WO2024065362A1 - 电化学装置及用电设备 - Google Patents

电化学装置及用电设备 Download PDF

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Publication number
WO2024065362A1
WO2024065362A1 PCT/CN2022/122461 CN2022122461W WO2024065362A1 WO 2024065362 A1 WO2024065362 A1 WO 2024065362A1 CN 2022122461 W CN2022122461 W CN 2022122461W WO 2024065362 A1 WO2024065362 A1 WO 2024065362A1
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WO
WIPO (PCT)
Prior art keywords
cathode
tab connecting
electrochemical device
connecting piece
current collector
Prior art date
Application number
PCT/CN2022/122461
Other languages
English (en)
French (fr)
Inventor
李芳芳
戴志芳
胡小明
Original Assignee
宁德新能源科技有限公司
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Filing date
Publication date
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 PCT/CN2022/122461 priority Critical patent/WO2024065362A1/zh
Priority to CN202280007960.3A priority patent/CN116802921A/zh
Publication of WO2024065362A1 publication Critical patent/WO2024065362A1/zh

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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F15/00—Digital computers in general; Data processing equipment in general
    • G06F15/16—Combinations of two or more digital computers each having at least an arithmetic unit, a program unit and a register, e.g. for a simultaneous processing of several programs
    • 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
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks

Definitions

  • the embodiments of the present application relate to the field of electrochemical technology, and in particular to an electrochemical device and electrical equipment.
  • electrochemical devices including but not limited to lithium-ion batteries, sodium-ion batteries, etc.
  • electrochemical devices including but not limited to lithium-ion batteries, sodium-ion batteries, etc.
  • a type of electrochemical device in the related art it is composed of a cathode electrode sheet, an anode electrode sheet and a separator disposed therebetween. During the preparation process, it is necessary to electrically connect the electrode ears at the blank areas at the edges of the current collectors on the cathode electrode sheet and the anode electrode sheet. For this type of electrochemical device, how to improve its preparation efficiency is a technical problem that needs to be solved.
  • embodiments of the present application provide an electrochemical device and an electrical equipment to at least partially solve the above problems.
  • an electrochemical device comprising: a pole piece, the pole piece comprising a current collector, an active material layer and a pole tab connecting piece, wherein when the pole piece is unfolded, the current collector comprises a first part and a second part along the width direction of the pole piece, the active material layer is arranged on the surface of the first part, the second part is an empty foil area where no active material layer is arranged, the pole tab connecting piece overlaps with the surface of the second part to form an overlapping area, the pole tab connecting piece is welded to the surface of the second part to form an electrical connection with the second part, and along the length direction of the pole piece, the ratio of the weld print area to the weld area area is greater than or equal to 20%, and the ratio of the weld area length to the overlapping area length is greater than or equal to 60%.
  • the electrode piece includes a cathode electrode piece and an anode electrode piece. Since the cathode electrode piece of the electrochemical device is welded to the surface of the second part of the cathode current collector (i.e., the edge empty foil area on the cathode current collector), and the anode electrode piece of the anode electrode piece is welded to the surface of the second part of the anode current collector (i.e., the edge empty foil area on the anode current collector), when the cathode electrode piece is led out from the cathode current collector in the present application, it is no longer necessary to electrically connect the cathode electrode piece directly to the second part of the cathode current collector, but it can be electrically connected to the cathode electrode piece through the cathode electrode piece welded to the second part of the cathode current collector, and in the present invention, When the anode tab is led out from the anode current collector in the application, the anode tab may no longer
  • the cathode tab when preparing the cathode tab of the electrochemical device in the present application, the cathode tab is not easy to wrinkle when the cathode tab is cold pressed, and when preparing the anode tab of the electrochemical device in the present application, the anode tab is not easy to wrinkle when the anode tab is cold pressed. Therefore, the electrochemical device is made by using such cathode tab and anode tab, which can effectively improve the preparation efficiency of the electrochemical device.
  • the ratio of the weld mark area to the welding zone area is greater than or equal to 20%, which can ensure that the second part can form a stable weld with the electrode ear connecting piece, and the ratio of the welding zone length to the overlapping zone length is greater than or equal to 60%, which can ensure that the weld marks are evenly distributed in the welding zone and the overlapping zone, avoiding the concentration of weld marks leading to excessive local strength or too low strength in other parts, and avoiding the resulting processing difficulties.
  • the pole piece is a cathode pole piece
  • the first part includes a first sub-part and a second sub-part connected to each other, the second sub-part is connected to the second part, the active material layer is arranged on the first sub-part, and the second sub-part is arranged with an insulating layer;
  • the second part along the width direction of the pole piece, the second part includes a first side close to the first sub-part and a second side away from the first sub-part, and the pole tab connecting piece includes a first side close to the first sub-part and a second side away from the first sub-part; wherein, there is a gap between the pole tab connecting piece and the first sub-part, and the second side of the second part is located between the first side of the pole tab connecting piece and the second side of the pole tab connecting piece.
  • one method of preventing the cathode electrode sheet from wrinkling during cold pressing is to first cold press the cathode electrode sheet with the cathode active material layer and the insulating layer, and then stretch the edge empty foil area of the cathode current collector of the cathode electrode sheet before cold pressing, so that the deformation degree of the edge empty foil area of the cathode current collector and the insulating layer tends to be consistent, thereby preventing the cathode electrode sheet from wrinkling during subsequent cold pressing of the cathode electrode sheet.
