WO2023077357A1 - 负极活性材料、电化学装置和电子装置 - Google Patents

负极活性材料、电化学装置和电子装置 Download PDF

Info

Publication number
WO2023077357A1
WO2023077357A1 PCT/CN2021/128701 CN2021128701W WO2023077357A1 WO 2023077357 A1 WO2023077357 A1 WO 2023077357A1 CN 2021128701 W CN2021128701 W CN 2021128701W WO 2023077357 A1 WO2023077357 A1 WO 2023077357A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative electrode
active material
electrode active
silicon
oxygen
Prior art date
Application number
PCT/CN2021/128701
Other languages
English (en)
French (fr)
Inventor
李鑫
Original Assignee
宁德新能源科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to CN202180016776.0A priority Critical patent/CN115152057A/zh
Priority to PCT/CN2021/128701 priority patent/WO2023077357A1/zh
Publication of WO2023077357A1 publication Critical patent/WO2023077357A1/zh

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of energy storage, in particular to a negative electrode active material, an electrochemical device and an electronic device.
  • silicon is considered to be the most likely anode material for large-scale application of lithium-ion batteries.
  • silicon will experience a volume expansion of about 400% during the charge and discharge process, and the ultra-high volume expansion will cause damage to the solid electrolyte interface (SEI). Formation produces a large number of SEI by-products.
  • one of the main means to improve the cycle performance of silicon-based materials is to coat the surface of silicon-based materials with carbon, but a single carbon coating cannot effectively withstand the volume expansion of silicon-oxygen materials during the electrochemical reaction, which limits its further application.
  • the present application provides a negative electrode active material and an electrochemical device comprising the negative electrode active material.
  • the negative electrode active material When used in an electrochemical device, it can significantly improve the cycle performance of the electrochemical device.
  • the negative electrode active material provided by the present application includes silicon-oxygen particles and a silicon-oxygen-carbon layer on the surface of the silicon-oxygen particles, wherein the silicon-oxygen-carbon layer includes silicon-oxygen-carbon composite particles.
  • the negative electrode active material of the present application utilizes the structural stability of the surface silicon-oxygen-carbon material to effectively improve the interface stability of the silicon-oxygen material during cycling, thereby improving the capacity retention and expansion rate of the electrochemical device using the negative electrode active material .
  • the negative electrode active material satisfies at least one of the following conditions (a) to (c): (a) the 29 Si MAS NMR spectrum of the negative electrode active material has a peak in the following range: -5ppm ⁇ 2ppm , -35ppm ⁇ 2ppm, -75ppm ⁇ 2ppm; (b) the 29 Si MAS NMR spectrum of the negative active material has a peak in the range of -100ppm ⁇ 2ppm; (c) the 29 Si MAS NMR spectrum of the negative active material is at -5ppm Peaks in the range of ⁇ 2ppm have a half-width of 20ppm to 25ppm.
  • the 29 Si MAS NMR spectrum of the negative electrode active material has peaks in the following ranges: -5ppm ⁇ 2ppm, -35ppm ⁇ 2ppm, -75ppm ⁇ 2ppm, -100ppm ⁇ 2ppm.
  • the 29 Si MAS NMR spectrogram of the negative electrode active material of the present application has absorption peaks within the above range, indicating that carbon atoms, silicon atoms and oxygen atoms in the material form bonds with each other. The three atoms of carbon, silicon, and oxygen are bonded together, which is conducive to improving the structural stability of silicon-oxygen-carbon materials.
  • the negative electrode active material satisfies at least one of the following conditions (d) to (g): (d) the thickness of the silicon oxygen carbon layer is d, where 10nm ⁇ d ⁇ 2000nm; (e) silicon The oxygen-carbon layer includes silicon-oxygen-carbon composite particles with an amorphous phase structure; (f) the particle size of the silicon-oxycarbon-carbon composite particles is 1 nm to 60 nm; (g) at least 70% of the silicon-oxygen-carbon composite particles in the silicon-oxygen-carbon composite particles are The particle size is from 20nm to 46nm.
  • the thickness d of the SiOC layer satisfies 10nm ⁇ d ⁇ 2000nm.
  • the silicon-oxygen-carbon layer cannot effectively protect the interface, which in turn leads to a decrease in the capacity retention rate and an increase in the expansion rate of the electrochemical device.
  • the thickness of the silicon oxygen carbon layer is large, although the capacity retention rate of the electrochemical device can be improved and the expansion rate can be reduced, more active lithium storage sites will be lost, resulting in a loss of energy density of the electrochemical device.
  • the silicon-oxygen-carbon layer includes silicon-oxygen-carbon composite particles with an amorphous phase structure.
  • the elements in the silicon-oxygen-carbon composite particles with amorphous phase structure are evenly distributed, and the silicon crystal grains are evenly dispersed in the Si-O-C skeleton, so that the silicon-oxygen-carbon material maintains the most stable structure, thereby achieving good protection for the silicon-oxygen material interface.
  • the particle size of the silicon-oxygen-carbon composite particles is 1 nm to 60 nm. In some embodiments, at least 70% of the silicon oxygen carbon composite particles in the silicon oxygen carbon composite particles have a particle size of 20 nm to 46 nm. If the particle size of the silicon-oxygen-carbon composite particles is too small, the electrical conductivity of the negative electrode active material will be poor, thereby reducing the gram capacity of the material, reducing the cycle retention rate of the electrochemical device, and increasing the expansion rate.
  • the particle size of the silicon-oxygen-carbon composite particles is too large, the ion transport of the negative electrode active material becomes poor, and the utilization rate of the negative electrode active material decreases, which in turn reduces the gram capacity of the material, reduces the cycle retention rate of the electrochemical device, and increases the expansion rate. .
  • the thickness d of the silicon oxygen carbon layer and the Dv50 of the silicon oxygen particles satisfy: 0.0015 ⁇ d/Dv50 ⁇ 0.8.
  • the Dv50 of the silica particles ranges from 2.5 ⁇ m to 10 ⁇ m. If the particle size of the silicon-oxygen particles is too small, adhesion between the silicon-oxygen particles will occur, and the stress distribution of the negative electrode active material will be uneven during the lithium intercalation process, which will lead to a decrease in the capacity retention rate and an increase in the expansion rate of the electrochemical device.
  • the silicon oxide particles are SiO x , and x satisfies 0.5 ⁇ x ⁇ 1.5.
  • the silica particles include at least two of Si, SiO, and SiO2 . In some embodiments, the silica particles are SiO.
  • the negative electrode active material satisfies at least one of the following conditions (h) to (j): (h) based on the mass of the negative electrode active material, the content of carbon element is a%, wherein 0.9 ⁇ a ⁇ 11; (i) based on the quality of negative electrode active material, the content of silicon element is b%, wherein 50 ⁇ b ⁇ 63; (j) based on the quality of negative electrode active material, the content of carbon element is a%, and the content of silicon element is b%, where 0.015 ⁇ a/b ⁇ 0.25. According to some embodiments of the present application, based on the mass of the negative electrode active material, the content a% of the carbon element satisfies 0.9 ⁇ a ⁇ 11.
  • the content b% of the silicon element satisfies 50 ⁇ b ⁇ 63. According to some embodiments of the present application, based on the mass of the negative electrode active material, the content a% of the carbon element and the content b% of the silicon element satisfy 0.015 ⁇ a/b ⁇ 0.25.
  • the negative electrode active material satisfies at least one of the following conditions (e) to (h): (k) 2 ⁇ in the X-ray diffraction pattern of the negative electrode active material belongs to the highest in the range of 28.0° to 29.0° The intensity value is I2, and the highest intensity value belonging to the range of 20.5° to 21.5° is I1, where 0 ⁇ I2/I1 ⁇ 1; (l) The specific surface area of the negative electrode active material is 1m 2 /g to 50m 2 /g; ( m) The powder conductivity of the negative electrode active material is 2.0 S/cm to 30 S/cm; (n) The negative electrode active material also includes graphite.
  • the negative electrode active material further includes graphite, and the addition of graphite can increase the gram capacity of the negative electrode active material.
  • the graphite includes at least one of natural graphite, artificial graphite, or mesocarbon microspheres.
  • the preparation method of the negative electrode active material includes the following steps: heat-treating a solution containing silicon oxide, silicon source, carbon source and organic solvent to obtain a heat-treated powder;
  • the powder is subjected to calcination treatment; wherein, the temperature of the heat treatment is 80°C to 120°C; and/or the calcination treatment includes calcination at a calcination temperature of 600°C to 1200°C.
  • the calcination treatment includes heating up to 600°C to 1200°C at a rate of 3°C/min to 10°C/min for calcination.
  • the calcination treatment includes heating up to 800°C to 1200°C at a rate of 3°C/min to 10°C/min for calcination.
  • the temperature of the heat treatment is 80°C to 120°C.
  • the heat treatment temperature is too high, the crosslinking temperature of silicon oxide, silicon source and carbon source is too high, and the uniformity of shrinkage stress in the crosslinking process becomes poor, which in turn increases the defects of the material, resulting in the loss of the obtained negative electrode active material.
  • the gram capacity decreases and the SiOC layer becomes thinner.
  • the firing temperature is 600°C to 1200°C.
  • the calcination temperature is too high, the crystal grains of the material become larger, and even crystallization peaks appear, resulting in poor ion transport of the negative electrode active material and a decrease in the gram capacity, which in turn affects the cycle retention and expansion rate of the electrochemical device.
  • the heating rate is 3°C/min to 10°C/min.
  • the crystal nucleation is small, resulting in poor electrical conductivity of the negative electrode active material, which in turn reduces the gram capacity of the negative electrode active material, reduces the cycle retention rate of the electrochemical device, and increases the expansion rate.
  • the heating rate increases, the crystal particles become larger, resulting in poor ion transport of the negative electrode active material, a decrease in the utilization rate of the negative electrode active material, a decrease in the cycle retention rate of the electrochemical device, and an increase in the expansion rate.
  • the present application provides an electrochemical device, which includes a negative electrode, and the negative electrode includes the negative electrode active material of the first aspect.
