料，其特征在于，还包括：第二壳层，所述第二壳层包覆或者部分包覆所述第一壳层，所述第二壳层包括氟锂化合物。
  10. 根据权利要求9所述的硅基储锂材料，其特征在于，所述第二壳层的质量占所述硅基储锂材料总质量的0.1％～2％。
  11. 一种硅基储锂材料的制备方法，其特征在于，包括：
    提供内核材料，所述内核材料包括0～4价的硅元素；
    在所述内核材料表面沉积碳材料，形成碳材料层；
    将所述碳材料层进行氟化处理，使所述碳材料层全部或者部分转化成氟碳化合物层，形成第一壳层。
  12. 根据权利要求11所述的硅基储锂材料的制备方法，其特征在于，采用含氟气体对所述碳材料层进行氟化处理，且0＜N F/N C≤1.5，其中N F为所述含氟气体中氟元素的摩尔数，N c为所述碳材料层中碳元素的摩尔数。
  13. 根据权利要求12所述的硅基储锂材料的制备方法，其特征在于，所述含 氟气体包括F 2，NF 3及ClF 3中的至少一种。
  14. 根据权利要求12所述的硅基储锂材料的制备方法，其特征在于，所述氟化处理的温度为20℃～600℃。
  15. 根据权利要求11所述的硅基储锂材料的制备方法，其特征在于，还包括：
    将包覆有第一壳层的内核材料置于锂溶液中；
    待所述包覆有第一壳层的内核材料吸附所述锂溶液后，去除所述锂溶液的溶剂；
    热处理，使所述锂溶液中的锂与所述内核材料反应，且所述第一壳层表面附着锂化合物；
    冷却至特定温度，对所述锂化合物进行氟化处理，使所述锂化合物转化成氟锂化合物，在所述第一壳层表面形成第二壳层。
  16. 根据权利要求15所述的硅基储锂材料的制备方法，其特征在于，所述锂溶液的溶剂包括萘，蒽，四氢呋喃及N-甲基吡咯烷酮中的至少一种。
  17. 根据权利要求15所述的硅基储锂材料的制备方法，其特征在于，所述热处理的温度为400℃～600℃。
  18. 根据权利要求15所述的硅基储锂材料的制备方法，其特征在于，经所述热处理后，所述锂与所述内核材料反应生成锂硅酸盐，所述第一壳层表面附着的锂化合物包括氢氧化锂和碳酸锂中的至少一种。
  19. 根据权利要求11所述的硅基储锂材料的制备方法，其特征在于，所述内核材料还包括掺杂元素R，所述掺杂元素R包括I～VI主族元素中的至少一种，其中0≤N R/N Si(0～4)≤1.5，N R为掺杂元素R的摩尔数，N Si(0～4)为0～4价的硅元素的摩尔数。
  20. 根据权利要求19所述的硅基储锂材料的制备方法，其特征在于，所述掺杂元素R包括O，N，C，Li，Mg，Ca，Al，P及Be中的至少一种。
  21. 根据权利要求11所述的硅基储锂材料的制备方法，其特征在于，所述碳材料包括无定形碳或者石墨化碳中的至少一种。
  22. 根据权利要求11所述的硅基储锂材料的制备方法，其特征在于，所述第一壳层的质量占所述硅基储锂材料总质量的0.5％～10％，所述第二壳层的质量占所述硅基储锂材料总质量的0.1％～2％。
PCT/CN2020/114849 2020-09-11 2020-09-11 硅基储锂材料及其制备方法 WO2022052054A1 (zh)

Priority Applications (4)

Application Number Priority Date Filing Date Title
PCT/CN2020/114849 WO2022052054A1 (zh) 2020-09-11 2020-09-11 硅基储锂材料及其制备方法
EP20952842.1A EP4231382A1 (en) 2020-09-11 2020-09-11 Silicon-based lithium storage material and preparation method therefor
US18/044,953 US20230361279A1 (en) 2020-09-11 2020-09-11 A silicon-based lithium storage material and a preparation method thereof
CN202080001969.4A CN112219295B (zh) 2020-09-11 2020-09-11 硅基储锂材料及其制备方法

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2020/114849 WO2022052054A1 (zh) 2020-09-11 2020-09-11 硅基储锂材料及其制备方法

Publications (1)

Publication Number Publication Date
WO2022052054A1 true WO2022052054A1 (zh) 2022-03-17

Family

ID=74067965

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2020/114849 WO2022052054A1 (zh) 2020-09-11 2020-09-11 硅基储锂材料及其制备方法

Country Status (4)

Country Link
US (1) US20230361279A1 (zh)
EP (1) EP4231382A1 (zh)
CN (1) CN112219295B (zh)
WO (1) WO2022052054A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116454393A (zh) * 2023-06-16 2023-07-18 蔚来电池科技(安徽)有限公司 二次电池和装置

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113782718B (zh) * 2021-08-30 2023-02-03 上海空间电源研究所 一种高电压锂离子电池材料、锂离子电池及其制备方法
KR102630914B1 (ko) * 2021-10-27 2024-01-29 컨템포러리 엠퍼렉스 테크놀로지 씨오., 리미티드 개질 실리콘재 및 제조 방법, 음극재, 음극판, 이차전지, 전지모듈, 전지팩 및 전기기기
WO2023245651A1 (zh) * 2022-06-24 2023-12-28 上海杉杉科技有限公司 硅基储锂材料及其制备方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005108724A (ja) * 2003-09-30 2005-04-21 Sanyo Electric Co Ltd 非水電解質二次電池
CN109167031A (zh) * 2018-08-21 2019-01-08 浙江大学 一种纳米硅碳复合材料及其制备方法和应用
CN109167032A (zh) * 2018-08-21 2019-01-08 浙江大学 一种纳米硅基复合材料及其制备方法和应用
CN109728259A (zh) * 2017-10-30 2019-05-07 华为技术有限公司 一种硅基复合负极材料及其制备方法和储能器件
CN110800142A (zh) * 2017-12-08 2020-02-14 株式会社Lg化学 锂二次电池用负极活性材料及其制备方法
CN110828812A (zh) * 2019-10-29 2020-02-21 宁德新能源科技有限公司 负极材料、包括其的负极及负极的制备方法
CN111149242A (zh) * 2019-12-30 2020-05-12 上海杉杉科技有限公司 硅基储锂材料及其制备方法
CN111554902A (zh) * 2020-05-12 2020-08-18 宁德新能源科技有限公司 负极材料、负极极片、电化学装置和电子装置