  • the cathode electrode sheet is prone to breakage during the cold pressing process due to the increased cold pressing tension of the cathode electrode sheet, which also reduces the preparation rate of the electrochemical device.
  • the cathode tab when the cathode tab is led out from the cathode current collector second part (i.e., the edge empty foil area of the cathode current collector) of the cathode current collector, the cathode tab can no longer be directly electrically connected to the cathode current collector second part, but can be electrically connected to the cathode tab through the cathode tab connecting piece welded to the cathode current collector second part, so that when preparing the cathode pole piece of the electrochemical device, it is not necessary to stretch the cathode current collector second part (i.e., the edge empty foil area of the cathode current collector) of the cathode pole piece before cold pressing the cathode pole piece, and it can also improve the problem of wrinkling of the cathode pole piece when the cathode pole piece is cold pressed later, and because it is not necessary to stretch the cathode current collector second part (i.e., the edge empty foil area of the cath
  • the width d1 of the pole tab connecting piece satisfies: 3mm ⁇ d1 ⁇ 25mm.
  • the cathode electrode sheet as an example, when the width d1 of the cathode electrode tab connecting sheet is too small, it is difficult to weld the cathode electrode tab connecting sheet to the second part of the cathode current collector when preparing the electrochemical device; and when the width d1 of the cathode electrode tab connecting sheet is too large, the edge of the cathode electrode tab connecting sheet is prone to collapse during the preparation of the cathode electrode sheet, and it is also easy to accidentally cause the cathode electrode tab connecting sheet to break.
  • the width of the cathode electrode tab connecting sheet in this embodiment meets the above-mentioned value range (i.e., 3mm ⁇ d1 ⁇ 25mm), which can better avoid the disadvantages of the cathode electrode tab connecting sheet being too small and the disadvantages of the cathode electrode tab connecting sheet being too large, thereby meeting the use needs of the electrochemical device and improving the preparation rate of the electrochemical device.
  • the width d2 of the second portion satisfies: 1mm ⁇ d2 ⁇ 20mm.
  • the cathode electrode sheet as an example, when the width of the second part of the cathode current collector is too small, it is difficult to ensure the welding width when preparing the electrochemical device, resulting in greater difficulty in welding the cathode tab connecting sheet and the second part of the cathode current collector; and when the width of the second part of the cathode current collector is too large, in the process of preparing the cathode electrode sheet, the second part of the cathode current collector is more likely to wrinkle after cold pressing, which is easy to increase the energy density loss and increase the cost.
  • the width of the second part of the cathode current collector in this embodiment meets the above-mentioned value range, which can better avoid the disadvantages of the second part of the cathode current collector being too small and the disadvantages of the second part of the cathode current collector being too large, thereby meeting the use needs of the electrochemical device and improving the preparation rate of the electrochemical device.
  • the width d3 of the insulating layer satisfies: 0.5 mm ⁇ d3 ⁇ 5 mm.
  • This embodiment uses an insulating layer within this width range to effectively insulate and isolate the second sub-portion of the cathode current collector from the anode electrode plate to prevent a short circuit between the two, while meeting the use requirements of the electrochemical device without adding additional costs.
  • the insulating layer includes a first side close to the first sub-portion and a second side away from the first sub-portion; if the first side of the pole tab connecting piece is located on the insulating layer, the spacing d4 between the first side of the pole tab connecting piece and the second side of the insulating layer satisfies: 0mm ⁇ d4 ⁇ 8mm; or, if the first side of the pole tab connecting piece is located on the second portion, the spacing d4 between the first side of the pole tab connecting piece and the second side of the insulating layer satisfies: 0mm ⁇ d4 ⁇ 10mm.
  • the electrode sheet as a cathode electrode sheet as an example, when the first side of the cathode electrode tab connecting sheet is located on the insulating layer, it is equivalent to that after the cathode electrode tab connecting sheet is welded to the second part of the cathode current collector, the first end of the cathode electrode tab connecting sheet exceeds the first side of the second part of the cathode current collector in the opposite direction of the width direction of the electrode sheet.
  • d4 satisfies such a value range, which can better avoid the disadvantages of the first end of the cathode electrode tab connecting sheet exceeding the first side of the second part of the cathode current collector in the opposite direction of the width direction of the electrode sheet, and can better avoid the disadvantages of the first side of the cathode electrode tab connecting sheet being located on the second part of the cathode current collector and d4 being too large, thereby meeting the use requirements of the electrochemical device and further improving the preparation rate of the electrochemical device.
  • the weld mark includes a first weld mark, which is formed when the second part is welded to the pole tab connecting sheet; along the width direction of the pole sheet, the first weld mark includes a first side close to the first sub-part and a second side away from the first sub-part; the second side of the first weld mark is located on the pole tab connecting sheet, and there is a distance between the first weld mark and the first sub-part.
  • the second side of the first weld mark of the present application is located on the cathode pole tab connecting piece, ensuring that the cathode pole tab connecting piece can form a stable welding connection with the second part of the cathode current collector.
  • the width d5 of the first weld mark satisfies: 0.1 mm ⁇ d5 ⁇ 10 mm.
