WO2022227729A1 - 电芯及用电装置 - Google Patents

电芯及用电装置 Download PDF

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Publication number
WO2022227729A1
WO2022227729A1 PCT/CN2022/073047 CN2022073047W WO2022227729A1 WO 2022227729 A1 WO2022227729 A1 WO 2022227729A1 CN 2022073047 W CN2022073047 W CN 2022073047W WO 2022227729 A1 WO2022227729 A1 WO 2022227729A1
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WIPO (PCT)
Prior art keywords
pole piece
tab
pole
tabs
current collector
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PCT/CN2022/073047
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English (en)
French (fr)
Inventor
戴志芳
张森
龙海
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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 EP22711851.0A priority Critical patent/EP4106048A4/en
Priority to US17/709,022 priority patent/US20220352605A1/en
Publication of WO2022227729A1 publication Critical patent/WO2022227729A1/zh

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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

  • the present application relates to the field of battery technology, and in particular, to a battery cell and an electrical device.
  • a blank current collector is exposed by digging grooves on the active material layer, and the tabs are welded on the blank current collector.
  • This type of tab is usually called an in-line tab.
  • the built-in tab can avoid reserving an empty foil area for welding tabs on the pole piece, which improves the energy density of the cell.
  • a built-in monopole lug structure is set on the anode pole piece, but the built-in monopole lug structure causes the current channel to be crowded, the internal resistance of the cell is too large, and the charging temperature rises, which cannot meet the rate charging temperature rise of 5C and above. need.
  • the blank current collector on the edge of the pole piece is die-cut out of the tab (that is, the tab and the current collector are integrally formed).
  • This kind of tab is usually called an external tab.
  • the ear structure can significantly reduce the internal resistance and meet the needs of large-rate temperature rise.
  • an insulating coating is usually arranged on the blank current collector at the edge of the cathode electrode piece to prevent burrs from being produced when the tabs are die-cut. A short circuit occurs due to the contact of the pole pieces, but the existence of the insulating layer leads to the need to leave more space at the head of the cell when bending the cathode tab, resulting in a loss of energy density of the cell.
  • a battery cell comprising a first pole piece, a second pole piece and a diaphragm, the diaphragm is arranged between the first pole piece and the second pole piece, so
  • the battery core is formed by winding the first pole piece, the diaphragm and the second pole piece, and the first pole piece includes a first current collector, a second current collector disposed on the surface of the first current collector.
  • the first active material layer is provided with a first groove, the first tab is disposed in the first groove, and is electrically connected to the first current collector ;
  • the second pole piece includes a second current collector, a second active material layer disposed on the surface of the second current collector, and a second tab; the second tab and the second current collector are integrally formed.
  • the first pole piece adopts an embedded pole ear structure
  • the second pole piece adopts an external pole ear structure.
  • the built-in tab can avoid reserving an empty foil area for welding the tab on the pole piece.
  • the external tab does not occupy the space of the active material layer on the pole piece. Both the built-in tab and the external tab can improve the performance of the cell. Energy Density.
  • the number of the first tabs is 1 to 10. In some embodiments, the first tabs are selected to be 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.
  • the plurality of first pole tabs can increase the current channel of the first pole piece, reduce the internal resistance of the battery cell, and reduce the charging temperature rise, so as to meet the needs of large rate temperature rise. In some embodiments, when the number of the first tabs is greater than 1, the projections of the first tabs overlap along the thickness direction of the cell. In this way, the overlapping first tabs are bent and welded with the adapter sheet, and the adapter sheet extends out of the packaging bag.
  • the projections of some of the first tabs overlap each other, and the projections of other first tabs overlap each other.
  • the projections do not overlap each other. Because the in-line tab is realized by grooving the pole piece, the thickness of the pole piece area where the in-line tab is located is usually smaller than the normal thickness of the pole piece. If the number of ears exceeds a certain number, the thickness of the cells in the overlapping area will be too thin, the interface of the cells will be poor, and there is a risk of lithium precipitation.
  • the first tabs are arranged on the same side of the winding surface of the cell. In this way, when the battery cell is packaged with the aluminum-plastic film, the first tab can extend out of the packaging bag without being excessively bent.
  • the number of the first pole lugs is one, and along the length direction of the first pole piece, the distance from the first pole lug to one end of the first pole piece is the first pole lug. One-third to two-thirds of the length of a pole piece.
  • the number of the first pole lugs is one, and along the length direction of the first pole piece, the distance from the first pole lug to one end of the first pole piece is the first pole lug. One-half the length of a pole piece.
  • the number of the first pole lugs is 2, and along the length direction of the first pole piece, the distance from the first pole lug to one end of the first pole piece is the first pole lug.
  • the number of the first pole lugs is 2, and along the length direction of the first pole piece, the distances from the first pole lugs to one end of the first pole piece are the One-third and two-thirds of the length of the first pole piece.
  • the first pole lug is arranged at the relative middle position of the first pole piece, so that when the pole piece expands, the groove around the groove is not tightly bonded, the thickness changes greatly and the film is caused when the groove is arranged at the end of the pole piece.
