WO2024086962A1 - Negative pole piece, electrochemical apparatus, and electrical apparatus - Google Patents

Negative pole piece, electrochemical apparatus, and electrical apparatus Download PDF

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Publication number
WO2024086962A1
WO2024086962A1 PCT/CN2022/126942 CN2022126942W WO2024086962A1 WO 2024086962 A1 WO2024086962 A1 WO 2024086962A1 CN 2022126942 W CN2022126942 W CN 2022126942W WO 2024086962 A1 WO2024086962 A1 WO 2024086962A1
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carbon
negative electrode
doped silicon
composite material
oxygen
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PCT/CN2022/126942
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French (fr)
Chinese (zh)
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李鑫
崔航
谢远森
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宁德新能源科技有限公司
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Priority to PCT/CN2022/126942 priority Critical patent/WO2024086962A1/en
Priority to CN202280040768.4A priority patent/CN117480634A/en
Publication of WO2024086962A1 publication Critical patent/WO2024086962A1/en

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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
    • H01M4/36—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 electrochemical technology, and in particular to a negative electrode sheet, an electrochemical device and an electronic device.
  • Lithium-ion batteries have the characteristics of high operating voltage, high energy density, long cycle life and wide operating temperature range. These excellent characteristics have enabled lithium-ion batteries to be widely used in the three major fields of consumer electronics, power batteries and energy storage.
  • Silicon materials have high theoretical gram capacity and have broad application prospects in lithium-ion batteries. However, during the charge and discharge cycle, as lithium ions are inserted and removed, silicon materials will expand in volume by 120% to 300%, causing the silicon materials to pulverize and separate from the negative electrode current collector, resulting in poor conductivity of the negative electrode sheet, affecting the cycle performance of lithium-ion batteries.
  • the purpose of this application is to provide an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device.
  • the specific technical solution is as follows:
  • the present application provides a negative electrode plate, which includes a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material, wherein the negative electrode active material includes a carbon-doped silicon-oxygen composite material and graphite, wherein the carbon-doped silicon-oxygen composite material includes carbon, silicon and oxygen, wherein the carbon content in the surface region of particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal region of the particles, wherein the surface region is a region from the surface of the particle to a depth of 500 nm, and the internal region is a region of the particle excluding the surface region; wherein, based on the total mass of the carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of the carbon in the carbon-doped silicon-oxygen composite material is 2% to 10%.
  • the carbon element is introduced into the carbon-doped silicon-oxygen composite material in the negative electrode pole piece provided in the present application, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is regulated within the above-mentioned range.
  • the carbon-doped silicon-oxygen composite material in the negative electrode pole piece has good expansion performance and is not easy to pulverize, and the negative electrode pole piece has good conductivity, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the mass percentage of the carbon element in the surface region is 0.5% to 8%.
  • the mass percentage of the silicon element in the carbon-doped silicon-oxygen composite material is 40% to 60%.
  • the particle size distribution range of the carbon-doped silicon-oxygen composite material is 0.2 ⁇ m to 20 ⁇ m, Dv50 is 4 ⁇ m to 10 ⁇ m, and Dv99 is 13 ⁇ m to 20 ⁇ m.
  • the carbon-doped silicon-oxygen composite material has a powder conductivity of 0.03 S/cm to 8 S/cm.
  • the carbon-doped silicon-oxygen composite material has a powder conductivity within the above range, which is beneficial for improving the cycle performance of the electrochemical device.
  • the internal region of the carbon-doped silicon-oxygen composite material particles forms Si-C bonds, and the surface region forms Si-O-C bonds, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the mass content of carbon in the surface region of the carbon-doped silicon-oxygen composite material particles accounts for 10% to 80% of the mass content of carbon in the carbon-doped silicon-oxygen composite material.
  • silicon and oxygen are evenly distributed in the carbon-doped silicon-oxygen composite material particles, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the graphite includes at least one of natural graphite, artificial graphite or mesophase carbon microspheres, etc.
  • the selection of the above graphite is conducive to improving the cycle performance of the electrochemical device.
  • the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite is (3 to 20): (80 to 97).
  • the negative electrode material layer further includes a binder
  • the binder includes at least one of polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, polystyrene butadiene copolymer, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose or potassium hydroxymethyl cellulose.
  • the second aspect of the present application provides an electrochemical device, which comprises the negative electrode sheet in any of the above embodiments. Therefore, the electrochemical device provided by the present application has good cycle performance and expansion performance.
  • the third aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
  • the present application provides a negative electrode plate, an electrochemical device and an electronic device, wherein the negative electrode plate comprises a negative electrode active material layer, the negative electrode active material layer comprises a negative electrode active material, the negative electrode active material comprises a carbon-doped silicon-oxygen composite material and graphite, the carbon-doped silicon-oxygen composite material comprises carbon, silicon and oxygen, the carbon content in the surface region of particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal region of the particles, wherein the surface region is a region from the surface of the particle to a depth of 500 nm, and the internal region is a region of the particle excluding the surface region; wherein, based on the total mass of the carbon, silicon and oxygen, the mass percentage of the carbon in the carbon-doped silicon-oxygen composite material is 2% to 10%.
  • the negative electrode plate provided by the present application has good conductivity, and its application in an electrochemical device can improve the cycle performance and expansion performance of the electrochemical device.
  • FIG1 is a schematic diagram of the structure of carbon-doped silicon-oxygen composite particles in some embodiments of the present application.
  • FIG2 is an X-ray energy dispersive spectrometer (EDS) image of the carbon-doped silicon-oxygen composite material in Example 1-1;
  • EDS X-ray energy dispersive spectrometer
  • FIG3 is a distribution image of oxygen element in a carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG1 ;
  • FIG4 is a distribution image of silicon in a carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG1 ;
  • FIG. 5 is a distribution image of carbon element in the carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG. 1 .
  • lithium-ion batteries are used as an example of electrochemical devices to explain the present application, but the electrochemical devices of the present application are not limited to lithium-ion batteries.
  • the specific technical solution is as follows:
  • the first aspect of the present application provides a negative electrode plate, which includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes a carbon-doped silicon-oxygen composite material and graphite, the carbon-doped silicon-oxygen composite material includes carbon, silicon and oxygen, the carbon content in the surface area of the particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal area of the particles, wherein the surface area is an area from the surface of the particle to a depth of 500nm, and the internal area is an area in the particle excluding the surface area; wherein, based on the total mass of the carbon element, silicon element and oxygen element in the carbon-doped silicon-oxygen composite material, the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is 2% to 10%.
  • Figure 1 shows a schematic structural diagram of a particle 10 of a carbon-doped silicon-oxygen composite material in some embodiments of the present application, wherein the particle 10 includes a surface region 12 and an internal region 13, and the direction indicated by the arrow inside the particle 10 is the direction extending from the surface 11 of the particle 10 to the interior of the particle 10, and the distance d shown in the figure is the depth extending from the surface 11 of the particle 10 to the interior of the particle 10, and the surface region 12 is the region from the surface 11 of the particle 10 to the internal depth d of 500 nm, and the internal region 13 is the region of the particle 10 excluding the surface region 11.
  • the introduction of carbon elements in the carbon-doped silicon-oxygen composite material in the negative electrode plate, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and Si-C bonds are formed in the internal area of the particles and Si-O-C bonds are formed in the surface area.
  • Si-C bonds and Si-O-C bonds Under the synergistic effect of Si-C bonds and Si-O-C bonds, the growth of silicon grains inside the particles during the cycle can be limited, the risk of pulverization of the negative electrode active material can be reduced, and its expansion performance can be improved.
  • the stability of the particle surface can also be improved, and the risk of being etched by the electrolyte can be reduced to improve the cycle performance of the electrochemical device.
  • the carbon-doped silicon-oxygen composite material in the negative electrode plate provided by the present application is not easy to pulverize during the cycle, the negative electrode plate has good conductivity, and the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize.
  • the negative electrode plate provided by the present application is applied to an electrochemical device, which can improve the cycle performance and expansion performance of the electrochemical device.
  • the mass percentage of carbon in the carbon-doped silicon-oxygen composite material can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range consisting of any two of the above values.
  • the mass percentage of carbon in the carbon-doped silicon-oxygen composite material is too low, for example, less than 2%, the Si-C bonds formed inside the carbon-doped silicon-oxygen composite material particles and the Si-O-C bonds formed on the surface of the particles are less, and the growth of silicon grains during the cycle cannot be effectively restricted.
  • the stability of the particle surface is not significantly improved, and the particles are easily pulverized during the charge and discharge cycle, which affects the expansion performance of the particles and the conductivity of the negative electrode.
  • the mass percentage of carbon in the carbon-doped silicon-oxygen composite material is too high, for example, higher than 10%, it will affect the gram capacity and first coulomb efficiency of the carbon-doped silicon-oxygen composite material, and thus affect the energy density of the electrochemical device.
  • the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize, and the negative electrode plate has good conductivity, which makes the electrochemical device have a higher energy density and is also beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the carbon element is introduced into the carbon-doped silicon-oxygen composite material in the negative electrode pole piece provided in the present application, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is regulated within the above-mentioned range.
  • the carbon-doped silicon-oxygen composite material in the negative electrode pole piece has good expansion properties and is not easy to pulverize, and the negative electrode pole piece has good conductivity, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the mass percentage of carbon in the surface region is 0.5% to 8%.
  • the mass percentage of carbon in the surface region can be 0.5%, 2%, 4%, 6%, 8% or a range consisting of any two of the above values.
  • the mass percentage of silicon in the carbon-doped silicon-oxygen composite material is 40% to 60%.
  • the mass percentage of silicon in the carbon-doped silicon-oxygen composite material can be 40%, 45%, 50%, 55%, 60% or a range consisting of any two of the above values.
  • the mass percentage of oxygen in the carbon-doped silicon-oxygen composite material is: 100% - (mass percentage of silicon + mass percentage of carbon). It should be noted that the carbon-doped silicon-oxygen composite material usually contains some impurity elements with a relatively low content (for example, the mass percentage is less than or equal to 0.1%), and the present application does not consider the above impurity elements when calculating the mass percentage of carbon, silicon and oxygen.
  • the present application has no particular restriction on the mass percentage of silicon and oxygen in the surface region, as long as the purpose of the present application can be achieved.
  • the mass percentage of silicon in the surface region can be 0.5% to 8%, and the mass percentage of oxygen in the surface region can be 20% to 40%.
  • the particle size distribution range of the carbon-doped silicon-oxygen composite material is 0.2 ⁇ m to 20 ⁇ m, Dv50 is 4 ⁇ m to 10 ⁇ m, and Dv99 is 13 ⁇ m to 20 ⁇ m.
  • the particle size distribution range can be any range of 0.2 ⁇ m to 20 ⁇ m, 0.3 ⁇ m to 20 ⁇ m, 0.4 ⁇ m to 20 ⁇ m, 0.5 ⁇ m to 20 ⁇ m, and 0.6 ⁇ m to 20 ⁇ m
  • Dv50 can be 4 ⁇ m, 5 ⁇ m, 5.5 ⁇ m, 6 ⁇ m, 6.5 ⁇ m, 7 ⁇ m, 7.5 ⁇ m, 9 ⁇ m, 10 ⁇ m, or a range consisting of any two of the above values
  • Dv99 can be 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 17 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m, 20 ⁇ m, or a range consisting of any two of the above values.
  • the side reaction between the carbon-doped silicon-oxygen composite material and the electrolyte can be reduced, thereby alleviating the volume change of the carbon-doped silicon-oxygen composite material, enhancing the compressive strength of the carbon-doped silicon-oxygen composite material, and further increasing the structural stability of the negative electrode sheet, which is beneficial to improving the cycle performance of the electrochemical device.
  • Dv50 means the particle size reaching 50% of the volume accumulation in the volume-based particle size distribution of the material, measured from the smallest particle size
  • Dv99 means the particle size reaching 99% of the volume accumulation in the volume-based particle size distribution of the material, measured from the smallest particle size.
  • the powder conductivity of the carbon-doped silicon-oxygen composite material is 0.03S/cm to 8S/cm.
  • the powder conductivity of the carbon-doped silicon-oxygen composite material can be 0.03S/cm, 0.05S/cm, 0.1S/cm, 0.5S/cm, 1S/cm, 1.5S/cm, 2S/cm, 3S/cm, 4S/cm, 5S/cm, 6S/cm, 7S/cm, 8S/cm or a range consisting of any two of the above values.
  • the carbon-doped silicon-oxygen composite material has a powder conductivity in the above range, which can effectively control the current density at the interface between the negative electrode plate and the electrolyte, making it less likely for the negative electrode plate to undergo lithium precipitation, which is beneficial to improving the cycle performance of the electrochemical device.
  • the mass content of carbon elements in the surface area of the carbon-doped silicon-oxygen composite material particles accounts for 10% to 80% of the mass content of carbon elements in the carbon-doped silicon-oxygen composite material.
  • the mass content of carbon elements in the surface area accounts for 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or a range composed of any two of the above values.
  • the above proportion is within the above range, the growth of silicon grains inside the particles during the cycle can be limited, the risk of pulverization of the negative electrode active material can be reduced and its expansion performance can be improved, and the stability of the particle surface can be improved, and the risk of being etched by the electrolyte can be reduced to improve the cycle performance of the electrochemical device.
  • the carbon-doped silicon-oxygen composite material in the negative electrode plate provided by the present application is not easy to pulverize during the cycle, the negative electrode plate has good conductivity, and the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize.
  • the negative electrode plate provided by the present application is applied to the electrochemical device, which can improve the cycle performance and expansion performance of the electrochemical device.
  • silicon and oxygen are evenly distributed in the carbon-doped silicon-oxygen composite material particles, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
  • the graphite includes at least one of natural graphite, artificial graphite or mesophase carbon microspheres, etc.
  • the selection of the above graphite materials is beneficial to improve the cycle performance of the electrochemical device.
  • the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite is (3 to 20): (80 to 97).
  • the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite can be 20:80, 18:82, 15:85, 12:88, 10:90, 7:93, 6:94, 5:95, 4:96, 3:97 or a range consisting of any two of the above ratios.
  • the negative electrode active material layer can maintain a high gram capacity, while reducing the probability of direct contact between silicon and the electrolyte to reduce the side reactions between silicon and the electrolyte and the formation of a solid electrolyte interface (SEI) film, alleviating the volume expansion of silicon, and graphite can increase the conductivity of the negative electrode plate, thereby facilitating a synergistic improvement in the cycle performance of the electrochemical device.
  • SEI solid electrolyte interface
  • the negative electrode material layer also includes a binder
  • the binder includes at least one of polyacrylate, polyimide, polyamide, polyamide-imide, polyvinylidene fluoride, polystyrene butadiene copolymer (styrene-butadiene rubber), sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose or potassium hydroxymethyl cellulose.
  • the obtained negative electrode material layer has good structural stability, which is conducive to improving the cycle performance of the electrochemical device.
  • the negative electrode active material layer may further include a conductive agent.
  • the present application has no particular restrictions on the conductive agent, as long as the purpose of the present application can be achieved.
  • the conductive agent may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, flake graphite, Ketjen black or graphene.
  • the present application has no particular restrictions on the mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode active material layer. Those skilled in the art may select according to actual needs, as long as the purpose of the present application can be achieved.
  • the negative electrode sheet of the present application includes a negative electrode current collector, and a negative electrode active material layer is arranged on at least one surface of the negative electrode current collector.
