WO2020078359A1 - 负极极片及电池 - Google Patents

负极极片及电池 Download PDF

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Publication number
WO2020078359A1
WO2020078359A1 PCT/CN2019/111333 CN2019111333W WO2020078359A1 WO 2020078359 A1 WO2020078359 A1 WO 2020078359A1 CN 2019111333 W CN2019111333 W CN 2019111333W WO 2020078359 A1 WO2020078359 A1 WO 2020078359A1
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Prior art keywords
negative electrode
active material
negative
electrode active
battery
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PCT/CN2019/111333
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English (en)
French (fr)
Inventor
王家政
申玉良
康蒙
何立兵
朱宝健
陈雷
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宁德时代新能源科技股份有限公司
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Publication of WO2020078359A1 publication Critical patent/WO2020078359A1/zh
Priority to US17/232,142 priority Critical patent/US11469409B2/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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • 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
    • 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
    • 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 invention relates to the field of batteries, in particular to a negative pole piece and a battery.
  • Rechargeable batteries have outstanding characteristics such as light weight, high energy density, no pollution, no memory effect, and long service life, so they are widely used in mobile phones, computers, household appliances, power tools and other fields. Among them, charging time is increasingly valued by end consumers, and is also an important factor limiting the popularity of rechargeable batteries.
  • the core of the rapid battery charging technology is to improve the speed of ion movement between the positive and negative electrodes through chemical system reconciliation and design optimization. If the negative electrode cannot withstand high-current charging, ions will be directly reduced and precipitated on the surface of the negative electrode instead of being embedded in the negative electrode active material when the battery is quickly charged. At the same time, a large amount of by-products will be produced on the surface of the negative electrode when the battery is quickly charged, affecting the cycle life and safety. Therefore, the key to rapid battery charging technology lies in the design of the negative active material and the negative pole piece.
  • an object of the present invention is to provide a negative electrode sheet and a battery, the negative electrode sheet having excellent dynamic performance, the battery has both excellent dynamic performance and long cycle life.
  • the present invention provides a negative electrode sheet including a negative electrode current collector and a negative electrode membrane provided on at least one surface of the negative electrode current collector and including a negative electrode active material, said The negative electrode diaphragm satisfies: 6.0 ⁇ PD ⁇ Dv50 ⁇ 32.0 and 0.2 ⁇ PD / Dn10 ⁇ 12.0.
  • PD is the compacted density of the negative electrode diaphragm, the unit is g / cm 3 ;
  • Dv50 is the corresponding particle size when the cumulative volume percentage of the negative electrode active material reaches 50%, the unit is ⁇ m;
  • Dn10 is the cumulative percentage of the negative electrode active material The particle size at 10% corresponds to the unit of ⁇ m.
  • the invention provides a battery including the negative electrode tab of the first aspect of the invention.
  • the present invention includes at least the following beneficial effects:
  • the present invention obtains both dynamics by adjusting the relationship between the compaction density PD of the negative electrode diaphragm and the particle diameters Dv50 and Dn10 of the negative electrode active material A battery with excellent performance and long cycle life under fast charging.
  • a negative electrode sheet which includes a negative electrode current collector and a negative electrode membrane provided on at least one surface of the negative electrode current collector and including a negative electrode active material, the negative electrode membrane satisfying: 6.0 ⁇ PD ⁇ Dv50 ⁇ 32.0 and 0.2 ⁇ PD / Dn10 ⁇ 12.0.
  • PD is the compacted density of the negative electrode diaphragm, the unit is g / cm 3 ;
  • Dv50 is the corresponding particle size when the cumulative volume percentage of the negative electrode active material reaches 50%, the unit is ⁇ m;
  • Dn10 is the cumulative percentage of the negative electrode active material The particle size at 10% corresponds to the unit of ⁇ m.
  • the following three electrochemical processes are required: (1) The ions (such as lithium ions, sodium ions, etc.) that are extracted from the positive electrode active material enter the electrolyte and pass through the negative electrode porous electrode The liquid phase of the pores diffuses and migrates to the surface of the negative electrode active material; (2) Ions and electrons exchange charge on the surface of the negative electrode active material; (3) The ions enter the negative electrode active material bulk and undergo solid phase diffusion and accumulation.
  • the charge exchange process is a very important step. The smaller the charge exchange resistance is, the faster the electrochemical reaction speed is, and the better the dynamic performance of the negative pole piece is, which is more conducive to the improvement of the rapid charging ability of the battery.
  • the factors that affect the charge exchange resistance include the electronic conductance and ion conductance of the entire negative pole piece.
  • the ions can quickly diffuse through the pores of the negative electrode porous electrode and migrate to the surface of the negative electrode active material. When the contact becomes worse, the electron conductance of the negative pole piece becomes worse, which also affects the speed of the electrochemical reaction.
  • the smaller the compact density PD design of the negative electrode diaphragm the smaller the negative electrode capacity, and the energy density and cycle life loss of the battery will increase.
  • the particle size Dv50 of the negative electrode active material represents the particle size corresponding to the cumulative volume percentage of the negative electrode active material reaching 50%.
  • the smaller the particle size Dv50 of the negative electrode active material the smaller the charge exchange resistance of ions and electrons on the surface of the negative electrode active material when the battery is rapidly charged, the faster the electrochemical reaction speed, and the ion is in the solid phase inside the negative electrode active material body phase
  • the particle size Dv50 of the negative electrode active material cannot reflect the actual content of the small particles (or fine powder) of the negative electrode active material in the negative electrode diaphragm, and thus cannot accurately reflect the actual effect degree of the negative electrode active material on the negative electrode ion conductivity.
  • the compaction density PD of the negative electrode membrane is considered in conjunction with the particle diameters Dv50 and Dn10 of the negative electrode active material, where Dn10 represents the corresponding percentage when the cumulative number of negative electrode active materials reaches 10%
  • the particle size which can reflect the content of small particles (or fine powder) in the negative electrode active material particles.
  • the smaller the Dn10 the better the electronic conductivity of the negative pole piece, the higher the content of the small particles (or fine powder) in the negative electrode membrane, and the higher the probability that the pores of the negative electrode porous electrode are blocked, so that the ions of the negative pole piece The conduction becomes worse.