  • the electrode sheet as a cathode electrode sheet since the width d5 of the first weld mark is too small (i.e., d5 ⁇ 0.1mm), it is difficult to ensure that the welding tension between the second part of the cathode current collector and the cathode tab connecting sheet meets the requirements, resulting in the disadvantage of the welding tension between the second part of the cathode current collector and the cathode tab connecting sheet being too small; and when the width d5 of the first weld mark is too large (i.e., d5>10mm), the welding is difficult and the cost is increased.
  • the width d5 of the first weld mark satisfies the above value range (0.1mm ⁇ d5 ⁇ 10mm), which can avoid the disadvantage of the width of the first weld mark being too small, and can also avoid the disadvantage of the width of the first weld mark being too large, thereby meeting the use needs of the electrochemical device, and further improving the preparation rate of the electrochemical device.
  • the spacing d6 between the first side of the first weld mark and the first side of the tab connecting sheet satisfies: 0mm ⁇ d6 ⁇ 5mm; or, if the first side of the first weld mark is located on the tab connecting sheet, the spacing d6 between the first side of the first weld mark and the first side of the tab connecting sheet satisfies: 0mm ⁇ d6 ⁇ 20mm.
  • the cathode electrode sheet as an example, when the first side of the first weld mark exceeds the first side of the cathode tab connecting sheet too much in the opposite direction of the width direction of the electrode sheet (for example, d6>5mm when the first side of the first weld mark is located on the second part of the cathode current collector), there are more parts without cathode active materials, and therefore the space occupies a large proportion of the part that cannot provide energy, resulting in serious loss of energy density, which affects the subsequent electrical connection between the cathode tab and the cathode tab connecting sheet (for example, the cathode tab and the cathode tab connecting sheet are electrically connected in the form of welding).
  • the cathode tab connecting sheet is also easily damaged, which ultimately affects the electrical performance of the manufactured electrochemical device; and when the first side of the first weld mark exceeds the first side of the cathode tab connecting sheet too much in the width direction of the electrode sheet (for example, d6>30mm when the first side of the first weld mark is located on the cathode tab connecting sheet), there is a situation where the cathode tab connecting sheet in an unconstrained state is too wide, which increases the process difficulty when preparing the cathode electrode sheet and affects the preparation rate of the electrochemical device.
  • the present application can avoid the disadvantages caused by the first side of the first weld mark exceeding the first side of the cathode tab connecting piece too much in the opposite direction of the width direction of the electrode piece, and can also avoid the disadvantages caused by the first side of the first weld mark exceeding the first side of the cathode tab connecting piece too much in the width direction of the electrode piece, thereby meeting the use needs of the electrochemical device and further improving the preparation efficiency of the electrochemical device.
  • the spacing d7 between the second side of the first weld mark and the second side of the second part satisfies: 0mm ⁇ d7 ⁇ 15mm; or, if the first projection of the second side of the first weld mark on the pole tab connecting sheet does not overlap with the second projection of the second part on the pole piece on the pole tab connecting sheet, the spacing d7 between the second side of the first weld mark and the second side of the second part satisfies: 0mm ⁇ d7 ⁇ 7mm.
  • the spacing d7 between the second side of the first weld mark and the second side of the second part of the cathode current collector is too large (for example, d7>15mm when the first projection and the second projection overlap), that is, when the second side of the second part of the cathode current collector exceeds the second side of the first weld mark too much in the width direction of the electrode sheet, there is a situation where the second part of the cathode current collector in an unconstrained state is too wide, which increases the process difficulty when preparing the cathode electrode sheet and affects the preparation rate of the electrochemical device; and when the first projection and the second projection do not overlap, the spacing d7 between the second side of the first weld mark and the second side of the cathode current collector is too large (for example, d7>7mm when the first projection and the second projection do not overlap), that is, when the second side of the first
  • the present application can avoid the disadvantages caused by the second side of the second part of the cathode current collector exceeding the second side of the first weld mark too much along the width direction of the electrode piece, and can also avoid the disadvantages caused by the second side of the first weld mark exceeding the second side of the second part of the cathode current collector too much along the width direction of the electrode piece, thereby meeting the use needs of the electrochemical device and further improving the preparation efficiency of the electrochemical device.
  • the electrochemical device also includes a pole ear, which is electrically connected to the pole ear connecting sheet by welding, and forms a second weld mark on the pole ear connecting sheet; along the width direction of the pole sheet, the second weld mark includes a first side close to the first sub-portion and a second side away from the first sub-portion; wherein, the spacing d8 between the second side of the first weld mark and the first side of the second weld mark satisfies: 0mm ⁇ d8 ⁇ 10mm.
  • the cathode electrode sheet As an example, when the cathode electrode tab is electrically connected to the cathode electrode tab connecting sheet by welding, the second weld mark formed on the cathode electrode tab connecting sheet cannot overlap with the first weld mark. If they overlap, the welding effect between the cathode electrode tab and the cathode electrode tab connecting sheet will be affected, so that the welding tension between the two will be reduced; and if the spacing d8 between the second side of the first weld mark and the first side of the second weld mark is too large (for example, when d8>10mm), it is easy to affect the energy density of the electrochemical device.
  • the welding tension between the second portion and the tab connecting piece is greater than or equal to 70N and less than or equal to 1000N.
  • the welding tension in this embodiment meets the above-mentioned value range, which can better avoid the disadvantages of too small welding tension between the second part and the tab tab, and can better avoid the disadvantages of too large welding tension between the second part and the tab tab, thereby meeting the use needs of the electrochemical device and improving the preparation rate of the electrochemical device.
