WO2024087225A1 - 一种电池单体、电池及用电装置 - Google Patents

一种电池单体、电池及用电装置 Download PDF

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Publication number
WO2024087225A1
WO2024087225A1 PCT/CN2022/128425 CN2022128425W WO2024087225A1 WO 2024087225 A1 WO2024087225 A1 WO 2024087225A1 CN 2022128425 W CN2022128425 W CN 2022128425W WO 2024087225 A1 WO2024087225 A1 WO 2024087225A1
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Prior art keywords
positive electrode
battery cell
battery
electrode sheet
negative electrode
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PCT/CN2022/128425
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English (en)
French (fr)
Inventor
牛从酥
李晓伟
刘晓梅
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宁德时代新能源科技股份有限公司
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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 CN202280013656.XA priority Critical patent/CN116888795A/zh
Priority to PCT/CN2022/128425 priority patent/WO2024087225A1/zh
Publication of WO2024087225A1 publication Critical patent/WO2024087225A1/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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of battery technology, and in particular to a battery cell, a battery and an electrical device.
  • the emerging high-energy-density battery has obvious advantages such as high energy density and low production cost, and is a secondary battery that can be recycled.
  • the fast charging performance of high-energy-density batteries is poor, which may affect the application of high-energy-density batteries.
  • the present application provides a battery cell, a battery and an electrical device, which have good fast charging performance.
  • the present application provides a battery cell, comprising: a positive electrode sheet and an electrolyte.
  • the coating mass of the positive active material layer on one side of the positive electrode sheet is 410mg/1540.25mm 2 to 550mg/1540.25mm 2 , and the film resistance of the positive electrode sheet is ⁇ 1 ⁇ .
  • the conductivity of the electrolyte is ⁇ 14mS/cm.
  • the battery cell of the present application has a thick coated pole piece.
  • the conductivity of the positive pole piece affects the DC resistance of the battery cell.
  • the lower the membrane resistance of the positive pole piece the higher its conductivity, which is beneficial to reducing the solid phase ohmic resistance of the battery cell.
  • the conductivity of the electrolyte affects the liquid phase ohmic impedance in the ohmic impedance and the concentration polarization in the diffusion impedance.
  • the greater the conductivity of the electrolyte the more conducive it is to reducing the liquid phase ohmic impedance of the battery and to alleviate the concentration polarization to a certain extent.
  • the membrane resistance of the positive pole piece is reduced and the conductivity of the electrolyte is increased, and the battery cell can achieve fast charging under thick coating.
  • the film resistance of the positive electrode sheet is ⁇ 0.8 ⁇
  • the conductivity of the electrolyte is ⁇ 16mS/cm.
  • the film resistance of the positive electrode sheet is ⁇ 0.8 ⁇
  • the conductivity of the electrolyte is ⁇ 16mS/cm
  • at least a battery cell having a coating mass of 410mg/ 1540.25mm2 to 470mg/ 1540.25mm2 of the positive electrode active material layer on a single side of the positive electrode sheet can be fast charged within 30min to 10% to 80% SOC.
  • the film resistance of the positive electrode sheet is ⁇ 0.5 ⁇
  • the conductivity of the electrolyte is ⁇ 18mS/cm.
  • the film resistance of the positive electrode sheet is ⁇ 0.5 ⁇
  • the conductivity of the electrolyte is ⁇ 18mS/cm
  • at least a battery cell having a coating mass of 410mg/ 1540.25mm2 to 550mg/ 1540.25mm2 of the positive electrode active material layer on a single side of the positive electrode sheet can be fast charged within 30min to 10% to 80% SOC.
  • the powder resistance of the positive active material of the positive electrode sheet is ⁇ 30 ⁇ /cm.
  • the powder resistance of the positive active material affects the film resistance of the positive electrode sheet.
  • the film resistance of the positive electrode sheet is ⁇ 1 ⁇ .
  • the positive electrode active material includes a carbon-coated lithium iron phosphate material.
  • the positive electrode active material affects the powder resistance of the positive electrode active material, and the powder resistance of the carbon-coated lithium iron phosphate material is ⁇ 30 ⁇ /cm.
  • the content of the positive active material of the positive electrode sheet is ⁇ 96wt%.
  • the content of the positive active material of the positive electrode sheet affects the energy density of the battery cell.
  • the content of the positive active material of the positive electrode sheet is ⁇ 96wt%, and the coating mass of the positive active material layer on one side of the positive electrode sheet is 410mg/ 1540.25mm2-550mg / 1540.25mm2 , the energy density of the battery cell is relatively high.
  • the compaction density of the positive electrode sheet is ⁇ 2.55 g/m 3 .
  • the compaction density of the positive electrode sheet affects the energy density of the battery cell.
  • the energy density of the battery cell is relatively high.
  • the porosity of the positive electrode sheet is 20% to 35%.
  • the porosity of the positive electrode sheet corresponds to the compaction density.
  • the battery cell has a higher energy density.
  • the thickness of the positive current collector of the positive electrode sheet is 10 ⁇ m to 20 ⁇ m.
  • the thickness of the positive current collector of the positive electrode sheet is greater than 20 ⁇ m, the energy density of the battery cell is low; when the thickness of the positive current collector of the positive electrode sheet is less than 10 ⁇ m, the positive current collector is prone to cracking; when the thickness of the positive current collector of the positive electrode sheet is 10 ⁇ m to 20 ⁇ m, it can ensure that the battery cell has a higher energy density and the positive current collector has better mechanical properties.
  • the battery cell further comprises a negative electrode sheet
  • the coating mass of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell is ⁇ 180 mg/1540.25 mm 2
  • the film resistance of the negative electrode sheet is ⁇ 0.01 ⁇ .
  • the coating mass of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell corresponds to the coating mass of the positive electrode active material layer on one side of the positive electrode sheet.
  • the compaction density of the negative electrode sheet is ⁇ 1.67 g/m 3 .
  • the compaction density of the negative electrode sheet affects the energy density of the battery cell.
  • the energy density of the battery cell is higher.
  • the porosity of the negative electrode sheet is 25% to 40%.
  • the porosity of the negative electrode sheet affects the tortuosity of the negative electrode sheet. Increasing the porosity of the negative electrode sheet is beneficial to increasing the tortuosity of the negative electrode sheet and reducing the lithium ion transmission path, thereby improving the fast charging performance of the battery.
  • the thickness of the negative electrode collector of the negative electrode plate is 4 ⁇ m to 8 ⁇ m.
  • the thickness of the negative electrode collector of the negative electrode plate is greater than 8 ⁇ m, the energy density of the battery cell is low; when the thickness of the negative electrode collector of the negative electrode plate is less than 4 ⁇ m, the negative electrode collector is prone to cracking; when the thickness of the negative electrode collector of the negative electrode plate is 4 ⁇ m to 8 ⁇ m, it can ensure that the battery cell has a higher energy density and the negative electrode collector has better mechanical properties.
  • the battery cell further includes a separator, and the thickness of the separator is ⁇ 7 ⁇ m.
  • the thickness of the separator affects the energy density of the battery cell. When the thickness of the separator is ⁇ 7 ⁇ m, the energy density of the battery cell is higher.
  • the present application provides a battery, which includes the battery cell of the above embodiment.
  • the present application provides an electrical device, which includes the battery of the above embodiment, and the battery is used to provide electrical energy.
  • FIG1 is a schematic diagram of the structure of a vehicle provided in some embodiments of the present application.
  • FIG2 is an exploded view of a battery provided in some embodiments of the present application.
  • FIG. 3 is a schematic diagram of the exploded structure of a first type of battery cell provided in some embodiments of the present application.
  • the term "and/or" is only a description of the association relationship of associated objects, indicating that three relationships may exist.
  • a and/or B can represent: A exists alone, A and B exist at the same time, and B exists alone.
  • the character "/" in this article generally indicates that the associated objects before and after are in an "or" relationship.
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • Power batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the continuous expansion of the application field of power batteries, the market demand is also constantly expanding.
  • the inventors have noticed that the fast charging performance of high specific energy batteries is relatively poor, which may affect the application of high specific energy batteries.
  • the inventors have found that as the coating mass of the active material layer of the pole piece of the battery cell increases, the thickness of the pole piece increases, which will lead to an increase in the polarization of the battery cell, and then lead to a deterioration in the fast charging of the battery cell.
  • the source of polarization of the battery cell under thick coating is decomposed, which is mainly composed of ohmic impedance and diffusion impedance. Among them, the liquid phase ohmic impedance in the ohmic impedance and the concentration polarization in the diffusion impedance are both affected by the electrolyte to a certain extent.
  • the battery liquid phase ohmic impedance and the concentration polarization under fast charging increase.
  • the solid phase ohmic impedance in the ohmic impedance can be defined by the membrane resistance (conductivity) of the positive electrode sheet, and the conductivity of the positive electrode sheet affects the DC resistance.
  • the battery cell of the present application has a thick-coated electrode sheet.
  • the conductivity of the positive electrode sheet affects the DC resistance of the battery cell.
  • the conductivity of the electrolyte affects the liquid-phase ohmic impedance in the ohmic impedance and the concentration polarization in the diffusion impedance.
  • the battery mentioned in the embodiments of the present application refers to a single physical module including multiple battery cells to provide higher voltage and capacity.
  • the battery generally includes a battery box for packaging multiple battery cells, and the battery box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery cells.
  • Each battery cell is a secondary battery; it can be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.
  • the battery cell can be cylindrical, flat, rectangular or in other shapes. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells.
  • the battery cell includes an electrode assembly and an electrolyte.
