WO2026007643A1 - 电池单体及其制备方法、电池和用电装置 - Google Patents

电池单体及其制备方法、电池和用电装置

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Publication number
WO2026007643A1
WO2026007643A1 PCT/CN2025/100273 CN2025100273W WO2026007643A1 WO 2026007643 A1 WO2026007643 A1 WO 2026007643A1 CN 2025100273 W CN2025100273 W CN 2025100273W WO 2026007643 A1 WO2026007643 A1 WO 2026007643A1
Authority
WO
WIPO (PCT)
Prior art keywords
pits
battery cell
lithium
positive electrode
battery
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2025/100273
Other languages
English (en)
French (fr)
Inventor
蔡梓熳
王瀚森
王禹淳
黄泽彧
黄圣源
冯富祥
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
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Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Publication of WO2026007643A1 publication Critical patent/WO2026007643A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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

  • This application relates to a battery cell and its preparation method, a battery, and an electrical device.
  • Lithium metal battery cells have a higher energy density than lithium-ion battery cells.
  • lithium metal battery cells use highly active lithium metal, and because of problems such as volume expansion and uneven deposition during the lithium metal stripping and deposition process, the cycle life of lithium metal battery cells is relatively poor.
  • This application provides a battery cell and its preparation method, a battery, and an electrical device, wherein the battery cell has a long cycle life.
  • the average size of the pits on the surface of the lithium metal layer of the negative electrode is 20 ⁇ m-160 ⁇ m, and the number density of pits is 208 to 320 per mm2 .
  • These pits expose fresh lithium metal, which can serve as preferential nucleation sites for subsequent lithium metal deposition.
  • lithium metal preferentially deposits at these nucleation sites, inducing uniform and dense deposition of subsequent lithium metal. This reduces the formation of dead lithium, lithium dendrites, etc., and also results in a lithium metal deposition morphology with a smaller specific surface area, reducing electrolyte consumption and lowering impedance and polarization. Therefore, the battery cell provided in this application embodiment has a long cycle life.
  • the average size of the pits is 20 ⁇ m-45 ⁇ m. An average pit size within this range can further improve the cycle life of the battery cell.
  • the number density of the pits is between 280 pits/ mm2 and 320 pits/ mm2 .
  • a pit density within this range can further improve the cycle life of the battery cell.
  • the proportion of pits with a maximum lateral dimension less than 50 ⁇ m is greater than or equal to 14%, and the proportion of pits with a maximum lateral dimension greater than 100 ⁇ m is greater than 0 and less than or equal to 55%.
  • the proportion of pits with a maximum lateral dimension less than 50 ⁇ m is greater than or equal to 48%, and the proportion of pits with a maximum lateral dimension greater than 100 ⁇ m is greater than 0 and less than or equal to 18%.
  • a high proportion of pits with a maximum lateral dimension less than 50 ⁇ m and a low proportion of pits with a maximum lateral dimension greater than 100 ⁇ m allows the negative electrode to have more preferential nucleation sites, thereby further reducing electrolyte consumption and further improving the cycle life of the battery cell.
  • the number density of pits with a maximum lateral dimension less than 50 ⁇ m is 30 to 202 pits/ mm2
  • the number density of pits with a maximum lateral dimension between 50 ⁇ m and 100 ⁇ m is 60 to 105 pits/mm2
  • the number density of pits with a maximum lateral dimension greater than 100 ⁇ m is 14 to 114 pits /mm2 .
  • the number density of pits with a maximum lateral dimension less than 50 ⁇ m is 130 to 202 pits/ mm2
  • the number density of pits with a maximum lateral dimension between 50 ⁇ m and 100 ⁇ m is 88 to 105 pits / mm2
  • the number density of pits with a maximum lateral dimension greater than 100 ⁇ m is 14 to 50 pits/ mm2 .
  • the depth of the pit is more than 10% of the thickness of the lithium metal layer and less than the thickness of the lithium metal layer.
  • the sum of the areas of the plurality of pits is 20%-50% of the area of the lithium metal layer.
  • the battery cell includes a positive electrode sheet, the positive electrode sheet includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes one or more of lithium phosphate, lithium transition metal oxide and their respective modified compounds.
  • the battery cell includes an electrolyte with a concentration of 1 mol/L to 6 mol/L.
  • this application provides a method for preparing a battery cell, comprising the following steps: assembling a lithium-poor positive electrode sheet and a negative electrode sheet to obtain a battery cell, wherein the negative electrode sheet includes a negative current collector and a lithium metal layer disposed on at least one surface of the negative current collector; subjecting the battery cell to pulse discharge to obtain a battery cell, wherein after pulse discharge, a plurality of pits are formed on the surface of the lithium metal layer, the average size of the pits being 20 ⁇ m-160 ⁇ m, and the number density of the pits being 208 pits/ mm2 to 320 pits/ mm2 .
  • pulse discharge can cause partial stripping of lithium metal from the surface of the negative electrode sheet. This allows multiple pits to form in situ on the lithium metal layer surface of the negative electrode sheet, and also releases some of the capacity lithium from the negative electrode into the lithium-poor positive electrode.
  • Using lithium-poor positive electrode sheets to assemble the battery cell also reduces damage to the positive electrode active material caused by the initial pulse discharge. Furthermore, the battery cell preparation method provided in this application is simple to operate and has low production costs.
  • the starting current of the pulse discharge is less than or equal to 3C, and the cutoff current of the pulse discharge is 0.05C-0.50C.
  • the starting current of the pulse discharge is less than or equal to 1C, and the cutoff current of the pulse discharge is 0.05C-0.10C.
  • the lithium-poor positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.
  • the positive electrode film layer includes a lithium-poor phase positive electrode active material, which includes one or more of lithium-poor phase phosphates, lithium-poor phase transition metal oxides, and their respective modified compounds.
  • this application provides a battery, including a battery cell according to the first aspect of this application or a battery cell prepared by the preparation method according to the second aspect of this application.
  • this application provides an electrical device, including the battery of the third aspect of this application.
  • the electrical device of this application includes the battery provided in this application, and therefore has at least the same advantages as the battery.
  • Figure 1 shows a schematic diagram of a battery cell provided in some embodiments of this application.
  • FIG. 2 shows a schematic diagram of a battery module provided in some embodiments of this application.
  • Figure 3 shows a schematic diagram of a battery pack provided in some embodiments of this application.
  • Figure 4 is an exploded view of the battery pack shown in Figure 3.
  • Figure 5 shows a scanning electron microscope (SEM) image of the negative electrode sheet provided in some embodiments of this application.
  • Figure 6 shows a schematic diagram of an electrical device provided in some embodiments of this application.
  • ranges disclosed in this application are defined by a lower limit and an upper limit.
  • a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.
  • the numerical range "a-b” represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers.
  • the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations.
  • a parameter is stated as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • steps in this application may be performed sequentially or randomly, preferably sequentially.
  • the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially.
  • the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order.
  • the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.
  • “above” or “below” the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, “above,” “over,” and “on top” can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. “Below,” “below,” and “under” the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
  • the values of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.
  • the battery mentioned in the embodiments of this application can be a single physical module comprising one or more battery cells to provide higher voltage and capacity.
  • the battery mentioned in this application can include battery cells, battery modules, or battery packs.
  • a battery cell is the smallest unit that makes up a battery, and it can independently perform the functions of charging and discharging.
  • a battery cell can be cylindrical, cuboid, or other shapes, and the embodiments of this application are not limited to this.
  • Figure 1 shows a cuboid battery cell 5 as an example.
  • the battery can be a battery module; when there are multiple battery cells, they are arranged and fixed to form a battery module.
  • the battery can be a battery pack, which includes a housing and battery cells, with the battery cells or battery modules housed within the housing.
  • the housing can be part of the vehicle's chassis structure. For example, a portion of the housing can be at least part of the vehicle's floor, or a portion of the housing can be at least part of the vehicle's crossbeams and longitudinal beams.
  • the battery can be an energy storage device.
  • Energy storage devices include energy storage containers, energy storage cabinets, etc.
  • individual battery cells can be assembled into a battery module.
  • the number of battery cells in a battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other arbitrary manner. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners.
  • the battery module 4 may also include a housing with a receiving space in which multiple battery cells 5 are received.
  • the battery modules described above can also be assembled into a battery pack, and 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 1 may include a housing and multiple battery modules 4 disposed within the housing.
  • the housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 and forming a closed space for accommodating the battery modules 4.
  • the multiple battery modules 4 can be arranged in the housing in any manner.
  • the battery cells provided in the embodiments of this application include lithium metal battery cells.
  • Each battery cell includes an electrode assembly and an electrolyte, and comprises a positive electrode, a negative electrode, and a separator.
  • the electrode assembly can be a wound structure or a stacked structure; this embodiment of the application is not limited in this regard.
  • the battery cell also includes an outer packaging, which can be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.
  • the outer packaging can also be a soft package, such as a pouch.
  • the material of the soft package can be aluminum-plastic film or plastic, such as one or more of polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).
  • Corrosion of the lithium metal anode is one of the important reasons for the cycle failure of lithium metal battery cells.
  • the battery cell As the battery cell is cycled for charging and discharging, lithium metal will continuously deposit and peel off on the surface of the lithium metal anode, forming a rough anode surface. This can easily lead to problems such as dead lithium, electrolyte consumption, and excessive polarization, resulting in poor cycle life of the battery cell.
