WO2024065764A1 - 负极极片及其制备方法、二次电池和用电装置 - Google Patents

负极极片及其制备方法、二次电池和用电装置 Download PDF

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Publication number
WO2024065764A1
WO2024065764A1 PCT/CN2022/123492 CN2022123492W WO2024065764A1 WO 2024065764 A1 WO2024065764 A1 WO 2024065764A1 CN 2022123492 W CN2022123492 W CN 2022123492W WO 2024065764 A1 WO2024065764 A1 WO 2024065764A1
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Prior art keywords
negative electrode
film layer
current collector
secondary battery
electrode sheet
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PCT/CN2022/123492
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English (en)
French (fr)
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唐代春
田亚西
王曦童
姬廷振
夏雨润
谌湘艳
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宁德时代新能源科技股份有限公司
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Priority to CN202280011416.6A priority Critical patent/CN116830282A/zh
Priority to PCT/CN2022/123492 priority patent/WO2024065764A1/zh
Publication of WO2024065764A1 publication Critical patent/WO2024065764A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • 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

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  • the present application relates to the field of batteries, and in particular to a negative electrode plate and a preparation method thereof, a secondary battery and an electrical device.
  • Secondary batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools, etc.
  • the pole pieces in the secondary batteries such as the negative pole pieces
  • their fast charging capability and safety performance are still poor and need to be further improved.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a negative electrode plate and its preparation method, a secondary battery and an electrical device.
  • the negative electrode plate When the negative electrode plate is applied to a secondary battery, it can improve the fast charging capability and safety performance of the secondary battery.
  • a first aspect of the present application provides a negative electrode plate, comprising a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer comprising an infiltration cavity having an opening facing away from the negative electrode current collector, and the infiltration cavity extending along a first direction; a size of the negative electrode film layer along the first direction is recorded as A ⁇ m; a size of the infiltration cavity along the first direction is recorded as A1 ⁇ m , and the negative electrode plate satisfies: 0.1 ⁇ A1 /A ⁇ 1; optionally, 0.2 ⁇ A1 /A ⁇ 1.
  • the diffusion path of active ions such as lithium ions in the negative electrode plate becomes shorter, which can significantly improve the concentration polarization problem on both sides of the negative electrode film layer and improve the safety performance and fast charging capability of the secondary battery.
  • the first direction and the length direction of the negative electrode sheet have an angle ⁇ °, 0 ⁇ 180°.
  • the first direction is parallel to the length direction of the negative electrode sheet.
  • the first direction is parallel to the width direction of the negative electrode sheet.
  • the negative electrode sheet, the positive electrode sheet and the separator in the present application form an electrode assembly
  • they can be wound along the length direction of the negative electrode sheet;
  • the electrode assembly when the electrode assembly is placed in the shell to form a secondary battery, the height direction of the secondary battery can be parallel to the length direction of the negative electrode sheet, can be parallel to the width direction of the negative electrode sheet, or can have an angle with the direction of the negative electrode sheet.
  • the electrolyte can be guided from the bottom to the top of the secondary battery in the infiltration cavity, and the electrolyte infiltrates the electrode assembly more evenly in the height direction of the secondary battery, and the migration rate of active ions in the height direction is not much different, so that the performance of the electrode assembly can be uniform during the charging and discharging process, and the fast charging ability and safety performance of the secondary battery can be further improved.
  • the dimension of the negative electrode film layer in the thickness direction of the negative electrode sheet is d ⁇ m; the dimension of the wetting cavity in the thickness direction of the negative electrode sheet is d 1 ⁇ m; the negative electrode sheet satisfies: 0.01 ⁇ d 1 /d ⁇ 1; optionally, 0.2 ⁇ d 1 /d ⁇ 0.8.
  • the size of the wetting cavity in the thickness direction of the negative electrode plate in the present application satisfies the above relationship, the impact of dimensional fluctuations caused by process deviations can be reduced, and the electrolyte can be fully infiltrated into the interior of the negative electrode film layer, so that the active ions can migrate more rapidly in the negative electrode film layer, thereby further reducing the risk of concentration polarization and improving the fast charging capability and safety performance of the secondary battery.
  • the cross section of the infiltration cavity parallel to the second direction includes a first edge and a second edge, the first edge and the second edge are opposite to each other along the thickness direction of the negative electrode sheet, the first edge is arranged away from the negative electrode current collector, and the second edge is arranged close to the negative electrode current collector; the second direction, the first direction and the thickness direction are perpendicular to each other; the size of the first edge is recorded as x 1 ⁇ m, 20 ⁇ x 1 ⁇ 5000; optionally, 20 ⁇ x 1 ⁇ 80; and/or the size of the second edge is recorded as x 2 ⁇ m, 20 ⁇ x 2 ⁇ 5000; optionally, 20 ⁇ x 2 ⁇ 80.
  • the cross-sectional shape of the infiltration cavity parallel to the thickness direction is a regular polygon or an irregular polygon; optionally, the cross-sectional shape of the infiltration cavity parallel to the thickness direction is a rectangle, a square, a trapezoid, or a polygon containing an arc.
  • the structural form of the infiltration cavity can be flexibly set according to production requirements, and the setting of the size of the first edge and the second edge of the infiltration cavity can regulate the speed at which the active ions are embedded in the negative electrode active material, thereby improving the fast charging capability of the secondary battery.
  • the cross section further includes two side edges opposite to each other along the second direction, and the two side edges are connected by a second edge; an angle formed by one of the two side edges and the second edge is ⁇ °, 0 ⁇ 150°.
  • the structural form of the infiltration cavity in the embodiment of the present application can be flexibly set according to production requirements, and the setting of the angle between the side and the second edge of the infiltration cavity can regulate the speed at which active ions are embedded in the negative electrode active material, thereby improving the fast charging capability of the secondary battery.
  • the porosity of the negative electrode film layer is recorded as P%, and 10 ⁇ P ⁇ 40.
  • the porosity P% of the negative electrode film layer is within the above range, the fast charging capability and energy density of the secondary battery can be improved.
  • a plurality of infiltration cavities are provided, and the plurality of infiltration cavities are provided at intervals.
  • the provision of the plurality of infiltration cavities can further improve the liquid phase conduction speed of the active ions in the negative electrode film layer, so that the active ions can be more quickly embedded in the negative electrode active material, thereby improving the fast charging capability of the secondary battery.
  • a second aspect of the present application provides a method for preparing a negative electrode plate, the method comprising: providing a negative electrode collector; arranging a shielding member on at least one surface of the negative electrode collector, the shielding member comprising a first through hole penetrating the shielding member; applying a negative electrode slurry on the shielding member so that the negative electrode slurry flows through the through hole to the surface of the negative electrode collector; curing the negative electrode slurry so that the negative electrode slurry forms a negative electrode film layer on the surface of the negative electrode collector, the negative electrode film layer having an infiltration cavity staggered with the first through hole, the negative electrode film layer and the negative electrode collector constituting a negative electrode plate, wherein the infiltration cavity extends along a first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A1 ⁇ m , and the negative electrode plate satisfies: 0.1 ⁇ A1 /A ⁇ 1; optionally, 0.2
  • a third aspect of the present application provides a method for preparing a negative electrode plate, the method comprising: providing a negative electrode collector; coating a negative electrode slurry on at least one surface of the negative electrode collector; using a pressing member disposed on the negative electrode slurry to apply a force to the negative electrode slurry so that the negative electrode slurry has a concave portion; curing the negative electrode slurry so that the negative electrode slurry forms a negative electrode film layer on the surface of the negative electrode collector, the negative electrode film layer having an infiltration cavity corresponding to the concave portion, the negative electrode film layer and the negative electrode collector constituting a negative electrode plate, wherein the infiltration cavity extends along a first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A1 ⁇ m , and the negative electrode plate satisfies: 0.1 ⁇ A1 /A ⁇ 1; optionally, 0.2 ⁇ A1 /A ⁇ 1.
  • a fourth aspect of the present application provides a method for preparing a negative electrode sheet, the method comprising: providing a negative electrode collector; coating a negative electrode slurry on at least one surface of the negative electrode collector; curing the negative electrode slurry so that the negative electrode slurry forms a negative electrode film layer on the surface of the negative electrode collector; opening an infiltration cavity on the negative electrode film layer, the negative electrode film layer and the negative electrode collector constitute a negative electrode sheet, wherein the infiltration cavity extends along a first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A1 ⁇ m , and the negative electrode sheet satisfies: 0.1 ⁇ A1 /A ⁇ 1; optionally, 0.2 ⁇ A1 /A ⁇ 1.
  • the fifth aspect of the present application further provides a secondary battery, wherein the secondary battery comprises a negative electrode sheet as described in any embodiment of the first aspect of the present application or a negative electrode sheet prepared by the method described in any embodiment of the second aspect of the present application.
  • the first direction and the height direction of the secondary battery have an angle ⁇ °, 0 ⁇ 180°; optionally, 0 ⁇ 30° or 150 ⁇ 180°.
  • the sixth aspect of the present application further provides an electrical device, comprising a secondary battery as in any embodiment of the fifth aspect of the present application.
  • FIG. 1 is a schematic structural diagram of an embodiment of a negative electrode plate of the present application.
  • FIG2 is a schematic cross-sectional view of the negative electrode sheet shown in FIG1 taken along line I-I.
  • FIG. 3 is a schematic structural diagram of an embodiment of a negative electrode plate of the present application.
  • FIG. 4 is an enlarged schematic diagram of the negative electrode plate shown in FIG. 3 at position II.
  • FIG. 5 is a schematic diagram of an electrode assembly of a secondary battery according to an embodiment of the present invention.
  • FIG. 6 is a schematic diagram of an embodiment of a secondary battery of the present application.
  • FIG. 7 is an exploded schematic diagram of the embodiment of the secondary battery of FIG. 6 .
  • FIG. 8 is a schematic diagram of an embodiment of a battery module of the present application.
  • FIG. 9 is a schematic diagram of an embodiment of a battery pack of the present application.
  • FIG. 10 is an exploded schematic diagram of the embodiment of the battery pack shown in FIG. 9 .
  • FIG. 11 is a schematic diagram of an embodiment of an electric device including the secondary battery of the present application as a power source.
  • X first direction
  • Y second direction
  • Z thickness direction
  • electrode assembly 521, negative electrode plate; 5211, negative electrode current collector; 5212, negative electrode film layer; 5213, wetting cavity; 5214, first edge; 5215, second edge; 5216, side
  • range disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range.
