WO2023184209A1 - 一种粘结剂、负极极片、电化学装置及电子装置 - Google Patents

一种粘结剂、负极极片、电化学装置及电子装置 Download PDF

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WO2023184209A1
WO2023184209A1 PCT/CN2022/083967 CN2022083967W WO2023184209A1 WO 2023184209 A1 WO2023184209 A1 WO 2023184209A1 CN 2022083967 W CN2022083967 W CN 2022083967W WO 2023184209 A1 WO2023184209 A1 WO 2023184209A1
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monomer
negative electrode
binder
active material
application
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PCT/CN2022/083967
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English (en)
French (fr)
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程宝校
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宁德新能源科技有限公司
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Priority to PCT/CN2022/083967 priority Critical patent/WO2023184209A1/zh
Priority to CN202280006060.7A priority patent/CN116195084A/zh
Publication of WO2023184209A1 publication Critical patent/WO2023184209A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • 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 electrochemistry technology, specifically to a binder, a negative electrode piece, an electrochemical device and an electronic device.
  • Lithium-ion batteries electrochemical devices
  • electrochemical devices have many advantages such as large volume and mass energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, and are widely used in the field of consumer electronics.
  • people With the rapid development of electric vehicles and mobile electronic devices in recent years, people have higher and higher demands for the safety performance and cycle performance of lithium-ion batteries, and they are looking forward to the emergence of new lithium-ion batteries with comprehensively improved comprehensive performance.
  • the negative active material layer on the negative electrode sheet of a lithium-ion battery is usually prepared by a coating method.
  • the binder in the negative active material layer has poor kinetics and uneven film distribution (on the surface of the negative active material particles).
  • the shortcomings of easy agglomeration and cluster-like distribution during film formation are not conducive to the cycle performance and expansion performance of lithium-ion batteries.
  • the purpose of this application is to provide a binder, negative electrode piece, electrochemical device and electronic device to improve the cycle performance and expansion performance of the electrochemical device.
  • the specific technical solutions are as follows:
  • a first aspect of the application provides a binder, including a copolymer, wherein the copolymer is obtained by copolymerizing a mixture including a first monomer butadiene, a second monomer styrene, a third Three monomers, cross-linking monomers and emulsifiers; the third monomer includes at least one of (meth)acrylate, acrylonitrile, acrylic acid and its derivatives, the cross-linking monomer includes triethylene glycol At least one of alcohol diacrylate, N,N-methylene bisacrylamide, ethylene glycol diacrylate or ethylene glycol diacrylate. The first monomer and the second monomer serve as the main structure of the binder.
  • the first monomer provides the binder with high toughness
  • the second monomer provides the binder with high strength and high glass transition temperature (Tg).
  • Tg glass transition temperature
  • the third monomer provides hydrophilicity to the binder, improves the dispersion of the binder emulsion particles, and facilitates discrete distribution and film formation on the surface of the negative active material;
  • the cross-linking monomer provides a cross-linked structure, which can improve the binder's performance Tg, reduces the migration of molecular chains to form films;
  • the emulsifier provides high adhesion.
  • the binder provided by this application is discretely distributed when forming a film on the surface of the negative active material, is evenly dispersed, and has high adhesion. Its application in the negative electrode piece can improve the structural stability of the negative electrode piece, thereby improving the electrochemical device. cycle performance and expansion performance.
  • the mass ratio of the first monomer, the second monomer and the third monomer is (15% to 35%): (60% to 85%): (0% to 15%); based on the total mass of the first monomer, the second monomer and the third monomer, the mass percentage of the cross-linking monomer is 0.5% to 3% .
  • the monomer content of the copolymer is within the above range, it is beneficial to improve the dispersion and cohesion of the binder.
  • the emulsifier includes anhydrous xylitol monooleate, sorbitan monooleate, dichloride-N,N'-di(3-rosinyloxy -At least one of -2-hydroxypropyl)tetrahydroxyethylisohydroxypropylenediamine, alkoxylated alcohol or fatty acid polyol ester. Select an emulsifier within the above range.
  • the polar groups (such as hydroxyl and cyano groups) in the emulsifier can provide strong adhesive force after film formation, and the emulsion particles have good dispersion, which can further improve the adhesive force. dispersion and adhesion.
  • the mass percentage of the emulsifier is 0.5% to 2% based on the total mass of the first monomer, the second monomer and the third monomer. .
  • the emulsifier content within the above range is beneficial to improving the dispersion and cohesion of the binder.
  • the binder meets at least one of the following characteristics 1) to 6): 1) the glass transition temperature of the binder is 10°C to 70°C; 2) The cross-linking degree of the binder is 10% to 80%; 3) the swelling degree of the binder in the electrolyte is 30% to 150%; 4) the binder is present in the negative electrode sheet Discrete distribution, the average diameter of each point in the discrete distribution is 100nm to 300nm; 5) the adhesive film tensile strength of the adhesive is 5MPa to 30MPa; 6) the adhesive film breaking elongation The length ratio is 50% to 300%.
  • the binder satisfies any one of the above characteristics 1) to 6), and its application in the negative electrode piece can improve the structural stability of the negative electrode piece, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • a second aspect of the present application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode active material layer includes a negative electrode active material and the present invention. Apply the adhesive provided by the first aspect.
  • the negative electrode sheet provided in this application contains the binder provided in the first aspect of this application and has good structural stability, thereby improving the cycle performance and expansion performance of the electrochemical device.
  • the mass percentage of the binder is 1% to 10% based on the mass of the negative active material layer.
  • the binder content within the above range is beneficial to improving the structural stability of the negative electrode piece.
  • the negative active material includes at least one of graphite, hard carbon, silicon, silicon carbon or silicon oxide.
  • the compacted density of the negative active material layer is 1.45g/cm 3 to 1.85g/cm 3 .
  • the compacted density of the negative active material layer is within the above range, which is beneficial to improving the structural stability of the negative electrode piece, thereby improving the cycle performance and expansion performance of the electrochemical device.
  • the negative electrode piece meets at least one of the following characteristics a) or b): a) the ionic resistance of the negative electrode piece is 4 m ⁇ to 20 m ⁇ ; b) the negative electrode activity
  • the bonding force of the material layer is 10N/m to 200N/m. The smaller the ionic resistance of the negative electrode piece, the greater the charging rate of the electrochemical device and the faster the charging rate.
  • the ionic resistance of the negative electrode piece provided by the present application is within the range of the above characteristic a), which is beneficial to improving the charging rate of the electrochemical device.
  • the adhesive force of the negative active material layer is within the range of the above characteristic b), which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • a third aspect of the application provides an electrochemical device, which includes the negative electrode plate provided in the second aspect of the application.
  • the negative electrode piece provided by this application has good structural stability, so that the electrochemical device provided by this application has good cycle performance and expansion performance.
  • a fourth aspect of the present application provides an electronic device, which includes the electrochemical device provided in the third aspect of the present application.
  • the electrochemical device provided by this application has good cycle performance and expansion performance, so the electronic device provided by this application has good cycle performance and expansion performance.
  • the present application provides a binder, a negative electrode sheet, an electrochemical device and an electronic device.
  • the binder includes a copolymer.
  • the copolymer is obtained by copolymerizing the following mixture.
  • the mixture includes the first monomer butadiene. , the second monomer styrene, the third monomer, the cross-linking monomer and the emulsifier;
  • the third monomer includes at least one of (meth)acrylate, acrylonitrile, acrylic acid and its derivatives
  • the The cross-linking monomer includes at least one of triethylene glycol diacrylate, N,N-methylene bisacrylamide, ethylene glycol diacrylate or ethylene glycol diacrylate.
