WO2023208007A1 - Composite material, preparation method therefor and application thereof - Google Patents
Composite material, preparation method therefor and application thereof Download PDFInfo
- Publication number
- WO2023208007A1 WO2023208007A1 PCT/CN2023/090709 CN2023090709W WO2023208007A1 WO 2023208007 A1 WO2023208007 A1 WO 2023208007A1 CN 2023090709 W CN2023090709 W CN 2023090709W WO 2023208007 A1 WO2023208007 A1 WO 2023208007A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- coating layer
- composite material
- core
- ion gel
- polymer
- Prior art date
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- 239000002131 composite material Substances 0.000 title claims abstract description 111
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 239000011162 core material Substances 0.000 claims abstract description 101
- 239000007773 negative electrode material Substances 0.000 claims abstract description 65
- 239000002608 ionic liquid Substances 0.000 claims abstract description 64
- 229920000642 polymer Polymers 0.000 claims abstract description 64
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 50
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 50
- 239000007774 positive electrode material Substances 0.000 claims abstract description 26
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 22
- 239000011247 coating layer Substances 0.000 claims description 126
- 150000002500 ions Chemical class 0.000 claims description 118
- -1 imidazole cations Chemical class 0.000 claims description 57
- 239000000463 material Substances 0.000 claims description 42
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- 239000002904 solvent Substances 0.000 claims description 37
- 238000000034 method Methods 0.000 claims description 31
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- 239000002243 precursor Substances 0.000 claims description 22
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- 125000004435 hydrogen atom Chemical group [H]* 0.000 claims description 8
- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 claims description 8
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- NQRYJNQNLNOLGT-UHFFFAOYSA-N tetrahydropyridine hydrochloride Natural products C1CCNCC1 NQRYJNQNLNOLGT-UHFFFAOYSA-N 0.000 claims description 5
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- ZZVZYACHEMVZGV-UHFFFAOYSA-N 1-methylimidazole 1,1,1-trifluoro-N-(trifluoromethylsulfonyl)methanesulfonamide Chemical compound Cn1ccnc1.FC(F)(F)S(=O)(=O)NS(=O)(=O)C(F)(F)F ZZVZYACHEMVZGV-UHFFFAOYSA-N 0.000 description 1
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- 239000003273 ketjen black Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- XIXADJRWDQXREU-UHFFFAOYSA-M lithium acetate Chemical compound [Li+].CC([O-])=O XIXADJRWDQXREU-UHFFFAOYSA-M 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 229910002102 lithium manganese oxide Inorganic materials 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- 229910002096 lithium permanganate Inorganic materials 0.000 description 1
- HPGPEWYJWRWDTP-UHFFFAOYSA-N lithium peroxide Chemical compound [Li+].[Li+].[O-][O-] HPGPEWYJWRWDTP-UHFFFAOYSA-N 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 description 1
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 238000007500 overflow downdraw method Methods 0.000 description 1
- 150000002927 oxygen compounds Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920000768 polyamine Polymers 0.000 description 1
- 125000003367 polycyclic group Chemical group 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000005076 polymer ester Substances 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920005862 polyol Polymers 0.000 description 1
- 150000003077 polyols Chemical class 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229960003351 prussian blue Drugs 0.000 description 1
- 239000013225 prussian blue Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000002153 silicon-carbon composite material Substances 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
-
- 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
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- 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
- This application relates to the field of battery technology, specifically composite materials and their preparation methods and applications.
- Lithium-ion batteries have been widely used in portable electronic products such as mobile phones and laptops, as well as new energy vehicles.
- the energy density of lithium-ion batteries based on traditional graphite anodes is close to the ceiling and can no longer meet people's growing needs for battery life and standby.
- Silicon-based and phosphorus-based anode materials with higher theoretical specific capacities are considered to be effective ways to break through the high energy density of lithium secondary batteries.
- negative electrode materials such as silicon-based and phosphorus-based are prone to large volume changes during charging and discharging, leading to pulverization of negative electrode material particles and deteriorating electrochemical properties such as battery cycle performance.
- the inorganic carbon coating layer has poor toughness and insufficient adhesion, and cannot withstand it for a long time.
- the volume change of the anode material during the process of deintercalating lithium although the toughness of the polymer coating is good, its ionic conductivity is poor, resulting in a high interface resistance of the material, which is not conducive to the capacity development of the anode material and reduces the rate performance.
- no solution has been found that can effectively solve the problem of lithium expansion in anode materials without reducing its capacity and rate performance.
- embodiments of the present application provide a composite material with an ion gel coating layer to improve the stability and electrochemical performance of the core material.
- the first aspect of the embodiment of the present application provides a composite material, including a core and a coating layer coating the core, wherein the core includes a negative active material, a positive active material, or a lithium replenishing agent, and the
- the coating layer includes an ion gel, the ion gel includes a polymer and an ionic liquid, and the ionic liquid is dispersed in a three-dimensional network structure formed by the polymer.
- the core is covered with a coating layer containing ion gel.
- the coating layer is a solid soft material with good toughness, certain adhesion and excellent ionic conductivity.
- the core is an anode active material, it can better withstand the volume change of the anode active material during the process of deintercalating lithium and expand/contract with it without reducing the rate performance of the core material and facilitating capacity development.
- the coating layer is not easy to be damaged/ fallen off, and the overall composite material is not easy to fall off from the pole piece, thereby improving the cycle stability of the negative active material.
- the adhesiveness and excellent ionic conductivity of the ion gel coating also help it maintain a strong binding force with the core without affecting the electrochemical performance of the core.
- the adhesiveness and excellent ionic conductivity of the ion gel coating also help it maintain a strong binding force with the core without affecting the electrochemical performance of the core.
- its good hydrophobicity can also improve the water and oxygen stability of the core material and the slurry stability during the pulping process.
- the thickness of the coating layer is 5nm-50nm.
- An ion gel coating of appropriate thickness can ensure that it can stably perform the functions of the coating (such as providing a buffer for the volume expansion of the core material and ensuring the storage or processing of the core). stability, etc.) without affecting the electrochemical performance of the core material due to its excessive thickness.
- the mass proportion of polymer is 5%-50%, and the mass proportion of ionic liquid is 50%-95%. This can ensure the formation of an ion gel without obvious macroscopic phase separation, and the strength of the ion gel will not be too high, with good tensile properties and excellent bonding properties.
- the polymer includes structural units represented by formula (I):
- R 1 is selected from hydrogen atom, fluorine atom or methyl group
- R 2 is selected from hydrogen atom, fluorine atom, methyl group, fluoromethyl, -(CH 2 ) a -Z-, where a is 0-6 is an integer
- Z is selected from -COOH, -COOLi, -COONa, -COOK, -(CH 2 CH 2 O) n H, -(CH 2 CH 2 O) n CH 3 , -COOR 3 , -CONH 2 , - CONH(R 4 ), -CON(R 5 )(R 6 );
- R 3 , R 4 , R 5 , R 6 are independently selected from C 1-6 alkyl groups, and each occurrence of n is independently selected from 1- An integer of 20.
- the polymer in the ion gel coating layer has such structural units, the polymer has greater polarity and can be smoothly dissolved in the ionic liquid to obtain an ion gel without obvious macroscopic phase separation; in addition, it can also be Adjust R 1 , R 1 and the ionic liquid to realize the adhesion performance of the ion gel to different coated core materials.
- the number average molecular weight of the polymer is 1 kDa-1000 kDa.
- the ion gel layer containing such a polymer can have high tensile strength and adhesion, and ensure good dispersion of the polymer in the ionic liquid matrix.
- the cations in the ionic liquid include alkyl-substituted imidazole cations, alkyl-substituted pyrrole cations, alkyl-substituted pyridine cations, alkyl-substituted thiazole cations, alkyl-substituted cations, One or more of piperidine cations, alkyl ammonium cations, and alkyl phosphonium cations.
- the ionic conductivity of the material of the coating layer at room temperature is above 10 -4 S ⁇ cm -1 .
- the breaking elongation of the coating layer is above 100%, and the breaking strength is in the range of 0.5MPa-5MPa.
- the coating layer further includes one or more of a conductive agent, a metal salt of active metal ions, and a surfactant.
- the coating layer also has a carbonized layer containing doping elements, wherein the doping elements are derived from the ionic liquid.
- the existence of the doped carbonization layer can improve the conductivity of the composite material.
- the second aspect of the embodiments of this application provides a method for preparing a composite material, which includes the following steps:
- the core material includes a negative active material, a positive active material, or a lithium replenishing agent;
- the solvent in the mixed material is removed. During the removal of the solvent, a coating layer containing ion gel is formed on the surface of the core material to obtain a composite material.
- the above preparation method further includes: heat treating the solid material obtained after removing the solvent at a temperature of 50-80°C. Heat treatment can enhance the fluidity of the ion gel on the surface of the core material and improve its coating uniformity.
- the above preparation method further includes: calcining the composite material at high temperature to carbonize part of the ion gel coating layer. In this way, a doped carbonized layer can be obtained outside the ion gel coating layer, which is beneficial to improving the conductivity of the composite material.
- the preparation method of the composite material in the embodiment of the present application has a simple process, is easy to operate, and is suitable for large-scale production. Moreover, in the composite material prepared by the above preparation method, the coating layer containing ion gel has certain adhesiveness and good tensile properties.
- the third aspect of the embodiment of the present application also provides an electrode pole piece, the positive electrode piece includes the composite material described in the first aspect of the embodiment of the present application.
- the electrode piece can be a negative electrode piece or a positive electrode piece.
- the negative electrode sheet contains the above-mentioned composite material whose core is the negative electrode active material, the negative electrode sheet is less likely to pulverize and fall off during battery recycling, and has better cycle performance.
- the fourth aspect of the embodiment of the present application also provides a secondary battery, including the electrode pole piece described in the third aspect of the embodiment of the present application.
- the secondary battery may be a lithium secondary battery, other secondary batteries, or the like.
- Secondary batteries using electrode plates containing the above composite materials have better cycle stability and better rate performance, and can better meet the requirements of consumer electronic equipment, power vehicles, etc. for long cycle life and high energy density of secondary batteries. needs.
- the fifth aspect of the embodiment of the present application provides an electronic device, which includes the secondary battery described in the fourth aspect of the present application.
- the electronic device can improve the user experience and market competitiveness of the product.
- Figure 1 is a schematic structural diagram of a composite material provided by an embodiment of the present application.
- Figure 2 is a schematic structural diagram of a lithium secondary battery provided by an embodiment of the present application.
- FIG. 3 is a schematic structural diagram of an electronic device provided by an embodiment of the present application.
- FIG. 4 is another schematic structural diagram of an electronic device provided by an embodiment of the present application.
- Figure 5 shows the surface micromorphology and energy spectrometer elemental analysis results of silicon oxide in Example 1 of the present application before coating (a) and after coating (b).
- FIG. 1 is a schematic structural diagram of a composite material provided in an embodiment of the present application.
- the composite material 100 includes a core 10 and a coating layer 20 covering the core 10, wherein the core 10 includes an anode active material, a cathode active material, or a lithium replenishing agent, and the coating layer 20 includes an ion gel.
- Glues include polymers and ionic liquids. The ionic liquids are dispersed in the three-dimensional network structure formed by the polymer.
- the coating layer 20 in this application includes an ion gel composed of a matrix ionic liquid and a polymer network skeleton.
- the ionic liquid is evenly dispersed in the polymer network structure.
- There is no macroscopic phase separation in the ion gel which is A solid soft material with good toughness (such as good tensile properties) and certain adhesion. It can be firmly coated on the surface of the core material to form a stable coating layer and give the coating layer 20 a certain deformation. ability.
- the coating layer 20 can expand/contract along with the volume change of the anode active material particles during the lithium deintercalation and deintercalation process, and the coating layer 20 is not easy to be damaged/fall off, thereby ensuring The particle integrity of the core anode material during the battery cycle can permanently improve its cycle stability and solve its cycle diving problem.
- the adhesiveness of the ion gel also facilitates the bonding of the composite material 100 to the adhesive in the electrode piece, improves the bonding strength of the composite material 100 on the electrode piece, and prevents the composite material 100 from being removed from the electrode piece during the volume expansion process. Fall off and become ineffective.
- the existence of ionic liquids with excellent ionic conductivity makes the ionic conductivity of the coating layer 20 higher and the interface resistance of the composite material 100 lower, which is conducive to deep lithium embedding, improving the first-efficiency capacity of the core 10, and also It can improve the conductivity of lithium ions on the surface of the composite material 100 without affecting the rate performance of the core 10 and improve the material fast charging capability.
- the ion gel coating layer 20 serves as an artificial SEI layer (solid electrolyte interface), which can isolate the direct contact between the core material and the electrolyte, stabilize the interface, and reduce side reactions with the electrolyte. Therefore, using an ion gel with good toughness, adhesion and high electrochemical properties as the coating layer can solve the volume expansion problem of the core and improve its cycle without reducing the rate performance and capacity of the core material. stability.
- the above-mentioned coating layer 20 is hydrophobic and can isolate water and oxygen, which can improve the stability of the core positive material in air and water, extend the stable storage time, and prevent deliquescence and water absorption.
- the material structure changes and the performance decreases; in addition, during the stirring and pulping process of the cathode slurry, the coating layer 20 also helps to stabilize the slurry to avoid water absorption and deterioration caused by the high residual alkali content on the surface of the cathode active material. Problems such as gelation of the slurry and difficulty in coating.
- the coating layer 20 has good ionic conductivity and will not affect the rate performance and capacity of the core cathode material. Moreover, because it has a certain viscosity, it can improve the relationship between the composite cathode material and the binder. The bonding strength.
- the coating layer 20 also helps to improve the storage stability of the core and the stability of the slurry during the pulping process without affecting the lithium replenishing effect.
- the coating layer 20 can cover the entire surface of the core 10 (as shown in FIG. 1 ), or can only cover a part of the surface of the core 10 . Specifically, it can continuously cover a part of the surface of the core 10 (for example, in A part of the surface of the core 10 has an island-shaped coating layer 20), or the surface of the core 10 is non-continuously coated, for example, a plurality of island-shaped coatings are spaced apart.
- the above-mentioned negative active material may include one or more of carbon-based materials, silicon-based materials, phosphorus-based materials, tin-based materials, sulfur-based materials, etc.
- negative electrode active materials with large volume expansion effects such as silicon-based materials, phosphorus-based materials, and tin-based materials, particularly need to be covered by the above-mentioned coating layer 20 .
- Carbon-based materials can include one or more of graphite (such as natural graphite, artificial graphite), soft carbon, hard carbon, anthracite, mesophase carbon microspheres, etc.; silicon-based materials can include elemental silicon, silicon-based alloys, silicon One or more of oxides (can be represented by SiOx, 0 ⁇ x ⁇ 2, for example, 0.9 ⁇ x ⁇ 1.7), silicon-carbon composite materials, etc.; phosphorus-based materials can include phosphorus elements (such as red phosphorus, black phosphorus, One or more of white phosphorus), phosphorus-carbon composite materials, etc.; tin-based materials can include one or more of elemental tin, tin alloy, tin oxide, etc.
- graphite such as natural graphite, artificial graphite
- silicon-based materials can include elemental silicon, silicon-based alloys, silicon One or more of oxides (can be represented by SiOx, 0 ⁇ x ⁇ 2, for example, 0.9 ⁇ x ⁇ 1.7), silicon-carbon composite materials,
- the positive active material can be selected according to the active ions that the specific secondary battery relies on for energy storage.
- Active ions may include lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, zinc ions, etc.
- the positive active material is a composite oxide of lithium, including but not limited to lithium cobalt oxide (such as lithium cobalt oxide LiCoO 2 ), lithium nickel oxide (such as lithium nickel oxide LiNiO 2 ) , Lithium manganese oxide (such as lithium manganate LiMnO 2 , lithium permanganate), lithium titanium oxide (such as lithium titanate), lithium iron phosphorus oxide (such as lithium iron phosphate, lithium iron manganese phosphate, etc.), lithium nickel Cobalt oxide (such as lithium nickel cobalt oxide LiNi a Co 1-a O 2 ), lithium nickel manganese oxide (such as lithium nickel manganese oxide LiNi a Mn 1-a O 2 ), nickel cobalt polyvalent oxide (such as nickel cobalt oxide
- the positive active material may include one or more of sodium-containing composite oxide, Prussian blue, Prussian white, etc.
- the positive active material may be a potassium-containing composite oxide.
- the cathode active material can be a composite oxide containing magnesium. The above-mentioned cathode active material can be undoped or doped and modified, and can undergo surface coating, pre-lithium treatment, etc. . Wherein, the particle size of the cathode active material may be in the range of 10 nm-100 ⁇ m.
- the above-mentioned lithium replenishing agent can be lithium-rich materials, including but not limited to LiCoO 2 , Li 6 CoO 4 , Li 2 MnO 3 , Li 2 CuO 2 , Li 2 NiO 2 , Li 5 FeO 4 , One of Li 2 CO 3 (lithium carbonate), Li 2 C 2 O 4 (lithium oxalate), Li 2 O (lithium oxide), Li 2 O 2 (lithium peroxide), CH 3 COOLi (lithium acetate), etc. or more.
- These lithium replenishing agents can be undoped or modified by doping, and can undergo surface coating, prelithiation treatment, etc.
- the particle size of the lithium supplement can be in the range of 10nm-100 ⁇ m.
- the thickness of the coating layer 20 is 5 nm-50 nm.
- the thickness of the cladding layer 20 can be determined according to the size of the core
- the coating layer 20 of appropriate thickness can ensure that it can stably perform the functions of the coating layer (such as providing a buffer for the volume expansion of the core material, ensuring the storage or processing stability of the core, etc.), and at the same time, the coating layer 20 has almost no Electrochemical activity, without excessively increasing the migration distance of lithium ions in the coating layer and reducing the gram capacity of the composite material due to its excessive thickness.
- the thickness of the cladding layer 20 may be 8 nm, 10 nm, 15 nm, 20 nm, 22 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 48 nm, etc. In some embodiments, the thickness of the cladding layer 20 is 5 nm-30 nm.
- the mass of the coating layer 20 accounts for 0.5%-1% of the mass of the core 10 .
- the mass proportion of the cladding layer 20 is within this range, which helps to form a cladding layer 20 with appropriate thickness and high coating integrity on the surface of the core material, and at the same time avoids excessive cladding layer material from reducing the weight of the composite material 100 capacity.
- the mass of the cladding layer 20 may account for 0.55%, 0.6%, 0.7%, 0.8%, 0.9%, or 0.95% of the mass of the core 10 .
- the mass proportion of polymer in the ion gel, is 5%-50%, and the mass proportion of ionic liquid is 50%-95%.
- the mass proportion of ionic liquid in the ion gel is controlled to be more than 50% to ensure the formation of an ion gel without obvious macroscopic phase separation; the mass proportion of polymer in the ion gel is below 50%, which can Ensure that the strength of the ion gel is not too high, has good tensile properties, and has excellent bonding properties, which is conducive to the expansion/shrinking of the core negative active material without being damaged and falling off during the process of deintercalation of lithium.
- the ion gel uses ionic liquid as the matrix.