  • the first pole piece is divided into several parts in parallel by the first pole lug, the current passing through each part of the pole piece is reduced, and the heat generation of the battery is reduced.
  • the first pole piece is a cathode pole piece. Since the first pole tab is an in-line tab, the edge of the cathode pole piece does not need to be provided with an insulating layer, and the active material layer of the first pole piece can be set wider, that is, the width of the first pole piece The width of the pole piece of the layer is wider, and the A/C overhang (usually, the width of the anode pole piece is greater than the width of the cathode pole piece, and A/C overhang is the difference between the width of the anode pole piece and the cathode pole piece) decreases. , which is conducive to the improvement of cell energy density.
  • the number of the second tab is at least one. In some embodiments, the number of the second tabs may also be 1 to N, such as 1, 2, 3, 4, 5, 6, 7, 8, etc., where N is The number of layers of the second pole piece along the thickness direction of the battery core. In an embodiment, along the thickness direction of the battery core, each layer of the second pole piece is provided with one of the second pole tabs. The multiple second pole tabs can increase the current channel of the second pole piece, reduce the internal resistance of the battery cell, and reduce the charging temperature rise, so as to meet the needs of large rate temperature rise.
  • the second tabs are arranged on the same side of the winding surface of the cell. In this way, when the battery cell is packaged with the aluminum-plastic film, the second tab can extend out of the packaging bag without being excessively bent.
  • the projections of the second tabs overlap along the thickness direction of the cell. In this way, the overlapping second tabs are bent and welded with the transfer tabs, and the transfer tabs extend out of the packaging bag.
  • the second pole piece is an anode pole piece
  • the edge of the anode pole piece is not provided with an insulating layer, and at the same time, there are multiple current channels on the anode pole piece, the internal resistance of the cell is reduced, and the charging temperature rise is low. , to meet the needs of large rate temperature rise.
  • the present application also provides an electrical device, which includes the battery cell described in any one of the above.
  • FIG. 1 is a schematic diagram of a winding structure of a battery cell according to an embodiment of the present application.
  • FIG. 2 is a schematic structural diagram of a first pole piece provided by an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a first pole piece provided by an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a first pole piece according to an embodiment of the present application.
  • FIG. 5 is a schematic structural diagram of a second pole piece provided by an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a winding structure of a battery cell according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of the winding structure of the battery core provided in Embodiment 1 of the present application.
  • FIG. 8 is a schematic diagram of the winding structure of the battery core provided in Embodiment 2 of the present application.
  • FIG. 9 is a schematic diagram of the winding structure of the battery core provided in Comparative Example 1.
  • FIG. 9 is a schematic diagram of the winding structure of the battery core provided in Comparative Example 1.
  • FIG. 10 is a schematic diagram of the winding structure of the cell provided in Comparative Example 2.
  • FIG. 10 is a schematic diagram of the winding structure of the cell provided in Comparative Example 2.
  • the first collector 101 The first collector 101
  • the second collector 301 The second collector 301
  • the second active material layer 302 is the second active material layer 302
  • spatially relative terms such as “on” and the like, may be used herein for convenience of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that, in addition to the orientation depicted in the figures, spatially relative terms are intended to encompass different orientations of the device or apparatus in use or operation. For example, if the device in the figures is turned over, elements described as “above” or “over” other elements or features would then be oriented “below” or “beneath” the other elements or features. Thus, the exemplary term “upper” can include both an orientation of above and below.
  • first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections may not be shall be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of example embodiments.
  • the present application provides a cell 100 , which includes a first pole piece 10 , a second pole piece 30 and a diaphragm, and the diaphragm is disposed between the first pole piece 10 and the second pole piece 30 During this time, the battery core 100 is formed by winding the first pole piece 10 , the diaphragm and the second pole piece 30 .
  • the width direction of the cell 100 is defined as the first direction X
  • the thickness direction of the cell 100 is defined as the second direction Y.
  • the length direction of the battery cell 100 ie, the width direction of the first pole piece 10 or the second pole piece 30
  • the third direction Z is defined as the third direction Z.
  • the first pole piece 10 includes a first current collector 101 , a first active material layer 102 disposed on the surface of the first current collector 101 , and a first tab 103 .
  • the first active material layer 102 is provided with a first groove 104
  • the first tab 103 is provided in the first groove 104, and is electrically connected to the first current collector 101, that is, the first tab 103 is disposed in the first groove 104.
  • a pole ear 103 is a built-in pole ear.
  • the number of the first tabs 103 is 1 to 10. In some embodiments, as shown in FIG. 3 , the number of the first tab 103 is one, and along the length direction of the first pole piece 10 (ie, the first direction X), the first tab 103 The distance to one end of the first pole piece 10 is one third to two thirds of the length of the first pole piece 10 . In a specific implementation manner, the above-mentioned distance is selected to be half, that is, the first tab 103 is approximately located at the middle position in the first direction X of the first pole piece 10 .
