WO2024065600A1 - 负极材料、二次电池和电子装置 - Google Patents

负极材料、二次电池和电子装置 Download PDF

Info

Publication number
WO2024065600A1
WO2024065600A1 PCT/CN2022/123062 CN2022123062W WO2024065600A1 WO 2024065600 A1 WO2024065600 A1 WO 2024065600A1 CN 2022123062 W CN2022123062 W CN 2022123062W WO 2024065600 A1 WO2024065600 A1 WO 2024065600A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative electrode
electrode material
secondary battery
lithium
graphite
Prior art date
Application number
PCT/CN2022/123062
Other languages
English (en)
French (fr)
Inventor
陈宇圣
蔡余新
董佳丽
Original Assignee
宁德新能源科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to CN202280058226.XA priority Critical patent/CN117882216A/zh
Priority to PCT/CN2022/123062 priority patent/WO2024065600A1/zh
Publication of WO2024065600A1 publication Critical patent/WO2024065600A1/zh

Links

Images

Classifications

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

Definitions

  • the present application relates to the field of energy storage, and in particular to a negative electrode material, a secondary battery and an electronic device.
  • the present application provides a negative electrode material and a secondary battery comprising the negative electrode material.
  • the negative electrode material of the present application has high gram capacity and excellent kinetic performance, so that the secondary battery comprising the negative electrode material has both high energy density and fast charging performance.
  • the present application provides a negative electrode material, which includes a carbon-based material, wherein the average surface roughness of the negative electrode material is Ra, 1.2nm ⁇ Ra ⁇ 30nm.
  • the surface carbon atoms of the negative electrode material are consumed by reactions to varying degrees, and a corresponding wrinkled structure will be formed on its surface, which is manifested as a certain roughness on the surface of the negative electrode material.
  • the wrinkled structure on the surface of the negative electrode material of the present application can provide a large number of adsorption sites for lithium ions, thereby increasing the gram capacity of the negative electrode material.
  • the surface wrinkled structure can also promote the diffusion of lithium ions on the basal surface of the negative electrode material, thereby improving the kinetic properties of the negative electrode material.
  • the negative electrode material of the present application can expose more end faces, which is conducive to the rapid embedding of lithium ions and can further improve its kinetic properties.
  • Ra is within the above range, the negative electrode material has a suitable wrinkled structure, which can effectively increase the gram capacity and improve the kinetic properties, thereby obtaining a secondary battery with high energy density and fast charging performance, while not affecting its first effect, storage, cycle and other electrical properties.
  • the ratio of the diffraction peak area C004 of the 004 crystal plane of the negative electrode material to the diffraction peak area C110 of the 110 crystal plane satisfies 2 ⁇ C004/C110 ⁇ 7 through X-ray diffraction testing.
  • the C004 crystal plane of the negative electrode material is parallel to the basal plane direction, and the C110 crystal plane is perpendicular to the basal plane direction.
  • the ratio of C004/C110 can represent the degree of crystal plane orientation of the negative electrode material. The larger the ratio of C004/C110, the larger the proportion of crystal planes parallel to the basal plane in the negative electrode material, the more unfavorable it is for the embedding of lithium ions, and the greater the expansion during the cycle.
  • the pole piece has a higher risk of deformation during the cycle.
  • the negative electrode material has a suitable degree of crystal plane orientation, and the secondary battery can show good dynamics and its energy density will not be significantly reduced. In some embodiments, 2 ⁇ C004/C110 ⁇ 5.
  • the average stacking thickness of the negative electrode material along the c-axis direction is Lc, 20nm ⁇ Lc ⁇ 35nm, as tested by X-ray diffraction. In some embodiments, the average stacking thickness of the negative electrode material along the a-axis direction is La, 95nm ⁇ La ⁇ 150nm, as tested by X-ray diffraction.
  • the Lc and La values of the negative electrode material represent its degree of graphitization. The smaller the Lc and La values, the smaller the gram capacity of the negative electrode material. When the Lc and La values are too high, although the gram capacity of the negative electrode material becomes larger, its cycle performance will decrease.
  • the negative electrode material has a high gram capacity while the cycle performance will not be significantly reduced.
  • the half-peak width of the diffraction peak of the 002 crystal plane of the negative electrode material is Fw, and 0.28° ⁇ Fw ⁇ 0.35° is tested by X-ray diffraction.
  • Fw is within the above range, the negative electrode material has a high gram capacity while the cycle performance is not significantly reduced.
  • the Dv50 of the negative electrode material satisfies: 6nm ⁇ Dv50 ⁇ 15nm. In some embodiments, the Dv99 of the negative electrode material satisfies: 15nm ⁇ Dv99 ⁇ 42nm.
  • the particle sizes Dv50 and Dv99 of the negative electrode material affect the size of its surface roughness. The smaller the particles, the larger the reaction contact area of the negative electrode material, the deeper the reaction degree of the carbon atoms, the higher the surface roughness, but the first effect and cycle capacity retention rate of the negative electrode material are also lower.
  • the Dv50 and Dv99 of the negative electrode material are within the above range, and the secondary battery including the negative electrode material has both high energy density and fast charging performance, while its electrical properties such as first effect, storage, and cycle will not be reduced.
  • the tap density (TD) of the negative electrode material is greater than or equal to 0.80 g/cm 3. Too low a tap density may cause the negative electrode material to have poor slurry dispersibility during the preparation of the secondary battery, making the slurry prone to sedimentation and causing uneven coating thickness, thereby affecting the electrical performance of the secondary battery. In some embodiments, the tap density of the negative electrode material is 0.80 g/cm 3 to 1.5 g/cm 3 .
  • the carbon-based material includes artificial graphite and/or natural graphite.
  • the method for preparing the negative electrode material comprises: heating the pretreated graphite material with (NH 4 ) 2 S 2 O 8 under liquid phase conditions, wherein the added (NH 4 ) 2 S 2 O 8 accounts for 1% to 6% by weight.
  • the heating reaction of the carbonaceous material and (NH 4 ) 2 S 2 O 8 lasts for 6 to 12 hours.
  • the reaction temperature of the carbonaceous material and (NH 4 ) 2 S 2 O 8 during the heating reaction is 80°C to 150°C.
  • the present application provides a secondary battery, which includes a negative electrode, the negative electrode includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes the negative electrode material described in the first aspect.
  • the mass content of the negative electrode material is w, wherein 70% ⁇ w ⁇ 100%. In some embodiments, 80% ⁇ w ⁇ 100%.
  • Negative electrode materials with Ra ranging from 1.2nm to 30nm can significantly improve their gram capacity and kinetic performance, so their proportion in the negative electrode active material is above 70%, which can effectively improve the energy density and fast charging performance of the secondary battery.
  • the expansion rate of the negative electrode is less than or equal to 30%. After the negative electrode material is processed, more crystal planes are exposed, so that the particles in the negative electrode sheet expand in multiple directions.
  • the Ra of the negative electrode material in the range of 1.2nm to 30nm can alleviate the expansion rate of the sheet to a certain extent.
  • the compaction density of the negative electrode is greater than or equal to 1.48 g/cm 3 . In some embodiments, the sheet resistivity of the negative electrode is less than or equal to 0.50 ⁇ /cm.
  • the present application provides an electronic device comprising the secondary battery of the second aspect.
  • FIG1 is a SEM image of the negative electrode material of Example 21 of the present application.
  • FIG. 2 is a SEM image of the negative electrode material of Comparative Example 1 of the present application.
  • FIG3 shows the charge and discharge curves of the lithium-ion batteries of Example 19 and Comparative Example 1 of the present application.
  • FIG. 4 shows the irreversible lithium loss of the lithium ion batteries of Example 1 and Comparative Example 1 of the present application.
  • FIG5 shows the DCR curves of the lithium-ion batteries of Example 32 of the present application and Comparative Example 1.
  • any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, and any upper limit can be combined with any other upper limit to form an undefined range.
  • each separately disclosed point or single value itself can be combined as a lower limit or upper limit with any other point or single value or with other lower limits or upper limits to form an undefined range.
  • a list of items connected by the terms “at least one of,” “at least one of,” “at least one of,” or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase “at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may contain a single component or multiple components.
  • Item B may contain a single component or multiple components.
  • Item C may contain a single component or multiple components.
  • the negative electrode material provided in the present application includes a carbon-based material, wherein the average surface roughness of the negative electrode material is Ra, 1.2nm ⁇ Ra ⁇ 30nm.
  • the surface carbon atoms of the negative electrode material are consumed by reactions to varying degrees, and a corresponding wrinkled structure will be formed on its surface, which is manifested as a certain roughness on the surface of the negative electrode material.
  • the wrinkled structure on the surface of the negative electrode material of the present application can provide a large number of adsorption sites for lithium ions, thereby increasing the gram capacity of the negative electrode material.
  • the surface wrinkled structure can also promote the diffusion of lithium ions on the basal surface of the negative electrode material, thereby improving the kinetic properties of the negative electrode material.
  • the negative electrode material of the present application can expose more end faces, which is conducive to the rapid embedding of lithium ions and can further improve its kinetic properties.
  • Ra is within the above range, the negative electrode material has a suitable wrinkled structure, which can effectively increase the gram capacity and improve the kinetic properties, thereby obtaining a secondary battery with high energy density and fast charging performance, while not affecting its first effect, storage, cycle and other electrical properties.
  • Ra is 1.5 nm, 2 nm, 3 nm, 4 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, 10 nm, 10.5 nm, 11 nm, 11.5 nm, 12 nm, 12.5 nm, 13 nm, 13.5 nm, 14 nm, 14.5 nm, 15 nm, 15.5 nm, 16 nm, 16.5 nm, 17 nm, 17.5 nm, 18 nm, 18.5 nm, 19 nm, 19.5 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, or a range consisting of any two of these values. In some embodiments,
  • the ratio of the diffraction peak area C004 of the 004 crystal plane of the negative electrode material to the diffraction peak area C110 of the 110 crystal plane satisfies 2 ⁇ C004/C110 ⁇ 7 through X-ray diffraction testing.
  • the C004 crystal plane of the negative electrode material is parallel to the basal plane direction, and the C110 crystal plane is perpendicular to the basal plane direction.
  • the ratio of C004/C110 can represent the degree of crystal plane orientation of the negative electrode material. The larger the ratio of C004/C110, the larger the proportion of crystal planes parallel to the basal plane in the negative electrode material, the more unfavorable it is for the embedding of lithium ions, and the greater the expansion during the cycle.
  • C004/C110 is 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, or a range consisting of any two of these values. In some embodiments, 2 ⁇ C004/C110 ⁇ 5.
  • the average stacking thickness of the negative electrode material along the c-axis direction is Lc, 20nm ⁇ Lc ⁇ 35nm, as tested by X-ray diffraction.