- the matrix has good stability and is not easy to dissolve or dissolve. Volatilization ensures that the ion gel coating layer can perform its coating function normally and will not cause side reactions of the battery due to matrix volatilization during battery operation.
- the mass proportion of ionic liquid in the ion gel can be 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.
- the mass proportion of the polymer in the ion gel The mass proportion can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%.
- the mass proportion of ionic liquid in the ion gel is 60%-75%.
- the mass proportion of polymer in the ion gel is 25%-40%.
- the polymer includes polyacrylate structural units represented by formula (I):
- R 1 is selected from hydrogen atom, fluorine atom or methyl group
- R 2 is selected from hydrogen atom, fluorine atom, methyl group, fluoromethyl, -(CH 2 ) a -Z-, where a is 0-6 is an integer
- Z is selected from -COOH, -COOLi, -COONa, -COOK, -(CH 2 CH 2 O) n H, -(CH 2 CH 2 O) n CH 3 , -COOR 3 , -CONH 2 , - CONH(R 4 ), -CON(R 5 )(R 6 );
- R 3 , R 4 , R 5 , R 6 are independently selected from C 1-6 alkyl groups, and each occurrence of n is independently selected from 1- An integer of 20.
- the polymer with the structural unit represented by formula (I) has greater polarity and can be smoothly dissolved in the ionic liquid.
- an ion gel without obvious macroscopic phase separation is obtained; in addition, the bonding performance of the ion gel to different coated core materials can also be achieved by regulating R 1 , R 1 and the ionic liquid.
- the above-mentioned polymer may contain a structural unit represented by formula (I) (in this case, the polymer ester is a homopolymer); or may contain a variety of different structures represented by formula (I) structural unit (the polymer at this time is a copolymer).
- the above-mentioned polymer can be obtained by polymerizing the corresponding monomer of the polymer in the presence of an initiator.
- the number average molecular weight of the polymer is 1 kDa-1000 kDa (Da is the abbreviation of Dalton).
- the molecular weight of the polymer in the ion gel is within this range, which is beneficial to the ion gel layer taking into account high tensile strength and adhesion, and ensuring good dispersion of the polymer in the ionic liquid matrix.
- the polymer in the ion gel, can be cross-linked through physical effects to form a three-dimensional network structure. Furthermore, it can also be cross-linked through chemical bonds to form a three-dimensional network structure.
- R 2 is -(CH 2 ) a -COOH-, -(CH 2 ) a -COOLi-, -(CH 2 ) a -COONa-, -(CH 2 ) a -COOK-
- polymers with structural units represented by formula (I) can be chemically cross-linked to form a polymer network structure.
- the cations in the ionic liquid include one or more of nitrogen-containing heterocyclic cations, alkylammonium cations, and alkylphosphonium cations.
- the nitrogen-containing heterocyclic cations may include alkyl-substituted imidazole cations, alkyl-substituted pyrroles cations, alkyl-substituted pyridine cations, alkyl-substituted thiazole cations, and alkyl-substituted piperidine cations. of one or more.
- each ionic liquid is liquid at room temperature, has high ionic conductivity, high chemical stability and thermal stability, wide electrochemical window, and good stability in the electrode, so that it can The core material exists stably on the surface without reducing the electrical performance of the core.
- the anions in the ionic liquid may include hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonamide, bistrifluoromethanesulfonimide, biscyanoimide, acetate, trifluoromethanesulfonamide, One or more of fluoroacetate, inorganic acid, and halide ions. It can be understood that there can be one or more ionic liquids (ie, two or more) in the ion gel, and the anions and cations of each ionic liquid can be independently selected from the above-mentioned range.
- the alkyl group in imidazole cations, pyrrole cations, pyridine cations, thiazole cations, piperidine and other nitrogen heterocyclic cations, the alkyl group can replace the hydrogen atom on the ring hetero N atom. Furthermore, the alkyl group can also replace the hydrogen atom on the ring carbon atom.
- the alkyl group may be a straight chain or branched chain alkyl group having 1 to 6 carbon atoms.
- the alkylammonium cation may specifically be a quaternary ammonium salt cation (ie, a nitrogen ion substituted by four alkyl groups), and the alkylphosphonium cation may specifically be a quaternary phosphonium salt cation.
- the ionic conductivity of the coating layer 20 is relatively high.
- the ionic conductivity of the material of the coating layer 20 at room temperature is above 10 -4 S ⁇ cm -1 .
- the material of the cladding layer 20 has an ionic conductivity in the range of 10 -4 S ⁇ cm -1 to 5 ⁇ 10 -2 S ⁇ cm -1 at room temperature.
- the breaking elongation of the coating layer 20 is above 100%, and the breaking strength is in the range of 0.5MPa-5MPa.
- Elongation at break and strength at break are both indicators of the tensile properties of materials.
- the elongation at break is an indicator that describes the plastic properties of the material. Specifically, it refers to the ratio of the plastic elongation length ⁇ L of the sample when it is stretched and broken to the original length L of the sample. The higher elongation at break reflects that the ion gel coating layer of the present application has good toughness and excellent tensile properties.
- the elongation at break of the coating layer 20 is in the range of 100%-500%, for example, it may be 150%, 200%, 250%, 300%, 350%, 400% or 450%, etc.
- Fracture strength also known as "tensile strength” refers to the ratio of the tensile force when a material breaks to the fracture cross-sectional area. The higher fracture strength reflects that the ion gel coating layer of the present application has better toughness and excellent tensile properties.
- the above-mentioned coating layer 20 is formed on the surface of the core material by using a precursor solution containing a polymer and an ionic liquid through a co-solvent evaporation method.
- the ion gels provided in the embodiments of the present application have higher toughness and are not too rigid.
- the coating layer 20 may also include one or more auxiliary agents among conductive agents, metal salts of active metal ions, and surfactants.
- the conductive agent helps to improve the electronic conductivity of the coating layer 20
- the metal salt helps to improve the ionic conductivity of the coating layer 20
- the surfactant helps to increase the surface energy of the coating layer and increase the size of the coating layer.
- the conductive agent may include one or more of conductive carbon black, carbon nanotubes, graphene, graphite, amorphous carbon, etc.
- the metal ions of the metal salt may include one or more of lithium ions, sodium ions, potassium ions, magnesium ions, etc.
- the anions may include hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonamide, bistrifluoro One or more of methanesulfonimide, dicyanimide, acetate, trifluoroacetate, inorganic acid, halogen ions, etc.
- Surfactants may include one or more of amphiphilic organic small molecules, amphiphilic non-ionic polymers, amphiphilic ionic polymers, etc. The types and contents of the conductive agent, metal salt, and surfactant added can be adjusted according to the specific composition system and application scenarios of the composite material 100 mentioned above.
- the coating layer 20 also has a carbonized layer containing doping elements, and the doping elements are derived from the ionic liquid.
- the carbonized layer can be obtained by carbonizing part of the coating layer 20, for example, at 450-650°C. Carbonization is achieved by calcination.
- the doping element may be one or more of N, S, P, and halogen elements.
- the composite materials with ion gel coating layers provided in the embodiments of the present application have better electrical properties, mechanical properties and Good stability, etc.
- the embodiments of this application also provide a method for preparing composite materials, including the following steps:
- the core material includes a negative active material, a positive active material, or a lithium replenishing agent;
- ionic liquids and polymers can be found in the previous description of this application and will not be described again here.
- polymers are directly used instead of polymer monomers in preparing the precursor solution. This can avoid the ion gel formed by in-situ cross-linking of polymer monomers and ionic liquids from being too rigid, insufficient in adhesion, and unable to have Better tensile and fatigue resistance, thereby avoiding the inability to maintain good coating integrity during multiple cyclic volume changes of the negative active material coated by the ion gel; in addition, a polymer and ionic liquid are used to prepare the precursor It is also beneficial to the dispersion uniformity of the polymer in the subsequently formed ion gel coating layer.
- the mass ratio of the polymer to the ionic liquid is in the range of 1: (1-19).
- the mass ratio between the two is within this range, which can ensure the formation of an ion gel without obvious macroscopic phase separation during the subsequent solvent removal process and ensure the tensile properties of the ion gel.
- the mass ratio of polymer to ionic liquid is in the range of 1: (1.5-3). At this time, the ion gel formed by using the two can better balance good tensile properties and bonding properties.
- the solvent used should be able to dissolve the polymer and ionic liquid.
- the solvent may include but is not limited to methanol, ethanol, dichloromethane, chloroform, acetone, tetrahydrofuran, dioxygen, etc.
- the mass ratio of the sum of the masses of the polymer and the ionic liquid to the solvent is in the range of 1: (5-20).
- step S01 the polymer and ionic liquid are dissolved in the solvent, and the stirring time used can be 5-12 hours; the stirring speed during the stirring process can be 300-500 rpm.
- the ion gel precursor solution in step S01 may also contain auxiliary agents, where the auxiliary agents include but are not limited to the aforementioned conductive agents, metal salts of active metal ions, surfactants, etc. of one or more.
- the mass ratio of the sum of the masses of the polymer and the ionic liquid to the additive may be in the range of 1: (0.1-0.5).
- the core material is usually a negative active material, a positive active material or a lithium replenishing agent.
- Mixing the core material and the ion gel precursor solution allows the surface of the core material to adsorb the ion gel precursor solution. Based on the fluidity of the precursor solution, it can penetrate into the tiny gaps on the surface of the core material.
- the coating layer formed after step S03 can improve the interface properties of the core material, increase its active sites, and increase the specific capacity.
- the mass ratio of the sum of the masses of the polymer and the ionic liquid to the core material may be in the range of 1: (100-200). This helps to form an ion gel coating layer with appropriate thickness and high coating integrity on the surface of the core material after the processing in step S03, while avoiding reducing the gram capacity of the overall composite material.
- the mixing method of the core material and the ion gel precursor solution may be a mechanical stirring method, a high-energy ball milling method, or a mechanical fusion method.
- mechanical stirring is used to achieve the mixing, where the stirring can be performed at 20-60°C; the stirring time can be 3h-15h.
- the stirring speed can be controlled within the range of 300-500rpm.
- the core material can be directly mixed with the ion gel precursor solution in the form of a powder material, or can be added in the form of a dispersion formed with a solvent.
- the core material and the solvent are first stirred and mixed (the stirring time is, for example, 1-2 h), to obtain into the core material dispersion; and then stir and mix with the ion gel precursor solution (the stirring time is, for example, 2-12 hours).
- the above-mentioned conductive agents, metal salts, surfactants and other additives can also be added together with the core material.
- the additives are added to the dispersion of the core material.
- the solvent can be removed at a certain temperature to allow the solvent to volatilize.
- the temperature for removing the solvent can be determined according to the volatilization temperature of the specific solvent.
- the solvent removal methods can include drying with a rotary evaporator, stirring in a water bath, drying in an oven, etc. These solvent removal methods can ensure that most or all of the solvent in the mixed material is removed, and a basically dry powder sample is obtained.
- the method further includes: heat treating the solid material obtained after removing the solvent at a temperature of 50-80°C.
- Heat treatment can enhance the fluidity of the ion gel on the surface of the core material and improve the coating uniformity of the coating layer.
- the time of heat treatment can be 8-24h.
- the heat treatment can be carried out by vacuum drying in a vacuum oven.
- most of the solvent in the mixed material can be dried using a rotary evaporator and then vacuum dried in a vacuum oven to obtain a composite material with high dryness.
- the obtained crude composite material can be screened to obtain the composite material with the required particle size.
- the size of the composite material obtained by screening is basically equivalent to the size of the micron-level core material raw material used.
- the composite material prepared in step S03 can also be subjected to high-temperature calcination treatment to carbonize part of the ion gel coating layer.
- the obtained composite material includes a core, an ion gel coating layer surrounding the core, and a carbonized layer containing doped elements (ie, an inorganic carbon coating layer) surrounding the ion gel coating layer.
- the preparation method of the composite material described in the embodiments of the present application can form a stable ion gel coating layer on the surface of the core material by mixing the precursor solution of polymer and ionic liquid with the core material, and then evaporating the solvent.
- the coating layer has strong bonding force with the core material and the coating layer has high toughness, which can well improve the interface properties of the core material. For example, it can improve the volume expansion problem of the core negative active material, improve the core positive active material or the core supplement. Water and oxygen stability of lithium agent, etc.
- the above preparation method of composite materials has simple process, easy operation, and is suitable for large-scale production.
- the obtained composite materials have high structural stability and good electrochemical properties.
- the embodiment of the present application also provides an electrode pole piece for a battery, the electrode pole piece contains the composite material mentioned in the embodiment of the present application.
- the electrode piece may be a negative electrode piece or a positive electrode piece.
- the negative electrode sheet includes the above-mentioned negative active material with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is a negative active material), which can be called a "composite negative electrode material".
- the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector.
- the negative electrode material layer includes the aforementioned composite negative electrode material, a binder, and an optional conductive agent. At this time, the negative electrode particles are less likely to pulverize and fall off during the battery charge and discharge cycle.
- the positive electrode sheet includes the above-mentioned positive electrode active material with an ion gel coating layer on the surface (that is, the aforementioned composite material 100 in which the core 10 is a positive electrode active material, which may be referred to as a "composite positive electrode material”), and/ Or a lithium replenishing agent with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is a lithium replenishing agent can be called a "composite lithium replenishing agent").
- the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector.
- the positive electrode material layer includes the aforementioned composite positive electrode material, a binder, and a conductive agent.
- the cathode material layer may also contain the aforementioned composite lithium replenishing agent.
- the side of the positive electrode material layer facing away from the positive electrode current collector also has an additive layer, and the additive layer contains the aforementioned composite lithium replenishing agent, binder and conductive agent.
- the surface of the positive electrode active material or lithium replenishing agent has the aforementioned ion gel coating layer, during the process of preparing the positive electrode slurry used for the positive electrode material layer and the additive slurry used for the additive layer, these slurries are not likely to gel. , the coating quality is less affected.
- these cladding layers The matrix is a non-volatile ionic liquid rather than volatile water or organic solvent. During the drying process of the pole piece, the integrity of the coating layer will not be damaged due to matrix volatilization. Of course, the battery will also reduce the Side reactions caused by moisture, etc.
- the binder may specifically include but is not limited to polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), sodium carboxymethylcellulose (CMC), polyacrylic acid (PAA), polyacrylate, polyacrylamide (PAM), polyimide (PI), etc.
- PTFE polytetrafluoroethylene
- PVDF polyvinylidene fluoride
- CMC sodium carboxymethylcellulose
- PAA polyacrylic acid
- PAM polyacrylate
- PAM polyacrylamide
- PI polyimide
- the conductive agent may specifically include, but is not limited to, one or more of acetylene black, Ketjen black, Supper P conductive carbon black, graphite, graphene, carbon nanotubes, carbon fiber, amorphous carbon, etc.
- the negative electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the negative electrode material layer.
- Exemplary metal foils may be copper foil, carbon-coated copper foil or copper-plated film, and exemplary alloy foils may be stainless steel foils, copper alloy foils, etc.
- the positive electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the positive electrode material layer.
- Exemplary metal foils may be aluminum foil, carbon-coated aluminum foil or aluminum-coated films, and exemplary alloy foils may be stainless steel foils, aluminum alloy foils or carbon-coated stainless steel foils.
- an embodiment of the present application also provides a secondary battery 200, which includes the above-mentioned electrode pole piece.
- the secondary battery 200 may be a lithium secondary battery, a sodium secondary battery, a potassium secondary battery, a magnesium secondary battery, or the like.
- the secondary battery 200 is a lithium secondary battery.
- the lithium secondary battery includes a positive electrode 201, a negative electrode 202, a separator 203 and an electrolyte 204 disposed between the positive electrode 201 and the negative electrode 202, as well as corresponding communication accessories and circuits.
- the positive electrode 201 is the positive electrode piece mentioned in the embodiment of this application
- the negative electrode 202 includes the negative electrode piece mentioned in the embodiment of this application.
- the separator 203 can be a polymer separator, non-woven fabric, etc., including but not limited to single-layer PP (polypropylene) film, single-layer PE (polyethylene) film, double-layer PP/PE, double-layer PP/PP And three-layer PP/PE/PP and other separators.
- the electrolyte 204 includes an active ion salt (specifically, a lithium salt) and an organic solvent.
- the organic solvent may include but is not limited to one or more of carbonate solvents, carboxylate solvents, and ether solvents.
- lithium ions are detached from the positive electrode 201 and migrate to the negative electrode 202 through the electrolyte 204 and the separator 203.
- electrons flow from the positive electrode to the negative electrode from the external circuit, and the electric energy is stored; during discharge , the lithium ions are detached from the negative electrode 202 and return to the positive electrode 201 through the electrolyte 204 and the separator 203.
- the corresponding electrons migrate from the negative electrode to the positive electrode through the external circuit, releasing electric energy to the outside.
- the capacity of the positive and negative electrodes is crucial to improving the energy density of the entire cell of the secondary battery.
- the negative electrode 202 of the lithium secondary battery 200 of the present application contains the above-mentioned negative active material with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is the negative active material).
- the negative active material has a higher theoretical capacity. (for example, when it is a silicon-based or phosphorus-based negative electrode active material), the composite material of the embodiment of the present application can improve its cycle stability, reduce volume expansion, and improve rate performance while maintaining a high capacity of this type of negative electrode material. It will help improve the capacity, life, safety and fast charging capabilities of current lithium batteries.
- the positive electrode 201 of the lithium secondary battery 200 contains the above-mentioned positive active material or lithium replenishing agent with an ion gel coating layer on the surface, during the preparation process of the positive electrode sheet of the battery, the slurry stability during the pulping process Good, not easy to gel.
- the existence of the coating layer can reduce the structural damage to the positive active material or lithium replenishing agent caused by trace amounts of moisture in the electrolyte, ensuring the cycle life of the battery.
- the secondary battery provided by the embodiment of the present application can be used in terminal consumer products, such as mobile phones, tablet computers, mobile power supplies, portable machines, notebook computers, digital cameras and other wearable or mobile electronic devices, as well as drones, electric Automobiles, energy storage equipment and other products to improve product competitiveness.
- terminal consumer products such as mobile phones, tablet computers, mobile power supplies, portable machines, notebook computers, digital cameras and other wearable or mobile electronic devices, as well as drones, electric Automobiles, energy storage equipment and other products to improve product competitiveness.
- An embodiment of the present application also provides an electronic device including the above-mentioned secondary battery.
- the electronic device may include various consumer electronic products, such as mobile phones, tablet computers, notebook computers, mobile power supplies, portable machines, and other wearable or removable electronic devices, televisions, DVD players, video recorders, and camcorders. , radio, cassette player, combo stereo, electronic singing Players, compact disc players, home office equipment, home electronic health care equipment, as well as cars, energy storage equipment and other products.
- this embodiment of the present application provides an electronic device 300, which includes a housing 301, electronic components (not shown in Figure 3) accommodated in the housing 301, and a battery 302.
- the battery 302 supplies power to the electronic device 300, and the battery 302 includes the lithium secondary battery 200 described in the embodiment of the present application.
- the housing 301 may include a front cover assembled on the front side of the terminal and a rear case assembled on the rear side, and the battery 302 may be fixed inside the rear case.
- the embodiment of the present application provides an electronic device 400 , which can be various movable devices used for loading, transportation, assembly, disassembly, security, etc., such as various forms of vehicles.