  • the electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator.
  • the battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work.
  • the positive electrode sheet includes a positive electrode collector and a positive electrode active material layer.
  • the positive electrode active material layer is coated on the surface of the positive electrode collector.
  • the positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer.
  • the positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab.
  • the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc.
  • the negative electrode sheet includes a negative electrode collector and a negative electrode active material layer.
  • the negative electrode active material layer is coated on the surface of the negative electrode collector.
  • the negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer.
  • the negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab.
  • the material of the negative electrode collector can be copper, and the negative electrode active material can be carbon or silicon, etc.
  • the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together.
  • the material of the isolation film can be polypropylene (PP) or polyethylene (PE).
  • the electrode assembly can be a winding structure or a laminated structure, and the embodiments of the present application are not limited thereto.
  • the battery cell also includes a current collecting component, which is used to electrically connect the tabs and electrode terminals of the battery cell to transmit electrical energy from the electrode assembly to the electrode terminals and then to the outside of the battery cell through the electrode terminals; multiple battery cells are electrically connected through a current collecting component to achieve series, parallel or mixed connection of multiple battery cells.
  • a current collecting component which is used to electrically connect the tabs and electrode terminals of the battery cell to transmit electrical energy from the electrode assembly to the electrode terminals and then to the outside of the battery cell through the electrode terminals; multiple battery cells are electrically connected through a current collecting component to achieve series, parallel or mixed connection of multiple battery cells.
  • the battery also includes a sampling terminal and a battery management system.
  • the sampling terminal is connected to the busbar to collect information about the battery cells, such as voltage or temperature, etc.
  • the sampling terminal transmits the collected information about the battery cells to the battery management system.
  • the battery management system detects that the information about the battery cells exceeds the normal range, it will limit the output power of the battery to achieve safety protection.
  • the electrical devices used by the batteries described in the embodiments of the present application can be in various forms, for example, mobile phones, portable devices, laptops, battery vehicles, electric cars, ships, spacecraft, electric toys and electric tools, etc.
  • spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.
  • Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.
  • Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers.
  • the battery cells and batteries described in the embodiments of the present application are not limited to the electrical devices described above, but can also be applied to all electrical devices using battery cells and batteries. However, for the sake of simplicity, the following embodiments are described using electric vehicles as examples.
  • the vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle.
  • the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.
  • a battery 100 is arranged inside the vehicle 1000, and the battery 100 can be arranged at the bottom, head or tail of the vehicle 1000.
  • the battery 100 can be used to power the vehicle 1000.
  • the battery 100 can be used as an operating power source for the vehicle 1000.
  • the vehicle 1000 may also include a controller 200 and a motor 300.
  • the controller 200 is used to control the battery 100 to power the motor 300, for example, for the starting, navigation and driving power requirements of the vehicle 1000.
  • the battery 100 can not only serve as an operating power source for the vehicle 1000, but also serve as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.
  • FIG. 2 is an exploded view of a battery provided in some embodiments of the present application.
  • the battery 100 includes a box body 10 and a battery cell 20, and the battery cell 20 is contained in the box body 10.
  • the box body 10 is used to provide a storage space for the battery cell 20, and the box body 10 can adopt a variety of structures.
  • the box body 10 may include a first part 11 and a second part 12, and the first part 11 and the second part 12 cover each other, and the first part 11 and the second part 12 jointly define a storage space for accommodating the battery cell 20.
  • the second part 12 may be a hollow structure with one end open, and the first part 11 may be a plate-like structure, and the first part 11 covers the open side of the second part 12, so that the first part 11 and the second part 12 jointly define a storage space; the first part 11 and the second part 12 may also be hollow structures with one side open, and the open side of the first part 11 covers the open side of the second part 12.
  • the box body 10 formed by the first part 11 and the second part 12 may be in a variety of shapes, such as a cylinder, a cuboid, etc.
  • the battery 100 there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a mixed connection.
  • the mixed connection means that the multiple battery cells 20 are both connected in series and in parallel.
  • the multiple battery cells 20 may be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 20 is accommodated in the box 10; of course, the battery 100 may also be a battery module formed by connecting multiple battery cells 20 in series, in parallel, or in a mixed connection, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 10.
  • the battery 100 may also include other structures, for example, the battery 100 may also include a busbar component for realizing electrical connection between the multiple battery cells 20.
  • Each battery cell 20 is a secondary battery, which may be a lithium-ion battery, a lithium-sulfur battery, a sodium-ion battery or a magnesium-ion battery, but is not limited thereto.
  • the battery cell 20 may be cylindrical, flat, rectangular or in other shapes.
  • FIG3 is a schematic diagram of the exploded structure of the first battery cell provided in some embodiments of the present application.
  • the battery cell 20 refers to the smallest unit that constitutes the battery. As shown in FIG3, the battery cell 20 includes an end cap 21, a housing 22, an electrode assembly 23 and other functional components.
  • the end cap 21 refers to a component that covers the opening of the shell 22 to isolate the internal environment of the battery cell 20 from the external environment.
  • the shape of the end cap 21 can be adapted to the shape of the shell 22 to match the shell 22.
  • the end cap 21 can be made of a material with a certain hardness and strength (such as aluminum alloy), so that the end cap 21 is not easily deformed when squeezed and collided, so that the battery cell 20 can have a higher structural strength and the safety performance can also be improved.
  • Functional components such as electrode terminals can be provided on the end cap 21. The electrode terminal can be used to electrically connect to the electrode assembly 23 for outputting or inputting electrical energy of the battery cell 20.
  • the end cap 21 can also be provided with a pressure relief mechanism for releasing the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold.
  • the material of the end cap 21 can also be a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiments of the present application do not impose special restrictions on this.
  • an insulating member may be provided inside the end cap 21, and the insulating member may be used to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit.
  • the insulating member may be plastic, rubber, or the like.
  • the shell 22 is a component used to cooperate with the end cap 21 to form the internal environment of the battery cell 20, wherein the formed internal environment can be used to accommodate the electrode assembly 23, the electrolyte and other components.
  • the shell 22 and the end cap 21 can be independent components, and an opening can be set on the shell 22, and the internal environment of the battery cell 20 is formed by covering the opening with the end cap 21 at the opening.
  • the end cap 21 and the shell 22 can also be integrated. Specifically, the end cap 21 and the shell 22 can form a common connection surface before other components are put into the shell, and when the interior of the shell 22 needs to be encapsulated, the end cap 21 covers the shell 22.
  • the shell 22 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 22 can be determined according to the specific shape and size of the electrode assembly 23.
  • the material of the shell 22 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and the embodiment of the present application does not impose any special restrictions on this.
  • the electrode assembly 23 is a component in the battery cell 20 where electrochemical reactions occur.
  • One or more electrode assemblies 23 may be included in the housing 22.
  • the electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets.
  • the parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab.
  • the positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs connect the electrode terminals to form a current loop.
  • the present application provides a battery cell, including: a positive electrode sheet and an electrolyte.
  • the coating mass of the positive active material layer on one side of the positive electrode sheet is 410mg/1540.25mm 2 to 550mg/1540.25mm 2 , and the film resistance of the positive electrode sheet is ⁇ 1 ⁇ .
  • the conductivity of the electrolyte is ⁇ 14mS/cm.
  • the coating quality of the positive electrode active material layer on one side of the positive electrode sheet can be understood as the quality of the positive electrode active material layer formed after coating the positive electrode active slurry on one side of the positive electrode collector and drying it, including the positive electrode active material, conductive agent and binder.
  • the coating mass of the positive electrode active material layer on one side of the positive electrode sheet can be 410mg/ 1540.25mm2 , 420mg/ 1540.25mm2 , 430mg/1540.25mm2 , 440mg/ 1540.25mm2 , 450mg / 1540.25mm2 , 460mg/ 1540.25mm2 , 470mg/1540.25mm2, 480mg/1540.25mm2 , 490mg/1540.25mm2 , 500mg/1540.25mm2, 510mg/1540.25mm2, 520mg/ 1540.25mm2 , 530mg/ 1540.25mm2 , 540mg/1540.25mm 2 or 550mg/1540.25mm 2 .
  • the coating mass of the positive electrode active material layer on one side of the positive electrode sheet is ⁇ 450 mg/1540.25 mm 2 .
  • the coating mass of the positive electrode active material layer on one side of the positive electrode sheet is ⁇ 500 mg/1540.25 mm 2 .
  • the diaphragm resistance of the positive electrode sheet is tested using a test method known in the art.
  • the present application embodiment provides a test method for the diaphragm resistance of the positive electrode sheet:
  • test method Take a 4cm*25cm area sample along the longitudinal direction of the positive electrode, turn on the two-probe diaphragm resistance tester, select the single-point mode, input the test area of the terminal as 154.02mm2, the number of parallel samples as 20, the pressure as 0.4t, the time interval as 15s, place the tested electrode in the middle of the probe, first click the run button on the software and then push the reversing valve downward, and automatically collect a data after 15s.
  • the test method is the same as above, until the group is changed after testing 20 points.
  • the film resistance of the positive electrode sheet can be 0.02 ⁇ , 0.05 ⁇ , 0.08, 0.1 ⁇ , 0.2 ⁇ , 0.3 ⁇ , 0.4 ⁇ , 0.5 ⁇ , 0.6 ⁇ , 0.7 ⁇ , 0.8 ⁇ , 0.9 ⁇ or 1 ⁇ .
  • the conductivity of the electrolyte is measured using a test method known in the art.
