WO2021184267A1 - 电极组件及具有该电极组件的电池 - Google Patents

电极组件及具有该电极组件的电池 Download PDF

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Publication number
WO2021184267A1
WO2021184267A1 PCT/CN2020/080064 CN2020080064W WO2021184267A1 WO 2021184267 A1 WO2021184267 A1 WO 2021184267A1 CN 2020080064 W CN2020080064 W CN 2020080064W WO 2021184267 A1 WO2021184267 A1 WO 2021184267A1
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WIPO (PCT)
Prior art keywords
pole piece
electrode assembly
area
polymer layer
sided
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PCT/CN2020/080064
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English (en)
French (fr)
Inventor
余舒娴
王坤
秦一鸣
明帮生
Original Assignee
宁德新能源科技有限公司
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Application filed by 宁德新能源科技有限公司 filed Critical 宁德新能源科技有限公司
Priority to CN202080005383.5A priority Critical patent/CN113196531B/zh
Priority to EP20920753.9A priority patent/EP3920305A4/en
Priority to PCT/CN2020/080064 priority patent/WO2021184267A1/zh
Publication of WO2021184267A1 publication Critical patent/WO2021184267A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/62—Heating or cooling; Temperature control specially adapted for specific applications
    • H01M10/623—Portable devices, e.g. mobile telephones, cameras or pacemakers
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/654—Means for temperature control structurally associated with the cells located inside the innermost case of the cells, e.g. mandrels, electrodes or electrolytes
    • 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
    • H01M10/60—Heating or cooling; Temperature control
    • H01M10/65—Means for temperature control structurally associated with the cells
    • H01M10/658—Means for temperature control structurally associated with the cells by thermal insulation or shielding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2200/00—Safety devices for primary or secondary batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • This application relates to the field of batteries, and in particular to an electrode assembly and a battery with the electrode assembly.
  • Lithium-ion batteries are widely used in various portable electronic devices due to their advantages of high energy density, volumetric energy density, and many cycles of use. Therefore, with the rapid development of portable electronic devices, the requirements for batteries have also increased. However, the pole pieces in the current battery often suffer from deformation and tearing after repeated cycles of use, which seriously affects the number of cycles and safety performance of the battery.
  • the application also provides a battery with the electrode assembly.
  • An electrode assembly comprising a winding unit formed by winding a stacked first pole piece, an isolation membrane, and a second pole piece.
  • the first pole piece includes a first current collector and is arranged on the first current collector
  • the first active material layer on both sides, the first current collector includes a first single-sided area and a first blank area connected to the first single-sided area, the first single-sided area facing away from the winding unit
  • the surface of the center is not provided with a first active material layer;
  • the first single-sided area and the first blank area are located at the outermost circle of the winding unit;
  • the electrode assembly further includes a polymer layer disposed on both sides of the first blank area and a surface of the first single-sided area facing away from the center of the winding unit.
  • the first current collector further includes a first double-sided region from the winding start end of the first pole piece to the first single-sided region, and the polymer layer is further disposed on the first single-sided region. Both sides of a double-sided zone.
  • the winding unit includes a horizontal area and corner areas located at both ends of the horizontal area, and the polymer layer is further disposed on the first pole piece located in the corner area.
  • the first pole piece is a cathode pole piece.
  • the polymer layer is polyvinylidene fluoride, styrene butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile or polyacrylate.
  • the polymer layer to form a coating weight of 1mg / 1540.25mm 2 -5mg / 1540.25mm 2 .
  • the electrode assembly further includes an adhesive member disposed between the polymer layer and the first pole piece.
  • the adhesive member is polyvinyl alcohol or polytetrafluoroethylene.
  • a battery includes a packaging bag and an electrolyte contained in the packaging bag; the battery also includes the above-mentioned electrode assembly, and the electrode assembly is contained in the packaging bag.
  • the thickness of the polymer layer is 1.7 ⁇ m-8.5 ⁇ m.
  • the first pole piece and the second pole piece are enlarged.
  • the gap between the pole pieces creates space for the expansion of the first pole piece and the second pole piece during the cycle, thereby reducing the risk of the first pole piece and the second pole piece being deformed and torn due to cyclic expansion, and then Effectively improve the cycle life and safety performance of the battery.
