WO2019218779A1 - Modified silicon-based anode material and preparation method therefor, and lithium-ion battery - Google Patents

Modified silicon-based anode material and preparation method therefor, and lithium-ion battery Download PDF

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WO2019218779A1
WO2019218779A1 PCT/CN2019/080139 CN2019080139W WO2019218779A1 WO 2019218779 A1 WO2019218779 A1 WO 2019218779A1 CN 2019080139 W CN2019080139 W CN 2019080139W WO 2019218779 A1 WO2019218779 A1 WO 2019218779A1
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silicon
negative electrode
electrode material
modified
based negative
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PCT/CN2019/080139
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French (fr)
Chinese (zh)
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张传健
李阳兴
刘辰光
王平华
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华为技术有限公司
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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
    • 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
    • H01M4/36—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
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • 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 technical field of lithium ion batteries, in particular to a modified silicon-based anode material, a preparation method thereof and a lithium ion battery.
  • Lithium-ion batteries have been widely used in consumer electronics, mobile terminals, and communication energy storage due to their high energy density and power density, small size, high security, and environmental friendliness.
  • mobile terminal devices such as smart phones, with the gradual strengthening of their functions and the increasing frequency of use, consumers are increasingly demanding long battery life and fast charging.
  • the current process of lithium-ion batteries has reached the limit, and further improvement in performance depends on the development and optimization of materials.
  • the anode material is one of the most critical materials for improving the performance of lithium-ion batteries.
  • the theoretical specific capacity of silicon materials is 4200 mAh/g, which is more than 10 times that of graphite, and it is also environmentally friendly and has abundant reserves. It has long been considered as a negative electrode material for the next generation of high energy density lithium ion batteries, which can increase the energy density of the cells.
  • the shortcomings of the silicon anode material are also quite obvious, for example: (1) The silicon anode material will produce a severe volume expansion (100% to 300%) during the lithium ion intercalation and deintercalation process, resulting in a large interior inside the material.
  • the lithium intercalation process is an alloying reaction
  • graphite is a conductor.
  • the lithium intercalation process is an insertion and deintercalation reaction, which causes the desorption process of lithium ions in silicon to be slower than graphite and irreversible, further reducing its first coulombic efficiency.
  • the silicon anode material has poor compatibility between the surface group and the organic electrolyte, that is, it does not match the organic electrolyte, the electrode interface has a long infiltration time and the uniformity of the infiltration is poor, and it is easy to be in the battery cycle.
  • the SEI film is unevenly grown, which eventually causes capacity decay.
  • the industry generally performs carbon coating on the surface of the silicon anode material, and establishes a protective interface between the silicon anode material and the organic electrolyte, which can relieve volume expansion and improve conductivity to some extent, but There is still a problem of mismatch with the electrolyte, and the carbon coating layer is usually uneven in thickness due to the process limitation. During the subsequent battery cycle, the uneven coating further aggravates the uneven growth of the SEI film to cause capacity degradation. Therefore, it is necessary to develop a modified silicon-based anode material which can uniformly grow an SEI film during battery cycling and has good ionic conductivity.
  • the first aspect of the embodiments of the present invention provides a modified silicon-based anode material, which can uniformly grow an SEI film during battery cycling, and has good ionic conductivity to solve the existing silicon-based anode material. It is easy to cause uneven growth of SEI film during battery cycling, and finally cause capacity attenuation, and the poor ion conductivity of silicon-based anode material leads to the problem of low efficiency of the first coulomb.
  • a first aspect of the embodiments of the present invention provides a modified silicon-based anode material, comprising a silicon-based anode material and a modified layer disposed on a surface of the silicon-based anode material, the modified layer comprising a sulfonic acid-containing layer a silane coupling agent, the sulfonic acid group-containing silane coupling agent comprising a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, the sulfonic acid group being attached to the non-hydrolyzable group At the end of the hydrolyzable group, the sulfonic acid group-containing silane coupling agent forms a chemical bond with the silicon-based negative electrode material through the hydrolyzable group.
  • the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3, -OC 2 H 4 OCH 3 , -OSi (CH 3) any one of the 3, -OOCCH 3, said at least one hydrolyzable group formed by the hydrolysis of chemical bonding of the silicon negative electrode material, the
  • the non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
  • the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
  • the silicon-based anode material is a particle, and the modified layer is coated on the surface of the silicon-based anode material to form a core-shell structure.
  • the core is the silicon-based anode material
  • the shell is the modified Sex layer.
  • the silicon-based anode material is a film, the silicon-based anode material is attached to a substrate, and the modified layer is coated on the surface of the silicon-based anode material.
  • the silicon alloy includes one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
  • the modified layer has a thickness of 0.1 nm to 20 nm.
  • the quality of the modified layer is from 0.01% to 10% by mass of the silicon-based negative electrode material.
  • the sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
  • the modified silicon-based negative electrode material provided by the first aspect of the present invention has a uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a double parent structure, which can significantly improve the surface of the inorganic silicon negative electrode and The compatibility between the organic electrolytes can make the SEI film grow evenly, prevent the electrolyte from decomposing continuously on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions, and improve cycle life. At the same time, lithium intercalation reaction occurs in the battery.
  • the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance and circulation of the silicon negative electrode. stability.
  • a second aspect of the present invention provides a method for preparing a modified silicon-based anode material, comprising the following steps:
  • the silicon-based anode material when the silicon-based anode material is a pellet, the silicon-based anode material is uniformly mixed with a sulfonic acid group-containing silane coupling agent, and is subjected to a reflow treatment to form a coating on the silicon-based anode. a modified layer on the surface of the material to obtain a modified silicon-based anode material;
  • the silicon-based negative electrode material is a thin film
  • the silicon-based negative electrode material is attached to a substrate, and the silicon-based negative electrode material is infiltrated or coated with a sulfonic acid group-containing silane coupling agent to form a package.
  • a modified layer covering the surface of the silicon-based anode material to obtain a modified silicon-based anode material
  • the sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, and the sulfonic acid group is attached to an end of the non-hydrolyzable group.
  • the sulfonic acid group-containing silane coupling agent is chemically bonded to the silicon-based negative electrode material through the hydrolyzable group to obtain the modified layer.
  • the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 , -OC 2 Any one of H 4 OCH 3 , -OSi(CH 3 ) 3 , and -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis, the non-hydrolyzable group Any one selected from the group consisting of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
  • the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
  • the modified layer is coated on the surface of the silicon-based negative electrode material to form a core-shell structure, wherein the core-shell structure is a silicon-based negative electrode material, and the shell is a Said modified layer.
  • the modified layer is coated on the surface of the silicon-based negative electrode material.
  • the silicon alloy includes one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
  • the modified layer has a thickness of 0.1 nm to 20 nm.
  • the quality of the modified layer is from 0.01% to 10% by mass of the silicon-based negative electrode material.
  • the sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
  • the silicon-based negative electrode material is vacuum dried prior to the reflow, wetting or coating treatment, and the vacuum drying temperature is 60 ° C to 80 ° C for 4-8 hours.
  • the vacuum drying temperature is 60 ° C - 80 ° C, The time is 4-8 hours.
  • the preparation method provided by the second aspect of the embodiment of the invention has a simple process, and a modified silicon-based anode material with high consistency of the modified layer can be obtained.
  • a third aspect of the present invention provides a lithium ion battery including a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode, the negative electrode including the first aspect of the present invention.
  • Modified silicon-based anode material Modified silicon-based anode material.
  • the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film.
  • the lithium ion battery provided by the third aspect of the embodiment of the invention has excellent cycle performance and high efficiency for the first time.
  • FIG. 1 is a schematic diagram of molecular bonding of a modified layer of a modified silicon-based anode material according to an embodiment of the present invention
  • FIG. 2 is a schematic view showing the formation of an SEI film in a modified silicon-based anode material in the process of lithium insertion reaction according to an embodiment of the present invention
  • FIG. 3 is a schematic structural view of a modified silicon-based anode material according to an embodiment of the present invention.
  • FIG. 4 is a schematic structural view of a modified silicon-based anode material according to another embodiment of the present invention.
  • silicon anode materials have attracted extensive attention as new anode materials, but the silicon anode materials themselves have the problems of volume expansion effect and low conductivity, and at the same time, as inorganic materials, there is also a mismatch with the organic electrolyte.
  • the electrode interface has a long infiltration time and poor uniformity of wetting, which is easy to cause uneven growth of the SEI film during battery cycling, and finally causes capacity attenuation. Meanwhile, the continuous growth of the SEI film on the surface of the silicon negative electrode reduces the conductivity of the electrode material and increases the interface. Impedance, affecting power performance.
  • the silicon anode material it is necessary to modify the silicon anode material to effectively protect the silicon anode material, prevent the electrolyte from continuously decomposing on the surface of the silicon anode, provide a stable solid-liquid interface, reduce side reactions, improve cycle life, and improve the electrode surface.
  • the ionic conductivity of the SEI film reduces the interface impedance and further enhances the power performance and cycle stability of the silicon negative electrode.
  • an embodiment of the present invention provides a modified silicon-based anode material, comprising a silicon-based anode material and a modified layer disposed on a surface of the silicon-based anode material, the modified layer comprising a sulfonic acid group-containing silane a coupling agent, the sulfonic acid group-containing silane coupling agent comprising a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, the sulfonic acid group being bonded to the non-hydrolyzable group
  • the sulfonic acid group-containing silane coupling agent forms a chemical bond with the silicon-based negative electrode material through the hydrolyzable group.
  • the modified silicon-based anode material provided by the embodiment of the invention is obtained by modifying a silicon-based anode material with a sulfonic acid group-containing silane coupling agent.
  • the sulfonic acid group-containing silane coupling agent is a parent group, Therefore, the inorganic silicon-based anode material and the organic electrolyte can have good compatibility, effectively improve the wettability of the silicon-based anode material, and make the growth of the SEI film more uniform, and the modified layer can prevent the electrolyte from continuously decomposing on the surface of the anode.
  • the sulfonic acid group will form lithium sulfonate during the lithium intercalation reaction, and lithium sulfonate is one of the constituent components of the SEI film, which can improve the ionic conductivity of the SEI film on the surface of the negative electrode. Reduce the interface impedance and further improve the power performance of the silicon negative electrode.
  • the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 And any one of -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis,
  • the non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group, and the sulfonic acid group is bonded to the non-hydrolyzable group. The end of the group.
  • the hydrolyzable group and the non-hydrolyzable group may also be other conventional groups constituting the
  • the structural formula of the sulfonic acid group-containing silane coupling agent is as shown in the formula (1):
  • X is the hydrolyzable group
  • R is a residue obtained by removing one hydrogen atom from the non-hydrolyzable group.
  • FIG. 1 a schematic diagram of molecular bonding of a modified layer of a modified silicon-based anode material provided by an embodiment of the present invention, wherein the sulfonic acid group-containing silane coupling agent is hydrolyzed by the hydrolyzable group
  • the silicon-based negative electrode material After forming a chemical bond with the silicon-based negative electrode material, the silicon-based negative electrode material finally forms a Si-O bond with the sulfonic acid group-containing silane coupling agent.
  • the silicon-based negative electrode material further includes other elements than silicon
  • the silicon-based negative electrode material and the sulfonic acid group-containing silane coupling agent may also constitute other forms of chemical bonding.
  • FIG. 2 a schematic diagram of the SEI film reinforcement formation in the modified silicon-based anode material provided by the embodiment of the present invention, in the process of lithium insertion reaction, the sulfonic acid group reacts with lithium ions to form a sulfonate.
  • Lithium acid and lithium sulfonate are one of the components of the SEI film, which improves the ionic conductivity of the SEI film on the surface of the negative electrode, thereby accelerating the lithium ion transport rate.
  • the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
  • the silicon alloy may include one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
  • the form of the silicon-based negative electrode material is not limited, and may be in the form of particles or a film.
  • the silicon-based negative electrode material is a particle, and the modified layer is coated on a surface of the silicon-based negative electrode material to form a core-shell structure.
  • the core is the silicon-based structure.