  • the present application provides a method for measuring the conductivity of the electrolyte:
  • sample bottle Use a dry, clean, corrosion-resistant sample bottle to take a sample of about 100 ml of electrolyte, seal it in a constant temperature water bath at 25°C ⁇ 0.5°C, and shake it from time to time to ensure uniform heating.
  • sample temperature is constant, replace the sample bottle cap with a rubber stopper with an electrode.
  • the temperature is within the range of 25°C ⁇ 0.5°C, read the data on the conductivity meter, which is the conductivity of the sample being tested.
  • the conductivity of the electrolyte may be 14 mS/cm, 15 mS/cm, 16 mS/cm, 17 mS/cm, 18 mS/cm, 19 mS/cm, or 20 mS/cm.
  • the conductivity of the electrolyte is 14 mS/cm ⁇ 30 mS/cm.
  • the battery cell of the present application has a thick coated pole piece.
  • the conductivity of the positive pole piece affects the DC resistance of the battery cell.
  • the lower the membrane resistance of the positive pole piece the higher its conductivity, which is beneficial to reducing the solid phase ohmic resistance of the battery cell.
  • the conductivity of the electrolyte affects the liquid phase ohmic impedance in the ohmic impedance and the concentration polarization in the diffusion impedance.
  • the greater the conductivity of the electrolyte the more beneficial it is to reduce the liquid phase ohmic impedance of the battery and alleviate the concentration polarization to a certain extent.
  • the membrane resistance of the positive pole piece is reduced and the conductivity of the electrolyte is increased, and the battery cell can achieve fast charging under thick coating.
  • the electrolyte solution comprises an electrolyte, an organic solvent and a film-forming additive.
  • the electrolyte is LiPF 6 , and the concentration of the electrolyte in the electrolyte solution is 0.8 mol/L to 1.3 mol/L.
  • Organic solvents include ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate.
  • the membrane resistance of the positive electrode sheet is ⁇ 0.8 ⁇
  • the conductivity of the electrolyte is ⁇ 16mS/cm.
  • the film resistance of the positive electrode sheet is ⁇ 0.8 ⁇ and the conductivity of the electrolyte is ⁇ 16mS/cm
  • at least a battery cell with a coating mass of 410mg/ 1540.25mm2 to 470mg/ 1540.25mm2 of positive active material layer on a single side of the positive electrode sheet can be fast charged to 10% to 80% SOC within 30min.
  • the membrane resistance of the positive electrode sheet is ⁇ 0.5 ⁇ , and the conductivity of the electrolyte is ⁇ 18mS/cm.
  • At least a battery cell with a coating mass of 410mg/ 1540.25mm2 to 550mg/ 1540.25mm2 of positive active material layer on a single side of the positive electrode sheet can be fast charged to 10% to 80% SOC within 30min.
  • the powder resistance of the positive active material of the positive electrode plate is ⁇ 30 ⁇ /cm.
  • the powder resistance of the positive active material of the positive electrode sheet can be 5 ⁇ /cm, 8 ⁇ /cm, 10 ⁇ /cm, 12 ⁇ /cm, 15 ⁇ /cm, 18 ⁇ /cm, 20 ⁇ /cm, 22 ⁇ /cm, 25 ⁇ /cm, 28 ⁇ /cm or 30 ⁇ /cm.
  • the powder resistance of the positive electrode active material affects the diaphragm resistance of the positive electrode sheet.
  • the powder resistance of the positive electrode active material of the positive electrode sheet is ⁇ 30 ⁇ /cm
  • the diaphragm resistance of the positive electrode sheet is ⁇ 1 ⁇ .
  • the positive electrode active material includes a carbon-coated lithium iron phosphate material.
  • the structural formula of the lithium iron phosphate material is LiM a Fe 1-a PO 4 , wherein M is selected from any one or more of Cu, Mn, Cr, Zn, Pb, Ca, Co, Ni, Sr, Nb and Ti, and 0 ⁇ a ⁇ 1.
  • the mass fraction of carbon element in the carbon-coated lithium iron phosphate material is 0.1wt% to 5wt%.
  • the positive electrode active material affects the powder resistance of the positive electrode active material.
  • the powder resistance of the carbon-coated lithium iron phosphate material is ⁇ 30 ⁇ /cm.
  • the content of the positive electrode active material in the positive electrode plate is ⁇ 96 wt %.
  • the content of the positive active material of the positive electrode sheet may be 96 wt %, 96.5 wt %, 97 wt %, 97.5 wt %, 98 wt % or 98.5 wt %.
  • the content of the positive electrode active material in the positive electrode plate is 96 wt % to 98.5 wt %.
  • the content of positive active material in the positive electrode sheet affects the energy density of the battery cell.
  • the content of positive active material in the positive electrode sheet is ⁇ 96wt%, and the coating mass of the positive active material layer on one side of the positive electrode sheet is 410mg/ 1540.25mm2-550mg / 1540.25mm2 , the energy density of the battery cell is relatively high.
  • the positive electrode active material layer of the positive electrode sheet includes 96 wt% to 98.5 wt% of positive electrode active material, 0 to 1 wt% of conductive agent, 1 wt% to 3 wt% of binder and 0 to 1 wt% of dispersant.
  • the conductive agent includes conductive carbon black SP and/or carbon nanotubes CNT;
  • the binder includes polyvinylidene difluoride (PVDF).
  • the compaction density of the positive electrode sheet is ⁇ 2.55 g/m 3 .
  • the compaction density of the positive electrode sheet may be 2.55 g/m 3 , 2.6 g/m 3 , 2.65 g/m 3 , 2.7 g/m 3 or 2.75 g/m 3 .
  • the compaction density of the positive electrode sheet is ⁇ 2.6 g/m 3 .
  • the compaction density of the positive electrode sheet affects the energy density of the battery cell.
  • the compaction density of the positive electrode sheet is ⁇ 2.55g/m 3 and the coating mass of the positive active material layer on one side of the positive electrode sheet is 410mg/1540.25mm 2 to 550mg/1540.25mm 2 , the energy density of the battery cell is relatively high.
  • the porosity of the positive electrode sheet is 20% to 35%.
  • the porosity of the positive electrode sheet can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34% or 35%.
  • the porosity of the positive electrode sheet is 22% to 30%.
  • the porosity of the positive electrode sheet corresponds to the compaction density.
  • the porosity of the positive electrode sheet is 20% to 35%, the battery cell has a higher energy density.
  • the thickness of the positive electrode collector of the positive electrode sheet is 10 ⁇ m to 20 ⁇ m.
  • the thickness of the positive current collector of the positive electrode sheet may be 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, 16 ⁇ m, 17 ⁇ m, 18 ⁇ m, 19 ⁇ m or 20 ⁇ m.
  • the thickness of the positive current collector of the positive electrode sheet is greater than 20 ⁇ m, the energy density of the battery cell is low; when the thickness of the positive current collector of the positive electrode sheet is less than 10 ⁇ m, the positive current collector is prone to cracking; when the thickness of the positive current collector of the positive electrode sheet is between 10 ⁇ m and 20 ⁇ m, it can ensure that the battery cell has a higher energy density and that the positive current collector has better mechanical properties.
  • the battery cell further includes a negative electrode plate
  • the coating mass of the negative active material layer on one side of the negative electrode plate of the battery cell is ⁇ 180 mg/1540.25 mm 2
  • the film resistance of the negative electrode plate is ⁇ 0.01 ⁇ .
  • the coating mass of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell can be 180mg/ 1540.25mm2 , 185mg/ 1540.25mm2 , 190mg/ 1540.25mm2 , 195mg/ 1540.25mm2 , 200mg/ 1540.25mm2 , 205mg / 1540.25mm2 , 210mg/1540.25mm2 , 215mg/1540.25mm2, 220mg/1540.25mm2, 225mg/1540.25mm2, 230mg/ 1540.25mm2 , 235mg/1540.25mm2, 240mg/1540.25mm2 2 or 245mg/ 1540.25mm2 .
  • the coating mass of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell is ⁇ 190 mg/1540.25 mm 2 .
  • the coating mass of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell is ⁇ 200 mg/1540.25 mm 2 .
  • the diaphragm resistance of the negative electrode sheet is tested using a test method known in the art.
  • the present application provides a method for testing the diaphragm resistance of the negative electrode sheet:
  • test method Take a 4cm*25cm area sample along the longitudinal direction of the negative electrode, turn on the two-probe diaphragm resistance tester, select the single-point mode, input the test area of the terminal as 154.02mm2, the number of parallel samples as 20, the pressure as 0.4t, the time interval as 15s, place the tested electrode in the middle of the probe, first click the run button on the software and then push the reversing valve downward, and automatically collect a data after 15s.
  • the test method is the same as above, until a group is changed after testing 20 points.
  • the sheet resistance of the negative electrode plate may be 0.005 ⁇ , 0.006 ⁇ , 0.007 ⁇ , 0.008 ⁇ , 0.009 ⁇ or 0.01 ⁇ .
  • the coating quality of the negative electrode active material layer on one side of the negative electrode sheet of the battery cell corresponds to the coating quality of the positive electrode active material layer on one side of the positive electrode sheet.
  • the content of negative electrode active material in the negative electrode plate is ⁇ 96wt%.
  • the content of the negative electrode active material in the negative electrode plate is 96 wt % to 98 wt %.
  • the negative electrode active material layer of the negative electrode sheet includes 96 wt% to 98 wt% of negative electrode active material, 0.5 wt% to 2 wt% of conductive agent and 2 wt% to 4 wt% of binder.