  • the number of the first pole tabs 103 is two, and along the length direction of the first pole piece 10 , the distance from the first pole tab 103 to one end of the first pole piece 10 is One quarter to three quarters of the length of the first pole piece 10 .
  • the number of the first pole tabs is 2, and along the first direction X, the first pole tabs 103 are respectively connected to one end of the first pole piece 10 .
  • the distances are one third and two thirds of the length of the first pole piece 10 , that is, the two first pole tabs 103 are approximately evenly arranged in the first direction X of the first pole piece 10 . In this way, the first pole piece 10 is divided into three parts in parallel by the first pole tab 103 , the current passing through each part of the first pole piece 10 is reduced, and the heat generation of the battery is reduced.
  • the length of the first pole piece 10 refers to the length of the first active material layer 102 in the first direction X, that is, the length of the first active material layer 102 is not included
  • the length of the current collector 101 ); one end of the first pole piece 10 is the starting end or the end of the first active material layer 102 .
  • the second pole piece 30 includes a second current collector 301 , a second active material layer 302 disposed on the surface of the second current collector 301 , and a second tab 303 , the second tab 303 is connected to
  • the second current collector 301 is integrally formed, that is, the second tab 303 is an external tab.
  • the projections of the three first tabs 103 overlap each other, and the two first tabs
  • the projections of 103 do not overlap each other.
  • the first tab 103 is an in-line tab, and if the overlapped in-line tab exceeds a certain number, the thickness of the cell in the overlapping area will be too thin, which may easily lead to poor cell interface and risk of lithium precipitation.
  • FIG. 6 please refer to FIG.
  • the first tab 103 is disposed on the same side of the winding surface of the battery cell 100 , so that the first tab 103 can be extended out of the casing without excessive bending (not shown in the figure) , which is conducive to the packaging of the casing.
  • the winding surface ⁇ of the battery cell 100 refers to the plane where the innermost diaphragm is located.
  • the number of the second tab 303 is at least one.
  • the number of the second pole tabs 303 may also be 1 to N, where N is the number of layers of the second pole piece along the thickness direction of the cell. As shown in FIG.
  • the sheet 30 is provided with one of the second tabs 303 . In this way, the rate temperature rise of each layer of pole pieces during charging and discharging is close, which is beneficial to give full play to the performance of each layer of pole pieces.
  • the second pole piece 30 has two layers of the second pole piece 30 along the thickness direction of the cell 100 every time the second pole piece 30 is wound.
  • the second tabs 303 are disposed on the same side of the winding surface ⁇ of the battery cell 100 .
  • the second tab 303 and the first tab 103 are both disposed on the same side of the winding surface ⁇ of the battery cell 100 . In this way, when the battery cell 100 is packaged with an aluminum-plastic film, the second tab Both the 303 and the first tab 103 can extend out of the casing (not shown) without excessive bending, which is beneficial to the packaging of the casing.
  • the projections of the second tabs 303 overlap. In this way, the overlapping second tabs 303 are bent and welded to the adapter piece, and the adapter piece extends out of the housing.
  • the first pole piece 10 is a cathode pole piece
  • the second pole piece 30 is an anode pole piece; further, the first pole piece 10 is provided with a single first pole lug 103 , the second pole piece is provided with a single second pole lug 303 .
  • the edge of the cathode electrode sheet is not provided with an insulating layer. Compared with the prior art cathode electrode sheet provided with an insulating layer, the cathode electrode sheet of the present application has a wider active material layer, which can improve the energy density of the cell.
  • the first pole piece 10 is a cathode pole piece
  • the second pole piece 30 is an anode pole piece; further, the first pole piece 10 is provided with a single first pole lug 103 , the second pole piece is provided with a plurality of the second pole tabs 303 .
  • the anode pole piece is provided with a plurality of second tabs, and has a plurality of current channels, so as to meet the temperature rise requirement of high-rate charging.
  • the first pole piece 10 is a cathode pole piece
  • the second pole piece 30 is an anode pole piece; further, the first pole piece 10 is provided with a plurality of the first pole lugs 103, the second pole piece is provided with a single second pole tab 303.
  • the cathode pole piece has a plurality of current channels, which can improve the energy density of the battery cell and also meet the requirements of high-rate charging temperature rise.
  • the first pole piece 10 is a cathode pole piece
  • the second pole piece 30 is an anode pole piece; further, the first pole piece 10 is provided with a plurality of the first pole lugs 103 , the second pole piece is provided with a plurality of the second pole tabs 303 . That is, both the cathode pole piece and the anode pole piece have multiple current channels to meet the temperature rise requirement of high-rate charging.
  • an insulating coating is usually arranged on the blank current collector at the edge of the cathode electrode piece to prevent burrs from being produced when the tabs are die-cut.
  • a short circuit occurs due to the contact of the pole pieces, but the existence of the insulating layer leads to the need to leave more space at the head of the cell when bending the cathode tab, resulting in a loss of energy density of the cell.
