WO2021203408A1 - 负极活性材料及使用其的电化学装置和电子装置 - Google Patents

负极活性材料及使用其的电化学装置和电子装置 Download PDF

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WO2021203408A1
WO2021203408A1 PCT/CN2020/084168 CN2020084168W WO2021203408A1 WO 2021203408 A1 WO2021203408 A1 WO 2021203408A1 CN 2020084168 W CN2020084168 W CN 2020084168W WO 2021203408 A1 WO2021203408 A1 WO 2021203408A1
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active material
negative electrode
negative
electrode active
lithium
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PCT/CN2020/084168
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English (en)
French (fr)
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唐佳
何丽红
冯鹏洋
谢远森
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宁德新能源科技有限公司
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Priority to CN202080004196.5A priority Critical patent/CN112640163B/zh
Priority to CN202210860935.1A priority patent/CN115000393A/zh
Priority to JP2021512518A priority patent/JP7236532B2/ja
Priority to PCT/CN2020/084168 priority patent/WO2021203408A1/zh
Priority to EP20930448.4A priority patent/EP4135065A4/en
Publication of WO2021203408A1 publication Critical patent/WO2021203408A1/zh
Priority to US17/963,564 priority patent/US20230049766A1/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
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This application relates to the field of energy storage, in particular to a negative electrode active material and an electrochemical device and an electronic device using the same.
  • Electrochemical devices for example, lithium-ion batteries
  • Small-sized lithium-ion batteries are generally used as power sources for driving portable electronic communication devices (for example, camcorders, mobile phones, or notebook computers, etc.), especially high-performance portable devices.
  • Examples of medium-sized and large-sized lithium batteries with high output characteristics have been developed for use in electric vehicles (EV) and large-scale energy storage systems (ESS).
  • EV electric vehicles
  • ESS large-scale energy storage systems
  • the present application attempts to solve at least one problem existing in related fields at least to some extent by providing a negative electrode active material, an electrochemical device and an electronic device using the same.
  • the present application provides a negative active material, wherein a dynamic particle image analyzer is used to test, when the cumulative distribution of particle volume of the negative active material is 10%, the width and length of the negative active material
  • the ratio AR 10 satisfies 0.4 ⁇ AR 10 ⁇ 0.55, and the sphericity S 10 of the negative electrode active material satisfies 0.48 ⁇ S 10 ⁇ 0.60.
  • the width of the negative electrode active material satisfies long 0.42 ⁇ AR 10 ⁇ 0.52 ratio AR 10. In some embodiments, the aspect ratio AR 10 of the negative active material satisfies 0.45 ⁇ AR 10 ⁇ 0.50. In some embodiments, the aspect ratio AR 10 of the negative active material is 0.4, 0.42, 0.45, 0.48, 0.50, 0.52, 0.55, or within a range composed of any two of the foregoing values.
  • the sphericity of the negative electrode active material satisfies S 10 0.50 ⁇ S 10 ⁇ 0.55. In some embodiments, the sphericity S 10 of the negative electrode active material satisfies 0.48, 0.50, 0.52, 0.55, 0.58, 0.60 or within a range composed of any two of the foregoing values.
  • the negative active material when the cumulative particle volume distribution of the negative active material is 50%, the negative active material satisfies at least one of the conditions (a) or (b):
  • said negative electrode active material satisfies the sphericity S 50 0.68 ⁇ S 50 ⁇ 0.82.
  • the width of the negative electrode active material satisfies long 0.62 ⁇ AR 50 ⁇ 0.72 ratio AR 50. In some embodiments, the width of the negative electrode active material satisfies long 0.65 ⁇ AR 50 ⁇ 0.70 ratio AR 50. In some embodiments, the aspect ratio AR 50 of the negative active material satisfies 0.6, 0.62, 0.65, 0.68, 0.70, 0.72, 0.75, or within a range composed of any two of the foregoing values.
  • the sphericity S 50 of the negative active material satisfies 0.70 ⁇ S 50 ⁇ 0.80. In some embodiments, the negative electrode active material satisfies the sphericity S 50 0.72 ⁇ S 50 ⁇ 0.75. In some embodiments, the sphericity S 50 of the negative electrode active material satisfies 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.82 or within a range composed of any two of the foregoing values.
  • the negative active material when the cumulative particle volume distribution of the negative active material is 90%, the negative active material satisfies at least one of the conditions (c) or (d):
  • the width of the negative electrode active material satisfies long 0.85 ⁇ AR 90 ⁇ 0.88 ratio AR 90.
  • the aspect ratio AR 90 of the negative active material satisfies 0.82, 0.85, 0.88, 0.90 or falls within the range composed of any two of the foregoing values.
  • the sphericity of the negative electrode active material satisfies S 90 0.88 ⁇ S 90 ⁇ 0.90. In some embodiments, the sphericity S 90 of the negative active material satisfies 0.85, 0.88, 0.90, 0.92, 0.95, or is within a range composed of any two of the foregoing values.
  • the compacted density of the negative active material is greater than 1.90 g/cm 3 . In some embodiments, the compacted density of the negative active material is greater than 1.95 g/cm 3 . In some embodiments, the compacted density of the negative active material is greater than 2.0 g/cm 3 .
  • the negative active material includes primary particles and secondary particles, and the number of primary particles is 20% to 55% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 25% to 50% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 30% to 40% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 30% to 35% based on the total number of particles of the negative active material. In some embodiments, based on the total number of particles of the negative active material, the number of the primary particles is 25%, 30%, 35%, 40%, 45%, 50% or a combination of any two of the foregoing values. In the range.
  • the present application provides an electrochemical device including a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode includes a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer Contains the negative active material according to the present application.
  • the negative electrode satisfies at least one of conditions (e) to (g):
  • the anode active material layer has a porosity of 20% to 45%.
  • the weight of the negative electrode active material layer was 0.095mg / mm 2 to 0.105mg / mm 2. In some embodiments, the weight of the negative electrode active material layer was 0.095mg / mm 2, 0.097mg / mm 2, 0.099mg / mm 2, 0.101mg / mm 2, 0.103mg / mm 2, 0.105mg / mm 2 Or within the range of any two of the above values.
  • the C004/C110 of the negative electrode active material layer measured by X-ray diffraction spectroscopy is in the range of 12-18. In some embodiments, the C004/C110 of the negative electrode active material layer measured by X-ray diffraction spectroscopy is in the range of 14-16. In some embodiments, the C004/C110 of the negative electrode active material layer measured by X-ray diffraction pattern is 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or any of the above. Within the range of two values.
  • the negative active material layer has a porosity of 25% to 40%. In some embodiments, the negative active material layer has a porosity of 30% to 35%. In some embodiments, the porosity of the negative active material layer is 20%, 25%, 30%, 35%, 40%, 45%, or within a range composed of any two of the foregoing values.
  • a coating layer is further included between the negative electrode current collector and the negative electrode active material layer, and the ratio of the thickness of the coating layer to the thickness of the negative electrode active material layer is 1:50 to 1: Within the range of 120. In some embodiments, the ratio of the thickness of the coating layer to the thickness of the negative active material layer is in the range of 1:60 to 1:100. In some embodiments, the ratio of the thickness of the coating layer to the thickness of the negative active material layer is in the range of 1:80 to 1:90.
  • the ratio of the thickness of the coating to the thickness of the negative active material layer is 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1: 110, 1:120 or within the range composed of any two of the above values.
  • the binding force between the negative active material layer and the negative current collector is greater than 18 N/m. In some embodiments, the binding force between the negative active material layer and the negative current collector is greater than 20 N/m. In some embodiments, the binding force between the negative active material layer and the negative current collector is greater than 25 N/m.
  • the electrochemical device satisfies the following relationship: Y ⁇ 0.417X+A, where: X is the state of charge of the electrochemical device, 1 ⁇ X ⁇ 1.5, when the electrochemical device is When the state of charge is 1, the thickness of the electrochemical device is Amm, and when the state of charge of the electrochemical device is X, the thickness of the electrochemical device is Ymm.
  • X is 1.1, 1.2, 1.3, 1.4, or 1.5.
  • the present application provides an electronic device, which includes the electrochemical device according to the present application.
  • FIG. 1 shows the width-to-length ratio of the negative active material according to the embodiment of the present application under the cumulative distribution of different particle volumes.
  • FIG. 2 shows the sphericity of the negative active material according to the embodiment of the present application under the cumulative distribution of different particle volumes.
  • Figure 3 shows a schematic diagram of the negative structure in the X, Y, and Z directions.
  • Figure 4 shows a scanning electron microscope (SEM) image of a negative electrode material according to an embodiment of the present application.
  • a list of items connected by the term "at least one of” can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (exclude B); B and C (exclude A); or all of A, B, and C.
  • Project A can contain a single element or multiple elements.
  • Project B can contain a single element or multiple elements.
  • Project C can contain a single element or multiple elements.
  • the “aspect ratio” of the negative active material refers to the ratio of the width to the long diameter of the negative active material particles.
  • the aspect ratio of the negative active material can be obtained by dynamic particle image analysis (for example, using the Sinpatec QICPIC dynamic particle image analyzer).
  • the "wide diameter” of the negative electrode active material particles refers to the smallest value between parallel lines tangent to the projected image of the particles.
  • the “major axis” of the negative electrode active material particle refers to the maximum value between parallel lines tangent to the projected image of the particle.
  • the width and length of the negative electrode active material are relatively small, and the negative electrode active material particles have an elongated shape. The closer the aspect ratio of the negative active material is to 1, the closer the width and the long diameter of the negative active material particles are, that is, the closer the negative active material particles are to a circular shape.
  • AR n refers to the width-to-length ratio of the corresponding negative active material particles when the cumulative volume distribution of the negative active material particles is n%.
  • AR 10 represents the width-to-length ratio of the negative electrode active material particles when the cumulative volume distribution of the negative electrode active material particles is 10%, as shown by “AR 10 ” in FIG. 1.
  • AR 50 represents the width-to-length ratio of the negative electrode active material particles when the cumulative volume distribution of the negative electrode active material particles is 50%, as shown by “AR 50 ” in FIG. 1.
  • AR 90 indicates the width-to-length ratio of the negative electrode active material particles when the cumulative volume distribution of the negative electrode active material particles is 10%, as shown by “AR 90 ” in FIG. 1.
  • the "sphericity" of the negative active material refers to the ratio of the projected circumference of a sphere having the same volume as the negative active material particles to the actual projected circumference of the negative active material particles. The closer the sphericity of the negative active material is to 1, the closer the negative active material particles are to the spherical shape. When the sphericity of the negative electrode active material is 1, the negative electrode active material particles have a positive spherical shape.
  • the sphericity of the negative electrode active material can be obtained by dynamic particle image analysis (for example, using the Sinpatec QICPIC dynamic particle image analyzer).
  • S n refers to the corresponding sphericity of the negative electrode active material particles when the cumulative distribution of the particle volume of the negative electrode active material is n%.
  • S 10 represents the sphericity of the corresponding negative active material particles when the cumulative distribution of the particle volume of the negative active material is 10%, as shown by “S 10 " in FIG. 2.
  • S 50 represents the sphericity of the negative electrode active material particles when the cumulative volume distribution of the particles of the negative electrode active material is 50%, as shown by “S 50 ” in FIG. 2.
  • S 90 represents the sphericity of the corresponding negative active material particles when the cumulative volume distribution of the negative active material particles is 90%, as shown by “S 90 " in FIG. 2.
  • the rate performance can reflect the fast charging capability of lithium-ion batteries.
  • lithium evolution may occur on the surface of the negative electrode, which will significantly reduce the rate performance of the lithium ion battery.
  • the kinetic performance of the negative electrode active material decreases, leading to an increase in the electrochemical polarization of the negative electrode, and the phenomenon of lithium evolution is more likely to occur.
  • the precipitated lithium metal may form lithium dendrites, which may pierce the separation film and cause a short circuit between the positive electrode and the negative electrode.
  • the deformation of lithium-ion batteries during cycling can also lead to lithium evolution. Therefore, how to improve the lithium evolution phenomenon of the negative electrode has become one of the research directions.
  • the present application can improve the lithium evolution phenomenon of the electrochemical device during the cycle to improve the rate performance and dynamic performance of the electrochemical device, and at the same time improve the deformation problem of the electrochemical device.
  • the present application provides a negative active material, wherein a dynamic particle image analyzer is used to test, when the cumulative distribution of particle volume of the negative active material is 10%, the aspect ratio of the negative active material is AR 10 When 0.4 ⁇ AR 10 ⁇ 0.55 is satisfied, the sphericity S 10 of the negative electrode active material satisfies 0.48 ⁇ S 10 ⁇ 0.60.
  • the width of the negative electrode active material satisfies long 0.42 ⁇ AR 10 ⁇ 0.52 ratio AR 10. In some embodiments, the aspect ratio AR 10 of the negative active material satisfies 0.45 ⁇ AR 10 ⁇ 0.50. In some embodiments, the aspect ratio AR 10 of the negative active material is 0.4, 0.42, 0.45, 0.48, 0.50, 0.52, 0.55, or within a range composed of any two of the foregoing values.
  • the sphericity of the negative electrode active material satisfies S 10 0.50 ⁇ S 10 ⁇ 0.55. In some embodiments, the sphericity S 10 of the negative electrode active material satisfies 0.48, 0.50, 0.52, 0.55, 0.58, 0.60 or within a range composed of any two of the foregoing values.
