WO2022021135A1 - 电池模组、电池包、装置以及电池模组的制造方法和制造设备 - Google Patents

电池模组、电池包、装置以及电池模组的制造方法和制造设备 Download PDF

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WO2022021135A1
WO2022021135A1 PCT/CN2020/105474 CN2020105474W WO2022021135A1 WO 2022021135 A1 WO2022021135 A1 WO 2022021135A1 CN 2020105474 W CN2020105474 W CN 2020105474W WO 2022021135 A1 WO2022021135 A1 WO 2022021135A1
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Prior art keywords
battery
type
ved
battery cells
battery module
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PCT/CN2020/105474
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English (en)
French (fr)
Inventor
梁成都
李全国
叶永煌
刘倩
金海族
李伟
Original Assignee
宁德时代新能源科技股份有限公司
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Priority to CN202080054687.0A priority Critical patent/CN114342173B/zh
Priority to EP20947010.3A priority patent/EP4020691B1/en
Priority to PCT/CN2020/105474 priority patent/WO2022021135A1/zh
Publication of WO2022021135A1 publication Critical patent/WO2022021135A1/zh
Priority to US17/970,603 priority patent/US20230231249A1/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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • H01M50/207—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape
    • H01M50/209—Racks, modules or packs for multiple batteries or multiple cells characterised by their shape adapted for prismatic or rectangular cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/204—Racks, modules or packs for multiple batteries or multiple cells
    • 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
    • H01M10/04—Construction or manufacture in general
    • H01M10/0404—Machines for assembling 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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/249—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders specially adapted for aircraft or vehicles, e.g. cars or trains
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/20—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders
    • H01M50/267—Mountings; Secondary casings or frames; Racks, modules or packs; Suspension devices; Shock absorbers; Transport or carrying devices; Holders having means for adapting to batteries or cells of different types or different sizes
    • 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
    • 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 belongs to the technical field of energy storage devices, and specifically relates to a battery module, a battery pack, a device, and a manufacturing method and manufacturing equipment for the battery module.
  • a first aspect of the present application provides a battery module, which includes a battery unit, the battery unit includes n first type battery cells and m second type battery cells, n ⁇ 1, m ⁇ 1, so The n first-type battery cells and m second-type battery cells are arranged in an arrangement and satisfy:
  • VED 1 VED 2
  • VED 1 represents the volume energy density of the first type of battery cell, in Wh/L
  • VED 2 represents the volumetric energy density of the second type of battery cell, in Wh/L,
  • ⁇ F 1 represents the rate of change of the expansion force of the first type of battery cell, the unit is Newton/circle,
  • ⁇ F 2 represents the rate of change of the expansion force of the second type of battery cells, in Newtons/circle.
  • the first type of battery cells with higher volumetric energy density and higher expansion force change rate are assembled with the second type of battery cells with lower volumetric energy density and lower expansion force change rate, and at the same time Controlling the change rate of the expansion force of the first type of battery cells and the change rate of the expansion force of the second type of battery cells to satisfy a specific relationship, effectively reducing the change of the expansion force of the battery cells in the battery module during the cycle charge and discharge process
  • the average rate of the battery module improves the stability of the ion transport interface between the pole pieces in each battery cell and between the pole piece and the separator during the cyclic charge and discharge process, thereby improving the overall long-term cycle life of the battery module. , the capacity that can be exerted by a single full charge is still high in the middle and late stages of the service life.
  • 0.5 ⁇ F 1 ⁇ ( ⁇ F 1 ⁇ n+ ⁇ F 2 ⁇ m)/(n+m) ⁇ 0.65 ⁇ F 1 is beneficial to make the battery module better take into account both higher volumetric energy density and higher cycle life.
  • the ⁇ F 1 may be 6N/circle to 15N/circle, 7N/circle to 14N/circle, 7N/circle to 13N/circle, 7.3N/circle to 12.6N/circle /circle, or 8.2N/circle to 12.6N/circle.
  • the ⁇ F 2 may be 0.9 N/circle to 4.5 Newtons/circle, 1.4 Newtons/circle to 4 Newtons/circle, 1.2 Newtons/circle to 3.5 Newtons/circle, 1.2 Newtons/circle to 2.3 Newtons/circle, or 1.4 Newtons/circle Loop ⁇ 1.6 N/lap.
  • the cyclic expansion force in the battery module can be further reduced, thereby further improving The cycle life of the battery module; and it is also beneficial to improve the volume energy density of the battery module.
  • the safety performance of the battery module can also be improved.
  • the rate of change of the expansion force of the battery cell is at 25° C., at a rate of 0.33C 0 (C 0 represents the nominal capacity of the battery cell), at the upper limit of the battery cell Within the range of cut-off voltage and lower limit cut-off voltage, the average expansion force change after 500 cycles of charge and discharge is ⁇ F/500, the ⁇ F is measured by the sensor of the detection device at the 500th cycle of the battery cell and at the beginning of the cycle The change value of the pressure of the battery cell.
  • the nominal capacity C1 of the first type of battery cells and the nominal capacity C2 of the second type of battery cells satisfy: 0.9 ⁇ C1/C2 ⁇ 1.1.
  • the nominal capacity C1 of the first type of battery cell and the nominal capacity C2 of the second type of battery cell are within the above ranges, it can ensure that the external energy output of the battery module or battery pack is relatively high.
  • the volumetric energy density of the first type of battery cell is higher than that of the second type of battery cell, the volume difference between the first type of battery cell and the second type of battery cell is within a certain range, which is important for improving the battery model.
  • the expansion force effect of the whole group or battery pack is more pronounced.
  • the number of the battery cells of the first type that are continuously arranged in the battery cells does not exceed n/2. Further, it may not exceed n/3.
  • the number of the first type of battery cells that are continuously arranged in the battery cells is no more than 5, or no more than 3.
  • the number of the battery cells of the first type that are continuously arranged in the battery cells may be 1-3, 2-3, or 1-2, etc. Disposing the second type of battery cells every appropriate number of the first type of battery cells can further improve the effect of improving the cyclic expansion force of the battery module, thereby further improving the cycle life of the battery module.
  • the number n of the first type of battery cells and the number m of the second type of battery cells may satisfy: 5 ⁇ n+m ⁇ 30.
  • the battery module may satisfy (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.7 ⁇ VED 1 .
  • (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) represents the average volumetric energy density of the battery cells in the battery module, when (VED 1 ⁇ n+VED 2 ⁇ m)/( When n+m) satisfies the above relationship, the assembled battery module can ensure lower cyclic expansion force, effectively improve long-term cycle life, and at the same time have higher volumetric energy density.
  • the battery module may satisfy VED 2 ⁇ m/(VED 1 ⁇ n+VED 2 ⁇ m) ⁇ 100% ⁇ 65%.
  • the battery module can satisfy VED 2 ⁇ m/(VED 1 ⁇ n+VED 2 ⁇ m) ⁇ 100% ⁇ 10%.
  • the battery module of the present application when the above relationship is further satisfied between the volumetric energy density of the first type of battery cell and the volumetric energy density of the second type of battery cell, the battery module can simultaneously take into account a higher cycle life and higher volumetric energy density.
  • the volume energy density VED of the battery module is greater than or equal to 300Wh/L.
  • VED ⁇ 350Wh/L.
  • the battery module not only has a high cycle life, but also has a high volumetric energy density.
  • the first type of battery cell includes a first negative electrode plate, and the first negative electrode plate includes a first negative electrode film layer containing a first negative electrode active material, wherein the first negative electrode active material Including one or more of artificial graphite and natural graphite, the surface density CW 1 of the first negative electrode film layer is 9.70 mg/cm 2 to 11.68 mg/cm 2 , and the compaction density of the first negative electrode film layer PD 1 is 1.35 g/cm 3 to 1.65 g/cm 3 .
  • the first type of battery cell adopts the first negative pole piece, which can have a relatively high energy density and a low cycle expansion force, so that the cycle expansion force of the battery module using the same is relatively low.
  • the volume expansion of the negative pole piece is small, which effectively improves the structural stability of the negative electrode active material under the action of external force. Therefore, under the premise of high energy density, the battery module has a high cycle life, and a single charge and discharge of the battery module can still exert a large capacity in the middle and late stages of the service life of the battery module.
  • CW 1 may be 10.38 mg/cm 2 to 11.36 mg/cm 2 .
  • PD 1 may be 1.40 g/cm 3 to 1.60 g/cm 3 , or 1.45 g/cm 3 to 1.55 g/cm 3 .
  • the first type of battery cell includes a first positive electrode plate, the first positive electrode electrode plate includes a first positive electrode active material, and the first positive electrode active material includes lithium represented by formula (I) transition metal oxides,
  • M is selected from Mn, Fe, Cr, Ti, Zn, V, One or more of Al, Zr and Ce, and A is selected from one or more of S, F, Cl and I.
  • the first type of battery cells can obtain higher energy density, thereby enabling the battery module to obtain higher energy density.
  • the first positive electrode active material includes single particles with a volume average particle diameter D v 50 of 2 ⁇ m to 8 ⁇ m.
  • the single particle is included in the first positive electrode active material, which can further improve the cycle life of the battery module.
  • the number of the first positive electrode active material having a single particle form accounts for ⁇ 40%.
  • the first positive electrode active material contains more single particles, which can further improve the cycle life of the battery module.
  • the second type of battery cell includes a second negative electrode plate
  • the second negative electrode plate includes a second negative electrode film layer containing a second negative electrode active material, wherein the second negative electrode active material At least one of artificial graphite and natural graphite is included
  • the areal density CW 2 of the second negative electrode film layer is 6.50 mg/cm 2 to 9.70 mg/cm 2
  • the compaction density PD 2 of the second negative electrode film layer It is 1.35g/cm 3 to 1.65g/cm 3 .
  • the second type of battery cell adopts the second negative pole piece, which can obtain a lower cyclic expansion force, so that the cycle expansion force of the battery module using it is lower.
  • the negative pole piece The volume expansion is small, which effectively improves the structural stability of the negative electrode active material under the action of external force. Therefore, the cycle life of the battery module as a whole can be improved, and a single charge and discharge of the battery module can still exert a large capacity in the middle and late stages of the service life of the battery module.
  • the second type of battery cells can also have higher energy density, so that the energy density of the battery module is also higher.
  • CW 2 may be 8.11 mg/cm 2 to 9.40 mg/cm 2 .
  • PD 2 may be 1.45 g/cm 3 to 1.60 g/cm 3 , or 1.45 g/cm 3 to 1.55 g/cm 3 .
  • the second type of battery cell includes a second positive electrode plate, the second positive electrode plate includes a second positive electrode active material, and the second positive electrode active material includes formula (II) of lithium-containing phosphates,
  • 0 ⁇ x2 ⁇ 1, 0 ⁇ y2 ⁇ 0.1, and M' is selected from one or more of transition metal elements and non-transition metal elements except Fe and Mn.
  • the second positive active material includes one or more of LiFePO 4 , LiMnPO 4 , LiMn 1-x3 Fe x3 PO 4 , and LiV 1- x3 Fe x3 PO 4 , wherein x3 independently satisfies 0 ⁇ x3 ⁇ 1.
  • the second active material contained in the second type of battery cells has better cycle stability, thereby facilitating the battery module to obtain a higher cycle life.
  • the second positive electrode active material includes single particles with a volume average particle diameter D v 50 of 800 nm ⁇ 1.5 ⁇ m.
  • the second positive electrode active material contains the single particle, which can improve the cycle life of the battery module.
  • the electrical connection manner of the first type of battery cells and the second type of battery cells at least includes series connection.
  • the electrical connection is series or a series/parallel combination.
  • the first type of battery cells and the second type of battery cells will perform the charging/discharging process synchronously.
  • the volume expansion changes of different types of battery cells are coordinated, which is conducive to predicting the overall volume expansion rate of the battery module in the design stage, and is more convenient to modulate the improvement of the cycle life of the battery module.
  • a second aspect of the present application provides a battery pack including the battery module according to the first aspect of the present application.
  • the battery pack of the present application includes the battery module, and thus has at least the same advantages as the battery module.
  • the battery pack includes two or more battery modules.
  • each battery module is a battery module according to the first aspect of the present application.
  • a third aspect of the present application provides a device comprising the battery module according to the first aspect of the present application or the battery pack according to the second aspect of the present application, the battery module or battery pack being used to provide power to the device or An energy storage unit for the device.
  • the device of the present application includes the battery module or battery pack, and thus has at least the same advantages as the battery module or battery pack.
  • a fourth aspect of the present application provides a method for manufacturing a battery module, comprising the following steps:
  • VED 1 VED 2
  • ⁇ F 1 > ⁇ F 2
  • VED 1 represents the volume energy density of the first type of battery cell, in Wh/L
  • VED 2 represents the volumetric energy density of the second type of battery cell, in Wh/L,
  • ⁇ F 1 represents the rate of change of the expansion force of the first type of battery cell, the unit is Newton/circle,
  • ⁇ F 2 represents the rate of change of the expansion force of the second type of battery cells, in Newtons/circle
  • the n battery cells of the first type and the m battery cells of the second type are arranged in an array to form the battery module.
  • the battery module using the manufacturing method of the present application can have a lower cycle expansion force, and thus can have a higher cycle life.
  • a fifth aspect of the present application provides a manufacturing equipment for a battery module, comprising:
  • a clip arm unit for obtaining n first-type battery cells and m second-type battery cells
  • VED 1 VED 2
  • ⁇ F 1 > ⁇ F 2
  • VED 1 represents the volume energy density of the first type of battery cell, in Wh/L
  • VED 2 represents the volumetric energy density of the second type of battery cell, in Wh/L,
  • ⁇ F 1 represents the rate of change of the expansion force of the first type of battery cell, the unit is Newton/circle,
  • ⁇ F2 represents the rate of change of the expansion force of the second type of battery cells, in Newtons/circle
  • the control unit is used for controlling the clamping arm unit and the assembling unit.
  • the battery module manufactured by the manufacturing equipment of the present application can have a lower cycle expansion force, and thus can have a higher cycle life.
  • FIG. 1 is a schematic diagram of an embodiment of a battery module.
  • FIG. 2 is a schematic diagram of another embodiment of a battery module.
  • FIG. 3 is a schematic diagram of an embodiment of a first type of battery cell or a second type of battery cell.
  • FIG. 4 is an exploded view of FIG. 3 .
  • FIG. 5 is a schematic diagram of an embodiment of a battery cell expansion force detection device.
  • FIG. 6 is a schematic view from another perspective of an embodiment of a battery cell expansion force detection device.
  • FIG. 7 is a schematic diagram of an embodiment of a battery pack.
  • FIG. 8 is an exploded view of FIG. 7 .
  • FIG. 9 is a schematic diagram of one embodiment of a device in which a battery module or battery pack is used as a power source.
  • FIG. 10 is a graph of the expansion force of the first type of battery cells as a function of the number of cycles in one embodiment.
  • 11 is a graph of the expansion force of the second type of battery cells as a function of the number of cycles in one embodiment.
  • any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with any other lower limit to form an unspecified range, and likewise any upper limit can be combined with any other upper limit to form an unspecified range.
  • every point or single value between the endpoints of a range is included within the range, even if not expressly recited.
  • each point or single value may serve as its own lower or upper limit in combination with any other point or single value or with other lower or upper limits to form a range not expressly recited.
  • positive electrode sheets made of high-gram capacity positive active materials such as lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide can be used, with high areal density and compaction density.
