WO2021238858A1 - 锂离子电池、动力电池模组、电池包、电动汽车和储能装置 - Google Patents

锂离子电池、动力电池模组、电池包、电动汽车和储能装置 Download PDF

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WO2021238858A1
WO2021238858A1 PCT/CN2021/095497 CN2021095497W WO2021238858A1 WO 2021238858 A1 WO2021238858 A1 WO 2021238858A1 CN 2021095497 W CN2021095497 W CN 2021095497W WO 2021238858 A1 WO2021238858 A1 WO 2021238858A1
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positive electrode
current collector
lithium ion
ion battery
electrode current
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PCT/CN2021/095497
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English (en)
French (fr)
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孙华军
王高武
林文生
赵玲
朱燕
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比亚迪股份有限公司
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Priority to JP2022573376A priority Critical patent/JP2023527860A/ja
Priority to KR1020227046097A priority patent/KR20230017868A/ko
Priority to EP21814514.2A priority patent/EP4160753A1/en
Priority to CA3180368A priority patent/CA3180368A1/en
Publication of WO2021238858A1 publication Critical patent/WO2021238858A1/zh
Priority to US18/070,876 priority patent/US20230086598A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • 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
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • 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
    • 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
    • H01M2004/028—Positive electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the technical field of lithium-ion batteries, in particular to lithium-ion batteries, power battery modules, battery packs, electric vehicles and energy storage devices.
  • lithium-ion batteries have been applied in more and more fields, especially power batteries, which have developed rapidly.
  • lithium batteries are used as the main energy supply source for electric vehicles, especially the large-scale use of ternary batteries in recent years
  • the thermal runaway of lithium-ion power batteries (the chain reaction of battery heat causes rapid changes in the battery's self-temperature rise rate caused by overheating and fire , Explosion) accidents such as fire and explosion occur from time to time.
  • the battery pack once a battery is thermally out of control, it will often trigger the thermal runaway of the battery pack or adjacent batteries in the system, which is thermal diffusion, resulting in the entire battery pack. Out of control, serious consequences such as fire and explosion will occur.
  • the safety of lithium-ion batteries is still facing challenges.
  • This application aims to solve one of the technical problems in the related technology at least to a certain extent.
  • one purpose of the present application is to provide a lithium ion battery that can effectively improve the thermal runaway problem and improve the safety of use.
  • the lithium ion battery includes an outer shell and a pole core encapsulated in the shell, the pole core includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector.
  • the positive electrode current collector, the positive electrode material layer, the negative electrode sheet, and the separator are defined as the effective component with the lowest melting point, and the effective component satisfies The following conditions:
  • n is the number of layers of the effective component
  • L is the size of the effective component in the first direction
  • W is the size of the effective component in the second direction
  • the unit of W is m
  • d 2 is the thickness of the effective part
  • d 2 is the unit of m
  • ⁇ is the density of the effective part
  • the unit of ⁇ is kg/m 3
  • C p is the specific heat capacity of the effective part (in this text, the heat Melting, specific heat capacity and specific heat can be used interchangeably)
  • the unit of C p is J/(Kg ⁇ °C) (ie J/(Kg ⁇ K), in this article J/(Kg ⁇ °C) and J/(Kg ⁇ K) ) Can be used interchangeably)
  • the first direction is parallel to the direction in which the current in the effective component is drawn
  • the second direction intersects the first direction.
  • the safety of the battery is greatly improved.
  • the lithium-ion battery that meets the above conditions effectively reduces the thermal runaway of the battery. Or the possibility of thermal diffusion, avoiding damage to adjacent batteries or the outside caused by battery heat generation.
  • the present application provides a lithium ion battery.
  • the lithium ion battery includes an outer shell and a pole core encapsulated in the shell, the pole core includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet ,
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector, and the positive electrode current collector satisfies the following conditions:
  • n is the number of layers of the positive electrode current collector
  • L is the size of the positive electrode current collector in the first direction
  • the unit of L is m
  • W is the size of the positive electrode current collector in the second direction
  • W The unit of is m
  • d 2 is the thickness of the positive current collector
  • the unit of d 2 is m
  • ⁇ is the density of the positive current collector
  • the unit of ⁇ is kg/m 3
  • C p is the positive current collector
  • the unit of C p is J/(Kg ⁇ °C)
  • the first direction is parallel to the direction of current in the positive electrode current collector
  • the second direction intersects the first direction.
  • the battery safety is greatly improved.
  • the lithium-ion battery that meets the above conditions effectively reduces battery heat.
  • the occurrence of out-of-control or thermal diffusion prevents damage to adjacent batteries or the outside caused by battery heat generation.
  • the present application provides a power battery module or battery pack.
  • the power battery module or battery pack includes at least one lithium ion battery as described above. The possibility of thermal runaway and thermal diffusion of the power battery module is significantly reduced, and the use safety is significantly improved.
  • this application provides an electric vehicle or an energy storage device.
  • the electric vehicle or energy storage device includes the aforementioned power battery module or the aforementioned battery pack.
  • the electric vehicle has excellent safety and long service life.
  • FIG. 1 is a schematic diagram of the structure of a laminated pole core according to an embodiment of the present application.
  • Fig. 2 is a schematic cross-sectional structure diagram of a positive electrode sheet in Fig. 1 along the line A-A.
  • Fig. 3 is a schematic structural view of a flattened state of the laminated body constituting the wound-shaped pole core according to an embodiment of the present application.
  • Fig. 4 is a schematic structural diagram of a wound pole core according to an embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of a wound pole core according to an embodiment of the present application.
  • Fig. 6 is a schematic plan view of a winding section in Figs. 4 and 5.
  • Fig. 7 is a schematic cross-sectional structure view taken along the line B-B in Fig. 6.
  • Fig. 8 is a schematic plan view of a winding section of another embodiment of the present application.