  • the inventors have found through extensive research that when adjusting the relationship between the density of the negative electrode diaphragm PD and the particle diameters Dv50 and Dn10 of the negative electrode active material to satisfy 6.0 ⁇ PD ⁇ Dv50 ⁇ 32.0 and 0.2 ⁇ PD / Dn10 ⁇ 12.0 At the same time, the overall electronic and ionic conductance of the negative pole piece can be maintained better.
  • the negative pole piece has a smaller charge exchange resistance and a higher electrochemical reaction speed, so that the negative pole piece can have excellent kinetic performance.
  • the battery can also have the characteristics of excellent dynamic performance and long cycle life.
  • the lower limit of PD ⁇ Dv50 may be 6.0, 6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.5, 7.8, 8.0
  • the upper limit of PD ⁇ Dv50 may be 8.0, 9.0 , 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0, 22.0, 23.0, 24.0, 25.0, 26.0, 27.0, 28.0, 29.0, 30.0, 31.0, 32.0.
  • 7.0 ⁇ PD ⁇ Dv50 ⁇ 23.0; more preferably, 7.5 ⁇ PD ⁇ Dv50 ⁇ 16.0.
  • the lower limit of PD / Dn10 may be 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.80, 1.0
  • the upper limit of PD / Dn10 may be 1.0 , 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0.
  • the particle diameter Dv50 of the negative electrode active material is 4 ⁇ m to 18 ⁇ m; more preferably, the particle diameter Dv50 of the negative electrode active material is 4 ⁇ m to 16 ⁇ m.
  • the uniformity of the negative electrode sheet can be higher, which can avoid the side effect of the negative electrode active material particle size being too small and the electrolyte causing more side effects to improve the battery performance. The effect can also avoid that the particle size is too large to hinder the solid phase diffusion of ions in the negative electrode active material body phase and affect the improvement effect on the battery performance.
  • the particle size Dn10 of the negative electrode active material is 0.1 ⁇ m to 8.0 ⁇ m; more preferably, the particle size Dn10 of the negative electrode active material is 0.2 ⁇ m to 6.0 ⁇ m .
  • the particle size Dn10 of the negative electrode active material falls within the above-mentioned preferred range, the ion conductivity of the negative electrode sheet can be maintained in a better state, the negative electrode sheet has more excellent kinetic performance, and the battery can also have more excellent kinetic performance And longer cycle life.
  • the internal liquid phase diffusion especially under the severe conditions where the battery has undergone multiple charge and discharge and repeated expansion and contraction, can still ensure that the resistance of the liquid phase diffusion of ions within the pores of the negative electrode porous electrode remains small.
  • the compaction density of the negative electrode membrane PD is too small, it will cause the negative electrode sheet to peel off and lose powder.
  • the negative electrode sheet When charging, the negative electrode sheet has poor electronic conductivity and causes ions to be directly reduced and precipitated on the surface of the negative electrode, affecting the battery's dynamic performance and cycle life. , At the same time, it will also reduce the energy density of the battery.
  • the compact density PD of the negative electrode diaphragm is 0.9 g / cm 3 to 1.8 g / cm 3 ; more preferably, the compact density PD of the negative electrode diaphragm is 1.0 g / cm 3 to 1.6 g / cm 3 .
  • the coating weight per unit area of the negative pole piece also has a certain influence on the dynamic performance of the negative pole piece.
  • the smaller the coating weight per unit area of the negative pole piece the shorter the liquid phase diffusion path of ions in the pores of the negative electrode porous electrode, and the smaller the ionic liquid phase diffusion resistance, the more beneficial it is to improve the dynamic performance of the negative pole piece and the battery.
  • the negative impact of battery energy density and cycle life tends to be greater.
  • the large-particle negative electrode active material also has a certain influence on the negative electrode plate and battery dynamic performance.
  • the particle size Dv90 corresponding to the cumulative volume percentage of the negative electrode active material reaching 90% represents the large particles of the negative electrode active material, and the larger the particle diameter Dv90 of the negative electrode active material, the more the negative electrode active material particles Larger, the greater the solid phase diffusion resistance of the ions in the negative electrode active material body phase, the poorer the ion conduction of the negative pole piece, the more unfavorable to the improvement of the negative pole piece and the battery dynamic performance.
  • the inventors found through extensive research that when the relationship between the coating weight per unit area of the negative pole piece CW and the particle size Dv90 of the negative electrode active material is adjusted to satisfy 0.2 ⁇ CW ⁇ Dv90 ⁇ 5.0, the negative pole piece can maintain excellent power At the same time, it has the advantages of high capacity, so that the battery can better improve the kinetic performance while maintaining a longer cycle life and higher energy density.
  • CW is the coating weight per unit area of the negative electrode piece, and the unit is mg / mm 2
  • Dv90 is the particle size corresponding to the cumulative volume percentage of the negative electrode active material reaching 90%, and the unit is ⁇ m.
  • the lower limit of CW ⁇ Dv90 may be 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0
  • the upper limit of CW ⁇ Dv90 can be 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0.
  • the negative electrode diaphragm satisfies: 1.0 ⁇ CW ⁇ Dv90 ⁇ 4.0; more preferably, the negative electrode diaphragm satisfies: 1.5 ⁇ CW ⁇ Dv90 ⁇ 3.0.
  • the coating weight CW per unit area of the negative electrode sheet is 0.01 mg / mm 2 to 0.20 mg / mm 2 ; more preferably, the unit area of the negative electrode sheet The coating weight CW is 0.04 mg / mm 2 to 0.12 mg / mm 2 .
  • the particle size Dv90 of the negative electrode active material is 12 ⁇ m to 35 ⁇ m; more preferably, the particle size Dv90 of the negative electrode active material is 18 ⁇ m to 30 ⁇ m.
  • the negative electrode active material may be selected from one or more of carbon materials, silicon-based materials, tin-based materials, and lithium titanate.
  • the carbon material may be selected from one or more of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres;
  • the graphite may be selected from one or more of artificial graphite and natural graphite ;
  • the silicon-based material may be selected from one or more of elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon alloys;
  • the tin-based material may be selected from elemental tin, tin-oxygen compounds, tin alloys One or more. More preferably, the negative electrode active material may be selected from one or more of carbon materials and silicon-based materials.
  • the negative electrode diaphragm may be provided on one surface of the negative electrode current collector or on both surfaces of the negative electrode current collector.