  • Graphite negative electrode sheet to prepare high energy density battery cells. Then a plurality of the battery cells are electrically connected to form a high energy density battery module, battery pack or energy storage system.
  • these high-energy-density battery cells often experience capacity fading during charge-discharge cycles, and the accelerated capacity fading of battery cells leads to shortened long-term cycle life of battery modules or battery packs. In the middle and late stages of life, the cruising range that can be achieved with a single charge and discharge shrinks.
  • the inventors found that when a plurality of battery cells are arranged to form a battery module or battery pack, the space utilization rate of the battery cell arrangement and the matching of electrical properties have an impact on the overall performance of the battery module or battery pack. Play also has a greater impact.
  • the internal pressure and expansion force become larger and larger. Due to the design of high-energy-density battery modules or battery packs, the residual volume of undisposed battery cells is often compressed, resulting in a small distance between battery cells.
  • the inventor of the present invention has made intensive research and proposed that a first type of battery cell with a higher volumetric energy density and a higher rate of change in expansion force can be reasonably combined with a second type of battery cell with a lower volumetric energy density and a lower rate of change in expansion force. It can effectively reduce the cyclic expansion force in the battery module or battery pack, and achieve the purpose of improving the cycle life of the battery module or battery pack under the premise of higher volumetric energy density.
  • the embodiments of the first aspect of the present application provide a battery module that can have a relatively high cycle life while having a relatively high volumetric energy density.
  • the battery module of the present application includes battery cells, the battery cells include n first type battery cells and m second type battery cells, n ⁇ 1, m ⁇ 1, the n first type battery cells and m second type battery cells are arranged in an arrangement and satisfy:
  • VED 1 VED 2
  • VED 1 represents the volume energy density of the first type of battery cell, in Wh/L
  • VED 2 represents the volumetric energy density of the second type of battery cell, in Wh/L,
  • ⁇ F 1 represents the rate of change of the expansion force of the first type of battery cell, the unit is Newton/circle,
  • ⁇ F 2 represents the rate of change of the expansion force of the second type of battery cells, in Newtons/circle.
  • the first type of battery cells can be formed by encapsulating the battery core and the electrolyte in an outer package.
  • the battery core can be formed by a stacking process or a winding process from the first positive pole piece, the separator and the first negative pole piece, wherein the separator is located between the first positive pole piece and the first negative pole piece to isolate the effect.
  • the first positive electrode active material is coated on the coated area of the first positive electrode sheet, and the positive electrode tabs can be formed by stacking a plurality of uncoated areas extending from the coated area of the first positive electrode sheet;
  • the negative electrode active material is coated on the coated area of the first negative electrode pole piece, and a plurality of uncoated areas extending from the coated area of the first negative electrode pole piece can be stacked to form negative electrode tabs.
  • the two tabs can be respectively electrically connected to corresponding electrode terminals (which can be arranged on the cover plate of the battery outer package) through the transfer sheet, so as to lead out the electric energy of the battery cells.
  • the first type of battery cell may be a hexahedral shape (eg, a rectangular parallelepiped, a rectangular parallelepiped, etc.) or a battery cell of other shapes.
  • a second type of battery cells may be formed by the second positive electrode tab, the separator, and the second negative electrode tab.
  • the second type of battery cells may be hexahedral shaped (eg, rectangular parallelepiped, rectangular parallelepiped, etc.) or battery cells of other shapes.
  • n first type battery cells and m second type battery cells are arranged in an arrangement
  • the groups are arranged in the longitudinal direction, and the two adjacent battery cells are large faces facing each other.
  • the large surface refers to the side (in terms of outer surface) with the largest area in the battery cell.
  • the large-surface expansion of a battery cell is relatively high, and two adjacent battery cells are arranged with large surfaces facing each other, which can effectively reduce the cycle expansion force of the battery module and improve the cycle life of the battery module.
  • the number n of the first type of battery cells and the number m of the second type of battery cells may be adjusted according to the application and capacity of the battery module.
  • the number of battery cells contained in the battery module can be one or several, and can be adjusted according to requirements.
  • the reason may be guessed as follows: because the interval between the battery cells in the battery module is usually small, even if a buffer pad is arranged between the battery cells, once the buffer pad is compressed to the limit, the battery cells will still be affected by the adjacent batteries. Squeeze and confinement of monomers. As the squeezing force received inside the battery cell increases, eventually the electrolyte between the positive and negative electrodes is squeezed out, and the pore structure of the separator is blocked, resulting in the difficulty of active ion transmission during charging and discharging, and the interface concentration polarization. increase, resulting in the degradation of the cycle performance of the battery cell.
  • the second type of battery cells by introducing the second type of battery cells and reasonably combining them with the first type of cells, it can play a continuous and effective buffering role between the first type of battery cells and reduce the expansion rate of the first type of battery cells.
  • the internal stress of the first type of battery cells is released, thereby effectively reducing the cyclic expansion force of the battery cells as a whole, and also ensuring the sufficient electrolyte inside the cells of the first type of battery cells and the second type of battery cells.
  • the infiltration improves the stability of the ion transport interface between the pole pieces in each battery cell and between the pole piece and the separator in the battery module, thereby improving the cycle life of the battery module.
  • the battery module have high safety performance.
  • ( ⁇ F 1 ⁇ n+ ⁇ F 2 ⁇ m)/(n+m) may be ⁇ 0.75 ⁇ F 1 , ⁇ 0.7 ⁇ F 1 , ⁇ 0.65 ⁇ F 1 , ⁇ 0.6 ⁇ F 1 , ⁇ 0.55 ⁇ F 1 , or ⁇ 0.5 ⁇ F 1 .
  • the cyclic expansion force in the battery module can be further improved, and the cycle life of the battery module can be further improved.
  • ( ⁇ F 1 ⁇ n+ ⁇ F 2 ⁇ m)/(n+m) may be ⁇ 0.3 ⁇ F 1 , ⁇ 0.4 ⁇ F 1 , ⁇ 0.45 ⁇ F 1 , ⁇ 0.5 ⁇ F 1 , or ⁇ 0.55 ⁇ F 1 .
  • the n first-type battery cells and m second-type battery cells in each battery cell may be arranged arbitrarily.
  • the m second-type battery cells are arranged between and/or at both ends of the n first-type battery cells.
  • the number of the first type of battery cells arranged in series in the battery cells does not exceed n/2. Further, there may be no more than n/3.
  • the number of the first type of battery cells that are continuously arranged in the battery unit is not more than 5, or not more than 3.
  • the number of the first type of battery cells that are continuously arranged in the battery cells may be 1-10, 1-8, 1-5, 1-3, 2-3, or 1-2. Disposing the second type of battery cells every appropriate number of the first type of battery cells can further reduce the cycle expansion force of the battery module, thereby further improving the cycle life of the battery module.
  • the number n of the first type of battery cells and the number m of the second type of battery cells satisfy: 5 ⁇ n+m ⁇ 30.
  • the sum of the number n of the first type of battery cells and the number m of the second type of battery cells may be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30.
  • the rate of change ⁇ F 1 of the expansion force of the first type of battery cells may be 6N/circle to 15N/circle, 7N/circle to 14N/circle, 7N/circle to 13N/circle , 7.3 N/circle to 12.6 Newtons/circle, or 8.2 Newtons/circle to 12.6 Newtons/circle.
  • the rate of change of the expansion force of the first type of battery cells is within an appropriate range, which can keep the cycle expansion force in the battery module relatively low while ensuring its high energy density, thereby further improving the cycle life of the battery module. .
  • the safety performance of the battery module can also be improved.
  • the expansion force change rate ⁇ F 2 of the second type of battery cells may be 0.9 N/circle to 4.5 Newtons/circle, 1.4 Newtons/circle to 4 Newtons/circle, 1.6 Newtons/circle to 3.3 Newtons/circle , 1.2 N/circle to 3.5 Newtons/circle, 1.2 Newtons/circle to 2.3 Newtons/circle, or 1.4 Newtons/circle to 1.6 Newtons/circle.
  • the change rate of the expansion force of the second type of battery cells is lower, which can more effectively reduce the cycle expansion force of the entire battery module.
  • the use of less of the second type of battery cells can effectively reduce the cyclic expansion force in the entire battery module, so that the advantages of the high energy volume density of the first type of battery cells can be better exhibited, and the battery The volumetric energy density of the module is further improved.
  • the battery module may satisfy (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.7 ⁇ VED 1 .
  • (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.75 ⁇ VED 1 (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.78 ⁇ VED 1 , (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.8 ⁇ VED 1 , or (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) ⁇ 0.83 ⁇ VED 1 .
  • (VED 1 ⁇ n+VED 2 ⁇ m)/(n+m) represents the average volumetric energy density of the battery cells in the battery module, when (VED 1 ⁇ n+VED 2 ⁇ When m)/(n+m) satisfies the above relationship, the assembled battery module can ensure low cyclic expansion force, effectively improve long-term cycle life, and also have high volumetric energy density.
  • the battery module may satisfy VED 2 ⁇ m/(VED 1 ⁇ n+VED 2 ⁇ m) ⁇ 100% ⁇ 65%.
  • the rate of change of the expansion force of the first type of battery cell and the rate of change of the expansion force of the second type of battery cell and the volumetric energy density of the first type of battery cell and the second type of battery cell
  • the volumetric energy densities of the monomers all satisfy a specific relationship, which enables the battery module to take into account both a higher cycle life and a higher volumetric energy density.
  • the volumetric energy density VED of the battery module may be ⁇ 300Wh/L, ⁇ 350Wh/L, or ⁇ 360Wh/L.
  • VED ⁇ 410Wh/L, ⁇ 400Wh/L, or ⁇ 390Wh/L.
  • the volume energy density VED 1 of the first type of battery cell may be 450Wh/L ⁇ 650Wh/kL, 500Wh/L ⁇ 620Wh/L, 520Wh/L ⁇ 610Wh/L, or 550Wh/L ⁇ 600Wh/L.
  • the volume energy density of the first type of battery cells is relatively high, which is beneficial to improve the volume energy density of the battery module.
  • the volume energy density VED 2 of the second type of battery cells may be 250Wh/L ⁇ 450Wh/L, 300Wh/L ⁇ 410Wh/L, or 340Wh/L ⁇ 380Wh/L.
  • the volumetric energy density can be above 250Wh/L, or even above 300Wh/L, so that the battery module using it can improve the cycle expansion force. At the same time, a higher volumetric energy density is also obtained.
  • the nominal capacity C1 of the first type of battery cells and the nominal capacity C2 of the second type of battery cells satisfy: 0.9 ⁇ C1/C2 ⁇ 1.1.
  • the actual capacity of the battery cell refers to the amount of electricity actually released by the battery cell under certain conditions (such as 0.2C). The amount of electricity given by the battery cells under different discharge regimes is also different. The actual capacity of the battery cells under this unspecified discharge regime is usually expressed by the nominal capacity. Nominal capacity is an approximate representation of actual capacity.
  • the discharge current intensity, temperature and discharge cut-off voltage of the battery cell are called the discharge regime of the battery cell.
  • the discharge regime of the nominal capacity of a battery cell is: the discharge current intensity is 50A, the temperature is 25°C, and the discharge cut-off voltage is determined according to the type of positive active material of the battery cell.
  • the nominal capacity C1 of the first type of battery cell and the nominal capacity C2 of the second type of battery cell are within the above ranges, it can ensure that the external energy output of the battery module or battery pack is high, and at the same time, Since the volumetric energy density of the first type of battery cell is higher than that of the second type of battery cell, the volume difference between the first type of battery cell and the second type of battery cell is within a certain range, which is very important for improving the battery module or battery pack. The overall expansion force effect is more significant.
  • the discharge cut-off voltage of a battery cell is its own characteristic.
  • the positive electrode active material is lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide
  • the discharge cut-off voltage is 2.8V.
  • the positive electrode active material is lithium iron phosphate (LiFePO 4 )
  • the discharge cut-off voltage range can be selected to be 2.5V.
  • the positive active material material is a mixture of two materials, the discharge cut-off voltage may be based on the material with a larger proportion of the mixture.
  • the n battery cells of the first type and the m battery cells of the second type in the battery unit may be disposed facing each other. This enables the battery module to have a higher volumetric energy density. It is also possible to set a buffer pad or reserve expansion space in the arrangement of the n first-type battery cells and the m second-type battery cells of the battery unit. This can further improve the cycle life of the battery module.
  • the first type of battery cells and the second type of battery cells are electrically connected, so as to output electrical energy externally or store electrical energy with required voltage and current.
  • the first type of battery cells and the second type of battery cells in the battery cells may be electrically connected in series or a series/parallel combination.
  • the first type of battery cells and the second type of battery cells will perform the charging/discharging process synchronously,
  • the volume expansion changes of different types of battery cells are coordinated, which is conducive to predicting the overall volume expansion rate of the battery module in the design stage, and it is more convenient to adjust the improvement range of the cycle life of the battery module.
  • the first type of battery cells and the second type of battery cells are electrically connected in series.
  • the first positive electrode sheet includes a first positive electrode current collector and a first positive electrode film layer disposed on at least one surface of the first positive electrode current collector and containing a first positive electrode active material.
  • the first positive electrode active material has a high gram capacity.
  • the first positive active material may include one or more of lithium transition metal oxides, lithium transition metal oxides and oxides obtained by adding other transition metals or non-transition metals or non-metals.
  • the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce and Mg.
  • the first positive active material may be selected from one or more of lithium nickel oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.
  • the first positive active material may include a lithium transition metal oxide Li 1+x1 Ni a Co b M 1-ab O 2- y1 A y1 , wherein -0.1 ⁇ x1 ⁇ 0.2, 0.5 ⁇ a ⁇ 0.95, 0 ⁇ b ⁇ 0.2, 0a+b ⁇ 1, 0 ⁇ y1 ⁇ 0.2, M is selected from one or more of Mn, Fe, Cr, Ti, Zn, V, Al, Zr and Ce, and A One or more selected from S, F, Cl and I.
  • M includes either Mn or Al.
  • the gram capacity of the first positive electrode active material is relatively high, and the first positive electrode pole piece using the same can obtain higher areal density and compaction density, so that the first type of battery cell can obtain higher volumetric energy density ( For example, the aforementioned VED 1 ), thereby enabling the battery module to have a higher volumetric energy density.
  • the first positive active material includes single particles with a volume average particle diameter D v 50 ranging from 2 ⁇ m to 8 ⁇ m.
  • the single particle is an independently dispersed primary particle, or a particle form formed by agglomeration of a small number (for example, 2 to 5) of primary particles.
  • the particle size of the primary particle is not less than 1 ⁇ m.
  • the single particle is included in the first positive electrode active material, which can improve the compressive performance of the first positive electrode sheet using the single particle.
  • the first positive electrode sheet can still maintain a high electrolyte wettability and retention amount, thereby ensuring the effective performance of the capacity performance of the first positive electrode active material, thereby further improving the battery The cycle life of the module.
  • the number of the first positive electrode active material having a single particle form accounts for ⁇ 40%.
  • the proportion of single particles in the first positive electrode active material is 40%-100%, 50%-100%, 50%-90%, 60%-100%, 60%-80%, 70%- 100%, or 80% to 100%.
  • the first positive electrode active material contains more single particles, which can further improve the cycle life of the battery module.
  • the first positive active material may further include secondary particles having a degree of aggregation greater than that of a single particle.
  • the degree of aggregation is characterized by the number of primary particles contained in the secondary particles.