  • the above-mentioned "negative electrode active material layer is arranged on at least one surface of the negative electrode current collector” means that the negative electrode active material layer can be arranged on one surface of the negative electrode current collector along its own thickness direction, or it can be arranged on two surfaces of the negative electrode current collector along its own thickness direction.
  • 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. This application has no special restrictions, as long as the purpose of this application can be achieved.
  • This application has no special restrictions on the negative electrode current collector, as long as the purpose of this application can be achieved.
  • it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or composite current collector (such as carbon copper composite current collector, nickel copper composite current collector, titanium copper composite current collector, etc.).
  • the present application has no particular restrictions on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the present application can be achieved, for example, the thickness of the negative electrode current collector is 6 ⁇ m to 12 ⁇ m, and the thickness of the negative electrode active material layer is 30 ⁇ m to 120 ⁇ m.
  • the application has no particular restrictions on the thickness of the negative electrode sheet, as long as the purpose of the present application can be achieved, for example, the thickness of the negative electrode sheet is 50 ⁇ m to 150 ⁇ m.
  • the negative electrode plate may further include a conductive layer, which is located between the negative electrode current collector and the negative electrode active material layer.
  • a conductive layer which is located between the negative electrode current collector and the negative electrode active material layer.
  • the present application has no particular restrictions on the composition of the conductive layer, which may be a conductive layer commonly used in the art.
  • the conductive layer includes a conductive agent and a binder.
  • the present application has no particular restrictions on the conductive agent and the binder in the conductive layer, which may be, for example, at least one of the above conductive agent and the above binder.
  • the preparation method of the carbon-doped silicon-oxygen composite material may include but is not limited to the following steps: the carbon-doped silicon-oxygen material and the organosilicon solution are mixed evenly and then dried, and then heat-treated under an inert atmosphere to obtain the carbon-doped silicon-oxygen composite material.
  • the drying temperature is 80°C to 120°C;
  • the heat treatment temperature is 600°C to 1000°C, the heating rate of the heat treatment is 1°C/min to 10°C/min, and the heat preservation time of the heat treatment is 1h to 6h;
  • the organosilicon solution includes organosilicon and solvent, the organosilicon may include but is not limited to at least one of tetramethyl-tetravinyl-cyclotetrasiloxane or polymethylhydrogensiloxane, etc., the solvent may include but is not limited to ethanol, etc., and the mass ratio of organosilicon to solvent may be 1: (2 to 6); the inert atmosphere may be argon and/or nitrogen.
  • the mass percentage of carbon, silicon and oxygen in carbon-doped silicon-oxygen composite materials can be controlled by changing the temperature, heating rate and holding time of heat treatment. For example, by increasing the heat treatment temperature, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials increases, the mass percentage of silicon increases, and the mass percentage of oxygen decreases; by reducing the heat treatment temperature, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials decreases, the mass percentage of silicon decreases, and the mass percentage of oxygen increases.
  • the mass percentage of carbon in carbon-doped silicon-oxygen composite materials decreases, the mass percentage of silicon decreases, and the mass percentage of oxygen increases; by reducing the heating rate, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials increases, the mass percentage of silicon increases, and the mass percentage of oxygen decreases.
  • the mass percentage of carbon element in the carbon-doped silicon-oxygen composite material increases, the mass percentage of silicon element increases, and the mass percentage of oxygen element decreases; by shortening the holding time of the heat treatment, the mass percentage of carbon element in the carbon-doped silicon-oxygen composite material decreases, the mass percentage of silicon element decreases, and the mass percentage of oxygen element increases.
  • Changing the temperature, heating rate and holding time of the heat treatment can also regulate the mass percentage of carbon, silicon and oxygen in the surface area. For example, increasing the heat treatment temperature increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen; decreasing the heat treatment temperature decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen. Increasing the heating rate decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen; decreasing the heating rate increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen.
  • Prolonging the holding time of the heat treatment increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen; shortening the holding time of the heat treatment decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen.
  • Changing the temperature, heating rate and heat preservation time of the heat treatment can also regulate the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material. For example, by increasing the heat treatment temperature, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases; by reducing the heat treatment temperature, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases.
  • the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases; by reducing the heating rate, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases.
  • the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases; by shortening the heat preservation time of the heat treatment, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases.
  • the preparation method of the carbon-doped silicon-oxygen material may include but is not limited to the following steps: silicon and silicon dioxide are mixed evenly and loaded into a vacuum deposition furnace, the temperature is controlled to be 1300°C to 1350°C and the vacuum degree is 1Pa to 100Pa, and an appropriate amount of carbon source gas (such as methane, acetylene, ethylene, etc.) is introduced to obtain a carbon-doped silicon-oxygen material.
  • carbon source gas such as methane, acetylene, ethylene, etc.
  • the contents of carbon, silicon, and oxygen in the carbon-doped silicon-oxygen material can be regulated by the mixing ratio of silicon and silicon dioxide and the content of the carbon source gas introduced.
  • the content of silicon increases and the content of oxygen decreases as the mixing ratio of silicon and silicon dioxide increases; the content of silicon decreases and the content of oxygen increases as the mixing ratio of silicon and silicon dioxide decreases; the content of carbon increases as the carbon source gas introduced increases; the content of carbon decreases as the carbon source gas introduced decreases.
  • the mass percentage of carbon is 2% to 10%
  • the mass percentage of silicon is 40% to 60%
  • the mass percentage of oxygen is 30% to 50%.
  • the carbon-doped silicon-oxygen material usually contains some impurity elements with a relatively low content (for example, the mass percentage is less than or equal to 0.1%).
  • the present application refers to the total mass obtained after excluding the above-mentioned impurity elements, and then obtaining the mass percentage of carbon, silicon, and oxygen.
  • the present application can obtain carbon-doped silicon-oxygen materials with different particle size distributions by particle size classification.
  • the present application has no particular restrictions on the particle size classification method, as long as a material that meets the particle size requirements of the present application can be obtained.
  • a carbon-doped silicon-oxygen composite material with different particle size distributions can be obtained by grinding and performing particle size screening.
  • the present application has no particular restrictions on the method for regulating the powder conductivity of the carbon-doped silicon-oxygen composite material, as long as the purpose of the present application can be achieved.
  • the conductivity of the carbon-doped silicon-oxygen composite material can be regulated by regulating the mass percentage of the carbon element.
  • the powder conductivity of the carbon-doped silicon-oxygen composite material increases with the increase of the mass percentage of the carbon element therein, and decreases with the decrease of the mass percentage of the carbon element therein.
  • the second aspect of the present application provides an electrochemical device, which comprises the negative electrode sheet in any of the above embodiments. Therefore, the electrochemical device provided by the present application has good cycle performance and expansion performance.
  • the electrochemical device also includes a positive electrode plate, which includes a positive electrode collector and a positive electrode active material layer disposed on at least one surface of the positive electrode collector.
  • a positive electrode plate which includes a positive electrode collector and a positive electrode active material layer disposed on at least one surface of the positive electrode collector.
  • the above-mentioned "positive electrode active material layer disposed on at least one surface of the positive electrode collector” means that the positive electrode active material layer can be disposed on one surface of the positive electrode collector along the thickness direction of itself, or on two surfaces of the positive electrode collector along the thickness direction of itself.
  • the "surface” here can be the entire area of the positive electrode collector or a partial area of the positive electrode collector. This application has no special restrictions, as long as the purpose of this application can be achieved. This application has no special restrictions on the positive electrode collector, as long as the purpose of this application can be achieved.
  • the positive electrode active material layer includes a positive electrode active material.
  • the present application has no particular restrictions on the positive electrode active material, as long as the purpose of the present application can be achieved.
  • the positive electrode active material may include at least one of nickel cobalt manganese oxide (such as common NCM811, NCM622, NCM523, NCM111), nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO 2 ), lithium manganate, lithium iron manganese phosphate or lithium titanate.
  • the positive electrode active material layer also includes a conductive agent and a binder.
  • the present application has no particular restrictions on the types of conductive agents and binders, as long as the purpose of the present application can be achieved. For example, it can be at least one of the above conductive agents and the above binders.
  • the present application has no particular restrictions on the mass ratio of the positive electrode active material, conductive agent and binder in the positive electrode active material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved.
  • the present application has no particular restrictions on the thickness of the positive current collector and the positive electrode material layer, as long as the purpose of the present application can be achieved. For example, the thickness of the positive electrode current collector is 6 ⁇ m to 12 ⁇ m, and the thickness of the positive electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • the application has no particular restrictions on the thickness of the positive electrode sheet, as long as the purpose of the application can be achieved, for example, the thickness of the positive electrode sheet is 50 ⁇ m to 150 ⁇ m.
  • the positive electrode sheet may further include a conductive layer, which is located between the positive electrode current collector and the positive electrode material layer.
  • the composition of the conductive layer is not particularly limited, and it can be a conductive layer commonly used in the art.
  • the conductive layer includes a conductive agent and a binder.
  • the present application has no particular restrictions on the conductive agent and the binder in the conductive layer, for example, it can be at least one of the above conductive agent and the above binder.
  • the electrochemical device also includes a separator to separate the positive electrode plate and the negative electrode plate, prevent internal short circuit of the electrochemical device, allow electrolyte ions to pass freely, and do not affect the electrochemical charge and discharge process.
  • the present application has no special restrictions on the separator, as long as the purpose of the present application can be achieved.
  • the material of the separator may include but is not limited to polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (for example, polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid;
  • the type of separator may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane or a spun membrane.
  • the isolation membrane may include a substrate layer and a surface treatment layer.
  • the substrate layer may be a nonwoven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder
  • the inorganic particles are not particularly limited, and may include, for example, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the binder is not particularly limited, and may be, for example, at least one of the above-mentioned binders.
  • the polymer layer includes a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether or polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
  • the electrochemical device also includes an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the lithium salt may include at least one of LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , Li 2 SiF 6 , lithium bis(oxalate borate) (LiBOB) or lithium difluoroborate.
  • LiBOB lithium bis(oxalate borate
  • the present application does not particularly limit the concentration of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved.
  • the concentration of the lithium salt in the electrolyte is 0.9 mol/L to 1.5 mol/L.
  • the concentration of the lithium salt in the electrolyte may be 0.9 mol/L, 1.0 mol/L, 1.1 mol/L, 1.3 mol/L, 1.5 mol/L or a range consisting of any two of the above values.
  • the present application has no particular restrictions on non-aqueous solvents, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • the above-mentioned carbonate compounds may include but are not limited to at least one of linear carbonate compounds, cyclic carbonate compounds or fluorinated carbonate compounds.
  • the above-mentioned linear carbonate compounds may include but are not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) or ethyl methyl carbonate (MEC).
  • the above-mentioned cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC).
  • the fluorinated carbonate compound may include, but is not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • the above-mentioned carboxylate compound may include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decalactone, valerolactone, or caprolactone.
  • the above-mentioned ether compound may include but is not limited to at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, cyclopentane, methyl cyclopentane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.
  • the mass percentage of the above-mentioned non-aqueous solvent in the electrolyte can be 15% to 80%, for example, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or any range therebetween.
  • the electrochemical device of the present application also includes a packaging bag for containing a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, as well as other components known in the art in the electrochemical device, and the present application does not limit the above other components.
  • the present application does not specifically limit the packaging bag, and it can be a packaging bag known in the art, as long as it can achieve the purpose of the present application.
  • the electrochemical device of the present application is not particularly limited, and may include any device that undergoes an electrochemical reaction.
  • the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the preparation process of the electrochemical device of the present application is well known to those skilled in the art, and the present application has no particular limitation.
  • it may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly of a wound structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device.
  • overcurrent protection elements, guide plates, etc. may also be placed in the packaging bag as needed to prevent pressure rise and overcharge and discharge inside the electrochemical device.
  • the third aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
  • the electronic device of the present application is not particularly limited, and it can be any electronic device known in the prior art.
  • the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
  • a conductive adhesive was applied to the sample stage, and the powdered samples of the carbon-doped silicon-oxygen composite materials in each embodiment or the negative electrode active materials other than graphite in the comparative example were spread on the conductive adhesive.
  • the unattached powder was blown away with an ear bulb, and gold was sprayed.
  • the distribution and mass percentage of the test elements were scanned using an EDS equipped with a Philips XL-30 field emission scanning electron microscope at an acceleration voltage of 10 kV and an emission current of 10 mA.
  • a conductive adhesive was pasted on the sample table, and the powdered samples of the carbon-doped silicon-oxygen composite materials in each embodiment or the negative electrode active materials other than graphite in the comparative examples were spread flat on the conductive adhesive, and the unadhered powder was blown away with an ear-cleaning bulb, and gold was sprayed, and the particles of the powdered sample were cross-sectioned using argon plasma.
  • the negative electrode active material conductive agent conductive carbon black: PAA binder polyethyl acrylate are mixed in a mass ratio of 8:1:1, N-methylpyrrolidone (NMP) is added as a solvent, and a slurry with a solid content of 45wt% is prepared. The slurry is evenly coated on the copper foil and dried to obtain the negative electrode plate. Then, the lithium plate is used as the counter electrode, and the negative electrode plate, lithium plate, isolation film and electrolyte are assembled into a button battery for testing.
  • NMP N-methylpyrrolidone
  • the above-mentioned negative electrode active material is the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, and the isolation film and electrolyte are the same as those in Example 1-1.
  • the lithium-ion battery was charged to 4.45V at 0.5C constant current, then charged to 0.025C at 4.45V constant voltage, left to stand for 5 minutes, and discharged to 3.0V at 0.5C constant current, left to stand for 5 minutes, and the discharge capacity of the first cycle was recorded. Then, the same steps were used for 500 charge and discharge cycles, and the discharge capacity of the lithium-ion battery at the 500th cycle was recorded.
  • Cycle capacity retention rate (%) of lithium ion battery (discharge capacity at the 500th cycle/discharge capacity at the first cycle) ⁇ 100%.
  • Tetramethyl-tetravinyl-cyclotetrasiloxane, polymethylhydrogensiloxane and ethanol were mixed in a mass ratio of 1:1:8 and stirred until uniformly mixed to obtain an organosilicon solution.
  • the carbon-doped silicon-oxygen material and the organosilicon solution were mixed in a mass ratio of 63:50 and stirred uniformly, dried at 80°C, and then heat-treated to obtain a carbon-doped silicon-oxygen composite material, with a heat treatment temperature of 800°C, a heating rate of 3°C/min, and a holding time of 3h.
  • the mass percentage of carbon element in the carbon-doped silicon-oxygen material is 2%
  • the mass percentage of silicon element is 59%
  • the mass percentage of oxygen element is 39%.
  • the carbon-doped silicon-oxygen composite material, graphite, conductive carbon black and styrene-butadiene rubber prepared above are mixed in a mass ratio of 5:92:1.8:1.2, deionized water is added as a solvent, and a slurry with a solid content of 45wt% is prepared. After being stirred evenly by a vacuum mixer, a negative electrode slurry is obtained. The negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 10 ⁇ m, and dried at 90°C to obtain a negative electrode sheet with a single-sided negative electrode active material layer coated with a coating thickness of 100 ⁇ m.
  • the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly.
  • NMP N-methylpyrrolidone
  • the slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10 ⁇ m, and dried at 90°C to obtain a positive electrode sheet with a single-sided coating of a negative electrode active material layer with a coating thickness of 100 ⁇ m.
  • organic solvents EC, PC, DEC and EP were mixed in a mass ratio of 3:1:3:3, and then lithium salt lithium hexafluorophosphate (LiPF 6 ) was added to the organic solvents to dissolve and mix evenly to obtain an electrolyte solution, wherein the concentration of the lithium salt was 12.5 wt %.