  • a negative electrode material, and the shell is the modified layer.
  • FIG. 3 it is a schematic structural view of a modified silicon-based anode material having a core-shell structure, in which 11 is a silicon-based anode material and 12 is a modified layer.
  • the particle size of the silicon-based anode material may be on the order of micrometers and nanometers, specifically 10 nm to 20 ⁇ m, more specifically, 100 nm to 500 nm, and 1 ⁇ m to 10 ⁇ m.
  • the silicon-based anode material is a film, the silicon-based anode material is attached to a substrate, and the modified layer is coated on the surface of the silicon-based anode material.
  • the modified layer covers only the upper surface of the silicon-based negative electrode material film, as shown in FIG. 4, and is a structural schematic diagram of a modified silicon-based negative electrode material in a thin film state, in which 20 is a substrate, 21 is a silicon-based anode material, and 22 is a modified layer.
  • the modified layer may also coat all surfaces of the silicon-based negative electrode material that are not in contact with the substrate.
  • the silicon-based negative electrode material film has a thickness of 2 ⁇ m to 8 ⁇ m, and further has a thickness of 4 ⁇ m.
  • the modified layer has a thickness of 0.1 nm to 20 nm. Further, the thickness of the modified layer may be 1 nm to 10 nm, 5 nm to 15 nm, and 1 nm to 5 nm.
  • the suitable thickness of the modified layer can effectively inhibit the expansion effect of the silicon-based anode material, prevent the electrolyte from decomposing continuously, and protect the electrode interface; the thickness of the modified layer is too thin to achieve the effect of protecting the electrode interface, and too thick will limit other SEI films.
  • the growth of the components affects the modification effect.
  • the quality of the modified layer is 0.01%-10% of the mass of the silicon-based negative electrode material.
  • the mass ratio of the modified layer is from 0.5% to 2%. The suitable mass ratio can make the modified layer better to improve the wettability of the negative electrode material, inhibit the continuous decomposition of the electrolyte, and improve the ionic conductivity of the negative electrode material, and maintain the high capacity of the negative electrode material.
  • the sulfonic acid group-containing silane coupling agent can be obtained by oxidizing a mercaptosilane coupling agent, and specifically, a mercapto group-containing silane coupling agent can be obtained by reacting with a common oxidizing agent.
  • the oxidizing agent may be, for example, hydrogen peroxide, sulfuric acid or the like.
  • the modified silicon-based anode material provided by the embodiment of the invention has uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a double parent structure, which can significantly improve the surface of the inorganic silicon anode and the organic electrolyte.
  • the compatibility between the SEI film can make the SEI film grow evenly, prevent the electrolyte from continuously decomposing on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions and improve cycle life.
  • the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance and cycle stability of the silicon negative electrode.
  • the embodiment of the invention further provides a method for preparing a modified silicon-based anode material, comprising the following steps:
  • the silicon-based anode material when the silicon-based anode material is a pellet, the silicon-based anode material is uniformly mixed with a sulfonic acid group-containing silane coupling agent, and is subjected to a reflow treatment to form a coating on the silicon-based anode. a modified layer on the surface of the material to obtain a modified silicon-based anode material;
  • the silicon-based negative electrode material is a thin film
  • the silicon-based negative electrode material is attached to a substrate, and the silicon-based negative electrode material is infiltrated or coated with a sulfonic acid group-containing silane coupling agent to form a package.
  • a modified layer covering the surface of the silicon-based anode material to obtain a modified silicon-based anode material
  • the sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, and the sulfonic acid group is attached to an end of the non-hydrolyzable group.
  • the sulfonic acid group-containing silane coupling agent is chemically bonded to the silicon-based negative electrode material through the hydrolyzable group to obtain the modified layer.
  • the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 And any one of -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis,
  • the non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
  • the hydrolyzable group and the non-hydrolyzable group may also be other conventional groups constituting the silane coupling agent, and are not limited to the above examples.
  • the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
  • the silicon alloy may include one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
  • the form of the silicon-based negative electrode material is not limited, and may be in the form of particles or a film.
  • the silicon-based negative electrode material is a particle, and the modified layer is coated on a surface of the silicon-based negative electrode material to form a core-shell structure.
  • the core is the silicon-based structure.
  • a negative electrode material, and the shell is the modified layer.
  • the particle diameter of the silicon-based anode material may be on the order of micrometers and nanometers, specifically 10 nm to 20 ⁇ m.
  • the silicon-based negative electrode material and the sulfonic acid group-containing silane coupling agent are uniformly mixed by ultrasonication, and an organic solvent may be added during the mixing process, and the organic solvent may be an alcohol solvent such as ethanol or methanol.
  • the alicyclic hydrocarbon solvent such as hexane or cyclohexanone may be an aromatic hydrocarbon solvent such as benzene or toluene.
  • the power and time of the ultrasonic wave may be set according to actual needs, for example, ultrasonic for 0.5 to 2 hours.
  • the reflux temperature of the reflux treatment is from 60 ° C to 100 ° C, and the reflux treatment time is from 4 to 8 hours. Further, the reflux temperature may be 80 ° C and the reflux treatment time is 6 hours.
  • the silicon-based negative electrode material is a film
  • the silicon-based negative electrode material is attached to a substrate
  • the modified layer covers the silicon-based negative electrode material and the substrate All surfaces in contact.
  • the specific operation of infiltrating or coating the silicon-based negative electrode material by using a sulfonic acid group-containing silane coupling agent is: adding a sulfonic acid group-containing silane coupling agent to an organic solvent a silane coupling agent solution containing a sulfonic acid group, immersing the silicon-based negative electrode material in the sulfonic acid group-containing silane coupling agent solution, or coupling the sulfonic acid group-containing silane A solution of the solution is coated on the surface of the silicon-based negative electrode material.
  • the organic solvent may be an alcohol solvent such as ethanol or methanol, an alicyclic hydrocarbon solvent such as cyclohexane or cyclohexanone, or an aromatic hydrocarbon solvent such as benzene or toluene.
  • the mass concentration of the sulfonic acid group-containing silane coupling agent solution may be controlled according to actual needs, and may specifically be, for example, 3% to 8%, more specifically 5%.
  • the thickness of the modified layer can be achieved by controlling parameters such as the length of the infiltration time, the concentration of the sulfonic acid group-containing silane coupling agent solution, and the coating thickness.
  • the substrate may be a copper foil
  • the coating method includes spin coating.
  • the modified layer obtained by the wetting method covers all the surfaces of the silicon-based negative electrode material film that are not in contact with the substrate; and the modified layer obtained by the coating method is usually only included.
  • the upper surface of the film of the silicon-based negative electrode material is coated.
  • the modified layer is coated by a spin coating method. Specifically, the substrate loaded with the silicon-based negative electrode material film is first heated in an oven. , placed in a spin coater, and then selected a certain concentration of sulfonic acid group-containing silane coupling agent solution for spin coating treatment, to modify the surface of the film to obtain a modified layer.
  • the modified layer has a thickness of 0.1 nm to 20 nm. Further, the thickness of the modified layer may be 1 nm to 10 nm, 5 nm to 15 nm, and 1 nm to 5 nm.
  • the suitable thickness of the modified layer can effectively inhibit the expansion effect of the silicon-based anode material, prevent the electrolyte from decomposing continuously, and protect the electrode interface; the thickness of the modified layer is too thin to achieve the effect of protecting the electrode interface, and too thick will limit other SEI films.
  • the growth of the components affects the modification effect.
  • the quality of the modified layer is 0.01%-10% of the mass of the silicon-based negative electrode material.
  • the mass ratio of the modified layer is from 0.5% to 2%. The suitable mass ratio can make the modified layer better to improve the wettability of the negative electrode material, inhibit the continuous decomposition of the electrolyte, and improve the ionic conductivity of the negative electrode material, and maintain the high capacity of the negative electrode material.
  • the sulfonic acid group-containing silane coupling agent can be obtained by oxidizing a mercaptosilane coupling agent, and specifically, a mercapto group-containing silane coupling agent can be obtained by reacting with a common oxidizing agent.
  • the oxidizing agent may be, for example, hydrogen peroxide, sulfuric acid or the like.
  • the sulfonic acid group-containing silane coupling agent is used in an amount of 0.01 to 10% by mass based on the mass of the silicon-based negative electrode material.
  • the silicon-based anode material is vacuum dried before the reflow, wetting or coating treatment, and the vacuum drying temperature is 60° C.-80° C., and the time is 4-8 hours. .
  • the vacuum drying treatment can reduce moisture in the silicon-based anode material and prevent excessive hydrolysis of the silane coupling agent on the surface thereof.
  • the modified silicon-based anode material is collected, and the modified silicon-based anode material is vacuum dried, and the vacuum drying temperature is 60 ° C - 80 ° C, time is 4-8 hours.
  • the vacuum drying here can make the sulfonic acid group-containing silane coupling agent better bonded to the surface of the silicon-based negative electrode material while performing the drying action.
  • the preparation method provided by the embodiment of the invention has simple process, and the prepared modified silicon-based anode material has a highly uniform modified layer on the surface thereof.
  • an embodiment of the present invention further provides a lithium ion battery including a positive electrode, a negative electrode, and a separator and an electrolyte solution between the positive electrode and the negative electrode, and the negative electrode is the modified silicon base provided by the above embodiment of the present invention.
  • Anode material is the lithium ion battery including a positive electrode, a negative electrode, and a separator and an electrolyte solution between the positive electrode and the negative electrode, and the negative electrode is the modified silicon base provided by the above embodiment of the present invention.
  • the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film.
  • the anode When the modified silicon-based anode material is a core-shell structure particle, the anode includes a cathode current collector and an anode active layer disposed on the anode current collector, the anode active layer including a modified silicon-based anode material, and a binder A binder, a conductive agent, and the like.
  • the modified silicon-based negative electrode material is a thin film, the modified silicon-based negative electrode material is attached to a substrate, and the substrate may serve as a current collector for a foil such as copper foil, and the modified silicon base The negative electrode material directly acts as a negative electrode.
  • the lithium ion battery provided by the embodiment of the invention has excellent cycle performance and high efficiency for the first time.
  • a preparation method of a modified silicon-based anode material comprises the following steps:
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 ⁇ m) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
  • a preparation method of a modified silicon-based anode material comprises the following steps:
  • the 3-sulfonic acid propyl triethoxysilane-modified silicon film prepared above is subjected to die-cutting to obtain a negative electrode tab having a size of 77 mm*58 mm;
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 ⁇ m) were formed into a square electric core by a lamination process, and the polymer was packaged, and the electrolyte was poured, and the electrolyte was 1 mol. /L LiPF 6 /EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
  • a preparation method of a modified silicon-based anode material (3-sulfonic acid methyldiethoxysilane-modified oxidized silicon oxide particles) comprises the following steps:
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 ⁇ m) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
  • a preparation method of a modified silicon-based anode material comprises the following steps:
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 ⁇ m) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
  • the preparation of the lithium ion battery differs from that of the first embodiment only in that the negative electrode active material used in the negative electrode piece is silicon nano particles, and the negative electrode piece is prepared by weighing: 7% by mass of polyacrylic acid lithium (PAALi). 3% conductive agent super P and 90% silicon nanoparticles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, and dried, cold pressed, and slit to obtain a negative electrode piece. .
  • PAALi polyacrylic acid lithium
  • the preparation of the lithium ion battery differs from that of the second embodiment only in that the preparation process of the negative electrode tab is as follows: a silicon foil having a copper foil as a substrate is die-cut to obtain a negative electrode tab having a size of 77 mm*58 mm.
  • the preparation of the lithium ion battery differs from that of the third embodiment only in that the negative electrode active material used in the negative electrode tab is oxysulfide particles, and the negative electrode tab is prepared by weighing 7% polyacrylic acid lithium (PAALi). 3% conductive agent super P and 90% oxypropylene nanoparticles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, dried, cold pressed, and slit. Negative pole piece.