  • Lc is 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm, 30nm, 31nm, 32nm, 33nm, 34nm, or a range consisting of any two of these values.
  • the average stacking thickness of the negative electrode material along the a-axis direction is La, 95nm ⁇ La ⁇ 150nm, as tested by X-ray diffraction.
  • La is 100nm, 103nm, 105nm, 107nm, 110nm, 113nm, 115nm, 117nm, 120nm, 123nm, 125nm, 127nm, 130nm, 143nm, 145nm, 147nm, or a range consisting of any two of these values.
  • the Lc and La values of the negative electrode material represent the degree of graphitization thereof. The smaller the Lc and La values are, the smaller the gram capacity of the negative electrode material is. When the Lc and La values are too high, although the gram capacity of the negative electrode material becomes larger, its cycle performance will decrease.
  • the negative electrode material has a high gram capacity while the cycle performance is not significantly reduced.
  • the half-peak width of the diffraction peak of the 002 crystal plane of the negative electrode material is Fw, 0.28° ⁇ Fw ⁇ 0.35°, as tested by X-ray diffraction.
  • Fw is 0.285°, 0.29°, 0.295°, 0.3°, 0.305°, 0.31°, 0.315°, 0.325°, 0.33°, 0.335°, 0.34°, 0.345°, or a range consisting of any two of these values.
  • the smaller the Fw the larger the grain size of the negative electrode material, the higher the corresponding gram capacity, but the worse the cycle expansion.
  • the larger the Fw the smaller the grain size of the negative electrode material, and the lower its gram capacity.
  • Fw is within the above range, the negative electrode material has a high gram capacity while the cycle performance is not significantly reduced.
  • the Dv50 of the negative electrode material satisfies: 6nm ⁇ Dv50 ⁇ 15nm. In some embodiments, Dv50 is 6.5nm, 7nm, 7.5nm, 8nm, 8.5nm, 9nm, 9.5nm, 10nm, 10.5nm, 11nm, 11.5nm, 12nm, 12.5nm, 13nm, 13.5nm, 14nm, 14.5nm, or a range consisting of any two of these values.
  • the Dv99 of the negative electrode material satisfies: 15nm ⁇ Dv99 ⁇ 42nm.
  • Dv99 is 20nm, 22nm, 24nm, 26nm, 28nm, 30nm, 32nm, 34nm, 36nm, 38nm, 40nm, or a range consisting of any two of these values.
  • the particle sizes Dv50 and Dv99 of the negative electrode material affect the size of its surface roughness. The smaller the particles, the larger the reaction contact area of the negative electrode material, the deeper the reaction degree of carbon atoms, and the higher the surface roughness, but the first effect and cycle capacity retention rate of the negative electrode material are also lower.
  • the Dv50 and Dv99 of the negative electrode material are within the above range, and the secondary battery including the negative electrode material has both high energy density and fast charging performance, while its electrical properties such as first effect, storage, and cycle will not be reduced.
  • Dv50 means that in the volume-based particle size distribution of the negative electrode material, 50% of the particles have a particle size less than this value.
  • Dv99 means that in the volume-based particle size distribution of the negative electrode material, 99% of the particles have a particle size less than this value.
  • the tap density of the negative electrode material is greater than or equal to 0.80 g/cm 3. Too low a tap density may cause the negative electrode material to have poor dispersibility in the slurry during the preparation of the secondary battery, making the slurry prone to sedimentation, resulting in uneven coating thickness, thereby affecting the electrical performance of the secondary battery.
  • the tap density of the negative electrode material is 0.90 g/cm 3 , 1.0 g/cm 3 , 1.1 g/cm 3 , 1.2 g/cm 3 , 1.3 g/cm 3 , 1.4 g/cm 3 , or a range consisting of any two of these values.
  • the carbon-based material includes a graphite material
  • the graphite material includes artificial graphite and/or natural graphite.
  • the preparation method of the negative electrode material comprises: heating the graphite material after surface pretreatment with (NH 4 ) 2 S 2 O 8 under liquid phase conditions, wherein the added (NH 4 ) 2 S 2 O 8 accounts for 1% to 6% by mass.
  • the mass proportion of (NH 4 ) 2 S 2 O 8 is 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6% or a range consisting of any two of these values.
  • the mass proportion of (NH 4 ) 2 S 2 O 8 is the mass ratio of (NH 4 ) 2 S 2 O 8 to the pretreated graphite material.
  • the liquid phase conditions can be provided by water, an alcohol solution or an organic solvent.
  • the reaction time of the surface pretreated graphite material and (NH 4 ) 2 S 2 O 8 for heating reaction is 6 to 12 hours. In some embodiments, the reaction time of the heating reaction is 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours or a range consisting of any two of these values.
  • the reaction temperature of the heating reaction of the surface pretreated graphite material and (NH 4 ) 2 S 2 O 8 is 80° C. to 150° C. In some embodiments, the reaction temperature of the heating reaction is 80° C., 90° C., 100° C., 110° C., 120° C., 130° C., 140° C., 150° C., or a range consisting of any two of these values.
  • the surface pretreatment method is to carbonize the graphite material under inert atmosphere conditions at 900°C-1200°C, such as 1000°C, after the surface is coated, for example, carbonize for 4 hours, and then perform surface etching reaction.
  • the coating agent used is at least one of asphalt, tar, and resinous organic matter, and the mass ratio of the coating agent to the graphite material is (1-5): (99-95).
  • the etching reaction mode includes one of high-temperature gas phase reaction, liquid phase heating reaction, and high-temperature solid phase reaction, wherein the gas source used in the high-temperature gas phase reaction includes one of oxygen-containing atmosphere, carbon dioxide, nitrogen dioxide, and methane, the reactant used in the liquid phase heating reaction includes one of H2O2 , concentrated sulfuric acid, and nitric acid, and the reactant used in the high-temperature solid phase reaction includes one of potassium permanganate, ammonium bicarbonate, and sodium bicarbonate.
  • the secondary battery provided in the present application includes a negative electrode, the negative electrode includes a negative electrode active material layer, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material includes the negative electrode material described in the first aspect.
  • the mass content of the negative electrode material is w, wherein 70% ⁇ w ⁇ 100%.
  • w is 70%, 75%, 80%, 85%, 90%, 95% or a range consisting of any two of these values.
  • Negative electrode materials with Ra sizes ranging from 1.2nm to 30nm can significantly improve their gram capacity and kinetic performance, so their proportion in the negative electrode active material is above 70%, which can effectively improve the energy density and fast charging performance of the secondary battery.
  • the expansion rate of the negative electrode is less than or equal to 30%.
  • the expansion rate of the negative electrode 100% ⁇ (T2-T1) / T1, where T1 is the thickness of the negative electrode when the secondary battery is 0% charged, and T2 is the thickness of the negative electrode when the secondary battery is 100% charged.
  • T1 is the thickness of the negative electrode when the secondary battery is 0% charged
  • T2 is the thickness of the negative electrode when the secondary battery is 100% charged.
  • the compaction density of the negative electrode is greater than or equal to 1.48 g/cm 3 .
  • the compaction density of the negative electrode is the compaction density of the negative electrode when the secondary battery is 50% charged.
  • the film resistivity of the negative electrode is less than or equal to 0.50 ⁇ /cm.
  • the negative electrode further includes a negative electrode current collector
  • the negative electrode current collector includes: copper foil, aluminum foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or any combination thereof.
  • the negative electrode active material layer further comprises a binder and a conductive agent.
  • the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon, etc.
  • the conductive agent includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver.
  • the conductive polymer is a polyphenylene derivative.
  • the secondary battery of the present application further includes a positive electrode, the positive electrode includes a positive electrode current collector and a positive electrode active material layer, and the positive electrode active material layer includes a positive electrode active material, a binder and a conductive agent.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer substrate.
  • the positive electrode active material includes at least one of lithium cobaltate, lithium nickel manganese cobaltate, lithium nickel manganese aluminum, lithium iron phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium manganese phosphate, lithium manganese iron phosphate, lithium iron silicate, lithium vanadium silicate, lithium cobalt silicate, lithium manganese silicate, spinel lithium manganese oxide, spinel nickel manganese oxide and lithium titanate.
  • the binder includes a binder polymer, such as polyvinylidene fluoride, polytetrafluoroethylene, polyolefins, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, modified polyvinylidene fluoride, modified SBR rubber or polyurethane.
  • the polyolefin binder includes at least one of polyethylene, polypropylene, polyolefin ester, polyolefin alcohol or polyacrylic acid.
  • the conductive agent includes a carbon-based material, such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black or carbon fiber; a metal-based material, such as metal powder or metal fiber of copper, nickel, aluminum, silver, etc.; a conductive polymer, such as a polyphenylene derivative; or a mixture thereof.
  • a carbon-based material such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black or carbon fiber
  • a metal-based material such as metal powder or metal fiber of copper, nickel, aluminum, silver, etc.
  • a conductive polymer such as a polyphenylene derivative
  • the secondary battery of the present application also includes a separator.
  • the material and shape of the separator used in the secondary battery of the present application are not particularly limited, and it can be any technology disclosed in the prior art.
  • the separator includes a polymer or inorganic substance formed of a material that is stable to the electrolyte of the present application.
  • the isolation film may include a substrate layer and a surface treatment layer.
  • the substrate layer is a non-woven fabric, a film or a composite film having a porous structure
  • 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 may be selected.
  • a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder, and the inorganic particles are selected from at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate.
  • the binder is selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride-hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyethylene alkoxy, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer is selected from at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyethylene alkoxy, polyvinylidene fluoride and poly (vinylidene fluoride-hexafluoropropylene).
  • the secondary battery of the present application further comprises an electrolyte.
  • the electrolyte that can be used in the present application can be an electrolyte known in the prior art.
  • the electrolyte includes an organic solvent, a lithium salt and an optional additive.
  • the organic solvent in the electrolyte of the present application may be any organic solvent known in the prior art that can be used as a solvent for the electrolyte.
  • the electrolyte used in the electrolyte according to the present application is not limited, and it can be any electrolyte known in the prior art.
  • the additive of the electrolyte according to the present application may be any additive known in the prior art that can be used as an electrolyte additive.
  • the organic solvent includes, but is not limited to: ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
  • the organic solvent includes an ether solvent, for example, including at least one of 1,3-dioxolane (DOL) and ethylene glycol dimethyl ether (DME).
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salt includes, but is not limited to, lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), lithium bis(trifluoromethanesulfonyl)imide LiN(CF 3 SO 2 ) 2 (LiTFSI), lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), lithium bis(oxalatoborate) LiB(C 2 O 4 ) 2 (LiBOB), or lithium di(oxalatoborate) LiBF 2 (C 2 O 4 )(LiDFOB).
  • the additive includes at least one of fluoroethylene carbonate and adiponitrile.