  • the type of the negative electrode current collector is also not specifically limited, and can be selected according to actual needs, and copper foil is preferably used.
  • each negative electrode diaphragm given by the present invention also refer to the parameters of the single-sided negative electrode diaphragm.
  • the negative electrode membrane may further include a conductive agent and a binder, wherein the types of the conductive agent and the binder are not specifically limited, and can be selected according to actual needs.
  • the particle diameters Dv50, Dv90, and Dn10 of the negative electrode active material can be obtained by testing using a laser diffraction particle size distribution measuring instrument (Mastersizer 3000), where Dv50 indicates that the cumulative volume percentage of the negative electrode active material reaches 50 % Corresponds to the particle size, Dv90 represents the particle size when the cumulative volume percentage of the negative electrode active material reaches 90%, and Dn10 represents the particle size when the cumulative volume percentage of the negative electrode active material reaches 10%.
  • Mastersizer 3000 a laser diffraction particle size distribution measuring instrument
  • the battery of the second aspect of the present invention further includes a positive pole piece, a separator, an electrolyte, and the like.
  • the battery according to the second aspect of the present application may be a lithium ion battery, a sodium ion battery, and any other battery using the negative pole piece described in the first aspect of the present invention.
  • the positive electrode tab may include a positive electrode current collector and a positive electrode membrane provided on at least one surface of the positive electrode current collector and including a positive electrode active material
  • the positive electrode active material may be selected from lithium Cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, olivine structure-containing lithium phosphate, etc., but this application is not limited
  • other conventionally known materials that can be used as positive electrode active materials for lithium ion batteries can also be used. Only one kind of these positive electrode active materials may be used alone, or two or more kinds may be used in combination.
  • the cathode active material may be selected from LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 O 2 , LiFePO 4 (LFP), LiMnPO 4 Or several.
  • the positive electrode sheet may include a positive electrode current collector and a positive electrode membrane provided on at least one surface of the positive electrode current collector and including a positive electrode active material
  • the positive electrode active material may be selected from the transition Metal oxide Na x MO 2 (M is a transition metal, preferably one or more selected from Mn, Fe, Ni, Co, V, Cu, Cr, 0 ⁇ x ⁇ 1), polyanionic material (phosphate , Fluorophosphate, pyrophosphate, sulfate), Prussian blue material, etc., but this application is not limited to these materials, this application can also use other conventionally known materials that can be used as positive electrode active materials for sodium ion batteries.
  • M is a transition metal, preferably one or more selected from Mn, Fe, Ni, Co, V, Cu, Cr, 0 ⁇ x ⁇ 1
  • polyanionic material phosphate , Fluorophosphate, pyrophosphate, sulfate
  • Prussian blue material etc.
  • the positive electrode active material may be selected from NaFeO 2 , NaCoO 2 , NaCrO 2 , NaMnO 2 , NaNiO 2 , NaNi 1/2 Ti 1/2 O 2 , NaNi 1/2 Mn 1/2 O 2 , Na 2 / 3 Fe 1/3 Mn 2/3 O 2 , NaNi 1/3 Co 1/3 Mn 1/3 O 2, NaFePO 4, NaMnPO 4, NaCoPO 4, Prussian blue materials, the general formula A a M b (PO 4 ) Materials of c O x Y 3-x (where A is selected from one or more of H + , Li + , Na + , K + , NH 4+ , M is a transition metal cation, preferably selected from V, One or more of Ti, Mn, Fe, Co, Ni, Cu, Zn, Y is a halogen anion, preferably one or more selected from F, Cl, Br
  • the separator is provided between the positive pole piece and the negative pole piece to play a role of isolation.
  • the type of the separator is not specifically limited, and may be any separator material used in existing batteries, such as polyethylene, polypropylene, polyvinylidene fluoride, and their multilayer composite membranes, but not limited to These ones.
  • the electrolyte includes an electrolyte salt and an organic solvent, and the specific types and compositions of the electrolyte salt and the organic solvent are not subject to specific restrictions, and can be selected according to actual needs.
  • the electrolyte may also include additives, and the type of additives is not particularly limited. It may be a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain performance of the battery, such as improving the battery's overcharge performance. Additives, additives to improve the high temperature performance of batteries, additives to improve the low temperature performance of batteries, etc.
  • the positive electrode active material (see Table 1 for details), the conductive agent acetylene black, the binder polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 96: 2: 2, and the solvent N-methylpyrrolidone (NMP) is added in a vacuum Stir under the action of a mixer until the system is uniform to obtain a positive electrode slurry; uniformly coat the positive electrode slurry on the positive electrode current collector aluminum foil, dry it at room temperature, then transfer to an oven to continue drying, and then obtain the positive electrode sheet after cold pressing and slitting .
  • NMP solvent N-methylpyrrolidone
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1: 1: 1 to obtain an organic solvent, and then the fully dried lithium salt LiPF 6 is dissolved in the mixture After the organic solvent is prepared, a concentration of 1mol / L electrolyte is prepared.
  • Polyethylene film is used as isolation film.
  • the above positive pole pieces, separators and negative pole pieces are stacked in order, so that the separation membrane is placed between the positive and negative pole pieces to play the role of isolation, and then wound to obtain the bare cell; place the bare cell in the outer packaging
  • the electrolyte is injected after drying, and the lithium ion battery is obtained through the steps of vacuum packaging, standing, forming, and shaping.
  • the batteries prepared in the examples and comparative examples were fully charged at xC and fully discharged at 1C for 10 times, the batteries were fully charged at xC, and then the negative pole pieces were disassembled and the negative electrode was observed Lithium precipitation on the surface of the pole piece. If lithium is not deposited on the surface of the negative electrode, the charging rate xC will be tested again in increments of 0.1C until the lithium is deposited on the surface of the negative electrode to stop the test. At this time, the charging rate xC minus 0.1C is the maximum charging rate of the battery .
  • the batteries prepared in the examples and comparative examples were charged at a rate of 3C and discharged at a rate of 1C.
  • a full-charge cycle test was conducted until the battery capacity was less than 80% of the initial capacity, and the number of battery cycles was recorded.
