WO2021023010A1 - 拼接成型锂带、其制备方法、及其相关的负极极片、电芯、锂离子电池、电池模块、电池包和装置 - Google Patents

拼接成型锂带、其制备方法、及其相关的负极极片、电芯、锂离子电池、电池模块、电池包和装置 Download PDF

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WO2021023010A1
WO2021023010A1 PCT/CN2020/103483 CN2020103483W WO2021023010A1 WO 2021023010 A1 WO2021023010 A1 WO 2021023010A1 CN 2020103483 W CN2020103483 W CN 2020103483W WO 2021023010 A1 WO2021023010 A1 WO 2021023010A1
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Prior art keywords
lithium
spliced
belt
thickness
lithium belt
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PCT/CN2020/103483
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English (en)
French (fr)
Inventor
谢斌
陈仕通
龚志杰
Original Assignee
宁德时代新能源科技股份有限公司
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to EP20849466.6A priority Critical patent/EP3883025B1/en
Publication of WO2021023010A1 publication Critical patent/WO2021023010A1/zh
Priority to US17/345,134 priority patent/US11223050B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/661—Metal or alloys, e.g. alloy coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D39/00—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders
    • B21D39/03—Application of procedures in order to connect objects or parts, e.g. coating with sheet metal otherwise than by plating; Tube expanders of sheet metal otherwise than by folding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/75—Wires, rods or strips
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • 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 belongs to the technical field of energy storage devices, and specifically relates to a spliced lithium belt, a preparation method thereof, and related negative pole pieces, batteries, lithium ion batteries, battery modules, battery packs and devices.
  • the anode also known as the negative electrode
  • the anode pre-lithiation schemes uses metallic lithium tape.
  • the lithium metal tape is rolled to obtain a pre-filled lithium lithium foil, the lithium foil is in contact with or laminated with the negative electrode film layer, and the negative electrode active material is prelithiated by the metal lithium foil under the action of the potential difference.
  • the currently commonly used lithium ribbons are small in width, which cannot well meet the requirements for prelithiation of wide electrodes. Therefore, there is an urgent need to develop a wide-width lithium belt to meet market demand.
  • TD Transverse Direction
  • Such a lithium belt is prone to accumulation of lithium belts in the production process of pre-supplementing lithium lithium foil, which is not conducive to continuous production, and seriously affects production efficiency and yield; at the same time, the obtained lithium foil is used for negative electrode pre-replenishing lithium, which will lead to negative electrode
  • the uniformity of the pre-inserted lithium deteriorates, which in turn affects the cycle performance of the battery.
  • the inventor has conducted a lot of research and has cleverly discovered that a wide-width lithium belt with good thickness consistency can be obtained by splicing and forming two or more narrow-width lithium belts as the basic lithium belt.
  • the present application provides a spliced and formed lithium belt, which is formed by splicing and forming two or more basic lithium belts; wherein,
  • the thickness fluctuation of the basic lithium belt is less than 5%
  • the spliced lithium belt has spliced areas and non-spliced areas alternately distributed along the splicing direction.
  • the maximum thickness H of the spliced area and the minimum thickness L of the non-spliced area satisfy:
  • this application adopts the splicing method of the basic lithium belt, and controls the thickness fluctuation of the basic lithium belt and the thickness relationship between the spliced area and the non-spliced area within a specific range. Large width and good thickness consistency.
  • the spliced and formed lithium belt can be used to prepare a pre-filled lithium negative pole piece with a larger width, and the negative pole piece can obtain higher pre-insertion lithium uniformity. Therefore, the lithium ion battery adopting the negative pole piece can simultaneously obtain higher energy density and cycle performance.
  • the splicing area may include a body area and a transition area, and the transition area of each splicing area is adjacent to the non-splicing area, and each of the body areas
  • the width is 0.1mm ⁇ 3.5mm, optional 1mm ⁇ 3mm. The proper width of each body area can make the spliced lithium belt have better thickness consistency, while also having higher splicing strength and mechanical properties.
  • the splicing area may include two protruding portions opposite to each other in the thickness direction of the spliced lithium belt, and the two protruding portions protrude from the
  • the two surfaces of the non-splicing area in the thickness direction, and the cross section of each protrusion in the thickness direction is trapezoidal or trapezoid-like, and the bottom angle of each trapezoid or trapezoid is 0.02 degrees Below, it can be selected to be 2 ⁇ 10 -3 degrees or less, or 1 ⁇ 10 -4 degrees to 2 ⁇ 10 -3 degrees.
  • the angle of the lower bottom corner is appropriate, which can further improve the thickness consistency of the spliced lithium belt.
  • the thickness fluctuation of the basic lithium belt is 3% or less, and optionally 2.5% or less.
  • the thickness fluctuation of the basic lithium belt is small, and the thickness consistency of the spliced formed lithium belt obtained after splicing is better.
  • the maximum thickness H of the splicing area and the minimum thickness L of the non-splicing area satisfy the following:
  • the width of the basic lithium belt is 170 mm or less, and may be selected from 80 mm to 160 mm, or 80 mm to 130 mm.
  • the width of the basic lithium belt is appropriate, and a spliced and formed lithium belt with better thickness consistency can be obtained.
  • the spliced lithium belt has a larger width while achieving better thickness consistency.
  • the thickness of the basic lithium belt is 0.2 mm to 4 mm, optionally 0.5 mm to 3 mm, or 1 mm to 2 mm.
  • the thickness of the basic lithium belt is appropriate, which can make the thickness consistency of the spliced lithium belt better, and also have a smaller thickness.
  • the Mohs hardness of the basic lithium belt is 0.6 to 2.5, optionally 0.6 to 2.0, 0.6 to 1.5, or 0.6 to 1.0.
  • the Mohs hardness of the basic lithium belt is within the above range, which can further improve the thickness consistency of the spliced lithium belt and increase the splicing strength of the spliced lithium belt.
  • the spliced and formed lithium belt is formed by splicing and forming two or more of the basic lithium belts in the width direction of each other, and the splicing area and the non-splicing area are formed in the splicing and forming The lithium ribbons are alternately distributed in the width direction.
  • the thickness consistency of such a spliced lithium belt is relatively high.
  • the position of the body region in the width direction fluctuates within 1 mm.
  • the overall thickness consistency of such a spliced lithium belt is further improved.
  • the second aspect of the present application provides a method for preparing a spliced lithium belt, which includes:
  • each basic lithium belt Provides more than two basic lithium belts, and the thickness fluctuation of each basic lithium belt is less than 5%;
  • the spliced lithium belt has spliced areas and non-spliced areas alternately distributed along the splicing direction, and the maximum thickness H of the spliced area and the minimum thickness L of the non-spliced area satisfy:
  • the improved preparation method of the present application adopts the splicing method of the basic lithium belt, and controls the thickness fluctuation of the basic lithium belt and the thickness relationship between the spliced area and the non-spliced area within a specific range.
  • the obtained spliced and formed lithium belt can simultaneously take into account the larger Width and good thickness consistency.
  • the spliced and formed lithium belt can be used to prepare a pre-filled lithium negative pole piece with a larger width, and the negative pole piece can obtain higher pre-insertion lithium uniformity. Therefore, the lithium ion battery adopting the negative pole piece can simultaneously obtain higher energy density and cycle performance.
  • two or more of the basic lithium belts are sequentially spliced along their own width direction, and the edges of the two adjacent basic lithium belts are stacked with each other in a width of 0.1 mm to 3.5. mm; Before the pressing, it also includes correcting the deviation of the two or more basic lithium belts after splicing, taking the outer edge of the outermost basic lithium belt as the reference, and the edges of the two adjacent basic lithium belts are stacked on each other The position of the laminated area in the width direction fluctuates within 1 mm.
  • a third aspect of the present application provides a negative electrode sheet, which includes: a negative electrode current collector; a negative electrode active material layer provided on the negative electrode current collector; a lithium-based metal layer provided on the negative electrode active material layer, wherein, The lithium-based metal layer is formed by laminating the spliced lithium belt according to the first aspect of the present application or the spliced lithium belt obtained according to the preparation method of the second aspect of the present application on the surface of the negative active material layer. form.
  • the negative pole piece of the present application adopts the spliced lithium belt described in the present application, it can have both a larger width and a higher uniformity of lithium pre-insertion.
  • the fourth aspect of the present application provides a battery cell, which includes the negative pole piece according to the third aspect of the present application.
  • the battery cell of this application adopts the negative pole piece described in this application, which can have higher energy density and cycle performance.
  • a fifth aspect of the present application provides a lithium ion battery, which includes a battery cell and an electrolyte, and the battery cell adopts the battery cell according to the fourth aspect of the present application.
  • the lithium ion battery of the present application uses the battery cell of the present application, it can have higher energy density and cycle performance.
  • a sixth aspect of the present application provides a battery module, which includes the lithium ion battery according to the fifth aspect of the present application.
  • a seventh aspect of the present application provides a battery pack including the battery module according to the sixth aspect of the present application.
  • An eighth aspect of the present application provides a device, which includes at least one of the lithium ion battery according to the fifth aspect of the present application, the battery module according to the sixth aspect of the present application, or the battery pack according to the seventh aspect of the present application.
  • the battery module, battery pack, and device of the present application include the lithium ion battery described in the present application, and therefore have at least the same or similar technical effects as the lithium ion battery.
  • FIG. 1 is a schematic cross-sectional view of a splicing area of a spliced lithium belt according to an embodiment of the application.
  • FIG. 2 is a graph showing the thickness change of the spliced lithium belt of Example 21 and the wide lithium belt of Comparative Example 1.
  • Fig. 3 is a schematic diagram of an embodiment of a lithium ion battery.
  • Fig. 4 is an exploded view of Fig. 3.
  • Fig. 5 is a schematic diagram of an embodiment of a battery module.
  • Fig. 6 is a schematic diagram of an embodiment of a battery pack.
  • Fig. 7 is an exploded view of Fig. 6.
  • FIG. 8 is a schematic diagram of an embodiment of a device in which a lithium ion battery is used as a power source.
  • any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range.
  • every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
  • the embodiment of the first aspect of the present application provides a spliced lithium belt.
  • the spliced lithium belt is formed by splicing two or more basic lithium belts, wherein the thickness fluctuation of the basic lithium belt is less than 5%; the spliced lithium belt has splicing areas and non-splicing areas alternately distributed along the splicing direction.
  • the maximum thickness H of and the minimum thickness L of the non-splicing area satisfy:
  • the inventors cleverly discovered that by adopting the splicing method of the basic lithium belt, and controlling the thickness fluctuation of the basic lithium belt and the thickness relationship between the splicing area and the non-splicing area within a specific range, the obtained splicing and forming lithium belt can simultaneously take into account the larger The width and good thickness consistency.