  • the range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • the negative electrode During the charging process of a secondary battery, the negative electrode generally needs to go through the following electrochemical processes: (1) desolvation of solvated lithium ions; (2) passage of desolvated lithium ions through the solid electrolyte membrane; (3) charge transfer reaction of lithium ions at the interface between the active material and the solid electrolyte membrane; and (4) solid phase diffusion of lithium ions in the active material.
  • the precipitated metallic lithium will further increase the barrier for lithium ions to enter the negative electrode active material, which may further aggravate the concentration polarization problem; lithium ions further precipitate on the surface of the negative electrode film layer and may further form lithium dendrites. Lithium dendrites may pierce the isolation membrane and cause the positive electrode sheet and the negative electrode sheet to short-circuit, causing safety risks. In addition, due to the slow liquid phase conduction rate of active ions, the fast charging ability of the secondary battery is poor.
  • the inventors start from improving the structure of the negative electrode plate, in order to obtain a negative electrode plate that can take into account both fast charging capability and safety performance. Next, the specific structure of the negative electrode plate is described.
  • the present application proposes a negative electrode plate.
  • the negative electrode plate 521 includes a negative electrode current collector 5211 and a negative electrode film layer 5212 disposed on at least one surface of the negative electrode current collector 5211 , the negative electrode film layer 5212 includes an infiltration cavity 5213 having an opening facing away from the negative electrode current collector 5211 , the infiltration cavity 5213 extends along a first direction, the size of the negative electrode film layer 5212 along the first direction is recorded as A ⁇ m, the size of the infiltration cavity 5213 along the first direction is recorded as A 1 ⁇ m, and 0.1 ⁇ A 1 /A ⁇ 1.
  • the negative electrode current collector 5211 has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer 5212 is disposed on any one or both of the two opposite surfaces of the negative electrode current collector 5211 .
  • the inventors have found through extensive research that the design parameters of the wetting cavity 5213 have a certain degree of influence on the fast charging capability and safety performance of the secondary battery, especially when 0.1 ⁇ A 1 /A ⁇ 1, due to the presence of the wetting cavity, the diffusion path of active ions such as lithium ions in the negative electrode plate becomes shorter, which can significantly improve the concentration polarization problem on both sides of the negative electrode film layer, and improve the safety performance and fast charging capability of the secondary battery.
  • the infiltration cavity 5213 extends along the first direction, which means that the infiltration cavity 5213 can be similar to a straight-line extension trend, or it can mean that the overall trend of the infiltration cavity 5213 is approximately extending along the first direction, for example, the infiltration cavity 5213 can include an arc segment, etc.
  • the first direction can have an angle ⁇ ° with the length direction of the negative electrode plate, 0 ⁇ 180°. Optionally, 0 ⁇ 30° or 150 ⁇ 180°.
  • ⁇ >0 it means that the first direction has a certain angle with the direction of the negative electrode plate.
  • the X direction shown in FIG. 1 represents a first direction, which is parallel to the width direction of the negative electrode sheet 521 .
  • the values of A1 and A can be measured using a soft ruler or a scanning electron microscope.
  • the liquid phase conduction of active ions in the negative electrode film layer 5212 includes two pathways.
  • One pathway is that the active ions can diffuse into the negative electrode film layer 5212 through the surface of the negative electrode film layer 5212; the other pathway is that since the electrolyte is stored in the infiltration cavity 5213, it is equivalent to the electrolyte infiltrating the negative electrode film layer 5212.
  • the active ions in this part of the electrolyte can directly migrate from the infiltration cavity 5213 to the inside of the negative electrode film layer 5212, and the path of migration to the negative electrode active material is relatively short, which can significantly improve the concentration polarization problem on both sides of the negative electrode film layer 5212 and improve the safety performance and fast charging capability of the secondary battery.
  • a 1 /A can be 0.1, 0.2, 0.5, 0.6, 0.8, 0.9, 1 or a range consisting of any two of the above values.
  • the negative electrode sheet 521 when the negative electrode sheet 521 is manufactured as a finished product, it presents a sheet structure with a preset length, height and width.
  • the negative electrode sheet 521, the positive electrode sheet 522 and the separator 523 form the electrode assembly 52, they can be wound along the length direction of the negative electrode sheet 521; when the electrode assembly 52 is placed in the shell 51 to form the secondary battery 5, the height direction of the secondary battery 5 can be parallel to the length direction of the negative electrode sheet 521, or it can be parallel to the width direction of the negative electrode sheet 521.
  • the X direction shown in Figure 7 indicates that the height direction of the secondary battery 5 is parallel to the width direction of the negative electrode sheet 521.
  • the electrolyte in the secondary battery 5 accumulates at the bottom, resulting in the electrolyte infiltrating the electrode assembly 52 at the bottom more fully, and the electrode assembly 52 far from the bottom is poorly infiltrated, and the electrolyte has uneven wetting performance on the electrode assembly 52 as a whole; during the charge and discharge cycle of the secondary battery 5, when active ions such as lithium ions migrate in the electrode assembly 52 far from the bottom, the lithium ions may not be embedded in the negative electrode plate 521 due to lack of electrolyte, thereby causing the lithium ions to precipitate on the surface of the negative electrode plate 521.
  • the extension direction (first direction) of the infiltration cavity 5213 and the height direction of the secondary battery 5 may have an angle ⁇ °, 0 ⁇ 180°.
  • the angle between the extension direction of the infiltration cavity 5213 and the height direction of the secondary battery 5 is within a certain range, the migration rate of active ions such as lithium ions in the liquid phase can be effectively improved, which is beneficial to improving the fast charging performance of the secondary battery 5.
  • ⁇ ° can be 0, 5°, 12°, 15°, 25°, 30°, 150°, 155°, 160°, 170°, 175°, 179° or within the range of any two of the above values.
  • the extending direction of the infiltration cavity 5213 is parallel to the height direction of the secondary battery 5; in this case, the length direction of the negative electrode sheet 521 may be parallel to the height direction of the secondary battery, or the width direction of the negative electrode sheet 521 may be parallel to the height direction of the secondary battery 5.
  • the X direction shown in FIG7 indicates that the height direction of the secondary battery 5 is parallel to the width direction of the negative electrode sheet 521.
  • the electrolyte can be guided from the bottom to the top of the secondary battery 5 in the infiltration cavity 5213.
  • the electrolyte infiltrates the electrode assembly 52 more evenly in the height direction of the secondary battery 5, and the migration rate of active ions in the height direction is not much different, thereby ensuring that the performance of the electrode assembly 52 is uniform during the charging and discharging process, further improving the fast charging capability and safety performance of the secondary battery 5.
  • the extending direction of the infiltration cavity 5213 may be parallel to the height direction of the secondary battery 5 or may intersect with the height direction. In this case, the infiltration cavity 5213 still has the ability to guide the electrolyte at the bottom to the top.
  • the inventors further discovered that, in addition to the extension length and extension direction of the infiltration cavity 5213 having an impact on the fast charging capability and safety performance of the secondary battery, other dimensional parameters of the infiltration cavity 5213 will further improve the performance of the secondary battery 5 if they can meet one or more of the following conditions.
  • the dimension of the negative electrode film layer 5212 in the thickness direction of the negative electrode sheet 521 is recorded as d ⁇ m; the dimension of the infiltration cavity 5213 in the thickness direction of the negative electrode sheet 521 is recorded as d 1 ⁇ m; the negative electrode sheet 521 satisfies: 0.01 ⁇ d 1 /d ⁇ 1.
  • d 1 and d are shown in FIG4 , and the Z direction shown in FIG3 and FIG4 represents the thickness direction.
  • the dimension d of the negative electrode film layer 5212 in the thickness direction i.e., the thickness of the negative electrode film layer 5212, is well known in the art and can be measured using equipment or methods well known in the art. Specifically, it can be measured using a micrometer, for example, a micrometer with a model of Mitutoyo 293-100 and an accuracy of 0.1 ⁇ m.
  • the thickness of the negative electrode film layer 5212 of the present invention refers to the thickness of the negative electrode film in the negative electrode sheet 521 used to assemble the battery after cold pressing.
  • the thickness data of the infiltration cavity 5213 in the thickness direction can be obtained by using a scanning electron microscope (SEM).
  • d 1 /d can be 0.01, 0.1, 0.2, 0.3, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95 or 0.99; or a range consisting of the above data.
  • the cross section of the wetting cavity 5213 parallel to the second direction includes a first edge 5214 and a second edge 5215, the first edge 5214 and the second edge 5215 are opposite to each other along the thickness direction, the first edge 5214 is arranged away from the negative electrode current collector 5211, and the second edge 5215 is arranged close to the negative electrode current collector 5211; the second direction, the first direction and the thickness direction are perpendicular to each other.
  • the Z direction shown in Figures 3 and 4 represents the thickness direction, and the Y direction represents the second direction.
  • the size of the first edge 5214 and the size of the second edge 5215 of the infiltration cavity 5213 are well known in the art and can be tested using equipment and methods well known in the art. Specifically, a scanning electron microscope (SEM) can be used to obtain the hole cross section for characterization.
  • SEM scanning electron microscope
  • the size of the first edge 5214 of the infiltration cavity 5213 is recorded as x 1 ⁇ m.
  • the size of the first edge 5214 is small, the number of active ions migrating from the infiltration cavity 5213 to the negative electrode film layer 5212 is relatively small, and its ability to improve the migration of active ions is relatively small; when the size of the first edge 5214 is large, the overall gram capacity of the negative electrode film layer 5212 is small, and the energy density of the secondary battery is small.
  • the size of the first edge 5214 of the infiltration cavity 5213 satisfies: 20 ⁇ x 1 ⁇ 100, and further satisfies 20 ⁇ x 1 ⁇ 80, the fast charging capability and safety performance of the secondary battery can be taken into account.
  • the size of the second edge 5215 of the infiltration cavity 5213 is recorded as x 2 ⁇ m.
  • the size of the second edge 5215 is small, the active ions that migrate from the infiltration cavity 5213 to the negative electrode film layer 5212 are relatively small, and its ability to improve the migration of active ions is relatively small; when the size of the second edge 5215 is large, the overall gram capacity of the negative electrode film layer 5212 is small, and the energy density of the secondary battery is small.
  • the size of the first edge 5214 of the infiltration cavity 5213 satisfies: 20 ⁇ x 2 ⁇ 5000, and further satisfies 20 ⁇ x 2 ⁇ 80, the fast charging capability, safety performance and energy density of the secondary battery can be taken into account.