  • the sheet resistance of the negative electrode is 0.2 ⁇ to 1 ⁇ .
  • the present application provides an electronic device, which includes the electrochemical device described in the second aspect of the present application.
  • the present application provides a negative electrode active material, which utilizes the structural stability of the surface silicon-oxygen-carbon material to effectively improve the interface stability of the silicon-oxygen material during cycling, thereby improving the electrochemical performance of the negative electrode active material. Capacity retention and expansion of the device.
  • Fig. 1 is a schematic structural diagram of negative electrode active materials according to some embodiments of the present application, where 1 represents SiO x , and 2 represents a silicon-oxygen-carbon layer.
  • FIG. 2 is an SEM image of the negative electrode active material of Example 1.
  • FIG. 3 is an SEM image of the negative electrode active material of Example 1.
  • FIG. 4 is an EDS diagram of the negative electrode active material of Example 1.
  • FIG. 5 is an NMR chart of the negative electrode active material of Example 1.
  • FIG. 6 is an XRD pattern of the negative electrode active material of Example 1.
  • any lower limit can be combined with any upper limit to form an unexpressed range; and any lower limit can be combined with any other lower limit to form an unexpressed range, just as any upper limit can be combined with any other upper limit to form an unexpressed range.
  • each individually disclosed point or individual value may serve as a lower or upper limit by itself in combination with any other point or individual value or with other lower or upper limits to form an unexpressly recited range.
  • a list of items to which the terms "at least one of”, “at least one of”, “at least one of” or other similar terms are concatenated can mean any combination of the listed items. For example, if the items A and B are listed, the phrase “at least one of A and B" means only A; only B; or A and B. In another example, if the items A, B, and C are listed, the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may comprise a single component or multiple components.
  • Item B may comprise a single component or multiple components.
  • Item C may comprise a single component or multiple components.
  • the negative electrode active material provided in the present application includes silicon oxygen particles and a silicon oxygen carbon layer located on the surface of the silicon oxygen particles, wherein the silicon oxygen carbon layer includes silicon oxygen carbon composite particles.
  • the negative electrode active material of the present application utilizes the structural stability of the surface silicon-oxygen-carbon material to effectively improve the interface stability of the silicon-oxygen material during cycling, thereby improving the capacity retention and expansion rate of the electrochemical device using the negative electrode active material .
  • the 29 Si MAS NMR spectrum of the negative electrode active material has peaks in the following ranges: -5ppm ⁇ 2ppm, -35ppm ⁇ 2ppm, -75ppm ⁇ 2ppm.
  • the 29 Si MAS NMR spectrum of the negative electrode active material has a peak within the range of -100ppm ⁇ 2ppm.
  • the 29 Si MAS NMR spectrogram of the negative electrode active material of the present application has absorption peaks within the above range, indicating that carbon atoms, silicon atoms and oxygen atoms in the material form bonds with each other. The three atoms of carbon, silicon and oxygen are associated together, which is conducive to improving the structural stability of silicon-oxygen-carbon materials.
  • the 29 Si MAS NMR spectrogram of the negative electrode active material has a half-peak width of the peak in the range of -5ppm ⁇ 2ppm, which is 20ppm to 25ppm, such as 21ppm, 22ppm, 23ppm, 24ppm or any two of these values. range of components.
  • the absorption peak at the chemical shift -5ppm ⁇ 2ppm is attributed to silicon in the SiOC 3 group.
  • the absorption peak at the chemical shift -35ppm ⁇ 2ppm is assigned to silicon in the SiO 2 C 2 group.
  • the absorption peak at chemical shift -75ppm ⁇ 2ppm is assigned to silicon in the SiO 3 C group.
  • the absorption peak at chemical shift ⁇ 100 ppm is assigned to the four-coordinated silicon bonded to oxygen in the silicon-oxygen tetrahedron ( SiO4 group).
  • the silicon oxycarbon layer has a thickness d, where 10 nm ⁇ d ⁇ 2000 nm.
  • d is 20nm, 40nm, 60nm, 80nm, 90nm, 120nm, 150nm, 200nm, 300nm, 500nm, 700nm, 900nm, 1000nm, 1200nm, 1500nm, 1700nm, 1900nm or any two of these values scope.
  • the silicon-oxygen-carbon coating layer cannot effectively protect the interface, which in turn leads to a decrease in the capacity retention rate and an increase in the expansion rate of the electrochemical device.
  • the thickness of the silicon oxygen carbon layer is large, although the capacity retention rate of the electrochemical device can be improved and the expansion rate can be reduced, more active lithium storage sites will be lost, resulting in a loss of energy density of the electrochemical device.
  • the silicon-oxygen-carbon layer includes silicon-oxygen-carbon composite particles with an amorphous phase structure.
  • the elements in the silicon-oxygen-carbon composite particles with amorphous phase structure are evenly distributed, and the silicon crystal grains are evenly dispersed in the Si-O-C skeleton, so that the silicon-oxygen-carbon material maintains the most stable structure, thereby achieving good protection for the silicon-oxygen material interface.
  • the particle size of the silicon-oxygen-carbon composite particles is 1 nm to 60 nm.
  • the particle size of the silicon oxygen carbon composite particle is 5nm to 55nm, 5nm to 50nm, 10nm to 55nm, 10nm to 50nm, 10nm to 48nm, 15nm to 55nm, 15nm to 50nm, 15nm to 48nm, 20nm to 50nm , 20nm to 48nm, 25nm to 50nm, 25nm to 48nm, 30nm to 55nm or 40nm to 55nm, etc.
  • At least 70%, eg, 75%, 80%, 85%, 90%, 95% of the silicon-oxycarbon-carbon composite particles have a particle size of 15 nm to 55 nm. In some embodiments, at least 70%, eg, 75%, 80%, 85%, 90%, 95% of the silicon oxygen carbon composite particles have a particle size of 20 nm to 50 nm. In some embodiments, at least 70%, eg, 75%, 80%, 85%, 90%, 95% of the silicon-oxycarbon-carbon composite particles have a particle size of 20 nm to 46 nm.
  • the particle size of the silicon-oxygen-carbon composite particles is too small, the electrical conductivity of the negative electrode active material will be poor, thereby reducing the gram capacity of the material, reducing the cycle retention rate of the electrochemical device, and increasing the expansion rate.
  • the particle size of the silicon-oxygen-carbon composite particles is too large, the ion transport of the negative electrode active material becomes poor, and the utilization rate of the negative electrode active material decreases, which in turn reduces the gram capacity of the material, reduces the cycle retention rate of the electrochemical device, and increases the expansion rate. .
  • the thickness d of the silicon oxygen carbon layer and the Dv50 of the silicon oxygen particles satisfy: 0.0015 ⁇ d/Dv50 ⁇ 0.8.
  • d/Dv50 is 0.002, 0.005, 0.01, 0.015, 0.02, 0.03, 0.05, 0.09, 0.15, 0.3, 0.4, 0.45, 0.55, 0.7, or a range consisting of any two of these values.
  • the Dv50 of the silica particles ranges from 2.5 ⁇ m to 10 ⁇ m.
  • the Dv50 is in the range of 2.5 ⁇ m, 3.0 ⁇ m, 4.0 ⁇ m, 4.5 ⁇ m, 5.5 ⁇ m, 6.0 ⁇ m, 7.0 ⁇ m, 8.0 ⁇ m, or a combination of any two of these values.
  • Dv50 is the particle diameter corresponding to when the cumulative volume percentage of particles reaches 50%. If the particle size of the silicon-oxygen particles is too small, adhesion between the silicon-oxygen particles will occur, and the stress distribution of the negative electrode active material will be uneven during the lithium intercalation process, which will lead to a decrease in the capacity retention rate and an increase in the expansion rate of the electrochemical device.
  • the silicon oxide particles are SiO x , and x satisfies 0.5 ⁇ x ⁇ 1.5.
  • the silica particles include at least two of Si, SiO, and SiO2 . In some embodiments, the silica particles are SiO.
  • the content of the carbon element is a%, wherein 0.9 ⁇ a ⁇ 11.
  • a is a range of 0.95, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10.5, or a combination of any two of these values. In some embodiments, 1 ⁇ a ⁇ 10.
  • the content of the silicon element is b%, wherein 50 ⁇ b ⁇ 63.
  • b is a range of 52, 54, 57, 59, 62, or any combination of any two of these values. In some embodiments, 55 ⁇ b ⁇ 63.
  • the content of carbon element is a%
  • the content of silicon element is b%, wherein 0.015 ⁇ a/b ⁇ 0.25.
  • a/b is a range of 0.018, 0.025, 0.035, 0.05, 0.07, 0.10, 0.13, 0.15, 0.17, 0.19, 0.23, or a combination of any two of these values.
  • the highest intensity value of 2 ⁇ belonging to the range of 28.0° to 29.0° is I2
  • the highest intensity value of the range of 20.5° to 21.5° is I1, where 0 ⁇ I2/I1 ⁇ 1.
  • the specific surface area of the negative electrode active material is 1 m 2 /g to 50 m 2 /g. In some embodiments, the specific surface area of the negative electrode active material is 1m 2 /g, 10m 2 /g, 20m 2 /g, 30m 2 /g, 40m 2 /g, 45m 2 /g or any combination of these values range.
  • the powder conductivity of the negative electrode active material is 2.0 S/cm to 30 S/cm. In some embodiments, the powder conductivity of the negative electrode active material is 3.0S/cm, 5.0S/cm, 7.0S/cm, 10S/cm, 15S/cm, 20S/cm, 25S/cm or any two of these values. range of components.
  • the negative electrode active material further includes graphite, and the addition of graphite can increase the gram capacity of the negative electrode active material.
  • the graphite includes at least one of natural graphite, artificial graphite, or mesocarbon microspheres.
  • the preparation method of the negative electrode active material of the present application includes heat-treating a solution containing silicon oxide, silicon source, carbon source and organic solvent to obtain a heat-treated powder; calcining the heat-treated powder; wherein, the heat-treated The temperature is 80°C to 120°C; and/or the firing treatment includes firing at a firing temperature of 600°C to 1200°C.
  • the calcination treatment includes heating up to 600°C to 1200°C at a rate of 3°C/min to 10°C/min for calcination.
  • the calcination treatment includes heating up to 800°C to 1200°C at a rate of 3°C/min to 10°C/min for calcination.
  • the temperature of the heat treatment is 80°C to 120°C.
  • the heat treatment temperature is too high, the crosslinking temperature of silicon oxide, silicon source and carbon source is too high, and the uniformity of shrinkage stress in the crosslinking process becomes poor, which in turn increases the defects of the material, resulting in the loss of the obtained negative electrode active material.
  • the gram capacity decreases and the SiOC layer becomes thinner.
  • the temperature of the heat treatment is in the range of 85°C, 90°C, 95°C, 105°C, 110°C, 115°C, or a combination of any two of these values.
  • the firing temperature is 600°C to 1200°C. In some embodiments, the firing temperature is 800°C to 1200°C.