  • Example 1 A PD ⁇ Dv50 PD / Dn10 CW ⁇ Dv90 Maximum battery charge rate Number of battery cycles
  • Example 1 6.0 10.00 0.24 3.0C 2800
  • Example 2 6.4 8.00 2.40 3.5C 3300
  • Example 3 6.8 3.40 0.24 3.6C 3700
  • Example 4 7.5 1.50 1.20 4.4C 4200
  • Example 5 9.6
  • 2.40 0.68 4.8C 4500 Example 6 11.2 1.40 0.68 4.8C 4500
  • Example 7 12.8 0.80 0.68 4.9C 4900
  • Example 8 16.0 1.33 2.32 5.0C 5500
  • Example 9 18.0 0.75 1.76 3.8C 3500
  • Example 10 20.4 0.34 1.76 3.2C 3000
  • Example 11 17.6 1.10 4.80 3.6C 3500
  • Example 12 21.6 12.00 3.50 3.2C 3100
  • Example 13 21.6 0.20 3.50 3.3C 3200
  • Example 14 18.0 0.50 3.50 3.7C 3300
  • Example 15 23.4 0.33 3.50 3.1
  • Example 16 32.0 0.45 3.50 3.0C 2600 Example 17 7.5 1.50 0.15 3.5C 3100 Example 18 19.2 1.60 5.22 3.3C 2900 Example 19 6.0 10.00 1.00 3.0C 2700 Example 20 22.0 1.10 3.80 4.0C 3300 Example 21 6.0 11.11 1.20 3.0C 2500 Example 22 24.0 0.20 2.80 3.0C 2400 Example 23 6.4 1.60 1.70 3.2C 2900 Example 24 11.4 3.80 1.20 4.8C 4000 Example 25 20.8 0.43 4.80 3.6C 1500 Example 26 24.0 0.25 4.80 3.0C 1550 Comparative Example 1 4.8 6.00 0.48 1.2C 330 Comparative Example 2 36.0 0.45 1.28 1.1C 320 Comparative Example 3 12.8 16.00 1.36 1.2C 280 Comparative Example 4 21.6 0.15 2.80 1.2C 260 Comparative Example 5 5.6 14.00 1.44 1.0C 160 Comparative Example 6 5.2 6.50 1.44 1.2C 330 Comparative Example 7 12.8 16.00 2.72 1.1C 320 Comparative Example 8 35.2 0.40
  • the negative pole pieces of the batteries of Examples 1-26 all satisfy 6.0 ⁇ PD ⁇ Dv50 ⁇ 32.0 and 0.2 ⁇ PD / Dn10 ⁇ 12.0 at the same time.
  • the matching relationship between the particle size Dv50 and Dn10 of the active material is good.
  • the charge exchange resistance of the negative pole piece can be controlled within a small range.
  • the negative pole piece has good electronic conductivity and ion conductivity at the same time, so the battery can be considered at the same time. Excellent dynamic performance and long cycle life.
  • the particle size of the negative electrode active material Dv50 is preferably controlled between 4 ⁇ m to 18 ⁇ m
  • the particle size of the negative electrode active material Dn10 is preferably controlled between 0.1 ⁇ m to 8.0 ⁇ m
  • the compacted density PD of the negative electrode diaphragm is preferably controlled to 0.9 g / cm 3 ⁇ 1.8g / cm 3
  • the battery dynamic performance can be better improved while ensuring the advantages of high energy density of the battery, and the ability of the negative pole piece to retain the electrolyte is better.
  • the difference between the negative electrode active material and the electrolyte The interface charge transfer impedance is also lower, and the battery cycle performance can be further improved.
  • the particle size Dv50 of the negative electrode active material when one or several parameters in the particle size Dv50 of the negative electrode active material, the particle size Dn10 of the negative electrode active material, and the compaction density PD of the negative electrode membrane fail to satisfy the above-mentioned preferred range, as long as the negative electrode sheet simultaneously satisfies 6.0 ⁇ PD ⁇ Dv50 ⁇ 32.0 and 0.2 ⁇ PD / Dn10 ⁇ 12.0, combined with Examples 19-24, the battery can still take into account both excellent kinetic performance and long cycle life.
  • the negative pole piece can maintain excellent dynamic performance while With the advantages of high capacity, the battery can better improve the dynamic performance while maintaining a longer cycle life and higher energy density.
  • the coating weight CW per unit area of the negative pole piece and the particle size Dv90 of the negative electrode active material do not reach an optimal match, CW ⁇ Dv90 ⁇ 0.2, at this time the coating weight per unit area of the negative pole piece is relatively small, although the ion The liquid phase diffusion path inside the anode porous electrode channel is shorter and the ion liquid phase diffusion resistance is smaller, the better the battery's dynamic performance, but the battery energy density and cycle life are slightly worse than those in Example 4.
  • the coating weight CW of the negative electrode piece per unit area and the particle size Dv90 of the negative electrode active material do not reach the optimal match, CW ⁇ Dv90> 5.0, at this time the particle size Dv90 of the negative electrode active material is relatively large, and the The solid phase diffusion resistance inside the bulk phase of the active material is relatively large, and the ion conduction of the negative pole piece is slightly poor. Therefore, compared with Example 8, the effect of improving the battery dynamic performance is slightly worse.