  • Figure 1 is a scanning electron microscope (SEM) photo of the distribution of traditional SBR binder on the surface of graphite;
  • Figure 2 is an SEM photograph of the distribution of the binder prepared in Example 1-1 of the present application on the surface of graphite.
  • a lithium ion battery is used as an example of an electrochemical device to explain the present application, but the electrochemical device of the present application is not limited to lithium ion batteries.
  • SBR emulsion binder
  • a first aspect of the present application provides a binder, including a copolymer, wherein the copolymer is obtained by copolymerizing a mixture including a first monomer butadiene, a second monomer styrene, a third Three monomers, cross-linking monomers and emulsifiers; the third monomer includes at least one of (meth)acrylate, acrylonitrile, acrylic acid and its derivatives, and the cross-linking monomer includes triethylene glycol diacrylate , at least one of N,N-methylene bisacrylamide, ethylene glycol diacrylate or ethylene glycol diacrylate.
  • the first monomer and the second monomer serve as the main structure of the binder.
  • the first monomer provides the binder with high toughness
  • the second monomer provides the binder with high strength and high glass transition temperature (Tg).
  • Tg glass transition temperature
  • the third monomer provides hydrophilicity to the binder, improves the dispersion of the binder emulsion particles, and is conducive to discrete distribution and film formation
  • the cross-linking monomer provides a cross-linked structure, which can increase the Tg of the binder and reduce the molecular chain Migrate to form a film
  • emulsifier provides high adhesion.
  • the binder provided by this application is discretely distributed when forming a film on the surface of the negative active material, is evenly dispersed, and has high adhesion. Its application in the negative electrode piece can improve the structural stability of the negative electrode piece, thereby improving the electrochemical device. cycle performance and expansion performance.
  • the mass ratio of the first monomer, the second monomer and the third monomer is (15% to 35%): (60% to 85%): (0% to 15% ); based on the total mass of the first monomer, the second monomer and the third monomer, the mass percentage of the cross-linking monomer is 0.5% to 3%.
  • the monomer content of the copolymer is within the above range, it is beneficial to improve the dispersion and cohesion of the binder.
  • the emulsifier includes anhydrous xylitol monooleate (M-201), sorbitan monooleate (Span-80), dichloride-N,N′- At least one of bis(3-abienoyloxy-2-hydroxypropyl)tetrahydroxyethylisohydroxypropylenediamine, alkoxylated alcohol or fatty acid polyol ester.
  • M-201 anhydrous xylitol monooleate
  • Span-80 sorbitan monooleate
  • alkoxylated alcohols include but are not limited to diethylene glycol, dipropylene glycol, glycerol, pentaerythritol or sorbitol, etc.
  • fatty acid polyol esters refer to alcohols with a hydroxyl number of ⁇ 3 (such as glycerol, polyglycerol, Esters produced from substances such as sorbitol, sorbitan anhydride) and sucrose and fatty acids, including but not limited to trimethylolpropane trifatty acid ester or pentaerythritol tetrafatty acid ester.
  • polar groups such as hydroxyl and cyano groups
  • the polar groups (such as hydroxyl and cyano groups) in the emulsifier can provide strong adhesive force after film formation, and the emulsion particles have good dispersion, which can further improve the adhesive force. dispersion and dynamics.
  • the mass percentage of the emulsifier is 0.5% to 2% based on the total mass of the first monomer, the second monomer and the third monomer.
  • the emulsifier content within the above range is beneficial to improving the dispersion and cohesion of the binder.
  • the mixture may also include an initiator, which is an emulsion polymerization initiator.
  • an initiator which is an emulsion polymerization initiator.
  • ammonium persulfate is used as initiator.
  • the reaction of mixture copolymerization is emulsion polymerization.
  • This application has no special restrictions on the reaction process. Those skilled in the art can choose according to the actual situation, as long as the purpose of this application can be achieved.
  • the emulsion polymerization reactants can be mixed and reacted under conditions of 40°C to 90°C and 0.6MPa to 1.0MPa for 3 hours to 10 hours. After the reaction stops, alkali is added to adjust the pH of the reaction solution to 7 -8 and then filter to obtain the binder.
  • the binder satisfies at least one of the following characteristics 1) to 6): 1) the glass transition temperature of the binder is 10°C to 70°C; 2) the binder has The degree of cross-linking is 10% to 80%; 3) The swelling degree of the binder in the electrolyte is 30% to 150%; 4) The binder is discretely distributed in the negative electrode piece, and every point in the discrete distribution The average diameter is 100nm to 300nm; 5) The adhesive film tensile strength is 5MPa to 30MPa; 6) The adhesive film elongation at break is 50% to 300%.
  • the binder satisfies any one of the above characteristics 1) to 6), and its application in the negative electrode piece can improve the structural stability of the negative electrode piece, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • discrete distribution means that the emulsion colloidal particles of the binder on the negative active material particles can be dispersed and distributed in the form of single particle points or in the form of small-sized clusters.
  • the diameter of single particle points is 100nm-250nm
  • the average diameter of small-sized clusters is 250nm-300nm, as shown in Figure 2, where the dark parts are binder particles.
  • the viscosity range of the binder is from 10 mPa ⁇ s to 1000 mPa ⁇ s.
  • the viscosity range of the binder is within the above range, and its application in the negative electrode piece can improve the structural stability of the negative electrode piece, thereby improving the cycle performance and expansion performance of the electrochemical device.
  • the second aspect of the application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector.
  • the negative electrode active material layer includes the negative electrode active material and the first aspect of the application. Adhesive provided.
  • the negative electrode sheet provided in this application contains the binder provided in the first aspect of this application and has good structural stability, thereby improving the cycle performance and expansion performance of the electrochemical device.
  • the mass percentage of the binder is 1% to 10% based on the mass of the negative active material layer.
  • the binder content within the above range is beneficial to improving the structural stability of the negative electrode piece.
  • the negative active material includes at least one of graphite, hard carbon, silicon, silicon carbon or silicon oxide.
  • This application has no particular limitation on the average particle size of the negative active material, as long as the purpose of this application can be achieved.
  • the average particle size of the negative active material is 5 ⁇ m to 20 ⁇ m.
  • the compacted density of the negative active material layer is 1.45g/cm 3 to 1.85g/cm 3 .
  • the compacted density of the negative active material layer is within the above range, which is beneficial to improving the structural stability of the negative electrode piece, thereby improving the cycle performance and expansion performance of the electrochemical device.
  • the negative electrode sheet meets at least one of the following characteristics a) or b): a) the ionic resistance of the negative electrode sheet is 4 m ⁇ to 20 m ⁇ ; b) the adhesion force of the negative electrode active material layer 10N/m to 200N/m.
  • the ionic resistance of the negative electrode piece provided by the present application is within the range of the above characteristic a), which is beneficial to improving the charging rate of the electrochemical device.
  • the adhesive force of the negative active material layer is within the range of the above characteristic b), which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • a third aspect of the application provides an electrochemical device, which includes the negative electrode plate provided in the second aspect of the application.
  • the negative electrode piece provided by this application has good structural stability, so that the electrochemical device provided by this application has good cycle performance and expansion performance.
  • the electrochemical device of the present application is not particularly limited and may include any device that undergoes electrochemical reactions.