  • the lithium ion battery includes an outer shell and a pole core encapsulated in the shell, the pole core includes a positive electrode sheet, a negative electrode sheet, and a separator located between the positive electrode sheet and the negative electrode sheet
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector, and the lowest melting point of the positive electrode current collector, the positive electrode material layer, the negative electrode sheet, and the separator is defined as the effective component, and the effective component satisfies The following conditions:
  • n is the number of layers of the effective component
  • L is the size of the effective component in the first direction
  • the unit of L is m
  • W is the size of the effective component in the second direction
  • the unit of W is m
  • d 2 is the thickness of the effective part
  • the unit of d 2 is m
  • ⁇ is the density of the effective part
  • the unit of ⁇ is kg/m 3
  • C p is the specific heat capacity of the effective part
  • the unit of C p The unit is J/(Kg ⁇ °C)
  • the first direction is parallel to the direction in which the current in the effective component is drawn, and the second direction intersects the first direction.
  • the battery safety is greatly improved.
  • the lithium-ion battery that meets the above conditions effectively reduces the battery heat The probability of out-of-control or thermal diffusion, without any new parts, without changing the battery system design, and without additional cost increase.
  • the higher the A value the relatively lower battery safety.
  • the value exceeds 500 the internal structure design of the battery prevents the heat generation from being discharged in time, and the battery safety decreases; and the lower the A value, the battery space is wasted.
  • the shape of the battery is not conducive to the arrangement of the battery inside the electric vehicle.
  • the effective component satisfies the following conditions:
  • the inventor of the present application performed reasonable design and optimization based on the following two equations and models, and obtained the lithium ion battery of the present application, which is specifically as follows:
  • the boundary conditions are:
  • ⁇ represents the density of the predetermined component in the system
  • T represents the temperature when the system reaches thermal equilibrium
  • t represents the time
  • Cp represents the specific heat of the predetermined component
  • k represents the thermal conductivity coefficient
  • Q represents the heat generated
  • h represents the thermal coefficient between the shell and the air
  • E represents the electromotive force
  • U represents the road terminal voltage
  • I represents the charge and discharge current
  • T surface represents the surface temperature of the system
  • T room represents the room temperature.
  • ⁇ is the density of the thermal conductor
  • c is the specific heat capacity of the thermal conductor
  • ⁇ is the thickness of the thermal conductor
  • k is the thermal conductivity coefficient of the thermal conductor
  • m 2 2h/(k ⁇ ).
  • Thermal runaway is mostly caused by a short circuit inside the battery. Once a short circuit occurs, the temperature of the short circuit point can rise rapidly, causing The thermal runaway of the battery can easily cause fire or explosion.
  • the lithium-ion battery of the present application by controlling the number, size, thermodynamics and other parameters of the effective components in the battery, when the battery is short-circuited, the short-circuit point is quickly melted, and then it is cut off. The short-circuit point is prevented, heat is prevented from being further generated, and the material does not reach the out-of-control point, which can greatly ensure the safety of the battery, thereby avoiding the occurrence of thermal runaway, and greatly improving the safety of the battery.
  • the lithium-ion battery of the present application may be a liquid battery, a solid-state battery, or a polymer battery.
  • it may include a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet (ie, Separator), of course, the pole core also includes electrolyte, while for solid batteries, it includes a positive electrode sheet, a negative electrode sheet, and a solid electrolyte layer (ie, a separator) located between the positive electrode sheet and the negative electrode sheet.
  • the negative electrode sheet may include a negative electrode current collector and a negative electrode material layer supported on the negative electrode current collector; in this embodiment, the positive electrode current collector, the positive electrode material layer, the negative electrode current collector, the negative electrode material layer, and the separator are defined
  • the lowest melting point is the effective component.
  • the negative electrode sheet may be a lithium foil or a lithium belt.
  • the lowest melting point of the positive electrode current collector, the positive electrode material layer, the lithium foil (or lithium belt), and the separator is defined as the effective component.
  • the negative electrode sheet may include a porous current collector and a negative electrode active material deposited in the porous structure.
  • the active component is defined as the positive electrode current collector, the positive electrode material layer, the porous current collector, and the separator with the lowest melting point.
  • the positive electrode sheet and the negative electrode sheet are respectively provided with a positive electrode tab and a negative electrode tab for drawing current.
  • the positive electrode tab and the negative electrode are respectively drawn on one side of the positive electrode sheet and the negative electrode sheet, and the positive electrode tab and the negative electrode
  • the tabs can be arranged on the same side (refer to Figure 8) or opposite (refer to Figures 1 and 7).
  • the direction in which the tabs are drawn is the direction in which the current is drawn.
  • a plurality of positive electrode sheets 10 and negative electrode sheets 20 can be alternately stacked in order to form a laminated pole core (refer to Figure 1 for the structure diagram).
  • Separator is provided between adjacent positive and negative sheets, or positive
  • the sheet, the separator, and the negative electrode sheet are stacked and arranged, and then wound to form a wound-shaped pole core (refer to FIG. 2 for the structure diagram).
  • the specific method can be carried out by referring to the conventional technology, and will not be described here too much.
  • the laminated pole core referring specifically to FIG. 1, it includes a plurality of positive electrode sheets 10 and negative electrode sheets 20 that are alternately stacked, and a separator (in the figure) (Not shown)
  • n is the number of stacks of effective components
  • L refers to the size of an effective component in the first direction
  • W refers to the size of an effective component in the second direction
  • d 2 is the size of an effective component. Thickness (dimension along the stacking direction).
  • the positive electrode sheet 10, the negative electrode sheet 20 and the separator 40 are stacked and then wound. Specifically, it is defined to be stacked in sequence
  • the positive electrode sheet 10, the separator 40, and the negative electrode sheet 20 are a laminated body 30.
  • the laminated body 30 is divided into a plurality of successively connected winding sections 31 (refer to FIG. 3). In the wound state, the plurality of wound sections 31 are arranged one after another.
  • n is the number of winding sections (or twice the number of winding turns of the effective part)
  • L is one and the size of the effective part in the winding section in the first direction
  • W is the average value of the size of the effective part in the second direction in the multiple winding sections
  • d 2 is the thickness of the effective part in one winding section.
  • intersection of the second direction and the first direction described in this article specifically refers to: the angle between the first direction and the second direction can be greater than 0 degrees and less than or equal to 90 degrees, some specific implementations In an example, the angle between the first direction and the second direction may specifically be 90 degrees, that is, the first direction and the second direction are perpendicular.
  • the melting point of the positive electrode current collector is usually low.