  • the maximum thickness of the basic lithium belt in the TD direction is recorded as L 1
  • the minimum thickness of the basic lithium belt in the TD direction is recorded as L 2
  • the design thickness of the basic lithium belt (that is, the thickness specification of the basic lithium belt) is recorded as L 0
  • the maximum thickness and minimum thickness of the basic lithium belt can be measured by instruments and methods known in the art. For example, a micrometer or a micrometer is used to measure the thickness of the basic lithium belt at predetermined intervals from one side edge in the width direction (ie TD direction) of the basic lithium belt to the opposite side edge. Those skilled in the art can select the preset distance according to the requirements of test accuracy. The preset distance is, for example, 1 mm to 30 mm, such as 5 mm to 20 mm. The maximum value among the multiple measured thickness values can be recorded as L 1 , and the minimum value can be recorded as L 2 .
  • the spliced lithium belt of the present application is formed by splicing more than two basic lithium belts. Specifically, the edges of two adjacent basic lithium belts are laminated with each other, and the resulting spliced and molded lithium belt includes spliced areas and non-spliced areas along the splicing direction.
  • the thickness fluctuation of the basic lithium belt is less than 5%, which can make the non-spliced area of the spliced lithium belt have a higher thickness consistency, and can make the thickness fluctuation of the spliced area of the spliced lithium belt smaller.
  • the maximum dimension of the splicing area in the thickness direction of the spliced lithium ribbon is the maximum thickness H of the splicing area.
  • the minimum dimension of the non-spliced area in the thickness direction of the spliced lithium ribbon is the thickness L of the non-spliced area.
  • the value of B can be measured with instruments and methods well known in the art. For example, using a micrometer or a micrometer and other size measuring tools, the thickness of the spliced lithium strip is measured at predetermined intervals from one side edge in the width direction (ie TD direction) of the spliced lithium belt to the opposite side edge. Those skilled in the art can select the preset distance according to the requirements of test accuracy. The preset distance is, for example, 1 mm to 30 mm, such as 5 mm to 20 mm.
  • the multiple thickness values measured include multiple thickness values in the spliced area and multiple thickness values in the non-spliced area. Wherein, the multiple thickness values of the splicing area include multiple thickness values of the body area (see the description below for details).
  • the maximum value among the multiple thickness values of the body region of the splicing area is recorded as H, and the minimum value among the multiple thickness values of the non-splicing area is recorded as L.
  • the spliced lithium belt has good thickness uniformity as a whole.
  • the thickness fluctuation A of the basic lithium belt satisfies A ⁇ 3%, for example, A ⁇ 2.5%, A ⁇ 2.0%, A ⁇ 1.7%, A ⁇ 1.5%, A ⁇ 1.3%, A ⁇ 1.1%, or A ⁇ 1.0%, etc.
  • the thickness fluctuation of the basic lithium belt is small, and the thickness consistency of the spliced formed lithium belt obtained after splicing is better.
  • the thickness of the base lithium belt is 4 mm or less.
  • the thickness of the basic lithium belt is appropriate, which can make the thickness consistency of the spliced lithium belt better, and also have a smaller thickness. This can better meet the application requirements of prelithiation of the negative electrode in the battery.
  • the thickness of the basic lithium belt may be 10 ⁇ m or more, 100 ⁇ m or more, 200 ⁇ m or more, 300 ⁇ m or more, 500 ⁇ m or more, 800 ⁇ m or more, 1 mm or more, or 1.2 mm or more.
  • the thickness of the basic lithium belt may be 4mm or less, 3.5mm or less, 3mm or less, 2.5mm or less, 2mm or less, or 1.5mm or less.
  • the thickness of the basic lithium belt is 0.2 mm to 4 mm, 0.5 mm to 3 mm, or 1 mm to 2 mm.
  • the width of the base lithium belt is 170 mm or less.
  • the width of the basic lithium belt affects its own thickness consistency, which in turn affects the thickness consistency of the spliced lithium belt. If the width of the basic lithium belt is appropriate, it can obtain better thickness consistency, so as to obtain a spliced lithium belt with better thickness consistency.
  • the width of the basic lithium belt is 160 mm or less. Using the basic lithium belt can make the spliced lithium belt have better thickness consistency. Further optionally, the width of the basic lithium belt may be 150 mm or less, 140 mm or less, 130 mm or less, 120 mm or less, 110 mm or less, or 100 mm or less.
  • an appropriately wide base lithium belt can be used.
  • the number of basic lithium ribbons that need to be spliced is small, that is, the number of splicing areas is small, which can reduce the influence of the thickness deviation of the splicing area on the thickness consistency of the entire spliced lithium ribbon.
  • the obtained spliced lithium belt has a larger width and better thickness consistency, that is, the overall thickness fluctuation of the spliced lithium belt is smaller.
  • the width of the basic lithium belt can be 10 mm or more, 30 mm or more, 50 mm or more, 60 mm or more, 70 mm or more, 80 mm or more, or 90 mm or more.
  • the width of the basic lithium belt is 80 mm to 160 mm, for example, 80 mm to 130 mm, or 80 mm to 100 mm.
  • the basic lithium belt can make the spliced lithium belt obtain better thickness consistency.
  • the Mohs hardness of the base lithium belt is 0.6 to 2.5.
  • the Mohs hardness of the basic lithium belt is 0.6 to 2.5, the fluidity of the metal is better during the pressing (such as rolling) process, which is convenient for the pressing operation, and the splicing strength is high.
  • the Mohs hardness of the basic lithium belt is 0.6-2.5, and the uniformity of the metal flow is better during the pressing (such as rolling) process, which can further improve the thickness consistency of the spliced lithium belt.
  • the Mohs hardness of the basic lithium belt is 0.6 to 2.0, 0.6 to 1.5, or 0.6 to 1.0.
  • the basic lithium belt may be a metal lithium belt or a lithium alloy belt.
  • the lithium alloy belt is based on metallic lithium and added with modifying elements.
  • the Mohs hardness of the basic lithium belt can be adjusted.
  • the modifying element may be selected from one or more of Al, Mg, Na, K, Ca, Si, Pb, Fe, Ni and Cu.
  • the mass percentage of metallic lithium in the lithium alloy belt is more than 80%, for example, more than 90%.
  • the lithium alloy ribbon has a relatively high content of metallic lithium. When it is used for the pre-lithiation of the negative electrode, it can improve the effect of the pre-lithiation of the negative electrode, thereby helping to increase the energy density of the battery.
  • the Mohs hardness of the basic lithium belt can be measured by instruments and methods known in the art. For example, Mohs hardness tester.
  • the maximum thickness H of the spliced area and the minimum thickness L of the non-spliced area satisfy B ⁇ 5%.
  • the spliced and molded lithium belt of the present application includes spliced areas and non-spliced areas. Specifically, the edges of two adjacent basic lithium belts are laminated with each other, and they are laminated into a whole by laminating. Among them, under the pressure of lamination, the thickness of the lamination area is reduced, and the metal in the lamination area will flow to the other edge of the two basic lithium belts opposite to the lamination edge, so that the finally formed spliced lithium
  • Each splicing area of the belt includes a main body area and transition areas located on both sides of the main body area. The transition area of each splicing area is adjacent to the non-splicing area.
  • the side of the transition area away from the body area is the non-splicing area.
  • the thickness of the non-splicing area is basically the same; the thickness of the body area of the splicing area is basically the same, and the thickness of the transition area shows a decreasing thickness gradient from the body area to the non-splicing area.
  • the width of the body region is substantially equal to the stacking width of the edges of two adjacent base lithium belts before lamination. Therefore, the width of the body region can be used to reflect the splicing width.
  • the width of each body area is less than 3.5mm, a spliced and formed lithium belt with higher thickness consistency can be obtained.
  • the width of each body region may be ⁇ 3.5mm, ⁇ 3mm, ⁇ 2.8mm, ⁇ 2.5mm, ⁇ 2.3mm, ⁇ 2mm, ⁇ 1.8mm, or ⁇ 1.5mm.
  • the width of each body area can be ⁇ 0.1mm, ⁇ 0.3mm, ⁇ 0.5mm, ⁇ 0.7mm, ⁇ 0.9mm, ⁇ 1.0mm, or ⁇ 1.1mm.
  • each body area is 0.1 mm to 3.5 mm, for example, 1 mm to 3 mm, or 1 mm to 2 mm.
  • the proper width of each body area can make the spliced lithium belt have better thickness consistency, and also have higher splicing strength and mechanical properties.
  • the splicing area includes two protruding parts opposite to each other in the thickness direction of the spliced lithium ribbon.
  • the two protruding parts respectively protrude from the two surfaces of the non-spliced area in the thickness direction of the spliced lithium belt. That is, one of the protrusions protrudes from the surface of the side of the non-spliced area in the thickness direction of the spliced lithium ribbon, and the other protrusion protrudes from the other side of the non-spliced area opposite to the aforementioned one side surface. surface.
  • each protrusion in the thickness direction of the spliced lithium ribbon is trapezoidal or trapezoid-like.
  • the area corresponding to the upper bottom of the trapezoid or trapezoid is the body area of the splicing area, and the areas corresponding to both sides of the trapezoid or trapezoid are the transition areas of the splicing area, respectively.
  • the bottom angle ⁇ of the trapezoid or trapezoid-like shape is 0.02 degrees or less, for example, 2 ⁇ 10 -3 degrees or less, for example, 1 ⁇ 10 -4 degrees to 2 ⁇ 10 -3 degrees, or 1 ⁇ 10 -4 degrees to 9 ⁇ 10 -4 degrees and so on.
  • the lateral thickness change of the splicing area has less influence on the thickness consistency of the spliced lithium ribbon, which can further improve the thickness consistency of the spliced lithium ribbon.
  • the lower bottom angle ⁇ of the splicing area can be measured with instruments and methods known in the art. For example, the following method can be used to determine the bottom angle ⁇ : take a sample of the spliced lithium ribbon, and cut the sample to obtain its cross section; measure the size of the transition area in the width direction of the spliced lithium ribbon and record it as l 1 , measure The size of the protrusion in the thickness direction of the spliced lithium ribbon is recorded as l 2 ; then ⁇ is calculated according to the following formula:
  • the basic lithium belt is a long strip, and the basic lithium belt is spliced along the width direction of the spliced lithium belt. That is, the spliced lithium belt is formed by splicing two or more basic lithium belts in the width direction of each other, and the spliced area and the non-spliced area are alternately distributed in the width direction of the spliced lithium belt. The thickness consistency of such a spliced lithium belt is relatively high.
