WO2024066087A1 - 二次电池及用电装置 - Google Patents

二次电池及用电装置 Download PDF

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Publication number
WO2024066087A1
WO2024066087A1 PCT/CN2022/141187 CN2022141187W WO2024066087A1 WO 2024066087 A1 WO2024066087 A1 WO 2024066087A1 CN 2022141187 W CN2022141187 W CN 2022141187W WO 2024066087 A1 WO2024066087 A1 WO 2024066087A1
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Prior art keywords
negative electrode
secondary battery
electrolyte
present application
lithium
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PCT/CN2022/141187
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English (en)
French (fr)
Inventor
刘鹏
陈云
李嫚
吕国显
褚春波
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欣旺达动力科技股份有限公司
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Priority to US18/704,135 priority Critical patent/US20240283028A1/en
Priority to EP22960682.7A priority patent/EP4407734A1/en
Publication of WO2024066087A1 publication Critical patent/WO2024066087A1/zh

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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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • 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
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0025—Organic electrolyte
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the technical field of secondary batteries, and in particular to a secondary battery and an electrical device.
  • lithium-ion batteries have gradually taken a dominant position in the field of new energy, and the market demand has increased rapidly year by year.
  • High energy density and high voltage lithium-ion secondary batteries have attracted much attention.
  • electric vehicles need to have the characteristics of short charging time and long driving time, which requires lithium-ion secondary batteries to have the characteristics of fast charging and high capacity.
  • the present application provides a secondary battery and an electrical device, which improve the problem of difficulty in achieving both fast charging and high capacity of the secondary battery.
  • the secondary battery in the first embodiment of the present application includes a positive electrode plate, a negative electrode plate, a separator and an electrolyte.
  • the non-Faraday capacitance value of the negative electrode plate is CdlnF, satisfying 1 ⁇ Cdl ⁇ 5;
  • the electrolyte includes an additive, and the additive includes a silicon-containing compound.
  • the silicon-containing compound includes at least one of tris(trimethylsilyl)phosphate, tris(trimethylsilyl)phosphite, trimethylfluorosilane or tris(trimethylsilyl)borate.
  • the mass percentage of the silicon-containing compound is A%, based on the total mass of the electrolyte, and satisfies 0.01 ⁇ A ⁇ 5.
  • the mass percentage of the silicon-containing compound is A%, satisfying: 0.01 ⁇ 10 ⁇ Cdl ⁇ A% ⁇ 2.5.
  • the compaction density of the negative electrode sheet is PD g/cm 3 , satisfying 1.1 ⁇ PD ⁇ 1.7.
  • the OI value of the negative electrode plate is 2 ⁇ 25.
  • the surface tension of the electrolyte at room temperature is FmN/m, satisfying 20 ⁇ F ⁇ 40, and the room temperature is 20°C ⁇ 25°C.
  • the internal resistance of the secondary battery is Rm ⁇ , satisfying 0.02 ⁇ R ⁇ 0.8.
  • the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, the negative electrode active material layer includes a negative electrode active substance, and the negative electrode active substance includes one or more of artificial graphite, natural graphite, amorphous carbon, carbon nanotubes or mesophase carbon microspheres.
  • the electric device includes the above-mentioned secondary battery.
  • This application adjusts the non-Faradaic capacitance Cdl value of the negative electrode to accelerate the non-Faradaic process of the negative electrode, improve the reaction activity, and make the kinetic performance more excellent;
  • a stable passivation film can be formed at the interface between the positive and negative electrodes at the same time, reducing the impedance between the electrolyte and the interface.
  • the non-Faraday capacitance Cdl value of the negative electrode plate is within the above range and silicon-containing compounds are added to the electrolyte, the side reaction between the negative electrode plate and the electrolyte can be effectively inhibited, so that the reaction between the reactive active sites of the negative electrode plate and the electrolyte is within a suitable range, so that the battery has a fast charging capability, improves the charging window, and provides excellent power performance.
  • FIG. 1 is a fitting curve of the scan rate-current scatter diagram of the negative electrode sheet prepared in Example 1 of the present application.
  • the embodiments of the present application provide a secondary battery and an electric device.
  • the following are detailed descriptions of each. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments.
  • a list of items connected by the term "at least one of” may mean any combination of the listed items. For example, if items A and B are listed, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, the phrase " at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C.
  • Item A may include a single element or multiple elements.
  • Item B may include a single element or multiple elements.
  • Item C may include a single element or multiple elements.
  • the term "at least one of" has the same meaning as the term "at least one of”.
  • a numerical range expressed using “to” means a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • the present application provides a secondary battery, which includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.
  • the non-Faraday capacitance value of the negative electrode plate is CdlnF, which satisfies 1 ⁇ Cdl ⁇ 5; currently, in order to meet the high energy density of secondary batteries, increasing the coating weight can increase the energy density of the battery, but it will affect the long-term reliability of the battery.
  • a secondary battery such as a lithium-ion battery
  • lithium precipitation will be triggered, which may lead to the formation of lithium dendrites, which may pierce the polymer microporous diaphragm and cause an internal short circuit.
  • Lithium precipitation of the negative electrode plate consumes lithium ions in the battery, causing the battery capacity to decay rapidly and the battery's cycle performance to deteriorate. Due to the large charge and discharge current, the heat generated by the internal resistance of the battery will also increase, which may lead to thermal runaway and combustion or even explosion and other safety issues.
  • the present application accelerates the non-Faraday process of the negative electrode plate by adjusting the non-Faraday capacitance Cdl value of the negative electrode plate, with high reaction activity and better kinetic performance.
  • the negative electrode plate of the present application has high capacity and high rate performance, and is not prone to side reactions with the electrolyte, so that the lithium-ion battery has high durability and cycle stability.
  • the non-Faraday capacitance Cdl value of the negative electrode plate can be adjusted by controlling the morphology of the negative active material, the compaction density of the negative electrode plate, the OI value of the negative electrode plate, the formulation composition of the negative electrode plate, the negative electrode slurry process, etc., so as to control the number of reactive active sites of the negative electrode plate, thereby affecting the performance of the battery. As long as the above control method is used, the non-Faraday capacitance of the negative electrode plate can be within the above range.
  • Cdl can be 1, 1.5, 1.9, 2.2, 2.7, 3.1, 3.4, 3.6, 4.5, 5 or a range consisting of any two of them. In some embodiments of the present application, 1.5 ⁇ Cdl ⁇ 4.5. In some embodiments of the present application, 1.9 ⁇ Cdl ⁇ 3.6.
  • the electrochemical reaction includes a Faradaic reaction in which the oxidation state of the active substance changes and the charge moves to the inside of the active substance, and a non-Faradaic reaction in which the ions are physically adsorbed and detached on the surface of the active substance to store and release the charge.
  • a Faradaic reaction refers to a change in the oxidation state of the active substance, and the charge moves to the inside of the active substance through the double charge layer through the electrode interface;
  • a non-Faradaic reaction refers to a reaction in which the charge does not move across the electrode interface, and the charge is stored and released by the physical adsorption and detachment of the ions on the electrode surface.
  • Cdl is within the above range, the non-Faradaic process is accelerated, the reaction activity is high, and the kinetic performance is more excellent.
  • the prepared lithium-ion battery can be quickly charged at a large rate, and has excellent safety performance, and also has excellent cycle performance.
  • the non-Faradaic capacitance value of the negative electrode plate can be obtained by testing the overhang area of the negative electrode plate in the secondary battery using the non-Faradaic capacitance value test method.
  • the overhang area of the negative electrode plate refers to the part of the negative electrode plate that exceeds the positive electrode plate in length and width. It can also be obtained by testing the negative electrode plate that has not been assembled into a battery.
  • the compaction density of the negative electrode sheet is PD g/cm 3 , which satisfies 1.1 ⁇ PD ⁇ 1.7, for example, it can be 1.1, 1.2, 1.3, 1.5, 1.6, 1.7 or a range consisting of any two numbers therein. In some embodiments of the present application, 1.3 ⁇ PD ⁇ 1.6.
  • the compaction density falls within the above range, the integrity of the negative electrode active material particles is higher, the occurrence of particle breakage after rolling is reduced, the increase of side reactions during battery cycling is reduced, and the cycle life of the battery is avoided from being affected.