  • a porous polyethylene film with a thickness of 7 ⁇ m (provided by Celgard Company) was used.
  • the prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain an electrode assembly.
  • the electrode assembly is placed in an aluminum-plastic film packaging bag, and the moisture is removed at 80°C, and the prepared electrolyte is injected. After vacuum packaging, standing, formation, degassing, trimming and other processes, a lithium-ion battery is obtained.
  • the negative electrode active material is prepared according to the following steps and the carbon-doped silicon-oxygen composite material in ⁇ Preparation of negative electrode sheet> is replaced with the negative electrode active material prepared below, and the rest is the same as Example 1-1;
  • the carbon-doped silicon-oxygen material is subjected to heat treatment to obtain a negative electrode active material, wherein the heat treatment temperature is 800°C, the heating rate is 3°C/min, and the holding time is 3h.
  • the mass percentage of carbon element in the carbon-doped silicon-oxygen material is 2%, the mass percentage of silicon element is 59%, and the mass percentage of oxygen element is 39%.
  • Example 1-1 Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.
  • the rest is the same as Example 1-1.
  • the mass percentage of silicon element in the silicon-oxygen material is 62%, and the mass percentage of oxygen element is 38%.
  • the silicon-oxygen material is a commercially available material, and it only needs to meet the above-mentioned element content.
  • element content in Table 1 refers to the mass percentage of the corresponding element
  • negative electrode active material refers to the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example
  • proportion refers to the ratio of the mass content of carbon element in the surface area of carbon-doped silicon-oxygen composite material particles to the mass content of carbon element in carbon-doped silicon-oxygen composite material
  • “/" indicates that there is no corresponding parameter or substance.
  • element content in Table 2 refers to the mass percentage of the corresponding element
  • negative electrode active material refers to the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, and "/" indicates that the corresponding parameter or substance does not exist; taking Example 1-1 as an example, "0.2-20” means that the particle size distribution of the negative electrode active material is 0.2 ⁇ m to 20 ⁇ m, and the rest of the embodiments and comparative examples are understood by analogy.
  • the lithium-ion battery obtained in the example has a higher cycle capacity retention rate and a smaller expansion rate, which shows that the use of the negative electrode sheet provided by the present application can effectively improve the cycle performance and expansion performance of the lithium-ion battery.
  • the negative active materials in Comparative Examples 1 and 3 have higher gram capacity, the cycle performance and expansion performance of the lithium-ion battery are significantly worse than those in the examples; the gram capacity of the carbon-doped silicon-oxygen composite material in the example is basically equivalent to or higher than that in Comparative Example 2, but the cycle performance and expansion performance of the lithium-ion battery in Comparative Example 2 are also significantly worse than those in the example.
  • This shows that the embodiment of the present application can take into account both the gram capacity of the negative electrode active material and the performance of the lithium-ion battery, while Comparative Examples 1 to 3 are difficult to take into account both.
  • Figure 2 is an EDS layered image of the carbon-doped silicon-oxygen composite material in Example 1-1
  • Figures 3 to 5 are respectively distribution images of oxygen, silicon and carbon in the carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in Figure 1. From Figures 2 to 5, it can be seen that the carbon-doped silicon-oxygen composite material contains oxygen, silicon and carbon, and the oxygen and silicon elements are distributed more evenly in the carbon-doped silicon-oxygen composite material, and the carbon element is mainly distributed in the surface area of the carbon-doped silicon-oxygen composite material particles.
  • the mass percentage of carbon element in the surface region of carbon-doped silicon-oxygen composite material particles usually affects the cycle performance and expansion performance of lithium-ion batteries. It can be seen from Examples 1-1 to 1-12 that when the mass percentage of carbon element in the surface region of carbon-doped silicon-oxygen composite material particles is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
  • the mass percentage of silicon in the carbon-doped silicon-oxygen composite material usually affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-12 that when the mass percentage of silicon in the carbon-doped silicon-oxygen composite material is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
  • the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material generally also affect the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-12 that when the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material are within the scope of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
  • the powder conductivity of the carbon-doped silicon-oxygen composite material generally also affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-11 that when the powder conductivity of the carbon-doped silicon-oxygen composite material is within the scope of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
  • the mass ratio of the carbon-doped silicon-oxygen composite material to graphite usually affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1, 2-1 and 2-2 that when the mass ratio of the carbon-doped silicon-oxygen composite material to graphite is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.

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Abstract

Provided are a negative pole piece, an electrochemical apparatus, and an electrical apparatus. The negative pole piece comprises a negative electrode active material layer, the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises a carbon-doped silicon-oxygen composite material and graphite. The carbon-doped silicon-oxygen composite material comprises the elements carbon, silicon and oxygen, and the carbon content in a surface region (12) of a particle (10) of the carbon-doped silicon-oxygen composite material is greater than the carbon content in an internal region (13) of the particle; and the mass percent content of carbon in the carbon-doped silicon-oxygen composite material is 2%-10% of the sum of the masses of carbon, silicon, and oxygen. The carbon-doped silicon-oxygen composite material in the negative pole piece has good expansion performance and does not easily disintegrate, and the negative pole piece has good electrical conductivity, thereby helping to improve the cycle performance and expansion performance of the electrochemical apparatus.

Description

一种负极极片、电化学装置和电子装置Negative electrode sheet, electrochemical device and electronic device 技术领域Technical Field
本申请涉及电化学技术领域，特别是涉及一种负极极片、电化学装置和电子装置。The present application relates to the field of electrochemical technology, and in particular to a negative electrode sheet, an electrochemical device and an electronic device.
背景技术Background technique
锂离子电池具有工作电压高，能量密度高、循环寿命长、工作温度范围宽等特性，这些优异的特性使锂离子电池在消费电子、动力电池和储能三大领域都实现了广泛应用。Lithium-ion batteries have the characteristics of high operating voltage, high energy density, long cycle life and wide operating temperature range. These excellent characteristics have enabled lithium-ion batteries to be widely used in the three major fields of consumer electronics, power batteries and energy storage.
硅材料具有高的理论克容量，在锂离子电池中具有广阔的应用前景。但硅材料在充放电循环过程中，随着锂离子的嵌入和脱出，会发生120％至300％的体积膨胀，导致硅材料粉化并与负极集流体脱离，从而导致负极极片导电性变差，影响锂离子电池的循环性能。Silicon materials have high theoretical gram capacity and have broad application prospects in lithium-ion batteries. However, during the charge and discharge cycle, as lithium ions are inserted and removed, silicon materials will expand in volume by 120% to 300%, causing the silicon materials to pulverize and separate from the negative electrode current collector, resulting in poor conductivity of the negative electrode sheet, affecting the cycle performance of lithium-ion batteries.
发明内容Summary of the invention
本申请的目的在于提供一种电化学装置和电子装置，以提高电化学装置的循环性能。具体技术方案如下：The purpose of this application is to provide an electrochemical device and an electronic device to improve the cycle performance of the electrochemical device. The specific technical solution is as follows:
本申请第一方面提供了一种负极极片，其包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述负极活性材料包括碳掺杂硅氧复合材料和石墨，所述碳掺杂硅氧复合材料包括碳元素、硅元素和氧元素，所述碳掺杂硅氧复合材料的颗粒的表面区域中的碳元素含量大于所述颗粒内部区域中的碳元素含量，其中，所述表面区域为沿所述颗粒表面至内部深度为500nm的区域，所述内部区域为所述颗粒中除去所述表面区域以外的区域；其中，基于所述碳掺杂硅氧复合材料中所述碳元素、所述硅元素和所述氧元素的质量总和，所述碳掺杂硅氧复合材料中所述碳元素的质量百分含量为2％至10％。本申请提供的负极极片中碳掺杂硅氧复合材料中碳元素的引入，且碳掺杂硅氧复合材料颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，以及调控碳掺杂硅氧复合材料中碳元素的质量百分含量在上述范围内，负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，从而有利于改善电化学装置的循环性能和膨胀性能。In a first aspect, the present application provides a negative electrode plate, which includes a negative electrode active material layer, wherein the negative electrode active material layer includes a negative electrode active material, wherein the negative electrode active material includes a carbon-doped silicon-oxygen composite material and graphite, wherein the carbon-doped silicon-oxygen composite material includes carbon, silicon and oxygen, wherein the carbon content in the surface region of particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal region of the particles, wherein the surface region is a region from the surface of the particle to a depth of 500 nm, and the internal region is a region of the particle excluding the surface region; wherein, based on the total mass of the carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of the carbon in the carbon-doped silicon-oxygen composite material is 2% to 10%. The carbon element is introduced into the carbon-doped silicon-oxygen composite material in the negative electrode pole piece provided in the present application, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is regulated within the above-mentioned range. The carbon-doped silicon-oxygen composite material in the negative electrode pole piece has good expansion performance and is not easy to pulverize, and the negative electrode pole piece has good conductivity, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，基于所述碳掺杂硅氧复合材料中所述碳元素、所述硅元素和所述氧元素的质量总和，所述表面区域中所述碳元素的质量百分含量为0.5％至8％。通过调控碳掺杂硅氧复合材料表面区域中碳元素的质量百分含量在上述范围内，负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，从而有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, based on the total mass of the carbon element, the silicon element and the oxygen element in the carbon-doped silicon-oxygen composite material, the mass percentage of the carbon element in the surface region is 0.5% to 8%. By regulating the mass percentage of the carbon element in the surface region of the carbon-doped silicon-oxygen composite material within the above range, the carbon-doped silicon-oxygen composite material in the negative electrode sheet has good expansion performance and is not easy to pulverize, and the negative electrode sheet has good conductivity, which is conducive to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，基于所述碳掺杂硅氧复合材料中所述碳元素、所述硅元素和所述氧元素的质量总和，所述碳掺杂硅氧复合材料中所述硅元素的质量百分含量为40％至60％。通过调控碳掺杂硅氧复合材料中硅元素的质量百分含量在上述范围内，得到的电化学装置在具有良好的循环性能和膨胀性能的同时，还具有较高的能量密度。In some embodiments of the present application, based on the total mass of the carbon element, the silicon element and the oxygen element in the carbon-doped silicon-oxygen composite material, the mass percentage of the silicon element in the carbon-doped silicon-oxygen composite material is 40% to 60%. By regulating the mass percentage of the silicon element in the carbon-doped silicon-oxygen composite material within the above range, the obtained electrochemical device has good cycle performance and expansion performance, and also has a high energy density.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料的粒径分布范围为0.2μm至20μm，Dv50为4μm至10μm，Dv99为13μm至20μm。通过将碳掺杂硅氧复合材料的粒径分布范围、Dv50和Dv99调控在上述范围内，有利于改善电化学装置的循环性能。In some embodiments of the present application, the particle size distribution range of the carbon-doped silicon-oxygen composite material is 0.2 μm to 20 μm, Dv50 is 4 μm to 10 μm, and Dv99 is 13 μm to 20 μm. By regulating the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material within the above range, it is beneficial to improve the cycle performance of the electrochemical device.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料的粉末电导率为0.03S/cm至8S/cm。碳掺杂硅氧复合材料具有上述范围的粉末电导率，有利于改善电化学装置的循环性能。In some embodiments of the present application, the carbon-doped silicon-oxygen composite material has a powder conductivity of 0.03 S/cm to 8 S/cm. The carbon-doped silicon-oxygen composite material has a powder conductivity within the above range, which is beneficial for improving the cycle performance of the electrochemical device.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料颗粒的所述内部区域形成Si-C键，所述表面区域形成Si-O-C键，有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, the internal region of the carbon-doped silicon-oxygen composite material particles forms Si-C bonds, and the surface region forms Si-O-C bonds, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料颗粒的所述表面区域的碳元素的质量含量占所述碳掺杂硅氧复合材料碳元素质量含量的10％至80％。通过调控表面区域的碳元素的质量含量占碳掺杂硅氧复合材料碳元素质量含量的占比在上述范围内，有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, the mass content of carbon in the surface region of the carbon-doped silicon-oxygen composite material particles accounts for 10% to 80% of the mass content of carbon in the carbon-doped silicon-oxygen composite material. By regulating the mass content of carbon in the surface region to account for the mass content of carbon in the carbon-doped silicon-oxygen composite material within the above range, it is beneficial to improve the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料颗粒中硅元素和氧元素分布均匀，有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, silicon and oxygen are evenly distributed in the carbon-doped silicon-oxygen composite material particles, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，所述石墨包括天然石墨、人造石墨或中间相碳微球等中的至少一种。通过选用上述石墨，有利于改善电化学装置的循环性能。In some embodiments of the present application, the graphite includes at least one of natural graphite, artificial graphite or mesophase carbon microspheres, etc. The selection of the above graphite is conducive to improving the cycle performance of the electrochemical device.
在本申请的一些实施方案中，所述碳掺杂硅氧复合材料与所述石墨的质量比为(3至20):(80至97)。通过将碳掺杂硅氧复合材料与石墨的质量比调控在上述范围内，有利于改善电化学装置的循环性能。In some embodiments of the present application, the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite is (3 to 20): (80 to 97). By regulating the mass ratio of the carbon-doped silicon-oxygen composite material to graphite within the above range, it is beneficial to improve the cycle performance of the electrochemical device.
在本申请的一些实施方案中，所述负极材料层还包括粘结剂，所述粘结剂包括聚丙烯酸酯、聚酰亚胺、聚酰胺、聚酰胺酰亚胺、聚偏氟乙烯、聚苯乙烯丁二烯共聚物、海藻酸钠、聚乙烯醇、聚四氟乙烯、聚丙烯腈、羧甲基纤维素钠、羧甲基纤维素钾、羟甲基纤维素钠或羟甲基纤维素钾中的至少一种。通过选择上述粘结剂，得到的负极材料层具有良好的结构稳定性，有利于提高电化学装置的循环性能。In some embodiments of the present application, the negative electrode material layer further includes a binder, and the binder includes at least one of polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, polystyrene butadiene copolymer, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose or potassium hydroxymethyl cellulose. By selecting the above binder, the obtained negative electrode material layer has good structural stability, which is conducive to improving the cycle performance of the electrochemical device.
本申请的第二方面提供了一种电化学装置，其包括前述任一实施方案中的负极极片。 因此，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。The second aspect of the present application provides an electrochemical device, which comprises the negative electrode sheet in any of the above embodiments. Therefore, the electrochemical device provided by the present application has good cycle performance and expansion performance.