  • the structural form of the infiltration cavity 5213 can be flexibly set according to production requirements.
  • the setting of the size of the first edge 5214 and the second edge 5215 of the infiltration cavity 5213 can regulate the speed at which active ions are embedded in the negative electrode active material, thereby improving the fast charging capability of the secondary battery.
  • the cross section of the infiltration cavity 5213 may be a regular quadrilateral structure (such as a rectangle, a square, etc.); when x1 - x2 >0 or x1 - x2 ⁇ 0, it indicates that the cross section of the infiltration cavity 5213 may be a trapezoidal structure, etc.; of course, in addition to the above-mentioned quadrilateral structure, the cross section of the infiltration cavity 5213 may also be a regular polygon such as a pentagon, a hexagon, a heptagon, or an irregular polygon; the irregular polygon may be a polygon with unequal sides, or a polygon structure including an arc, etc.
  • the cross section of the infiltration chamber 5213 may further include two side edges 5216 opposite to each other along the second direction, the two side edges 5216 are connected by a second edge 5215, and the angle formed by one of the two side edges 5216 and the second edge 5215 is ⁇ °, 0 ⁇ 150.
  • the angle formed by the side 5216 of the infiltration cavity 5213 and the second edge 5215 is well known in the art and can be tested using equipment and methods well known in the art. Specifically, a scanning electron microscope SEM can be used to obtain the hole cross section for characterization and determine the angle data.
  • the structural form of the infiltration cavity 5213 can be flexibly set according to production requirements.
  • the setting of the angle between the side 5216 and the second edge 5215 of the infiltration cavity 5213 can regulate the speed at which active ions are embedded in the negative electrode active material, thereby improving the fast charging capability of the secondary battery.
  • the porosity of the negative electrode film layer 5212 is denoted as P%, where 10 ⁇ P ⁇ 40.
  • the porosity P% of the negative electrode film layer 5212 will affect the liquid phase conduction ability of active ions in the pores of the negative electrode film layer 5212.
  • the active ions are more easily embedded in the negative electrode active material. At the same time, it can also reduce the risk of active ions being reduced and precipitated on the surface of the negative electrode film layer 5212 and growing lithium dendrites.
  • the secondary battery can only have a small irreversible capacity loss during repeated charge and discharge, and the cycle life of the secondary battery is increased; however, as the porosity P% further increases, the loss of energy density of the secondary battery will become more and more serious.
  • the porosity P% of the negative electrode film layer 5212 is within the above range, the fast charging capability and energy density of the secondary battery can be improved.
  • the porosity of the negative electrode film layer 5212 may be 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, or a range consisting of any two of the above values.
  • the infiltration chamber 5213 is provided in plurality, and the plurality of infiltration chambers 5213 are arranged at intervals.
  • the provision of multiple infiltration cavities 5213 can further improve the liquid phase conduction speed of active ions in the negative electrode film layer 5212, so that the active ions can be embedded in the negative electrode active material more quickly, thereby improving the fast charging capability of the secondary battery.
  • the negative electrode current collector 5211 may be a metal foil or a composite current collector.
  • a metal foil a copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode film layer 5212 includes a negative electrode active material.
  • the negative electrode active material may be a negative electrode active material for a battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the negative electrode film layer 5212 may further include a negative electrode binder.
  • the negative electrode binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the negative electrode film layer 5212 may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the negative electrode film layer 5212 may also optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet 521 can be prepared by various methods. Next, the preparation of the negative electrode sheet 521 is described.
  • the present application proposes a method for preparing a negative electrode sheet.
  • the method comprises:
  • the infiltration cavity extends along the first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A 1 ⁇ m, and the negative electrode plate satisfies: 0.1 ⁇ A 1 /A ⁇ 1; optionally, 0.2 ⁇ A 1 /A ⁇ 1.
  • the negative electrode slurry of the present application is pore-formed before solidification, that is, the negative electrode slurry has a certain fluidity.
  • the negative electrode slurry When the negative electrode slurry is coated on the shielding member, the negative electrode slurry will automatically flow to the first through hole, and the solid part of the shielding member will play a shielding role, providing favorable conditions for the subsequent preparation of the wetting cavity; the shielding member is heated to solidify the slurry around the shielding member, reducing the risk of the wetting cavity being filled due to the flow of the negative electrode slurry, thereby ensuring the effective formation of the wetting cavity.
  • the present application also proposes a method for preparing a negative electrode plate.
  • the method comprises:
  • the infiltration cavity extends along the first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A 1 ⁇ m, and the negative electrode plate satisfies: 0.1 ⁇ A 1 /A ⁇ 1; optionally, 0.2 ⁇ A 1 /A ⁇ 1.
  • the negative electrode slurry of the present application is pore-formed before solidification, that is, the negative electrode slurry has a certain fluidity.
  • the required force is relatively small, and basically no loss of the negative electrode slurry is caused.
  • the present application also proposes a method for preparing a negative electrode plate.
  • the method comprises:
  • the infiltration cavity extends along the first direction; the size of the negative electrode film layer along the first direction is recorded as A ⁇ m; the size of the infiltration cavity along the first direction is recorded as A 1 ⁇ m, and the negative electrode plate satisfies: 0.1 ⁇ A 1 /A ⁇ 1; optionally, 0.2 ⁇ A 1 /A ⁇ 1.
  • holes are formed after the negative electrode slurry is solidified, and equipment such as a roller cutter can be used to form holes on the solidified negative electrode sheet.
  • the present application proposes a secondary battery 5 .
  • the secondary battery includes a positive electrode sheet 522, a negative electrode sheet 521, an electrolyte and a separator 523.
  • active ions are embedded and removed back and forth between the positive electrode sheet 522 and the negative electrode sheet 521.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet 522 and the negative electrode sheet 521.
  • the separator 523 is arranged between the positive electrode sheet 522 and the negative electrode sheet 521, which mainly plays the role of preventing the positive and negative electrodes from short-circuiting, and at the same time allows ions to pass through.
  • the negative electrode sheet 521 of the present application can be the negative electrode sheet 521 of any embodiment of the first aspect of the present application or the negative electrode sheet 521 prepared by any method described in the second to fourth aspects of the present application.
  • the positive electrode sheet 522 includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode film layer includes a positive electrode active material, and the positive electrode active material can adopt a positive electrode active material for a secondary battery known in the art.
  • the positive electrode active material may include at least one of the following materials: a layered structure positive electrode active material (such as ternary, lithium nickelate/sodium, lithium cobaltate/sodium, lithium manganate/sodium, lithium/sodium-rich layered and rock salt phase layered materials), an olivine-type phosphate active material, a spinel structured positive electrode active material (such as spinel lithium manganate, spinel nickel lithium manganate, lithium-rich spinel lithium manganate, and lithium nickel lithium manganate, etc.).
  • a layered structure positive electrode active material such as ternary, lithium nickelate/sodium, lithium cobaltate/sodium, lithium manganate/sodium, lithium/sodium-rich layered and rock salt phase layered materials
  • an olivine-type phosphate active material such as spinel lithium manganate,
  • the general formula of the layered positive electrode active material is: LixAyNiaCobMncM (1-abc) Yz , wherein 0 ⁇ x ⁇ 2.1, 0 ⁇ y ⁇ 2.1, and 0.9 ⁇ x+y ⁇ 2.1; 0 ⁇ a ⁇ 1 , 0 ⁇ b ⁇ 1, 0 ⁇ c ⁇ 1, and 0.1 ⁇ a+b+c ⁇ 1; 1.8 ⁇ z ⁇ 3.5;
  • A is selected from one or more of Na, K, and Mg;
  • M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • Y is selected from one or more of O and F.
  • the layered structure positive active material may include one or more of lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), and LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523).
  • the general formula of the olivine phosphate active material is: LixAyMeaMbP1 - cXcYz , wherein 0 ⁇ x ⁇ 1.3 , 0 ⁇ y ⁇ 1.3 , and 0.9 ⁇ x+y ⁇ 1.3; 0.9 ⁇ a ⁇ 1.5, 0 ⁇ b ⁇ 0.5, and 0.9 ⁇ a+b ⁇ 1.5; 0 ⁇ c ⁇ 0.5; 3 ⁇ z ⁇ 5;
  • A is selected from one or more of Na, K, and Mg;
  • Me is selected from one or more of Mn, Fe, Co, and Ni;
  • M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce;
  • X is selected from one or more of S, Si, Cl, B, C, and N; and Y is selected from one or more of O and F
  • the general formula of the positive electrode active material with a spinel structure is: LixAyMnaM2 - aYz , wherein 0 ⁇ x ⁇ 2 , 0 ⁇ y ⁇ 1, and 0.9 ⁇ x+y ⁇ 2; 0.5 ⁇ a ⁇ 2; 3 ⁇ z ⁇ 5;
  • A is selected from one or more of Na, K, and Mg;
  • M is selected from one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F.
  • the positive electrode active material of the spinel structure includes one or more of LiMn 2 O 4 , LiNi 0.5 Mn 1.5 O 4 , LiCr 0.3 Mn 1.7 O 4 , Li 1.1 Al 0.1 Mn 1.9 O 4 , Li 2 Mn 2 O 4 and Li 1.5 Mn 2 O 4 .
  • the positive electrode film layer may further include a positive electrode conductive agent.
  • a positive electrode conductive agent includes a combination of one or more selected from superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the mass percentage of the positive electrode conductive agent is less than 5%.
  • the positive electrode film layer may also optionally include a positive electrode binder.
  • the positive electrode binder may include a combination of one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • tetrafluoroethylene-hexafluoropropylene copolymer
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • a metal foil an aluminum foil or an aluminum alloy foil may be used.
  • the composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer.
  • the metal material may include a combination of one or more selected from aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy
  • the polymer material base layer may include a combination of one or more selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).
  • the positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing.
  • the positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder and any other components in a solvent and stirring them uniformly.
  • the solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.
  • the electrolyte plays a role in conducting ions between the positive electrode plate 522 and the negative electrode plate 521.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the lithium salt may include a combination of one or more selected from lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bisfluorosulfonyl imide (LiFSI), lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium bisoxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobisoxalatophosphate (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium te
  • the organic solvent may include a combination of one or more selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), cyclopentane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (ESE).
  • EC ethylene carbon
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator 523.