  • the negative electrode active material includes graphite or silicon-carbon material
  • the conductive agent includes conductive carbon black SP and/or carbon nanotubes CNT
  • the binder includes 0.5wt% to 1.5wt% of sodium carboxymethylcellulose (CMC-Na) and 1wt% to 3wt% of polymerized styrene butadiene rubber (SBR).
  • the negative electrode plate adopts multi-layer coating
  • the negative electrode active material close to the negative electrode current collector adopts high-pressure dense graphite
  • the negative electrode active material far from the negative electrode current collector adopts fast-charging graphite
  • the compaction density of the negative electrode sheet is ⁇ 1.67 g/m 3 .
  • the compaction density of the negative electrode sheet may be 1.67 g/m 3 , 1.7 g/m 3 , 1.75 g/m 3 , 1.8 g/m 3 , 1.85 g/m 3 , 1.9 g/m 3 , 1.95 g/m 3 or 2 g/m 3 .
  • the compaction density of the negative electrode sheet is ⁇ 1.75 g/m 3 .
  • the compaction density of the negative electrode sheet is ⁇ 1.8 g/m 3 .
  • the compaction density of the negative electrode sheet affects the energy density of the battery cell.
  • the compaction density of the negative electrode sheet is ⁇ 1.67 g/m 3 and the coating mass of the negative active material layer on one side of the negative electrode sheet is ⁇ 180 mg/1540.25 mm 2 , the energy density of the battery cell is relatively high.
  • the porosity of the negative electrode sheet is 25% to 40%.
  • the porosity of the negative electrode sheet can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%.
  • the porosity of the negative electrode sheet is 27% to 35%.
  • the porosity of the negative electrode sheet is 30% to 35%.
  • the porosity of the negative electrode sheet affects the tortuosity of the negative electrode sheet. Increasing the porosity of the negative electrode sheet is beneficial to increasing the tortuosity of the negative electrode sheet and reducing the lithium ion transmission path, thereby improving the fast charging performance of the battery.
  • adding a pore former to the negative active slurry for preparing the negative active material layer can increase the porosity of the negative electrode sheet. For every 3 wt % pore former added to the negative active slurry, the porosity of the negative electrode sheet can increase by 0.5% to 1%. In order to ensure the bonding force of the negative active material, the amount of the pore former added to the negative active slurry does not exceed 25 wt %. The pore former volatilizes after the negative electrode sheet is cold pressed.
  • the thickness of the negative electrode collector of the negative electrode sheet is 4 ⁇ m to 8 ⁇ m.
  • the thickness of the negative current collector of the negative electrode sheet may be 4 ⁇ m, 5 ⁇ m, 6 ⁇ m, 7 ⁇ m or 8 ⁇ m.
  • the thickness of the negative electrode collector of the negative electrode plate is greater than 8 ⁇ m, the energy density of the battery cell is low; when the thickness of the negative electrode collector of the negative electrode plate is less than 4 ⁇ m, the negative electrode collector is prone to cracking; when the thickness of the negative electrode collector of the negative electrode plate is between 4 ⁇ m and 8 ⁇ m, it can ensure that the battery cell has a higher energy density and that the negative electrode collector has better mechanical properties.
  • the battery cell further includes a separation film, and the thickness of the separation film is ⁇ 7 ⁇ m.
  • the thickness of the isolation film may be 1 ⁇ m, 2 ⁇ m, 3 ⁇ m, 4 ⁇ m, 5 ⁇ m, 6 ⁇ m or 7 ⁇ m.
  • the thickness of the separator affects the energy density of the battery cell.
  • the thickness of the separator is ⁇ 7 ⁇ m, the energy density of the battery cell is higher.
  • the isolation film includes a base film, and the base film is made of polypropylene or polyethylene.
  • the isolation film includes a base film and a functional layer, and the functional layer includes any one or more of a fireproof coating, a high electrolyte wettability coating and a lithium ion conductive coating.
  • the fireproof coating includes any one or more of alumina, zirconium oxide, titanium dioxide and magnesium oxide.
  • the high electrolyte wettability coating includes any one or more of polyethylene, polypropylene, polytetrafluoroethylene and styrene-butadiene rubber.
  • the lithium ion conductive coating includes lithium lanthanum titanium oxide and/or lithium lanthanum zirconium oxide.
  • the battery cell of the present application is further described in detail below in conjunction with the embodiments.
  • the prepared positive electrode sheets and negative electrode sheets are die-cut and slit, and then wound into electrode assemblies.
  • the isolation film includes a 5 ⁇ m polyethylene base film, and the base film surface has a 15 ⁇ m Al2O3 coating. Then, hot pressing is performed to compact the battery cell, and then the film is coated, the pole ears are welded, the adapter is fixed, and the top cover of the shell is welded to form a dry battery cell. After baking to remove moisture, the electrolyte is injected. After the injection, the battery cell is charged at a constant current of 0.1C to a specified cut-off voltage to complete the formation process, the sealing pins of the injection port are welded, and then it is replayed once at a constant current of 0.33C to complete the capacity process. Finally, the blue film is wrapped to obtain a battery cell.
  • test method of the energy density of the battery cell is as follows:
  • Battery volume energy density battery discharge capacity * discharge platform voltage / battery volume.
  • Battery discharge capacity is the capacity of the battery when it is charged to 3.65V at 1/3C at 25°C and then discharged to 2.0V.
  • the discharge platform voltage is the potential when the electrochemical reaction reaches equilibrium, which can be automatically extracted by general testing equipment.
  • the battery volume uses the drainage method, which is to place the battery in pure water and drain the volume of water.
  • the battery capacity test equipment is a battery tester.
  • the test method for the 10% to 80% SOC fast charge time of a battery cell is as follows:
  • the stacked three-electrode test method takes out the positive and negative pole pieces of the hard shell battery cell and soaks and cleans them with DMC solvent for more than 72 hours. After the electrolyte solvent, lithium salt and additives are completely leached, the pole pieces are dried in a vacuum oven, and then the positive and negative pole pieces are assembled into a stacked three-electrode battery cell, in which the copper wire is used as the reference electrode. Then the stacked three-electrode battery cell is tested at 25°C for the lithium deposition charging rate at each SOC of the stacked battery cell. The maximum charging rate ends when the reference electrode potential drops to 0mV, and the maximum charging rate at this SOC is recorded.
  • the maximum charging rate at each 5% SOC is tested, such as 5% SOC, 10% SOC, 15% SOC to 100% SOC.
  • the continuous charging time at 10% to 80% SOC is calculated as the fast charging time.
  • Example 1 when the membrane resistance of the positive electrode sheet is 1 ⁇ and the conductivity of the electrolyte is 14mS/cm, a battery cell with a coating mass of 410mg/ 1540.25mm2 of the positive electrode active material layer on a single side of the positive electrode sheet can achieve 10% to 80% SOC@ ⁇ 30min fast charging.
  • a battery cell with a coating mass of 410mg/1540.25mm2 to 470mg/ 1540.25mm2 of the positive electrode active material layer on a single side of the positive electrode sheet can achieve 10% to 80% SOC@ ⁇ 30min fast charging, and the shortest can reach 20min.
  • a battery cell with a coating mass of 410mg/1540.25mm2 to 550mg/ 1540.25mm2 of the positive electrode active material layer on a single side of the positive electrode sheet can achieve 10% to 80% SOC@ ⁇ 30min fast charging, and the shortest can reach 15min.
  • Example 9 By comparing Example 9 with Example 1, it can be seen that the membrane resistance of the positive electrode plate is reduced to 0.8 ⁇ , the conductivity of the electrolyte remains unchanged at 14mS/cm, and the fast charging time of the battery cell is shortened to 28min.
  • Example 10 By comparing Example 10 with Example 1, it can be seen that by increasing the conductivity of the electrolyte to 16 mS/cm, the membrane resistance of the positive electrode sheet remains unchanged at 1 ⁇ , and the fast charging time of the battery cell is shortened to 25 min.
  • Example 11 By comparing Example 11 with Example 1, it can be seen that the membrane resistance of the positive electrode plate is reduced to 0.8 ⁇ , the conductivity of the electrolyte is increased to 18mS/cm, and the fast charging time of the battery cell is shortened to 20min.
  • Example 12 From the comparison between Example 12 and Example 1, it can be seen that by reducing the porosity of the negative electrode plate by 25%, the fast charging time of the battery cell is extended to 32 minutes.
  • Example 13 From the comparison between Example 13 and Example 1, it can be seen that by increasing the porosity of the negative electrode plate by 40%, the fast charging time of the battery cell is shortened to 28 minutes.