  • the calcination temperature is too high, the crystal grains of the material become larger, and even crystallization peaks appear, resulting in poor ion transport of the negative electrode active material and a decrease in the gram capacity, which in turn affects the cycle retention and expansion rate of the electrochemical device.
  • the firing temperature is in the range of 650°C, 700°C, 750°C, 850°C, 950°C, 1050°C, 1150°C, or a combination of any two of these values.
  • the heating rate is 3°C/min to 10°C/min.
  • the heating rate is reduced, the crystal nucleation is small, resulting in poor electrical conductivity of the negative electrode active material, which in turn reduces the gram capacity of the negative electrode active material, reduces the cycle retention rate of the electrochemical device, and increases the expansion rate.
  • the heating rate increases, the crystal particles become larger, resulting in poor ion transport of the negative electrode active material, a decrease in the utilization rate of the negative electrode active material, a decrease in the cycle retention rate of the electrochemical device, and an increase in the expansion rate.
  • the heating rate is in the range of 4°C/min, 6°C/min, 7°C/min, 8°C/min, 9°C/min or a combination of any two of these values.
  • the silicon oxide is SiO x , and x satisfies 0.5 ⁇ x ⁇ 1.5.
  • the silicon oxide includes at least two of Si, SiO, and SiO2 .
  • the silicon oxide is SiO.
  • the silicon source includes at least one of tetramethyl-tetravinyl-cyclotetrasiloxane or polymethylhydrogensiloxane.
  • the carbon source includes at least one of tetramethyl-tetravinyl-cyclotetrasiloxane or polymethylhydrogensiloxane.
  • the organic solvent includes at least one of methanol, ethanol, n-hexane, N,N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol or n-propanol.
  • the electrochemical device provided by the present application includes a negative electrode, and the negative electrode includes the negative electrode active material of the first aspect. According to some embodiments of the present application, the sheet resistance of the negative electrode is 0.2 ⁇ to 1 ⁇ .
  • the negative electrode includes a negative electrode current collector and a negative electrode active material layer disposed on the surface of the negative electrode current collector, and the negative electrode active material layer includes the negative electrode active material of the first aspect.
  • the negative active material layer further includes a binder, and the binder may include various binder polymers.
  • the binder includes polyvinylidene fluoride, copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polypropylene ester, polyacrylic acid, polyacrylate salt, sodium carboxymethyl cellulose , polyvinylpyrrolidone, polyvinyl ether, polymethylmethacrylate, polytetrafluoroethylene, polyhexafluoropropylene or styrene-butadiene rubber.
  • the negative active material layer further includes a conductive material to improve electrode conductivity. Any conductive material can be used as the conductive material as long as it does not cause a chemical change.
  • the conductive material includes at least one of conductive carbon black, acetylene black, carbon nanotubes, Ketjen black, conductive graphite, or graphene.
  • the negative electrode current collector may be copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with conductive metal, or a combination thereof.
  • the electrochemical device further includes a positive electrode, and the positive electrode includes a current collector and a positive electrode active material layer on the current collector.
  • the positive electrode active material includes, but is not limited to: lithium cobalt oxide (LiCoO 2 ), lithium nickel cobalt manganese (NCM) ternary material, lithium ferrous phosphate (LiFePO 4 ) or lithium manganese oxide (LiMn 2 O 4 ).
  • the cathode active material layer further includes a conductive agent and a binder.
  • binders include, but are not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin or Nylon etc.
  • conductive agents include, but are not limited to, carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum or silver.
  • the conductive polymer is a polyphenylene derivative.
  • the positive electrode current collector may use a metal foil or a composite current collector.
  • a metal foil aluminum foil can be used.
  • the composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate.
  • the positive electrode of the present application can be prepared by methods known in the art. Usually, materials such as positive electrode materials and optional conductive agents (such as carbon materials such as carbon black and metal particles, etc.), binders (such as SBR), and other optional additives (such as PTC thermistor materials) are mixed together Disperse in a solvent (such as deionized water), stir evenly, and evenly coat on the positive electrode current collector, and dry to obtain the positive electrode containing the positive electrode membrane.
  • a solvent such as deionized water
  • the electrochemical device further includes an electrolytic solution or a solid electrolyte.
  • the electrolyte that can be used in the examples of the present application can be the electrolyte known in the prior art.
  • the electrolyte includes an organic solvent, a lithium salt, and additives.
  • the organic solvent of the electrolytic solution according to the present application can be any organic solvent known in the prior art that can be used as a solvent for the electrolytic solution.
  • the electrolyte used in the electrolytic solution according to the present application is not limited, and it may be any electrolyte known in the prior art.
  • the additive of the electrolytic solution according to the present application may be any additive known in the prior art as an additive to the electrolytic solution.
  • the organic solvents include, but are not limited to: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
  • the organic solvent includes an ether solvent, for example, at least one of 1,3-dioxane (DOL) and ethylene glycol dimethyl ether (DME).
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salts include, but are not limited to: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bisoxalate borate LiB(C 2 O 4 ) 2 (LiBOB ) or lithium difluorooxalate borate LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiTFSI bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2
  • the solid electrolyte includes Li 2+x Al 2+x Si 1-x S 6 (0 ⁇ x ⁇ 1), Li 3 YCl 6 , Li 3 YBr 6 , Li 3 OCl, LiPON , Li 0.5 La 0.5 TiO 3 , Li 1+x Al x Ti 2-x (PO 4 ) 3 , Li 7 La 3 Zr 2 O 12 , Li 10 GeP 2 S 12 (LGPS), Li 9.54 Si 1.74 P 1.44 S At least one of 11.7 Cl 0.3 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 11 AlP 2 S 12 and Li 7 P 3 S 11 .
  • a separator is provided between the positive electrode and the negative electrode to prevent short circuit.
  • the material and shape of the isolation film used in the embodiments of the present application are not particularly limited, and it can be any technology disclosed in the prior art.
  • the separator includes a polymer or an inorganic substance formed of a material stable to the electrolyte of the present application.
  • a release film may include a substrate layer and a surface treatment layer.
  • the substrate layer is non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer includes at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide.
  • polypropylene porous film, polyethylene porous film, polypropylene non-woven fabric, polyethylene non-woven fabric or polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing polymers and inorganic materials.
  • the inorganic layer includes inorganic particles and binders, and the inorganic particles include aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium oxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, oxide At least one of yttrium, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • Binders include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether, poly At least one of methyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the polymer layer comprises a polymer, and the polymer material includes polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly( at least one of vinylidene fluoride-hexafluoropropylene).
  • the electrochemical device of the present application includes, but is not limited to: all kinds of primary batteries, secondary batteries, fuel cells, solar cells or capacitors.
  • the electrochemical device is a lithium secondary battery.
  • lithium secondary batteries include, but are not limited to: lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, or lithium ion polymer secondary batteries.
  • the electronic device of the present application can be any device using the electrochemical device according to the third aspect of the present application.
  • the electronic devices include, but are not limited to: notebook computers, pen-based computers, mobile computers, e-book players, cellular phones, portable fax machines, portable copiers, portable printers, stereo headsets , VCR, LCD TV, Portable Cleaner, Portable CD Player, Mini Disc, Transceiver, Electronic Notepad, Calculator, Memory Card, Portable Recorder, Radio, Backup Power, Motor, Automobile, Motorcycle, Assisted Bicycle, Bicycle , Lighting appliances, toys, game consoles, clocks, electric tools, flashlights, cameras, large household batteries or lithium-ion capacitors, etc.
  • Step 1 Add organosilicon (polysiloxane, etc.) into the organic solvent in a certain proportion, and stir for 0.5h to 4h.
  • the SiO x (0.5 ⁇ x ⁇ 1.5) material was completely immersed in the silicone solution, then stirred and heated at 80°C to remove the solvent, and then the product was dried in an oven at 80°C to 120°C for 24 hours.
  • Step 2 Put the dried product obtained in step 1 into a tube furnace for high temperature pyrolysis, use N2 or Ar as the protective atmosphere, and the heating program: 3°C/min to 10°C/min to 800°C to 1200°C and keep 3h, high temperature pyrolysis to obtain SiO x @ silicon oxygen carbon material.
  • the SiO x @ silicon oxygen carbon material and graphite were mixed in a weight ratio of 4:6 to obtain a mixed powder.
  • the mixed powder, conductive agent acetylene black, and PAA are fully stirred and mixed in a deionized water solvent system according to the weight ratio of 95:1.2:3.8, and then coated on Cu foil, dried, and cold pressed to obtain a negative electrode sheet.
  • the prepared positive electrode slurry is coated on the aluminum foil of the positive electrode current collector, dried, and cold pressed to obtain the positive electrode sheet.
  • the PE porous polymer film is used as the isolation membrane.
  • Put the electrode assembly in the outer packaging, inject the prepared electrolyte (EC:DEC 4:6+1.2M LiPF 6 ) and then package it. After chemical formation, degassing, trimming and other processes, the lithium-ion battery is obtained.
  • Step 2 Add 630g SiO (Dv50 is 5.6 ⁇ m) to the precursor solution in step 1, stir for 30min, heat treatment at 80°C to obtain dry powder;
  • Step 3 Calcining the dry powder obtained in step 2, raising the temperature at 5°C/min to 800°C and maintaining for 3h, the SiO x @silicon carbon material can be obtained.