  • the present application has no particular limitation on the type of separator 523, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation film 523 can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation film can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the positive electrode sheet 522 , the negative electrode sheet 521 , and the separator 523 may be formed into the electrode assembly 52 by a winding process or a lamination process.
  • FIG6 is a secondary battery 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film may form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the secondary battery 5 may be one or more, which can be adjusted according to demand.
  • the positive electrode sheet 522, the separator 523, the negative electrode sheet 521 and the electrolyte can be assembled to form the secondary battery 5.
  • the positive electrode sheet 522, the separator 523, and the negative electrode sheet 521 can be formed into an electrode assembly 52 through a winding process or a lamination process, and the electrode assembly 52 is placed in an outer package, and the electrolyte is injected after drying, and the secondary battery 5 is obtained through vacuum packaging, standing, forming, shaping and other processes.
  • the secondary battery 5 according to the present application can be assembled into a battery module.
  • the number of secondary batteries 5 contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG8 is a schematic diagram of a battery module 4 as an example.
  • a plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a housing space, and the plurality of secondary batteries 5 are housed in the housing space.
  • the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.
  • FIG9 and FIG10 are schematic diagrams of a battery pack 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 may be arranged in the battery box in any manner.
  • the present application provides an electrical device, which includes at least one of the secondary battery, battery module and battery pack of the present application.
  • the secondary battery, battery module and battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device.
  • the electrical device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.
  • the electric device can select a secondary battery, a battery module or a battery pack according to its usage requirements.
  • Fig. 11 is a schematic diagram of an electric device as an example.
  • the electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack 1 or a battery module can be used.
  • the electric device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • the electric device is usually required to be light and thin, and a secondary battery may be used as a power source.
  • Aluminum foil with a thickness of 12 ⁇ m was used as the positive electrode current collector.
  • the positive electrode active material, the conductive agent carbon black, and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in a proper amount of solvent NMP at a weight ratio of 97.5:1.4:1.1 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on the surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained.
  • PVDF polyvinylidene fluoride
  • a copper foil with a thickness of 8 ⁇ m was used as the negative electrode current collector.
  • the negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) were fully stirred and mixed in an appropriate amount of solvent deionized water at a weight ratio of 96.8:0.7:1.3:1.2 to form a uniform negative electrode slurry.
  • a shielding member such as a coating gasket is set on the negative electrode collector, and the negative electrode slurry flows to the surface of the negative electrode collector through the first through hole of the coating gasket.
  • the negative electrode slurry is solidified into a negative electrode film layer, and the negative electrode film layer protects the infiltration cavity. After drying and cold pressing, the negative electrode film layer and the negative electrode collector form a negative electrode sheet.
  • a porous polyethylene (PE) membrane was used as the isolation membrane.
  • non-aqueous organic solvents ethylene carbonate EC and diethyl carbonate DMC are mixed in a volume ratio of 1:1 to obtain an electrolyte solvent, and then lithium salt and the mixed solvent are mixed to prepare an electrolyte with a lithium salt concentration of 1 mol/L.
  • the positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, and after drying, the electrolyte is injected, and the lithium-ion battery is obtained after vacuum packaging, standing, forming, shaping, etc.
  • the extension direction of the infiltration cavity in the negative electrode sheet is parallel to the height direction of the lithium-ion battery.
  • Examples 1-2 to 1-4 lithium-ion batteries were prepared in a similar manner to that in Example 1-1. The difference from Example 1-1 was that in Examples 1-2 to 1-4, the size d 1 ⁇ m of the wetting cavity in the thickness direction of the negative electrode sheet was adjusted.
  • Examples 2-1 to 2-4 prepare lithium ion batteries in a manner similar to that of Example 1-3. The difference from Example 1-3 is that in Examples 2-1 to 2-4, the size A 1 ⁇ m of the wetting cavity in the first direction is adjusted.
  • Examples 3-1 to 3-3 prepared lithium ion batteries in a similar manner to Example 1-3. The difference from Example 1-3 was that the size x 2 ⁇ m of the second edge of the wetting cavity was adjusted in Examples 3-1 to 3-3.
  • Example 4-1 and Example 4-2 lithium ion batteries were prepared in a similar manner to Example 1-3. The difference from Example 1-3 was that in Example 4-1 and Example 4-2, the angle ⁇ ° formed by the side of the wetting cavity and the second edge was adjusted.
  • lithium-ion batteries are prepared according to methods similar to those in Example 1-3. The difference from Example 1-3 is that in Examples 5-1 to 5-3, at least the angle ⁇ ° between the extension direction of the wetting cavity and the height direction of the lithium-ion battery is adjusted.
  • Comparative Example 1 A lithium-ion battery was prepared in a similar manner to that of Example 1. The difference from Example 1 is that the preparation process of the negative electrode sheet was adjusted in Comparative Example 1; specifically, a copper foil with a thickness of 6 ⁇ m was used as the negative electrode current collector.
  • the negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene butadiene rubber (SBR), and the thickener sodium hydroxymethyl cellulose (CMC) were fully stirred and mixed in an appropriate amount of solvent deionized water at a weight ratio of 96.8:0.7:1.3:1.2 to form a uniform negative electrode slurry, and the negative electrode slurry was coated on the negative electrode current collector; the negative electrode slurry was dried and cold pressed to form a negative electrode film layer, which was the negative electrode sheet.
  • the pore size of Comparative Example 1 was 1 ⁇ m, and its porosity was 20%.
  • the porosity of Comparative Example 1 originated from the pore structure formed in the negative electrode film layer during the drying and cold pressing process.
  • an infiltration cavity is opened on the negative electrode film layer, and the infiltration cavity is arranged along the height direction of the secondary battery.
  • the electrolyte can be absorbed through the infiltration cavity, so that the electrolyte enhances the infiltration effect on the negative electrode film layer, which is beneficial to the rapid migration of lithium ions, improves the fast charging capability, and can also reduce the local precipitation of lithium ions and improve safety performance.
  • Examples 5-1 to 5-3 adjust the extension direction of the infiltration cavity.
  • the extension direction of the infiltration cavity has an angle greater than 0° with the height direction of the lithium ions, the liquid phase transmission rate of lithium ions can be improved to a certain extent, which is beneficial to improving the fast charging capability of lithium ions.
  • the prepared secondary battery was charged at a constant current of 0.33C to a charge cut-off voltage of 4.4V, then charged at a constant voltage to a current of 0.05C, allowed to stand for 5 minutes, and then discharged at a constant current of 0.33C to a discharge cut-off voltage of 2.8V, and its actual capacity was recorded as C0.
  • the secondary battery is charged with a constant current of 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, and 4.5C0 in sequence to a full battery charge cutoff voltage of 4.4V or a negative electrode cutoff potential of 0V (whichever is reached first).
  • a full battery charge cutoff voltage of 4.4V or a negative electrode cutoff potential of 0V (whichever is reached first).
  • 1C0 to a full battery discharge cutoff voltage of 2.8V.
  • the negative electrode potential corresponding to charging to 10%, 20%, 30%...80% SOC (State of Charge) at different charge rates is recorded, and the rate-negative electrode potential curve under different SOC states is plotted. After linear fitting, the negative electrode potential curve under different SOC states is obtained.
  • the charging rate corresponding to the pole potential of 0V is the charging window under the SOC state, which is recorded as C10%SOC, C20%SOC, C30%SOC, C40%SOC, C50%SOC, C60%SOC, C70%SOC, and C80%SOC.
  • the charging time T of the secondary battery from 10%SOC to 80%SOC is calculated according to the formula (60/C20%SOC+60/C30%SOC+60/C40%SOC+60/C50%SOC+60/C60%SOC+60/C70%SOC+60/C80%SOC) ⁇ 10%. The shorter the charging time T, the better the fast charging performance of the secondary battery.
  • the ambient temperature was adjusted to 25°C, the secondary battery prepared above was charged to 4.25V at 1C, then charged to 0.05C at a constant voltage, and the secondary battery was placed in a heating furnace, which was heated at 10°C/min and kept warm for 10 minutes until the secondary battery had thermal runaway, and the process was terminated. The temperature monitored by the heating furnace when the secondary battery had thermal runaway was recorded, which was the thermal runaway temperature.