  • the particles of the negative electrode active material are usually piled layer by layer with a certain range of porosity in different orientations on the surface of the negative electrode current collector to form the negative electrode active material layer. Since the negative electrode active material particles are stacked in a random state, too long and thin negative electrode active material particles (for example, AR 10 ⁇ 0.3) will reduce the pores between the particles, which is not conducive to the infiltration of the electrolyte. Spherical anode active material particles (for example, S 10 >0.9) will extend the lithium ion transmission path and increase the resistance to lithium ion insertion and extraction.
  • the width-to-length ratio of the negative active material can be controlled in a graded manner, and then the edges and corners of the surface of the negative active material can be removed by shaping to control the sphericity of the negative active material.
  • the negative electrode active material satisfies 0.4 ⁇ AR 10 ⁇ 0.55 and 0.48 ⁇ S 10 ⁇ 0.60, part of the negative electrode active material particles are relatively slender and have edges and corners, which can be filled in the pores of the negative electrode active material and help to inhibit the formation of lithium
  • the swelling of the negative electrode active material layer caused by the intercalation and deintercalation of ions, thereby improving the deformation problem and the lithium evolution phenomenon of the lithium ion battery during the cycle.
  • the width of the negative electrode active material when the negative electrode active material particle volume cumulative distribution of 50%, the width of the negative electrode active material satisfies long 0.6 ⁇ AR 50 ⁇ 0.75 ratio AR 50. In some embodiments, the width of the negative electrode active material satisfies long 0.62 ⁇ AR 50 ⁇ 0.72 ratio AR 50. In some embodiments, the width of the negative electrode active material satisfies long 0.65 ⁇ AR 50 ⁇ 0.70 ratio AR 50. In some embodiments, the aspect ratio AR 50 of the negative active material satisfies 0.6, 0.62, 0.65, 0.68, 0.70, 0.72, 0.75, or within a range composed of any two of the foregoing values.
  • the sphericity of the negative electrode active material 50 when the negative electrode active material particle volume cumulative distribution of 50%, the sphericity of the negative electrode active material 50 satisfies S 0.68 ⁇ S 50 ⁇ 0.82. In some embodiments, the sphericity S 50 of the negative active material satisfies 0.70 ⁇ S 50 ⁇ 0.80. In some embodiments, the negative electrode active material satisfies the sphericity S 50 0.72 ⁇ S 50 ⁇ 0.75. In some embodiments, the sphericity S 50 of the negative electrode active material satisfies 0.68, 0.70, 0.72, 0.75, 0.78, 0.80, 0.82 or within a range composed of any two of the foregoing values.
  • the width of the negative electrode active material satisfies long 0.82 ⁇ AR 90 ⁇ 0.90 ratio AR 90. In some embodiments, the width of the negative electrode active material satisfies long 0.85 ⁇ AR 90 ⁇ 0.88 ratio AR 90. In some embodiments, the aspect ratio AR 90 of the negative active material satisfies 0.82, 0.85, 0.88, 0.90 or falls within the range composed of any two of the foregoing values.
  • the sphericity of the negative electrode active material 90 when the negative electrode active material particle volume cumulative distribution of 90%, the sphericity of the negative electrode active material 90 satisfies S 0.85 ⁇ S 90 ⁇ 0.95. In some embodiments, the sphericity of the negative electrode active material satisfies S 90 0.88 ⁇ S 90 ⁇ 0.90. In some embodiments, the sphericity S 90 of the negative active material satisfies 0.85, 0.88, 0.90, 0.92, 0.95, or is within a range composed of any two of the foregoing values.
  • the overall negative electrode active material will be rounder but still have a certain angular appearance form.
  • the overall rounder appearance makes the accumulation layer formed by the negative electrode active material particles have a proper amount of pores, shortens the transmission path of lithium ions, accelerates the deintercalation of lithium ions, and ensures the smooth transfer of lithium ions in the pores.
  • edges and corners can increase the friction between the negative electrode active material particles, so that the stress on the negative electrode active material particles during the lithium ion intercalation and deintercalation process is uniformly released in all directions, thereby inhibiting the expansion of the negative electrode active material layer, thereby improving lithium The swelling problem of ion batteries during cycling.
  • the compacted density of the negative active material is greater than 1.90 g/cm 3 . In some embodiments, the compacted density of the negative active material is greater than 1.95 g/cm 3 . In some embodiments, the compacted density of the negative active material is greater than 2.0 g/cm 3 . Larger compaction density enables the negative electrode active material particles with angular appearance to be intertwined with each other, so that they are stacked in a direction parallel to the current collector, and the pores between the stacked structures are reduced. There are still enough pores between the spherical particles to ensure the smooth transmission of lithium ions.
  • the negative active material includes primary particles (for example, particles encircled by solid circles in Fig. 4) and secondary particles (for example, particles encircled by dashed lines in Fig. 4).
  • the number of the primary particles is 20% to 55% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 25% to 50% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 30% to 40% based on the total number of particles of the negative active material. In some embodiments, the number of the primary particles is 30% to 35% based on the total number of particles of the negative active material. In some embodiments, based on the total number of particles of the negative active material, the number of the primary particles is 25%, 30%, 35%, 40%, 45%, 50% or a combination of any two of the foregoing values. In the range.
  • the negative electrode active material includes primary particles in an amount within the above range
  • the anisotropy of the negative electrode active material particles increases, thereby effectively improving the swelling problem of the lithium ion battery during cycling and suppressing the deformation of the lithium ion battery.
  • the primary particles having an amount within the above range also contribute to increasing the energy density of the negative electrode active material.
  • the application also provides an electrochemical device, which includes a positive electrode, a negative electrode, a separator, and an electrolyte.
  • a positive electrode a negative electrode
  • a separator a separator
  • electrolyte an electrolyte
  • the negative electrode used in the electrochemical device of the present application includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer includes the negative electrode active material according to the present application.
  • the negative active material layer is disposed on the negative current collector. In some embodiments, the negative active material layer is disposed on both sides of the negative current collector. In some embodiments, the negative electrode current collector includes a region of a single-sided negative electrode active material layer.
  • the weight of the negative electrode active material layer was 0.095g / cm 2 to 0.105g / cm 2. In some embodiments, the weight of the negative active material layer is 0.095 g/cm 2 to 0.0.101 g/cm 2 . In some embodiments, the weight of the negative active material layer is 0.095g/cm 2 , 0.097g/cm 2 , 0.099g/cm 2 , 0.101g/cm 2 , 0.103g/cm 2 , 0.105g/cm 2 Or within the range of any two of the above values. When the weight of the negative electrode active material layer is within the above range, it helps the electrolyte to infiltrate the negative electrode active material layer, thereby accelerating the transmission of lithium ions.
  • the ratio C004/C110 of the peak area C004 of the (004) plane and the peak area C110 of the (110) plane of the negative electrode active material layer measured by the X-ray diffraction pattern is in the range of 10 to 20 Inside.
  • the C004/C110 of the negative electrode active material layer measured by X-ray diffraction spectroscopy is in the range of 12-18.
  • the C004/C110 of the negative electrode active material layer measured by X-ray diffraction spectroscopy is in the range of 14-16.
  • the C004/C110 of the negative electrode active material layer measured by X-ray diffraction pattern is 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or any of the above. Within the range of two values.
  • the C004/C110 value of the negative active material layer can reflect the orientation of the negative active material layer. If C004/C110 is too large or too small, the negative electrode active material layer shows large anisotropy.
  • C004/C110 is larger, that is, when the peak area C004 of the (004) plane is larger, under a certain compaction density, the negative electrode active material particles tend to be arranged on the current collector in a manner parallel to the current collector.
  • the negative electrode active material particles tend to be arranged on the current collector in a manner perpendicular to the current collector.
  • the C004/C110 of the negative electrode active material layer is within the above range, a part of the negative electrode active material particles are arranged on the current collector in a manner parallel to the current collector, and another part of the negative electrode active material particles are arranged on the current collector in a manner perpendicular to the current collector.
  • the negative electrode active material layer has appropriate anisotropy in all directions, which helps to improve the expansion and deformation of lithium-ion batteries during cycling.
  • the negative active material layer has a porosity of 20% to 45%. In some embodiments, the negative active material layer has a porosity of 25% to 40%. In some embodiments, the negative active material layer has a porosity of 30% to 35%. In some embodiments, the porosity of the negative active material layer is 20%, 25%, 30%, 35%, 40%, 45%, or within a range composed of any two of the foregoing values.
  • the porosity of the negative electrode active material layer When the porosity of the negative electrode active material layer is within the above range, it will help the electrolyte to infiltrate the negative electrode active material layer, shorten the transmission path of lithium ions, accelerate the deintercalation of lithium ions, and also help to form an appropriate amount of solid electrolyte interface (SEI) film to reduce the loss of lithium ions.
  • SEI solid electrolyte interface
  • the porosity of the negative active material layer can be achieved by controlling the rolling pressure during the preparation of the negative electrode. By controlling the rolling pressure, a continuous change in the thickness of the negative active material layer can be achieved, so that the porosity of the negative active material layer can be controlled.
  • the porosity of the negative electrode active material layer can be tested according to the standard of "GB/T24586-2009 Iron Ore Apparent Density and True Density and Porosity Determination".
  • a coating layer is further included between the negative electrode current collector and the negative electrode active material layer, and the ratio of the thickness of the coating layer to the thickness of the negative electrode active material layer is 1:50 to 1: Within the range of 120. In some embodiments, the ratio of the thickness of the coating layer to the thickness of the negative active material layer is in the range of 1:60 to 1:100. In some embodiments, the ratio of the thickness of the coating layer to the thickness of the negative active material layer is in the range of 1:80 to 1:90.
  • the ratio of the thickness of the coating to the thickness of the negative active material layer is 1:50, 1:60, 1:70, 1:80, 1:90, 1:100, 1: 110, 1:120 or within the range composed of any two of the above values.
  • the coating includes a conductive layer.
  • the conductive material of the conductive layer may include any conductive material as long as it does not cause a chemical change.
  • conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, graphene, etc.), metal-based materials (e.g., metal Powder, metal fibers, etc., such as copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof.
  • the binding force between the negative active material layer and the negative current collector is greater than 18 N/m. In some embodiments, the binding force between the negative active material layer and the negative current collector is greater than 20 N/m. In some embodiments, the binding force between the negative active material layer and the negative current collector is greater than 25 N/m.
  • the binding force between the negative electrode active material layer and the negative electrode current collector is within the above range, it can avoid the occurrence of peeling or burrs during the rolling or striping process during the preparation of the negative electrode, thereby avoiding potential safety hazards, and at the same time It can also ensure that the internal resistance of the battery is within an acceptable range and ensure the dynamic performance of the electrochemical device.
  • the binding between the negative electrode active material layer and the negative electrode current collector can be achieved by controlling the rolling process during the preparation of the negative electrode. Specifically, the bonding between the negative electrode active material layer and the negative electrode current collector can be tested using an Instron (model 33652) tester: take a 15-20mm long pole piece and fix it on the steel plate with 3M double-sided adhesive tape , Stick the adhesive tape on the surface of the negative active material layer, connect one side of the adhesive tape to the paper tape of equal width, adjust the limit block of the tensile machine to a suitable position, fold the tape upwards and slide 40mm, the sliding rate It is 50 mm/min, and the binding force between the negative electrode active material layer and the negative electrode current collector at 180° (that is, stretched in the opposite direction) is tested.
  • Instron model 33652
  • the electrochemical device satisfies the following relationship: Y ⁇ 0.417X+A, where: X is the state of charge of the electrochemical device, 1 ⁇ X ⁇ 1.5, when the electrochemical device is When the state of charge is 1, the thickness of the electrochemical device is Amm, and when the state of charge of the electrochemical device is X, the thickness of the electrochemical device is Y mm.
  • X is 1.1, 1.2, 1.3, 1.4, or 1.5.
  • the negative electrode current collector used in the present application may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, polymer substrates coated with conductive metals, and combinations thereof.
  • the negative electrode further includes a binder, and the binder is selected from at least one of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose , Polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, poly Propylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin or nylon, etc.
  • the binder is selected from at least one of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, and diacetyl cellulose , Polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone
  • the positive electrode includes a positive electrode current collector and a positive electrode active material provided on the positive electrode current collector.
  • the specific types of positive electrode active materials are not subject to specific restrictions, and can be selected according to requirements.
  • the positive electrode active material includes a positive electrode material capable of absorbing and releasing lithium (Li).
  • positive electrode materials capable of absorbing/releasing lithium (Li) may include lithium cobalt oxide, lithium nickel cobalt manganate, lithium nickel cobalt aluminate, lithium manganate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, and phosphoric acid. Lithium iron, lithium titanate and lithium-rich manganese-based materials.
  • the chemical formula of lithium cobalt oxide can be as chemical formula 1:
  • M1 represents selected from nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), Copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W), yttrium (Y), lanthanum (La), zirconium (Zr) and For at least one of silicon (Si), the values of x, a, b, and c are within the following ranges: 0.8 ⁇ x ⁇ 1.2, 0.8 ⁇ a ⁇ 1, 0 ⁇ b ⁇ 0.2, -0.1 ⁇ c ⁇ 0.2.