  • arranging the polymer layer on the outermost ring of the winding unit also plays a role of heat insulation.
  • FIG. 1 is a schematic diagram of the structure of a battery according to an embodiment of the application.
  • Fig. 2 is a schematic partial cross-sectional view of the first pole piece shown in Fig. 1.
  • FIG 3 is a schematic partial cross-sectional view of a first pole piece according to an embodiment of the application.
  • FIG. 4 is a schematic diagram of the structure of an electrode assembly according to an embodiment of the application.
  • Fig. 5 is a schematic partial cross-sectional view of a winding unit according to an embodiment of the application.
  • Fig. 6 is a schematic cross-sectional view of the second pole piece shown in Fig. 1.
  • Example 7 is a partial scanning electron micrograph of the polymer layer on the first pole piece in Example 3 before formation.
  • Figure 8 is a partial scanning electron microscope image of the polymer layer on the first pole piece in Example 3 after formation.
  • Figure 9 is an elemental analysis spectrum of the first pole piece in Example 3 after chemical conversion.
  • Figure 10 is an elemental analysis spectrum of the first pole piece in Example 4 after chemical conversion.
  • FIG. 11 is a graph of the cycle performance of the battery 100 in Example 3 and Comparative Example 1.
  • FIG. 11 is a graph of the cycle performance of the battery 100 in Example 3 and Comparative Example 1.
  • FIG. 12 is a CT image of the battery 100 in Comparative Example 1.
  • FIG. 12 is a CT image of the battery 100 in Comparative Example 1.
  • FIG. 13 is a CT image of the battery 100 in the third embodiment.
  • the first single-sided area 1111 is the first single-sided area 1111
  • the first active material layer 112 is the first active material layer 112
  • the present application provides a battery 100 including an electrode assembly 10, a packaging bag 20 and an electrolyte 30 contained in the packaging bag 20.
  • the battery 100 is a lithium ion battery.
  • the electrode assembly 10 is contained in the packaging bag 20.
  • the electrode assembly 10 includes a winding unit 14 formed by winding a stacked first pole piece 11, an isolation film 12, and a second pole piece 13, and a polymer layer 15.
  • the isolation film 12 is located between the first pole piece 11 and the second pole piece 13.
  • the first pole piece 11 includes a first current collector 111 and a first active material layer 112 disposed on both sides of the first current collector 111.
  • the first pole piece 11 is a cathode pole piece.
  • the first current collector 111 includes a first single-sided area 1111 and a first blank area 1112 connected to the first single-sided area 1111.
  • the first single-sided area 1111 and the first blank area 1112 are located at the outermost circle of the winding unit 14.
  • the surface of the first single-sided region 1111 facing away from the center of the winding unit 14 is not provided with a first active material layer 112.
  • the first active material layer 112 is not provided on both sides of the first blank area 1112.
  • the polymer layer 15 is disposed on both sides of the first blank area 1112 and the surface of the first single-sided area 1111 facing away from the center of the winding unit 14.
  • the polymer layer 15 is polyvinylidene fluoride, styrene butadiene rubber, carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile or polyacrylate.
  • the formation of the polymer layer 15 includes the following steps:
  • the polymer layer 15 melts and diffuses at a high temperature, so that the thickness of the polymer layer 15 becomes thinner than that during drying, thus increasing the size of the first pole piece 11 and the second pole piece 11 and the second pole piece.
  • the gap between the sheets 13 creates space for the expansion of the first pole piece 11 and the second pole piece 13 in the cycle, thereby reducing the deformation and tearing of the first pole piece 11 and the second pole piece 13 due to the cyclic expansion Therefore, the cycle life and safety performance of the battery 100 are effectively improved.
  • disposing the polymer layer 15 on the outermost ring of the winding unit 14 also plays a role of heat insulation.
  • the weight of the paint sprayed to form the polymer layer 15 is controlled at 1 mg/1540.25 mm 2 to 5 mg/1540.25 mm 2 .
  • the thickness of the polymer layer 15 is 1.7 ⁇ m-8.5 ⁇ m.
  • the weight of the paint sprayed to form the polymer layer 15 is 1.5 mg/1540.25 mm 2 .