  • this application provides a battery cell with a long cycle life, starting from the negative electrode sheet.
  • the battery cell provided in the embodiments of this application includes a negative electrode sheet, which includes a negative current collector and a lithium metal layer disposed on at least one surface of the negative current collector.
  • the surface of the lithium metal layer has multiple pits.
  • the average size of the pits is 20 ⁇ m-160 ⁇ m, and the number density of pits is 208 pits/ mm2 to 320 pits/ mm2 .
  • the surface of the lithium metal layer has multiple pits.
  • the average size of the pits on the surface of the lithium metal layer of the negative electrode is 20 ⁇ m-160 ⁇ m, and the number density of pits is 208 to 320 per mm2 .
  • These pits expose fresh lithium metal, which can serve as preferential nucleation sites for subsequent lithium metal deposition.
  • lithium metal preferentially deposits at these nucleation sites, inducing uniform and dense deposition of subsequent lithium metal. This reduces the formation of dead lithium, lithium dendrites, etc., and also results in a lithium metal deposition morphology with a smaller specific surface area, reducing electrolyte consumption and lowering impedance and polarization. Therefore, the battery cell provided in this application embodiment has a long cycle life.
  • the average size of the pit is 20 ⁇ m-160 ⁇ m, for example, it can be 20 ⁇ m, 21 ⁇ m, 22 ⁇ m, 23 ⁇ m, 24 ⁇ m, 25 ⁇ m, 26 ⁇ m, 27 ⁇ m, 28 ⁇ m, 29 ⁇ m, 30 ⁇ m, 32 ⁇ m, 34 ⁇ m, 36 ⁇ m, 38 ⁇ m, 40 ⁇ m, 42 ⁇ m, 44 ⁇ m, 46 ⁇ m, 48 ⁇ m, 50 ⁇ m, 52 ⁇ m, 54 ⁇ m, 56 ⁇ m, 58 ⁇ m, 60 ⁇ m, 65 ⁇ m, 70 ⁇ m, 75 ⁇ m, 80 ⁇ m, 85 ⁇ m, 90 ⁇ m, 100 ⁇ m, 110 ⁇ m, 120 ⁇ m, 130 ⁇ m, 140 ⁇ m, 150 ⁇ m, 160 ⁇ m, or any combination of the above values.
  • the average size of the pit can be 20 ⁇ m-120 ⁇ m, 20 ⁇ m-100 ⁇ m, 20 ⁇ m-90 ⁇ m, 20 ⁇ m-80 ⁇ m, 20 ⁇ m-70 ⁇ m, 20 ⁇ m-60 ⁇ m, 20 ⁇ m-50 ⁇ m, 20 ⁇ m-45 ⁇ m, 20 ⁇ m-40 ⁇ m, 22 ⁇ m-100 ⁇ m, 22 ⁇ m-90 ⁇ m, 22 ⁇ m-80 ⁇ m, 22 ⁇ m-70 ⁇ m, 22 ⁇ m-60 ⁇ m, 22 ⁇ m-50 ⁇ m, 22 ⁇ m-45 ⁇ m, or 22 ⁇ m-40 ⁇ m.
  • the cycle life of the battery cell can be further improved.
  • the number density of pits ranges from 208 to 320 per mm2 , for example, 208, 210 , 215 , 220 , 225, 230 , 235, 240 , 245, 250 , 255 , 260, 265 , 270 , 275 , 280 , 285 , 290 , 295 , 300 , 305 , and 310 per mm2 . 315 pieces/ mm2 , 320 pieces/ mm2 , or any range of the above values.
  • the number density of pits can be 225 to 320 , 250 to 320 , 275 to 320, 280 to 320 , 285 to 320, 290 to 320 , 295 to 320 , or 300 to 320 .
  • the percentage of pits with a maximum lateral dimension of less than 50 ⁇ m can be greater than or equal to 14%.
  • the percentage of pits with a maximum lateral dimension of less than 50 ⁇ m can be greater than or equal to 20%, greater than or equal to 25%, greater than or equal to 30%, greater than or equal to 35%, greater than or equal to 40%, greater than or equal to 45%, greater than or equal to 48%, greater than or equal to 52%, greater than or equal to 56%, or greater than or equal to 60%.
  • the percentage of pits with a maximum lateral dimension greater than 100 ⁇ m can be greater than 0 and less than or equal to 55%.
  • the percentage of pits with a maximum lateral dimension greater than 100 ⁇ m can be greater than 0 and less than or equal to 50%, greater than 0 and less than or equal to 45%, greater than 0 and less than or equal to 40%, greater than 0 and less than or equal to 35%, greater than 0 and less than or equal to 30%, greater than 0 and less than or equal to 25%, greater than 0 and less than or equal to 20%, greater than 0 and less than or equal to 18%, greater than 0 and less than or equal to 15%, greater than 0 and less than or equal to 12%, greater than 0 and less than or equal to 10%, or greater than 0 and less than or equal to 8%.
  • the high proportion of pits with a maximum lateral dimension less than 50 ⁇ m and the low proportion of pits with a maximum lateral dimension greater than 100 ⁇ m indicate that the negative electrode sheet can have more preferential nucleation sites, which can further reduce electrolyte consumption and further improve the cycle life of the battery cell.
  • the number density of pits with a maximum lateral dimension of less than 50 ⁇ m can be from 30 pits/ mm2 to 202 pits/ mm2 , for example, it can be 30 pits/ mm2 , 40 pits/ mm2 , 50 pits / mm2 , 60 pits/ mm2 , 70 pits/ mm2 , 80 pits/ mm2 , 90 pits/ mm2 , 100 pits/ mm2 , 110 pits/ mm2 , 120 pits/ mm2 , 130 pits/ mm2 , 140 pits/ mm2 , 150 pits/mm2, 160 pits/ mm2 , 170 pits/ mm2 , 180 pits/ mm2 , 190 pits/ mm2 , 202 pits/ mm2 , or any range of the above values.
  • the number density of pits with a maximum lateral dimension of less than 50 ⁇ m can be 50 to 202 per mm2 , 80 to 202 per mm2 , 100 to 202 per mm2 , 110 to 202 per mm2, 120 to 202 per mm2 , 130 to 202 per mm2, 140 to 202 per mm2 , 150 to 202 per mm2 , 160 to 202 per mm2 , 170 to 202 per mm2 , or 180 to 202 per mm2 .
  • the number density of pits with a maximum lateral dimension between 50 ⁇ m and 100 ⁇ m can be between 60 pits/ mm2 and 105 pits/ mm2 , for example, 60 pits/ mm2 , 62 pits/ mm2 , 64 pits/ mm2 , 66 pits/ mm2 , 68 pits/ mm2 , 70 pits/ mm2 , 72 pits/mm2, 74 pits/ mm2 , 76 pits/ mm2 , 78 pits/ mm2 , 80 pits/ mm2 , 82 pits/ mm2 , 84 pits/ mm2 , 86 pits/ mm2 , 88 pits/ mm2 , 90 pits/ mm2 , 92 pits/ mm2 , 94 pits/ mm2 , 96 pits/ mm2 , 98 pits/ mm2 , 100 pits/ mm2 , or 103
  • the number density of pits with a maximum lateral dimension between 50 ⁇ m and 100 ⁇ m can be 70 to 105 pits/ mm2 , 75 to 105 pits/ mm2 , 80 to 105 pits/mm2, 85 to 105 pits/ mm2 , 88 to 105 pits/ mm2 , 70 to 103 pits/ mm2 , 75 to 103 pits/mm2 , 80 to 103 pits/mm2, 85 to 103 pits/ mm2 , or 88 to 103 pits / mm2 .
  • the number density of pits with a maximum lateral dimension greater than 100 ⁇ m can be from 14 pits/ mm2 to 114 pits/ mm2 , for example, 14 pits/ mm2 , 16 pits/ mm2 , 18 pits/ mm2 , 20 pits/ mm2 , 22 pits/ mm2 , 24 pits/ mm2 , 26 pits/ mm2 , 28 pits/ mm2 , 30 pits/ mm2 , 32 pits/ mm2 , 34 pits/ mm2 , 36 pits/ mm2 , 38 pits/ mm2 , 40 pits/ mm2 , 45 pits/ mm2 , 50 pits/ mm2 , 55 pits/ mm2 , 60 pits/mm2, 65 pits/ mm2 , 70 pits/ mm2 , 75 pits/ mm2 , 80 pits/ mm2 , or 90 pits/ mm2 .
  • the number density of pits with a maximum lateral dimension greater than 100 ⁇ m can be 14 to 100, 14 to 80 , 14 to 70, 14 to 60, 14 to 50 , 14 to 45, 14 to 40 , or 14 to 35 .
  • the number density of pits of different sizes can further reduce electrolyte consumption and further improve the cycle life of individual battery cells.
  • the depth of the pit can be more than 10% of the thickness of the lithium metal layer and less than the thickness of the lithium metal layer, for example, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, or any range of the above values.
  • the depth of the pit can be 10%-95%, 20%-95%, 30%-95%, 40%-95%, 50%-95%, 10%-90%, 20%-90%, 30%-90%, 40%-90%, or 50%-90% of the thickness of the lithium metal layer.