本申请的第三方面提供了一种电子装置，其包括前述任一实施方案中的电化学装置。因此，本申请提供的电子装置具有良好的使用性能。The third aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
本申请提供了一种负极极片、电化学装置和电子装置，负极极片包括负极活性材料层，负极活性材料层包括负极活性材料，负极活性材料包括碳掺杂硅氧复合材料和石墨，碳掺杂硅氧复合材料包括碳元素、硅元素和氧元素，碳掺杂硅氧复合材料的颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，其中，表面区域为沿颗粒表面至内部深度为500nm的区域，内部区域为颗粒中除去表面区域以外的区域；其中，基于碳元素、硅元素和氧元素的质量总和，碳掺杂硅氧复合材料中碳元素的质量百分含量为2％至10％。负极极片中碳掺杂硅氧复合材料中碳元素的引入，且其颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，在颗粒内部形成Si-C键以及表面区域形成Si-O-C键，在Si-C键和Si-O-C键的协同作用下，能够限制循环过程中硅晶粒的生长，降低负极活性材料粉化的风险并改善其膨胀性能，还能够提升颗粒表面的稳定性，降低被电解液刻蚀的风险以改善电化学装置的循环性能。因而，本申请提供的负极极片具有良好的导电性，将其应用于电化学装置中，能够改善电化学装置的循环性能和膨胀性能。The present application provides a negative electrode plate, an electrochemical device and an electronic device, wherein the negative electrode plate comprises a negative electrode active material layer, the negative electrode active material layer comprises a negative electrode active material, the negative electrode active material comprises a carbon-doped silicon-oxygen composite material and graphite, the carbon-doped silicon-oxygen composite material comprises carbon, silicon and oxygen, the carbon content in the surface region of particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal region of the particles, wherein the surface region is a region from the surface of the particle to a depth of 500 nm, and the internal region is a region of the particle excluding the surface region; wherein, based on the total mass of the carbon, silicon and oxygen, the mass percentage of the carbon in the carbon-doped silicon-oxygen composite material is 2% to 10%. The introduction of carbon elements in the carbon-doped silicon-oxygen composite material in the negative electrode plate, and the carbon element content in the surface area of the particles is greater than the carbon element content in the internal area of the particles, Si-C bonds are formed inside the particles and Si-O-C bonds are formed in the surface area. Under the synergistic effect of Si-C bonds and Si-O-C bonds, the growth of silicon grains during the cycle process can be limited, the risk of pulverization of the negative electrode active material can be reduced and its expansion performance can be improved, and the stability of the particle surface can be improved, and the risk of being etched by the electrolyte can be reduced to improve the cycle performance of the electrochemical device. Therefore, the negative electrode plate provided by the present application has good conductivity, and its application in an electrochemical device can improve the cycle performance and expansion performance of the electrochemical device.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
为了更清楚地说明本申请实施例的技术方案，下面对实施例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，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.
图1为本申请一些实施例中的碳掺杂硅氧复合材料颗粒的结构示意图；FIG1 is a schematic diagram of the structure of carbon-doped silicon-oxygen composite particles in some embodiments of the present application;
图2为实施例1-1中的碳掺杂硅氧复合材料的X射线能谱仪(EDS)图像；FIG2 is an X-ray energy dispersive spectrometer (EDS) image of the carbon-doped silicon-oxygen composite material in Example 1-1;
图3为图1中的EDS分层图像对应的氧元素在碳掺杂硅氧复合材料中的分布图像；FIG3 is a distribution image of oxygen element in a carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG1 ;
图4为图1中的EDS分层图像对应的硅元素在碳掺杂硅氧复合材料中的分布图像；FIG4 is a distribution image of silicon in a carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG1 ;
图5为图1中的EDS分层图像对应的碳元素在碳掺杂硅氧复合材料中的分布图像。FIG. 5 is a distribution image of carbon element in the carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in FIG. 1 .
具体实施方式Detailed ways
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，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在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。In order to make the purpose, technical solution, and advantages of the present application more clearly understood, the present application is further described in detail with reference to the accompanying drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.
需要说明的是，在以下内容中，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。具体技术方案如下：It should be noted that in the following content, lithium-ion batteries are used as an example of electrochemical devices to explain the present application, but the electrochemical devices of the present application are not limited to lithium-ion batteries. The specific technical solution is as follows:
本申请第一方面提供了一种负极极片，其包括负极活性材料层，负极活性材料层包括负极活性材料，负极活性材料包括碳掺杂硅氧复合材料和石墨，碳掺杂硅氧复合材料包括碳元素、硅元素和氧元素，碳掺杂硅氧复合材料的颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，其中，表面区域为沿颗粒表面至内部深度为500nm的区域，内部区域为颗粒中除去表面区域以外的区域；其中，基于碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量总和，碳掺杂硅氧复合材料中碳元素的质量百分含量为2％至10％。示例性地，图1示出了本申请一些实施例中碳掺杂硅氧复合材料的颗粒10的结构示意图，颗粒10包括表面区域12和内部区域13，颗粒10内部的箭头所示方向为沿颗粒10表面11向颗粒10内部延伸的方向，图中所示的距离d为沿颗粒10表面11向颗粒10内部延伸的深度，表面区域12即为沿颗粒10表面11至内部深度d为500nm的区域，内部区域13为颗粒10中除去表面区域11以外的区域。The first aspect of the present application provides a negative electrode plate, which includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes a carbon-doped silicon-oxygen composite material and graphite, the carbon-doped silicon-oxygen composite material includes carbon, silicon and oxygen, the carbon content in the surface area of the particles of the carbon-doped silicon-oxygen composite material is greater than the carbon content in the internal area of the particles, wherein the surface area is an area from the surface of the particle to a depth of 500nm, and the internal area is an area in the particle excluding the surface area; wherein, based on the total mass of the carbon element, silicon element and oxygen element in the carbon-doped silicon-oxygen composite material, the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is 2% to 10%. Exemplarily, Figure 1 shows a schematic structural diagram of a particle 10 of a carbon-doped silicon-oxygen composite material in some embodiments of the present application, wherein the particle 10 includes a surface region 12 and an internal region 13, and the direction indicated by the arrow inside the particle 10 is the direction extending from the surface 11 of the particle 10 to the interior of the particle 10, and the distance d shown in the figure is the depth extending from the surface 11 of the particle 10 to the interior of the particle 10, and the surface region 12 is the region from the surface 11 of the particle 10 to the internal depth d of 500 nm, and the internal region 13 is the region of the particle 10 excluding the surface region 11.
负极极片中碳掺杂硅氧复合材料中碳元素的引入，且碳掺杂硅氧复合材料颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，在颗粒内部区域形成Si-C键以及表面区域形成Si-O-C键，在Si-C键和Si-O-C键的协同作用下，可以限制循环过程中颗粒内部硅晶粒的生长，降低负极活性材料粉化的风险并改善其膨胀性能，还能够提升颗粒表面的稳定性，降低被电解液刻蚀的风险以改善电化学装置的循环性能。从而，本申请提供的负极极片中的碳掺杂硅氧复合材料在循环过程中不易粉化，负极极片具有良好的导电性，而且负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，将本申请提供的负极极片应用于电化学装置中，能够改善电化学装置的循环性能和膨胀性能。The introduction of carbon elements in the carbon-doped silicon-oxygen composite material in the negative electrode plate, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and Si-C bonds are formed in the internal area of the particles and Si-O-C bonds are formed in the surface area. Under the synergistic effect of Si-C bonds and Si-O-C bonds, the growth of silicon grains inside the particles during the cycle can be limited, the risk of pulverization of the negative electrode active material can be reduced, and its expansion performance can be improved. The stability of the particle surface can also be improved, and the risk of being etched by the electrolyte can be reduced to improve the cycle performance of the electrochemical device. Therefore, the carbon-doped silicon-oxygen composite material in the negative electrode plate provided by the present application is not easy to pulverize during the cycle, the negative electrode plate has good conductivity, and the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize. The negative electrode plate provided by the present application is applied to an electrochemical device, which can improve the cycle performance and expansion performance of the electrochemical device.
具体地，碳掺杂硅氧复合材料中碳元素的质量百分含量可以为2％、3％、4％、5％、6％、7％、8％、9％、10％或为上述任意两个数值组成的范围。当碳掺杂硅氧复合材料中碳元素的质量百分含量过低时，例如低于2％，在碳掺杂硅氧复合材料颗粒内部形成Si-C键和颗粒表面区域形成的Si-O-C键较少，不能有效限制循环过程中硅晶粒的生长，对颗粒表面的稳定性改善不明显，颗粒在充放电循环过程中容易粉化且影响颗粒的膨胀性能以及负极极片的导电性。当碳掺杂硅氧复合材料中碳元素的质量百分含量过高时，例如高于10％，会影响碳掺杂硅氧复合材料的克容量和首次库伦效率，进而影响电化学装置的能量密度。将碳掺杂硅氧复合材料中碳元素的质量百分含量调控在上述范围内，负极极片中的碳掺杂 硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，使得电化学装置具有较高能量密度的同时，还有利于改善电化学装置的循环性能和膨胀性能。Specifically, the mass percentage of carbon in the carbon-doped silicon-oxygen composite material can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or a range consisting of any two of the above values. When the mass percentage of carbon in the carbon-doped silicon-oxygen composite material is too low, for example, less than 2%, the Si-C bonds formed inside the carbon-doped silicon-oxygen composite material particles and the Si-O-C bonds formed on the surface of the particles are less, and the growth of silicon grains during the cycle cannot be effectively restricted. The stability of the particle surface is not significantly improved, and the particles are easily pulverized during the charge and discharge cycle, which affects the expansion performance of the particles and the conductivity of the negative electrode. When the mass percentage of carbon in the carbon-doped silicon-oxygen composite material is too high, for example, higher than 10%, it will affect the gram capacity and first coulomb efficiency of the carbon-doped silicon-oxygen composite material, and thus affect the energy density of the electrochemical device. By controlling the mass percentage of carbon element in the carbon-doped silicon-oxygen composite material within the above range, the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize, and the negative electrode plate has good conductivity, which makes the electrochemical device have a higher energy density and is also beneficial to improving the cycle performance and expansion performance of the electrochemical device.
整体而言，本申请提供的负极极片中碳掺杂硅氧复合材料中碳元素的引入，且碳掺杂硅氧复合材料颗粒的表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，以及调控碳掺杂硅氧复合材料中碳元素的质量百分含量在上述范围内，负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，从而有利于改善电化学装置的循环性能和膨胀性能。In general, the carbon element is introduced into the carbon-doped silicon-oxygen composite material in the negative electrode pole piece provided in the present application, and the carbon element content in the surface area of the carbon-doped silicon-oxygen composite material particles is greater than the carbon element content in the internal area of the particles, and the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is regulated within the above-mentioned range. The carbon-doped silicon-oxygen composite material in the negative electrode pole piece has good expansion properties and is not easy to pulverize, and the negative electrode pole piece has good conductivity, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，基于碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量总和，表面区域中碳元素的质量百分含量为0.5％至8％。例如，表面区域中碳元素的质量百分含量可以为0.5％、2％、4％、6％、8％或为上述任意两个数值组成的范围。通过调控碳掺杂硅氧复合材料表面区域中碳元素的质量百分含量在上述范围内，负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，从而有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, based on the total mass of carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of carbon in the surface region is 0.5% to 8%. For example, the mass percentage of carbon in the surface region can be 0.5%, 2%, 4%, 6%, 8% or a range consisting of any two of the above values. By regulating the mass percentage of carbon in the surface region of the carbon-doped silicon-oxygen composite material within the above range, the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion properties and is not easy to pulverize, and the negative electrode plate has good conductivity, which is beneficial to improve the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，基于碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量总和，碳掺杂硅氧复合材料中硅元素的质量百分含量为40％至60％。例如，碳掺杂硅氧复合材料中硅元素的质量百分含量可以为40％、45％、50％、55％、60％或为上述任意两个数值组成的范围。通过调控碳掺杂硅氧复合材料中硅元素的质量百分含量在上述范围内，能够发挥硅材料高容量的特点，同时负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，负极极片具有良好的导电性，从而得到的电化学装置在具有良好的循环性能和膨胀性能的同时，还具有较高的能量密度。In some embodiments of the present application, based on the sum of the masses of carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of silicon in the carbon-doped silicon-oxygen composite material is 40% to 60%. For example, the mass percentage of silicon in the carbon-doped silicon-oxygen composite material can be 40%, 45%, 50%, 55%, 60% or a range consisting of any two of the above values. By regulating the mass percentage of silicon in the carbon-doped silicon-oxygen composite material within the above range, the high capacity of silicon materials can be brought into play. At the same time, the carbon-doped silicon-oxygen composite material in the negative electrode has good expansion properties and is not easy to pulverize. The negative electrode has good conductivity, so that the electrochemical device obtained has good cycle performance and expansion performance while also having a high energy density.
在本申请中，基于碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量总和，碳掺杂硅氧复合材料中氧元素的质量百分含量为：100％－(硅元素的质量百分含量+碳元素的质量百分含量)。需要说明的是，碳掺杂硅氧复合材料中通常会包含一些含量较低(例如质量百分含量小于或等于0.1％)的杂质元素，本申请在计算碳元素、硅元素和氧元素的质量百分含量时不考虑上述杂质元素。In the present application, based on the sum of the masses of carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of oxygen in the carbon-doped silicon-oxygen composite material is: 100% - (mass percentage of silicon + mass percentage of carbon). It should be noted that the carbon-doped silicon-oxygen composite material usually contains some impurity elements with a relatively low content (for example, the mass percentage is less than or equal to 0.1%), and the present application does not consider the above impurity elements when calculating the mass percentage of carbon, silicon and oxygen.
本申请对表面区域中硅元素和氧元素的质量百分含量没有特别限制，只要能实现本申请的目的即可，例如，基于碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量总和，表面区域中硅元素的质量百分含量可以为0.5％至8％，表面区域中氧元素的质量百分含量可以为20％至40％。The present application has no particular restriction on the mass percentage of silicon and oxygen in the surface region, as long as the purpose of the present application can be achieved. For example, based on the total mass of carbon, silicon and oxygen in the carbon-doped silicon-oxygen composite material, the mass percentage of silicon in the surface region can be 0.5% to 8%, and the mass percentage of oxygen in the surface region can be 20% to 40%.
在本申请的一些实施方案中，碳掺杂硅氧复合材料的粒径分布范围为0.2μm至20μm，Dv50为4μm至10μm，Dv99为13μm至20μm。例如，粒径分布范围可以为0.2μm至20μm、0.3μm至20μm、0.4μm至20μm、0.5μm至20μm、0.6μm至20μm中的任一范围，Dv50可以为4μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、9μm、10μm或为上述任意两个数值组成的范围，Dv99可以为13μm、14μm、15μm、17μm、17μm、18μm、19μm、20μm或为上述任意两个数值组成的范围。通过将碳掺杂硅氧复合材料的粒径分布范围、Dv50和Dv99调控在上述范围内，能够减少碳掺杂硅氧复合材料与电解液之间的副反应，以缓解碳掺杂硅氧复合材料的体积变化，增强碳掺杂硅氧复合材料的抗压强度，进一步增加负极极片的结构稳定性，从而有利于改善电化学装置的循环性能。In some embodiments of the present application, the particle size distribution range of the carbon-doped silicon-oxygen composite material is 0.2 μm to 20 μm, Dv50 is 4 μm to 10 μm, and Dv99 is 13 μm to 20 μm. For example, the particle size distribution range can be any range of 0.2 μm to 20 μm, 0.3 μm to 20 μm, 0.4 μm to 20 μm, 0.5 μm to 20 μm, and 0.6 μm to 20 μm, Dv50 can be 4 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 9 μm, 10 μm, or a range consisting of any two of the above values, and Dv99 can be 13 μm, 14 μm, 15 μm, 17 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range consisting of any two of the above values. By regulating the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material within the above range, the side reaction between the carbon-doped silicon-oxygen composite material and the electrolyte can be reduced, thereby alleviating the volume change of the carbon-doped silicon-oxygen composite material, enhancing the compressive strength of the carbon-doped silicon-oxygen composite material, and further increasing the structural stability of the negative electrode sheet, which is beneficial to improving the cycle performance of the electrochemical device.
在本申请中，Dv50表示在材料的体积基准的粒度分布中，从小粒径测起，到达体积累积50％的粒径，Dv99表示在材料的体积基准的粒度分布中，从小粒径测起，到达体积累积99％的粒径。In this application, Dv50 means the particle size reaching 50% of the volume accumulation in the volume-based particle size distribution of the material, measured from the smallest particle size, and Dv99 means the particle size reaching 99% of the volume accumulation in the volume-based particle size distribution of the material, measured from the smallest particle size.