- the electronic device 400 may include a vehicle body 401, a moving component 402, and a driving component.
- the driving component includes a motor 403 and a battery system 404.
- the battery system 404 includes the above-mentioned secondary battery 200 provided in the embodiment of the present application.
- the moving component 402 may be a wheel.
- the battery system 404 can be a battery pack including the above-mentioned secondary battery 200, which is housed at the bottom of the vehicle body and is electrically connected to the motor 403. It can provide power to the motor 403, and the motor 403 provides power to drive the movement of the electronic device 400.
- Component 402 moves.
- Example 1 Ion gel-coated negative active material
- the ion gel includes poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt dispersed in the three-dimensional network structure of the copolymer.
- Figure 5 shows the surface micromorphology and energy dispersive spectroscopy (EDS) elemental analysis results of the silicon oxide in Example 1 of the present application before coating (a) and after coating (b).
- EDS energy dispersive spectroscopy
- the mass proportion of ionic liquid in the ion gel coating layer is 66.7%, and the mass proportion of the three-dimensional network structure composed of polymer is approximately 33.3%.
- the thickness of the coating layer is about 6nm, the ionic conductivity of the coating layer at room temperature is about 5 ⁇ 10 -3 S ⁇ cm -1 , the fracture elongation of the coating layer is 470%, and the fracture strength is 2.5MPa .
- Example 2 The difference between the composite negative electrode material of Example 2 and Example 1 is that a conductive agent - single-arm carbon nanotubes is also added to the dispersion of silicone material in step (2).
- Example 1 SiOx@C without surface modification was directly used as the negative active material.
- the composite negative electrode materials obtained in Examples 1 and 2 and the SiOx@C of Comparative Example 1 were respectively mixed with the binder (specifically, a commercial polyacrylic acid aqueous solution) and the conductive agent (specifically, Super P conductive carbon black) in a mass ratio of 75: Mix with a mass ratio of 15:10, dilute with water, and stir thoroughly to obtain a negative electrode slurry; apply the negative electrode slurry on the negative electrode current collector (specifically, copper foil), vacuum dry, roll, and cut. , get the negative electrode piece.
- the binder specifically, a commercial polyacrylic acid aqueous solution
- the conductive agent specifically, Super P conductive carbon black
- metal lithium sheet as the counter electrode, assemble the negative electrode sheet, commercial PE separator and 1mol/L LiPF 6 /(EC+DEC) electrolyte (volume ratio 1:1) in an argon-protected glove box to form a 2032-type buckle. type battery.
- the button batteries made of the composite negative electrode materials of Examples 1-2 and Comparative Example 1 were subjected to electrochemical performance tests as shown in Table 1, where the test temperature was 25 ⁇ 5°C, conduct charge and discharge tests on button batteries in the voltage range of 0.05V ⁇ 1.5V at a charge and discharge rate of 0.05C/0.02C.
- Example 3 The difference between the composite negative electrode material of Example 3 and Example 1 is that the solvent in Example 1 is replaced with acetone, and the poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is replaced with a number average molecular weight of 450kDa poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, which also contains structural units
- the preparation method of the composite negative electrode material of Example 3 includes the following steps:
- step (1) Add 10g of negative active material powder (specifically commercial silicone material) to 30g of acetone, and heat at 30°C and 300rpm for 1 hour to obtain a dispersion of silicone material; add the dispersion in step (1) The precursor solution is added to the dispersion of silicone material under stirring, and the mixed material is obtained at 30°C and a rotation speed of 300 rpm for 6 hours;
- negative active material powder specifically commercial silicone material
- the ion gel includes poly(vinylidene fluoride-co-hexafluoropropylene) copolymer and 1-ethyl-3-methylimidazole bistriflate dispersed in the three-dimensional network structure of the copolymer. Amine salt.
- the ion conductivity of the ion gel coating layer at room temperature is approximately 3 ⁇ 10 -3 S ⁇ cm -1
- the elongation at break of the coating layer is 200%
- the ion conductivity at room temperature is approximately 3 ⁇ 10 -3 S ⁇ cm -1 .
- the strength is 2MPa.
- Example 4 The difference between the preparation method of the composite negative electrode material provided in Example 4 and that of Example 1 is that a trifunctional aziridine cross-linking agent is also added to the silicone material dispersion in step (2).
- the ion conductivity of the ion gel coating layer at room temperature is approximately 4 ⁇ 10 -3 S ⁇ cm -1
- the elongation at break of the coating layer is 200%
- the ion conductivity at room temperature is approximately 4 ⁇ 10 -3 S ⁇ cm -1 .
- the strength is 4.5MPa.
- Example 2 Compared with Example 1, under the same circumstances, after introducing the cross-linking agent auxiliary agent, the breaking strength of the ion gel coating layer is improved to a certain extent.
- the preparation method of the composite negative electrode material provided in Example 5 is different from that in Example 1 in that the ionic liquid used is specifically 1-ethyl-3-methylimidazole hexafluorophosphate.
- the ion conductivity of the ion gel coating layer at room temperature is approximately 4.2 ⁇ 10 -3 S ⁇ cm -1
- the rupture elongation of the coating layer is 450%
- the ion conductivity at room temperature is approximately 4.2 ⁇ 10 -3 S ⁇ cm -1 .
- the strength is 2.5MPa.
- the preparation method of the composite negative electrode material provided in Example 6 is different from that in Example 1 in that the ionic liquid used is specifically N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt ( CAS number is 223437-11-4).
- the ionic conductivity of the ion gel coating layer at room temperature is approximately 4.5 ⁇ 10 -3 S ⁇ cm -1
- the elongation at break of the coating layer is 400%
- the elongation at break is The strength is 3MPa.
- a composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is modified from 30 mg to 45 mg, and the amount of ionic liquid is changed from 60mg was revised to 45mg.
- the thickness of the ion gel coating layer is about 5 nm, and the ionic conductivity of the coating layer at room temperature is about 2 ⁇ 10 -3 S ⁇ cm -1 .
- the layer has an elongation at break of 200% and a strength at break of 4MPa.
- a composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is modified from 30 mg to 4.5 mg, and the amount of ionic liquid is Modified from 60mg to 85.5mg.
- the thickness of the ion gel coating layer is about 5 nm, and the ionic conductivity of the coating layer at room temperature is about 8 ⁇ 10 -3 S ⁇ cm -1 .
- the layer has an elongation at break of 1000% and a strength at break of 1 MPa.
- a composite negative electrode material, the preparation method of which is different from that of Example 1 is: the poly(acrylic acid- The dosage of lithium acrylate-ethyl acrylate copolymer was increased from 30 mg to 40 mg.
- the thickness of the ion gel coating layer is about 8 nm
- the mass of the coating layer accounts for 1% of the core mass
- the ionic conductivity of the coating layer at room temperature is about 4 ⁇ 10 -3 S ⁇ cm -1
- the breaking elongation of the coating layer is 200%
- the breaking strength is 5MPa.
- a composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is increased from 30 mg to 120 mg, 1-ethyl- The dosage of 3-methylimidazole bistrifluoromethanesulfonimide salt was increased from 60 mg to 240 mg, and the corresponding amount of organic solvent methanol was also increased four times, keeping the quality of the active material unchanged.
- the thickness of the ion gel coating layer is about 20 nm, and the ionic conductivity of the coating layer at room temperature is about 5 ⁇ 10 -3 S ⁇ cm -1 .
- the elongation at break is 470% and the strength at break is 2.5MPa.
- Example 10 Compared with Example 1, the mass proportion of the coating layer in the overall composite negative electrode material in Example 10 is increased, which helps to further improve the stability of the material and increase its first Coulombic efficiency. However, due to the increase in inactive components , the material capacity will decrease to a certain extent. Among them, the composite negative electrode material of Example 10 was made into a button battery according to the method of Example 1, and the first Coulombic efficiency was measured to be 88% (Example 1 was 86%), and the first lithium insertion capacity was 1448.1 mAh/g, the first delithiation capacity is 1274.3mAh/g.
- a composite negative electrode material, the preparation method of which is different from that of Example 1 is that: in step (3), after vacuum drying, the obtained solid powder is calcined at high temperature at 550°C for 3 hours to make part of the ion gel The cladding layer is carbonized.
- the composite negative electrode material obtained in Example 11 also has an inorganic carbon coating layer (containing F, N, and S doping elements) with a thickness of approximately 1 nm in addition to the ion gel coating layer.
- the existence of the doped carbon coating layer helps to improve the conductivity of the composite negative electrode material, and then the rate performance of the battery made of the composite negative electrode material is also improved.
- Embodiment 12 provides a composite cathode material.
- the preparation method is different from that in Example 1 in that the negative active material-silicon oxide in Example 1 is replaced with a high-nickel ternary cathode active material (its structure is generally The formula is lithium nickel cobalt manganate LiNi 0.83 Co 0.12 Mn 0.05 O 2 , and the particle size is about 4.3 ⁇ m).
- the thickness of the ion gel coating layer is about 8 nm
- the elongation at break of the coating layer is 470%
- the breaking strength is 2.5 MPa.
- the core-shell composite cathode material provided in Example 12 of the present application will not deliquesce and absorb water when stored at an ambient humidity of 25% for 30 days; while pure high-nickel nickel If the cobalt-manganese ternary material is stored at this humidity for more than one day, its electrochemical performance will decrease due to deliquescence, and gelation will easily occur when it is prepared. This indicates that the ion gel coating layer can improve the water and oxygen stability of the core cathode active material.
Abstract
Embodiments of the present application provide a composite material, a preparation method therefor and an application thereof. The composite material comprises an inner core and a cladding layer covering the inner core; the inner core comprises a negative electrode active material, a positive electrode active material, or a lithium supplementing agent; the cladding layer contains an ionic gel; the ionic gel comprises a polymer and an ionic liquid; the ionic liquid is dispersed in a three-dimensional network structure formed by the polymer. The cladding layer containing the ionic gel can improve the stability and electrochemical performance of the inner core material, thereby improving the electrochemical performance of a secondary battery using the composite material, and improving competitiveness of a product.
Description
本申请要求于2022年4月29日提交至中国专利局、申请号为202210468809.1、申请名称为“复合材料及其制备方法和应用”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims priority to the Chinese patent application submitted to the China Patent Office on April 29, 2022, with application number 202210468809.1 and the application title "Composite Materials and Preparation Methods and Applications", the entire content of which is incorporated herein by reference. Applying.
本申请涉及电池技术领域，具体涉及复合材料及其制备方法和应用。This application relates to the field of battery technology, specifically composite materials and their preparation methods and applications.
锂离子电池已经在手机、笔记本电脑等便携式电子产品及新能源汽车等领域得到广泛应用，基于传统石墨负极的锂离子电池的能量密度已接近天花板，已不能满足人们日益增长的续航和待机需求，而理论比容量较高的硅基、磷基负极材料被认为是突破锂二次电池高能量密度的有效途径。然而，硅基、磷基等负极材料在充放电过程中易发生较大的体积变化，导致负极材料颗粒发生粉化，恶化电池的循环性能等电化学性能。Lithium-ion batteries have been widely used in portable electronic products such as mobile phones and laptops, as well as new energy vehicles. The energy density of lithium-ion batteries based on traditional graphite anodes is close to the ceiling and can no longer meet people's growing needs for battery life and standby. Silicon-based and phosphorus-based anode materials with higher theoretical specific capacities are considered to be effective ways to break through the high energy density of lithium secondary batteries. However, negative electrode materials such as silicon-based and phosphorus-based are prone to large volume changes during charging and discharging, leading to pulverization of negative electrode material particles and deteriorating electrochemical properties such as battery cycle performance.
目前改进上述膨胀问题的方案多是在负极材料构建无机碳包覆层、聚合物包覆层或多层包覆层，但无机碳包覆层的韧性差、粘附性不足，不能持久地承受负极材料在脱嵌锂过程中的体积变化；聚合物包覆层的韧性虽较好，但其离子电导性较差，造成材料的界面阻抗高，不利于负极材料的容量发挥、降低倍率性能。目前还未找到能有效解决负极材料的脱嵌锂膨胀问题且不降低其容量发挥和倍率性能的方案。Most of the current solutions to improve the above-mentioned expansion problem are to build an inorganic carbon coating layer, a polymer coating layer or a multi-layer coating layer on the negative electrode material. However, the inorganic carbon coating layer has poor toughness and insufficient adhesion, and cannot withstand it for a long time. The volume change of the anode material during the process of deintercalating lithium; although the toughness of the polymer coating is good, its ionic conductivity is poor, resulting in a high interface resistance of the material, which is not conducive to the capacity development of the anode material and reduces the rate performance. At present, no solution has been found that can effectively solve the problem of lithium expansion in anode materials without reducing its capacity and rate performance.
发明内容Contents of the invention
鉴于此，本申请实施例提供了一种具有离子凝胶包覆层的复合材料，以提升内核材料的稳定性、电化学性能。In view of this, embodiments of the present application provide a composite material with an ion gel coating layer to improve the stability and electrochemical performance of the core material.
本申请实施例第一方面提供了一种复合材料，包括内核和包覆在所述内核上的包覆层，其中，所述内核包括负极活性材料、正极活性材料、或补锂剂，所述包覆层包括离子凝胶，所述离子凝胶包括聚合物和离子液体，所述离子液体分散在所述聚合物形成的三维网络结构中。The first aspect of the embodiment of the present application provides a composite material, including a core and a coating layer coating the core, wherein the core includes a negative active material, a positive active material, or a lithium replenishing agent, and the The coating layer includes an ion gel, the ion gel includes a polymer and an ionic liquid, and the ionic liquid is dispersed in a three-dimensional network structure formed by the polymer.
本申请实施例提供的复合材料中，采用含离子凝胶的包覆层包覆内核，该包覆层是一种固态软质材料，具有良好的韧性、一定的粘接性和优异的离子电导性，在内核为负极活性材料时，其能在不降低内核材料倍率性能、利于容量发挥的同时，较好地承受负极活性材料在脱嵌锂过程中的体积变化，随其一起膨胀/收缩，包覆层不易破损/脱落，整体的复合材料也不易从极片脱落，从而提升负极活性材料的循环稳定性。此外，在内核为正极活性材料或补锂剂时，离子凝胶包覆层的粘接性和优异离子电导性，也利于其与内核保持较强的结合力、不影响内核电化学性能的发挥，且其良好的疏水性还能提升内核材料的水氧稳定性，及制浆过程中的浆料稳定性。In the composite material provided in the embodiment of the present application, the core is covered with a coating layer containing ion gel. The coating layer is a solid soft material with good toughness, certain adhesion and excellent ionic conductivity. When the core is an anode active material, it can better withstand the volume change of the anode active material during the process of deintercalating lithium and expand/contract with it without reducing the rate performance of the core material and facilitating capacity development. The coating layer is not easy to be damaged/fallen off, and the overall composite material is not easy to fall off from the pole piece, thereby improving the cycle stability of the negative active material. In addition, when the core is a cathode active material or lithium replenishing agent, the adhesiveness and excellent ionic conductivity of the ion gel coating also help it maintain a strong binding force with the core without affecting the electrochemical performance of the core. , and its good hydrophobicity can also improve the water and oxygen stability of the core material and the slurry stability during the pulping process.
本申请实施方式中，所述包覆层的厚度为5nm-50nm。合适厚度的离子凝胶包覆层既可以保证其稳定地发挥包覆层的功能(如提供内核材料体积膨胀的缓冲、保证内核的储存或加工
稳定性等)，又不会因其厚度过厚而影响内核材料的电化学性能发挥。In the embodiment of the present application, the thickness of the coating layer is 5nm-50nm. An ion gel coating of appropriate thickness can ensure that it can stably perform the functions of the coating (such as providing a buffer for the volume expansion of the core material and ensuring the storage or processing of the core). stability, etc.) without affecting the electrochemical performance of the core material due to its excessive thickness.
本申请实施方式中，所述离子凝胶中，聚合物的质量占比为5％-50％，离子液体的质量占比为50％-95％。这样可保证形成无明显宏观相分离的离子凝胶，且离子凝胶的强度不会过大、拉伸性能良好、粘接性能出色。In the embodiment of the present application, in the ion gel, the mass proportion of polymer is 5%-50%, and the mass proportion of ionic liquid is 50%-95%. This can ensure the formation of an ion gel without obvious macroscopic phase separation, and the strength of the ion gel will not be too high, with good tensile properties and excellent bonding properties.
本申请实施方式中，所述聚合物包括式(Ⅰ)所示的结构单元：
In the embodiment of the present application, the polymer includes structural units represented by formula (I):
In the embodiment of the present application, the polymer includes structural units represented by formula (I):
其中，R1选自氢原子、氟原子或甲基，R2选自氢原子、氟原子、甲基、氟代甲基、-(CH2)a-Z-，其中，a为0-6的整数，Z选自-COOH、-COOLi、-COONa、-COOK、-(CH2CH2O)nH、-(CH2CH2O)nCH3、-COOR3、-CONH2、-CONH(R4)、-CON(R5)(R6)；R3、R4、R5、R6独立地选自C1-6的烷基，n每次出现独立地选自1-20的整数。当离子凝胶包覆层中的聚合物具有这样的结构单元时，聚合物的极性较大，能在离子液体中顺利溶解，得到无明显宏观相分离的离子凝胶；此外，还可通过调控R1、R1及离子液体来实现离子凝胶对不同被包覆内核材料的粘接性能。Wherein, R 1 is selected from hydrogen atom, fluorine atom or methyl group, R 2 is selected from hydrogen atom, fluorine atom, methyl group, fluoromethyl, -(CH 2 ) a -Z-, where a is 0-6 is an integer, Z is selected from -COOH, -COOLi, -COONa, -COOK, -(CH 2 CH 2 O) n H, -(CH 2 CH 2 O) n CH 3 , -COOR 3 , -CONH 2 , - CONH(R 4 ), -CON(R 5 )(R 6 ); R 3 , R 4 , R 5 , R 6 are independently selected from C 1-6 alkyl groups, and each occurrence of n is independently selected from 1- An integer of 20. When the polymer in the ion gel coating layer has such structural units, the polymer has greater polarity and can be smoothly dissolved in the ionic liquid to obtain an ion gel without obvious macroscopic phase separation; in addition, it can also be Adjust R 1 , R 1 and the ionic liquid to realize the adhesion performance of the ion gel to different coated core materials.
本申请实施方式中，所述聚合物的数均分子量为1kDa-1000kDa。含有这样聚合物的离子凝胶层能兼顾较高的拉伸强度、粘接性，并保证聚合物在离子液体基质中的良好分散性。In the embodiment of the present application, the number average molecular weight of the polymer is 1 kDa-1000 kDa. The ion gel layer containing such a polymer can have high tensile strength and adhesion, and ensure good dispersion of the polymer in the ionic liquid matrix.
本申请实施方式中，所述离子液体中的阳离子包括烷基取代的咪唑类阳离子、烷基取代的吡咯类阳离子、烷基取代的吡啶类阳离子、烷基取代的噻唑类阳离子、烷基取代的哌啶类阳离子、烷基铵类阳离子、烷基鏻类阳离子中的一种或多种。In the embodiment of the present application, the cations in the ionic liquid include alkyl-substituted imidazole cations, alkyl-substituted pyrrole cations, alkyl-substituted pyridine cations, alkyl-substituted thiazole cations, alkyl-substituted cations, One or more of piperidine cations, alkyl ammonium cations, and alkyl phosphonium cations.