  • the electrochemical devices of the present application include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries (lithium ion batteries), lithium polymer secondary batteries or lithium ion polymer secondary batteries. Batteries etc.
  • the lithium ion battery structure of the present application includes, but is not limited to: wound structure, laminate structure or multi-lub structure, etc.
  • the lithium-ion battery structure of this application includes but is not limited to: soft-pack lithium-ion battery, square aluminum shell battery or cylindrical aluminum shell battery, etc.
  • the negative electrode current collector may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam or composite current collector.
  • This application has no special restrictions on the thickness of the negative electrode current collector, as long as the purpose of this application can be achieved.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 10 ⁇ m.
  • the negative active material layer may be disposed on one surface in the thickness direction of the negative electrode current collector, or may be disposed on both surfaces in the thickness direction of the negative electrode current collector.
  • the "surface” here can be the entire area of the negative electrode current collector, or it can be a partial area of the negative electrode current collector. There is no particular limitation in this application, as long as the purpose of this application can be achieved.
  • the positive electrode current collector may include aluminum foil, aluminum alloy foil, composite current collector, etc.
  • This application has no special restrictions on the thickness of the positive electrode current collector and the positive electrode active material layer, as long as the purpose of this application can be achieved.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m.
  • the cathode active material layer of the present application may include a cathode active material.
  • This application has no particular limitation on the type of positive electrode active material, as long as it can achieve the purpose of this application.
  • the positive electrode active material may include at least one of lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganate, lithium iron manganese phosphate, or lithium titanate. kind.
  • the positive active material layer may also include a positive electrode binder.
  • This application has no special restrictions on the positive electrode binder, as long as it can achieve the purpose of this application.
  • it may include but is not limited to polyvinylidene fluoride, polyvinylidene fluoride, polyvinylidene fluoride, Vinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyethylene, polypropylene, butyl At least one of styrene rubber, acrylic (ester) styrene-butadiene rubber or epoxy resin.
  • the cathode active material layer may be disposed on one surface in the thickness direction of the cathode current collector, or may be disposed on both surfaces in the thickness direction of the cathode current collector.
  • the "surface” here can be the entire area of the positive electrode current collector, or it can be a partial area of the positive electrode current collector. There is no particular limitation in this application, as long as the purpose of this application can be achieved.
  • a fourth aspect of the present application provides an electronic device, which includes the electrochemical device provided in the third aspect of the present application.
  • the electrochemical device provided by this application has good cycle performance and expansion performance, so the electronic device provided by this application has good cycle performance and expansion performance.
  • electronic devices may include, but are not limited to, laptop computers, pen computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headsets, video recorders, LCD TV, portable cleaner, portable CD player, mini CD, transceiver, electronic notepad, calculator, memory card, portable recorder, radio, backup power supply, motor, automobile, motorcycle, power-assisted bicycle, bicycle, lighting equipment , toys, game consoles, clocks, power tools, flashlights, cameras, large household batteries or lithium-ion capacitors, etc.
  • the glass transition temperature (Tg) of the binder was tested by differential scanning calorimetry (DSC). Take a 5 mg binder sample and heat it from -20°C to 150°C at a heating rate of 5°C/min. Analyze and measure the The DSC curve determines the Tg of the binder.
  • the emulsion colloidal particles are dispersed in the form of single particle points or in the form of small-sized clusters (the average diameter of each point is 100nm). -300nm), its film-forming characteristics are discrete distribution, recorded as discrete; emulsion colloidal particles agglomerate into cluster-like distribution, and the cluster size is >300nm, its film-forming characteristics are recorded as clusters. In addition, the diameters of 20 particle points were counted, the average diameter was calculated, and recorded as the film-forming particle point diameter.
  • the average particle size (D50) of the binder emulsion was tested by a laser particle size analyzer.
  • Test steps Fix the initial distance L 0 between the upper and lower clamps, which is the initial length L 0 of the sample.
  • the upper clamp is stretched at a constant rate of 50mm/min until the sample breaks. Record the maximum load F when the sample breaks.
  • the test frequency range is 30mHz to 500kHz, the amplitude is 5mV, and the Nyquist spectrum is obtained from the test.
  • the curve of the spectrum is a semicircle, and the impedance value corresponding to its diameter is the ionic impedance of the negative electrode of the battery.
  • the capacity is the initial capacity
  • the initial thickness of the lithium-ion battery is recorded as the initial thickness.
  • the capacity retention rate (cycling capacity - initial capacity) / initial capacity ⁇ 100%
  • the cyclic expansion rate (expansion thickness - initial thickness) / initial thickness ⁇ 100%.
  • the negative active material graphite, silicon, conductive carbon black, and the binder prepared in this example were mixed according to a mass ratio of 92:4:2:2, and then deionized water was added as a solvent to prepare a solid content of 70wt%. of negative electrode slurry and stir evenly.
  • the negative electrode slurry is evenly coated on one surface of the negative electrode current collector copper foil with a thickness of 10 ⁇ m, and dried at 110°C to obtain a negative electrode sheet with a coating thickness of 150 ⁇ m coated with a negative electrode active material layer on one side, and then Repeat the above steps on the other surface of the negative electrode piece to obtain a negative electrode piece coated with a negative electrode active material layer on both sides.
  • the negative electrode sheet is cold-pressed and cut into sheets with specifications of 78mm ⁇ 875mm for use.
  • the compacted density of the negative electrode piece is 1.7g/cm 3 .
  • the above steps are repeated on the other surface of the positive electrode piece, thereby obtaining a positive electrode piece coated with the positive electrode active material on both sides.
  • the positive electrode sheet is cold-pressed and cut into sheets with specifications of 74mm ⁇ 867mm for use.
  • the compacted density of the positive electrode piece is 4.15g/cm 3 .
  • LiPF 6 lithium salt lithium hexafluorophosphate
  • a polyethylene film with a thickness of 15 ⁇ m (provided by Celgard) was used.
  • the positive electrode piece, separator, and negative electrode piece prepared above are stacked in order so that the separator is between the positive electrode piece and the negative electrode piece to play an isolation role, and then the electrode assembly is obtained by winding.
  • the electrode assembly is obtained by winding.
  • put the electrode assembly into the aluminum plastic film packaging shell place it in a vacuum oven at 85°C to dry for 12 hours to remove the moisture, inject the electrolyte prepared above, vacuum seal, let it stand, and form (0.02C constant Current charging to 3.5V, then 0.1C constant current charging to 3.9V), shaping, capacity testing and other processes to obtain a lithium-ion battery.
  • Example 1-1 Except for adjusting the binder composition according to Table 1, the rest is the same as Example 1-1.
  • Example 1-1 Except for adjusting parameters according to Table 2, the rest is the same as in Example 1-1.
  • Example 1-1 Except for adjusting the parameters according to Table 1, the rest is the same as in Example 1-1.
  • Figure 2 is an SEM photo of the distribution of the binder prepared in Example 1-1 of the present application on the surface of graphite. It can be seen from Figure 2 that the binder provided by this application is discretely distributed in the form of single particles and small-sized clusters when forming a film on the graphite surface, and is evenly dispersed.
  • Example 1-1 to Example 1-3 From Example 1-1 to Example 1-3, it can be seen that as the first monomer content increases and the second monomer content decreases, the elongation at break and swelling degree increase significantly, and Tg and tensile strength decrease, that is, The first monomer provides high toughness to the binder, and the second monomer provides high strength and high Tg to the binder.