  • the non-Faraday capacitance value of the negative electrode sheet is 1 nF ⁇ 5nF, and the compaction density is within the above range
  • the electrical contact between the negative electrode active material particles is better, which is conducive to the migration of lithium ions, increases the consistency of the negative electrode sheet current, slows down the polarization of the battery, and also enables the gaps between the negative electrode active material particles to be within a suitable range, so that the structure of the negative electrode active material particles is in a relatively complete state, and can make the electrolyte wettability better, and improve the kinetic performance.
  • the compaction density of the negative electrode sheet changes, the physical contact between the particles in the negative electrode sheet changes, and the pores between the particles in the negative electrode sheet change, the non-Faraday capacitance of the negative electrode sheet will be affected.
  • the OI value of the negative electrode plate is 2 to 25, for example, the OI value can be 2, 4, 5, 6, 7, 10, 11, 15, 20, 25 or a range consisting of any two numbers therein. In some embodiments of the present application, the OI value of the negative electrode plate can be 4 to 20. In some embodiments of the present application, the OI value of the negative electrode plate can also be 5 to 15.
  • the OI value (C004/C110) of the negative electrode plate can be tested by XRD technology.
  • the OI value of the negative electrode plate can reflect the crystal phase index of the negative active material layer, wherein C004 is the peak intensity of the 004 characteristic diffraction peak in the X-ray diffraction spectrum of the negative active material layer, and C110 is the peak intensity of the 110 characteristic diffraction peak in the X-ray diffraction spectrum of the negative active material layer. Adjusting the OI value of the negative electrode sheet can affect the lithium ion transmission path. During the lithium insertion process, lithium ions will enter the interlayer from the end face of the graphite of the negative electrode material, and perform solid phase diffusion in the interlayer to complete the lithium insertion process.
  • the highly isotropic graphite end face will be exposed on the surface of the negative electrode sheet, shortening the migration path of lithium ions, which is conducive to the rapid migration of lithium ions and accelerating the electrochemical reaction kinetics, thereby further realizing the high-rate discharge performance of lithium ions; in addition, excellent isotropy can inhibit the expansion between graphite layers and improve the cycle performance. Therefore, when the OI value falls within the above range, it can achieve the effect of improving fast charging, reducing expansion, and improving circulation.
  • Testing the non-Faraday capacitance of the negative electrode includes the following steps:
  • non-Faraday interval cathode scanning Select the potential interval in S1 for linear scanning voltammetry (LSV) test, the scanning direction is from high potential to low potential, and the voltage-current curve is collected, where the voltage range is 2.5V ⁇ 2.6V, and the scanning speed is 0.05mV/s ⁇ 5mV/s; further, select the median U of the potential interval at a specific scanning speed V to obtain the corresponding current value;
  • LSV linear scanning voltammetry
  • the battery pack includes a positive electrode shell, a negative electrode sheet, a separator, an electrolyte, a lithium sheet, and a negative electrode shell.
  • the obtained negative electrode sheet is dried, cut into small discs, weighed, and transferred to a vacuum oven, dried at 90°C to 110°C for 7h to 9h, and then transferred to a glove box filled with Ar for half-cell assembly to obtain a buckle battery.
  • the assembly steps of the buckle battery are conventional in the art.
  • the negative electrode current collector includes, but is not limited to, metal foil, metal cylinder, metal strip, metal plate, metal film, metal mesh, stamped metal, foamed metal, etc.
  • the negative electrode current collector is metal foil.
  • the negative electrode current collector is copper foil.
  • the term "copper foil” includes copper alloy foil.
  • the negative electrode current collector is a conductive resin.
  • the conductive resin includes a film obtained by evaporating copper on a polypropylene film.
  • the negative electrode active material layer may be one or more layers, and each layer of the multilayer negative electrode active material may contain the same or different negative electrode active materials.
  • the negative electrode active material is any material that can reversibly embed and extract metal ions such as lithium ions.
  • the chargeable capacity of the negative electrode active material is greater than the discharge capacity of the positive electrode active material to prevent lithium metal from being precipitated on the negative electrode during charging.
  • the thickness of the negative electrode active material layer refers to the thickness of the negative electrode active material layer coated on a single side of the negative electrode current collector. In some embodiments, the thickness of the negative electrode active material layer is 15 ⁇ m or more. In some embodiments, the thickness of the negative electrode active material layer is 20 ⁇ m or more. In some embodiments, the thickness of the negative electrode active material layer is 30 ⁇ m or more. In some embodiments, the thickness of the negative electrode active material layer is 150 ⁇ m or less. In some embodiments, the thickness of the negative electrode active material layer is 120 ⁇ m or less. In some embodiments, the thickness of the negative electrode active material layer is 100 ⁇ m or less.
  • the thickness of the negative electrode active material layer is within the range consisting of any two of the above values.
  • the electrolyte can penetrate into the vicinity of the interface of the negative electrode current collector, thereby improving the charge and discharge characteristics of the electrochemical device at high current density; at the same time, the volume ratio of the negative electrode current collector to the negative electrode active material is within an appropriate range, which can ensure the capacity of the secondary battery.
  • the negative electrode active material layer includes a negative electrode active material, a conductive agent, a binder, an additive and a solvent.
  • the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube or graphene.
  • the negative electrode active material includes one or more of artificial graphite, natural graphite, soft carbon, hard carbon, amorphous carbon, carbon nanotubes or mesophase carbon microspheres.
  • the negative electrode active material layer includes a negative electrode binder, which can improve the bonding between the negative electrode active materials.
  • the type of the binder is not particularly limited as long as it is a material that is stable to the electrolyte or the solvent used in the electrode manufacturing.
  • the negative electrode sheet in the secondary battery of the present application can be prepared by any known method.
  • the negative electrode active material, the conductive agent, the binder, the additive and the solvent can be made into a negative electrode slurry in a certain proportion, the negative electrode slurry can be applied to the negative electrode current collector, and the negative electrode sheet can be obtained by rolling and cutting.
  • the electrolyte includes lithium salt, organic solvent and additives, and the additives include silicon-containing compounds.
  • the present application reasonably adjusts the relationship between the non-Faraday capacitance value of the negative electrode plate and the content of the additive in the electrolyte, so that the obtained lithium-ion secondary battery has the characteristics of high capacity and fast charging.
  • the secondary battery of the present application can form a stable passivation film at the interface of the positive and negative electrodes by adding an additive containing a silicon-containing compound to the electrolyte, reduce the impedance between the electrolyte and the interface, and effectively inhibit the side reaction between the positive electrode plate or the negative electrode plate and the electrolyte; when the non-Faraday capacitance value of the negative electrode plate is 1nF ⁇ 5nF and the electrolyte contains a silicon-containing compound, the silicon-containing compound has a lone pair of electrons with nucleophilicity and alkalinity, which can play a role in controlling the HF content, reducing the internal resistance of the battery and increasing the charging speed; at the same time, under the action of the electron-deficient central atom, the silicon-containing compound can form a film at the negative electrode, increase the ionic conductivity of the SEI film, accelerate the transmission of lithium ions, make the battery have fast charging capability, improve the lithium precipitation window, and provide excellent power performance.
  • the silicon-containing compound includes at least one of tris(trimethylsilyl)phosphate (TMSP), tris(trimethylsilyl)phosphite (TMSPi), trimethylfluorosilane or tris(trimethylsilyl)borate (TMSB).
  • TMSP tris(trimethylsilyl)phosphate
  • TMSPi tris(trimethylsilyl)phosphite
  • TMSB trimethylfluorosilane or tris(trimethylsilyl)borate
  • Such silicon-containing compounds can better interact with the negative electrode plate, can form a stable and dense passivation film on the surface of the negative electrode plate of the lithium-ion battery, effectively inhibit the side reaction of the electrode-electrolyte, can reduce the surface tension of the electrolyte, increase the compatibility of the electrode and electrolyte interface, improve the cycle performance of the lithium-ion battery, and improve the safety of the lithium-ion battery.
  • the mass percentage of the silicon-containing compound is A%, satisfying 0.01 ⁇ A ⁇ 5, for example, it can be 0.01, 0.1, 0.5, 0.7, 1, 1.5, 1.8, 2.2, 2.7, 3, 4, 5 or a range consisting of any two numbers therein. In some embodiments of the present application, 0.1 ⁇ A ⁇ 4. In some embodiments of the present application, 0.5 ⁇ A ⁇ 3.
  • the mass percentage of the silicon-containing compound is lower than 0.01%, the film-forming ability is insufficient, resulting in limited improvement in lithium ion performance.