  • the position of the body region in the width direction fluctuates within 1 mm on the basis of the side edges in the width direction of the spliced lithium belt itself.
  • the position fluctuation of the splicing area in the width direction can be tested by the following methods.
  • the method includes: testing the side edge of the body area with the same side or the opposite side to form the lithium by measuring the size (such as a soft ruler, etc., the test accuracy is 0.1mm)
  • the distance between the edges of the belt is measured at intervals of 0.2m ⁇ 0.5m in the length direction of the spliced lithium belt (the test interval can be adjusted by those skilled in the art according to requirements); the maximum value among the multiple values obtained by the test
  • the difference from the minimum value is less than or equal to 1mm. Since the brightness of the body region after lamination is greater than that of other regions, it is easy to distinguish the edges of the body region.
  • the position of the body area fluctuates within 1 mm, that is, the splicing area is basically a straight line area along the length of the spliced lithium belt.
  • the overall thickness consistency of such a spliced lithium belt is further improved.
  • the Mohs hardness of the basic lithium belt is 0.6-2.5, such as 0.6-2.0, 0.6-1.5, or 0.6-1.0, it is also suitable for making the lower base angle ⁇ of the splicing zone meet the aforementioned requirements.
  • the Mohs hardness of the basic lithium belt is 0.6 to 2.5, such as 0.6 to 2.0, 0.6 to 1.5, or 0.6 to 1.0, it is also beneficial to fluctuate the position of the body region of the splicing area within 1 mm.
  • the shape of the basic lithium belt and the splicing direction there is no particular limitation on the shape of the basic lithium belt and the splicing direction.
  • the basic lithium belt can be any shape, such as triangle, quadrilateral, pentagon, irregular polygon, etc.
  • the splicing direction of the basic lithium belt may be along the width direction or the length direction of the spliced lithium belt, or the splicing direction of the basic lithium belt may be any other direction.
  • the embodiment of the second aspect of the present application provides a method for preparing a spliced lithium belt, by which any of the foregoing spliced lithium belts can be obtained.
  • a method for preparing a spliced lithium belt of the present application includes the following steps:
  • S10 Provide more than two basic lithium belts, and the thickness fluctuation of each basic lithium belt is less than 5%.
  • the basic lithium belt may be a metal lithium belt or a lithium alloy belt.
  • the lithium alloy belt can be the lithium alloy belt described above.
  • the thickness fluctuation of the basic lithium belt is 3% or less, or 2.5% or less.
  • the width of the basic lithium belt is 80 mm to 160 mm, 80 mm to 130 mm, or 80 mm to 100 mm, etc.
  • the Mohs hardness of the basic lithium belt is 0.6-2.5, 0.6-2.0, 0.6-1.5, or 0.6-1.0, etc.
  • the thickness of the basic lithium belt is 0.2 mm to 4 mm, 0.5 mm to 3 mm, or 1 mm to 2 mm, etc.
  • the basic lithium belt is commercially available or can be prepared by methods known in the art.
  • the first substrate, the lithium sheet to be rolled, and the second substrate can be stacked in sequence, and rolled by a rolling device, so that the three are laminated together;
  • the second substrate is peeled off.
  • both sides of the lithium sheet to be rolled are completely covered by the first substrate and the second substrate.
  • the first substrate may be a polymer film, a metal film or an inorganic material film.
  • the first substrate may be Teflon, polyethylene, polypropylene, polyurethane, polytetrafluoroethylene, polyarylsulfone, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer , One or more of polyimide and polyethersulfone.
  • the second substrate may be a polymer film, a metal film or an inorganic material film.
  • the second substrate can be Teflon, polyethylene, polypropylene, polyurethane, polytetrafluoroethylene, polyarylsulfone, polyethylene terephthalate, acrylonitrile-butadiene-styrene copolymer , One or more of polyimide and polyethersulfone.
  • the heating temperature of the work roll is, for example, 35°C to 120°C.
  • the rolling pressure can be 0.2MPa ⁇ 1.5MPa.
  • the speed of the work roll can range from 0.001m/min to 60m/min.
  • the gap between the work rolls can be greater than 0 and less than or equal to 5 mm.
  • two or more basic lithium belts are spliced sequentially, so that the edges of two adjacent basic lithium belts are laminated on each other, and the spliced lithium belt is obtained by pressing and bonding.
  • step S20 two or more basic lithium belts are spliced sequentially, wherein the edges of each adjacent two basic lithium belts are stacked on each other, and the width of the stack may be less than 3.5 mm, for example, 0.1 mm to 3 mm, 1 mm to 3 mm, 0.1 mm ⁇ 2mm, 0.1mm ⁇ 1mm, or 1mm ⁇ 2mm, etc.
  • the spliced multiple basic lithium belts are pressed together so that the laminated edges of every two adjacent basic lithium belts are laminated with each other into a whole.
  • the pressing can be performed by using devices and methods known in the art, such as a rolling device.
  • the pressing temperature can be normal temperature, 20°C to 30°C, or 20°C to 25°C.
  • the pressure of lamination can be adjusted according to the material and thickness of the base lithium belt. For example, in some embodiments, the pressure of lamination may be 0.9 ton to 2 ton, such as 1 ton to 1.5 ton. Among them, 1 ton pressure is equivalent to 9.8KN pressure.
  • step S20 two or more basic lithium ribbons may be spliced sequentially along their own width direction.
  • step S20 includes:
  • S210 splicing two or more basic lithium belts in order along their own width direction, so that the edges of two adjacent basic lithium belts are laminated with each other and the laminated width is less than 3.5mm, for example, 0.1mm ⁇ 3mm, 1mm ⁇ 3mm, 0.1mm ⁇ 2mm, 0.1mm ⁇ 1mm, or 1mm ⁇ 2mm, etc.
  • the position fluctuation in the width direction of the laminated area where the edges of two adjacent basic lithium belts overlap each other can be tested by the following method, including: measuring with size tools (such as tape, CCD image sensor, etc.), the test accuracy is for example 0.1mm ) Test the distance between one side edge of the laminated area of two adjacent basic lithium belts and the outer edge of the outermost basic lithium belt, at intervals of 0.2m ⁇ 0.5m in the length direction of the basic lithium belt (a person skilled in the art The test interval can be adjusted according to requirements) Test a value; the difference between the maximum value and the minimum value of the multiple values obtained by the test is less than or equal to 1mm.
  • the outermost basic lithium belt may be the outermost basic lithium belt on the same side or a different side from the side edge of the laminated area. The outer edge of the outermost basic lithium belt corresponds to the outer edge of the spliced lithium belt.
  • the deviation correction can be performed using a deviation correction sensor or the like.
  • the rolling can be performed using a device and method known in the art, such as a rolling device.
  • the temperature of the rolling can be normal temperature, 20°C to 30°C, or 20°C to 25°C.
  • the rolling pressure can be 0.9 to 2 tons, such as 1 to 1.5 tons.
  • a spliced lithium belt with a larger width and good thickness consistency can be obtained.
  • the preparation method has high operability, can improve production efficiency and reduce production costs.
  • using the preparation method of the present application to prepare a wide-width lithium belt with good thickness consistency can also obtain a higher production yield. Therefore, this application not only improves the thickness consistency of the wide-width lithium belt, but also solves the problems of extremely low production yield and high production and processing cost of directly processing a metal lithium belt with a larger width in the prior art.
  • a third aspect of the present application provides a negative electrode sheet, which includes a negative electrode current collector; a negative electrode active material layer provided on the negative electrode current collector and containing a negative electrode active material; and a lithium-based electrode provided on the negative electrode active material layer
  • the negative electrode current collector has two opposite surfaces in the thickness direction of the negative electrode.
  • the negative electrode active material layer can be provided on either one of the two surfaces, or can be respectively provided on the two surfaces.
  • the lithium-based metal layer is disposed on the surface of the negative electrode active material layer facing away from the negative electrode current collector.
  • the negative pole piece described in the third aspect of the application is a negative pole piece that has not been infiltrated by the electrolyte, and after the electrolyte is injected, there is a potential difference between the negative electrode active material layer and the lithium-based metal layer, which can be performed spontaneously
  • the lithium-based metal layer pre-inserts lithium on the negative electrode active material layer, and part or all of the metal lithium of the lithium-based metal layer is pre-inserted into the negative electrode active material to form the negative electrode active material pre-inserted with lithium.
  • the negative pole piece of the present application adopts the spliced lithium belt described in the present application, it can have both a larger width and a higher uniformity of lithium pre-insertion. Therefore, the lithium ion battery adopting the negative pole piece can simultaneously obtain higher energy density and cycle performance.
  • the negative electrode current collector can be made of a material with good electrical conductivity and mechanical strength, such as copper foil.
  • the negative electrode sheet of the present application has no particular limitation on the type of negative electrode active material, and negative electrode active materials known in the art can be used.
  • the negative active material can be selected from natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microspheres, nano carbon, elemental silicon, silicon-oxygen compounds, silicon-carbon composites, silicon alloys, elemental tin, tin oxide One or more of compound, tin-carbon composite, tin alloy and lithium titanate.
  • the negative electrode active material layer may also include an optional conductive agent, an optional binder, and an optional thickener, and there is no specific restriction on their types, and those skilled in the art can refer to Choose according to actual needs.
  • the conductive agent may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the binder can be selected from polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyvinyl alcohol (PVA), styrene butadiene rubber (SBR), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl One or more of CMCS.
  • the thickener may be selected from sodium carboxymethyl cellulose (CMC-Na).
  • the negative pole piece can be prepared according to conventional methods in the art. For example, disperse the negative electrode active material and optional conductive agent, optional binder and optional thickener in a solvent.
  • the solvent can be deionized water to form a uniform negative electrode slurry; coating the negative electrode slurry On the negative electrode current collector, after drying, cold pressing, etc., the negative electrode active material layer is formed; the spliced lithium tape described in this application is laminated on the surface of the negative electrode active material layer facing away from the negative electrode current collector to form lithium Base metal layer to obtain a negative pole piece.
  • the spliced lithium belt can be pressed onto the surface of the negative electrode active material layer by rolling.
  • the fourth aspect of the present application provides a battery cell, which includes any negative pole piece of the present application.
  • the battery cell is formed by a positive pole piece, a negative pole piece, and an isolation film through a lamination process or a winding process, and the isolation film is interposed between the positive pole piece and the negative pole piece for isolation.
  • the battery cell in the fourth aspect of the present application refers to a battery cell that has not been infiltrated with electrolyte.