  • the electrode material is not out of control, which can greatly ensure the safety of the battery.
  • various forms of short circuits inside the battery that cause thermal runaway such as the short circuit between the positive and negative materials, the short circuit between the positive electrode current collector and the negative electrode sheet, the short circuit between the negative electrode current collector and the positive electrode sheet, etc., the positive electrode current collector and the negative electrode After the material is in contact with a short circuit, the heat generated is the largest.
  • the temperature of the short circuit point can quickly rise to 200°C, which will cause the material to lose control, which can easily cause fire or explosion.
  • the basic purpose is to ensure that the material does not reach the out-of-control point when the short-circuit point is fused, and the cathode current collector is selected as an effective component, which can effectively avoid thermal runaway and thermal diffusion, thereby greatly improving the safety of the battery.
  • a positive electrode tab 11 is also led out on one side of the positive electrode sheet 10.
  • the direction in which the positive electrode tab is drawn is the direction in which the current in the positive electrode collector is drawn. Therefore, at this time, the first direction is parallel to the direction in which the positive electrode tab is drawn.
  • the positive electrode tab can be welded to the positive electrode current collector or formed by cutting the positive electrode current collector, that is, the positive electrode tab and the positive electrode current collector are integrally formed. It should be noted that no matter how the positive electrode tab is removed from Leaded out from the positive electrode current collector, the size of the positive electrode current collector in the first direction does not include the size of the positive electrode tab in the first direction. It can be understood that the situation of the negative electrode tab can be the same as that of the positive electrode tab, which will not be repeated here.
  • the second direction can be selected according to actual conditions.
  • the second direction is perpendicular to the first direction.
  • the pole core in the lithium ion battery may be a laminated pole core, the laminated pole core includes a plurality of positive electrode sheets 10 and negative electrode sheets 20 alternately stacked, and n is multiple.
  • the number of the positive electrode current collectors 12 in each positive electrode sheet 10, L is the size of the positive electrode current collector 12 in one positive electrode sheet 10 in the first direction, and W is all the positive electrode current collectors 12 in one positive electrode sheet 10.
  • the pole core in the lithium ion battery may be a wound pole core.
  • the wound pole core is divided into a stack of a plurality of successively connected winding sections 31.
  • the material of the positive electrode current collector includes aluminum, such as aluminum foil, and the negative electrode current collector is copper foil.
  • the low melting point of aluminum can effectively ensure that the material is not out of control when the short-circuit point is melted, thereby avoiding In addition to thermal runaway and thermal diffusion, the safety of lithium-ion batteries is greatly ensured.
  • the thickness d 2 of the positive electrode current collector can range from 6 ⁇ m to 15 ⁇ m (specifically, 6 ⁇ m, 7 ⁇ m, 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, 11 ⁇ m, 12 ⁇ m, 13 ⁇ m, 14 ⁇ m, 15 ⁇ m, etc.);
  • ⁇ is the density of the fluid in the range between 2000kg ⁇ m -3 ⁇ 3000kg ⁇ m -3 (particularly as 2000kg ⁇ m -3, 2100kg ⁇ m -3, 2200kg ⁇ m -3, 2300kg ⁇ m -3, 2400kg ⁇ m -3, 2500kg ⁇ m -3, 2600kg ⁇ m -3, 2700kg ⁇ m -3, 2800kg ⁇ m -3, 2900kg ⁇ m -3, 3000kg ⁇ m -3 , etc.); specific heat capacity C p takes a positive electrode current collector value range between 800J ⁇ kg
  • the short-circuit point fusing is more difficult, and the risk of loss of control is greater. Within the above range, it can effectively ensure that the material is not out of control when the short-circuit point is fused. Good to ensure the safety of the battery.
  • the number of layers n of the positive electrode current collector ranges from 1 to 150 (specifically, 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120). , 130, 140, 150, etc.).
  • n is the total number of short circuit layers of the positive current collector. When n is larger, the heat released by the short circuit is greater, and the risk of loss of control is greater. Within the above range, the energy density of the battery can be guaranteed, and the risk of loss of control is higher. Low.
  • the ratio L/w of the size L of the positive electrode current collector in the first direction to the size W of the positive electrode current collector in the second direction ranges from 0 to 30 (specifically, such as 1, 2, 5, 8, 10, 12, 15, 18, 20, 22, 25, 28, 30, etc.).
  • L/w determines the ohmic resistance inside the battery. The greater the L/w, the greater the ohmic resistance, the greater the battery’s heat generation.
  • L/w determines the impedance of the positive current collector. The greater the value, the more the cell is at the short-circuit point. The greater the total heat produced by the battery cell before fusing, the greater the risk of loss of control. In the above range, the normal operation of the battery can be guaranteed, and the risk of loss of control is low, and the heat generation can be controlled within a certain range, so as to prevent the battery heat from damaging adjacent batteries or the outside.
  • the specific types of the positive electrode material layer and the negative electrode active material are not particularly limited, and those skilled in the art can flexibly select and adjust according to actual needs.
  • the positive electrode material layer may include lithium iron phosphate material.
  • the negative electrode sheet includes a negative electrode active material, and the negative electrode active material may include at least one of graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, and lithium titanate. . Therefore, the compatibility with the above thermal runaway conditions is better, and the risk of thermal runaway of lithium-ion batteries is lower.
  • the lithium ion battery may be a rectangular battery; further, the length of the lithium ion battery may be 500mm-2500mm (specifically, 500mm, 800mm, 1000mm, 1500mm, 1800mm, 2000mm, 2200mm, 2500mm, etc. ). Specifically, it may be a lithium ion battery with a certain strength casing (preferably a metal casing).
  • the lithium-ion battery in this shape and size range can better match the above thermal runaway conditions. Through the above thermal runaway conditions, the lithium ion battery can be controlled more accurately and has a lower risk of thermal runaway. .
  • the lithium ion battery can also have the necessary structures and components of a conventional lithium ion battery, for example, it can include electrolyte or solid electrolyte, necessary connection lines, etc., which can be carried out with reference to conventional technologies. , I won’t repeat them here.