  • an electrical equipment comprising the above-mentioned electrochemical device.
  • the electrical equipment in the embodiment of the present application includes the electrochemical device provided in the first aspect above. Since the preparation rate of the electrochemical device is relatively high, the preparation rate of the electrical equipment is also relatively high.
  • FIG. 1 is a schematic diagram of an electrochemical device according to an example of an embodiment of the present application.
  • FIG. 2 is a diagram showing a process for preparing a cathode electrode of an electrochemical device according to an example of the related art.
  • FIG. 3A is a diagram showing a process for preparing a cathode electrode of an electrochemical device according to an exemplary embodiment of the present application.
  • FIG. 3B is an enlarged schematic diagram of point T in FIG. 3A .
  • FIG. 4A is a schematic cross-sectional view along the thickness direction of a cathode electrode of an electrochemical device according to an example embodiment of the present application.
  • 4B is a schematic cross-sectional view along the thickness direction of a cathode electrode piece of an electrochemical device according to another example of an embodiment of the present application.
  • 4C is a schematic cross-sectional view along the thickness direction of a cathode electrode of an electrochemical device according to yet another example of an embodiment of the present application.
  • FIG. 5 is a schematic diagram of an exemplary ultrasonic roll welding method according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of an exemplary first weld print according to an embodiment of the present application.
  • FIG. 7 is a schematic diagram of another exemplary first weld print according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of a first weld print according to another example of an embodiment of the present application.
  • FIG. 9 is a schematic diagram of a first weld print according to another example of an embodiment of the present application.
  • FIG. 10 is a schematic diagram of an exemplary electrical device according to an embodiment of the present application.
  • a lithium-ion battery is used as an example of the electrochemical device 10 to explain the present application, but the electrochemical device 10 of the present application is not limited to a lithium-ion battery, for example, it can also be a sodium-ion battery, etc.
  • an electrochemical device comprising: a pole piece, the pole piece comprising a current collector, an active material layer and a pole tab connecting piece, wherein when the pole piece is unfolded, the current collector comprises a first part and a second part along the width direction of the pole piece, the active material layer is arranged on the surface of the first part, the second part is an empty foil area where no active material layer is arranged, the pole tab connecting piece overlaps with the surface of the second part to form an overlapping area, the pole tab connecting piece is welded to the surface of the second part to form an electrical connection with the second part, and along the length direction of the pole piece, the ratio of the weld print area to the weld area area is greater than or equal to 20%, and the ratio of the weld area length to the overlapping area length is greater than or equal to 60%.
  • the pole piece of the electrochemical device of the present application may include a cathode pole piece and an anode pole piece.
  • the current collector is a cathode current collector
  • the active material layer is a cathode active material layer
  • the pole tab connecting piece is a cathode pole tab connecting piece
  • the pole tab electrically connected to the pole tab connecting piece is a cathode pole tab
  • the pole piece is an anode pole piece
  • the current collector is an anode current collector
  • the active material layer is an anode active material layer
  • the pole tab connecting piece is an anode pole tab connecting piece
  • the pole tab electrically connected to the pole tab connecting piece is an anode pole tab.
  • the electrochemical device of the present application mainly takes the pole piece as an example of a cathode pole piece, and the anode pole piece is not described in detail. The following is explained in conjunction with Figures 1 to 9.
  • an exemplary electrochemical device 10 comprising: a cathode electrode sheet 1, an anode electrode sheet 2, a separator 3, a cathode tab 41, and an anode tab; the separator 3 is disposed between the cathode electrode sheet 1 and the anode electrode sheet 2; the cathode electrode sheet 1 comprises a cathode current collector 11, a cathode active material layer 12, and a cathode tab connecting piece 51, the cathode current collector 11 comprises a first part and a second part along the width direction Y of the electrode sheet, the cathode active material layer 12 is disposed on the surface of the first part of the cathode current collector, the second part of the cathode current collector is an empty foil area where the cathode active material layer 12 is not disposed, the cathode tab connecting piece 51 overlaps with the surface of the second part to form an overlapping area, the cathode tab connecting piece 51 is welded on the surface
  • the cathode tab connecting piece of the cathode electrode piece of the electrochemical device is welded to the surface of the second part of the cathode current collector (i.e., the edge empty foil area on the cathode current collector), when the cathode tab is led out from the cathode current collector in the present application, it is no longer necessary to electrically connect the cathode tab directly to the second part of the cathode current collector, but it is possible to electrically connect the cathode tab to the cathode tab through the cathode tab connecting piece welded to the second part of the cathode current collector. Based on this, when preparing the cathode electrode piece of the electrochemical device in the present application, the cathode electrode piece is not easy to wrinkle when the cathode electrode piece is cold pressed, which can effectively improve the preparation efficiency of the electrochemical device.
  • the electrochemical device 10 can be made by winding the cathode electrode sheet 1, the separator 3, and the anode electrode sheet 2. It should be understood that this is only for illustration and should not be regarded as a limitation of the present embodiment.
  • the separator 3 is disposed between the cathode electrode sheet 1 and the anode electrode sheet 2, which can isolate the cathode electrode sheet 1 and the anode electrode sheet 2, prevent the cathode and anode electrodes from short-circuiting inside the electrochemical device, and allow ions to pass through, and can maintain the function of the electrolyte between the cathode electrode sheet 1, the separator 3, and the anode electrode sheet 2.