  • Step 4 The preparation method of the lithium-ion battery is the same as that described in the preparation process two.
  • the thickness of the silicon oxygen carbon layer is 100nm. Based on the mass of SiO x @ silicon oxygen carbon material, the content of carbon element is 1.77%, the content of silicon element is 60.0%, and the ratio of carbon and silicon content is 0.0295. The ratio of SiOC coating thickness to Dv50 of SiO is 0.017.
  • the XPS binding energy peaks of Si2 p in SiO x @ silicon oxygen carbon materials are 101.4 ⁇ 0.3eV, 102.2 ⁇ 0.3eV, 103.1 ⁇ 0.3eV, 104.40 ⁇ 0.3e.
  • silicon oxygen carbon composite particles with a particle size of 28nm-46nm can be observed.
  • the shifts of silicon in the solid-state nuclear magnetic (sNMR) test of SiO x @ silicon oxygen carbon materials include -5ppm, -35ppm, -75ppm, -110ppm.
  • the powder gram capacity of SiO x @ silicon oxygen carbon material is 1430mAh/g. After 500 cycles of lithium-ion batteries, the capacity retention rate is 90.1%, and the expansion rate is 10%.
  • Example 2 The preparation of SiO x @ silicon oxygen carbon material and the manufacturing process of lithium ion battery refer to Example 1, the difference is that in Example 2 to Example 4, the quality of SiO added in step 2 is different, see Table 1 for details.
  • Example 1 The preparation of SiO x @ silicon oxygen carbon material and the manufacturing process of lithium ion battery refer to Example 1, the difference is that in Example 5 to Example 12, the heating temperature in Step 2 and Step 3, the roasting temperature during roasting treatment The temperature and heating rate are different, see Table 2 for details.
  • Example 1 The preparation of SiO x @ silicon oxygen carbon material and the manufacturing process of lithium ion battery refer to Example 1, the difference is that in Example 13 to Example 14, the Dv50 of SiO is different, see Table 3 for details.
  • Step 1 Calcining 630g of SiO (Dv50 is 5.6 ⁇ m) powder, raising the temperature at 5°C/min to 800°C and keeping it for 3h, the SiO x material can be obtained.
  • Step 2 The method for preparing the lithium-ion battery is the same as that described in the second preparation process.
  • the powder gram capacity of the SiO x material is 1527mAh/g, and after 500 cycles of the lithium-ion battery, the capacity retention rate is 65.2%, and the expansion rate is 19%.
  • Step 2 Add 630g SiO (Dv50 is 5.6 ⁇ m) to the precursor solution in step 1, stir for 30min, heat treatment at 80°C to obtain dry powder;
  • Step 3 Roasting the dry powder obtained in step 2, raising the temperature at 5°C/min to 1400°C and maintaining for 3h, the SiO x @ silicon oxygen carbon material can be obtained.
  • Step 4 The method for preparing the lithium-ion battery is the same as that described in the preparation process two.
  • the thickness of the silicon carbon layer is 110 nm. Based on the mass of the SiO x @ silicon oxygen carbon material, the content of carbon element is 1.23%, the content of silicon element is 52.1%, and the ratio of carbon and silicon content is 0.0236. The ratio of SiOC layer thickness to Dv50 of SiOx is 0.01964.
  • the gram capacity of SiO x @ silicon oxygen carbon material powder is 231mAh/g, after 500 cycles of lithium ion battery, the capacity retention rate is 65.2%, and the expansion rate is 18%.
  • the SiO x @ silicon oxygen carbon material generates SiC during the synthesis process, so its electrochemical activity is greatly reduced, resulting in a greatly reduced powder gram capacity, which in turn makes the cycle performance and expansion performance of lithium-ion batteries also decrease. sharply worsened.
  • step 2 Add 630g SiO (Dv50 is 5.6 ⁇ m) to the precursor solution in step 1, stir for 30min, heat treatment at 200°C to obtain dry powder;
  • step 3 Roasting the dry powder obtained in step 2, raising the temperature at 5°C/min to 1400°C and keeping it for 3h, the SiO x @ silicon oxygen carbon material can be obtained.
  • the method for preparing the lithium-ion battery is the same as the description in the preparation process two.
  • SiO x @ silicon oxygen carbon material There is no silicon oxygen carbon layer in SiO x @ silicon oxygen carbon material.
  • the powder gram capacity of SiO x @ silicon oxygen carbon material is 1521mAh/g, after 500 cycles of lithium-ion battery, the capacity retention rate is 65.2%, and the expansion rate is 18%. Since the heating temperature is too high, the silicon oxygen carbon precursor is volatilized, so there is no silicon oxygen carbon layer.
  • 29 Si MAS NMR test AVANCE III 400WB wide-cavity solid-state nuclear magnetic resonance instrument was used for the test, and the rotation rate was 8kHz.
  • Carbon content test The sample is heated and burned by a high-frequency furnace under oxygen-enriched conditions to oxidize carbon and sulfur into carbon dioxide and sulfur dioxide respectively. into corresponding signals.
  • the signal is sampled by the computer, and converted into a value proportional to the concentration of carbon dioxide and sulfur dioxide after linear correction, and then the value of the entire analysis process is accumulated. After the analysis, the accumulated value is divided by the weight value in the computer, and then multiplied by The calibration coefficient and the blank can be deducted to obtain the percentage content of carbon and sulfur in the sample.
  • Sample testing was performed using a high-frequency infrared carbon-sulfur analyzer (Shanghai Dekai HCS-140).
  • Silicon content test Weigh 0.5g of active material powder, mix the powder with 10mL HNO 3 solution, dissolve the trace elements in the powder in the solution by microwave digestion, and introduce the digested solution into the ICP (inductively coupled photoelectron) light source
  • ICP-OES inductively coupled plasma optical emission spectrometer
  • Particle size test Add about 0.02g powder sample to a 50mL clean beaker, add about 20mL deionized water, and then drop a few drops of 1% surfactant to completely disperse the powder in the water. MasterSizer 2000 measures particle size distribution.
  • X-ray diffraction (XRD) test X-ray powder diffractometer (XRD, instrument model: Bruker D8 ADVANCE) is used to test the negative electrode active material, the target is Cu K ⁇ ; the voltage and current are 40KV/40mA, and the scanning angle range is 5° to 80° °, the scan step is 0.00836°, and the time of each step is 0.3s.
  • Negative electrode active material gram capacity test under dry argon atmosphere, in a solvent mixed with propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC) (weight ratio about 1:1:1) , add LiPF 6 and mix evenly, wherein the content of LiPF 6 is about 12%, and then add about 7.5% fluoroethylene carbonate (FEC), and mix evenly to obtain an electrolyte solution.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • the assembled button cells were taken to ensure that the open circuit voltage (OCV) was normal, and each group contained at least 4 parallel samples.
  • the voltage window for the coin cell is set from 0V to 2.5V. Let it stand at 25°C for 1 hour, and then discharge the battery with a three-stage low current of 0.05C/50 ⁇ A/20 ⁇ A to realize SEI (solid electrolyte interfacial film) film formation and record the lithium intercalation capacity. Then charge the battery to 2.5V with a current of 0.1C, and record the delithiation capacity, which is the gram capacity of the negative electrode active material.
  • Cycle test The test temperature is 25°C, charge to 4.45V with a constant current of 0.5C, charge to 0.025C with a constant voltage, and discharge to 3.0V at 0.5C after standing for 5 minutes.
  • the capacity obtained in this step is used as the initial capacity, and the 0.5C charge/0.5C discharge is carried out for cycle testing, and the capacity at each step is compared with the initial capacity to obtain the capacity decay curve.
  • the capacity retention rate of the nth lap the discharge capacity of the nth lap/initial capacity ⁇ 100%.
  • Full-charge expansion rate test of lithium-ion batteries The test temperature is 25°C, charged to 4.45V at a constant current of 0.5C, charged at a constant voltage to 0.025C, and discharged to 3.0V at 0.5C after standing for 5 minutes.
  • the cycle reaches 500 times when the lithium-ion battery is fully charged, use a screw micrometer to test the thickness of the lithium-ion battery at this time, which is calculated as h,
  • Table 1 shows the effect of the addition amount of SiO on the negative electrode active material and the performance of the lithium ion battery containing the negative electrode active material.
  • the temperature of the negative electrode active material of Comparative Example 1 and Example 1 to Example 4 is 80°C during the preparation process, the heating rate of the roasting treatment is 5°C/min, the temperature is 800°C, and the roasting time is 3h;
  • the Dv50 of SiO is both 5.6 ⁇ m.
  • the particle size of the carbon-silicon-oxygen composite particles in the table is the particle size corresponding to at least 70% of the carbon-silicon-oxygen composite particles
  • Table 2 shows the influence of the heating temperature in step 2 and step 3, the temperature of calcination during the calcination treatment and the heating rate on the performance of the obtained negative active material and the lithium ion battery containing the negative active material.
  • the amount of SiO added in Example 5 to Example 12 and Comparative Example 2 to Comparative Example 3 is 630 g, and the Dv50 of SiO is 5.6 ⁇ m.
  • the half peak width at the solid NMR-5ppm place of SiO x @ silicon oxygen carbon material in embodiment 5 to embodiment 12 is 20ppm, the half peak width at the solid NMR-5ppm place of the SiO x @ silicon oxygen carbon material of comparative example 2 is 25ppm.
  • the particle size of the carbon-silicon-oxygen composite particles in the table is the particle size corresponding to at least 70% of the carbon-silicon-oxygen composite particles
  • the heating rate When the heating rate is reduced, the crystal nucleation is small, which leads to the deterioration of the electrical conductivity of the SiO x @ silicon oxygen carbon material, which in turn reduces the gram capacity of the material, reduces the cycle retention rate of the lithium-ion battery, and increases the expansion rate.
  • the heating rate is too high, the crystal particles will become larger, resulting in poor ion transport of SiO x @ silicon oxygen carbon material, low utilization rate of active materials, resulting in reduced gram capacity of the material, reduced cycle retention rate of lithium-ion batteries, and low expansion rate. rise.
  • Table 3 shows the Dv50 value of SiO on the negative electrode active material and the performance impact of the lithium ion battery comprising the negative electrode active material.
  • Example 1 the amount of SiO added in Example 1, Example 13 to Example 14 is 630g; the temperature of the negative electrode active material in the preparation process is 80°C, the heating rate of the roasting treatment is 5°C/min, and the temperature is 800°C. °C, the calcination time is 3h.
  • the particle size of the carbon-silicon-oxygen composite particles in the table is the particle size corresponding to at least 70% of the carbon-silicon-oxygen composite particles