  • the film When the mass percentage of the silicon-containing compound is higher than 5%, the film is too dense, resulting in a decrease in the lithium ion deintercalation rate, an increase in polarization, and a deterioration in the cycle performance of the lithium ion battery.
  • the mass percentage of the silicon-containing compound is A%, satisfying: 0.01 ⁇ 10 ⁇ Cdl ⁇ A% ⁇ 2.5, for example, it can be 0.02, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.1, 2.2 or a range consisting of any two numbers therein.
  • the surface tension of the electrolyte at room temperature is FmN/m, which satisfies 20 ⁇ F ⁇ 40, and the room temperature is 20°C ⁇ 25°C.
  • F can be 20, 25, 30, 35, 40 or a range consisting of any two numbers therein. In some embodiments of the present application, 25 ⁇ F ⁇ 35.
  • the force acting on the surface of the liquid to reduce the surface area of the liquid is called the surface tension of the liquid.
  • the degree of wetting of the electrolyte will affect the performance of the lithium-ion battery, and the improvement method includes adjusting the solvent system and using additives.
  • the surface tension of the electrolyte can accelerate the wetting effect of the pole piece, improve the distribution uniformity and dynamic balance ability of the electrolyte, increase the penetration rate, help reduce the battery impedance, improve the battery reaction kinetics, and make the lithium-ion battery have good rate performance; the electrolyte with the above surface tension makes the negative electrode coating have a good interface, which helps to improve the cycle performance of the electrochemical device. In addition, reducing the wetting time can also improve production efficiency.
  • the surface tension of the electrolyte can be tested by SY/T 5370-2018 surface and interfacial tension determination method. Test settings: total time 10.0 s, start pause 0.0 s, last frame 10% (33FPS), pipette tip size 300 ⁇ L, drop volume 6 ⁇ L.
  • 1.1 ⁇ Cdl+R ⁇ F/10 ⁇ 8 for example, it can be 1.1, 1.5, 2, 3, 5, 7, 8 or a range consisting of any two numbers therein. In some embodiments of the present application, 1.5 ⁇ Cdl+R ⁇ F/10 ⁇ 6. In some embodiments of the present application, 1.9 ⁇ Cdl+R ⁇ F/10 ⁇ 4.5.
  • the negative electrode plate has a higher electron and lithium ion transmission performance, so that the battery has a higher charging and discharging performance at a high rate, thereby making the lithium-ion battery performance have better comprehensive performance.
  • the electrolyte further comprises any organic solvent known in the prior art that can be used as a solvent for the electrolyte.
  • the organic solvent comprises a carbonate solvent, including at least two of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and polycarbonate.
  • the lithium salt includes at least one of lithium hexafluorophosphate, organic lithium borate, lithium perchlorate, and sulfonyl imide lithium salt.
  • the content of lithium salt is not particularly limited as long as it does not impair the effect of the present application.
  • the molar concentration of lithium salt can be 0.5mol/L ⁇ 2mol/L, 1mol/L ⁇ 1.8mol/L, or 1.2mol/L ⁇ 1.5mol/L, based on the total volume of the electrolyte.
  • the lithium salt concentration is within the above range, the lithium ions as charged ions will not be too few, and the viscosity can be within an appropriate range, so it is easy to ensure good conductivity.
  • the additive includes a compound containing a sulfur-oxygen double bond, such as 1,3-propane sultone, vinyl sulfate, vinyl sulfite, and the like.
  • the additive includes a cyclic carbonate containing an unsaturated double bond, such as vinylene carbonate, vinyl ethylene carbonate, and the like.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer may be one layer or multiple layers. Each layer of the multiple layers of positive electrode active material may contain the same or different positive electrode active materials.
  • the positive electrode active material is any material that can reversibly embed and extract metal ions such as lithium ions.
  • the positive electrode active material layer includes a positive electrode active material, a positive electrode conductor, a positive electrode binder and a solvent.
  • the positive electrode active material includes lithium iron phosphate (LFP) and one or more of the ternary materials.
  • LFP lithium iron phosphate
  • the positive electrode active material includes a ternary material, and the ternary material includes lithium nickel cobalt manganese oxide and/or lithium nickel cobalt aluminum oxide.
  • the content of the nickel element is greater than or equal to 0.5.
  • the content of the nickel element is less than or equal to 0.85.
  • the positive electrode active material further includes a doping element and/or a coating element.
  • the content of the positive electrode active material can be 80% to 98%, 85% to 96%, or 90% to 95%. In some embodiments, based on the weight of the positive electrode active material layer, the content of the positive electrode active material is within the range formed by any two of the above values. When the content of the positive electrode active material is within the above range, the capacity of the positive electrode active material in the positive electrode active material layer can be ensured, and the strength of the positive electrode sheet can be maintained.
  • positive electrode conductive agent there is no limitation on the type of positive electrode conductive agent, and any known conductive agent can be used.
  • positive electrode conductive agents may include, but are not limited to, natural graphite, artificial graphite, acetylene black, needle coke, carbon nanotubes, graphene and other carbon materials. The above positive electrode conductive agents may be used alone or in any combination. 3. Positive electrode binder
  • positive electrode binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of a coating method, any material may be used as long as it is soluble or dispersible in a liquid medium used in the production of the electrode.
  • positive electrode binders may include, but are not limited to, one or more of the following: resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose, etc.; rubber polymers such as styrene-butadiene rubber (SBR), nitrile rubber (NBR), fluororubber, isoprene rubber, polybutadiene rubber, ethylene-propylene rubber, etc.; thermoplastic elastomer polymers such as styrene-butadiene-styrene block copolymer or its hydride, ethylene-propylene-diene terpolymer (EPDM), styren
  • solvent used to form the positive electrode slurry there is no limitation on the type of solvent used to form the positive electrode slurry, as long as it is a solvent that can dissolve or disperse the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder.
  • solvents used to form the positive electrode slurry may include any of aqueous solvents and organic solvents.
  • aqueous media may include, but are not limited to, water and mixed media of alcohol and water.
  • organic media may include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF); amides such as N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide, etc.
  • aliphatic hydrocarbons such as hexane
  • aromatic hydrocarbons such as benzen
  • positive electrode current collector which may be any material known to be suitable for use as a positive electrode current collector.
  • positive electrode current collectors may include, but are not limited to, metal materials such as aluminum, stainless steel, nickel plating, titanium, tantalum, and carbon materials such as carbon cloth and carbon paper.
  • the positive electrode current collector is a metal material.
  • the positive electrode current collector is aluminum.
  • the form of the positive electrode current collector When the positive electrode current collector is a metal material, the form of the positive electrode current collector may include, but is not limited to, metal foil, metal cylinder, metal strip roll, metal plate, metal foil, metal plate mesh, stamped metal, foamed metal, etc.
  • the form of the positive electrode current collector may include, but is not limited to, carbon plate, carbon film, carbon cylinder, etc.
  • the positive electrode current collector is a metal foil.
  • the metal foil is mesh-shaped. There is no particular limitation on the thickness of the metal foil. In some embodiments, the thickness of the metal foil is greater than 1 ⁇ m, greater than 3 ⁇ m, or greater than 5 ⁇ m. In some embodiments, the thickness of the metal foil is less than 1 mm, less than 100 ⁇ m, or less than 50 ⁇ m. In some embodiments, the thickness of the metal foil is within a range formed by any two of the above values.
  • a separator is usually provided between the positive electrode and the negative electrode.
  • the separator may be a resin, glass fiber, inorganic substance, etc. formed by a material that is stable to the electrolyte of the present application.
  • the separator includes a porous sheet or non-woven fabric-like material with excellent liquid retention, etc.
  • materials for resin or glass fiber separators may include, but are not limited to, polyolefins, aromatic polyamides, polytetrafluoroethylene, polyether sulfone, etc.
  • the polyolefin is polyethylene or polypropylene.
  • the polyolefin is polypropylene.
  • the materials of the above-mentioned separators may be used alone or in any combination.
  • the internal resistance of the secondary battery is Rm ⁇ , satisfying 0.02 ⁇ R ⁇ 0.8, for example, it can be 0.02, 0.05, 0.1, 0.3, 0.5, 0.7, 0.8 or a range consisting of any two numbers therein. In some embodiments of the present application, 0.05 ⁇ R ⁇ 0.7. In some embodiments of the present application, 0.1 ⁇ R ⁇ 0.5.