  • the pole cores encapsulated in the housing include a plurality of pole cores, and the plurality of pole cores are divided into a plurality of pole core groups, and the pole core groups are connected in series. Specifically, if there are 15 pole cores in the package and the shell, and every 5 pole cores are divided into a pole core group, the shell includes 3 pole core groups, and the 3 pole core groups are connected in series.
  • an encapsulation film is further provided between the housing and the pole core, and the pole core is encapsulated in the encapsulation film.
  • the present application provides a lithium ion battery.
  • the lithium ion battery includes an outer casing and a pole core housed in the outer shell, and the pole core includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer supported on the positive electrode current collector, and the positive electrode current collector satisfies the following conditions:
  • n is the number of layers of the positive electrode current collector
  • L is the size of the positive electrode current collector in the first direction
  • the unit of L is m
  • W is the size of the positive electrode current collector in the second direction
  • W The unit of is m
  • d 2 is the thickness of the positive electrode current collector
  • the unit of d 2 is m
  • ⁇ is the density of the positive current collector
  • the unit of ⁇ is kg/m 3
  • C p is the positive current collector
  • the unit of C p is J/(Kg ⁇ °C)
  • the first direction is parallel to the direction in which the current in the positive electrode current collector is drawn, and the second direction intersects the first direction.
  • the casing, the positive electrode sheet, the negative electrode sheet, and the separator involved in the lithium ion battery can all be consistent with the foregoing description, and will not be repeated here.
  • the present application provides a power battery module.
  • the power battery module includes at least one lithium-ion battery as described above. The possibility of thermal runaway and thermal diffusion of the power battery module is significantly reduced, and the use safety is significantly improved.
  • multiple lithium-ion batteries can be connected in series, parallel and their combination, or some lithium-ion batteries can be connected to form a module, and multiple modules can be further connected to form a power battery module.
  • the specific design and selection can be made according to actual needs, so I won’t describe it too much here.
  • the present application provides a battery pack.
  • the battery pack includes at least one of the aforementioned lithium ion battery or the aforementioned battery module.
  • the battery pack has higher safety and longer service life.
  • this application provides an electric vehicle.
  • the electric vehicle includes the aforementioned battery module or the aforementioned battery pack.
  • the electric vehicle has excellent safety and long service life.
  • the electric vehicle may also include the necessary structures and components of a conventional electric vehicle, such as the body, tires, transmitter, frame, interior trim, etc., which can be specifically carried out according to conventional technologies. I won't repeat them here.