  • the aggregation degree of the secondary particles is ⁇ 300, ⁇ 500, or ⁇ 800.
  • the first positive electrode active material contains secondary particles with a degree of aggregation greater than that of a single particle, which is conducive to improving the transmission capacity of active ions in the first positive electrode plate, thereby reducing battery polarization and further improving the battery module's performance at low temperatures. cycle life.
  • the proportion of secondary particles in the first positive electrode active material may be ⁇ 10%, ⁇ 40%, or ⁇ 60%. Further optionally, the proportion of secondary particles with a degree of aggregation greater than that of a single particle in the first positive electrode active material may be ⁇ 100%, ⁇ 90%, ⁇ 80%, or ⁇ 50%.
  • the first cathode film layer may include the first cathode active material and optional binder and/or conductive agent.
  • the binder can be selected from known binders in the art, and the conductive agent can be selected from known conductive agents in the art.
  • the binder may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene vinyl acetate (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral ( One or more of PVB) etc.
  • the conductive agent may be selected from one or more of superconducting carbon, carbon black (eg, acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • carbon black eg, acetylene black, Ketjen black, Super P, etc.
  • carbon dots carbon nanotubes, graphene, and carbon nanofibers.
  • the areal density CW 3 of the first positive electrode film layer may be 15.00 mg/cm 2 to 20.00 mg/cm 2 , for example, 17.50 mg/cm 2 to 20.00 mg/cm 2 .
  • the compaction density PD 3 of the first positive electrode film layer may be 3.0 g/cm 3 to 3.5 g/cm 3 , or 3.25 g/cm 3 to 3.45 g/cm 3 .
  • the first positive electrode current collector can be a known positive electrode current collector in the art, such as aluminum foil.
  • the first negative electrode sheet may include a first negative electrode current collector and a first negative electrode film layer disposed on at least one surface of the first negative electrode current collector and containing a first negative electrode active material.
  • the specific capacity of the first negative electrode pole piece and the first positive electrode pole piece can be matched, so that The first type of battery cell obtains a higher volumetric energy density (for example, the aforementioned VED 1 ); at the same time, the expansion force change rate ⁇ F 1 of the first type of battery cell can also meet the aforementioned requirement.
  • the first negative active material may include one or more of artificial graphite and natural graphite. Compared with other negative electrode active materials, the gram capacity of graphite negative electrode material is higher, and the cycle expansion is small, which can improve the volume energy density and cycle performance of the first type of battery cell, thereby increasing the volume of the battery module Energy density and cycle life.
  • the first negative electrode film layer may include a first negative electrode active material along with optional binders, optional conductive agents, and other optional auxiliary agents.
  • the binder can be selected from the binders known in the art.
  • the binder may be selected from one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinyl alcohol (PVA), and the like.
  • the conductive agent can be selected from those known in the art.
  • the conductive agent may be selected from one or more of superconducting carbon, carbon black (eg, acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • Other optional auxiliary agents are, for example, thickeners, such as sodium carboxymethyl cellulose (CMC-Na), and PTC thermistor materials, for example.
  • the areal density CW 1 of the first negative electrode film layer may be 9.70 mg/cm 2 to 11.68 mg/cm 2 .
  • the optional range is 10.38 mg/cm 2 to 11.36 mg/cm 2 .
  • the CW 1 of the first negative electrode film layer is within an appropriate range, which not only enables the first type of battery cell to obtain a higher volumetric energy density, but also reduces the diffusion resistance of active ions and improves the cycle life of the first type of battery cell , thereby improving the cycle life of the battery module.
  • the compaction density PD 1 of the first negative electrode film layer may be 1.35 g/cm 3 to 1.65 g/cm 3 .
  • the options are 1.40g/cm 3 -1.60g/cm 3 , 1.45g/cm 3 -1.60g/cm 3 , or 1.45g/cm 3 -1.55g/cm 3 .
  • the PD 1 of the first negative electrode film layer is in an appropriate range, which can enable the first type of battery cells to obtain higher volumetric energy density, and at the same time, the first negative electrode active materials in the first negative electrode film layer are in close contact and good contact.
  • the pore structure has high active ion diffusion performance and reduces the risk of lithium precipitation in the negative electrode, thereby improving the cycle life and safety performance of the first type of battery cells. Therefore, the cycle life and safety performance of the battery module are also improved.
  • the first negative electrode current collector can be a negative electrode current collector known in the art, such as copper foil.
  • the separator is arranged between the first positive electrode and the first negative electrode, and plays a role of isolation. Separating membranes known in the art can be selected according to requirements.
  • the separator may include a glass fiber film, a non-woven fabric film, a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, and a multilayer composite film including two or more of them.
  • the electrolyte may include an organic solvent and a lithium salt.
  • organic solvents and lithium salts and the composition of the electrolyte are not specifically limited, and can be selected according to requirements.
  • the organic solvent may include ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dicarbonate Propyl (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate ( MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), butyrate One or more of ethyl acetate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (
  • lithium salts may include LiPF6 (lithium hexafluorophosphate), LiBF4 (lithium tetrafluoroborate), LiClO4 (lithium perchlorate), LiAsF6 (lithium hexafluoroarsenate), LiFSI (lithium bisfluorosulfonimide) ), LiTFSI (Lithium Bistrifluoromethanesulfonimide), LiTFS (Lithium Trifluoromethanesulfonate), LiDFOB (Lithium Difluorooxalate Borate), LiBOB (Lithium Dioxalate Borate), LiPO2F 2 (Lithium Difluorophosphate) , one or more of LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
  • LiPF6 lithium hexafluorophosphate
  • LiBF4 lithium tetraflu
  • additives are also optionally included in the electrolyte.
  • the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance of the battery, such as additives to improve battery overcharge performance, additives to improve battery high temperature performance, and additives to improve battery low temperature performance. additives, etc.
  • the outer packaging is used to encapsulate the cells and electrolyte.
  • the outer packaging can be a hard case, such as a hard plastic case, an aluminum case, a steel case, and the like.
  • the outer package can also be a flexible package, such as a bag-type flexible package.
  • the material of the soft bag may be plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • the second positive electrode sheet includes a second positive electrode current collector and a second positive electrode film layer disposed on at least one surface of the second positive electrode current collector and containing a second positive electrode active material.
  • the second positive active material may include one or more of olivine-structured lithium-containing phosphates and modified materials thereof.
  • the modified material may be doping modification and/or coating modification of the olivine-structured lithium-containing phosphate.
  • the second positive active material may include a lithium-containing phosphate LiFe 1-x2-y2 Mn x2 M' y2 PO 4 , wherein 0 ⁇ x2 ⁇ 1, 0 ⁇ y2 ⁇ 0.1, and M' is selected from the group consisting of One or more of transition metal elements other than Fe, Mn and non-transition metal elements.
  • the second positive active material may include one or more of LiFePO 4 (lithium iron phosphate, may be abbreviated as LFP), LiMnPO 4 , LiMn 1-x3 Fe x3 PO 4 , and LiV 1-x3 Fe x3 PO 4 . , where x3 independently satisfies 0 ⁇ x3 ⁇ 1.
  • the cycle stability of the second active material is good, and the compaction density of the second positive pole piece using it is generally low, and the areal density of the second negative pole piece matched with the second positive pole piece is correspondingly. It is lower, has lower pole piece rebound and better electrolyte infiltration performance, which is beneficial to the second type of battery cells to obtain lower cycle expansion force and higher cycle life, so that the battery module can obtain better performance. Low cyclic expansion force and high cycle life.
  • the second positive active material may include single particles having a volume average particle diameter D v 50 of 800 nm to 1.5 ⁇ m.
  • the single particle contained in the second positive electrode active material can improve the compression resistance of the second positive electrode sheet using the single particle. Under the action of the cyclic expansion force in the battery module, the second positive electrode sheet can still maintain a high electrolyte wettability and retention amount, thereby ensuring the effective performance of the capacity performance of the second positive electrode active material, thereby further improving the battery The cycle life of the module.
  • the number of single particles in the second positive electrode active material accounts for ⁇ 60%.
  • the number of single particles in the second positive electrode active material accounts for 60% to 100%, 70% to 100%, or 80% to 100%.
  • the second positive electrode active material contains more single particles, which can further improve the cycle life of the battery module.
  • the second cathode film layer may include a second cathode active material and optionally a binder and/or a conductive agent.
  • the binder can be selected from known binders in the art
  • the conductive agent can be selected from known conductive agents in the art, such as the binders and conductive agents described herein.
  • the areal density CW 4 of the second positive electrode film layer may be 18.00 mg/cm 2 to 28.00 mg/cm 2 , for example, 18.00 mg/cm 2 to 20.00 mg/cm 2 .
  • the compaction density PD4 of the second positive electrode film layer may be 2.00 g/cm 3 to 2.50 g/cm 3 , or 2.20 g/cm 3 to 2.40 g/cm 3 .
  • the second positive electrode current collector can be a known positive electrode current collector in the art, such as aluminum foil.
  • the second negative electrode sheet may include a second negative electrode current collector and a second negative electrode film layer disposed on at least one surface of the second negative electrode current collector and containing a second negative electrode active material.
  • the specific capacity of the second negative electrode pole piece and the second positive electrode pole piece can be matched, so that The volumetric energy density and expansion force change rate of the second type of battery cells meet the aforementioned requirements.
  • the second negative active material may include one or more of artificial graphite and natural graphite.
  • the second negative electrode film layer may include a second negative electrode active material and optional binders, conductive agents, and/or other additives.
  • the binder can be selected from known binders in the art
  • the conductive agent can be selected from known conductive agents in the art
  • other additives can be selected from additives known in the art for negative electrode film layers. Such as the binders, conductive agents and other additives described herein.
  • the areal density CW 2 of the second negative electrode film layer may be 6.50 mg/cm 2 to 9.70 mg/cm 2 , or 8.11 mg/cm 2 to 9.40 mg/cm 2 .
  • the CW 2 of the second negative electrode film layer is within an appropriate range, which not only enables the second type of battery cell to obtain a higher volumetric energy density, but also reduces the diffusion resistance of active ions and improves the cycle life of the second type of battery cell , thereby improving the cycle life of the battery module.
  • the compaction density PD 2 of the second negative electrode film layer may be 1.35 g/cm 3 to 1.65 g/cm 3 , 1.45 g/cm 3 to 1.60 g/cm 3 , or 1.45 g/cm 3 to 1.45 g/cm 3 . 1.55g/cm 3 .
  • the PD 2 of the second negative electrode film layer is in an appropriate range, so that the second type of battery cell can obtain a higher volume energy density, and at the same time, the second negative electrode active material in the second negative electrode film layer forms close contact and good
  • the pore structure has high active ion diffusion performance and reduces the risk of lithium precipitation in the negative electrode, thereby improving the cycle life and safety performance of the second type of battery cells. Therefore, the cycle life and safety performance of the battery module are also improved.
  • the second negative electrode current collector can be a negative electrode current collector known in the art, such as copper foil.
  • the separator is arranged between the second positive electrode and the second negative electrode, and plays a role of isolation. Separating membranes known in the art can be selected according to requirements. For example the isolation films described herein.
  • the electrolyte may include an organic solvent and a lithium salt.
  • the electrolyte also optionally includes additives.
  • the types of organic solvents, lithium salts and additives and the composition of the electrolyte are not specifically limited, and can be selected according to requirements. Examples are organic solvents, lithium salts, and additives described herein.
  • the outer packaging is used to encapsulate the cells and electrolyte.
  • the outer packaging of the second type of battery cells may adopt the outer packaging described herein.
  • FIG. 1 shows a battery module 4 as an example.
  • a battery unit may be included in the battery module 4, and the n first-type battery cells 5a and m second-type battery cells 5b in the battery unit are along the length direction of the battery module 4 (for example, L direction) arrangement. Further, the battery cells can be fixed by fasteners.
  • FIG. 2 shows a battery module 4 as another example.
  • more than two battery cells may be included in the battery module 4 .
  • the number of battery cells can be adjusted according to actual needs.
  • the n first-type battery cells 5a and m second-type battery cells 5b in each battery unit are arranged along the length direction of the battery module 4 (for example, the L direction).
  • the battery modules 4 are arranged in the width direction (for example, the W direction).
  • the two or more battery cells can also be arranged in other ways. Further, the two or more battery cells can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodating space, and the battery cells are accommodated in the accommodating space.
  • FIG. 3 shows a hexahedral-shaped battery cell 5 as an example, which may be a first-type battery cell 5a or a second-type battery cell 5b.
  • Figure 4 is an exploded schematic view thereof.
  • the outer package of the battery cells 5 may include a case 51 and a cover plate 53 .
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a accommodating cavity.
  • the housing 51 has an opening that communicates with the accommodating cavity, and a cover plate 53 can cover the opening to close the accommodating cavity.
  • the battery cells 52 are packaged in the receiving cavity.
  • the electrolyte is infiltrated in the battery core 52 .
  • the battery cells 5 shown in FIGS. 3 and 4 are hard case batteries, but not limited thereto.
  • the battery cell 5 may be a pouch type battery, that is, the case 51 is replaced by a soft package such as a metal plastic film and the top cover assembly 53 is eliminated.
  • the number of cells 52 contained can be one or several, and can be adjusted according to requirements.
  • a detection device 10 is shown in FIG. 5 and FIG. 6 .
  • the detection device 10 includes a clamp assembly 11 and a pressure sensor 12.
  • the clamp assembly 11 includes three steel plate clamps, and the battery cell to be tested is clamped between two of the clamps, wherein the battery cell is The large surface of the steel plate is in surface-to-surface contact with the steel plate clamp; the pressure sensor 12 is clamped between another clamp and any one of the aforementioned two clamps, wherein the pressure sensor 12 is connected to a pressure collector (such as a computer).
  • the thickness of the steel plate is 30mm.
  • the material of the steel plate and the connecting piece between the steel plates may be 45-gauge steel, and further, the surface of the steel plate may be chrome-plated.
  • the diameter of the pretensioner between the steel plates is optional to be 15mm.
  • the rectangular area enclosed by the straight lines of the four-corner pretensioners of the fixture must be greater than or equal to the large surface area of the battery cell.
  • the battery cell and the pressure sensor can be clamped in the center of the clamp, and the preloads (such as screws) at the four corners of the clamp are alternated diagonally. Tighten, and finally fine-tune the preloads at the four corners to achieve the required preload. Then, under the condition that the ambient temperature is set to 25°C, charge with a constant current of 0.33C 0 to the upper limit cut-off voltage, then charge with a constant voltage until the current is less than 0.05C 0 , let it stand for 10 minutes, and then discharge it with a constant current of 0.33C 0 to The lower cut-off voltage is recorded as one cycle. The battery cells were charged and discharged for 500 cycles, and the expansion force of the battery cells was monitored in real time. Finally, the change rate of the expansion force of the battery cell was calculated according to ⁇ F/500.
  • the upper limit cut-off voltage and the lower limit cut-off voltage of a battery cell are its own characteristics.
  • the charge and discharge voltage range is 2.8V to 4.5V; when Ni atoms account for 80% of the transition metal atoms in lithium nickel cobalt manganese oxide, the charge and discharge voltage range can be selected 2.8V ⁇ 4.25V; when Ni atoms account for 60% ⁇ 70% of transition metal atoms in lithium nickel cobalt manganese oxide, the charge-discharge voltage range can be selected as 2.8V ⁇ 4.4V; When the proportion of transition metal atoms is 50%, the charge-discharge voltage range can be selected from 2.8V to 4.35V.