  • the weight of the paint sprayed to form the polymer layer 15 is 2 mg/1540.25 mm 2 .
  • the weight of the paint sprayed to form the polymer layer 15 is 2.5 mg/1540.25 mm 2 .
  • the weight of the paint sprayed to form the polymer layer 15 is 3 mg/1540.25 mm 2 .
  • the first current collector 111 further includes a first double-sided region 1113 from the winding start end of the first pole piece 11 to the first single-sided region 1111. Both sides of the first double-sided region 1113 are provided with first active material layers 112. The polymer layer 15 is also arranged on both sides of the first double-sided area 1113 to further avoid the risk of deformation and tearing of the first pole piece 11 and the second pole piece 13 due to cyclic expansion.
  • the winding unit 14 includes a horizontal area 141 and corner areas 142 located at both ends of the horizontal area 141.
  • the polymer layer 15 is also disposed on the first pole piece 11 located in the corner area 142. Among them, due to the small gap between the first pole piece 11 and the second pole piece 13 in the corner area 142, the electrolyte 30 is squeezed out, and the corner area 142 is caused by the lack of the electrolyte 30 and lithium evolution occurs. Phenomenon, thereby affecting the cycle capacity of the battery 100.
  • the polymer layer 15 is disposed on the first pole piece 11 located in the corner area 142, so that when the battery 100 is formed, the corners are enlarged due to the melting and diffusion of the polymer layer 15 at a high temperature.
  • the gap between the first pole piece 11 and the second pole piece 13 at the area 142 effectively avoids the problem of lithium evolution in the corner area 142, thereby greatly improving the cycle capacity of the battery 100.
  • the electrode assembly 10 further includes an adhesive member 16.
  • the adhesive 16 is disposed between the polymer layer 15 and the first pole piece 11 to strengthen the connection force between the polymer layer 15 and the first pole piece 11.
  • the adhesive 16 is polyvinyl alcohol or polytetrafluoroethylene.
  • the battery 100 includes a packaging bag 20 and an electrolyte 30 and an electrode assembly 10 contained in the packaging bag 20.
  • the electrode assembly 10 includes a polymer layer 15 and a winding unit 14 formed by winding a stacked first pole piece 11, an isolation film 12, and a second pole piece 13.
  • the isolation film 12 is located between the first pole piece 11 and the second pole piece 13.
  • the first pole piece 11 includes a first current collector 111 and a first active material layer 112 disposed on both sides of the first current collector 111.
  • the first pole piece 11 is a cathode pole piece.
  • the first current collector 111 includes a first single-sided area 1111 and a first blank area 1112 connected to the first single-sided area 1111.
  • the first single-sided area 1111 and the first blank area 1112 are located at the outermost circle of the winding unit 14. Wherein, the surface of the first single-sided region 1111 facing away from the center of the winding unit 14 is not provided with a first active material layer 112.
  • the second pole piece 13 includes a second current collector 131 and a second active material layer 132 disposed on both sides of the second current collector 131.
  • the second current collector 131 includes a second blank area 1311, a second single-sided area 1312, and a second double-sided area 1313 arranged in sequence.
  • the second active material layer 132 is not provided on both sides of the second blank area 1311.
  • the surface of the second single-sided region 1312 facing the center of the winding unit 14 is not provided with a second active material layer 132.
  • the second active material layer 132 is provided on both sides of the second double-sided area 1313.
  • the polymer layer 15 is disposed on both sides of the first blank area 1112 and the surface of the first single-sided area 1111 facing away from the center of the winding unit 14. Wherein, the polymer layer 15 is polyvinylidene fluoride.
  • Example 1 the formation of the polymer layer 15 includes the following steps:
  • the first pole piece 11 is cold-pressed; then, the surface of the first blank area 1112 and the surface of the first single-sided area 1111 facing away from the center of the winding unit 14 is uniformly sprayed with polypolarization.
  • Vinyl fluoride wherein the weight of the polyvinylidene fluoride sprayed is controlled at 1.5 mg/1540.25 mm 2 ; finally, the polyvinylidene fluoride on the first single-sided area 1111 and the first blank area 1112 is dried to form the Polymer layer 15.