  • the internal resistance of the secondary battery can be tested by an electrochemical workstation AC impedance test. Wherein, the disturbance voltage is 5mV, and the frequency range is 100kHz ⁇ 100mHz.
  • An embodiment of the present application further provides an electrical device, comprising the above-mentioned secondary battery pack.
  • the electrical devices of the present application include, but are not limited to, backup power supplies, motors, electric vehicles, electric motorcycles, power-assisted bicycles, bicycles, power tools, large household batteries, and the like.
  • NCM811 The positive electrode active material
  • the positive electrode conductive agent carbon black
  • the positive electrode binder polyvinylidene fluoride
  • NMP N-methylpyrrolidone
  • the negative electrode active material, conductive agent, binder and additive are mixed evenly in a mass ratio of 96.5:1.5:1.5:0.5, and then mixed with solvent deionized water to form a negative electrode slurry.
  • the negative electrode active material is artificial graphite
  • the conductive agent is carbon black
  • the binder is styrene-butadiene rubber
  • the additive is sodium carboxymethyl cellulose;
  • the negative electrode slurry is obtained by stirring under the action of a vacuum mixer, and the prepared negative electrode slurry is evenly coated on both sides of the negative electrode current collector copper foil, and after baking and drying, the negative electrode sheet is rolled and cut into pieces.
  • the baking temperature is 90°C ⁇ 110°C
  • the rolling compaction density is controlled at 1.55g/ cm3
  • the negative electrode sheet OI value is 6.5.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (EDC) were mixed in a mass ratio of 3:4:3, 0.1% of tris(trimethylsilyl) phosphate and 1% of vinylene carbonate were added, and then 1 mol/L of LiPF 6 was added and mixed evenly to prepare an electrolyte with a surface tension of 35 mN/m.
  • Step 1 disassemble the lithium-ion battery in a glove box or a dry room, obtain the negative electrode overhang area electrode, soak it in dimethyl carbonate (DMC) solution, cut it and assemble it with a metal lithium sheet into a button half-cell, or take the negative electrode electrode that has not been assembled into a battery and cut it and assemble it with a metal lithium sheet into a button half-cell;
  • Step 2 perform CV test on the button battery in the voltage range of 0.005V ⁇ 3.0V, with a scan rate of 0.1mV/s, and confirm that the non-Faraday potential range is 2.5V ⁇ 2.6V;
  • Step 3 then perform L from 2.6V to 2.5V SV test, the scanning rates were 0.1mV/s, 0.2mV/s, 0.5mV/s, 1mV/s, 2mV/s, respectively, and the median of the potential interval was 2.55V, and the corresponding current values were -7.87E-07A, -9.94E-
  • the parameters of the battery prepared in this embodiment are: the compaction density of the negative electrode sheet after rolling is 1.55g/ cm3 , and the OI value of the sheet is 6.5; 0.1% tris(trimethylsilyl)phosphate is added to the electrolyte to prepare the electrolyte, and its surface tension is 35mN/m; the non-Faraday capacitance value of the lithium ion battery is 2.22.
  • a lithium ion battery was prepared according to the method of Example 1, except for the following differences as shown in Table 1.
  • a lithium ion battery was prepared according to the method of Example 1, except for the following differences:
  • the compaction density of the negative electrode sheet after rolling is 1.05g/ cm3 , and the OI value of the sheet is 20; no additives are added to the electrolyte, and its surface tension is 45mN/m; the non-Faraday capacitance value of the lithium-ion battery is 0.8.
  • a lithium ion battery was prepared according to the method of Example 1, except for the following differences:
  • the compaction density of the negative electrode sheet after rolling is 1.3g/ cm3 , and the OI value of the sheet is 27; 5.5% tris(trimethylsilyl) phosphate is added to the electrolyte to prepare the electrolyte, and its surface tension is 15mN/m; the non-Faraday capacitance value of the lithium-ion battery is 5.3.
  • the Cdl value in Examples 1 to 20 and Comparative Examples 1 to 2 can be changed by controlling the morphology of the negative electrode active material, the compaction density of the negative electrode sheet, and the OI value of the negative electrode sheet, as long as the Cdl value can be the value of the example in this application.
  • the lithium-ion battery was left at 25°C for 30 minutes, fully charged at 5C, left for 30 minutes, fully discharged at 1C, left for 10 minutes, and after 10 cycles of charge and discharge, the lithium-ion battery was fully charged at 5C again, and stopped after standing for 10 minutes.
  • the lithium-ion battery was disassembled, the interface condition of the surface of the negative electrode was observed, and the area of the lithium-deposited part was recorded.
  • the percentage of lithium-deposited area area of lithium-deposited part/total area of negative electrode ⁇ 100%. Among them, the degree of lithium-deposited is divided into no lithium-deposited, slight lithium-deposited, moderate lithium-deposited, and severe lithium-deposited.
  • No lithium-deposited means that the area of lithium-deposited on the surface of the negative electrode is less than 3%;
  • slight lithium-deposited means that the area of lithium-deposited on the surface of the negative electrode is greater than or equal to 3% and less than 20% of the overall area;
  • moderate lithium-deposited means that the area of lithium-deposited on the surface of the negative electrode is 20% to 70% of the overall area;
  • severe lithium-deposited means that the area of lithium-deposited on the surface of the negative electrode exceeds 70% of the overall area.
  • the secondary battery was placed at 25°C for 30 min, discharged at 1C constant current, placed for 10 min, charged at 1C constant current and constant voltage, placed for 10 min, and a full charge and discharge cycle test was performed, and the capacity retention rate after 2000 cycles was recorded.
  • the surface tension test of electrolyte refers to SY/T 5370-2018 Surface and interfacial tension test method.
  • the lithium-ion battery was left at 25°C for 30 min, charged at 1C constant current and constant voltage with a cut-off current of 0.05C, and then discharged at 1C capacity for 30 min, adjusted to 50% SOC, and then an AC impedance test was performed on an electrochemical workstation, where the disturbance voltage was 5mV and the frequency range was 100kHz ⁇ 100mHz.
  • the battery cycle performance of the embodiment is significantly improved compared with the comparative example.
  • Comparative example 1 is that no silicon-containing compound is added to the electrolyte and the non-faradaic capacitance value is lower than the scope of the present application
  • comparative example 2 is that an excessive amount of silicon-containing compound is added to the electrolyte and the non-faradaic capacitance value is higher than the scope of the present application. This shows that compared with the comparative example, the embodiment adds silicon-containing compounds within the scope of the present application to the electrolyte, and the non-faradaic capacitance value is not within the scope of the present application, and the battery has better cycle performance.
  • the present application provides a secondary battery, which can be quickly charged at a large rate, has a high capacity, and has excellent cycle performance.