  • this application provides an energy storage device.
  • the energy storage device includes the aforementioned power battery module or the aforementioned battery pack.
  • the energy storage device has a significantly reduced probability of thermal runaway and thermal diffusion, and has excellent safety and long service life.
  • a power battery module is used.
  • the power battery module is formed by a plurality of lithium ion batteries connected in series.
  • Each lithium ion battery is a laminated battery
  • the anode current collector is aluminum foil
  • the cathode material is lithium iron phosphate.
  • the negative electrode current collector is copper foil
  • the negative electrode material is graphite
  • the separator is a polyolefin separator
  • the electrolyte is a lithium hexafluorophosphate organic electrolyte
  • the lithium ion battery is a rectangular battery with a length of 1000 mm.
  • the acupuncture experiment was conducted through the method of "GB/T 31485-2015 Safety Requirements and Test Methods for Power Batteries for Electric Vehicles".
  • the specific acupuncture procedures are as follows:
  • the single battery At room temperature, the single battery is first discharged with a current of 1C+0.2C to a final voltage of 2.0V, left for 30min, and then charged with a current of 1C+0.2C to 3.8V.
  • Acupuncture use diameter
  • the high-temperature resistant steel needle with a taper of 45° ⁇ 60° the needle surface is smooth, free of rust, oxide layer and oil
  • the steel needle stays in the battery for observation for 1 hour.

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Abstract

本申请提供了锂离子电池、动力电池模组、电池包、电动汽车和储能装置，该锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，定义正极集流体、正极材料层、负极片和分隔件中熔点最低者为有效部件，所述有效部件满足条件（aa）。

Description

锂离子电池、动力电池模组、电池包、电动汽车和储能装置 技术领域
本申请涉及锂离子电池技术领域，具体的，涉及锂离子电池、动力电池模组、电池包、电动汽车和储能装置。
背景技术
锂离子电池独特的特点在越来越多的领域得到了应用，尤其是动力电池方面，更是飞速发展。当用锂电池作为电动汽车主要的能量供给来源，尤其是近年来三元电池的大范围使用，使得锂离子动力电池热失控(电池放热连锁反应引起电池自温升速率急剧变化的过热、起火、爆炸现象)发生起火、爆炸的事故时有发生，而电池包中，一旦一个电池热失控又常常会触发电池包或系统中相邻电池的热失控，即为热扩散，从而造成整个电池包失控，产生起火爆炸等严重后果。目前，锂离子电池使用安全性仍面临挑战。
申请内容
本申请旨在至少在一定程度上解决相关技术中的技术问题之一。为此，本申请的一个目的在于提出一种具有能够有效改善热失控问题、提高使用安全性的锂离子电池。
在本申请的一个方面，本申请提供了一种锂离子电池。根据本申请的实施例，该锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，定义正极集流体、正极材料层、负极片和分隔件中熔点最低者为有效部件，所述有效部件满足以下条件：
Figure PCTCN2021095497-appb-000001
其中，n为所述有效部件的层数，L为所述有效部件在第一方向上的尺寸，L的单位为m，W为所述有效部件在第二方向上的尺寸，W的单位为m，d 2为所述有效部件的厚度，d 2的单位为m，ρ为所述有效部件的密度，ρ的单位为kg/m 3，C p为所述有效部件的比热容(本文中热熔、比热容和比热可以互换使用)，C p的单位为J/(Kg·℃)(即J/(Kg·K)，本文中J/(Kg·℃)与J/(Kg·K)可以互换使用)，所述第一方向与所述有效部件中的电流引出的方向平行，所述第二方向与所述第一方向相交。该锂离子电池中，通过对极芯部件的层数、不同的尺寸等参数进行合理的优化和设计，极大的提高了电池安全性，满足上述条件的锂离子电池，有效降低了电池热失控或热扩散的发生的几率，避免了电池产热对 相邻电池或外部产生损伤。
在本申请的另一个方面，本申请提供了一种锂离子电池。根据本申请的实施例，该锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，所述正极集流体满足以下条件：
Figure PCTCN2021095497-appb-000002
其中，n为所述正极集流体的层数，L为所述正极集流体在第一方向上的尺寸，L的单位为m，W为所述正极集流体在第二方向上的尺寸，W的单位为m，d 2为所述正极集流体的厚度，d 2的单位为m，ρ为所述正极集流体的密度，ρ的单位为kg/m 3，C p为所述正极集流体的比热容，C p的单位为J/(Kg·℃)，所述第一方向与所述正极集流体中的电流方向平行，所述第二方向与所述第一方向相交。该锂离子电池中，通过对正极集流体的层数、不同方向的尺寸等参数进行合理的优化和设计，极大的提高了电池安全性，满足上述条件的锂离子电池，有效降低了电池热失控或热扩散的发生的几率，避免了电池产热对相邻电池或外部产生损伤。
在本申请的另一方面，本申请提供了一种动力电池模组或电池包。根据本申请的实施例，该动力电池模组或电池包包括至少一个前面所述的锂离子电池。该动力电池模组发生热失控和热扩散的可能性明显降低，使用安全性显著提高。