  • the charge-discharge voltage range can be selected from 2.8V to 4.3V.
  • the positive electrode active material is lithium iron phosphate (LiFePO 4 )
  • the charge-discharge voltage range can be selected from 2.5V to 3.65V.
  • the positive active material is a mixture of two materials, the voltage range may be based on the material with a larger proportion of the mixture.
  • the volume energy density of a battery cell and a battery module is a meaning known in the art, and can be tested by a method known in the art.
  • the volumetric energy density of a battery cell is the maximum energy that the battery cell has when it is within the range of the upper cut-off voltage and the lower cut-off voltage of the battery cell divided by the volume of the battery case (length ⁇ width ⁇ shoulder height), where, The shoulder height is the remaining height after subtracting the height of the electrode terminals from the total height of the battery.
  • the volumetric energy density of a battery module is the sum of the energy of all battery cells in the battery module divided by the total volume of the battery module (length ⁇ width ⁇ height), where the total volume of the battery module includes the total volume of all battery cells. volume, and other constituent parts of the battery module (including but not limited to wiring harnesses, end and/or side panels, and top cover panels).
  • the volume of the second type of battery cells and the volume of the first type of battery cells are both calculated as the volume enclosed by their outer surfaces, and the volume of the electrode terminals is ignored.
  • the areal density of the negative electrode film layer is the meaning known in the art, which refers to the quality of the negative electrode film layer on one side of the negative electrode current collector per unit area, and can be measured by methods known in the art. For example, take a single-side coated and cold-pressed negative pole piece (if it is a double-sided coated negative pole piece, you can wipe off the negative film layer on one side first), punch it into a small circle with an area of S1, and call it Its weight, recorded as M1.
  • the compaction density of the negative electrode film layer area density of the negative electrode film layer/thickness of the negative electrode film layer.
  • the thickness of the negative electrode film is a meaning known in the art, which refers to the thickness of the negative electrode film layer on one side of the negative electrode current collector, and can be measured by methods known in the art. For example, a 4-digit precision spiral micrometer.
  • An exemplary test method is as follows: cut a 1cm ⁇ 1cm positive pole piece, paste it on a sample stage as a sample to be tested; put the sample stage into a vacuum sample chamber and fix it, and prepare it with a cross-section polishing machine (eg JEOL IB-09010CP) The cross section of the pole piece along the thickness direction; the particles in the sample to be tested are tested by scanning electron microscope & energy dispersive spectrometer (such as ZEISS sigma300). The test can refer to JY/T010-1996.
  • the primary particle size in a single particle has the meaning known in the art, and can be measured by a method known in the art.
  • An exemplary test method is as follows: the positive electrode film layer is peeled off from the positive electrode current collector by ethanol immersion, repeated ultrasonic cleaning, drying, and powder sintering at 300-400 ° C, and the sample obtained after sintering is placed on the sample stage as a test. Sample; put the sample stage into the vacuum sample chamber and fix it, and use the scanning electron microscope & energy dispersive spectrometer (such as ZEISS sigma300) to test the surface morphology of the particles in the sample to be tested.
  • the scanning electron microscope & energy dispersive spectrometer such as ZEISS sigma300
  • the volume-average particle size D v 50 of the positive electrode active material is the meaning known in the art, which means the particle size corresponding to when the cumulative volume distribution percentage of the positive electrode active material reaches 50%. method to measure.
  • a laser particle size analyzer such as the Mastersizer 2000E laser particle size analyzer of Malvern Instruments Ltd., UK.
  • Another aspect of the present application provides a method for manufacturing a battery module, comprising the following steps:
  • VED 1 represents the volumetric energy density of the first type of battery cell, in Wh/L
  • VED 2 represents the volume of the second type of battery cell Energy density, in Wh/L
  • ⁇ F 1 represents the rate of change of the expansion force of the first type of battery cell, in N/circle
  • ⁇ F 2 represents the rate of change of the expansion force of the second type of battery cell, in the unit is Newton/circle;
  • the n battery cells of the first type and the m battery cells of the second type are arranged in an array to form a battery module.
  • the battery module using the manufacturing method of the present application can have a lower cycle expansion force, and thus can have a higher cycle life.
  • the electrical connection manner of the n first type battery cells and m second type battery cells includes: connecting n first type battery cells and m second type battery cells in series or Electrically connected in series/parallel combination.
  • the technical features of the battery module in the present application are also applicable to the manufacturing method of the battery module, and produce corresponding beneficial effects.
  • the positive pole piece, the separator and the negative pole piece can be formed into a battery cell through a stacking process or a winding process; the battery cell is put into an outer package, injected with an electrolyte, and after encapsulation and other subsequent processes, a battery cell is obtained .
  • the positive electrode sheet can be prepared according to conventional methods in the art.
  • the positive electrode active material, the conductive agent and the binder are dispersed in a solvent to form a uniform positive electrode slurry, such as N-methylpyrrolidone (NMP); the positive electrode slurry is coated on the positive electrode current collector, and the After drying, cold pressing and other processes, a positive electrode sheet is obtained.
  • NMP N-methylpyrrolidone
  • the negative pole piece can be prepared according to conventional methods in the art.
  • the negative electrode active material, conductive agent, binder and thickener are dispersed in a solvent to form a uniform negative electrode slurry, the solvent is deionized water, for example; the negative electrode slurry is coated on the negative electrode current collector, and dried After drying, cold pressing and other processes, a negative electrode piece is obtained.
  • Another aspect of the present application provides a manufacturing equipment for a battery module, which includes a clamping arm unit, an assembling unit and a control unit.
  • the clip arm unit is used to obtain n first-type battery cells and m second-type battery cells, where VED 1 >VED 2 , ⁇ F 1 > ⁇ F 2 , n ⁇ 1, m ⁇ 1, ( ⁇ F 1 ⁇ n + ⁇ F 2 ⁇ m)/(n+m) ⁇ 0.8 ⁇ F 1 , where VED 1 represents the volumetric energy density of the first type of battery cell, in Wh/L, and VED 2 represents the second type of battery cell The volumetric energy density of the battery cell, in Wh/L, ⁇ F1 represents the rate of change of the expansion force of the first type of battery cell, in Newtons/circle, ⁇ F2 represents the expansion force of the second type of battery cell The rate of change in Newtons per revolution.
  • the assembling unit is used for arranging the n battery cells of the first type and the m battery cells of the second type.
  • the control unit is used for controlling the clamping arm unit and the assembling unit to work.
  • the clamping arm unit, the assembling unit and the control unit can be selected from devices or devices known in the art according to actual needs.
  • the battery module manufactured by the manufacturing equipment of the present application can have a lower cycle expansion force, and thus can have a higher cycle life.
  • a battery pack which includes any one or several battery modules of the present application.
  • the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack may further include auxiliary components such as a battery management system module (BMS) and cooling/heating components.
  • BMS battery management system module
  • the battery pack includes more than two battery modules, each of which is a battery module described in this application.
  • the cycle expansion force in the battery pack is greatly alleviated, so its cycle life can be significantly improved.
  • the battery pack can also have a higher volumetric energy density.
  • the battery pack 1 may include a battery case and a plurality of battery modules 4 disposed in the battery case.
  • the battery box includes an upper box body 2 and a lower box body 3 .
  • the upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery module 4 .
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the battery module or battery pack can be used as a power source of the device to provide power to the device; it can also be used as an energy storage unit of the device.
  • the device may be, but is not limited to, mobile devices (eg, cell phones, laptops, etc.), electric vehicles (eg, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf balls) vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device may select an electrochemical device such as a primary battery, a secondary battery, a battery module or a battery pack according to its usage requirements.
  • Figure 9 is an apparatus as an example.
  • the device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or the like.
  • the device can use a battery pack or a battery module.
  • the slurry is coated on two opposite surfaces of the positive electrode current collector aluminum foil, and after drying and cold pressing, a first positive electrode pole piece is obtained.
  • the areal density of the positive electrode film layer is 18.83 mg/cm 2 , and the compaction density is 3.25 g/cm 3 ; the number of single particles in the first positive electrode active material accounts for 100%.
  • the areal density of the negative electrode film layer was 11.62 mg/cm 2 , and the compaction density was 1.45 g/cm 3 .
  • Ethylene carbonate (EC), propylene carbonate (PC) and dimethyl carbonate (DMC) are mixed uniformly in a weight ratio of 1:1:1 to obtain an organic solvent; then lithium salt LiPF 6 is dissolved in the above organic solvent. In the solvent, mix uniformly to obtain an electrolyte solution, wherein the concentration of LiPF 6 is 1 mol/L.
  • the first positive pole piece, the polyethylene porous separator, and the first negative pole piece are stacked in sequence, and then wound to obtain a battery cell; the battery core is put into an outer package, injected with an electrolyte, and packaged to obtain a first-type battery monomer.
  • the group margin of the first type of battery cells is 99.0%.
  • the volume energy density of the first type of battery cell is 552Wh/L.
  • the preparation method of the second type of battery cell is similar to the preparation method of the first type of battery cell, the difference is: the preparation parameters of the positive electrode piece and the negative electrode piece are adjusted, and the differences are shown in Table 1.
  • FIG. 10 is a graph showing the expansion force of the first type of battery cells in Example 1 as a function of the number of cycles.
  • FIG. 11 is a graph showing the expansion force of the second type of battery cells in Example 1 as a function of the number of cycles. It can be seen that the first type of battery cells with a higher volumetric energy density have a higher rate of change in the expansion force. The change rate of the expansion force of the second type of battery cells with lower volumetric energy density is very small, and the change of the expansion force is relatively gentle in the process of cyclic charge and discharge.
  • the preparation methods of the first type of battery cell, the second type of battery cell and the battery module are similar to those in Example 1, the difference is that the positive electrode and the negative electrode in the first type of battery cell and the second type of battery cell are adjusted.
  • the preparation parameters of the sheet and the preparation parameters of the battery module are adjusted, and the differences are shown in Tables 1 to 4.
  • the rated upper limit cut-off voltage of the battery module is the sum of the rated upper limit cut-off voltage of each battery cell
  • the rated lower limit cut-off voltage of the battery module is the sum of the rated lower limit cut-off voltage of each battery cell
  • 1C (C represents the nominal capacity of the first type of battery cell) is used as the constant current charging rate, and 1C is used as the discharge rate, and the cycle is charged and discharged 10 times. End the lithium deposition test.
  • Table 4 The arrangement of the first type of battery cells and the second type of battery cells in the battery module
  • the examples of the present application combine the first type of battery cells with higher volume energy density but also higher expansion force change rate and the second type with lower volume energy density and lower expansion force change rate.
  • the battery cells are assembled, and at the same time, the change rate of the expansion force of the first type of battery cells and the change rate of the expansion force of the second type of battery cells are controlled to satisfy a specific relationship, so that the battery module can take into account higher volume energy at the same time. density and high cycle life.
  • the risk of lithium precipitation in the battery cells in the battery module is significantly reduced, and its safety performance is also improved.
  • the battery modules of Comparative Examples 1-4 did not meet the above conditions, and therefore could not take into account high volumetric energy density and high cycle life at the same time.
  • the battery module includes battery cells with high volumetric energy density, lithium deposition is likely to occur.