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109119617B (zh) * 2018-08-30 2021-08-27 华为技术有限公司 一种硅基复合负极材料及其制备方法和储能器件

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005108724A (ja) * 2003-09-30 2005-04-21 Sanyo Electric Co Ltd 非水電解質二次電池
CN109728259A (zh) * 2017-10-30 2019-05-07 华为技术有限公司 一种硅基复合负极材料及其制备方法和储能器件
CN110800142A (zh) * 2017-12-08 2020-02-14 株式会社Lg化学 锂二次电池用负极活性材料及其制备方法
CN109167031A (zh) * 2018-08-21 2019-01-08 浙江大学 一种纳米硅碳复合材料及其制备方法和应用
CN109167032A (zh) * 2018-08-21 2019-01-08 浙江大学 一种纳米硅基复合材料及其制备方法和应用
CN110828812A (zh) * 2019-10-29 2020-02-21 宁德新能源科技有限公司 负极材料、包括其的负极及负极的制备方法
CN111149242A (zh) * 2019-12-30 2020-05-12 上海杉杉科技有限公司 硅基储锂材料及其制备方法
CN111554902A (zh) * 2020-05-12 2020-08-18 宁德新能源科技有限公司 负极材料、负极极片、电化学装置和电子装置

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116454393A (zh) * 2023-06-16 2023-07-18 蔚来电池科技(安徽)有限公司 二次电池和装置
CN116454393B (zh) * 2023-06-16 2023-09-05 蔚来电池科技(安徽)有限公司 二次电池和装置

Also Published As

Publication number Publication date
EP4231382A1 (en) 2023-08-23
US20230361279A1 (en) 2023-11-09
CN112219295B (zh) 2022-11-22
CN112219295A (zh) 2021-01-12

Similar Documents

Publication Publication Date Title
WO2022052054A1 (zh) 硅基储锂材料及其制备方法
KR102617731B1 (ko) 실리콘 함유 복합체, 그 제조방법, 이를 이용한 탄소 복합체, 이를 포함한 전극, 리튬 전지 및 전자소자
JP7483297B2 (ja) 多孔性シリコン含有複合体、それを利用した炭素複合体、それを含んだ、電極、リチウム電池及び電子素子
US6783890B2 (en) Positive active material for rechargeable lithium battery and method of preparing same
JP6138960B2 (ja) 負極活物質及びこの製造方法
TWI501456B (zh) Non-aqueous electrolyte battery negative electrode material and non-aqueous electrolyte battery anode material manufacturing method and lithium-ion battery
JP7330252B2 (ja) ヨーク－シェル構造の粒子、その製造方法、及びこれを含むリチウム二次電池
KR100674015B1 (ko) 수명특성이 우수한 리튬 2 차 전지의 양극 활물질, 이의 제조 방법, 및 이를 포함하는 리튬 2차 전지
JP2022518585A (ja) シリコン複合物負極材料、その調製方法及びリチウムイオン電池
KR101981609B1 (ko) 리튬 이차전지용 음극활물질 및 그 제조방법
KR20180056395A (ko) 다공성 실리콘 복합체 클러스터 구조체, 이를 포함한 탄소 복합체, 그 제조방법, 이를 포함한 전극, 및 리튬 전지, 소자
KR20100136073A (ko) 리튬 이차 전지용 음극 활물질, 이의 제조 방법 및 리튬 이차 전지
KR20170036637A (ko) 리튬 이차전지용 음극활물질 및 그 제조방법
KR20190091411A (ko) 실리콘 함유 구조체, 그 제조방법, 이를 이용한 탄소 복합체, 이를 포함한 전극, 리튬 전지, 및 소자
US10084183B2 (en) Silicon oxide-carbon composite and method of manufacturing the same
KR20210035634A (ko) 탄소 코팅층을 포함하는 다공성 실리콘 복합체, 이의 제조방법 및 이를 포함하는 리튬이차전지
CN116565174A (zh) 一种硅碳复合材料、制备方法、硅基负极及锂离子电池
KR102308691B1 (ko) 비수전해질 이차전지용 음극재, 이의 제조 방법 및 이를 포함하는 비수전해질 이차전지
JP2000231933A (ja) リチウムイオン二次電池
CN116259755A (zh) 二次电池用负极活性物质及其制备方法
CN115241436A (zh) 高首效锂掺杂硅氧化物复合负极材料及其制备方法
WO2020138629A1 (ko) 복합 음극활물질, 이의 제조 방법, 및 이를 포함한 음극을 구비한 리튬 이차 전지
Zhu et al. MnO 2 nanowires as precursor synthesis of lithium-rich cathode material with enhanced electrochemical performances
WO2024142644A1 (ja) 複合体粒子、その製造方法およびその用途
KR102318864B1 (ko) 비수전해질 이차전지용 음극재, 이의 제조 방법 및 이를 포함하는 비수전해질 이차전지

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20952842

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2020952842

Country of ref document: EP

Effective date: 20230411