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Abstract

本发明提供了一种负极极片及电池，所述负极极片包括负极集流体以及设置在负极集流体至少一个表面上且包括负极活性材料的负极膜片，所述负极膜片满足：6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0。本发明的负极极片具有优异的动力学性能，本发明的电池兼具优异的动力学性能以及长的循环寿命。

Description

负极极片及电池 技术领域
本发明涉及电池领域，尤其涉及一种负极极片及电池。
背景技术
可充电电池具有重量轻、能量密度高、无污染、无记忆效应、使用寿命长等突出特点，因而被广泛应用于手机、电脑、家用电器、电动工具等领域。其中，充电时间越来越受到终端消费者的重视，也是限制可充电电池普及的重要因素。
从技术原理来说，电池快速充电技术的核心是通过化学体系调和及设计优化来提升离子在正负极间的移动速度。如果负极无法承受大电流充电，在电池快速充电时离子会在负极表面直接还原析出而不是嵌入负极活性材料中，同时在电池快速充电时负极表面还会产生大量副产物，影响电池的循环寿命和安全性。因此，电池快速充电技术的关键在于负极活性材料以及负极极片的设计。
发明内容
鉴于背景技术中存在的问题，本发明的目的在于提供一种负极极片及电池，所述负极极片具有优异的动力学性能，所述电池兼具优异的动力学性能以及长的循环寿命。
为了达到上述目的，在本发明的第一方面，本发明提供了一种负极极片，其包括负极集流体以及设置在负极集流体至少一个表面上且包括负极活性材料的负极膜片，所述负极膜片满足：6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0。其中，PD为负极膜片的压实密度，单位为g/cm 3；Dv50为负极活性材料累计体积百分数达到50％时所对应的粒径，单位为μm；Dn10为负极活性材料累计数量百分数达到10％时所对应的粒径，单位为μm。
在本发明的第二方面，本发明提供了一种电池，其包括本发明第一方面 所述的负极极片。
相对于现有技术，本发明至少包括如下所述的有益效果：本发明通过调节负极膜片的压实密度PD与负极活性材料的粒径Dv50、Dn10之间的关系，得到了兼具动力学性能优异以及快速充电下循环寿命长特点的电池。
具体实施方式
下面详细说明根据本发明的负极极片及电池。
首先说明根据本发明第一方面的负极极片，其包括负极集流体以及设置在负极集流体至少一个表面上且包括负极活性材料的负极膜片，所述负极膜片满足：6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0。其中，PD为负极膜片的压实密度，单位为g/cm 3；Dv50为负极活性材料累计体积百分数达到50％时所对应的粒径，单位为μm；Dn10为负极活性材料累计数量百分数达到10％时所对应的粒径，单位为μm。
在电池充电过程中，对于负极极片来说，需要经过如下的3个电化学过程：(1)正极活性材料脱出的离子(例如锂离子、钠离子等)进入电解液中，经由负极多孔电极的孔道液相扩散并迁移到负极活性材料表面；(2)离子与电子在负极活性材料表面发生电荷交换；(3)离子进入负极活性材料体相内部并进行固相扩散和积累。其中，电荷交换过程是相当重要的一个步骤，电荷交换电阻越小说明电化学反应的速度越快，负极极片的动力学性能越好，越有利于电池快速充电能力的提升。通常，影响电荷交换电阻的因素包括负极极片整体的电子电导和离子电导。
一般而言，负极膜片的压实密度PD设计越高，负极膜片中活性材料颗粒与颗粒之间的电子接触越好，负极极片的电子电导越好，但负极膜片的孔隙变少，离子在负极多孔电极孔道内部液相扩散阻力变大，负极极片的离子电导变差，从而影响了电化学反应的速度；负极膜片的压实密度PD设计越小，负极极片的离子电导越好，离子在负极多孔电极孔道内部液相扩散阻力越小，离子可以经由负极多孔电极的孔道快速扩散并迁移至负极活性材料表面，但负极膜片中活性材料颗粒与颗粒之间的电子接触变差，负极极片的电子电导变差，也会影响电化学反应的速度。另外，负极膜片的压实密度PD 设计越小，负极容量也越小，电池的能量密度以及循环寿命损失还会增加。
在负极极片设计中，负极活性材料的粒径Dv50表示负极活性材料累计体积百分数达到50％时所对应的粒径。一般而言，负极活性材料的粒径Dv50越小，电池快速充电时离子与电子在负极活性材料表面电荷交换阻力越小，电化学反应速度越快，且离子在负极活性材料体相内部固相扩散阻力也越小，但同时，发生小颗粒(或细粉)负极活性材料堵塞负极多孔电极孔道的概率也越高，离子在负极多孔电极孔道内部液相扩散路径延长、液相扩散阻力增加，负极极片的离子传导变差，由此影响了电化学反应的速度。但是负极活性材料的粒径Dv50不能反映出负极膜片中小颗粒(或细粉)负极活性材料的实际含量，由此不能准确反映负极活性材料对负极极片离子电导的实际影响程度。
在本发明的负极极片设计中，将负极膜片的压实密度PD与负极活性材料的粒径Dv50、Dn10结合考虑，其中，Dn10表示负极活性材料的累计数量百分数达到10％时所对应的粒径，其可以反映负极活性材料颗粒中小颗粒(或细粉)部分的含量。通常，Dn10越小，负极极片的电子电导越好，负极膜片中小颗粒(或细粉)部分含量也越高，负极多孔电极孔道被堵塞的概率也越高，由此负极极片的离子传导变差。且发明人经过大量研究发现，当调节负极膜片的压实密度PD与负极活性材料的粒径Dv50、Dn10之间的关系使其满足6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0时，负极极片整体的电子电导和离子电导均可保持较优，负极极片具有较小的电荷交换电阻以及较高的电化学反应速度，由此负极极片可具有优异的动力学性能，电池也可兼具动力学性能优异以及循环寿命长的特点。
在本发明的一些实施方式中，PD×Dv50的下限值可以为6.0、6.2、6.4、6.6、6.8、7.0、7.2、7.5、7.8、8.0，PD×Dv50的上限值可以为8.0、9.0、11.0、12.0、13.0、14.0、15.0、16.0、17.0、18.0、19.0、20.0、21.0、22.0、23.0、24.0、25.0、26.0、27.0、28.0、29.0、30.0、31.0、32.0。优选地，7.0≤PD×Dv50≤23.0；更优选地，7.5≤PD×Dv50≤16.0。
在本发明的一些实施方式中，PD/Dn10的下限值可以为0.20、0.25、0.30、0.35、0.40、0.45、0.50、0.55、0.60、0.80、1.0，PD/Dn10的上限值可以为1.0、1.5、2.0、2.5、3.0、3.5、4.0、4.5、5.0、5.5、6.0、6.5、7.0、7.5、8.0、 8.5、9.0、9.5、10.0、10.5、11.0、11.5、12.0。优选地，0.3≤PD/Dn10≤9.0；更优选地，0.35≤PD/Dn10≤6.0。
