WO2020078358A1 - 负极极片及电池 - Google Patents

负极极片及电池 Download PDF

Info

Publication number
WO2020078358A1
WO2020078358A1 PCT/CN2019/111331 CN2019111331W WO2020078358A1 WO 2020078358 A1 WO2020078358 A1 WO 2020078358A1 CN 2019111331 W CN2019111331 W CN 2019111331W WO 2020078358 A1 WO2020078358 A1 WO 2020078358A1
Authority
WO
WIPO (PCT)
Prior art keywords
negative electrode
battery
active material
diaphragm
negative
Prior art date
Application number
PCT/CN2019/111331
Other languages
English (en)
French (fr)
Inventor
王家政
康蒙
申玉良
何立兵
Original Assignee
宁德时代新能源科技股份有限公司
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 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to EP19872955.0A priority Critical patent/EP3790081A4/en
Priority to US16/973,536 priority patent/US11469418B2/en
Publication of WO2020078358A1 publication Critical patent/WO2020078358A1/zh

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/04Processes of manufacture in general
    • H01M4/0402Methods of deposition of the material
    • H01M4/0404Methods of deposition of the material by coating on electrode collectors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/58Selection 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
    • H01M4/583Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134Electrodes based on metals, Si or alloys
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386Silicon or alloys based on silicon
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/38Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387Tin or alloys based on tin
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M2004/021Physical characteristics, e.g. porosity, surface area
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M2004/026Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027Negative electrodes
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy 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, and power tools. 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.
  • the object of the present invention is to provide a negative pole piece and a battery, the negative pole piece has the characteristics of excellent dynamic performance, the battery can simultaneously take into account the excellent dynamic performance, long cycle life, High energy density.
  • 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, and
  • the negative electrode diaphragm satisfies: 4 ⁇ P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] ⁇ 20.
  • P is the porosity of the negative electrode diaphragm
  • Dv50 is the volume median particle size of the negative electrode active material, in units of ⁇ m
  • M is the capacity of the negative electrode diaphragm per unit area, in mAh / cm 2 .
  • the invention provides a battery comprising the negative pole piece according to the first aspect of the invention.
  • the present invention includes at least the following beneficial effects: the present invention adjusts the porosity P of the negative electrode membrane, the capacity M of the negative electrode membrane per unit area, and the volume median diameter Dv50 of the negative electrode active material The relationship between the battery and the battery with excellent dynamic performance, long cycle life and high energy density was obtained.
  • a negative electrode sheet which includes a negative electrode current collector and a negative electrode film provided on at least one surface of the negative electrode current collector and including a negative electrode active material, and the negative electrode film satisfies: 4 ⁇ P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] ⁇ 20.
  • P is the porosity of the negative electrode diaphragm
  • Dv50 is the volume median particle size of the negative electrode active material, in units of ⁇ m
  • M is the capacity of the negative electrode diaphragm per unit area, in mAh / cm 2 .
  • the capacity M per unit area of the negative electrode membrane refers to the capacity per unit area of the negative electrode membrane located on any one surface of the negative electrode current collector.
  • the lower limit of P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] may be 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, the upper limit of P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] can be 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13 , 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20.
  • the ions such as lithium ions, sodium ions, etc.
  • the liquid enters the pores of the negative electrode porous electrode and undergoes a liquid phase diffusion process of ions inside the pores of the negative electrode porous electrode;
  • the ions pass through the SEI film on the surface of the negative electrode active material and exchange charge with electrons on the surface of the negative electrode active material;
  • Ions enter the negative electrode active material bulk and undergo solid phase diffusion and accumulation.
  • the porosity P of the negative electrode diaphragm becomes larger, the degree of accumulation between the particles of the negative electrode active material in the negative diaphragm becomes loose, the electronic contact between the particles becomes poor, the electron conduction performance deteriorates, and the ions and electrons The charge exchange resistance of the surface of the negative electrode active material tends to increase, thereby affecting the improvement effect on the battery dynamic performance.
  • the porosity P of the negative electrode diaphragm becomes larger, the advantage of the high volume energy density of the negative electrode is gradually lost, thereby also affecting the energy density of the battery.
  • the smaller the volume median 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 charged, and the smaller the solid phase diffusion and accumulation resistance of ions in the negative electrode active material body phase.
  • the probability of occurrence of small particle size negative electrode active materials clogging the pores of the negative electrode porous electrode is also higher.
  • the liquid phase conduction path of the ions in the negative electrode porous electrode channel is extended, and the liquid phase diffusion resistance is increased, thereby affecting the battery dynamic performance. Lifting effect.
  • the smaller the volume median particle size Dv50 of the negative electrode active material the advantage of the high volume energy density of the negative electrode is gradually lost, thereby also affecting the energy density of the battery.
  • the different parameters of the negative electrode active material and the negative pole piece have different influences on the battery cycle life, energy density and kinetic performance.
  • the above parameters are optimized by themselves to achieve excellent kinetic performance and long cycle at the same time. There are significant limitations in terms of lifetime and higher energy density.
  • P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] ⁇ 20 the liquid phase conduction resistance of ions in the pores of the negative electrode porous electrode and the charge exchange of ions and electrons on the surface of the negative electrode active material Resistance and solid phase diffusion and accumulation resistance of ions in the negative electrode active material body phase are kept to a small extent.