  • the cathode pole piece adopts an in-line tab, and the edge of the pole piece and the tail of the pole piece are not provided with an insulating layer. Therefore, the pole ear set on the cathode pole piece can be bent, which requires more space for the head of the cell than the current one.
  • the PA Gap (the distance between the casing and the anode pole piece) can be reduced, increasing the energy density of the cell.
  • the active material layer on the cathode pole piece can be set wider, that is, the width of the cathode pole piece is wider than that of the cathode pole piece provided with the insulating layer, and the A/C overhang (usually, the width of the anode pole piece is greater than
  • the width of the cathode pole piece, A/C overhang is the difference between the width of the anode pole piece and the width of the cathode pole piece), which is beneficial to the improvement of the energy density of the cell.
  • cathode pole piece (first pole piece 10 ): the first active material layer 102 whose main material is lithium cobalt oxide is respectively coated on the opposite first surface and second surface of the first current collector 101 (aluminum foil), and the single side is The areal density of the coating (without current collector) was 0.167 g/1500 mm 2 , with a coating length of 842 mm for the first surface and a coating length of 745 mm for the second surface.
  • a first groove 104 is opened on the first active material layer 102 , and the first tab 103 (ie, the cathode tab) is arranged in the first groove 104 and is electrically connected to the first current collector 101 .
  • Two sides of the tab 103 are respectively covered with insulating tape to cover the first groove 104 .
  • the number of cathode tabs is one, which is located approximately in the middle of the length of the cathode tab (excluding the length of the empty foil area).
  • the preparation of the anode pole piece (the second pole piece 30 ): the second active material layer 302 whose main material is graphite is respectively coated on the opposite third surface and the fourth surface of the second current collector 301 (copper foil), and the single-sided coating is carried out.
  • the areal density of the coating (without current collector) was 0.09 g/1500 mm 2 , where the coating length of the third surface was 844 mm and the coating length of the fourth surface was 791 mm.
  • Ten second tabs ie, anode tabs
  • the battery cell 100 is obtained by winding the cathode electrode sheet, the separator and the anode electrode sheet prepared above, as shown in FIG. 7 .