  • the sum of the areas of the plurality of pits can be 20%-50% of the area of the lithium metal layer, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, or any range of the above values.
  • the sum of the areas of multiple pits can be 24%-42% of the area of the lithium metal layer.
  • the number density of pits can be obtained by observation using a scanning electron microscope (SEM). During testing, the negative electrode sheet is disassembled from the battery cell, and the number density of pits on its surface is calculated. The maximum lateral dimension of each observed pit is taken as the size of that pit. During testing, the selected observation area should contain at least 100 complete pits. For accuracy, more than three observation areas can be selected, and the average value is taken.
  • SEM scanning electron microscope
  • the negative current collector may be a metal foil.
  • metal foils include copper foil, copper alloy foil, nickel foil, nickel alloy foil, etc.
  • the positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer including a positive electrode active material.
  • the positive electrode active material may include, but is not limited to, one or more of lithium phosphates, lithium transition metal oxides, and their respective modified compounds.
  • Lithium phosphates may include, but are not limited to, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.
  • Lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.
  • the modified compounds of the above-mentioned positive electrode active materials may be for doping modification and/or surface coating modification of the positive electrode active material.
  • the positive electrode film layer may further include a positive electrode conductive agent.
  • the positive electrode conductive agent may include, but is not limited to, one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive electrode film layer may further include a positive electrode binder.
  • the positive electrode binder may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PVDF-tetrafluoroethylene-propylene terpolymer PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer
  • tetrafluoroethylene-hexafluoropropylene copolymer tetrafluoroethylene-hexafluoropropy
  • the positive current collector may be a metal foil or a composite current collector.
  • An example of a metal foil is aluminum foil.
  • the composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate.
  • the metal material may include, but is not limited to, one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys.
  • the polymeric material substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.
  • the positive electrode film can be formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing.
  • the positive electrode slurry is typically formed by dispersing positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and stirring until homogeneous.
  • the solvent can be N-methylpyrrolidone (NMP), but is not limited to this.
  • a separator can be disposed between the positive and negative electrode plates, primarily serving to prevent internal short circuits. This application does not impose any particular limitation on the type of separator; any known porous membrane with good chemical and mechanical stability can be selected.
  • the separator material may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide.
  • the separator can be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.
  • the electrolyte comprises a lithium salt and an organic solvent.
  • the lithium salt may include, but is not limited to, lithium bis(trifluoromethyl)sulfonylimide (LiFSI), lithium hexafluorophosphate ( LiPF6 ), lithium tetrafluoroborate ( LiBF4 ), lithium hexafluoroarsenate ( LiAsF6 ), lithium bis(trifluoromethyl)sulfonylimide (LiTFSI), lithium trifluoromethanesulfonate (LiOTF), lithium dioxalateborate (LiBOB), lithium difluorooxalateborate (LiDFOB), lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.
  • LiFSI lithium bis(trifluoromethyl)sulfonylimide
  • LiPF6 lithium hexafluorophosphate
  • LiBF4 lithium tetrafluoroborate
  • the lithium salt includes lithium bisfluorosulfonylimide (LiFSI).
  • LiFSI lithium bisfluorosulfonylimide
  • This lithium salt can decompose on the negative electrode surface to form an inorganic fluorine-rich SEI film component, which is beneficial to the long cycle life of the battery cell; at the same time, this lithium salt also has good oxidation stability, which can support the cycling of the battery cell under high voltage.
  • the organic solvent may include ether solvents.
  • Ether solvents may include one or more of chain ether solvents and cyclic ether solvents.
  • Chain ether solvents may include, but are not limited to, one or more of diethyl ether, dipropyl ether, ethylpropyl ether, methyl butyl ether, dibutyl ether, ethyl butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, propylene glycol diethyl ether, butanediol dimethyl ether, butanediol diethyl ether, and butanediol dieth
  • Cyclic ether solvents may include, but are not limited to, one or more of tetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxopentane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.
  • the electrolyte may further include a diluent.
  • the diluent may include, but is not limited to, benzene, fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, trifluoromethoxybenzene, decafluoropentane, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-dimethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(difluoromethoxy)ethane, 1,2-bis(trifluoromethoxy)ethane, 1,2-diethoxy-1,1,2,2-tetrafluoroethane, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl
  • the concentration of the electrolyte can be 1 mol/L to 6 mol/L, for example, it can be 1 mol/L, 1.2 mol/L, 1.4 mol/L, 1.6 mol/L, 1.8 mol/L, 2 mol/L, 2.2 mol/L, 2.4 mol/L, 2.6 mol/L, 2.8 mol/L, 3 mol/L, 3.2 mol/L, 3.4 mol/L, 3.6 mol/L, 3.8 mol/L, 4 mol/L, 4.2 mol/L, 4.4 mol/L, 4.6 mol/L, 4.8 mol/L, 5 mol/L, 5.2 mol/L, 5.4 mol/L, 5.6 mol/L, 5.8 mol/L, 6 mol/L, or any range of the above values.
  • the concentration of the electrolyte can be 2 mol/L to 5 mol/L.
  • This application also provides a method for preparing a battery cell, which can prepare the battery cell provided in this application.
  • the method for preparing a battery cell includes the following steps: assembling a lithium-poor positive electrode sheet and a negative electrode sheet to obtain a battery cell, wherein the negative electrode sheet includes a negative current collector and a lithium metal layer disposed on at least one surface of the negative current collector; subjecting the battery cell to pulse discharge to obtain a battery cell, wherein multiple pits are formed on the surface of the lithium metal layer after pulse discharge, the average size of the pits is 20 ⁇ m-160 ⁇ m, and the number density of pits is 208 pits/ mm2 to 320 pits/ mm2 .
  • pulse discharge can cause partial stripping of lithium metal from the surface of the negative electrode sheet. This allows multiple pits to form in situ on the lithium metal layer surface of the negative electrode sheet, and also releases some of the capacity lithium from the negative electrode into the lithium-poor positive electrode.
  • Using lithium-poor positive electrode sheets to assemble the battery cell also reduces damage to the positive electrode active material caused by the initial pulse discharge. Furthermore, the battery cell preparation method provided in this application is simple to operate and has low production costs.
  • the starting current of the pulse discharge may be less than or equal to 3C.
  • the starting current of the pulse discharge may be less than or equal to 2C, less than or equal to 1.5C, or less than or equal to 1C.
  • Using a small starting current for pulse discharge can result in a smaller pit size and a higher pit density on the negative electrode, thereby further improving the cycle life of the battery cell.
  • the cutoff current of the pulse discharge can be 0.05C-0.50C.
  • the cutoff current of the pulse discharge can be 0.05C-0.40C, 0.05C-0.30C, 0.05C-0.20C, or 0.05C-0.10C.
  • the size of the pits can be reduced and the number density of pits can be increased without damaging the positive electrode active material, thereby further improving the cycle life of the battery cell.
  • the lithium-deficient positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector, the positive electrode film layer comprising a lithium-deficient phase positive electrode active material.
  • the lithium-deficient phase positive electrode active material transforms into a conventional positive electrode active material, i.e., the positive electrode active material in the positive electrode described above in this application.
  • the lithium-depleted phase cathode active material may include one or more of lithium-depleted phase phosphates, lithium-depleted phase transition metal oxides, and their respective modified compounds.
  • Lithium-depleted phase phosphates may include, but are not limited to, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and their respective modified compounds.
  • Lithium-depleted phase transition metal oxides may include, but are not limited to, lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their respective modified compounds.
  • the modified compounds of the above-mentioned lithium-depleted phase cathode active materials may be used for doping modification and/or surface coating modification of the lithium-depleted phase cathode active materials.
  • the lithium-lean phase cathode active material may include one or more of Li ⁇ sub>a ⁇ /sub>FePO ⁇ sub> 4 ⁇ /sub>, Li ⁇ sub> b ⁇ /sub> Ni ⁇ sub> 1-xy ⁇ /sub>Co ⁇ sub>x ⁇ /sub> Mn ⁇ sub>y ⁇ /sub> M ⁇ sub>z ⁇ /sub>O ⁇ sub> c ⁇ /sub>A ⁇ sub> d ⁇ /sub>.
  • M may include one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A may include one or more of N, F, S, and Cl.
  • a may be less than 1, and can be selected as 0.2-0.9.
  • b may be less than 1, and can be selected as 0.2-0.9.
  • x may be greater than 0 and less than 1.
  • y may be greater than 0 and less than 1.
  • z may be greater than 0 and less than 1.
  • c may be 1-2.
  • d may be greater than or equal to 0 and less than or equal to 1.
  • the cutoff voltage of the pulse discharge can be greater than or equal to the lower cutoff voltage of the lithium-poor phase cathode active material.
  • the lower cutoff voltage of the positive electrode active material is a voltage known in the art.
  • the lower cutoff voltage can be 2.8V
  • the cutoff voltage of pulse discharge can be greater than or equal to 2.8V, for example, it can be 2.8V.
  • the lower cutoff voltage can be 2.5V, and the cutoff voltage of pulse discharge can be greater than or equal to 2.5V, for example, it can be 2.5V.
  • This application also provides an electrical device, which includes the battery provided in this application embodiment.
  • the battery can be used as the power source of the electrical device or as the energy storage unit of the electrical device.