  • the negative pole piece can have excellent kinetic performance and high volume energy density, thereby enabling the battery to have excellent kinetic performance At the same time taking into account the advantages of long cycle life and higher energy density.
  • the negative electrode membrane has a porosity P of 20% to 65%; further preferably, the negative electrode membrane has a porosity P of 22% to 60% More preferably, the negative electrode membrane has a porosity P of 22% to 55%.
  • the porosity of the negative electrode membrane falls within the above-mentioned preferred range, the resistance of the liquid phase diffusion of ions in the pores of the negative electrode porous electrode and the charge exchange resistance of ions and electrons on the surface of the negative electrode active material are both small, and the negative electrode sheet can have more excellent power
  • the ability of the negative electrode diaphragm to retain the electrolyte is also better, which can ensure that the negative electrode active material particles have good electrolyte wettability between the particles, and the interface charge transfer resistance between the negative electrode active material and the electrolyte is also Lower, battery dynamic performance and cycle life can be further improved.
  • the volume median particle size Dv50 of the negative electrode active material is 4 ⁇ m to 20 ⁇ m; further preferably, the volume median particle size Dv50 of the negative electrode active material is 4 ⁇ m -18 ⁇ m; more preferably, the volume median particle size Dv50 of the negative electrode active material is 4 ⁇ m-16 ⁇ m.
  • the volume median particle size of the negative electrode active material falls within the above-mentioned preferred range, the uniformity of the negative electrode sheet can be higher, thereby preventing the side effect of the negative electrode active material particle size being too small and the electrolyte from generating more side reactions.
  • the improvement effect of the battery performance can also avoid that the particle size is too large to hinder the solid phase diffusion and accumulation of the ions in the negative electrode active material bulk phase and affect the improvement effect on the battery performance.
  • the capacity M of the negative electrode membrane per unit area is controlled at 0.5 mAh / cm 2 to 7.0 mAh / cm 2 ; further preferably, the negative electrode membrane per unit area The capacity M is controlled within 1.0 mAh / cm 2 to 6.0 mAh / cm 2 ; more preferably, the capacity M per unit area of the negative electrode diaphragm is controlled within 1.0 mAh / cm 2 to 5.5 mAh / cm 2 .
  • the negative electrode sheet can maintain excellent kinetic performance while having the advantage of high volume energy density, and thus the battery can better improve the kinetics while maintaining High energy density advantage.
  • the gram capacity of the negative electrode active material (unit mAh / g), the coating weight per unit area of the negative electrode sheet (unit g / cm 2 ) and the proportion of the negative electrode active material in the negative electrode membrane all affect the negative electrode membrane unit area
  • the capacity M (unit mAh / cm 2 ).
  • the higher the gram capacity of the negative electrode active material the higher the coating weight per unit area of the negative electrode sheet, the higher the proportion of negative electrode active material in the negative electrode membrane, The larger the capacity M, the weaker the battery's rapid charging ability and the worse the battery's dynamic performance.
  • 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 coating weight per unit area of the negative electrode sheet is 1 mg / cm 2 to 22 mg / cm 2 ; further preferably, the coating weight per unit area of the negative electrode sheet It is 2 mg / cm 2 to 18 mg / cm 2 ; more preferably, the coating weight per unit area of the negative electrode sheet is 4 mg / cm 2 to 12 mg / cm 2 .
  • the coating weight per unit area of the negative pole piece falls within the above-mentioned preferred range, the negative pole piece can maintain excellent kinetic performance while having the advantage of high volume energy density, and thus the battery can better improve the kinetic performance while maintaining The advantage of higher energy density.
  • 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 is too small, it will cause the negative electrode membrane to peel off and lose powder.
  • the electronic conductivity is poor during charging and the ions are directly reduced and precipitated on the surface of the negative electrode. Reduce the energy density of the battery.
  • the compact density PD of the negative electrode diaphragm is 0.8 g / cm 3 to 2.0 g / cm 3 ; further preferably, the compact density PD of the negative electrode diaphragm is 1.0 g / cm 3 to 1.6 g / cm 3 .
  • the battery dynamic performance can be better improved while maintaining the battery's higher energy density advantage.
  • the capacity M of the negative electrode membrane per unit area, and the volume median particle size Dv50 of the negative electrode active material have a great influence on the battery dynamic performance
  • the adhesion force F between the negative electrode diaphragm and the negative electrode current collector will also affect the battery dynamic performance.
  • the adhesion force F (unit N / m) between the negative electrode diaphragm and the negative electrode current collector and the capacity M (unit mAh / cm 2 ) per unit area of the negative electrode diaphragm satisfy M / 3 ⁇ F
  • the adhesive force between the negative electrode membrane and the negative electrode current collector satisfies M / 2 ⁇ F ⁇ 5M.
  • the coating weight per unit area of the negative electrode sheet is constant, the magnitude of the adhesive force between the negative electrode membrane and the negative electrode current collector and the binder content, type of binder, and negative electrode membrane in the negative electrode membrane Factors such as the compacted density of the sheet are related, and those skilled in the art can select a known method to adjust the adhesion between the negative electrode membrane and the negative electrode current collector according to the actual situation.
  • 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 negative electrode diaphragm may further include a conductive agent and a binder, and the types and contents of the conductive agent and the binder are not specifically limited, and can be selected according to actual needs.
  • 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 battery further includes a positive pole piece, a separator, and an electrolyte.
  • 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-structured lithium-containing 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 positive electrode 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 , one or more of LiFePO 4 and LiMnPO 4 .
  • 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, wherein the specific types of electrolyte salt and 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 lithium ion batteries of Examples 1-22 and Comparative Examples 1-4 were prepared according to the following methods