  • PAALi polyacrylic acid lithium
  • the preparation of the lithium ion battery differs from that of the fourth embodiment only in that the negative electrode active material used in the negative electrode tab is silicon carbon particles, and the negative electrode tab is prepared by weighing 7% polyacrylic acid (PAALi). 3% conductive agent super P and 90% silicon carbon particles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, and dried, cold pressed, and slit to obtain a negative electrode piece. .
  • PAALi polyacrylic acid
  • the lithium ion batteries prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention were subjected to electrochemical performance tests: a 0.2 C charge/0.2 C discharge was used, and a charging voltage range was 0.05-2 V, and the first discharge capacity of the battery was tested. The first discharge efficiency and the first discharge capacity of the silicon-based negative electrode material were calculated, and the capacity value after 100 cycles was further recorded, and the capacity retention ratio was calculated.
  • the specific test results are shown in Table 1:
  • the battery samples prepared by using the modified silicon-based anode material provided by the embodiment of the present invention exhibit performance improvement in the first discharge capacity, the first efficiency, and the cycle performance, as compared with the comparative examples.
  • the reason is that the modified silicon-based anode material provided by the embodiment of the invention has a uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a parent structure, which can significantly improve the inorganic silicon anode.
  • the compatibility between the surface and the organic electrolyte can uniformly grow the SEI film, prevent the electrolyte from continuously decomposing on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions, and improve cycle life;
  • the sulfonic acid group can react with lithium ions to form lithium sulfonate groups as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance of the silicon negative electrode.
  • cycle stability can be used to uniformly grow the SEI film, prevent the electrolyte from continuously decomposing on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions, and improve cycle life;

Abstract

Embodiments of the present invention provide a modified silicon-based anode material, comprising a silicon-based anode material and a modified layer provided on the surface of the silicon-based anode material. The modified layer comprises a silane coupling agent containing a sulfonyl group. The silane coupling agent containing a sulfonyl group comprises a silicon atom and a non-hydrolyzable group and a hydrolysable group which are bonded to the silicon atom. The sulfonyl group is bonded to the terminal of the non-hydrolyzable group. The silane coupling agent containing a sulfonyl group is chemically bonded to the silicon-based anode material by means of the hydrolysable group. The modified silicon-based anode material can uniformly grow, on its surface, a SEI film during a battery cycling process, and can enable an anode to have good ionic conductivity, thereby improving the power property and cycling stability of the anode. The embodiments of the present invention also provide a preparation method for the modified silicon-based anode material and a lithium-ion battery.

Description

一种改性硅基负极材料及其制备方法和锂离子电池Modified silicon-based anode material, preparation method thereof and lithium ion battery 技术领域Technical field
本发明涉及锂离子电池技术领域，特别是涉及一种改性硅基负极材料及其制备方法和锂离子电池。The invention relates to the technical field of lithium ion batteries, in particular to a modified silicon-based anode material, a preparation method thereof and a lithium ion battery.
背景技术Background technique
锂离子电池由于具有较高的能量密度和功率密度、小体积、高安全、环境友好等优势，已经在消费电子、移动终端、通信储能等领域得到广泛应用。尤其是对于智慧手机等移动终端设备，随着其功能的逐步强大和使用频率的提高，消费者对于长续航和快充的需求越来越强烈。然而目前锂离子电池的制程工艺已经达到极限，想要进一步获得性能的提高只能依靠材料的开发和优化。Lithium-ion batteries have been widely used in consumer electronics, mobile terminals, and communication energy storage due to their high energy density and power density, small size, high security, and environmental friendliness. Especially for mobile terminal devices such as smart phones, with the gradual strengthening of their functions and the increasing frequency of use, consumers are increasingly demanding long battery life and fast charging. However, the current process of lithium-ion batteries has reached the limit, and further improvement in performance depends on the development and optimization of materials.
负极材料是锂离子电池实现性能提高的最关键材料之一，在众多新型负极材料中，硅材料的理论比容量为4200mAh/g，是石墨的10倍以上，而且还具有环境友好、储量丰富等特点，很早就被考虑作为下一代高能量密度锂离子电池的负极材料，可以提高电芯的能量密度。然而，硅负极材料的缺点也相当明显，例如：(1)硅负极材料在锂离子嵌入脱嵌过程中，会产生剧烈的体积膨胀(100％～300％)，在材料内部产生较大的内应力，对材料结构造成破坏，电极材料从集流体上脱落，同时硅表面的SEI膜不断重复形成-破裂-形成，共同降低了电极的导电性和循环稳定性；(2)硅为半导体材料，嵌锂过程为合金化反应，而石墨为导体，嵌锂过程为***脱出反应，这样就导致锂离子在硅中的脱嵌过程动力学比石墨慢，不可逆程度大，进一步降低了其首次库伦效率；(3)此外硅负极材料作为无机材料，其表面基团与有机电解液相容性较差，即与有机电解液不匹配，电极界面浸润时间较长且浸润均匀性差，容易在电池循环过程中造成SEI膜生长不均匀，最终引起容量衰减。The anode material is one of the most critical materials for improving the performance of lithium-ion batteries. Among the many new anode materials, the theoretical specific capacity of silicon materials is 4200 mAh/g, which is more than 10 times that of graphite, and it is also environmentally friendly and has abundant reserves. It has long been considered as a negative electrode material for the next generation of high energy density lithium ion batteries, which can increase the energy density of the cells. However, the shortcomings of the silicon anode material are also quite obvious, for example: (1) The silicon anode material will produce a severe volume expansion (100% to 300%) during the lithium ion intercalation and deintercalation process, resulting in a large interior inside the material. Stress, damage to the material structure, the electrode material is detached from the current collector, and the SEI film on the silicon surface is repeatedly formed-ruptured-formed to reduce the conductivity and cycle stability of the electrode; (2) silicon is a semiconductor material, The lithium intercalation process is an alloying reaction, and graphite is a conductor. The lithium intercalation process is an insertion and deintercalation reaction, which causes the desorption process of lithium ions in silicon to be slower than graphite and irreversible, further reducing its first coulombic efficiency. (3) In addition, as the inorganic material, the silicon anode material has poor compatibility between the surface group and the organic electrolyte, that is, it does not match the organic electrolyte, the electrode interface has a long infiltration time and the uniformity of the infiltration is poor, and it is easy to be in the battery cycle. The SEI film is unevenly grown, which eventually causes capacity decay.
为解决上述问题，目前业界通常在硅负极材料表面进行碳包覆，在硅负极材料和有机电解液之间建立保护界面，该碳包覆层可一定程度上缓解体积膨胀并提高导电性，但是仍然存在与电解液不匹配的问题，且受工艺限制该碳包覆层通常厚薄不均，后续电池循环过程中，这种不均匀包覆会进一步加剧SEI膜生长不均匀从而造成容量衰减。因此，有必要开发一种改性硅基负极材料，其在电池循环过程中表面能均匀生长SEI膜，且具有良好的离子导电性。In order to solve the above problems, the industry generally performs carbon coating on the surface of the silicon anode material, and establishes a protective interface between the silicon anode material and the organic electrolyte, which can relieve volume expansion and improve conductivity to some extent, but There is still a problem of mismatch with the electrolyte, and the carbon coating layer is usually uneven in thickness due to the process limitation. During the subsequent battery cycle, the uneven coating further aggravates the uneven growth of the SEI film to cause capacity degradation. Therefore, it is necessary to develop a modified silicon-based anode material which can uniformly grow an SEI film during battery cycling and has good ionic conductivity.
发明内容Summary of the invention
鉴于此，本发明实施例第一方面提供了一种改性硅基负极材料，其在电池循环过程中表面能均匀生长SEI膜，且具有良好的离子导电性，以解决现有硅基负极材料在电池循环过程中易造成SEI膜生长不均匀，最终引起容量衰减，以及硅基负极材料离子导电性不佳导致首次库伦效率低的问题。In view of this, the first aspect of the embodiments of the present invention provides a modified silicon-based anode material, which can uniformly grow an SEI film during battery cycling, and has good ionic conductivity to solve the existing silicon-based anode material. It is easy to cause uneven growth of SEI film during battery cycling, and finally cause capacity attenuation, and the poor ion conductivity of silicon-based anode material leads to the problem of low efficiency of the first coulomb.
具体地，本发明实施例第一方面提供了一种改性硅基负极材料，包括硅基负极材料和设置于所述硅基负极材料表面的改性层，所述改性层包括含磺酸基的硅烷偶联剂，所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合。Specifically, a first aspect of the embodiments of the present invention provides a modified silicon-based anode material, comprising a silicon-based anode material and a modified layer disposed on a surface of the silicon-based anode material, the modified layer comprising a sulfonic acid-containing layer a silane coupling agent, the sulfonic acid group-containing silane coupling agent comprising a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, the sulfonic acid group being attached to the non-hydrolyzable group At the end of the hydrolyzable group, the sulfonic acid group-containing silane coupling agent forms a chemical bond with the silicon-based negative electrode material through the hydrolyzable group.
本发明第一方面中，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可 水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、-OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种。 In a first aspect of the invention, the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3, -OC 2 H 4 OCH 3 , -OSi (CH 3) any one of the 3, -OOCCH 3, said at least one hydrolyzable group formed by the hydrolysis of chemical bonding of the silicon negative electrode material, the The non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。The silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
所述硅基负极材料为颗粒，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。The silicon-based anode material is a particle, and the modified layer is coated on the surface of the silicon-based anode material to form a core-shell structure. In the core-shell structure, the core is the silicon-based anode material, and the shell is the modified Sex layer.
所述硅基负极材料为薄膜，所述硅基负极材料附着于一衬底上，所述改性层包覆在所述硅基负极材料表面上。The silicon-based anode material is a film, the silicon-based anode material is attached to a substrate, and the modified layer is coated on the surface of the silicon-based anode material.
所述硅合金中包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。The silicon alloy includes one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
所述改性层的厚度为0.1nm-20nm。The modified layer has a thickness of 0.1 nm to 20 nm.
所述改性层的质量为所述硅基负极材料质量的0.01％-10％。The quality of the modified layer is from 0.01% to 10% by mass of the silicon-based negative electrode material.
所述含磺酸基的硅烷偶联剂由巯基硅烷偶联剂经氧化得到。The sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
本发明实施例第一方面提供的改性硅基负极材料，其表面的改性层厚度均匀，改性层的含磺酸基的硅烷偶联剂具有双亲结构，可显著提高无机硅负极表面与有机电解液之间的相容性，能使SEI膜均匀生长，阻止电解液在硅负极表面的持续分解，提供稳定的固液界面，减少副反应，提升循环寿命；同时在电池发生嵌锂反应过程中，磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一，从而可提高负极表面SEI膜的离子电导性，降低界面阻抗，进一步提升硅负极的功率性能和循环稳定性。The modified silicon-based negative electrode material provided by the first aspect of the present invention has a uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a double parent structure, which can significantly improve the surface of the inorganic silicon negative electrode and The compatibility between the organic electrolytes can make the SEI film grow evenly, prevent the electrolyte from decomposing continuously on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions, and improve cycle life. At the same time, lithium intercalation reaction occurs in the battery. During the process, the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance and circulation of the silicon negative electrode. stability.
本发明实施例第二方面提供了一种改性硅基负极材料的制备方法，包括以下步骤：A second aspect of the present invention provides a method for preparing a modified silicon-based anode material, comprising the following steps:
取硅基负极材料，当所述硅基负极材料为颗粒时，将所述硅基负极材料与含磺酸基的硅烷偶联剂混合均匀，经回流处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；Taking a silicon-based anode material, when the silicon-based anode material is a pellet, the silicon-based anode material is uniformly mixed with a sulfonic acid group-containing silane coupling agent, and is subjected to a reflow treatment to form a coating on the silicon-based anode. a modified layer on the surface of the material to obtain a modified silicon-based anode material;
当所述硅基负极材料为薄膜时，所述硅基负极材料附着于一衬底上，采用含磺酸基的硅烷偶联剂对所述硅基负极材料进行浸润或涂覆处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；When the silicon-based negative electrode material is a thin film, the silicon-based negative electrode material is attached to a substrate, and the silicon-based negative electrode material is infiltrated or coated with a sulfonic acid group-containing silane coupling agent to form a package. a modified layer covering the surface of the silicon-based anode material to obtain a modified silicon-based anode material;
所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合，得到所述改性层。The sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, and the sulfonic acid group is attached to an end of the non-hydrolyzable group. The sulfonic acid group-containing silane coupling agent is chemically bonded to the silicon-based negative electrode material through the hydrolyzable group to obtain the modified layer.