  • Embodiment 1 The difference from Embodiment 1 is: as shown in FIG. 8 , the number of the first tabs 103 is 2, which are arranged at one-third and one-third of the length of the cathode pole piece (excluding the length of the empty foil area). Second place.
  • the number of the second tab 303 is one, and the setting of the second tab 303 is similar to that of the first tab 103 , that is, when the second active A second groove is opened on the material layer 302 , and the second tab 303 (ie, the anode tab) is arranged in the second groove and electrically connected to the second current collector 301 , and on both sides of the second tab 303 Cover the second groove with insulating tape respectively.
  • the number of the second tab is one, which is located approximately in the middle of the length of the anode pole piece (excluding the length of the empty foil area).
  • the first tabs 103 are external tabs, the number of which is 10, and the projections of the first tabs 103 overlap each other along the thickness direction of the cell 100 .
  • the arrangement of the first tabs 103 is similar to that of the second tabs 303 , that is, 10 first tabs 103 (ie, cathode tabs) are arranged on the first current collector 101 at certain intervals by laser die-cutting.
  • the edge of the first pole piece 10 ie, the cathode pole piece located on the same side of the first pole tab 103 is provided with an insulating layer, and the tail of the first pole tab 103 (the part connected to the first current collector 101 ) is also An insulating layer is provided.
  • the capacity of the battery cell 100 is calculated according to the following formula:
  • the temperature rise test is performed on the battery cell 100 according to the following process:

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Abstract

本申请提供一种电芯及用电装置，所述电芯由第一极片、隔膜和第二极片卷绕而成，所述第一极片包括第一集流体、设置于所述第一集流体表面上的第一活性物质层、第一极耳；所述第一活性物质层设置有第一凹槽，所述第一极耳设置于所述第一凹槽内，且与所述第一集流体电连接；所述第二极片包括第二集流体、设置于第二集流体表面上的第二活性物质层、第二极耳；所述第二极耳与所述第二集流体一体成型。本申请提供的电芯满足大倍率温升的需求，有利于能量密度的提升。

Description

电芯及用电装置
本申请要求2021年04月28日提交的中国专利申请202110470292.5的优先权。
技术领域
本申请涉及电池技术领域，尤其涉及一种电芯及用电装置。
背景技术
集流体上涂覆了活性物质层后，在活性物质层上挖槽露出空白集流体，将极耳焊接在空白集流体上，这种极耳通常被称为内嵌式极耳。内嵌式极耳可以避免在极片上预留焊接极耳的空箔区，提升了电芯的能量密度。通常在阳极极片上设置内嵌式单极耳结构，但内嵌式单极耳结构造成电流通道拥挤，电芯内阻过大，充电温升高，无法满足5C及5C以上的倍率充电温升需求。
集流体上涂覆活性物质层后，将极片边缘的空白集流体模切出极耳(即极耳与集流体一体成型)，这种极耳通常被称为外置极耳，外置极耳结构可以显著降低内阻，满足大倍率温升需求。现有技术中，通常在阴极极片的边缘空白集流体上设置绝缘涂层来防止模切极耳时产生毛刺，同时在阴极极耳的尾部也会设置绝缘涂层，防止阴极极耳与阳极极片接触而产生短路，但绝缘层的存在导致了在对阴极极耳进行折弯时，需要在电芯头部留更大空间，造成电芯的能量密度损失。
发明内容
有鉴于此，有必要提供一种电芯及用电装置以解决现有技术的电芯及用电装置不能同时满足大倍率升温需求以及保证高能量密度的问题。