  • the positive electrode active material (see Table 1 for details), the conductive agent conductive carbon black SP, the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 96: 2: 2, and the solvent N-methylpyrrolidone (NMP) is added, Stir under the action of a vacuum mixer until the system is uniform to obtain a positive electrode slurry; evenly coat the positive electrode slurry on both surfaces of the positive electrode current collector aluminum foil, dry it at room temperature, then transfer to an oven to continue drying, and then cold press, Cut to obtain the positive pole piece.
  • 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, followed by dissolving the fully dried lithium salt LiPF 6 in the mixture After the organic solvent is prepared, a concentration of 1mol / L electrolyte is prepared.
  • 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 volume median particle size Dv50 of the negative electrode active material can be obtained by testing using a laser diffraction particle size distribution measuring instrument (Mastersizer 3000). Dv50 represents the particle size corresponding to the cumulative volume percentage of the negative electrode active material reaching 50%.
  • a small area of negative pole coated with a single surface was obtained by using a punching die.
  • the lithium metal sheet as the counter electrode and the Celgard membrane as the separator using the electrolytes prepared in the above examples and comparative examples, six CR2430 button batteries were assembled in an argon-protected glove box. After assembling the button battery, let it stand for 12h, and then test it.
  • the capacity of the negative electrode membrane per unit area M the average charging capacity of the negative electrode membrane / the area of the negative electrode wafer.
  • the adhesion test between the negative electrode diaphragm and the negative electrode current collector can refer to the national standard GB / T2790-1995 adhesive 180 ° peel strength test method, and the specific operation can be carried out by using a high-speed rail tensile machine at a peeling speed of 50 mm / min for 180 ° peeling
  • the average value of the peeling force collected when the 60 mm negative electrode membrane is completely peeled off from the negative electrode current collector is the adhesive force between the negative electrode membrane and the negative electrode current collector.
  • 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. 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 fully charged at 1C rate and fully discharged at 1C rate, and the actual discharge energy at this time was recorded; at 25 ° C, the battery was weighed using an electronic balance; The ratio of the actual discharge energy of the battery 1C to the weight of the battery is the actual energy density of the battery.
  • the actual energy density of the battery when the actual energy density is less than 80% of the expected energy density, the actual energy density of the battery is considered to be very low; when the actual energy density is greater than or equal to 80% of the expected energy density and less than 95% of the expected energy density, the actual energy density of the battery is considered low When the actual energy density is greater than or equal to 95% of the expected energy density and less than 105% of the expected energy density, the actual energy density of the battery is considered to be moderate; when the actual energy density is greater than or equal to 105% of the expected energy density and less than 120% of the expected energy density, It is considered that the actual energy density of the battery is high; when the actual energy density is more than 120% of the expected energy density, the actual energy density of the battery is considered to be very high.
  • 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.
  • the negative pole pieces of Examples 1-22 all satisfy 4 ⁇ P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M)] ⁇ 20, and the battery can simultaneously achieve excellent The characteristics of dynamic performance, long cycle life and high energy density. This is due to the good matching relationship between the porosity P of the negative electrode diaphragm, the capacity M of the negative electrode diaphragm per unit area, and the volume median particle size Dv50 of the negative electrode active material, and the liquid phase diffusion resistance of lithium ions in the pores of the negative electrode porous electrode.
  • the charge exchange resistance of lithium ions and electrons on the surface of the negative electrode active material and the solid phase diffusion and accumulation resistance of lithium ions in the negative electrode active material body phase are small, so the battery can simultaneously take into account excellent kinetic performance, long cycle life and high energy Characteristics of density.
  • the porosity P of the negative electrode diaphragm is preferably controlled between 20% and 65%.
  • the battery can take into account both excellent dynamic performance and long cycle life.
  • the capacity M per unit area of the negative electrode diaphragm is preferably controlled between 0.5 mAh / cm 2 and 7.0 mAh / cm 2.
  • the battery can take into account a longer cycle life and a higher energy density.
  • the volume median particle size Dv50 of the negative electrode active material is preferably controlled to be between 4 ⁇ m and 20 ⁇ m.
  • the battery can balance excellent kinetic performance and high energy density.
  • the battery can still have good kinetic performance and cycle performance without sacrificing energy density.
  • Example 11 and Comparative Examples 3-4 when different positive and negative electrode active materials are used for the battery, as long as the negative pole piece satisfies 4 ⁇ P ⁇ [(30-Dv50) / 2 + 2 ⁇ (10-M) ] ⁇ 20, the battery can still take into account the characteristics of excellent dynamic performance, long cycle life and higher energy density.
  • the battery can be better improved Dynamic performance and cycle performance, while ensuring that the battery has the advantage of higher energy density.
  • Example 21 In combination with Example 21, the adhesion force F between the negative electrode diaphragm and the negative electrode current collector is small, the electronic contact between the negative electrode active material particles is poor, and the electronic contact between the negative electrode film and the negative electrode current collector is also relatively low Poor, the conductivity of electrons through the negative electrode current collector to the negative electrode membrane is poor, and the resistance of lithium ion and electron charge exchange on the surface of the negative electrode active material is greater, so compared with Example 8, Example 21 has better battery dynamic performance and cycling The performance improvement effect is slightly worse. Combining with Example 22, the adhesive force F between the negative electrode diaphragm and the negative electrode current collector is too large.
  • Example 22 improves the battery dynamic performance and cycle performance The effect is also slightly worse.