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Abstract

本申请公开了一种二次电池及用电装置。二次电池包括正极极片、负极极片、隔膜和电解液，负极极片的非法拉第电容值为CdlnF，满足1≤Cdl≤5；电解液包括添加剂，添加剂包括含硅化合物。本申请通过合理调节负极极片的非法拉第电容值和电解液中添加剂的含量之间的关系，所得二次电池具有高容量快充的特点。

Description

二次电池及用电装置
本申请要求于2022年09月26日提交中国专利局、申请号为202211175108.5、发明名称为“二次电池及用电装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及二次电池技术领域，具体涉及一种二次电池及用电装置。
 背景技术
目前，二次电池，例如锂离子电池在新能源领域逐渐占据了主导地位，市场需求量逐年快速递增。高能量密度和高电压的锂离子二次电池倍受关注。例如，电动汽车要具备充电时间短、续航时间长的特点，这就要求锂离子二次电池需要具有快充和高容量的特点。
因此，有必要提供一种二次电池，能够改善上述问题。
发明内容
 技术问题
本申请提供一种二次电池及用电装置，改善了二次电池快充和高容量难以兼顾的问题。
 技术解决方案
根据本申请第一实施例中的二次电池，包括正极极片、负极极片、隔膜和电解液，负极极片的非法拉第电容值为CdlnF，满足1≤Cdl≤5；电解液包括添加剂，添加剂包括含硅化合物。
可选的，在本申请的其它实施例中，含硅化合物包括三（三甲基硅烷）磷酸酯、三（三甲基硅烷）亚磷酸酯、三甲基氟硅烷或三（三甲基硅烷）硼酸酯中的至少一种。
可选的，在本申请的其它实施例中，以电解液的总质量计，含硅化合物的质量百分比为A%，满足0.01≤A≤5。
可选的，在本申请的其它实施例中，以电解液的总质量计，含硅化合物的质量百分比为A%，满足：0.01≤10×Cdl×A%≤2.5。
可选的，在本申请的其它实施例中，负极极片的压实密度为PD g/cm 3，满足1.1≤PD≤1.7。
可选的，在本申请的其它实施例中，负极极片的OI值为2~25。
可选的，在本申请的其它实施例中，电解液在室温下的表面张力为FmN/m，满足20≤F≤40，室温为20℃~25℃。
可选的，在本申请的其它实施例中，二次电池的内阻为RmΩ，满足0.02≤R≤0.8。
可选的，在本申请的其它实施例中，1.1≤Cdl+R×F/10≤8。
可选的，在本申请的其它实施例中，负极极片包括负极集流体和设置于负极集流体上的负极活性材料层，负极活性材料层包括负极活性物质，负极活性物质包括人造石墨、天然石墨、无定型碳、碳纳米管或中间相炭微球中的一种或多种。
根据本申请第二实施例中的用电装置，包括上述的二次电池。
 有益效果
根据本申请实施例的二次电池，至少具有如下技术效果：
（1）本申请通过调整负极极片非法拉第电容Cdl值，使负极极片非法拉第过程加快，反应活性提高，动力学性能更加优异；
（2）通过在电解液中添加含硅化合物添加剂，能同时在正负极界面形成稳定的钝化膜，降低电解液与界面的阻抗，当负极极片非法拉第电容Cdl值在上述范围内，且电解液中添加含硅化合物，能够有效的抑制负极极片与电解液之间的副反应，使得负极极片的反应活性位点与电解液的反应在合适的范围内，使电池具有快速充电能力，提升充电窗口，且提供优异的功率性能。
 附图说明
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是本申请实施例1所制备的负极极片的扫速-电流散点图的拟合曲线。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
本申请实施例提供一种二次电池及用电装置。以下分别进行详细说明。需说明的是，以下实施例的描述顺序不作为对实施例优选顺序的限定。
在具体实施方式及权利要求书中，由术语“中的至少一者”连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“ A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。术语“中的至少一种”具有与术语“中的至少一者”相同的含义。
本说明书中，使用“～”来显示的数值范围，表示包含以在“～”前后记载的数值分别作为最小值和最大值的范围。
在一个实施例中，本申请提供了一种二次电池，其包括正极极片、负极极片、隔膜和电解液。
I 、负极极片
负极极片包括负极集流体和设置于负极集流体上的负极活性材料层。
在本申请的一些实施例中，负极极片的非法拉第电容值为CdlnF，满足1≤Cdl≤5；目前为了满足二次电池的高能量密度，增加涂布重量可提高电池的能量密度，但是会影响电池的长期可靠性。当二次电池，例如锂离子电池，在快速充电或高倍率放电时，若锂离子不能快速嵌入、脱嵌到负极活性材料中，会引发析锂，可能会导致形成锂枝晶，可能刺穿聚合物微孔隔膜，造成内部短路。负极极片析锂会消耗电池中的锂离子，使得电池容量迅速衰减，电池的循环性能劣化。由于充放电电流大，电池的内阻所导致产生的热量也会增大，可能导致热失控而出现燃烧甚至爆炸等安全问题。本申请通过调整负极极片的非法拉第电容Cdl值，使负极极片的非法拉第过程加快，反应活性高，动力学性能更加优异。本申请的负极极片具有高容量、高倍率性能，且不易与电解液发生副反应，从而使得锂离子电池具有较高的耐久性和循环稳定性。负极极片的非法拉第电容Cdl值可以通过控制负极活性物质形貌、负极极片压实密度、负极极片OI值、负极极片配方组成、负极浆料工艺等方式调整，从而控制负极极片的反应活性位点数量，从而影响电池的性能。只要通过上述控制方式，能够使负极极片的非法拉第电容在上述范围即可。
具体的，Cdl可以为1、1.5、1.9、2.2、2.7、3.1、3.4、3.6、4.5、5或其中任意两个数组成的范围。在本申请的一些实施例中，1.5≤Cdl≤4.5。在本申请的一些实施例中，1.9≤Cdl≤3.6。电化学反应包括活性物质的氧化态发生变化、电荷移向活性物质内部的法拉第反应和离子在活性物质表面物理性的吸附、脱离来存储、释放电荷的非法拉第反应。法拉第反应是指活性物质的氧化态发生变化，电荷穿过双电荷层通过电极界面移到活性物质内部；非法拉第反应是指不发生穿过电极界面的电荷移动，通过离子在电极表面被物理性的吸附脱离，将电荷存储释放的反应。当Cdl在上述范围内非法拉第过程加快，反应活性高，动力学性能更加优异。制得的锂离子电池能在大倍率下进行快速充电，且具有优良的安全性能，同时具有优良的循环性能。
负极极片的非法拉第电容值可通过非法拉第电容值测试方法测试二次电池中负极极片overhang区域得到。负极极片overhang区域是指负极极片长度和宽度方向超出正极极片的部分。也可以通过测试未组装成电池的负极极片得到。
压实密度
在本申请的一些实施例中，负极极片的压实密度为PD g/cm 3，满足1.1≤PD≤1.7，例如可以为1.1、1.2、1.3、1.5、1.6、1.7或其中任意两个数组成的范围。在本申请的一些实施例中，1.3≤PD≤1.6。当压实密度落入上述范围内时，负极活性物质颗粒的完整性更高，减少辊压后颗粒破碎现象的出现，减少电池循环过程中副反应的增加，避免电池的循环寿命受到影响，同时，当负极极片的非法拉第电容值为1 nF~5nF，且压实密度在上述范围时，负极活性材料颗粒之间的电接触更好，有利于锂离子迁移，使负极极片电流的一致性增大，减缓电池极化，同时也能使负极活性材料颗粒之间的间隙在合适的范围内，使负极活性材料颗粒结构处于较完整状态，且能使电解液的浸润性更好，提高动力学性能。当负极极片的压实密度改变，负极极片中颗粒与颗粒之间物理接触发生改变，负极极片中颗粒与颗粒之间的孔隙发生改变，会影响负极极片的非法拉第电容。
OI 值