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Abstract

一种电池单体(20)、电池(100)及用电装置(1000)，电池单体(20)包括正极极片和电解液。正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2-550mg/1540.25mm 2，正极极片的膜片电阻≤1Ω，电解液的电导率≥14 mS/cm。电池单体(20)的正极极片的膜片电阻越低，越有利于降低电池单体(20)的固相欧姆电阻；电解液的电导率越大，越有利于降低电池单体(20)的液相欧姆电阻，并在一定程度上缓解浓差极化。同时降低正极极片的膜片电阻以及提高电解液的电导率，能够实现电池单体(20)在厚涂布下的快充。

Description

一种电池单体、电池及用电装置 技术领域
本申请涉及电池技术领域，具体而言，涉及一种电池单体、电池及用电装置。
背景技术
近年来，随着军用、民用储能系统的不断更新升级，人们对电池的能量密度提出了更高的要求。
新兴的高比能电池具有高能量密度、生产成本低等明显优势，是一种能循环利用的二次电池。但是，高比能电池的快充性能较差，这可能会影响到高比能电池的应用。
发明内容
鉴于上述问题，本申请提供一种电池单体、电池及用电装置，其具有较好的快充性能。
第一方面，本申请提供一种电池单体，其包括：正极极片和电解液。正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，正极极片的膜片电阻≤1Ω。电解液的电导率≥14mS/cm。
本申请实施例的技术方案中，本申请的电池单体具有厚涂布极片，正极极片的导电性影响电池单体的直流电阻，正极极片的膜片电阻越低，其具有越高的导电性，有利于降低电池单体的固相欧姆电阻。电解液的电导率影响欧姆阻抗中液相欧姆阻抗和扩散阻抗中浓差极化，电解液的电导率越大，有利于降低电池液相欧姆阻抗，并在一定程度上缓解浓差极化。同时降低正极极片的膜片电阻以及提高电解液的电导率，电池单体能够实现厚涂布下的快充。
在一些实施例中，正极极片的膜片电阻≤0.8Ω，电解液的电导率≥16mS/cm。当正极极片的膜片电阻≤0.8Ω，且电解液的电导率≥16mS/cm，至少可以实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～470mg/1540.25mm 2的电池单体10％～80％SOC在30min内的快充。
在一些实施例中，正极极片的膜片电阻≤0.5Ω，电解液的电导率≥18mS/cm。当正极极片的膜片电阻≤0.5Ω，且电解液的电导率≥18mS/cm，至少可以实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2的电池单体10％～80％SOC在30min内的快充。
在一些实施例中，正极极片的正极活性物质的粉末电阻≤30Ω/cm。正极活性物质的粉末电阻影响正极极片的膜片电阻，当正极极片的正极活性物质的粉末电阻≤30Ω/cm时，正极极片的膜片电阻≤1Ω。
在一些实施例中，正极活性物质包括碳包覆的磷酸铁锂材料。正极活性物质影响到正极活性物质的粉末电阻，碳包覆的磷酸铁锂材料的粉末电阻≤30Ω/cm。
在一些实施例中，正极极片的正极活性物质的含量≥96wt％。正极极片的正极活性物质的含量影响到电池单体的能量密度，当正极极片的正极活性物质的含量≥96wt％时，且正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，电池单体的能量密度较高。
在一些实施例中，正极极片的压实密度≥2.55g/m 3。正极极片的压实密度影响到电池单体的能量密度，当正极极片的压实密度≥2.55g/m 3时，且正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，电池单体的能量密度较高。
在一些实施例中，正极极片的孔隙率为20％～35％。正极极片的孔隙率和压实密度对应，当正极极片的孔隙率为20％～35％时，电池单体具有较高的能量密度。
在一些实施例中，正极极片的正极集流体的厚度为10μm～20μm。当正极极片的正极集流体的厚度＞20μm时，电池单体的能量密度较低；当正极极片的正极集流体的厚度＜10μm时，正极集流体容易开裂；当正极极片的正极集流体的厚度为10μm～20μm时，既能保证电池单体具有较高的能量密度，还能保证正极集流体具有较好的机械性能。
在一些实施例中，电池单体还包括负极极片，电池单体的负极极片单面的负极活性物质层的涂布质量≥180mg/1540.25mm 2，负极极片的膜片电阻≤0.01Ω。电池单体的负极极片单面的负极活性物质层的涂布质量和正极极片单面的正极活性物质层的涂布质量相对应。
在一些实施例中，负极极片的压实密度≥1.67g/m 3。负极极片的压实密度影响到电池单体的能量密度，当负极极片的压实密度≥1.67g/m 3时，且负极极片单面的负极活性物质层的涂布质量≥180mg/1540.25mm 2，电池单体的能量密度较高。
在一些实施例中，负极极片的孔隙率为25％～40％。负极极片的孔隙率影响到负极极片的曲折度，提高负极极片的孔隙率有利于提高负极极片的曲折度，以及降低锂离子传输路径，从而提高电池的快充性能。
在一些实施例中，负极极片的负极集流体的厚度为4μm～8μm。当负极极片的负极集流体的厚度＞8μm时，电池单体的能量密度较低；当负极极片的负极集流体的厚度＜4μm时，负极集流体容易开裂；当负极极片的负极集流体的厚度为4μm～8μm时，既能保证电池单体具有较高的能量密度，还能保证负极集流体具有较好的机械性能。
在一些实施例中，电池单体还包括隔离膜，隔离膜的厚度≤7μm。隔离膜的厚度影响到电池单体的能量密度，当隔离膜的厚度≤7μm时，电池单体的能量密度较高。
第二方面，本申请提供了一种电池，其包括上述实施例的电池单体。
第三方面，本申请提供了一种用电装置，其包括上述实施例的电池，电池用于提供电能。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读对下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在全部附图中，用相同的附图标号表示相同的部件。在附图中：
图1为本申请一些实施例提供的车辆的结构示意图；
图2为本申请一些实施例提供的电池的爆炸图；
图3为本申请一些实施例提供的第一种电池单体的分解结构示意图。
具体实施方式中的附图标号如下：
1000-车辆；
100-电池；200-控制器；300-马达；
10-箱体；11-第一部分；12-第二部分；
20-电池单体；21-端盖；22-壳体；23-电极组件。
具体实施方式
下面将结合附图对本申请技术方案的实施例进行详细的描述。以下实施例仅用于更加清楚地说明本申请的技术方案，因此只作为示例，而不能以此来限制本申请的保护范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员 通常理解的含义相同；本文中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请；本申请的说明书和权利要求书及上述附图说明中的术语“包括”和“具有”以及它们的任何变形，意图在于覆盖不排他的包含。
在本申请实施例的描述中，技术术语“第一”“第二”等仅用于区别不同对象，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量、特定顺序或主次关系。在本申请实施例的描述中，“多个”的含义是两个以上，除非另有明确具体的限定。
在本文中提及“实施例”意味着，结合实施例描述的特定特征、结构或特性可以包含在本申请的至少一个实施例中。在说明书中的各个位置出现该短语并不一定均是指相同的实施例，也不是与其它实施例互斥的独立的或备选的实施例。本领域技术人员显式地和隐式地理解的是，本文所描述的实施例可以与其它实施例相结合。
在本申请实施例的描述中，术语“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
在本申请实施例的描述中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
在本申请实施例的描述中，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
在本申请实施例的描述中，除非另有明确的规定和限定，技术术语“安装”“相连”“连接”“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或成一体；也可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本申请实施例中的具体含义。
目前，从市场形势的发展来看，动力电池的应用越加广泛。动力电池不仅被应用于水力、火力、风力和太阳能电站等储能电源系统，而且还被广泛应用于电动自行车、电动摩托车、电动汽车等电动交通工具，以及军事装备和航空航天等多个领域。随着动力电池应用领域的不断扩大，其市场的需求量也在不断地扩增。
本发明人注意到，高比能电池的快充性能较差，这可能会影响到高比能电池的应用。
为了缓解高比能电池的快充性能较差的问题，发明人研究发现，随着电池单体的极片的活性物质层的涂布质量增加，极片的厚度增加，这将导致电池单体的极化增加，进而导致电池单体的快充恶化。分解厚涂布下的电池单体的极化来源，主要由欧姆阻抗和扩散阻抗组成，其中，欧姆阻抗中的液相欧姆阻抗和扩散阻抗中的浓差极化均在一定程度上受到电解液影响，而随着电池单体的极片的活性物质层的涂布质量增加，电池液相欧姆阻抗和快充下浓差极化增大。另外，欧姆阻抗中的固相欧姆阻抗可由正极极片的膜片电阻(导电性)定义，正极极片导电性影响直流电阻。