本申请实施方式中，所述包覆层的材料在室温下的离子电导率在10-4S·cm-1以上。In the embodiment of the present application, the ionic conductivity of the material of the coating layer at room temperature is above 10 -4 S·cm -1 .
本申请实施方式中，所述包覆层的断裂延伸率在100％以上，断裂强度在0.5MPa-5Mpa的范围内。这些参数反映离子凝胶包覆层的韧性较好，拉伸性能优异；采用其包覆负极活性材料，不易破损脱落，能持久为负极内核材料提供体积膨胀的缓冲，提升材料的循环稳定性。In the embodiment of the present application, the breaking elongation of the coating layer is above 100%, and the breaking strength is in the range of 0.5MPa-5MPa. These parameters reflect that the ion gel coating layer has good toughness and excellent tensile properties; it is used to coat the negative electrode active material, which is not easy to break and fall off. It can provide a long-term buffer for the volume expansion of the negative electrode core material and improve the cycle stability of the material.
本申请一些实施方式中，所述包覆层中还包含导电剂、活性金属离子的金属盐、表面活性剂中的一种或多种。In some embodiments of the present application, the coating layer further includes one or more of a conductive agent, a metal salt of active metal ions, and a surfactant.
本申请一些实施方式中，所述包覆层外还具有含掺杂元素的碳化层，其中，所述掺杂元素源自所述离子液体。掺杂型碳化层的存在，可提升复合材料的导电性。In some embodiments of the present application, the coating layer also has a carbonized layer containing doping elements, wherein the doping elements are derived from the ionic liquid. The existence of the doped carbonization layer can improve the conductivity of the composite material.
本申请实施例第二方面提供了一种复合材料的制备方法，包括以下步骤：The second aspect of the embodiments of this application provides a method for preparing a composite material, which includes the following steps:
将聚合物、离子液体分散到溶剂中，得到离子凝胶前驱体溶液；Disperse the polymer and ionic liquid into the solvent to obtain an ion gel precursor solution;
将内核材料与所述离子凝胶前驱体溶液进行混合，得到混合物料；其中，所述内核材料包括负极活性材料、正极活性材料、或补锂剂；Mix the core material and the ion gel precursor solution to obtain a mixed material; wherein the core material includes a negative active material, a positive active material, or a lithium replenishing agent;
去除所述混合物料中的所述溶剂，在所述溶剂的去除过程中所述内核材料的表面形成含离子凝胶的包覆层，得到复合材料。The solvent in the mixed material is removed. During the removal of the solvent, a coating layer containing ion gel is formed on the surface of the core material to obtain a composite material.
本申请一些实施方式中，在去除所述溶剂之后，上述制备方法还包括：将去除溶剂后得到的固态材料在50-80℃的温度下进行热处理。热处理可以使内核材料表面的离子凝胶的流动性增强，提升其包覆均匀性。In some embodiments of the present application, after removing the solvent, the above preparation method further includes: heat treating the solid material obtained after removing the solvent at a temperature of 50-80°C. Heat treatment can enhance the fluidity of the ion gel on the surface of the core material and improve its coating uniformity.
本申请一些实施方式中，形成含离子凝胶的包覆层之后，上述制备方法还包括：对复合材料进行高温煅烧处理，以使部分离子凝胶包覆层发生碳化。这样在离子凝胶包覆层外可得到掺杂型碳化层，利于提升复合材料的导电性。
In some embodiments of the present application, after forming the coating layer containing ion gel, the above preparation method further includes: calcining the composite material at high temperature to carbonize part of the ion gel coating layer. In this way, a doped carbonized layer can be obtained outside the ion gel coating layer, which is beneficial to improving the conductivity of the composite material.
本申请实施例的复合材料的制备方法，流程简单，易于操作，适合于大规模生产。且，采用上述制备方法制得的复合材料中，含离子凝胶的包覆层具有一定的粘结性，且拉伸性能较好。The preparation method of the composite material in the embodiment of the present application has a simple process, is easy to operate, and is suitable for large-scale production. Moreover, in the composite material prepared by the above preparation method, the coating layer containing ion gel has certain adhesiveness and good tensile properties.
本申请实施例第三方面还提供一种电极极片，所述正极极片包括本申请实施例第一方面所述的复合材料。The third aspect of the embodiment of the present application also provides an electrode pole piece, the positive electrode piece includes the composite material described in the first aspect of the embodiment of the present application.
其中，该电极极片可以是负极极片或正极极片。特别地，负极极片含有内核为负极活性材料的上述复合材料时，该负极极片在电池循环使用过程中，不易发生极片颗粒粉化、脱落，循环性能较好。Wherein, the electrode piece can be a negative electrode piece or a positive electrode piece. In particular, when the negative electrode sheet contains the above-mentioned composite material whose core is the negative electrode active material, the negative electrode sheet is less likely to pulverize and fall off during battery recycling, and has better cycle performance.
本申请实施例第四方面还提供一种二次电池，包括本申请实施例第三方面所述的电极极片。该二次电池可以是锂二次电池或其他二次电池等。The fourth aspect of the embodiment of the present application also provides a secondary battery, including the electrode pole piece described in the third aspect of the embodiment of the present application. The secondary battery may be a lithium secondary battery, other secondary batteries, or the like.
采用含上述复合材料的电极极片的二次电池，其循环稳定性较好，倍率性能较优，能更好地满足消费类电子设备、动力车辆等对二次电池长循环寿命、高能量密度的需求。Secondary batteries using electrode plates containing the above composite materials have better cycle stability and better rate performance, and can better meet the requirements of consumer electronic equipment, power vehicles, etc. for long cycle life and high energy density of secondary batteries. needs.
本申请实施例第五方面提供了一种电子设备，所述电子设备包括本申请第四方面所述的二次电池。该电子设备通过采用本申请实施例提供的二次电池供电，能够提升产品的使用体验和市场竞争力。The fifth aspect of the embodiment of the present application provides an electronic device, which includes the secondary battery described in the fourth aspect of the present application. By using the secondary battery provided by the embodiment of the present application for power supply, the electronic device can improve the user experience and market competitiveness of the product.
图1为本申请实施例提供的复合材料的一种结构示意图。Figure 1 is a schematic structural diagram of a composite material provided by an embodiment of the present application.
图2为本申请实施例提供的锂二次电池的结构示意图。Figure 2 is a schematic structural diagram of a lithium secondary battery provided by an embodiment of the present application.
图3为本申请实施例提供的电子设备的一种结构示意图。FIG. 3 is a schematic structural diagram of an electronic device provided by an embodiment of the present application.
图4为本申请实施例提供的电子设备的另一种结构示意图。FIG. 4 is another schematic structural diagram of an electronic device provided by an embodiment of the present application.
图5为本申请实施例1中硅氧化物在包覆前(a)和包覆后(b)的表面微观形貌及能谱仪元素分析结果。Figure 5 shows the surface micromorphology and energy spectrometer elemental analysis results of silicon oxide in Example 1 of the present application before coating (a) and after coating (b).
下面将结合本申请实施例中的附图，对本申请技术方案进行说明。The technical solution of the present application will be described below with reference to the drawings in the embodiments of the present application.
请参见图1，此为本申请实施例提供的复合材料的结构示意图。该复合材料100包括内核10和包覆在内核10上的包覆层20，其中，内核10包括负极活性材料、正极活性材料、或补锂剂，包覆层20包括离子凝胶，该离子凝胶包括聚合物和离子液体，离子液体分散在聚合物形成的三维网络结构中。Please refer to Figure 1, which is a schematic structural diagram of a composite material provided in an embodiment of the present application. The composite material 100 includes a core 10 and a coating layer 20 covering the core 10, wherein the core 10 includes an anode active material, a cathode active material, or a lithium replenishing agent, and the coating layer 20 includes an ion gel. Glues include polymers and ionic liquids. The ionic liquids are dispersed in the three-dimensional network structure formed by the polymer.
本申请中的包覆层20包括通过基质离子液体与聚合物网络骨架组成的离子凝胶，离子液体均匀分散在聚合物网络结构中，该离子凝胶中不存在宏观上的相分离，其是一种固态软质材料，具有良好的韧性(如拉伸性能好)和一定的粘接性，能够牢固包覆在内核材料的表面形成稳定的包覆层，并赋予包覆层20一定的变形能力。当内核10为负极活性材料时，一来，包覆层20能随着负极活性材料颗粒在脱嵌锂循环过程中的体积变化而一起膨胀/收缩，包覆层20不易破损/脱落，从而保证内核负极材料在电池循环过程中的颗粒完整性，能持久地改善其循环稳定性、解决其循环跳水问题。二来，离子凝胶的粘接性还利于复合材料100与电极极片中粘结剂的粘接，提升复合材料100在电极极片上的粘接牢固性，避免在体积膨胀过程中从极片脱落而失效。三来，具有出色离子电导率的离子液体存在，使得包覆层20的离子电导率较高，复合材料100的界面阻抗较低，有利于深层嵌锂，提高内核10的首效容量发挥，还能提高锂离子在复合材料100表面的传导性能，不会影响内核10的倍率性能，并提升材料
的快充能力。此外，离子凝胶包覆层20作为一种人工SEI层(solid electrolyte interface，固体电解质界面层)，能隔绝内核材料与电解液的直接接触，稳定界面，减少与电解质之间的副反应。因此，采用兼具良好韧性、粘接性及高电化学性能的离子凝胶作为包覆层，能在不降低内核材料的倍率性能与容量发挥的同时，解决内核的体积膨胀问题，提升其循环稳定性。The coating layer 20 in this application includes an ion gel composed of a matrix ionic liquid and a polymer network skeleton. The ionic liquid is evenly dispersed in the polymer network structure. There is no macroscopic phase separation in the ion gel, which is A solid soft material with good toughness (such as good tensile properties) and certain adhesion. It can be firmly coated on the surface of the core material to form a stable coating layer and give the coating layer 20 a certain deformation. ability. When the core 10 is an anode active material, firstly, the coating layer 20 can expand/contract along with the volume change of the anode active material particles during the lithium deintercalation and deintercalation process, and the coating layer 20 is not easy to be damaged/fall off, thereby ensuring The particle integrity of the core anode material during the battery cycle can permanently improve its cycle stability and solve its cycle diving problem. Secondly, the adhesiveness of the ion gel also facilitates the bonding of the composite material 100 to the adhesive in the electrode piece, improves the bonding strength of the composite material 100 on the electrode piece, and prevents the composite material 100 from being removed from the electrode piece during the volume expansion process. Fall off and become ineffective. Thirdly, the existence of ionic liquids with excellent ionic conductivity makes the ionic conductivity of the coating layer 20 higher and the interface resistance of the composite material 100 lower, which is conducive to deep lithium embedding, improving the first-efficiency capacity of the core 10, and also It can improve the conductivity of lithium ions on the surface of the composite material 100 without affecting the rate performance of the core 10 and improve the material fast charging capability. In addition, the ion gel coating layer 20 serves as an artificial SEI layer (solid electrolyte interface), which can isolate the direct contact between the core material and the electrolyte, stabilize the interface, and reduce side reactions with the electrolyte. Therefore, using an ion gel with good toughness, adhesion and high electrochemical properties as the coating layer can solve the volume expansion problem of the core and improve its cycle without reducing the rate performance and capacity of the core material. stability.
当内核10为正极活性材料时，上述包覆层20具有疏水性，能起到隔绝水氧的作用，可提升内核正极材料在空气、水中的稳定性，延长稳定存放的时间，防止潮解吸水导致的材料结构变化及性能下降；此外，在正极浆料的搅拌制浆过程中，包覆层20也有助于稳定浆料，避免因正极活性材料的表面残碱含量高而易吸水变质所导致的浆料凝胶化、涂布困难等问题。此外，基于上段的类似理由，包覆层20因离子电导性好，也不会影响内核正极材料的倍率性能和容量发挥，并因具有一定的粘性，可提升复合正极材料与粘结剂之间的粘接牢固性。When the core 10 is a positive active material, the above-mentioned coating layer 20 is hydrophobic and can isolate water and oxygen, which can improve the stability of the core positive material in air and water, extend the stable storage time, and prevent deliquescence and water absorption. The material structure changes and the performance decreases; in addition, during the stirring and pulping process of the cathode slurry, the coating layer 20 also helps to stabilize the slurry to avoid water absorption and deterioration caused by the high residual alkali content on the surface of the cathode active material. Problems such as gelation of the slurry and difficulty in coating. In addition, based on similar reasons as mentioned in the previous paragraph, the coating layer 20 has good ionic conductivity and will not affect the rate performance and capacity of the core cathode material. Moreover, because it has a certain viscosity, it can improve the relationship between the composite cathode material and the binder. The bonding strength.
类似地，当内核10为补锂剂时，包覆层20也有助于提升内核的储存稳定性，及制浆过程中浆料的稳定性，且不影响补锂效果的发挥。Similarly, when the core 10 is a lithium replenishing agent, the coating layer 20 also helps to improve the storage stability of the core and the stability of the slurry during the pulping process without affecting the lithium replenishing effect.
需要说明的是，包覆层20可以包覆内核10的全部表面(如图1所示)，也可以只包覆内核10的一部分表面，具体可以是连续包覆内核10的一部分表面(例如在内核10的一部分表面具有一岛状的包覆层20)，或者非连续包覆内核10的表面，例如呈间隔的多个岛状包覆。It should be noted that the coating layer 20 can cover the entire surface of the core 10 (as shown in FIG. 1 ), or can only cover a part of the surface of the core 10 . Specifically, it can continuously cover a part of the surface of the core 10 (for example, in A part of the surface of the core 10 has an island-shaped coating layer 20), or the surface of the core 10 is non-continuously coated, for example, a plurality of island-shaped coatings are spaced apart.
本申请实施方式中，上述负极活性材料可以包括碳基材料、硅基材料、磷基材料、锡基材料、硫基材料等中的一种或多种。其中，硅基材料、磷基材料、锡基材料等体积膨胀效应较大的负极活性材料，特别需要上述包覆层20的包覆。碳基材料可以包括石墨(如天然石墨、人造石墨)、软碳、硬碳、无烟煤、中间相碳微球等中的一种或多种；硅基材料可包括单质硅、硅基合金、硅氧化物(可用SiOx表示，0<x<2，例如是0.9<x<1.7)、硅碳复合材料等中的一种或多种；磷基材料可包括磷单质(如红磷、黑磷、白磷)、磷碳复合材料等中的一种或多种；锡基材料可以包括单质锡、锡合金、锡氧化物等中的一种或多种。In the embodiment of the present application, the above-mentioned negative active material may include one or more of carbon-based materials, silicon-based materials, phosphorus-based materials, tin-based materials, sulfur-based materials, etc. Among them, negative electrode active materials with large volume expansion effects, such as silicon-based materials, phosphorus-based materials, and tin-based materials, particularly need to be covered by the above-mentioned coating layer 20 . Carbon-based materials can include one or more of graphite (such as natural graphite, artificial graphite), soft carbon, hard carbon, anthracite, mesophase carbon microspheres, etc.; silicon-based materials can include elemental silicon, silicon-based alloys, silicon One or more of oxides (can be represented by SiOx, 0<x<2, for example, 0.9<x<1.7), silicon-carbon composite materials, etc.; phosphorus-based materials can include phosphorus elements (such as red phosphorus, black phosphorus, One or more of white phosphorus), phosphorus-carbon composite materials, etc.; tin-based materials can include one or more of elemental tin, tin alloy, tin oxide, etc.
本申请中，正极活性材料可根据具体的二次电池进行能量存储所依赖的活性离子进行选择。活性离子可以包括锂离子、钠离子、钾离子、镁离子、铝离子、锌离子等。其中，对于锂二次电池来说，其正极活性材料是锂的复合氧化物，包括但不限于锂钴氧化物(如钴酸锂LiCoO2)、锂镍氧化物(如镍酸锂LiNiO2)、锂锰氧化物(如锰酸锂LiMnO2、高锰酸锂)、锂钛氧化物(如钛酸锂)、锂铁磷氧化物(如磷酸铁锂、磷酸锰铁锂等)、锂镍钴氧化物(如镍钴酸锂LiNiaCo1-aO2)、锂镍锰氧化物(例如镍锰酸锂LiNiaMn1-aO2)、镍钴多元氧化物(如镍钴锰酸锂LiNiaCobMn1-a-bO2、镍钴铝酸锂LiNiaCobAl1-a-bO2、镍钴锰铝酸锂(LiNiaCobMncAl1-a-b-cO2)中的一种或多种。其中，0<a<1，0<b<1，0<c<1，0<1-a-b<1，0<1-a-b-c<1。对于钠二次电池来说，其正极活性材料可以包括含钠的复合氧化物、普鲁士蓝、普鲁士白等中的一种或多种。对于钾二次电池来说，其正极活性材料可以是含钾的复合氧化物，对于镁二次电池来说，其正极活性材料可以是含镁的复合氧化物。上述正极活性材料可以是未经掺杂的或经掺杂改性的，可以经过表面包覆、预锂化处理等。其中，正极活性材料的颗粒粒径可以在10nm-100μm的范围。In this application, the positive active material can be selected according to the active ions that the specific secondary battery relies on for energy storage. Active ions may include lithium ions, sodium ions, potassium ions, magnesium ions, aluminum ions, zinc ions, etc. Among them, for lithium secondary batteries, the positive active material is a composite oxide of lithium, including but not limited to lithium cobalt oxide (such as lithium cobalt oxide LiCoO 2 ), lithium nickel oxide (such as lithium nickel oxide LiNiO 2 ) , Lithium manganese oxide (such as lithium manganate LiMnO 2 , lithium permanganate), lithium titanium oxide (such as lithium titanate), lithium iron phosphorus oxide (such as lithium iron phosphate, lithium iron manganese phosphate, etc.), lithium nickel Cobalt oxide (such as lithium nickel cobalt oxide LiNi a Co 1-a O 2 ), lithium nickel manganese oxide (such as lithium nickel manganese oxide LiNi a Mn 1-a O 2 ), nickel cobalt polyvalent oxide (such as nickel cobalt manganese Lithium oxide LiNi a Co b Mn 1-ab O 2 , lithium nickel cobalt aluminate LiNi a Co b Al 1-ab O 2 , lithium nickel cobalt manganese aluminate (LiNi a Co b Mn c Al 1-abc O 2 ) One or more of them. Among them, 0<a<1, 0<b<1, 0<c<1, 0<1-ab<1, 0<1-abc<1. For sodium secondary batteries , the positive active material may include one or more of sodium-containing composite oxide, Prussian blue, Prussian white, etc. For potassium secondary batteries, the positive active material may be a potassium-containing composite oxide. For magnesium secondary batteries, the cathode active material can be a composite oxide containing magnesium. The above-mentioned cathode active material can be undoped or doped and modified, and can undergo surface coating, pre-lithium treatment, etc. .Wherein, the particle size of the cathode active material may be in the range of 10 nm-100 μm.