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于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,且所述负极膜片满足:4≤P×[(30-Dv50)/2+2×(10-M)]≤20。其中,P为负极膜片的孔隙率;Dv50为负极活性材料的体积中位粒径,单位为μm;M为负极膜片单位面积的容量,单位为mAh/cm2。本发明的负极极片具有动力学性能优异的特点,本发明的电池同时兼顾动力学性能优异、循环寿命长、能量密度较高的特点。

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。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,所述负极极片具有动力学性能优异的特点,所述电池能同时兼顾动力学性能优异、循环寿命长、能量密度较高的特点。
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于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,且所述负极膜片满足:4≤P×[(30-Dv50)/2+2×(10-M)]≤20。其中,P为负极膜片的孔隙率;Dv50为负极活性材料的体积中位粒径,单位为μm;M为负极膜片单位面积的容量,单位为mAh/cm 2
在本发明的第二方面,本发明提供了一种电池,其包括根据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孔隙率P、负极膜片单位面积的容量M以及负极活性材料的体积中位粒径Dv50之间的关系,得到了同时兼顾优异动力学性能、长循环寿命以及较高能量密度的电池。
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于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,且所述负极膜片满足:4≤P×[(30-Dv50)/2+2×(10-M)]≤20。其中,P为负极膜片的孔隙率;Dv50为负极活性材料的体积中位粒径,单位为μm;M为负极膜片单位面积的容量,单位为mAh/cm 2。需要说明的是,负极膜片单位面积的容量M是指位于负极集流体其中任一个表面上的负极膜片单位面积的容量。
在本发明的一些实施方式中,P×[(30-Dv50)/2+2×(10-M)]的下限值可以为4、4.5、5、5.5、6、6.5、7、7.5、8、8.5、9,P×[(30-Dv50)/2+2×(10-M)]的上限值可以为8.5、9、9.5、10、10.5、11、11.5、12、12.5、13、13.5、14、14.5、15、15.5、16、16.5、17、17.5、18、18.5、19、19.5、20。优选地,6≤P×[(30-Dv50)/2+2×(10-M)]≤15;进一步优选地,8≤P×[(30-Dv50)/2+2×(10-M)]≤12。
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,并随着电解液进入负极多孔电极的孔道中,进行离子在负极多孔电极孔道内部的液相扩散过程;(2)离子穿过负极活性材料表面的SEI膜并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。上述3个电化学过程的阻力越小,越有利于提升电池快速充电能力,电池的动力学性能也越优异;反之,上述3个电化学过程的阻力越大,越不利于提升电池快速充电能力,电池的动力学性能也越差。
通常,负极膜片的孔隙率P越小,离子在负极多孔电极孔道内部液相扩散阻力就越大,越不利于提升电池快速充电能力,电池的动力学性能也越差; 反之,负极膜片的孔隙率P越大,离子在负极多孔电极孔道内部液相扩散阻力就越小,原则上越有利于提升电池快速充电能力,电池的动力学性能也越优异。但是负极膜片的孔隙率P变大时,负极膜片中负极活性材料颗粒与颗粒之间堆积程度变得松散,颗粒与颗粒之间的电子接触变差,电子传导性能恶化,离子与电子在负极活性材料表面电荷交换阻力趋向于增加,由此影响了对电池动力学性能的提升效果。同时,负极膜片的孔隙率P变大时,负极高体积能量密度的优势逐渐丧失,由此还影响了电池的能量密度。
通常,负极活性材料的体积中位粒径Dv50越小,那么电池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,离子在负极活性材料体相内部固相扩散以及积累阻力也越小,但同时,发生小粒径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传导路径延长、液相扩散阻力增加,由此影响了对电池动力学性能的提升效果。且负极活性材料的体积中位粒径Dv50越小,负极高体积能量密度的优势逐渐丧失,由此还影响了电池的能量密度。
通常,负极膜片单位面积的容量M越小,离子在负极活性材料体相内部积累速率越快,越有利于提升电池快速充电能力,电池的动力学性能也越优异,但同时负极膜片单位面积的容量M越小,电池能量密度以及循环寿命受到的负面影响也越大。
因此,负极活性材料以及负极极片的不同参数对电池循环寿命、能量密度以及动力学性能的影响程度是不一样的,仅靠上述参数自身优化,对实现电池同时兼顾优异动力学性能、长循环寿命以及较高能量密度方面存在很大的局限性。
发明人通过大量研究发现,当负极膜片的孔隙率P(无量纲)、负极活性材料的体积中位粒径Dv50(单位为μm)、负极膜片单位面积的容量M(单位为mAh/cm 2)满足4≤P×[(30-Dv50)/2+2×(10-M)]≤20时,离子在负极多孔电极孔道内部液相传导阻力、离子与电子在负极活性材料表面电荷交换阻力以及离子在负极活性材料体相内部固相扩散以及积累阻力均保持在较小程度,负极极片可具有优异的动力学性能以及高的体积能量密度,由此可以使电池具有优异动力学性能同时兼顾长循环寿命以及较高能量密度的优势。
在本发明第一方面的负极极片中,优选地,所述负极膜片的孔隙率P为 20%~65%;进一步优选地,所述负极膜片的孔隙率P为22%~60%;更进一步优选地,所述负极膜片的孔隙率P为22%~55%。负极膜片的孔隙率落入上述优选范围内时,离子在负极多孔电极孔道内部液相扩散阻力以及离子与电子在负极活性材料表面电荷交换阻力均较小,负极极片可具有更优异的动力学性能;同时,负极膜片保有电解液的能力也更好,可保证负极活性材料颗粒与颗粒之间具有良好的电解液浸润性,且负极活性材料和电解液之间的界面电荷转移阻抗也更低,电池动力学性能以及循环寿命可得到进一步提升。
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体积中位粒径Dv50为4μm~20μm;进一步优选地,所述负极活性材料的体积中位粒径Dv50为4μm~18μm;更进一步优选地,所述负极活性材料的体积中位粒径Dv50为4μm~16μm。负极活性材料的体积中位粒径落入上述优选范围内时,负极极片的均一性可更高,由此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的固相扩散以及积累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,所述负极膜片单位面积的容量M控制在0.5mAh/cm 2~7.0mAh/cm 2;进一步优选地,所述负极膜片单位面积的容量M控制在1.0mAh/cm 2~6.0mAh/cm 2;更进一步优选地,所述负极膜片单位面积的容量M控制在1.0mAh/cm 2~5.5mAh/cm 2。负极膜片单位面积的容量落入上述优选范围内时,负极极片可在保持优异动力学性能的同时兼具高体积能量密度优势,进而电池可以在更好地提升动力学性的同时保持较高能量密度优势。