基于以上考虑，为了提高高比能电池的快充性能，发明人经过深入研究，设计了一种电池单体，本申请的电池单体具有厚涂布极片，正极极片的导电性影响电池单体的直流电阻，正极极片的膜片电阻越低，其具有越高的导电性，有利于降低电池单体的固相欧姆电阻。电解液的电导率影响欧姆阻抗中液相欧姆阻抗和扩散阻抗中浓差极化，电解液的电导率越大，有利于降低电池液相欧姆阻抗，并在一定程度上缓解浓差极化。同时降低正极极片的膜片电阻以及提高电解液的电导率，电池单体能够实现厚涂布下的快充。
本申请的实施例所提到的电池是指包括多个电池单体以提供更高的电压和容量的单一的物理模块。电池一般包括用于封装多个电池单体的电池箱体，电池箱体可以避免液体或其他异物影响电池单体的充电或放电。
其中，每个电池单体为二次电池；可以是锂离子电池，还可以是锂硫电池、钠离子电池或镁离子电池，但不局限于此。电池单体可呈圆柱体、扁平体、长方体或其它形状等。电池单体一般按封装的方式分成三种：圆柱电池单体、方形电池单体和软包电池单体。
电池单体包括电极组件和电解液，电极组件由正极极片、负极极片和隔离膜组成。电池单体主要依靠金属离子在正极极片和负极极片之间移动来工作。正极极片包括正极集流体和正极活性物质层，正极活性物质层涂覆于正极集流体的表面，未涂覆正极活性物质层的正极集流体凸出于已涂覆正极活性物质层的正极集流体，未涂覆正极活性物质层的正极集流体作为正极极耳。以锂离子电池为例，正极集流体的材料可以为铝，正极活性物质可以为钴酸锂、磷酸铁锂、三元锂或锰酸锂等。负极极片包括负极集流体和负极活性物质层，负极活性物质层涂覆于负极集流体的表面，未涂覆负极活性物质层的负极集流体凸出于已涂覆负极活性物质层的负极集流体，未涂覆负极活性物质层的负极集流体作负极极耳。负极集流体的材料可以为铜，负极活性物质可以为碳或硅等。为了保证通过大电流而不发生熔断，正极极耳的数量为多个且层叠在一起，负极极耳的数量为多个且层叠在一起。隔离膜的材质可以为聚丙烯(Polypropylene，PP)或聚乙烯(Polyethylene，PE)等。此外，电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例并不限于此。
电池单体还包括集流构件，集流构件用于将电池单体的极耳和电极端子电连接，以将电能从电极组件输送至电极端子，经电极端子输送至电池单体的外部；多个电池单体之间通过汇流部件实现电连接，以实现多个电池单体的串联、并联或者混联。
电池还包括采样端子和电池管理系统，采样端子连接于汇流部件，用于采集电池单体的信息，例如电压或者温度等等。采样端子将所采集到的电池单体的信息传递至电池管理系统，电池管理系统检测到电池单体的信息超出正常范围时，会限制电池的输出功率以实现安全防护。
可以理解的是，本申请实施例中描述的使用电池所适用的用电装置可以为多种形式，例如，手机、便携式设备、笔记本电脑、电瓶车、电动汽车、轮船、航天器、电动玩具和电动工具等等，例如，航天器包括飞机、火箭、航天飞机和宇宙飞船等等，电动玩具包括固定式或移动式的电动玩具，例如，游戏机、电动汽车玩具、电动轮船玩具和电动飞机玩具等等，电动工具包括金属切削电动工具、研磨电动工具、装配电动工具和铁道用电动工具，例如，电钻、电动砂轮机、电动扳手、电动螺丝刀、电锤、冲击电钻、混凝土振动器和电刨。
本申请的实施例描述的电池单体以及电池不仅仅局限适用于上述所描述的用电装置，还可以适用于所有使用电池单体以及电池的用电装置，但为描述简洁，下述实施例均以电动汽车为例进行说明。
请参阅图1，图1为本申请一些实施例提供的车辆的结构示意图。车辆1000可以为燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等。车辆1000的内部设置有电池100，电池100可以设置在车辆1000的底部或头部或尾部。电池100可以用于车辆1000的供电，例如，电池100可以作为车辆1000的操作电源。车辆1000还可以包括控制器200和马达300，控制器200用来控制电池100为马达300供电，例如，用于车辆1000的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池100不仅仅可以作为车辆1000的操作电源，还可以作为车辆1000的驱动电源，代替或部分地代替燃油或天然气为车辆1000提供驱动动力。
请参照图2，图2为本申请一些实施例提供的电池的爆炸图。电池100包括箱体10和电池单体20，电池单体20容纳于箱体10内。其中，箱体10用于为电池单体20提供容纳空间，箱体10可以采用多种结构。在一些实施例中，箱体10可以包括第一部分11和第二部分12，第一部分11与第二部分12相互盖合，第一部分11和第二部分12共同限定出用于容纳电池单体20的容纳空间。第二部分12可以为一端开口的空心结构，第一部分11可以为板状结构，第一部分11盖合于第二部分12的开口侧，以使第一部分11与第二部分12共同限定出容纳空间；第一部分11和第二部分12也可以是均为一侧开口的空心结构，第一部分11的开口侧盖合于第二部分12的开口侧。当然，第一部分11和第二部分12形成的箱体10可以是多种形状，比如，圆柱体、长方体等。
在电池100中，电池单体20可以是多个，多个电池单体20之间可串联或并联或混联，混 联是指多个电池单体20中既有串联又有并联。多个电池单体20之间可直接串联或并联或混联在一起，再将多个电池单体20构成的整体容纳于箱体10内；当然，电池100也可以是多个电池单体20先串联或并联或混联组成电池模块形式，多个电池模块再串联或并联或混联形成一个整体，并容纳于箱体10内。电池100还可以包括其他结构，例如，该电池100还可以包括汇流部件，用于实现多个电池单体20之间的电连接。
其中，每个电池单体20为二次电池；可以是锂离子电池，还可以是锂硫电池、钠离子电池或镁离子电池，但不局限于此。电池单体20可呈圆柱体、扁平体、长方体或其它形状等。
请参照图3，图3为本申请一些实施例提供的第一种电池单体的分解结构示意图。电池单体20是指组成电池的最小单元。如图3，电池单体20包括有端盖21、壳体22、电极组件23以及其他的功能性部件。
端盖21是指盖合于壳体22的开口处以将电池单体20的内部环境隔绝于外部环境的部件。不限地，端盖21的形状可以与壳体22的形状相适应以配合壳体22。可选地，端盖21可以由具有一定硬度和强度的材质(如铝合金)制成，这样，端盖21在受挤压碰撞时就不易发生形变，使电池单体20能够具备更高的结构强度，安全性能也可以有所提高。端盖21上可以设置有如电极端子等的功能性部件。电极端子可以用于与电极组件23电连接，以用于输出或输入电池单体20的电能。在一些实施例中，端盖21上还可以设置有用于在电池单体20的内部压力或温度达到阈值时泄放内部压力的泄压机构。端盖21的材质也可以是多种的，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。在一些实施例中，在端盖21的内侧还可以设置有绝缘件，绝缘件可以用于隔离壳体22内的电连接部件与端盖21，以降低短路的风险。示例性的，绝缘件可以是塑料、橡胶等。
壳体22是用于配合端盖21以形成电池单体20的内部环境的组件，其中，形成的内部环境可以用于容纳电极组件23、电解液以及其他部件。壳体22和端盖21可以是独立的部件，可以于壳体22上设置开口，通过在开口处使端盖21盖合开口以形成电池单体20的内部环境。不限地，也可以使端盖21和壳体22一体化，具体地，端盖21和壳体22可以在其他部件入壳前先形成一个共同的连接面，当需要封装壳体22的内部时，再使端盖21盖合壳体22。壳体22可以是多种形状和多种尺寸的，例如长方体形、圆柱体形、六棱柱形等。具体地，壳体22的形状可以根据电极组件23的具体形状和尺寸大小来确定。壳体22的材质可以是多种，比如，铜、铁、铝、不锈钢、铝合金、塑胶等，本申请实施例对此不作特殊限制。
电极组件23是电池单体20中发生电化学反应的部件。壳体22内可以包含一个或更多个电极组件23。电极组件23主要由正极片和负极片卷绕或层叠放置形成，并且通常在正极片与负极片之间设有隔膜。正极片和负极片具有活性物质的部分构成电极组件的主体部，正极片和负极片不具有活性物质的部分各自构成极耳。正极极耳和负极极耳可以共同位于主体部的一端或是分别位于主体部的两端。在电池的充放电过程中，正极活性物质和负极活性物质与电解液发生反应，极耳连接电极端子以形成电流回路。
根据本申请的一些实施例，本申请提供了一种电池单体，包括：正极极片和电解液。正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，正极极片的膜片电阻≤1Ω。电解液的电导率≥14mS/cm。
正极极片单面的正极活性物质层的涂布质量可理解为在正极集流体的一面涂布正极活性浆料并干燥后形成的正极活性物质层的质量，包括正极活性物质、导电剂和粘结剂等。
作为示例，正极极片单面的正极活性物质层的涂布质量可以为410mg/1540.25mm 2、420mg/1540.25mm 2、430mg/1540.25mm 2、440mg/1540.25mm 2、450mg/1540.25mm 2、460mg/1540.25mm 2、470mg/1540.25mm 2、480mg/1540.25mm 2、490mg/1540.25mm 2、500mg/1540.25mm 2、510mg/1540.25mm 2、520mg/1540.25mm 2、530mg/1540.25mm 2、540mg/1540.25mm 2或550mg/1540.25mm 2。
可选地，正极极片单面的正极活性物质层的涂布质量≥450mg/1540.25mm 2。
可选地，正极极片单面的正极活性物质层的涂布质量≥500mg/1540.25mm 2。
正极极片的膜片电阻使用本领域公知的测试方法进行，作为示例，本申请实施例提供一种正极极片的膜片电阻的测试方法：
沿着正极极片纵向取4cm*25cm面积样品，打开两探针膜片电阻测试仪，选择单点模式，输入端子的测试面积154.02mm2，平行样品数量20个，压力0.4t，时间间隔15s，将测试的极片放在探针中间，先点击软件上的运行按钮然后向下拨动换向阀，15s后自动采集一个数据，换一个点时测试方法如上，直到测试20个点时换个组别。