  • the secondary battery of the present application includes, but is not limited to: a lithium ion battery or a sodium ion battery. In some embodiments, the secondary battery includes a lithium ion battery.
  • the present application further provides an electronic device, which includes the secondary battery according to the second aspect of the present application.
  • the electronic device or device of the present application is not particularly limited.
  • the electronic device of the present application includes, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large household battery and a lithium-ion capacitor, etc.
  • the graphite materials used in this case include artificial graphite and/or natural graphite, wherein artificial graphite is obtained by high-temperature graphitization of carbonaceous raw materials such as needle coke, petroleum coke, asphalt coke, biomass, etc., and natural graphite is obtained by spheroidization of natural flake graphite.
  • a certain mass of the graphite material is weighed, and surface pretreatment is first performed, wherein the graphite material is coated on the surface and then carbonized under an inert atmosphere at 1000°C for 4 hours, wherein the coating agent used is at least one of asphalt, tar, and resinous organic matter, and the mass ratio of the coating agent to the graphite material is (1-5):(99-95); then a surface etching reaction is performed, wherein the reaction mode includes one of a high-temperature gas phase reaction, a liquid phase heating reaction, and a high-temperature solid phase reaction, wherein the gas source used in the high-temperature gas phase reaction includes one of an oxygen-containing atmosphere, carbon dioxide , nitrogen dioxide, and methane; the reactant used in the liquid phase heating reaction includes one of H2O2 , ( NH4 ) 2S2O8 , concentrated sulfuric acid, and nitric acid; and the reactant used in the high-temperature solid phase reaction includes one of potassium permanganate, ammonium bicarbonate,
  • Example 1 The preparation method of Example 1 is as follows: 3 kg of artificial graphite material is weighed, asphalt is used as a coating agent and mixed evenly with the artificial graphite (the mass ratio of asphalt to artificial graphite is 3:97), and then carbonized at 1000°C in a nitrogen atmosphere for 4 hours to obtain a surface pretreated product; the surface pretreated product is made into a slurry with a solid content of 10%, ( NH4 ) 2S2O8 with a mass ratio (accounting for the mass ratio of the surface pretreated product) of 1% is added, and then reacted at 80°C for 6 hours , and finally filtered, washed and dried to obtain a carbon-based material, i.e., a negative electrode active material.
  • a carbon-based material i.e., a negative electrode active material.
  • the above-mentioned negative electrode material, binder styrene butadiene rubber (abbreviated as SBR), and thickener sodium carboxymethyl cellulose (abbreviated as CMC) are mixed in a weight ratio of 97:1.5:1.5, and then fully stirred and mixed in an appropriate amount of deionized water solvent to form a uniform negative electrode slurry; the slurry is coated on a current collector Cu foil with a conductive coating thickness of 1 ⁇ m, dried, and cold pressed to obtain a negative electrode sheet.
  • SBR binder styrene butadiene rubber
  • CMC thickener sodium carboxymethyl cellulose
  • Lithium cobalt oxide (chemical formula: LiCoO 2 ) is selected as the positive electrode active material, and is fully stirred and mixed with a conductive agent, acetylene black, and a binder, polyvinylidene fluoride (abbreviated as PVDF), in a proper amount of N-methylpyrrolidone (abbreviated as NMP) solvent at a weight ratio of 96.3:2.2:1.5 to form a uniform positive electrode slurry; the slurry is coated on a current collector Al foil, dried, and cold pressed to obtain a positive electrode sheet.
  • PVDF polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the mass percentage of LiPF 6 was 12.5%
  • the mass percentage of fluoroethylene carbonate was 2%
  • the mass percentage of 1,3-propane sultone was 2%
  • the mass percentage of each substance was calculated based on the mass of the electrolyte.
  • a polyethylene (PE) porous polymer film with a thickness of 7 ⁇ m and a porosity of 35% was used as the isolation membrane.
  • the positive electrode, the separator, and the negative electrode are stacked in order, so that the separator is placed between the positive electrode and the negative electrode to play an isolating role, and then they are wound to obtain an electrode assembly; after welding the pole ears, the electrode assembly is placed in an outer packaging foil aluminum-plastic film, and the prepared electrolyte is injected into the dried electrode assembly. After vacuum packaging, standing, formation, shaping, capacity testing and other processes, a soft-pack lithium-ion battery is obtained.
  • the preparation process of the negative electrode material is similar to that of Example 1, except that the corresponding negative electrode material is prepared by adjusting the mass ratio of the added (NH 4 ) 2 S 2 O 8.
  • the specific preparation parameters are shown in Table a:
  • the preparation process of the negative electrode material is similar to that of Example 8, except that the C004/C110 value of the negative electrode material is adjusted by adjusting the reaction time.
  • the specific preparation parameters are shown in Table b:
  • the preparation process of the negative electrode material is similar to that of Example 21, except that the C004/C110 value of the negative electrode material is adjusted by adjusting the reaction temperature.
  • the specific preparation parameters are shown in Table C:
  • the preparation of the negative electrode, button cell and lithium-ion battery is the same as that in Example 21.
  • the preparation process of the negative electrode material is the same as that of Example 27.
  • the preparation process of the negative electrode is similar to that of Example 27, except that graphite negative electrode material and conventional artificial graphite are used as negative electrode active materials, wherein the mass ratio of graphite negative electrode material to negative electrode active material is 95%, 90%, 85%, 80%, 75% and 70% respectively.
  • This application uses a Malvern particle size tester to measure the particle size of the negative electrode material: the negative electrode material is dispersed in a dispersant (ethanol), and after 30 minutes of ultrasound, the sample is added to the Malvern particle size tester to start the test.
  • the particle size that reaches 50% of the volume accumulation from the small particle size side is the Dv50 of the negative electrode material; at the same time, in the volume-based particle size distribution of the negative electrode material, the particle size that reaches 99% of the volume accumulation from the small particle size side is the Dv99 of the negative electrode material.
  • the (004) plane diffraction line pattern and (110) plane diffraction line pattern of the negative electrode material were tested.
  • the test conditions are as follows: X-rays are CuK ⁇ radiation, 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 recorded as C004.
  • the peak area obtained from the (110) plane diffraction line pattern is recorded as C110.
  • the negative electrode active material graphite was tested by X-ray powder diffractometer, and the target material was CuK ⁇ ; the voltage and current were 40KV/40mA, the scanning angle range was 5° to 80°, the scanning step length was 0.00836°, and the time for each step was 0.3s. According to the obtained X-ray diffraction spectrum, the full width at 50% between the lowest and highest points of the peak intensity of the 002 peak was recorded as Fw.
  • ⁇ is the half-width of the diffraction peak of the 100 crystal plane
  • ⁇ is the wavelength (0.154056
  • ⁇ is the position angle of the maximum peak intensity of the diffraction peak of the 100 crystal plane.
  • Lc is the average stacking thickness of graphite crystallites along the c-axis direction
  • Lc K ⁇ / ⁇ (2 ⁇ )/cos ⁇ .
  • ⁇ is the half-width of the 002 peak
  • ⁇ is the wavelength (0.154056)
  • ⁇ is the position angle of the maximum peak intensity of the 002 peak.
  • the tap density is the mass per unit volume of the powder in a container measured after being tapped under specified conditions, and is expressed in g/cm 3 .
  • the test method is to fix a graduated cylinder containing a certain mass of powder on a mechanical vibration device.
  • the vibration motor drives the mechanical vibration device to vibrate vertically up and down.
  • the graduated cylinder containing powder vibrates rhythmically with the mechanical vibration device.
  • the mechanical vibration device stops vibrating and the volume of the graduated cylinder is read.
  • density mass divided by volume, the density of the powder after compaction can be calculated.
  • the button cell was placed on a blue battery tester for testing.
  • the test process was to discharge to 5mv at 0.05C, let stand for 5 minutes, discharge to 5mv at 0.05mA, discharge to 5mv at 0.01mA, and charge to 2.0V at 0.1C to get the charging capacity. Finally, divide it by the weight of the active substance to get the gram capacity of the negative electrode material. The charging capacity divided by the discharge capacity can get the first efficiency.
  • the fast charging performance test of the button battery is carried out, and the test process is as follows:
  • test temperature is set at 25°C;
  • Steps 5)-8) are repeated 10 times;
  • the capacity of the last discharge cycle is recorded as D10
  • the capacity of the first charge cycle is recorded as C1
  • test temperature is 25°C;
  • step 15 If the voltage is ⁇ 2.5V, jump to step 15;
  • Table 1 shows the effect of the average surface roughness Ra of the negative electrode material on the performance of lithium-ion batteries.
  • Table 2 further studies the effects of the ratio of the diffraction peak area of the 004 crystal plane to the diffraction peak area of the 110 crystal plane of the negative electrode material (C004/C110), the average stacking thickness of the negative electrode material along the c-axis (Lc), the average stacking thickness of the negative electrode material along the a-axis (La), and the half-width of the diffraction peak of the 002 crystal plane on the performance of lithium-ion batteries on the basis of Example 8.
  • C004/C110 indicates the degree of orientation of the crystal plane of the negative electrode material.
  • Lc is limited to 23.0nm ⁇ Lc ⁇ 32.0nm
  • La is 98.0nm ⁇ La ⁇ 145nm
  • Fw 0.280° ⁇ Fw ⁇ 0.320°
  • the negative electrode material has a higher gram capacity.
  • Table 3 further studies the influence of the Dv50 and Dv99 of the negative electrode material on the performance of lithium-ion batteries based on Example 21.
  • Example 21 Example 24 to Example 26 in Table 3 that with the decrease of Dv50 and Dv99, the first effect of the negative electrode material shows a decreasing trend. It is speculated that the reaction contact area of the negative electrode material increases, the degree of carbon atom reaction deepens, and the surface roughness increases, which leads to the intensification of the side reaction between the electrolyte and the electrolyte, and then the first effect is reduced. It can be seen from Example 21, Example 27 to Example 30 that with the increase of Dv50 and Dv99, the average surface roughness Ra of the negative electrode material gradually decreases, and the gram capacity level shows a downward trend.
  • the negative electrode material is more difficult to react during processing, the surface roughness is smaller, and the adsorption sites of lithium ions are reduced, which leads to a weakening of the improvement effect on gram capacity.
  • too large particles may also cause the processing performance of the negative electrode slurry to deteriorate, and particle scratches will be generated in the thinner pole piece coating process, resulting in reduced performance.
  • the tap density (TD) reacts to the difficulty of the material in the slurry processing process. As the degree of reaction increases, the surface groups of the material increase, and it is easy to disperse evenly in the slurry. In summary, it is more appropriate to limit the range of Dv50 to 8nm to 13nm, the range of Dv99 to 20nm to 35nm, and TD ⁇ 0.80g/ cm3 .
  • Table 4 further studies the effect of the mass proportion w of the above-mentioned graphite negative electrode material in the negative electrode active material on the performance of the lithium-ion battery on the basis of Example 27.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Secondary Cells (AREA)