其中，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、-OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种。 Wherein the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 , -OC 2 Any one of H 4 OCH 3 , -OSi(CH 3 ) 3 , and -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis, the non-hydrolyzable group Any one selected from the group consisting of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。The silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy.
当所述硅基负极材料为颗粒时，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。When the silicon-based negative electrode material is a particle, the modified layer is coated on the surface of the silicon-based negative electrode material to form a core-shell structure, wherein the core-shell structure is a silicon-based negative electrode material, and the shell is a Said modified layer.
当所述硅基负极材料为薄膜时，所述改性层包覆在所述硅基负极材料表面上。When the silicon-based negative electrode material is a thin film, the modified layer is coated on the surface of the silicon-based negative electrode material.
所述硅合金中包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。The silicon alloy includes one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
所述改性层的厚度为0.1nm-20nm。The modified layer has a thickness of 0.1 nm to 20 nm.
所述改性层的质量为所述硅基负极材料质量的0.01％-10％。The quality of the modified layer is from 0.01% to 10% by mass of the silicon-based negative electrode material.
所述含磺酸基的硅烷偶联剂由巯基硅烷偶联剂经氧化得到。The sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
在进行所述回流、浸润或涂覆处理之前，先将所述硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。The silicon-based negative electrode material is vacuum dried prior to the reflow, wetting or coating treatment, and the vacuum drying temperature is 60 ° C to 80 ° C for 4-8 hours.
在进行所述回流、浸润或涂覆处理之后，收集所述改性硅基负极材料，并将所述改性硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。After performing the reflowing, wetting or coating treatment, collecting the modified silicon-based anode material, and vacuum drying the modified silicon-based anode material, the vacuum drying temperature is 60 ° C - 80 ° C, The time is 4-8 hours.
本发明实施例第二方面提供的制备方法，工艺简单，可获得改性层一致性高的改性硅基负极材料。The preparation method provided by the second aspect of the embodiment of the invention has a simple process, and a modified silicon-based anode material with high consistency of the modified layer can be obtained.
本发明实施例第三方面还提供了一种锂离子电池，包括正极、负极，以及位于所述正极与所述负极之间的隔膜和电解液，所述负极包括本发明第一方面所述的改性硅基负极材料。A third aspect of the present invention provides a lithium ion battery including a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode, the negative electrode including the first aspect of the present invention. Modified silicon-based anode material.
其中，在电池发生嵌锂反应过程中，所述磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一。Wherein, during the lithium insertion reaction of the battery, the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film.
本发明实施例第三方面提供的锂离子电池，循环性能优异，首次效率较高。The lithium ion battery provided by the third aspect of the embodiment of the invention has excellent cycle performance and high efficiency for the first time.
附图说明DRAWINGS
为了更清楚地说明本发明实施例或背景技术中的技术方案，下面将对本发明实施例或背景技术中所需要使用的附图进行说明。In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background art, the drawings to be used in the embodiments of the present invention or the background art will be described below.
图1为本发明一实施例提供的改性硅基负极材料的改性层分子键合示意图；1 is a schematic diagram of molecular bonding of a modified layer of a modified silicon-based anode material according to an embodiment of the present invention;
图2为本发明一实施例提供的改性硅基负极材料在发生嵌锂反应时SEI膜增强形成示意图；2 is a schematic view showing the formation of an SEI film in a modified silicon-based anode material in the process of lithium insertion reaction according to an embodiment of the present invention;
图3为本发明一实施例提供的改性硅基负极材料的结构示意图；3 is a schematic structural view of a modified silicon-based anode material according to an embodiment of the present invention;
图4为本发明另一实施例提供的改性硅基负极材料的结构示意图。4 is a schematic structural view of a modified silicon-based anode material according to another embodiment of the present invention.
具体实施方式Detailed ways
下面将结合本发明实施例中的附图，对本发明实施例进行说明。The embodiments of the present invention will be described below in conjunction with the accompanying drawings in the embodiments of the present invention.
目前，锂离子电池领域中，硅负极材料作为新型负极材料受到广泛关注，但是硅负极材料本身存在体积膨胀效应以及导电性较低的问题，同时作为无机材料，还存在与有机电解液不匹配，电极界面浸润时间较长且浸润均匀性差，容易在电池循环过程中造成SEI膜生长不均匀，最终引起容量衰减；同时，硅负极表面SEI膜的不断生长会降低电极材料的导电性，增大界面阻抗，影响功率性能。因此，有必要对硅负极材料进行相应改性，以有效保护硅负极材料，阻止电解液在硅负极表面的持续分解，提供稳定的固液界面，减少副反应，提升循环寿命；以及提高电极表面SEI膜的离子电导性，降低界面阻抗，进一步提升硅负极的功率性能和循环稳定性。At present, in the field of lithium ion batteries, silicon anode materials have attracted extensive attention as new anode materials, but the silicon anode materials themselves have the problems of volume expansion effect and low conductivity, and at the same time, as inorganic materials, there is also a mismatch with the organic electrolyte. The electrode interface has a long infiltration time and poor uniformity of wetting, which is easy to cause uneven growth of the SEI film during battery cycling, and finally causes capacity attenuation. Meanwhile, the continuous growth of the SEI film on the surface of the silicon negative electrode reduces the conductivity of the electrode material and increases the interface. Impedance, affecting power performance. Therefore, it is necessary to modify the silicon anode material to effectively protect the silicon anode material, prevent the electrolyte from continuously decomposing on the surface of the silicon anode, provide a stable solid-liquid interface, reduce side reactions, improve cycle life, and improve the electrode surface. The ionic conductivity of the SEI film reduces the interface impedance and further enhances the power performance and cycle stability of the silicon negative electrode.
基于此，本发明实施例提供了一种改性硅基负极材料，包括硅基负极材料和设置于所述硅基负极材料表面的改性层，所述改性层包括含磺酸基的硅烷偶联剂，所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合。Based on this, an embodiment of the present invention provides a modified silicon-based anode material, comprising a silicon-based anode material and a modified layer disposed on a surface of the silicon-based anode material, the modified layer comprising a sulfonic acid group-containing silane a coupling agent, the sulfonic acid group-containing silane coupling agent comprising a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, the sulfonic acid group being bonded to the non-hydrolyzable group At the end, the sulfonic acid group-containing silane coupling agent forms a chemical bond with the silicon-based negative electrode material through the hydrolyzable group.
本发明实施例提供的改性硅基负极材料，由硅基负极材料经含磺酸基的硅烷偶联剂改性获得，一方面，由于含磺酸基的硅烷偶联剂为双亲基团，因而可以使无机硅基负极材料和有机电解液具有良好相容性，有效提高硅基负极材料的浸润性，使SEI膜的生长更加均匀，同时改性层可以阻止电解液在负极表面的持续分解，提高电极循环稳定性；另一方面，磺酸基团在嵌锂反应过程中会生成磺酸锂，磺酸锂作为SEI膜的组成成分之一，可提高负极表面SEI膜的离子电导性，降低界面阻抗，进一步提升硅负极的功率性能。The modified silicon-based anode material provided by the embodiment of the invention is obtained by modifying a silicon-based anode material with a sulfonic acid group-containing silane coupling agent. On the one hand, since the sulfonic acid group-containing silane coupling agent is a parent group, Therefore, the inorganic silicon-based anode material and the organic electrolyte can have good compatibility, effectively improve the wettability of the silicon-based anode material, and make the growth of the SEI film more uniform, and the modified layer can prevent the electrolyte from continuously decomposing on the surface of the anode. To improve the stability of the electrode cycle; on the other hand, the sulfonic acid group will form lithium sulfonate during the lithium intercalation reaction, and lithium sulfonate is one of the constituent components of the SEI film, which can improve the ionic conductivity of the SEI film on the surface of the negative electrode. Reduce the interface impedance and further improve the power performance of the silicon negative electrode.
本发明实施方式中，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、-OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种，所述磺酸基结合在所述非水解基团末端。应该说明的是，本发明实施方式中，所述可水解基团和非水解基团也可以是其他组成硅烷偶联剂的常规基团，并不局限于上述的举例。 In an embodiment of the invention, the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 And any one of -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis, The non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group, and the sulfonic acid group is bonded to the non-hydrolyzable group. The end of the group. It should be noted that, in the embodiment of the present invention, the hydrolyzable group and the non-hydrolyzable group may also be other conventional groups constituting the silane coupling agent, and are not limited to the above examples.
具体地，本发明一实施方式中，所述含磺酸基的硅烷偶联剂的结构通式如式(1)所示：Specifically, in one embodiment of the present invention, the structural formula of the sulfonic acid group-containing silane coupling agent is as shown in the formula (1):
Figure PCTCN2019080139-appb-000001
Figure PCTCN2019080139-appb-000001
其中，X为所述可水解基团，R为所述非水解基团去掉一个氢原子后的残基。Wherein X is the hydrolyzable group, and R is a residue obtained by removing one hydrogen atom from the non-hydrolyzable group.
如图1所示，为本发明实施例提供的改性硅基负极材料的改性层分子键合示意图，由于所述含磺酸基的硅烷偶联剂是通过所述可水解基团经水解后与所述硅基负极材料形成化学键合，因此硅基负极材料最终与含磺酸基的硅烷偶联剂构成Si-O键键合，当然如果硅基负极材料还包括硅以外的其他元素，则硅基负极材料与含磺酸基的硅烷偶联剂也可能构成其他方式的化学键合。As shown in FIG. 1 , a schematic diagram of molecular bonding of a modified layer of a modified silicon-based anode material provided by an embodiment of the present invention, wherein the sulfonic acid group-containing silane coupling agent is hydrolyzed by the hydrolyzable group After forming a chemical bond with the silicon-based negative electrode material, the silicon-based negative electrode material finally forms a Si-O bond with the sulfonic acid group-containing silane coupling agent. Of course, if the silicon-based negative electrode material further includes other elements than silicon, The silicon-based negative electrode material and the sulfonic acid group-containing silane coupling agent may also constitute other forms of chemical bonding.
如图2所示，为本发明实施例提供的改性硅基负极材料在发生嵌锂反应时SEI膜增强形成示意图，在电池发生嵌锂反应过程中，磺酸基与锂离子反应生成了磺酸锂，磺酸锂作为SEI膜的成分之一，提高了负极表面SEI膜的离子电导性，从而可使得锂离子传输速率加快。As shown in FIG. 2, a schematic diagram of the SEI film reinforcement formation in the modified silicon-based anode material provided by the embodiment of the present invention, in the process of lithium insertion reaction, the sulfonic acid group reacts with lithium ions to form a sulfonate. Lithium acid and lithium sulfonate are one of the components of the SEI film, which improves the ionic conductivity of the SEI film on the surface of the negative electrode, thereby accelerating the lithium ion transport rate.
本发明实施例方式中，所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。其中，所述硅合金中可包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。所述硅基负极材料的形态不限，可以是颗粒状，也可以是薄膜状。In the embodiment of the present invention, the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy. Wherein, the silicon alloy may include one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg. The form of the silicon-based negative electrode material is not limited, and may be in the form of particles or a film.
本发明一具体实施方式中，所述硅基负极材料为颗粒，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。如图3所示，为具有核壳结构的改性硅基负极材料的结构示意图，图中，11为硅基负极材料，12为改性层。其中，所述硅基负极材料的颗粒粒径可以是微纳米级别，具体地可为10nm-20μm，更具体地可为100nm-500nm，1μm-10μm。In a specific embodiment of the present invention, the silicon-based negative electrode material is a particle, and the modified layer is coated on a surface of the silicon-based negative electrode material to form a core-shell structure. In the core-shell structure, the core is the silicon-based structure. A negative electrode material, and the shell is the modified layer. As shown in FIG. 3, it is a schematic structural view of a modified silicon-based anode material having a core-shell structure, in which 11 is a silicon-based anode material and 12 is a modified layer. The particle size of the silicon-based anode material may be on the order of micrometers and nanometers, specifically 10 nm to 20 μm, more specifically, 100 nm to 500 nm, and 1 μm to 10 μm.