  • the cell of the present application may only include positive pole pieces, separators, and negative pole pieces in a narrow sense, but the cell of the present application may also include other structures in a broad sense, such as terminal components, protective shell components, etc.
  • the positive pole piece includes a positive current collector and a positive active material layer provided on at least one surface of the positive current collector and including a positive active material.
  • the positive electrode current collector can be made of a material with good conductivity and mechanical strength, such as aluminum foil.
  • the battery core of the present application does not specifically limit the specific types of positive electrode active materials, and positive electrode active materials known in the art can be used, and those skilled in the art can make selections according to actual needs.
  • the positive electrode active material may be selected from lithium transition metal oxides and modified materials thereof, and the modified material may be coating modification and/or doping modification of lithium transition metal oxide.
  • the lithium transition metal oxide may be selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. One or more.
  • the positive active material layer may also include an optional binder and an optional conductive agent.
  • the types of the binder and conductive agent are not specifically limited, and those skilled in the art can according to actual conditions. Need to choose.
  • the binder may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene One or more of terpolymer and tetrafluoroethylene-hexafluoropropylene copolymer.
  • the conductive agent can be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the positive pole piece can be prepared according to conventional methods in the art.
  • the positive electrode active material and optional conductive agent and optional binder are dispersed in a solvent (such as N-methylpyrrolidone, NMP for short) to form a uniform positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector On the fluid, after drying, cold pressing and other processes, the positive pole piece is obtained.
  • a solvent such as N-methylpyrrolidone, NMP for short
  • the battery core of the present application has no particular limitation on the type of isolation membrane.
  • Any well-known porous structure isolation membrane with good chemical and mechanical stability can be selected, such as glass fiber membrane, non-woven membrane, polyethylene film, One or more of polypropylene film, polyvinylidene fluoride film, and their multilayer composite film.
  • the fifth aspect of the application provides a lithium ion battery, which includes a battery cell and an electrolyte, wherein the battery cell adopts any one or several battery cells of the application.
  • the lithium ion battery of the present application uses the battery cell of the present application, it can have both higher energy density and cycle performance.
  • the electrolyte is infiltrated in the battery core, and the positive pole piece and the negative pole piece play a role in conducting ions.
  • the electrolyte includes an electrolyte lithium salt and a solvent.
  • the electrolyte lithium salt is selected from LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI (difluorosulfonate) Lithium imide), LiTFSI (lithium bistrifluoromethanesulfonimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate borate), LiBOB (lithium bisoxalate borate), LiPO 2 F 2 (Lithium difluorophosphate), LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate) one or more.
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • the solvent is selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), carbonic acid Dipropyl ester (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), One or more of ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE)
  • the electrolyte may also optionally include additives, where there is no specific restriction on the type of additives, and can be selected according to requirements.
  • the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance of the battery, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and those that improve battery low-temperature performance. Additives etc.
  • Fig. 3 shows a lithium ion battery 5 with a square structure as an example.
  • the lithium ion battery may include an outer packaging.
  • the outer packaging is used to package the positive pole piece, the negative pole piece and the electrolyte.
  • the outer package may include a housing 51 and a cover 53.
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the housing 51 has an opening communicating with the containing cavity, and a cover plate 53 can cover the opening to close the containing cavity.
  • the positive pole piece, the negative pole piece, and the separator may be formed into the cell 52 through a winding process or a lamination process.
  • the battery core 52 is encapsulated in the containing cavity.
  • the electrolyte is infiltrated in the cell 52.
  • the number of cells 52 contained in the lithium ion battery 5 can be one or several, which can be adjusted according to requirements.
  • the outer packaging of the lithium ion battery may be a hard case, such as a hard plastic case, aluminum case, steel case, and the like.
  • the outer packaging of the lithium ion battery can also be a soft bag, such as a pouch type soft bag.
  • the material of the soft bag can be plastic, for example, it can include one or more of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), and the like.
  • lithium ion batteries can be assembled into battery modules, and the number of lithium ion batteries contained in the battery modules can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • Fig. 5 is a battery module 4 as an example.
  • a plurality of lithium ion batteries 5 may be arranged in sequence along the length direction of the battery module 4. Of course, it can also be arranged in any other manner. Furthermore, the plurality of lithium ion batteries 5 can be fixed by fasteners.
  • the battery module 4 may further include a housing having an accommodation space, and a plurality of lithium ion batteries 5 are accommodated in the accommodation space.
  • the above-mentioned battery modules 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 battery box and a plurality of battery modules 4 provided in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3.
  • the upper box body 2 can be covered on the lower box body 3 and forms a closed space for accommodating the battery module 4.
  • Multiple battery modules 4 can be arranged in the battery box in any manner.
  • This application also provides a device, which includes the lithium ion battery, battery module or battery pack described in this application.
  • the lithium ion battery, battery module or battery pack can be used as the power source of the device, and can also be used as the energy storage unit of the device.
  • the device can be, but is not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf Vehicles, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device can select a lithium ion battery, battery module or battery pack according to its usage requirements.
  • Fig. 8 is a device as an example.
  • the device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • battery packs or battery modules can be used.
  • the device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • the device usually requires light and thin, and can use lithium-ion batteries as a power source.
  • the national lithium belt (a lithium belt that complies with Li-2 in GB/T 20930-2015 "Lithium Belt”) is obtained by the roll forming method described above, and the national lithium belt is used as the basic lithium belt.
  • the width of the basic lithium belt is 80 mm
  • the design thickness is 2 mm
  • the thickness fluctuation A in the TD direction is 1%.
  • the edges of the two basic lithium belts were layered on each other with a stacking width of 1 mm. Afterwards, the two basic lithium belt layers are combined into a spliced lithium belt with a width of 159mm by rolling, and the rolling pressure is 1.5 tons.
  • the thickness fluctuation in the TD direction of the non-spliced area of the spliced lithium belt is 1%, and the B value of the spliced lithium belt is 2%.
  • Example 1 Similar to Example 1, the difference is that the width of the basic lithium belt is 100 mm, the thickness fluctuation in the TD direction is 1.3%, and the other parameters are shown in Table 1.
  • Example 1 Similar to Example 1, the difference is that the width of the basic lithium belt is 130 mm, the thickness fluctuation in the TD direction is 1.5%, and the other parameters are shown in Table 1.
  • Example 2 Similar to Example 1, the difference is that the width of the basic lithium belt is 140 mm, the thickness fluctuation in the TD direction is 2.0%, and the remaining parameters are shown in Table 1.
  • Example 1 Similar to Example 1, the difference is that the width of the basic lithium belt is 160 mm, the thickness fluctuation in the TD direction is 3.0%, and the remaining parameters are shown in Table 1.
  • Example 1 Similar to Example 1, the difference is that the width of the basic lithium belt is 170 mm, the thickness fluctuation in the TD direction is 5.0%, and the remaining parameters are shown in Table 1.
  • Example 3 Similar to Example 3, the difference is that the design thickness of the basic lithium belt is 0.2 mm, the thickness fluctuation in the TD direction is 3%, and the other parameters are shown in Table 1.
  • Example 3 Similar to Example 3, the difference is that the design thickness of the basic lithium belt is 0.5 mm, the thickness fluctuation in the TD direction is 2.5%, and the other parameters are shown in Table 1.
  • Example 3 Similar to Example 3, the difference is that the design thickness of the basic lithium belt is 1 mm, the thickness fluctuation in the TD direction is 1.7%, and the remaining parameters are shown in Table 1.
  • Example 3 Similar to Example 3, the difference is that the design thickness of the basic lithium belt is 3 mm, the thickness fluctuation in the TD direction is 1.3%, and the remaining parameters are shown in Table 1.
  • Example 3 Similar to Example 3, the difference is that the design thickness of the basic lithium belt is 4 mm, the thickness fluctuation in the TD direction is 1.1%, and the remaining parameters are shown in Table 1.
  • the thickness fluctuation of the wide lithium belt is 23% (measured according to the measurement method of the thickness fluctuation of the basic lithium belt) , And other parameters are shown in Table 1.
  • the Mohs hardness of the lithium sheet used to prepare the wide lithium belt is 0.6.
  • Example 1 Similar to Example 1, the difference is that the width of the basic lithium belt is 180 mm, the thickness fluctuation in the TD direction is 5.5%, and the remaining parameters are shown in Table 1.
  • Comparative Example 1 a wide-width lithium belt was directly formed and processed at one time, and the thickness of the wide-width lithium belt was greatly fluctuated and the thickness uniformity was poor (as shown in FIG. 2).
  • the thickness of the basic lithium belts of Comparative Examples 2 and 3 fluctuates greatly, which also causes the thickness uniformity of the spliced wide-width lithium belts to deteriorate.
  • the thickness of the basic lithium belt will affect its own thickness fluctuation, which in turn will affect the thickness consistency of the spliced lithium belt.
  • the thickness of the basic lithium belt is 4 mm or less, and the thickness fluctuation is less than 5%, it is beneficial to improve the thickness consistency of the spliced lithium belt.
  • Example 21 It can be seen from the results of Example 3 and Example 21 that the rolling pressure of the spliced basic lithium belt will affect the thickness consistency of the spliced lithium belt.
  • the rolling pressure in Example 21 is relatively small, resulting in a large thickness of the splicing zone, and the thickness consistency of the obtained spliced lithium belt is relatively reduced.