作为示例，正极极片的膜片电阻可以为0.02Ω、0.05Ω、0.08、0.1Ω、0.2Ω、0.3Ω、0.4Ω、0.5Ω、0.6Ω、0.7Ω、0.8Ω、0.9Ω或1Ω。
电解液的电导率使用本领域公知的测试方法进行，作为示例，本申请实施例提供一种电解液的电导率的测试方法：
采用干燥、洁净的耐腐蚀样品瓶取电解液约100ml试样，密闭置于25℃±0.5℃恒温水浴中，并不时摇动，使其受热均匀，待试样温度恒定时，用查有电极的胶塞代替样品瓶盖，待温度在25℃±0.5℃范围内时，读取电导率仪上数据，即为被测试试样的电导率。
作为示例，电解液的电导率可以为14mS/cm、15mS/cm、16mS/cm、17mS/cm、18mS/cm、19mS/cm或20mS/cm。
可选地，14mS/cm≤电解液的电导率≤30mS/cm。
本申请的电池单体具有厚涂布极片，正极极片的导电性影响电池单体的直流电阻，正极极片的膜片电阻越低，其具有越高的导电性，有利于降低电池单体的固相欧姆电阻。电解液的电导率影响欧姆阻抗中液相欧姆阻抗和扩散阻抗中浓差极化，电解液的电导率越大，有利于降低电池液相欧姆阻抗，并在一定程度上缓解浓差极化。同时降低正极极片的膜片电阻以及提高电解液的电导率，电池单体能够实现厚涂布下的快充。
可选地，电解液包含电解质、有机溶剂和成膜添加剂。
其中，电解质为LiPF 6，且电解质在电解液中的浓度为0.8mol/L～1.3mol/L。
有机溶剂包括乙烯碳酸酯、碳酸甲乙酯和碳酸二甲酯。
根据本申请的一些实施例，可选地，正极极片的膜片电阻≤0.8Ω，电解液的电导率≥16mS/cm。
当正极极片的膜片电阻≤0.8Ω，且电解液的电导率≥16mS/cm，至少可以实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～470mg/1540.25mm 2的电池单体10％～80％SOC在30min内的快充。
根据本申请的一些实施例，可选地，正极极片的膜片电阻≤0.5Ω，电解液的电导率≥18mS/cm。
当正极极片的膜片电阻≤0.5Ω，且电解液的电导率≥18mS/cm，至少可以实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2的电池单体10％～80％SOC在30min内的快充。
根据本申请的一些实施例，可选地，正极极片的正极活性物质的粉末电阻≤30Ω/cm。
作为示例，正极极片的正极活性物质的粉末电阻可以为5Ω/cm、8Ω/cm、10Ω/cm、12Ω/cm、15Ω/cm、18Ω/cm、20Ω/cm、22Ω/cm、25Ω/cm、28Ω/cm或30Ω/cm。
正极活性物质的粉末电阻影响正极极片的膜片电阻，当正极极片的正极活性物质的粉末电阻≤30Ω/cm时，正极极片的膜片电阻≤1Ω。
根据本申请的一些实施例，可选地，正极活性物质包括碳包覆的磷酸铁锂材料。
磷酸铁锂材料的结构式为LiM aFe 1-aPO 4，其中M选自Cu、Mn、Cr、Zn、Pb、Ca、Co、Ni、Sr、Nb和Ti中的任意一种或多种，且0≤a≤1。
可选地，碳包覆的磷酸铁锂材料中碳元素的质量分数为0.1wt％～5wt％。
正极活性物质影响到正极活性物质的粉末电阻，碳包覆的磷酸铁锂材料的粉末电阻≤30Ω/cm。
根据本申请的一些实施例，可选地，正极极片的正极活性物质的含量≥96wt％。
作为示例，正极极片的正极活性物质的含量可以为96wt％、96.5wt％、97wt％、97.5wt％、98wt％或98.5wt％。
可选地，正极极片的正极活性物质的含量为96wt％～98.5wt％。
正极极片的正极活性物质的含量影响到电池单体的能量密度，当正极极片的正极活性物质的含量≥96wt％时，且正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，电池单体的能量密度较高。
可选地，正极极片的正极活性物质层包括96wt％～98.5wt％正极活性物质、0～1wt％的导电剂、1wt％～3wt％粘结剂和0～1wt％分散剂。
其中，导电剂包括导电炭黑SP和/或碳纳米管CNT；粘结剂包括聚偏二氟乙烯(Polyvinylidene difluoride，PVDF)。
根据本申请的一些实施例，可选地，正极极片的压实密度≥2.55g/m 3。
作为示例，正极极片的压实密度可以为2.55g/m 3、2.6g/m 3、2.65g/m 3、2.7g/m 3或2.75g/m 3。
可选地，正极极片的压实密度≥2.6g/m 3。
正极极片的压实密度影响到电池单体的能量密度，当正极极片的压实密度≥2.55g/m 3时，且正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，电池单体的能量密度较高。
根据本申请的一些实施例，可选地，正极极片的孔隙率为20％～35％。
作为示例，正极极片的孔隙率可以为20％、21％、22％、23％、24％、25％、26％、27％、28％、29％、30％、31％、32％、33％、34％或35％。
可选地，正极极片的孔隙率为22％～30％。
正极极片的孔隙率和压实密度对应，当正极极片的孔隙率为20％～35％时，电池单体具有较高的能量密度。
根据本申请的一些实施例，可选地，正极极片的正极集流体的厚度为10μm～20μm。
作为示例，正极极片的正极集流体的厚度可以为10μm、11μm、12μm、13μm、14μm、15μm、16μm、17μm、18μm、19μm或20μm。
当正极极片的正极集流体的厚度＞20μm时，电池单体的能量密度较低；当正极极片的正极集流体的厚度＜10μm时，正极集流体容易开裂；当正极极片的正极集流体的厚度为10μm～20μm时，既能保证电池单体具有较高的能量密度，还能保证正极集流体具有较好的机械性能。
根据本申请的一些实施例，可选地，电池单体还包括负极极片，电池单体的负极极片单面的负极活性物质层的涂布质量≥180mg/1540.25mm 2，负极极片的膜片电阻≤0.01Ω。
作为示例，电池单体的负极极片单面的负极活性物质层的涂布质量可以为180mg/1540.25mm 2、185mg/1540.25mm 2、190mg/1540.25mm 2、195mg/1540.25mm 2、200mg/1540.25mm 2、205mg/1540.25mm 2、210mg/1540.25mm 2、215mg/1540.25mm 2、220mg/1540.25mm 2、225mg/1540.25mm 2、230mg/1540.25mm 2、235mg/1540.25mm 2、240mg/1540.25mm 2或245mg/1540.25mm 2。
可选地，电池单体的负极极片单面的负极活性物质层的涂布质量≥190mg/1540.25mm 2。
可选地，电池单体的负极极片单面的负极活性物质层的涂布质量≥200mg/1540.25mm 2。
负极极片的膜片电阻使用本领域公知的测试方法进行，作为示例，本申请实施例提供一种负极极片的膜片电阻的测试方法：
沿着负极极片纵向取4cm*25cm面积样品，打开两探针膜片电阻测试仪，选择单点模式，输入端子的测试面积154.02mm2，平行样品数量20个，压力0.4t，时间间隔15s，将测试的极片放在探针中间，先点击软件上的运行按钮然后向下拨动换向阀，15s后自动采集一个数据，换一个点时测试方法如上，直到测试20个点时换个组别。
作为示例，负极极片的膜片电阻可以为0.005Ω、0.006Ω、0.007Ω、0.008Ω、0.009Ω或0.01Ω。
电池单体的负极极片单面的负极活性物质层的涂布质量和正极极片单面的正极活性物质层的涂布质量相对应。
可选地，负极极片的负极活性物质的含量≥96wt％。
可选地，负极极片的负极活性物质的含量为96wt％～98wt％。
可选地，负极极片的负极活性物质层包括96wt％～98wt％负极活性物质、0.5wt％～2wt％的导电剂和2wt％～4wt％粘结剂。
其中，负极活性物质包括石墨或硅碳材料，导电剂包括导电炭黑SP和/或碳纳米管CNT；粘结剂包括0.5wt％～1.5wt％羧甲基纤维素钠(Carboxymethylcellulose sodium，CMC-Na)和1wt％～3wt％丁苯橡胶(Polymerized styrene butadiene rubber，SBR)。
可选地，负极极片采用多层涂布，靠近负极集流体的负极活性材料采用高压密石墨，远离负极集流体的负极活性材料采用快充石墨。
根据本申请的一些实施例，可选地，负极极片的压实密度≥1.67g/m 3。
作为示例，负极极片的压实密度可以为1.67g/m 3、1.7g/m 3、1.75g/m 3、1.8g/m 3、1.85g/m 3、1.9g/m 3、1.95g/m 3或2g/m 3。
可选地，负极极片的压实密度≥1.75g/m 3。
可选地，负极极片的压实密度≥1.8g/m 3。
负极极片的压实密度影响到电池单体的能量密度，当负极极片的压实密度≥1.67g/m 3时，且负极极片单面的负极活性物质层的涂布质量≥180mg/1540.25mm 2，电池单体的能量密度较高。
根据本申请的一些实施例，可选地，负极极片的孔隙率为25％～40％。
作为示例，负极极片的孔隙率可以为25％、26％、27％、28％、29％、30％、31％、32％、33％、34％、35％、36％、37％、38％、39％或40％。
可选地，负极极片的孔隙率为27％～35％。
可选地，负极极片的孔隙率为30％～35％。
负极极片的孔隙率影响到负极极片的曲折度，提高负极极片的孔隙率有利于提高负极极片的曲折度，以及降低锂离子传输路径，从而提高电池的快充性能。
需要说明的是，在制备负极活性物质层的负极活性浆料中添加造孔剂，可以提高负极极片的孔隙率，在负极活性浆料中每添加3wt％造孔剂，负极极片的孔隙率可增加0.5％～1％，且为了保证负极活性物质的粘结力，负极活性浆料中造孔剂的添加量不超过25wt％，造孔剂在负极极片冷压后挥发。
根据本申请的一些实施例，可选地，负极极片的负极集流体的厚度为4μm～8μm。
作为示例，负极极片的负极集流体的厚度可以为4μm、5μm、6μm、7μm或8μm。