  • the chemical formula of lithium nickel cobalt manganate or lithium nickel cobalt aluminate can be as chemical formula 2:
  • M2 represents selected from cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), At least one of copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), tungsten (W), zirconium (Zr), and silicon (Si),
  • the values of y, d, e, and f are in the following ranges: 0.8 ⁇ y ⁇ 1.2, 0.3 ⁇ d ⁇ 0.98, 0.02 ⁇ e ⁇ 0.7, -0.1 ⁇ f ⁇ 0.2.
  • the chemical formula of lithium manganate can be as chemical formula 3:
  • M3 represents selected from cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), At least one of copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr) and tungsten (W), with z, g and h values in the following ranges respectively Inner: 0.8 ⁇ z ⁇ 1.2, 0 ⁇ g ⁇ 1.0 and -0.2 ⁇ h ⁇ 0.2.
  • the weight of the positive electrode active material layer is 1.5 to 15 times the weight of the negative electrode active material layer. In some embodiments, the weight of the positive active material layer is 3 to 10 times the weight of the negative active material layer. In some embodiments, the weight of the positive active material layer is 5 to 8 times the weight of the negative active material layer. In some embodiments, the weight of the positive active material layer is 1.5 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times the weight of the negative active material layer. , 10 times, 11 times, 12 times, 13 times, 14 times or 15 times.
  • the positive active material layer may have a coating on the surface, or may be mixed with another compound having a coating.
  • the coating may include oxides of coating elements, hydroxides of coating elements, oxyhydroxides of coating elements, oxycarbonates of coating elements, and hydroxycarbonates of coating elements ( At least one coating element compound selected from hydroxycarbonate).
  • the compound used for the coating may be amorphous or crystalline.
  • the coating element contained in the coating may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, F, or a mixture thereof.
  • the coating can be applied by any method as long as the method does not adversely affect the performance of the positive electrode active material.
  • the method may include any coating method well-known to those of ordinary skill in the art, such as spraying, dipping, and the like.
  • the positive active material layer further includes a binder, and optionally further includes a positive conductive material.
  • the binder can improve the binding of the positive electrode active material particles to each other, and also improve the binding of the positive electrode active material to the current collector.
  • binders include polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl chloride Vinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin, nylon, etc.
  • the positive electrode active material layer includes a positive electrode conductive material, thereby imparting conductivity to the electrode.
  • the positive electrode conductive material may include any conductive material as long as it does not cause a chemical change.
  • Non-limiting examples of positive electrode conductive materials include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., Including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (for example, polyphenylene derivatives), and mixtures thereof.
  • the positive electrode current collector used in the electrochemical device according to the present application may be aluminum (Al), but is not limited thereto.
  • the electrolyte that can be used in the embodiments of the present application may be an electrolyte known in the prior art.
  • the electrolytes that can be used in the electrolyte of the embodiments of the present application include, but are not limited to: inorganic lithium salts, such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF 4 , LiSbF 6 , LiSO 3 F, LiN(FSO 2 ) 2, etc.; Fluorine-containing organic lithium salts, such as LiCF 3 SO 3 , LiN(FSO 2 )(CF 3 SO 2 ), LiN(CF 3 SO 2 ) 2 , LiN(C 2 F 5 SO 2 ) 2 , cyclic 1,3- Lithium hexafluoropropane disulfonimide, lithium cyclic 1,2-tetrafluoroethane disulfonimide, LiN (CF 3 SO 2 ) (C 4 F 9 SO 2 ), LiC (CF 3 SO 2 ) 3.
  • inorganic lithium salts such as LiClO 4 , LiAsF 6 , LiPF 6 , LiBF
  • Lithium salt containing dicarboxylic acid complex such as bis(oxalato) lithium borate, difluorooxalic acid Lithium borate, tris(oxalato)lithium, difluorobis(oxala
  • the electrolyte includes a combination of LiPF 6 and LiBF 4.
  • the electrolyte includes a combination of an inorganic lithium salt such as LiPF 6 or LiBF 4 and a fluorine-containing organic lithium salt such as LiCF 3 SO 3 , LiN(CF 3 SO 2 ) 2 , and LiN(C 2 F 5 SO 2 ) 2 .
  • the electrolyte includes LiPF 6 .
  • the concentration of the electrolyte is in the range of 0.8-3 mol/L, for example, in the range of 0.8-2.5 mol/L, in the range of 0.8-2 mol/L, in the range of 1-2 mol/L, for example It is 1mol/L, 1.15mol/L, 1.2mol/L, 1.5mol/L, 2mol/L or 2.5mol/L.
  • Solvents that can be used in the electrolyte of the embodiments of the present application include, but are not limited to, cyclic carbonate, chain carbonate, cyclic carboxylic acid ester, chain carboxylic acid ester, cyclic ether, chain ether, phosphorus-containing Organic solvents, sulfur-containing organic solvents and aromatic fluorine-containing solvents.
  • the cyclic carbonate includes, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate.
  • the cyclic carbonate has 3-6 carbon atoms.
  • the chain carbonate includes, but is not limited to: dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate (DEC), methyl n-propyl carbonate, ethyl n-propyl carbonate Carbonic acid esters, di-n-propyl carbonate and other chain carbonates, as chain carbonates substituted by fluorine, such as bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate, bis(trifluoromethyl) ) Carbonate, bis(2-fluoroethyl)carbonate, bis(2,2-difluoroethyl)carbonate, bis(2,2,2-trifluoroethyl)carbonate, 2-fluoroethyl Methyl carbonate, 2,2-difluoroethyl methyl carbonate and 2,2,2-trifluoroethyl methyl carbonate.
  • fluorine such as bis(fluoromethyl)carbonate, bis(difluoromethyl)carbonate,
  • cyclic carboxylic acid esters include, but are not limited to, ⁇ -butyrolactone and ⁇ -valerolactone.
  • part of the hydrogen atoms of the cyclic carboxylic acid ester may be substituted by fluorine.
  • the chain carboxylic acid esters include, but are not limited to: methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, tertiary acetate Butyl ester, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate , Methyl valerate, ethyl valerate, methyl pivalate and ethyl pivalate.
  • part of the hydrogen atoms of the chain carboxylic acid ester may be replaced by fluorine.
  • the fluorine-substituted chain carboxylic acid esters include, but are not limited to: methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, and trifluoroacetic acid 2,2 , 2-Trifluoroethyl ester.
  • cyclic ethers include, but are not limited to, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 2-methyl 1,3-dioxolane, 4-methyl 1 , 3-dioxolane, 1,3-dioxane, 1,4-dioxane and dimethoxypropane.
  • chain ethers include, but are not limited to, dimethoxymethane, 1,1-dimethoxyethane, 1,2-dimethoxyethane, diethoxymethane, 1 ,1-diethoxyethane, 1,2-diethoxyethane, ethoxymethoxymethane, 1,1-ethoxymethoxyethane and 1,2-ethoxymethane Oxyethane.
  • the phosphorus-containing organic solvent includes, but is not limited to, trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene phosphate Ethyl ester, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphate and tris(2,2, 3,3,3-pentafluoropropyl) ester.
  • sulfur-containing organic solvents include, but are not limited to, sulfolane, 2-methyl sulfolane, 3-methyl sulfolane, dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, methyl propyl sulfone Sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, and dibutyl sulfate.
  • part of the hydrogen atoms of the sulfur-containing organic solvent may be replaced by fluorine.
  • the aromatic fluorine-containing solvent includes, but is not limited to, fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.
  • the solvent used in the electrolyte of the present application includes one or more of the above.
  • the solvent used in the electrolyte of the present application includes cyclic carbonate, chain carbonate, cyclic carboxylic acid ester, chain carboxylic acid ester, and combinations thereof.
  • the solvent used in the electrolyte of the present application includes an organic solvent selected from the group consisting of: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propionic acid Propyl ester, n-propyl acetate, ethyl acetate and combinations thereof.
  • the solvent used in the electrolyte of the present application includes: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ⁇ -butyrolactone or a combination thereof .
  • the additives that can be used in the electrolyte of the embodiments of the present application include, but are not limited to, compounds with 2-3 cyano groups, cyclic carbonates containing carbon-carbon double bonds, compounds containing sulfur-oxygen double bonds, difluorophosphoric acid lithium.
  • the compound having 2-3 cyano groups may include selected from succinonitrile (SN), adiponitrile (ADN), ethylene glycol bis(propionitrile) ether (EDN), 1, 3, 5-glutaronitrile, 1,2,3-propanetricarbonitrile, 1,3,6-hexamethylenetricarbonitrile (HTCN), 1,2,6-hexamethylenetricarbonitrile, 1,2,3-tris(2-cyanide At least one of ethoxy)propane (TCEP) or 1,2,4-tris(2-cyanoethoxy)butane.
  • SN succinonitrile
  • ADN adiponitrile
  • EDN ethylene glycol bis(propionitrile) ether
  • HTCN 1,3,6-hexamethylenetricarbonitrile
  • TCEP ethoxypropane
  • 1,2,4-tris(2-cyanoethoxy)butane 1,2,4-tris(2-cyanoethoxy)butane.
  • the cyclic carbonate having a carbon-carbon double bond specifically includes, but is not limited to: vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, vinyl ethylene ethylene carbonate Or at least one of carbonic acid-1,2-dimethyl vinylene.
  • compounds containing sulfur and oxygen double bonds include, but are not limited to: vinyl sulfate, 1,2-propanediol sulfate, 1,3-propane sultone, 1-fluoro-1,3-propane At least one of sultone, 2-fluoro-1,3-propane sultone or 3-fluoro-1,3-propane sultone.
  • a separator is provided between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the isolation film that can be used in the embodiments of the present application are not particularly limited, and they can be any technology disclosed in the prior art.
  • the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application, or the like.
  • the isolation film may include a substrate layer and a surface treatment layer.
  • the substrate layer is a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • the porous structure can improve the heat resistance, oxidation resistance and electrolyte infiltration performance of the isolation membrane, and enhance the adhesion between the isolation membrane and the pole piece.
  • a surface treatment layer is provided on at least one surface of the substrate layer.
  • the surface treatment layer may be a polymer layer or an inorganic substance 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 selected from alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer is selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride, poly At least one of (vinylidene fluoride-hexafluoropropylene).
  • the application also provides an electrochemical device, which includes a positive electrode, an electrolyte, and a negative electrode.
  • the positive electrode includes a positive electrode active material layer and a positive electrode current collector.
  • the negative electrode includes a negative electrode active material layer and a negative electrode current collector.
  • the material layer includes the negative active material according to the present application.
  • the electrochemical device of the present application includes any device that undergoes an electrochemical reaction, and specific examples thereof include all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
  • the electrochemical device is a lithium secondary battery, including a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
  • the application also provides an electronic device, which includes the electrochemical device according to the application.
  • the use of the electrochemical device of the present application is not particularly limited, and it can be used in any electronic device known in the prior art.
  • the electrochemical device of the present application can be used in, but not limited to, notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, and headsets.
  • Stereo headsets video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, cars, motorcycles, power assistance Bicycles, bicycles, lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large household storage batteries and lithium-ion capacitors, etc.
  • the negative active material graphite, styrene-butadiene rubber (abbreviated as SBR) and sodium carboxymethyl cellulose (abbreviated as CMC) are fully stirred and mixed in a deionized water solvent at a weight ratio of 95:2:3 to form a uniform negative electrode Slurry;
  • This slurry is coated on both surfaces of the current collector copper foil pre-coated with a primer layer (such as carbon black), the thickness of the primer layer is 1.0 ⁇ m, and the negative electrode activity is obtained by cold pressing after drying
  • the material layer is cut and welded to obtain the negative electrode.
  • the weight of the negative electrode active material layer was 0.100 mg/mm 2 , and the thickness of the negative electrode active material layer was 130 ⁇ m.
  • the weight of the negative electrode active material layer is based on the weight of the negative electrode active material layer on either surface of the negative electrode current collector.
  • the aspect ratio and sphericity of the negative active material can be controlled in the following way: during the preparation of the negative active material, the prepared graphite enters the shaping zone through the feeding system for grinding, so that the particle surface has edges and corners, thereby controlling the particle size Aspect ratio and sphericity. Then, the polished particles are classified through the self-dividing classification zone to obtain the particles of the desired distribution.
  • the primary particles of the negative electrode active material refer to the samples that are directly graphitized with particles with a certain particle size distribution after being crushed.
  • the secondary particles of the negative electrode active material refer to the samples that are crushed and mixed with a certain proportion of asphalt and passed through the granulation equipment in a certain Heat treatment at temperature makes the particles adhere to each other through pitch, and then graphitizes to obtain secondary particles.
  • the content of the primary particles in the negative electrode active material is obtained by controlling the mixing ratio of the primary particles and the secondary particles.
  • the test method for the powder compaction of the negative electrode active material is to weigh 1g of the powder and place it in a mold (with a diameter of 13mm), then place the mold in an automatic powder compaction test equipment (Sansi Zongheng UTM7305), and apply a certain pressure to the mold through the equipment for the final test. The compacted density of the powder under the condition of 5t is obtained.
  • LiCoO 2 lithium cobaltate
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the mass ratio of ethylene carbonate (abbreviated as EC), diethyl carbonate (abbreviated as DEC) and propylene carbonate (abbreviated as PC) is 3:4:3 Mix well, and then dissolve the fully dried lithium salt LiPF 6 in the above non-aqueous solvent, and finally add 3wt% of fluoroethylene carbonate, 2wt% of 1,3-propane sultone, and 2wt% of succinonitrile.
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • PC propylene carbonate
  • a polyethylene (PE) porous polymer film with a thickness of 7 ⁇ m was used as the separator.