Abstract

一种拼接成型锂带、其制备方法、及其相关的负极极片、电芯(52)、、锂离子电池(5)、电池模块(4)、电池包(1)和装置。拼接成型锂带为由两个以上的基础锂带相互拼接成型；其中，所述基础锂带的厚度波动为5％以下；所述拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，拼接区的最大厚度H与非拼接区的最小厚度L之间满足（I）。

Description

拼接成型锂带、其制备方法、及其相关的负极极片、电芯、锂离子电池、电池模块、电池包和装置
相关申请的交叉引用
本申请要求享有于2019年08月02日提交的名称为“拼接成型锂带及其制备方法”的中国专利申请201910712143.8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
本申请属于储能装置技术领域，具体涉及一种拼接成型锂带、其制备方法、及其相关的负极极片、电芯、锂离子电池、电池模块、电池包和装置。
背景技术
随着新能源汽车的普及，大家对动力电池的续航里程要求越来越高。同时，手机等消费类电子产品越来越普及和多样化，用户的一个重要体验感就是一次充电后的使用时间。因此，高能量密度二次电池的需求越来越渴望。
增加电极宽度能增大电芯的容量。而为了获得更高的能量密度，可以对阳极(又称负极)进行预锂化。预锂化的方式很多，其中一种阳极预锂化方案采用的是金属锂带。例如，将金属锂带经辊压得到预补锂锂箔，锂箔与负极膜层接触或层合，在电位差的作用下，使金属锂箔对负极活性材料预锂化。然而，目前普遍使用的锂带宽度较小，不能很好地满足宽电极预锂化的需求。因此，急需开发一种宽幅锂带，以满足市场的需求。
发明内容
本发明人发现，如果直接增大金属锂带的宽度，即采用一次成型的方式制备宽幅锂带，则宽幅锂带TD(Transverse Direction，横向)方向的厚度一致性较差。这样的锂带用于预补锂锂箔的生产过程中易发生锂带堆积，不利于连续生产，严重影响生产效率和优率；同时所获得的锂箔用于负极预补锂，会导致负极预嵌锂的均匀性变差，进而影响电池的循环性能。
本发明人进行了大量研究并巧妙地发现，可以通过将两个以上的窄幅锂带作为基础 锂带相互拼接成型，来获得厚度一致性良好的宽幅锂带。
因此，本申请一方面提供一种拼接成型锂带，其为由两个以上的基础锂带相互拼接成型；其中，
基础锂带的厚度波动为5％以下；
拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，拼接区的最大厚度H与非拼接区的最小厚度L之间满足：
Figure PCTCN2020103483-appb-000001
令人惊奇地发现，本申请采用基础锂带拼接的方式，并控制基础锂带的厚度波动以及拼接区和非拼接区的厚度关系在特定范围内，所获得的拼接成型锂带能同时兼顾较大的宽度和良好的厚度一致性。该拼接成型锂带可用于制备更大宽度的预补锂负极极片，并且使负极极片获得较高的预嵌锂均匀性。因此，采用该负极极片的锂离子电池，能同时获得较高的能量密度和循环性能。
在本申请第一方面的上述任意实施方式中，所述拼接区可包括本体区域及过渡区域，各所述拼接区的所述过渡区域与所述非拼接区相邻，各所述本体区域的宽度为0.1mm～3.5mm，可选为1mm～3mm。各本体区域的宽度适当，能使拼接成型锂带具有较好的厚度一致性的同时，还具有较高的拼接强度和力学性能。
在本申请第一方面的上述任意实施方式中，所述拼接区可包括沿所述拼接成型锂带的厚度方向相对的两个凸出部，所述两个凸出部分别凸出于所述非拼接区在所述厚度方向上的两个表面，且各所述凸出部在所述厚度方向上的横截面呈梯形或类梯形，各所述梯形或类梯形的下底角为0.02度以下，可选为2×10 -3度以下，或1×10 -4度～2×10 -3度。所述下底角的角度适当，能进一步提高拼接成型锂带的厚度一致性。
在本申请第一方面的上述任意实施方式中，所述基础锂带的厚度波动为3％以下，可选为2.5％以下。基础锂带的厚度波动较小，拼接后得到的拼接成型锂带的厚度一致性更好。
在本申请第一方面的上述任意实施方式中，所述拼接区的最大厚度H与所述非拼接区的最小厚度L之间满足：
Figure PCTCN2020103483-appb-000002
拼接成型锂带的拼接区与非拼接区的厚度偏差越小，拼接成型锂带整体的厚度一致性越好。
在本申请第一方面的上述任意实施方式中，所述基础锂带的宽度为170mm以下，可 选为80mm～160mm，或80mm～130mm。基础锂带的宽度适当，能获得厚度一致性更好的拼接成型锂带。尤其是，拼接成型锂带在具有较大宽度的同时获得更好的厚度一致性。
在本申请第一方面的上述任意实施方式中，所述基础锂带的厚度为0.2mm～4mm，可选为0.5mm～3mm，或1mm～2mm。基础锂带的厚度适当，能使拼接成型锂带的厚度一致性较好的同时，还具有较小的厚度。
在本申请第一方面的上述任意实施方式中，所述基础锂带的莫氏硬度为0.6～2.5，可选为0.6～2.0，0.6～1.5，或0.6～1.0。基础锂带的莫氏硬度在上述范围内，能进一步提高拼接成型锂带的厚度一致性，并提高拼接成型锂带的拼接强度。
在本申请第一方面的上述任意实施方式中，所述拼接成型锂带为由两个以上的所述基础锂带在自身宽度方向上相互拼接成型，拼接区和非拼接区在所述拼接成型锂带自身宽度方向上交替分布。这样的拼接成型锂带整体上的厚度一致性较高。
在本申请第一方面的上述任意实施方式中，以所述拼接成型锂带自身宽度方向上的侧边沿为基准，所述本体区域在所述宽度方向上的位置波动在1mm以内。这样的拼接成型锂带的整体厚度一致性得到进一步提高。
本申请第二方面提供一种拼接成型锂带的制备方法，其包括：
提供两个以上的基础锂带，各基础锂带的厚度波动为5％以下；
将两个以上的基础锂带依次拼接，使相邻两个基础锂带的边缘相互层叠，经压合，得到拼接成型锂带；
其中，拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，拼接区的最大厚度H与非拼接区的最小厚度L之间满足：
Figure PCTCN2020103483-appb-000003
本申请提高的制备方法采用基础锂带拼接的方式，并控制基础锂带的厚度波动以及拼接区和非拼接区的厚度关系在特定范围内，所获得的拼接成型锂带能同时兼顾较大的宽度和良好的厚度一致性。该拼接成型锂带可用于制备更大宽度的预补锂负极极片，并且使负极极片获得较高的预嵌锂均匀性。因此，采用该负极极片的锂离子电池，能同时获得较高的能量密度和循环性能。
在本申请第二方面的上述任意实施方式中，两个以上的所述基础锂带为沿自身宽度方向依次拼接，相邻两个所述基础锂带的边缘相互层叠的宽度为0.1mm～3.5mm；在所述压合之前还包括对拼接后的两个以上所述基础锂带进行纠偏，以最外侧基础锂带的外侧 边沿为基准，相邻两个所述基础锂带的边缘相互层叠的层叠区域在所述宽度方向上的位置波动在1mm以内。
本申请第三方面提供一种负极极片，其包括：负极集流体；设置于所述负极集流体上的负极活性物质层；设置于所述负极活性物质层上的锂基金属层，其中，所述锂基金属层为由根据本申请第一方面所述的拼接成型锂带或根据本申请第二方面所述制备方法得到的拼接成型锂带层合于所述负极活性物质层的表面而形成。
本申请的负极极片由于采用了本申请所述的拼接成型锂带，其可以兼具更大的宽度和较高的预嵌锂均匀性。
本申请第四方面提供一种电芯，其包括根据本申请第三方面的负极极片。
本申请的电芯采用本申请所述的负极极片，其可具有较高的能量密度和循环性能。
本申请第五方面提供一种锂离子电池，其包括电芯和电解液，所述电芯采用根据本申请第四方面的电芯。
本申请的锂离子电池由于采用本申请的电芯，因而能具有较高的能量密度和循环性能。
本申请第六方面提供一种电池模块，其包括根据本申请第五方面的锂离子电池。
本申请第七方面提供一种电池包，其包括根据本申请第六方面的电池模块。
本申请第八方面提供一种装置，其包括根据本申请第五方面的锂离子电池、根据本申请第六方面的电池模块、或根据本申请第七方面的电池包中的至少一种。
本申请的电池模块、电池包和装置包括本申请所述锂离子电池，因而至少具有与所述锂离子电池相同或类似的技术效果。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请一个实施例的拼接成型锂带的拼接区的截面示意图。
图2为实施例21的拼接成型锂带及对比例1的宽幅锂带的厚度变化曲线图。
图3是锂离子电池的一实施方式的示意图。
图4是图3的分解图。
图5是电池模块的一实施方式的示意图。
图6是电池包的一实施方式的示意图。
图7是图6的分解图。
图8是锂离子电池用作电源的装置的一实施方式的示意图。
具体实施方式
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合具体实施例对本申请进行详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或几种”中“几种”的含义是两种以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代表性组，不应解释为穷举。
本申请第一方面的实施例提供一种拼接成型锂带。拼接成型锂带为由两个以上的基础锂带相互拼接成型，其中，基础锂带的厚度波动为5％以下；拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，拼接区的最大厚度H与非拼接区的最小厚度L之间满足：
Figure PCTCN2020103483-appb-000004
本发明人巧妙地发现，采用基础锂带拼接的方式，并控制基础锂带的厚度波动以及拼接区和非拼接区的厚度关系在特定范围内，所获得的拼接成型锂带能同时兼顾较大的宽度和良好的厚度一致性。
在本文中，基础锂带的TD方向最大厚度记为L 1，基础锂带的TD方向最小厚度记为L 2，基础锂带的设计厚度(即该基础锂带的厚度规格)记为L 0，则基础锂带的厚度波动A＝(L 1-L 2)/L 0×100％，且A满足A≤5％。
可以用本领域公知的仪器及方法进行测定基础锂带的最大厚度和最小厚度。例如采用千分尺或万分尺等尺寸量具，由基础锂带的宽度方向(即TD方向)的一侧边沿至相对的另一侧边沿每隔预设间距测定基础锂带的厚度值。本领域技术人员可根据测试精度的需求选择所述预设间距。所述预设间距例如为1mm～30mm，如5mm～20mm。所测的多个厚度值中的最大值可记为L 1，最小值可记为L 2。
本申请的拼接成型锂带由两个以上的基础锂带拼接而成。具体的，相邻两个基础锂带的边缘相互层合，则所得拼接成型锂带包括沿拼接方向的拼接区和非拼接区。基础锂带的厚度波动为5％以下，能使拼接成型锂带的非拼接区具有较高的厚度一致性，并且能使拼接成型锂带的拼接区的厚度波动较小。