Abstract

提供一种负极材料，其包括碳基材料，其中，负极材料的表面平均粗糙度为Ra，1.2nm≤Ra≤30nm。本申请的负极材料具有高的克容量和优异的动力学性能，进而使得包含该负极材料的二次电池兼具高的能量密度和快充性能。还提供包括该负极材料的二次电池。

Description

负极材料、二次电池和电子装置 技术领域
本申请涉及储能领域，具体涉及一种负极材料、二次电池和电子装置。
背景技术
随着消费类电子产品的不断更新迭代，其对锂离子电池的性能要求也越来越高，其中锂离子电池的能量密度和快充电能力通常是影响产品体验感的关键指标。人造石墨作为锂离子电池使用的主要负极材料，可以通过提升其克容量和动力学性能来改善锂离子电池的能量密度和快充性能。
常规人造石墨往往通过提高前驱体的石墨化程度来提升克容量，但此方式提升克容量的程度有限，且此方式下的石墨内部和表面都具有非常规整的晶体结构，不利于锂离子的快速扩散，进而会加大锂离子的扩散难度从而恶化动力学性能。因此，开发新的技术手段能较大程度的提高石墨克容量和动力学性能有着重要意义。
发明内容
鉴于现有技术存在的上述问题，本申请提供了一种负极材料及包括该负极材料的二次电池。本申请的负极材料具有高的克容量和优异的动力学性能，进而使得包含该负极材料的二次电池兼具高的能量密度和快充性能。
在第一方面，本申请提供一种负极材料，其包括碳基材料，其中，负极材料的表面平均粗糙度为Ra，1.2nm≤Ra≤30nm。负极材料的表层碳原子被不同程度的反应消耗，其表面就会形成相应的褶皱结构，表现为负极材料表面具有一定的粗糙度。本申请的负极材料表面的褶皱结构可以为锂离子提供大量的吸附位点，从而提升负极材料的克容量。同时表面褶皱结构还能够促进锂离子在负极材料基面的扩散，从而改善负极材料的动力学性能。此外，本申请的负极材料可以暴露更多的端面，有利于锂离子的快速嵌入，能够进一步改善其动力学性能。Ra在上述范围内，负极材料具有合适的褶皱结构，可有效提升克容量和改善动力学性能，从而获得高能量密度兼顾快充性能的二次电池，同时不影响其首效、存储、循环等电性能。在一些实施方式中，5nm≤Ra≤25nm。
在一些实施方式中，通过X射线衍射法测试，负极材料的004晶面衍射峰面积C004与110晶面衍射峰面积C110的比值满足2≤C004/C110≤7。负极材料的C004晶面与基面方向平行，C110晶面与基面方向垂直，C004/C110的比值大小可代表负极材料的晶面取向程度。C004/C110的比值越大，负极材料中与基面平行的晶面占比越大，越不利于锂离子的嵌入，并且循环过程中的膨胀越大。C004/C110的比值过小，极片在循环过程中则有较高的变形风险。C004/C110在上述范围内，负极材料具有合适的晶面取向程度，二次电池既能表现出良好的动力学，其能量密度也不会明显降低。在一些实施方式中，2≤C004/C110≤5。
在一些实施方式中，通过X射线衍射法测试，负极材料沿c轴方向的平均堆积厚度为Lc，20nm≤Lc≤35nm。在一些实施方式中，通过X射线衍射法测试，负极材料沿a轴方向的平均堆积厚度为La，95nm≤La≤150nm。负极材料的Lc和La值代表其石墨化程度，Lc和La值越小，负极材料的克容量越小。Lc和La值过高时，虽然负极材料的克容量变大，但其循环性能会降低。Lc和La值在上述范围内，负极材料具有高克容量的同时循环性能不会明显降低。在一些实施方式中，23nm≤Lc≤32nm。在一些实施方式中98nm≤La≤145nm。
在一些实施方式中，通过X射线衍射法测试，负极材料002晶面衍射峰的半峰宽为Fw，0.28°≤Fw≤0.35°。Fw越小，负极材料的晶粒尺寸越大，相应的克容量较高，但循环膨胀越差。Fw越大，负极材料的晶粒尺寸越小，其克容量较低。Fw在上述范围内，负极材料具有高克容量的同时循环性能不会明显降低。在一些实施方式中，0.28°≤Fw≤0.32°。
在一些实施方式中，负极材料的Dv50满足：6nm≤Dv50≤15nm。在一些实施方式中，负极材料的Dv99满足：15nm≤Dv99≤42nm。负极材料的颗粒尺寸Dv50和Dv99影响其表面粗糙度的大小。颗粒越小，负极材料的反应接触面积越大，碳原子反应程度越深，表面粗糙度越高，但负极材料的首效和循环容量保持率也更低。颗粒越大，负极材料在处理时反应更困难，表面粗糙度更小，对其克容量和动力学无明显改善效果，且颗粒太大也使其浆料加工性能变差。负极材料的Dv50和Dv99在上述范围内，包括该负极材料的二次电池兼具高能量密度和快充性能，同时其首效、存储、循环等电性能不会降低。在一些实施方式中，8nm≤Dv50≤13nm。在一些实施方式中，20nm≤Dv99≤35nm。
在一些实施方式中，负极材料的振实密度(TD)大于或等于0.80g/cm 3。振实密度过低会导致负极材料在二次电池制备过程中浆料分散性变差，使得浆料易发生沉降，造成涂 布厚度不均匀，从而影响二次电池的电性能。在一些实施方式中，负极材料的振实密度为0.80g/cm 3至1.5g/cm 3。
在一些实施方式中，所述碳基材料包括人造石墨和/或天然石墨。
在一些实施方式中，负极材料的制备方法包括：将预处理后的石墨材料在液相条件下与(NH 4) 2S 2O 8进行加热反应，其中，所加入的(NH 4) 2S 2O 8质量占比为1％至6％。
在一些实施方式中，碳质材料与(NH 4) 2S 2O 8进行加热反应的反应时间为6至12h。
在一些实施方式中，碳质材料与(NH 4) 2S 2O 8进行加热反应的反应温度为80℃至150℃。
在第二方面，本申请提供了一种二次电池，其包括负极，负极包括负极活性材料层，负极活性材料层包括负极活性材料，负极活性材料包括第一方面所述的负极材料。
在一些实施方式中，基于负极活性材料的质量，负极材料的质量含量为w，其中，70％≤w≤100％。在一些实施方式中，80％≤w≤100％。负极材料Ra大小介于1.2nm至30nm范围内的可显著其提升克容量以及动力学性能，因此其在负极活性材料中的比例在70％以上就可以有效改善二次电池的能量密度和快充性能。
在一些实施方式中，负极的膨胀率小于或等于30％。负极材料在处理后暴露了更多晶面，使负极极片中颗粒的膨胀呈多个方向，负极材料的Ra在1.2nm至30nm范围内可一定程度上缓解极片的膨胀率。
在一些实施方式中，负极的压实密度大于或等于1.48g/cm 3。在一些实施方式中，负极的膜片电阻率为小于或等于0.50Ω/cm。
在第三方面，本申请提供了一种电子装置，其包括第二方面的二次电池。
附图说明
图1为本申请实施例21的负极材料的SEM图。
图2为本申请对比例1的负极材料的SEM图。
图3示出了本申请实施例19和对比例1的锂离子电池的充放电曲线。
图4示出了本申请实施例1和对比例1的锂离子电池的不可逆锂损失。
图5示出了本申请实施例32和对比例1的锂离子电池的DCR曲线。
具体实施方式
为了简明，本申请仅具体地公开了一些数值范围。然而，任意下限可以与任何上限组 合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，每个单独公开的点或单个数值自身可以作为下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本申请的描述中，除非另有说明，“以上”、“以下”包含本数。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测量方法进行测量(例如，可以按照在本申请的实施例中给出的方法进行测试)。
术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个组分或多个组分。项目B可包含单个组分或多个组分。项目C可包含单个组分或多个组分。
下面结合具体实施方式，进一步阐述本申请。应理解，这些具体实施方式仅用于说明本申请而不用于限制本申请的范围。
一、负极材料
本申请提供的负极材料包括碳基材料，其中，负极材料的表面平均粗糙度为Ra，1.2nm≤Ra≤30nm。负极材料的表层碳原子被不同程度的反应消耗，其表面就会形成相应的褶皱结构，表现为负极材料表面具有一定的粗糙度。本申请的负极材料表面的褶皱结构可以为锂离子提供大量的吸附位点，从而提升负极材料的克容量。同时表面褶皱结构还能够促进锂离子在负极材料基面的扩散，从而改善负极材料的动力学性能。此外，本申请的负极材料可以暴露更多的端面，有利于锂离子的快速嵌入，能够进一步改善其动力学性能。Ra在上述范围内，负极材料具有合适的褶皱结构，可有效提升克容量和改善动力学性能，从而获得高能量密度兼顾快充性能的二次电池，同时不影响其首效、存储、循环等电性能。在一些实施方式中，Ra为1.5nm、2nm、3nm、4nm、5.5nm、6nm、6.5nm、7nm、7.5nm、8nm、8.5nm、9nm、9.5nm、10nm、10.5nm、11nm、11.5nm、12nm、12.5nm、13nm、13.5nm、14nm、14.5nm、15nm、15.5nm、16nm、16.5nm、17nm、17.5nm、18nm、18.5nm、19nm、19.5nm、20nm、21nm、22nm、23nm、24nm、25nm、26nm、27nm、28nm、29nm或这些 值中任意两者组成的范围。在一些实施方式中，5nm≤Ra≤25nm。
在一些实施方式中，通过X射线衍射法测试，负极材料的004晶面衍射峰面积C004与110晶面衍射峰面积C110的比值满足2≤C004/C110≤7。负极材料的C004晶面与基面方向平行，C110晶面与基面方向垂直，C004/C110的比值大小可代表负极材料的晶面取向程度。C004/C110的比值越大，负极材料中与基面平行的晶面占比越大，越不利于锂离子的嵌入，并且循环过程中的膨胀越大。C004/C110的比值过小，极片在循环过程中则有较高的变形风险。C004/C110在上述范围内，负极材料具有合适的晶面取向程度，二次电池既能表现出良好的动力学，其能量密度也不会明显降低。在一些实施方式中，C004/C110为2.5、3、3.5、4、4.5、5、5.5、6、6.5或这些值中任意两者组成的范围。在一些实施方式中，2≤C004/C110≤5。
在一些实施方式中，通过X射线衍射法测试，负极材料沿c轴方向的平均堆积厚度为Lc，20nm≤Lc≤35nm。在一些实施方式中，Lc为21nm、22nm、23nm、24nm、25nm、26nm、27nm、28nm、29nm、30nm、31nm、32nm、33nm、34nm或这些值中任意两者组成的范围。在一些实施方式中，通过X射线衍射法测试，负极材料沿a轴方向的平均堆积厚度为La，95nm≤La≤150nm。在一些实施方式中，La为100nm、103nm、105nm、107nm、110nm、113nm、115nm、117nm、120nm、123nm、125nm、127nm、130nm、143nm、145nm、147nm或这些值中任意两者组成的范围。负极材料的Lc和La值代表其石墨化程度，Lc和La值越小，负极材料的克容量越小。Lc和La值过高时，虽然负极材料的克容量变大，但其循环性能会降低。Lc和La值在上述范围内，负极材料具有高克容量的同时循环性能不会明显降低。在一些实施方式中，23nm≤Lc≤32nm。在一些实施方式中98nm≤La≤145nm。