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Abstract

本申请公开了一种电池模组、电池包、装置以及电池模组的制造方法和制造设备。电池模组包括电池单元，所述电池单元包括n个第一类电池单体和m个第二类电池单体，n≥1，m≥1，所述n个第一类电池单体和m个第二类电池单体排列设置，且满足：VED 1＞VED 2，ΔF 1＞ΔF 2，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，其中，VED 1、VED 2、ΔF 1和ΔF 2分别如本文所定义。

Description

电池模组、电池包、装置以及电池模组的制造方法和制造设备 技术领域
本申请属于储能装置技术领域，具体涉及一种电池模组、电池包、装置以及电池模组的制造方法和制造设备。
背景技术
二次电池具有能量密度高、使用寿命长，以及无记忆效应、使用过程绿色环保等特点，因而被广泛应用。
另外，根据应用场景以及能量密度的需求，通常需要将多个电池单体组装成电池模组、电池包、或系统电柜，作为新能源汽车或储能电站的重要能源组成部分。例如，随着新能源汽车的加速普及，行驶里程需求不断增加，相应地对新能源汽车所携带的电池模组或电池包也不断提出更高能量密度的要求，由此，电池模组或电池包中大多采用高能量密度的电池单体，并且在有限的空间内所含电池单体的数量也越来越多。
然而，高能量密度的电池模组或电池包在长期使用过程中，尤其在使用寿命的中后期，容易出现容量衰减过快、单次满充可实现的续航里程大幅缩水等问题，如何实现高能量密度电池的长寿命、以及在整个生命周期内的单次长续航，已成为二次电池实际应用急需解决的一个技术难点。
发明内容
本申请的第一方面提供一种电池模组，其包括电池单元，所述电池单元包括n个第一类电池单体和m个第二类电池单体，n≥1，m≥1，所述n个第一类电池单体和m个第二类电池单体排列设置，且满足：
VED 1＞VED 2，
ΔF 1＞ΔF 2，
(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈。
本申请通过将体积能量密度较高但膨胀力变化率也较高的第一类电池单体与体积能量密度较低且膨胀力变化率也较低的第二类电池单体进行组配，同时控制第一类电池单体的膨胀力变化率和第二类电池单体的膨胀力变化率之间满足特定关系，有效降低了在循环充放电过程中电池模组中电池单体的膨胀力变化率均值，改善了在循环充放电过程中电池模组中每个电池单体内极片间、以及极片与隔离膜间的离子传输界面的稳定性，从而能提高电池模组整体的长期循环寿命，在使用寿命的中后期单次满充可发挥的容量仍然较高。
在上述任意实施方式中，可选地，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.75×ΔF 1。通过进一步降低电池模组中电池单体的膨胀力变化率均值，可以进一步提高电池模组整体的长期循环寿命。
可选的，0.5×ΔF 1≤(ΔF 1×n+ΔF 2×m)/(n+m)≤0.65×ΔF 1。这样有利于使电池模组更好地同时兼顾较高的体积能量密度和较高的循环寿命。
在上述任意实施方式中，所述ΔF 1可以为6牛顿/圈～15牛顿/圈，7牛顿/圈～14牛顿/圈，7牛顿/圈～13牛顿/圈，7.3牛顿/圈～12.6牛顿/圈，或8.2牛顿/圈～12.6牛顿/圈。所述ΔF 2可以为0.9牛顿/圈～4.5牛顿/圈，1.4牛顿/圈～4牛顿/圈，1.2牛顿/圈～3.5牛顿/圈，1.2牛顿/圈～2.3牛顿/圈，或1.4牛顿/圈～1.6牛顿/圈。本申请中，当第一类电池单体的膨胀力变化率和/或第二类电池单体的膨胀力变化率在适当范围内，能进一步降低电池模组内的循环膨胀力，从而进一步提高电池模组的循环寿命；并且还有利于提升电池模组的体积能量密度。此外，电池模组的安全性能也能得到提升。
在上述任意实施方式中，所述膨胀力变化率为电池单体在25℃下、以0.33C 0倍率(C 0表示所述电池单体的标称容量)、在所述电池单体的上限截止电压和下限截止电压的范围内，循环充放电500圈后的平均膨胀力变化ΔF/500，所述ΔF为所述电池单体在循环第500圈与循环起始时检测装置传感器测到的所述电池单体的压力的变化值。
在上述任意实施方式中，所述第一类电池单体的标称容量C1与所述第二类电池单体的标称容量C2满足：0.9≤C1/C2≤1.1。本申请中，所述第一类电池单体的标称容量C1与所述第二类电池单体的标称容量C2在上述范围内时，可以保证电池模组或电池包的对外能量输出较高，同时，由于第一类电池单体的体积能量密度高于第二类电池单体，因此第一类电池单体与第二类电池单体的体积差异在一定范围内，对于改善电池模组或电池包整体的膨胀力效果更加显著。
在上述任意实施方式中，所述电池单元中连续排列的第一类电池单体的个数不超过 n/2。进一步可以不超过n/3。可选的，所述电池单元中连续排列的第一类电池单体的个数不超过5个，或不超过3个。作为示例的，所述电池单元中连续排列的第一类电池单体的个数可以为1～3，2～3，或1～2等。每隔适当数量的第一类电池单体设置第二类电池单体，能进一步提高对电池模组循环膨胀力的改善效果，从而能进一步提高电池模组的循环寿命。
在上述任意实施方式中，所述第一类电池单体的个数n与所述第二类电池单体的个数m可满足：5≤n+m≤30。可选的，8≤n+m≤25。进一步可选的，9≤n+m≤20。
在上述任意实施方式中，所述电池模组可满足(VED 1×n+VED 2×m)/(n+m)≥0.7×VED 1。可选的，(VED 1×n+VED 2×m)/(n+m)≥0.78×VED 1。本申请中，(VED 1×n+VED 2×m)/(n+m)代表电池模组中电池单体的体积能量密度平均值，当(VED 1×n+VED 2×m)/(n+m)满足上述关系时，组配形成的电池模组能在保证循环膨胀力较低、长期循环寿命得到有效改善的同时，还具有较高的体积能量密度。
在上述任意实施方式中，所述电池模组可满足VED 2×m/(VED 1×n+VED 2×m)×100％≤65％。可选的，VED 2×m/(VED 1×n+VED 2×m)×100％≤60％，≤55％，≤50％，≤45％，或≤40％。进一步地，所述电池模组可满足VED 2×m/(VED 1×n+VED 2×m)×100％≥10％。可选的，VED 2×m/(VED 1×n+VED 2×m)×100％≥15％，≥20％，≥25％，≥30％，或≥35％。进一步可选的，20％≤VED 2×m/(VED 1×n+VED 2×m)×100％≤40％。本申请的电池模组中，当第一类电池单体的体积能量密度和第二类电池单体的体积能量密度之间进一步满足上述关系时，能使电池模组同时兼顾较高的循环寿命和较高的体积能量密度。
在上述任意实施方式中，所述电池模组的体积能量密度VED≥300Wh/L。可选的，VED≥350Wh/L。该电池模组不仅具有较高的循环寿命，还兼具较高的体积能量密度。
在上述任意实施方式中，第一类电池单体包括第一负极极片，所述第一负极极片包括含有第一负极活性物质的第一负极膜层，其中，所述第一负极活性物质包括人造石墨、天然石墨中的一种或几种，所述第一负极膜层的面密度CW 1为9.70mg/cm 2～11.68mg/cm 2，所述第一负极膜层的压实密度PD 1为1.35g/cm 3～1.65g/cm 3。
第一类电池单体采用该第一负极极片，能在具有较高的能量密度的同时，还具有较低的循环膨胀力，使采用其的电池模组的循环膨胀力较低。在电池模组的寿命中后期，负极极片的体积膨胀较小，有效改善在外力作用下负极活性物质的结构稳定性。由此，电池模组在高能量密度的前提下，具有较高的循环寿命，并且在电池模组使用寿命的中后期单次充放电仍可发挥出较大容量。
可选的，CW 1可以为10.38mg/cm 2～11.36mg/cm 2。
可选的，PD 1可以为1.40g/cm 3～1.60g/cm 3，或1.45g/cm 3～1.55g/cm 3。
在上述任意实施方式中，第一类电池单体包括第一正极极片，所述第一正极极片包含第一正极活性物质，所述第一正极活性物质包括式(I)所示的锂过渡金属氧化物，
Li 1+x1Ni aCo bM 1-a-bO 2-y1A y1      式(I)
其中，-0.1≤x1≤0.2，0.5≤a＜0.95，0＜b＜0.2，0＜a+b＜1，0≤y1＜0.2，M选自Mn、Fe、Cr、Ti、Zn、V、Al、Zr和Ce中的一种或几种，并且A选自S、F、Cl和I中的一种或几种。
第一类电池单体可获得较高的能量密度，由此能使电池模组获得较高的能量密度。
可选的，所述第一正极活性物质包括体积平均粒径D v50在2μm～8μm的单颗粒。该第一正极活性物质中包含所述的单颗粒，能进一步提高电池模组的循环寿命。
可选的，在所述第一正极活性物质中，具有单颗粒形态的第一正极活性物质数量占比≥40％。第一正极活性物质中包含较多的所述单颗粒，能更进一步地提高电池模组的循环寿命。
在上述任意实施方式中，第二类电池单体包括第二负极极片，所述第二负极极片包括含有第二负极活性物质的第二负极膜层，其中，所述第二负极活性物质包括人造石墨、天然石墨中的至少一种，所述第二负极膜层的面密度CW 2为6.50mg/cm 2～9.70mg/cm 2，所述第二负极膜层的压实密度PD 2为1.35g/cm 3～1.65g/cm 3。
第二类电池单体采用该第二负极极片，能获得较低的循环膨胀力，使采用其的电池模组的循环膨胀力较低，在电池模组的寿命中后期，负极极片的体积膨胀较小，有效改善在外力作用下负极活性物质的结构稳定性。因而能提高电池模组整体的循环寿命，并且在电池模组使用寿命的中后期单次充放电仍可发挥出较大容量。另外，该第二类电池单体同时还可以具有较高的能量密度，使得电池模组的能量密度也较高。
可选的，CW 2可以为8.11mg/cm 2～9.40mg/cm 2。
可选的，PD 2可以为1.45g/cm 3～1.60g/cm 3，或1.45g/cm 3～1.55g/cm 3。
在上述任意实施方式中，所述第二类电池单体包含第二正极极片，所述第二正极极片包含第二正极活性物质，所述第二正极活性物质包括式(II)所示的含锂磷酸盐，
LiFe 1-x2-y2Mn x2M’ y2PO 4      式(II)
其中，0≤x2≤1，0≤y2≤0.1，M’选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的一种或几种。
可选的，所述第二正极活性物质包括LiFePO 4、LiMnPO 4、LiMn 1-x3Fe x3PO 4、LiV 1- x3Fe x3PO 4中的一种或几种，其中x3独立地满足0＜x3＜1。
第二类电池单体所包含的所述第二活性物质的循环稳定性较好，由此有利于电池模组获得较高的循环寿命。
可选的，所述第二正极活性物质包括体积平均粒径D v50为800nm～1.5μm的单颗粒。该第二正极活性物质中包含所述的单颗粒，能提高电池模组的循环寿命。
在上述任意实施方式中，第一类电池单体和第二类电池单体的电连接方式至少包括串联连接。可选的，所述电连接为串联、或串/并联组合。本申请中，当第一类电池单体和第二类电池单体至少以串联的方式电连接后，第一类电池单体和第二类电池单体会同步的进行充电/放电过程，不同类型电池单体的体积膨胀变化协同进行，有利于在设计阶段提前预期电池模组整体的体积膨胀率，更便于调制电池模组循环寿命的改善幅度。
本申请第二方面提供一种电池包，其包括根据本申请第一方面的电池模组。本申请的电池包包括所述的电池模组，因而至少具有与所述电池模组相同的优势。
在上述任意实施方式中，电池包包括两个以上电池模组。可选的，每个电池模组均为根据本申请第一方面的电池模组。由此能进一步降低电池包内的循环膨胀力，提高电池包的循环寿命。
本申请第三方面提供一种装置，其包括根据本申请第一方面的电池模组或根据本申请第二方面的电池包，所述电池模组或电池包用于给所述装置提供动力或用于所述装置的能量存储单元。本申请的装置包括所述的电池模组或电池包，因而至少具有与所述电池模组或电池包相同的优势。
本申请第四方面提供一种电池模组的制造方法，其包括以下步骤：
获取n个第一类电池单体和m个第二类电池单体，其中
VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，
(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈；
将所述n个第一类电池单体和m个第二类电池单体排列设置，形成所述电池模组。
采用本申请的制造方法的电池模组可具有较低的循环膨胀力，因而能具有较高的循环寿命。
本申请第五方面提供一种电池模组的制造设备，其包括：
夹臂单元，用于获取n个第一类电池单体和m个第二类电池单体，其中
VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，
(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
ΔF2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈；
组装单元，用于将所述n个第一类电池单体和m个第二类电池单体排列设置；
控制单元，用于控制所述夹臂单元和所述组装单元。
采用本申请的制造设备制造的电池模组可具有较低的循环膨胀力，因而能具有较高的循环寿命。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1是电池模组的一实施方式的示意图。
图2是电池模组的另一实施方式的示意图。
图3是第一类电池单体或第二类电池单体的一实施方式的示意图。
图4是图3的分解图。
图5是电池单体膨胀力检测装置的一实施方式的示意图。
图6是电池单体膨胀力检测装置的一实施方式的另一视角示意图。
图7是电池包的一实施方式的示意图。
图8是图7的分解图。
图9是电池模组或电池包用作电源的装置的一实施方式的示意图。
图10是一实施方式中第一类电池单体的膨胀力随循环圈数变化的曲线图。
图11是一实施方式中第二类电池单体的膨胀力随循环圈数变化的曲线图。
具体实施方式
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合实施例对本申请进行进一步详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或几种”中“几种”的含义是两种或两种以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
为了满足高能量密度的需求，可以采用诸如锂镍钴锰氧化物、锂镍钴铝氧化物等高克容量的正极活性物质制成的正极极片，搭配具有较高面密度和压实密度的石墨负极极片来制备高能量密度的电池单体。然后将多个该电池单体电连接组成高能量密度的电池模组、电池包或储能系统。然而，这些高能量密度的电池单体常常在充放电循环过程中发生容量衰减，电池单体的容量衰减加速导致电池模组或电池包的长期循环寿命缩短，在电池模组或电池包的使用寿命的中后期，单次充放电可实现的续航里程缩水。
现阶段为了解决上述问题，大部分改善方案都是集中在电池单体中化学体系的优化，包括如使用成膜质量较高且电化学性质较稳定的电解液添加剂、对正极活性物质进行进一步的包覆改性、对负极活性物质的表面活性及抗压性进一步提升等。但是，提升电池单体的循环寿命，只能一定程度上提升电池模组或电池包整体的循环性能。
本发明人经进一步的研究发现，在多个电池单体排布组成电池模组或电池包时，电池单体排布的空间利用率及电性能的匹配对电池模组或电池包整体性能的发挥同样具有较大影响。在电池单体的充放电循环过程中，随着负极极片的逐渐反弹，加上电解液的分解产气，使得内部压力及膨胀力越来越大。由于高能量密度电池模组或电池包在设计时，往往会压缩未设置电池单体的残余体积，导致电池单体间的间距较小，因此，在充放电循环过程中，尤其到循环寿命的中后期，当多个电池单体同时膨胀时，电池模组或电池包内会累加产生很大的膨胀力，电池单体受到的外界的挤压力剧增。在外界高挤压力的作用下，电池单体内的充放电界面易发生相对位移、局部电解液被挤压出，离子传输路径受阻，电池模组或电池包的整体循环性能发生“跳水”(即在充放电过程中电池 模组容量骤减，甚至无法继续充放电)。因此，如何在电池模组或电池包具有较高能量密度的前提下，提升整体循环性能是本领域的关键挑战所在。
本发明人经锐意研究，提出可以通过合理组配体积能量密度较高但膨胀力变化率也较高的第一类电池单体与体积能量密度较低且膨胀力变化率也较低的第二类电池单体，来有效降低电池模组或电池包内的循环膨胀力，达到在较高体积能量密度的前提下，提高电池模组或电池包的循环寿命的目的。
因此，本申请第一方面的实施方式提供一种能在具有较高体积能量密度的同时具有较高循环寿命的电池模组。
电池模组