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Abstract

本申请提供了一种负极极片及其制备方法、二次电池和用电装置。所述负极极片包括负极集流体和设置于负极集流体至少一个表面上的负极膜层，负极膜层包括具有朝向背离负极集流体的方向开口的浸润腔，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A1/A≤1；可选地，0.2≤A1/A≤1。本申请的负极极片在应用于二次电池时能够改善二次电池的安全性能和快充能力。

Description

负极极片及其制备方法、二次电池和用电装置 技术领域
本申请涉及电池领域，具体涉及一种负极极片及其制备方法、二次电池和用电装置。
背景技术
二次电池具有容量高、寿命长等特性，因此广泛应用于电子设备，例如手机、笔记本电脑、电瓶车、电动汽车、电动飞机、电动轮船、电动玩具汽车、电动玩具轮船、电动玩具飞机和电动工具等等。
随着电池应用范围越来越广泛，对二次电池性能的要求也逐渐严苛。为了提高二次电池的性能，通常对二次电池内的极片例如负极极片进行优化改善。然而，目前负极极片应用于二次电池时，其快速充电能力和安全性能仍较差，需要进一步改善。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种负极极片及其制备方法、二次电池和用电装置，负极极片在应用于二次电池时可以改善二次电池的快速充电能力和安全性能。
本申请的第一方面提供了一种负极极片，所述负极极片包括负极集流体和设置于负极集流体至少一个表面上的负极膜层，负极膜层包括具有朝向背离负极集流体的方向开口的浸润腔，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
由此，本申请中由于浸润腔的存在，活性离子例如锂离子在负极极片中的扩散路径变短，能够显著地改善负极膜层两侧浓差极化的问题，改善二次电池的安全性能和快充能力。
在一些实施方式中，所述第一方向与所述负极极片的长度方向具有夹角β°，0≤β<180°。可选地，0≤β≤30°或者150≤β＜180°。
在一些实施方式中，所述第一方向与所述负极极片的长度方向平行。
在一些实施方式中，所述第一方向与所述负极极片的宽度方向平行。
由此，本申请中的负极极片、正极极片以及隔离膜形成电极组件时，可以沿着负极极片的长度方向卷绕；将电极组件放入壳体所组成二次电池时，二次电池的高度 方向可以与负极极片的长度方向平行，也可以与负极极片的宽度方向平行，也可以与负极极片方向有夹角。电解液在浸润腔中可以由二次电池的底部引导至顶部，在二次电池的高度方向上电解液对电极组件的浸润较为均匀，在高度方向上活性离子的迁移速率相差不大，从而能够保证电极组件在充放电过程中性能均一，进一步改善二次电池的快充能力和安全性能。
在一些实施方式中，负极膜层在负极极片的厚度方向上的尺寸记为dμm；浸润腔在负极极片的厚度方向上的尺寸记为d 1μm；负极极片满足：0.01≤d 1/d＜1；可选地，0.2≤d 1/d≤0.8。
由此，本申请中的浸润腔在负极极片的厚度方向上的尺寸满足上述关系时，能够降低因工艺偏差带来的尺寸波动的影响，并且能够使得电解液充分浸润于负极膜层的内部，使得活性离子在负极膜层内的迁移更迅速，从而进一步降低浓差极化的风险，改善二次电池的快速充电能力和安全性能。
在一些实施方式中，浸润腔平行于第二方向的截面包括第一边缘和第二边缘，第一边缘和第二边缘沿负极极片的厚度方向彼此相对，第一边缘背离负极集流体设置，第二边缘靠近负极集流体设置；第二方向、第一方向和厚度方向两两垂直；第一边缘的尺寸记为x 1μm，20≤x 1≤5000；可选地，20≤x 1≤80；和/或第二边缘的尺寸记为x 2μm，20≤x 2≤5000；可选地，20≤x 2≤80。浸润腔满足上述范围时，能够兼顾二次电池的快充能力和安全性能等。
在一些实施方式中，0≤|x 1-x 2|≤60。浸润腔满足上述范围时，能够进一步改善二次电池的快充能力、安全性能和能量密度等。
在一些实施方式中，浸润腔平行于厚度方向的截面形状为规则多边形或不规则多边形；可选地，浸润腔平行于厚度方向的截面形状为长方形、正方形、梯形或包含弧形的多边形。浸润腔的结构形式可以根据生产需求灵活设置，浸润腔的第一边缘和第二边缘的尺寸的设置可以调控活性离子嵌入负极活性物质的速度，改善二次电池的快充能力。
在一些实施方式中，截面还包括沿第二方向彼此相对的两个侧边，两个侧边通过第二边缘连接；两个侧边中的其中一个与第二边缘构成的夹角记为θ°，0<θ≤150°。
由此，本申请实施例的浸润腔的结构形式可以根据生产需求灵活设置，浸润腔的侧边和第二边缘的夹角的设置可以调控活性离子嵌入负极活性物质的速度，改善二次电池的快充能力。
在一些实施方式中，负极膜层的孔隙率记为P％，10≤P≤40。负极膜层的孔隙率P％在上述范围时，可以改善二次电池的快充能力和能量密度。
在一些实施方式中，浸润腔设置为多个，多个浸润腔间隔设置。多个浸润腔的设置能够进一步改善活性离子在负极膜层内的液相传导速度，使得活性离子能够更迅速地嵌入负极活性物质内，改善二次电池的快充能力。
本申请的第二方面提供了一种制备负极极片的方法，所述方法包括：提供负极 集流体；于负极集流体至少一个表面上设置遮挡构件，遮挡构件包括贯穿遮挡构件的第一通孔；将负极浆料涂布于遮挡构件上，以使负极浆料经通孔流至负极集流体的表面上；固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层，负极膜层具有与第一通孔错开设置的浸润腔，负极膜层和负极集流体构成负极极片，其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请的第三方面提供了一种制备负极极片的方法，所述方法包括：提供负极集流体；于负极集流体至少一个表面上涂布负极浆料；采用压制构件设置于负极浆料上对负极浆料施加作用力，以使负极浆料具有凹部；固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层，负极膜层具有与凹部对应的浸润腔，负极膜层和负极集流体构成负极极片，其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请的第四方面提供了一种制备负极极片的方法，所述方法包括：提供负极集流体；于负极集流体至少一个表面上涂布负极浆料；固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层；在负极膜层上开设浸润腔，负极膜层和负极集流体构成负极极片，其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请第五方面还提供了一种二次电池，所述二次电池包括如本申请第一方面任一实施方式的负极极片或如本申请第二方面任一实施方式所述的方法制备得到的负极极片。
在一些实施方式中，第一方向与二次电池的高度方向具有夹角δ°，0≤δ＜180°；可选地，0≤δ≤30°或者，150≤δ＜180°。
本申请第六方面还提供了一种用电装置，包括如本申请第五方面任一实施方式的二次电池。
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例，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是本申请的负极极片的一实施方式的结构示意图。
图2是图1所示的负极极片沿I-I线作出的剖视示意图。
图3是本申请负极极片的一实施方式的结构示意图。
图4是图3所示的负极极片在II处的放大示意图。
图5是本申请二次电池的电极组件的一实施方式的示意图。
图6是本申请的二次电池的一实施方式的示意图。
图7是图6的二次电池的实施方式的分解示意图。
图8是本申请的电池模块的一实施方式的示意图。
图9是本申请的电池包的一实施方式的示意图。
图10是图9所示的电池包的实施方式的分解示意图。
图11是包含本申请的二次电池作为电源的用电装置的一实施方式的示意图。
附图未必按照实际的比例绘制。
附图标记说明如下：
X、第一方向；Y、第二方向；Z、厚度方向；
1、电池包；2、上箱体；3、下箱体；4、电池模块；
5、二次电池；51、壳体；
52、电极组件；521、负极极片；5211、负极集流体；5212、负极膜层；5213、浸润腔；5214、第一边缘；5215、第二边缘；5216、侧边
522、正极极片；523、隔离膜；
53、盖板；
6、用电装置。
具体实施方式
以下，详细说明具体公开了本申请的负极极片及其制备方法、二次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。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。
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，方法包括步骤(a)和(b)，表示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，提到方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到方法，例如，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，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
在本申请中，术语“多个”、“多种”是指两个或两种以上。
在二次电池充电过程中，对于负极极片而言通常需要经过以下电化学过程：(1)溶剂化的锂离子脱溶剂化过程(2)脱溶剂化后的锂离子穿过固态电解质膜；(3)锂离子在活性物质和固态电解质膜界面处的电荷转移反应；(4)锂离子在活性物质的固相扩散。
负极极片在成型过程中，通常需要进行冷压等工序，冷压后的负极膜层表面容易出现闭孔等问题，不利于电解液快速浸润到负极膜层靠近负极集流体的一侧，导致活性离子例如锂离子在负极膜层的两侧的浓度差异较大，即形成锂离子浓差极化问题，锂离子在负极膜层背离负极集流体的表面容易发生析锂，析出的金属锂会进一步增大锂离子进入负极活性物质内部的势垒，由此可能会进一步恶化浓差极化问题；锂离子进一步在负极膜层表面析出可能进一步形成锂枝晶，锂枝晶可能会刺破隔离膜导致正极极片和负极极片短接，引发安全风险。并且，由于活性离子的液相传导速率较慢，导致二次电池的快速充电能力较差。
鉴于此，发明人从改善负极极片的结构出发，以期获得能够兼顾快速充电能力和安全性能的负极极片。接下来对负极极片的具体结构进行说明。
负极极片
第一方面，本申请提出了一种负极极片。
如图1至图4所示，所述负极极片521包括负极集流体5211和设置于负极集流体5211至少一个表面上的负极膜层5212，负极膜层5212包括具有朝向背离负极集流体5211的方向开口的浸润腔5213，浸润腔5213沿第一方向延伸，负极膜层5212沿第一方向的尺寸记为Aμm，浸润腔5213沿第一方向的尺寸记为A 1μm，0.1≤A 1/A≤1。
作为示例，负极集流体5211具有在其自身厚度方向相对的两个表面，负极膜层5212设置在负极集流体5211相对的两个表面中的任意一者或两者上。
发明人通过大量研究发现，浸润腔5213的设计参数对二次电池的快速充电能力和安全性能均具有一定程度的影响，尤其是0.1≤A 1/A≤1时，由于浸润腔的存在，活 性离子例如锂离子在负极极片中的扩散路径变短，能够显著地改善负极膜层两侧浓差极化的问题，改善二次电池的安全性能和快充能力。
在本申请中，浸润腔5213沿第一方向延伸，是指浸润腔5213可以类似于直线型的延伸趋势，也可以指浸润腔5213的整体趋势为近似沿第一方向延伸，例如浸润腔5213可以包含弧形段等。第一方向可以与负极极片的长度方向具有夹角β°，0≤β<180°。可选地，0≤β≤30°或者150≤β＜180°。当β＝0时，表示第一方向与负极极片的长度方向平行，或者近似平行。当β＞0时，表示第一方向与负极极片的方向具有一定的夹角。当β＝90°时，表示第一方向与负极极片的宽度方向平行，或者近似平行。
平行于负极极片521的宽度方向或长度方向，或者其它方向。图1中示出的X方向表示第一方向，该第一方向与负极极片521的宽度方向平行。
A 1和A的数值可采用软尺或者扫面电子显微镜测量得到。