在本文中，拼接区在拼接成型锂带的厚度方向上的最大尺寸为拼接区的最大厚度H。非拼接区在拼接成型锂带的厚度方向上的最小尺寸为非拼接区的厚度L。拼接区的最大厚度H与非拼接区的最小厚度L之间的关系记为B＝|H-L|/L×100％。也就是，B可表示拼接成型锂带的拼接区与非拼接区的厚度偏差，同时，B也体现了拼接成型锂带的厚度一致性。B≤6％，使拼接区的厚度对拼接成型锂带的整体厚度的波动影响较小，拼接成型锂带的厚度一致性得到显著提高。
可以用本领域公知的仪器及方法进行测定B的值。例如，采用千分尺或万分尺等尺寸量具，由拼接成型锂带的宽度方向(即TD方向)的一侧边沿至相对的另一侧边沿每隔预设间距测定拼接成型锂带的厚度值。本领域技术人员可根据测试精度的需求选择所述预设间距。所述预设间距例如为1mm～30mm，如5mm～20mm。所测的多个厚度值中包括拼接区的多个厚度值和非拼接区的多个厚度值。其中，拼接区的多个厚度值中包括本体区域(详见后文的描述)的多个厚度值。拼接区的本体区域的多个厚度值中的最大值记为H，非拼接区的多个厚度值中的最小值记为L。
若A≤5％且B≤6％，则拼接成型锂带的整体具有良好的厚度一致性。
在一些可选的实施方式中，基础锂带的厚度波动A满足A≤3％，例如A≤2.5％，A≤2.0％，A≤1.7％，A≤1.5％，A≤1.3％，A≤1.1％，或A≤1.0％等。基础锂带的厚度波动较小，拼接后得到的拼接成型锂带的厚度一致性更好。
在一些可选的实施方式中，基础锂带的厚度为4mm以下。基础锂带的厚度适当，能使拼接成型锂带的厚度一致性较好的同时，还具有较小的厚度。这能更好地满足电池中负极预锂化的应用需求。
可选地，基础锂带的厚度可以为10μm以上，100μm以上，200μm以上，300μm以上，500μm以上，800μm以上，1mm以上，或1.2mm以上。可选的，基础锂带的厚度可 以为4mm以下，3.5mm以下，3mm以下，2.5mm以下，2mm以下，或1.5mm以下。例如，基础锂带的厚度为0.2mm～4mm，0.5mm～3mm，或1mm～2mm。
在一些可选的实施方式中，基础锂带的宽度为170mm以下。基础锂带的宽度影响其自身的厚度一致性，进而影响拼接成型锂带的厚度一致性。基础锂带的宽度适当，则其能获得较好的厚度一致性，从而获得厚度一致性较好的拼接成型锂带。
可选的，基础锂带的宽度为160mm以下。采用该基础锂带能使拼接成型锂带具有更好的厚度一致性。进一步可选的，基础锂带的宽度可以为150mm以下，140mm以下，130mm以下，120mm以下，110mm以下，或100mm以下。
为了获得较宽的拼接成型锂带，则可使用适当宽的基础锂带。这样所需拼接的基础锂带的数量较少，即拼接区的数量较少，能减小拼接区厚度偏差对整个拼接成型锂带厚度一致性的影响。由此，获得的拼接成型锂带的宽度较大、且厚度一致性更好，即拼接成型锂带整体的厚度波动更小。可选的，基础锂带的宽度可以为10mm以上，30mm以上，50mm以上，60mm以上，70mm以上，80mm以上，或90mm以上。
在一些可选的实施方式中，基础锂带的宽度为80mm～160mm，例如80mm～130mm，或80mm～100mm等。该基础锂带能使拼接成型锂带获得更好的厚度一致性。
在一些可选的实施方式中，基础锂带的莫氏硬度为0.6～2.5。当基础锂带的莫氏硬度为0.6～2.5时，在压合(如辊压)过程中，金属的流动性较好，方便压合操作，且拼接强度较高。特别地，基础锂带的莫氏硬度为0.6～2.5，在压合(如辊压)过程中，金属流动的均匀性较好，能使拼接成型锂带的厚度一致性得到进一步提高。
可选的，基础锂带的莫氏硬度为0.6～2.0，0.6～1.5或0.6～1.0等。
在一些可选的实施方式中，基础锂带可以为金属锂带或锂合金带。锂合金带为以金属锂为基材且添加有改性元素。由此可以调整基础锂带的莫氏硬度。例如，改性元素可以选自Al、Mg、Na、K、Ca、Si、Pb、Fe、Ni及Cu中的一种或几种。
可选的，锂合金带中金属锂的质量百分含量为80％以上，例如90％以上。锂合金带中金属锂的含量较高，当其用于负极预锂化时，能提高负极预锂化的效果，从而有利于提升电池的能量密度。
可以用本领域公知的仪器及方法进行测定基础锂带的莫氏硬度。例如莫氏硬度计。
在一些可选的实施方式中，拼接区的最大厚度H与非拼接区的最小厚度L之间满足B≤5％。拼接成型锂带的拼接区与非拼接区的厚度偏差越小，则拼接成型锂带整体的厚度一致性越好。例如，B≤4.5％，≤4.0％，≤3.5％，≤3.0％，≤2.7％，≤2.5％，≤2.3％，≤2.0％，或≤1.7％等。
本申请的拼接成型锂带包括拼接区和非拼接区。具体的，相邻两个基础锂带的边缘相互层叠，并经压合层合为一体。其中，在层合的压力作用下，层叠区域的厚度减小，层叠区域的金属还会发生向两个基础锂带的与层叠边缘相对的另一边缘方向的流动，使最终形成的拼接成型锂带的各拼接区包括本体区域及位于该本体区域两侧的过渡区域。各拼接区的过渡区域与非拼接区相邻。具体的，过渡区域远离本体区域的一侧为非拼接区。请参照图1，非拼接区的厚度基本一致；拼接区的本体区域的厚度基本一致，过渡区域的厚度由本体区域至非拼接区的方向呈减小的厚度梯度。
相邻两个基础锂带的拼接宽度越小，拼接区的厚度偏差对拼接成型锂带的厚度一致性的影响越小。本申请的拼接成型锂带中，本体区域的宽度基本上等于层压前相邻两个基础锂带的边缘相互层叠的层叠宽度，因此可以通过本体区域的宽度来体现拼接宽度的大小。当各本体区域的宽度为3.5mm以下时，能获得厚度一致性较高的拼接成型锂带。
在一些实施方式中，各本体区域的宽度可以≤3.5mm，≤3mm，≤2.8mm，≤2.5mm，≤2.3mm，≤2mm，≤1.8mm，或≤1.5mm。各本体区域的宽度可以≥0.1mm，≥0.3mm，≥0.5mm，≥0.7mm，≥0.9mm，≥1.0mm，或≥1.1mm。
可选的，各本体区域的宽度为0.1mm～3.5mm，例如1mm～3mm，或1mm～2mm等。各本体区域的宽度适当，能在使拼接成型锂带具有较好的厚度一致性的同时，还具有较高的拼接强度及力学性能。
在一些实施方式中，拼接区包括沿拼接成型锂带的厚度方向相对的两个凸出部。两个凸出部分别凸出于非拼接区在拼接成型锂带的厚度方向上的两个表面。也就是，其中一个凸出部凸出于非拼接区在拼接成型锂带厚度方向上的一侧的表面，另一个凸出部凸出于非拼接区的与前述一侧表面相对的另一侧表面。
各凸出部在拼接成型锂带厚度方向上的横截面呈梯形或类梯形。其中，梯形或类梯形的上底对应的区域即为拼接区的本体区域，梯形或类梯形的两侧腰对应的区域分别为拼接区的过渡区域。在一些可选的实施例中，梯形或类梯形的下底角θ为0.02度以下，例如2×10 -3度以下，再例如1×10 -4度～2×10 -3度，或1×10 -4度～9×10 -4度等。
拼接区的截面角度θ适当，则拼接区的横向厚度变化对拼接成型锂带的厚度一致性影响较小，能进一步提高拼接成型锂带的厚度一致性。
可以用本领域公知的仪器及方法进行测定拼接区的下底角θ。例如可以采用如下的方法测定下底角θ：取拼接成型锂带样品，并对样品进行裁切获取其横截面；测量过渡区域在拼接成型锂带宽度方向上的尺寸并记为l 1，测量凸出部在拼接成型锂带厚度方向上的尺寸并记为l 2；之后根据下述公式计算θ：
Figure PCTCN2020103483-appb-000005
在一些实施方式中，基础锂带为长条状，基础锂带沿拼接成型锂带的宽度方向进行拼接。即，拼接成型锂带为由两个以上的基础锂带在自身宽度方向上相互拼接成型，拼接区和非拼接区在拼接成型锂带自身宽度方向上交替分布。这样的拼接成型锂带整体上的厚度一致性较高。
在一些实施方式中，以拼接成型锂带自身宽度方向上的侧边沿为基准，本体区域在宽度方向上的位置波动在1mm以内。
拼接区在宽度方向上的位置波动可通过以下方法测试得到，方法包括：通过尺寸量具(如软尺等，测试精度例如为0.1mm)测试本体区域一侧边沿与同侧或相对侧拼接成型锂带边沿之间的距离，在拼接成型锂带的长度方向上每隔0.2m～0.5m(本领域技术人员可根据需求调整该测试间隔)测试一个数值；测试得到的多个数值中的最大值与最小值之差为小于或等于1mm。由于层压后本体区域的亮度较其他区域的亮度大，因此能很方便地区分本体区域的边沿。
本体区域的位置波动在1mm以内，即拼接区基本上是沿拼接成型锂带的长度方向上的一条直线区域。这样的拼接成型锂带的整体厚度一致性得到进一步提高。
基础锂带的莫氏硬度为0.6～2.5时，例如0.6～2.0，0.6～1.5，或0.6～1.0等，还适于使拼接区的下底角θ满足前文所述的要求。此外，基础锂带的莫氏硬度为0.6～2.5时，例如0.6～2.0，0.6～1.5，或0.6～1.0等，还有利于使拼接区的本体区域的位置波动在1mm以内。
可以理解的是，本申请的拼接成型锂带中，对基础锂带的形状及其拼接方向并没有特别的限制。基础锂带可以是任意的形状，如三角形、四边形、五边形、不规则多边形等。基础锂带的拼接方向可以是沿拼接成型锂带的宽度方向或长度方向，或者基础锂带的拼接方向是其他任意的方向。
本申请第二方面的实施例提供一种拼接成型锂带的制备方法，通过该制备方法能够获得上述任意的拼接成型锂带。本申请的一种拼接成型锂带的制备方法包括以下步骤：
S10，提供两个以上的基础锂带，各基础锂带的厚度波动为5％以下。
在步骤S10，基础锂带可以为金属锂带或锂合金带。锂合金带可以采用前文所述的锂合金带。
在步骤S10，可选的，基础锂带的厚度波动为3％以下，或2.5％以下等。
在步骤S10，可选的，基础锂带的宽度为80mm～160mm，80mm～130mm，或80mm～100mm等。
在步骤S10，可选的，基础锂带的莫氏硬度为0.6～2.5，0.6～2.0，0.6～1.5，或0.6～1.0等。
在步骤S10，可选的，基础锂带的厚度为0.2mm～4mm，0.5mm～3mm，或1mm～2mm等。
在本文中，基础锂带可以商购获得，也可以采用本领域已知的方法制备得到。作为基础锂带的制备方法的一个示例，可以将第一基材、待辊压锂片及第二基材依次层叠放置，并通过辊压装置进行辊压，使三者层合在一起；之后将第二基材剥离。其中，在层叠结构中，待辊压锂片的两侧分别被第一基材及第二基材完全覆盖。
第一基材可以为高分子膜片、金属膜片或无机材料膜片。例如，第一基材可以采用特氟龙、聚乙烯、聚丙烯、聚氨酯、聚四氟乙烯、聚芳砜、聚对苯二甲酸乙二醇醚、丙烯腈-丁二烯-苯乙烯共聚物、聚酰亚胺和聚醚砜中的一种或几种。
第二基材可以为高分子膜片、金属膜片或无机材料膜片。例如，第二基材可以采用特氟龙、聚乙烯、聚丙烯、聚氨酯、聚四氟乙烯、聚芳砜、聚对苯二甲酸乙二醇醚、丙烯腈-丁二烯-苯乙烯共聚物、聚酰亚胺和聚醚砜中的一种或几种。
通过辊压装置对第一基材、待辊压锂片及第二基材的层叠结构进行辊压的过程中，工作辊的加热温度例如为35℃～120℃。辊压压力可以在0.2MPa～1.5MPa。工作辊的速度可以在0.001m/min～60m/min。工作辊之间的间隙可以为大于0且小于等于5mm。