在本发明第一方面的负极极片中，优选地，所述负极活性材料的粒径Dv50为4μm～18μm；更优选地，所述负极活性材料的粒径Dv50为4μm～16μm。负极活性材料的粒径Dv50落入上述优选范围内时，负极极片的均一性可更高，可以避免负极活性材料粒径太小与电解液产生较多的副反应而影响对电池性能的改善效果，还可以避免粒径太大阻碍离子在负极活性材料体相内部固相扩散而影响对电池性能的改善效果。
在本发明第一方面的负极极片中，优选地，所述负极活性材料的粒径Dn10为0.1μm～8.0μm；更优选地，所述负极活性材料的粒径Dn10为0.2μm～6.0μm。负极活性材料的粒径Dn10落入上述优选范围内时，负极极片的离子电导可保持在更优的状态，负极极片具有更优异的动力学性能，电池也可具有更优异的动力学性能以及更长的循环寿命。
在本发明第一方面的负极极片中，在其它条件相同的情况下，负极膜片的压实密度PD越小，则负极多孔电极的孔道结构越发达，越有利于离子在负极多孔电极孔道内部的液相扩散，尤其是在电池经历多次充放电并出现反复膨胀收缩的严苛条件下，仍可以保证离子在负极多孔电极孔道内部液相扩散阻力保持在较小程度。但负极膜片的压实密度PD过小，会导致负极极片脱膜掉粉，充电时负极极片电子电导较差而使离子直接在负极表面还原析出，影响电池的动力学性能和循环寿命，同时也会降低电池的能量密度。优选地，所述负极膜片的压实密度PD为0.9g/cm 3～1.8g/cm 3；更优选地，所述负极膜片的压实密度PD为1.0g/cm 3～1.6g/cm 3。负极膜片的压实密度落入上述优选范围内时，可以在更好地提升电池动力学性能以及循环寿命的同时保持电池较高能量密度优势。
在本发明第一方面的负极极片中，负极极片单位面积涂布重量也会对负极极片的动力学性能有一定影响。通常，负极极片单位面积涂布重量越小，离子在负极多孔电极孔道内部液相扩散路径就越短、离子液相扩散阻力就越小，越有利于负极极片以及电池动力学性能的提升，但同时电池能量密度以及循环寿命受到的负面影响趋向于越大。除了涂布重量外，大颗粒负极活性材料对负极极片以及电池动力学性能也有一定影响。通常，在负极极片设计 中，用负极活性材料累计体积百分数达到90％时所对应的粒径Dv90表示负极活性材料大颗粒，且负极活性材料的粒径Dv90越大，说明负极活性材料颗粒越大，离子在负极活性材料体相内部固相扩散阻力越大，负极极片的离子传导越差，越不利于负极极片以及电池动力学性能的提升。发明人通过大量研究发现，当调节负极极片单位面积涂布重量CW和负极活性材料的粒径Dv90之间的关系使其满足0.2≤CW×Dv90≤5.0时，负极极片可在保持优异动力学性能的同时兼具高容量优势，进而电池可在更好地提升动力学性能的同时保持更长的循环寿命和更高的能量密度。其中，CW为负极极片单位面积涂布重量，单位为mg/mm 2；Dv90为负极活性材料累计体积百分数达到90％时所对应的粒径，单位为μm。
在本发明的一些实施方式中，CW×Dv90的下限值可以为0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9、1.0、1.1、1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2.0，CW×Dv90的上限值可以为1.8、2.0、2.2、2.4、2.6、2.8、3.0、3.2、3.4、3.6、3.8、4.0、4.2、4.4、4.6、4.8、5.0。优选地，所述负极膜片满足：1.0≤CW×Dv90≤4.0；更优选地，所述负极膜片满足：1.5≤CW×Dv90≤3.0。
在本发明第一方面的负极极片中，优选地，所述负极极片单位面积涂布重量CW为0.01mg/mm 2～0.20mg/mm 2；更优选地，所述负极极片单位面积涂布重量CW为0.04mg/mm 2～0.12mg/mm 2。
在本发明第一方面的负极极片中，优选地，所述负极活性材料的粒径Dv90为12μm～35μm；更优选地，所述负极活性材料的粒径Dv90为18μm～30μm。
在本发明第一方面的负极极片中，优选地，所述负极活性材料可选自碳材料、硅基材料、锡基材料、钛酸锂中的一种或几种。其中，所述碳材料可选自石墨、软碳、硬碳、碳纤维、中间相碳微球中的一种或几种；所述石墨可选自人造石墨、天然石墨中的一种或几种；所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅合金中的一种或几种；所述锡基材料可选自单质锡、锡氧化合物、锡合金中的一种或几种。更优选地，所述负极活性材料可选自碳材料、硅基材料中的一种或几种。
在本发明第一方面的负极极片中，所述负极膜片可设置在负极集流体的其中一个表面上也可以设置在负极集流体的两个表面上。所述负极集流体的 种类也不受具体的限制，可根据实际需求进行选择，优选可使用铜箔。
需要说明的是，当负极膜片同时设置在负极集流体两个表面上时，只要其中任意一个表面上的负极膜片满足本发明，即认为该负极极片落入本发明的保护范围内。同时本发明所给的各负极膜片参数也均指单面负极膜片的参数。
在本发明第一方面的负极极片中，所述负极膜片还可以包括导电剂、粘结剂，其中导电剂和粘结剂的种类不受具体的限制，可根据实际需求进行选择。
在本发明第一方面的负极极片中，负极活性材料的粒径Dv50、Dv90、Dn10可通过使用激光衍射粒度分布测量仪(Mastersizer 3000)测试得到，Dv50表示负极活性材料的累计体积百分数达到50％时所对应的粒径，Dv90表示负极活性材料的累计体积百分数达到90％时所对应的粒径，Dn10表示负极活性材料的累计数量百分数达到10％时所对应的粒径。
其次说明根据本发明第二方面的电池，其包括根据本发明第一方面所述的负极极片。
进一步，本发明第二方面的电池还包括正极极片、隔离膜以及电解液等。
需要说明的是，根据本申请第二方面的电池可为锂离子电池、钠离子电池以及任何其它使用本发明第一方面所述负极极片的电池。
具体的，当电池为锂离子电池时：所述正极极片可包括正极集流体以及设置在正极集流体至少一个表面上且包括正极活性材料的正极膜片，所述正极活性材料可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、橄榄石结构的含锂磷酸盐等，但本申请并不限定于这些材料，还可以使用其他可被用作锂离子电池正极活性材料的传统公知的材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。优选地，所述正极活性材料可选自LiCoO 2、LiNiO 2、LiMnO 2、LiMn 2O 4、LiNi 1/3Co 1/3Mn 1/3O 2(NCM333)、LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)、LiNi 0.6Co 0.2Mn 0.2O 2(NCM622)、LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)、LiNi 0.85Co 0.15Al 0.05O 2、LiFePO 4(LFP)、LiMnPO 4中的一种或几种。