Abstract

本申请涉及一种负极活性材料、电化学装置和电子装置。该负极活性材料包括硅氧颗粒和位于所述硅氧颗粒表面的硅氧碳层，其中，所述硅氧碳层包括硅氧碳复合颗粒。该负极活性材料用于电化学装置，能够显著改善循环性能。

Description

负极活性材料、电化学装置和电子装置 技术领域
本申请涉及储能领域，具体涉及一种负极活性材料、电化学装置和电子装置。
背景技术
近年来，由于硅的可逆容量高达4200mAh/g，被认为是最可能大规模应用的锂离子电池负极材料。但是硅在充放电过程中会发生约400％的体积膨胀，超高的体积膨胀造成固体电解质界面(SEI)的破坏，由于界面破坏而露出的新鲜材料表面会不断消耗电解液，导致SEI的反复形成，产生大量的SEI副产物。目前提升硅基材料循环性能的一个主要手段是在硅基材料表面进行碳包覆，但是单一的碳包覆层不能有效地承受硅氧材料在电化学反应过程中发生的体积膨胀，限制了其进一步应用。
发明内容
为了解决现有技术存在的问题，本申请提供一种负极活性材料及包含该负极活性材料的电化学装置。该负极活性材料用于电化学装置时，能够显著改善电化学装置的循环性能。
在第一方面，本申请提供的负极活性材料包括硅氧颗粒和位于硅氧颗粒表面的硅氧碳层，其中，硅氧碳层包括硅氧碳复合颗粒。本申请的负极活性材料利用表面硅氧碳材料的结构稳定性，有效改善了硅氧材料在循环过程中的界面稳定，进而改善了使用该负极活性材料的电化学装置的容量保持率和膨胀率。
根据本申请的一些实施方式，负极活性材料满足如下条件(a)至(c)中的至少一者：(a)负极活性材料的 29Si MAS NMR谱图在如下范围具有峰：-5ppm±2ppm，-35ppm±2ppm，-75ppm±2ppm；(b)负极活性材料的 29Si MAS NMR谱图在-100ppm±2ppm范围内具有峰；(c)负极活性材料的 29Si MAS NMR谱图在-5ppm±2ppm范围内的峰的半峰宽为20ppm至25ppm。
根据本申请的一些实施方式，负极活性材料的 29Si MAS NMR谱图在如下范围具有峰：-5ppm±2ppm，-35ppm±2ppm，-75ppm±2ppm，-100ppm±2ppm。本申请的负极活性材料的 29Si MAS NMR谱图中在上述范围内具有吸收峰，说明该材料中碳原子、硅原子与氧原子之间相互成键。碳、硅、氧这三种原子键连在一起，有利于提高硅氧碳材料的结构稳定性。
根据本申请的一些实施方式，负极活性材料满足如下条件(d)至(g)中的至少一者：(d)硅氧碳层的厚度为d，其中10nm≤d≤2000nm；(e)硅氧碳层包括非晶相结构的硅氧碳复合颗粒；(f)硅氧碳复合颗粒的粒径为1nm至60nm；(g)硅氧碳复合颗粒中至少70％的硅氧碳复合颗粒的粒径为20nm至46nm。
根据本申请的一些实施方式，硅氧碳层的厚度d满足10nm≤d≤2000nm。当硅氧碳层的厚度较小时，硅氧碳层无法实现界面的有效保护，进而导致电化学装置的容量保持率降低和膨胀率上升。当硅氧碳层的厚度较大时，虽然能够提高电化学装置的容量保持率和降低膨胀率，但是会损失较多的活性储锂位点，导致电化学装置能量密度的损失。
根据本申请的一些实施方式，硅氧碳层包括非晶相结构的硅氧碳复合颗粒。非晶相结构的硅氧碳复合颗粒中元素分布均匀，硅晶粒均匀的分散在Si-O-C骨架中，使得硅氧碳材料保持最稳定的结构，从而实现对硅氧材料界面的良好保护。
根据本申请的一些实施方式，硅氧碳复合颗粒的粒径为1nm至60nm。 在一些实施方式中，硅氧碳复合颗粒中至少70％的硅氧碳复合颗粒的粒径为20nm至46nm。硅氧碳复合颗粒的粒径过小时，负极活性材料的电导性差，进而使得材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。硅氧碳复合颗粒的粒径过大时，负极活性材料的离子传输变差，负极活性材料的利用率降低，进而使得材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。
根据本申请的一些实施方式，硅氧碳层的厚度d与硅氧颗粒的Dv50满足：0.0015≤d/Dv50≤0.8。根据本申请的一些实施方式，硅氧颗粒的Dv50的范围为2.5μm至10μm。硅氧颗粒的粒径过小时，硅氧颗粒之间会发生粘连，负极活性材料在嵌锂过程中应力分布不均匀，进而导致电化学装置的容量保持率降低和膨胀率上升。硅氧颗粒的粒径过大时，硅氧碳层的厚度相对较小，使得硅氧碳层受到的应力变大，硅氧碳层无法实现界面的有效保护，进而导致电化学装置的容量保持率降低和膨胀率上升。
根据本申请的一些实施方式，硅氧颗粒为SiO x，x满足0.5≤x≤1.5。在一些实施方式中，硅氧颗粒包括Si、SiO和SiO 2中的至少两种。在一些实施方式中，硅氧颗粒为SiO。
根据本申请的一些实施方式，负极活性材料满足如下条件(h)至(j)中的至少一者：(h)基于负极活性材料的质量，碳元素的含量为a％，其中0.9≤a≤11；(i)基于负极活性材料的质量，硅元素的含量为b％，其中50≤b≤63；(j)基于负极活性材料的质量，碳元素的含量为a％，硅元素的含量为b％，其中0.015≤a/b≤0.25。根据本申请的一些实施方式，基于负极活性材料的质量，碳元素的含量a％满足0.9≤a≤11。根据本申请的一些实施方式，基于负极活性材料的质量，硅元素的含量b％满足50≤b≤63。根据本申请的一些实施方式，基于负极活性材料的质量，碳元素的含量a％与硅元素的含量b％满足0.015≤a/b≤0.25。
根据本申请的一些实施方式，负极活性材料满足如下条件(e)至(h)中的至少一者：(k)负极活性材料的X射线衍射图案中2θ归属于28.0°至29.0°范围内最高强度数值为I2，归属于20.5°至21.5°范围内最高强度数值为I1，其中0<I2/I1≤1；(l)负极活性材料的比表面积为1m 2/g至50m 2/g；(m)负极活性材料的粉末电导率为2.0S/cm至30S/cm；(n)负极活性材料还包括石墨。根据本申请的一些实施方式，负极活性材料还包括石墨，石墨的加入可以提高负极活性材料的克容量。在一些实施方式中，石墨包括天然石墨、人造石墨或中间相碳微球中的至少一种。
根据本申请的一些实施方式，该负极活性材料的制备方法包括以下步骤：对包含硅氧化物、硅源、碳源和有机溶剂的溶液进行热处理，得到热处理后的粉末；对所述热处理后的粉末进行焙烧处理；其中，热处理的温度为80℃至120℃；和/或焙烧处理包括在600℃至1200℃的焙烧温度下进行焙烧。在一些实施方式中，焙烧处理包括以3℃/min至10℃/min的升温速率升温至600℃至1200℃进行焙烧。在一些实施方式中，焙烧处理包括以3℃/min至10℃/min的升温速率升温至800℃至1200℃进行焙烧。
根据本申请的一些实施方式，热处理的温度为80℃至120℃。热处理的温度过高时，硅氧化物、硅源以及碳源的交联温度过高，在交联过程中的收缩应力均匀性变差，进而使得材料的缺陷增加，导致得到的负极活性材料的克容量降低，硅氧碳层变薄。
根据本申请的一些实施方式，焙烧温度为600℃至1200℃。焙烧温度过高时，材料的晶粒变大，甚至出现结晶峰，导致负极活性材料的离子传输变差，克容量降低，进而影响电化学装置的循环保持率和膨胀率。
根据本申请的一些实施方式，升温速率为3℃/min至10℃/min。升温速率降低时，晶体成核较小，导致负极活性材料的电导性变差，进而使得负极活性材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。升温 速率升高时，晶体颗粒变大，导致负极活性材料的离子传输变差，负极活性材料的利用率降低，电化学装置的循环保持率降低，膨胀率升高。
在第二方面，本申请提供一种电化学装置，其包括负极，负极包括第一方面的负极活性材料。根据本申请的一些实施方式，负极的膜片电阻为0.2Ω至1Ω。
在第三方面，本申请提供一种电子装置，其包括本申请第二方面所述的电化学装置。
本申请提供了一种负极活性材料，该负极活性材料利用表面硅氧碳材料的结构稳定性，有效改善了硅氧材料在循环过程中的界面稳定，进而改善了使用该负极活性材料的电化学装置的容量保持率和膨胀率。
附图说明
图1为本申请的一些实施方式的负极活性材料的结构示意图，其中1代表SiO x，2代表硅氧碳层。
图2为实施例1的负极活性材料的SEM图。
图3为实施例1的负极活性材料的SEM图。
图4为实施例1的负极活性材料的EDS图。
图5为实施例1的负极活性材料的NMR图。
图6为实施例1的负极活性材料的XRD图。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合实施例对本申请的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一 部分实施例，而不是全部的实施例。在此所描述的有关实施例为说明性质的且用于提供对本申请的基本理解。本申请的实施例不应该被解释为对本申请的限制。
为了简明，本文仅具体地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，除非另有说明，“以上”、“以下”包含本数。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组分或多个组分。项目B可包含单个组分或多个组分。项目C可包含单个组分或多个组分。
一、负极活性材料
本申请提供的负极活性材料包括硅氧颗粒和位于硅氧颗粒表面的硅氧碳层，其中，硅氧碳层包括硅氧碳复合颗粒。本申请的负极活性材料利用表面 硅氧碳材料的结构稳定性，有效改善了硅氧材料在循环过程中的界面稳定，进而改善了使用该负极活性材料的电化学装置的容量保持率和膨胀率。
根据本申请的一些实施方式，负极活性材料的 29Si MAS NMR谱图在如下范围具有峰：-5ppm±2ppm，-35ppm±2ppm，-75ppm±2ppm。根据本申请的一些实施方式，负极活性材料的 29Si MAS NMR谱图在-100ppm±2ppm范围内具有峰。本申请的负极活性材料的 29Si MAS NMR谱图中在上述范围内具有吸收峰，说明该材料中碳原子、硅原子与氧原子之间相互成键。碳硅氧三原子关联在一起，有利于提高硅氧碳材料的结构稳定性。
根据本申请的一些实施方式，负极活性材料的 29Si MAS NMR谱图在-5ppm±2ppm范围内的峰的半峰宽为20ppm至25ppm，例如21ppm、22ppm、23ppm、24ppm或这些值中任意两者组成的范围。
本申请中， 29Si MAS NMR谱图中，化学位移-5ppm±2ppm处的吸收峰归属于SiOC 3基团中的硅。化学位移-35ppm±2ppm处的吸收峰归属于SiO 2C 2基团中的硅。化学位移-75ppm±2ppm处的吸收峰归属于SiO 3C基团中的硅。化学位移-100ppm处的吸收峰归属于硅氧四面体(SiO 4基团)中与氧结合的四配位硅。
根据本申请的一些实施方式，硅氧碳层的厚度为d，其中10nm≤d≤2000nm。在一些实施方式中，d为20nm、40nm、60nm、80nm、90nm、120nm、150nm、200nm、300nm、500nm、700nm、900nm、1000nm、1200nm、1500nm、1700nm、1900nm或这些值中任意两者组成的范围。在一些实施方式中，50nm≤d≤500nm。当硅氧碳层的厚度较小时，硅氧碳包覆层无法实现界面的有效保护，进而导致电化学装置的容量保持率降低和膨胀率上升。当硅氧碳层的厚度较大时，虽然能够提高电化学装置的容量保持率和降低膨胀率，但是会损失较多的活性储锂位点，导致电化学装置能量密度的损失。
根据本申请的一些实施方式，硅氧碳层包括非晶相结构的硅氧碳复合颗粒。非晶相结构的硅氧碳复合颗粒中元素分布均匀，硅晶粒均匀的分散在Si-O-C骨架中，使得硅氧碳材料保持最稳定的结构，从而实现对硅氧材料界面的良好保护。
根据本申请的一些实施方式，硅氧碳复合颗粒的粒径为1nm至60nm。在一些实施方式中，硅氧碳复合颗粒的粒径为5nm至55nm、5nm至50nm、10nm至55nm、10nm至50nm、10nm至48nm、15nm至55nm、15nm至50nm、15nm至48nm、20nm至50nm、20nm至48nm、25nm至50nm、25nm至48nm、30nm至55nm或40nm至55nm等。在一些实施方式中，硅氧碳复合颗粒中至少70％，例如75％、80％、85％、90％、95％的硅氧碳复合颗粒的粒径为15nm至55nm。在一些实施方式中，硅氧碳复合颗粒中至少70％，例如75％、80％、85％、90％、95％的硅氧碳复合颗粒的粒径为20nm至50nm。在一些实施方式中，硅氧碳复合颗粒中至少70％，例如75％、80％、85％、90％、95％的硅氧碳复合颗粒的粒径为20nm至46nm。硅氧碳复合颗粒的粒径过小时，负极活性材料的电导性差，进而使得材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。硅氧碳复合颗粒的粒径过大时，负极活性材料的离子传输变差，负极活性材料的利用率降低，进而使得材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。