活性离子在负极膜层5212中的液相传导包括两种途径，一种途径是：活性离子能够经负极膜层5212的表面向负极膜层5212内部扩散；另一种途径是：由于浸润腔5213中存储有电解液，此时相当于电解液浸润于负极膜层5212内部，该部分电解液中的活性离子能够直接由浸润腔5213向负极膜层5212的内部迁移，并且迁移至负极活性物质中的路径相对较短，能够显著改善负极膜层5212两侧浓差极化的问题，改善二次电池的安全性能和快充能力。可选地，0.2≤A 1/A≤1。示例性地，A 1/A可以为0.1、0.2、0.5、0.6、0.8、0.9、1或是上述任意两个数值组成的范围。
结合图5至图7，负极极片521制作为成品时，其呈现为片状结构，具有预设的长度、高度和宽度。负极极片521、正极极片522以及隔离膜523形成电极组件52时，可以沿着负极极片521的长度方向卷绕；将电极组件52放入壳体51所组成二次电池5时，二次电池5的高度方向可以与负极极片521的长度方向平行，也可以与负极极片521的宽度方向平行。图7中示出的X方向表示二次电池5的高度方向与负极极片521的宽度方向平行。
由于重力作用会导致二次电池5内的电解液积聚于底部，导致电解液对位于底部的电极组件52的浸润较为充分，对远离底部的电极组件52的浸润较差，电解液对电极组件52整体的浸润性能不均一；在二次电池5充放电循环过程中，活性离子例如锂离子在远离底部的电极组件52中进行迁移时，可能由于缺少电解液导致锂离子无法嵌入负极极片521中，从而使得锂离子在负极极片521表面析出。
进一步地，浸润腔5213的延伸方向(第一方向)与所述二次电池5的高度方向可以具有夹角δ°，0≤δ＜180°。在浸润腔5213的延伸方向与二次电池5的高度方向的夹角在一定范围时，能够有效地改善活性离子例如锂离子在液相中的迁移速率，有利于提升二次电池5的快速充电性能。可选地，0≤δ≤30°或者150≤δ＜180°；进一步可选地，所述浸润腔5213沿所述二次电池5的高度方向延伸，即第一方向与二次电池5的高度方向平行，平行可以是指绝对平行或近似平行。示例性地，δ°可以为0、5°、12°、15°、25°、30°、150°、155°、160°、170°、175°、179°或是上述任意两个数值组成的范围内。
浸润腔5213的延伸方向与二次电池5的高度方向平行；在此情况下，可能是负极极片521的长度方向与二次电池的高度方向平行，也可能是负极极片521的宽度方向与二次电池5的高度方向平行。图7中示出的X方向表示二次电池5的高度方向与负极极片521的宽度方向平行。
电解液在浸润腔5213中可以由二次电池5的底部引导至顶部，在二次电池5的高度方向上电解液对电极组件52的浸润较为均匀，在高度方向上活性离子的迁移速率相差不大，从而能够保证电极组件52在充放电过程中性能均一，进一步改善二次电池5的快充能力和安全性能。
当然，浸润腔5213的延伸方向除了可以平行于二次电池5的高度方向，也可以与高度方向相交。在此情况下，浸润腔5213仍具有将位于底部的电解液引导至顶部的能力。
发明人进一步研究发现，除了浸润腔5213的延伸长度和延伸方向对二次电池的快速充电能力和安全性能具有影响，浸润腔5213的其它尺寸参数如果能够满足以下条件中的一者或多者，将进一步改善二次电池5的性能。
在一些实施方式中，负极膜层5212在负极极片521的厚度方向上的尺寸记为dμm；浸润腔5213在负极极片521的厚度方向上的尺寸记为d 1μm；负极极片521满足：0.01≤d 1/d＜1。可选地，0.2≤d 1/d≤0.8。图4中示出了d 1和d，图3和图4示出的Z方向表示厚度方向。
负极膜层5212在厚度方向上的尺寸d即负极膜层5212的厚度，其为本领域公知的含义，可以采用本领域公知的设备或方法测试得到，具体地，可采用万分尺测量得到，例如可使用型号为Mitutoyo293-100、精度为0.1μm的万分尺测量得到。本发明的负极膜层5212厚度是指经冷压压实后并用于组装电池的负极极片521中的负极膜片的厚度。
浸润腔5213在厚度方向的尺寸，可以采用扫描电子显微镜SEM获取厚度数据。
研究发现，浸润腔5213在负极极片521的厚度方向上的尺寸满足上述关系时，能够降低因工艺偏差带来的尺寸波动的影响，并且能够使得电解液充分浸润于负极膜层5212的内部，使得活性离子在负极膜层5212内的迁移更迅速，从而进一步降低浓差极化的风险，改善二次电池的快速充电能力和安全性能。示例性地，d 1/d可以为0.01、0.1、0.2、0.3、0.5、0.6、0.7、0.8、0.9、0.95或0.99；或是上述数据所组成的范围。
d 1/d＝1表示浸润腔5213完全贯通负极膜层5212，电解液可以通过浸润腔5213直接与负极集流体5211相接触，活性离子能够直接在负极集流体5211的表面上得电子。
在一些实施方式中，浸润腔5213平行于第二方向的截面包括第一边缘5214和第二边缘5215，第一边缘5214和第二边缘5215沿厚度方向彼此相对，第一边缘5214背离负极集流体5211设置，第二边缘5215靠近负极集流体5211设置；第二方向、第一方向和厚度方向两两垂直。图3和图4示出的Z方向表示厚度方向，Y方向表示第 二方向。
浸润腔5213的第一边缘5214的尺寸和第二边缘5215的尺寸是本领域公知的含义，其可以采用本领域公知的设备和方法测试得到，具体地可以采用扫描电子显微镜SEM获取孔截面进行表征。
浸润腔5213的第一边缘5214的尺寸记为x 1μm，第一边缘5214的尺寸较小时，由浸润腔5213迁移至负极膜层5212内的活性离子相对较少，其改善活性离子迁移的能力相对较小；第一边缘5214的尺寸较大时，负极膜层5212整体的克容量较小，二次电池的能量密度较小。浸润腔5213的第一边缘5214的尺寸满足：20≤x 1≤100时，进一步满足20≤x 1≤80时，能够兼顾二次电池的快充能力和安全性能等。
浸润腔5213的第二边缘5215的尺寸记为x 2μm，第二边缘5215的尺寸较小时，由浸润腔5213迁移至负极膜层5212内的活性离子相对较小，其改善活性离子迁移的能力相对较小；第二边缘5215的尺寸较大时，负极膜层5212整体的克容量较小，二次电池的能量密度较小。浸润腔5213的第一边缘5214的尺寸满足：20≤x 2≤5000时，进一步满足20≤x 2≤80时，能够兼顾二次电池的快充能力、安全性能和能量密度等。
进一步地，0≤|x 1-x 2|≤60。
浸润腔5213的结构形式可以根据生产需求灵活设置，浸润腔5213的第一边缘5214和第二边缘5215的尺寸的设置可以调控活性离子嵌入负极活性物质的速度，改善二次电池的快充能力。
x 1-x 2＝0时，表示浸润腔5213的截面可以为规则的四边形结构(例如长方形、正方形等)，x 1-x 2＞0或者x 1-x 2＜0时，表示浸润腔5213的截面可以为梯形等结构；当然浸润腔5213的截面除了包含上述四边形结构，还可以为五边形、六边形、七边形等规则多边形或不规则多边形；不规则的多边形可以为边长不相等的多边形，也可以为包含弧形的多边形结构等。
在一些实施方式中，浸润腔5213的截面还可以包括沿第二方向彼此相对的两个侧边5216，两个侧边5216通过第二边缘5215连接，两个侧边5216中的其中一个与第二边缘5215构成的夹角记为θ°，0<θ≤150。
浸润腔5213的侧边5216与第二边缘5215构成的夹角是本领域公知的含义，其可以采用本领域公知的设备和方法测试得到，具体地可以采用扫描电子显微镜SEM获取孔截面进行表征，确定夹角数据。
浸润腔5213的结构形式可以根据生产需求灵活设置，浸润腔5213的侧边5216和第二边缘5215的夹角的设置可以调控活性离子嵌入负极活性物质的速度，改善二次电池的快充能力。
在一些实施方式中，负极膜层5212的孔隙率记为P％，10≤P≤40。
负极膜层5212的孔隙率P％为本领域公知的含义，可以采用本领域已知的设备或方法测试，具体地，可以通过气体置换法得到，孔隙率P＝(V 1-V 2)/V 1×100％，V 1表示表观体积，V 2表示真实体积。
负极膜层5212的孔隙率P％会影响活性离子在负极膜层5212孔道内部的液相传导能力，孔隙率P％越高，负极膜层5212内部的孔道结构越多，负极极片521的电解液浸润性能越好，活性离子在负极膜层5212内部的液相传导速度越快，在二次电池快速充电时，活性离子更容易嵌入负极活性物质内，同时还可以降低活性离子在负极膜层5212表面还原析出而长出锂枝晶的风险，二次电池反复充放电过程只能够不可逆容量损失较小，二次电池的循环寿命增加；但是随着孔隙率P％的进一步增加，二次电池的能量密度的损失也会越来越严重。负极膜层5212的孔隙率P％在上述范围时，可以改善二次电池的快充能力和能量密度。示例性地，负极膜层5212的孔隙率可以为10％、12％、15％、18％、20％、25％、30％、35％、40％或是上述任意两个数值组成的范围。
在一些实施方式中，浸润腔5213设置为多个，多个浸润腔5213间隔设置。
多个浸润腔5213的设置能够进一步改善活性离子在负极膜层5212内的液相传导速度，使得活性离子能够更迅速地嵌入负极活性物质内，改善二次电池的快充能力。
在一些实施方式中，负极集流体5211可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、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)、聚乙烯(PE)等的基材)上而形成。
在一些实施方式中，负极膜层5212包括负极活性物质。负极活性物质可采用本领域公知的用于电池的负极活性物质。作为示例，负极活性物质可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性物质的传统材料。这些负极活性物质可以仅单独使用一种，也可以将两种以上组合使用。
在一些实施方式中，负极膜层5212还可选地包括负极粘结剂。负极粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。
在一些实施方式中，负极膜层5212还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。
在一些实施方式中，负极膜层5212还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。
负极极片521可以采用多种方法制备形成，接下来对负极极片521的制备进行说明。
制备负极极片的方法
第二方面，本申请提出了一种制备负极极片的方法。
所述方法包括：
S210，提供负极集流体；
S220，于负极集流体至少一个表面上设置遮挡构件，遮挡构件包括贯穿遮挡构件的第一通孔；
S230，将负极浆料涂布于遮挡构件上，以使负极浆料经第一通孔流至负极集流体的表面上；
S240，固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层，负极膜层具有与第一通孔错开设置的浸润腔，负极膜层和负极集流体构成负极极片，
其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请的负极浆料固化前进行造孔，即负极浆料具有一定的流动性，在将负极浆料涂布于遮挡构件上时，负极浆料将会自动向第一通孔处流动，而遮挡构件的实体部分将会起到遮挡作用，为后续的浸润腔的制备提供有利条件；对遮挡构件进行加热，使得遮挡构件周围的浆料凝固，降低由于负极浆料流动导致浸润腔被填埋的风险，保证浸润腔的有效形成。
第三方面，本申请还提出了一种制备负极极片的方法。
所述方法包括：
S310，提供负极集流体；
S320，于负极集流体至少一个表面上涂布负极浆料；
S330，采用压制构件设置于负极浆料上对负极浆料施加作用力，以使负极浆料具有凹部；
S340，固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层，负极膜层具有与凹部对应的浸润腔，负极膜层和负极集流体构成负极极片，
其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请的负极浆料固化前进行造孔，即负极浆料具有一定的流动性，采用压制构件在负极浆料上设置凹部时，其所需的作用力相对较小，基本不会造成负极浆料的损失。
第四方面，本申请还提出了一种制备负极极片的方法。
所述方法包括：
S410，提供负极集流体；
S420，于负极集流体至少一个表面上涂布负极浆料；
S430，固化负极浆料，以使负极浆料在负极集流体的表面形成负极膜层；
S440，在负极膜层上开设浸润腔，负极膜层和负极集流体构成负极极片，