对于锂二次电池来说，上述补锂剂可以是富锂材料，包括但不限于LiCoO2、Li6CoO4、Li2MnO3、Li2CuO2、Li2NiO2、Li5FeO4、Li2CO3(碳酸锂)、Li2C2O4(草酸锂)、Li2O(氧化锂)、Li2O2(过氧化锂)、CH3COOLi(醋酸锂)等中的一种或多种。这些补锂剂可以是未经掺杂的或经掺杂改性的，可以经过表面包覆、预锂化处理等。补锂剂的颗粒粒径可以在10nm-100μm的范围。For lithium secondary batteries, the above-mentioned lithium replenishing agent can be lithium-rich materials, including but not limited to LiCoO 2 , Li 6 CoO 4 , Li 2 MnO 3 , Li 2 CuO 2 , Li 2 NiO 2 , Li 5 FeO 4 , One of Li 2 CO 3 (lithium carbonate), Li 2 C 2 O 4 (lithium oxalate), Li 2 O (lithium oxide), Li 2 O 2 (lithium peroxide), CH 3 COOLi (lithium acetate), etc. or more. These lithium replenishing agents can be undoped or modified by doping, and can undergo surface coating, prelithiation treatment, etc. The particle size of the lithium supplement can be in the range of 10nm-100μm.
本申请实施方式中，包覆层20的厚度为5nm-50nm。包覆层20的厚度可根据内核的大小
来调整，合适厚度的包覆层20可以保证其稳定地发挥包覆层的功能(如提供内核材料体积膨胀的缓冲、保证内核的储存或加工稳定性等)，同时包覆层20几乎不具备电化学活性，又不会因其厚度过厚而过度增加锂离子在该包覆层中的迁移路程、降低复合材料的克容量等。具体地，包覆层20的厚度具体可以是8nm、10nm、15nm、20nm、22nm、25nm、30nm、35nm、40nm、45nm或48nm等。在一些实施方式中，包覆层20的厚度为5nm-30nm。In the embodiment of the present application, the thickness of the coating layer 20 is 5 nm-50 nm. The thickness of the cladding layer 20 can be determined according to the size of the core To adjust, the coating layer 20 of appropriate thickness can ensure that it can stably perform the functions of the coating layer (such as providing a buffer for the volume expansion of the core material, ensuring the storage or processing stability of the core, etc.), and at the same time, the coating layer 20 has almost no Electrochemical activity, without excessively increasing the migration distance of lithium ions in the coating layer and reducing the gram capacity of the composite material due to its excessive thickness. Specifically, the thickness of the cladding layer 20 may be 8 nm, 10 nm, 15 nm, 20 nm, 22 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 48 nm, etc. In some embodiments, the thickness of the cladding layer 20 is 5 nm-30 nm.
本申请实施方式中，包覆层20的质量占内核10质量的0.5％-1％。包覆层20的质量占比在此范围，有助于在内核材料表面形成厚度合适、包覆完整度较高的包覆层20，同时避免过多的包覆层材料降低复合材料100的克容量。具体地，包覆层20的质量可以占内核10质量的0.55％、0.6％、0.7％、0.8％、0.9％、或0.95％等。In the embodiment of the present application, the mass of the coating layer 20 accounts for 0.5%-1% of the mass of the core 10 . The mass proportion of the cladding layer 20 is within this range, which helps to form a cladding layer 20 with appropriate thickness and high coating integrity on the surface of the core material, and at the same time avoids excessive cladding layer material from reducing the weight of the composite material 100 capacity. Specifically, the mass of the cladding layer 20 may account for 0.55%, 0.6%, 0.7%, 0.8%, 0.9%, or 0.95% of the mass of the core 10 .
本申请实施方式中，所述离子凝胶中，聚合物的质量占比为5％-50％，离子液体的质量占比为50％-95％。其中，控制离子液体在该离子凝胶中的质量占比为50％以上，保证形成无明显宏观相分离的离子凝胶；聚合物在该离子凝胶中的质量占比在50％以下，可保证离子凝胶的强度不会过大、拉伸性能良好、粘接性能出色，利于在内核负极活性材料的脱嵌锂过程中，随其一起膨胀/收缩而不破损脱落。此外，不同于以水为基质的水凝胶或以有机溶剂为基质的有机凝胶体系，本申请的包覆层中，离子凝胶以离子液体为基质，基质稳定性较好，不易溶解或挥发，保证离子凝胶包覆层能正常发挥其包覆层功能，不会在电池运行过程中因基质挥发引起电池的副反应等。示例性地，离子液体在离子凝胶中的质量占比可以为55％、60％、65％、70％、75％、80％、85％、90％等，聚合物在离子凝胶中的质量占比可以为10％、15％、20％、25％、30％、35％、40％、45％。在一些实施方式中，离子液体在离子凝胶中的质量占比为60％-75％。聚合物在离子凝胶中的质量占比为25％-40％。In the embodiment of the present application, in the ion gel, the mass proportion of polymer is 5%-50%, and the mass proportion of ionic liquid is 50%-95%. Among them, the mass proportion of ionic liquid in the ion gel is controlled to be more than 50% to ensure the formation of an ion gel without obvious macroscopic phase separation; the mass proportion of polymer in the ion gel is below 50%, which can Ensure that the strength of the ion gel is not too high, has good tensile properties, and has excellent bonding properties, which is conducive to the expansion/shrinking of the core negative active material without being damaged and falling off during the process of deintercalation of lithium. In addition, unlike hydrogels with water as the matrix or organic gel systems with organic solvents as the matrix, in the coating layer of the present application, the ion gel uses ionic liquid as the matrix. The matrix has good stability and is not easy to dissolve or dissolve. Volatilization ensures that the ion gel coating layer can perform its coating function normally and will not cause side reactions of the battery due to matrix volatilization during battery operation. For example, the mass proportion of ionic liquid in the ion gel can be 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc., and the mass proportion of the polymer in the ion gel The mass proportion can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%. In some embodiments, the mass proportion of ionic liquid in the ion gel is 60%-75%. The mass proportion of polymer in the ion gel is 25%-40%.
本申请实施方式中，所述聚合物包括式(Ⅰ)所示的聚丙烯酸酯类结构单元：
In the embodiment of the present application, the polymer includes polyacrylate structural units represented by formula (I):
In the embodiment of the present application, the polymer includes polyacrylate structural units represented by formula (I):
其中，R1选自氢原子、氟原子或甲基，R2选自氢原子、氟原子、甲基、氟代甲基、-(CH2)a-Z-，其中，a为0-6的整数，Z选自-COOH、-COOLi、-COONa、-COOK、-(CH2CH2O)nH、-(CH2CH2O)nCH3、-COOR3、-CONH2、-CONH(R4)、-CON(R5)(R6)；R3、R4、R5、R6独立地选自C1-6的烷基，n每次出现独立地选自1-20的整数。当式(Ⅰ)所示的结构单元中，R1、R1选自上述基团时，具有式(Ⅰ)所示结构单元的聚合物的极性较大，能在离子液体中顺利溶解，从而得到无明显宏观相分离的离子凝胶；此外，还可通过调控R1、R1及离子液体来实现离子凝胶对不同被包覆内核材料的粘接性能。Wherein, R 1 is selected from hydrogen atom, fluorine atom or methyl group, R 2 is selected from hydrogen atom, fluorine atom, methyl group, fluoromethyl, -(CH 2 ) a -Z-, where a is 0-6 is an integer, Z is selected from -COOH, -COOLi, -COONa, -COOK, -(CH 2 CH 2 O) n H, -(CH 2 CH 2 O) n CH 3 , -COOR 3 , -CONH 2 , - CONH(R 4 ), -CON(R 5 )(R 6 ); R 3 , R 4 , R 5 , R 6 are independently selected from C 1-6 alkyl groups, and each occurrence of n is independently selected from 1- An integer of 20. When R 1 and R 1 in the structural unit represented by formula (I) are selected from the above groups, the polymer with the structural unit represented by formula (I) has greater polarity and can be smoothly dissolved in the ionic liquid. Thus, an ion gel without obvious macroscopic phase separation is obtained; in addition, the bonding performance of the ion gel to different coated core materials can also be achieved by regulating R 1 , R 1 and the ionic liquid.
需要说明的是，上述聚合物可以是包含式(Ⅰ)所示的一种结构单元(此时的聚合物酯为均聚物)；或者是包含如式(Ⅰ)所示的多种不同结构的结构单元(此时的聚合物为共聚物)。It should be noted that the above-mentioned polymer may contain a structural unit represented by formula (I) (in this case, the polymer ester is a homopolymer); or may contain a variety of different structures represented by formula (I) structural unit (the polymer at this time is a copolymer).
本申请中，上述聚合物可通过聚合物对应的单体在引发剂存在下进行聚合反应得到。本申请实施方式中，所述聚合物的数均分子量为1kDa-1000kDa(Da是道尔顿的简写)。离子凝胶中的聚合物的分子量在此范围，有利于使离子凝胶层兼顾较高的拉伸强度、粘接性，并保证聚合物在离子液体基质中的良好分散性。In this application, the above-mentioned polymer can be obtained by polymerizing the corresponding monomer of the polymer in the presence of an initiator. In the embodiment of the present application, the number average molecular weight of the polymer is 1 kDa-1000 kDa (Da is the abbreviation of Dalton). The molecular weight of the polymer in the ion gel is within this range, which is beneficial to the ion gel layer taking into account high tensile strength and adhesion, and ensuring good dispersion of the polymer in the ionic liquid matrix.
本申请实施方式中，该离子凝胶中，聚合物可以通过物理作用交联形成三维网络结构。进一步地，还可以通过化学键作用交联形成三维网络结构。例如当上述R2为-(CH2)a-COOH-、-(CH2)a-COOLi-、-(CH2)a-COONa-、-(CH2)a-COOK-时，在多元环氧化合物、多元醇、多元胺
等交联剂的存在下，具有式(Ⅰ)所示结构单元的聚合物可以进行化学交联形成聚合物网络结构。In the embodiment of the present application, in the ion gel, the polymer can be cross-linked through physical effects to form a three-dimensional network structure. Furthermore, it can also be cross-linked through chemical bonds to form a three-dimensional network structure. For example, when the above R 2 is -(CH 2 ) a -COOH-, -(CH 2 ) a -COOLi-, -(CH 2 ) a -COONa-, -(CH 2 ) a -COOK-, in the polycyclic ring Oxygen compounds, polyols, polyamines In the presence of cross-linking agents, polymers with structural units represented by formula (I) can be chemically cross-linked to form a polymer network structure.
本申请实施方式中，所述离子液体中的阳离子包括含氮杂环阳离子、烷基铵类阳离子、烷基鏻类阳离子中的一种或多种。其中，含氮杂环阳离子可以包括烷基取代的咪唑类阳离子、烷基取代的吡咯类阳离子、烷基取代的吡啶类阳离子、烷基取代的噻唑类阳离子、烷基取代的哌啶类阳离子中的一种或多种。离子液体的阳离子选自上述范围时，各离子液体在室温下呈液态，离子电导率高，化学稳定性和热稳定性较高，电化学窗口宽，在电极中稳定性较好，从而能在内核材料表面稳定存在，且不降低内核的电学性能发挥。其中，所述离子液体中的阴离子可以包括六氟磷酸根、四氟硼酸根、三氟甲磺酰胺根、双三氟甲磺酰亚胺根、双氰基酰亚胺根、乙酸根、三氟乙酸根、无机酸根、卤素离子中的一种或多种。可以理解的是，离子凝胶中的离子液体可以有一种或者多种(即，两种以上)，每种离子液体的阴、阳离子可以独立地选自上述所列举范围。In the embodiment of the present application, the cations in the ionic liquid include one or more of nitrogen-containing heterocyclic cations, alkylammonium cations, and alkylphosphonium cations. Among them, the nitrogen-containing heterocyclic cations may include alkyl-substituted imidazole cations, alkyl-substituted pyrroles cations, alkyl-substituted pyridine cations, alkyl-substituted thiazole cations, and alkyl-substituted piperidine cations. of one or more. When the cations of the ionic liquid are selected from the above range, each ionic liquid is liquid at room temperature, has high ionic conductivity, high chemical stability and thermal stability, wide electrochemical window, and good stability in the electrode, so that it can The core material exists stably on the surface without reducing the electrical performance of the core. Wherein, the anions in the ionic liquid may include hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonamide, bistrifluoromethanesulfonimide, biscyanoimide, acetate, trifluoromethanesulfonamide, One or more of fluoroacetate, inorganic acid, and halide ions. It can be understood that there can be one or more ionic liquids (ie, two or more) in the ion gel, and the anions and cations of each ionic liquid can be independently selected from the above-mentioned range.
其中，咪唑类阳离子、吡咯类阳离子、吡啶类阳离子、噻唑类阳离子、哌啶类等氮杂环阳离子中，烷基可以取代环杂N原子上的氢原子。进一步地，烷基还可以取代环碳原子上的氢原子。所述烷基可以是碳原子数为1-6的直链或支链烷基。烷基铵阳离子可具体是季铵盐类阳离子(即，被四个烷基取代的氮离子)，烷基鏻类阳离子可具体是季鏻盐类阳离子。Among them, in imidazole cations, pyrrole cations, pyridine cations, thiazole cations, piperidine and other nitrogen heterocyclic cations, the alkyl group can replace the hydrogen atom on the ring hetero N atom. Furthermore, the alkyl group can also replace the hydrogen atom on the ring carbon atom. The alkyl group may be a straight chain or branched chain alkyl group having 1 to 6 carbon atoms. The alkylammonium cation may specifically be a quaternary ammonium salt cation (ie, a nitrogen ion substituted by four alkyl groups), and the alkylphosphonium cation may specifically be a quaternary phosphonium salt cation.
由于包覆层中，离子凝胶中离子液体的存在，包覆层20的离子电导率较高。本申请实施方式中，包覆层20的材料在室温下的离子电导率在10-4S·cm-1以上。在一些实施方式中，包覆层20的材料在室温下的离子电导率在10-4S·cm-1至5×10-2S·cm-1的范围内。Due to the presence of ionic liquid in the ion gel in the coating layer, the ionic conductivity of the coating layer 20 is relatively high. In the embodiment of the present application, the ionic conductivity of the material of the coating layer 20 at room temperature is above 10 -4 S·cm -1 . In some embodiments, the material of the cladding layer 20 has an ionic conductivity in the range of 10 -4 S·cm -1 to 5×10 -2 S·cm -1 at room temperature.
本申请实施方式中，包覆层20的断裂延伸率在100％以上，断裂强度在0.5MPa-5MPa的范围内。断裂延伸率、断裂强度都是衡量材料拉伸性能的指标。其中，断裂延伸率是描述材料塑性性能的指标，具体指试样拉伸断裂时，其塑性伸长的长度ΔL与试样原本长度L的比值。较高的断裂延伸率反映出本申请离子凝胶包覆层的韧性较好，拉伸性能优异。在一些实施方式中，包覆层20的断裂延伸率在100％-500％的范围内，例如可以为150％、200％、250％、300％、350％、400％或450％等。断裂强度又称“抗拉强度”是指材料发生断裂时的拉力与断裂横截面积的比值。较高的断裂强度反映出本申请离子凝胶包覆层的韧性较好，拉伸性能优异。In the embodiment of the present application, the breaking elongation of the coating layer 20 is above 100%, and the breaking strength is in the range of 0.5MPa-5MPa. Elongation at break and strength at break are both indicators of the tensile properties of materials. Among them, the elongation at break is an indicator that describes the plastic properties of the material. Specifically, it refers to the ratio of the plastic elongation length ΔL of the sample when it is stretched and broken to the original length L of the sample. The higher elongation at break reflects that the ion gel coating layer of the present application has good toughness and excellent tensile properties. In some embodiments, the elongation at break of the coating layer 20 is in the range of 100%-500%, for example, it may be 150%, 200%, 250%, 300%, 350%, 400% or 450%, etc. Fracture strength, also known as "tensile strength", refers to the ratio of the tensile force when a material breaks to the fracture cross-sectional area. The higher fracture strength reflects that the ion gel coating layer of the present application has better toughness and excellent tensile properties.
本申请实施方式中，上述包覆层20通过含聚合物、离子液体的前驱体溶液借助共溶剂蒸发法形成在内核材料的表面。相较于通过聚合物单体与离子液体原位交联形成的离子凝胶，本申请实施例提供的离子凝胶的韧性较高、刚性不会过大。In the embodiment of the present application, the above-mentioned coating layer 20 is formed on the surface of the core material by using a precursor solution containing a polymer and an ionic liquid through a co-solvent evaporation method. Compared with ion gels formed by in-situ cross-linking of polymer monomers and ionic liquids, the ion gels provided in the embodiments of the present application have higher toughness and are not too rigid.
本申请一些实施方式中，包覆层20中还可以包含导电剂、活性金属离子的金属盐、表面活性剂中的一种或多种助剂。其中，导电剂有利于提升包覆层20的电子电导性，金属盐有助于提升包覆层20的离子电导性，表面活性剂有助于提高包覆层的表面能，增大包覆层材料与内核材料颗粒之间的结合力。其中，导电剂可以包括导电炭黑、碳纳米管、石墨烯、石墨、无定形碳等中的一种或多种。金属盐的金属离子可以包括锂离子、钠离子、钾离子、镁离子等中的一种或多种，阴离子可以包括六氟磷酸根、四氟硼酸根、三氟甲磺酰胺根、双三氟甲磺酰亚胺根、双氰基酰亚胺根、乙酸根、三氟乙酸根、无机酸根、卤素离子等中的一种或多种。表面活性剂可以包括两亲性有机小分子、两亲性非离子型聚合物、两亲性离子型聚合物等中的一种或多种。含导电剂、金属盐、表面活性剂的添加种类及添加含量可根据上述复合材料100的具体构成体系及应用场景进行调整。In some embodiments of the present application, the coating layer 20 may also include one or more auxiliary agents among conductive agents, metal salts of active metal ions, and surfactants. Among them, the conductive agent helps to improve the electronic conductivity of the coating layer 20, the metal salt helps to improve the ionic conductivity of the coating layer 20, and the surfactant helps to increase the surface energy of the coating layer and increase the size of the coating layer. The bonding force between the material and the core material particles. The conductive agent may include one or more of conductive carbon black, carbon nanotubes, graphene, graphite, amorphous carbon, etc. The metal ions of the metal salt may include one or more of lithium ions, sodium ions, potassium ions, magnesium ions, etc., and the anions may include hexafluorophosphate, tetrafluoroborate, trifluoromethanesulfonamide, bistrifluoro One or more of methanesulfonimide, dicyanimide, acetate, trifluoroacetate, inorganic acid, halogen ions, etc. Surfactants may include one or more of amphiphilic organic small molecules, amphiphilic non-ionic polymers, amphiphilic ionic polymers, etc. The types and contents of the conductive agent, metal salt, and surfactant added can be adjusted according to the specific composition system and application scenarios of the composite material 100 mentioned above.
本申请一些实施方式中，包覆层20外还具有含掺杂元素的碳化层，所述掺杂元素源自所述离子液体。本申请中，该碳化层可以通过部分包覆层20进行碳化得到，例如在450-650℃
下煅烧碳化实现。掺杂元素可以是N、S、P、卤素元素中的一种或多种。In some embodiments of the present application, the coating layer 20 also has a carbonized layer containing doping elements, and the doping elements are derived from the ionic liquid. In this application, the carbonized layer can be obtained by carbonizing part of the coating layer 20, for example, at 450-650°C. Carbonization is achieved by calcination. The doping element may be one or more of N, S, P, and halogen elements.