根据本申请的一些实施方式，硅氧碳层的厚度d与硅氧颗粒的Dv50满足：0.0015≤d/Dv50≤0.8。在一些实施方式中，d/Dv50为0.002、0.005、0.01、0.015、0.02、0.03、0.05、0.09、0.15、0.3、0.4、0.45、0.55、0.7或这些值中任意两者组成的范围。在一些实施方式中，0.002≤d/Dv50≤0.5。根据本申请的一些实施方式，硅氧颗粒的Dv50的范围为2.5μm至10μm。在一些实施方式中，Dv50为2.5μm、3.0μm、4.0μm、4.5μm、5.5μm、6.0μm、7.0μm、8.0μm或这些值中任意两者组成的范围。本申请中，Dv50为颗粒累计体积百分数达 到50％时所对应的粒径。硅氧颗粒的粒径过小时，硅氧颗粒之间会发生粘连，负极活性材料在嵌锂过程中应力分布不均匀，进而导致电化学装置的容量保持率降低和膨胀率上升。硅氧颗粒的粒径过大时，硅氧碳层的厚度相对较小，使得硅氧碳层受到的应力变大，硅氧碳层无法实现界面的有效保护，进而导致电化学装置的容量保持率降低和膨胀率上升。
根据本申请的一些实施方式，硅氧颗粒为SiO x，x满足0.5≤x≤1.5。在一些实施方式中，硅氧颗粒包括Si、SiO和SiO 2中的至少两种。在一些实施方式中，硅氧颗粒为SiO。
根据本申请的一些实施方式，基于负极活性材料的质量，碳元素的含量为a％，其中0.9≤a≤11。在一些实施方式中，a为0.95、1.5、2、3、4、5、6、7、8、9、10.5或这些值中任意两者组成的范围。在一些实施方式中，1≤a≤10。
根据本申请的一些实施方式，基于负极活性材料的质量，硅元素的含量为b％，其中50≤b≤63。在一些实施方式中，b为52、54、57、59、62或这些值中任意两者组成的范围。在一些实施方式中，55≤b≤63。
根据本申请的一些实施方式，基于负极活性材料的质量，碳元素的含量为a％、硅元素的含量为b％，其中0.015≤a/b≤0.25。在一些实施方式中，a/b为0.018、0.025、0.035、0.05、0.07、0.10、0.13、0.15、0.17、0.19、0.23或这些值中任意两者组成的范围。在一些实施方式中，0.015≤a/b≤0.20。在一些实施方式中，0.015≤a/b≤0.10。
根据本申请的一些实施方式，负极活性材料的X射线衍射图案中2θ归属于28.0°至29.0°范围内最高强度数值为I2，归属于20.5°至21.5°范围内最高强度数值为I1，其中0<I2/I1≤1。根据本申请的一些实施方式，负极活性材料的比表面积为1m 2/g至50m 2/g。在一些实施方式中，负极活性材料的比表面积为1m 2/g、10m 2/g、20m 2/g、30m 2/g、40m 2/g、45m 2/g或这些值中任意两者组成的范围。根据本申请的一些实施方式，负极活性材料的粉末电导率 为2.0S/cm至30S/cm。在一些实施方式中，负极活性材料的粉末电导率为3.0S/cm、5.0S/cm、7.0S/cm、10S/cm、15S/cm、20S/cm、25S/cm或这些值中任意两者组成的范围。
根据本申请的一些实施方式，负极活性材料还包括石墨，石墨的加入可以提高负极活性材料的克容量。在一些实施方式中，石墨包括天然石墨、人造石墨或中间相碳微球中的至少一种。
二、负极活性材料制备方法
本申请的负极活性材料的制备方法包括对包含硅氧化物、硅源、碳源和有机溶剂的溶液进行热处理，得到热处理后的粉末；对所述热处理后的粉末进行焙烧处理；其中，热处理的温度为80℃至120℃；和/或焙烧处理包括在600℃至1200℃的焙烧温度下进行焙烧。在一些实施方式中，焙烧处理包括以3℃/min至10℃/min的升温速率升温至600℃至1200℃进行焙烧。在一些实施方式中，焙烧处理包括以3℃/min至10℃/min的升温速率升温至800℃至1200℃进行焙烧。
根据本申请的一些实施方式，热处理的温度为80℃至120℃。热处理的温度过高时，硅氧化物、硅源以及碳源的交联温度过高，在交联过程中的收缩应力均匀性变差，进而使得材料的缺陷增加，导致得到的负极活性材料的克容量降低，硅氧碳层变薄。在一些实施方式中，热处理的温度为85℃、90℃、95℃、105℃、110℃、115℃或这些值中任意两者组成的范围。
根据本申请的一些实施方式，焙烧温度为600℃至1200℃。在一些实施方式中，焙烧温度为800℃至1200℃。焙烧温度过高时，材料的晶粒变大，甚至出现结晶峰，导致负极活性材料的离子传输变差，克容量降低，进而影响电化学装置的循环保持率和膨胀率。在一些实施方式中，焙烧温度为650℃、700℃、750℃、850℃、950℃、1050℃、1150℃或这些值中任意两者组成的范围。
根据本申请的一些实施方式，升温速率为3℃/min至10℃/min。升温速率降低时，晶体成核较小，导致负极活性材料的电导性变差，进而使得负极活性材料的克容量降低，电化学装置的循环保持率降低，膨胀率升高。升温速率升高时，晶体颗粒变大，导致负极活性材料的离子传输变差，负极活性材料的利用率降低，电化学装置的循环保持率降低，膨胀率升高。在一些实施方式中，升温速率为4℃/min、6℃/min、7℃/min、8℃/min、9℃/min或这些值中任意两者组成的范围。
根据本申请的一些实施方式，硅氧化物为SiO x，x满足0.5≤x≤1.5。在一些实施方式中，硅氧化物包括Si、SiO和SiO 2中的至少两种。在一些实施方式中，硅氧化物为SiO。
根据本申请的一些实施方式，硅源包括四甲基-四乙烯基-环四硅氧烷或聚甲基氢硅氧烷中的至少一种。根据本申请的一些实施方式，碳源包括四甲基-四乙烯基-环四硅氧烷或聚甲基氢硅氧烷中的至少一种。根据本申请的一些实施方式，有机溶剂包括甲醇、乙醇、正己烷、N,N-二甲基甲酰胺、吡咯烷酮、丙酮、甲苯、异丙醇或正丙醇中的至少一种。
三、电化学装置
本申请提供的电化学装置包括负极，该负极包括第一方面的负极活性材料。根据本申请的一些实施方式，负极的膜片电阻为0.2Ω至1Ω。
根据本申请的一些实施方式，负极包括负极集流体和设置于所述负极集流体表面上的负极活性材料层，该负极活性材料层包括第一方面的负极活性材料。在一些实施例中，负极活性材料层还包含有粘合剂，且该粘合剂可以包括各种粘合剂聚合物。在一些实施方式中，粘结剂包括聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酯、聚丙烯酸、聚丙烯酸盐、羧甲基纤维素钠、聚乙烯吡咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、 聚四氟乙烯、聚六氟丙烯或丁苯橡胶中的至少一种。在一些实施例中，负极活性材料层还包括导电材料来改善电极导电率。可以使用任何导电的材料作为该导电材料，只要它不引起化学变化即可。在一些实施方式中，导电材料包括导电炭黑、乙炔黑、碳纳米管、科琴黑、导电石墨或石墨烯中的至少一种。
根据本申请的一些实施方式，负极集流体可以为铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、包覆有导电金属的聚合物基板或它们的组合。
根据本申请的一些实施方式，该电化学装置还包括正极，正极包括集流体和位于该集流体上的正极活性材料层。
根据本申请的一些实施方式，正极活性材料包括，但不限于：钴酸锂(LiCoO 2)、锂镍钴锰(NCM)三元材料、磷酸亚铁锂(LiFePO 4)或锰酸锂(LiMn 2O 4)。
根据本申请的一些实施方式，正极活性材料层还包括导电剂和粘结剂。在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。在一些实施例中，导电剂包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝或银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
根据本申请的一些实施方式，正极集流体可以采用金属箔片或复合集流体。例如，可以使用铝箔。复合集流体可以通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子基材上而形成。
本申请的正极可以采用本领域的公知方法进行制备。通常，将正极材料以及可选的导电剂(例如碳黑等碳素材料和金属颗粒等)、粘结剂(例如SBR)、其他可选添加剂(例如PTC热敏电阻材料)等材料混合在一起分散于溶剂(例如去离子水)中，搅拌均匀后均匀涂覆在正极集流体上，烘干后即得到含有正极膜片的正极。
根据本申请的一些实施方式，该电化学装置还包括电解液或固态电解质。
根据本申请的一些实施方式，可用于本申请实施例的电解液可以为现有技术中已知的电解液。
在一些实施例中，所述电解液包括有机溶剂、锂盐和添加剂。根据本申请的电解液的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中使用的电解质没有限制，其可为现有技术中已知的任何电解质。根据本申请的电解液的添加剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。在一些实施例中，所述有机溶剂包括，但不限于：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯。在一些实施例中，有机溶剂包括醚类溶剂，例如包括1，3-二氧五环(DOL)和乙二醇二甲醚(DME)中的至少一种。在一些实施例中，所述锂盐包括有机锂盐或无机锂盐中的至少一种。在一些实施例中，所述锂盐包括，但不限于：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。
根据本申请的一些实施方式，所述固态电解质包括Li 2+xAl 2+xSi 1-xS 6(0≤x<1)、Li 3YCl 6，Li 3YBr 6，Li 3OCl，LiPON，Li 0.5La 0.5TiO 3、 Li 1+xAl xTi 2-x(PO 4) 3、Li 7La 3Zr 2O 12、Li 10GeP 2S 12(LGPS)、Li 9.54Si 1.74P 1.44S 11.7Cl 0.3、Li 3.25Ge 0.25P 0.75S 4、Li 11AlP 2S 12和Li 7P 3S 11中的至少一种。
根据本申请的一些实施方式，该电化学装置中，正极与负极之间设有隔离膜以防止短路。本申请的实施例中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。例如，隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。具体地，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。无机物层包括无机颗粒和粘结剂，无机颗粒包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。粘结剂包括聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
根据本申请的一些实施方式，本申请的电化学装置包括，但不限于：所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容。在一些实施例中，所述电化学装置是锂二次电池。在一些实施例中，锂二次电池包括，但不限于：锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
四、电子装置
本申请的电子装置可为任何使用根据本申请第三方面所述的电化学装置的装置。
在一些实施例中，所述电子装置包括，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。
实施例及对比例
一、SiO x@硅氧碳材料的制备
步骤1.将有机硅(聚硅氧烷等)按一定比例加入有机溶剂中，搅拌0.5h至4h。将SiO x(0.5≤x≤1.5)材料完全浸渍于有机硅溶液中，随后80℃搅拌加热去除溶剂，再将产物放入80℃至120℃烘箱干燥24h。
步骤2.将步骤1中得到的干燥产物放入管式炉中高温裂解，以N 2或者Ar为保护气氛，升温程序：以3℃/min至10℃/min升温至800℃至1200℃保持3h，高温裂解得到SiO x@硅氧碳材料。
二、锂离子电池的制备