在一些实施方式中，通过X射线衍射法测试，负极材料002晶面衍射峰的半峰宽为Fw，0.28°≤Fw≤0.35°。在一些实施方式中，Fw为0.285°、0.29°、0.295°、0.3°、0.305°、0.31°、0.315°、0.325°、0.33°、0.335°、0.34°、0.345°或这些值中任意两者组成的范围。Fw越小，负极材料的晶粒尺寸越大，相应的克容量较高，但循环膨胀越差。Fw越大，负极材料的晶粒尺寸越小，其克容量较低。Fw在上述范围内，负极材料具有高克容量的同时循环性能不会明显降低。在一些实施方式中，0.28°≤Fw≤0.32°。
在一些实施方式中，负极材料的Dv50满足：6nm≤Dv50≤15nm。在一些实施方式中，Dv50为6.5nm、7nm、7.5nm、8nm、8.5nm、9nm、9.5nm、10nm、10.5nm、11nm、11.5nm、12nm、12.5nm、13nm、13.5nm、14nm、14.5nm或这些值中任意两者组成的范围。负极材 料的Dv99满足：15nm≤Dv99≤42nm。在一些实施方式中，Dv99为20nm、22nm、24nm、26nm、28nm、30nm、32nm、34nm、36nm、38nm、40nm或这些值中任意两者组成的范围。负极材料的颗粒尺寸Dv50和Dv99影响其表面粗糙度的大小。颗粒越小，负极材料的反应接触面积越大，碳原子反应程度越深，表面粗糙度越高，但负极材料的首效和循环容量保持率也更低。颗粒越大，负极材料在处理时反应更困难，表面粗糙度更小，对其克容量和动力学无明显改善效果，且颗粒太大也使其浆料加工性能变差。负极材料的Dv50和Dv99在上述范围内，包括该负极材料的二次电池兼具高能量密度和快充性能，同时其首效、存储、循环等电性能不会降低。在一些实施方式中，8nm≤Dv50≤13nm。在一些实施方式中，20nm≤Dv99≤35nm。本申请中，Dv50表示负极材料在体积基准的粒度分布中，50％的颗粒粒径小于该值。Dv99表示负极材料在体积基准的粒度分布中，99％的颗粒粒径小于该值。
在一些实施方式中，负极材料的振实密度大于或等于0.80g/cm 3。振实密度过低会导致负极材料在二次电池制备过程中浆料分散性变差，使得浆料易发生沉降，造成涂布厚度不均匀，从而影响二次电池的电性能。在一些实施方式中，负极材料的振实密度为0.90g/cm 3、1.0g/cm 3、1.1g/cm 3、1.2g/cm 3、1.3g/cm 3、1.4g/cm 3或这些值中任意两者组成的范围。
在一些实施方式中，所述碳基材料包括石墨材料，所述石墨材料包括人造石墨和/或天然石墨。
在一些实施方式中，负极材料的制备方法包括：将表面预处理后的石墨材料在液相条件下与(NH 4) 2S 2O 8进行加热反应，其中，所加入的(NH 4) 2S 2O 8质量占比为1％至6％。在一些实施方式中，(NH 4) 2S 2O 8质量占比为1％、1.5％、2％、2.5％、3％、3.5％、4％、4.5％、5％、5.5％、6％或这些值中任意两者组成的范围。本申请中，(NH 4) 2S 2O 8质量占比为(NH 4) 2S 2O 8占预处理后的石墨材料的质量比。在一些实施方式中，液相条件可以由水、醇溶液或有机溶剂提供。
在一些实施方式中，表面预处理后的石墨材料与(NH 4) 2S 2O 8进行加热反应的反应时间为6h至12h。在一些实施方式中，加热反应的反应时间为6h、6.5h、7h、7.5h、8h、8.5h、9h、9.5h、10h、10.5h、11h、11.5h、12h或这些值中任意两者组成的范围。
在一些实施方式中，表面预处理后的石墨材料与(NH 4) 2S 2O 8进行加热反应的反应温度为80℃至150℃。在一些实施方式中，加热反应的反应温度为80℃、90℃、100℃、110℃、120℃、130℃、140℃、150℃或这些值中任意两者组成的范围。
在一些实施方式中，表面预处理方法是石墨材料进行表面包覆后在900℃-1200℃例如1000℃惰性气氛条件下进行炭化，例如炭化4h，然后进行表面刻蚀反应。所用包覆剂为沥青、焦油、树脂类有机物中的至少一种，包覆剂与石墨材料的质量比为(1～5):(99～95)。刻蚀反应方式包括高温气相反应、液相加热反应、高温固相反应中的一种，其中高温气相反应所用气源包括含氧气氛、二氧化碳、二氧化氮、甲烷中的一种，液相加热反应所用反应物包括H 2O 2、浓硫酸、硝酸中的一种，高温固相反应所用反应物包括高锰酸钾、碳酸氢铵、碳酸氢钠中的一种。
二、二次电池
本申请提供的二次电池包括负极，负极包括负极活性材料层，负极活性材料层包括负极活性材料，负极活性材料包括第一方面所述的负极材料。
在一些实施方式中，基于负极活性材料的质量，负极材料的质量含量为w，其中，70％≤w≤100％。在一些实施方式中，w为70％、75％、80％、85％、90％、95％或这些值中任意两者组成的范围。在一些实施方式中，80％≤w≤100％。负极材料Ra大小介于1.2nm至30nm范围内的可显著其提升克容量以及动力学性能，因此其在负极活性材料中的比例在70％以上就可以有效改善二次电池的能量密度和快充性能。
在一些实施方式中，负极的膨胀率小于或等于30％。本申请中，负极的膨胀率＝100％×(T2-T1)/T1，其中，T1为二次电池为0％荷电状态下的负极的厚度，T2为二次电池为100％荷电状态下的负极的厚度。负极材料在处理后暴露了更多晶面，使负极极片中颗粒的膨胀呈多个方向，负极材料的Ra在1.2nm至30nm范围内可一定程度上缓解极片的膨胀率。
在一些实施方式中，负极的压实密度大于或等于1.48g/cm 3。本申请中，负极的压实密度为二次电池为50％荷电状态下的负极的压实密度。在一些实施方式中，负极的膜片电阻率为小于或等于0.50Ω/cm。
在一些实施方式中，负极还包括负极集流体，负极集流体包括：铜箔、铝箔、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或其任意组合。
在一些实施方式中，负极活性材料层还包括粘结剂和导电剂。在一些实施方式中，粘结剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1，1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。
在一些实施方式中，导电剂包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝或银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
本申请的二次电池还包括正极，正极包括正极集流体和正极活性材料层，正极活性材料层包括正极活性材料、粘结剂和导电剂。
根据本申请的一些实施方式，正极集流体可以采用金属箔片或复合集流体。例如，可以使用铝箔。复合集流体可以通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子基材上而形成。
根据本申请的一些实施方式，正极活性材料包括钴酸锂、镍锰钴酸锂、镍锰铝酸锂、磷酸铁锂、磷酸钒锂、磷酸钴锂、磷酸锰锂、磷酸锰铁锂、硅酸铁锂、硅酸钒锂、硅酸钴锂、硅酸锰锂、尖晶石型锰酸锂、尖晶石型镍锰酸锂和钛酸锂中的至少一种。在一些实施例中，粘结剂包括粘合剂聚合物，例如聚偏氟乙烯、聚四氟乙烯、聚烯烃类、羧甲基纤维素钠、羧甲基纤维素锂、改性聚偏氟乙烯、改性SBR橡胶或聚氨酯中的至少一种。在一些实施例中，聚烯烃类粘结剂包括聚乙烯、聚丙烯、聚烯酯、聚烯醇或聚丙烯酸中的至少一种。在一些实施例中，导电剂包括碳基材料，例如天然石墨、人造石墨、炭黑、乙炔黑、科琴黑或碳纤维；金属基材料，例如铜、镍、铝、银等的金属粉或金属纤维；导电聚合物，例如聚亚苯基衍生物；或它们的混合物。
本申请的二次电池还包括隔离膜，本申请的二次电池中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、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。
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至少一种。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、聚乙烯烷氧、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的至少一种。聚合物层中包含聚合物，聚合物的材料选自聚酰胺、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、聚乙烯烷氧、聚偏氟乙烯、聚(偏氟乙烯-六氟丙烯)中的至少一种。
本申请的二次电池还包括电解液。可用于本申请的电解液可以为现有技术中已知的电解液。
根据本申请的一些实施方式，电解液包括有机溶剂、锂盐和可选的添加剂。本申请的电解液中的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中使用的电解质没有限制，其可为现有技术中已知的任何电解质。根据本申请的电解液的添加剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。在一些实施例中，有机溶剂包括，但不限于：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯。在一些实施例中，有机溶剂包括醚类溶剂，例如包括1，3-二氧五环(DOL)和乙二醇二甲醚(DME)中的至少一种。在一些实施例中，锂盐包括有机锂盐或无机锂盐中的至少一种。在一些实施例中，锂盐包括，但不限于：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。在一些实施例中，添加剂包括氟代碳酸乙烯酯和己二腈中的至少一种。
根据本申请的一些实施方式，本申请的二次电池包括，但不限于：锂离子电池或钠离子电池。在一些实施例中，二次电池包括锂离子电池。
三、电子装置
本申请进一步提供了一种电子装置，其包括本申请第二方面的二次电池。
本申请的电子设备或装置没有特别限定。在一些实施例中，本申请的电子设备包括但不限于，笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
在下述实施例及对比例中，所使用到的试剂、材料以及仪器如没有特殊的说明，均可商购获得。
实施例及对比例
实施例1
1、石墨材料制备
本案所用石墨材料包括人造石墨和/或天然石墨，其中人造石墨由针状焦、石油焦、沥青焦、生物质等碳质原料经高温石墨化得到，天然石墨由天然鳞片石墨经球化得到。
2、石墨材料表面预处理
称取一定质量的上述石墨材料，首先进行表面预处理，预处理方法是将石墨材料进行表面包覆后在1000℃惰性气氛条件下炭化4h，所用包覆剂为沥青、焦油、树脂类有机物中的至少一种，包覆剂与石墨材料的质量比为(1～5):(99～95)；然后进行表面刻蚀反应，反应方式包括高温气相反应、液相加热反应、高温固相反应中的一种，其中高温气相反应所用气源包括含氧气氛、二氧化碳、二氧化氮、甲烷中的一种；液相加热反应所用反应物包括H 2O 2、(NH 4) 2S 2O 8、浓硫酸、硝酸中的一种；高温固相反应所用反应物包括高锰酸钾、碳酸氢铵、碳酸氢钠中的一种。