本发明另一具体实施方式中，所述硅基负极材料为薄膜，所述硅基负极材料附着于一衬底上，所述改性层包覆在所述硅基负极材料表面上。本发明某一实施方式中，所述改性层仅包覆所述硅基负极材料薄膜的上表面，如图4所示，为薄膜态的硅基负极材料改性后的结构 示意图，图中，20为衬底，21为硅基负极材料，22为改性层。在本发明其他实施方式中，所述改性层也可能包覆所述硅基负极材料未与所述衬底接触的所有表面。In another embodiment of the present invention, the silicon-based anode material is a film, the silicon-based anode material is attached to a substrate, and the modified layer is coated on the surface of the silicon-based anode material. In one embodiment of the present invention, the modified layer covers only the upper surface of the silicon-based negative electrode material film, as shown in FIG. 4, and is a structural schematic diagram of a modified silicon-based negative electrode material in a thin film state, in which 20 is a substrate, 21 is a silicon-based anode material, and 22 is a modified layer. In other embodiments of the invention, the modified layer may also coat all surfaces of the silicon-based negative electrode material that are not in contact with the substrate.
本发明实施方式中，所述硅基负极材料薄膜的厚度为2μm-8μm，进一步地厚度为4μm。In an embodiment of the invention, the silicon-based negative electrode material film has a thickness of 2 μm to 8 μm, and further has a thickness of 4 μm.
本发明实施方式中，所述改性层的厚度为0.1nm-20nm。进一步地，改性层的厚度可以是1nm-10nm、5nm-15nm、1nm-5nm。适合的改性层厚度能够有效抑制硅基负极材料的膨胀效应，阻止电解液的持续分解，保护电极界面；改性层厚度太薄无法实现保护电极界面的效果，太厚则会限制其他SEI膜组分的生长，影响改性效果。In an embodiment of the invention, the modified layer has a thickness of 0.1 nm to 20 nm. Further, the thickness of the modified layer may be 1 nm to 10 nm, 5 nm to 15 nm, and 1 nm to 5 nm. The suitable thickness of the modified layer can effectively inhibit the expansion effect of the silicon-based anode material, prevent the electrolyte from decomposing continuously, and protect the electrode interface; the thickness of the modified layer is too thin to achieve the effect of protecting the electrode interface, and too thick will limit other SEI films. The growth of the components affects the modification effect.
本发明实施方式中，所述改性层的质量为所述硅基负极材料质量的0.01％-10％。进一步地，改性层的质量占比为0.5％-2％。适合的质量占比能够使得改性层较好地发挥其改善负极材料浸润性，抑制电解液持续分解，以及提升负极材料离子电导性的效果，又能够使负极材料保持较高的容量。In an embodiment of the invention, the quality of the modified layer is 0.01%-10% of the mass of the silicon-based negative electrode material. Further, the mass ratio of the modified layer is from 0.5% to 2%. The suitable mass ratio can make the modified layer better to improve the wettability of the negative electrode material, inhibit the continuous decomposition of the electrolyte, and improve the ionic conductivity of the negative electrode material, and maintain the high capacity of the negative electrode material.
本发明实施方式中，所述含磺酸基的硅烷偶联剂可通过将巯基硅烷偶联剂经氧化得到，具体地，可以将带有巯基的硅烷偶联剂与常见氧化剂反应获得，所述氧化剂例如可以是双氧水、硫酸等。In the embodiment of the present invention, the sulfonic acid group-containing silane coupling agent can be obtained by oxidizing a mercaptosilane coupling agent, and specifically, a mercapto group-containing silane coupling agent can be obtained by reacting with a common oxidizing agent. The oxidizing agent may be, for example, hydrogen peroxide, sulfuric acid or the like.
本发明实施例提供的改性硅基负极材料，其表面的改性层厚度均匀，改性层的含磺酸基的硅烷偶联剂具有双亲结构，可显著提高无机硅负极表面与有机电解液之间的相容性，能使SEI膜均匀生长，阻止电解液在硅负极表面的持续分解，提供稳定的固液界面，减少副反应，提升循环寿命；同时在电池发生嵌锂反应过程中，磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一，从而可提高负极表面SEI膜的离子电导性，降低界面阻抗，进一步提升硅负极的功率性能和循环稳定性。The modified silicon-based anode material provided by the embodiment of the invention has uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a double parent structure, which can significantly improve the surface of the inorganic silicon anode and the organic electrolyte. The compatibility between the SEI film can make the SEI film grow evenly, prevent the electrolyte from continuously decomposing on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions and improve cycle life. At the same time, during the lithium insertion reaction of the battery, The sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance and cycle stability of the silicon negative electrode.
相应地，本发明实施例还提供了一种改性硅基负极材料的制备方法，包括以下步骤：Correspondingly, the embodiment of the invention further provides a method for preparing a modified silicon-based anode material, comprising the following steps:
取硅基负极材料，当所述硅基负极材料为颗粒时，将所述硅基负极材料与含磺酸基的硅烷偶联剂混合均匀，经回流处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；Taking a silicon-based anode material, when the silicon-based anode material is a pellet, the silicon-based anode material is uniformly mixed with a sulfonic acid group-containing silane coupling agent, and is subjected to a reflow treatment to form a coating on the silicon-based anode. a modified layer on the surface of the material to obtain a modified silicon-based anode material;
当所述硅基负极材料为薄膜时，所述硅基负极材料附着于一衬底上，采用含磺酸基的硅烷偶联剂对所述硅基负极材料进行浸润或涂覆处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；When the silicon-based negative electrode material is a thin film, the silicon-based negative electrode material is attached to a substrate, and the silicon-based negative electrode material is infiltrated or coated with a sulfonic acid group-containing silane coupling agent to form a package. a modified layer covering the surface of the silicon-based anode material to obtain a modified silicon-based anode material;
所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合，得到所述改性层。The sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, and the sulfonic acid group is attached to an end of the non-hydrolyzable group. The sulfonic acid group-containing silane coupling agent is chemically bonded to the silicon-based negative electrode material through the hydrolyzable group to obtain the modified layer.
本发明实施方式中，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、-OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种。应该说明的是，本发明实施方式中，所述可水解基团和非水解基团也可以是其他组成硅烷偶联剂的常规基团，并不局限于上述的举例。 In an embodiment of the invention, the sulfonic acid group-containing silane coupling agent comprises three of the hydrolyzable groups, and the three hydrolyzable groups are respectively selected from -Cl, -OCH 3 , -OCH 2 CH 3 And any one of -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups is chemically bonded to the silicon-based negative electrode material after hydrolysis, The non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group. It should be noted that, in the embodiment of the present invention, the hydrolyzable group and the non-hydrolyzable group may also be other conventional groups constituting the silane coupling agent, and are not limited to the above examples.
本发明实施例方式中，所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。其中，所述硅合金中可包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。所述硅基负极材料的形态不限，可以是颗粒状，也可以是薄膜状。In the embodiment of the present invention, the silicon-based anode material includes one or more of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy. Wherein, the silicon alloy may include one or more elements of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg. The form of the silicon-based negative electrode material is not limited, and may be in the form of particles or a film.
本发明一具体实施方式中，所述硅基负极材料为颗粒，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。其中，所述硅基负极材料的颗粒粒径可以是微纳米级别，具体地可为10nm-20μm。In a specific embodiment of the present invention, the silicon-based negative electrode material is a particle, and the modified layer is coated on a surface of the silicon-based negative electrode material to form a core-shell structure. In the core-shell structure, the core is the silicon-based structure. A negative electrode material, and the shell is the modified layer. Wherein, the particle diameter of the silicon-based anode material may be on the order of micrometers and nanometers, specifically 10 nm to 20 μm.
本发明实施方式中，将所述硅基负极材料与含磺酸基的硅烷偶联剂通过超声混合均匀，混合过程可加入有机溶剂，所述有机溶剂可以是乙醇、甲醇等醇类溶剂，环己烷、环己酮等脂环烃类溶剂，也可以是苯、甲苯等芳香烃类溶剂，超声的功率和时间可根据实际需要设定，例如超声0.5-2小时。所述回流处理的回流温度为60℃-100℃，回流处理时间为4-8小时。进一步地，回流温度可以是80℃，回流处理时间为6小时。In the embodiment of the present invention, the silicon-based negative electrode material and the sulfonic acid group-containing silane coupling agent are uniformly mixed by ultrasonication, and an organic solvent may be added during the mixing process, and the organic solvent may be an alcohol solvent such as ethanol or methanol. The alicyclic hydrocarbon solvent such as hexane or cyclohexanone may be an aromatic hydrocarbon solvent such as benzene or toluene. The power and time of the ultrasonic wave may be set according to actual needs, for example, ultrasonic for 0.5 to 2 hours. The reflux temperature of the reflux treatment is from 60 ° C to 100 ° C, and the reflux treatment time is from 4 to 8 hours. Further, the reflux temperature may be 80 ° C and the reflux treatment time is 6 hours.
本发明另一具体实施方式中，所述硅基负极材料为薄膜，所述硅基负极材料附着于一衬底上，所述改性层包覆所述硅基负极材料未与所述衬底接触的所有表面。In another embodiment of the present invention, the silicon-based negative electrode material is a film, the silicon-based negative electrode material is attached to a substrate, and the modified layer covers the silicon-based negative electrode material and the substrate All surfaces in contact.
本发明实施方式中，所述采用含磺酸基的硅烷偶联剂对所述硅基负极材料进行浸润或涂覆处理的具体操作为：将含磺酸基的硅烷偶联剂加入到有机溶剂中，配成含磺酸基的硅烷偶联剂溶液，将所述硅基负极材料浸没在所述含磺酸基的硅烷偶联剂溶液中，或将所述含磺酸基的硅烷偶联剂溶液涂覆在所述硅基负极材料表面。所述有机溶剂可以是乙醇、甲醇等醇类溶剂，环己烷、环己酮等脂环烃类溶剂，也可以是苯、甲苯等芳香烃类溶剂。所述含磺酸基的硅烷偶联剂溶液的质量浓度可根据实际需要控制，具体例如可以是3％-8％，更具体地为5％。In the embodiment of the present invention, the specific operation of infiltrating or coating the silicon-based negative electrode material by using a sulfonic acid group-containing silane coupling agent is: adding a sulfonic acid group-containing silane coupling agent to an organic solvent a silane coupling agent solution containing a sulfonic acid group, immersing the silicon-based negative electrode material in the sulfonic acid group-containing silane coupling agent solution, or coupling the sulfonic acid group-containing silane A solution of the solution is coated on the surface of the silicon-based negative electrode material. The organic solvent may be an alcohol solvent such as ethanol or methanol, an alicyclic hydrocarbon solvent such as cyclohexane or cyclohexanone, or an aromatic hydrocarbon solvent such as benzene or toluene. The mass concentration of the sulfonic acid group-containing silane coupling agent solution may be controlled according to actual needs, and may specifically be, for example, 3% to 8%, more specifically 5%.
本发明实施方式中，可以通过控制浸润时间长短、含磺酸基的硅烷偶联剂溶液浓度、涂覆厚度等参数以实现不同厚度改性层包覆。In the embodiment of the present invention, the thickness of the modified layer can be achieved by controlling parameters such as the length of the infiltration time, the concentration of the sulfonic acid group-containing silane coupling agent solution, and the coating thickness.
本发明实施方式中，所述衬底可以是铜箔，所述涂覆方式包括旋涂。In an embodiment of the invention, the substrate may be a copper foil, and the coating method includes spin coating.