在本申请的一些实施方案中，碳掺杂硅氧复合材料的粉末电导率为0.03S/cm至8S/cm。例如，碳掺杂硅氧复合材料的粉末电导率可以为0.03S/cm、0.05S/cm、0.1S/cm、0.5S/cm、1S/cm、1.5S/cm、2S/cm、3S/cm、4S/cm、5S/cm、6S/cm、7S/cm、8S/cm或为上述任意两个数值组成的范围。碳掺杂硅氧复合材料具有上述范围的粉末电导率，能够有效控制负极极片与电解液之间界面的电流密度，使得负极极片不易出现析锂现象，有利于改善电化学装置的循环性能。In some embodiments of the present application, the powder conductivity of the carbon-doped silicon-oxygen composite material is 0.03S/cm to 8S/cm. For example, the powder conductivity of the carbon-doped silicon-oxygen composite material can be 0.03S/cm, 0.05S/cm, 0.1S/cm, 0.5S/cm, 1S/cm, 1.5S/cm, 2S/cm, 3S/cm, 4S/cm, 5S/cm, 6S/cm, 7S/cm, 8S/cm or a range consisting of any two of the above values. The carbon-doped silicon-oxygen composite material has a powder conductivity in the above range, which can effectively control the current density at the interface between the negative electrode plate and the electrolyte, making it less likely for the negative electrode plate to undergo lithium precipitation, which is beneficial to improving the cycle performance of the electrochemical device.
在本申请的一些实施方案中，碳掺杂硅氧复合材料颗粒的表面区域的碳元素的质量含量占碳掺杂硅氧复合材料碳元素质量含量的10％至80％。例如，表面区域的碳元素的质量含量占碳掺杂硅氧复合材料碳元素质量含量的占比可以为10％、20％、30％、40％、50％、60％、70％、80％或为上述任意两个数值组成的范围。当上述占比在上述范围内时可以限制循环过程中颗粒内部硅晶粒的生长，降低负极活性材料粉化的风险并改善其膨胀性能，还能够提升颗粒表面的稳定性，降低被电解液刻蚀的风险以改善电化学装置的循环性能。从而，本申请提供的负极极片中的碳掺杂硅氧复合材料在循环过程中不易粉化，负极极片具有良好的导电性，而且负极极片中的碳掺杂硅氧复合材料具有良好的膨胀性能且不易粉化，将本申请提供的负极极片应用于电化学装置中，能够改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, the mass content of carbon elements in the surface area of the carbon-doped silicon-oxygen composite material particles accounts for 10% to 80% of the mass content of carbon elements in the carbon-doped silicon-oxygen composite material. For example, the mass content of carbon elements in the surface area accounts for 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or a range composed of any two of the above values. When the above proportion is within the above range, the growth of silicon grains inside the particles during the cycle can be limited, the risk of pulverization of the negative electrode active material can be reduced and its expansion performance can be improved, and the stability of the particle surface can be improved, and the risk of being etched by the electrolyte can be reduced to improve the cycle performance of the electrochemical device. Thus, the carbon-doped silicon-oxygen composite material in the negative electrode plate provided by the present application is not easy to pulverize during the cycle, the negative electrode plate has good conductivity, and the carbon-doped silicon-oxygen composite material in the negative electrode plate has good expansion performance and is not easy to pulverize. The negative electrode plate provided by the present application is applied to the electrochemical device, which can improve the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，碳掺杂硅氧复合材料颗粒中硅元素和氧元素分布均匀， 有利于改善电化学装置的循环性能和膨胀性能。In some embodiments of the present application, silicon and oxygen are evenly distributed in the carbon-doped silicon-oxygen composite material particles, which is beneficial to improving the cycle performance and expansion performance of the electrochemical device.
在本申请的一些实施方案中，石墨包括天然石墨、人造石墨或中间相碳微球等中的至少一种。通过选用上述石墨材料，有利于改善电化学装置的循环性能。In some embodiments of the present application, the graphite includes at least one of natural graphite, artificial graphite or mesophase carbon microspheres, etc. The selection of the above graphite materials is beneficial to improve the cycle performance of the electrochemical device.
在本申请的一些实施方案中，碳掺杂硅氧复合材料与石墨的质量比为(3至20):(80至97)。例如，碳掺杂硅氧复合材料与所述石墨的质量比可以为20:80、18:82、15:85、12:88、10:90、7:93、6:94、5:95、4:96、3:97或为上述任意两个比值组成的范围。通过将碳掺杂硅氧复合材料与石墨的质量比调控在上述范围内，能够使负极活性材料层保持高的克容量，同时降低硅与电解液直接接触的概率以减少硅与电解液之间的副反应和固体电解质界面(SEI)膜的形成，缓解硅的体积膨胀，并且石墨可以增加负极极片的导电性，从而有利于协同改善电化学装置的循环性能。In some embodiments of the present application, the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite is (3 to 20): (80 to 97). For example, the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite can be 20:80, 18:82, 15:85, 12:88, 10:90, 7:93, 6:94, 5:95, 4:96, 3:97 or a range consisting of any two of the above ratios. By regulating the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite within the above range, the negative electrode active material layer can maintain a high gram capacity, while reducing the probability of direct contact between silicon and the electrolyte to reduce the side reactions between silicon and the electrolyte and the formation of a solid electrolyte interface (SEI) film, alleviating the volume expansion of silicon, and graphite can increase the conductivity of the negative electrode plate, thereby facilitating a synergistic improvement in the cycle performance of the electrochemical device.
在本申请的一些实施方案中，负极材料层还包括粘结剂，粘结剂包括聚丙烯酸酯、聚酰亚胺、聚酰胺、聚酰胺酰亚胺、聚偏氟乙烯、聚苯乙烯丁二烯共聚物(丁苯橡胶)、海藻酸钠、聚乙烯醇、聚四氟乙烯、聚丙烯腈、羧甲基纤维素钠、羧甲基纤维素钾、羟甲基纤维素钠或羟甲基纤维素钾中的至少一种。通过选择上述粘结剂，得到的负极材料层具有良好的结构稳定性，有利于提高电化学装置的循环性能。In some embodiments of the present application, the negative electrode material layer also includes a binder, and the binder includes at least one of polyacrylate, polyimide, polyamide, polyamide-imide, polyvinylidene fluoride, polystyrene butadiene copolymer (styrene-butadiene rubber), sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose or potassium hydroxymethyl cellulose. By selecting the above-mentioned binder, the obtained negative electrode material layer has good structural stability, which is conducive to improving the cycle performance of the electrochemical device.
在本申请中，负极活性材料层还可以包括导电剂，本申请对导电剂没有特别限制，只要能够实现本申请目的即可，例如导电剂可以包括导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、科琴黑或石墨烯等中的至少一种。本申请对负极活性材料层中负极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。In the present application, the negative electrode active material layer may further include a conductive agent. The present application has no particular restrictions on the conductive agent, as long as the purpose of the present application can be achieved. For example, the conductive agent may include at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fiber, flake graphite, Ketjen black or graphene. The present application has no particular restrictions on the mass ratio of the negative electrode active material, the conductive agent and the binder in the negative electrode active material layer. Those skilled in the art may select according to actual needs, as long as the purpose of the present application can be achieved.
本申请的负极极片包括负极集流体，负极活性材料层设置于负极集流体至少一个表面上。上述“负极活性材料层设置于负极集流体至少一个表面上”是指，负极活性材料层可以设置于负极集流体沿自身厚度方向上的一个表面上，也可以设置于负极集流体沿自身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，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(例如碳铜复合集流体、镍铜复合集流体、钛铜复合集流体等)等。本申请对负极集流体和负极活性材料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，负极集流体的厚度为6μm至12μm， 负极活性材料层的厚度为30μm至120μm。申请对负极极片的厚度没有特别限制，只要能够实现本申请目的即可，例如，负极极片的厚度为50μm至150μm。The negative electrode sheet of the present application includes a negative electrode current collector, and a negative electrode active material layer is arranged on at least one surface of the negative electrode current collector. The above-mentioned "negative electrode active material layer is arranged on at least one surface of the negative electrode current collector" means that the negative electrode active material layer can be arranged on one surface of the negative electrode current collector along its own thickness direction, or it can be arranged on two surfaces of the negative electrode current collector along its own thickness direction. It should be noted that 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. This application has no special restrictions, as long as the purpose of this application can be achieved. This application has no special restrictions on the negative electrode current collector, as long as the purpose of this application can be achieved. For example, it can include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or composite current collector (such as carbon copper composite current collector, nickel copper composite current collector, titanium copper composite current collector, etc.). The present application has no particular restrictions on the thickness of the negative electrode current collector and the negative electrode active material layer, as long as the purpose of the present application can be achieved, for example, the thickness of the negative electrode current collector is 6 μm to 12 μm, and the thickness of the negative electrode active material layer is 30 μm to 120 μm. The application has no particular restrictions on the thickness of the negative electrode sheet, as long as the purpose of the present application can be achieved, for example, the thickness of the negative electrode sheet is 50 μm to 150 μm.
任选地，负极极片还可以包含导电层，导电层位于负极集流体和负极活性材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层。例如，导电层包括导电剂和粘结剂。本申请对导电层中的导电剂和粘结剂没有特别限制，例如可以是上述导电剂和上述粘结剂中的至少一种。Optionally, the negative electrode plate may further include a conductive layer, which is located between the negative electrode current collector and the negative electrode active material layer. The present application has no particular restrictions on the composition of the conductive layer, which may be a conductive layer commonly used in the art. For example, the conductive layer includes a conductive agent and a binder. The present application has no particular restrictions on the conductive agent and the binder in the conductive layer, which may be, for example, at least one of the above conductive agent and the above binder.
本申请对碳掺杂硅氧复合材料的制备方法没有特别限制，示例性地，碳掺杂硅氧复合材料的制备方法可以包括但不限于以下步骤：将碳掺杂硅氧材料与有机硅溶液混合均匀后烘干，然后在惰性气氛下进行热处理得到碳掺杂硅氧复合材料。其中，烘干的温度为80℃至120℃；热处理的温度为600℃至1000℃，热处理的升温速率为1℃/min至10℃/min，热处理的保温时间为1h至6h；有机硅溶液包括有机硅和溶剂，有机硅可以包括但不限于四甲基-四乙烯基-环四硅氧烷或聚甲基氢硅氧烷等中的至少一种，溶剂可以包括但不限于乙醇等，有机硅和溶剂的质量比可以为1:(2至6)；惰性气氛可以为氩气和/或氮气。The present application does not particularly limit the preparation method of the carbon-doped silicon-oxygen composite material. For example, the preparation method of the carbon-doped silicon-oxygen composite material may include but is not limited to the following steps: the carbon-doped silicon-oxygen material and the organosilicon solution are mixed evenly and then dried, and then heat-treated under an inert atmosphere to obtain the carbon-doped silicon-oxygen composite material. Wherein, the drying temperature is 80°C to 120°C; the heat treatment temperature is 600°C to 1000°C, the heating rate of the heat treatment is 1°C/min to 10°C/min, and the heat preservation time of the heat treatment is 1h to 6h; the organosilicon solution includes organosilicon and solvent, the organosilicon may include but is not limited to at least one of tetramethyl-tetravinyl-cyclotetrasiloxane or polymethylhydrogensiloxane, etc., the solvent may include but is not limited to ethanol, etc., and the mass ratio of organosilicon to solvent may be 1: (2 to 6); the inert atmosphere may be argon and/or nitrogen.
通常情况下，可以通过改变热处理的温度、升温速率和保温时间来调控碳掺杂硅氧复合材料中碳元素、硅元素和氧元素的质量百分含量。例如，提高热处理温度，碳掺杂硅氧复合材料中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低；降低热处理温度，碳掺杂硅氧复合材料中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧元素的质量百分含量升高。提高升温速率，碳掺杂硅氧复合材料中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧元素的质量百分含量升高；降低升温速率，碳掺杂硅氧复合材料中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低。延长热处理的保温时间，碳掺杂硅氧复合材料中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低；缩短热处理的保温时间，碳掺杂硅氧复合材料中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧元素的质量百分含量升高。Generally, the mass percentage of carbon, silicon and oxygen in carbon-doped silicon-oxygen composite materials can be controlled by changing the temperature, heating rate and holding time of heat treatment. For example, by increasing the heat treatment temperature, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials increases, the mass percentage of silicon increases, and the mass percentage of oxygen decreases; by reducing the heat treatment temperature, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials decreases, the mass percentage of silicon decreases, and the mass percentage of oxygen increases. By increasing the heating rate, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials decreases, the mass percentage of silicon decreases, and the mass percentage of oxygen increases; by reducing the heating rate, the mass percentage of carbon in carbon-doped silicon-oxygen composite materials increases, the mass percentage of silicon increases, and the mass percentage of oxygen decreases. By extending the holding time of the heat treatment, the mass percentage of carbon element in the carbon-doped silicon-oxygen composite material increases, the mass percentage of silicon element increases, and the mass percentage of oxygen element decreases; by shortening the holding time of the heat treatment, the mass percentage of carbon element in the carbon-doped silicon-oxygen composite material decreases, the mass percentage of silicon element decreases, and the mass percentage of oxygen element increases.
改变热处理的温度、升温速率和保温时间还可以调控表面区域中碳元素、硅元素和氧元素的质量百分含量。例如，提高热处理温度，表面区域中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低；降低热处理温度，表面区域中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧元素的质量百分含量升高。提高升温速率，表面区域中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧 元素的质量百分含量升高；降低升温速率，表面区域中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低。延长热处理的保温时间，表面区域中碳元素的质量百分含量升高，硅元素的质量百分含量升高，氧元素的质量百分含量降低；缩短热处理的保温时间，表面区域中碳元素的质量百分含量降低，硅元素的质量百分含量降低，氧元素的质量百分含量升高。Changing the temperature, heating rate and holding time of the heat treatment can also regulate the mass percentage of carbon, silicon and oxygen in the surface area. For example, increasing the heat treatment temperature increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen; decreasing the heat treatment temperature decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen. Increasing the heating rate decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen; decreasing the heating rate increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen. Prolonging the holding time of the heat treatment increases the mass percentage of carbon in the surface area, increases the mass percentage of silicon, and decreases the mass percentage of oxygen; shortening the holding time of the heat treatment decreases the mass percentage of carbon in the surface area, decreases the mass percentage of silicon, and increases the mass percentage of oxygen.
改变热处理的温度、升温速率和保温保温时间还可以调控碳掺杂硅氧复合材料的粒径分布范围、Dv50和Dv99。例如，提高热处理温度，碳掺杂硅氧复合材料的粒径分布范围变宽，Dv50增大，Dv99增大；降低热处理温度，碳掺杂硅氧复合材料的粒径分布范围变窄，Dv50减小，Dv99减小。提高升温速率，碳掺杂硅氧复合材料的粒径分布范围变窄，Dv50减小，Dv99减小；降低升温速率，碳掺杂硅氧复合材料的粒径分布范围变宽，Dv50增大，Dv99增大。延长热处理的保温时间，碳掺杂硅氧复合材料的粒径分布范围变宽，Dv50增大，Dv99增大；缩短热处理的保温时间，碳掺杂硅氧复合材料的粒径分布范围变窄，Dv50减小，Dv99减小。Changing the temperature, heating rate and heat preservation time of the heat treatment can also regulate the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material. For example, by increasing the heat treatment temperature, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases; by reducing the heat treatment temperature, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases. By increasing the heating rate, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases; by reducing the heating rate, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases. By extending the heat preservation time of the heat treatment, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes wider, Dv50 increases, and Dv99 increases; by shortening the heat preservation time of the heat treatment, the particle size distribution range of the carbon-doped silicon-oxygen composite material becomes narrower, Dv50 decreases, and Dv99 decreases.