本申请一实施方式的技术方案是：一种电芯，包括第一极片、第二极片和隔膜，所述隔膜设置在所述第一极片和所述第二极片之间，所述电芯由所述第一极片、所述隔膜和所述第二极片卷绕而成，所述第一极片包括第一集流体、设置于所述第一集流体表面上的第一活性物质层、第一极耳；所述第一活性物质层设置有第一凹槽，所述第一极耳设置于所述第一凹槽内，且与所述第一集流体电连接； 所述第二极片包括第二集流体、设置于第二集流体表面上的第二活性物质层、第二极耳；所述第二极耳与所述第二集流体一体成型。
第一极片采用内嵌式极耳结构，第二极片采用外置极耳结构。内嵌式极耳可以避免在极片上预留焊接极耳的空箔区，外置极耳不占用极片上活性物质层的空间，内嵌式极耳和外置极耳均可提升电芯的能量密度。
一些实施方式中，所述第一极耳的数量为1至10个。在一些实施方式中，所述第一极耳选择为1个、2个、3个、4个、5个、6个、7个、8个、9个或10个。多个第一极耳可以增加第一极片的电流通道，电芯内阻降低，充电温升低，满足大倍率温升的需求。一些实施方式中，当所述第一极耳的数量大于1时，沿所述电芯的厚度方向，所述第一极耳的投影重叠。如此，将重叠的第一极耳弯折并与转接片焊接，转接片伸出包装袋。
在一些实施方式中，当所述第一极耳的数量大于1时，沿所述电芯的厚度方向，部分的所述第一极耳的投影相互重叠，其他的所述第一极耳的投影互不重叠。因为内嵌式极耳是通过在极片上挖槽实现，内嵌式极耳所在的极片区域的厚度通常小于极片的正常厚度，沿着电芯的厚度方向，如果重叠的内嵌式极耳超过一定的数量，则该重叠区域的电芯厚度将过薄，电芯界面不良，有析锂风险。
在一些实施方式中，所述第一极耳设置在电芯卷绕面的同一侧。如此，在用铝塑膜封装电芯时，所述第一极耳不用过度弯折便可伸出包装袋。
一种实施方式中，所述第一极耳的数量为1个，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的三分之一至三分之二。
一种实施方式中，所述第一极耳的数量为1个，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的二分之一。
一种实施方式中，所述第一极耳的数量为2个，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的四分之一至四分之三。
一种实施方式中，所述第一极耳的数量为2个，沿所述第一极片的长度方向，所述第一极耳分别到所述第一极片的一端的距离为所述第一极片的长度的三分之一和三分之二。
即所述第一极耳设置在第一极片相对中间的位置，这样可以克服当极片膨胀时凹槽设置在极片端部时带来的凹槽周围区域粘结不牢、厚度变化大和膜片易脱落等缺陷，同时第一极片被第一极耳分成了并联的若干部分，通过极片每部分的电流减小，降低了电池的发热量。
一种实施方式中，所述第一极片为阴极极片。由于第一极耳为内嵌式极耳，阴极极片的极片边缘不需要设置绝缘层，第一极片的活性物质层可以设置更宽，即第一极片的宽度相比设置有绝缘层的极片的宽度更宽，A/C overhang(通常情况下，阳极极片的宽度大于阴极极片的宽度，A/C overhang为阳极极片宽度与阴极极片宽度的差值)减小，有利于电芯能量密度的提升。
一些实施方式中，所述第二极耳的数量为至少1个。一些实施方式中，所述第二极耳的数量还可以为1个至N个，如1个、2个、3个、4个、5个、6个、7个、8个等，N为所述第二极片沿所述电芯厚度方向的层数。一种实施方式中，沿所述电芯的厚度方向，每一层所述第二极片上设置有1个所述第二极耳。多个第二极耳可以增加第二极片的电流通道，电芯内阻降低，充电温升低，满足大倍率温升的需求。
在一些实施方式中，所述第二极耳设置在电芯卷绕面的同一侧。如此，在用铝塑膜封装电芯时，所述第二极耳不用过度弯折便可伸出包装袋。
一种实施方式中，当所述第二极耳的数量大于1时，沿所述电芯的厚度方向，所述第二极耳的投影重叠。如此，将重叠的第二极耳弯折并与转接极耳焊接，转接极耳伸出包装袋。
一种实施方式中，所述第二极片为阳极极片，所述阳极极片的边缘未设置绝缘层，同时，阳极极片上有多个电流通道，电芯内阻降低，充电温升低，满足大倍率温升的需求。
本申请还提供一种用电装置，所述用电装置包括如上任一项所述的电芯。
附图说明
下面结合附图和具体实施方式对本申请作进一步详细的说明。
图1为本申请一实施方式提供的电芯的卷绕结构示意图。
图2为本申请一实施方式提供的第一极片的结构示意图。
图3为本申请一实施方式提供的第一极片的结构示意图。
图4为本申请一实施方式提供的第一极片的结构示意图。
图5为本申请一实施方式提供的第二极片的结构示意图。
图6为本申请一实施方式提供的电芯的卷绕结构示意图。
图7为本申请实施例1提供的电芯的卷绕结构示意图。
图8为本申请实施例2提供的电芯的卷绕结构示意图。
图9为对比例1提供的电芯的卷绕结构示意图。
图10为对比例2提供的电芯的卷绕结构示意图。
主要元件符号说明：
电芯                 100
第一极片             10
第二极片             30
隔膜                 50
第一集流体           101
第一活性物质层       102
第一极耳             103
第一凹槽             104
第二集流体           301
第二活性物质层       302
第二极耳             303
绝缘层               500
第一方向             X
第二方向             Y
第三方向             Z
卷绕面               α
如下具体实施方式将结合上述附图进一步说明本申请实施例。
具体实施方式
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实施例的技术领域的技术人员通常理解的含义相同。本文中所使用的术语只是为了描述具体的实施方式的目的，不是旨在于限制本申请实施例。
空间相关术语，比如“上”等可在本文用于方便描述，以描述如图中阐释的一 个要素或特征与另一要素(多个要素)或特征(多个特征)的关系。应理解，除了图中描述的方向之外，空间相关术语旨在包括设备或装置在使用或操作中的不同方向。例如，如果将图中的设备翻转，则描述为在其他要素或特征“上方”或“上”的要素将定向在其他要素或特征的“下方”或“下面”。因此，示例性术语“上”可包括上面和下面的方向。