本申请的电池模组包括电池单元，电池单元包括n个第一类电池单体和m个第二类电池单体，n≥1，m≥1，所述n个第一类电池单体和m个第二类电池单体排列设置，且满足：
VED 1＞VED 2，
ΔF 1＞ΔF 2，
(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈。
在本申请的电池模组中，可通过将电芯和电解液封装于外包装中，形成第一类电池单体。电芯可为由第一正极极片、隔离膜和第一负极极片经堆叠工艺或卷绕工艺而形成，其中隔离膜位于第一正极极片和第一负极极片之间，起到隔离的作用。通常地，第一正极活性物质被涂覆在第一正极极片的涂覆区，并可由第一正极极片的涂覆区延伸出的多个未涂覆区层叠形成正极极耳；第一负极活性物质被涂覆在第一负极极片的涂覆区，并可由第一负极极片的涂覆区延伸出的多个未涂覆区层叠形成负极极耳。进一步地，两个极耳可分别通过转接片与对应的电极端子(可设置于电池外包装的盖板上)电连接，从而将电芯的电能引出。第一类电池单体可以是六面体形状(例如长方体、类长方体等)或其它形状的电池单体。类似地，可通过第二正极极片、隔离膜和第二负极极片形成第二类电池单体。第二类电池单体可以是六面体形状(例如长方体、类长方体等)或其它形状的电池单体。
本申请中，“n个第一类电池单体和m个第二类电池单体排列设置”指的是：n个第一类电池单体和m个第二类电池单体可以沿电池模组的长度方向排列设置，并且相邻两个电池单体之间为大面相对。所述大面指的是电池单体中面积最大的侧面(以外表面计)。一般地，电池单体的大面膨胀幅度相对较高，各相邻两个电池单体设置为大面相对，能有效降低电池模组的循环膨胀力，改善电池模组的循环寿命。
第一类电池单体的数量n和第二类电池单体的数量m可根据电池模组的应用和容量来调节。电池模组中所含电池单元的数量可以为一个或几个，可根据需求来调节。
发明人通过锐意研究发现，通过将体积能量密度较高但膨胀力变化率也较高的第一类电池单体与体积能量密度较低且膨胀力变化率也较低的第二类电池单体进行组配，同时控制第一类电池单体的膨胀力变化率和第二类电池单体的膨胀力变化率之间满足特定关系(即，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1)，可以有效改善电池模组中电池单体受到的平均挤压力，从而极大地改善电池模组的长期循环寿命。猜测其原因可能如下：由于电池模组内，电池单体之间的间隔通常较小，即使在电池单体间设置缓冲垫，缓冲垫一旦被压缩到极限，电池单体仍然会受到相邻电池单体的挤压和束缚。随着电池单体内部收到的挤压力也越来越大，最终导致正负极间电解液被挤出，隔离膜孔道结构被堵塞，造成充放电时活性离子传输困难，界面浓差极化增大，造成电池单体的循环性能衰减。本申请中通过引入第二类电池单体，与第一类单体进行合理组配，可以在第一类电池单体间起到持续有效的缓冲作用，降低第一类电池单体的膨胀速率，同时释放第一类电池单体的内应力，由此有效降低了电池单元整体的循环膨胀力，还保证了第一类电池单体和第二类电池单体的电芯内部电解液的充分浸润，改善了电池模组中每个电池单体内极片间、以及极片与隔离膜间的离子传输界面的稳定性，从而实现提高电池模组的循环寿命。
此外，由于电池模组中第一类电池单体的的循环膨胀力得到有效缓解，还能大幅降低过大的内压冲破防爆阀的概率，还可以避免因电芯受挤压造成的电池内短路或漏液的问题，使电池模组兼具较高的安全性能。
在一些实施方式中，(ΔF 1×n+ΔF 2×m)/(n+m)可以≤0.75×ΔF 1，≤0.7×ΔF 1，≤0.65×ΔF 1，≤0.6×ΔF 1，≤0.55×ΔF 1，或≤0.5×ΔF 1。这样能进一步改善电池模组内的循环膨胀力，进一步提高电池模组的循环寿命。另外，(ΔF 1×n+ΔF 2×m)/(n+m)可以≥0.3×ΔF 1，≥0.4×ΔF 1，≥0.45×ΔF 1，≥0.5×ΔF 1，或≥0.55×ΔF 1。这样不仅能改善电池模组的循环寿命，还使得电池模组中具有较高体积能量密度的第一类电池单体的数量相对较多，从而使得电池模组兼具更高的体积能量密度。可选的，0.5×ΔF 1≤(ΔF 1×n+ ΔF 2×m)/(n+m)≤0.7×ΔF 1，0.5×ΔF 1≤(ΔF 1×n+ΔF 2×m)/(n+m)≤0.65×ΔF 1，或0.55×ΔF 1≤(ΔF 1×n+ΔF 2×m)/(n+m)≤0.62×ΔF 1等。
在本申请的电池模组中，各电池单元内的n个第一类电池单体和m个第二类电池单体可以任意排列。例如，将m个第二类电池单体分设在n个第一类电池单体之间和/或两端。在一些实施方式中，所述电池单元中连续排列的第一类电池单体的个数不超过n/2个。进一步可以不超过n/3个。作为示例，所述电池单元中连续排列的第一类电池单体的个数不超过5个，或不超过3个。例如，所述电池单元中连续排列的第一类电池单体的个数可以为1～10，1～8，1～5，1～3，2～3，或1～2。每隔适当数量的第一类电池单体设置第二类电池单体，能进一步降低电池模组的循环膨胀力，从而能进一步提高电池模组的循环寿命。
在一些实施方式中，第一类电池单体的个数n与第二类电池单体的个数m满足：5≤n+m≤30。可选的，8≤n+m≤25。进一步可选的，9≤n+m≤20。作为示例，第一类电池单体的个数n与第二类电池单体的个数m之和可以为5、6、7、8、9、10、11、12、13、14、15、16、17、18、19、20、21、22、23、24、25、26、27、28、29、或30。
在一些实施方式中，第一类电池单体的膨胀力变化率ΔF 1可以为6牛顿/圈～15牛顿/圈，7牛顿/圈～14牛顿/圈，7牛顿/圈～13牛顿/圈，7.3牛顿/圈～12.6牛顿/圈，或8.2牛顿/圈～12.6牛顿/圈。第一类电池单体的膨胀力变化率在适当范围内，能在保证其较高的能量密度的同时，保持电池模组内的循环膨胀力相对较低，从而进一步提高电池模组的循环寿命。此外，电池模组的安全性能也能得到提升。
在一些实施方式中，第二类电池单体的膨胀力变化率ΔF 2可以为0.9牛顿/圈～4.5牛顿/圈，1.4牛顿/圈～4牛顿/圈，1.6牛顿/圈～3.3牛顿/圈，1.2牛顿/圈～3.5牛顿/圈，1.2牛顿/圈～2.3牛顿/圈，或1.4牛顿/圈～1.6牛顿/圈。第二类电池单体的膨胀力变化率较低，能更有效地降低整个电池模组的循环膨胀力。尤其是，采用较少的该第二类电池单体，即可有效降低整个电池模组内的循环膨胀力，由此能更加表现出第一类电池单体的高能体积量密度优势，使电池模组的体积能量密度进一步提升。
在一些实施方式中，电池模组可满足(VED 1×n+VED 2×m)/(n+m)≥0.7×VED 1。可选的，(VED 1×n+VED 2×m)/(n+m)≥0.75×VED 1，(VED 1×n+VED 2×m)/(n+m)≥0.78×VED 1，(VED 1×n+VED 2×m)/(n+m)≥0.8×VED 1，或(VED 1×n+VED 2×m)/(n+m)≥0.83×VED 1。本申请的电池模组中，(VED 1×n+VED 2×m)/(n+m)代表电池模组中电池单体的体积能量密度平均值，当(VED 1×n+VED 2×m)/(n+m)满足上述关系时，组配形成的电池模组能在保证循环膨胀力较低、长期循环寿命得到有效改善的同时，还具有较高的体 积能量密度。
在一些实施方式中，电池模组可满足VED 2×m/(VED 1×n+VED 2×m)×100％≤65％。可选的，VED 2×m/(VED 1×n+VED 2×m)×100％≤60％，≤55％，≤50％，≤45％，或≤40％。可选的，VED 2×m/(VED 1×n+VED 2×m)×100％≥10％，≥15％，≥20％，≥25％，≥30％，或≥35％。可选的，20％≤VED 2×m/(VED 1×n+VED 2×m)×100％≤40％。可选的，30％≤VED 2×m/(VED 1×n+VED 2×m)×100％≤40％。本申请的电池模组中，第一类电池单体的膨胀力变化率和第二类电池单体的膨胀力变化率之间，以及第一类电池单体的体积能量密度和第二类电池单体的体积能量密度之间均满足特定关系，能使电池模组同时兼顾较高的循环寿命和较高的体积能量密度。
在一些实施方式中，电池模组的体积能量密度VED可以≥300Wh/L，≥350Wh/L，或≥360Wh/L。可选的，VED≤410Wh/L，≤400Wh/L，或≤390Wh/L。
为了使电池模组的VED在所述范围内，可选的，第一类电池单体的体积能量密度VED 1可以为450Wh/L～650Wh/kL，500Wh/L～620Wh/L，520Wh/L～610Wh/L，或550Wh/L～600Wh/L。第一类电池单体的体积能量密度较高，有利于提升电池模组的体积能量密度。并且可选的，第二类电池单体的体积能量密度VED 2可以为250Wh/L～450Wh/L，300Wh/L～410Wh/L，或340Wh/L～380Wh/L。第二类电池单体在具有较低的膨胀力变化率的同时，体积能量密度可以在250Wh/L以上，甚至300Wh/L以上，由此能使采用其的电池模组在改善循环膨胀力的同时，还获得较高的体积能量密度。
在一些实施方式中，所述第一类电池单体的标称容量C1与所述第二类电池单体的标称容量C2满足：0.9≤C1/C2≤1.1。电池单体的实际容量是指在一定条件(如0.2C)下，电池单体实际放出的电量。电池单体在不同放电制度下所给出的电量也不相同，这种未标明放电制度下的电池单体实际容量通常用标称容量来表示。标称容量是实际容量的一种近似表示方法。电池单体的放电电流强度、温度和放电截止电压，称为电池单体的放电制度。本申请中，作为示例的，电池单体的标称容量的放电制度为：放电电流强度为50A、温度在25℃、放电截止电压根据该电池单体的正极活性物质种类确定。所述第一类电池单体的标称容量C1与所述第二类电池单体的标称容量C2在上述范围内时，可以保证电池模组或电池包的对外能量输出较高，同时，由于第一类电池单体的体积能量密度高于第二类电池单体，因此第一类电池单体与第二类电池单体的体积差异在一定范围内，对于改善电池模组或电池包整体的膨胀力效果更加显著。
电池单体的放电截止电压为其自身的特性。例如，正极活性物质为锂镍钴锰氧化物或锂镍钴铝氧化物时，放电截止电压为2.8V。正极活性物质为磷酸铁锂(LiFePO 4)时， 放电截止电压范围可选为2.5V。当正极活性物质材料为两种材料混合时，放电截止电压可按照混合占比多的材料为准。
在本申请的电池模组中，电池单元中的n个第一类电池单体和m个第二类电池单体可以是彼此面面相对设置。这样能使电池模组具有更高的体积能量密度。还可以在电池单元的n个第一类电池单体和m个第二类电池单体设置中设置缓冲垫或预留膨胀空间。这样能进一步提高电池模组的循环寿命。
在本申请的电池模组中，第一类电池单体和第二类电池单体进行电连接，以便于以所需的电压和电流对外输出电能或进行储存电能。电池单元中的第一类电池单体和第二类电池单体可以以串联或串/并联组合的方式电连接。在本申请中，当第一类电池单体和第二类电池单体至少以串联的方式电连接后，第一类电池单体和第二类电池单体会同步的进行充电/放电过程，不同类型电池单体的体积膨胀变化协同进行，有利于在设计阶段提前预期电池模组整体的体积膨胀率，更便于调制电池模组循环寿命的改善幅度。在一个具体的示例中，第一类电池单体和第二类电池单体的电连接方式为串联连接。
[第一类电池单体]
第一类电池单体中，第一正极极片包括第一正极集流体和设置于第一正极集流体至少一个表面上且包含第一正极活性物质的第一正极膜层。第一正极活性物质具有较高的克容量。可选的，第一正极活性物质可包括锂过渡金属氧化物、锂过渡金属氧化物添加其它过渡金属或非过渡金属或非金属得到的氧化物中的一种或几种。其中过渡金属可以是Mn、Fe、Ni、Co、Cr、Ti、Zn、V、Al、Zr、Ce及Mg中的一种或几种。例如，第一正极活性物质可选自锂镍氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物中的一种或几种。
在一些实施方式中，第一正极活性物质可包括锂过渡金属氧化物Li 1+x1Ni aCo bM 1-a-bO 2- y1A y1，其中，-0.1≤x1≤0.2，0.5≤a＜0.95，0＜b＜0.2，0a+b＜1，0≤y1＜0.2，M选自Mn、Fe、Cr、Ti、Zn、V、Al、Zr和Ce中的一种或几种，并且A选自S、F、Cl和I中的一种或几种。可选的，0.5≤a≤0.85。可选的，0.5≤a≤0.8。可选的，M包括或是Mn或Al。
所述第一正极活性物质的克容量较高，并且采用其的第一正极极片可获得较高的面密度和压实密度，使得第一类电池单体可获得较高的体积能量密度(例如前文所述的VED 1)，由此能使电池模组具有较高的体积能量密度。
在一些实施方式中，第一正极活性物质包括体积平均粒径D v50在2μm～8μm的单颗粒。所述单颗粒为独立分散的一次颗粒、或由一次颗粒少量(例如2～5个)团聚而成的 颗粒形态。可选的，所述单颗粒中，一次颗粒的粒径不低于1μm。可选的，第一正极活性物质中包含所述的单颗粒，能提高采用其的第一正极极片的抗压性能。在电池模组中的循环膨胀力作用下，第一正极极片仍能保持较高的电解液浸润性和保持量，由此确保第一正极活性物质容量性能的有效发挥，从而能进一步提高电池模组的循环寿命。
在一些实施方式中，所述单颗粒在所述第一正极活性物质中，具有单颗粒形态的第一正极活性物质数量占比≥40％。可选的，单颗粒在第一正极活性物质的数量占比为40％～100％，50％～100％，50％～90％，60％～100％，60％～80％，70％～100％，或80％～100％。第一正极活性物质中包含较多的所述单颗粒，能进一步提高电池模组的循环寿命。
在一些实施方式中，第一正极活性物质还可包括聚集度大于单颗粒的二次颗粒。聚集度用二次颗粒中所包含的一次颗粒的数量来表征。可选的，二次颗粒的聚集度≥300，≥500，或≥800。第一正极活性物质中包含聚集度大于单颗粒的二次颗粒，有利于提高活性离子在第一正极极片中的传输能力，由此可降低电池极化，进一步提高电池模组在低温下的循环寿命。
可选的，二次颗粒在第一正极活性物质的数量占比可以≥10％，≥40％，或≥60％。进一步可选的，聚集度大于单颗粒的二次颗粒在第一正极活性物质的数量占比可以≤100％，≤90％，≤80％，或≤50％。
在一些实施方式中，第一正极膜层可包括第一正极活性物质以及可选的粘结剂和/或导电剂。其中，粘结剂可选自本领域公知的粘结剂，导电剂可选自本领域公知的导电剂。作为示例，粘结剂可选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、乙烯-醋酸乙烯酯共聚物(EVA)、聚乙烯醇(PVA)及聚乙烯醇缩丁醛(PVB)等中的一种或几种。作为示例，导电剂可选自超导碳、炭黑(例如乙炔黑、科琴黑、Super P等)、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或几种。
在一些实施方式中，可选的，第一正极膜层的面密度CW 3可以为15.00mg/cm 2～20.00mg/cm 2，例如17.50mg/cm 2～20.00mg/cm 2。可选的，第一正极膜层的压实密度PD 3可以为3.0g/cm 3～3.5g/cm 3，或3.25g/cm 3～3.45g/cm 3。
第一类电池单体中，第一正极集流体可采用本领域公知的正极集流体，例如铝箔。
第一类电池单体中，第一负极极片可包括第一负极集流体和设置于第一负极集流体至少一个表面上且包含第一负极活性物质的第一负极膜层。
通过合理调整第一负极极片中第一负极活性物质的种类、第一负极膜层的面密度、压实密度，可以使第一负极极片和第一正极极片的比容量相匹配，使得第一类电池单体 获得较高的体积能量密度(例如前文所述的VED 1)；同时还可以使第一类电池单体的膨胀力变化率ΔF 1满足前文所述的需求。
在一些实施方式中，第一负极活性物质可包括人造石墨、天然石墨中的一种或几种。相对于其它负极活性物质来说，石墨负极材料的克容量较高，且循环膨胀较小，由此可改善第一类电池单体的体积能量密度和循环性能，从而可提升电池模组的体积能量密度和循环寿命。
在一些实施方式中，第一负极膜层可包括第一负极活性物质以及可选的粘结剂、可选的导电剂和其它可选助剂。其中，粘结剂可选自本领域公知的粘结剂。作为示例，粘结剂可选自丁苯橡胶(SBR)、水性丙烯酸树脂、聚乙烯醇(PVA)等中的一种或几种。导电剂可选自本领域公知的导电剂。作为示例，导电剂可选自超导碳、炭黑(例如乙炔黑、科琴黑、Super P等)、碳点、碳纳米管、石墨烯及碳纳米纤维中一种或几种。其它可选助剂例如是增稠剂，如羧甲基纤维素钠(CMC-Na)，再例如是PTC热敏电阻材料等。