  • the positive electrode, separator, and negative electrode in order, so that the separator is between the positive electrode and the negative electrode for isolation, and then wind to obtain a bare cell; after welding the tabs, place the bare cell on the outer packaging foil aluminum plastic
  • the prepared electrolyte is injected into the dried bare cell, and the soft-packed lithium-ion battery is obtained through the processes of vacuum packaging, standing, forming, shaping, and capacity testing.
  • Simpatec QICPIC dynamic particle image analyzer was used to test the width-to-length ratio distribution of the negative electrode active material.
  • Simpatec QICPIC dynamic particle image analyzer was used to test the sphericity distribution of the negative electrode active material.
  • Instron (model 33652) tester to test the bonding between the negative electrode active material layer and the negative electrode current collector: take a 15-20mm long pole piece, fix it on the steel plate with 3M double-sided adhesive tape, and attach the adhesive tape Stick it on the surface of the negative active material layer, connect one side of the adhesive tape to the paper tape of equal width, adjust the limit block of the tensile machine to a suitable position, turn the paper tape upwards and slide 40mm, the sliding rate is 50mm/min , To test the binding force between the negative electrode active material layer and the negative electrode current collector at 180° (ie, stretched in the opposite direction).
  • the X-ray diffraction pattern of the negative active material layer in the X-ray diffraction pattern of the (004) surface diffraction line pattern and the (110) surface diffraction line pattern are tested .
  • the test conditions are as follows: CuK ⁇ radiation is used for X-rays, and CuK ⁇ radiation is removed by a filter or a monochromator.
  • the working voltage of the X-ray tube is (30-35) kV, and the working current is (15-20) mA.
  • the scanning speed of the counter is 1/4 (°) /min.
  • the scanning range of the diffraction angle 2 ⁇ is 53°-57°.
  • the scanning range of the diffraction angle 2 ⁇ is 75°-79°.
  • the peak area obtained from the (004) plane diffraction line pattern is denoted as C004.
  • the peak area obtained from the (110) plane diffraction line pattern is denoted as C110.
  • the ratio of C004/C110 of the negative active material layer was calculated.
  • a sample of the negative active material layer was prepared into a complete wafer.
  • Each example or comparative example tested 30 samples, and the volume of each sample was about 0.35 cm 3 .
  • the porosity of the negative electrode active material layer was tested.
  • the lithium-ion battery was connected to the Bio-Logic VMP3B electrochemical workstation produced by Bio-Roger Company in France for testing.
  • the frequency range was 30mHz to 50kHz, and the amplitude was 5mV.
  • the impedance complex plane diagram is used to analyze the data, and the lithium ion liquid phase transfer impedance (R ion ) is obtained.
  • 2C discharge capacity preservation rate 2C discharge capacity/0.1C discharge capacity ⁇ 100%.
  • the lithium ion battery was allowed to stand at 25°C for 5 minutes.
  • the lithium-ion battery was charged with a constant current of 0.7C to a voltage of 4.45V, and then charged with a constant voltage of 4.45V to 0.05C, and left to stand for 5 minutes.
  • Adjust the furnace temperature to -20°C repeat the above charging and discharging process, and test the discharge capacity of the lithium-ion battery at -20°C. Calculate the discharge capacity retention rate of lithium-ion batteries at -20°C by the following formula:
  • Discharge capacity retention rate -20°C discharge capacity/25°C discharge capacity ⁇ 100%.
  • the lithium-ion battery was charged to 4.45V at a constant current of 1.5C, then charged to 0.05C at a constant voltage of 4.45V, and left to stand for 30 minutes. Discharge at 0.1C for 10 seconds and record the voltage value as U1. Discharge at 1C for 360 seconds and record the voltage value as U2. Repeat the charging and discharging steps 5 times. "1C" is the current value at which the lithium-ion battery capacity is completely discharged within one hour.
  • the DCR described in this application refers to the DC resistance of a lithium-ion battery at 10% state of charge (SOC).
  • the lithium ion battery is charged to 4.45V at a constant current of 0.7C or 2C, then charged to 0.05C at a constant voltage of 4.45V, and left to stand for 5 minutes. Then discharge to 3.0V at a constant current of 0.5C and stand still for 5 minutes. Repeat the above charging and discharging process 10 times. Fully charge the battery, disassemble it under dry conditions, and take a photo to record the state of the negative electrode.
  • the disassembled negative electrode is golden-yellow as a whole, and a very small part of the negative electrode can be observed in gray; and the area of the gray area is less than 2%, it is judged that there is no lithium precipitation.
  • the disassembled negative electrode is gray as a whole, golden yellow can be observed in some positions; and the area of the gray area is between 20% and 60%, it is judged to be lithium-deposited.
  • the disassembled negative electrode is gray as a whole and the area of the gray area is greater than 60%, it is judged as serious lithium evolution.
  • a copper wire was additionally inserted as a reference electrode, and lithium was plated on the negative electrode at a current of 20 ⁇ A for 6 hours to obtain a three-electrode lithium ion battery.
  • the three-electrode lithium-ion battery was connected to the Bio-Logic VMP3B electrochemical station produced by Bio-Logic, France, for testing.
  • the frequency range was 30mHz to 50kHz, and the amplitude was 5mV.
  • the impedance complex plane diagram is used to analyze the data, and the charge transfer impedance (Rct) of the lithium-ion battery is obtained.
  • a charge-coupled device was used to test the width H1 of the cold-pressed negative electrode in the X/Y direction.
  • the negative electrode is made into a lithium ion battery according to the preparation steps of a lithium ion battery.
  • the lithium ion battery is charged to 4.45V at a constant current of 0.7C after standing at 25°C for 5 minutes, and then charged to 0.05C at a constant voltage of 4.45V .
  • Use a charge-coupled device (CCD) to test the width H2 of the negative electrode along the X/Y direction (as shown in Figure 3). Calculate the expansion rate of the negative electrode along the X/Y direction by the following formula:
  • the thickness of the negative electrode treated with a certain compaction density (1.78g/cc) is measured, and it is recorded as T1.
  • the negative electrode is made into a lithium ion battery according to the preparation steps of a lithium ion battery, and the lithium ion battery is allowed to stand at 25° C. for 5 minutes and then charged to 3.95V (ie, 50% SOC) at a constant current of 0.7C.
  • Expansion rate in Z direction (T2-T1)/T1 ⁇ 100%.
  • the lithium-ion battery was charged to 4.45V at a constant current of 0.7C at 45°C for 5 minutes, then charged to 0.05C at a constant voltage of 4.45V, and left to stand for 5 minutes.
  • the thickness of the lithium-ion battery at three locations is tested by the PPG test method, and the average value is recorded as PPG 0
  • the thickness of the lithium ion battery is tested by the MMC test method at three locations, and the average value is recorded as MMC 0 .
  • discharge the lithium-ion battery to 3.0V at a constant current of 0.5C and stand still for 5 minutes.
  • the battery thickness is recorded every 50 times during the 1-200th charge-discharge cycle
  • the battery thickness is recorded every 100 times during the 300-500th charge-discharge cycle
  • the lithium-ion battery is tested every time
  • the thickness of the three points is averaged and recorded as PPG x and MMC x (x represents the number of cycles), and the maximum value of the thickness of the MMC tested at the three test points is recorded as Max(MMC x ).
  • the difference between MMC x and MMC 0 is recorded as the increase in battery thickness.
  • Cycle expansion rate (45°C) MMC x -MMC 0 /MMC 0 ⁇ 100%.
  • Cycle deformation rate (45°C) [PPG x /Max(MMC x )-1] ⁇ 100%.
  • the above-mentioned PPG test method is: use the PPG soft-pack battery thickness gauge (manufactured by Shenzhen Automate Automation Technology Co., Ltd.), place the lithium ion battery on the lower plate of the thickness gauge, and the upper cover will drop at a constant speed during the test.
  • the thickness of the lithium-ion battery measured by pressure sensor is the PPG thickness.
  • the above-mentioned MMC test method is: use a micrometer tester (made by Mitutoyo, Japan, model: MDC-25SX) to measure the thickness of the positive electrode tab of the lithium-ion battery, measure three different positions for each sample, take the average value, and record it as MMC thickness.
  • a micrometer tester made by Mitutoyo, Japan, model: MDC-25SX
  • the MMC test method tested the lithium-ion battery at three different points at 150% SOC.
  • the thickness of the location point, the maximum value is recorded as Max (MMC 5 ).
  • Table 1 shows the influence of the width-to-length ratio distribution and the sphericity distribution of the negative active material on the performance of the lithium-ion battery.
  • the results show that when the width-to-length ratio distribution and sphericity distribution of the negative electrode active material meet the following conditions: 0.4 ⁇ AR 10 ⁇ 0.55, 0.48 ⁇ S 10 ⁇ 0.60, 0.6 ⁇ AR 50 ⁇ 0.75, 0.68 ⁇ S 50 ⁇ 0.82, 0.82 ⁇ AR 90 ⁇ 0.90,0.85 ⁇ S 90 ⁇ 0.95, the negative electrode active material particles with the use of different shapes, rounded form voids between the negative electrode active material than the elongate corners and there is a negative electrode active material particles filled in the pores, This makes the negative active material present a relatively round but still angular appearance, which can significantly reduce the high temperature cycle expansion rate and DC resistance (DCR) of the lithium-ion battery, and prevent the lithium-ion battery from precipitation during the cycle.
  • the lithium phenomenon that is, significantly improves the performance of lithium-ion batteries
  • Table 2 shows the influence of the orientation of the negative electrode active material layer on the performance of the lithium ion battery.
  • the stress generated by the insertion and deintercalation of lithium ions is directed in various directions, along the Z direction and The expansion rate along the X/Y direction is balanced, which can significantly reduce the overcharge deformation rate, the thickness growth value and the cycle deformation rate of the lithium ion battery, that is, the deformation problem of the lithium ion battery is significantly improved.
  • Table 3 shows the influence of the proportion of the number of primary particles of the negative active material and the compaction density, the weight of the negative active material layer and the coating on the performance of the lithium ion battery. Except for the parameters listed in Table 3, the other settings of Embodiments 28-39 are the same as those of Embodiment 10.
  • Table 4 shows the influence of the porosity of the negative electrode active material layer on the performance of the lithium ion battery.
  • references to “embodiments”, “parts of embodiments”, “one embodiment”, “another example”, “examples”, “specific examples” or “partial examples” throughout the specification mean that At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: “in some embodiments”, “in an embodiment”, “in one example”, “in another example”, “in an example “In”, “in a specific example” or “exemplary”, which are not necessarily quoting the same embodiment or example in this application.