本发明实施方式中，通过浸润方式获得的改性层，会包覆所述硅基负极材料薄膜未与所述衬底接触的所有表面；而通过涂覆方式获得的改性层，通常仅包覆所述硅基负极材料薄膜的上表面。In the embodiment of the present invention, the modified layer obtained by the wetting method covers all the surfaces of the silicon-based negative electrode material film that are not in contact with the substrate; and the modified layer obtained by the coating method is usually only included. The upper surface of the film of the silicon-based negative electrode material is coated.
本发明一具体实施方式中，当所述硅基负极材料为薄膜时，采用旋涂法进行改性层包覆，具体地，先将负载有硅基负极材料薄膜的衬底在烘箱中加热后，置于旋涂机，再选用一定浓度的含磺酸基的硅烷偶联剂溶液进行旋涂处理，以在薄膜表面进行修饰改性，得到改性层。In a specific embodiment of the present invention, when the silicon-based negative electrode material is a film, the modified layer is coated by a spin coating method. Specifically, the substrate loaded with the silicon-based negative electrode material film is first heated in an oven. , placed in a spin coater, and then selected a certain concentration of sulfonic acid group-containing silane coupling agent solution for spin coating treatment, to modify the surface of the film to obtain a modified layer.
本发明实施方式中，所述改性层的厚度为0.1nm-20nm。进一步地，改性层的厚度可以是1nm-10nm、5nm-15nm、1nm-5nm。适合的改性层厚度能够有效抑制硅基负极材料的膨胀效应，阻止电解液的持续分解，保护电极界面；改性层厚度太薄无法实现保护电极界面的效果，太厚则会限制其他SEI膜组分的生长，影响改性效果。In an embodiment of the invention, the modified layer has a thickness of 0.1 nm to 20 nm. Further, the thickness of the modified layer may be 1 nm to 10 nm, 5 nm to 15 nm, and 1 nm to 5 nm. The suitable thickness of the modified layer can effectively inhibit the expansion effect of the silicon-based anode material, prevent the electrolyte from decomposing continuously, and protect the electrode interface; the thickness of the modified layer is too thin to achieve the effect of protecting the electrode interface, and too thick will limit other SEI films. The growth of the components affects the modification effect.
本发明实施方式中，所述改性层的质量为所述硅基负极材料质量的0.01％-10％。进一步地，改性层的质量占比为0.5％-2％。适合的质量占比能够使得改性层较好地发挥其改善负极材料浸润性，抑制电解液持续分解，以及提升负极材料离子电导性的效果，又能够使负极材料保持较高的容量。In an embodiment of the invention, the quality of the modified layer is 0.01%-10% of the mass of the silicon-based negative electrode material. Further, the mass ratio of the modified layer is from 0.5% to 2%. The suitable mass ratio can make the modified layer better to improve the wettability of the negative electrode material, inhibit the continuous decomposition of the electrolyte, and improve the ionic conductivity of the negative electrode material, and maintain the high capacity of the negative electrode material.
本发明实施方式中，所述含磺酸基的硅烷偶联剂可通过将巯基硅烷偶联剂经氧化得到，具体地，可以将带有巯基的硅烷偶联剂与常见氧化剂反应获得，所述氧化剂例如可以是双氧水、硫酸等。In the embodiment of the present invention, the sulfonic acid group-containing silane coupling agent can be obtained by oxidizing a mercaptosilane coupling agent, and specifically, a mercapto group-containing silane coupling agent can be obtained by reacting with a common oxidizing agent. The oxidizing agent may be, for example, hydrogen peroxide, sulfuric acid or the like.
本发明实施方式中，所述含磺酸基的硅烷偶联剂的用量为硅基负极材料质量的0.01-10％。In an embodiment of the invention, the sulfonic acid group-containing silane coupling agent is used in an amount of 0.01 to 10% by mass based on the mass of the silicon-based negative electrode material.
本发明实施方式中，在进行所述回流、浸润或涂覆处理之前，先将所述硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。真空干燥处理能够减少硅基负极材料中的水分，防止硅烷偶联剂在其表面过度水解。In the embodiment of the present invention, the silicon-based anode material is vacuum dried before the reflow, wetting or coating treatment, and the vacuum drying temperature is 60° C.-80° C., and the time is 4-8 hours. . The vacuum drying treatment can reduce moisture in the silicon-based anode material and prevent excessive hydrolysis of the silane coupling agent on the surface thereof.
本发明实施方式中，在进行所述回流、浸润或涂覆处理之后，收集所述改性硅基负极材料，并将所述改性硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。此处的真空干燥在起到干燥作用的同时，可以使得含磺酸基的硅烷偶联剂更好地结合在所述硅基负极材料表面。In the embodiment of the present invention, after the reflowing, wetting or coating treatment, the modified silicon-based anode material is collected, and the modified silicon-based anode material is vacuum dried, and the vacuum drying temperature is 60 ° C - 80 ° C, time is 4-8 hours. The vacuum drying here can make the sulfonic acid group-containing silane coupling agent better bonded to the surface of the silicon-based negative electrode material while performing the drying action.
本发明实施例提供的制备方法，工艺简单，制备得到的改性硅基负极材料，其表面具有一致性高的改性层。The preparation method provided by the embodiment of the invention has simple process, and the prepared modified silicon-based anode material has a highly uniform modified layer on the surface thereof.
此外，本发明实施例还提供一种锂离子电池，包括正极、负极，以及位于所述正极与所述负极之间的隔膜和电解液，所述负极本发明上述实施例提供的改性硅基负极材料。In addition, an embodiment of the present invention further provides a lithium ion battery including a positive electrode, a negative electrode, and a separator and an electrolyte solution between the positive electrode and the negative electrode, and the negative electrode is the modified silicon base provided by the above embodiment of the present invention. Anode material.
其中，在电池发生嵌锂反应过程中，所述磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一。Wherein, during the lithium insertion reaction of the battery, the sulfonic acid group can react with lithium ions to form a lithium sulfonate group as one of the components of the SEI film.
当改性硅基负极材料为核壳结构的颗粒时，所述负极包括负极集流体和设置在所述负极集流体上的负极活性层，所述负极活性层包括改性硅基负极材料、粘结剂、导电剂等。而当所述改性硅基负极材料为薄膜时，所述改性硅基负极材料附着于一衬底上，所述衬底可为铜箔等箔材充当集流体，所述改性硅基负极材料直接充当负极。When the modified silicon-based anode material is a core-shell structure particle, the anode includes a cathode current collector and an anode active layer disposed on the anode current collector, the anode active layer including a modified silicon-based anode material, and a binder A binder, a conductive agent, and the like. When the modified silicon-based negative electrode material is a thin film, the modified silicon-based negative electrode material is attached to a substrate, and the substrate may serve as a current collector for a foil such as copper foil, and the modified silicon base The negative electrode material directly acts as a negative electrode.
本发明实施例提供的锂离子电池，循环性能优异，首次效率较高。The lithium ion battery provided by the embodiment of the invention has excellent cycle performance and high efficiency for the first time.
下面分多个实施例对本发明实施例进行进一步的说明。The embodiments of the present invention are further described below in various embodiments.
实施例1Example 1
一种改性硅基负极材料(3-磺酸丙基甲基二甲氧基硅烷改性的硅纳米颗粒)的制备方法，包括以下步骤：A preparation method of a modified silicon-based anode material (3-sulfonic acid propylmethyldimethoxysilane-modified silicon nanoparticle) comprises the following steps:
(1)取5g直径为100nm的纳米硅粉，在真空干燥箱中进行干燥处理，处理温度为60℃，处理时间为5小时；(1) taking 5 g of nano-silica powder having a diameter of 100 nm, drying in a vacuum drying oven, the treatment temperature is 60 ° C, and the treatment time is 5 hours;
(2)将上一步干燥处理得到的纳米硅粉与0.25g 3-磺酸丙基甲基二甲氧基硅烷加入到500mL烧瓶中，然后加入200mL无水乙醇，超声混合0.5h；接着在搅拌条件下温度为80℃体系下回流6h，回流结束后，将反应液于6000r/min转速的离心机中进行分离处理，得到固体沉淀；(2) Adding the nano silicon powder obtained by the previous drying treatment to 0.25 g of 3-sulfonic acid propylmethyldimethoxysilane into a 500 mL flask, then adding 200 mL of absolute ethanol, ultrasonically mixing for 0.5 h; Under the condition, the temperature is 80 ° C under reflux for 6 h. After the reflux is completed, the reaction solution is separated in a centrifuge at 6000 r/min to obtain a solid precipitate;
(3)将所述固体沉淀放入真空干燥箱，在60℃真空干燥6h，得到3-磺酸丙基甲基二甲氧基硅烷改性的硅纳米颗粒。(3) The solid precipitate was placed in a vacuum drying oven and vacuum dried at 60 ° C for 6 hours to obtain 3-sulfonic acid propylmethyldimethoxysilane-modified silicon nanoparticles.
锂离子电池的制备Preparation of lithium ion battery
称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％3-磺酸丙基甲基二甲氧基硅烷改性的硅纳米颗粒依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片；Weighing 7% polyacrylic acid lithium (PAALi), 3% conductive agent super P and 90% 3-sulfonic acid propyl methyl dimethoxysilane modified silicon nanoparticles were added to deionized water in turn. , stirring and mixing well, coating the slurry on the copper foil current collector, drying, cold pressing, and slitting to obtain the negative electrode tab;
称取质量百分含量为3％聚偏氟乙烯(PVDF)、3％导电剂super P和95％钴酸锂(LiCoO 2)，依次加入到N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀，将浆料涂布在铝箔集流体上，烘干、冷压、分切制得正极极片； Weigh 3% by weight of polyvinylidene fluoride (PVDF), 3% of conductive agent super P and 95% of lithium cobaltate (LiCoO 2 ), and then add it to N-methylpyrrolidone (NMP), stir well. Uniformly, the slurry is coated on an aluminum foil current collector, and dried, cold pressed, and slit to obtain a positive electrode tab;
将上述制备的正极极片、负极极片和商用PP/PE/PP三层隔膜(厚度为16μm)制成方形电芯，采用聚合物包装，灌注电解液，电解液为1mol/L LiPF 6/EC+PC+DEC+EMC(体积比1:0.3:1:1)，经化成等工艺后制成3.7Ah的软包锂二次电池。 The positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 μm) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
实施例2Example 2
一种改性硅基负极材料(3-磺酸丙基三乙氧基硅烷改性的硅薄膜)的制备方法，包括以下步骤：A preparation method of a modified silicon-based anode material (3-sulfonic acid propyl triethoxysilane-modified silicon film) comprises the following steps:
(1)取面积为77mm*58mm的以铜箔为衬底的硅薄膜，将硅薄膜放入真空干燥箱进行干燥处理，干燥温度为80℃，处理时间为6小时；(1) taking a silicon film with a copper foil as a substrate with an area of 77 mm*58 mm, and drying the silicon film in a vacuum drying oven at a drying temperature of 80 ° C for a treatment time of 6 hours;
(2)将干燥处理得到的硅薄膜放入旋涂机中心并开启真空泵，吸住硅薄膜，用玻璃滴管吸取10mL 5％的3-磺酸丙基三乙氧基硅烷滴到硅薄膜中心，设置转速1500r/min，时间为2min，开启旋涂机电源，进行旋涂处理；(2) Put the silicon film obtained by drying into the center of the spin coater and turn on the vacuum pump, suck the silicon film, and use a glass dropper to draw 10 mL of 5% 3-sulfonic acid propyl triethoxysilane to the center of the silicon film. , set the speed of 1500r / min, the time is 2min, turn on the power of the spin coating machine, and perform spin coating treatment;
(3)将旋涂完毕的硅薄膜放入真空干燥箱于60℃干燥6h，得到3-磺酸丙基三乙氧基硅烷改性的硅薄膜。(3) The spin-coated silicon film was placed in a vacuum drying oven at 60 ° C for 6 hours to obtain a 3-sulfonic acid propyl triethoxysilane-modified silicon film.