在一些实施方式中，第一负极膜层的面密度CW 1可以为9.70mg/cm 2～11.68mg/cm 2。可选的为10.38mg/cm 2～11.36mg/cm 2。第一负极膜层的CW 1在适当范围内，既能使第一类电池单体获得较高的体积能量密度，还能减小活性离子的扩散阻抗，提升第一类电池单体的循环寿命，从而提升电池模组的循环寿命。
在一些实施方式中，第一负极膜层的压实密度PD 1可以为1.35g/cm 3～1.65g/cm 3。可选的为1.40g/cm 3～1.60g/cm 3，1.45g/cm 3～1.60g/cm 3，或1.45g/cm 3～1.55g/cm 3。第一负极膜层的PD 1在适当范围内，能使第一类电池单体获得较高的体积能量密度，同时第一负极膜层中的第一负极活性物质之间形成紧密接触和良好的孔隙结构，具有较高的活性离子扩散性能，降低负极发生析锂的风险，由此能提升第一类电池单体的循环寿命和安全性能。因此，电池模组的循环寿命和安全性能也得到提升。
第一类电池单体中，第一负极集流体可采用本领域公知的负极集流体，例如铜箔。
第一类电池单体中，隔离膜设置在第一正极极片和第一负极极片之间，起到隔离的作用。可以根据需求来选用本领域已知的隔离膜。例如，隔离膜可包括玻璃纤维膜、无纺布膜、聚乙烯膜、聚丙烯膜、聚偏二氟乙烯膜以及包括它们中的两种以上的多层复合薄膜。
第一类电池单体中，电解液可包括有机溶剂和锂盐。其中有机溶剂和锂盐的种类及电解液的组成均不受到具体的限制，可根据需求进行选择。
作为示例，有机溶剂可包括碳酸亚乙酯(EC)、碳酸亚丙基酯(PC)、碳酸甲乙酯 (EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1，4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
作为示例，锂盐可包括LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或几种。
在一些实施方式中，电解液中还可选地包括添加剂。对添加剂的种类没有具体的限制，可根据需求进行选择。例如添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
第一类电池单体中，外包装用于封装电芯和电解液。外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。外包装也可以是软包，例如袋式软包装。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。
[第二类电池单体]
第二类电池单体中，第二正极极片包括第二正极集流体和设置于第二正极集流体至少一个表面上且包含第二正极活性物质的第二正极膜层。可选的，第二正极活性物质可包括橄榄石结构的含锂磷酸盐及其改性材料中的一种或几种。所述改性材料可以是对橄榄石结构的含锂磷酸盐进行掺杂改性和/或包覆改性。
在一些实施方式中，第二正极活性物质可包括含锂磷酸盐LiFe 1-x2-y2Mn x2M’ y2PO 4，其中，0≤x2≤1，0≤y2≤0.1，M’选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的一种或几种。可选的，第二正极活性物质可包括LiFePO 4(磷酸铁锂，可简写为LFP)、LiMnPO 4、LiMn 1-x3Fe x3PO 4、LiV 1-x3Fe x3PO 4中的一种或几种，其中x3独立地满足0＜x3＜1。所述第二活性物质的循环稳定性较好，并且采用其的第二正极极片的压实密度通常较低，与该第二正极极片相匹配的第二负极极片的面密度相应地较低，具有较低的极片反弹以及较好的电解液浸润性能，由此有利于第二类电池单体获得较低的循环膨 胀力和较高的循环寿命，从而使电池模组获得较低的循环膨胀力和较高的循环寿命。
在一些实施方式中，第二正极活性物质可包括体积平均粒径D v50为800nm～1.5μm的单颗粒。第二正极活性物质中包含所述的单颗粒，能提高采用其的第二正极极片的抗压性能。在电池模组中的循环膨胀力作用下，第二正极极片仍能保持较高的电解液浸润性和保持量，由此确保第二正极活性物质容量性能的有效发挥，从而能进一步提高电池模组的循环寿命。
在一些实施方式中，单颗粒在第二正极活性物质的数量占比≥60％。可选的，单颗粒在第二正极活性物质的数量占比为60％～100％，70％～100％，或80％～100％。第二正极活性物质中包含较多的所述单颗粒，能进一步提高电池模组的循环寿命。
在一些实施方式中，第二正极膜层可包括第二正极活性物质以及可选的粘结剂和/或导电剂。其中，粘结剂可选自本领域公知的粘结剂，导电剂可选自本领域公知的导电剂，例如本文所述的粘结剂和导电剂。
在一些实施方式中，可选的，第二正极膜层的面密度CW 4可以为18.00mg/cm 2～28.00mg/cm 2，例如18.00mg/cm 2～20.00mg/cm 2。可选的，第二正极膜层的压实密度PD4可以为2.00g/cm 3～2.50g/cm 3，或2.20g/cm 3～2.40g/cm 3。
第二类电池单体中，第二正极集流体可采用本领域公知的正极集流体，例如铝箔。
第二类电池单体中，第二负极极片可包括第二负极集流体和设置于第二负极集流体至少一个表面上且包含第二负极活性物质的第二负极膜层。
通过合理调整第二负极极片中第二负极活性物质的种类、第二负极膜层的面密度、压实密度，可以使第二负极极片和第二正极极片的比容量相匹配，使得第二类电池单体的体积能量密度和膨胀力变化率满足前文所述的需求。
在一些实施方式中，第二负极活性物质可包括人造石墨、天然石墨中的一种或几种。
在一些实施方式中，第二负极膜层可包括第二负极活性物质以及可选的粘结剂、导电剂和/或其它添加剂。其中，粘结剂可选自本领域公知的粘结剂，导电剂可选自本领域公知的导电剂，其它添加剂可选自本领域公知的用于负极膜层的添加剂。例如本文所述的粘结剂、导电剂和其它添加剂。
在一些实施方式中，第二负极膜层的面密度CW 2可以为6.50mg/cm 2～9.70mg/cm 2，或8.11mg/cm 2～9.40mg/cm 2。第二负极膜层的CW 2在适当范围内，既能使第二类电池单体获得较高的体积能量密度，还能减小活性离子的扩散阻抗，提升第二类电池单体的循环寿命，从而提升电池模组的循环寿命。
在一些实施方式中，第二负极膜层的压实密度PD 2可以为1.35g/cm 3～1.65g/cm 3，1.45g/cm 3～1.60g/cm 3，或1.45g/cm 3～1.55g/cm 3。第二负极膜层的PD 2在适当范围内，能使第二类电池单体获得较高的体积能量密度，同时第二负极膜层中的第二负极活性物质之间形成紧密接触和良好的孔隙结构，具有较高的活性离子扩散性能，降低负极发生析锂的风险，由此能提升第二类电池单体的循环寿命和安全性能。因此，电池模组的循环寿命和安全性能也得到提升。
第二类电池单体中，第二负极集流体可采用本领域公知的负极集流体，例如铜箔。
第二类电池单体中，隔离膜设置在第二正极极片和第二负极极片之间，起到隔离的作用。可以根据需求来选用本领域已知的隔离膜。例如本文所述的隔离膜。
第二类电池单体中，电解液可包括有机溶剂和锂盐。电解液中还可选的包括添加剂。其中有机溶剂、锂盐和添加剂的种类及电解液的组成均不受到具体的限制，可根据需求进行选择。例如本文所述的有机溶剂、锂盐和添加剂。
第二类电池单体中，外包装用于封装电芯和电解液。可选的，第二类电池单体的外包装可采用本文所述的外包装。
图1示出作为一个示例的电池模组4。参照图1，在电池模组4中可包含一个电池单元，该电池单元中的n个第一类电池单体5a和m个第二类电池单体5b沿电池模组4的长度方向(例如L方向)排列设置。进一步可以通过紧固件将电池单元进行固定。
图2示出作为另一个示例的电池模组4。参照图2，在电池模组4中可包含两个以上的电池单元。电池单元的数量可根据实际需求来调节。其中，各电池单元中的n个第一类电池单体5a和m个第二类电池单体5b沿电池模组4的长度方向(例如L方向)排列设置，该两个以上的电池单元沿电池模组4的宽度方向(例如W方向)排列设置。当然，该两个以上的电池单元也可以按照其他方式排列。进一步可以通过紧固件将该两个以上的电池单元进行固定。
可选的，电池模组4还可以包括具有容纳空间的外壳，电池单元容纳于该容纳空间。
图3示出作为一个示例的六面体形状的电池单体5，其可以是第一类电池单体5a或第二类电池单体5b。图4是其分解示意图。参照图4，电池单体5的外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。电芯52封装于所述容纳腔。电解液浸润于电芯52中。需要注意的是，图3和图4所示的电池单体5为硬壳电池，但不限于此。电池单体5可以是袋型电池，即壳体51由诸如金属塑膜等软包替代且取消顶盖组件53。电池单体5作为第一类电池单体5a或第二类 电池单体5b时所含电芯52的数量可以为一个或几个，可根据需求来调节。
在本申请中，膨胀力变化率表示电池单体在25℃下、以0.33C 0倍率(C 0表示电池单体标称容量)、在电池单体相应的上限截止电压和下限截止电压范围内，循环充放电500圈的平均膨胀力变化ΔF/500，其中ΔF＝F 500-F 0，F 500表示电池单体在循环500圈后检测装置传感器测到的所述电池单体的压力(即电池单体此时的膨胀力)，F 0表示电池单体循环起始时检测装置传感器测到的所述电池单体的压力(即电池单体此时的膨胀力)。电池单体在循环过程中的膨胀力可采用本领域已知的方法和装置进行测试。例如图5和图6示出的一种检测装置10。如图5和图6所示，检测装置10包括夹具组件11和压力传感器12，夹具组件11包括三片钢板夹具，将待测电池单体夹持于其中两个夹具之间，其中电池单体的大面与钢板夹具面面接触；将压力传感器12夹持于另一个夹具与前述两个夹具中的任一者之间，其中压力传感器12连接至压力采集器(如计算机)。其中，钢板厚度为30mm。钢板以及钢板间连接件的材质可以为45号钢，进一步地可以在钢板表面镀铬。钢板间预紧件的直径可选的为15mm。夹具四角预紧件直线围成的矩形面积需大于或等于电池单体的大面面积。通过钢板夹具向待测电池单体施加预紧力(例如，电池单体为硬壳电池时，预紧力可以选3KN；电池单体为袋型电池时，预紧力可以选1KN)且在测试过程中一直保持，该预紧力记为待测电池单体起始时的膨胀力F 0。为了使电池单体和压力传感器各处的受力更加均匀，电池单体和压力传感器可以夹持在夹具的中央位置，并且把夹具四角的预紧件(例如螺丝)按照对角线的方式交替调紧，最后微调四角的预紧件达到所需的预紧力。然后，在周围环境温度设置为25℃的条件下，以0.33C 0恒流充电至上限截止电压，再恒压充电至电流小于0.05C 0，静置10min，然后以0.33C 0恒流放电至下限截止电压，记为一个循环。将电池单体以此进行500圈充放电循环，实时监测电池单体的膨胀力。最后根据ΔF/500计算得到电池单体的膨胀力变化率。
电池单体的上限截止电压和下限截止电压为其自身的特性。例如，正极活性物质为锂镍钴锰氧化物时，充放电电压范围为2.8V～4.5V；其中Ni原子占锂镍钴锰氧化物中过渡金属原子的80％时，充放电电压范围可选2.8V～4.25V；Ni原子占锂镍钴锰氧化物中过渡金属原子的60％～70％时，充放电电压范围可选为2.8V～4.4V；Ni原子占锂镍钴锰氧化物中过渡金属原子的50％时，充放电电压范围可选为2.8V～4.35V。正极活性物质为锂镍钴铝氧化物时，充放电电压范围可选为2.8V～4.3V。正极活性物质为磷酸铁锂(LiFePO 4)时，充放电电压范围可选为2.5V～3.65V。当正极活性物质材料为两种材料混合时，电压范围可按照混合占比多的材料为准。
在本申请中，电池单体、电池模组的体积能量密度为本领域公知的含义，可采用本 领域已知的方法测试。例如，电池单体的体积能量密度为在电池单体的上限截止电压和下限截止电压的范围内时电池单体所具有的最大能量除以电池外壳体积(长×宽×肩高)，其中，肩高为电池总高度减去电极端子高度后的剩余高度。电池模组的体积能量密度为电池模组中所有电池单体的能量的总和除以电池模组的总体积(长×宽×高)，其中，电池模组的总体积包括所有电池单体的体积，以及电池模组的其他构成部件(包括但不限于线束、端板和/或侧板、以及顶盖板)。
在本申请中，第二类电池单体的体积和第一类电池单体的体积均以其外表面围合的体积计，且忽略电极端子的体积。
在本申请中，负极膜层的面密度为本领域公知的含义，指的是单位面积上负极集流体单侧的负极膜层质量，可采用本领域已知的方法测定。例如取单面涂布且经冷压后的负极极片(若是双面涂布的负极极片，可先擦拭掉其中一面的负极膜层)，冲切成面积为S1的小圆片，称其重量，记录为M1。然后将上述称重后的负极极片的负极膜层擦拭掉，称量负极集流体的重量，记录为M0，负极膜层的面密度＝(负极极片的重量M1-负极集流体的重量M0)/S1。
负极膜层的压实密度＝负极膜层的面密度/负极膜层的厚度。其中，负极膜片的厚度为本领域公知的含义，指的是负极集流体单侧的负极膜层厚度，可采用本领域已知的方法测定。例如4位精度的螺旋测微仪。
在本申请中，可采用本领域已知的方法测试单颗粒在正极活性物质中的数量占比。示例性测试方法如下：裁剪1cm×1cm的正极极片，粘贴到样品台上作为待测样品；将样品台装入真空样品仓内并固定好，采用截面抛光仪(例如JEOL IB-09010CP)制备极片沿厚度方向的截面；采用扫描电镜&能谱仪(如ZEISS sigma300)对待测样品中颗粒进行测试。测试可参考JY/T010-1996。
为了确保测试结果的准确性，可在待测样品中随机选取10个不同区域进行扫描测试，并在一定放大倍率(例如5000倍)下，统计各区域中单颗粒数量与总颗粒数量的比值，即为该区域中单颗粒的数量占比；取10个测试区域的测试结果的平均值作为正极活性物质中单颗粒的数量占比。
在本申请中，正极活性物质中，单颗粒中的一次颗粒粒径为本领域公知的含义，可采用本领域已知的方法测定。示例性测试方法如下：采用乙醇浸泡将正极膜层从正极集流体剥离，超声波反复清洗、烘干、并在300～400℃下烧粉，将烧结后得到的样品置于样品台上作为待测样品；将样品台装入真空样品仓内并固定好，采用扫描电镜&能谱仪(如ZEISS sigma300)对待测样品中颗粒表面形貌进行测试。
为了确保测试结果的准确性，可在待测样品中随机选取10个不同区域进行扫描测试，并在一定放大倍率(例如5000倍)下，统计各区域中单颗粒中一次颗粒的数量与最大直径。
在本申请中，正极活性物质的体积平均粒径D v50为本领域公知的含义，表示正极活性物质累计体积分布百分数达到50％时所对应的粒径，其可以用本领域公知的仪器及方法进行测定。例如可参照GB/T 19077-2016粒度分布激光衍射法，采用激光粒度分析仪方便地测定，如英国马尔文仪器有限公司的Mastersizer 2000E型激光粒度分析仪。
制造方法
本申请另一方面提供一种电池模组的制造方法，其包括以下步骤：
获取n个第一类电池单体和m个第二类电池单体，其中VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L；VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L；ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈；ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈；
将所述n个第一类电池单体和m个第二类电池单体排列设置，形成电池模组。
采用本申请的制造方法的电池模组可具有较低的循环膨胀力，因而能具有较高的循环寿命。
可选的，所述n个第一类电池单体和m个第二类电池单体的电连接方式包括：将n个第一类电池单体和m个第二类电池单体以串联或串/并联组合的方式电连接。
本申请中电池模组的技术特征也适用于电池模组的制造方法中，并产生相应的有益效果。
第一类电池单体和第二类电池单体均可商购获得或采用本领域已知的方法制备得到。作为示例，可以将正极极片、隔离膜和负极极片经堆叠工艺或卷绕工艺形成电芯；将电芯装入外包装中，注入电解液，经封装等后续工序后，得到电池单体。
正极极片可按照本领域常规方法制备。例如，将正极活性物质、导电剂和粘结剂分散于溶剂中，形成均匀的正极浆料，溶剂例如是N-甲基吡咯烷酮(NMP)；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，得到正极极片。
负极极片可以按照本领域常规方法制备。例如，将负极活性物质、导电剂、粘结剂和增稠剂分散于溶剂中，形成均匀的负极浆料，溶剂例如是去离子水；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，得到负极极片。
制造设备
本申请另一方面提供一种电池模组的制造设备，其包括夹臂单元、组装单元和控制单元。