  • the content of the third monomer acrylic acid or acrylonitrile increases, the binding force of the negative active material layer increases, and as the acrylic acid content increases, it is also beneficial to reduce the ion The resistance improves the dispersion of the emulsion and facilitates the discrete distribution of the adhesive during film formation.
  • the obtained binder is discretely distributed and evenly dispersed when forming a film on the graphite surface, thereby improving the The bonding force of the negative active material layer enables the resulting lithium-ion battery to have good cycle performance and expansion performance.
  • Comparative Examples 1-1 and 1-2 the cross-linking degree of the adhesive without cross-linking monomer is 0, and there is no cross-linking monomer to provide a cross-linked structure. Comparative Examples 1-1 and 1
  • the binding force of the negative active material layer of the negative electrode sheet prepared in -2 is lower than that of the binder provided in the embodiment of the present application, which is not conducive to the structural stability of the negative electrode sheet, and thus cannot improve the cycle performance and expansion performance of the lithium-ion battery.
  • Cross-linking monomers provide a cross-linked structure, increase Tg, and reduce the migration of molecular chains to form films. It can be seen from Example 1-1, Example 1-8 to Example 1-10 that the cross-linking monomer content is within the scope of the present application, and the obtained binder is discretely distributed when forming a film on the graphite surface, which improves the The bonding force of the negative active material layer results in a lithium-ion battery with better cycle performance and expansion performance.
  • Example 1-1 Example 1-11 to Example 1-12 that as the emulsifier content increases, the diameter of the binder film-forming particle points decreases, which is conducive to discrete distribution of film formation, thereby improving the performance of the negative electrode.
  • the adhesion of the active material layer The emulsifier content is within the scope of the present application, and the prepared binder can improve the bonding force of the negative active material layer, thereby improving the cycle performance and expansion performance of the lithium-ion battery.
  • the diameter of the binder film-forming particles is small, and the surface coverage area of the active material is small.
  • the ionic resistance of the negative electrode sheet obtained is also small, and at the same time, the rapid performance of the lithium-ion battery can be improved. Charging performance.
  • the added emulsifier is sodium dodecyl sulfonate, which is not within the range of emulsifiers provided in this application.
  • the film-forming particle point diameters are both greater than 300nm and distributed in clusters. .
  • the binders prepared in Examples 1-2 and 1-3 are applied to the negative electrode piece.
  • the ionic resistance of the negative electrode piece is higher than that of the embodiment of the present application, and the bonding force of the negative active material layer is much lower than that of the embodiment of the present application. For example, the fast charging performance, cycle performance and expansion performance of lithium-ion batteries cannot be improved.
  • Example 1-1 Example 2-1 to Example 2-2 that in the negative electrode piece, the binder content is within the scope of the present application, which can effectively improve the structural stability of the negative electrode piece, thereby improving Cycling performance and swell performance of lithium-ion batteries.