  • the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

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Abstract

一种负极活性材料及使用其的电化学装置和电子装置，该一种负极活性材料在一定颗粒体积累计分布下具有特定的宽长比和球形度，有助于改善电化学装置的倍率性能、动力学性能和变形问题。

Description

负极活性材料及使用其的电化学装置和电子装置 技术领域
本申请涉及储能领域，具体涉及一种负极活性材料及使用其的电化学装置和电子装置。
背景技术
电化学装置(例如，锂离子电池)由于具有环境友好、工作电压高、比容量大和循环寿命长等优点而被广泛应用，已成为当今世界最具发展潜力的新型绿色化学电源。小尺寸锂离子电池通常用作驱动便携式电子通讯设备(例如，便携式摄像机、移动电话或者笔记本电脑等)的电源，特别是高性能便携式设备的电源。具有高输出特性的中等尺寸和大尺寸锂例子电池被发展应用于电动汽车(EV)和大规模储能系统(ESS)。随着锂离子电池的广泛应用，其倍率性能、动力学性能和变形问题已成为重要的研发方向。这些性能均与负极析锂现象相关。如何改善负极的析锂现象已成为亟待解决的关键技术问题。改进负极中的活性材料是解决上述问题的研究方向之一。
有鉴于此，确有必要提供一种改进的负极活性材料及使用其的电化学装置和电子装置。
发明内容
本申请通过提供一种负极活性材料及使用其的电化学装置和电子装置以试图在至少某种程度上解决至少一种存在于相关领域中的问题。
根据本申请的一个方面，本申请提供了一种负极活性材料，其中利用动态颗粒图像分析仪测试，当所述负极活性材料的颗粒体积累计分布为10％时，所述负极活性材料的宽长比AR 10满足0.4≤AR 10≤0.55，所述负极活性材料的球形度S 10满足0.48≤S 10≤0.60。
在一些实施例中，所述负极活性材料的宽长比AR 10满足0.42≤AR 10≤0.52。在一些实施例中，所述负极活性材料的宽长比AR 10满足0.45≤AR 10≤0.50。在一些实施例中，所述负极活性材料的宽长比AR 10为0.4、0.42、0.45、0.48、0.50、0.52、0.55或在上述任意两个数值所组成的范围内。
在一些实施例中，所述负极活性材料的球形度S 10满足0.50≤S 10≤0.55。在一些实 施例中，所述负极活性材料的球形度S 10满足0.48、0.50、0.52、0.55、0.58、0.60或在上述任意两个数值所组成的范围内。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为50％时，所述负极活性材料满足条件(a)或(b)中的至少一者：
(a)所述负极活性材料的宽长比AR 50满足0.6≤AR 50≤0.75；
(b)所述负极活性材料的球形度S 50满足0.68≤S 50≤0.82。
在一些实施例中，所述负极活性材料的宽长比AR 50满足0.62≤AR 50≤0.72。在一些实施例中，所述负极活性材料的宽长比AR 50满足0.65≤AR 50≤0.70。在一些实施例中，所述负极活性材料的宽长比AR 50满足0.6、0.62、0.65、0.68、0.70、0.72、0.75或在上述任意两个数值所组成的范围内。
在一些实施例中，所述负极活性材料的球形度S 50满足0.70≤S 50≤0.80。在一些实施例中，所述负极活性材料的球形度S 50满足0.72≤S 50≤0.75。在一些实施例中，所述负极活性材料的球形度S 50满足0.68、0.70、0.72、0.75、0.78、0.80、0.82或在上述任意两个数值所组成的范围内。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为90％时，所述负极活性材料满足条件(c)或(d)中的至少一者：
(c)所述负极活性材料的宽长比AR 90满足0.82≤AR 90≤0.90；
(d)所述负极活性材料的球形度S 90满足0.85≤S 90≤0.95。
在一些实施例中，所述负极活性材料的宽长比AR 90满足0.85≤AR 90≤0.88。在一些实施例中，所述负极活性材料的宽长比AR 90满足0.82、0.85、0.88、0.90或在上述任意两个数值所组成的范围内。
在一些实施例中，所述负极活性材料的球形度S 90满足0.88≤S 90≤0.90。在一些实施例中，所述负极活性材料的球形度S 90满足0.85、0.88、0.90、0.92、0.95或在上述任意两个数值所组成的范围内。
根据本申请的实施例，所述负极活性材料的压实密度大于1.90g/cm 3。在一些实施例中，所述负极活性材料的压实密度大于1.95g/cm 3。在一些实施例中，所述负极活性材料的压实密度大于2.0g/cm 3。
根据本申请的实施例，所述负极活性材料包括一次颗粒和二次颗粒，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为20％至55％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为25％至50％。在一些实施例 中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为30％至40％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为30％至35％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为25％、30％、35％、40％、45％、50％或在上述任意两个数值所组成的范围内。
根据本申请的另一个方面，本申请提供了一种电化学装置，其包括正极、负极、隔离膜和电解液，其中所述负极包括负极集流体和负极活性材料层，所述负极活性材料层包含根据本申请所述的负极活性材料。
根据本申请的实施例，所述负极满足条件(e)至(g)中的至少一者：
(e)所述负极活性材料层的重量为0.095mg/mm 2至0.105mg/mm 2；
(f)由X射线衍射图谱测定得到的所述负极活性材料层的(004)面的峰面积C004和(110)面的峰面积C110的比值C004/C110在10至20的范围内；
(g)所述负极活性材料层具有20％至45％的孔隙率。
在一些实施例中，所述负极活性材料层的重量为0.095mg/mm 2至0.105mg/mm 2。在一些实施例中，所述负极活性材料层的重量为0.095mg/mm 2、0.097mg/mm 2、0.099mg/mm 2、0.101mg/mm 2、0.103mg/mm 2、0.105mg/mm 2或在上述任意两个数值所组成的范围内。
在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110在12至18的范围内。在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110在14至16的范围内。在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110为10、11、12、13、14、15、16、17、18、19、20或在上述任意两个数值所组成的范围内。
在一些实施例中，所述负极活性材料层具有25％至40％的孔隙率。在一些实施例中，所述负极活性材料层具有30％至35％的孔隙率。在一些实施例中，所述负极活性材料层的孔隙率为20％、25％、30％、35％、40％、45％或在上述任意两个数值所组成的范围内。
根据本申请的实施例，所述负极集流体与所述负极活性材料层之间进一步包含涂层，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶50至1∶120的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶60至1∶100的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶80至1∶90的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚 度的比值为1∶50、1∶60、1∶70、1∶80、1∶90、1∶100、1∶110、1∶120或在上述任意两个数值所组成的范围内。
根据本申请的实施例，所述负极活性材料层与所述负极集流体之间的粘结力大于18N/m。在一些实施例中，所述负极活性材料层与所述负极集流体之间的粘结力大于20N/m。在一些实施例中，所述负极活性材料层与所述负极集流体之间的粘结力大于25N/m。
根据本申请的实施例，所述电化学装置满足以下关系：Y≤0.417X+A，其中：X为所述电化学装置的荷电状态，1＜X≤1.5，当所述电化学装置的荷电状态为1时，所述电化学装置的厚度为Amm，当所述电化学装置的荷电状态为X时，所述电化学装置的厚度为Ymm。在一些实施例中，X为1.1、1.2，、1.3、1.4或1.5。
根据本申请的又一个方面，本申请提供了一种电子装置，其包括根据本申请所述的电化学装置。
本申请的额外层面及优点将部分地在后续说明中描述、显示、或是经由本申请实施例的实施而阐释。
附图说明
在下文中将简要地说明为了描述本申请实施例或现有技术所必要的附图以便于描述本申请的实施例。显而易见地，下文描述中的附图仅只是本申请中的部分实施例。对本领域技术人员而言，在不需要创造性劳动的前提下，依然可以根据这些附图中所例示的结构来获得其他实施例的附图。
图1展示了根据本申请实施例的负极活性材料在不同颗粒体积累计分布下的宽长比。
图2展示了根据本申请实施例的负极活性材料在不同颗粒体积累计分布下的球形度。
图3展示了负极结构的X、Y和Z方向的示意图。
图4展示了根据本申请实施例的负极材料的扫描电子显微镜(SEM)图。
具体实施方式
本申请的实施例将会被详细的描示在下文中。在本申请说明书中，将相同或相似的组件以及具有相同或相似的功能的组件通过类似附图标记来表示。在此所描述的有关附图的实施例为说明性质的、图解性质的且用于提供对本申请的基本理解。本申请的实施例不应该被解释为对本申请的限制。
在具体实施方式及权利要求书中，由术语“中的至少一种”连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一种”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一种”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
如本文中所使用，负极活性材料的“宽长比”指的是负极活性材料颗粒的宽径与长径的比值。负极活性材料的宽长比可通过动态颗粒图像分析(例如，使用新帕泰克QICPIC动态颗粒图像分析仪)获得。负极活性材料颗粒的“宽径”指的是与颗粒的投影图像相切的平行线之间的最小数值。负极活性材料颗粒的“长径”指的是与颗粒的投影图像相切的平行线之间的最大数值。负极活性材料的宽长比较小时，负极活性材料颗粒呈细长形状。负极活性材料的宽长比越接近1，表明负极活性材料颗粒的宽径与长径越相近，即，负极活性材料颗粒越接近圆形。
如本文中所使用，“AR n”指的是当负极活性材料的颗粒体积累计分布为n％时所对应的负极活性材料颗粒的宽长比。“AR 10”表示当负极活性材料的颗粒体积累计分布为10％时所对应的负极活性材料颗粒的宽长比，如图1中“AR 10”所示。“AR 50”表示当负极活性材料的颗粒体积累计分布为50％时所对应的负极活性材料颗粒的宽长比，如图1中“AR 50”所示。“AR 90”表示当负极活性材料的颗粒体积累计分布为10％时所对应的负极活性材料颗粒的宽长比，如图1中“AR 90”所示。
如本文中所使用，负极活性材料的“球形度”指的是与负极活性材料颗粒具有相同体积的球体的投影的周长与负极活性材料颗粒的实际投影的周长的比值。负极活性材料的球形度越接近1，表明负极活性材料颗粒越接近球形。当负极活性材料的球形度为1时，负极活性材料颗粒为正球形。负极活性材料的球形度可通过动态颗粒图像分析(例如，使用新帕泰克QICPIC动态颗粒图像分析仪)获得。
如本文中所使用，“S n”指的是当负极活性材料的颗粒体积累计分布为n％时所对应的负极活性材料颗粒的球形度。“S 10”表示当负极活性材料的颗粒体积累计分布为10％时所对应的负极活性材料颗粒的球形度，如图2中“S 10”所示。“S 50”表示当负极活性材料的颗粒体积累计分布为50％时所对应的负极活性材料颗粒的球形度，如图2中“S 50”所示。“S 90”表示当负极活性材料的颗粒体积累计分布为90％时所对应的负极活性材料颗粒的球形度，如图2中“S 90”所示。
随着电化学装置(例如，锂离子电池，下文以锂离子电池为例)的广泛应用，其快速充电能力成为评价电化学装置性能的一个重要指标。倍率性能可反映出锂离子电池的快速充电能力。在锂离子电池的循环过程中，负极表面可能会出现析锂现象，其会显著降低锂离子电池的倍率性能。尤其是在低温下，负极活性材料的动力学性能有所下降，导致负极的电化学极化增大，更易发生析锂现象。析出的锂金属可能会形成锂枝晶，其会穿破隔离膜，引发正极与负极之间的短路。此外，锂离子电池在循环过程中的形变也会导致析锂现象的产生。因此，如何改善负极的析锂现象已成为研发方向之一。
本申请通过调整负极活性材料的形状及其分布可改善电化学装置在循环过程中的析锂现象以提高电化学装置的倍率性能和动力学性能，同时改善电化学装置的变形问题。具体而言，本申请提供了一种负极活性材料，其中利用动态颗粒图像分析仪测试，当所述负极活性材料的颗粒体积累计分布为10％时，所述负极活性材料的宽长比AR 10满足0.4≤AR 10≤0.55，所述负极活性材料的球形度S 10满足0.48≤S 10≤0.60。
在一些实施例中，所述负极活性材料的宽长比AR 10满足0.42≤AR 10≤0.52。在一些实施例中，所述负极活性材料的宽长比AR 10满足0.45≤AR 10≤0.50。在一些实施例中，所述负极活性材料的宽长比AR 10为0.4、0.42、0.45、0.48、0.50、0.52、0.55或在上述任意两个数值所组成的范围内。
在一些实施例中，所述负极活性材料的球形度S 10满足0.50≤S 10≤0.55。在一些实施例中，所述负极活性材料的球形度S 10满足0.48、0.50、0.52、0.55、0.58、0.60或在上述任意两个数值所组成的范围内。