  • the thickness of one side of the polymer layer 15 after drying is 260 ⁇ m.
  • Example 1 after the above-mentioned battery 100 was subjected to chemical conversion treatment, the thickness of the polymer layer was reduced to 2.6 ⁇ m.
  • Embodiment 2 The difference between Embodiment 2 and Embodiment 1 lies in the position where the polymer layer 15 is arranged.
  • the winding unit 14 includes a horizontal area 141 and corner areas 142 located at both ends of the horizontal area 141.
  • the polymer layer 15 in Embodiment 2 is further disposed on the first pole piece 11 in the corner area 142.
  • Embodiment 3 The difference between Embodiment 3 and Embodiment 1 lies in the position where the polymer layer 15 is arranged and the structure of the first pole piece 11.
  • the first current collector 111 further includes a first double-sided region 1113 from the winding start end of the first pole piece 11 to the first single-sided region 1111.
  • the polymer layer 15 in Embodiment 3 is further disposed on both sides of the first double-sided region 1113.
  • the first pole piece 11 before formation in Example 3 is photographed by a scanning electron microscope to obtain a scanning electron microscope image as shown in FIG. 7;
  • Figure 8 shows the scanning electron micrograph.
  • Fig. 7 and Fig. 8 it can be seen that the polyvinylidene fluoride particles on the surface of the first pole piece 11 after the formation are significantly smaller than before the formation. That is, after chemical conversion, the thickness of the polymer layer 15 will be reduced, so that the gap between the first pole piece 11 and the second pole piece 13 will increase, which in turn will provide the first pole piece 11 and the second pole piece 13 The expansion in the cycle creates space.
  • Example 4 The difference between Example 4 and Example 3 is that the weight of the polyvinylidene fluoride sprayed in Example 4 is controlled at 2.5 mg/1540.25 mm 2 .
  • an energy spectrometer is used to perform elemental analysis on the first pole piece 11 in the battery 100 after chemical conversion in Example 3, and a spectrum as shown in FIG. 9 is obtained.
  • Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that the battery 100 in Comparative Example 1 does not have a polymer layer 15.
  • the black line is the change curve of the capacity retention rate of the battery 100 in Example 3 under different cycles
  • the gray line is the change curve of the capacity retention rate of the battery 100 in Comparative Example 1 under different cycles. According to the two lines, it can be seen that the arrangement of the polymer layer 15 can further improve the cycle performance of the battery 100.
  • each pole piece in Comparative Example 1 is severely deformed; referring to FIG. 13, it can be seen that each pole piece in Example 3 is flat and has no deformation. It can be seen that the arrangement of the polymer layer 15 can further solve the problem of deformation and tearing of the pole piece due to cyclic expansion.
  • the hot box test is performed on the battery 100 in Example 3 and Comparative Example 1.
  • the specific test includes the following steps:
  • the fully charged batteries 100 in Comparative Example 1 and Example 3 were respectively placed in a hot box, and then raised from room temperature to 130°C, 132°C or 135°C at a rate of 5 ⁇ 2°C/min, and kept for 30 minutes. If the battery 100 does not catch fire or explode, it is determined that the battery 100 has passed the hot box test.
  • Table 1 shows the test results (pass rates) of the battery 100 of Comparative Example 1 and Example 3 in the hot box test at different temperatures. It can be seen that the arrangement of the polymer layer 15 also has a certain heat insulation effect.