具体的，当电池为钠离子电池时：所述正极极片可包括正极集流体以及 设置在正极集流体至少一个表面上且包括正极活性材料的正极膜片，所述正极活性材料可选自过渡金属氧化物Na xMO 2(M为过渡金属，优选选自Mn、Fe、Ni、Co、V、Cu、Cr中的一种或几种，0<x≤1)、聚阴离子材料(磷酸盐、氟磷酸盐、焦磷酸盐、硫酸盐)、普鲁士蓝材料等，但本申请并不限定于这些材料，本申请还可以使用其他可被用作钠离子电池正极活性材料的传统公知的材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。优选地，所述正极活性材料可选自NaFeO 2、NaCoO 2、NaCrO 2、NaMnO 2、NaNiO 2、NaNi 1/2Ti 1/2O 2、NaNi 1/2Mn 1/2O 2、Na 2/3Fe 1/3Mn 2/3O 2、NaNi 1/3Co 1/3Mn 1/3O 2、NaFePO 4、NaMnPO 4、NaCoPO 4、普鲁士蓝材料、通式为A aM b(PO 4) cO xY 3-x的材料(其中A选自H +、Li +、Na +、K +、NH 4+中的一种或几种，M为过渡金属阳离子，优选选自V、Ti、Mn、Fe、Co、Ni、Cu、Zn中的一种或几种，Y为卤素阴离子，优选选自F、Cl、Br中的一种或几种，0<a≤4，0<b≤2，1≤c≤3，0≤x≤2)中的一种或几种。
在本发明第二方面的电池中，所述隔离膜设置在正极极片和负极极片之间，起到隔离的作用。其中，所述隔离膜的种类并不受到具体的限制，可以是现有电池中使用的任何隔离膜材料，例如聚乙烯、聚丙烯、聚偏氟乙烯以及它们的多层复合膜，但不仅限于这些。
在本发明第二方面的电池中，所述电解液包括电解质盐以及有机溶剂，其中电解质盐和有机溶剂的具体种类及组成均不受到具体的限制，可根据实际需求进行选择。所述电解液还可包括添加剂，添加剂种类没有特别的限制，可以为负极成膜添加剂，也可为正极成膜添加剂，也可以为能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
下面以锂离子电池为例并结合具体实施例，进一步阐述本申请。应理解，这些实施例仅用于说明本申请而不用于限制本申请的范围。
实施例1
(1)正极极片的制备
将正极活性材料(详见表1)、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF) 按重量比96:2:2进行混合，加入溶剂N-甲基吡咯烷酮(NMP)，在真空搅拌机作用下搅拌至体系呈均一状，获得正极浆料；将正极浆料均匀涂覆在正极集流体铝箔上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切得到正极极片。
(2)负极极片的制备
将负极活性材料(详见表1)、导电剂乙炔黑、增稠剂羧甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按重量比96.4:1:1.2:1.4进行混合，加入溶剂去离子水，在真空搅拌机作用下搅拌至体系呈均一状，获得负极浆料；将负极浆料均匀涂覆在负极集流体铜箔上，室温晾干后转移至烘箱继续干燥，然后经过冷压、分切得到负极极片。
(3)电解液的制备
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照按体积比1:1:1进行混合得到有机溶剂，接着将充分干燥的锂盐LiPF 6溶解于混合后的有机溶剂中，配制成浓度为1mol/L的电解液。
(4)隔离膜的制备
选用聚乙烯膜作为隔离膜。
(5)锂离子电池的制备
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正、负极极片之间起到隔离的作用，然后卷绕得到裸电芯；将裸电芯置于外包装壳中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，获得锂离子电池。
实施例2-26以及对比例1-9的锂离子电池均按照与实施例1类似的方法进行制备，具体区别示出在表1中。
表1：实施例1-26以及对比例1-9的参数
Figure PCTCN2019111333-appb-000001
Figure PCTCN2019111333-appb-000002
Figure PCTCN2019111333-appb-000003
接下来说明电池的性能测试。
(1)动力学性能测试
在25℃下，将实施例和对比例制备得到的电池以x C满充、以1C满放重复10次后，再将电池以x C满充，然后拆解出负极极片，并观察负极极片表面析锂情况。如果负极表面未析锂，则将充电倍率x C以0.1C为梯度递增再次进行测试，直至负极表面析锂，停止测试，此时的充电倍率x C减去0.1C即为电池的最大充电倍率。
(2)循环性能测试
在25℃下，将实施例和对比例制备得到的电池以3C倍率充电、以1C倍率放电，进行满充满放循环测试，直至电池的容量小于初始容量的80％，记录电池的循环圈数。
各实施例和对比例的测试结果详见表2。
表2：实施例1-26以及对比例1-9的性能测试结果
  PD×Dv50 PD/Dn10 CW×Dv90 电池最大充电倍率 电池循环圈数
实施例1 6.0 10.00 0.24 3.0C 2800
实施例2 6.4 8.00 2.40 3.5C 3300
实施例3 6.8 3.40 0.24 3.6C 3700
实施例4 7.5 1.50 1.20 4.4C 4200
实施例5 9.6 2.40 0.68 4.8C 4500
实施例6 11.2 1.40 0.68 4.8C 4500
实施例7 12.8 0.80 0.68 4.9C 4900
实施例8 16.0 1.33 2.32 5.0C 5500
实施例9 18.0 0.75 1.76 3.8C 3500
实施例10 20.4 0.34 1.76 3.2C 3000
实施例11 17.6 1.10 4.80 3.6C 3500
实施例12 21.6 12.00 3.50 3.2C 3100
实施例13 21.6 0.20 3.50 3.3C 3200
实施例14 18.0 0.50 3.50 3.7C 3300
实施例15 23.4 0.33 3.50 3.1C 2800
实施例16 32.0 0.45 3.50 3.0C 2600
实施例17 7.5 1.50 0.15 3.5C 3100
实施例18 19.2 1.60 5.22 3.3C 2900
实施例19 6.0 10.00 1.00 3.0C 2700
实施例20 22.0 1.10 3.80 4.0C 3300
实施例21 6.0 11.11 1.20 3.0C 2500