负极活性材料(例如，石墨)的颗粒通常以一定范围的孔隙率按不同取向一层一层地堆积在负极集流体表面形成负极活性材料层。由于负极活性材料颗粒呈无规则状态堆积，过于细长的负极活性材料颗粒(例如，AR 10＜0.3)会减小颗粒间的孔隙，不利于电解液的浸润。类球形的负极活性材料颗粒(例如，S 10＞0.9)会延长锂离子的传递路径，增加锂离子嵌入和脱出的阻力。在负极活性材料的制备过程中，可通过分级的方式控制负极活性材料的宽长比，然后通过整形的方式去除负极活性材料表面部分的棱角以控制负极活性材料的球形度。当负极活性材料的满足0.4≤AR 10≤0.55和0.48≤S 10≤0.60时，一部分负极活性材料颗粒较为细长且存在棱角，其可填充在负极活性材料的孔隙中，有助于抑制由锂离子的嵌入和脱嵌导致的负极活性材料层的膨胀，由此改善锂离子电池在循环过程中的变形问题和析锂现象。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为50％时，所述负 极活性材料的宽长比AR 50满足0.6≤AR 50≤0.75。在一些实施例中，所述负极活性材料的宽长比AR 50满足0.62≤AR 50≤0.72。在一些实施例中，所述负极活性材料的宽长比AR 50满足0.65≤AR 50≤0.70。在一些实施例中，所述负极活性材料的宽长比AR 50满足0.6、0.62、0.65、0.68、0.70、0.72、0.75或在上述任意两个数值所组成的范围内。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为50％时，所述负极活性材料的球形度S 50满足0.68≤S 50≤0.82。在一些实施例中，所述负极活性材料的球形度S 50满足0.70≤S 50≤0.80。在一些实施例中，所述负极活性材料的球形度S 50满足0.72≤S 50≤0.75。在一些实施例中，所述负极活性材料的球形度S 50满足0.68、0.70、0.72、0.75、0.78、0.80、0.82或在上述任意两个数值所组成的范围内。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为90％时，所述负极活性材料的宽长比AR 90满足0.82≤AR 90≤0.90。在一些实施例中，所述负极活性材料的宽长比AR 90满足0.85≤AR 90≤0.88。在一些实施例中，所述负极活性材料的宽长比AR 90满足0.82、0.85、0.88、0.90或在上述任意两个数值所组成的范围内。
根据本申请的实施例，当所述负极活性材料的颗粒体积累计分布为90％时，所述负极活性材料的球形度S 90满足0.85≤S 90≤0.95。在一些实施例中，所述负极活性材料的球形度S 90满足0.88≤S 90≤0.90。在一些实施例中，所述负极活性材料的球形度S 90满足0.85、0.88、0.90、0.92、0.95或在上述任意两个数值所组成的范围内。
搭配使用不同外观形态的负极活性材料颗粒使负极活性材料满足上述AR 10、AR 50、AR 90、S 10、S 50和S 90时，负极活性材料整体上呈现较圆润但仍有一定棱角的外观形态。整体上较圆润的外观形态使得负极活性材料颗粒形成的堆积层之间存在适量孔隙，缩短锂离子的传输路径，加快锂离子的脱嵌，保证了锂离子在孔隙内的顺利传递。棱角的存在可增加负极活性材料颗粒间的摩擦力，使负极活性材料颗粒在锂离子嵌入和脱嵌过程中受到的应力朝各个方向均匀释放，从而抑制负极活性材料层的膨胀，由此改善锂离子电池在循环过程中的膨胀问题。
根据本申请的实施例，所述负极活性材料的压实密度大于1.90g/cm 3。在一些实施例中，所述负极活性材料的压实密度大于1.95g/cm 3。在一些实施例中，所述负极活性材料的压实密度大于2.0g/cm 3。较大的压实密度可使外观形态具有棱角的负极活性材料颗粒相互咬合，从而呈平行于集流体的方向层叠排列，减小层叠结构之间的孔隙。外观形态呈类球形的颗粒之间依然保留足够的孔隙以保证锂离子的顺利传输。
根据本申请的实施例，所述负极活性材料包括一次颗粒(例如，图4中实线圈出的 颗粒)和二次颗粒(例如，图4中虚线圈出的颗粒)。
根据本申请的实施例，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为20％至55％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为25％至50％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为30％至40％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为30％至35％。在一些实施例中，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为25％、30％、35％、40％、45％、50％或在上述任意两个数值所组成的范围内。当负极活性材料包括上述范围内的量的一次颗粒时，负极活性材料颗粒的各向异性增加，由此可有效地改善锂离子电池在循环过程中的膨胀问题，抑制锂离子电池的变形。同时，具有上述范围内的量的一次颗粒还有助于提高负极活性材料的能量密度。
本申请还提供了一种电化学装置，其包括正极、负极、隔离膜和电解液。以下说明可用于本申请中正极、负极、隔离膜和电解液。
负极
本申请的电化学装置所使用的负极包括负极集流体和负极活性材料层，所述负极活性材料层包含根据本申请所述的负极活性材料。
根据本申请的实施例，所述负极活性材料层设置在所述负极集流体上。在一些实施例中，所述负极活性材料层设置于所述负极集流体的两侧。在一些实施例中，所述负极集流体包含单面负极活性材料层的区域。
根据本申请的实施例，所述负极活性材料层的重量为0.095g/cm 2至0.105g/cm 2。在一些实施例中，所述负极活性材料层的重量为0.095g/cm 2至0.0.101g/cm 2。在一些实施例中，所述负极活性材料层的重量为0.095g/cm 2、0.097g/cm 2、0.099g/cm 2、0.101g/cm 2、0.103g/cm 2、0.105g/cm 2或在上述任意两个数值所组成的范围内。当负极活性材料层的重量在上述范围内时，有助于电解液浸润负极活性材料层，从而加快锂离子的传输。
根据本申请的实施例，由X射线衍射图谱测定得到的所述负极活性材料层的(004)面的峰面积C004和(110)面的峰面积C110的比值C004/C110在10至20的范围内。在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110在12至18的范围内。在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110在14至16的范围内。在一些实施例中，由X射线衍射图谱测定得到的所述负极活性材料层的C004/C110为10、11、12、13、14、15、16、17、18、19、20 或在上述任意两个数值所组成的范围内。负极活性材料层的C004/C110值可反映出负极活性材料层的取向性。C004/C110过大或过小时，负极活性材料层都表现出各向异性大。当C004/C110较大时，即(004)面的峰面积C004较大时，在一定的压实密度下，负极活性材料颗粒倾向于以与集流体平行的方式排列于集流体上。当C004/C110较小时，即(110)面的峰面积C110较大时，在一定的压实密度下，负极活性材料颗粒倾向于以与集流体垂直的方式排列于集流体上。当负极活性材料层的C004/C110至在上述范围内时，一部分负极活性材料颗粒以与集流体平行的方式排列于集流体上，另一部分负极活性材料颗粒以与集流体垂直的方式排列于集流体上，使得负极活性材料层在各个方向上具有适当的各向异性，有助于改善锂离子电池在循环过程中的膨胀和变形问题。根据本申请的实施例，所述负极活性材料层具有20％至45％的孔隙率。在一些实施例中，所述负极活性材料层具有25％至40％的孔隙率。在一些实施例中，所述负极活性材料层具有30％至35％的孔隙率。在一些实施例中，所述负极活性材料层的孔隙率为20％、25％、30％、35％、40％、45％或在上述任意两个数值所组成的范围内。当负极活性材料层的孔隙率在上述范围内时，有助于电解液浸润负极活性材料层，缩短锂离子的传输路径，加快锂离子的脱嵌，同时还有助于形成适量的固体电解质界面(SEI)膜，减少锂离子的损耗。
负极活性材料层的孔隙率可通过控制负极制备过程中辊压压力来实现。通过控制辊压压力，可实现负极活性材料层厚度的连续变化，从而可控制负极活性材料层的孔隙率。负极活性材料层的孔隙率可根据《GB/T24586-2009铁矿石表观密度真密度和孔隙率的测定》标准进行测试得到。
根据本申请的实施例，所述负极集流体与所述负极活性材料层之间进一步包含涂层，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶50至1∶120的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶60至1∶100的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚度的比值在1∶80至1∶90的范围内。在一些实施例中，所述涂层的厚度与所述负极活性材料层的厚度的比值为1∶50、1∶60、1∶70、1∶80、1∶90、1∶100、1∶110、1∶120或在上述任意两个数值所组成的范围内。
根据本申请的实施例，所述涂层包括导电层。在一些实施方案中，所述导电层的导电材料可以包括任何导电材料，只要它不引起化学变化。导电材料的非限制性示例包括基于碳的材料(例如，天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维、碳纳米 管、石墨烯等)、基于金属的材料(例如，金属粉、金属纤维等，例如铜、镍、铝、银等)、导电聚合物(例如，聚亚苯基衍生物)和它们的混合物。
根据本申请的实施例，所述负极活性材料层与所述负极集流体之间的粘结力大于18N/m。在一些实施例中，所述负极活性材料层与所述负极集流体之间的粘结力大于20N/m。在一些实施例中，所述负极活性材料层与所述负极集流体之间的粘结力大于25N/m。当负极活性材料层与负极集流体之间的粘结力在上述范围内时，可避免在负极制备过程中的辊压或分条工序中发生脱膜或产生毛刺，从而可避免安全隐患，同时还可保证电池的内阻在可接受范围内，保证电化学装置的动力学性能。
负极活性材料层与负极集流体之间的粘结可通过控制负极制备过程中的辊压工序来是实现。具体地，负极活性材料层与负极集流体之间的粘结可使用Instron(型号为33652)测试仪进行测试：取15-20mm长的极片，用3M双面胶纸将其固定于钢板上，将胶纸贴在负极活性材料层表面，该胶纸一侧与其等宽的纸带相连接，调整拉力机限位块至合适位置，将纸带向上翻折及滑移40mm，滑移速率为50mm/min，测试180°下(即，反方向拉伸)负极活性材料层与负极集流体之间的粘结力。
根据本申请的实施例，所述电化学装置满足以下关系：Y≤0.417X+A，其中：X为所述电化学装置的荷电状态，1＜X≤1.5，当所述电化学装置的荷电状态为1时，所述电化学装置的厚度为Amm，当所述电化学装置的荷电状态为X时，所述电化学装置的厚度为Y mm。在一些实施例中，X为1.1、1.2，、1.3、1.4或1.5。当X、Y和A满足上述关系时，电化学装置在过充状态下厚度变化较小，即，电化学装置基本不发生变形。
用于本申请所述的负极集流体可以选自铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜、覆有导电金属的聚合物基底和它们的组合。
根据本申请的实施例，所述负极进一步包括粘结剂，所述粘结剂选自以下的至少一种：聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1，1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。
正极
正极包括正极集流体和设置在所述正极集流体上的正极活性材料。正极活性材料的具体种类均不受到具体的限制，可根据需求进行选择。
在一些实施方案中，正极活性材料包括够吸收和释放锂(Li)的正极材料。能够吸 收/释放锂(Li)的正极材料的例子可以包括钴酸锂、镍钴锰酸锂、镍钴铝酸锂、锰酸锂、磷酸锰铁锂、磷酸钒锂、磷酸钒氧锂、磷酸铁锂、钛酸锂和富锂锰基材料。
具体的，钴酸锂的化学式可以如化学式1：
Li xCo aM1 bO 2-c         化学式1
其中M1表示选自镍(Ni)、锰(Mn)、镁(Mg)、铝(Al)、硼(B)、钛(Ti)、钒(V)、铬(Cr)、铁(Fe)、铜(Cu)、锌(Zn)、钼(Mo)、锡(Sn)、钙(Ca)、锶(Sr)、钨(W)、钇(Y)、镧(La)、锆(Zr)和硅(Si)中的至少一种，x、a、b和c值分别在以下范围内：0.8≤x≤1.2、0.8≤a≤1、0≤b≤0.2、-0.1≤c≤0.2。
镍钴锰酸锂或镍钴铝酸锂的化学式可以如化学式2：
Li yNi dM2 eO 2-f       化学式2
其中M2表示选自钴(Co)、锰(Mn)、镁(Mg)、铝(Al)、硼(B)、钛(Ti)、钒(V)、铬(Cr)、铁(Fe)、铜(Cu)、锌(Zn)、钼(Mo)、锡(Sn)、钙(Ca)、锶(Sr)、钨(W)、锆(Zr)和硅(Si)中的至少一种，y、d、e和f值分别在以下范围内：0.8≤y≤1.2、0.3≤d≤0.98、0.02≤e≤0.7、-0.1≤f≤0.2。
锰酸锂的化学式可以如化学式3：
Li zMn 2-gM3 gO 4-h       化学式3
其中M3表示选自钴(Co)、镍(Ni)、镁(Mg)、铝(Al)、硼(B)、钛(Ti)、钒(V)、铬(Cr)、铁(Fe)、铜(Cu)、锌(Zn)、钼(Mo)、锡(Sn)、钙(Ca)、锶(Sr)和钨(W)中的至少一种，z、g和h值分别在以下范围内：0.8≤z≤1.2、0≤g＜1.0和-0.2≤h≤0.2。
在一些实施例中，所述正极活性材料层的重量是所述负极活性材料层的重量的1.5至15倍。在一些实施例中，所述正极活性材料层的重量是所述负极活性材料层的重量的3至10倍。在一些实施例中，所述正极活性材料层的重量是所述负极活性材料层的重量的5至8倍。在一些实施例中，所述正极活性材料层的重量是所述负极活性材料层的重量的1.5倍、2倍、3倍、4倍、5倍、6倍、7倍、8倍、9倍、10倍、11倍、12倍、13倍、14倍或15倍。