  • the electrical device can be, but is not limited to, mobile devices (such as mobile phones, tablets, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • Electrical devices can choose the type of battery according to their usage needs, such as individual battery cells, battery modules, or battery packs.
  • FIG. 6 is a schematic diagram of an example electrical device.
  • This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or battery module can be used.
  • Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.
  • lithium-lean positive electrode sheet Positive electrode active material Li 0.5 Ni 0.8 Co 0.1 Mn 0.1 O 2 , positive electrode conductive agent acetylene black, and positive electrode binder polyvinylidene fluoride (PVDF) were mixed at a mass ratio of 98:1:1 and added to the solvent N-methylpyrrolidone (NMP). The mixture was stirred until the system was homogeneous to obtain a positive electrode slurry. The positive electrode slurry was uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. The slurry was then cut into 40mm ⁇ 50mm rectangles to serve as lithium-lean positive electrode sheets for later use. The positive electrode surface capacity was 3.5 mAh/ cm2 .
  • Preparation of negative electrode sheet A 50 ⁇ m thick lithium foil is rolled onto a 12 ⁇ m thick copper foil, and then cut into a 41mm ⁇ 51mm rectangle as a negative electrode sheet for later use.
  • Preparation of the separator membrane Cut a polyethylene porous membrane into rectangles of 45mm ⁇ 55mm as the separator membrane for later use.
  • LiFSI lithium bis(fluorosulfonyl)imide
  • a pre-cut lithium-poor positive electrode sheet is matched with two pre-cut negative electrode sheets, separated by the aforementioned separator, and wrapped in an aluminum-plastic film bag to form a battery cell to be injected with electrolyte; 0.3g of electrolyte is injected into the prepared battery cell, and then the aluminum-plastic film bag is vacuum heat-sealed and left to stand at 25°C for more than 6 hours.
  • the capacity of the battery cell is 140mAh; then the battery cell is subjected to pulse discharge, with a pulse discharge initiation current of 1C (140mA), a cutoff current of 0.05C (7mA), and a cutoff voltage of 2.8V. After the discharge, the battery cell is obtained and cycle performance testing is performed.
  • the cycle performance test method is as follows: Take the prepared battery cell, set the ambient temperature to 25°C, and charge it with a constant current of 0.2C (28mA) until the cutoff voltage of 4.3V is reached. Then, continue charging with a constant voltage of 4.3V until the current decays to 0.1C (14mA). Then, discharge it with a constant current of 1C (140mA) to 2.8V to obtain the first discharge capacity. Repeat the above charge-discharge cycle and record the discharge capacity after each cycle. When the discharge capacity decays to 80% of the first discharge capacity, the battery cell is considered to have reached the end of its lifespan, and the number of cycles experienced by the battery cell at this time is recorded.
  • test methods for the consumption of organic solvents and lithium salts are as follows.
  • the battery cells were subjected to 100 charge-discharge cycles as described above. After the test, the surface of the battery cells was wiped clean and the total mass of the battery cells was measured (m3). The battery cells were disassembled, and the electrolyte was tested to determine the mass percentages of organic solvent and lithium salt. A separator bag was fabricated and its mass (m4) was measured. All the disassembled components were placed into the separator bag, and the separator bag was soaked in diethylene glycol dimethyl ether (DGE) solvent to remove residual electrolyte. The separator bag, along with all the internal components, was then heated and dried. After the drying process, the total mass (m5) of the separator bag and all the internal components was measured. m3 + m4 - m5 represents the remaining amount of electrolyte. The remaining mass of organic solvent (m6) and the remaining mass of lithium salt (m7) were calculated based on the mass percentages of organic solvent and lithium salt.
  • DGE diethylene glycol dimethyl ether
  • Organic solvent consumption m1 - m6.
  • Lithium salt consumption m2 - m7.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 1.5C (210mA), the cutoff current is 0.05C (7mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 2C (280mA), the cutoff current is 0.05C (7mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 3C (420mA), the cutoff current is 0.05C (7mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 0.5C (70mA), the cutoff current is 0.05C (7mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge starting current is 1C (140mA), the cutoff current is 0.50C (70mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 1C (140mA), the cutoff current is 0.25C (35mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that pulse discharge is not performed.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 4C (560mA), the cutoff current is 0.01C (1.4mA), and the cutoff voltage is 2.8V.