  • Example 1-1 Example 2-3 to Example 2-4 that in the negative electrode sheet, the compaction density of the negative active material layer is within the scope of this application, and the binder provided by this application can effectively Improve the structural stability of the negative electrode plate, thereby improving the cycle performance and expansion performance of lithium-ion batteries.
  • Applying the binder provided by this application to the negative electrode sheet can improve the structural stability of the negative electrode sheet, thereby increasing the charging rate of the lithium-ion battery and extending the cycle life.
  • the lithium-ion battery provided by this application is cycled 800 times at 25°C, the cycle expansion rate is ⁇ 10%, and the capacity retention rate is both >90%, which effectively improves the cycle performance and expansion performance of the lithium-ion battery.

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Abstract

本申请提供一种粘结剂、负极极片、电化学装置及电子装置，粘结剂包括共聚物，共聚物通过以下混合物共聚获得，混合物包括第一单体丁二烯、第二单体苯乙烯、第三单体、交联单体和乳化剂；第三单体包括(甲基)丙烯酸酯、丙烯腈、丙烯酸及其衍生物中的至少一种，交联单体包括三乙二醇二丙烯酸酯、N,N-亚甲基双丙烯酰胺、二丙烯酸乙二醇酯或乙二醇二丙烯酸酯中的至少一种。将本申请提供的粘结剂，应用于负极极片中能够提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。

Description

一种粘结剂、负极极片、电化学装置及电子装置 技术领域
本申请涉及电化学技术领域，具体涉及一种粘结剂、负极极片、电化学装置及电子装置。
背景技术
锂离子电池(电化学装置)具有体积和质量能量密度大、循环寿命长、标称电压高、自放电率低、体积小、重量轻等许多优点，在消费电子领域具有广泛的应用。随着近年来电动汽车和可移动电子设备的高速发展，人们对锂离子电池的安全性能、循环性能等相关需求越来越高，期待着综合性能全面提升的新型锂离子电池的出现。
通常采用涂布法制备锂离子电池的负极极片上的负极活性物质层，成膜过程中，负极活性物质层中的粘结剂存在动力学差、成膜分布不均匀(在负极活性物质颗粒表面成膜时容易团聚，成团簇状分布)的缺点，不利于锂离子电池的循环性能和膨胀性能。
发明内容
本申请的目的在于提供一种粘结剂、负极极片、电化学装置及电子装置，以改善电化学装置的循环性能和膨胀性能。具体技术方案如下：
本申请的第一方面提供了一种粘结剂，包括共聚物，其中，所述共聚物通过以下混合物共聚获得，所述混合物包括第一单体丁二烯、第二单体苯乙烯、第三单体、交联单体和乳化剂；所述第三单体包括(甲基)丙烯酸酯、丙烯腈、丙烯酸及其衍生物中的至少一种，所述交联单体包括三乙二醇二丙烯酸酯、N,N-亚甲基双丙烯酰胺、二丙烯酸乙二醇酯或乙二醇二丙烯酸酯中的至少一种。第一单体和第二单体作为粘结剂的主体结构，第一单体为粘结剂提供高韧性，第二单体为粘结剂提供高强度和高玻璃化转变温度(Tg)，第三单体为粘结剂提供亲水性，改善粘结剂乳液颗粒的分散性，有利于在负极活性物质表面离散分布成膜；交联单体提供交联结构，可以提高粘结剂的Tg，减少分子链的迁移成膜；乳化剂提供高粘结力。本申请提供的粘结剂在负极活性物质表面成膜时呈离散分布，分散均匀，粘结力高，将其应用于负极极片中能够提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，所述第一单体、所述第二单体和所述第三单体的质量比为(15％至35％):(60％至85％):(0％至15％)；基于所述第一单体、所述第二单体和所述第三 单体的总质量，所述交联单体的质量百分含量为0.5％至3％。制备共聚物的单体含量在上述范围内，均有利于提高粘结剂的分散性和粘结力。
在本申请的一种实施方案中，所述乳化剂包括失水木糖醇单油酸酯、山梨糖醇酐单油酸酯、二氯化-N,N′-二(3-松香酰氧基-2-羟丙基)四羟乙基异羟基丙二胺、烷氧基化醇或脂肪酸多元醇酯中的至少一种。选择上述范围内的乳化剂，乳化剂中的极性基团(如羟基和氰基)，在成膜后可以提供强的粘结力，并且乳液胶粒分散性好，可以进一步提高粘结剂的分散性和粘结力。
在本申请的一种实施方案中，基于所述第一单体、所述第二单体和所述第三单体的总质量，所述乳化剂的质量百分含量为0.5％至2％。乳化剂含量在上述范围内，均有利于提高粘结剂的分散性和粘结力。
在本申请的一种实施方案中，所述粘结剂满足以下特征1)至6)中的至少一者：1)所述粘结剂的玻璃化转变温度为10℃至70℃；2)所述粘结剂的交联度为10％至80％；3)所述粘结剂在电解液中的溶胀度为30％至150％；4)所述粘结剂在负极极片中呈离散分布，所述离散分布中的每一个点的平均直径为100nm至300nm；5)所述粘结剂的胶膜拉伸强度为5MPa至30MPa；6)所述粘结剂的胶膜断裂伸长率为50％至300％。粘结剂满足上述特征1)至6)中的任一者，将其应用于负极极片中能够提高负极极片的结构稳定性，均有利于改善电化学装置的循环性能和膨胀性能。
本申请的第二方面提供了一种负极极片，其包括负极集流体以及设置于所述负极集流体的至少一个表面上的负极活性物质层，所述负极活性物质层包括负极活性物质和本申请第一方面提供的粘结剂。本申请提供的负极极片包含本申请第一方面提供的粘结剂，具有良好的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，基于所述负极活性物质层的质量，所述粘结剂的质量百分含量为1％至10％。粘结剂含量在上述范围内，均有利于提高负极极片的结构稳定性。
在本申请的一种实施方案中，所述负极活性物质包括石墨、硬碳、硅、硅碳或氧化亚硅中的至少一种。通过选择上述负极活性物质，得到的负极极片具有良好的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，所述负极活性物质层的压实密度为1.45g/cm 3至1.85g/cm 3。负极活性物质层的压实密度在上述范围内，有利于提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，所述负极极片满足以下特征a)或b)中的至少一者：a)所述负极极片的离子电阻为4mΩ至20mΩ；b)所述负极活性物质层的粘结力为10N/m至200N/m。负极极片的离子电阻越小，电化学装置的充电倍率越大，充电速率越快，本申请提供的负极极片的离子电阻在上述特征a)范围内，有利于提高电化学装置的充电速率。负极活性物质层的粘结力在上述特征b)范围内，有利于改善电化学装置的循环性能和膨胀性能。
本申请的第三方面提供了一种电化学装置，其包括本申请第二方面提供的负极极片。本申请提供的负极极片具有良好的结构稳定性，从而本申请提供的电化学装置具有良好的循环性能和膨胀性能。
本申请的第四方面提供了一种电子装置，其包括本申请第三方面提供的电化学装置。本申请提供的电化学装置具有良好的循环性能和膨胀性能，从而本申请提供的电子装置具有良好的循环性能和膨胀性能。
本申请提供一种粘结剂、负极极片、电化学装置及电子装置，所述粘结剂包括共聚物，所述共聚物通过以下混合物共聚获得，所述混合物包括第一单体丁二烯、第二单体苯乙烯、第三单体、交联单体和乳化剂；所述第三单体包括(甲基)丙烯酸酯、丙烯腈、丙烯酸及其衍生物中的至少一种，所述交联单体包括三乙二醇二丙烯酸酯、N,N-亚甲基双丙烯酰胺、二丙烯酸乙二醇酯或乙二醇二丙烯酸酯中的至少一种。将本申请提供的粘结剂，应用于负极极片中能够提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
附图说明
为了更清楚地说明本申请实施例和现有技术的技术方案，下面对实施例和现有技术中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，本领域普通技术人员来讲还可以根据这些附图获得其他的附图。
图1为传统SBR粘结剂在石墨表面分布的扫描电镜(SEM)照片；