其中,负极活性材料的克容量(单位mAh/g)、负极极片单位面积涂布重量(单位g/cm 2)以及负极活性材料在负极膜片中所占比例均会影响负极膜片单位面积的容量M(单位mAh/cm 2)。通常,在其它制备条件相同的情况下,负极活性材料的克容量越高、负极极片单位面积涂布重量越高、负极活性材料在负极膜片中所占比例越高,负极膜片单位面积的容量M越大,电池的快速充电能力越弱,电池的动力学性能也越差。这是由于负极活性材料的克容量越高,在相同条件下离子在负极活性材料体相内部固相扩散以及积 累阻力越大;负极极片单位面积涂布重量越高、负极活性材料在负极膜片中所占比例越高,负极膜片的厚度越大,离子在负极多孔电极孔道内部液相扩散路径就越长、离子液相扩散阻力越大,越不利于电池动力学性能的提升。
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,优选地,所述负极极片单位面积涂布重量为1mg/cm 2~22mg/cm 2;进一步优选地,所述负极极片单位面积涂布重量为2mg/cm 2~18mg/cm 2;更进一步优选地,所述负极极片单位面积涂布重量为4mg/cm 2~12mg/cm 2。负极极片单位面积涂布重量落入上述优选范围内时,负极极片可在保持优异动力学性能的同时兼具高体积能量密度优势,进而电池可以在更好地提升动力学性能的同时保持较高能量密度优势。
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过小,会导致负极极片脱膜掉粉,充电时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0.8g/cm 3~2.0g/cm 3;进一步优选地,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,除了负极膜片的孔隙率P、负极膜片单位面积的容量M、负极活性材料的体积中位粒径Dv50对电池动力学性能影响很大之外,负极膜片与负极集流体之间的粘接力F也会对电池动力学性 能产生影响。负极膜片与负极集流体之间的粘接力F越大,电子经过负极集流体到达负极膜片的传导能力越好,离子与电子在负极活性材料表面电荷交换阻力越小,电池动力学性能越优异;但负极膜片与负极集流体之间的粘接力F过大可能会降低电池的能量密度。发明人通过大量研究发现,当负极膜片与负极集流体之间的粘接力F(单位N/m)与负极膜片单位面积的容量M(单位mAh/cm 2)满足M/3≤F≤6M时,可以更好地提升电池动力学性能以及循环性能,同时保证电池具有较高能量密度的优势。优选地,负极膜片与负极集流体之间的粘接力满足M/2≤F≤5M。
需要说明的是,在负极极片单位面积涂布重量一定的情况下,负极膜片与负极集流体之间的粘接力大小与负极膜片中粘结剂含量、粘结剂种类、负极膜片压实密度等因素有关,本领域技术人员可以根据实际情况选择公知的方法来调节负极膜片与负极集流体之间的粘接力大小。
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。所述负极膜片还可包括导电剂以及粘接剂,且导电剂以及粘接剂的种类和含量不受具体的限制,可根据实际需求进行选择。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。
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,所述电池还包括正极极片、隔离膜以及电解液。
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、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。在下述实施例中,除非另有说明,所用到的原料均可商购获得。
一、实施例1-22和对比例1-4的锂离子电池均按照下述方法进行制备
(1)正极极片的制备
将正极活性材料(详见表1)、导电剂导电碳黑SP、粘接剂聚偏氟乙烯(PVDF)按质量比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的两个表面上,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)、导电剂导电碳黑SP、增稠剂羧甲基纤维素钠(CMC)、粘接剂丁苯橡胶(SBR)按一定质量比进行混合,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的两个表面上,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
选择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。
二、负极活性材料及负极极片参数测定
(1)负极活性材料的体积中位粒径Dv50可通过使用激光衍射粒度分布测量仪(Mastersizer 3000)测试得到,Dv50表示负极活性材料累计体积百分数达到50%时所对应的粒径。
(2)负极膜片的孔隙率P可通过气体置换法得到,孔隙率P=(V 1-V 2)/V 1×100%,V 1表示负极膜片的表观体积,V 2表示负极膜片的真实体积。
(3)负极膜片单位面积的容量M可通过如下方法测试得到:
取各实施例及对比例制备的负极极片,利用冲片模具获得一定面积的单面涂覆的负极小圆片。以金属锂片为对电极、Celgard膜为隔离膜,采用上述各实施例及对比例制备的电解液,在氩气保护的手套箱中组装6个CR2430型扣式电池。扣式电池组装完后静置12h,之后进行测试。首先在0.05C的放电电流下进行恒流放电,直到电压为5mV;然后再用50μA的放电电流进行恒流放电,直到电压为5mV;接着用10μA的放电电流进行恒流放电,直到电压为5mV;静置5min,最后在0.05C的充电电流下进行恒流充电,直到最终电压为2V,记录此步骤的充电容量。6个扣式电池充电容量的平均值即为负极膜片的平均充电容量。
负极膜片单位面积的容量M=负极膜片的平均充电容量/负极小圆片的面积。
(4)负极膜片与负极集流体之间的粘接力
负极膜片与负极集流体之间的粘接力测试可参考国家标准GB/T2790-1995胶粘剂180°剥离强度试验方法,具体操作时可利用高铁拉力机以50mm/min的剥离速度进行180°剥离力测试,60mm负极膜片从负极集流体上完全剥离时所采集的剥离力平均值即为负极膜片与负极集流体之间的粘接力。
三、电池性能测试
(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)实际能量密度测试