  • the preparation method of the battery cell is the same as that in Example 1, except that the pulse discharge initiation current is 4C (560mA), the cutoff current is 1C (140mA), and the cutoff voltage is 2.8V.
  • a pre-cut lithium-poor positive electrode sheet is matched with two pre-cut negative electrode sheets, separated by the aforementioned separator, and wrapped in an aluminum-plastic film bag to form a battery cell to be injected with electrolyte; 0.3g of electrolyte is injected into the prepared battery cell, and then the aluminum-plastic film bag is vacuum heat-sealed and left to stand at 25°C for more than 6 hours.
  • the capacity of the battery cell is 140mAh; then the battery cell is discharged at a constant current of 1C (140mA) with a cutoff voltage of 2.8V. After the discharge, the battery cell is obtained and cycle performance testing is performed.
  • the pits on the surface of the lithium metal layer of the negative electrode sheet have an average size of 20 ⁇ m-160 ⁇ m and a number density of 208 pits/ mm2 to 320 pits/ mm2 , which can give the battery cell a longer cycle life.
  • test results from Examples 1 to 7 also show that further adjusting the pulse discharge initiation current and/or cutoff current can give the battery cells a longer cycle life.

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Abstract

本申请公开了一种电池单体及其制备方法、电池和用电装置，电池单体包括负极极片，负极极片包括负极集流体以及设置在负极集流体至少一个表面上的锂金属层，锂金属层表面具有多个凹坑，凹坑的平均尺寸为20μm-160μm，凹坑的数量密度为208个/mm2至320个/mm2。电池单体具有长循环寿命。

Description

电池单体及其制备方法、电池和用电装置
相关申请的交叉引用
本申请要求享有于2024年07月03日提交的名称为“电池单体及其制备方法、电池和用电装置”的中国专利申请202410888152.3的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及一种电池单体及其制备方法、电池和用电装置。
背景技术
锂金属电池单体相较锂离子电池单体具有更高的能量密度，然而，由于锂金属电池单体使用了活性极高的金属锂，同时由于锂金属剥离及沉积过程中的体积膨胀、不均匀沉积等问题，导致锂金属电池单体的循环寿命较差。
发明内容
本申请提供一种电池单体及其制备方法、电池和用电装置，电池单体具有长循环寿命。
第一方面，本申请提供一种电池单体，所述电池单体包括负极极片，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面上的锂金属层，所述锂金属层表面具有多个凹坑，所述凹坑的平均尺寸为20μm-160μm，所述凹坑的数量密度为208个/mm2至320个/mm2。
负极极片锂金属层表面凹坑的平均尺寸为20μm-160μm，凹坑的数量密度为208个/mm2至320个/mm2，这些凹坑暴露了新鲜的锂金属，由此可以作为后续锂金属沉积的优先成核位点。在之后的充电过程中，锂金属会优先在这些成核位点进行定向沉积，并可以诱导后续锂金属进行均匀且致密地沉积，由此可以减少死锂、锂枝晶等的生成，还可以形成比表面积较小的锂金属沉积形貌，减少电解液的消耗，还可以降低阻抗和极化。因此，本申请实施例提供的电池单体能具有长循环寿命。
在一些实施例中，所述凹坑的平均尺寸为20μm-45μm。凹坑的平均尺寸在上述范围内，可以进一步提升电池单体的循环寿命。
在一些实施例中，所述凹坑的数量密度为280个/mm2至320个/mm2。凹坑的数量密度在上述范围内，可以进一步提升电池单体的循环寿命。
在一些实施例中，基于所有凹坑的数量计，最大横向尺寸小于50μm的凹坑的数量占比为大于等于14％，最大横向尺寸大于100μm的凹坑的数量占比为大于0且小于等于55％。可选地，基于所有凹坑的数量计，最大横向尺寸小于50μm的凹坑的数量占比为大于等于48％，最大横向尺寸大于100μm的凹坑的数量占比为大于0且小于等于18％。最大横向尺寸小于50μm的凹坑的数量占比高、最大横向尺寸大于100μm的凹坑的数量占比少，负极极片可具有较多的优先成核位点，由此可以进一步减少电解液的消耗，还可以进一步提升电池单体的循环寿命。
在一些实施例中，最大横向尺寸小于50μm的凹坑的数量密度为30个/mm2至202个/mm2，最大横向尺寸在50μm至100μm之间的凹坑的数量密度为60个/mm2至105个/mm2，最大横向尺寸大于100μm的凹坑的数量密度为14个/mm2至114个/mm2。可选地，最大横向尺寸小于50μm的凹坑的数量密度为130个/mm2至202个/mm2，最大横向尺寸在50μm至100μm之间的凹坑的数量密度为88个/mm2至105个/mm2，最大横向尺寸大于100μm的凹坑的数量密度为14个/mm2至50个/mm2。不同尺寸的凹坑的数量密度在上述范围内，可以进一步减少电解液的消耗，还可以进一步提升电池单体的循环寿命。
在一些实施例中，所述凹坑的深度为所述锂金属层的厚度的10％以上且小于所述锂金属层的厚度。
在一些实施例中，所述多个凹坑的面积之和为所述锂金属层的面积的20％-50％。
在一些实施例中，所述电池单体包括正极极片，所述正极极片包括正极集流体以及设置在所述正极集流体至少一个表面上的正极膜层，所述正极膜层包括正极活性材料，所述正极活性材料包括含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物中的一种或多种。
在一些实施例中，所述电池单体包括电解液，所述电解液的浓度为1mol/L-6mol/L。
第二方面，本申请提供一种电池单体的制备方法，包括如下步骤：将贫锂正极极片与负极极片组装得到电池单体，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面上的锂金属层；将所述电池单体进行脉冲放电，得到电池单体，脉冲放电后所述锂金属层表面形成多个凹坑，所述凹坑的平均尺寸为20μm-160μm，所述凹坑的数量密度为208个/mm2至320个/mm2。
将贫锂正极极片与负极极片组装成电池单体后进行脉冲放电，可以使负极极片表面部分锂金属发生剥离，由此可以在负极极片锂金属层表面原位形成多个凹坑，还可以将负极的部分容量锂释放到贫锂正极中。采用贫锂正极极片组装电池单体，还可以减少初始脉冲放电对正极活性材料的损害。另外，本申请实施例提供的电池单体的制备方法操作简单、生产成本低。
在一些实施例中，所述脉冲放电的起始电流小于等于3C，所述脉冲放电的截止电流为0.05C-0.50C。可选地，所述脉冲放电的起始电流小于等于1C，所述脉冲放电的截止电流为0.05C-0.10C。采用小起始电流进行脉冲放电，可以使负极极片具有较小的凹坑尺寸和较高的凹坑数量密度，从而可以进一步提升电池单体的循环寿命。脉冲放电的截止电流在上述范围内，可以在不损害正极活性材料的同时降低凹坑尺寸、增加凹坑的数量密度，从而可以进一步提升电池单体的循环寿命。
在一些实施例中，所述贫锂正极极片包括正极集流体以及设置在所述正极集流体至少一个表面上的正极膜层，所述正极膜层包括贫锂相正极活性材料，所述贫锂相正极活性材料包括贫锂相磷酸盐、贫锂相过渡金属氧化物及其各自的改性化合物中的一种或多种。
第三方面，本申请提供一种电池，包括本申请第一方面的电池单体或通过本申请第二方面的制备方法制备的电池单体。
第四方面，本申请提供一种用电装置，包括本申请第三方面的电池。
本申请的用电装置包括本申请提供的电池，因而至少具有与所述电池相同的优势。
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。显而易见地，下面所描述的附图仅仅是本申请的一些实施方式，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，还可以根据附图获得其他的附图。
图1示出本申请一些实施例提供的电池单体的示意图。
图2示出本申请一些实施例提供的电池模块的示意图。
图3示出本申请一些实施例提供的电池包的示意图。
图4是图3所示的电池包的分解示意图。
图5示出本申请一些实施例提供的负极极片的扫描电子显微镜(SEM)图。
图6示出本申请一些实施例提供的用电装置的示意图。
在附图中，附图未必按照实际的比例绘制。
附图标记说明如下：1、电池包；2、上箱体；3、下箱体；4、电池模块；5、电池单体。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的电池单体及其制备方法、电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案，并且这样的技术方案应被认为包含在本申请的公开内容中。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，在本申请中，术语“第一”、“第二”等是用于区别不同对象，而不是用于描述特定顺序或主次关系。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
在本申请实施例的描述中，如果没有特别的说明，第一特征在第二特征“上”或“下”可以是第一和第二特征直接接触，或第一和第二特征通过中间媒介间接接触。而且，第一特征在第二特征“之上”、“上方”和“上面”可是第一特征在第二特征正上方或斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”可以是第一特征在第二特征正下方或斜下方，或仅仅表示第一特征水平高度小于第二特征。
除非另有说明，本申请中使用的术语具有本领域技术人员通常所理解的公知含义。