锂离子电池的制备Preparation of lithium ion battery
将上述制备的3-磺酸丙基三乙氧基硅烷改性的硅薄膜通过模切制得尺寸为77mm*58mm的负极极片；The 3-sulfonic acid propyl triethoxysilane-modified silicon film prepared above is subjected to die-cutting to obtain a negative electrode tab having a size of 77 mm*58 mm;
称取质量百分含量为3％聚偏氟乙烯(PVDF)、3％导电剂super P和95％钴酸锂(LiCoO 2)，依次加入到N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀，将浆料涂布在铝箔集流体上，烘干、冷压、分切尺寸为76mm*57mm的正极极片； Weigh 3% by weight of polyvinylidene fluoride (PVDF), 3% of conductive agent super P and 95% of lithium cobaltate (LiCoO 2 ), and then add it to N-methylpyrrolidone (NMP), stir well. Uniformly, the slurry is coated on an aluminum foil current collector, and dried, cold pressed, and cut into a positive electrode piece having a size of 76 mm*57 mm;
将上述制备的正极极片、负极极片和商用PP/PE/PP三层隔膜(厚度为16μm)，采用叠片工艺制成方形电芯，采用聚合物包装，灌注电解液，电解液为1mol/L LiPF 6/EC+PC+DEC+EMC(体积比1:0.3:1:1)，经化成等工艺后制成3.7Ah的软包锂二次电池。 The positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 μm) were formed into a square electric core by a lamination process, and the polymer was packaged, and the electrolyte was poured, and the electrolyte was 1 mol. /L LiPF 6 /EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
实施例3Example 3
一种改性硅基负极材料(3-磺酸基甲基二乙氧基硅烷改性的氧化亚硅颗粒)的制备方法，包括以下步骤：A preparation method of a modified silicon-based anode material (3-sulfonic acid methyldiethoxysilane-modified oxidized silicon oxide particles) comprises the following steps:
(1)取5g直径为5μm的氧化亚硅粉体，在真空干燥箱中进行干燥处理，处理温度为50℃，处理时间为6小时；(1) taking 5 g of 5 μm diameter silicon oxide powder, drying in a vacuum drying oven, the treatment temperature is 50 ° C, the treatment time is 6 hours;
(2)将上一步干燥处理得到的氧化亚硅粉体与0.5g 3-磺酸基甲基二乙氧基硅烷加入到500mL烧瓶中，然后加入200mL无水乙醇，超声混合0.5h；接着在搅拌条件下温度为80℃体系下回流6h，回流结束后，将反应液于6000r/min转速的离心机中进行分离处理，得到固体沉淀；(2) adding the SiO2 powder obtained by the drying process in the previous step and 0.5 g of 3-sulfonic acid methyldiethoxysilane to a 500 mL flask, then adding 200 mL of absolute ethanol, ultrasonically mixing for 0.5 h; Under the stirring condition, the temperature was 80 ° C under reflux for 6 h. After the reflux was completed, the reaction solution was separated in a centrifuge of 6000 r/min to obtain a solid precipitate;
(3)将分离得到的所述固体沉淀放入真空干燥箱，在60℃真空干燥6h，得到3-磺酸基甲基二乙氧基硅烷改性的氧化亚硅颗粒。(3) The solid precipitate obtained by separation was placed in a vacuum drying oven and vacuum-dried at 60 ° C for 6 hours to obtain 3-sulfonic acid methyldiethoxysilane-modified SiO2 particles.
锂离子电池的制备Preparation of lithium ion battery
称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％3-磺酸基甲基二乙氧基硅烷改性的氧化亚硅颗粒(SiO)依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片；Weigh 7% polyacrylic acid lithium (PAALi), 3% conductive agent super P and 90% 3-sulfomethyldiethoxysilane modified SiO2 particles (SiO) were added to Deionized water, fully stirred and mixed uniformly, the slurry is coated on a copper foil current collector, dried, cold pressed, and slit to obtain a negative electrode piece;
称取质量百分含量为3％聚偏氟乙烯(PVDF)、3％导电剂super P和95％钴酸锂(LiCoO 2)，依次加入到N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀，将浆料涂布在铝箔集流体上，烘干、冷压、分切制得正极极片； Weigh 3% by weight of polyvinylidene fluoride (PVDF), 3% of conductive agent super P and 95% of lithium cobaltate (LiCoO 2 ), and then add it to N-methylpyrrolidone (NMP), stir well. Uniformly, the slurry is coated on an aluminum foil current collector, and dried, cold pressed, and slit to obtain a positive electrode tab;
将上述制备的正极极片、负极极片和商用PP/PE/PP三层隔膜(厚度为16μm)制成方形电芯，采用聚合物包装，灌注电解液，电解液为1mol/L LiPF 6/EC+PC+DEC+EMC(体积比1:0.3:1:1)，经化成等工艺后制成3.7Ah的软包锂二次电池。 The positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 μm) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
实施例4Example 4
一种改性硅基负极材料(3-磺酸基甲基三乙氧基硅烷改性的硅碳颗粒)的制备方法，包括以下步骤：A preparation method of a modified silicon-based anode material (3-sulfonic acid methyltriethoxysilane-modified silicon carbon particles) comprises the following steps:
(1)取5g直径为15μm的硅碳粉体，在真空干燥箱中进行干燥处理，处理温度为50℃，处理时间为6小时；(1) taking 5 g of silicon carbon powder having a diameter of 15 μm, drying in a vacuum drying oven, the treatment temperature is 50 ° C, and the treatment time is 6 hours;
(2)将上一步干燥处理得到的硅碳粉体与1g 3-磺酸基甲基三乙氧基硅烷加入到500mL烧瓶中，然后加入200mL无水甲醇，超声混合0.5h；接着在搅拌条件下温度为80℃体系下回流6h，回流结束后，将反应液于6000r/min转速的离心机中进行分离处理，得到固体沉淀；(2) Adding the silicon carbon powder obtained by the previous drying treatment to 1 g of 3-sulfonic acid methyltriethoxysilane into a 500 mL flask, then adding 200 mL of anhydrous methanol, ultrasonically mixing for 0.5 h; The lower temperature is refluxed for 6 hours under the system of 80 ° C. After the reflux is completed, the reaction liquid is separated and treated in a centrifuge of 6000 r/min to obtain a solid precipitate;
(3)将分离得到的所述固体沉淀放入真空干燥箱，在60℃真空干燥6h，得到3-磺酸基甲基三乙氧基硅烷改性的硅碳颗粒。(3) The solid precipitate obtained by separation was placed in a vacuum drying oven and vacuum dried at 60 ° C for 6 hours to obtain 3-sulfonic acid methyltriethoxysilane-modified silicon carbon particles.
锂离子电池的制备Preparation of lithium ion battery
称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％3-磺酸基甲基三乙氧基硅烷改性的硅碳颗粒(SiC)依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片；Weighed 7% polyacrylic acid lithium (PAALi), 3% conductive agent super P and 90% 3-sulfomethyltriethoxysilane modified silicon carbon particles (SiC) were added to In the ionic water, stir well and mix well, apply the slurry on the copper foil current collector, dry, cold press, and slit to obtain the negative electrode piece;
称取质量百分含量为3％聚偏氟乙烯(PVDF)、3％导电剂super P和95％钴酸锂(LiCoO 2)，依次加入到N-甲基吡咯烷酮(NMP)中，充分搅拌混合均匀，将浆料涂布在铝箔集流体上，烘干、冷压、分切制得正极极片； Weigh 3% by weight of polyvinylidene fluoride (PVDF), 3% of conductive agent super P and 95% of lithium cobaltate (LiCoO 2 ), and then add it to N-methylpyrrolidone (NMP), stir well. Uniformly, the slurry is coated on an aluminum foil current collector, and dried, cold pressed, and slit to obtain a positive electrode tab;
将上述制备的正极极片、负极极片和商用PP/PE/PP三层隔膜(厚度为16μm)制成方形电芯，采用聚合物包装，灌注电解液，电解液为1mol/L LiPF 6/EC+PC+DEC+EMC(体积比1:0.3:1:1)，经化成等工艺后制成3.7Ah的软包锂二次电池。 The positive electrode piece, the negative electrode piece prepared above and the commercial PP/PE/PP three-layer separator (thickness of 16 μm) were made into a square electric core, and the electrolyte was poured into a polymer, and the electrolyte was 1 mol/L LiPF 6 / EC+PC+DEC+EMC (volume ratio 1:0.3:1:1), made into a 3.7Ah soft-packed lithium secondary battery after chemical conversion.
对比例1Comparative example 1
锂离子电池的制备与实施例1的区别仅在于，负极极片采用的负极活性材料为硅纳米颗粒，负极极片的制备过程为：称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％硅纳米颗粒依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片。The preparation of the lithium ion battery differs from that of the first embodiment only in that the negative electrode active material used in the negative electrode piece is silicon nano particles, and the negative electrode piece is prepared by weighing: 7% by mass of polyacrylic acid lithium (PAALi). 3% conductive agent super P and 90% silicon nanoparticles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, and dried, cold pressed, and slit to obtain a negative electrode piece. .
对比例2Comparative example 2
锂离子电池的制备与实施例2的区别仅在于，负极极片的制备过程为：将铜箔为衬底的硅薄膜模切制得尺寸为77mm*58mm的负极极片。The preparation of the lithium ion battery differs from that of the second embodiment only in that the preparation process of the negative electrode tab is as follows: a silicon foil having a copper foil as a substrate is die-cut to obtain a negative electrode tab having a size of 77 mm*58 mm.
对比例3Comparative example 3
锂离子电池的制备与实施例3的区别仅在于，负极极片采用的负极活性材料为氧化亚硅颗粒，负极极片的制备过程为：称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％氧化亚硅纳米颗粒依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片。The preparation of the lithium ion battery differs from that of the third embodiment only in that the negative electrode active material used in the negative electrode tab is oxysulfide particles, and the negative electrode tab is prepared by weighing 7% polyacrylic acid lithium (PAALi). 3% conductive agent super P and 90% oxypropylene nanoparticles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, dried, cold pressed, and slit. Negative pole piece.
对比例4Comparative example 4
锂离子电池的制备与实施例4的区别仅在于，负极极片采用的负极活性材料为硅碳颗粒， 负极极片的制备过程为：称取质量百分含量为7％聚丙烯酸锂(PAALi)、3％导电剂super P和90％硅碳颗粒依次加入到去离子水中，充分搅拌混合均匀，将浆料涂布在铜箔集流体上，烘干、冷压、分切制得负极极片。The preparation of the lithium ion battery differs from that of the fourth embodiment only in that the negative electrode active material used in the negative electrode tab is silicon carbon particles, and the negative electrode tab is prepared by weighing 7% polyacrylic acid (PAALi). 3% conductive agent super P and 90% silicon carbon particles are sequentially added to deionized water, fully stirred and mixed uniformly, and the slurry is coated on a copper foil current collector, and dried, cold pressed, and slit to obtain a negative electrode piece. .