  • the first part of the cathode current collector is referred to as the cathode current collector first part (labeled 111 in the figure), and the second part of the cathode current collector is referred to as the cathode current collector second part (labeled 112 in the figure).
  • the cathode current collector first part 111 and the cathode current collector second part 112 can be conductive foil.
  • the cathode current collector first portion 111 includes a first sub-portion 1111 and a second sub-portion 1112 connected to each other, the second sub-portion 1112 is connected to the cathode current collector second portion 112, the cathode active material layer 12 is disposed on the first sub-portion, and the second sub-portion is disposed with an insulating layer 13; along the width direction Y of the electrode sheet, the cathode current collector second portion 112 includes a first side close to the first sub-portion 1111 and a second side away from the first sub-portion 1111, and the cathode tab connecting piece 51 includes a first side close to the first sub-portion 1111 and a second side away from the first sub-portion 1111; wherein, there is a spacing between the cathode tab connecting piece 51 and the first sub-portion 1111, and the second side of the cathode current collector second portion 112 is located between the first side of the cathode
  • one method of preventing the cathode electrode sheet from wrinkling during cold pressing is to first cold press the cathode electrode sheet with the cathode active material layer and the insulating layer, and then stretch the edge empty foil area of the cathode current collector of the cathode electrode sheet before cold pressing, so that the deformation degree of the edge empty foil area of the cathode current collector and the insulating layer tends to be consistent, thereby preventing the cathode electrode sheet from wrinkling during subsequent cold pressing of the cathode electrode sheet.
  • the cathode electrode sheet is prone to breakage during the cold pressing process due to the increased cold pressing tension of the cathode electrode sheet, which also reduces the preparation rate of the electrochemical device.
  • the cathode electrode tab 41 when the cathode electrode tab 41 is led out from the cathode current collector second part 112 of the cathode current collector 11 (i.e., the edge empty foil area of the cathode current collector 11), the cathode electrode tab 41 may no longer be directly electrically connected to the cathode current collector second part 112, but may be electrically connected to the cathode electrode tab 41 through a cathode electrode tab connecting piece 51 welded to the cathode current collector second part 112.
  • the cathode current collector second part 112 i.e., the edge empty foil area of the cathode current collector 11
  • the problem of wrinkling of the cathode electrode sheet 1 during subsequent cold pressing of the cathode electrode sheet 1 can also be improved.
  • the cold pressing tension of the cathode electrode sheet 1 is also reduced, thereby improving the problem of easy breakage of the cathode electrode sheet 1 during the cold pressing process, and thus the preparation rate of the electrochemical device can be improved.
  • the insulating layer 13 can insulate and isolate the second sub-portion 1112 and the anode pole piece 2 , and can effectively prevent a short circuit between the cathode pole piece 1 and the anode pole piece 2 .
  • both the first sub-portion 1111 and the second sub-portion 1112 can be conductive foils.
  • the first sub-portion 1111 and the cathode current collector second portion 112 are respectively connected to both sides of the second sub-portion 1112 along the width direction of the electrode sheet.
  • Figures 4A, 4B and 4C also schematically show the position of the cathode tab 41 that is electrically connected to the cathode tab connecting piece 51.
  • Figures 4A, 4B and 4C are only used to schematically illustrate this embodiment and are not intended to limit this embodiment.
  • the cathode tab connecting piece 51 can prevent the thickness of the manufactured electrochemical device 10 from being too thick. And because ions can pass through the separator 3 and the cathode active material layer 12 and the anode active material layer 22, but cannot pass through the cathode tab connecting piece 51 (which will be introduced below, the cathode tab connecting piece 51 can be a conductive foil, etc., such as an aluminum-plated foil, etc.), the gap between the cathode tab connecting piece 51 and the cathode current collector first part 111 can prevent the cathode tab connecting piece 51 from being sandwiched between the cathode active material layer 12 (including the cathode active material) of the cathode pole piece 1 and the anode active material layer 22 (including the anode active material) of the anode pole piece 2, thereby hindering the transmission of cation and cathode ions.
  • the second side of the cathode current collector second portion 112 is located between the first side of the cathode tab connecting piece 51 and the second side of the cathode tab connecting piece 51 , which is equivalent to the cathode tab connecting piece 51 being an extension of the cathode current collector second portion 112 .
  • the cathode tab 41 and the anode tab 42 of the electrochemical device 10 in this embodiment may be located on the same side of the electrochemical device 10 , or may be located on different sides of the electrochemical device 10 .
  • the cathode active material layer 12 disposed on the first sub-portion 1111 of the cathode electrode sheet 1 includes a cathode active material, and the type of the cathode active material is not limited here, and may be, for example, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, etc.
  • the cathode active material layer 12 may be a coating, that is, the cathode active material layer 12 is coated on the first sub-portion 1111. In this way, the structural stability of the cathode active material layer 12 disposed on the first sub-portion 1111 can be ensured.
  • the electrochemical device 10 in the embodiment of the present application is briefly described below in combination with the preparation of the cathode electrode of the electrochemical device in the related art. It should be understood that it is only used to facilitate understanding and does not constitute any limitation to the present embodiment.
  • the cathode active material layer and the insulating layer of the cathode electrode sheet are coatings applied on the cathode current collector.