除非另有说明，本申请中提到的各参数的数值可以用本领域常用的各种测试方法进行测定，例如，可以按照本申请的实施例中给出的测试方法进行测定。除非另有说明，各参数的测试温度均为25℃。
本申请的实施例中所提到的电池可以为包括一个或多个电池单体以提供更高的电压和容量的单一的物理模块。例如，本申请中所提到的电池可以包括电池单体、电池模块或电池包等。
电池单体是组成电池的最小单元，其独自能够实现充放电的功能。电池单体可呈圆柱体、长方体或其它形状等，本申请实施例对此并不限定。如图1是作为一个示例的长方体结构的电池单体5。
电池单体有多个时，多个电池单体通过汇流部件串联、并联或混联。在一些实施例中，电池可以为电池模块；电池单体有多个时，多个电池单体排列并固定形成一个电池模块。在一些实施例中，电池可以为电池包，电池包包括箱体和电池单体，电池单体或电池模块容纳于箱体中。在一些实施例中，箱体可以作为车辆的底盘结构的一部分。例如，箱体的部分可以成为车辆的底板的至少一部分，或者，箱体的部分可以成为车辆的横梁和纵梁的至少一部分。
在一些实施例中，电池可以为储能装置。储能装置包括储能集装箱、储能电柜等。
在一些实施例中，电池单体可以组装成电池模块，电池模块所含电池单体的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。如图2所示，在电池模块4中，多个电池单体5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体5进行固定。
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。如图3和图4所示，在电池包1中可以包括箱体和设置于箱体中的多个电池模块4。箱体包括上箱体2和下箱体3，上箱体2用于盖设下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于箱体中。
本申请的实施例提供的电池单体包括锂金属电池单体。电池单体包括电极组件和电解液，电池单体包括正极极片、负极极片和隔离膜。电极组件可以是卷绕式结构，也可以是叠片式结构，本申请实施例对此并不限定。电池单体还包括外包装，外包装可用于封装电极组件和电解液。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。软包的材质可以是铝塑膜或塑料，如聚丙烯、聚对苯二甲酸丁二醇酯(PBT)和聚丁二酸丁二醇酯(PBS)中的一种或多种。
锂金属负极的腐蚀是导致锂金属电池单体循环失效的重要原因之一。随着电池单体循环充放电的进行，锂金属负极表面会不断进行锂金属的沉积和剥离，由此形成了粗糙的负极表面，容易带来死锂、电解液消耗、极化过大等问题，进而导致电池单体循环寿命较差。
基于此，本申请实施例从负极极片出发，提供了一种具有长循环寿命的电池单体。
本申请的实施例提供的电池单体包括负极极片，负极极片包括负极集流体以及设置在负极集流体至少一个表面上的锂金属层，锂金属层表面具有多个凹坑。凹坑的平均尺寸为20μm-160μm，凹坑的数量密度为208个/mm2至320个/mm2。
如图5所示，锂金属层表面具有多个凹坑。
负极极片锂金属层表面凹坑的平均尺寸为20μm-160μm，凹坑的数量密度为208个/mm2至320个/mm2，这些凹坑暴露了新鲜的锂金属，由此可以作为后续锂金属沉积的优先成核位点。在之后的充电过程中，锂金属会优先在这些成核位点进行定向沉积，并可以诱导后续锂金属进行均匀且致密地沉积，由此可以减少死锂、锂枝晶等的生成，还可以形成比表面积较小的锂金属沉积形貌，减少电解液的消耗，还可以降低阻抗和极化。因此，本申请实施例提供的电池单体能具有长循环寿命。
凹坑的平均尺寸为20μm-160μm，例如可以为20μm、21μm、22μm、23μm、24μm、25μm、26μm、27μm、28μm、29μm、30μm、32μm、34μm、36μm、38μm、40μm、42μm、44μm、46μm、48μm、50μm、52μm、54μm、56μm、58μm、60μm、65μm、70μm、75μm、80μm、85μm、90μm、100μm、110μm、120μm、130μm、140μm、150μm、160μm、或上述任意数值组成的范围。
可选地，凹坑的平均尺寸可以为20μm-120μm，20μm-100μm，20μm-90μm，20μm-80μm，20μm-70μm，20μm-60μm，20μm-50μm，20μm-45μm，20μm-40μm，22μm-100μm，22μm-90μm，22μm-80μm，22μm-70μm，22μm-60μm，22μm-50μm，22μm-45μm，22μm-40μm。
凹坑的平均尺寸在上述范围内，可以进一步提升电池单体的循环寿命。
凹坑的数量密度为208个/mm2至320个/mm2，例如可以为208个/mm2、210个/mm2、215个/mm2、220个/mm2、225个/mm2、230个/mm2、235个/mm2、240个/mm2、245个/mm2、250个/mm2、255个/mm2、260个/mm2、265个/mm2、270个/mm2、275个/mm2、280个/mm2、285个/mm2、290个/mm2、295个/mm2、300个/mm2、305个/mm2、310个/mm2、315个/mm2、320个/mm2、或上述任意数值组成的范围。
可选地，凹坑的数量密度可以为225个/mm2至320个/mm2，250个/mm2至320个/mm2，275个/mm2至320个/mm2，280个/mm2至320个/mm2，285个/mm2至320个/mm2，290个/mm2至320个/mm2，295个/mm2至320个/mm2，300个/mm2至320个/mm2。
凹坑的数量密度在上述范围内，可以进一步提升电池单体的循环寿命。
在一些实施例中，基于所有凹坑的数量计，最大横向尺寸小于50μm的凹坑的数量占比可以为大于等于14％。
可选地，最大横向尺寸小于50μm的凹坑的数量占比可以为大于等于20％、大于等于25％、大于等于30％、大于等于35％、大于等于40％、大于等于45％、大于等于48％、大于等于52％、大于等于56％、大于等于60％。
在一些实施例中，基于所有凹坑的数量计，最大横向尺寸大于100μm的凹坑的数量占比可以为大于0且小于等于55％。
可选地，最大横向尺寸大于100μm的凹坑的数量占比可以为大于0且小于等于50％、大于0且小于等于45％、大于0且小于等于40％、大于0且小于等于35％、大于0且小于等于30％、大于0且小于等于25％、大于0且小于等于20％、大于0且小于等于18％、大于0且小于等于15％、大于0且小于等于12％、大于0且小于等于10％、大于0且小于等8％。
最大横向尺寸小于50μm的凹坑的数量占比高、最大横向尺寸大于100μm的凹坑的数量占比少，负极极片可具有较多的优先成核位点，由此可以进一步减少电解液的消耗，还可以进一步提升电池单体的循环寿命。
在一些实施例中，最大横向尺寸小于50μm的凹坑的数量密度可以为30个/mm2至202个/mm2，例如可以为30个/mm2、40个/mm2、50个/mm2、60个/mm2、70个/mm2、80个/mm2、90个/mm2、100个/mm2、110个/mm2、120个/mm2、130个/mm2、140个/mm2、150个/mm2、160个/mm2、170个/mm2、180个/mm2、190个/mm2、202个/mm2、或上述任意数值组成的范围。
可选地，最大横向尺寸小于50μm的凹坑的数量密度可以为50个/mm2至202个/mm2，80个/mm2至202个/mm2，100个/mm2至202个/mm2，110个/mm2至202个/mm2，120个/mm2至202个/mm2，130个/mm2至202个/mm2，140个/mm2至202个/mm2，150个/mm2至202个/mm2，160个/mm2至202个/mm2，170个/mm2至202个/mm2，180个/mm2至202个/mm2。
在一些实施例中，最大横向尺寸在50μm至100μm之间的凹坑的数量密度可以为60个/mm2至105个/mm2，例如可以为60个/mm2、62个/mm2、64个/mm2、66个/mm2、68个/mm2、70个/mm2、72个/mm2、74个/mm2、76个/mm2、78个/mm2、80个/mm2、82个/mm2、84个/mm2、86个/mm2、88个/mm2、90个/mm2、92个/mm2、94个/mm2、96个/mm2、98个/mm2、100个/mm2、103个/mm2、105个/mm2、或上述任意数值组成的范围。
可选地，最大横向尺寸在50μm至100μm之间的凹坑的数量密度可以为70个/mm2至105个/mm2，75个/mm2至105个/mm2，80个/mm2至105个/mm2，85个/mm2至105个/mm2，88个/mm2至105个/mm2，70个/mm2至103个/mm2，75个/mm2至103个/mm2，80个/mm2至103个/mm2，85个/mm2至103个/mm2，88个/mm2至103个/mm2。
在一些实施例中，最大横向尺寸大于100μm的凹坑的数量密度可以为14个/mm2至114个/mm2，例如可以为14个/mm2、16个/mm2、18个/mm2、20个/mm2、22个/mm2、24个/mm2、26个/mm2、28个/mm2、30个/mm2、32个/mm2、34个/mm2、36个/mm2、38个/mm2、40个/mm2、45个/mm2、50个/mm2、55个/mm2、60个/mm2、65个/mm2、70个/mm2、75个/mm2、80个/mm2、90个/mm2、100个/mm2、114个/mm2、或上述任意数值组成的范围。
可选地，最大横向尺寸大于100μm的凹坑的数量密度可以为14个/mm2至100个/mm2，14个/mm2至80个/mm2，14个/mm2至70个/mm2，14个/mm2至60个/mm2，14个/mm2至50个/mm2，14个/mm2至45个/mm2，14个/mm2至40个/mm2，14个/mm2至35个/mm2。
不同尺寸的凹坑的数量密度在上述范围内，可以进一步减少电解液的消耗，还可以进一步提升电池单体的循环寿命。
在一些实施例中，凹坑的深度可以为锂金属层的厚度的10％以上且小于锂金属层的厚度，例如可以为30％、35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％、98％、或上述任意数值组成的范围。
可选地，凹坑的深度可以为锂金属层的厚度的10％-95％，20％-95％，30％-95％，40％-95％，50％-95％，10％-90％，20％-90％，30％-90％，40％-90％，50％-90％。
在一些实施例中，多个凹坑的面积之和可以为锂金属层的面积的20％-50％，例如可以为20％、22％、24％、26％、28％、30％、32％、34％、36％、38％、40％、42％、44％、46％、48％、50％、或上述任意数值组成的范围。
可选地，多个凹坑的面积之和可以为锂金属层的面积的24％-42％。
凹坑的数量密度可以通过扫描电子显微镜(SEM)观察获得。测试时，可从电池单体中拆解出负极极片，然后计算负极极片表面凹坑的数量密度。以观察的各凹坑的最大横向尺寸作为各凹坑的尺寸。测试时，所选观察区域视野内至少具有100个完整的凹坑。为了准确度，可以选择3个以上观察区域，然后取平均值。
在一些实施例中，负极集流体可以采用金属箔片。可选地，作为金属箔片的示例，可采用铜箔、铜合金箔、镍箔、镍合金箔等。