实施例1制备方法为：称取3kg人造石墨材料，以沥青作为包覆剂与人造石墨混合均匀(沥青与人造石墨的质量比为3:97)，然后在1000℃氮气气氛下炭化4h得到表面预处理品；将表面预处理品制成固含量为10％的浆料，加入质量占比(占表面预处理品的质量比)为1％的(NH 4) 2S 2O 8，然后在80℃下反应6h，最后经过滤洗涤干燥可得碳基材料，即负极活性材料。
负极的制备
将上述负极材料、粘结剂丁苯橡胶(简写为SBR)、增稠剂羧甲基纤维素钠(简写为CMC)按照重量比97∶1.5∶1.5配比，再用适量的去离子水溶剂中充分搅拌混合，使其形成均匀的负极浆料；将此浆料涂覆于导电涂层厚度为1μm的集流体Cu箔上，烘干、冷压，即可得到负极极片。
正极的制备
选取钴酸锂(化学式：LiCoO 2)为正极活性材料，将其与导电剂乙炔黑、粘结剂聚偏二氟乙烯(简写为PVDF)按重量比96.3∶2.2∶1.5在适量的N-甲基吡咯烷酮(简写为NMP)溶剂中充分搅拌混合，使其形成均匀的正极浆料；将此浆料涂覆于集流体Al箔上， 烘干、冷压，得到正极极片。
电解液的制备
在干燥的氩气气氛手套箱中，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照质量比为EC:EMC:DEC＝1:3:3:3进行混合，接着加入氟代碳酸乙烯酯和1,3-丙烷磺内酯，溶解并充分搅拌后加入锂盐LiPF 6，混合均匀后得到电解液。其中，LiPF 6的质量百分含量为12.5％，氟代碳酸乙烯酯的质量百分含量为2％，1,3-丙烷磺内酯的质量百分含量为2％，各物质的质量百分含量为基于电解液的质量计算得到。
隔离膜的制备
以厚度为7μm的聚乙烯(PE)多孔聚合物薄膜作为隔离膜，孔隙率为35％。
锂离子电池的制备
1)扣式锂离子电池的制备
将负极裁切成Φ(直径)＝14mm圆片作为工作电极，以Φ(直径)＝18mm金属锂片作为参比电极，两者中间用Φ(直径)＝20mm隔离膜隔开，滴加适量电解液，装配得到CR2430型扣式锂离子电池。
2)软包锂离子电池的制备
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，然后卷绕得到电极组件；焊接极耳后将电极组件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电极组件中，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。
实施例2至实施例11、对比例1至对比例5
负极材料制备
负极材料的制备过程与实施例1类似，不同之处在于通过调整所加入(NH 4) 2S 2O 8的质量比来制备相应的负极材料。具体制备参数如表a所示：
表a
Figure PCTCN2022123062-appb-000001
Figure PCTCN2022123062-appb-000002
负极以及扣式电池、锂离子电池的制备同实施例1。
实施例12至实施例23
负极材料制备
负极材料的制备过程与实施例8类似，不同之处在于通过调整反应时间来调整负极材料的C004/C110值。具体制备参数如表b所示：
表b
Figure PCTCN2022123062-appb-000003
实施例24至实施例30
负极材料的制备过程与实施例21类似，不同之处在于通过调整反应温度来调整负极材料的C004/C110值。具体制备参数如表c所示：
表c
Figure PCTCN2022123062-appb-000004
负极以及扣式电池、锂离子电池的制备同实施例21。
实施例31至实施例36
负极材料制备
负极材料的制备过程与实施例27相同。
负极制备
负极的制备过程与实施例27类似，不同之处在于以石墨负极材料和常规人造石墨作为负极活性材料，其中，石墨负极材料占负极活性材料的质量比分别为95％、90％、85％、80％、75％、70％。
扣式电池、锂离子电池的制备同实施例27。
测试方法
1、Dv50、Dv99测试
本申请使用马尔文粒度测试仪对负极材料粒径进行测量：将负极材料分散在分散剂(乙醇)中，超声30分钟后，将样品加入到马尔文粒度测试仪内，开始测试。所述负极材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积50％的粒径即为所述负极材料的Dv50；同时所述负极材料在体积基准的粒度分布中，从小粒径侧起、达到体积累积99％的粒径即为所述负极材料的Dv99。
2、负极材料表面平均粗糙度测试
通过原子力显微镜(AFM)在负极材料表面15μm×15μm的区域内测试其表面粗糙度R 1、R 2、···、R 100，其表面算术平均粗糙度Ra＝(R 1+R 2+···+R 100)/100。
3、负极材料XRD测试
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》测试负极材料的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CuKα辐射，CuKα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。
采用X射线粉末衍射仪测试负极活性材料石墨，靶材为CuKα；电压电流为40KV/40mA，扫描角度范围为5°至80°，扫描步长为0.00836°，每步长时间为0.3s。根据所得X射线衍射图谱，取002峰的峰强度的最低和最高点之间的50％处的全宽度记为Fw。La为石墨微晶沿a轴方向的平均大小，La＝Kλ/β(2θ)/cosβ。K＝scherrer常数(K＝0.9)，β为100晶面衍射峰的半峰宽，λ为波长(0.154056，θ为100晶面衍射峰最大峰强位置角度。Lc为石墨微晶沿c轴方向的平均堆积厚度，Lc＝Kλ/α(2θ)/cosα。K＝scherrer常数(K＝0.9)，α为002峰的半峰宽，λ为波长(0.154056)，θ为002峰最大峰强位置角度。
4、负极材料振实密度测试
振实密度为在规定条件下容器中的粉末经振实后所测得的单位体积的质量，单位为g/cm 3。
测试方法为将装有一定质量的粉末的刻度量筒固定在机械振动装置上，振动电机带动机械振动装置垂直上下振动，装有粉末的刻度量筒随机械振动装置而发生有节拍的振动，随着振动次数的增加，刻度量筒里的粉末逐渐振实，振动次数达到设定次数后，机械振动装置停止振动，读出刻度量筒的体积。根据密度的定义：质量除以体积，从而求出振实后的粉末密度。具体的工艺参数：振动次数：5000次；振动频率：250±15次/min；环境温度：15℃至28℃。
5、克容量测试
将扣式电池置于蓝电测试仪上进行测试，测试流程为在0.05C下放电至5mv，静置5min，在0.05mA下放电至5mv，在0.01mA下放电至5mv，在0.1C下充电至2.0V即可得充电容量，最后除以活性物质重量即可得负极材料的克容量，充电容量比上放电容量可得首次效率。
6、不可逆Li损失率测试
对扣式电池进行快充性能测试，测试流程如下：
1)测试温度设置在25℃条件下；
2)搁置10min；
3)0.025C放电至3.0V；
4)搁置10min；
5)3C充电至4.48V，恒压至0.025C；
6)搁置10min；
7)0.025C放电至3.0V；
8)搁置10min；
9)第5)-8)步循环10圈；
将最后一圈放电的容量记为D10，将第一圈充电的容量记为C1，不可逆Li损失率Q表示为：Q＝(C1-D10)/C1×100％。
7、锂离子电池DCR直流阻抗测试
1)测试温度为25℃；
2)静置60min；
3)0.5C CC(恒流)至4.48V,CV(恒压)至0.025C；
4)静置10min；
5)0.1C DC(直流)至3V；
6)静置10min；
7)0.5C CC至4.48V,CV至0.025C；
8)静置1h；
9)0.1C DC至10s；
10)1C DC至1s；
11)静置1h；
12)0.5C DC至6min；
13)如果电压≤2.5V，则跳转至第15步；
14)第8步到第13步循环26次；
15)静置10min；
16)0.5C CC至3.95V,CV至0.025C；
17)静置10min；
取70％SOC时电池的阻抗DCR，测试结束。
测试结果
表1示出了负极材料的表面平均粗糙度Ra对锂离子电池性能的影响。
表1
Figure PCTCN2022123062-appb-000005
从表1的数据可以看出，Ra在满足范围1.2nm≤Ra≤30nm时，负极材料具有较高的 克容量和首效，以及较低的DCR和Li损失率。Ra在1.2nm以下时，负极材料克容量偏低，且DCR和Li损失率偏高。Ra在30nm以上，负极材料首效降低，会对锂离子电池的能量密度和循环性能带来不利影响。
表2在实施例8的基础上进一步研究了负极材料的004晶面衍射峰面积与110晶面衍射峰面积的比值C004/C110、负极材料沿c轴方向的平均堆积厚度为Lc、负极材料沿a轴方向的平均堆积厚度La以及002晶面衍射峰的半峰宽对锂离子电池性能的影响。
表2
Figure PCTCN2022123062-appb-000006
从表2的数据可以看出，C004/C110表示负极材料晶面的取向程度，其值越小，负极材料的各向同性越好，有利于锂离子从多个方向嵌入，从而改善动力学性能；但C004/C110过小会造成循环过程中极片变形的风险升高，当C004/C110为2至5时较为合适。此外，限定Lc满足23.0nm≤Lc≤32.0nm，La满足98.0nm≤La≤145nm，Fw满足0.280°≤Fw≤0.320°时，负极材料具有更高的克容量。
表3在实施例21的基础上进一步研究了负极材料的Dv50和Dv99的大小对锂离子电池性能的影响。
表3
Figure PCTCN2022123062-appb-000007
从表3的实施例21、实施例24至实施例26可以看出，随着Dv50和Dv99的减小，负极材料的首效呈降低趋势。推测是因为负极材料的反应接触面积增大，碳原子反应程度加深，表面粗糙度增高，导致与电解液之间发生的副反应加剧，进而导致首效降低。从实施例21、实施例27至实施例30可以看出，随着Dv50和Dv99的增大，负极材料的表面平均粗糙度Ra逐渐减小，克容量水平呈下降趋势。推测是因为颗粒增大后，负极材料在处理时反应更困难，表面粗糙度更小，锂离子的吸附位点减少，从而导致对克容量的改善效果减弱。同时颗粒太大也可能使负极浆料加工性能变差，在较薄的极片涂布工艺中产生颗粒划痕，造成性能降低。振实密度(TD)反应材料在浆料加工过程中的难易程度，随着反应程度增加，材料表面基团增多，易于在浆料中均匀分散。综上，限定Dv50的范围在8nm至13nm，Dv99的范围在20nm至35nm，TD≥0.80g/cm 3时较为合适。
表4在实施例27的基础上进一步研究了负极活性材料中上述石墨负极材料的质量占比w对锂离子电池性能的影响。
表4
Figure PCTCN2022123062-appb-000008
从表4的数据可以看出，Ra满足1.2nm≤Ra≤30nm的石墨占比w在80％以上时，负极片具有更高的克容量，更小的负极膨胀率、更低的DCR和Li损失率。推测是因为1.2nm≤Ra≤30nm的石墨负极材料具有比常规石墨更高的克容量，并且其C004/C110也小于常规石墨，使其在嵌锂后的极片膨胀呈多个方向，故而可缓解负极膨胀率。此外也更有利于锂离子从多个方向嵌入，进而改善动力学性能。因此限定Ra满足1.2nm≤Ra≤30nm的石墨占比w在80％以上可获得较好的改善效果。
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 (10)