  • the structure A1 in FIG2 the structure A1 is actually a plurality of cathode electrode sheets that have not been further processed (in simple terms, the structure A1 is cut along the dotted line a1, and then cut along the dotted lines a2 and a3, respectively, so that the structure A1 is separated into four cathode electrode sheets 1′. This process will be described in detail below).
  • the structure A1 is obtained after the cathode active material layer 12′ and the insulating layer 13′ are applied to the cathode current collector 11′, and the structure A1 is cold pressed (for example, a step roller (i.e., a special cold pressing roller) adapted to the structure A1 can be used for cold pressing.
  • a step roller i.e., a special cold pressing roller
  • a different step roller size must be designed to match each structure A1 of different sizes. For specific details, refer to the related art of cold pressing of electrode sheets using step rollers, which will not be repeated here).
  • the edge empty foil area 14' of the cathode current collector 11' is different from the deformation degree of the coating area (i.e., the insulating layer 13' and the cathode active material layer 12'), it is easy to cause the structure A1 to wrinkle during the cold pressing process, that is, the cathode pole piece 1' prepared later is wrinkled. Therefore, the edge empty foil area 14' is generally stretched first to make its deformation tend to be consistent during the cold pressing process, thereby preventing the cathode pole piece from wrinkling when the structure A1 is subsequently cold pressed.
  • the cold-pressed structure A1 is cut along the dotted line a1 (for example, the cutting method can use laser cutting technology) to obtain two structures A2 (each structure A2 is equivalent to two cathode pole pieces 1'). Then the two structures A2 are cut along the dotted lines a2 and a3 respectively (for example, the cutting method can use laser cutting technology) to obtain four cathode pole pieces 1' as shown in Figure 2.
  • the cathode electrode sheet 1' is used to prepare an electrochemical device, the cathode electrode sheet 1' can be wound with a separator, an anode electrode sheet, etc., and the edge empty foil area 14' can be electrically connected to the cathode electrode tab (for example, by welding). Finally, the electrochemical device is successfully prepared.
  • the electrochemical device 10 in the embodiment of the present application is briefly described. It should be understood that it is only used to facilitate understanding and does not constitute any limitation to the present embodiment.
  • FIG3A the preparation process of the cathode electrode sheet 1 of an electrochemical device 10 in this embodiment is shown, and FIG3B shows an enlarged schematic diagram of T in FIG3A .
  • the cathode active material layer 12 and the insulating layer 13 of the cathode electrode sheet 1 are coatings respectively coated on the first sub-portion 1111 and the second sub-portion 1112 of the cathode current collector 11.
  • the structure B1 is actually a plurality of cathode electrode sheets 1 that have not been further processed (in simple terms, the structure A1 is cut along the dotted line b1, and then cut along the dotted lines b2 and b3 respectively, so that the structure B1 is separated into 4 cathode electrode sheets 1, and this process will be described in detail below).
  • the structure B1 is obtained after the cathode active material layer 12 and the insulating layer 13 are coated on the cathode current collector 11, and the structure B1 is cold pressed (the implementation method of cold pressing here can be understood by referring to the relevant technology of cold pressing the electrode sheet using a cold pressing roller, which will not be repeated here).
  • the cold pressed structure B1 is cut along the dotted line b1 (for example, the cutting method can use laser cutting technology) to obtain two structures B2, and the cathode tab connecting pieces 51 are respectively welded on the edge empty foil areas (that is, the cathode current collector second part 112) on both sides of the structure B2, and two structures B3 are obtained after welding (each structure B3 is equivalent to two cathode pole pieces 1).
  • the two structures B3 are cut along the dotted lines b2 and b3 respectively (for example, the cutting method can use laser cutting technology) to obtain four cathode pole pieces 1 as shown in FIG3A (in addition, the structure can be further understood with reference to FIG3B ).
  • the cathode electrode sheet 1 When the cathode electrode sheet 1 is used to prepare the electrochemical device 10, the cathode electrode sheet 1 can be wound with the separator 3, the anode electrode sheet 2, etc., and the cathode tab connecting sheet 51 can be electrically connected to the cathode tab 41 (for example, by welding). Finally, the electrochemical device 10 is successfully prepared.
  • FIG. 3A the first weld mark 61 formed by welding the cathode tab connecting piece 51 and the cathode current collector second part 112 is omitted in FIG. 3A , while the first weld mark 61 is schematically shown in the enlarged schematic diagram of FIG. 3B .
  • FIGS. 3A and 3B do not constitute any limitation to the present application.
  • the cathode current collector second portion 112 is a conductive foil, and the resistance R per square millimeter of the conductive foil (i.e., the cathode current collector second portion 112 ) satisfies: R ⁇ 20 m ⁇ , so that the cathode current collector second portion 112 has good conductivity and meets the use requirements of the electrochemical device 10 .
  • the first sub-portion 1111 and/or the second sub-portion 1112 of the first portion 111 of the cathode current collector may also be a conductive foil.
  • the resistance per square millimeter of the conductive foil of the first sub-portion 1111 and/or the second sub-portion 1112 is less than 20 m ⁇ , which also makes the first sub-portion 1111 and/or the second sub-portion 1112 have good conductivity and meet the use requirements of the electrochemical device 10.
  • the cathode current collector second portion 112 is welded to the cathode tab connecting piece 51, and the cathode tab 41 is electrically connected to the cathode tab connecting piece 51.