当负极极片的负极集流体的厚度＞8μm时，电池单体的能量密度较低；当负极极片的负极集流体的厚度＜4μm时，负极集流体容易开裂；当负极极片的负极集流体的厚度为4μm～8μm时，既能保证电池单体具有较高的能量密度，还能保证负极集流体具有较好的机械性能。
根据本申请的一些实施例，可选地，电池单体还包括隔离膜，隔离膜的厚度≤7μm。
作为示例，隔离膜的厚度可以为1μm、2μm、3μm、4μm、5μm、6μm或7μm。
隔离膜的厚度影响到电池单体的能量密度，当隔离膜的厚度≤7μm时，电池单体的能量密度较高。
可选地，隔离膜包括基膜，基膜的材质为聚丙烯或聚乙烯。
隔离膜包括基膜和功能层，功能层包括防火涂层、高电解液浸润涂层和导锂离子涂层中的任意一种或多种。
其中，防火涂层包括米氧化铝、氧化锆、二氧化钛和氧化镁中的任意一种或多种。
高电解液浸润涂层包括聚乙烯、聚丙烯、聚四氟乙烯和丁苯橡胶中的任意一种或多种。
导锂离子涂层包括锂镧钛氧和/或锂镧锆氧。
以下结合实施例对本申请的电池单体作进一步的详细描述。
实施例1～13和对比例1～3的电池单体的正极极片的参数如表1所示，实施例1～13和对比例1～3的电池单体的负极极片的参数如表2所示。
表1实施例1～13和对比例1～3的电池单体的正极极片的参数
Figure PCTCN2022128425-appb-000001
Figure PCTCN2022128425-appb-000002
表2实施例1～13和对比例1～3的电池单体的负极极片的参数
Figure PCTCN2022128425-appb-000003
Figure PCTCN2022128425-appb-000004
实施例1～3和对比例1～3的电池单体的制备方法：
S1、制备正极极片
将96.9wt％碳包覆的磷酸铁锂材料、0.7wt％导电炭黑、0.1wt％碳纳米管、1.8wt％聚偏二氟乙烯、0.5wt％乙基纤维素分别溶于N-甲基吡咯烷酮溶剂中经搅拌制成正极活性浆料，然后将制得的正极活性浆料均匀涂覆在厚度为17μm的铝箔表面，经烘干、冷压，制得正极极片。
S2、制备负极极片
将96.6wt％石墨、1wt％导电炭黑、0.1wt％碳纳米管、0.6wt％羧甲基纤维素钠和1.7wt％丁苯橡胶分别溶于超纯水制成负极活性浆料，然后将制得的负极活性浆料均匀涂覆在厚度为4.5μm的铜箔表面，远离铝箔的一层为快充石墨，靠近铝箔的一层为高压密石墨，两层厚度比为5:5，经烘干、冷压，制得负极极片。
S3、制备电池单体
将制备得到的正极极片和负极极片模切、分切后卷绕成电极组件，隔离膜包括5μm的聚乙烯基膜，基膜表面有15μm的Al 2O 3涂层，然后进行热压，将电芯压实，再进行包膜、极耳焊接、转接片固定及入壳顶盖焊接装成干电芯，经烘焙除掉水分后，注入电解液，注液后将电芯使用以0.1C恒电流充电至规定的截至电压，完成化成流程，将注液口密封钉焊接好，然后再以0.33C恒电流重放一次完成容量流程，最后包好蓝膜，制得电池单体。
试验例1
分别测得实施例1～13和对比例1～3的电池单体的能量密度和10％～80％SOC快充时间，结果如表3所示。
其中，电池单体的能量密度的测试方法如下：
电池单体体积能量密度＝电池放电容量*放电平台电压/电池体积，电池放电容量为电池在 25℃下以1/3C充电至3.65V，然后放电至2.0V时的容量；放电平台电压为电化学反应达到平衡时电位，一般测试设备可自动提取；电池体积使用排水法，将电池置于纯水中，排出水的体积。电池容量测试设备为电池测试仪。
电池单体的10％～80％SOC快充时间的测试方法如下：
叠片三电极测试法，将硬壳电芯正负极极片取出使用DMC溶剂浸泡清洗72h以上，待电解液溶剂、锂盐、添加剂完全浸出，将极片在真空烘箱中烘干，然后将阴阳极极片组装成叠片三电极电芯，其中铜丝作为参比电极。然后将叠片三电极电芯在25℃下测试叠片电芯每个SOC下的析锂充电倍率，充电最大倍率以参比电极电位降至0mV截至，记录此SOC下的最大充电倍率。按此方法，以5％SOC为一个点，测试每5％SOC下的最大充电倍率，如5％SOC、10％SOC、15％SOC至100％SOC，按照此测试所得的10％SOC～80％SOC下的最大充电倍率计算10％～80％SOC下连续充电时间即为快充时间。
表3实施例1～13和对比例1～3的电池单体的能量密度和10％～80％SOC快充时间
项目 能量密度(Wh/L) 10％～80％SOC快充时间(min)
实施例1 400 30
实施例2 400 20
实施例3 430 25
实施例4 460 30
实施例5 400 15
实施例6 430 20
实施例7 460 25
实施例8 500 30
实施例9 430 28
实施例10 430 25
实施例11 430 20
实施例12 415 32
实施例13 400 28
对比例1 400 32
对比例2 400 35
对比例3 400 33
由实施例1可知，当正极极片的膜片电阻为1Ω，且电解液的电导率为14mS/cm时，可实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2的电池单体10％～80％SOC@≤30min快充。
由实施例2～4可知，当正极极片的膜片电阻为0.8Ω，且电解液的电导率为16mS/cm时，可实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～470mg/1540.25mm 2的电池单体10％～80％SOC@≤30min快充，最短可达到20min。
由实施例5～8可知，当正极极片的膜片电阻为0.5Ω，且电解液的电导率为18mS/cm时，可实现具有正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2的电池单体10％～80％SOC@≤30min快充，最短可达到15min。
由实施例1、实施例4和实施例8对比可知，随着正极极片单面的正极活性物质层的涂布质量的增加，可通过降低正极极片的膜片电阻和提高电解液的电导率实现电池单体30min及以内的快充时间。
由实施例9和实施例1对比可知，降低正极极片的膜片电阻为0.8Ω，电解液的电导率不变为14mS/cm，电池单体的快充时间缩短为28min。
由实施例10和实施例1对比可知，提高电解液的电导率为16mS/cm，正极极片的膜片电阻不变为1Ω，电池单体的快充时间缩短为25min。
由实施例11和实施例1对比可知，降低正极极片的膜片电阻为0.8Ω，提高电解液的电导率为18mS/cm，电池单体的快充时间缩短为20min。
由实施例12和实施例1对比可知，降低负极极片的孔隙率为25％，电池单体的快充时间延长至32min。
由实施例13和实施例1对比可知，提高负极极片的孔隙率为40％，电池单体的快充时间缩短至28min。
由对比例1和实施例1对比可知，提高正极极片的膜片电阻为1.2Ω，电解液的电导率不变为14mS/cm，电池单体的快充时间延长为32min。
由对比例2和实施例1对比可知，降低电解液的电导率为12mS/cm，正极极片的膜片电阻不变为1.2Ω，电池单体的快充时间延长为35min。
由对比例3和实施例1对比可知，降低正极极片的膜片电阻为0.8Ω，降低电解液的电导率为12mS/cm，电池单体的快充时间延长为33min。
且对于对比例1～3快充性能较差的电池单体，如果使用和实施例1相同的快充条件，电池单体衰减会加快，甚至出现跳水，导致电池循环次数下降。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (16)

  1. 一种电池单体，其中，所述电池单体包括：正极极片和电解液；
    所述正极极片单面的正极活性物质层的涂布质量为410mg/1540.25mm 2～550mg/1540.25mm 2，所述正极极片的膜片电阻≤1Ω；
    所述电解液的电导率≥14mS/cm。
  2. 根据权利要求1所述的电池单体，其中，所述正极极片的膜片电阻≤0.8Ω，所述电解液的电导率≥16mS/cm。
  3. 根据权利要求1或2所述的电池单体，其中，所述正极极片的膜片电阻≤0.5Ω，所述电解液的电导率≥18mS/cm。
  4. 根据权利要求1～3任一项所述的电池单体，其中，所述正极极片的正极活性物质的粉末电阻≤30Ω/cm。
  5. 根据权利要求4所述的电池单体，其中，所述正极活性物质包括碳包覆的磷酸铁锂材料。
  6. 根据权利要求1～5任一项所述的电池单体，其中，所述正极极片的正极活性物质的含量≥96wt％。
  7. 根据权利要求1～6任一项所述的电池单体，其中，所述正极极片的压实密度≥2.55g/m 3。
  8. 根据权利要求1～7任一项所述的电池单体，其中，所述正极极片的孔隙率为20％～35％。
  9. 根据权利要求1～8任一项所述的电池单体，其中，所述正极极片的正极集流体的厚度为10μm～20μm。
  10. 根据权利要求1～9任一项所述的电池单体，其中，所述电池单体还包括负极极片，所述电池单体的负极极片单面的负极活性物质层的涂布质量≥180mg/1540.25mm 2，所述负极极片的膜片电阻≤0.01Ω。
  11. 根据权利要求10所述的电池单体，其中，所述负极极片的压实密度≥1.67g/m 3。
  12. 根据权利要求10或11所述的电池单体，其中，所述负极极片的孔隙率为25％～40％。
  13. 根据权利要求10～12任一项所述的电池单体，其中，所述负极极片的负极集流体的厚度为4μm～8μm。
  14. 根据权利要求10～13任一项所述的电池单体，其中，所述电池单体还包括隔离膜，所述隔离膜的厚度≤7μm。
  15. 一种电池，其中，所述电池包括权利要求1～14任一项所述的电池单体。
  16. 一种用电装置，其中，所述用电装置包括权利要求15所述的电池，所述电池用于提供电能。
PCT/CN2022/128425 2022-10-28 2022-10-28 一种电池单体、电池及用电装置 WO2024087225A1 (zh)

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