在一些实施例中，正极极片包括正极集流体以及设置在正极集流体至少一个表面上的正极膜层，正极膜层包括正极活性材料。可选地，正极活性材料可以包括但不限于含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物中的一种或多种。含锂磷酸盐可以包括但不限于磷酸铁锂、磷酸锰锂、磷酸锰铁锂及其各自的改性化合物中的一种或多种。锂过渡金属氧化物可以包括但不限于锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物及其各自的改性化合物中的一种或多种。上述各正极活性材料的改性化合物可以是对正极活性材料进行掺杂改性和/或表面包覆改性。
在一些实施例中，正极膜层还可以包括正极导电剂。作为示例，正极导电剂可以包括但不限于超导碳、导电石墨、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或多种。
在一些实施例中，正极膜层还可以包括正极粘结剂。作为示例，正极粘结剂可以包括但不限于聚偏二氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏二氟乙烯-四氟乙烯-丙烯三元共聚物、偏二氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物和含氟丙烯酸酯类树脂中的一种或多种。
在一些实施例中，正极集流体可采用金属箔片或复合集流体。作为金属箔片的示例，可采用铝箔。复合集流体可以包括高分子材料基层以及形成于高分子材料基层至少一个表面上的金属材料层。作为示例，金属材料可以包括但不限于铝、铝合金、镍、镍合金、钛、钛合金、银和银合金中的一种或多种。作为示例，高分子材料基层可以包括但不限于聚丙烯、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)和聚乙烯中的一种或多种。
正极膜层可以是将正极浆料涂布于正极集流体上，经干燥、冷压而成的。正极浆料通常是将正极活性材料、正极导电剂、正极粘结剂以及任意的其他组分分散于溶剂中并搅拌均匀而形成的。溶剂可以是N-甲基吡咯烷酮(NMP)，但不限于此。
隔离膜可设置在正极极片和负极极片之间，主要起到防止内部短路的作用。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构膜。在一些实施例中，隔离膜的材质可以包括但不限于玻璃纤维、无纺布、聚乙烯、聚丙烯、聚偏二氟乙烯、聚酰亚胺中的一种或多种。隔离膜可以是单层薄膜，也可以是多层复合薄膜。隔离膜为多层复合薄膜时，各层的材料相同或不同。
电解液包括锂盐和有机溶剂。在一些实施例中，锂盐可以包括但不限于双氟磺酰亚胺锂(LiFSI)、六氟磷酸锂(LiPF6)、四氟硼酸锂(LiBF4)、六氟砷酸锂(LiAsF6)、双(三氟甲基)磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiOTF)、二草酸硼酸锂(LiBOB)、二氟草酸硼酸锂(LiDFOB)、二氟二草酸磷酸锂、四氟草酸磷酸锂中的一种或多种。
可选地，锂盐包括双氟磺酰亚胺锂(LiFSI)。该锂盐可以在负极表面分解形成富含无机氟的SEI膜组分，从而有利于电池单体具有长循环寿命；同时，该锂盐还具有较为良好的氧化稳定性，能够支持电池单体高压下的循环。
在一些实施例中，有机溶剂可以包括醚类溶剂。醚类溶剂可以包括链状醚溶剂、环状醚溶剂中的一种或多种。链状醚溶剂可以包括但不限于二乙醚、二丙醚、乙丙醚、甲丁醚、二丁醚、乙丁醚、乙二醇二甲醚、乙二醇二乙醚、乙二醇甲乙醚、乙二醇二乙醚、乙二醇二丙醚、乙二醇二丁醚、丙二醇二甲醚、丙二醇甲乙醚、丙二醇二乙醚、丁二醇二甲醚、丁二醇甲乙醚、丁二醇二乙醚中的一种或多种。环状醚溶剂可以包括但不限于四氢呋喃、3-甲基四氢呋喃、1,3-二氧五环、四氢吡喃、1,3-二氧六环、1,4-二氧六环中的一种或多种。
在一些实施例中，电解液还可以包括稀释剂。可选地，稀释剂可以包括但不限于苯、氟苯、对二氟苯、间二氟苯、邻二氟苯、三氟甲苯、三氟甲氧基苯、十氟戊烷、1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚、1,2-二甲氧基-1,1,2,2-四氟乙烷、1,2-双(二氟甲氧基)乙烷、1,2-双(三氟甲氧基)乙烷、1,2-二乙氧基-1,1,2,2-四氟乙烷、1,2-双(1,1,2,2-四氟乙氧基)乙烷、双(2,2,2-三氟乙基)醚、双(2,2-二氟乙基)醚、1,1,2,3,3,3-六氟丙基乙基醚、1H,1H,5H-八氟戊基-1,1,2,2-四氟乙基醚、乙基三氟甲基醚、二氟甲基-2,2,3,3,3-五氟丙基醚、七氟丙基-1,2,2,2-四氟乙基醚、二氟甲基2,2,3,3-四氟丙基醚、全氟异丙基甲基醚、1,1,2,2-四氟乙基-2,2,2-三氟乙基醚、乙基-1,1,2,2-四氟乙基醚、乙基-2,2,2-四氟乙基醚、双(1,1,2,2-四氟乙基)醚中的一种或多种。
在一些实施例中，电解液的浓度可以为1mol/L-6mol/L，例如可以为1mol/L、1.2mol/L、1.4mol/L、1.6mol/L、1.8mol/L、2mol/L、2.2mol/L、2.4mol/L、2.6mol/L、2.8mol/L、3mol/L、3.2mol/L、3.4mol/L、3.6mol/L、3.8mol/L、4mol/L、4.2mol/L、4.4mol/L、4.6mol/L、4.8mol/L、5mol/L、5.2mol/L、5.4mol/L、5.6mol/L、5.8mol/L、6mol/L、或上述任意数值组成的范围。
可选地，电解液的浓度可以为2mol/L-5mol/L。
提高锂盐浓度可以诱导锂金属进行更加致密且均匀地沉积。
本申请实施例还提供了一种电池单体的制备方法，其能制备本申请实施例提供的电池单体。
电池单体的制备方法包括如下步骤：将贫锂正极极片与负极极片组装得到电池单体，负极极片包括负极集流体以及设置在负极集流体至少一个表面上的锂金属层；将电池单体进行脉冲放电，得到电池单体，脉冲放电后锂金属层表面形成多个凹坑，凹坑的平均尺寸为20μm-160μm，凹坑的数量密度为208个/mm2至320个/mm2。
将贫锂正极极片与负极极片组装成电池单体后进行脉冲放电，可以使负极极片表面部分锂金属发生剥离，由此可以在负极极片锂金属层表面原位形成多个凹坑，还可以将负极的部分容量锂释放到贫锂正极中。采用贫锂正极极片组装电池单体，还可以减少初始脉冲放电对正极活性材料的损害。另外，本申请实施例提供的电池单体的制备方法操作简单、生产成本低。
在一些实施例中，脉冲放电的起始电流可以小于等于3C。可选地，脉冲放电的起始电流可以小于等于2C，小于等于1.5C，小于等于1C。
采用小起始电流进行脉冲放电，可以使负极极片具有较小的凹坑尺寸和较高的凹坑数量密度，从而可以进一步提升电池单体的循环寿命。
在一些实施例中，脉冲放电的截止电流可以为0.05C-0.50C。可选地，脉冲放电的截止电流可以为0.05C-0.40C，0.05C-0.30C，0.05C-0.20C，0.05C-0.10C。
脉冲放电的截止电流在上述范围内，可以在不损害正极活性材料的同时降低凹坑尺寸、增加凹坑的数量密度，从而可以进一步提升电池单体的循环寿命。
在一些实施例中，贫锂正极极片包括正极集流体以及设置在正极集流体至少一个表面上的正极膜层，正极膜层包括贫锂相正极活性材料。脉冲放电后，贫锂相正极活性材料转变为常规正极活性材料，即本申请上文所述的正极极片中的正极活性材料。
可选地，贫锂相正极活性材料可以包括贫锂相磷酸盐、贫锂相过渡金属氧化物及其各自的改性化合物中的一种或多种。贫锂相磷酸盐可以包括但不限于贫锂相磷酸铁锂、贫锂相磷酸锰锂、贫锂相磷酸锰铁锂及其各自的改性化合物中的一种或多种。贫锂相过渡金属氧化物可以包括但不限于贫锂相锂钴氧化物、贫锂相锂镍氧化物、贫锂相锂锰氧化物、贫锂相锂镍钴氧化物、贫锂相锂锰钴氧化物、贫锂相锂镍锰氧化物、贫锂相锂镍钴锰氧化物、贫锂相锂镍钴铝氧化物及其各自的改性化合物中的一种或多种。上述各贫锂相正极活性材料的改性化合物可以是对贫锂相正极活性材料进行掺杂改性和/或表面包覆改性。
可选地，贫锂相正极活性材料可以包括LiaFePO4、LibNi1-x-yCoxMnyMzOcAd中的一种或多种。M可以包括Mn、Al、Zr、Zn、Cu、Cr、Mg、Fe、V、Ti和B中的一种或多种，A可以包括N、F、S和Cl中的一种或多种。a可以小于1，可选为0.2-0.9。b可以小于1，可选为0.2-0.9。x可以大于0且小于1。y可以大于0且小于1。z可以大于0且小于1。c可以为1-2。d可以大于等于0且小于等于1。
在一些实施例中，脉冲放电的截止电压可以大于等于贫锂相正极活性材料的下限截止电压。
正极活性材料的下限截止电压为本领域已知的电压。
例如，贫锂相正极活性材料包括LibNi1-x-yCoxMnyMzOcAd时，下限截止电压可以为2.8V，脉冲放电的截止电压可以大于等于2.8V，例如可以为2.8V。
例如，贫锂相正极活性材料包括LiaFePO4时，下限截止电压可以为2.5V，脉冲放电的截止电压可以大于等于2.5V，例如可以为2.5V。
本申请实施例还提供一种用电装置，用电装置包括本申请实施例提供的电池。电池可以用作用电装置的电源，也可以用作用电装置的能量存储单元。用电装置可以但不限于是移动设备(例如手机、平板电脑、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。
用电装置可以根据其使用需求来选择电池的类型，例如电池单体、电池模块或电池包。
图6是作为一个示例的用电装置的示意图。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的用电装置可以是手机、平板电脑、笔记本电脑等。该用电装置通常要求轻薄化，可以采用电池单体作为电源。
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
贫锂正极极片的制备：将正极活性材料Li0.5Ni0.8Co0.1Mn0.1O2、正极导电剂乙炔黑、正极粘结剂聚偏二氟乙烯(PVDF)按质量比98:1:1进行混合，加入至溶剂N-甲基吡咯烷酮(NMP)中搅拌至体系呈均一状，获得正极浆料；将正极浆料均匀地涂覆在正极集流体铝箔的两个表面上，室温晾干后转移至烘箱继续干燥，然后裁切成40mm×50mm的长方形，作为贫锂正极极片，备用。正极面容量为3.5mAh/cm2。
负极极片的制备：将厚度为50μm锂箔通过辊压方式覆于厚度为12μm铜箔上，然后裁切成41mm×51mm的长方形作为负极极片，备用。
隔离膜的制备：将聚乙烯多孔膜裁切成45mm×55mm的长方形，作为隔离膜，备用。
电解液的制备：取3.74g双氟磺酰亚胺锂(LiFSI)，加入4.33g乙二醇二甲醚中，充分搅拌，形成浓度为4mol/L的无色透明电解液。
电池单体的制备：取一片裁剪好的贫锂正极极片与两片裁剪好的负极极片进行匹配，中间使用上述隔离膜隔绝，并包裹于铝塑膜袋中组成待注液电池单体；取0.3g电解液注入上述制备好的待注液电池单体中，然后将铝塑膜袋进行真空热压封装，在25℃下静置6小时以上，电池单体的容量为140mAh；然后对电池单体进行脉冲放电，脉冲放电起始电流为1C(140mA)，截止电流为0.05C(7mA)，截止电压为2.8V，结束后得到电池单体，进行循环性能测试。
循环性能测试方法如下：取制备好的电池单体，将环境温度设定为25℃，使用0.2C(28mA)恒流充电达到截止电压4.3V之后，继续改用4.3V恒压充电，直至电流衰减至0.1C(14mA)；然后以1C(140mA)恒流放电至2.8V，得到首圈放电容量。重复上述充放电循环，记录每圈循环后的放电容量。当放电容量衰减到首圈放电容量的80％时，认为电池单体寿命截止，记录此时电池单体经历的循环圈数。
有机溶剂和锂盐的消耗量测试方法如下。