  1. 一种负极材料，其包括碳基材料，其中，所述负极材料的表面平均粗糙度为Ra，1.2nm≤Ra≤30nm。
  2. 根据权利要求1所述的负极材料，其中，5nm≤Ra≤25nm。
  3. 根据权利要求1所述的负极材料，其中，所述负极材料满足如下条件(i)至(v)中的至少一者：
    (i)通过X射线衍射法测试，所述负极材料的004晶面衍射峰面积C004与110晶面衍射峰面积C110的比值满足2≤C004/C110≤7；
    (ii)通过X射线衍射法测试，所述负极材料沿c轴方向的平均堆积厚度为Lc，20nm≤Lc≤35nm，所述负极材料沿a轴方向的平均堆积厚度为La，95nm≤La≤150nm；
    (iii)通过X射线衍射法测试，所述负极材料002晶面衍射峰的半峰宽为Fw，0.28°≤Fw≤0.35°；
    (iv)所述负极材料的Dv50满足：6nm≤Dv50≤15nm，所述负极材料的Dv99满足：15nm≤Dv99≤42nm；
    (v)所述负极材料的振实密度大于或等于0.80g/cm 3。
  4. 根据权利要求3所述的负极材料，其中，所述负极材料满足如下条件(vi)至(x)中的至少一者：
    (vi)2≤C004/C110≤5；
    (vii)23nm≤Lc≤32nm，98nm≤La≤145nm；
    (viii)0.28°≤Fw≤0.32°；
    (ix)8nm≤Dv50≤13nm，20nm≤Dv99≤35nm；
    (x)所述负极材料的振实密度为0.80g/cm 3至1.5g/cm 3。
  5. 根据权利要求1所述的负极材料，其中，所述碳基材料包括天然石墨和/或人造石墨。
  6. 根据权利要求1所述的负极材料，其中，所述负极材料的制备方法包括：将预处理后的石墨材料在液相条件下与(NH 4) 2S 2O 8进行加热反应，其中，所加入的(NH 4) 2S 2O 8质量占比为1％至6％。
  7. 一种二次电池，其包括负极，所述负极包括负极活性材料层，所述负极活性材料层包括负极活性材料，所述负极活性材料包括权利要求1-6中任一项所述的负极材料。
  8. 根据权利要求7所述的二次电池，其中，基于所述负极活性材料的质量，所述负 极材料的质量含量为w，其中，70％≤w≤100％。
  9. 根据权利要求7所述的二次电池，其中，所述负极满足如下条件(xi)至(xiii)中的至少一者：
    (xi)所述负极的膨胀率小于或等于30％；
    (xii)所述负极的压实密度大于或等于1.48g/cm 3；
    (xiii)所述负极的膜片电阻率为小于或等于0.50Ω/cm。
  10. 一种电子装置，其包括权利要求7-9中任一项所述的二次电池。
PCT/CN2022/123062 2022-09-30 2022-09-30 负极材料、二次电池和电子装置 WO2024065600A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202280058226.XA CN117882216A (zh) 2022-09-30 2022-09-30 负极材料、二次电池和电子装置
PCT/CN2022/123062 WO2024065600A1 (zh) 2022-09-30 2022-09-30 负极材料、二次电池和电子装置