在本申请的又一方面，本申请提供了一种电动汽车或储能装置。根据本申请的实施例，该电动汽车或储能装置包括前面所述的动力电池模组或前面所述的电池包。该电动汽车具有极好的安全性和较长的使用寿命。
附图说明
图1是本申请一个实施例的层叠状极芯的结构示意图。
图2是图1中一个正极片沿A-A线的剖面结构示意图。
图3是本申请一个实施例的构成卷绕状极芯的层叠体展平状态的结构示意图。
图4是本申请一个实施例的卷绕状极芯的结构示意图。
图5是本申请一个实施例的卷绕状极芯的结构示意图。
图6是图4和图5中一个卷绕段的平面结构示意图。
图7是图6中沿B-B线的剖面结构示意图。
图8是本申请另一个实施例的一个卷绕段的平面结构示意图。
具体实施方式
下面详细描述本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
在本申请的一个方面，本申请提供了一种锂离子电池。根据本申请的实施例，该锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，定义正极集流体、正极材料层、负极片和分隔件中熔点最低者为有效部件，所述有效部件满足以下条件：
Figure PCTCN2021095497-appb-000003
其中，n为所述有效部件的层数，L为所述有效部件在第一方向上的尺寸，L的单位为m，W为所述有效部件在第二方向上的尺寸，W的单位为m，d 2为所述有效部件的厚度，d 2的单位为m，ρ为所述有效部件的密度，ρ的单位为kg/m 3，C p为所述有效部件的比热容，C p的单位为J/(Kg·℃)，所述第一方向与所述有效部件中的电流引出的方向平行，所述第二方向与所述第一方向相交。该锂离子电池中，通过对极芯部件的层数、不同方向的尺寸等参数进行合理的优化和设计，极大的提高了电池安全性，满足上述条件的锂离子电池，有效降低了电池热失控或热扩散的发生的几率，同时无任何新增零部件，不改变电池系统设计，无额外成本增加。另外，本申请的锂离子电池中，A值越高，电池安全性相对降低，超过500后，电池内部结构设计使得产热无法及时排出，电池安全性降低；而A值越低，电池空间浪费严重且电池形状不利于电池在电动汽车内部排布。
一些实施例中，所述有效部件满足以下条件：
Figure PCTCN2021095497-appb-000004
由此，锂离子电池的安全性进一步提升，发生热失控和热扩散的概率进一步降低。
具体的，本申请的发明人基于以下两个方程和模型为基础进行合理设计和优化，得到了本申请的锂离子电池，具体如下：
按照一般热平衡方程：
Figure PCTCN2021095497-appb-000005
边界条件为：
Figure PCTCN2021095497-appb-000006
其中ρ表示体系中预定成分的密度，T代表系统达到热平衡时的温度，t表示时间，Cp代表预定成分的比热，k表示热传导系数，Q表示产生的热量，h表示外壳与空气的热系数，E表示电动势，U表示路端电压，I表示充放电电流，T surface表示系统表面温度，T room表示室温。
对于一维度热扩散模型有：
Figure PCTCN2021095497-appb-000007
其中，Q为t＝0的瞬时在x＝0点处给的一个热量，△T为在距离零点x＝R处的温度相对于室温的增值，ρ为热导体的密度，c为热导体比热容，δ为热导体厚度，α为热传导系数α＝k/(ρc)，k为热导体的导热系数，m 2＝2h/(kδ)。
基于上述方程和模型，结合发明人的实际研究经验，并遵循以下原则，发明人提出了本申请：热失控大多是因为电池内部短路所致，一旦短路，短路点的温度可迅速上升，从而引发电池的热失控，进而极易引起起火或爆炸，本申请的锂离子电池中，通过控制电池中有效部件的数量、尺寸、热力学等参数，使得在电池发生短路时快速使得短路点熔断，则切断了短路点，阻止了热量进一步产生，同时保证材料未达到失控点，从而可极大保证电池安全，进而避免了热失控现象的发生，大大提高了电池的安全性。
具体的，本申请的锂离子电池可以为液态电池、固态电池或者聚合物电池，对于液体电池和聚合物电池，可以包括正极片、负极片和位于正极片和负极片之间的隔离膜(即分隔件)，当然，极芯还包括电解液，而对于固体电池，则包括正极片、负极片和位于正极片和负极片之间的固态电解质层(即分隔件)。
一些实施例中，负极片可包括负极集流体和负载在负极集流体上的负极材料层；在该种实施方式中，定义正极集流体、正极材料层、负极集流体、负极材料层和分隔件中熔点最低者为有效部件。
另一些实施例中，负极片可以为锂箔、锂带，在该种实施方式中，定义正极集流体、正极材料层、锂箔(或锂带)和分隔件中熔点最低者为有效部件。
又一些实施例中，负极片可以包括多孔集流体以及沉积在多孔结构中的负极活性材料。在该种实施例方式中，定义正极集流体、正极材料层、多孔集流体和分隔件中熔点最低者为有效部件。
另外，正极片和负极片上分别设有用于引出电流的正极极耳和负极极耳，具体的，正极片和负极片中的一个边上分别引出正极极耳和负极极，且正极极耳和负极极耳可以同侧设置(参照图8)，也可以相对设置(参照图1和图7)，极耳引出的方向即为电流引出的方向。在极芯中，可以多个正极片10和负极片20依次交替层叠设置构成层叠状极芯(结构示意图参照图1)，相邻的正极片和负极片之间设有分隔件，也可以正极片、分隔件和负极片层叠设置，然后卷绕构成卷绕状极芯(结构示意图参照图2)，具体方式均可参照常规技术进行，在此不再过多描述。
需要说明的是，对于层叠状极芯，具体参照图1，包括多个交替层叠设置的正极片10和负极片20，相邻的正极片10和负极片20之间设有分隔件(图中未示出)此时，n为有效部件层叠的数量，L是指一个有效部件在第一方向上的尺寸，W是指一个有效部件在第二方向上的尺寸，d 2为一个有效部件的厚度(沿层叠方向的尺寸)。
对于卷绕状极芯，具体参照图3、图4、图5、图6和图7，正极片10、负极片20和分隔件40层叠设置后进行卷绕，具体的，定义依次层叠设置的正极片10、分隔件40和负极片20为层叠体30，层叠体30划分为多个依次相连的卷绕段31(参照图3)，卷绕状态时，多个卷绕段31依次层叠设置(参照图4)，此时，n为卷绕段的数量(或者称为有效部件卷绕圈数的两倍)，L为一个而卷绕段中的效部件在第一方向上的尺寸，W为多个卷绕段中有效部件在第二方向上的尺寸的平均值，d 2为一个卷绕段中有效部件的厚度。
另外，还需要说明的是，本文中描述的第二方向与第一方向相交，具体是指：第一方向与第二方向之间的夹角的可以大于0度小于等于90度，一些具体实施例中，第一方向与第二方向之间的夹角具体可以为90度，即第一方向和第二方向垂直。
具体的，根据锂离子电池中各部件常用的材料，通常正极集流体的熔点较低，热失控时正极集流体熔断时，电极材料未失控，可极大保证电池安全。而导致热失控的电池内部的多种短路形式中，如正负极材料之间短路、正极集流体与负极片之间短路、负极集流体与正极片之间短路等，其中正极集流体与负极材料接触短路后，产生的热量是最大的，实验发现一旦短路，短路点的温度可迅速上升到200℃，从而引发材料的失控，进而极易引起起火或爆炸。本申请的锂离子电池中，以保证短路点熔断时，材料未达到失控点为基本目的，选择正极集流体作为有效部件，可以有效避免热失控和热扩散，进而大大提高电池的使用安全性。
下面以正极集流体为有效部件，进一步详细描述本申请的方案。
根据本申请的实施例，参照图1和图2，正极片10的一个边上还引出有正极极耳11，具体的，正极极耳引出的方向即为正极集流体中的电流引出的方向，因此，此时第一方向 与正极极耳引出的方向平行。