在本申请的一些实施例中，负极极片的OI值为2~25，例如OI值可以为2、4、5、6、7、10、11、15、20、25或其中任意两个数组成的范围。在本申请的一些实施例中，负极极片的OI值可以为4~20。在本申请的一些实施例中，负极极片的极片OI值还可以为5~15。通过XRD技术可以测试负极极片的OI值(C004/C110)。负极极片的OI值可以体现负极活性材料层的晶相指数，其中，C004为负极活性材料层的X衍射图谱中004特征衍射峰的峰强度，C110为负极活性材料层的X衍射图谱中110特征衍射峰的峰强度。调整负极极片的OI值能够影响锂离子传输路径，在嵌锂过程中，锂离子会从负极材料石墨的端面进入到层间，在层间进行固相扩散，完成嵌锂过程，所以高各向同性的石墨端面会被暴露在负极极片表面，缩短了锂离子的迁移路径，有利于锂离子的快速迁移，加快电化学反应动力学，从而进一步实现锂离子大倍率放电性能；另外，同性度优异能够抑制石墨层间的膨胀，提高循环性能。因此，当OI值落入上述范围内时，能够达到提高快充、降低膨胀、改善循环的效果。
非法拉第电容的测试方法
测试负极极片的非法拉第电容包括步骤：
S1、非法拉第电位区间确认：将负极极片组装成扣式半电池（简称扣电）进行循环伏安法（CV）测试，其中电压范围为0.005 V~3.0V，扫速为0.1 mV/s~1mV/s；
S2、非法拉第区间阴极扫描：选取S1中的电位区间进行线性扫描伏安法（LSV）测试，扫描方向从高电位到低电位，采集电压-电流曲线，其中电压范围为2.5 V~2.6V，扫速为0.05mV/s~5mV/s；进一步地，在某一特定扫速V下选取电位区间中值U，获得对应的电流值；
S3、非法拉第电容计算：根据S2采集扫速-电流散点图，拟合得到线性函数，该线性函数的斜率K即为该负极极片阴极扫描方向Cdl值。
进一步的，扣电包括正极壳、负极片、隔膜、电解液、锂片、负极壳。
进一步的，将得到的负极极片烘干裁成小圆片称量后转移至真空烘箱中，在90℃~110℃下干燥7h~9h，再转移至充满Ar的手套箱中进行半电池组装，得到扣电。扣电的组装步骤为本领域常规的组装方式。
负极集流体
在本申请的一些实施例中，负极集流体包括，但不限于，金属箔、金属圆柱、金属带卷、金属板、金属薄膜、金属板网、冲压金属、发泡金属等。在一些实施例中，负极集流体为金属箔。在一些实施例中，负极集流体为铜箔。如本文所使用，术语“铜箔”包含铜合金箔。在一些实施例中，负极集流体为导电性树脂。在一些实施例中，导电性树脂包括在聚丙烯膜上蒸镀铜而得的膜。
负极活性材料层
负极活性材料层可以是一层或多层，多层负极活性材料中的每层可以包含相同或不同的负极活性物质。负极活性物质为任何能够可逆地嵌入和脱出锂离子等金属离子的物质。在一些实施例中，负极活性物质的可充电容量大于正极活性物质的放电容量，以防止在充电期间锂金属析出在负极上。
在本申请的一些实施例中，负极活性材料层的厚度指的是涂布在负极集流体的单独一侧的负极活性材料层的厚度。在一些实施例中，负极活性材料层的厚度为15μm以上。在一些实施例中，负极活性材料层的厚度为20μm以上。在一些实施例中，负极活性材料层的厚度为30μm以上。在一些实施例中，负极活性材料层的厚度为150μm以下。在一些实施例中，负极活性材料层的厚度为120μm以下。在一些实施例中，负极活性材料层的厚度为100μm以下。在一些实施例中，负极活性材料层的厚度在由上述任意两个数值所组成的范围内。当负极活性材料层的厚度在上述范围内时，电解液可浸透到负极集流体界面附近，提高电化学装置在高电流密度下的充放电特性；同时负极集流体相对于负极活性物质的体积比在适当范围内，可确保二次电池的容量。
负极活性材料层包括负极活性物质、导电剂、粘结剂、添加剂和溶剂。
1 、导电剂
在本申请的一些实施例中，导电剂包括导电炭黑、导电石墨、碳纤维、碳纳米管或石墨烯中的一种或多种。
2 、负极活性物质
在本申请的一些实施例中，负极活性物质包括人造石墨、天然石墨、软炭、硬炭、无定型碳、碳纳米管或中间相炭微球中的一种或多种。
3 、粘结剂
负极活性材料层包括负极粘接剂，其可提高负极活性物质之间的粘结。粘结剂的种类没有特别限制，只要是对于电解液或电极制造时使用的溶剂稳定的材料即可。
负极极片的制备
本申请的二次电池中的负极极片可使用任何已知方法制备。例如，可以将负极活性物质、导电剂、粘结剂、添加剂与溶剂按一定比例制成负极浆料，将负极浆料涂覆于负极集流体，进行辊压裁片得到负极极片。
II 、电解液
电解液包括锂盐、有机溶剂和添加剂，添加剂包括含硅化合物。本申请通过合理调节负极极片的非法拉第电容值和电解液中添加剂的含量之间的关系，使所得锂离子二次电池具有高容量快充的特点。
添加剂
本申请的二次电池通过在电解液中添加含有含硅化合物的添加剂，能同时在正负极界面形成稳定的钝化膜，降低电解液与界面的阻抗，有效的抑制正极极片或负极极片与电解液之间的副反应；当负极极片的非法拉第电容值为1nF~5nF且电解液含有含硅化合物时，含硅化合物具有亲核性和碱性的孤对电子，能够起到控制HF含量的作用，降低电池内阻，提高充电速度；同时，在缺电子中心原子的作用下，含硅化合物可在负极成膜，增加SEI膜的离子电导率，加快锂离子的传输，使得电池具有快速充电能力，提升析锂窗口，且提供优异的功率性能。本申请的电解液与本申请的负极极片共同应用到锂离子电池中后，不仅能够提高锂离子电池的循环性能，而且能够提高锂离子电池的倍率性能。
在本申请的一些实施例中，含硅化合物包括三（三甲基硅烷）磷酸酯（TMSP）、三（三甲基硅烷）亚磷酸酯（TMSPi）、三甲基氟硅烷或三（三甲基硅烷）硼酸酯（TMSB）中的至少一种。该类含硅化合物能够更好的与负极极片作用，能在锂离子电池负极片表面形成性质稳定且具有一定致密性的钝化膜，有效的抑制电极-电解液的副反应，可以降低电解液表面张力，增加电极与电解液界面的相容性，改善锂离子电池的循环性能，提高锂离子电池的安全性。
在本申请的一些实施例中，以电解液的总质量计，含硅化合物的质量百分比为A%，满足0.01≤A≤5，例如可以为0.01、0.1、0.5、0.7、1、1.5、1.8、2.2、2.7、3、4、5或其中任意两个数组成的范围。在本申请的一些实施例中，0.1≤A≤4。在本申请的一些实施例中，0.5≤A≤3。当含硅化合物的质量百分比低于0.01%时，成膜能力不足，导致对锂离子性能的改善有限，当含硅化合物的质量百分比高于5%时，成膜过于致密导致锂离子脱嵌速度降低，极化现象增加，锂离子电池的循环性能恶化。
在本申请的一些实施例中，以电解液的总质量计，含硅化合物的质量百分比为A%，满足：0.01≤10×Cdl×A%≤2.5，例如可以为0.02、0.1、0.2、0.3、0.4、0.5、0.6、0.8、1.1、2.2或其中任意两个数组成的范围。在本申请的一些实施例中，0.02≤10×Cdl×A%≤2.2。在本申请的一些实施例中，0.1≤10×Cdl×A%≤1.1。
表面张力
在本申请的一些实施例中，电解液在室温下的表面张力为FmN/m，满足20≤F≤40，室温为20℃~25℃。例如F可以为20、25、30、35、40或其中任意两个数组成的范围。在本申请的一些实施例中，25≤F≤35。作用于液体表面，使液体表面积缩小的力，称为液体的表面张力。电解液的浸润程度会影响锂离子电池的性能，改善方法包括调整溶剂体系和使用添加剂。当电解液的表面张力落入上述范围内时，能够加速极片的浸润效果，提高电解液的分布均匀性和动态平衡能力，提高渗透速率，有助于降低电池阻抗，提高电池反应动力学，使锂离子电池具有良好的倍率性能；如上所述表面张力的电解液使负极涂层具有良好的界面，有助于改善电化学装置的循环性能。另外，减少浸润时间，还能够提升生产效率。电解液表面张力可通过SY/T 5370-2018 表面及界面张力测定方法测试。测试设置：总时间10.0 s，起始暂停0.0 s，最后一帧10%（33FPS），吸液头尺寸300μL，滴液体积6μL。
在本申请的一些实施例中，1.1≤Cdl+R×F/10≤8，例如可以为1.1、1.5、2、3、5、7、8或其中任意两个数组成的范围。在本申请的一些实施例中，1.5≤Cdl+R×F/10≤6。在本申请的一些实施例中，1.9≤Cdl+R×F/10≤4.5。当负极极片的非法拉第电容值、二次电池的内阻及电解液的表面张力满足该数值范围时，负极极片具有较高的电子及锂离子的传输性能，实现电池在高倍率下具有较高的充电和放电性能，进而使锂离子电池性能具有更优异的综合性能。