由上述可知，相较于无包覆层的负极活性材料、正极活性材料、补锂剂，本申请实施例提供的带离子凝胶包覆层的复合材料具有更优的电学性能、力学性能及良好稳定性等。It can be seen from the above that compared with the negative active materials, positive active materials and lithium replenishing agents without coating layers, the composite materials with ion gel coating layers provided in the embodiments of the present application have better electrical properties, mechanical properties and Good stability, etc.
本申请实施例还提供了一种复合材料的制备方法，包括以下步骤：The embodiments of this application also provide a method for preparing composite materials, including the following steps:
S01，将聚合物、离子液体分散到溶剂中，得到离子凝胶前驱体溶液；S01, disperse the polymer and ionic liquid into the solvent to obtain the ion gel precursor solution;
S02，将内核材料与所述离子凝胶前驱体溶液进行混合，得到混合物料；其中，所述内核材料包括负极活性材料、正极活性材料、或补锂剂；S02, mix the core material and the ion gel precursor solution to obtain a mixed material; wherein the core material includes a negative active material, a positive active material, or a lithium replenishing agent;
S03，去除所述混合物料中的所述溶剂，在所述溶剂的去除过程中所述内核材料的表面形成含离子凝胶的包覆层，得到复合材料。S03, remove the solvent in the mixed material. During the removal of the solvent, a coating layer containing ion gel is formed on the surface of the core material to obtain a composite material.
离子液体、聚合物的选择范围可参见本申请前文的描述，这里不再赘述。本申请在配制前驱体溶液中直接采用聚合物而非聚合物单体，这样可避免聚合物单体与离子液体原位交联形成的离子凝胶的刚性过强、粘结性不足、不能具有较好的抗拉耐疲劳性，进而避免不能在被离子凝胶包覆的负极活性材料多次循环体积变化中保持良好的包覆层完整性；此外，采用聚合物与离子液体配制成前驱体还利于后续形成的离子凝胶包覆层中聚合物的分散均匀性。The selection range of ionic liquids and polymers can be found in the previous description of this application and will not be described again here. In this application, polymers are directly used instead of polymer monomers in preparing the precursor solution. This can avoid the ion gel formed by in-situ cross-linking of polymer monomers and ionic liquids from being too rigid, insufficient in adhesion, and unable to have Better tensile and fatigue resistance, thereby avoiding the inability to maintain good coating integrity during multiple cyclic volume changes of the negative active material coated by the ion gel; in addition, a polymer and ionic liquid are used to prepare the precursor It is also beneficial to the dispersion uniformity of the polymer in the subsequently formed ion gel coating layer.
步骤S01中，聚合物与离子液体的质量比在1：(1-19)的范围内。二者的质量比在此范围，可保证后续在去除溶剂的过程中形成无明显宏观相分离的离子凝胶，并保证离子凝胶的拉伸性能。本申请一些实施方式中，聚合物与离子液体的质量比在1：(1.5-3)的范围内。此时，采用二者形成的离子凝胶能更好地兼顾良好的拉伸性能及粘结性能。In step S01, the mass ratio of the polymer to the ionic liquid is in the range of 1: (1-19). The mass ratio between the two is within this range, which can ensure the formation of an ion gel without obvious macroscopic phase separation during the subsequent solvent removal process and ensure the tensile properties of the ion gel. In some embodiments of the present application, the mass ratio of polymer to ionic liquid is in the range of 1: (1.5-3). At this time, the ion gel formed by using the two can better balance good tensile properties and bonding properties.
本申请实施方式中，步骤S01中，所用溶剂应能将聚合物、离子液体溶解，其中，所述溶剂可以包括但不限于甲醇、乙醇、二氯甲烷、三氯甲烷、丙酮、四氢呋喃、二氧六环、甲苯、氯苯、N,N-二甲基甲酰胺(DMF)、N-甲基吡咯烷酮(NMP)、二甲基亚砜(DMSO)中的一种或多种。在一些实施方式中，离子凝胶前驱体溶液中，聚合物与离子液体的质量之和与所述溶剂的质量比在1：(5-20)的范围内。这样可保证聚合物、离子液体在溶剂中充分溶解。可选地，步骤S01中，将聚合物、离子液体在溶剂中实现溶解，所用的搅拌时间可以是5-12小时；搅拌过程中的搅拌速度可以是300-500rpm。In the embodiment of the present application, in step S01, the solvent used should be able to dissolve the polymer and ionic liquid. The solvent may include but is not limited to methanol, ethanol, dichloromethane, chloroform, acetone, tetrahydrofuran, dioxygen, etc. One or more of six rings, toluene, chlorobenzene, N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO). In some embodiments, in the ion gel precursor solution, the mass ratio of the sum of the masses of the polymer and the ionic liquid to the solvent is in the range of 1: (5-20). This ensures that the polymer and ionic liquid are fully dissolved in the solvent. Optionally, in step S01, the polymer and ionic liquid are dissolved in the solvent, and the stirring time used can be 5-12 hours; the stirring speed during the stirring process can be 300-500 rpm.
本申请一些实施方式中，步骤S01的离子凝胶前驱体溶液中还可以含有助剂，其中，助剂包括但不限于前文提及的导电剂、活性金属离子的金属盐、表面活性剂等中的一种或多种。其中，聚合物与离子液体的质量之和与所述助剂的质量比可以在1：(0.1-0.5)的范围内。In some embodiments of the present application, the ion gel precursor solution in step S01 may also contain auxiliary agents, where the auxiliary agents include but are not limited to the aforementioned conductive agents, metal salts of active metal ions, surfactants, etc. of one or more. Wherein, the mass ratio of the sum of the masses of the polymer and the ionic liquid to the additive may be in the range of 1: (0.1-0.5).
步骤S02中，内核材料通常是负极活性材料、正极活性材料或补锂剂等。将内核材料与所述离子凝胶前驱体溶液进行混合，可使内核材料的表面吸附上所述离子凝胶前驱体溶液。基于前驱体溶液的流动性，其可渗透到内核材料表面的微小空隙处，经步骤S03处理后形成的包覆层可改善内核材料的界面性能，增加其活性位点，提升比容量。In step S02, the core material is usually a negative active material, a positive active material or a lithium replenishing agent. Mixing the core material and the ion gel precursor solution allows the surface of the core material to adsorb the ion gel precursor solution. Based on the fluidity of the precursor solution, it can penetrate into the tiny gaps on the surface of the core material. The coating layer formed after step S03 can improve the interface properties of the core material, increase its active sites, and increase the specific capacity.
本申请一些实施方式中，聚合物与离子液体的质量之和与内核材料的质量比可以在1：(100-200)的范围内。这样有助于经步骤S03的处理后，在内核材料表面形成厚度合适、包覆完整度较高的离子凝胶包覆层，同时避免降低整体复合材料的克容量。In some embodiments of the present application, the mass ratio of the sum of the masses of the polymer and the ionic liquid to the core material may be in the range of 1: (100-200). This helps to form an ion gel coating layer with appropriate thickness and high coating integrity on the surface of the core material after the processing in step S03, while avoiding reducing the gram capacity of the overall composite material.
步骤S02中，内核材料与所述离子凝胶前驱体溶液的混合方式可以是机械搅拌法、高能球磨法、机械融合法。在一些实施方式中，采用机械搅拌法实现所述混合，其中，搅拌可以在20-60℃下进行；搅拌的时间可以是3h-15h。为避免固态的内核材料在搅拌过程中沉到容器底部，可控制搅拌的速度在300-500rpm的范围内。需要说明的是，内核材料可以直接以其粉体材料的形式与离子凝胶前驱体溶液混合，也可以以其和溶剂形成的分散液的形式加入。在本申请一些实施方式中，先将内核材料与所述溶剂搅拌混合(搅拌时间例如是1-2h)，得
到内核材料的分散液；再与所述离子凝胶前驱体溶液进行搅拌混合(搅拌时间例如是2-12h)。在一些实施方式中，上述导电剂、金属盐、表面活性剂等助剂也可以与内核材料一起加入，例如助剂加入到内核材料的分散液中。In step S02, the mixing method of the core material and the ion gel precursor solution may be a mechanical stirring method, a high-energy ball milling method, or a mechanical fusion method. In some embodiments, mechanical stirring is used to achieve the mixing, where the stirring can be performed at 20-60°C; the stirring time can be 3h-15h. In order to prevent the solid core material from sinking to the bottom of the container during the stirring process, the stirring speed can be controlled within the range of 300-500rpm. It should be noted that the core material can be directly mixed with the ion gel precursor solution in the form of a powder material, or can be added in the form of a dispersion formed with a solvent. In some embodiments of the present application, the core material and the solvent are first stirred and mixed (the stirring time is, for example, 1-2 h), to obtain into the core material dispersion; and then stir and mix with the ion gel precursor solution (the stirring time is, for example, 2-12 hours). In some embodiments, the above-mentioned conductive agents, metal salts, surfactants and other additives can also be added together with the core material. For example, the additives are added to the dispersion of the core material.
步骤S03中，所述溶剂的去除可以在一定温度下进行，以便溶剂挥发。在溶剂挥发的过程中，离子液体、聚合物会自发形成均相的离子凝胶，并包覆在内核材料的表面。其中，去除溶剂的温度可根据具体溶剂的挥发温度来定。其中，溶剂的去除方式可以包括旋转蒸发仪旋干、水浴锅搅干、烘箱烘干等。这些溶剂去除方式可保证混合物料中溶剂大部分去除掉甚至全部去除掉，得到基本干燥的粉末样品。In step S03, the solvent can be removed at a certain temperature to allow the solvent to volatilize. During the process of solvent evaporation, ionic liquids and polymers will spontaneously form a homogeneous ionic gel and coat the surface of the core material. Among them, the temperature for removing the solvent can be determined according to the volatilization temperature of the specific solvent. Among them, the solvent removal methods can include drying with a rotary evaporator, stirring in a water bath, drying in an oven, etc. These solvent removal methods can ensure that most or all of the solvent in the mixed material is removed, and a basically dry powder sample is obtained.
本申请一些实施方式中，在去除所述溶剂之后，还包括：将去除溶剂后得到的固态材料在50-80℃的温度下进行热处理。热处理可以使内核材料表面的离子凝胶的流动性增强，提升包覆层的包覆均匀性。热处理的时间可以为8-24h。其中，加热处理可以在真空烘箱中进行真空干燥。本申请一些实施例中，可以先通过旋转蒸发仪旋干所述混合物料的大部分溶剂，再在真空烘箱中进行真空干燥，以得到干燥度高的复合材料。In some embodiments of the present application, after removing the solvent, the method further includes: heat treating the solid material obtained after removing the solvent at a temperature of 50-80°C. Heat treatment can enhance the fluidity of the ion gel on the surface of the core material and improve the coating uniformity of the coating layer. The time of heat treatment can be 8-24h. Among them, the heat treatment can be carried out by vacuum drying in a vacuum oven. In some embodiments of the present application, most of the solvent in the mixed material can be dried using a rotary evaporator and then vacuum dried in a vacuum oven to obtain a composite material with high dryness.
本申请一些实施方式中，在热处理完成后，可将得到的复合材料粗品进行过筛处理，以筛选得到所需粒径的复合材料。考虑到本申请中离子凝胶包覆层的厚度较薄，在5-50nm级别，筛选得到的复合材料的尺寸基本与所采用微米级的内核材料原料的尺寸相当。In some embodiments of the present application, after the heat treatment is completed, the obtained crude composite material can be screened to obtain the composite material with the required particle size. Considering that the thickness of the ion gel coating layer in this application is thin, at the level of 5-50 nm, the size of the composite material obtained by screening is basically equivalent to the size of the micron-level core material raw material used.
本申请一些实施方式中，还可在步骤S03之后，将步骤S03制得的复合材料进行高温煅烧处理，以使部分离子凝胶包覆层发生碳化。此时，所得的复合材料包括内核，包裹内核的离子凝胶包覆层、包裹离子凝胶包覆层的含掺杂元素的碳化层(即无机碳包覆层)。In some embodiments of the present application, after step S03, the composite material prepared in step S03 can also be subjected to high-temperature calcination treatment to carbonize part of the ion gel coating layer. At this time, the obtained composite material includes a core, an ion gel coating layer surrounding the core, and a carbonized layer containing doped elements (ie, an inorganic carbon coating layer) surrounding the ion gel coating layer.
本申请实施例上述的复合材料的制备方法，通过将聚合物、离子液体的前驱体溶液与内核材料混合，再经溶剂蒸发，可在内核材料表面形成稳定的离子凝胶包覆层，且该包覆层与内核材料的粘结力强、包覆层的韧性高，能很好地改善内核材料的界面性能，例如能改善内核负极活性材料的体积膨胀问题，改善内核正极活性材料或内核补锂剂的水氧稳定性等。The preparation method of the composite material described in the embodiments of the present application can form a stable ion gel coating layer on the surface of the core material by mixing the precursor solution of polymer and ionic liquid with the core material, and then evaporating the solvent. The coating layer has strong bonding force with the core material and the coating layer has high toughness, which can well improve the interface properties of the core material. For example, it can improve the volume expansion problem of the core negative active material, improve the core positive active material or the core supplement. Water and oxygen stability of lithium agent, etc.
复合材料的上述制备方法，工艺简单，易于操作，适合大规模生产，所得复合材料的结构稳定性高、电化学性能良好。The above preparation method of composite materials has simple process, easy operation, and is suitable for large-scale production. The obtained composite materials have high structural stability and good electrochemical properties.
本申请实施例还提供了一种用于电池的电极极片，所述电极极片含有本申请实施例上述的复合材料。其中，电极极片可以是负极极片或正极极片。The embodiment of the present application also provides an electrode pole piece for a battery, the electrode pole piece contains the composite material mentioned in the embodiment of the present application. The electrode piece may be a negative electrode piece or a positive electrode piece.
本申请实施方式中，负极极片包括上述表面带离子凝胶包覆层的负极活性材料(即，前述内核10为负极活性材料的复合材料100)，可称为“复合负极材料”。在一实施例中，负极极片包括负极集流体和设置在负极集流体上的负极材料层，负极材料层包括前述复合负极材料、粘结剂及可选的导电剂。此时，负极极片在电池充放电循环过程中，不易发生负极极片颗粒的粉化、脱落。In the embodiment of the present application, the negative electrode sheet includes the above-mentioned negative active material with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is a negative active material), which can be called a "composite negative electrode material". In one embodiment, the negative electrode sheet includes a negative electrode current collector and a negative electrode material layer disposed on the negative electrode current collector. The negative electrode material layer includes the aforementioned composite negative electrode material, a binder, and an optional conductive agent. At this time, the negative electrode particles are less likely to pulverize and fall off during the battery charge and discharge cycle.
本申请实施方式中，正极极片包括上述表面带离子凝胶包覆层的正极活性材料(即，前述内核10为正极活性材料的复合材料100，可简称为“复合正极材料”)、和/或表面带离子凝胶包覆层的补锂剂(即，前述内核10为补锂剂的复合材料100，可称为“复合补锂剂”)。In the embodiment of the present application, the positive electrode sheet includes the above-mentioned positive electrode active material with an ion gel coating layer on the surface (that is, the aforementioned composite material 100 in which the core 10 is a positive electrode active material, which may be referred to as a "composite positive electrode material"), and/ Or a lithium replenishing agent with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is a lithium replenishing agent can be called a "composite lithium replenishing agent").
在一些实施方式中，正极极片包括正极集流体和设置在正极集流体上的正极材料层，所述正极材料层包括前述复合正极材料、粘结剂和导电剂。在一些实施例中，该正极材料层还可以含有前述复合补锂剂。在另一些实施例中，该正极材料层背离正极集流体的一侧还具有添加剂层，该添加剂层含有前述复合补锂剂、粘结剂和导电剂。由于正极活性材料或补锂剂的表面具有前述离子凝胶包覆层，在制备正极材料层所用的正极浆料、制备添加剂层所用的添加剂浆料的过程中，这些浆料不易发生凝胶化，涂布质量受影响较小。此外，这些包覆层
的基质是不易挥发的离子液体，而非易挥发的水分或有机溶剂，在极片的烘干过程中不会因基质挥发而破坏包覆层的完整性，当然在电池运行过程中也减少了水分等所带来的副反应。In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on the positive electrode current collector. The positive electrode material layer includes the aforementioned composite positive electrode material, a binder, and a conductive agent. In some embodiments, the cathode material layer may also contain the aforementioned composite lithium replenishing agent. In other embodiments, the side of the positive electrode material layer facing away from the positive electrode current collector also has an additive layer, and the additive layer contains the aforementioned composite lithium replenishing agent, binder and conductive agent. Since the surface of the positive electrode active material or lithium replenishing agent has the aforementioned ion gel coating layer, during the process of preparing the positive electrode slurry used for the positive electrode material layer and the additive slurry used for the additive layer, these slurries are not likely to gel. , the coating quality is less affected. In addition, these cladding layers The matrix is a non-volatile ionic liquid rather than volatile water or organic solvent. During the drying process of the pole piece, the integrity of the coating layer will not be damaged due to matrix volatilization. Of course, the battery will also reduce the Side reactions caused by moisture, etc.
上述粘结剂、导电剂均为电池领域的常规选择。其中，粘结剂可以具体包括但不限于聚四氟乙烯(PTFE)、聚偏氟乙烯(PVDF)、羧甲基纤维素钠(CMC)、聚丙烯酸(PAA)、聚丙烯酸酯、聚丙烯酰胺(PAM)、聚酰亚胺(PI)等中的一种或多种。导电剂可以具体包括但不限于乙炔黑、科琴黑、Supper P导电炭黑、石墨、石墨烯、碳纳米管、碳纤维、无定形碳等中的一种或多种。其中，负极集流体包括但不仅限于金属箔材、合金箔材或镀金属膜，其表面可被蚀刻处理或粗化处理，以形成次级结构，便于和负极材料层形成有效接触。示例性的金属箔材可以为铜箔、涂炭铜箔或镀铜膜，示例性的合金箔材可以是不锈钢箔、铜合金箔等。类似地，正极集流体包括但不仅限于金属箔材、合金箔材或镀金属膜，其表面可被蚀刻处理或粗化处理，以形成次级结构，便于和正极材料层形成有效接触。示例性的金属箔材可以为铝箔、涂炭铝箔或镀铝膜，示例性的合金箔材可以是不锈钢箔、铝合金箔或者涂炭不锈钢箔。The above-mentioned binders and conductive agents are conventional choices in the battery field. Among them, the binder may specifically include but is not limited to polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), sodium carboxymethylcellulose (CMC), polyacrylic acid (PAA), polyacrylate, polyacrylamide (PAM), polyimide (PI), etc. One or more. The conductive agent may specifically include, but is not limited to, one or more of acetylene black, Ketjen black, Supper P conductive carbon black, graphite, graphene, carbon nanotubes, carbon fiber, amorphous carbon, etc. Among them, the negative electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the negative electrode material layer. Exemplary metal foils may be copper foil, carbon-coated copper foil or copper-plated film, and exemplary alloy foils may be stainless steel foils, copper alloy foils, etc. Similarly, the positive electrode current collector includes but is not limited to metal foil, alloy foil or metallized film, and its surface can be etched or roughened to form a secondary structure to facilitate effective contact with the positive electrode material layer. Exemplary metal foils may be aluminum foil, carbon-coated aluminum foil or aluminum-coated films, and exemplary alloy foils may be stainless steel foils, aluminum alloy foils or carbon-coated stainless steel foils.