应理解，尽管术语第一、第二、第三等可在本文用于描述各种要素、组分、区域、层和/或部分，但是这些要素、组分、区域、层和/或部分不应受这些术语的限制。这些术语用于区分一个要素、组分、区域、层或部分与另一要素、组分、区域、层或部分。因此，下面讨论的第一要素、组分、区域、层或部分可称为第二要素、组分、区域、层或部分，而不背离示例性实施方式的教导。
请参阅图1，本申请提供一种电芯100，包括第一极片10、第二极片30和隔膜，所述隔膜设置在所述第一极片10和所述第二极片30之间，所述电芯100由所述第一极片10、所述隔膜和所述第二极片30卷绕而成。如图1所示，定义所述电芯100的宽度方向为第一方向X，所述电芯100的厚度方向为第二方向Y。如图2-5所示，定义所述电芯100的长度方向(即第一极片10或第二极片30的宽度方向)为第三方向Z。
请参阅图2，所述第一极片10包括第一集流体101、设置于所述第一集流体101表面上的第一活性物质层102、第一极耳103。所述第一活性物质层102设置有第一凹槽104，所述第一极耳103设置于所述第一凹槽104内，且与所述第一集流体101电连接，即所述第一极耳103为内嵌极耳。
一些实施方式中，所述第一极耳103的数量为1至10个。一些实施方式中，如图3所示，所述第一极耳103的数量为1个，沿所述第一极片10的长度方向(即第一方向X)，所述第一极耳103到所述第一极片10的一端的距离为所述第一极片10的长度的三分之一至三分之二。在一个具体实施方式中，上述距离选择二分之一，即第一极耳103大致位于第一极片10第一方向X上的中间位置。
一些实施方式中，所述第一极耳103的数量为2个，沿所述第一极片10的长度方向，所述第一极耳103到所述第一极片10的一端的距离为所述第一极片10的长度的四分之一至四分之三。请参阅图4，作为一种具体实施方式，所述第一极耳的个数为2个，沿第一方向X，所述第一极耳103分别到所述第一极片10的一端的距离为所述第一极片10的长度的三分之一和三分之二，即2个第一 极耳103大致均匀排布在第一极片10的第一方向X上。如此，所述的第一极片10被所述的第一极耳103分成了并联的三部分，通过第一极片10每部分的电流减小，降低了电池的发热量。
本申请中，所述第一极片10的长度指的是在第一方向X上第一活性物质层102的长度，即不包括空箔区(不涂覆第一活性物质层102的第一集流体101)的长度；所述第一极片10的一端为所述第一活性物质层102的起始端或末端。
请参阅图5，所述第二极片30包括第二集流体301、设置于第二集流体301表面上的第二活性物质层302、第二极耳303，所述第二极耳303与所述第二集流体301一体成型，即所述第二极耳303为外置极耳。
一些实施方式中，如图6所示，沿所述电芯100的厚度方向(即第二方向Y)，3个所述第一极耳103的投影互相重叠，2个所述第一极耳103的投影互不重叠。第一极耳103为内嵌式极耳，重叠的内嵌式极耳超过一定的数量，则该重叠区域的电芯厚度将过薄，容易引起电芯界面不良，有析锂风险。此外，请参阅图8，所述第一极耳103设置在电芯100卷绕面的同一侧，如此，所述第一极耳103不用过度弯折即可伸出壳体(图未示)，有利于壳体的封装。在本申请中，电芯100的卷绕面α指的最内圈隔膜所在的平面。一些实施方式中，所述第二极耳303的数量为至少1个。一些实施方式中，所述第二极耳303的数量还可以为1个至N个，N为所述第二极片沿所述电芯厚度方向的层数。如图1所示，电芯100有所述第二极耳7个，沿第二方向Y，所述第二极片30共7层(即N＝7)，每一层所述第二极片30上设置有1个所述第二极耳303。如此，每一层极片在充放电时的倍率温升接近，有利于充分发挥每一层极片的性能。本申请中，第二极片30每卷绕一周，沿电芯100的厚度方向，则具有两层第二极片30。
一种实施方式中，如图6所示，所述第二极耳303设置在电芯100卷绕面α的同一侧。并且，所述第二极耳303和所述第一极耳103均设置在电芯100卷绕面α的同一侧，如此，在用铝塑膜封装电芯100时，所述第二极耳303和第一极耳103均不用过度弯折便可伸出壳体(图未示)，有利于壳体的封装。
在一些实施方式中，如图1和图6所示，当所述第二极耳303的数量大于1时，沿第二方向Y，所述第二极耳303的投影重叠。如此，将重叠的第二极耳303弯折并与转接片焊接，转接片伸出壳体。
在一具体实施方式中，所述第一极片10为阴极极片，所述第二极片30为阳 极极片；进一步地，所述第一极片10设置单个所述第一极耳103，所述第二极片设置单个所述第二极耳303。所述阴极极片的边缘未设置绝缘层，相比现有技术的设置有绝缘层的阴极极片，本申请的阴极极片具有更宽的活性物质层，可以提高电芯的能量密度。
在一具体实施方式中，所述第一极片10为阴极极片，所述第二极片30为阳极极片；进一步地，所述第一极片10设置单个所述第一极耳103，所述第二极片设置多个所述第二极耳303。所述阳极极片设置多个第二极耳，具有多个电流通道，满足大倍率充电温升需求。
在一具体实施方式中，所述第一极片10为阴极极片，所述第二极片30为阳极极片；进一步地，所述第一极片10设置多个所述第一极耳103，所述第二极片设置单个所述第二极耳303。所述阴极极片具有多个电流通道，在可以提高电芯能量密度的同时，也可以满足大倍率充电温升的需求。
在一具体实施方式中，所述第一极片10为阴极极片，所述第二极片30为阳极极片；进一步地，所述第一极片10设置多个所述第一极耳103，所述第二极片设置多个所述第二极耳303。即，阴极极片和阳极极片均具有多个电流通道，满足大倍率充电温升需求。
现有技术中，通常在阴极极片的边缘空白集流体上设置绝缘涂层来防止模切极耳时产生毛刺，同时在阴极极耳的尾部也会设置绝缘涂层，防止阴极极耳与阳极极片接触而产生短路，但绝缘层的存在导致了在对阴极极耳进行折弯时，需要在电芯头部留更大空间，造成电芯的能量密度损失。本申请中，阴极极片采用内嵌式极耳，极片边缘以及极耳尾部未设置绝缘层，因此，阴极极片上设置的极耳可以弯折，对电芯头部的空间要求相比现有技术较低，PA Gap(壳体与阳极极片之间的距离)可以减小，增加了电芯的能量密度。同时，阴极极片上的活性物质层可以设置更宽，即阴极极片的宽度相比设置有绝缘层的阴极极片的宽度更宽，A/C overhang(通常情况下，阳极极片的宽度大于阴极极片的宽度，A/C overhang为阳极极片宽度与阴极极片宽度的差值)减小，有利于电芯能量密度的提升。