图2为本申请的实施例1-1制备的粘结剂在石墨表面分布的SEM照片。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图和实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员所获得的所有其他技术方案，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为电化学装置的例子来解释本申请，但是本申请的电化学装置并不仅限于锂离子电池。
目前负极极片中使用最多的乳液粘结剂(SBR)存在动力学差、成膜分散不均匀(成膜时容易团聚，成团簇状分布)的缺点，传统SBR粘结剂在石墨表面分布的SEM照片如图1所示。
有鉴于此，本申请的第一方面提供了一种粘结剂，包括共聚物，其中，共聚物通过以下混合物共聚获得，混合物包括第一单体丁二烯、第二单体苯乙烯、第三单体、交联单体和乳化剂；第三单体包括(甲基)丙烯酸酯、丙烯腈、丙烯酸及其衍生物中的至少一种，交联单体包括三乙二醇二丙烯酸酯、N,N-亚甲基双丙烯酰胺、二丙烯酸乙二醇酯或乙二醇二丙烯酸酯中的至少一种。第一单体和第二单体作为粘结剂的主体结构，第一单体为粘结剂提供高韧性，第二单体为粘结剂提供高强度和高玻璃化转变温度(Tg)，第三单体为粘结剂提供亲水性，改善粘结剂乳液颗粒的分散性，有利于离散分布成膜；交联单体提供交联结构，可以提高粘结剂的Tg，减少分子链的迁移成膜；乳化剂提供高粘结力。本申请提供的粘结剂在负极活性物质表面成膜时呈离散分布，分散均匀，粘结力高，将其应用于负极极片中能够提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，第一单体、第二单体和第三单体的质量比为(15％至35％):(60％至85％):(0％至15％)；基于第一单体、第二单体和第三单体的总质量，交联单体的质量百分含量为0.5％至3％。制备共聚物的单体含量在上述范围内，均有利于提高粘结剂的分散性和粘结力。
在本申请的一种实施方案中，乳化剂包括失水木糖醇单油酸酯(M-201)、山梨糖醇酐单油酸酯(Span-80)、二氯化-N,N′-二(3-松香酰氧基-2-羟丙基)四羟乙基异羟基丙二胺、烷氧基化醇或脂肪酸多元醇酯中的至少一种。本申请中，烷氧基化醇包括但不限于二乙二醇、二丙二醇、甘油、季戊四醇或山梨糖醇等，脂肪酸多元醇酯是指羟基数≥3的醇类(如甘油、聚甘油、山梨醇、失水山梨醇)和蔗糖等物质与脂肪酸生成的酯类，包括但不限于三羟甲基丙烷三脂脂肪酸酯或季戊四醇四脂肪酸酯等。选择上述范围内的乳化剂，乳化剂中的极性基团(如羟基和氰基)，在成膜后可以提供强的粘结力，并且乳液胶粒分散性好，可以进一步提高粘结剂的分散性和动力学。
在本申请的一种实施方案中，基于第一单体、第二单体和第三单体的总质量，乳化剂的质量百分含量为0.5％至2％。乳化剂含量在上述范围内，均有利于提高粘结剂的分散性 和粘结力。
在本申请中，混合物还可以包括引发剂，引发剂为乳液聚合引发剂，本领域技术人员可以根据实际需要进行选择，只要能实现本申请的目的即可。示例性地，采用过硫酸铵作为引发剂。
在本申请中，混合物共聚的反应为乳液聚合反应，本申请对反应过程没有特别限制，本领域技术人员可以根据实际情况选择，只要能实现本申请的目的即可。示例性地，可采用将乳液聚合的反应物混合后在40℃至90℃、0.6MPa至1.0MPa条件下，反应3小时至10小时，反应停止后，加碱将反应液的pH调节至7-8后过滤得到粘结剂。
在本申请的一种实施方案中，粘结剂满足以下特征1)至6)中的至少一者：1)粘结剂的玻璃化转变温度为10℃至70℃；2)粘结剂的交联度为10％至80％；3)粘结剂在电解液中的溶胀度为30％至150％；4)粘结剂在负极极片中呈离散分布，离散分布中的每一个点的平均直径为100nm至300nm；5)粘结剂的胶膜拉伸强度为5MPa至30MPa；6)粘结剂的胶膜断裂伸长率为50％至300％。粘结剂满足上述特征1)至6)中的任一者，将其应用于负极极片中能够提高负极极片的结构稳定性，均有利于改善电化学装置的循环性能和膨胀性能。
本申请中，离散分布是指粘结剂在负极活性物质颗粒上乳液胶粒可以以单颗粒点形式分散分布，还可以以小尺寸的团簇体形式分散分布。离散分布中，单颗粒点的直径为100nm-250nm，小尺寸团簇体的团簇平均直径为250nm-300nm，如图2所示，其中深色的部分为粘结剂颗粒。
本申请中，粘结剂的粘度范围为10mPa·s至1000mPa·s。粘结剂的粘度范围在上述范围内，将其应用于负极极片中能够提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
本申请的第二方面提供了一种负极极片，其包括负极集流体以及设置于负极集流体的至少一个表面上的负极活性物质层，负极活性物质层包括负极活性物质和本申请第一方面提供的粘结剂。本申请提供的负极极片包含本申请第一方面提供的粘结剂，具有良好的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，基于负极活性物质层的质量，粘结剂的质量百分含量为1％至10％。粘结剂含量在上述范围内，均有利于提高负极极片的结构稳定性。
在本申请的一种实施方案中，负极活性物质包括石墨、硬碳、硅、硅碳或氧化亚硅中 的至少一种。通过选择上述负极活性物质，得到的负极极片具有良好的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
本申请对负极活性物质的平均粒径没有特别限制，只要能实现本申请的目的即可。示例性地，负极活性物质的平均粒径为5μm至20μm。
在本申请的一种实施方案中，负极活性物质层的压实密度为1.45g/cm 3至1.85g/cm 3。负极活性物质层的压实密度在上述范围内，有利于提高负极极片的结构稳定性，从而改善电化学装置的循环性能和膨胀性能。
在本申请的一种实施方案中，负极极片满足以下特征a)或b)中的至少一者：a)负极极片的离子电阻为4mΩ至20mΩ；b)负极活性物质层的粘结力为10N/m至200N/m。负极极片的离子电阻越小，电化学装置的充电倍率越大，充电速率越快，本申请提供的负极极片的离子电阻在上述特征a)范围内，有利于提高电化学装置的充电速率。负极活性物质层的粘结力在上述特征b)范围内，有利于改善电化学装置的循环性能和膨胀性能。
本申请的第三方面提供了一种电化学装置，其包括本申请第二方面提供的负极极片。本申请提供的负极极片具有良好的结构稳定性，从而本申请提供的电化学装置具有良好的循环性能和膨胀性能。
本申请的电化学装置没有特别限制，其可以包括发生电化学反应的任何装置。在本申请的一些实施方案中，本申请的电化学装置包括但不限于：锂金属二次电池、锂离子二次电池(锂离子电池)、锂聚合物二次电池或锂离子聚合物二次电池等。在本申请的一些实施方案中，本申请的锂离子电池结构包括但不限于：卷绕型结构、叠片结构或多极耳结构等。本申请的锂离子电池结构包括但不限于：软包型锂离子电池、方形铝壳电池或圆柱形铝壳电池等。
本申请对负极集流体没有特别限制，只要能够实现本申请目的即可。例如，负极集流体可以包含铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体等。本申请对负极集流体的厚度没有特别限制，只要能够实现本申请目的即可。例如，负极集流体的厚度为4μm至10μm。
在本申请中，负极活性物质层可以设置于负极集流体厚度方向上的一个表面上，也可以设置于负极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体的全部区域，也可以是负极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请对正极集流体没有特别限制，只要能够实现本申请目的即可。例如，正极集流体可以包含铝箔、铝合金箔或复合集流体等。本申请对正极集流体和正极活性物质层的厚度没有特别限制，只要能够实现本申请目的即可。例如，正极集流体的厚度为5μm至20μm。
本申请的正极活性物质层可以包括正极活性物质。本申请对正极活性物质的种类没有特别限制，只要能够实现本申请目的即可。例如，正极活性物质可以包含镍钴锰酸锂、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂、锰酸锂、磷酸锰铁锂或钛酸锂等中的至少一种。
在本申请中，正极活性物质层还可以包括正极粘结剂，本申请对正极粘结剂没有特别限制，只要能够实现本申请目的即可，例如可以包括但不限于聚偏二氟乙烯、聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶或环氧树脂中的至少一种。
在本申请中，正极活性物质层可以设置于正极集流体厚度方向上的一个表面上，也可以设置于正极集流体厚度方向上的两个表面上。需要说明，这里的“表面”可以是正极集流体的全部区域，也可以是正极集流体的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请对隔膜和电解液没有特别限制，本领域技术人员可以根据实际情况进行选择，只要能够实现本申请目的即可。