Abstract

一种电极组件(10)，包括由叠置的第一极片(11)、隔离膜(12)和第二极片(13)卷绕形成的卷绕单元(14)。所述第一极片(11)包括第一集流体(111)及设置于所述第一集流体(111)两侧的第一活性物质层(112)。所述第一集流体(111)包括第一单面区(1111)及连接所述第一单面区(1111)的第一空白区(1112)。所述第一单面区(1111)背对所述卷绕单元(14)中心的表面未设置第一活性物质层(112)。所述第一单面区(1111)和所述第一空白区(1112)位于所述卷绕单元(14)的最外圈。所述电极组件(10)还包括聚合物层(15)，所述聚合物层(15)设置于所述第一空白区(1112)的两侧以及所述第一单面区(1111)背对所述卷绕单元(14)中心的表面。一种具有该电极组件(10)的电池(100)。

Description

电极组件及具有该电极组件的电池 技术领域
本申请涉及电池领域，尤其涉及电极组件及具有该电极组件的电池。
背景技术
锂离子电池，由于其具有高能量密度和体积能量密度、循环使用次数多等优点，被广泛应用于各类便携式电子设备中。因此，随着便携式电子设备的迅速发展，对电池的要求也随之提高。然而，目前的电池中的极片，在多次循环使用后经常出现变形及被撕裂的问题，从而严重影响到电池的循环使用次数及安全性能。
发明内容
有鉴于此，有必要提供一种电极组件，以解决上述问题。
本申请还提供了一种具有该电极组件的电池。
一种电极组件，包括由叠置的第一极片、隔离膜和第二极片卷绕形成的卷绕单元，所述第一极片包括第一集流体及设置于所述第一集流体两侧的第一活性物质层，所述第一集流体包括第一单面区及连接所述第一单面区的第一空白区，所述第一单面区背对所述卷绕单元中心的表面未设置第一活性物质层；
所述第一单面区和所述第一空白区位于所述卷绕单元的最外圈；
所述电极组件还包括聚合物层，所述聚合物层设置于所述第一空白区的两侧以及所述第一单面区背对所述卷绕单元中心的表面。可选地，所述第一集流体还包括由所述第一极片的卷绕起始端到所述第一单面区的第一双面区，所述聚合物层还设置于所述第一双面区的两侧。
可选地，所述卷绕单元包括水平区域及位于所述水平区域两端 的拐角区域，所述聚合物层还设置于位于所述拐角区域的第一极片。可选地，所述第一极片为阴极极片。
可选地，所述聚合物层为聚偏氟乙烯、丁苯橡胶、羧甲基纤维素、聚丙烯酸、聚丙烯腈或聚丙烯酸酯。
可选地，形成所述聚合物层的涂料的重量为1mg/1540.25mm 2-5mg/1540.25mm 2。
可选地，所述电极组件还包括粘接件，所述粘接件设置于所述聚合物层和所述第一极片之间。
可选地，所述粘接件为聚乙烯醇或聚四氟乙烯。
一种电池，包括包装袋及容纳于所述包装袋内的电解液；所述电池还包括上述所述的电极组件，所述电极组件容纳于所述包装袋内。
可选地，所述电池经化成后，所述聚合物层的厚度为1.7μm-8.5μm。
综上所述，通过将聚合物层设置于所述第一空白区的两侧以及所述第一单面区背对所述卷绕单元中心的表面，增大了第一极片和第二极片之间的空隙，给第一极片和第二极片在循环中的膨胀制造了空间，从而降低了第一极片和第二极片因循环膨胀变形及被撕裂的风险，进而有效提升电池的循环使用寿命及安全性能。此外，将所述聚合物层设置于所述卷绕单元的最外圈还起到隔热的作用。
附图说明
图1为本申请一实施方式的电池的结构示意图。
图2为图1所示第一极片的部分剖面示意图。
图3为本申请一实施方式的第一极片的部分剖面示意图。
图4为本申请一实施方式的电极组件的结构示意图。
图5为本申请一实施方式的卷绕单元的部分剖面示意图。
图6为图1所示第二极片的剖面示意图。
图7为实施例3中第一极片上的聚合物层在化成前的部分扫描电镜图。
图8为实施例3中第一极片上的聚合物层在化成后的部分扫描 电镜图。
图9为经化成后实施例3中第一极片的元素分析谱图。
图10为经化成后实施例4中第一极片的元素分析谱图。
图11为实施例3及对比例1中的电池100的循环性能图。
图12为对比例1中电池100的CT图。
图13为实施例3中电池100的CT图。
主要元件符号说明
电池                        100
电极组件                    10
第一极片                    11
第一集流体                  111