以下将结合具体实施例对本申请作进一步说明。
实施例1
阴极极片(第一极片10)的制备：在第一集流体101(铝箔)相对的第一表 面和第二表面分别涂覆主材料为钴酸锂的第一活性物质层102，单面涂覆的面密度(不含集流体)为0.167g/1500mm 2，其中第一表面的涂覆长度为842mm，第二表面的涂覆长度为745mm。在第一活性物质层102上开设第一凹槽104，将第一极耳103(即阴极极耳)设置于第一凹槽104中并与第一集流体101电连接，并在在第一极耳103的两侧分别贴绝缘胶纸覆盖第一凹槽104。阴极极耳的数量为1个，大致位于阴极极片长度(不包括空箔区的长度)上的中间位置。
阳极极片(第二极片30)的制备：在第二集流体301(铜箔)相对的第三表面和第四表面分别涂覆主材料为石墨的第二活性物质层302，单面涂覆的面密度(不含集流体)为0.09g/1500mm 2，其中第三表面的涂覆长度为844mm，第四表面的涂覆长度为791mm。通过激光模切在第二集流体301上按照一定间隔设置10个第二极耳(即阳极极耳)，沿电芯100的厚度方向，第二极耳的投影互相重叠。
将上述制备的阴极极片、隔膜和阳极极片卷绕后得到电芯100，如图7所示。
实施例2
与实施例1的区别在于：如图8所示，第一极耳103的数量为2个，设置于阴极极片长度(不包括空箔区的长度)上的三分之一及三分之二处。
对比例1
与实施例1的区别在于：如图9所示，第二极耳303的个数为1个，第二极耳303设置的方式与第一极耳103设置的方式类似，即在第二活性物质层302上开设第二凹槽，将第二极耳303(即阳极极耳)设置于第二凹槽中并与第二集流体301电连接，并在在第二极耳303的两侧分别贴绝缘胶纸覆盖第二凹槽。第二极耳的数量为1个，大致位于阳极极片长度(不包括空箔区的长度)上的中间位置。
对比例2
与实施例1的区别在于：如图10所示，第一极耳103为外置极耳，数量为10个，沿电芯100的厚度方向，第一极耳103的投影互相重叠。第一极耳103的设置方式与第二极耳303设置的方式类似，即通过激光模切在第一集流体101上按照一定间隔设置10个第一极耳103(即阴极极耳)。该对比例中，位于第一极耳103同侧的第一极片10(即阴极极片)边缘设置有绝缘层，第一极耳103的尾部(与第一集流体101连接的部分)也设置有绝缘层。
对电芯100的容量按照如下公式计算：
容量＝(阴极极片的宽度×(第一表面涂覆长度+第二表面涂覆长度)-贴胶面积)×阴极极片的面密度×阴极克容量(即170mAh/g)，其中，贴胶面积＝内嵌极耳个数×20mm×28mm×2。
对电芯100按如下过程进行温升测试：
环境温度25℃，6C恒流充电至4.2V，转5C恒流充电至4.32V，转3C恒流充电至4.5V，4.5V恒压充电至0.1C，测试记录充电过程中电芯100的主体温度，温升＝充电过程主体温度的最高温度-环境温度。
上述各实施例和对比例的参数设置及测试结果见表1。
表1
Figure PCTCN2022073047-appb-000001
由表1可知，相对于比较例1，阴极极片和阳极极片均设置内嵌式单极耳，实施例1和2的电芯，阳极极片设置有多个外置的阳极极耳，温升更小，并且容量并没有明显降低。相对于比较例2，阴极极片设置多个外置阴极极耳，实施例1和2的电芯，即使阴极极片采用单个内嵌式阴极极耳或两个内嵌式阴极极耳，并没有明显地提高温升，但同时却具有更大的容量，即能量密度更高。

Claims (10)

  1. 一种电芯，包括第一极片、第二极片和隔膜，所述隔膜设置在所述第一极片和所述第二极片之间，所述电芯由所述第一极片、所述隔膜和所述第二极片卷绕而成，其特征在于，所述第一极片包括第一集流体、设置于所述第一集流体表面上的第一活性物质层、第一极耳；所述第一活性物质层设置有第一凹槽，所述第一极耳设置于所述第一凹槽内，且与所述第一集流体电连接；所述第二极片包括第二集流体、设置于第二集流体表面上的第二活性物质层、第二极耳；所述第二极耳与所述第二集流体一体成型。
  2. 如权利要求1所述的电芯，其特征在于，所述第一极片为阴极极片，所述第二极片为阳极极片。
  3. 如权利要求1所述的电芯，其特征在于，所述第一极耳为至少1个，和/或，所述第二极耳为至少1个。
  4. 如权利要求1所述的电芯，其特征在于，沿所述电芯的厚度方向，部分的所述第一极耳的投影相互重叠，和/或，全部的所述第二极耳的投影相互重叠。
  5. 如权利要求1所述的电芯，其特征在于，沿所述电芯的厚度方向，所述第一极耳和所述第二极耳位于电芯卷绕面的同一侧。
  6. 如权利要求1所述的电芯，其特征在于，沿所述电芯的厚度方向，每一层所述第二极片上设置有1个所述第二极耳。
  7. 如权利要求1所述的电芯，其特征在于，所述第一极耳的数量为1个，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的三分之一至三分之二。
  8. 如权利要求1所述的电芯，其特征在于，所述第一极耳的数量为2个，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的四分之一至四分之三。
  9. 如权利要求1所述的电芯，其特征在于，当所述第一极耳的数量为1个时，沿所述第一极片的长度方向，所述第一极耳到所述第一极片的一端的距离为所述第一极片的长度的二分之一；当所述第一极耳的数量为2个时，沿所述第一极片的长度方向，所述第一极耳分别到所述第一极片的一端的距离为所述第一极片的 长度的三分之一和三分之二。
  10. 一种用电装置，其特征在于，所述用电装置包括如权利要求1-9任一项所述的电芯。
PCT/CN2022/073047 2021-04-28 2022-01-20 电芯及用电装置 WO2022227729A1 (zh)

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