参见图2，本申请实施例还提供一种二次电池200，其包括上述电极极片。Referring to Figure 2, an embodiment of the present application also provides a secondary battery 200, which includes the above-mentioned electrode pole piece.
该二次电池200可以是锂二次电池、钠二次电池、钾二次电池或镁二次电池等。在一实施例中，该二次电池200是锂二次电池。该锂二次电池包括正极201、负极202、设置于正极201与负极202之间的隔膜203及电解液204，以及相应的连通辅件和回路。其中，正极201本申请实施例上述的正极极片，和/或负极202包括本申请实施例上述的负极极片。The secondary battery 200 may be a lithium secondary battery, a sodium secondary battery, a potassium secondary battery, a magnesium secondary battery, or the like. In one embodiment, the secondary battery 200 is a lithium secondary battery. The lithium secondary battery includes a positive electrode 201, a negative electrode 202, a separator 203 and an electrolyte 204 disposed between the positive electrode 201 and the negative electrode 202, as well as corresponding communication accessories and circuits. Among them, the positive electrode 201 is the positive electrode piece mentioned in the embodiment of this application, and/or the negative electrode 202 includes the negative electrode piece mentioned in the embodiment of this application.
本申请中，隔膜203可以是聚合物隔膜、无纺布等，包括但不限于单层PP(聚丙烯)膜、单层PE(聚乙烯)膜、双层PP/PE、双层PP/PP和三层PP/PE/PP等隔膜。电解液204包括活性离子盐(具体是锂盐)和有机溶剂，该有机溶剂可以包括但不限于碳酸酯类溶剂、羧酸酯类溶剂、醚类溶剂中的一种或多种。In this application, the separator 203 can be a polymer separator, non-woven fabric, etc., including but not limited to single-layer PP (polypropylene) film, single-layer PE (polyethylene) film, double-layer PP/PE, double-layer PP/PP And three-layer PP/PE/PP and other separators. The electrolyte 204 includes an active ion salt (specifically, a lithium salt) and an organic solvent. The organic solvent may include but is not limited to one or more of carbonate solvents, carboxylate solvents, and ether solvents.
在锂二次电池充电过程中，在外加电路的作用下，锂离子从正极201脱出经过电解液204、隔膜203迁移到负极202，同时电子从外电路从正极流向负极，电能被储存；放电时，锂离子从负极202脱出并经电解液204、隔膜203返回正极201，相应的电子经外电路从负极迁移到正极，对外释放电能。During the charging process of the lithium secondary battery, under the action of the external circuit, lithium ions are detached from the positive electrode 201 and migrate to the negative electrode 202 through the electrolyte 204 and the separator 203. At the same time, electrons flow from the positive electrode to the negative electrode from the external circuit, and the electric energy is stored; during discharge , the lithium ions are detached from the negative electrode 202 and return to the positive electrode 201 through the electrolyte 204 and the separator 203. The corresponding electrons migrate from the negative electrode to the positive electrode through the external circuit, releasing electric energy to the outside.
正负极的容量对二次电池的整个电芯的能量密度的提升至关重要。本申请的锂二次电池200的负极202含有上述表面带离子凝胶包覆层的负极活性材料(即，前述内核10为负极活性材料的复合材料100)，在负极活性材料为理论容量较高时(例如为硅基、磷基负极活性材料时)，本申请实施例的复合材料能在保持该类负极材料较高容量的同时，改善其循环稳定性，减小体积膨胀，提升倍率性能，有利于提升当前锂电池的容量、寿命、安全性及快充能力。此外，当锂二次电池200的正极201含有上述表面带离子凝胶包覆层的正极活性材料或补锂剂时，在电池的正极极片制备过程中，制浆过程中的浆料稳定性好，不易凝胶化，在电池运行过程中，包覆层的存在可减少电解液中微量水分等对正极活性材料或补锂剂的结构破坏，保证电池的循环寿命。The capacity of the positive and negative electrodes is crucial to improving the energy density of the entire cell of the secondary battery. The negative electrode 202 of the lithium secondary battery 200 of the present application contains the above-mentioned negative active material with an ion gel coating layer on the surface (that is, the composite material 100 in which the core 10 is the negative active material). The negative active material has a higher theoretical capacity. (for example, when it is a silicon-based or phosphorus-based negative electrode active material), the composite material of the embodiment of the present application can improve its cycle stability, reduce volume expansion, and improve rate performance while maintaining a high capacity of this type of negative electrode material. It will help improve the capacity, life, safety and fast charging capabilities of current lithium batteries. In addition, when the positive electrode 201 of the lithium secondary battery 200 contains the above-mentioned positive active material or lithium replenishing agent with an ion gel coating layer on the surface, during the preparation process of the positive electrode sheet of the battery, the slurry stability during the pulping process Good, not easy to gel. During battery operation, the existence of the coating layer can reduce the structural damage to the positive active material or lithium replenishing agent caused by trace amounts of moisture in the electrolyte, ensuring the cycle life of the battery.
本申请实施例提供的二次电池，可用于终端消费产品，如手机、平板电脑、移动电源、便携机、笔记本电脑、数码相机以及其它可穿戴或可移动的电子设备、以及无人机、电动汽车、储能设备等产品，以提高产品的竞争力。The secondary battery provided by the embodiment of the present application can be used in terminal consumer products, such as mobile phones, tablet computers, mobile power supplies, portable machines, notebook computers, digital cameras and other wearable or mobile electronic devices, as well as drones, electric Automobiles, energy storage equipment and other products to improve product competitiveness.
本申请实施例还提供一种包含有上述二次电池的电子设备。该电子设备可以是包括各种消费类电子产品，如手机、平板电脑、笔记本电脑、移动电源、便携机、以及其它可穿戴或可移动的电子设备、电视机、影碟机、录像机、摄录机、收音机、收录机、组合音响、电唱
机、激光唱机、家庭办公设备、家用电子保健设备，还可以是汽车、储能设备等产品。An embodiment of the present application also provides an electronic device including the above-mentioned secondary battery. The electronic device may include various consumer electronic products, such as mobile phones, tablet computers, notebook computers, mobile power supplies, portable machines, and other wearable or removable electronic devices, televisions, DVD players, video recorders, and camcorders. , radio, cassette player, combo stereo, electronic singing Players, compact disc players, home office equipment, home electronic health care equipment, as well as cars, energy storage equipment and other products.
一些实施方式中，参见图3，本申请实施例提供了一种电子设备300，其包括壳体301和容纳于壳体301内的电子元器件(图3中未示出)和电池302，电池302为电子设备300供电，电池302包括本申请实施例上述的锂二次电池200。在一些实施方式中，壳体301可包括组装在终端前侧的前盖和组装在后侧的后壳，电池302可固定在后壳内侧。In some embodiments, referring to Figure 3, this embodiment of the present application provides an electronic device 300, which includes a housing 301, electronic components (not shown in Figure 3) accommodated in the housing 301, and a battery 302. The battery 302 supplies power to the electronic device 300, and the battery 302 includes the lithium secondary battery 200 described in the embodiment of the present application. In some embodiments, the housing 301 may include a front cover assembled on the front side of the terminal and a rear case assembled on the rear side, and the battery 302 may be fixed inside the rear case.
另一些实施方式中，参见图4，本申请实施例提供了一种电子设备400，其可以是各种用于装载、运输、组装、拆卸、安防等可移动装置，例如是各种形式的车辆。具体地，该电子设备400可包括车体401、移动组件402、驱动组件，驱动组件包括电机403及电池***404，电池***404包括本申请实施例提供的上述二次电池200。其中，移动组件402可以是车轮。电池***404可以是包含上述二次电池200的电池包，其容置在车辆的车体底部，并与电机403电连接，其可以为电机403供电，电机403提供动力以驱动电子设备400的移动组件402移动。In other embodiments, referring to FIG. 4 , the embodiment of the present application provides an electronic device 400 , which can be various movable devices used for loading, transportation, assembly, disassembly, security, etc., such as various forms of vehicles. . Specifically, the electronic device 400 may include a vehicle body 401, a moving component 402, and a driving component. The driving component includes a motor 403 and a battery system 404. The battery system 404 includes the above-mentioned secondary battery 200 provided in the embodiment of the present application. Wherein, the moving component 402 may be a wheel. The battery system 404 can be a battery pack including the above-mentioned secondary battery 200, which is housed at the bottom of the vehicle body and is electrically connected to the motor 403. It can provide power to the motor 403, and the motor 403 provides power to drive the movement of the electronic device 400. Component 402 moves.
下面分多个实施例对本申请实施例进行进一步的说明。The embodiments of the present application will be further described below in multiple embodiments.
实施例1——离子凝胶包覆的负极活性材料Example 1 - Ion gel-coated negative active material
(1)将数均分子量为100kDa的聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物30mg(该聚合物同时含有结构单元)与离子液体(具体是1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐)60mg加入到1g的甲醇中，在30℃下以300rpm的转速6小时，使聚合物和离子液体完全溶解，得到离子凝胶前驱体溶液；(1) 30 mg of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer with a number average molecular weight of 100 kDa (the polymer also contains structural units ) and ionic liquid (specifically 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt) 60 mg were added to 1 g of methanol, and the polymer was heated at 30°C for 6 hours at 300 rpm. The ionic liquid is completely dissolved to obtain an ion gel precursor solution;
(2)将10g的负极活性材料粉末(具体是表面具有碳包覆层的硅氧化物，SiOx@C，粒径约为5μm)加入到30g甲醇中，在30℃下以300rpm的转速1小时，得到硅氧材料的分散液；将步骤(1)中的前驱体溶液在搅拌状态下加入到硅氧材料的分散液中，在30℃下以300rpm的转速6小时，得到混合物料；(2) Add 10g of negative active material powder (specifically, silicon oxide with a carbon coating layer on the surface, SiOx@C, with a particle size of about 5 μm) into 30g of methanol, and heat at 30°C for 1 hour at 300rpm. , obtain a dispersion of silicone material; add the precursor solution in step (1) to the dispersion of silicone material under stirring, and heat at 30°C and a rotation speed of 300rpm for 6 hours to obtain a mixed material;
(3)利用旋转蒸发(减压40℃下)除去上述混合物料中的溶剂甲醇，将得到的粉末样品置于真空干燥箱中50℃干燥24h，得到复合负极材料，即，表面具有离子凝胶包覆层的硅氧化物。该离子凝胶包括聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物和分散在该共聚物的三维网络结构中的1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐。(3) Use rotary evaporation (under reduced pressure at 40°C) to remove the solvent methanol in the above mixture, and place the obtained powder sample in a vacuum drying box to dry at 50°C for 24 hours to obtain a composite negative electrode material, that is, with an ion gel on the surface Silicon oxide cladding. The ion gel includes poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer and 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide salt dispersed in the three-dimensional network structure of the copolymer.
图5为本申请实施例1中硅氧化物在包覆前(a)、包覆后(b)的表面微观形貌及能谱仪(Energy Dispersive Spectroscopy，EDS)元素分析结果。其中，与图5中(a)列示出的未经离子凝胶包覆的硅氧化物相比，在采用本申请实施例1的上述方法处理后可以看出，硅氧化物的表面有凝胶状包覆物的存在。表面EDS元素分析表征也显示，包覆后，所得复合材料中C、O元素的含量显著提高，Si的含量减少，这表明材料表面存在新的有机物包覆层。Figure 5 shows the surface micromorphology and energy dispersive spectroscopy (EDS) elemental analysis results of the silicon oxide in Example 1 of the present application before coating (a) and after coating (b). Among them, compared with the silicon oxide that is not coated with ion gel as shown in column (a) of Figure 5, after using the above method of Example 1 of the present application, it can be seen that the surface of the silicon oxide has coagulation. Presence of gelatinous coating. Surface EDS elemental analysis and characterization also showed that after coating, the content of C and O elements in the obtained composite material increased significantly, and the content of Si decreased, which indicated that there was a new organic coating layer on the surface of the material.
其中，实施例1所得的复合负极材料中，离子凝胶包覆层中，离子液体的质量占比为66.7％，聚合物构成的三维网络结构的质量占比约为33.3％。该包覆层的厚度约为6nm，该包覆层在室温下的离子电导率约为5×10-3S·cm-1，包覆层的断裂延伸率为470％，断裂强度为2.5MPa。Among them, in the composite negative electrode material obtained in Example 1, the mass proportion of ionic liquid in the ion gel coating layer is 66.7%, and the mass proportion of the three-dimensional network structure composed of polymer is approximately 33.3%. The thickness of the coating layer is about 6nm, the ionic conductivity of the coating layer at room temperature is about 5×10 -3 S·cm -1 , the fracture elongation of the coating layer is 470%, and the fracture strength is 2.5MPa .
实施例2Example 2
实施例2的复合负极材料与实施例1的区别在于：在步骤(2)的硅氧材料的分散液中，还加入有导电剂-单臂碳纳米管。
The difference between the composite negative electrode material of Example 2 and Example 1 is that a conductive agent - single-arm carbon nanotubes is also added to the dispersion of silicone material in step (2).
对比例1Comparative example 1
直接以实施例1中所用内核原料-未经表面改性的SiOx@C作为负极活性材料。The core raw material used in Example 1 - SiOx@C without surface modification was directly used as the negative active material.
将实施例1、2得到的复合负极材料、对比例1的SiOx@C分别与粘结剂(具体为商用聚丙烯酸水溶液)、导电剂(具体是Super P导电炭黑)按质量比为75:15:10的质量比混合，并用水稀释，充分搅拌后，得到负极浆料；将该负极浆料涂布在负极集流体(具体是铜箔)上，经真空干燥、辊压、分切后，得到负极极片。以金属锂片作对电极，将负极极片与商用PE隔膜和1mol/L LiPF6/(EC+DEC)电解液(体积比1:1)，在氩气保护的手套箱中组装成2032型扣式电池。The composite negative electrode materials obtained in Examples 1 and 2 and the SiOx@C of Comparative Example 1 were respectively mixed with the binder (specifically, a commercial polyacrylic acid aqueous solution) and the conductive agent (specifically, Super P conductive carbon black) in a mass ratio of 75: Mix with a mass ratio of 15:10, dilute with water, and stir thoroughly to obtain a negative electrode slurry; apply the negative electrode slurry on the negative electrode current collector (specifically, copper foil), vacuum dry, roll, and cut. , get the negative electrode piece. Use the metal lithium sheet as the counter electrode, assemble the negative electrode sheet, commercial PE separator and 1mol/L LiPF 6 /(EC+DEC) electrolyte (volume ratio 1:1) in an argon-protected glove box to form a 2032-type buckle. type battery.
为对本申请实施例的有益效果进行有力支持，将实施例1-2及对比例1的复合负极材料制得的扣式电池进行如表1所示的电化学性能测试，其中，测试温度25±5℃，以0.05C/0.02C充放电倍率在0.05V～1.5V的电压区间内对扣式电池进行充放电测试。In order to strongly support the beneficial effects of the embodiments of the present application, the button batteries made of the composite negative electrode materials of Examples 1-2 and Comparative Example 1 were subjected to electrochemical performance tests as shown in Table 1, where the test temperature was 25± 5℃, conduct charge and discharge tests on button batteries in the voltage range of 0.05V ~ 1.5V at a charge and discharge rate of 0.05C/0.02C.
表1.不同样品的电池性能测试结果
Table 1. Battery performance test results of different samples
Table 1. Battery performance test results of different samples
从表1可以获知，商用的负极活性材料SiOx@C经包覆上本申请实施例的离子凝胶层后，采用其制得的锂扣式电池的循环稳定性明显提升，负极极片的膨胀率大大降低，且电池的首次脱锂容量也得到一定提升。It can be seen from Table 1 that after the commercial negative active material SiOx@C is coated with the ion gel layer of the embodiment of the present application, the cycle stability of the lithium button battery produced using it is significantly improved, and the expansion of the negative electrode sheet The rate is greatly reduced, and the first delithium capacity of the battery is also improved to a certain extent.
实施例3Example 3
实施例3的复合负极材料与实施例1的区别在于：将实施例1中的溶剂替换为丙酮，将实施例1中的聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物替换为数均分子量为450kDa的聚(偏二氟乙烯-co-六氟丙烯)共聚物，该聚合物同时含有结构单元
The difference between the composite negative electrode material of Example 3 and Example 1 is that the solvent in Example 1 is replaced with acetone, and the poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is replaced with a number average molecular weight of 450kDa poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, which also contains structural units
具体地，实施例3的复合负极材料的制备方法，包括以下步骤：Specifically, the preparation method of the composite negative electrode material of Example 3 includes the following steps:
(1)将数均分子量为450kDa的聚(偏二氟乙烯-co-六氟丙烯)共聚物30mg与离子液体(具体是1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐)60mg加入到1g的丙酮中，在30℃下以300rpm的转速6小时，使聚合物和离子液体完全溶解，得到离子凝胶前驱体溶液；(1) Mix 30 mg of poly(vinylidene fluoride-co-hexafluoropropylene) copolymer with a number average molecular weight of 450 kDa and ionic liquid (specifically 1-ethyl-3-methylimidazole bistrifluoromethanesulfonimide Salt) 60 mg was added to 1 g of acetone, and the polymer and ionic liquid were completely dissolved at 30°C and a rotation speed of 300 rpm for 6 hours to obtain an ion gel precursor solution;
(2)将10g的负极活性材料粉末(具体是商用硅氧材料)加入到30g的丙酮中，在30℃下以300rpm的转速1小时，得到硅氧材料的分散液；将步骤(1)中的前驱体溶液在搅拌状态下加入到硅氧材料的分散液中，在30℃下以300rpm的转速6小时，得到混合物料；(2) Add 10g of negative active material powder (specifically commercial silicone material) to 30g of acetone, and heat at 30°C and 300rpm for 1 hour to obtain a dispersion of silicone material; add the dispersion in step (1) The precursor solution is added to the dispersion of silicone material under stirring, and the mixed material is obtained at 30°C and a rotation speed of 300 rpm for 6 hours;
(3)利用旋转蒸发(减压40℃下)除去上述混合物料中的溶剂丙酮，将得到的粉末样品置于真空干燥箱中50℃干燥24h，得到复合负极材料，即，表面具有离子凝胶包覆层的硅氧化物。该离子凝胶包括聚聚(偏二氟乙烯-co-六氟丙烯)共聚物和分散在该共聚物的三维网络结构中的1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐。
(3) Use rotary evaporation (under reduced pressure at 40°C) to remove the solvent acetone in the above mixture, and place the obtained powder sample in a vacuum drying box to dry at 50°C for 24 hours to obtain a composite negative electrode material, that is, with an ion gel on the surface Silicon oxide cladding. The ion gel includes poly(vinylidene fluoride-co-hexafluoropropylene) copolymer and 1-ethyl-3-methylimidazole bistriflate dispersed in the three-dimensional network structure of the copolymer. Amine salt.