有机溶剂
在本申请的一些实施例中，电解液进一步包含现有技术中已知的任何可作为电解液的溶剂的有机溶剂。在一些实施例中，有机溶剂包括碳酸酯类溶剂，包括碳酸乙烯酯、碳酸丙烯酯、碳酸二甲酯、碳酸二乙酯、碳酸甲乙酯、聚碳酸酯中的至少两种。
锂盐
在本申请的一些实施例中，锂盐包括六氟磷酸锂、有机硼酸锂、高氯酸锂、磺酰亚胺类锂盐中的至少一种。
锂盐的含量没有特别限制，只要不损害本申请的效果即可。在本申请的一些实施例中，以电解液的总体积计，锂盐的摩尔浓度可以为0.5mol/L~2mol/L，也可以为1mol/L~1.8mol/L，还可以为1.2mol/L~1.5mol/L。当锂盐浓度在上述范围内时，作为带电离子的锂离子不会过少，并且可以使粘度处于适当的范围，因而容易确保良好的电导率。
添加剂
在本申请的一些实施例中，添加剂包含含硫氧双键的化合物，例如1,3-丙烷磺内酯、硫酸乙烯酯、亚硫酸乙烯酯等。
在本申请的一些实施例中，添加剂包含含不饱和双键的环状碳酸酯，例如碳酸亚乙烯酯、乙烯基碳酸亚乙酯等。
III 、正极极片
正极极片包括正极集流体和设置于正极集流体上的正极活性材料层。
正极活性材料层
正极活性材料层可以是一层或多层。多层正极活性材料中的每层可以包含相同或不同的正极活性物质。正极活性物质为任何能够可逆地嵌入和脱出锂离子等金属离子的物质。
正极活性材料层包括正极活性物质、正极导电剂、正极粘结剂和溶剂。
1 、正极活性物质
正极活性物质的种类没有特别限制，只要是能够以电化学方式吸收和释放金属离子(例如，锂离子)即可。在本申请的一些实施例中，正极活性物质包含磷酸铁锂（LFP）以及三元材料中的一种或几种。
在本申请的一些实施例中，正极活性物质包含三元材料，所述三元材料包含锂镍钴锰氧化物和/或锂镍钴铝氧化物。
在本申请的一些实施例中，以所述锂镍钴锰氧化物中镍元素、钴元素和锰元素的摩尔量为1计，所述镍元素的含量大于或等于0.5。
在本申请的一些实施例中，以所述锂镍钴锰氧化物中镍元素、钴元素和锰元素的摩尔量为1计，所述镍元素的含量小于或等于0.85。
在本申请的一些实施例中，所述正极活性材料中还包含掺杂元素和/或包覆元素。
在本申请的一些实施例中，基于正极活性材料层的重量，正极活性物质的含量可以为80%~98%，也可以为85%~96%，还可以为90%~95%。在一些实施例中，基于正极活性材料层的重量，正极活性物质的含量在上述任意两个数值所组成的范围内。当正极活性物质的含量在上述范围内时，可以确保正极活性物质层中的正极活性物质的容量，同时可以保持正极极片的强度。
2 、正极导电剂
正极导电剂的种类没有限制，可以使用任何已知的导电剂。正极导电剂的实例可包括，但不限于，天然石墨、人造石墨、乙炔黑、针状焦、碳纳米管、石墨烯等碳材料。上述正极导电剂可单独使用或任意组合使用。 3 、正极粘结剂
正极活性材料层的制造中使用的正极粘结剂的种类没有特别限制，在涂布法的情况下，只要是在电极制造时使用的液体介质中可溶解或分散的材料即可。正极粘合剂的实例可包括，但不限于，以下中的一种或多种：聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯、聚甲基丙烯酸甲酯、聚酰亚胺、芳香族聚酰胺、纤维素、硝酸纤维素等树脂系高分子；丁苯橡胶(SBR)、丁腈橡胶(NBR)、氟橡胶、异戊二烯橡胶、聚丁橡胶、乙烯-丙烯橡胶等橡胶状高分子；苯乙烯·丁二烯·苯乙烯嵌段共聚物或其氢化物、乙烯·丙烯·二烯三元共聚物(EPDM)、苯乙烯·乙烯· 丁二烯·乙烯共聚物、苯乙烯·异戊二烯·苯乙烯嵌段共聚物或其氢化物等热塑性弹性体状高分子；间规-1,2-聚丁二烯、聚乙酸乙烯酯、乙烯·乙酸乙烯酯共聚物、丙烯·α-烯烃共聚物等软质树脂状高分子；聚偏氟乙烯(PVDF)、聚四氟乙烯、氟化聚偏二氟乙烯、聚四氟乙烯·乙烯共聚物等氟系高分子；具有碱金属离子(特别是锂离子)的离子传导性的高分子组合物等。上述正极粘结剂可单独使用或任意组合使用。
4 、溶剂
用于形成正极浆料的溶剂的种类没有限制，只要是能够溶解或分散正极活性物质、正极导电剂、正极粘结剂的溶剂即可。用于形成正极浆料的溶剂的实例可包括水系溶剂和有机系溶剂中的任一种。水系介质的实例可包括，但不限于，水和醇与水的混合介质等。有机系介质的实例可包括，但不限于，己烷等脂肪族烃类；苯、甲苯、二甲苯、甲基萘等芳香族烃类；喹啉、吡啶等杂环化合物；丙酮、甲基乙基酮、环己酮等酮类；乙酸甲酯、丙烯酸甲酯等酯类；二亚乙基三胺、N ,N-二甲氨基丙胺等胺类；二乙醚、环氧丙烷、四氢呋喃(THF)等醚类；N-甲基吡咯烷酮(NMP)、二甲基甲酰胺、二甲基乙酰胺等酰胺类；六甲基磷酰胺、二甲基亚砜等非质子性极性溶剂等。
正极集流体
正极集流体的种类没有特别限制，其可为任何已知适于用作正极集流体的材质。正极集流体的实例可包括，但不限于，铝、不锈钢、镍镀层、钛、钽等金属材料；碳布、碳纸等碳材料。在一些实施例中，正极集流体为金属材料。在一些实施例中，正极集流体为铝。正极集流体的形式没有特别限制。当正极集流体为金属材料时，正极集流体的形式可包括，但不限于，金属箔、金属圆柱、金属带卷、金属板、金属箔、金属板网、冲压金属、发泡金属等。当正极集流体为碳材料时，正极集流体的形式可包括，但不限于，碳板、碳薄膜、碳圆柱等。在一些实施例中，正极集流体为金属箔。在一些实施例中，所述金属箔为网状。金属箔的厚度没有特别限制。在一些实施例中，金属箔的厚度为大于1μm、大于3μm或大于5μm。在一些实施例中，金属箔的厚度为小于1mm、小于100μm或小于50μm。在一些实施例中，金属箔的厚度在上述任意两个数值所组成的范围内。
IV 、隔膜
为了防止短路，在正极与负极之间通常设置有隔膜。对隔膜的材料及形状没有特别限制，只要不显著损害本申请的效果即可。隔膜可为由对本申请的电解液稳定的材料所形成的树脂、玻璃纤维、无机物等。在一些实施例中，隔膜包括保液性优异的多孔性片状或无纺布状形态的物质等。树脂或玻璃纤维隔膜的材料的实例可包括，但不限于，聚烯烃、芳香族聚酰胺、聚四氟乙烯、聚醚砜等。在一些实施例中，所述聚烯烃为聚乙烯或聚丙烯。在一些实施例中，所述聚烯烃为聚丙烯。上述隔膜的材料可以单独使用或任意组合使用。
二次电池的内阻
在本申请的一些实施例中，二次电池的内阻为RmΩ，满足0.02≤R≤0.8，例如可以为0.02、0.05、0.1、0.3、0.5、0.7、0.8或其中任意两个数组成的范围。在本申请的一些实施例中，0.05≤R≤0.7。在本申请的一些实施例中，0.1≤R≤0.5。二次电池的内阻可通过电化学工作站交流阻抗测试。其中，扰动电压：5mV, 频率范围：100kHz~100mHz。
V 、应用
本申请的实施例还提供一种用电装置，包括上述的二次电池包。
本申请的用电装置为，但不限于备用电源、电机、电动汽车、电动摩托车、助力自行车、自行车、电动工具、家庭用大型蓄电池等。
下面结合具体实施例进行说明。
实施例1、
本实施例提供电池的制备方法包括如下步骤：
1）正极极片制备：将正极活性物质（NCM811）、正极导电剂（炭黑）、正极粘结剂（聚偏氟乙烯）按照质量比96：2：2进行混合，之后与溶剂混合制成正极浆料，溶剂为N-甲基吡咯烷酮（NMP）；将制得的正极浆料均匀地涂覆在正极集流体铝箔的两侧，然后在120℃下烘干、辊压、分切得到正极极片。
2）负极极片的制备：将负极活性物质、导电剂、粘结剂、添加剂按照质量比96.5：1.5：1.5：0.5混合均匀，之后与溶剂去离子水混合制成负极浆料，负极活性物质为人造石墨，导电剂为炭黑，粘结剂为丁苯橡胶，添加剂为羧甲基纤维素钠；在真空搅拌机作用下搅拌获得负极浆料，将制备好的负极浆料均匀涂覆在负极集流体铜箔的两侧，经烘烤干燥后进行辊压裁片得到负极极片，烘烤温度为90℃~110℃，辊压压实密度控制在1.55g/cm 3，负极极片OI值为6.5。通过控制负极极片中负极活性物质的形貌、搅拌工艺、辊压条件等方法，只要能实现负极极片的非法拉第电容值为表1所示值即可。