具体的，正极极耳可以是焊接在正极集流体上，也可以由正极集流体裁切形成，即正极极耳与正极集流体一体成型，需要说明的是，无论正极极耳以哪种方式从正极集流体上引出，正极集流体沿第一方向的尺寸均不包括正极极耳的沿第一方向的尺寸。可以理解，负极极耳的情况可以与正极极耳相同，在此不再一一赘述。
进一步的，第二方向可以根据实际情况进行选择，一些具体实施例中，第二方向与第一方向垂直。由此，与上述条件匹配度更高，发生热失控和热扩散的概率更低，电池的安全性更好。
一些实施例中，参照图1和图2，锂离子电池中的极芯可以为层叠状极芯，所述层叠状极芯包括多个交替层叠设置的正极片10和负极片20，n为多个所述正极片10中的所述正极集流体12的数量，L为一个正极片10中的所述正极集流体12在所述第一方向上的尺寸，W为一个正极片10中的所述正极集流体12在所述第二方向上的尺寸，d 2为一个正极片10中的所述正极集流体12的厚度，图1和图2所示极芯中正极集流体的层数n＝3，L、W和d 2如图中所示。
另一些实施例中，锂离子电池中的极芯可以为卷绕状极芯，参照图3至图7，所述卷绕状极芯由划分为多个依次相连的卷绕段31的层叠体30卷绕构成，在所述卷绕状极芯中，多个卷绕段31层叠设置，每个所述卷绕段31包括依次层叠设置的正极片10、分隔件40和负极片20，n为所述卷绕段31的数量，L为一个所述卷绕段31中的所述正极集流体12在所述第一方向上的尺寸，W为多个所述卷绕段31中的所述正极集流体12在所述第二方向上的尺寸的平均值，d 2为一个所述卷绕段31中的所述正极集流体12的厚度，具体的，图3至图7所示卷绕状极芯中，n＝5，W＝(W1+W2+W3+W4+W5)/5，L＝L1。
一些实施例中，所述正极集流体的材料包括铝，如铝箔，负极集流体为铜箔。在对电池各参数(有效部件层数、不同方向尺寸、厚度、比热容等参数)做出合理设计的情况下，配合以铝的低熔点可以有效保证在短路点熔断时，材料未失控，从而避免了热失控和热扩散，极大的保证了锂离子电池的安全性。
一些具体实施例中，正极集流体的厚度d 2取值范围可以在6μm-15μm之间(具体如6μm、7μm、8μm、9μm、10μm、11μm、12μm、13μm、14μm、15μm等)；正极集流体的密度ρ取值范围在2000kg·m -3～3000kg·m -3之间(具体如2000kg·m -3、2100kg·m -3、2200kg·m -3、2300kg·m -3、2400kg·m -3、2500kg·m -3、2600kg·m -3、2700kg·m -3、2800kg·m -3、2900kg·m -3、3000kg·m -3等)；正极集流体的比热容C p取值范围在800J·kg -1·K -1-900J·kg -1·K -1之间(具体如800J·kg -1·K -1、810J·kg -1·K -1、820J·kg -1·K -1、830J·kg -1·K -1、840J·kg -1·K -1、850J·kg -1·K -1、 860J·kg -1·K -1、870J·kg -1·K -1、880J·kg -1·K -1、890J·kg -1·K -1、900J·kg -1·K -1等)具体的，d 2、ρ、C p是正极集流体的热特征属性，当三者的乘积越大时，短路点熔断越困难，失控的风险也就越大，而在上述范围内，可以有效保证在短路点熔断时，材料未失控，更好的保证了电池的安全性。
一些具体实施例中，正极集流体的层数n取值范围在1-150之间(具体如1、10、20、30、40、50、60、70、80、90、100、110、120、130、140、150等)。n是正极集流体的总的短路层数，当n越大时，短路放出来的热量就越大，失控风险也就越大，在上述范围内，可以保证电池的能量密度，同时失控风险较低。
一些具体实施例中，正极集流体在第一方向上的尺寸L和正极集流体在第二方向上的尺寸W的比值L/w取值范围在0-30之间(具体如1、2、5、8、10、12、15、18、20、22、25、28、30等)。L/w决定电池内部的欧姆电阻，L/w越大，欧姆电阻越大，电池产热越大，同时L/w决定正极集流体的阻抗大小，其取值越大，电芯在短路点熔断前电芯的总产热就越大，失控风险也越大。而在上述范围内，可以保证电池的正常工作，同时失控风险较低，产热可以控制在一定的范围内，从而能避免电池产热对相邻电池或外部产生损伤。
一些具体实施例中，本申请的锂离子电池中，正极材料层和负极活性材料的具体种类没有特别限制，本领域技术人员可以根据实际需要灵活选择和调整。一些具体实施例中，正极材料层可以包括磷酸铁锂材料。一些具体实施例中，负极片包括负极活性材料，负极活性材料可以包括石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料和钛酸锂中的至少一种。由此，与上述热失控条件的匹配性更好，锂离子电池热失控的风险更低。
一些具体实施例中，所述锂离子电池可以为长方形电池；进一步的，所述锂离子电池的长度可以为500mm-2500mm(具体如500mm、800mm、1000mm、1500mm、1800mm、2000mm、2200mm、2500mm等)。具体可以为具有一定强度外壳(优选金属外壳)的锂离子电池。该形状和尺寸范围内的锂离子电池，可以很好地与上述热失控条件的相匹配性更好，通过上述热失控条件可以比较精准的控制锂离子电池具有较低的热失控的风险更低。
可以理解，除了前面描述的部件之外，锂离子电池还可以具有常规锂离子电池必要的结构和部件，例如可以包括电解液或固体电解质、必要的连接线路等等，具体均可参照常规技术进行，在此不再过多赘述。
一些具体实施例中，封装于所述外壳内的极芯包括多个，多个所述极芯分成若干个极芯组，所述极芯组间串联。具体如封装与外壳内的极芯为15个，每5个极芯划分为一个极芯组，则外壳内包括3个极芯组，该3个极芯组之间串联连接。
一些具体实施例中，所述外壳与所述极芯之间还设有封装膜，所述极芯封装在封装膜内。由此，可以更好地保护极芯，避免破损等问题，提供电池的安全性，延长电池的使用寿命。
在本申请的另一方面，本申请提供了一种锂离子电池。根据本申请的实施例，所述锂离子电池包括外壳以及收纳在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，所述正极集流体满足以下条件：
Figure PCTCN2021095497-appb-000008
其中，n为所述正极集流体的层数，L为所述正极集流体在第一方向上的尺寸，L的单位为m，W为所述正极集流体在第二方向上的尺寸，W的单位为m，d 2为所述正极集流体的厚度，d 2的单位为m，ρ为所述正极集流体的密度，ρ的单位为kg/m 3，C p为所述正极集流体的比热容，C p的单位为J/(Kg·℃)，所述第一方向与所述正极集流体中的电流引出的方向平行，所述第二方向与所述第一方向相交。
可以理解，该锂离子电池中涉及的外壳、正极片、负极片和分隔件均可以与前文描述一致，在此不再一一赘述。
在本申请的另一方面，本申请提供了一种动力电池模组。根据本申请的实施例，该动力电池模组包括至少一个前面所述的锂离子电池。该动力电池模组发生热失控和热扩散的可能性明显降低，使用安全性显著提高。
具体的，该动力电池模组中，多个锂离子电池可以按照串联、并联及其结合的方式进行连接，也可以部分锂离子电池连接构成模块，多个模块进一步连接构成动力电池模组，当然，具体可以根据实际需要进行设计和选择，在此不再过多描述。
在本申请的再一方面，本申请提供了一种电池包。根据本申请的实施例，该电池包包括至少一个前面所述的锂离子电池或前面所述的电池模组。该电池包具有较高的使用安全性和较长的使用寿命。
在本申请的又一方面，本申请提供了一种电动汽车。根据本申请的实施例，该电动汽车包括前面所述的电池模组或前面所述的电池包。该电动汽车具有极好的安全性和较长的使用寿命。