其中，浸润腔沿第一方向延伸；负极膜层沿第一方向的尺寸记为Aμm；浸润腔沿第一方向的尺寸记为A 1μm，负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
本申请在负极浆料固化后造孔，可以采用辊刀等设备对固化后的负极极片进行造孔。
二次电池
第五方面，本申请提出了一种二次电池5。
通常情况下，所述二次电池包括正极极片522、负极极片521、电解质和隔离膜523。在二次电池5充放电过程中，活性离子在正极极片522和负极极片521之间往返嵌入和脱出。电解质在正极极片522和负极极片521之间起到传导离子的作用。隔离膜523设置在正极极片522和负极极片521之间，主要起到防止正负极短路的作用，同时可以使离子通过。本申请的负极极片521可以采用本申请第一方面任一实施方式的负极极片521或者本申请第二方面至第四方面任一所述的方法制备得到的负极极片521。
[正极极片]
在一些实施方式中，正极极片522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。例如，正极集流体具有在自身厚度方向相对的两个表面，正极膜层设置于正极集流体的两个相对表面中的任意一者或两者上。
所述正极膜层包括正极活性物质，所述正极活性物质可采用本领域公知的用于二次电池的正极活性物质。作为示例，正极活性物质可包括以下材料中的至少一种：层状结构正极活性物质(例如三元、镍酸锂/钠、钴酸锂/钠、锰酸锂/钠、富锂/钠层状和岩盐相层状等材料)、橄榄石型磷酸盐活性物质、尖晶石结构的正极活性物质(例如尖晶石锰酸锂、尖晶石镍锰酸锂、富锂的尖晶石锰酸锂和镍锰酸锂等)。
示例性地，层状结构正极活性物质的通式为：Li xA yNi aCo bMn cM (1-a-b-c)Y z，其中，0≤x≤2.1，0≤y≤2.1，且0.9≤x+y≤2.1；0≤a≤1，0≤b≤1，0≤c≤1，且0.1≤a+b+c≤1；1.8≤z≤3.5；A选自Na、K、Mg中的一种或几种；M选自B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Fe、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；Y选自O、F中的一种或几种。可选地，y＝0。具体地，层状结构正极活性物质可以包括钴酸锂LCO、镍酸锂LNO、锰酸锂LMO、LiNi 1/3Co 1/3Mn 1/3O 2(NCM333)、LiNi 0.8Co 0.1Mn 0.1O 2(NCM811)和LiNi 0.5Co 0.2Mn 0.3O 2(NCM523)中的一种或多种。
示例性地，橄榄石型磷酸盐活性物质的通式为：Li xA yMe aM bP 1-cX cY z，其中，0≤x≤1.3，0≤y≤1.3，且0.9≤x+y≤1.3；0.9≤a≤1.5，0≤b≤0.5，且0.9≤a+b≤1.5；0≤c≤0.5；3≤z≤5；A选自Na、K、Mg中的一种或几种；Me选自Mn、Fe、Co、Ni中的一种或几种；M选自B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；X选自S、Si、Cl、B、C、N中的一种或几种；Y选自O、F中的一种或几种。具体地，橄榄石型磷酸盐活性物质包括LiFePO 4、LiMnPO 4、LiNiPO 4、和LiCoPO 4中的一种或多种。
示例性地，尖晶石结构的正极活性物质的通式为：Li xA yMn aM 2-aY z，其中，0≤x≤2，0≤y≤1，且0.9≤x+y≤2；0.5≤a≤2；3≤z≤5；A选自Na、K、Mg中的一种或几种； M选自Ni、Co、B、Mg、Al、Si、P、S、Ca、Sc、Ti、V、Cr、Fe、Cu、Zn、Sr、Y、Zr、Nb、Mo、Cd、Sn、Sb、Te、Ba、Ta、W、Yb、La、Ce中的一种或几种；Y选自O、F中的一种或几种。具体地，尖晶石结构的正极活性物质包括LiMn 2O 4、LiNi 0.5Mn 1.5O 4、LiCr 0.3Mn 1.7O 4、Li 1.1Al 0.1Mn 1.9O 4、Li 2Mn 2O 4和Li 1.5Mn 2O 4中的一种或多种。
在一些实施方式中，正极膜层还可选地包括正极导电剂。本申请对正极导电剂的种类没有特别的限制，作为示例，正极导电剂包括选自超导碳、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的组合。在一些实施方式中，基于正极膜层的总质量，正极导电剂的质量百分含量在5％以下。
在一些实施方式中，正极膜层还可选地包括正极粘结剂。本申请对正极粘结剂的种类没有特别的限制，作为示例，正极粘结剂可包括选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-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的组合。在一些实施方式中，基于正极膜层的总质量，正极粘结剂的质量百分含量在5％以下。
在一些实施方式中，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，可采用铝箔或铝合金箔。复合集流体可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，金属材料可包括选自铝、铝合金、镍、镍合金、钛、钛合金、银和银合金中的一种或多种的组合，高分子材料基层可包括选自聚丙烯(PP)、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(PE)中的一种或多种的组合。
正极膜层通常是将正极浆料涂布在正极集流体上，经干燥、冷压而成的。正极浆料通常是将正极活性物质、可选的导电剂、可选的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。
[电解质]
电解质在正极极片522和负极极片521之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
作为示例，锂盐可包括选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)和四氟草酸磷酸锂(LiTFOP)中的一种或多种的组合。
作为示例，有机溶剂可包括选自碳酸乙烯酯(EC)、碳酸亚丙酯(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)、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)和二乙砜(ESE)中的一种或多种的组合。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、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、改善电池高温或低温性能的添加剂等。
[隔离膜]
在一些实施方式中，二次电池中还包括隔离膜523。本申请对隔离膜523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隔离膜。
在一些实施方式中，隔离膜523的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，正极极片522、负极极片521和隔离膜523可通过卷绕工艺或叠片工艺制成电极组件52。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图6是作为一个示例的方形结构的二次电池5。
在一些实施例中，如图6和图7所示，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用于盖设开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于容纳腔。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，可根据需求来调节。
本申请的二次电池5的制备方法是公知的。在一些实施例中，可将正极极片522、隔离膜523、负极极片521和电解液组装形成二次电池5。作为示例，可将极极片522、隔离膜523、负极极片521经卷绕工艺或叠片工艺形成电极组件52，将电极组件52置于外包装中，烘干后注入电解液，经过真空封装、静置、化成、整形等工序，得到二次电池5。
在本申请的一些实施例中，根据本申请的二次电池5可以组装成电池模块，电池模块所含二次电池5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。
图8是作为一个示例的电池模块4的示意图。如图8所示，在电池模块4中，多个二次电池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二次电池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，多个二次电池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。
图9和图10是作为一个示例的电池包1的示意图。如图9和图10所示，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块4。电池箱包括上箱体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电池箱中。
用电装置
第六方面，本申请提供一种用电装置，用电装置包括本申请的二次电池、电池模块和电池包中的至少一种。二次电池、电池模块和电池包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、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二次电池、电池模块或电池包。
图11是作为一个示例的用电装置的示意图。该用电装置6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1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，可以采用二次电池作为电源。
实施例
以下，说明本申请的实施方式。下面描述的实施方式是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施方式中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
实施例1-1
1、正极极片的制备
采用厚度为12μm的铝箔作为正极集流体。
将正极活性物质、导电剂炭黑、粘结剂聚偏氟乙烯(PVDF)按重量比97.5:1.4:1.1在适量的溶剂NMP中充分搅拌混合，形成均匀的正极浆料；将正极浆料均匀涂覆于正极集流体铝箔的表面上，经干燥、冷压后，得到正极极片。
2、负极极片的制备
采用厚度为8μm的铜箔作为负极集流体。
将负极活性物质人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按重量比96.8:0.7:1.3:1.2在适量的溶剂去离子水中充分搅拌混合，形成均匀的负极浆料。
将遮挡构件例如涂布垫片设置于负极集流体上，负极浆料经涂布垫片的第一通孔处流至负极集流体的表面，通过对涂布垫片加热，负极浆料固化为负极膜层，负极膜层保护浸润腔，经干燥、冷压后，负极膜层和负极集流体形成负极极片。
3、隔离膜
采用多孔聚乙烯(PE)膜作为隔离膜。
4、电解液的制备
在含水量小于10ppm的环境下，将非水有机溶剂碳酸乙烯酯EC、碳酸二乙酯DMC按照体积比1:1进行混合得到电解液溶剂，随后将锂盐和混合后的溶剂混合，配置成锂盐浓度为1mol/L的电解液。
5、二次电池的制备
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正极极片和负极极片之间起到隔离作用，然后卷绕得到电极组件；将电极组件置于外包装壳中，干燥后注入电解液，经过真空封装、静置、化成、整形等工序，得到锂离子电池。负极极片中浸润腔的延伸方向与锂离子电池的高度方向平行。
实施例1-2至实施例1-4
实施例1-2至实施例1-4按照实施例1-1类似的方法制备锂离子电池，与实施例1-1不同的是，实施例1-2至实施例1-4调整了浸润腔在负极极片厚度方向的尺寸d 1μm。