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（EDC）按照质量比3:4:3混合，加入0.1%的三（三甲基硅烷）磷酸酯，1%的碳酸亚乙烯酯，然后加入1mol/L的LiPF 6混合均匀，配制成电解液，其表面张力为35mN/m。
4）锂离子电池的制备：采用上述步骤制备出的负极极片、正极极片经过干燥后，与隔膜一起卷绕成电芯，将制备好的电芯放入外壳中，所述隔膜采用PP膜；经过注液、化成定容制得锂离子电池。
5）非法拉第电容值测试：步骤1，将锂离子电池在手套箱内或干燥房中进行拆解，得到负极overhang区域极片，用碳酸二甲酯（DMC）溶液浸泡，裁切后与金属锂片组装成扣式半电池，或取未组装成电池的负极极片裁切后与金属锂片组装成扣式半电池；步骤2，将扣电在电压范围0.005V~3.0V进行CV测试，扫速为0.1mV/s，确认非法拉第电位区间为2.5V~2.6V；步骤3，然后从2.6V到2.5V进行LSV测试，扫描速率分别为0.1mV/s，0.2mV/s，0.5mV/s，1mV/s，2mV/s，选取电位区间中值2.55V，获得对应的电流值-7.87E-07A，-9.94E-07A，-1.80E-06A，-3.03E-06A，-4.99E-06A；步骤4，绘制扫速-电流散点图，拟合得到一条线性函数，如图1所示，该线性函数的斜率-2.22E-06即为该负极极片阴极扫描方向Cdl为2.22nF。
本实施例制备的电池的参数为：负极极片辊压后的压实密度为1.55g/cm 3，极片OI值为6.5；电解液中加入0.1%的三（三甲基硅烷）磷酸酯配制成电解液，其表面张力为35mN/m；锂离子电池的非法拉第电容值为2.22。
实施例2~实施例20
依照实施例1的方法制备锂离子电池，除以下不同之处如表1所示。
对比例1、
依照实施例1的方法制备锂离子电池，除以下不同之处：
负极极片辊压后的压实密度为1.05g/cm 3，极片OI值为20；电解液中不添加任何添加剂，其表面张力为45mN/m；锂离子电池的非法拉第电容值为0.8。
对比例2、
依照实施例1的方法制备锂离子电池，除以下不同之处：
负极极片辊压后的压实密度为1.3g/cm 3，极片OI值为27；电解液中加入5.5%的三（三甲基硅烷）磷酸酯配制成电解液，其表面张力为15mN/m；锂离子电池的非法拉第电容值为5.3。
实施例1~实施例20和对比例1~对比例2中Cdl值可以通过控制负极活性物质形貌、负极极片压实密度、负极极片OI值来改变，只要能够使Cdl值为本申请示例的值即可。
对实施例1~实施例20和对比例1~对比例2所得到的电池进行动力学性能测试，测试方法包括：
将锂离子电池在25℃静置30min，以5C满充，静置30min、1C满放，静置10min，冲放电循环10次后，再将锂离子电池以5C满充，静置10min后停止。将锂离子电池拆解，观察负极极片表面的界面状况，记录析锂的部分的面积。析锂面积的百分比=析锂部分面积/负极极片总面积×100%。其中，析锂的程度分为不析锂、轻微析锂、中度析锂以及严重析锂。不析锂表示负极极片表面的析锂的区域为小于3％；轻微析锂表示负极极片表面的析锂的区域大于或等于3%且小于整体区域的20％，中度析锂表示负极极片表面的析锂的区域为整体区域的20％～ 70％，严重析锂表示负极极片表面的析锂区域超过整体区域的70％。
循环性能测试方法
将二次电池在25℃静置30min，在1C恒流放电，静置10min，1C恒流恒压充电，静置10min，进行满充满放循环测试，记录循环2000圈的容量保持率。
电解液表面张力测试方法
电解液表面张力测试参照SY/T 5370-2018 表面及界面张力测定方法。
电池内阻测试方法
将锂离子电池在25℃静置30min，1C恒流恒压充电，截止电流0.05C，再以1C容量放电30min，调至50％SOC，然后在电化学工作站进行交流阻抗测试，其中，扰动电压：5mV，频率范围：100kHz~100mHz。
测试结果如下表所示：
表1
由表中结果可知，对比例1为电解液中不添加含硅化合物并且非法拉第电容值低于本申请的范围，对比例2为电解液中添加过量的含硅化合物并且非法拉第电容值高于本申请的范围，说明实施例相比于对比例，在电解液中添加本申请范围内的含硅化合物，且非法拉第电容值在本申请范围内，电池动力学性能较佳。
实施例的电池循环性能相比对比例显著提升，对比例1为电解液中不添加含硅化合物并且非法拉第电容值低于本申请的范围，对比例2为电解液中添加过量的含硅化合物并且非法拉第电容值高于本申请的范围，说明实施例相比于对比例，在电解液中添加本申请范围内的含硅化合物，且非法拉第电容值在本申请范围内，电池具有更优的循环性能。
本申请提供一种二次电池，二次电池能在大倍率下进行快速充电，且二次电池具有高容量，同时具有优良的循环性能。
以上对本申请所提供的一种二次电池及用电装置进行详细介绍，本文中应用了具体个例对本申请的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本申请的方法及其核心思想；同时，对于本领域的技术人员，依据本申请的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本申请的限制。

Claims (11)

  1. 一种二次电池，其特征在于，包括正极极片、负极极片、隔膜和电解液，所述负极极片的非法拉第电容值为CdlnF，满足1≤Cdl≤5；所述电解液包括添加剂，所述添加剂包括含硅化合物。
  2. 根据权利要求1所述的二次电池，其特征在于，所述含硅化合物包括三（三甲基硅烷）磷酸酯、三（三甲基硅烷）亚磷酸酯、三甲基氟硅烷或三（三甲基硅烷）硼酸酯中的至少一种。
  3. 根据权利要求1~2中任一项所述的二次电池，其特征在于，以所述电解液的总质量计，所述含硅化合物的质量百分比为A%，满足0.01≤A≤5。
  4. 根据权利要求1~3中任一项所述的二次电池，其特征在于，以所述电解液的总质量计，所述含硅化合物的质量百分比为A%，满足：0.01≤10×Cdl×A%≤2.5。
  5. 根据权利要求1~4中任一项所述的二次电池，其特征在于，所述负极极片的压实密度为PD g/cm 3，满足1.1≤PD≤1.7。
  6. 根据权利要求1~5中任一项所述的二次电池，其特征在于，所述负极极片的OI值为2~25。
  7. 根据权利要求1~6中任一项所述的二次电池，其特征在于，所述电解液在室温下的表面张力为FmN/m，满足20≤F≤40，所述室温为20℃~25℃。
  8. 根据权利要求1~7中任一项所述的二次电池，其特征在于，所述二次电池的内阻为RmΩ，满足0.02≤R≤0.8。
  9. 根据权利要求1~8中任一项所述的二次电池，其特征在于，所述电解液在室温下的表面张力为FmN/m，所述二次电池的内阻为RmΩ，满足1.1≤Cdl+R×F/10≤8。
  10. 根据权利要求1~9中任一项所述的二次电池，其特征在于，所述负极极片包括负极集流体和设置于所述负极集流体上的负极活性材料层，所述负极活性材料层包括负极活性物质，所述负极活性物质包括人造石墨、天然石墨、无定型碳、碳纳米管或中间相炭微球中的一种或多种。
  11. 一种用电装置，其特征在于，包括如权利要求1~10中任一项所述的二次电池。
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CN110690501A (zh) * 2019-11-15 2020-01-14 欣旺达电动汽车电池有限公司 电解液和电化学装置
CN115004418A (zh) * 2020-07-31 2022-09-02 宁德时代新能源科技股份有限公司 二次电池、其制备方法及含有该二次电池的电池模块、电池包和装置
CN114938689A (zh) * 2021-11-18 2022-08-23 宁德新能源科技有限公司 电化学装置及电子装置
CN115472896A (zh) * 2022-09-26 2022-12-13 欣旺达电动汽车电池有限公司 二次电池及用电装置

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