其中，实施例3所得的复合负极材料中，离子凝胶包覆层在室温下的离子电导率约为3×10-3S·cm-1，包覆层的断裂延伸率为200％，断裂强度为2MPa。Among them, in the composite negative electrode material obtained in Example 3, the ion conductivity of the ion gel coating layer at room temperature is approximately 3×10 -3 S·cm -1 , the elongation at break of the coating layer is 200%, and the ion conductivity at room temperature is approximately 3×10 -3 S·cm -1 . The strength is 2MPa.
实施例4Example 4
实施例4提供的复合负极材料，其制备方法与实施例1的不同之处在于：在步骤(2)的硅氧材料的分散液中，还加入有三官能度氮丙啶交联剂。The difference between the preparation method of the composite negative electrode material provided in Example 4 and that of Example 1 is that a trifunctional aziridine cross-linking agent is also added to the silicone material dispersion in step (2).
其中，实施例4所得的复合负极材料中，离子凝胶包覆层在室温下的离子电导率约为4×10-3S·cm-1，包覆层的断裂延伸率为200％，断裂强度为4.5MPa。Among them, in the composite negative electrode material obtained in Example 4, the ion conductivity of the ion gel coating layer at room temperature is approximately 4×10 -3 S·cm -1 , the elongation at break of the coating layer is 200%, and the ion conductivity at room temperature is approximately 4×10 -3 S·cm -1 . The strength is 4.5MPa.
与实施例1相比，在同等情况下，引入交联剂助剂后，离子凝胶包覆层的断裂强度得到一定提升。Compared with Example 1, under the same circumstances, after introducing the cross-linking agent auxiliary agent, the breaking strength of the ion gel coating layer is improved to a certain extent.
实施例5Example 5
实施例5提供的复合负极材料，其制备方法与实施例1的不同之处在于：所用离子液体具体为1-乙基-3-甲基咪唑六氟磷酸盐。The preparation method of the composite negative electrode material provided in Example 5 is different from that in Example 1 in that the ionic liquid used is specifically 1-ethyl-3-methylimidazole hexafluorophosphate.
其中，实施例5所得的复合负极材料中，离子凝胶包覆层在室温下的离子电导率约为4.2×10-3S·cm-1，包覆层的断裂延伸率为450％，断裂强度为2.5MPa。Among them, in the composite negative electrode material obtained in Example 5, the ion conductivity of the ion gel coating layer at room temperature is approximately 4.2×10 -3 S·cm -1 , the rupture elongation of the coating layer is 450%, and the ion conductivity at room temperature is approximately 4.2×10 -3 S·cm -1 . The strength is 2.5MPa.
实施例6Example 6
实施例6提供的复合负极材料，其制备方法与实施例1的不同之处在于：所用离子液体具体为N-丁基-N-甲基吡咯烷双(三氟甲烷磺酰)亚胺盐(CAS号是223437-11-4)。The preparation method of the composite negative electrode material provided in Example 6 is different from that in Example 1 in that the ionic liquid used is specifically N-butyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide salt ( CAS number is 223437-11-4).
其中，实施例6所得的复合负极材料中，离子凝胶包覆层在室温下的离子电导率约为4.5×10-3S·cm-1，包覆层的断裂延伸率为400％，断裂强度为3MPa。Among them, in the composite negative electrode material obtained in Example 6, the ionic conductivity of the ion gel coating layer at room temperature is approximately 4.5×10 -3 S·cm -1 , the elongation at break of the coating layer is 400%, and the elongation at break is The strength is 3MPa.
实施例7Example 7
一种复合负极材料，其制备方法与实施例1的不同之处在于：将实施例1中聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物的用量从30mg修改为45mg，离子液体的用量从60mg修改为45mg。A composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is modified from 30 mg to 45 mg, and the amount of ionic liquid is changed from 60mg was revised to 45mg.
其中，实施例7所得的复合负极材料中，离子凝胶包覆层的厚度约为5nm，该包覆层在室温下的离子电导率约为2×10-3S·cm-1，包覆层的断裂延伸率为200％，断裂强度为4MPa。Among them, in the composite negative electrode material obtained in Example 7, the thickness of the ion gel coating layer is about 5 nm, and the ionic conductivity of the coating layer at room temperature is about 2×10 -3 S·cm -1 . The layer has an elongation at break of 200% and a strength at break of 4MPa.
实施例8Example 8
一种复合负极材料，其制备方法与实施例1的不同之处在于：将实施例1中聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物的用量从30mg修改为4.5mg，离子液体的用量从60mg修改为85.5mg。A composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is modified from 30 mg to 4.5 mg, and the amount of ionic liquid is Modified from 60mg to 85.5mg.
其中，实施例8所得的复合负极材料中，离子凝胶包覆层的厚度约为5nm，该包覆层在室温下的离子电导率约为8×10-3S·cm-1，包覆层的断裂延伸率为1000％，断裂强度为1MPa。Among them, in the composite negative electrode material obtained in Example 8, the thickness of the ion gel coating layer is about 5 nm, and the ionic conductivity of the coating layer at room temperature is about 8×10 -3 S·cm -1 . The layer has an elongation at break of 1000% and a strength at break of 1 MPa.
从实施例7-8、实施例1可以看出，当离子凝胶的总质量不变时，离子液体的占比较大时，离子凝胶包覆层的离子电导率较高，断裂延伸率变大，断裂强度有所降低。It can be seen from Examples 7-8 and 1 that when the total mass of the ion gel remains unchanged and the proportion of ionic liquid is large, the ionic conductivity of the ion gel coating layer is higher and the elongation at break becomes Large, the breaking strength is reduced.
实施例9Example 9
一种复合负极材料，其制备方法与实施例1的不同之处在于：将实施例1中聚(丙烯酸-
丙烯酸锂-丙烯酸乙酯)共聚物的用量从30mg提高至40mg。A composite negative electrode material, the preparation method of which is different from that of Example 1 is: the poly(acrylic acid- The dosage of lithium acrylate-ethyl acrylate copolymer was increased from 30 mg to 40 mg.
实施例9所得的复合负极材料中，离子凝胶包覆层的厚度约为8nm，包覆层的质量占内核质量的1％，该包覆层在室温下的离子电导率约为4×10-3S·cm-1，包覆层的断裂延伸率为200％，断裂强度为5MPa。In the composite negative electrode material obtained in Example 9, the thickness of the ion gel coating layer is about 8 nm, the mass of the coating layer accounts for 1% of the core mass, and the ionic conductivity of the coating layer at room temperature is about 4×10 -3 S·cm -1 , the breaking elongation of the coating layer is 200%, and the breaking strength is 5MPa.
实施例10Example 10
一种复合负极材料，其制备方法与实施例1的不同之处在于：将实施例1中聚(丙烯酸-丙烯酸锂-丙烯酸乙酯)共聚物的用量从30mg提高至120mg，1-乙基-3-甲基咪唑双三氟甲磺酰亚胺盐的用量从60mg提高至240mg，相对应的有机溶剂甲醇的量也提升四倍，保持活性材料的质量不变。A composite negative electrode material, the preparation method of which is different from that in Example 1 is that the amount of poly(acrylic acid-lithium acrylate-ethyl acrylate) copolymer in Example 1 is increased from 30 mg to 120 mg, 1-ethyl- The dosage of 3-methylimidazole bistrifluoromethanesulfonimide salt was increased from 60 mg to 240 mg, and the corresponding amount of organic solvent methanol was also increased four times, keeping the quality of the active material unchanged.
实施例10所得的复合负极材料中，离子凝胶包覆层的厚度约为20nm，该包覆层在室温下的离子电导率约为5×10-3S·cm-1，包覆层的断裂延伸率为470％，断裂强度为2.5MPa。In the composite negative electrode material obtained in Example 10, the thickness of the ion gel coating layer is about 20 nm, and the ionic conductivity of the coating layer at room temperature is about 5×10 -3 S·cm -1 . The elongation at break is 470% and the strength at break is 2.5MPa.
与实施例1相比，实施例10中包覆层在整体复合负极材料中的质量占比提升，有助于进一步改善材料的稳定性，提升其首次库伦效率，但是由于非活性组分的增加，材料容量会有一定程度的下降。其中，按上述实施例1的方式，将实施例10的复合负极材料制成扣式电池，测得其首次库伦效率为88％(实施例1是86％)，其中，首次嵌锂容量为1448.1mAh/g，首次脱锂容量为1274.3mAh/g。Compared with Example 1, the mass proportion of the coating layer in the overall composite negative electrode material in Example 10 is increased, which helps to further improve the stability of the material and increase its first Coulombic efficiency. However, due to the increase in inactive components , the material capacity will decrease to a certain extent. Among them, the composite negative electrode material of Example 10 was made into a button battery according to the method of Example 1, and the first Coulombic efficiency was measured to be 88% (Example 1 was 86%), and the first lithium insertion capacity was 1448.1 mAh/g, the first delithiation capacity is 1274.3mAh/g.
实施例11Example 11
一种复合负极材料，其制备方法与实施例1的不同之处在于：步骤(3)中，在真空干燥之后，还将所得固态粉末在550℃下进行高温煅烧3h，以使部分离子凝胶包覆层发生碳化。A composite negative electrode material, the preparation method of which is different from that of Example 1 is that: in step (3), after vacuum drying, the obtained solid powder is calcined at high temperature at 550°C for 3 hours to make part of the ion gel The cladding layer is carbonized.
实施例11所得的复合负极材料，在离子凝胶包覆层外，还具有厚度约为1nm的无机碳包覆层(含F、N、S掺杂元素)。该掺杂碳包覆层的存在，有助于提升复合负极材料的导电性，进而采用该复合负极材料制得的电池的倍率性能也得到提升。The composite negative electrode material obtained in Example 11 also has an inorganic carbon coating layer (containing F, N, and S doping elements) with a thickness of approximately 1 nm in addition to the ion gel coating layer. The existence of the doped carbon coating layer helps to improve the conductivity of the composite negative electrode material, and then the rate performance of the battery made of the composite negative electrode material is also improved.
实施例12Example 12
实施例12提供了一种复合正极材料，其制备方法与实施例1的不同之处在于：将实施例1中的负极活性材料-硅氧化物替换为高镍三元正极活性材料(其结构通式为镍钴锰酸锂LiNi0.83Co0.12Mn0.05O2，粒径约为4.3μm)。Embodiment 12 provides a composite cathode material. The preparation method is different from that in Example 1 in that the negative active material-silicon oxide in Example 1 is replaced with a high-nickel ternary cathode active material (its structure is generally The formula is lithium nickel cobalt manganate LiNi 0.83 Co 0.12 Mn 0.05 O 2 , and the particle size is about 4.3 μm).
其中，实施例12所得的复合正极材料中，离子凝胶包覆层的厚度约为8nm，该包覆层的断裂延伸率为470％，断裂强度为2.5MPa。Among them, in the composite cathode material obtained in Example 12, the thickness of the ion gel coating layer is about 8 nm, the elongation at break of the coating layer is 470%, and the breaking strength is 2.5 MPa.
与未经包覆的镍钴锰酸锂相比，本申请实施例12提供的核壳型复合正极材料在环境湿度为25％下存储30天，不会发生潮解吸水；而单纯的高镍镍钴锰三元材料在该湿度下，存放超过一天就会因潮解出现电化学性能下降，采用其制备时也极易出现凝胶化现象。这表明离子凝胶包覆层可提高内核正极活性材料的水氧稳定性。此外，当将该复合正极材料与粘结剂、导电剂、水配制成正极浆料时，在制浆搅拌过程中，因内核表面离子凝胶包覆层的存在，不会出现浆料凝胶化现象。Compared with uncoated lithium nickel cobalt manganate, the core-shell composite cathode material provided in Example 12 of the present application will not deliquesce and absorb water when stored at an ambient humidity of 25% for 30 days; while pure high-nickel nickel If the cobalt-manganese ternary material is stored at this humidity for more than one day, its electrochemical performance will decrease due to deliquescence, and gelation will easily occur when it is prepared. This indicates that the ion gel coating layer can improve the water and oxygen stability of the core cathode active material. In addition, when the composite cathode material is mixed with a binder, a conductive agent, and water to form a cathode slurry, during the slurry stirring process, no slurry gel will appear due to the presence of the ion gel coating layer on the core surface. phenomenon.
以上所述仅表达了本申请的几种示例性实施方式，其描述较为具体和详细，但并不能因此而理解为对本申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都应涵盖在本申请的保护范围内。因此，本申请专利的保护范围应以所附权利要求为准。
The above description only expresses several exemplary embodiments of the present application. The descriptions are relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these should be covered by the protection scope of the present application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims (15)
- 一种复合材料，其特征在于，所述复合材料包括内核和包覆在所述内核上的包覆层，其中，所述内核包括负极活性材料、正极活性材料、或补锂剂，所述包覆层包括离子凝胶，所述离子凝胶包括聚合物和离子液体，所述离子液体分散在所述聚合物形成的三维网络结构中。A composite material, characterized in that the composite material includes a core and a coating layer covering the core, wherein the core includes a negative active material, a positive active material, or a lithium replenishing agent, and the coating The coating includes an ion gel that includes a polymer and an ionic liquid dispersed in a three-dimensional network structure formed by the polymer.
- 如权利要求1所述的复合材料，其特征在于，所述包覆层的厚度为5nm-50nm。The composite material according to claim 1, wherein the thickness of the coating layer is 5nm-50nm.
- 如权利要求1或2所述的复合材料，其特征在于，所述离子凝胶中，聚合物的质量占比为5％-50％，离子液体的质量占比为50％-95％。The composite material according to claim 1 or 2, characterized in that in the ion gel, the mass proportion of polymer is 5%-50%, and the mass proportion of ionic liquid is 50%-95%.
- 如权利要求1-3任一项所述的复合材料，其特征在于，所述聚合物包括式(Ⅰ)所示的结构单元：
The composite material according to any one of claims 1 to 3, characterized in that the polymer includes structural units represented by formula (I):
其中，R1选自氢原子、氟原子或甲基，R2选自氢原子、氟原子、甲基、氟代甲基、-(CH2)a-Z-，其中，a为0-6的整数，Z选自-COOH、-COOLi、-COONa、-COOK、-(CH2CH2O)nH、-(CH2CH2O)nCH3、-COOR3、-CONH2、-CONH(R4)、-CON(R5)(R6)；R3、R4、R5、R6独立地选自C1-6的烷基，n每次出现独立地选自1-20的整数。Wherein, R 1 is selected from hydrogen atom, fluorine atom or methyl group, R 2 is selected from hydrogen atom, fluorine atom, methyl group, fluoromethyl, -(CH 2 ) a -Z-, where a is 0-6 is an integer, Z is selected from -COOH, -COOLi, -COONa, -COOK, -(CH 2 CH 2 O) n H, -(CH 2 CH 2 O) n CH 3 , -COOR 3 , -CONH 2 , - CONH(R 4 ), -CON(R 5 )(R 6 ); R 3 , R 4 , R 5 , R 6 are independently selected from C 1-6 alkyl groups, and each occurrence of n is independently selected from 1- An integer of 20. - 如权利要求1-4任一项所述的复合材料，其特征在于，所述聚合物的数均分子量为1kDa-1000kDa。The composite material according to any one of claims 1 to 4, characterized in that the number average molecular weight of the polymer is 1 kDa to 1000 kDa.
- 如权利要求1-5任一项所述的复合材料，其特征在于，所述离子液体中的阳离子包括烷基取代的咪唑类阳离子、烷基取代的吡咯类阳离子、烷基取代的吡啶类阳离子、烷基取代的噻唑类阳离子、烷基取代的哌啶类阳离子、烷基铵类阳离子、烷基鏻类阳离子中的一种或多种。The composite material according to any one of claims 1 to 5, wherein the cations in the ionic liquid include alkyl-substituted imidazole cations, alkyl-substituted pyrroles cations, and alkyl-substituted pyridine cations. , one or more of alkyl-substituted thiazole cations, alkyl-substituted piperidine cations, alkyl ammonium cations, and alkyl phosphonium cations.
- 如权利要求1-6任一项所述的复合材料，其特征在于，所述包覆层的材料在室温下的离子电导率在10-4S·cm-1以上。The composite material according to any one of claims 1 to 6, characterized in that the ionic conductivity of the material of the coating layer at room temperature is above 10 -4 S·cm -1 .
- 如权利要求1-7任一项所述的复合材料，其特征在于，所述包覆层的断裂延伸率在100％以上，断裂强度在0.5MPa-5Mpa的范围内。The composite material according to any one of claims 1 to 7, characterized in that the rupture elongation of the coating layer is above 100%, and the rupture strength is in the range of 0.5MPa-5MPa.
- 如权利要求1-8任一项所述的复合材料，其特征在于，所述包覆层中还包含导电剂、活性金属离子的金属盐、表面活性剂中的一种或多种。The composite material according to any one of claims 1 to 8, characterized in that the coating layer further contains one or more of a conductive agent, a metal salt of active metal ions, and a surfactant.
- 如权利要求1-9任一项所述的复合材料，其特征在于，所述包覆层外还具有含掺杂元素的碳化层，其中，所述掺杂元素源自所述离子液体。The composite material according to any one of claims 1 to 9, characterized in that the coating layer also has a carbonized layer containing doping elements, wherein the doping elements are derived from the ionic liquid.
- 一种复合材料的制备方法，其特征在于，包括以下步骤：A method for preparing composite materials, characterized by comprising the following steps:将聚合物、离子液体分散到溶剂中，得到离子凝胶前驱体溶液；Disperse the polymer and ionic liquid into the solvent to obtain an ion gel precursor solution;将内核材料与所述离子凝胶前驱体溶液进行混合，得到混合物料；其中，所述内核材料包括负极活性材料、正极活性材料、或补锂剂；Mix the core material and the ion gel precursor solution to obtain a mixed material; wherein the core material includes a negative active material, a positive active material, or a lithium replenishing agent;去除所述混合物料中的所述溶剂，在所述溶剂的去除过程中所述内核材料的表面形成含离子凝胶的包覆层，得到复合材料。The solvent in the mixed material is removed. During the removal of the solvent, a coating layer containing ion gel is formed on the surface of the core material to obtain a composite material.
- 如权利要求11所述的制备方法，其特征在于，在去除所述溶剂之后，还包括：The preparation method according to claim 11, characterized in that, after removing the solvent, it further includes:将去除溶剂后得到的固态材料在50-80℃的温度下进行热处理。The solid material obtained after removing the solvent is heat treated at a temperature of 50-80°C.
- 一种电极极片，其特征在于，所述电极极片含有如权利要求1-10任一项所述的复合 材料。An electrode pole piece, characterized in that the electrode pole piece contains the composite compound according to any one of claims 1-10. Material.
- 一种二次电池，其特征在于，所述二次电池包括如权利要求13所述的电极极片。A secondary battery, characterized in that the secondary battery includes the electrode pole piece according to claim 13.
- 一种电子设备，其特征在于，所述电子设备包括如权利要求14所述的二次电池。 An electronic device, characterized in that the electronic device includes the secondary battery according to claim 14.
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