将SiO x@硅氧碳材料与石墨按按4:6的重量比混合，得到混合粉末。将混合粉末、导电剂乙炔黑、PAA按照重量比95：1.2：3.8在去离子水溶剂体系中充分搅拌混合均匀后，涂覆于Cu箔上，烘干、冷压，得到负极极片。将LiCoO 2、导电炭黑和聚偏二氟乙烯(PVDF)按照约95:2.5:2.5的重量比在N-甲基吡咯烷酮溶剂体系中充分搅拌混合均匀，制得正极浆料。将制得的正极浆料涂布在正极集流体铝箔上，烘干，冷压，得到正极极片。以PE多 孔聚合薄膜作为隔离膜。将正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到电极组件。将电极组件置于外包装中，注入配好的电解液(EC:DEC＝4:6+1.2M LiPF 6)后进行封装，经过化成，脱气，切边等工艺流程得到锂离子电池。
实施例1
步骤1.配制聚硅氧烷前驱体溶液(四甲基-四乙烯基-环四硅氧烷:聚甲基氢硅氧烷:乙醇＝50g:50g:400g)，搅拌30min，混合均匀；
步骤2.加入630g SiO(Dv50为5.6μm)于步骤1的前驱体溶液中，搅拌30min后，80℃下加热处理，得到干燥粉末；
步骤3.对步骤2得到的干燥粉末进行焙烧处理，5℃/min升温至800℃保持3h，便可得到SiO x@硅氧碳材料。
步骤4.锂离子电池的制备方法同制备过程二中的描述。
SiO x@硅氧碳材料中，硅氧碳层厚度为100nm。以SiO x@硅氧碳材料质量计，碳元素的含量为1.77％，硅元素的含量为60.0％，碳和硅含量的比例为0.0295。硅氧碳包覆层厚度与SiO的Dv50的比例为0.017。
SiO x@硅氧碳材料中Si2 p的XPS结合能峰位有101.4±0.3eV、102.2±0.3eV、103.1±0.3eV、104.40±0.3e。
如图2所示，在SiO x@硅氧碳材料的SEM图中，硅氧碳与SiO x的界面相互交联，界面处有暗色硅氧碳层。
如图3所示，在SiO x@硅氧碳材料的颗粒表面，可以观察到粒径为28nm-46nm的硅氧碳复合颗粒。
如图4所示，在SiO x@硅氧碳材料的EDS图中，可以在颗粒内部观察到Si和O元素，在颗粒边缘，可以看到C元素。
如图5所示，SiO x@硅氧碳材料的固体核磁(sNMR)测试中硅的位移包括-5ppm，-35ppm，-75ppm，-110ppm。
SiO x@硅氧碳材料的粉末克容量为1430mAh/g。锂离子电池循环500圈后，容量保持率为90.1％，膨胀率为10％。
实施例2至实施例4
SiO x@硅氧碳材料的制备及锂离子电池的制作过程参考实施例1，不同之处在于实施例2至实施例4中，步骤2中加入的SiO的质量不同，具体参见表1。
实施例5至实施例12
SiO x@硅氧碳材料的制备及锂离子电池的制作过程参考实施例1，不同之处在于实施例5至实施例12中，步骤2和步骤3中的加热温度，焙烧处理时的焙烧的温度以及升温速率不同，具体参见表2。
实施例13至实施例14
SiO x@硅氧碳材料的制备及锂离子电池的制作过程参考实施例1，不同之处在于实施例13至实施例14中，SiO的Dv50不同，具体参见表3。
对比例1
步骤1.对630g SiO(Dv50为5.6μm)粉末进行焙烧处理，5℃/min升温至800℃保持3h，便可得到SiO x材料。
步骤2.制备锂离子电池的方法同制备过程二中的描述。
SiO x材料的粉末克容量为1527mAh/g，锂离子电池循环500圈后，容量保持率为65.2％，膨胀率为19％。
对比例2
步骤1.配制聚硅氧烷前驱体溶液(四甲基-四乙烯基-环四硅氧烷:聚甲基 氢硅氧烷:乙醇＝50g:50g:400g)，搅拌30min，混合均匀；
步骤2.加入630g SiO(Dv50为5.6μm)于步骤1的前驱体溶液中，搅拌30min后，80℃下加热处理，得到干燥粉末；
步骤3.对步骤2得到的干燥粉末进行焙烧处理，5℃/min升温至1400℃保持3h，便可得到SiO x@硅氧碳材料。
步骤4.制备锂离子电池的方法同制备过程二中的描述。
SiO x@硅氧碳材料中，硅氧碳层厚度为110nm。以SiO x@硅氧碳材料质量计，碳元素的含量为1.23％，硅元素的含量为52.1％，碳和硅含量的比例为0.0236。硅氧碳层厚度与SiO x的Dv50的比例为0.01964。
SiO x@硅氧碳材料粉末的克容量为231mAh/g，锂离子电池循环500圈后，容量保持率为65.2％，膨胀率为18％。由于焙烧温度达到了1400℃，SiO x@硅氧碳材料在合成过程中生成了SiC，因而其电化学活性大大降低，导致粉末克容量大大降低，进而使得锂离子电池的循环性能和膨胀性能也急剧恶化。
对比例3
1.配制聚硅氧烷前驱体溶液(四甲基-四乙烯基-环四硅氧烷:聚甲基氢硅氧烷:乙醇＝50g:50g:400g)，搅拌30min，混合均匀；
2.加入630g SiO(Dv50为5.6μm)于步骤1的前驱体溶液中，搅拌30min后，200℃下加热处理，得到干燥粉末；
3.对步骤2得到的干燥粉末进行焙烧处理，5℃/min升温至1400℃保持3h，便可得到SiO x@硅氧碳材料。
4.制备锂离子电池的方法同制备过程二中的描述。
SiO x@硅氧碳材料中没有硅氧碳层。SiO x@硅氧碳材料的粉末克容量为1521mAh/g，锂离子电池循环500圈后，容量保持率为65.2％，膨胀率为18％。由于加热温度过高，导致硅氧碳前驱体挥发，因而没有硅氧碳层存在。
测试方法
SEM测试：
(1)制备负极离子研磨(CP，Cross Section Polisher)样品：将负极活性材料粉末固定于样品台上，然后使用氩离子抛光(参数：8KV的加速电压，每个样品4h)进行处理，得到负极活性材料CP样品；
(2)负极活性材料CP样品制备完成后，利用扫描式电子显微镜(PhilipsXL-30型场发射扫描电子显微镜)在10kV，10mA条件下拍摄负极活性材料CP样品的SEM照片，分析该SEM照片得到活性材料表面硅氧碳包覆层的厚度以及表面的细小颗粒(即硅氧碳复合颗粒)的粒径。
29Si MAS NMR测试：采用AVANCE III 400WB宽腔固体核磁共振仪进行测试，其中旋转速率为8kHz。
碳含量测试：样品在富氧条件下由高频炉高温加热燃烧使碳和硫分别氧化成二氧化碳和二氧化硫，该气体经处理后进入相应的吸收池，对相应的红外辐射进行吸收再由探测器转化成对应的信号。此信号由计算机采样，经线性校正后转换成与二氧化碳、二氧化硫浓度成正比的数值，然后把整个分析过程的取值累加，分析结束后，此累加值在计算机中除以重量值，再乘以校正系数，扣除空白，即可获得样品中碳、硫百分含量。利用高频红外碳硫分析仪(上海徳凯HCS-140)进行样品测试。
硅含量测试：称取活性材料粉末0.5g，将粉末与10mL HNO 3溶液混合，采用微波消解的方式将粉末中的微量元素溶于溶液中，消解后的溶液引入ICP(电感耦合光电子)光源中，电感耦合等离子体发射光谱仪(ICP-OES)设备根据试样物质中气态原子被激发后其外层电子由激发态返回到基态时，辐射跃迁所发射的特征辐射能来检测不同物质含量。
粒度测试：50mL洁净烧杯中加入约0.02g粉末样品，加入约20mL去离子水，再滴加几滴1％的表面活性剂，使粉末完全分散于水中，120W超声清 洗机中超声5分钟，利用MasterSizer 2000测试粒度分布。
X射线衍射(XRD)测试：采用X射线粉末衍射仪(XRD，仪器型号:Bruker D8 ADVANCE)测试负极活性材料，靶材为Cu Kα；电压电流为40KV/40mA，扫描角度范围为5°至80°，扫描步长为0.00836°，每步长时间为0.3s。
负极活性材料克容量测试：干燥氩气环境下，在碳酸丙烯酯(PC)，碳酸乙烯酯(EC)，碳酸二乙酯(DEC)(重量比约1：1：1)混合而成的溶剂中，加入LiPF 6，混合均匀，其中LiPF 6的含量为约12％，再加入约7.5％的氟代碳酸乙烯酯(FEC)后，混合均匀得到电解液。
将负极活性材料、导电炭黑与粘结剂PAA(改性聚丙烯酸，PAA)按照重量比约80：10：10加入去离子水中，搅拌形成浆料，利用刮刀涂覆形成厚度为约100μm的涂层，在真空干燥箱中在约85℃烘干约12小时，在干燥环境中用冲压机切成直径为约1cm的圆片，在手套箱中以金属锂片作为对电极，隔离膜选择ceglard复合膜，加入上述电解液组装成扣式电池。用蓝电(LAND)系列电池测试系统对电池进行充放电测试。
具体地，取装配好的扣式电池，确保开路电压(OCV)正常，每组至少包含4个平行样。扣式电池的电压窗口设定在0V至2.5V。在25℃先静置1h，再以0.05C/50μA/20μA三阶段小电流对电池进行放电，实现SEI(固体电解质界面膜)成膜并记录嵌锂容量。随后以0.1C电流将电池充电至2.5V，记录脱锂容量，该脱锂容量即负极活性材料的克容量。
循环测试：测试温度为25℃，以0.5C恒流充电到4.45V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V。以此步得到的容量为初始容量，进行0.5C充电/0.5C放电进行循环测试，以每一步的容量与初始容量做比值，得到容量衰减曲线。其中，第n圈容量保留率＝第n圈放电容量/初始容量×100％。
锂离子电池的满充膨胀率测试：测试温度为25℃，以0.5C恒流充电到 4.45V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V。用螺旋千分尺测试初始半充时锂离子电池的厚度，计为h 0。循环至500次时，锂离子电池于满充状态下，再用螺旋千分尺测试此时锂离子电池的厚度，计为h，
Figure PCTCN2021128701-appb-000001
测试结果
表1示出了SiO的加入量对负极活性材料以及包含所述负极活性材料的锂离子电池的性能影响。
其中，对比例1、实施例1至实施例4的负极活性材料在制备过程中加热处理的温度为80℃，焙烧处理的升温速率为5℃/min，温度为800℃，焙烧时间为3h；SiO的Dv50均为5.6μm。
表1
Figure PCTCN2021128701-appb-000002
注：表中碳硅氧复合颗粒的粒径为至少70％以上的碳硅氧复合颗粒对应的粒径
从表1中的数据可以看出，加入的SiO量较多时，硅氧碳的相对含量就会较少，相应的硅氧碳层的厚度会降低，SiO x@硅氧碳材料克容量轻微上升，硅氧碳纳米颗粒会更小。但是硅氧碳层的厚度较小时，硅氧碳层无法实现界面的有效保护，进而导致电化学装置的容量保持率降低和膨胀率的上升。加入的SiO较少时，硅氧碳的相对含量较多，对应的硅氧碳层的厚度升高，SiO x@硅氧碳材料克容量降低。当硅氧碳包覆层的厚度较大时，虽然能够提高锂离子电池的容量保持率和降低膨胀率，但是会损失较多的活性储锂位点，导致锂离子电池能量密度的损失。
表2示出了步骤2和步骤3中加热温度、焙烧处理时的焙烧的温度以及升温速率对得到的负极活性材料以及包含负极活性材料的锂离子电池的性能影响。
其中，实施例5至实施例12、对比例2至对比例3中SiO加入量均为630g，SiO的Dv50均为5.6μm。实施例5至实施例12中SiO x@硅氧碳材料的固体核磁-5ppm处的半峰宽均为20ppm，对比例2的SiO x@硅氧碳材料的固体核磁-5ppm处的半峰宽为25ppm。
表2
Figure PCTCN2021128701-appb-000003
Figure PCTCN2021128701-appb-000004
注：表中碳硅氧复合颗粒的粒径为至少70％以上的碳硅氧复合颗粒对应的粒径
从表2中的数据可以看出，热处理的温度过高时，硅氧化物、硅源以及碳源的交联温度过高，在交联过程中的材料收缩应力均匀性变差，进而使得SiO x@硅氧碳材料的缺陷增加，导致其克容量降低。同时硅氧碳层变薄，碳含量相应减少，硅氧碳纳米颗粒尺寸变小，使得锂离子电池的容量保持率降低和膨胀率上升。
升温速度降低时，晶体成核较小，导致SiO x@硅氧碳材料的电导性变差，进而使得材料的克容量降低，锂离子电池的循环保持率降低，膨胀率上升。升温速度过高时，晶体颗粒变大，导致SiO x@硅氧碳材料的离子传输变差，活性物质利用率将低，导致材料的克容量降低，锂离子电池的循环保持率降低，膨胀率上升。
焙烧温度过高时，SiO x@硅氧碳材料的晶粒变大，甚至出现结晶峰，导致材料的离子传输变差，惰性硅酸盐增多，克容量降低，锂离子电池的循环保持率降低，膨胀率上升。
表3示出了SiO的Dv50值对负极活性材料以及包含所述负极活性材料 的锂离子电池的性能影响。
其中，实施例1、实施例13至实施例14的SiO加入量均为630g；负极活性材料在制备过程中加热处理的温度为80℃，焙烧处理的升温速率为5℃/min，温度为800℃，焙烧时间为3h。
表3
Figure PCTCN2021128701-appb-000005
注：表中碳硅氧复合颗粒的粒径为至少70％以上的碳硅氧复合颗粒对应的粒径
从表3中可以看出：硅氧颗粒的粒径过小时，硅氧颗粒之间会发生粘连，负极活性材料在嵌锂过程中应力分布不均匀，会影响电化学装置的容量保持率和膨胀率。硅氧颗粒的粒径过大时，硅氧碳层的厚度相对较小，使得硅氧碳层受到的应力变大，硅氧碳层无法实现界面的有效保护，同样会影响电化学装置的容量保持率和膨胀率。
虽然已经说明和描述了本申请的一些示例性实施方式，然而本申请不限于所公开的实施方式。相反，本领域普通技术人员将认识到，在不脱离如所附权利要求中描述的本申请的精神和范围的情况下，可对所描述的实施方式进行一些修饰和改变。