在25℃下,将实施例和对比例制备得到的电池以1C倍率满充、以1C倍率满放,记录此时的实际放电能量;在25℃下,使用电子天平对该电池进行称重;电池1C实际放电能量与电池重量的比值即为电池的实际能量密度。
其中,实际能量密度小于预期能量密度的80%时,认为电池实际能量密度非常低;实际能量密度大于等于预期能量密度的80%且小于预期能量密度的95%时,认为电池实际能量密度偏低;实际能量密度大于等于预期能量密度的95%且小于预期能量密度的105%时,认为电池实际能量密度适中;实际能量密度大于等于预期能量密度的105%且小于预期能量密度的120%时,认为电池实际能量密度较高;实际能量密度为预期能量密度的120%以上时,认为电池实际能量密度非常高。
(3)循环寿命测试
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。
表1:实施例1-22和对比例1-4的参数
Figure PCTCN2019111331-appb-000001
Figure PCTCN2019111331-appb-000002
注:公式1=P×[(30-Dv50)/2+2×(10-M)]
表2:实施例1-22和对比例1-4的性能测试结果
Figure PCTCN2019111331-appb-000003
Figure PCTCN2019111331-appb-000004
从表2的测试结果可以看出:实施例1-22的负极极片均满足4≤P×[(30-Dv50)/2+2×(10-M)]≤20,电池可同时兼顾优异动力学性能、长循环寿命以及较高能量密度的特点。这是由于负极膜片的孔隙率P、负极膜片单位面积的容量M以及负极活性材料的体积中位粒径Dv50之间的匹配关系良好,锂离子在负极多孔电极孔道内部液相扩散阻力、锂离子与电子在负极活性材料表面电荷交换阻力以及锂离子在负极活性材料体相内部固相扩散以 及积累阻力均较小,由此电池能同时兼顾优异动力学性能、长循环寿命以及较高能量密度的特点。
与实施例1-22相比,在对比例1-4中,负极膜片的孔隙率P、负极膜片单位面积的容量M以及负极活性材料的体积中位粒径Dv50没有合理匹配,导致P×[(30-Dv50)/2+2×(10-M)]不在所给范围内,难以满足电池优异动力学性能、长循环寿命以及较高能量密度的需求。
其中,负极膜片的孔隙率P优选控制在20%~65%之间,在上述优选范围内,电池可兼顾优异的动力学性能以及较长的循环寿命。负极膜片单位面积的容量M优选控制在0.5mAh/cm 2~7.0mAh/cm 2之间,在上述优选范围内,电池可兼顾较长的循环寿命以及较高的能量密度。负极活性材料的体积中位粒径Dv50优选控制在4μm~20μm之间,在上述优选范围内,电池可兼顾优异的动力学性能以及较高的能量密度。
但是当负极膜片的孔隙率P、负极膜片单位面积容量M、负极活性材料体积中位粒径Dv50中的一个或几个参数未能满足上述优选范围时,只要保证4≤P×[(30-Dv50)/2+2×(10-M)]≤20,结合实施例15-20,电池仍可在不牺牲能量密度的前提下具有良好的动力学性能以及循环性能。
从实施例11以及对比例3-4中可知,当电池选用不同的正、负极活性材料时,只要负极极片满足4≤P×[(30-Dv50)/2+2×(10-M)]≤20,电池仍可同时兼顾优异动力学性能、长循环寿命以及较高能量密度的特点。
进一步地,当调节负极膜片与负极集流体之间的粘接力F以及负极膜片单位面积的容量M之间的关系使其满足M/3≤F≤6M时,可以更好地提升电池动力学性能以及循环性能,同时保证电池具有较高能量密度的优势。
结合实施例21,负极膜片与负极集流体之间的粘接力F较小,负极活性材料颗粒与颗粒之间的电子接触较差、负极膜片与负极集流体之间的电子接触也较差,电子经过负极集流体到达负极膜片的传导能力较差,锂离子与电子在负极活性材料表面电荷交换阻力较大,因此与实施例8相比,实施例21对电池动力学性能以及循环性能的提升效果略差。结合实施例22,负极膜片与负极集流体之间的粘接力F过大,在这个过程中负极膜片加入了大量导电性较差的粘接剂,电池的能量密度会降低,同时电子经过负极集流体到达负极膜片的传导能力较差,锂离子与电子在负极活性材料表面电荷交换阻力较 大,因此与实施例9相比,实施例22对电池动力学性能以及循环性能的提升效果也略差。
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于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:4≤P×[(30-Dv50)/2+2×(10-M)]≤20;
    其中,
    P为负极膜片的孔隙率;
    Dv50为负极活性材料的体积中位粒径,单位为μm;
    M为负极膜片单位面积的容量,单位为mAh/cm 2
  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:6≤P×[(30-Dv50)/2+2×(10-M)]≤15;
    优选地,所述负极膜片满足:8≤P×[(30-Dv50)/2+2×(10-M)]≤12。
  3. 根据权利要求1或2所述的负极极片,其特征在于,所述负极膜片的孔隙率P为20%~65%,优选为22%~55%。
  4. 根据权利要求1或2所述的负极极片,其特征在于,所述负极活性材料的体积中位粒径Dv50为4μm~20μm,优选为4μm~16μm。
  5. 根据权利要求1或2所述的负极极片,其特征在于,所述负极膜片单位面积的容量M为0.5mAh/cm 2~7.0mAh/cm 2,优选为1.0mAh/cm 2~5.5mAh/cm 2
  6. 根据权利要求1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为1mg/cm 2~22mg/cm 2,优选为4mg/cm 2~12mg/cm 2
  7. 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0.8g/cm 3~2.0g/cm 3,优选为1.0g/cm 3~1.6g/cm 3
  8. 根据权利要求1所述的负极极片,其特征在于,
    负极膜片与负极集流体之间的粘接力F与负极膜片单位面积的容量M满足:M/3≤F≤6M;
    优选地,负极膜片与负极集流体之间的粘接力F与负极膜片单位面积的容量M满足:M/2≤F≤5M;
    其中,
    F的单位为N/m;
    M的单位为mAh/cm 2
  9. 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。
  10. 一种电池,其特征在于,包括根据权利要求1-9中任一项所述的负极极片。
PCT/CN2019/111331 2018-10-17 2019-10-15 负极极片及电池 WO2020078358A1 (zh)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19872955.0A EP3790081A4 (en) 2018-10-17 2019-10-15 NEGATIVE ELECTRODE SHEET AND BATTERY
US16/973,536 US11469418B2 (en) 2018-10-17 2019-10-15 Negative electrode sheet and battery