可以理解，除了前面描述的动力电池模组，该电动汽车还可以包括常规电动汽车必要的结构和部件，如车身、轮胎、发送机、车架，内饰等等，具体可以根据常规技术进行，在此不再过多赘述。
在本申请的另一方面，本申请提供了一种储能装置。根据本申请的实施例，该储能装 置包括前面所述的动力电池模组或前面所述的电池包。该储能装置发生热失控和热扩散的概率明显降低，具有极好的安全性和较长的使用寿命。
下面详细描述本申请的实施例。
下面实施例和对比例中采用动力电池模组，动力电池模组由多个锂离子电池串联形成其中，每个锂离子电池为叠片电池，正极集流体为铝箔，正极材料为磷酸铁锂材料，负极集流体为铜箔，负极材料为石墨，隔离膜为聚烯烃隔离膜，电解液为六氟磷酸锂有机电解液，锂离子电池为长方形电池，长度为1000mm。
性能测试：
针刺实验通过《GB/T 31485-2015电动汽车用动力蓄电池安全要求及试验方法》的方法进行试验，具体针刺程序如下：
充电：室温下，单体蓄电池先以1C+0.2C电流放电至终止电压2.0V，搁置30min，然后以1C+0.2C电流充电至3.8V。
针刺：用直径
Figure PCTCN2021095497-appb-000009
锥度45°～60°的耐高温钢针(针表面光洁，无锈蚀、氧化层及油污)，以(25±5)mm/s的速度，从垂直于蓄电池极板方向贯穿，贯穿位置宜靠近所刺面的几何中心，钢针停留在蓄电池中观察1h。
各实施例和对比例的参数和测试结果如下表所示：
Figure PCTCN2021095497-appb-000010
Figure PCTCN2021095497-appb-000011
其中，
Figure PCTCN2021095497-appb-000012
从测试结果可以看出，当A大于500时，电池无法通过针刺实验，发生热失控，而A小于500且大于1时，电池可以通过针刺实验，不会发生热失控，说明满足本申请条件的锂离子电池具有更低的失控风险和更高的安全性。
在本说明书的描述中，参考术语“一个实施例”、“一些实施例”、“示例”、“具体示例”、或“一些示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本申请的至少一个实施例或示例中。在本说明书中，对上述术语的示意性表述不必须针对的是相同的实施例或示例。而且，描述的具体特征、结构、材料或者特点可以在任一个或多个实施例或示例中以合适的方式结合。此外，在不相互矛盾的情况下，本领域的技术人员可以将本说明书中描述的不同实施例或示例以及不同实施例或示例的特征进行结合和组合。
尽管上面已经示出和描述了本申请的实施例，可以理解的是，上述实施例是示例性的，不能理解为对本申请的限制，本领域的普通技术人员在本申请的范围内可以对上述实施例进行变化、修改、替换和变型。

Claims (14)

  1. 一种锂离子电池，所述锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极集流体以及负载在所述正极集流体上的正极材料层，其特征在于，定义正极集流体、正极材料层、负极片和分隔件中熔点最低者为有效部件，所述有效部件满足以下条件：
    Figure PCTCN2021095497-appb-100001
    其中，n为所述有效部件的层数，L为所述有效部件在第一方向上的尺寸，L的单位为m，W为所述有效部件在第二方向上的尺寸，W的单位为m，d 2为所述有效部件的厚度，d 2的单位为m，ρ为所述有效部件的密度，ρ的单位为kg/m 3，C p为所述有效部件的比热容，C p的单位为J/(Kg·K)，所述第一方向与所述有效部件中的电流引出的方向平行，所述第二方向与所述第一方向相交。
  2. 根据权利要求1所述的锂离子电池，其特征在于，所述有效部件满足以下条件：
    Figure PCTCN2021095497-appb-100002
  3. 根据权利要求1或2所述的锂离子电池，其特征在于，所述有效部件为正极集流体。
  4. 根据权利要求1～3中任一项所述的锂离子电池，其特征在于，所述正极集流体的一个边上引出正极极耳，所述第一方向与所述正极极耳引出的方向平行。
  5. 根据权利要求1～4中任一项所述的锂离子电池，其特征在于，所述第二方向与所述第一方向垂直。
  6. 根据权利要求1～5中任一项所述的锂离子电池，其特征在于，所述正极集流体满足以下条件的至少之一：
    所述正极集流体的厚度d 2取值范围在6μm-15μm之间；
    所述正极集流体的密度ρ取值范围在2000kg·m -3～3000kg·m -3之间；
    所述正极集流体的比热容C p取值范围在800J·kg -1·K -1-900J·kg -1·K -1之间；
    所述正极集流体的层数n取值范围在1-150之间；
    所述正极集流体在第一方向上的尺寸L和所述正极集流体在第二方向上的尺寸W的比值L/w取值范围在0-30之间。
  7. 根据权利要求1～6中任一项所述的锂离子电池，其特征在于，所述正极集流体的材料包括铝。
  8. 根据权利要求1～7中任一项所述的锂离子电池，其特征在于，所述极芯满足以下条件的至少之一：
    所述正极材料层包括磷酸铁锂材料；
    所述负极片包括负极活性材料，所述负极活性材料包括石墨、软碳、硬碳、碳纤维、中间相碳微球、硅基材料、锡基材料和钛酸锂中的至少一种。
  9. 根据权利要求1～8中任一项所述的锂离子电池，其特征在于，所述锂离子电池满足以下条件的至少之一：
    所述锂离子电池为长形电池；
    所述锂离子电池的长度为500mm-2500mm。
  10. 一种锂离子电池，所述锂离子电池包括外壳以及封装在所述外壳内的极芯，所述极芯包括正极片、负极片以及位于所述正极片和所述负极片之间的分隔件，所述正极片包括正极片集流体以及负载在所述正极集流体上的正极材料层，其特征在于，所述正极集流体满足以下条件：
    Figure PCTCN2021095497-appb-100003
    其中，n为所述正极集流体的层数，L为所述正极集流体在第一方向上的尺寸，L的单位为m，W为所述正极集流体在第二方向上的尺寸，W的单位为m，d 2为所述正极集流体的厚度，d 2的单位为m，ρ为所述正极集流体的密度，ρ的单位为kg/m 3，C p为所述正极集流体的比热容，C p的单位为J/(Kg·℃)，所述第一方向与所述正极集流体中的电流引出的方向平行，所述第二方向与所述第一方向相交。
  11. 根据权利要求1～10中任一项所述的锂离子电池，其特征在于，封装于所述外壳内的极芯包括多个，多个所述极芯分成若干个极芯组，所述极芯组间串联。
  12. 根据权利要求1～11中任一项所述的锂离子电池，其特征在于，所述外壳与所述极芯之间还设有封装膜，所述极芯封装在封装膜内。
  13. 一种动力电池模组或电池包，其特征在于，包括至少一个权利要求1～12中任一项所述的锂离子电池。
  14. 一种电动汽车或储能装置，其特征在于，包括权利要求13所述的动力电池模组或电池包。
PCT/CN2021/095497 2020-05-29 2021-05-24 锂离子电池、动力电池模组、电池包、电动汽车和储能装置 WO2021238858A1 (zh)

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CN101369671A (zh) * 2007-08-15 2009-02-18 日产自动车株式会社 电池和包含该电池的电池组以及包括该电池组的车辆

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