Claims (11)

  1. 一种负极活性材料，包括硅氧颗粒和位于所述硅氧颗粒表面的硅氧碳层，其中，所述硅氧碳层包括硅氧碳复合颗粒。
  2. 根据权利要求1所述的负极活性材料，其中，所述负极活性材料满足如下条件(a)至(c)中的至少一者：
    (a)所述负极活性材料的 29Si MAS NMR谱图在如下范围具有峰：-5ppm±2ppm，-35ppm±2ppm，-75ppm±2ppm；
    (b)所述负极活性材料的 29Si MAS NMR谱图在-100ppm±2ppm范围内具有峰；
    (c)所述负极活性材料的 29Si MAS NMR谱图在-5ppm±2ppm范围内的峰的半峰宽为20ppm至25ppm。
  3. 根据权利要求1所述的负极活性材料，其中，所述负极活性材料满足如下条件(d)至(g)中的至少一者：
    (d)所述硅氧碳层的厚度为d，其中10nm≤d≤2000nm；
    (e)所述硅氧碳层包括非晶相结构的硅氧碳复合颗粒；
    (f)所述硅氧碳复合颗粒的粒径为1nm至60nm；
    (g)所述硅氧碳复合颗粒中至少70％的硅氧碳复合颗粒的粒径为20nm至46nm。
  4. 根据权利要求1所述的负极活性材料，其中，所述硅氧碳层的厚度d与所述硅氧颗粒的Dv50满足：0.002≤d/Dv50≤0.8。
  5. 根据权利要求1所述的负极活性材料，其中，所述硅氧颗粒的Dv50的范围为2.5μm至10μm；和/或所述硅氧颗粒为SiO x，x满足0.5≤x≤1.5。
  6. 根据权利要求1所述的负极活性材料，其中，所述负极活性材料满足如下条件(h)至(j)中的至少一者：
    (h)基于所述负极活性材料的质量，所述碳元素的含量为a％，其中 0.9≤a≤11；
    (i)基于所述负极活性材料的质量，所述硅元素的含量为b％，其中50≤b≤63；
    (j)基于所述负极活性材料的质量，所述碳元素的含量为a％，所述硅元素的含量为b％，其中0.015≤a/b≤0.25。
  7. 根据权利要求1所述的负极活性材料，其中，所述负极活性材料满足如下条件(k)至(n)中的至少一者：
    (k)所述负极活性材料的X射线衍射图案中2θ归属于28.0°至29.0°范围内最高强度数值为I2，归属于20.5°至21.5°范围内最高强度数值为I1，其中0<I2/I1≤1；
    (l)所述负极活性材料的比表面积为1m 2/g至50m 2/g；
    (m)所述负极活性材料的粉末电导率为2.0S/cm至30S/cm；
    (n)所述负极活性材料还包括石墨。
  8. 根据权利要求1所述的负极活性材料，其中，所述负极活性材料的制备方法包括以下步骤：对包含硅氧化物、硅源、碳源和有机溶剂的溶液进行热处理，得到热处理后的粉末；对所述热处理后的粉末进行焙烧处理；
    其中，所述热处理的温度为80℃至120℃；和/或所述焙烧处理包括在600℃至1200℃的焙烧温度下进行焙烧。
  9. 根据权利要求8所述的负极活性材料，其中，所述焙烧处理包括以3℃/min至10℃/min的升温速率升温至600℃至1200℃进行焙烧。
  10. 一种电化学装置，包括负极，所述负极包括权利要求1至9中任一项所述的负极活性材料。
  11. 一种电子装置，包括权利要求10所述的电化学装置。
PCT/CN2021/128701 2021-11-04 2021-11-04 负极活性材料、电化学装置和电子装置 WO2023077357A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202180016776.0A CN115152057A (zh) 2021-11-04 2021-11-04 负极活性材料、电化学装置和电子装置
PCT/CN2021/128701 WO2023077357A1 (zh) 2021-11-04 2021-11-04 负极活性材料、电化学装置和电子装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2021/128701 WO2023077357A1 (zh) 2021-11-04 2021-11-04 负极活性材料、电化学装置和电子装置

Publications (1)

Publication Number Publication Date
WO2023077357A1 true WO2023077357A1 (zh) 2023-05-11

Family

ID=83405350

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/128701 WO2023077357A1 (zh) 2021-11-04 2021-11-04 负极活性材料、电化学装置和电子装置

Country Status (2)

Country Link
CN (1) CN115152057A (zh)
WO (1) WO2023077357A1 (zh)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1505187A (zh) * 2002-11-26 2004-06-16 信越化学工业株式会社 非水电解质二次电池负极材料，制造方法，和锂离子二次电池
CN1674325A (zh) * 2004-03-26 2005-09-28 信越化学工业株式会社 硅复合颗粒、其制备，和用于非水电解质二次电池的负电极材料
CN1758466A (zh) * 2004-07-30 2006-04-12 信越化学工业株式会社 Si－C－O复合材料、制备方法、及非水电解液蓄电池负电极材料
CN109616654A (zh) * 2018-12-13 2019-04-12 合肥国轩高科动力能源有限公司 一种C/Si/SiOx材料及其制备方法和应用

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1505187A (zh) * 2002-11-26 2004-06-16 信越化学工业株式会社 非水电解质二次电池负极材料，制造方法，和锂离子二次电池
CN1674325A (zh) * 2004-03-26 2005-09-28 信越化学工业株式会社 硅复合颗粒、其制备，和用于非水电解质二次电池的负电极材料
CN1758466A (zh) * 2004-07-30 2006-04-12 信越化学工业株式会社 Si－C－O复合材料、制备方法、及非水电解液蓄电池负电极材料
CN109616654A (zh) * 2018-12-13 2019-04-12 合肥国轩高科动力能源有限公司 一种C/Si/SiOx材料及其制备方法和应用

Also Published As

Publication number Publication date
CN115152057A (zh) 2022-10-04

Similar Documents

Publication Publication Date Title
CN111029543B (zh) 负极材料及包含其的电化学装置和电子装置
CN110797520B (zh) 负极材料及包含其的电化学装置和电子装置
CN114530604A (zh) 负极材料及包含其的电化学装置和电子装置
CN114975980A (zh) 负极材料及使用其的电化学装置和电子装置
CN110911636A (zh) 负极材料及包含其的电化学装置和电子装置
WO2022193123A1 (zh) 负极材料及其制备方法, 电化学装置及电子装置
CN111403693A (zh) 负极活性材料和使用其的负极极片、电化学装置和电子装置
CN110931742B (zh) 负极及包含其的电化学装置和电子装置
WO2022140973A1 (zh) 负极极片、电化学装置和电子装置
CN115425215A (zh) 复合材料及其制备方法、电化学装置及电子装置
WO2023082245A1 (zh) 电极及其制作方法、电化学装置和电子装置
CN111146433A (zh) 负极及包含其的电化学装置和电子装置
CN111146422A (zh) 负极材料及包含其的电化学装置和电子装置
CN110911635A (zh) 负极材料及包含其的电化学装置和电子装置
WO2022193286A1 (zh) 负极材料及其制备方法、电化学装置及电子装置
WO2021102846A1 (zh) 负极及包含其的电化学装置和电子装置
CN113517442B (zh) 负极材料、电化学装置和电子装置
CN116344766A (zh) 一种二次电池和电子装置
US20220158175A1 (en) Anode material, electrochemical device and electronic device including the same
WO2022140964A1 (zh) 一种负极材料、包含该负极材料的极片以及电化学装置
WO2023077357A1 (zh) 负极活性材料、电化学装置和电子装置
CN115956306A (zh) 一种电化学装置和电子装置
EP4060767A1 (en) Negative electrode material, electrochemical device including same, and electronic device
WO2021102847A1 (zh) 负极材料及包含其的电化学装置和电子装置
WO2021102848A1 (zh) 负极材料及包含其的电化学装置和电子装置

Legal Events

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

Ref document number: 21962874

Country of ref document: EP

Kind code of ref document: A1