第一单面区                  1111
第一空白区                  1112
第一双面区                  1113
第一活性物质层              112
隔离膜                      12
第二极片                    13
第二集流体                  131
第二空白区                  1311
第二单面区                  1312
第二双面区                  1313
第二活性物质层              132
卷绕单元                    14
水平区域                    141
拐角区域                    142
聚合物层                    15
粘接件                      16
包装袋                      20
电解液                      30
如下具体实施方式将结合上述附图进一步说明本申请。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
除非另有定义，本文所使用的所有的技术和科学术语与属于本申请的技术领域的技术人员通常理解的含义相同。本文中在本申请的说明书中所使用的术语只是为了描述具体的实施例的目的，不是旨在于限制本申请。
下面结合附图，对本申请的一些实施方式作详细说明。在不冲突的情况下，下述的实施例及实施例中的特征可以相互组合。
参图1，本申请提供了一种电池100，包括电极组件10、包装袋20及容纳于所述包装袋20内的电解液30。一实施方式中，所述电池100为锂离子电池。
所述电极组件10容纳于所述包装袋20内。在本实施方式中，所述电极组件10包括由叠置的第一极片11、隔离膜12及第二极片13卷绕形成的卷绕单元14，以及聚合物层15。所述隔离膜12位于所述第一极片11和所述第二极片13之间。
参图2，所述第一极片11包括第一集流体111及设置于所述第一集流体111两侧的第一活性物质层112。一实施方式中，所述第一极片11为阴极极片。
参阅图1和图2，所述第一集流体111包括第一单面区1111及连接所述第一单面区1111的第一空白区1112。所述第一单面区1111和所述第一空白区1112位于所述卷绕单元14的最外圈。其中，所述第一单面区1111背对所述卷绕单元14中心的表面未设置第一活性物质层112。所述第一空白区1112的两侧均未设置第一活性物质层112。
参阅图1和图2，所述聚合物层15设置于所述第一空白区1112 的两侧以及所述第一单面区1111背对所述卷绕单元14中心的表面。其中，所述聚合物层15为聚偏氟乙烯、丁苯橡胶、羧甲基纤维素、聚丙烯酸、聚丙烯腈或聚丙烯酸酯。
具体地，所述聚合物层15的形成包括步骤如下：
首先，将第一极片11进行冷压处理；然后，于所述第一空白区1112的两侧以及所述第一单面区1111背对所述卷绕单元14中心的表面均匀喷涂形成所述聚合物层15的涂料；最后，烘干第一单面区1111及第一空白区1112上的涂料，以形成所述聚合物层15。其中，当对电池100进行化成时，所述聚合物层15在高温下熔融扩散，使得聚合物层15的厚度较烘干时变薄，如此，增大了第一极片11和第二极片13之间的空隙，给第一极片11和第二极片13在循环中的膨胀制造了空间，从而降低了第一极片11和第二极片13因循环膨胀变形及被撕裂的风险，进而有效提升电池100的循环使用寿命及安全性能。此外，将所述聚合物层15设置于所述卷绕单元14的最外圈还起到隔热的作用。
在本实施方式中，喷涂形成所述聚合物层15的涂料的重量控制在1mg/1540.25mm 2-5mg/1540.25mm 2。其中，所述电池100经化成后，所述聚合物层15的厚度为1.7μm-8.5μm。在一实施方式中，喷涂形成所述聚合物层15的涂料的重量为1.5mg/1540.25mm 2。在另一实施方式中，喷涂形成所述聚合物层15的涂料的重量为2mg/1540.25mm 2。在另一实施方式中，喷涂形成所述聚合物层15的涂料的重量为2.5mg/1540.25mm 2。在另一实施方式中，喷涂形成所述聚合物层15的涂料的重量为3mg/1540.25mm 2。