本申请的第四方面提供了一种电子装置，其包括本申请第三方面提供的电化学装置。本申请提供的电化学装置具有良好的循环性能和膨胀性能，从而本申请提供的电子装置具有良好的循环性能和膨胀性能。
本申请的电子装置没有特别限定，其可以是用于现有技术中已知的任何电子装置。在一些实施例中，电子装置可以包括但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池或锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
玻璃化转变温度测试：
通过差示扫描量热法(DSC)测试粘结剂的玻璃化转变温度(Tg)，取5mg粘结剂样品，以5℃/min的升温速率从-20℃升温至150℃，分析测得的DSC曲线确定粘结剂的Tg。
交联度测试：
采用浸泡溶解法测试粘结剂胶膜的交联度，取1g粘结剂胶膜样品，在丙酮或四氯化碳溶剂中浸泡7天(d)，然后取出样品，烘干称重，浸泡后的样品的质量(w 1)，根据浸泡前后端额重量变化计算交联度，则交联度＝w 1×100％。
溶胀度的测试：
将粘结剂胶膜裁切为10mm×20mm的样品，称量浸泡前样品的质量(w 0)，然后在60℃下将样品浸泡在电解液中48小时(h)，擦干样品表面的溶剂，称量溶胀后样品的质量(w 2)，测试时每个样品称量三次，则溶胀度＝(w 2-w 0)/w 0×100％。
其中，电解液的有机溶剂为碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸二乙酯(DEC)、丙酸乙酯(EP)，且质量比EC:PC:DEC:EP＝3:1:3:3，溶质为六氟磷酸锂(LiPF 6)，LiPF 6的浓度为1mol/L。
粘结剂在石墨/硅颗粒表面分布测试：
通过SEM观察负极极片中石墨/硅颗粒表面的粘结剂状态，其中，乳液胶粒以单颗粒点形式分散分布或者以小尺寸的团簇体形式分散分布(每一个点的平均直径为100nm-300nm)，其成膜特点为离散分布，记为离散；乳液胶粒团聚成团簇状分布，且团簇体尺寸＞300nm，其成膜特点记为团簇。另外，统计20个颗粒点的直径，计算平均直径，记为成膜颗粒点直径。
粒径测试：
通过激光粒度仪测试粘结剂乳液的平均粒径(D50)。
拉伸强度和断裂伸长率测试：
通过万能试验机测试粘结剂的胶膜的拉伸强度和断裂伸长率。制备15mm宽、0.3mm厚的胶膜(120℃烘干成膜)，进行拉伸模式测试。
测试步骤：固定上下夹具初始间距L 0，即为样品初始长度L 0，上夹具以恒定速率 50mm/min拉伸至样品断裂，记录样品断裂时的最大载荷F，断裂时上下夹具间距为L 1，则：拉伸强度＝F/(15×0.3)，断裂伸长率＝(L 1-L 0)/L 0×100％。
离子电阻测试：
用负极极片制作对称电池，使用Bio-Logic VMP3电化学工作站测试电化学交流阻抗谱(EIS)。测试频率范围为30mHz至500kHz，振幅为5mV，测试得到Nyquist谱图。谱图的曲线为半圆形，其直径对应的阻抗值大小即电池负极极片的离子阻抗。
粘结力测试GB/T 2792-2014
将负极极片在60℃烘箱中放置15h烘干，裁切成1.5cm×110cm条状样品，将样品通过双面胶粘贴在3cm×15cm钢板上，用小棍辊压8次，将钢板固定在拉力机的下夹具中，上夹具夹住样品，以恒定速率50mm/min拉伸50mm，其中被拉起的样品部分与钢板在空间上夹角为180°，最终测得平稳区域的拉力平均值记为负极活性物质层的粘结力。
锂离子电池循环性能和膨胀性能的测试：
将锂离子电池置于25℃恒温环境中，以0.5C恒流充电到4.45V，再恒压充电至电流为0.025C，静置5分钟后以0.5C恒流放电到3V，以此步得到的容量为初始容量，并记录锂离子电池的初始厚度，记为初始厚度。再以0.5C充电/0.5C放电循环测试800次后，以0.5C充电后，记录循环后锂离子电池的循环容量和膨胀厚度，计算锂离子电池的循环容量保持率和循环膨胀率，并作为评价锂离子电池的循环性能和膨胀性能的指标。其中，容量保持率＝(循环容量－初始容量)/初始容量×100％，循环膨胀率＝(膨胀厚度－初始厚度)/初始厚度×100％。
实施例1-1
<粘结剂的制备>
将第一单体丁二烯、第二单体苯乙烯、交联单体三乙二醇二丙烯酸酯(TEGDA)、乳化剂失水木糖醇单油酸酯(M-201)按照质量比25:75:2:1混合，得到混合物，将所述混合物和引发剂过硫酸铵(基于所述混合物总质量的0.5％)加入与所述混合物等量的去离子水，得到乳液聚合反应的反应液，然后将反应液在70℃、0.8MPa条件下进行自由基乳液聚合，反应7小时后停止，然后加碱将反应液的pH调节至8，经过滤得到固含量为50wt％的粘结剂乳液，测得粘结剂乳液的平均粒径为270nm。
<负极极片的制备>
将负极活性物质石墨、硅、导电炭黑、本实施例中制备的粘结剂按照质量比为92:4:2:2 进行混合，然后加入去离子水作为溶剂，调配成固含量为70wt％的负极浆料，并搅拌均匀。将负极浆料均匀涂布在厚度为10μm的负极集流体铜箔的一个表面上，110℃条件下烘干，得到涂层厚度为150μm的单面涂布负极活性物质层的负极极片，然后在该负极极片的另一个表面上重复以上步骤，得到双面涂布有负极活性物质层的负极极片。涂布完成后，将负极极片冷压、裁切成规格为78mm×875mm的片材待用。负极极片的压实密度为1.7g/cm 3。
<正极极片的制备>
将正极活性物质钴酸锂(LiCoO 2)、导电剂导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照质量比97:1.4:1.6进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成固含量为75wt％的浆料，并搅拌均匀。将正极浆料均匀涂覆在厚度为10μm的正极集流体铝箔的一个表面上，110℃条件下烘干，得到正极活性物质层厚度为110μm的单面涂布正极活性物质的正极极片。之后，在该正极极片的另一个表面上重复以上步骤，即得到双面涂布正极活性物质的正极极片。涂布完成后，将正极极片冷压、裁切成规格为74mm×867mm的片材待用。正极极片的压实密度为4.15g/cm 3。
<电解液的制备>
在干燥氩气气氛手套箱中，将有机溶剂碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸二乙酯(DEC)和丙酸乙酯(EP)以质量比EC:PC:DEC:EP＝3:1:3:3混合，然后向有机溶剂中加入锂盐六氟磷酸锂(LiPF 6)溶解并混合均匀，得到锂盐的浓度为1mol/L的电解液。
<隔膜的制备>
采用厚度为15μm的聚乙烯薄膜(Celgard公司提供)。
<锂离子电池的制备>
将上述制备的正极极片、隔膜、负极极片按顺序叠好，使隔膜处于正极极片和负极极片中间起到隔离的作用，然后卷绕得到电极组件。焊接极耳后将电极组件装入铝塑膜包装壳中，放置在85℃真空烘箱中干燥12小时脱去水分，注入上述配好的电解液，经过真空封装、静置、化成(0.02C恒流充电至3.5V，再以0.1C恒流充电至3.9V)、整形、容量测试等工序得到锂离子电池。
实施例1-2至实施例1-12
除了按照表1调整粘结剂组成以外，其余与实施例1-1相同。
实施例2-1至实施例2-4
除了按照表2调整参数以外，其余与实施例1-1相同。
对比例1-1至对比例1-3
除了按照表1调整参数以外，其余与实施例1-1相同。
各实施例和对比例的相关制备参数及性能测试如表1至表2所示。
表1
Figure PCTCN2022083967-appb-000001
Figure PCTCN2022083967-appb-000002
表2
Figure PCTCN2022083967-appb-000003
图2是本申请实施例1-1制备的粘结剂在石墨表面分布的SEM照片。从图2可以看出，本申请提供的粘结剂在石墨表面成膜时呈单颗粒和小尺寸团簇状离散分布，分散均匀。
从实施例1-1至实施例1-3可得，随着第一单体含量增加、第二单体含量减小，断裂伸长率和溶胀度显著增加，Tg和拉伸强度降低，即第一单体为粘结剂提供了高韧性，第二单体为粘结剂提供了高强度和高Tg。实施例1-4至实施例1-7中，随着第三单体丙烯酸或丙烯腈含量的增加，负极活性物质层的粘结力增加，随着丙烯酸含量的增加，还有利于减小离子电阻，改善乳液的分散性，有利于粘结剂成膜时呈离散分布。当第一单体、第二单体、第三单体、交联单体和乳化剂含量在本申请范围内，得到的粘结剂在石墨表面成膜时呈离散分布，分散均匀，提高了负极活性物质层的粘结力，得到的锂离子电池具有良好的循环性能和膨胀性能。
对比例1-1和对比例1-2中，不含交联单体的粘结剂的交联度为0，无交联单体来提供交联结构，对比例1-1和对比例1-2制备的负极极片，负极活性物质层的粘结力低于本申请实施例提供的粘结剂，不利于负极极片结构稳定，从而无法改善锂离子电池的循环性能和膨胀性能。