实施例2-1至实施例2-4
实施例2-1至实施例2-4按照实施例1-3类似的方法制备锂离子电池，与实施例1-3不同的是，实施例2-1至实施例2-4调整了浸润腔在第一方向的尺寸A 1μm。
实施例3-1至实施例3-3
实施例3-1至实施例3-3按照实施例1-3类似的方法制备锂离子电池，与实施例1-3不同的是，实施例3-1至实施例3-3调整了浸润腔的第二边缘的尺寸x 2μm。
实施例4-1和实施例4-2
实施例4-1和实施例4-2按照实施例1-3类似的方法制备锂离子电池，与实施例1-3不同的是，实施例4-1和实施例4-2调整了浸润腔的侧边与第二边缘所形成的夹角θ°。
实施例5-1至实施例5-3
实施例5-1至实施例5-3按照实施例1-3类似的方法制备锂离子电池，与实施例1-3不同的是，实施例5-1至实施例5-3至少调整了浸润腔的延伸方向与锂离子电池高度方向的夹角δ°。
对比例1
对比例1按照实施例1类似的方法制备锂离子电池，与实施例1不同的是，对比例1调整了负极极片的制备工艺；具体地：采用厚度为6μm的铜箔作为负极集流体。将负极活性物质人造石墨、导电剂碳黑、粘结剂丁苯橡胶(SBR)、增稠剂羟甲基纤维素钠(CMC)按重量比96.8:0.7:1.3:1.2在适量的溶剂去离子水中充分搅拌混合，形 成均匀的负极浆料，将负极浆料涂布于负极集流体上；负极浆料经干燥、冷压后形成负极膜层即为负极极片。对比例1的孔径为1μm，其孔隙率为20％，对比例1的孔隙率来源于负极膜层在干燥冷压过程中形成的孔隙结构。
实施例和对比例的相关参数如表1所示。
表1
Figure PCTCN2022123492-appb-000001
由表1可知，相较于对比例1，本申请实施例通过在负极膜层中造孔，使得锂离子的液相传输速率更快，有利于提升其动力学性能，其充电速度较快，有利于提升其快速充电能力。
本申请实施例1-1至实施例4-2在负极膜层上开设浸润腔，且浸润腔沿二次电池的高度方向设置可以通过浸润腔吸取电解液，使得电解液增强对负极膜层的浸润效果，有利于锂离子的快速迁移，改善快速充电能力，并且还能够减少锂离子的局部析出，提高安全性能。
实施例5-1至实施例5-3调整了浸润腔的延伸方向，在浸润腔的延伸方向与锂离子的高度方向具有大于0°的夹角时，也能够在一定程度上改善锂离子的液相传输速率，有利于改善锂离子的快速充电能力。
测试部分
1、二次电快速充电性能测试
在25℃下，将上述制备的二次电池以0.33C恒流充电至充电截止电压4.4V，之后恒压充电至电流为0.05C，静置5min，再以0.33C恒流放电至放电截止电压2.8V，记录其实际容量为C0。
然后将二次电池依次以0.5C0、1C0、1.5C0、2C0、2.5C0、3C0、3.5C0、4C0、4.5C0恒流充电至全电池充电截止电压4.4V或者0V负极截止电位(以先达到者为准)，每次充电完成后需以1C0放电至全电池放电截止电压2.8V，记录不同充电倍率下充电至10％、20％、30％……80％SOC(State of Charge，荷电状态)时所对应的负极电位，绘制出不同SOC态下的倍率-负极电位曲线，线性拟合后得出不同SOC态下负极电位为0V时所对应的充电倍率，该充电倍率即为该SOC态下的充电窗口，分别记为C10％SOC、C20％SOC、C30％SOC、C40％SOC、C50％SOC、C60％SOC、C70％SOC、C80％SOC，根据公式(60/C20％SOC+60/C30％SOC+60/C40％SOC+60/C50％SOC+60/C60％SOC+60/C70％SOC+60/C80％SOC)×10％计算得到该二次电池从10％SOC充电至80％SOC的充电时间T。充电时间T越短，则代表二次电池的快速充电性能越优秀。
2、采用二次电池的热失控温度评述其安全性能，热失控温度的测试
环境温度调节为25℃，将上述制备的二次电池以1C充电到4.25V，随后恒压充电到0.05C，将二次电池放到加热炉中，加热炉按照10℃/min升温，保温10min，直至二次电池出现热失控，流程截止。记录二次电池热失控时加热炉监控的温度，即为热失控温度。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (15)

  1. 一种负极极片，包括负极集流体和设置于负极集流体至少一个表面上的负极膜层，所述负极膜层包括具有朝向背离所述负极集流体的方向开口的浸润腔，所述浸润腔沿第一方向延伸；
    所述负极膜层沿所述第一方向的尺寸记为Aμm；
    所述浸润腔沿所述第一方向的尺寸记为A 1μm，
    所述负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
  2. 根据权利要求1所述的负极极片，其中，所述第一方向与所述负极极片的长度方向具有夹角β°，0≤β<180°；
    可选地，所述第一方向与所述负极极片的长度方向平行；或
    所述第一方向与所述负极极片的宽度方向平行。
  3. 根据权利要求1或2所述的负极极片，其中，
    所述负极膜层在所述负极极片的厚度方向上的尺寸记为dμm；
    所述浸润腔在所述负极极片的厚度方向上的尺寸记为d 1μm；
    所述负极极片满足：0.01≤d 1/d＜1；可选地，0.2≤d 1/d≤0.8。
  4. 根据权利要求1至3中任一项所述的负极极片，其中，
    所述浸润腔平行于第二方向的截面包括第一边缘和第二边缘，所述第一边缘和所述第二边缘沿所述负极极片的厚度方向彼此相对，所述第一边缘背离所述负极集流体设置，所述第二边缘靠近所述负极集流体设置；所述第二方向、所述第一方向和所述厚度方向两两垂直；
    所述第一边缘的尺寸记为x 1μm，20≤x 1≤5000；可选地，20≤x 1≤80；和/或
    所述第二边缘的尺寸记为x 2μm，20≤x 2≤5000；可选地，20≤x 2≤80。
  5. 根据权利要求4所述的负极极片，其中，0≤|x 1-x 2|≤60。
  6. 根据权利要求4或5所述的负极极片，其中，所述浸润腔平行于所述厚度方向的截面形状为规则多边形或不规则多边形；
    可选地，所述浸润腔平行于所述厚度方向的截面形状为长方形、正方形、梯形或包含弧形的多边形。
  7. 根据权利要求4至6中任一项所述的负极极片，其中，
    所述截面还包括沿所述第二方向彼此相对的两个侧边，两个所述侧边通过所述第二边缘连接；
    两个所述侧边中的其中一个与所述第二边缘构成的夹角记为θ°，0<θ≤150。
  8. 根据权利要求1至7中任一项所述的负极极片，其中，
    所述负极膜层的孔隙率记为P％，10≤P≤40。
  9. 根据权利要求1至8中任一项所述的负极极片，其中，
    所述浸润腔设置为多个，多个浸润腔间隔设置。
  10. 一种制备负极极片的方法，包括：
    提供负极集流体；
    于所述负极集流体至少一个表面上设置遮挡构件，所述遮挡构件包括贯穿所述遮挡构件的第一通孔；
    将负极浆料涂布于所述遮挡构件上，以使所述负极浆料经所述通孔流至所述负极集流体的表面上；
    固化所述负极浆料，以使所述负极浆料在所述负极集流体的表面形成负极膜层，所述负极膜层具有与第一通孔错开设置的浸润腔，所述负极膜层和所述负极集流体构成所述负极极片，
    其中，所述浸润腔沿第一方向延伸；
    所述负极膜层沿所述第一方向的尺寸记为Aμm；
    所述浸润腔沿所述第一方向的尺寸记为A 1μm，
    所述负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
  11. 一种制备负极极片的方法，包括：
    提供负极集流体；
    于所述负极集流体至少一个表面上涂布负极浆料；
    采用压制构件设置于所述负极浆料上对所述负极浆料施加作用力，以使所述负极浆料具有凹部；
    固化所述负极浆料，以使所述负极浆料在所述负极集流体的表面形成负极膜层，所述负极膜层具有与所述凹部对应的浸润腔，所述负极膜层和所述负极集流体构成所述负极极片，
    其中，所述浸润腔沿第一方向延伸；
    所述负极膜层沿所述第一方向的尺寸记为Aμm；
    所述浸润腔沿所述第一方向的尺寸记为A 1μm，
    所述负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
  12. 一种制备负极极片的方法，包括：
    提供负极集流体；
    于所述负极集流体至少一个表面上涂布负极浆料；
    固化所述负极浆料，以使所述负极浆料在所述负极集流体的表面形成负极膜层；
    在所述负极膜层上开设浸润腔，所述负极膜层和所述负极集流体构成所述负极极片，
    其中，所述浸润腔沿第一方向延伸；
    所述负极膜层沿所述第一方向的尺寸记为Aμm；
    所述浸润腔沿所述第一方向的尺寸记为A 1μm，
    所述负极极片满足：0.1≤A 1/A≤1；可选地，0.2≤A 1/A≤1。
  13. 一种二次电池，包括根据权利要求1至9中任一项所述的负极极片或根据权利要求10至12中任一项所述的方法制备得到的负极极片。
  14. 根据权利要求13所述的二次电池，其中，
    所述第一方向与所述二次电池的高度方向具有夹角δ°，0≤δ＜180°；
    可选地，0≤δ≤30°或者150≤δ＜180°；
    进一步可选地，所述浸润腔沿所述二次电池的高度方向延伸。
  15. 一种用电装置，包括根据权利要求14所述的二次电池。
PCT/CN2022/123492 2022-09-30 2022-09-30 负极极片及其制备方法、二次电池和用电装置 WO2024065764A1 (zh)

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Citations (5)

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JPH11154508A (ja) * 1997-11-19 1999-06-08 Toshiba Corp 非水電解液電池
JP2001176558A (ja) * 1999-12-20 2001-06-29 Toshiba Corp 非水電解液二次電池
JP2003168421A (ja) * 2001-12-03 2003-06-13 Japan Storage Battery Co Ltd 非水電解質二次電池
JP2004158441A (ja) * 2002-10-15 2004-06-03 Toshiba Corp 非水電解質二次電池
CN207732007U (zh) * 2017-10-23 2018-08-14 宁德新能源科技有限公司 负极极片以及锂离子电池

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JP2007311328A (ja) * 2006-04-18 2007-11-29 Hitachi Maxell Ltd 非水電解液電池
JP2013134977A (ja) * 2011-12-27 2013-07-08 Toyota Industries Corp 電極、二次電池、電極の製造方法及び車両
CN114709358B (zh) * 2022-03-22 2023-07-07 湖北亿纬动力有限公司 浆料涂布方法及电极极片、锂离子电池

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JPH11154508A (ja) * 1997-11-19 1999-06-08 Toshiba Corp 非水電解液電池
JP2001176558A (ja) * 1999-12-20 2001-06-29 Toshiba Corp 非水電解液二次電池
JP2003168421A (ja) * 2001-12-03 2003-06-13 Japan Storage Battery Co Ltd 非水電解質二次電池
JP2004158441A (ja) * 2002-10-15 2004-06-03 Toshiba Corp 非水電解質二次電池
CN207732007U (zh) * 2017-10-23 2018-08-14 宁德新能源科技有限公司 负极极片以及锂离子电池

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