实施例22 24.0 0.20 2.80 3.0C 2400
实施例23 6.4 1.60 1.70 3.2C 2900
实施例24 11.4 3.80 1.20 4.8C 4000
实施例25 20.8 0.43 4.80 3.6C 1500
实施例26 24.0 0.25 4.80 3.0C 1550
对比例1 4.8 6.00 0.48 1.2C 330
对比例2 36.0 0.45 1.28 1.1C 320
对比例3 12.8 16.00 1.36 1.2C 280
对比例4 21.6 0.15 2.80 1.2C 260
对比例5 5.6 14.00 1.44 1.0C 160
对比例6 5.2 6.50 1.44 1.2C 330
对比例7 12.8 16.00 2.72 1.1C 320
对比例8 35.2 0.40 5.60 1.2C 220
对比例9 14.4 0.15 4.40 1.2C 160
从表2的测试结果可以看出：实施例1-26的电池中负极极片均同时满足6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0，负极膜片的压实密度PD与负极活性材料的粒径Dv50、Dn10之间的匹配关系良好，负极极片的电荷交换电阻均能控制在较小的范围内，负极极片同时具有好的电子电导和离子电导，因此电池可同时兼顾优异的动力学性能以及较长的循环寿命。
与实施例1-26相比，在对比例1-9中，当PD×Dv50和PD/Dn10至少一个不在所给范围内时，电池的动力学性能及循环寿命均较差。
其中，负极活性材料的粒径Dv50优选控制在4μm～18μm之间，负极活性材料的粒径Dn10优选控制在0.1μm～8.0μm之间，负极膜片的压实密度PD优选控制在为0.9g/cm 3～1.8g/cm 3之间。各参数在上述优选范围内时，可以在更好地提升电池动力学性能的同时保证电池高能量密度优势，同时负极极片 保有电解液的能力也更好，负极活性材料和电解液之间的界面电荷转移阻抗也更低，电池循环性能也能得到进一步提升。但当负极活性材料的粒径Dv50、负极活性材料的粒径Dn10、负极膜片的压实密度PD中的一个或几个参数未能满足上述优选范围时，只要保证负极极片同时满足6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0，结合实施例19-24，电池仍可同时兼顾优异的动力学性能以及较长的循环寿命。
进一步地，当调节负极极片单位面积涂布重量CW和负极活性材料的粒径Dv90之间的关系使其满足0.2≤CW×Dv90≤5.0时，负极极片可在保持优异动力学性能的同时兼具高容量优势，进而电池可在更好地提升动力学性能的同时保持更长的循环寿命和更高的能量密度。
结合实施例17，负极极片单位面积涂布重量CW和负极活性材料的粒径Dv90未达到最优匹配，CW×Dv90<0.2，此时负极极片单位面积涂布重量相对较小，尽管离子在负极多孔电极孔道内部液相扩散路径较短、离子液相扩散阻力较小，电池的动力学性能越好，但电池能量密度以及循环寿命与实施例4相比略差。
结合实施例18，负极极片单位面积涂布重量CW和负极活性材料的粒径Dv90未达到最优匹配，CW×Dv90>5.0，此时负极活性材料的粒径Dv90相对较大，离子在负极活性材料体相内部固相扩散阻力较大，负极极片的离子传导稍差，因此与实施例8相比，对电池动力学性能的提升效果略差。
从实施例25-26以及对比例6-9中可知，当电池选用不同的正、负极活性材料，只要负极极片同时满足6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0时，电池仍可兼顾优异的动力学性能以及较长的循环寿命。
根据上述说明书的揭示和教导，本领域技术人员还可以对上述实施方式进行变更和修改。因此，本发明并不局限于上面揭示和描述的具体实施方式，对本发明的一些修改和变更也应当落入本发明的权利要求的保护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本发明构成任何限制。

Claims (10)

  1. 一种负极极片，包括负极集流体以及设置在负极集流体至少一个表面上且包括负极活性材料的负极膜片；
    其特征在于，
    所述负极膜片满足：6.0≤PD×Dv50≤32.0以及0.2≤PD/Dn10≤12.0；
    其中，
    PD为负极膜片的压实密度，单位为g/cm 3；
    Dv50为负极活性材料累计体积百分数达到50％时所对应的粒径，单位为μm；
    Dn10为负极活性材料累计数量百分数达到10％时所对应的粒径，单位为μm。
  2. 根据权利要求1所述的负极极片，其特征在于，
    所述负极膜片满足：7.0≤PD×Dv50≤23.0；
    优选地，所述负极膜片满足：7.5≤PD×Dv50≤16.0。
  3. 根据权利要求1所述的负极极片，其特征在于，
    所述负极膜片满足：0.3≤PD/Dn10≤9.0；
    优选地，所述负极膜片满足：0.35≤PD/Dn10≤6.0。
  4. 根据权利要求1所述的负极极片，其特征在于，所述负极活性材料的粒径Dv50为4μm～18μm，优选为4μm～16μm。
  5. 根据权利要求1所述的负极极片，其特征在于，所述负极活性材料的粒径Dn10为0.1μm～8.0μm，优选为0.2μm～6.0μm。
  6. 根据权利要求1所述的负极极片，其特征在于，所述负极膜片的压实密度PD为0.9g/cm 3～1.8g/cm 3，优选为1.0g/cm 3～1.6g/cm 3。
  7. 根据权利要求1所述的负极极片，其特征在于，
    所述负极活性材料选自碳材料、硅基材料、锡基材料、钛酸锂中的一种或几种；
    优选地，所述负极活性材料选自碳材料、硅基材料中的一种或几种。
  8. 根据权利要求1-7中任一项所述的负极极片，其特征在于，
    所述负极膜片还满足：0.2≤CW×Dv90≤5.0；
    其中，
    CW为负极极片单位面积涂布重量，单位为mg/mm 2；
    Dv90为负极活性材料累计体积百分数达到90％时所对应的粒径，单位为μm；
    优选地，所述负极膜片满足：1.0≤CW×Dv90≤4.0；
    更优选地，所述负极膜片满足：1.5≤CW×Dv90≤3.0。
  9. 根据权利要求8所述的负极极片，其特征在于，
    所述负极极片单位面积涂布重量CW为0.01mg/mm 2～0.20mg/mm 2，优选为0.04mg/mm 2～0.12mg/mm 2；
    和/或，所述负极活性材料的粒径Dv90为12μm～35μm，优选为18μm～30μm。
  10. 一种电池，其特征在于，包括权利要求1-9中任一项所述负极极片。
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