交联单体提供交联结构，提高Tg，可以减少分子链的迁移成膜。从实施例1-1、实施例1-8至实施例1-10可以看出，交联单体含量在本申请范围内，得到的粘结剂在石墨表面成膜时呈离散分布，提高了负极活性物质层的粘结力，得到的锂离子电池具有更好的循环性能和膨胀性能。
从实施例1-1、实施例1-11至实施例1-12可以看出，乳化剂含量的增加，粘结剂成膜颗粒点直径减小，有利于离散分布成膜，从而提高了负极活性物质层的粘结力。乳化剂含量在本申请范围内，制备的粘结剂可以提高负极活性物质层的粘结力，从而改善锂离子电池的循环性能和膨胀性能。另外，乳化剂含量在本申请范围内，粘结剂成膜颗粒点直径小，在活性物质表面覆盖面积较小，得到的负极极片的离子电阻也较小，同时可以提高锂离子电池的快速充电性能。
对比例1-2和对比例1-3中，添加的乳化剂为十二烷基磺酸钠，不在本申请提供的乳化剂范围内，其成膜颗粒点直径均大于300nm，成团簇分布。将对比例1-2和对比例1-3制备的粘结剂应用于负极极片，负极极片的离子电阻高于本申请实施例，负极活性物质层的粘结力远低于本申请实施例，无法改善锂离子电池的快速充电性能、循环性能和膨胀性 能。
从实施例1-1、实施例2-1至实施例2-2可以看出，负极极片中，粘结剂含量在本申请范围内，可以有效提高负极极片的结构稳定性，从而改善锂离子电池的循环性能和膨胀性能。
从实施例1-1、实施例2-3至实施例2-4可以看出，负极极片中，负极活性物质层的压实密度在本申请范围内，本申请提供的粘结剂可以有效提高负极极片的结构稳定性，从而改善锂离子电池的循环性能和膨胀性能。
将本申请提供的粘结剂，应用于负极极片中能够提高负极极片的结构稳定性，从而提高锂离子电池的充电速率，延长循环寿命。本申请提供的锂离子电池在25℃循环800次时，循环膨胀率＜10％，容量保持率均＞90％，有效改善了锂离子电池的循环性能和膨胀性能。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (12)

  1. 一种粘结剂，包括共聚物，其中，所述共聚物通过以下混合物共聚获得，所述混合物包括第一单体丁二烯、第二单体苯乙烯、第三单体、交联单体和乳化剂；所述第三单体包括(甲基)丙烯酸酯、丙烯腈、丙烯酸及其衍生物中的至少一种，所述交联单体包括三乙二醇二丙烯酸酯、N,N-亚甲基双丙烯酰胺、二丙烯酸乙二醇酯或乙二醇二丙烯酸酯中的至少一种。
  2. 根据权利要求1所述的粘结剂，其中，所述第一单体、所述第二单体和所述第三单体的质量比为(15％至35％):(60％至85％):(0％至15％)；基于所述第一单体、所述第二单体和所述第三单体的总质量，所述交联单体的质量百分含量为0.5％至3％。
  3. 根据权利要求1所述的粘结剂，其中，所述乳化剂包括失水木糖醇单油酸酯、山梨糖醇酐单油酸酯、二氯化-N,N′-二(3-松香酰氧基-2-羟丙基)四羟乙基异羟基丙二胺、烷氧基化醇或脂肪酸多元醇酯中的至少一种。
  4. 根据权利要求1所述的粘结剂，其中，基于所述第一单体、所述第二单体和所述第三单体的总质量，所述乳化剂的质量百分含量为0.5％至2％。
  5. 根据权利要求1所述的粘结剂，其中，所述粘结剂满足以下特征1)至6)中的至少一者：
    1)所述粘结剂的玻璃化转变温度为10℃至70℃；
    2)所述粘结剂的交联度为10％至80％；
    3)所述粘结剂在电解液中的溶胀度为30％至150％；
    4)所述粘结剂在负极极片中呈离散分布，所述离散分布中的每一个点的平均直径为100nm至300nm；
    5)所述粘结剂的胶膜拉伸强度为5MPa至30MPa；
    6)所述粘结剂的胶膜断裂伸长率为50％至300％。
  6. 一种负极极片，其包括负极集流体以及设置于所述负极集流体的至少一个表面上的负极活性物质层，所述负极活性物质层包括负极活性物质和权利要求1至5中任一项所述的粘结剂。
  7. 根据权利要求6所述的负极极片，其中，基于所述负极活性物质层的质量，所述粘结剂的质量百分含量为1％至10％。
  8. 根据权利要求6所述的负极极片，其中，所述负极活性物质包括石墨、硬碳、硅、硅碳或氧化亚硅中的至少一种。
  9. 根据权利要求6所述的负极极片，其中，所述负极活性物质层的压实密度为1.45g/cm 3至1.85g/cm 3。
  10. 根据权利要求6至9中任一项所述的负极极片，其中，所述负极极片满足以下特征a)或b)中的至少一者：
    a)所述负极极片的离子电阻为4mΩ至20mΩ；
    b)所述负极活性物质层的粘结力为10N/m至200N/m。
  11. 一种电化学装置，其包括权利要求6至10中任一项所述的负极极片。
  12. 一种电子装置，其包括权利要求11所述的电化学装置。
PCT/CN2022/083967 2022-03-30 2022-03-30 一种粘结剂、负极极片、电化学装置及电子装置 WO2023184209A1 (zh)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030113626A1 (en) * 1997-03-04 2003-06-19 Nippon Zeon Co., Ltd. Binder for battery, slurry for battery electrode, electrode for lithium secondary battery, and lithium secondary battery
US20070191531A1 (en) * 2004-07-20 2007-08-16 Basf Aktiengesellschaft Method for the production of aqueous styrol-butadiene polymer dispersions
JP2009266612A (ja) * 2008-04-25 2009-11-12 Toray Ind Inc リチウムイオン二次電池用バインダー
JP2013073921A (ja) * 2011-09-29 2013-04-22 Panasonic Corp 電池電極用バインダーおよびそれを用いたリチウム二次電池用電極
CN105246932A (zh) * 2013-03-15 2016-01-13 巴斯夫欧洲公司 包含固体级低聚物和疏水性单体和/或气相单体的共聚物的组合物及其制备方法
CN110416547A (zh) * 2018-04-26 2019-11-05 中国石油化工股份有限公司 浆料组合物及其制备方法和电池负极以及锂离子电池
CN113045702A (zh) * 2021-03-15 2021-06-29 珠海冠宇电池股份有限公司 一种硼酸衍生物改性的粘结剂及含有该粘结剂的锂离子电池
CN113410468A (zh) * 2021-08-19 2021-09-17 江苏卓高新材料科技有限公司 负极粘结剂及其制备方法、负极片的制备方法、锂离子电池

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20030113626A1 (en) * 1997-03-04 2003-06-19 Nippon Zeon Co., Ltd. Binder for battery, slurry for battery electrode, electrode for lithium secondary battery, and lithium secondary battery
US20070191531A1 (en) * 2004-07-20 2007-08-16 Basf Aktiengesellschaft Method for the production of aqueous styrol-butadiene polymer dispersions
JP2009266612A (ja) * 2008-04-25 2009-11-12 Toray Ind Inc リチウムイオン二次電池用バインダー
JP2013073921A (ja) * 2011-09-29 2013-04-22 Panasonic Corp 電池電極用バインダーおよびそれを用いたリチウム二次電池用電極
CN105246932A (zh) * 2013-03-15 2016-01-13 巴斯夫欧洲公司 包含固体级低聚物和疏水性单体和/或气相单体的共聚物的组合物及其制备方法
CN110416547A (zh) * 2018-04-26 2019-11-05 中国石油化工股份有限公司 浆料组合物及其制备方法和电池负极以及锂离子电池
CN113045702A (zh) * 2021-03-15 2021-06-29 珠海冠宇电池股份有限公司 一种硼酸衍生物改性的粘结剂及含有该粘结剂的锂离子电池
CN113410468A (zh) * 2021-08-19 2021-09-17 江苏卓高新材料科技有限公司 负极粘结剂及其制备方法、负极片的制备方法、锂离子电池

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