一实施方式中，参图3，所述第一集流体111还包括由所述第一极片11的卷绕起始端到所述第一单面区1111的第一双面区1113。所述第一双面区1113的两侧均设置有第一活性物质层112。其中，所述聚合物层15还设置于所述第一双面区1113的两侧，以进一步避免第一极片11和第二极片13因循环膨胀而发生形变及被撕裂的风险。
在另一实施方式中，参图4，所述卷绕单元14包括水平区域141及位于所述水平区域141两端的拐角区域142。所述聚合物层15还 设置于位于所述拐角区域142的第一极片11。其中，由于拐角区域142处第一极片11和第二极片13之间的空隙较小，导致电解液30被挤出去，而致使拐角区域142处因电解液30缺失而出现析锂的现象，从而影响到电池100的循环能力。如此，将所述聚合物层15设置于位于所述拐角区域142的第一极片11，使得电池100在进行化成时，由于所述聚合物层15在高温下的熔融扩散，增大了拐角区域142处第一极片11和第二极片13之间的空隙，从而有效避免了拐角区域142析锂的问题，从而大大提升了所述电池100的循环能力。
参图5，所述电极组件10还包括粘接件16。所述粘接件16设置于所述聚合物层15和所述第一极片11之间，以加强所述聚合物层15和所述第一极片11之间的连接力。其中，所述粘接件16为聚乙烯醇或聚四氟乙烯。
下面通过实施例对本申请中的电池100进行具体说明。
实施例1
参图1，所述电池100包括包装袋20以及容纳于所述包装袋20内的电解液30和电极组件10。
所述电极组件10包括聚合物层15以及由叠置的第一极片11、隔离膜12及第二极片13卷绕形成的卷绕单元14。所述隔离膜12位于所述第一极片11和所述第二极片13之间。
参图2，所述第一极片11包括第一集流体111及设置于所述第一集流体111两侧的第一活性物质层112。在实施例1中，所述第一极片11为阴极极片。
参阅图1和图2，所述第一集流体111包括第一单面区1111及连接所述第一单面区1111的第一空白区1112。所述第一单面区1111和所述第一空白区1112位于所述卷绕单元14的最外圈。其中，所述第一单面区1111背对所述卷绕单元14中心的表面未设置第一活性物质层112。
参图6，所述第二极片13包括第二集流体131及设置于所述第二集流体131两侧的第二活性物质层132。在实施例1中，所述第二集流体131包括依次设置的第二空白区1311、第二单面区1312 及第二双面区1313。其中，所述第二空白区1311的两侧均未设置第二活性物质层132。所述第二单面区1312朝向所述卷绕单元14中心的表面未设置第二活性物质层132。所述第二双面区1313的两侧均设置有第二活性物质层132。
所述聚合物层15设置于所述第一空白区1112的两侧以及所述第一单面区1111背对所述卷绕单元14中心的表面。其中，所述聚合物层15为聚偏氟乙烯。
在实施例1中，所述聚合物层15的形成包括如下步骤：
首先，将第一极片11进行冷压处理；然后，于所述第一空白区1112的两侧以及所述第一单面区1111背对所述卷绕单元14中心的表面均匀喷涂聚偏氟乙烯，其中，喷涂所述聚偏氟乙烯的重量控制在1.5mg/1540.25mm 2；最后，烘干第一单面区1111及第一空白区1112上的聚偏氟乙烯，以形成所述聚合物层15。其中，烘干后的聚合物层15的单面厚度为260μm。
在实施例1中，将上述电池100进行化成处理后，所述聚合物层的厚度降为2.6μm。
实施例2
实施例2与实施例1的区别在于，聚合物层15设置的位置。
在实施例2中，参图4，所述卷绕单元14包括水平区域141及位于所述水平区域141两端的拐角区域142。
相较于实施例1，实施例2中的所述聚合物层15还设置于所述拐角区域142的第一极片11。
实施例3
实施例3与实施例1的区别在于，聚合物层15设置的位置及第一极片11的结构。
在实施例3中，参图3，所述第一集流体111还包括由所述第一极片11的卷绕起始端到所述第一单面区1111的第一双面区1113。
相较于实施例1，参图3，实施例3中的所述聚合物层15还设置于所述第一双面区1113的两侧。
其中，利用扫描电镜拍摄实施例3中化成前的第一极片11，以得到如图7所示的扫描电镜图；利用扫描电镜拍摄实施例3中化成 后的第一极片11，以得到如图8所示的扫描电镜图。根据图7和图8可知，化成后第一极片11表面的所述聚偏氟乙烯的颗粒明显较化成前变小。即经化成后，所述聚合物层15的厚度会减薄，从而使得第一极片11和第二极片13之间的空隙增大，进而为给第一极片11和第二极片13在循环中的膨胀制造了空间。