效果实施例Effect embodiment
为对本发明实施例技术方案带来的有益效果进行有力支持，特提供以下测试：In order to strongly support the beneficial effects brought by the technical solutions of the embodiments of the present invention, the following tests are provided:
将本发明实施例1-4与对比例1-4制备得到的锂离子电池进行电化学性能测试：采用0.2C充电/0.2C放电，充电电压范围为0.05-2V，测试电池的首次放电容量，计算出硅基负极材料首次放电效率、首次放电容量，并进一步记录100次循环之后的容量值，计算出容量保持率。具体测试结果如表1所示：The lithium ion batteries prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention were subjected to electrochemical performance tests: a 0.2 C charge/0.2 C discharge was used, and a charging voltage range was 0.05-2 V, and the first discharge capacity of the battery was tested. The first discharge efficiency and the first discharge capacity of the silicon-based negative electrode material were calculated, and the capacity value after 100 cycles was further recorded, and the capacity retention ratio was calculated. The specific test results are shown in Table 1:
表1各实施例及对比例电池电化学性能对比Table 1 Comparison of electrochemical performance of various examples and comparative batteries
Figure PCTCN2019080139-appb-000002
Figure PCTCN2019080139-appb-000002
从表1中的结果可以看出，相比于对比例，采用本发明实施例提供的改性硅基负极材料制备的电池样品在首次放电容量、首次效率和循环性能上都表现出了性能提升，这是由于，本发明实施例提供的改性硅基负极材料，其表面的改性层厚度均匀，改性层的含磺酸基的硅烷偶联剂具有双亲结构，可显著提高无机硅负极表面与有机电解液之间的相容性，能使SEI膜均匀生长，阻止电解液在硅负极表面的持续分解，提供稳定的固液界面，减少副反应，提升循环寿命；同时在电池发生嵌锂反应过程中，磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一，从而可提高负极表面SEI膜的离子电导性，降低界面阻抗，进一步提升硅负极的功率性能和循环稳定性。It can be seen from the results in Table 1 that the battery samples prepared by using the modified silicon-based anode material provided by the embodiment of the present invention exhibit performance improvement in the first discharge capacity, the first efficiency, and the cycle performance, as compared with the comparative examples. The reason is that the modified silicon-based anode material provided by the embodiment of the invention has a uniform thickness of the modified layer on the surface, and the sulfonic acid group-containing silane coupling agent of the modified layer has a parent structure, which can significantly improve the inorganic silicon anode. The compatibility between the surface and the organic electrolyte can uniformly grow the SEI film, prevent the electrolyte from continuously decomposing on the surface of the silicon negative electrode, provide a stable solid-liquid interface, reduce side reactions, and improve cycle life; During the lithium reaction, the sulfonic acid group can react with lithium ions to form lithium sulfonate groups as one of the components of the SEI film, thereby improving the ionic conductivity of the SEI film on the surface of the negative electrode, reducing the interface impedance, and further improving the power performance of the silicon negative electrode. And cycle stability.

Claims (22)

  1. 一种改性硅基负极材料，其特征在于，包括硅基负极材料和设置于所述硅基负极材料表面的改性层，所述改性层包括含磺酸基的硅烷偶联剂，所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合。A modified silicon-based negative electrode material, comprising: a silicon-based negative electrode material and a modified layer disposed on a surface of the silicon-based negative electrode material, the modified layer comprising a sulfonic acid group-containing silane coupling agent, The sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, the sulfonic acid group being attached to an end of the non-hydrolyzable group, A sulfonic acid group-containing silane coupling agent forms a chemical bond with the silicon-based negative electrode material through the hydrolyzable group.
  2. 如权利要求1所述的改性硅基负极材料，其特征在于，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、-OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种。 The modified silicon-based negative electrode material according to claim 1, wherein said sulfonic acid group-containing silane coupling agent comprises three said hydrolyzable groups, and said three hydrolyzable groups are each selected from the group consisting of Any one of -Cl, -OCH 3 , -OCH 2 CH 3 , -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups after hydrolysis The silicon-based negative electrode material is chemically bonded, and the non-hydrolyzable group is selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group.
  3. 如权利要求1或2所述的改性硅基负极材料，其特征在于，所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。The modified silicon-based negative electrode material according to claim 1 or 2, wherein the silicon-based negative electrode material comprises one of silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, silicon alloy or A variety.
  4. 如权利要求1-3任一项所述的改性硅基负极材料，其特征在于，所述硅基负极材料为颗粒，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。The modified silicon-based negative electrode material according to any one of claims 1 to 3, wherein the silicon-based negative electrode material is a particle, and the modified layer is coated on the surface of the silicon-based negative electrode material to form a core shell. In the core-shell structure, the core is the silicon-based anode material, and the shell is the modified layer.
  5. 如权利要求1-3任一项所述的改性硅基负极材料，其特征在于，所述硅基负极材料为薄膜，所述硅基负极材料附着于一衬底上，所述改性层包覆在所述硅基负极材料表面上。The modified silicon-based negative electrode material according to any one of claims 1 to 3, wherein the silicon-based negative electrode material is a thin film, and the silicon-based negative electrode material is attached to a substrate, the modified layer Coated on the surface of the silicon-based negative electrode material.
  6. 如权利要求3所述的改性硅基负极材料，其特征在于，所述硅合金中包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。The modified silicon-based negative electrode material according to claim 3, wherein the silicon alloy comprises one or more of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg.
  7. 如权利要求1所述的改性硅基负极材料，其特征在于，所述改性层的厚度为0.1nm-20nm。The modified silicon-based negative electrode material according to claim 1, wherein the modified layer has a thickness of from 0.1 nm to 20 nm.
  8. 如权利要求1所述的改性硅基负极材料，其特征在于，所述改性层的质量为所述硅基负极材料质量的0.01％-10％。The modified silicon-based negative electrode material according to claim 1, wherein the quality of the modified layer is from 0.01% to 10% by mass of the silicon-based negative electrode material.
  9. 如权利要求1所述的改性硅基负极材料，其特征在于，所述含磺酸基的硅烷偶联剂由巯基硅烷偶联剂经氧化得到。The modified silicon-based negative electrode material according to claim 1, wherein the sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
  10. 一种改性硅基负极材料的制备方法，其特征在于，包括以下步骤：A method for preparing a modified silicon-based anode material, comprising the steps of:
    取硅基负极材料，当所述硅基负极材料为颗粒时，将所述硅基负极材料与含磺酸基的硅烷偶联剂混合均匀，经回流处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；Taking a silicon-based anode material, when the silicon-based anode material is a pellet, the silicon-based anode material is uniformly mixed with a sulfonic acid group-containing silane coupling agent, and is subjected to a reflow treatment to form a coating on the silicon-based anode. a modified layer on the surface of the material to obtain a modified silicon-based anode material;
    当所述硅基负极材料为薄膜时，所述硅基负极材料附着于一衬底上，采用含磺酸基的硅烷偶联剂对所述硅基负极材料进行浸润或涂覆处理，形成包覆于所述硅基负极材料表面的改性层，得到改性硅基负极材料；When the silicon-based negative electrode material is a thin film, the silicon-based negative electrode material is attached to a substrate, and the silicon-based negative electrode material is infiltrated or coated with a sulfonic acid group-containing silane coupling agent to form a package. a modified layer covering the surface of the silicon-based anode material to obtain a modified silicon-based anode material;
    所述含磺酸基的硅烷偶联剂包括硅原子，以及与所述硅原子相连的非水解基团和可水解基团，所述磺酸基连接在所述非水解基团的末端，所述含磺酸基的硅烷偶联剂通过所述可水解基团与所述硅基负极材料形成化学键合，得到所述改性层。The sulfonic acid group-containing silane coupling agent includes a silicon atom, and a non-hydrolyzable group and a hydrolyzable group attached to the silicon atom, and the sulfonic acid group is attached to an end of the non-hydrolyzable group. The sulfonic acid group-containing silane coupling agent is chemically bonded to the silicon-based negative electrode material through the hydrolyzable group to obtain the modified layer.
  11. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，所述含磺酸基的硅烷偶联剂包括三个所述可水解基团，三个所述可水解基团分别选自-Cl、-OCH 3、-OCH 2CH 3、 -OC 2H 4OCH 3、-OSi(CH 3) 3、-OOCCH 3中的任意一种，至少一所述可水解基团经水解后与所述硅基负极材料形成化学键合，所述非水解基团选自C 1-C 20烷基、烷基胺基、酰胺基、C 2-C 20烯基、芳基中的任意一种。 A method of preparing a modified silicon-based negative electrode material according to claim 10, wherein said sulfonic acid group-containing silane coupling agent comprises three said hydrolyzable groups, and said three hydrolyzable groups Any one selected from the group consisting of -Cl, -OCH 3 , -OCH 2 CH 3 , -OC 2 H 4 OCH 3 , -OSi(CH 3 ) 3 , -OOCCH 3 , at least one of the hydrolyzable groups Forming a chemical bond with the silicon-based negative electrode material after hydrolysis, the non-hydrolyzable group being selected from any one of a C 1 -C 20 alkyl group, an alkylamino group, an amide group, a C 2 -C 20 alkenyl group, and an aryl group. One.
  12. 如权利要求10或11所述的改性硅基负极材料的制备方法，其特征在于，所述硅基负极材料包括硅单质、硅氧化物及其复合物、硅碳复合物、硅合金中的一种或多种。The method for preparing a modified silicon-based negative electrode material according to claim 10 or 11, wherein the silicon-based negative electrode material comprises silicon simple substance, silicon oxide and composite thereof, silicon carbon composite, and silicon alloy. One or more.
  13. 如权利要求10-12任一项所述的改性硅基负极材料的制备方法，其特征在于，当所述硅基负极材料为颗粒时，所述改性层包覆于所述硅基负极材料表面形成核壳结构，所述核壳结构中，核为所述硅基负极材料，壳为所述改性层。The method for preparing a modified silicon-based negative electrode material according to any one of claims 10 to 12, wherein when the silicon-based negative electrode material is a particle, the modified layer is coated on the silicon-based negative electrode. The surface of the material forms a core-shell structure in which the core is the silicon-based anode material and the shell is the modified layer.
  14. 如权利要求10-12任一项所述的改性硅基负极材料的制备方法，其特征在于，当所述硅基负极材料为薄膜时，所述改性层包覆在所述硅基负极材料表面上。The method for preparing a modified silicon-based anode material according to any one of claims 10 to 12, wherein when the silicon-based anode material is a film, the modified layer is coated on the silicon-based anode On the surface of the material.
  15. 如权利要求12所述的改性硅基负极材料的制备方法，其特征在于，所述硅合金中包括Fe、Co、Ni、Cu、Zn、Sn、Ge、Al、Mg中的一种或多种元素。The method for preparing a modified silicon-based negative electrode material according to claim 12, wherein the silicon alloy comprises one or more of Fe, Co, Ni, Cu, Zn, Sn, Ge, Al, and Mg. Elements.
  16. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，所述改性层的厚度为0.1nm-20nm。The method of preparing a modified silicon-based negative electrode material according to claim 10, wherein the modified layer has a thickness of 0.1 nm to 20 nm.
  17. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，所述改性层的质量为所述硅基负极材料质量的0.01％-10％。The method for preparing a modified silicon-based negative electrode material according to claim 10, wherein the quality of the modified layer is 0.01% to 10% by mass of the silicon-based negative electrode material.
  18. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，所述含磺酸基的硅烷偶联剂由巯基硅烷偶联剂经氧化得到。The method for producing a modified silicon-based negative electrode material according to claim 10, wherein the sulfonic acid group-containing silane coupling agent is obtained by oxidation of a mercaptosilane coupling agent.
  19. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，在进行所述回流、浸润或涂覆处理之前，先将所述硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。The method for preparing a modified silicon-based negative electrode material according to claim 10, wherein the silicon-based negative electrode material is vacuum dried before the reflowing, wetting or coating treatment, the vacuum drying The temperature is from 60 ° C to 80 ° C and the time is from 4 to 8 hours.
  20. 如权利要求10所述的改性硅基负极材料的制备方法，其特征在于，在进行所述回流、浸润或涂覆处理之后，收集所述改性硅基负极材料，并将所述改性硅基负极材料进行真空干燥，所述真空干燥的温度为60℃-80℃，时间为4-8小时。The method for preparing a modified silicon-based negative electrode material according to claim 10, wherein after said reflowing, wetting or coating treatment, said modified silicon-based negative electrode material is collected and said modified The silicon-based negative electrode material is subjected to vacuum drying at a temperature of from 60 ° C to 80 ° C for a period of from 4 to 8 hours.
  21. 一种锂离子电池，包括正极、负极，以及位于所述正极与所述负极之间的隔膜和电解液，所述负极包括如权利要求1-9任一项所述的改性硅基负极材料。A lithium ion battery comprising a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode, the negative electrode comprising the modified silicon-based negative electrode material according to any one of claims 1-9 .
  22. 如权利要求21所述的锂离子电池，其特征在于，在电池发生嵌锂反应过程中，所述磺酸基可与锂离子反应生成磺酸锂基团作为SEI膜的成分之一。The lithium ion battery according to claim 21, wherein the sulfonic acid group reacts with lithium ions to form a lithium sulfonate group as one of components of the SEI film during a lithium insertion reaction of the battery.
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