本申请对上述碳掺杂硅氧材料的制备方法没有特别限制，只要能实现本申请的目的即可，例如，碳掺杂硅氧材料的制备方法可以包括但不限于以下步骤：将硅和二氧化硅混合均匀并装入真空沉积炉中，控制温度为1300℃至1350℃且真空度在1Pa至100Pa，通入适量的碳源气体(例如甲烷、乙炔、乙烯等)，得到碳掺杂硅氧材料。碳掺杂硅氧材料中碳元素、硅元素、氧元素的含量可以通过硅和二氧化硅和混合比例以及通入的碳源气体的含量来调控，例如，硅与二氧化硅的混合比例增大，硅元素的含量增加，氧元素含量降低；硅与二氧化硅的混合比例减小，硅元素的含量降低，氧元素的含量增加；通入的碳源气体增多，碳元素的含量增加；通入的碳源气体的含量减少，碳元素的含量降低。The present application has no particular restrictions on the preparation method of the above-mentioned carbon-doped silicon-oxygen material, as long as the purpose of the present application can be achieved. For example, the preparation method of the carbon-doped silicon-oxygen material may include but is not limited to the following steps: silicon and silicon dioxide are mixed evenly and loaded into a vacuum deposition furnace, the temperature is controlled to be 1300°C to 1350°C and the vacuum degree is 1Pa to 100Pa, and an appropriate amount of carbon source gas (such as methane, acetylene, ethylene, etc.) is introduced to obtain a carbon-doped silicon-oxygen material. The contents of carbon, silicon, and oxygen in the carbon-doped silicon-oxygen material can be regulated by the mixing ratio of silicon and silicon dioxide and the content of the carbon source gas introduced. For example, the content of silicon increases and the content of oxygen decreases as the mixing ratio of silicon and silicon dioxide increases; the content of silicon decreases and the content of oxygen increases as the mixing ratio of silicon and silicon dioxide decreases; the content of carbon increases as the carbon source gas introduced increases; the content of carbon decreases as the carbon source gas introduced decreases.
示例性地，在本申请中，基于碳掺杂硅氧材料的总质量，碳元素的质量百分含量为2％至10％，硅元素的质量百分含量为40％至60％，氧元素的质量百分含量为30％至50％。需要说明的是，碳掺杂硅氧材料通常会包含一些含量较低(例如质量百分含量小于或等于0.1％)的杂质元素，本申请在计算碳掺杂硅氧材料中的碳元素、硅元素、氧元素的质量百分含量时，“基于碳掺杂硅氧材料的总质量”是指将上述杂质元素排除后得到的总质量，进而得到碳元素、硅元素、氧元素的质量百分含量。For example, in the present application, based on the total mass of the carbon-doped silicon-oxygen material, the mass percentage of carbon is 2% to 10%, the mass percentage of silicon is 40% to 60%, and the mass percentage of oxygen is 30% to 50%. It should be noted that the carbon-doped silicon-oxygen material usually contains some impurity elements with a relatively low content (for example, the mass percentage is less than or equal to 0.1%). When calculating the mass percentage of carbon, silicon, and oxygen in the carbon-doped silicon-oxygen material, the present application refers to the total mass obtained after excluding the above-mentioned impurity elements, and then obtaining the mass percentage of carbon, silicon, and oxygen.
本申请可以通过粒径分级获得不同粒径分布的碳掺杂硅氧材料。本申请对粒径分级方法没有特别限制，只要能得到符合本申请粒径要求的材料即可，例如，可以通过研磨并进 行粒径筛分从而获取具有不同粒径分布的碳掺杂硅氧复合材料。The present application can obtain carbon-doped silicon-oxygen materials with different particle size distributions by particle size classification. The present application has no particular restrictions on the particle size classification method, as long as a material that meets the particle size requirements of the present application can be obtained. For example, a carbon-doped silicon-oxygen composite material with different particle size distributions can be obtained by grinding and performing particle size screening.
本申请对调控碳掺杂硅氧复合材料的粉末电导率的方法没有特别限制，只要能实现本申请目的即可，例如，可以通过调控碳元素的质量百分含量来调控碳掺杂硅氧复合材料的电导率。通常情况下，碳掺杂硅氧复合材料中的粉末电导率随其中碳元素的质量百分含量的增加而提高，随其中碳元素的质量百分含量的降低而降低。The present application has no particular restrictions on the method for regulating the powder conductivity of the carbon-doped silicon-oxygen composite material, as long as the purpose of the present application can be achieved. For example, the conductivity of the carbon-doped silicon-oxygen composite material can be regulated by regulating the mass percentage of the carbon element. Generally, the powder conductivity of the carbon-doped silicon-oxygen composite material increases with the increase of the mass percentage of the carbon element therein, and decreases with the decrease of the mass percentage of the carbon element therein.
本申请的第二方面提供了一种电化学装置，其包括前述任一实施方案中的负极极片。因此，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。The second aspect of the present application provides an electrochemical device, which comprises the negative electrode sheet in any of the above embodiments. Therefore, the electrochemical device provided by the present application has good cycle performance and expansion performance.
在本申请中，电化学装置还包括正极极片，正极极片包括正极集流体以及设置于正极集流体至少一个表面上的正极活性材料层。上述“设置于正极集流体至少一个表面上的正极活性材料层”是指，正极活性材料层可以设置于正极集流体沿自身厚度方向上的一个表面上，也可以设置于正极集流体沿自身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，可以包含铝箔、铝合金箔或复合集流体(例如铝碳复合集流体)等。正极活性材料层包括正极活性材料，本申请对正极活性材料没有特别限制，只要能够实现本申请目的即可，例如，正极活性材料可以包含镍钴锰酸锂(例如常见的NCM811、NCM622、NCM523、NCM111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂(LiCoO 2)、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。正极活性材料层还包括导电剂和粘结剂，本申请对导电剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可，例如，可以是上述导电剂和上述粘结剂中的至少一种。本申请对正极活性材料层中正极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。本申请对正极集流体和正极材料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6μm至12μm，正极材料层的厚度为30μm至120μm。申请对正极极片的厚度没有特别限制，只要能够实现本申请目的即可，例如，正极极片的厚度为50μm至150μm。 In the present application, the electrochemical device also includes a positive electrode plate, which includes a positive electrode collector and a positive electrode active material layer disposed on at least one surface of the positive electrode collector. The above-mentioned "positive electrode active material layer disposed on at least one surface of the positive electrode collector" means that the positive electrode active material layer can be disposed on one surface of the positive electrode collector along the thickness direction of itself, or on two surfaces of the positive electrode collector along the thickness direction of itself. It should be noted that the "surface" here can be the entire area of the positive electrode collector or a partial area of the positive electrode collector. This application has no special restrictions, as long as the purpose of this application can be achieved. This application has no special restrictions on the positive electrode collector, as long as the purpose of this application can be achieved. For example, it can include aluminum foil, aluminum alloy foil or a composite current collector (such as an aluminum-carbon composite current collector). The positive electrode active material layer includes a positive electrode active material. The present application has no particular restrictions on the positive electrode active material, as long as the purpose of the present application can be achieved. For example, the positive electrode active material may include at least one of nickel cobalt manganese oxide (such as common NCM811, NCM622, NCM523, NCM111), nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide (LiCoO 2 ), lithium manganate, lithium iron manganese phosphate or lithium titanate. The positive electrode active material layer also includes a conductive agent and a binder. The present application has no particular restrictions on the types of conductive agents and binders, as long as the purpose of the present application can be achieved. For example, it can be at least one of the above conductive agents and the above binders. The present application has no particular restrictions on the mass ratio of the positive electrode active material, conductive agent and binder in the positive electrode active material layer. Those skilled in the art can choose according to actual needs, as long as the purpose of the present application can be achieved. The present application has no particular restrictions on the thickness of the positive current collector and the positive electrode material layer, as long as the purpose of the present application can be achieved. For example, the thickness of the positive electrode current collector is 6 μm to 12 μm, and the thickness of the positive electrode material layer is 30 μm to 120 μm. The application has no particular restrictions on the thickness of the positive electrode sheet, as long as the purpose of the application can be achieved, for example, the thickness of the positive electrode sheet is 50 μm to 150 μm.
任选地，正极极片还可以包含导电层，导电层位于正极集流体和正极材料层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。导电层包括导电剂和粘结剂。本申请对导电层中的导电剂和粘结剂没有特别限制，例如，可以是上述导电剂和上述粘结剂中的至少一种。Optionally, the positive electrode sheet may further include a conductive layer, which is located between the positive electrode current collector and the positive electrode material layer. The composition of the conductive layer is not particularly limited, and it can be a conductive layer commonly used in the art. The conductive layer includes a conductive agent and a binder. The present application has no particular restrictions on the conductive agent and the binder in the conductive layer, for example, it can be at least one of the above conductive agent and the above binder.
在本申请中，电化学装置还包括隔离膜，用以分隔正极极片和负极极片，防止电化学装置内部短路，允许电解质离子自由通过，且不影响电化学充放电过程的进行。本申请对隔离膜没有特别限制，只要能够实现本申请目的即可。例如，隔离膜的材料可以包括但不限于聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类、聚酯(例如，聚对苯二甲酸二乙酯(PET)膜)、纤维素、聚酰亚胺(PI)、聚酰胺(PA)、氨纶或芳纶中的至少一种；隔离膜的类型可以包括织造膜、非织造膜、微孔膜、复合膜、碾压膜或纺丝膜中的至少一种。In the present application, the electrochemical device also includes a separator to separate the positive electrode plate and the negative electrode plate, prevent internal short circuit of the electrochemical device, allow electrolyte ions to pass freely, and do not affect the electrochemical charge and discharge process. The present application has no special restrictions on the separator, as long as the purpose of the present application can be achieved. For example, the material of the separator may include but is not limited to polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (for example, polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex or aramid; the type of separator may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane or a spun membrane.
例如，隔离膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。任选地，可以使用聚丙烯多孔膜、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。任选地，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。For example, the isolation membrane may include a substrate layer and a surface treatment layer. The substrate layer may be a nonwoven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance.
例如，无机物层包括无机颗粒和粘结剂，所述无机颗粒没有特别限制，例如可以包括氧化铝、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。所述粘结剂没有特别限制，例如可以是上述粘结剂中的至少一种。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、聚乙烯醚或聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, and may include, for example, aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate. The binder is not particularly limited, and may be, for example, at least one of the above-mentioned binders. The polymer layer includes a polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether or polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
在本申请中，电化学装置还包括电解液，电解液包括锂盐和非水溶剂。锂盐可以包括LiPF 6、LiBF 4、LiAsF 6、LiClO 4、LiB(C 6H 5) 4、LiCH 3SO 3、LiCF 3SO 3、LiN(SO 2CF 3) 2、LiC(SO 2CF 3) 3、Li 2SiF 6、双草酸硼酸锂(LiBOB)或二氟硼酸锂中的至少一种。本申请对锂盐在电解液中的浓度没有特别限制，只要能实现本申请的目的即可。例如，锂盐在电解液中的浓度为0.9mol/L至1.5mol/L，示例性地，锂盐在电解液中的浓度可以为0.9mol/L、1.0mol/L、1.1mol/L、1.3mol/L、1.5mol/L或为上述任意两个数值组成的范围。本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯 可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、1-乙氧基-1-甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯或磷酸三辛酯中的至少一种。电解液中上述非水溶剂的质量百分含量可以为15％至80％，例如可以15％、20％、30％、40％、50％、60％、70％、80％或为其间的任意范围。 In the present application, the electrochemical device also includes an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent. The lithium salt may include at least one of LiPF 6 , LiBF 4 , LiAsF 6 , LiClO 4 , LiB(C 6 H 5 ) 4 , LiCH 3 SO 3 , LiCF 3 SO 3 , LiN(SO 2 CF 3 ) 2 , LiC(SO 2 CF 3 ) 3 , Li 2 SiF 6 , lithium bis(oxalate borate) (LiBOB) or lithium difluoroborate. The present application does not particularly limit the concentration of the lithium salt in the electrolyte, as long as the purpose of the present application can be achieved. For example, the concentration of the lithium salt in the electrolyte is 0.9 mol/L to 1.5 mol/L. For example, the concentration of the lithium salt in the electrolyte may be 0.9 mol/L, 1.0 mol/L, 1.1 mol/L, 1.3 mol/L, 1.5 mol/L or a range consisting of any two of the above values. The present application has no particular restrictions on non-aqueous solvents, as long as the purpose of the present application can be achieved, for example, it may include but is not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents. The above-mentioned carbonate compounds may include but are not limited to at least one of linear carbonate compounds, cyclic carbonate compounds or fluorinated carbonate compounds. The above-mentioned linear carbonate compounds may include but are not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) or ethyl methyl carbonate (MEC). The above-mentioned cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC). The fluorinated carbonate compound may include, but is not limited to, at least one of fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, or trifluoromethylethylene carbonate. The above-mentioned carboxylate compound may include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decalactone, valerolactone, or caprolactone. The above-mentioned ether compound may include but is not limited to at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran. The above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, cyclopentane, methyl cyclopentane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate. The mass percentage of the above-mentioned non-aqueous solvent in the electrolyte can be 15% to 80%, for example, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80% or any range therebetween.
本申请的电化学装置还包括包装袋，用于容纳正极极片、隔离膜、负极极片和电解液，以及电化学装置中本领域已知的其它部件，本申请对上述其它部件不做限定。本申请对包装袋没有特别限制，可以为本领域公知的包装袋，只要能够实现本申请目的即可。The electrochemical device of the present application also includes a packaging bag for containing a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, as well as other components known in the art in the electrochemical device, and the present application does not limit the above other components. The present application does not specifically limit the packaging bag, and it can be a packaging bag known in the art, as long as it can achieve the purpose of the present application.
本申请的电化学装置没有特别限定，其可以包括发生电化学反应的任何装置。在一些实施例中，电化学装置可以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。The electrochemical device of the present application is not particularly limited, and may include any device that undergoes an electrochemical reaction. In some embodiments, the electrochemical device may include, but is not limited to, a lithium metal secondary battery, a lithium ion secondary battery (lithium ion battery), a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
本申请的电化学装置的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，可以包括但不限于以下步骤：将正极极片、隔离膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入包装袋内，将电解液注入包装袋并封口，得到电化学装置；或者，将正极极片、隔离膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入包装袋内，将电解液注入包装袋并封口，得到电化学装置。此外，也可以根据需要将防过电流元件、导板等置于包装袋中，从而防止电化学装置内部的压力上升、过充放电。The preparation process of the electrochemical device of the present application is well known to those skilled in the art, and the present application has no particular limitation. For example, it may include but is not limited to the following steps: stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and winding, folding and other operations as needed to obtain an electrode assembly of a wound structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device; or stacking the positive electrode sheet, the separator and the negative electrode sheet in order, and then fixing the four corners of the entire stacked structure with tape to obtain an electrode assembly of a stacked structure, placing the electrode assembly in a packaging bag, injecting the electrolyte into the packaging bag and sealing it to obtain an electrochemical device. In addition, overcurrent protection elements, guide plates, etc. may also be placed in the packaging bag as needed to prevent pressure rise and overcharge and discharge inside the electrochemical device.