S20，将两个以上的基础锂带依次拼接，使相邻两个基础锂带的边缘相互层叠，经压合，得到拼接成型锂带。
在步骤S20，将两个以上的基础锂带依次拼接，其中每相邻两个基础锂带的边缘相互层叠，层叠的宽度可以为3.5mm以下，例如0.1mm～3mm，1mm～3mm，0.1mm～2mm，0.1mm～1mm，或1mm～2mm等。对拼接好的多个基础锂带进行压合，使每相邻两个基础锂带的层叠边缘相互层合为一体。
在步骤S20，压合可以采用本领域已知的装置及方法进行，如辊压装置。压合的温度可以为常温，20℃～30℃，或20℃～25℃。层压的压力可以根据基础锂带的材料、厚度等进行调节。例如在一些实施例中，层压的压力可以为0.9吨～2吨，如1吨～1.5吨。其中，1吨压力相当于9.8KN压力。
在一些实施例中，在步骤S20，两个以上的基础锂带可以为沿自身宽度方向依次拼接。
在一些实施例中，在步骤S20包括：
S210，将两个以上的基础锂带沿自身宽度方向依次拼接，使相邻两个基础锂带的边缘相互层叠且层叠宽度为3.5mm以下，例如0.1mm～3mm，1mm～3mm，0.1mm～2mm，0.1mm～1mm，或1mm～2mm等。
S220，对拼接后的两个以上基础锂带进行纠偏，以最外侧基础锂带的外侧边沿为基准，相邻两个基础锂带的边缘相互层叠的层叠区域在宽度方向上的位置波动在1mm以内。
相邻两个基础锂带的边缘相互层叠的层叠区域在宽度方向上的位置波动可以采用如下方法测试得到，方法包括：通过尺寸量具(如软尺、CCD图像传感器等，测试精度例如为0.1mm)测试相邻两个基础锂带的层叠区域的一侧边沿与最外侧基础锂带的外侧边沿之间的距离，在基础锂带的长度方向上每隔0.2m～0.5m(本领域技术人员可根据需求调整该测试间隔)测试一个数值；测试得到的多个数值中的最大值与最小值之差为小于或等于1mm。最外侧基础锂带可以是与层叠区域的所述一侧边缘同侧或不同侧的最外侧基础锂带。最外侧基础锂带的外侧边沿对应拼接成型锂带的外侧边沿。
使相邻两个基础锂带的层叠区域在宽度方向上的位置波动在1mm以内，有利于使拼接成型锂带以自身宽度方向上的侧边沿为基准，其本体区在宽度方向上的位置波动在1mm以内，从而使获得的拼接成型锂带具有较好的整体厚度一致性。
在步骤S220，纠偏可以采用纠偏传感器等进行。
S230，对拼接后的两个以上基础锂带进行辊压，得到拼接成型锂带。
在步骤S230，辊压可以采用本领域已知的装置及方法进行，如辊压装置。辊压的温度可以为常温，20℃～30℃，或20℃～25℃。辊压的压力可以为0.9吨～2吨，如1吨～1.5吨。
本申请的制备方法中，将基础锂带拼接后，经压合，即可获得宽度较大且厚度一致性良好的拼接成型锂带。该制备方法可操作性高，能提高生产效率，降低生产成本。此外，采用本申请的制备方法制备厚度一致性良好的宽幅锂带，还能获得较高的生产优率。因此，本申请在提高宽幅锂带的厚度一致性的同时，还解决了现有技术中直接加工宽度较大的金属锂带的生产优率极低、生产加工成本高的问题。
本申请第一方面的实施例中的其它技术特征也可以应用于本申请第二方面的实施例中，在此不再赘述。
本申请的第三方面提供一种负极极片，其包括负极集流体；设置于所述负极集流体 上且包含负极活性材料的负极活性物质层；设置于所述负极活性物质层上的锂基金属层，其中，所述锂基金属层为由本申请所述的拼接成型锂带层合于所述负极活性物质层的表面而形成。
负极集流体具有在自身厚度方向上相对的两个表面，负极活性物质层可以设置于两个表面中的任意一者上，也可以是分别设置于两个表面。锂基金属层设置于负极活性物质层的背离负极集流体的表面。
需要说明的是，本申请第三方面所述的负极极片是尚未经过电解液浸润的负极极片，而注入电解液后，负极活性物质层与锂基金属层之间存在电势差，可自发进行锂基金属层对负极活性物质层的预嵌锂，锂基金属层的部分或全部金属锂预嵌入负极活性材料中，形成预嵌锂的负极活性材料。
本申请的负极极片由于采用了本申请所述的拼接成型锂带，其可以兼具更大的宽度和较高的预嵌锂均匀性。因此，采用该负极极片的锂离子电池，能同时获得较高的能量密度和循环性能。
本申请的负极极片中，所述负极集流体可以采用具有良好导电性及机械强度的材质，例如铜箔。
本申请的负极极片对负极活性材料的种类没有特别限制，可使用本领域已知的负极活性材料。作为示例，负极活性材料可选自天然石墨、人造石墨、软碳、硬碳、中间相碳微球、纳米碳、单质硅、硅氧化合物、硅碳复合物、硅合金、单质锡、锡氧化合物、锡碳复合物、锡合金和钛酸锂中的一种或几种。
本申请的负极极片中，负极活性物质层还可以包括可选的导电剂、可选的粘结剂和可选的增稠剂，对它们的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，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一种或几种。粘结剂可选自聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚乙烯醇(PVA)、丁苯橡胶(SBR)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或几种。增稠剂可选自羧甲基纤维素钠(CMC-Na)。
可以按照本领域常规方法制备负极极片。例如将负极活性材料及可选的导电剂、可选的粘结剂和可选的增稠剂分散于溶剂中，溶剂可以是去离子水，形成均匀的负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，形成负极活性物质层；将本申请所述的拼接成型锂带层合于负极活性物质层的背向负极集流体的表面，形成锂基金属层，得到负极极片。其中，可采用辊压的方式将拼接成型锂带压合在负极活性物 质层的表面。
本申请的第四方面提供一种电芯，其包括本申请任意一种负极极片。在一些实施方式中，电芯由正极极片、负极极片及隔离膜经叠片工艺或卷绕工艺而形成，隔离膜介于正极极片和负极极片之间起到隔离的作用。
需要说明的是，本申请第四方面的电芯是指尚未经过电解液浸润的电芯。本申请的电芯在狭义上可仅包括正极极片、隔离膜和负极极片，但是本申请的电芯在广义上还可包括其它的结构，例如端子组件、保护壳组件等。
本申请的电芯中，所述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且包括正极活性材料的正极活性物质层。
本申请的电芯中，所述正极集流体可以采用具有良好导电性及机械强度的材质，例如铝箔。
本申请的电芯对正极活性材料的具体种类不做具体限制，可采用本领域已知的正极活性材料，本领域技术人员可以根据实际需求进行选择。作为示例，正极活性材料可选自锂过渡金属氧化物及其改性材料，所述改性材料可以是对锂过渡金属氧化物进行包覆改性和/或掺杂改性。可选的，所述锂过渡金属氧化物可选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物中的一种或几种。
本申请的电芯中，所述正极活性物质层还可包括可选的粘结剂和可选的导电剂，对粘结剂、导电剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，粘结剂可选自聚偏氟乙烯(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-六氟丙烯共聚物中的一种或几种。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一种或几种。
可以按照本领域常规方法制备正极极片。例如将正极活性材料及可选的导电剂和可选的粘结剂分散于溶剂(例如N-甲基吡咯烷酮，简称NMP)中，形成均匀的正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，得到正极极片。
本申请的电芯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隔离膜，例如玻璃纤维膜、无纺布膜、聚乙烯薄膜、聚丙烯薄膜、聚偏二氟乙烯薄膜、及它们的多层复合薄膜中的一种或几种。
本申请的第五方面提供一种锂离子电池，其包括电芯和电解液，其中电芯采用本申 请任意一种或几种电芯。
本申请的锂离子电池由于采用了本申请的电芯，因而能兼具较高的能量密度和循环性能。
在本申请的锂离子电池中，电解液浸润于电芯中，在正极极片和负极极片起到传导离子的作用。所述电解液包括电解质锂盐和溶剂。
可选的，所述电解质锂盐选自LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或几种。
可选的，所述溶剂选自碳酸亚乙酯(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)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
所述电解液中还可选地包括添加剂，其中对添加剂的种类没有具体的限制，可根据需求进行选择。例如添加剂可以包括负极成膜添加剂，也可以包括正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温性能的添加剂、改善电池低温性能的添加剂等。
本申请对锂离子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3是作为一个示例的方形结构的锂离子电池5。
在一些实施例中，锂离子电池可包括外包装。该外包装用于封装正极极片、负极极片和电解质。
在一些实施例中，参照图4，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。
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芯52。电芯52封装于所述容纳腔。电解液浸润于电芯52中。锂离子电池5所含电芯52的数量可以为一个或几个，可根据需求来调节。
在一些实施例中，锂离子电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。锂离子电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，如可包括聚丙烯(PP)、聚对苯二甲酸丁二醇酯(PBT)、聚丁二酸丁二醇酯(PBS)等中的一种或几种。
在一些实施例中，锂离子电池可以组装成电池模块，电池模块所含锂离子电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图5是作为一个示例的电池模块4。参照图5，在电池模块4中，多个锂离子电池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锂离子电池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，多个锂离子电池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6和图7是作为一个示例的电池包1。参照图6和图7，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能够盖设于下箱体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。