实施例4
实施例4与实施例3的区别在于，实施例4中喷涂所述聚偏氟乙烯的重量控制在2.5mg/1540.25mm 2。
其中，利用能谱仪，将实施例3中，经化成后的电池100中的第一极片11进行元素分析，并得到如图9的谱图。
利用能谱仪，将实施例4中，经化成后的电池100中的第一极片11进行元素分析，并得到如图10的谱图。
分析图9和图10可知，改变喷涂所述聚偏氟乙烯的重量，不会改变化成后第一极片11的成分。
对比例1
对比例1与实施例3的区别在于，对比例1中的电池100无聚合物层15。
参图11，黑色线条为实施例3中的电池100在不同循环次数下的容量保持率的变化曲线，灰色线条为对比例1中的电池100在不同循环次数下的容量保持率的变化曲线。其中，根据两线条可知，所述聚合物层15的设置还可进一步提高所述电池100的循环性能。
图12和图13分别为经相同循环次数后，对比例1中电池100的CT图和实施例3中电池100的CT图。参图12可知，对比例1中的各极片严重变形；参图13可知，实施例3中的各极片平整，无变形。由此可知，所述聚合物层15的设置还可进一步解决极片因循环膨胀而发生形变及被撕裂的问题。
对实施例3及对比例1中的电池100进行热箱测试，具体测试包括如下步骤：
将对比例1及实施例3中充满电的电池100分别放置于热箱中，再以5±2℃/min的速率从常温升至130℃、132℃或135℃，并保温30分钟。若电池100不起火、不爆炸，即判定电池100通过热箱测 试。
表1
  130℃ 132℃ 135℃
实施例3 100％ 100％ 100％
对比例1 100％ 30％ 0％
表1为对比例1及实施例3的电池100在不同温度下进行热箱测试的测试结果(通过率)。由此可知，所述聚合物层15的设置还具有一定的隔热作用。
以上实施例仅用以说明本申请的技术方案而非限制，尽管参照较佳实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解，可以对本申请的技术方案进行修改或等同替换，而不脱离本申请技术方案的精神和实质。

Claims (10)

  1. 一种电极组件，包括由叠置的第一极片、隔离膜和第二极片卷绕形成的卷绕单元，所述第一极片包括第一集流体及设置于所述第一集流体两侧的第一活性物质层，所述第一集流体包括第一单面区及连接所述第一单面区的第一空白区，所述第一单面区背对所述卷绕单元中心的表面未设置第一活性物质层，其特征在于，
    所述第一单面区和所述第一空白区位于所述卷绕单元的最外圈；
    所述电极组件还包括聚合物层，所述聚合物层设置于所述第一空白区的两侧以及所述第一单面区背对所述卷绕单元中心的表面。
  2. 如权利要求1所述的电极组件，其特征在于，所述第一集流体还包括由所述第一极片的卷绕起始端到所述第一单面区的第一双面区，所述聚合物层还设置于所述第一双面区的两侧。
  3. 如权利要求1所述的电极组件，其特征在于，所述卷绕单元包括水平区域及位于所述水平区域两端的拐角区域，所述聚合物层还设置于位于所述拐角区域的第一极片。
  4. 如权利要求1-3中任一项所述的电极组件，其特征在于，所述第一极片为阴极极片。
  5. 如权利要求1-3中任一项所述的电极组件，其特征在于，所述聚合物层为聚偏氟乙烯、丁苯橡胶、羧甲基纤维素、聚丙烯酸、聚丙烯腈或聚丙烯酸酯。
  6. 如权利要求5所述的电极组件，其特征在于，形成所述聚合物层的涂料的重量为1mg/1540.25mm 2-5mg/1540.25mm 2。
  7. 如权利要求1-3中任一项所述的电极组件，其特征在于，所述电极组件还包括粘接件，所述粘接件设置于所述聚合物层和所述第一极片之间。
  8. 如权利要求7所述的电极组件，其特征在于，所述粘接件为聚乙烯醇或聚四氟乙烯。
  9. 一种电池，包括包装袋及容纳于所述包装袋内的电解液，其特征在于，所述电池还包括如权利要求1-8中任一项所述的电极组 件，所述电极组件容纳于所述包装袋内。
  10. 如权利要求9所述的电池，其特征在于，所述电池经化成后，所述聚合物层的厚度为1.7μm-8.5μm。
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