  • the cathode tab connecting piece 51 may also be a conductive foil material, and optionally, the resistance R per square millimeter of the cathode tab connecting piece 51 satisfies: R ⁇ 20 m ⁇ , so that the cathode tab connecting piece 51 has good conductivity and meets the use requirements of the electrochemical device 10.
  • the electrochemical device 10 when actually measuring the resistance R per square millimeter of the cathode current collector second part 112 or the cathode tab connecting piece 51 of the prepared electrochemical device 10, the electrochemical device 10 can be disassembled first, and then the clean part of the cathode current collector second part 112 or the cathode tab connecting piece 51 (i.e., the part without insulating material or cathode active material) can be taken for measurement using a resistance tester.
  • the insulating material or cathode active material attached to the cathode current collector second part 112 or the cathode tab connecting piece 51 can be washed away with an organic solvent such as alcohol, and then the clean part after washing can be taken for measurement using a resistance tester, or it can be measured in other ways, which are not limited here.
  • the specific material of the conductive foil is not specifically limited in this embodiment, and any material can be used on the basis of ensuring the conductive performance and structural strength, for example, the conductive foil includes: at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil.
  • the conductive foil of such material can ensure the conductive performance of the cathode current collector second part 112 and/or the cathode tab connecting piece 51 of the cathode electrode piece 1, and meet the use requirements of the electrochemical device 10.
  • the aluminum-plated foil includes at least one of: a foil with aluminum-plated surface on a polypropylene film and a foil with aluminum-plated surface on a polyethylene terephthalate film.
  • conductive foils can ensure the conductivity of the cathode current collector second portion 112 of the cathode electrode sheet 1 and/or the cathode tab connecting sheet 51, and meet the use requirements of the electrochemical device 10.
  • the cathode current collector second portion 112 and the cathode tab connecting piece 5 in the present application may be made of the same conductive foil material, or may be made of different conductive foil materials, which is not limited here.
  • the thickness L of the cathode tab connecting piece 51 satisfies: 4 ⁇ m ⁇ L ⁇ 25 ⁇ m.
  • the process difficulty of manufacturing the cathode tab 1 will be increased, and the cost will increase.
  • the strength is low, and it is difficult to meet the requirements of the structural strength of the cathode tab 1 and the cathode tab connecting piece 51; and when the thickness of the cathode tab connecting piece 51 is too thick, it will also lead to an increase in material cost and a decrease in the energy density benefit of the electrochemical device 10.
  • the thickness L in this embodiment satisfies the above-mentioned value range (i.e., 4 ⁇ m ⁇ L ⁇ 25 ⁇ m), which can better avoid the disadvantages of the cathode tab connecting piece 51 being too thin, and the disadvantages of the cathode tab connecting piece 51 being too thick, thereby meeting the use requirements of the electrochemical device 10 and improving the preparation rate of the electrochemical device 10.
  • the thickness L of the cathode tab connecting piece 51 satisfies: 5 ⁇ m ⁇ L ⁇ 20 ⁇ m.
  • L can select a suitable value as needed. For example, taking 5 ⁇ m ⁇ L ⁇ 20 ⁇ m as an example, L can be 5 ⁇ m, 7 ⁇ m, 10 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, etc., without specific limitation here.
  • the electrochemical device 10 when actually measuring the thickness L of the cathode tab connecting piece 51 of the prepared electrochemical device 10, the electrochemical device 10 can be disassembled first, and then the unwelded portion of the cathode tab connecting piece 5 between the first weld mark 61 and the second weld mark 62 (the first weld mark 61 and the second weld mark 62 will be introduced below) can be measured using a micrometer or a ten-thousandth caliper, or it can also be measured in other ways, which are not limited here.
  • the fracture strength S of the cathode tab connecting piece 51 satisfies: 80MPa ⁇ S ⁇ 800MPa. If the fracture strength of the cathode tab connecting piece 51 is too small, it is easy to break during the preparation process, which will increase the process difficulty of manufacturing the cathode tab 1 and increase the cost. If the fracture strength is too small, it is difficult to meet the requirements of the structural strength of the cathode tab 1 and the cathode tab connecting piece 51; and if the fracture strength S of the cathode tab connecting piece 51 is too large, it will also increase the process difficulty of manufacturing the cathode tab 1 and increase the cost.
  • the fracture strength S in this embodiment satisfies the above-mentioned value range (i.e., 80MPa ⁇ S ⁇ 800MPa), which can better avoid the disadvantages of too small fracture strength of the cathode tab connecting piece 51 and the disadvantages of too large fracture strength of the cathode tab connecting piece 51, thereby meeting the use requirements of the electrochemical device 10 and improving the preparation rate of the electrochemical device 10.
  • the fracture strength S of the cathode tab connecting piece 51 satisfies: 100MPa ⁇ S ⁇ 450MPa.
  • the fracture strength S of the cathode tab connecting piece 51 can select a suitable value as needed. For example, taking 100MPa ⁇ S ⁇ 450MPa as an example, the fracture strength S can be 100MPa, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, 400MPa, 450MPa, etc., which are not limited here.