在一些实施例中，正极活性材料层可以在表面上具有涂层，或者可以与具有涂层的另一化合物混合。所述涂层可以包括从涂覆元素的氧化物、涂覆元素的氢氧化物、涂覆元素的羟基氧化物、涂覆元素的碳酸氧盐(oxycarbonate)和涂覆元素的羟基碳酸盐(hydroxycarbonate)中选择的至少一种涂覆元素化合物。用于涂层的化合物可以是非晶的 或结晶的。在涂层中含有的涂覆元素可以包括Mg、Al、Co、K、Na、Ca、Si、Ti、V、Sn、Ge、Ga、B、As、Zr、F或它们的混合物。可以通过任何方法来施加涂层，只要所述方法不对正极活性材料的性能产生不利影响即可。例如，所述方法可以包括对本领域普通技术人员来说众所周知的任何涂覆方法，例如喷涂、浸渍等。
在一些实施方案中，正极活性材料层还包含粘合剂，并且可选地还包括正极导电材料。
粘合剂可提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。粘合剂的非限制性示例包括聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1，1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂、尼龙等。
正极活性材料层包括正极导电材料，从而赋予电极导电性。所述正极导电材料可以包括任何导电材料，只要它不引起化学变化。正极导电材料的非限制性示例包括基于碳的材料(例如，天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维等)、基于金属的材料(例如，金属粉、金属纤维等，包括例如铜、镍、铝、银等)、导电聚合物(例如，聚亚苯基衍生物)和它们的混合物。
用于根据本申请的电化学装置的正极集流体可以是铝(Al)，但不限于此。
电解液
可用于本申请实施例的电解液可以为现有技术中已知的电解液。
可用于本申请实施例的电解液中的电解质包括，但不限于：无机锂盐，例如LiClO 4、LiAsF 6、LiPF 6、LiBF 4、LiSbF 6、LiSO 3F、LiN(FSO 2) 2等；含氟有机锂盐，例如LiCF 3SO 3、LiN(FSO 2)(CF 3SO 2)、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2、环状1，3-六氟丙烷二磺酰亚胺锂、环状1，2-四氟乙烷二磺酰亚胺锂、LiN(CF 3SO 2)(C 4F 9SO 2)、LiC(CF 3SO 2) 3、LiPF 4(CF 3) 2、LiPF 4(C 2F 5) 2、LiPF 4(CF 3SO 2) 2、LiPF 4(C 2F 5SO 2) 2、LiBF 2(CF 3) 2、LiBF2(C2F5)2、LiBF 2(CF 3SO 2) 2、LiBF 2(C 2F 5SO 2) 2；含二羧酸配合物锂盐，例如双(草酸根合)硼酸锂、二氟草酸根合硼酸锂、三(草酸根合)磷酸锂、二氟双(草酸根合)磷酸锂、四氟(草酸根合)磷酸锂等。另外，上述电解质可以单独使用一种，也可以同时使用两种或两种以上。在一些实施例中，电解质包括LiPF 6和LiBF 4的组合。在一些实施例中，电解质包括LiPF 6或LiBF 4等无机锂盐与LiCF 3SO 3、LiN(CF 3SO 2) 2、LiN(C 2F 5SO 2) 2等含氟有机锂盐的组合。在一些实施例中，电解质包括LiPF 6。
在一些实施例中，电解质的浓度在0.8-3mol/L的范围内，例如0.8-2.5mol/L的范围内、0.8-2mol/L的范围内、1-2mol/L的范围内、又例如为1mol/L、1.15mol/L、1.2mol/L、1.5mol/L、2mol/L或2.5mol/L。
可用于本申请实施例的电解液中的溶剂包括，但不限于，环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯、环状醚、链状醚、含磷有机溶剂、含硫有机溶剂和芳香族含氟溶剂。
在一些实施例中，环状碳酸酯包括，但不限于，碳酸亚乙酯(ethylene carbonate，EC)、碳酸亚丙酯(propylene carbonate，PC)和碳酸亚丁酯。
在一些实施例中，环状碳酸酯具有3-6个碳原子。
在一些实施例中，链状碳酸酯包括，但不限于：碳酸二甲酯、碳酸甲乙酯、碳酸二乙酯(diethyl carbonate，DEC)、碳酸甲基正丙基酯、碳酸乙基正丙基酯、碳酸二正丙酯等链状碳酸酯，作为被氟取代的链状碳酸酯，例如双(氟甲基)碳酸酯、双(二氟甲基)碳酸酯、双(三氟甲基)碳酸酯、双(2-氟乙基)碳酸酯、双(2，2-二氟乙基)碳酸酯、双(2，2，2-三氟乙基)碳酸酯、2-氟乙基甲基碳酸酯、2，2-二氟乙基甲基碳酸酯和2，2，2-三氟乙基甲基碳酸酯。
在一些实施例中，环状羧酸酯包括，但不限于，γ-丁内酯和γ-戊内酯。在一些实施例中，环状羧酸酯的部分氢原子可被氟取代。
在一些实施例中，链状羧酸酯包括，但不限于：乙酸甲酯、乙酸乙酯、乙酸丙酯、乙酸异丙酯、乙酸丁酯、乙酸仲丁酯、乙酸异丁酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丙酸异丙酯、丁酸甲酯、丁酸乙酯、丁酸丙酯、异丁酸甲酯、异丁酸乙酯、戊酸甲酯、戊酸乙酯、特戊酸甲酯和特戊酸乙酯。在一些实施例中，链状羧酸酯的部分氢原子可被氟取代。在一些实施例中，氟取代的链状羧酸酯包括，但不限于：三氟乙酸甲酯、三氟乙酸乙酯、三氟乙酸丙酯、三氟乙酸丁酯和三氟乙酸2，2，2-三氟乙酯。
在一些实施例中，环状醚包括，但不限于，四氢呋喃、2-甲基四氢呋喃、1，3-二氧戊环、2-甲基1，3-二氧戊环、4-甲基1，3-二氧戊环、1，3-二氧六环、1，4-二氧六环和二甲氧基丙烷。
在一些实施例中，链状醚包括，但不限于，二甲氧基甲烷、1，1-二甲氧基乙烷、1，2-二甲氧基乙烷、二乙氧基甲烷、1，1-二乙氧基乙烷、1，2-二乙氧基乙烷、乙氧基甲氧基甲烷、1，1-乙氧基甲氧基乙烷和1，2-乙氧基甲氧基乙烷。
在一些实施例中，含磷有机溶剂包括，但不限于，磷酸三甲酯、磷酸三乙酯、磷酸 二甲基乙酯、磷酸甲基二乙酯、磷酸亚乙基甲酯、磷酸亚乙基乙酯、磷酸三苯酯、亚磷酸三甲酯、亚磷酸三乙酯、亚磷酸三苯酯、磷酸三(2，2，2-三氟乙基)酯和磷酸三(2，2，3，3，3-五氟丙基)酯。
在一些实施例中，含硫有机溶剂包括，但不限于，环丁砜、2-甲基环丁砜、3-甲基环丁砜、二甲基砜、二乙基砜、乙基甲基砜、甲基丙基砜、二甲基亚砜、甲磺酸甲酯、甲磺酸乙酯、乙磺酸甲酯、乙磺酸乙酯、硫酸二甲酯、硫酸二乙酯和硫酸二丁酯。在一些实施例中，含硫有机溶剂的部分氢原子可被氟取代。
在一些实施例中，芳香族含氟溶剂包括，但不限于，氟苯、二氟苯、三氟苯、四氟苯、五氟苯、六氟苯和三氟甲基苯。
在一些实施例中，本申请的电解液中使用的溶剂包括如上所述的一种或多种。在一些实施例中，本申请的电解液中使用的溶剂包括环状碳酸酯、链状碳酸酯、环状羧酸酯、链状羧酸酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含选自由下列物质组成的群组的有机溶剂：碳酸亚乙酯、碳酸亚丙酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、乙酸正丙酯、乙酸乙酯及其组合。在一些实施例中，本申请的电解液中使用的溶剂包含：碳酸亚乙酯、碳酸亚丙酯、碳酸二乙酯、丙酸乙酯、丙酸丙酯、γ-丁内酯或其组合。
可用于本申请实施例的电解液中的添加剂包括，但不限于，具有2-3个氰基的化合物、含碳碳双键的环状碳酸酯、含硫氧双键的化合物、二氟磷酸锂。
在一些实施例中，具有2-3个氰基的化合物可以包括选自丁二腈(SN)、己二腈(ADN)、乙二醇双(丙腈)醚(EDN)、1，3，5-戊三甲腈、1，2，3-丙三甲腈、1，3，6-己三甲腈(HTCN)、1，2，6-己三甲腈、1，2，3-三(2-氰基乙氧基)丙烷(TCEP)或1，2，4-三(2-氰基乙氧基)丁烷中的至少一种。
在一些实施例中，具有碳-碳双键的环状碳酸酯具体包括，但不限于：碳酸亚乙烯酯、碳酸甲基亚乙烯酯、碳酸乙基亚乙烯酯、乙烯基碳酸乙烯亚乙酯或碳酸-1，2-二甲基亚乙烯酯中的至少一种。
在一些实施例中，含硫氧双键的化合物包括，但不限于：硫酸乙烯酯、1，2-丙二醇硫酸酯、1，3-丙磺酸内酯、1-氟-1，3-丙磺酸内酯、2-氟-1，3-丙磺酸内酯或3-氟-1，3-丙磺酸内酯中的至少一种。
隔离膜
在一些实施方案中，正极与负极之间设有隔离膜以防止短路。可用于本申请的实施 例中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施方案中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如，隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。多孔结构可以提升隔离膜的耐热性能、抗氧化性能和电解质浸润性能，增强隔离膜与极片之间的粘接性。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、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、氢氧化钙和硫酸钡中的一种或几种的组合。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。
聚合物层中包含聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯、聚(偏氟乙烯-六氟丙烯)中的至少一种。
电化学装置
本申请还提供了一种电化学装置，其包括正极、电解液和负极，所述正极包括正极活性材料层和正极集流体，所述负极包括负极活性材料层和负极集流体，所述负极活性材料层包括根据本申请所述的负极活性材料。
本申请的电化学装置包括发生电化学反应的任何装置，它的具体实例包括所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容器。特别地，该电化学装置是锂二次电池，包括锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
电子装置
本申请另提供了一种电子装置，其包括根据本申请的电化学装置。
本申请的电化学装置的用途没有特别限定，其可用于现有技术中已知的任何电子装 置。在一些实施方案中，本申请的电化学装置可用于，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。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
实施例
以下说明根据本申请的锂离子电池的实施例和对比例进行性能评估。
一、锂离子电池的制备
1、负极的制备
将负极活性物质石墨、丁苯橡胶(简写为SBR)和羧甲基纤维素钠(简写为CMC)按照重量比95∶2∶3在去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于预先涂覆有底涂层(如炭黑)的集流体铜箔的两个表面上，底涂层的厚度为1.0μm，烘干后冷压得到负极活性材料层，经裁片、焊接极耳，得到负极。负极活性材料层的重量为0.100mg/mm 2，负极活性材料层厚度为130μm。负极活性材料层重量为以负极集流体任一表面上的负极活性材料层的重量计。
负极活性材料的宽长比和球形度可通过如下方式控制：在负极活性材料的制备过程中，将制备好的石墨通过进料系统进入整形区进行打磨，使颗粒表面具有棱角，从而控制颗粒的宽长比和球形度。随后将打磨后的颗粒通过自分流分级区进行分级，得到所需分布的颗粒。
负极活性材料一次颗粒指的是经过破碎后得到一定颗粒粒度分布的颗粒直接石墨化的样品，负极活性材料二次颗粒指的是经过破碎后和一定比例的沥青混合，通过造粒设备在一定的温度下热处理使得颗粒与颗粒之间通过沥青粘附在一起，然后石墨化得到二次颗粒。负极活性材料中一次颗粒的含量是通过控制一次颗粒和二次颗粒的混合比例获得的。
负极活性材料粉末压实的测试方法为称取1g粉末置于模具中(直径为13mm)，然后将模具置于自动粉压测试设备(三思纵横UTM7305)，通过设备对模具施加一定 的压力最终测得粉末在5t条件下的粉末压实密度。
2、正极的制备
将钴酸锂(LiCoO 2)、乙炔黑和聚偏二氟乙烯(PVDF)按重量比96∶2∶2在适量的N-甲基吡咯烷酮(NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料。将此浆料涂覆于正极集流体铝箔上，烘干、冷压、裁片、分切后，得到正极。
3、电解液的制备
在含水量＜10ppm的氩气气氛手套箱中，将碳酸乙烯酯(简写为EC)、碳酸二乙酯(简写为DEC)和碳酸丙烯酯(简写为PC)按照3∶4∶3的质量比混合均匀，再将充分干燥的锂盐LiPF 6溶解于上述非水溶剂，最后加入3wt％的氟代碳酸乙烯酯、2wt％的1，3-丙烷磺内酯、2wt％的丁二腈，配成电解液。
4、隔离膜的制备
以7μm厚的聚乙烯(PE)多孔聚合物薄膜作为隔离膜。
5、锂离子电池的制备
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极之间起到隔离的作用，然后卷绕得到裸电芯；焊接极耳后将裸电芯置于外包装箔铝塑膜中，将上述制备好的电解液注入到干燥后的裸电芯中，经过真空封装、静置、化成、整形、容量测试等工序，获得软包锂离子电池。
二、测试方法
1、负极活性材料的宽长比分布的测试方法
使用新帕泰克QICPIC动态颗粒图像分析仪测试负极活性材料的宽长比分布。
2、负极活性材料的球形度分布的测试方法
使用新帕泰克QICPIC动态颗粒图像分析仪测试负极活性材料的球形度分布。
3、负极活性材料层与负极集流体之间的粘结力的测试方法
使用Instron(型号为33652)测试仪进行测试负极活性材料层与负极集流体之间的粘结：取15-20mm长的极片，用3M双面胶纸将其固定于钢板上，将胶纸贴在负极活性材料层表面，该胶纸一侧与其等宽的纸带相连接，调整拉力机限位块至合适位置，将纸带向上翻折及滑移40mm，滑移速率为50mm/min，测试180°下(即，反方向拉伸)负极活性材料层与负极集流体之间的粘结力。
4、负极活性材料层的C004/C110的测试方法
按照中华人民共和国机械行业标准JB/T 4220-2011《人造石墨的点阵参数测定方法》 测试负极活性材料层的X射线衍射图谱中的(004)面衍射线图形和(110)面衍射线图形。试验条件如下：X射线采用CuK α辐射，CuK α辐射由滤波片或单色器除去。X射线管的工作电压为(30-35)kV，工作电流为(15-20)mA。计数器的扫描速度为1/4 (°)/min。在记录004衍射线图形时，衍射角2θ的扫描范围为53°-57°。在记录110衍射线图形时，衍射角2θ的扫描范围为75°-79°。由(004)面衍射线图形得到的峰面积记为C004。由(110)面衍射线图形得到的峰面积记为C110。计算负极活性材料层的C004/C110的比值。