本申请第三方面提供了一种电子装置，其包括前述任一实施方案中的电化学装置。因此，本申请提供的电子装置具有良好的使用性能。The third aspect of the present application provides an electronic device, which includes the electrochemical device in any of the above embodiments. Therefore, the electronic device provided by the present application has good performance.
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、家庭用大型蓄电池和锂离子电容器等。The electronic device of the present application is not particularly limited, and it can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an electronic book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
实施例Example
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。The following examples and comparative examples are given to more specifically describe the embodiments of the present application. Various tests and evaluations were performed according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.
测试方法和设备：Test methods and equipment:
元素的分布和含量的测试：Test of element distribution and content:
将样品台上贴好导电胶，取各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用PhilipsXL-30型场发射扫描电子显微镜配备的EDS在加速电压为10kV，发射电流为10mA的条件下面扫测试元素的分布和质量百分含量。A conductive adhesive was applied to the sample stage, and the powdered samples of the carbon-doped silicon-oxygen composite materials in each embodiment or the negative electrode active materials other than graphite in the comparative example were spread on the conductive adhesive. The unattached powder was blown away with an ear bulb, and gold was sprayed. The distribution and mass percentage of the test elements were scanned using an EDS equipped with a Philips XL-30 field emission scanning electron microscope at an acceleration voltage of 10 kV and an emission current of 10 mA.
表面区域中碳元素的质量百分含量的测试：Test of the mass percentage of carbon in the surface area:
将样品台上贴好导电胶，取各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料的粉末状样品平铺于导电胶上，用洗耳球吹走未粘上的粉末，喷金，使用氩气等离子体对粉末状样品的颗粒进行截面切割。使用PhilipsXL-30型场发射扫描电子显微镜配备的EDS在加速电压为10kV，发射电流为10mA的条件下，选择粒径为4μm至10μm的颗粒，对颗粒的表面区域进行元素质量百分含量测试，得到表面区域中碳元素的质量百分含量。A conductive adhesive was pasted on the sample table, and the powdered samples of the carbon-doped silicon-oxygen composite materials in each embodiment or the negative electrode active materials other than graphite in the comparative examples were spread flat on the conductive adhesive, and the unadhered powder was blown away with an ear-cleaning bulb, and gold was sprayed, and the particles of the powdered sample were cross-sectioned using argon plasma. Using an EDS equipped with a Philips XL-30 field emission scanning electron microscope at an acceleration voltage of 10 kV and an emission current of 10 mA, particles with a particle size of 4 μm to 10 μm were selected, and the mass percentage content of the element on the surface area of the particles was tested to obtain the mass percentage content of the carbon element in the surface area.
粉末电导率的测试：Powder conductivity test:
取5g各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料的粉末样品，用电子压力机恒压至5000kg，维持20s，得到样品片，此时样品片的面积S＝3.14cm 2，测得样品片高度h后的面积S＝3.14cm 2。将样品片置于电阻测试仪(苏州晶格电子ST-2255A)电极间，在样品片两端施加电压U，测得电流I，根据公式R＝U/I，得到样品片电阻R。根据公式δ＝h/(S×R)/1000计算得到粉末电导率，单位为S/cm。 Take 5g of the powder sample of the carbon-doped silicon-oxygen composite material in each example or the negative electrode active material other than graphite in the comparative example, and use an electronic press to press it to 5000kg, and maintain it for 20s to obtain a sample sheet. At this time, the area of the sample sheet is S= 3.14cm2 , and the area after the sample sheet height h is measured is S= 3.14cm2 . The sample sheet is placed between the electrodes of a resistance tester (Suzhou Jingge Electronics ST-2255A), and a voltage U is applied to both ends of the sample sheet. The current I is measured, and the resistance R of the sample sheet is obtained according to the formula R=U/I. The powder conductivity is calculated according to the formula δ=h/(S×R)/1000, and the unit is S/cm.
粒径分布、Dv50和Dv99的测试：Particle size distribution, Dv50 and Dv99 testing:
在50ml洁净烧杯中加入0.02g各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料的粉末样品，加入20ml去离子水，再滴加5滴浓度为1％的表面活性剂，使粉末样品完全分散于水中，在120W超声清洗机中超声5分钟，利用激光散射粒度仪MasterSizer 2000测试粒度分布、Dv50和Dv99。In a 50 ml clean beaker, add 0.02 g of powder sample of the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, add 20 ml of deionized water, and then add 5 drops of a 1% surfactant to make the powder sample completely disperse in the water. Ultrasonicate in a 120 W ultrasonic cleaner for 5 minutes, and use a laser scattering particle size analyzer MasterSizer 2000 to test the particle size distribution, Dv50 and Dv99.
克容量的测试：Test of gram capacity:
将负极活性材料：导电剂导电炭黑：PAA粘接剂聚丙烯酸乙酯按照质量比8:1:1进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为45wt％的浆料，均匀地涂布在铜箔上烘干得到负极极片，然后以锂片为对电极，将负极极片、锂片、隔离膜和电解液组装成纽扣电池进行测试。测试流程为：0.05C恒流充电至5mV，再以10uA恒流充电至5mV，记录首次的充电容量；然后静置5min，再以0.05C放电至2V，记录首次的放电容量；克容量＝首次的放电容量/负极活性材料的质量。上述负极活性材料为各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料，隔离膜和电解液与实施例1-1中的相同。The negative electrode active material: conductive agent conductive carbon black: PAA binder polyethyl acrylate are mixed in a mass ratio of 8:1:1, N-methylpyrrolidone (NMP) is added as a solvent, and a slurry with a solid content of 45wt% is prepared. The slurry is evenly coated on the copper foil and dried to obtain the negative electrode plate. Then, the lithium plate is used as the counter electrode, and the negative electrode plate, lithium plate, isolation film and electrolyte are assembled into a button battery for testing. The test process is: 0.05C constant current charge to 5mV, then 10uA constant current charge to 5mV, record the first charge capacity; then stand for 5min, and then discharge to 2V at 0.05C, record the first discharge capacity; gram capacity = first discharge capacity/mass of negative electrode active material. The above-mentioned negative electrode active material is the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, and the isolation film and electrolyte are the same as those in Example 1-1.
循环容量保持率的测试：Cycle capacity retention rate test:
在25℃的环境中，将锂离子电池以0.5C恒流充电至4.45V，再以4.45V恒压充电至0.025C，静置5min，以0.5C恒流放电至3.0V，静置5min，记录首次循环的放电容量。然后以相同的步骤进行500次的充电和放电循环，记录第500次循环锂离子电池的放电容量。In an environment of 25°C, the lithium-ion battery was charged to 4.45V at 0.5C constant current, then charged to 0.025C at 4.45V constant voltage, left to stand for 5 minutes, and discharged to 3.0V at 0.5C constant current, left to stand for 5 minutes, and the discharge capacity of the first cycle was recorded. Then, the same steps were used for 500 charge and discharge cycles, and the discharge capacity of the lithium-ion battery at the 500th cycle was recorded.
锂离子电池的循环容量保持率(％)＝(第500次循环的放电容量/首次循环的放电容量)×100％。Cycle capacity retention rate (%) of lithium ion battery = (discharge capacity at the 500th cycle/discharge capacity at the first cycle) × 100%.
循环膨胀率测试：Cyclic expansion rate test:
在测试温度为25℃下，用螺旋千分尺测试锂离子电池在50％荷电状态(SOC)下的厚度，记为H 0，然后按照“循环容量保持率的测试”中的充放电步骤循环至500圈时，测试锂离子电池在100％SOC下的厚度，记为H 1。循环膨胀率＝(H 1-H 0)/H 0×100％。 At a test temperature of 25°C, use a screw micrometer to measure the thickness of the lithium-ion battery at 50% state of charge (SOC), recorded as H 0 , and then test the thickness of the lithium-ion battery at 100% SOC when the battery is cycled to 500 cycles according to the charge and discharge steps in the "Test of Cyclic Capacity Retention Rate", recorded as H 1 . Cyclic expansion rate = (H 1 -H 0 )/H 0 × 100%.
实施例1-1Example 1-1
<碳掺杂硅氧复合材料的制备><Preparation of Carbon-doped Silicon-Oxygen Composite Materials>
将四甲基-四乙烯基-环四硅氧烷、聚甲基氢硅氧烷、乙醇按照质量比为1:1:8混合并搅拌至混合均匀得到有机硅溶液。将碳掺杂硅氧材料与有机硅溶液按照质量比为63:50混合并搅拌均匀，在80℃下烘干，然后进行热处理得到碳掺杂硅氧复合材料，热处理的温度为800℃、升温速率为3℃/min、保温时间为3h。其中，碳掺杂硅氧材料中碳元素的质量百分 含量为2％，硅元素的质量百分含量为59％，氧元素的质量百分含量为39％。Tetramethyl-tetravinyl-cyclotetrasiloxane, polymethylhydrogensiloxane and ethanol were mixed in a mass ratio of 1:1:8 and stirred until uniformly mixed to obtain an organosilicon solution. The carbon-doped silicon-oxygen material and the organosilicon solution were mixed in a mass ratio of 63:50 and stirred uniformly, dried at 80°C, and then heat-treated to obtain a carbon-doped silicon-oxygen composite material, with a heat treatment temperature of 800°C, a heating rate of 3°C/min, and a holding time of 3h. Among them, the mass percentage of carbon element in the carbon-doped silicon-oxygen material is 2%, the mass percentage of silicon element is 59%, and the mass percentage of oxygen element is 39%.
<负极极片的制备><Preparation of negative electrode sheet>
将上述制备的碳掺杂硅氧复合材料、石墨、导电炭黑和丁苯橡胶按照质量比5:92:1.8:1.2进行混合，加入去离子水作为溶剂，调配成为固含量为45wt％的浆料，真空搅拌机搅拌均匀后得到负极浆料。将负极浆料均匀涂覆于厚度为10μm的负极集流体铜箔的一个表面上，90℃条件下烘干，得到涂层厚度为100μm的单面涂布负极活性材料层的负极极片。然后在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料层的负极极片。90℃条件下烘干后冷压，再经裁片、焊接极耳，得到规格为78mm×875mm的负极极片待用。The carbon-doped silicon-oxygen composite material, graphite, conductive carbon black and styrene-butadiene rubber prepared above are mixed in a mass ratio of 5:92:1.8:1.2, deionized water is added as a solvent, and a slurry with a solid content of 45wt% is prepared. After being stirred evenly by a vacuum mixer, a negative electrode slurry is obtained. The negative electrode slurry is evenly coated on one surface of a negative electrode current collector copper foil with a thickness of 10μm, and dried at 90°C to obtain a negative electrode sheet with a single-sided negative electrode active material layer coated with a coating thickness of 100μm. Then repeat the above steps on the other surface of the copper foil to obtain a negative electrode sheet with a double-sided negative electrode active material layer. After drying at 90°C, cold pressing is performed, and then cutting and welding of the pole ears are performed to obtain a negative electrode sheet with a specification of 78mm×875mm for standby use.
<正极极片的制备><Preparation of positive electrode sheet>
将正极活性材料钴酸锂(LiCoO 2)、导电炭黑、聚偏氟乙烯(PVDF)按照质量比97.5:1.0:1.5进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75wt％的浆料，并搅拌均匀。将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，90℃条件下烘干，得到涂层厚度为100μm的单面涂布负极活性材料层的正极极片。然后在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极活性材料的正极极片。90℃条件下烘干后冷压，再经裁片、焊接极耳，得到规格为74mm×867mm的正极极片待用。 The positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on one surface of a positive electrode current collector aluminum foil with a thickness of 10μm, and dried at 90°C to obtain a positive electrode sheet with a single-sided coating of a negative electrode active material layer with a coating thickness of 100μm. Then repeat the above steps on the other surface of the aluminum foil to obtain a positive electrode sheet with a double-sided coating of positive electrode active materials. After drying at 90°C, cold pressing is performed, and then cutting and welding of the tabs are performed to obtain a positive electrode sheet with a specification of 74mm×867mm for standby use.
<电解液的制备><Preparation of Electrolyte>
在干燥氩气气氛手套箱中，将有机溶剂EC、PC、DEC和EP按照质量比为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，得到电解液。其中，锂盐的浓度为12.5wt％。 In a dry argon atmosphere glove box, organic solvents EC, PC, DEC and EP were mixed in a mass ratio of 3:1:3:3, and then lithium salt lithium hexafluorophosphate (LiPF 6 ) was added to the organic solvents to dissolve and mix evenly to obtain an electrolyte solution, wherein the concentration of the lithium salt was 12.5 wt %.
<隔离膜><Isolation film>
采用厚度为7μm的多孔聚乙烯薄膜(Celgard公司提供)。A porous polyethylene film with a thickness of 7 μm (provided by Celgard Company) was used.
<锂离子电池的制备><Preparation of lithium-ion batteries>
将上述制备的正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片中间起到隔离的作用，并卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱去水分，注入配好的电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。The prepared positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain an electrode assembly. The electrode assembly is placed in an aluminum-plastic film packaging bag, and the moisture is removed at 80°C, and the prepared electrolyte is injected. After vacuum packaging, standing, formation, degassing, trimming and other processes, a lithium-ion battery is obtained.
实施例1-2至实施例1-12Example 1-2 to Example 1-12
除了在<碳掺杂硅氧复合材料的制备>中，按照表1调整相关制备参数以外，其余与实施例1-1相同。Except that the relevant preparation parameters in <Preparation of Carbon-doped Silicon-Oxygen Composite Material> are adjusted according to Table 1, the rest is the same as Example 1-1.
实施例2-1至实施例2-2Example 2-1 to Example 2-2
除了在<负极极片的制备>中，按照表3调整碳掺杂硅氧复合材料与石墨的质量比且碳掺杂硅氧复合材料和石墨的总质量不变以外，其余与实施例1-1相同。Except that in <Preparation of Negative Electrode Plate>, the mass ratio of the carbon-doped silicon-oxygen composite material to graphite is adjusted according to Table 3 and the total mass of the carbon-doped silicon-oxygen composite material and graphite remains unchanged, the rest is the same as Example 1-1.
对比例1Comparative Example 1
除了按照以下步骤制备负极活性材料并将<负极极片的制备>中的碳掺杂硅氧复合材料替换为以下制备的负极活性材料以外，其余与实施例1-1相同；The negative electrode active material is prepared according to the following steps and the carbon-doped silicon-oxygen composite material in <Preparation of negative electrode sheet> is replaced with the negative electrode active material prepared below, and the rest is the same as Example 1-1;
<负极活性材料的制备><Preparation of negative electrode active material>
将碳掺杂硅氧材料进行热处理得到负极活性材料，热处理的温度为800℃、升温速率为3℃/min、保温时间为3h。其中，碳掺杂硅氧材料中碳元素的质量百分含量为2％，硅元素的质量百分含量为59％，氧元素的质量百分含量为39％。The carbon-doped silicon-oxygen material is subjected to heat treatment to obtain a negative electrode active material, wherein the heat treatment temperature is 800°C, the heating rate is 3°C/min, and the holding time is 3h. The mass percentage of carbon element in the carbon-doped silicon-oxygen material is 2%, the mass percentage of silicon element is 59%, and the mass percentage of oxygen element is 39%.
对比例2Comparative Example 2
除了按照表1调整相关制备参数以外，其余与实施例1-1相同。Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1-1.