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2022/123062 WO2024065600A1 (zh) 2022-09-30 2022-09-30 负极材料、二次电池和电子装置

Publications (1)

Publication Number Publication Date
WO2024065600A1 true WO2024065600A1 (zh) 2024-04-04

Family

ID=90475503

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2022/123062 WO2024065600A1 (zh) 2022-09-30 2022-09-30 负极材料、二次电池和电子装置

Country Status (2)

Country Link
CN (1) CN117882216A (zh)
WO (1) WO2024065600A1 (zh)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08171914A (ja) * 1994-12-16 1996-07-02 Toray Ind Inc 電池用電極およびそれを用いた二次電池
CN113795947A (zh) * 2021-02-01 2021-12-14 宁德新能源科技有限公司 负极活性材料及包含其的负极、电化学装置和电子装置
CN115020703A (zh) * 2021-06-21 2022-09-06 宁德新能源科技有限公司 负极活性材料、二次电池和电子装置
CN115101803A (zh) * 2022-07-14 2022-09-23 江苏正力新能电池技术有限公司 一种二次电池

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08171914A (ja) * 1994-12-16 1996-07-02 Toray Ind Inc 電池用電極およびそれを用いた二次電池
CN113795947A (zh) * 2021-02-01 2021-12-14 宁德新能源科技有限公司 负极活性材料及包含其的负极、电化学装置和电子装置
CN115020703A (zh) * 2021-06-21 2022-09-06 宁德新能源科技有限公司 负极活性材料、二次电池和电子装置
CN115101803A (zh) * 2022-07-14 2022-09-23 江苏正力新能电池技术有限公司 一种二次电池

Also Published As

Publication number Publication date
CN117882216A (zh) 2024-04-12

Similar Documents

Publication Publication Date Title
WO2020187040A1 (en) Anode material, and electrochemical device and electronic device using the same
WO2021184532A1 (zh) 负极活性材料及使用其的电化学装置和电子装置
CN111370680B (zh) 电化学装置
CN113795947B (zh) 负极活性材料及包含其的负极、电化学装置和电子装置
JP7295232B2 (ja) 電気化学装置及びそれを含む電子装置
EP4318647A1 (en) Negative electrode, electrochemical device comprising negative electrode, and electronic device
WO2021102846A1 (zh) 负极及包含其的电化学装置和电子装置
WO2024193654A1 (zh) 负极材料、二次电池和电子装置
WO2024065599A1 (zh) 负极材料、二次电池和电子装置
WO2021092869A1 (zh) 负极材料及包含其的电化学装置和电子装置
CN113517442B (zh) 负极材料、电化学装置和电子装置
WO2024065600A1 (zh) 负极材料、二次电池和电子装置
CN112421031B (zh) 电化学装置和电子装置
WO2024178610A1 (zh) 负极活性材料、二次电池和电子装置
WO2024065597A1 (zh) 负极材料、二次电池和电子装置
WO2024178611A1 (zh) 负极活性材料、二次电池和电子装置
WO2024065595A1 (zh) 负极材料、二次电池和电子装置
WO2023070668A1 (zh) 负极活性材料、电化学装置和电子装置
WO2024044974A1 (zh) 负极极片、二次电池和电子装置
WO2024065596A1 (zh) 负极材料、二次电池和电子装置
WO2024044963A1 (zh) 负极极片、二次电池和电子装置
WO2021092866A1 (zh) 负极材料及包含其的电化学装置和电子装置
WO2021134755A1 (zh) 负极和包含其的电化学装置及电子装置
WO2021092867A1 (zh) 负极材料及包含其的电化学装置和电子装置
JP2024129066A (ja) 負極、ならびにこれを用いた電気化学装置および電子装置

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 202280058226.X

Country of ref document: CN

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

Ref document number: 22960228

Country of ref document: EP

Kind code of ref document: A1