夹臂单元用于获取n个第一类电池单体和m个第二类电池单体，其中VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，ΔF2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈。
组装单元用于将所述n个第一类电池单体和m个第二类电池单体排列设置。
控制单元用于控制所述夹臂单元和所述组装单元进行工作。
夹臂单元、组装单元及控制单元均可根据实际需求选择本领域公知的装置或器件。
采用本申请的制造设备制造的电池模组可具有较低的循环膨胀力，因而能具有较高的循环寿命。
电池包
本申请另一方面还提供一种电池包，其中包括本申请任意一种或几种电池模组。电池包所含电池模组的数量可以根据电池包的应用和容量进行调节。可选的，电池包中还可以进一步包含电池管理系统模块(BMS)、冷却/加热部件等辅助构件。
在一些实施方式中，电池包包括两个以上的电池模组，每个电池模组均为本申请所述的电池模组。该电池包内的循环膨胀力大幅缓解，因而其循环寿命能得到显著提升。另外，电池包还可具有较高的体积能量密度。
图7和图8作为一个示例的电池包1。参照图7和图8，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模组4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模组4的封闭空间。多个电池模组4可以按照任意的方式排布于电池箱中。
装置
本申请另一方面还提供一种装置，所述装置包括本申请所述的电池模组或电池包。所述电池模组或电池包可用作装置的电源，用于给装置提供动力；也可以作为装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。所述装置可以根据其使用需求来选择电化学装置，如一次电池、二次电池、电池模块或电池包。
图9是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。该装置可以采用电池包或电池模组。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于重量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例1
第一类电池单体的制备：
正极极片的制备
将第一正极活性物质LiNi 0.5Co 0.2Mn 0.3O 2、导电剂Super-P、粘结剂PVDF按照重量比95∶2∶3分散于溶剂NMP中，充分搅拌混合均匀得到正极浆料；将正极浆料涂覆于正极集流体铝箔的相对两个表面，经烘干、冷压后，得到第一正极极片。其中，正极膜层的面密度为18.83mg/cm 2，压实密度为3.25g/cm 3；第一正极活性物质中的单颗粒数量占比为100％。
负极极片的制备
将第一负极活性物质天然石墨、导电剂Super-P、粘结剂SBR及增稠剂CMC-Na按照重量比93∶3∶2∶2分散于溶剂去离子水中，搅拌混合均匀后得到负极浆料。之后将负极浆料涂覆在负极集流体铜箔的相对两个表面，经烘干、冷压后，得到负极极片。其中，负极膜层的面密度为11.62mg/cm 2，压实密度为1.45g/cm 3。
电解液的制备
将碳酸亚乙酯(EC)、碳酸亚丙酯(PC)及碳酸二甲酯(DMC)按照重量比为1∶1∶1混合均匀，得到有机溶剂；再将锂盐LiPF 6溶解于上述有机溶剂中，混合均匀，得到电解液，其中LiPF 6的浓度为1mol/L。
第一类电池单体的制备
将第一正极极片、聚乙烯多孔隔离膜、第一负极极片按顺序层叠好，然后卷绕得到电芯；将电芯装入外包装中，注入电解液并封装，得到第一类电池单体。其中，第一类电池单体的群裕度为99.0％。第一类电池单体的体积能量密度为552Wh/L。
第二类电池单体的制备：
第二类电池单体的制备方法与第一类电池单体的制备方法类似，区别在于：调整正 极极片和负极极片的制备参数，不同之处详见表1。
电池模组的制备：
取6个第一类电池单体和14个第二类电池单体；将该6个第一类电池单体和14个第二类电池单体沿电池模组的长度方向排列排列，并串联连接，上述多个电池单体在电池模组中的排列次序为BBBABBBAABBBAABBBABB，其中，第一类电池单体记为A，第二类电池单体记为B；并装入外壳中，形成电池模组。
图10示出了实施例1中第一类电池单体的膨胀力随循环圈数变化的曲线图。图11示出了实施例1中第二类电池单体的膨胀力随循环圈数变化的曲线图。可以看到，具有较高体积能量密度的第一类电池单体具有较高的膨胀力变化率。具有较低体积能量密度的第二类电池单体的膨胀力变化率很小，在循环充放电的过程中，膨胀力变化较平缓。
实施例2～13和对比例1～4
第一类电池单体、第二类电池单体和电池模组的制备方法与实施例1类似，区别在于：调整第一类电池单体和第二类电池单体中正极极片和负极极片的制备参数，以及调整电池模组的制备参数，不同之处详见表1至表4。
测试部分
(1)按照前文描述的方法测试电池模组的体积能量密度。
(2)电池单体群裕度测试
分别测量所有正极极片、负极极片和隔离膜圈绕后的裸电芯的总体积V 1，以及电池外包装空壳时的内部体积V t。电池单体的群裕度＝V 1/V t×100％。
(3)电池模组的循环寿命测试
将电池模组放在高低温箱内，保持温度恒定在25℃。以0.33C(C表示第一类电池单体的标称容量)作为充放电倍率。先以0.33C充电到电池模组额定上限截止电压，静置5分钟，再用0.33C放电到额定下限截止电压。静置5分钟。完成一次充放电过程记为一个循环，不断重复充放电，直至电池模组放电容量为起始容量的80％结束测试。其中，电池模组的额定上限截止电压是各电池单体额定上限截止电压之和，电池模组的额定下限截止电压是各电池单体额定下限截止电压之和。
(4)析锂测试
在25℃环境下，以1C(C表示第一类电池单体的标称容量)作为恒流充电倍率，1C作为放电倍率，循环充放电10次。结束析锂测试。
测试结果示于下面的表3。
Figure PCTCN2020105474-appb-000001
Figure PCTCN2020105474-appb-000002
表4：电池模组中第一类电池单体与第二类电池单体的排布方式
序号 排布方式(第一类电池单体-A；第二类电池单体-B)
实施例1 BBBABBBAABBBAABBBABB
实施例2 BBAABBBAABBBAABBBABB
实施例3 BAABBAABBAABBAABBAAB
实施例4 BAABBAABAAABBAAABAAB
实施例5 BAAABAAABAAABAAABAAB
实施例6 BAAABAAABBAABAAABAAB
实施例7 BAABBAABAAABBAABBAAB
实施例8 BAABBAABBAABBAABBAAB
实施例9 BAABBAABBAABBAABBAAB
实施例10 BBAABBABBAABBAABBABB
实施例11 BAABBAABBAABBAABBAAB
实施例12 BAABBAABBAABBAABBAAB
实施例13 BAABBAABBAABBAABBAAB
对比例1 AAAAAAAAAAAAAAAAAAAA
对比例2 BBBBBBBBBBBBBBBBBBBB
对比例3 AAAABAAAABAAAABAAAAA
对比例4 AAAAAABAAAAAABAAAAAA
由以上测试结果可知，本申请的实施例通过将体积能量密度较高但膨胀力变化率也较高的第一类电池单体与体积能量密度较低且膨胀力变化率也较低的第二类电池单体进行组配，同时控制第一类电池单体的膨胀力变化率和第二类电池单体的膨胀力变化率之间满足特定关系，使得电池模组同时兼顾较高的体积能量密度和较高的循环寿命。并且，电池模组中的电池单体发生析锂的风险显著降低，其安全性能也得到提升。
对比例1-4的电池模组不满足上述条件，因而不能同时兼顾较高的体积能量密度和较高的循环寿命。并且，电池模组中包含高体积能量密度的电池单体时，容易发生析锂。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (18)

  1. 一种电池模组，包括：
    电池单元，所述电池单元包括n个第一类电池单体和m个第二类电池单体，n≥1，m≥1，所述n个第一类电池单体和m个第二类电池单体排列设置，且满足：
    VED 1＞VED 2，
    ΔF 1＞ΔF 2，
    (ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
    其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
    VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
    ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
    ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈。
  2. 根据权利要求1所述的电池模组，其中，所述电池模组还满足以下两个条件至少其中之一：
    条件1：(VED 1×n+VED 2×m)/(n+m)≥0.7×VED 1；
    可选的，(VED 1×n+VED 2×m)/(n+m)≥0.78×VED 1；
    条件2：VED 2×m/(VED 1×n+VED 2×m)×100％≤65％；
    可选的，VED 2×m/(VED 1×n+VED 2×m)×100％≤50％；
    进一步可选的，20％≤VED 2×m/(VED 1×n+VED 2×m)×100％≤40％。
  3. 根据权利要求1或2所述的电池模组，其中，所述电池模组的体积能量密度VED≥300Wh/L；可选的，所述VED≥350Wh/L。
  4. 根据权利要求1至3任一项所述的电池模组，其中，(ΔF 1×n+ΔF 2×m)/(n+m)≤0.75×ΔF 1；可选的，0.5×ΔF 1≤(ΔF 1×n+ΔF 2×m)/(n+m)≤0.65×ΔF 1。
  5. 根据权利要求1至4任一项所述的电池模组，其中，所述ΔF 1为6牛顿/圈～15牛顿/圈；可选的，所述ΔF 1为7牛顿/圈～14牛顿/圈；进一步可选的，所述ΔF 1为7.3牛顿/圈～12.6牛顿/圈；和/或，
    所述ΔF 2为0.9牛顿/圈～4.5牛顿/圈；可选的，所述ΔF 2为1.2牛顿/圈～2.3牛顿/圈；进一步可选的，所述ΔF 2为1.4牛顿/圈～1.6牛顿/圈。
  6. 根据权利要求1至5任一项所述的电池模组，其中，所述膨胀力变化率为电池单体在25℃下、以0.33C 0倍率(C 0表示所述电池单体的标称容量)、在所述电池单体的上限截止电压和下限截止电压的范围内，循环充放电500圈后的平均膨胀力变化ΔF/500，所 述ΔF为所述电池单体在循环第500圈与循环起始时检测装置传感器测到的所述电池单体的压力的变化值。
  7. 根据权利要求1至6任一项所述的电池模组，其中，所述第一类电池单体的标称容量C1与所述第二类电池单体的标称容量C2满足：0.9≤C1/C2≤1.1。
  8. 根据权利要求1至7任一项所述的电池模组，其中，所述电池单元中连续排列的所述第一类电池单体的个数不超过n/2个；可选的不超过n/3个。
  9. 根据权利要求1至8任一项所述的电池模组，其中，所述第一类电池单体包括第一负极极片，所述第一负极极片包括含有第一负极活性物质的第一负极膜层，所述第一负极活性物质包括人造石墨、天然石墨中的一种或几种，
    所述第一负极膜层满足以下条件至少其中之一：
    条件1：所述第一负极膜层的面密度CW 1为9.70mg/cm 2～11.68mg/cm 2，可选的为10.38mg/cm 2～11.36mg/cm 2；
    条件2：所述第一负极膜层的压实密度PD 1为1.35g/cm 3～1.65g/cm 3，可选的为1.40g/cm 3～1.60g/cm 3。
  10. 根据权利要求1至9任一项所述的电池模组，其中，所述第一类电池单体包括第一正极极片，所述第一正极极片包含第一正极活性物质，所述第一正极活性物质包括式(I)所示的锂过渡金属氧化物，
    Li 1+x1Ni aCo bM 1-a-bO 2-y1A y1    式(I)
    其中，-0.1≤x1≤0.2，0.5≤a＜0.95，0＜b＜0.2，0＜a+b＜1，0≤y1＜0.2，M选自Mn、Fe、Cr、Ti、Zn、V、Al、Zr和Ce中的一种或几种，并且A选自S、F、Cl和I中的一种或几种；
    可选的，所述第一正极活性物质包括体积平均粒径D v50为2μm～8μm的单颗粒；
    进一步可选的，在所述第一正极活性物质中，具有单颗粒形态的第一正极活性物质数量占比≥40％。
  11. 根据权利要求1至10任一项所述的电池模组，其中，所述第二类电池单体包括第二负极极片，所述第二负极极片包括含有第二负极活性物质的第二负极膜层，所述第二负极活性物质包括人造石墨、天然石墨中的至少一种，
    所述第二负极膜层满足以下条件至少其中之一：
    条件1：所述第二负极膜层的面密度CW 2为6.50mg/cm 2～9.70mg/cm 2，可选的为8.11mg/cm 2～9.40mg/cm 2；
    条件2：所述第二负极膜层的压实密度PD 2为1.35g/cm 3～1.65g/cm 3，可选的为1.45 g/cm 3～1.60g/cm 3。
  12. 根据权利要求1至11任一项所述的电池模组，其中，所述第二类电池单体包含第二正极极片，所述第二正极极片包含第二正极活性物质，所述第二正极活性物质包括式(II)所示的含锂磷酸盐，
    LiFe 1-x2-y2Mn x2M’ y2PO 4        式(II)
    其中，0≤x2≤1，0≤y2≤0.1，M’选自除Fe、Mn外的过渡金属元素以及非过渡金属元素中的一种或几种；
    可选的，所述第二正极活性物质包括LiFePO 4、LiMnPO 4、LiMn 1-x3Fe x3PO 4、LiV 1- x3Fe x3PO 4中的一种或几种，其中x3独立地满足0<x3＜1，
    进一步可选的，所述第二正极活性物质包括体积平均粒径D v50为800nm～1.5μm的单颗粒。
  13. 根据权利要求1至12任一项所述的电池模组，其中，所述n个第一类电池单体和m个第二类电池为电连接，所述电连接至少包括串联；可选的，所述电连接为串联、或串/并联组合。
  14. 一种电池包，包括根据权利要求1至13任一项所述的电池模组。
  15. 根据权利要求14所述的电池包，其中，所述电池包包括两个以上的电池模组，可选的，每个所述电池模组均为根据权利要求1至13任一项所述的电池模组。
  16. 一种装置，包括根据权利要求1至13任一项所述的电池模组、或根据权利要求14或15所述的电池包，所述电池模组或所述电池包用于给所述装置提供动力或用于所述装置的能量存储单元。
  17. 一种电池模组的制造方法，包括以下步骤：
    获取n个第一类电池单体和m个第二类电池单体，其中
    VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，
    (ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
    其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
    VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
    ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
    ΔF 2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈；
    将所述n个第一类电池单体和m个第二类电池单体排列设置，形成所述电池模组。
  18. 一种电池模组的制造设备，包括：
    夹臂单元，用于获取n个第一类电池单体和m个第二类电池单体，其中
    VED 1＞VED 2，ΔF 1＞ΔF 2，n≥1，m≥1，
    (ΔF 1×n+ΔF 2×m)/(n+m)≤0.8×ΔF 1，
    其中，VED 1表示所述第一类电池单体的体积能量密度，单位为Wh/L，
    VED 2表示所述第二类电池单体的体积能量密度，单位为Wh/L，
    ΔF 1表示所述第一类电池单体的膨胀力变化率，单位为牛顿/圈，
    ΔF2表示所述第二类电池单体的膨胀力变化率，单位为牛顿/圈；组装单元，用于将所述n个第一类电池单体和m个第二类电池单体排列设置；控制单元，用于控制所述夹臂单元和所述组装单元。
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