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201811208744.7A CN109449373B (zh) 2018-10-17 2018-10-17 负极极片及电池
CN201811208744.7 2018-10-17

Publications (1)

Publication Number Publication Date
WO2020078358A1 true WO2020078358A1 (zh) 2020-04-23

Family

ID=65546905

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2019/111331 WO2020078358A1 (zh) 2018-10-17 2019-10-15 负极极片及电池

Country Status (4)

Country Link
US (1) US11469418B2 (zh)
EP (1) EP3790081A4 (zh)
CN (1) CN109449373B (zh)
WO (1) WO2020078358A1 (zh)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109449373B (zh) * 2018-10-17 2020-09-11 宁德时代新能源科技股份有限公司 负极极片及电池
CN112909220A (zh) 2019-12-04 2021-06-04 宁德时代新能源科技股份有限公司 二次电池及含有它的装置
KR20220115812A (ko) * 2020-01-02 2022-08-18 닝더 엠프렉스 테크놀로지 리미티드 음극 및 이를 포함하는 전기 화학 디바이스
CN111337842A (zh) * 2020-02-20 2020-06-26 东莞维科电池有限公司 一种锂离子电池负极片最优压实密度的测试方法
WO2021189454A1 (zh) * 2020-03-27 2021-09-30 宁德新能源科技有限公司 一种电极组件及包含其的电化学装置和电子装置
CN113097438B (zh) * 2021-03-31 2022-08-12 宁德新能源科技有限公司 电化学装置和电子装置
CN114267862A (zh) * 2021-12-27 2022-04-01 华秦储能技术有限公司 一种全钒液流电池混合储能体系及组成的电堆
CN115172667B (zh) * 2022-09-07 2022-11-18 中创新航科技股份有限公司 一种电池负极片及其制备方法、应用其的锂离子电池
CN115632175B (zh) * 2022-11-02 2023-12-15 江苏正力新能电池技术有限公司 一种负极补锂快充极片及快充电池
CN116632170B (zh) * 2023-07-25 2023-09-26 中创新航科技集团股份有限公司 一种负极极片、包含该负极极片的二次电池及用电装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101174683A (zh) * 2006-11-01 2008-05-07 比亚迪股份有限公司 锂离子二次电池的负极以及包括该负极的锂离子二次电池
CN102610791A (zh) * 2012-02-27 2012-07-25 宁德新能源科技有限公司 一种用于插电式混合动力汽车的锂离子电池及其负极
KR20140008957A (ko) * 2012-07-13 2014-01-22 주식회사 엘지화학 접착력과 고율 특성이 향상된 음극 및 이를 포함하는 리튬 이차 전지
JP5460948B2 (ja) 2004-02-06 2014-04-02 エー123 システムズ, インコーポレイテッド 高速充放電性能を備えたリチウム二次電池
EP3232497A1 (en) 2015-01-21 2017-10-18 LG Chem, Ltd. Lithium secondary battery having improved output characteristics
CN108461842A (zh) 2018-04-09 2018-08-28 合肥国轩高科动力能源有限公司 一种提高圆柱型钛酸锂储能电芯短路通过率的方法
CN109449373A (zh) * 2018-10-17 2019-03-08 宁德时代新能源科技股份有限公司 负极极片及电池