5、负极活性材料层的孔隙率的测试方法
将负极活性材料层样品制备成完整圆片。每个实施例或对比例测试30个样品，每个样品体积为约0.35cm 3。根据《GB/T24586-2009铁矿石表观密度真密度和孔隙率的测定》标准进行测试负极活性材料层的孔隙率。
6、负极活性材料层的浸润时间的测试方法
取长50mm、宽50mm的负极活性材料层样品。在干燥条件下，将5mL电解液滴在样品表面，开始计时。待样品表面电解液完全消失，停止计时。计时时间记为负极活性材料层的浸润时间。每个实施例或对比例测试30个样品，取平均值。
7、锂离子液相传递阻抗(R ion)的测试方法
将锂离子电池接入法国比奥罗杰公司生产的Bio-Logic VMP3B电化学工作站进行测试，频率范围为30mHz至50kHz，振幅为5mV。采集数据后采用阻抗复平面图对数据进行分析，得到锂离子液相传递阻抗(R ion)。
8、锂离子电池的2C放电容量保存率的测试方法
将锂离子电池在25℃下静止5分钟后以0.7C的电流恒流充电至电压为4.45V，再以4.45V的恒压充电至0.05C，静置5分钟，然后以0.5C恒流放电至电压为3.0V，静止5分钟。重复上述充放电过程，以0.1C进行放电至电压为3.0V，记录锂离子电池的0.1C放电容量，然后以2C进行放电至电压为3.0V，记录锂离子电池的2C放电容量。通过下式锂离子电池的2C放电容量保存率：
2C放电容量保存率＝2C放电容量/0.1C放电容量×100％。
9、锂离子电池在-20℃下的放电容量保存率的测试方法
将锂离子电池在25℃下静置5分钟。将锂离子电池以0.7C的电流恒流充电至电压为4.45V，再以4.45V的恒压充电至0.05C，静置5分钟。以0.5C的电流恒流放电至电压为3.0V，测试锂离子电池在25℃下的放电容量。调整炉温至-20℃，重复上述充放电过程，测试锂离子电池在-20℃下的放电容量。通过下式计算锂离子电池在-20℃下 的放电容量保存率：
放电容量保持率＝-20℃放电容量/25℃放电容量×100％。
10、锂离子电池的直流电阻(DCR)的测试方法
在25℃下，将锂离子电池以1.5C恒流充电至4.45V，再以4.45V恒压充电至0.05C，静置30分钟。以0.1C放电10秒，记录电压值为U1，以1C放电360秒，记录电压值为U2。重复充放电步骤5次。“1C”是在1小时内将锂离子电池容量完全放完的电流值。
通过下式计算锂离子电池在25℃下的直流电阻R：
R＝(U2-U1)/(1C-0.1C)。
采用基本相同的方法测试锂离子电池在0℃下的直流电阻，区别仅在于操作温度为0℃。
除非有特别说明，本申请所述的DCR指的是锂离子电池在10％荷电状态(SOC)下的直流电阻。
11、锂离子电池的析锂现象的判断方法
将锂离子电池在25℃下静止5分钟。根据实施例或对比例的设置，将锂离子电池以0.7C或2C的电流恒流充电至4.45V，再以4.45V的恒压充电至0.05C，静置5分钟。然后以0.5C的电流恒流放电至3.0V，静止5分钟。重复上述充放电过程10次。将电池满充，在干燥条件下拆解，拍照记录负极的状态。
根据以下标准判断锂离子电池的析锂程度：
当拆解后的负极整体呈现金黄色，极少部分可观察到灰色；且灰色区域的面积＜2％，则判定为不析锂。
当拆解后的负极大部分呈现金黄色，部分位置可观察到灰色；且灰色区域的面积在2％至20％之间，则判定为轻微析锂。
当拆解后的负极整体呈现为灰色，部分位置可观察到金黄色；且灰色区域的面积在20％至60％之间，则判定为析锂。
当拆解后的负极整体呈现灰色且灰色区域的面积＞60％时，则判定为严重析锂。
12、锂离子电池的电荷转移阻抗(Rct)的测试方法
在上述制备锂离子电池的过程中额外接入铜丝作为参比电极，并以20μA的电流在负极镀锂6小时，得到三电极锂离子电池。
将三电极锂离子电池接入法国比奥罗杰公司生产的Bio-Logic VMP3B电化学工作 站进行测试，频率范围为30mHz至50kHz，振幅为5mV。采集数据后采用阻抗复平面图对数据进行分析，得到锂离子电池的电荷转移阻抗(Rct)。
13、负极沿X/Y方向的膨胀率的测试方法
使用电荷耦合元件(CCD)测试冷压后的负极沿X/Y方向的宽度H1。将负极按照锂离子电池的制备步骤制成锂离子电池，将锂离子电池在25℃下静止5分钟后以0.7C的电流恒流充电至4.45V，再以4.45V的恒压充电至0.05C。在干燥条件下拆解锂离子电池，得到拆解后的负极。使用电荷耦合元件(CCD)测试负极沿X/Y方向(如图3所示)的宽度H2。通过下式计算负极沿X/Y方向的膨胀率：
X/Y方向的膨胀率＝(H2-H1)/H1×100％。
14、负极沿Z方向的膨胀率的测试方法
测试经一定压实密度(1.78g/cc)处理的负极的厚度，记为T1。将负极按照锂离子电池的制备步骤制成锂离子电池，将锂离子电池在25℃下静止5分钟后以0.7C的电流恒流充电至3.95V(即，50％SOC)。在干燥条件下拆解锂离子电池，得到拆解后的负极。记录至少14个点的负极厚度，取平均值，记为T2。。通过下式计算负极沿Z方向的膨胀率：
Z方向的膨胀率＝(T2-T1)/T1×100％。
15、锂离子电池的循环膨胀率和循环变形率的测试方法
将锂离子电池在45℃下静止5分钟后以0.7C的电流恒流充电至4.45V，再以4.45V的恒压充电至0.05C，静置5分钟。通过PPG测试方法测试锂离子电池三个位置点的厚度，取平均值记为PPG 0，通过MMC测试方法测试锂离子电池三个位置点的厚度，取平均值记为MMC 0。然后将锂离子电池以0.5C的电流恒流放电至3.0V，静止5分钟。重复上述充放电循环500次，其中在第1-200次充放电循环期间每充放电50次记录电池厚度，第300-500次充放电循环期间每100次记录电池厚度，每次测试锂离子电池三个位置点的厚度，取平均值，记为PPG x和MMC x(x代表循环次数)，将三个测试点测试的MMC厚度的最大值记为Max(MMC x)。MMC x与MMC 0的差值记为电池厚度增长值。
通过下式计算锂离子电池在45℃下的循环膨胀率：
循环膨胀率(45℃)＝MMC x-MMC 0/MMC 0×100％。
通过下式计算锂离子电池在45℃下的循环变形率：
循环变形率(45℃)＝[PPG x/Max(MMC x)-1]×100％。
如上所述的PPG测试方法为：使用PPG软包电池测厚仪(深圳奥拓美自动化科技有限公司制造)，将锂离子电池放置于测厚仪下面板上，在测试过程中上盖板匀速下降，通过压力传感测得锂离子电池的厚度，为PPG厚度。
如上所述的MMC测试方法为：使用千分尺测试仪(日本Mitutoyo制造，型号：MDC-25SX)测量锂离子电池正极极耳处的厚度，每个样品测量三个不同位置，取平均值，记为MMC厚度。
采用基本相同的方法测试锂离子电池在25℃下的循环膨胀率和循环变形率，区别在于操作温度为25℃。
16、锂离子电池在150％SOC下的变形率的测试方法
将锂离子电池在25℃下静止5分钟后以0.5C的电流恒流充电至4.45V，再以4.45V的恒压充电至0.025C(即，100％SOC，也称荷电状态为1)。然后以0.1C的电流恒流充电1小时，静置30分钟。重复0.1C恒流充电过程共5次，其中第1次、第2次、第3次、第4次和第5次充电分别达到110％SOC(即，荷电状态为1.1)、120％SOC(即，荷电状态为1.2)、130％SOC(即，荷电状态为1.3)、140％SOC(即，荷电状态为1.4)和150SOC％(即，荷电状态为1.5)，每次充电时长1小时，每次充电结束后静置30分钟。循环5次后，通过PPG测试方法测试锂离子电池在150％SOC下三个不同位置点的厚度，取平均值记为PPG 5，通过MMC测试方法测试锂离子电池在150％SOC下三个不同位置点的厚度，取最大值记为Max(MMC 5)。通过下式计算锂离子电池在150％SOC下的变形率：
150％SOC变形率＝[PPG x/Max(MMC 5)-1]×100％。
三、测试结果
表1展示了负极活性材料的宽长比分布和球形度分布对锂离子电池的性能的影响。结果表明，当负极活性材料的宽长比分布和球形度分布满足以下条件时：0.4≤AR 10≤0.55、0.48≤S 10≤0.60、0.6≤AR 50≤0.75、0.68≤S 50≤0.82、0.82≤AR 90≤0.90、0.85≤S 90≤0.95，不同形状的负极活性材料颗粒搭配使用，较圆润的负极活性材料之间形成孔隙，细长且存在棱角的负极活性材料颗粒填充在这些孔隙中，使得负极活性材料整体上呈现较圆润但仍有一定棱角的外观形态，从而可显著降低锂离子电池的高温循环膨胀率和直流电阻(DCR)，并且使锂离子电池在循环过程中不会出现析锂现象，即，显著提升锂离子电池的性能。
Figure PCTCN2020084168-appb-000001
表2 展示了负极活性材料层的取向对锂离子电池的性能的影响。
结果表明，随着颗粒宽长比和球形度的减小，负极活性材料层的C004/C110值增加，使得负极活性材料层沿Z方向的膨胀率减小，电池的厚度增加值减小。在负极活性材料的宽长比分布和球形度分布满足以下条件的基础上：0.4≤AR 10≤0.55、0.48≤S 10≤0.60、0.6≤AR 50≤0.75、0.68≤S 50≤0.82、0.82≤AR 90≤0.90、0.85≤S 90≤0.95，当负极活性材料层的C004/C110值在10至20的范围内时，锂离子的嵌入和脱嵌所产生的应力朝向各个方向，沿Z方向和沿X/Y方向的膨胀率达到平衡，由此可显著降低锂离子电池过充变形率、厚度增长值以及循环变形率，即，显著改善了锂离子电池的变形问题。
Figure PCTCN2020084168-appb-000002
表3 展示了负极活性材料的一次颗粒数量占比和压实密度、负极活性材料层的重量和涂层对锂离子电池的性能的影响。除表3中所列参数以外，实施例28-39与实施例10的其它设置相同。
表3
Figure PCTCN2020084168-appb-000003
结果表明，随着负极活性材料中一次颗粒数量占比的增加，负极活性材料的压实密度增加。当负极活性材料中一次颗粒数量占比相同时，降低负极活性材料层的重量可减小负极活性材料层的厚度，使得锂离子经过颗粒与颗粒之间的孔隙进入到集流体附近的电荷转移阻抗(Rct)减小，并且可改善锂离子电池的析锂现象。此外，增加涂层(即，导电层)可增大锂离子的传递速度，降低锂离子电池的电荷转移阻抗(Rct)，由此可改善大倍率嵌锂过程中的析锂现象。
表4 展示了负极活性材料层的孔隙率对锂离子电池的性能的影响。
Figure PCTCN2020084168-appb-000004
结果表明，当负极活性材料层的孔隙率在20％至45％的范围内时，电解液浸润负极活性材料层的时间显著缩短，锂离子的液相传递阻抗(R ion)以及锂离子电池的电荷转移阻抗(Rct)和直流电阻(DCR)均显著降低，由此可显著改善锂离子电池的2C放电速率和析锂现象，从而显著改善锂离子电池的倍率性能。
整个说明书中对“实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施方案中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例”，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (11)

  1. 一种负极活性材料，其中利用动态颗粒图像分析仪测试，当所述负极活性材料的颗粒体积累计分布为10％时，所述负极活性材料的宽长比AR 10满足0.4≤AR 10≤0.55，所述负极活性材料的球形度S 10满足0.48≤S 10≤0.60。
  2. 根据权利要求1所述负极活性材料，当所述负极活性材料的颗粒体积累计分布为50％时，所述负极活性材料满足条件(a)或(b)中的至少一者：
    (a)所述负极活性材料的宽长比AR 50满足0.6≤AR 50≤0.75；
    (b)所述负极活性材料的球形度S 50满足0.68≤S 50≤0.82。
  3. 根据权利要求1所述负极活性材料，当所述负极活性材料的颗粒体积累计分布为90％时，所述负极活性材料满足条件(c)或(d)中的至少一者：
    (c)所述负极活性材料的宽长比AR 90满足0.82≤AR 90≤0.90；
    (d)所述负极活性材料的球形度S 90满足0.85≤S 90≤0.95。
  4. 根据权利要求1所述的负极活性材料，其中所述负极活性材料的压实密度大于1.90g/cm 3。
  5. 根据权利要求1所述的负极活性材料，其中所述负极活性材料包括一次颗粒和二次颗粒，基于所述负极活性材料的总颗粒数量，所述一次颗粒的数量为20％至55％。
  6. 一种电化学装置，其包括正极、负极、隔离膜和电解液，其中所述负极包括负极集流体和负极活性材料层，所述负极活性材料层包含根据权利要求1-5中任一权利要求所述的负极活性材料。
  7. 根据权利要求6所述的电化学装置，其中所述负极满足条件(e)至(g)中的至少一者：
    (e)所述负极活性材料层的重量为0.095mg/mm 2至0.105mg/mm 2；
    (f)由X射线衍射图谱测定得到的所述负极活性材料层的(004)面的峰面积C004和(110)面的峰面积C110的比值C004/C110在10至20的范围内；
    (g)所述负极活性材料层具有20％至45％的孔隙率。
  8. 根据权利要求6所述的电化学装置，其中所述负极集流体与所述负 极活性材料层之间进一步包含涂层，所述涂层的厚度与所述负极活性材料层的厚度的比值在1:50至1:120的范围内。
  9. 根据权利要求6所述的负极，其中所述负极活性材料层与所述负极集流体之间的粘结力大于18N/m。
  10. 根据权利要求6所述的电化学装置，其中所述电化学装置满足以下关系：Y≤0.417X+A，
    其中：
    X为所述电化学装置的荷电状态，1＜X≤1.5，
    当所述电化学装置的荷电状态为1时，所述电化学装置的厚度为Amm，
    当所述电化学装置的荷电状态为X时，所述电化学装置的厚度为Ymm。
  11. 一种电子装置，其包括根据权利要求6至10中任意一项权利要求所述的电化学装置。
PCT/CN2020/084168 2020-04-10 2020-04-10 负极活性材料及使用其的电化学装置和电子装置 WO2021203408A1 (zh)

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