本申请还提供一种装置，所述装置包括本申请所述的锂离子电池、电池模块或电池包。所述锂离子电池、电池模块或电池包可以用作所述装置的电源，也可以作为所述装置的能量存储单元。所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
所述装置可以根据其使用需求来选择锂离子电池、电池模块或电池包。
图8是作为一个示例的装置。该装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对锂离子电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用锂离子电池作为电源。
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
通过前文所述辊压成型的方法获得国二锂带(符合GB/T 20930-2015《锂带》中Li-2的锂带)，该国二锂带作为基础锂带。其中，基础锂带的宽度为80mm、设计厚度为2mm、TD方向的厚度波动A为1％。
将两个基础锂带的边缘相互层叠，层叠宽度为1mm。之后通过辊压使两基础锂带层合成为一个宽度为159mm的拼接成型锂带，辊压的压力为1.5吨。拼接成型锂带的非拼接区的TD方向厚度波动为1％，拼接成型锂带的B值为2％。
实施例2
与实施例1类似，不同的是，基础锂带的宽度为100mm、TD方向厚度波动为1.3％，其余参数详见表1。
实施例3
与实施例1类似，不同的是，基础锂带的宽度为130mm、TD方向厚度波动为1.5％，其余参数详见表1。
实施例4
与实施例1类似，不同的是，基础锂带的宽度为140mm、TD方向厚度波动为2.0％，其余参数详见表1。
实施例5
与实施例1类似，不同的是，基础锂带的宽度为160mm、TD方向厚度波动为3.0％，其余参数详见表1。
实施例6
与实施例1类似，不同的是，基础锂带的宽度为170mm、TD方向厚度波动为5.0％，其余参数详见表1。
实施例7
与实施例3类似，不同的是，基础锂带的莫氏硬度为0.8，其余参数详见表1。
实施例8
与实施例3类似，不同的是，基础锂带的莫氏硬度为1.0，其余参数详见表1。
实施例9
与实施例3类似，不同的是，基础锂带的莫氏硬度为1.2，其余参数详见表1。
实施例10
与实施例3类似，不同的是，基础锂带的莫氏硬度为2，其余参数详见表1。
实施例11
与实施例3类似，不同的是，基础锂带的莫氏硬度为2.5，其余参数详见表1。
实施例12
与实施例3类似，不同的是，两个基础锂带的边缘相互层叠的宽度为为0.1mm，其余参数详见表1。
实施例13
与实施例3类似，不同的是，两个基础锂带的边缘相互层叠的宽度为为2mm，其余参数详见表1。
实施例14
与实施例3类似，不同的是，两个基础锂带的边缘相互层叠的宽度为为3mm，其余参数详见表1。
实施例15
与实施例3类似，不同的是，两个基础锂带的边缘相互层叠的宽度为为3.5mm，其余参数详见表1。
实施例16
与实施例3类似，不同的是，基础锂带的设计厚度为0.2mm、TD方向厚度波动为3％，其余参数详见表1。
实施例17
与实施例3类似，不同的是，基础锂带的设计厚度为0.5mm、TD方向厚度波动为2.5％，其余参数详见表1。
实施例18
与实施例3类似，不同的是，基础锂带的设计厚度为1mm、TD方向厚度波动为1.7％，其余参数详见表1。
实施例19
与实施例3类似，不同的是，基础锂带的设计厚度为3mm、TD方向厚度波动为1.3％，其余参数详见表1。
实施例20
与实施例3类似，不同的是，基础锂带的设计厚度为4mm、TD方向厚度波动为1.1％，其余参数详见表1。
实施例21
与实施例3类似，不同的是，辊压压力为0.9吨，其余参数详见表1。
对比例1
将锂片进行辊压，采用一次成型直接加工宽度为259mm、设计厚度为2mm的宽幅锂带，宽幅锂带的厚度波动为23％(按照基础锂带的厚度波动的测定方法进行测定)，其余参数详见表1。制备宽幅锂带的锂片的莫氏硬度为0.6。
对比例2
与实施例1类似，不同的是，基础锂带的宽度为180mm、TD方向厚度波动为5.5％，其余参数详见表1。
对比例3
与实施例3类似，不同的是，基础锂带的厚度波动为10％，其余参数详见表1。
测试部分
(1)基础锂带宽度(软尺，精度0.1mm)
(2)各厚度(千分尺，精度0.001mm)
(3)基础锂带硬度(莫氏硬度计)
(4)拼接区本体区域的宽度(软尺，精度0.1mm)
(5)拼接成型锂带宽度(软尺，精度0.1mm)
表1
Figure PCTCN2020103483-appb-000006
表1中，实施例1～21与对比例2～3中拼接成型锂带的整体厚度波动等于厚度偏差B。
由实施例1～21与对比例1～3的比较可知，本申请采用基础锂带拼接的方式，并控制基础锂带的厚度波动A以及拼接区和非拼接区的厚度偏差B在特定范围内，所获得的拼接成型锂带能同时兼顾较大的宽度和良好的厚度一致性。
而对比例1中直接一次成型加工宽幅锂带，该宽幅锂带的厚度波动较大，厚度一致性 较差(如图2所示)。对比例2、3的基础锂带的厚度波动较大，同样导致拼接成型的宽幅锂带的厚度一致性变差。
由实施例1～6及对比例2的结果可知，基础锂带的宽度为170mm以下时，其厚度波动通常也较小，能改善拼接成型锂带的厚度一致性。
由实施例3、7～11的结果可知，基础锂带的硬度为0.6～2.5时，有利于改善拼接成型锂带的厚度一致性。
由实施例3、12～15的结果可知，基础锂带的层叠宽度为3.5mm以下时，能提高拼接成型锂带的厚度一致性。
由实施例3、16～20的结果可知，基础锂带的厚度会影响其自身的厚度波动，进而会影响拼接成型锂带的厚度一致性。基础锂带的厚度为4mm以下，且厚度波动为5％以下时，有利于提高拼接成型锂带的厚度一致性。
由实施例3和实施例21的结果可知，对拼接后的基础锂带的辊压压力会影响拼接成型锂带的厚度一致性。实施例21中的辊压压力较小，导致拼接区的厚度较大，所获得的拼接成型锂带的厚度一致性相对降低。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (18)

  1. 一种拼接成型锂带，由两个以上的基础锂带相互拼接成型；其中，
    所述基础锂带的厚度波动为5％以下；
    所述拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，所述拼接区的最大厚度H与所述非拼接区的最小厚度L之间满足：
    Figure PCTCN2020103483-appb-100001
  2. 根据权利要求1所述的拼接成型锂带，其中，所述拼接区包括本体区域及过渡区域，各所述拼接区的所述过渡区域与所述非拼接区相邻，各所述本体区域的宽度为0.1mm～3.5mm，可选为1mm～3mm。
  3. 根据权利要求1或2所述的拼接成型锂带，其中，所述拼接区包括沿所述拼接成型锂带的厚度方向相对的两个凸出部，所述两个凸出部分别凸出于所述非拼接区在所述厚度方向上的两个表面，且各所述凸出部在所述厚度方向上的横截面呈梯形或类梯形，各所述梯形或类梯形的下底角为0.02度以下，可选为2×10 -3度以下，或1×10 -4度～2×10 -3度。
  4. 根据权利要求1-3任一项所述的拼接成型锂带，其中，所述基础锂带的厚度波动为3％以下，可选为2.5％以下。
  5. 根据权利要求1-4任一项所述的拼接成型锂带，其中，所述拼接区的最大厚度H与所述非拼接区的最小厚度L之间满足：
    Figure PCTCN2020103483-appb-100002
  6. 根据权利要求1-5任一项所述的拼接成型锂带，其中，所述基础锂带的宽度为170mm以下，可选为80mm～160mm，或80mm～130mm。
  7. 根据权利要求1-6任一项所述的拼接成型锂带，其中，所述基础锂带的厚度为0.2mm～4mm，可选为0.5mm～3mm，或1mm～2mm。
  8. 根据权利要求1-7任一项所述的拼接成型锂带，其中，所述基础锂带的莫氏硬度为0.6～2.5，可选为0.6～2.0，0.6～1.5，或0.6～1.0。
  9. 根据权利要求2所述的拼接成型锂带，其中，所述拼接成型锂带为由两个以上的所述基础锂带在自身宽度方向上相互拼接成型，所述拼接区和非拼接区在所述拼接成型锂带自身宽度方向上交替分布。
  10. 根据权利要求9所述的拼接成型锂带，其中，以所述拼接成型锂带自身宽度方向上的侧边沿为基准，所述本体区域在所述宽度方向上的位置波动在1mm以内。
  11. 一种拼接成型锂带的制备方法，包括：
    提供两个以上的基础锂带，各所述基础锂带的厚度波动为5％以下；
    将两个以上的所述基础锂带依次拼接，使相邻两个所述基础锂带的边缘相互层叠，经压合，得到所述拼接成型锂带；
    其中，所述拼接成型锂带具有沿拼接方向交替分布的拼接区和非拼接区，所述拼接区的最大厚度H与所述非拼接区的最小厚度L之间满足：
    Figure PCTCN2020103483-appb-100003
  12. 根据权利要求11所述的方法，其中，
    两个以上的所述基础锂带为沿自身宽度方向依次拼接，相邻两个所述基础锂带的边缘相互层叠的宽度为0.1mm～3.5mm；
    在所述压合之前还包括对拼接后的两个以上所述基础锂带进行纠偏，以最外侧基础锂带的外侧边沿为基准，相邻两个所述基础锂带的边缘相互层叠的层叠区域在所述宽度方向上的位置波动在1mm以内。
  13. 一种负极极片，包括：
    负极集流体；
    负极活性物质层，设置于所述负极集流体；
    锂基金属层，设置于所述负极活性物质层，其中，所述锂基金属层为由根据权利要求1-10任一项所述的拼接成型锂带或根据权利要求11-12任一项所述制备方法得到的拼接成型锂带层合于所述负极活性物质层的表面而形成。
  14. 一种电芯，包括负极极片，所述负极极片为根据权利要求13所述的负极极片。
  15. 一种锂离子电池，包括电芯和电解液，所述电芯采用根据权利要求14所述的电芯。
  16. 一种电池模块，包括根据权利要求15所述的锂离子电池。
  17. 一种电池包，包括根据权利要求16所述的电池模块。
  18. 一种装置，包括根据权利要求15所述的锂离子电池、根据权利要求16所述的电池模块、或根据权利要求17所述的电池包中的至少一种。
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