测试注液前电解液中有机溶剂和锂盐的质量百分比；称量注液前电池单体的总质量、注液后电池单体的总质量，得到电解液的注液量m0，根据有机溶剂和锂盐的质量百分比计算得到有机溶剂的质量m1、锂盐的质量m2。
将电池单体按照上述方法进行100圈循环充放电测试，结束后擦拭电池单体表面的污垢并称量电池单体的总质量m3；拆解电池单体，并取其中的电解液测试有机溶剂和锂盐的质量百分比；制作隔离膜袋并称其质量m4；将拆解得到的所有部件装入隔离膜袋中，向隔离膜袋中加入溶剂二乙二醇二甲醚进行浸泡清洗从而除去残留的电解液；之后将隔离膜袋连同内部所有的部件进行加热干燥，结束后称取隔离膜袋连同内部所有的部件的总质量m5。m3+m4-m5为电解液的剩余量，根据有机溶剂和锂盐的质量百分比计算得到有机溶剂的剩余质量m6、锂盐的剩余质量m7。
有机溶剂的消耗量＝m1-m6。锂盐的消耗量＝m2-m7。
实施例2
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为1.5C(210mA)，截止电流为0.05C(7mA)，截止电压为2.8V。
实施例3
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为2C(280mA)，截止电流为0.05C(7mA)，截止电压为2.8V。
实施例4
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为3C(420mA)，截止电流为0.05C(7mA)，截止电压为2.8V。
实施例5
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为0.5C(70mA)，截止电流为0.05C(7mA)，截止电压为2.8V。
实施例6
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为1C(140mA)，截止电流为0.50C(70mA)，截止电压为2.8V。
实施例7
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为1C(140mA)，截止电流为0.25C(35mA)，截止电压为2.8V。
对比例1
电池单体的制备方法与实施例1相同，不同之处在于未进行脉冲放电。
对比例2
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为4C(560mA)，截止电流为0.01C(1.4mA)，截止电压为2.8V。
对比例3
电池单体的制备方法与实施例1相同，不同之处在于脉冲放电起始电流为4C(560mA)，截止电流为1C(140mA)，截止电压为2.8V。
对比例4
除电池单体循环充放电前采用恒电流放电之外，电池单体的制备方法与实施例1相同。
电池单体的制备：取一片裁剪好的贫锂正极极片与两片裁剪好的负极极片进行匹配，中间使用上述隔离膜隔绝，并包裹于铝塑膜袋中组成待注液电池单体；取0.3g电解液注入上述制备好的待注液电池单体中，然后将铝塑膜袋进行真空热压封装，在25℃下静置6小时以上，电池单体的容量为140mAh；然后对电池单体进行恒电流1C(140mA)放电，截止电压为2.8V，结束后得到电池单体，进行循环性能测试。
由表1测试结果可知，负极极片的锂金属层表面的凹坑满足平均尺寸为20μm-160μm、数量密度为208个/mm2至320个/mm2，可以使电池单体具有更长的循环寿命。
由实施例1至实施例7的测试结果还可知，进一步调节脉冲放电起始电流和/或截止电流，可以使电池单体具有更长的循环寿命。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其他方式也包含在本申请的范围内。

Claims (16)

  1. 一种电池单体，其中，
    所述电池单体包括负极极片，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面上的锂金属层，所述锂金属层表面具有多个凹坑，所述凹坑的平均尺寸为20μm-160μm，所述凹坑的数量密度为208个/mm2至320个/mm2。
  2. 根据权利要求1所述的电池单体，其中，
    所述凹坑的平均尺寸为20μm-45μm；和/或，
    所述凹坑的数量密度为280个/mm2至320个/mm2。
  3. 根据权利要求1-2任一项所述的电池单体，其中，基于所有凹坑的数量计，最大横向尺寸小于50μm的凹坑的数量占比为大于等于14％，最大横向尺寸大于100μm的凹坑的数量占比为大于0且小于等于55％。
  4. 根据权利要求3所述的电池单体，其中，基于所有凹坑的数量计，最大横向尺寸小于50μm的凹坑的数量占比为大于等于48％，最大横向尺寸大于100μm的凹坑的数量占比为大于0且小于等于18％。
  5. 根据权利要求1-4任一项所述的电池单体，其中，最大横向尺寸小于50μm的凹坑的数量密度为30个/mm2至202个/mm2，最大横向尺寸在50μm至100μm之间的凹坑的数量密度为60个/mm2至105个/mm2，最大横向尺寸大于100μm的凹坑的数量密度为14个/mm2至114个/mm2。
  6. 根据权利要求5所述的电池单体，其中，最大横向尺寸小于50μm的凹坑的数量密度为130个/mm2至202个/mm2，最大横向尺寸在50μm至100μm之间的凹坑的数量密度为88个/mm2至105个/mm2，最大横向尺寸大于100μm的凹坑的数量密度为14个/mm2至50个/mm2。
  7. 根据权利要求1-6任一项所述的电池单体，其中，所述凹坑的深度为所述锂金属层的厚度的10％以上且小于所述锂金属层的厚度。
  8. 根据权利要求1-7任一项所述的电池单体，其中，所述多个凹坑的面积之和为所述锂金属层的面积的20％-50％。
  9. 根据权利要求1-8任一项所述的电池单体，其中，所述电池单体包括正极极片，所述正极极片包括正极集流体以及设置在所述正极集流体至少一个表面上的正极膜层，所述正极膜层包括正极活性材料，所述正极活性材料包括含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物中的一种或多种。
  10. 根据权利要求1-9任一项所述的电池单体，其中，所述电池单体包括电解液，所述电解液的浓度为1mol/L-6mol/L。
  11. 一种电池单体的制备方法，包括如下步骤：
    将贫锂正极极片与负极极片组装得到电池单体，所述负极极片包括负极集流体以及设置在所述负极集流体至少一个表面上的锂金属层；
    将所述电池单体进行脉冲放电，得到电池单体，脉冲放电后所述锂金属层表面形成多个凹坑，所述凹坑的平均尺寸为20μm-160μm，所述凹坑的数量密度为208个/mm2至320个/mm2。
  12. 根据权利要求11所述的制备方法，其中，所述脉冲放电的起始电流小于等于3C，所述脉冲放电的截止电流为0.05C-0.50C。
  13. 根据权利要求12所述的制备方法，其中，所述脉冲放电的起始电流小于等于1C，所述脉冲放电的截止电流为0.05C-0.10C。
  14. 根据权利要求11-13任一项所述的制备方法，其中，所述贫锂正极极片包括正极集流体以及设置在所述正极集流体至少一个表面上的正极膜层，所述正极膜层包括贫锂相正极活性材料，所述贫锂相正极活性材料包括贫锂相磷酸盐、贫锂相过渡金属氧化物及其各自的改性化合物中的一种或多种。
  15. 一种电池，包括权利要求1-10任一项所述的电池单体或通过权利要求11-14任一项所述的制备方法制备的电池单体。
  16. 一种用电装置，包括权利要求15所述的电池。
PCT/CN2025/100273 2024-07-03 2025-06-10 电池单体及其制备方法、电池和用电装置 Pending WO2026007643A1 (zh)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1126022A (ja) * 1997-07-01 1999-01-29 Matsushita Electric Ind Co Ltd リチウムイオン二次電池の製造方法
US20050112469A1 (en) * 2003-11-25 2005-05-26 Ngk Spark Plug Co., Ltd. Lithium cell and method for manufacturing the same
CN108615892A (zh) * 2018-05-02 2018-10-02 南方科技大学 一种有效抑制锂金属电池枝晶不可控生长的改性集流体、其制备方法及用途
CN112889164A (zh) * 2020-04-23 2021-06-01 宁德时代新能源科技股份有限公司 锂金属电池及其制备方法、包含锂金属电池的装置和负极极片
CN112952185A (zh) * 2021-03-29 2021-06-11 湖北亿纬动力有限公司 一种锂离子电池及其制备方法
JP2023030374A (ja) * 2021-08-23 2023-03-08 株式会社スリーダムアライアンス リチウム金属電池の放電方法、リチウム金属電池の充放電方法、リチウム金属電池の制御装置、組電池の制御方法、組電池の制御システム
US20230275204A1 (en) * 2022-01-04 2023-08-31 Contemporary Amperex Technology Co., Limited Secondary battery, battery module, battery pack, and electric apparatus

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1126022A (ja) * 1997-07-01 1999-01-29 Matsushita Electric Ind Co Ltd リチウムイオン二次電池の製造方法
US20050112469A1 (en) * 2003-11-25 2005-05-26 Ngk Spark Plug Co., Ltd. Lithium cell and method for manufacturing the same
CN108615892A (zh) * 2018-05-02 2018-10-02 南方科技大学 一种有效抑制锂金属电池枝晶不可控生长的改性集流体、其制备方法及用途
CN112889164A (zh) * 2020-04-23 2021-06-01 宁德时代新能源科技股份有限公司 锂金属电池及其制备方法、包含锂金属电池的装置和负极极片
CN112952185A (zh) * 2021-03-29 2021-06-11 湖北亿纬动力有限公司 一种锂离子电池及其制备方法
JP2023030374A (ja) * 2021-08-23 2023-03-08 株式会社スリーダムアライアンス リチウム金属電池の放電方法、リチウム金属電池の充放電方法、リチウム金属電池の制御装置、組電池の制御方法、組電池の制御システム
US20230275204A1 (en) * 2022-01-04 2023-08-31 Contemporary Amperex Technology Co., Limited Secondary battery, battery module, battery pack, and electric apparatus
CN117157782A (zh) * 2022-01-04 2023-12-01 宁德时代新能源科技股份有限公司 二次电池、电池模块、电池包和用电装置

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