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1688063A (zh) * 2005-04-27 2005-10-26 惠州Tcl金能电池有限公司 一种高比容量二次锂离子电池
JP2008311209A (ja) * 2007-05-17 2008-12-25 Sanyo Electric Co Ltd 非水電解質二次電池
US9065093B2 (en) * 2011-04-07 2015-06-23 Massachusetts Institute Of Technology Controlled porosity in electrodes
CN105934845B (zh) * 2014-01-24 2019-07-05 日产自动车株式会社 电器件
US10340508B2 (en) * 2014-06-16 2019-07-02 The Regents Of The University Of California Porous silicon oxide (SiO) anode enabled by a conductive polymer binder and performance enhancement by stabilized lithium metal power (SLMP)

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5460948B2 (ja) 2004-02-06 2014-04-02 エー123 システムズ, インコーポレイテッド 高速充放電性能を備えたリチウム二次電池
CN101174683A (zh) * 2006-11-01 2008-05-07 比亚迪股份有限公司 锂离子二次电池的负极以及包括该负极的锂离子二次电池
CN102610791A (zh) * 2012-02-27 2012-07-25 宁德新能源科技有限公司 一种用于插电式混合动力汽车的锂离子电池及其负极
KR20140008957A (ko) * 2012-07-13 2014-01-22 주식회사 엘지화학 접착력과 고율 특성이 향상된 음극 및 이를 포함하는 리튬 이차 전지
EP3232497A1 (en) 2015-01-21 2017-10-18 LG Chem, Ltd. Lithium secondary battery having improved output characteristics
CN108461842A (zh) 2018-04-09 2018-08-28 合肥国轩高科动力能源有限公司 一种提高圆柱型钛酸锂储能电芯短路通过率的方法
CN109449373A (zh) * 2018-10-17 2019-03-08 宁德时代新能源科技股份有限公司 负极极片及电池

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ANONYMOUS: "Solef® PVDF Aqueous Dispersions for Lithium Batteries", SOLVAY SPECIALTY POLYMERS, 1 January 2015 (2015-01-01), pages 1 - 8, XP055889708
K. AMINE, B. LUCHT, J. MULDOON: "Lithium-Ion Batteries and Beyond ", 1 January 2015, THE ELECTROCHEMICAL SOCIETY, article "Lithium-Ion Batteries and Beyond /Passage/", pages: 2pp, 49, XP055889718

Also Published As

Publication number Publication date
EP3790081A1 (en) 2021-03-10
US11469418B2 (en) 2022-10-11
US20210249656A1 (en) 2021-08-12
EP3790081A4 (en) 2021-08-18
CN109449373A (zh) 2019-03-08
CN109449373B (zh) 2020-09-11

Similar Documents

Publication Publication Date Title
CN109449446B (zh) 二次电池
CN109449373B (zh) 负极极片及电池
CN109449447B (zh) 二次电池
CN111129502B (zh) 一种负极极片以及二次电池
CN109994706B (zh) 锂离子电池
US11114659B2 (en) Negative electrode sheet and secondary battery
US11088361B2 (en) Secondary battery
WO2020135766A1 (zh) 正极活性材料、正极极片、电化学储能装置及装置
US11469409B2 (en) Negative electrode and battery
CN109509909B (zh) 二次电池
CN113328099B (zh) 一种负极极片以及二次电池
CN109273771B (zh) 二次电池
CN111384374B (zh) 负极活性材料、负极极片及电池
CN112310360A (zh) 负极活性材料及电池
CN109494348B (zh) 负极极片及二次电池
CN109841832B (zh) 正极片及电化学电池
CN109461881B (zh) 负极极片及二次电池
CN108808006B (zh) 负极极片及电池
CN109904404B (zh) 锂二次电池负极活性材料、其制备方法及含其锂二次电池
CN117996191A (zh) 二次电池以及电子设备
CN117996190A (zh) 二次电池以及电子设备
CN116722098A (zh) 一种全生命周期持续补锂的复合负极

Legal Events

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

Ref document number: 19872955

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2019872955

Country of ref document: EP

Effective date: 20201130

NENP Non-entry into the national phase

Ref country code: DE