对比例3Comparative Example 3
除了将<负极极片的制备>中的碳掺杂硅氧复合材料替换为负极活性材料硅氧材料以外，其余与实施例1-1相同。其中，硅氧材料中硅元素的质量百分含量为62％，氧元素的质量百分含量为38％。硅氧材料为市售材料，满足上述元素含量即可。Except that the carbon-doped silicon-oxygen composite material in the preparation of the negative electrode plate is replaced by the negative electrode active material silicon-oxygen material, the rest is the same as Example 1-1. The mass percentage of silicon element in the silicon-oxygen material is 62%, and the mass percentage of oxygen element is 38%. The silicon-oxygen material is a commercially available material, and it only needs to meet the above-mentioned element content.
各实施例和对比例的制备参数和性能参数如表1至表3所示。The preparation parameters and performance parameters of each embodiment and comparative example are shown in Tables 1 to 3.
表1Table 1
Figure PCTCN2022126942-appb-000001
Figure PCTCN2022126942-appb-000001
Figure PCTCN2022126942-appb-000002
Figure PCTCN2022126942-appb-000002
注：表1中的“元素含量”是指对应元素的质量百分含量，“负极活性材料”是指各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料，“占比”是指碳掺杂硅氧复合材料颗粒的表面区域的碳元素的质量含量占碳掺杂硅氧复合材料碳元素质量含量的比例，“/”表示不存在对应的参数或物质。Note: "element content" in Table 1 refers to the mass percentage of the corresponding element, "negative electrode active material" refers to the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, "proportion" refers to the ratio of the mass content of carbon element in the surface area of carbon-doped silicon-oxygen composite material particles to the mass content of carbon element in carbon-doped silicon-oxygen composite material, and "/" indicates that there is no corresponding parameter or substance.
表2Table 2
Figure PCTCN2022126942-appb-000003
Figure PCTCN2022126942-appb-000003
注：表2中的“元素含量”是指对应元素的质量百分含量，“负极活性材料”是指各实施例中的碳掺杂硅氧复合材料或对比例中除石墨以外的负极活性材料，“/”表示不存在对应的参数或物质；以实施例1-1为例，“0.2-20”是指负极活性材料的粒径分布为0.2μm至20μm， 其余实施例和对比例以此类推理解。Note: "element content" in Table 2 refers to the mass percentage of the corresponding element, "negative electrode active material" refers to the carbon-doped silicon-oxygen composite material in each embodiment or the negative electrode active material other than graphite in the comparative example, and "/" indicates that the corresponding parameter or substance does not exist; taking Example 1-1 as an example, "0.2-20" means that the particle size distribution of the negative electrode active material is 0.2μm to 20μm, and the rest of the embodiments and comparative examples are understood by analogy.
从实施例1-1至实施例1-12、对比例1至对比例3可以看出，实施例均采用本申请提供的负极极片，负极极片中的碳掺杂硅氧复合材料中的碳元素的质量百分含量在本申请的范围内，且碳掺杂硅氧复合材料的颗粒表面区域中的碳元素含量大于颗粒内部区域中的碳元素含量，而对比例1中制得的负极活性材料表面不存在碳元素，对比例2中的碳掺杂硅氧复合材料的颗粒表面区域中的碳元素含量小于颗粒内部区域中的碳元素含量，对比例3中的硅氧材料不包含碳元素，实施例得到的锂离子电池具有更高的循环容量保持率和更小的膨胀率，从而说明采用本申请提供的负极极片可以有效改善锂离子电池的循环性能和膨胀性能。对比例1和对比例3中的负极活性材料虽然具有较高的克容量，但锂离子电池的循环性能和膨胀性能明显差于实施例；实施例中的碳掺杂硅氧复合材料的克容量与对比例2中的基本相当或者更高，但对比例2中的锂离子电池的循环性能和膨胀性能也明显差于实施例。从而说明本申请实施例能够兼顾负极活性材料的克容量与锂离子电池的性能，而对比例1至对比例3难以兼顾。From Examples 1-1 to 1-12 and Comparative Examples 1 to 3, it can be seen that the examples all use the negative electrode sheets provided by the present application, the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material in the negative electrode sheet is within the scope of the present application, and the carbon element content in the particle surface region of the carbon-doped silicon-oxygen composite material is greater than the carbon element content in the particle internal region, while there is no carbon element on the surface of the negative active material prepared in Comparative Example 1, the carbon element content in the particle surface region of the carbon-doped silicon-oxygen composite material in Comparative Example 2 is less than the carbon element content in the particle internal region, and the silicon-oxygen material in Comparative Example 3 does not contain carbon elements. The lithium-ion battery obtained in the example has a higher cycle capacity retention rate and a smaller expansion rate, which shows that the use of the negative electrode sheet provided by the present application can effectively improve the cycle performance and expansion performance of the lithium-ion battery. Although the negative active materials in Comparative Examples 1 and 3 have higher gram capacity, the cycle performance and expansion performance of the lithium-ion battery are significantly worse than those in the examples; the gram capacity of the carbon-doped silicon-oxygen composite material in the example is basically equivalent to or higher than that in Comparative Example 2, but the cycle performance and expansion performance of the lithium-ion battery in Comparative Example 2 are also significantly worse than those in the example. This shows that the embodiment of the present application can take into account both the gram capacity of the negative electrode active material and the performance of the lithium-ion battery, while Comparative Examples 1 to 3 are difficult to take into account both.
具体地，图2为实施例1-1中的碳掺杂硅氧复合材料的EDS分层图像，图3至图5依次分别为图1中的EDS分层图像对应的氧元素、硅元素和碳元素在碳掺杂硅氧复合材料中的分布图像。从图2至图5中可以，看出碳掺杂硅氧复合材料中含有氧元素、硅元素和碳元素，氧元素和硅元素的在碳掺杂硅氧复合材料中分布较为均匀，碳元素主要分布在碳掺杂硅氧复合材料颗粒的表面区域。Specifically, Figure 2 is an EDS layered image of the carbon-doped silicon-oxygen composite material in Example 1-1, and Figures 3 to 5 are respectively distribution images of oxygen, silicon and carbon in the carbon-doped silicon-oxygen composite material corresponding to the EDS layered image in Figure 1. From Figures 2 to 5, it can be seen that the carbon-doped silicon-oxygen composite material contains oxygen, silicon and carbon, and the oxygen and silicon elements are distributed more evenly in the carbon-doped silicon-oxygen composite material, and the carbon element is mainly distributed in the surface area of the carbon-doped silicon-oxygen composite material particles.
碳掺杂硅氧复合材料颗粒表面区域中碳元素的质量百分含量通常会影响锂离子电池的循环性能和膨胀性能，从实施例1-1至实施例1-12可以看出，当碳掺杂硅氧复合材料颗粒表面区域中碳元素的质量百分含量在本申请的范围内，得到的锂离子电池具有较高循环容量以及较小的循环膨胀率，从而说明锂离子电池具有良好的循环性能和膨胀性能。The mass percentage of carbon element in the surface region of carbon-doped silicon-oxygen composite material particles usually affects the cycle performance and expansion performance of lithium-ion batteries. It can be seen from Examples 1-1 to 1-12 that when the mass percentage of carbon element in the surface region of carbon-doped silicon-oxygen composite material particles is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
碳掺杂硅氧复合材料中硅元素的质量百分含量通常会影响锂离子电池的循环性能和膨胀性能，从实施例1-1至实施例1-12可以看出，当碳掺杂硅氧复合材料中硅元素的质量百分含量在本申请的范围内，得到的锂离子电池具有较高循环容量以及较小的循环膨胀率，从而说明锂离子电池具有良好的循环性能和膨胀性能。The mass percentage of silicon in the carbon-doped silicon-oxygen composite material usually affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-12 that when the mass percentage of silicon in the carbon-doped silicon-oxygen composite material is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
碳掺杂硅氧复合材料的粒径分布范围、Dv50和Dv99通常也会影响锂离子电池的循环性能和膨胀性能，从实施例1-1至实施例1-12可以看出，当碳掺杂硅氧复合材料的粒径分布范围、Dv50和Dv99在本申请的范围内，得到的锂离子电池具有较高循环容量以及较小 的循环膨胀率，从而说明锂离子电池具有良好的循环性能和膨胀性能。The particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material generally also affect the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-12 that when the particle size distribution range, Dv50 and Dv99 of the carbon-doped silicon-oxygen composite material are within the scope of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
碳掺杂硅氧复合材料的粉末电导率通常也会影响锂离子电池的循环性能和膨胀性能，从实施例1-1至实施例1-11可以看出，当碳掺杂硅氧复合材料的粉末电导率在本申请的范围内，得到的锂离子电池具有较高循环容量以及较小的循环膨胀率，从而说明锂离子电池具有良好的循环性能和膨胀性能。The powder conductivity of the carbon-doped silicon-oxygen composite material generally also affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1 to 1-11 that when the powder conductivity of the carbon-doped silicon-oxygen composite material is within the scope of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
表3table 3
 The 碳掺杂硅氧复合材料与石墨的质量比Mass ratio of carbon-doped silicon-oxygen composite to graphite 循环容量保持率(％)Cycle capacity retention rate (%) 循环膨胀率(％)Cycle expansion rate (%)
实施例1-1Example 1-1 5.2:94.85.2:94.8 90.190.1 1010
实施例2-1Example 2-1 20:8020:80 85.685.6 11.011.0
实施例2-2Example 2-2 3:973:97 93.293.2 9.29.2
碳掺杂硅氧复合材料与石墨的质量比通常会影响锂离子电池的循环性能和膨胀性能，从实施例1-1、实施例2-1和实施例2-2可以看出，当碳掺杂硅氧复合材料与石墨的质量比在本申请的范围内，得到的锂离子电池具有较高循环容量以及较小的循环膨胀率，从而说明锂离子电池具有良好的循环性能和膨胀性能。The mass ratio of the carbon-doped silicon-oxygen composite material to graphite usually affects the cycle performance and expansion performance of the lithium-ion battery. It can be seen from Examples 1-1, 2-1 and 2-2 that when the mass ratio of the carbon-doped silicon-oxygen composite material to graphite is within the range of the present application, the obtained lithium-ion battery has a higher cycle capacity and a smaller cycle expansion rate, which indicates that the lithium-ion battery has good cycle performance and expansion performance.
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。The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims (13)

  1. 一种负极极片，其包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述负极活性材料包括碳掺杂硅氧复合材料和石墨，所述碳掺杂硅氧复合材料包括碳元素、硅元素和氧元素，所述碳掺杂硅氧复合材料的颗粒的表面区域中的碳元素含量大于所述颗粒内部区域中的碳元素含量，其中，所述表面区域为沿所述颗粒表面至内部深度为500nm的区域，所述内部区域为所述颗粒中除去所述表面区域以外的区域；A negative electrode sheet, comprising a negative electrode active material layer, the negative electrode active material layer comprising a negative electrode active material, the negative electrode active material comprising a carbon-doped silicon-oxygen composite material and graphite, the carbon-doped silicon-oxygen composite material comprising carbon, silicon and oxygen, the carbon content in the surface region of particles of the carbon-doped silicon-oxygen composite material being greater than the carbon content in the internal region of the particles, wherein the surface region is a region from the surface of the particles to a depth of 500 nm, and the internal region is a region of the particles excluding the surface region;
    其中，基于所述碳元素、所述硅元素和所述氧元素的质量总和，所述碳掺杂硅氧复合材料中所述碳元素的质量百分含量为2％至10％。Wherein, based on the total mass of the carbon element, the silicon element and the oxygen element, the mass percentage of the carbon element in the carbon-doped silicon-oxygen composite material is 2% to 10%.
  2. 根据权利要求1所述的负极极片，其中，基于所述碳元素、所述硅元素和所述氧元素的质量总和，所述表面区域中所述碳元素的质量百分含量为0.5％至8％。The negative electrode plate according to claim 1, wherein the mass percentage of the carbon element in the surface area is 0.5% to 8% based on the total mass of the carbon element, the silicon element and the oxygen element.
  3. 根据权利要求1所述的负极极片，其中，基于所述碳元素、所述硅元素和所述氧元素的质量总和，所述碳掺杂硅氧复合材料中所述硅元素的质量百分含量为40％至60％。The negative electrode plate according to claim 1, wherein the mass percentage of the silicon element in the carbon-doped silicon-oxygen composite material is 40% to 60% based on the total mass of the carbon element, the silicon element and the oxygen element.
  4. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料的粒径分布范围为0.2μm至20μm，Dv50为4μm至10μm，Dv99为13μm至20μm。The negative electrode plate according to claim 1, wherein the particle size distribution range of the carbon-doped silicon-oxygen composite material is 0.2 μm to 20 μm, Dv50 is 4 μm to 10 μm, and Dv99 is 13 μm to 20 μm.
  5. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料的粉末电导率为0.03S/cm至8S/cm。The negative electrode plate according to claim 1, wherein the powder conductivity of the carbon-doped silicon-oxygen composite material is 0.03 S/cm to 8 S/cm.
  6. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料颗粒的所述内部区域形成Si-C键，所述表面区域形成Si-O-C键。The negative electrode plate according to claim 1, wherein the inner region of the carbon-doped silicon-oxygen composite material particles forms Si-C bonds, and the surface region forms Si-O-C bonds.
  7. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料颗粒的所述表面区域的碳元素的质量含量占所述碳掺杂硅氧复合材料碳元素质量含量的10％至80％。The negative electrode plate according to claim 1, wherein the mass content of carbon element in the surface area of the carbon-doped silicon-oxygen composite material particles accounts for 10% to 80% of the mass content of carbon element in the carbon-doped silicon-oxygen composite material.
  8. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料颗粒中硅元素和氧元素分布均匀。The negative electrode plate according to claim 1, wherein silicon and oxygen are evenly distributed in the carbon-doped silicon-oxygen composite material particles.
  9. 根据权利要求1所述的负极极片，其中，所述石墨包括天然石墨、人造石墨或中间相碳微球等中的至少一种。The negative electrode sheet according to claim 1, wherein the graphite comprises at least one of natural graphite, artificial graphite or mesophase carbon microbeads.
  10. 根据权利要求1所述的负极极片，其中，所述碳掺杂硅氧复合材料与所述石墨的质量比为(3至20):(80至97)。The negative electrode plate according to claim 1, wherein the mass ratio of the carbon-doped silicon-oxygen composite material to the graphite is (3 to 20):(80 to 97).
  11. 根据权利要求1所述的负极极片，其中，所述负极材料层还包括粘结剂，所述粘结剂包括聚丙烯酸酯、聚酰亚胺、聚酰胺、聚酰胺酰亚胺、聚偏氟乙烯、聚苯乙烯丁二烯共聚物、海藻酸钠、聚乙烯醇、聚四氟乙烯、聚丙烯腈、羧甲基纤维素钠、羧甲基纤维素钾、 羟甲基纤维素钠或羟甲基纤维素钾中的至少一种。The negative electrode plate according to claim 1, wherein the negative electrode material layer further comprises a binder, and the binder comprises at least one of polyacrylate, polyimide, polyamide, polyamideimide, polyvinylidene fluoride, polystyrene butadiene copolymer, sodium alginate, polyvinyl alcohol, polytetrafluoroethylene, polyacrylonitrile, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium hydroxymethyl cellulose or potassium hydroxymethyl cellulose.
  12. 一种电化学装置，其包括权利要求1至11中任一项所述的负极极片。An electrochemical device comprising the negative electrode sheet according to any one of claims 1 to 11.
  13. 一种电子装置，其包括权利要求12所述的电化学装置。An electronic device comprising the electrochemical device according to claim 12.
PCT/CN2022/126942 2022-10-24 2022-10-24 Negative pole piece, electrochemical apparatus, and electrical apparatus WO2024086962A1 (en)

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