  • the thickness range of the cathode current collector second part 112 of the cathode current collector 11 of the cathode electrode sheet 1 can be the same as the thickness range of the above-mentioned cathode tab connecting piece 51, that is, the thickness range of the cathode current collector second part 112 can be 4 ⁇ m ⁇ 25 ⁇ m, further optionally 5 ⁇ m ⁇ 20 ⁇ m, and the fracture strength range of the cathode current collector second part 112 can be the same as the fracture strength range of the above-mentioned cathode tab connecting piece 51, that is, the fracture strength range of the cathode current collector second part 112 can be 80MPa ⁇ 800MPa, further optionally 100MPa ⁇ 450MPa.
  • the thickness of the cathode current collector second part 112 and the thickness of the cathode tab connecting piece 51 can be the same or different, and the breaking strength of the cathode current collector second part 112 and the breaking strength of the cathode tab connecting piece 51 can be the same or different.
  • first sub-portion 1111 and/or the second sub-portion 1112 of the cathode current collector 11 of the cathode electrode sheet 1 is a conductive foil, it can be made of the same material as the cathode current collector second portion 112 and have the same thickness range as the cathode current collector second portion 112 .
  • the first sub-portion 1111 and/or the second sub-portion 1112 when it is a conductive foil, it can be at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil; and the aluminum-plated foil includes at least one of a polypropylene film surface aluminum-plated foil and a polyethylene terephthalate film surface aluminum-plated foil; the thickness of the first sub-portion 1111 and/or the second sub-portion 1112 ranges from 4 ⁇ m to 25 ⁇ m, preferably 5 ⁇ m to 20 ⁇ m; the breaking strength of the first sub-portion 1111 and/or the second sub-portion 1112 ranges from 80MPa to 800MPa, preferably 100MPa to 450MPa, thereby meeting the corresponding use requirements of the electrochemical device 10.
  • the insulating layer 13 is provided in the second sub-portion 1112 of the cathode electrode piece 1.
  • the material of the insulating layer 13 is not specifically limited, and it can be at least one of aluminum oxide and silicon oxide, for example.
  • the insulating layer 13 made of such a material is used to insulate and isolate the second sub-portion 1112 and the anode electrode piece 2, which can effectively prevent a short circuit between the cathode electrode piece 1 and the anode electrode piece 2.
  • the insulating layer 13 may be a coating (such as an aluminum oxide coating, a silicon oxide coating, etc.), that is, the insulating layer 13 is coated on the second sub-portion 1112 of the cathode plate 1. In this way, the structural stability of the insulating layer 13 disposed on the second sub-portion 1112 can be ensured.
  • a coating such as an aluminum oxide coating, a silicon oxide coating, etc.
  • the width d3 of the insulating layer 13 satisfies: 0.5 mm ⁇ d3 ⁇ 5 mm.
  • the width d3 of the insulating layer 13 is the distance d3 between the first side of the insulating layer 13 and the second side of the insulating layer 13 in the width direction Y of the electrode piece.
  • the insulating layer 13 within this width range can effectively insulate and isolate the second sub-portion 1112 of the cathode current collector 11 from the anode electrode piece 2 to prevent a short circuit between the two, and on the basis of meeting the use requirements of the electrochemical device 10, no additional cost is added.
  • the width d3 of the insulating layer 13 is equal to the width of the second sub-portion 1112 (i.e., the distance between the first side of the second sub-portion 1112 and the second side of the second sub-portion 1112 along the width direction Y of the electrode). It can be understood that the first side of the second sub-portion 1112 is the side of the second sub-portion 1112 close to the first sub-portion 1111 along the width direction Y of the electrode; the second side of the second sub-portion 1112 is the side of the second sub-portion 1112 away from the first sub-portion 1111 along the width direction Y of the electrode.
  • the welding tension between the second part of the current collector of the pole piece and the pole tab connecting piece is greater than or equal to 70N and less than or equal to 1000N.
  • the electrode piece is a cathode electrode piece 1
  • the cathode current collector second part 112 and the cathode tab connecting piece 51 are welded, and the welding tension F between the cathode current collector second part 112 and the cathode tab connecting piece 51 satisfies: 70N ⁇ F ⁇ 1000N.
  • the cathode tab connecting piece 51 is easily detached from the cathode current collector second part 112 when the electrochemical device 10 is used; and if the welding tension F between the cathode current collector second part 112 and the cathode tab connecting piece 51 is too large, the cost of preparing the electrochemical device 10 is affected.
  • the welding tension F in this embodiment satisfies the above-mentioned value range (i.e., 70N ⁇ F ⁇ 1000N), which can better avoid the disadvantage of too small welding tension F between the second part 112 of the cathode current collector and the cathode tab connecting piece 51, and can better avoid the disadvantage of too large welding tension F between the second part 112 of the cathode current collector and the cathode tab connecting piece 51, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation efficiency of the electrochemical device 10.
  • the above-mentioned value range i.e., 70N ⁇ F ⁇ 1000N
  • the welding tension F between the cathode current collector second part 112 and the cathode tab connecting piece 51 satisfies: 150N ⁇ F ⁇ 500N.
  • the disadvantage of too small welding tension between the cathode current collector second part 112 and the cathode tab connecting piece 51 can be better avoided, and the disadvantage of too large welding tension between the cathode current collector second part 112 and the cathode tab connecting piece 51 can be better avoided, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • the welding tension F can be selected as a suitable value as needed.
  • the welding tension F can be 150N, 200N, 300N, 350N, 400N, 500N, etc., and no specific limitation is made here.
  • the method of testing the welding tension F can refer to the relevant technology and is not limited here.
  • an exemplary method of testing the welding tension F can be the following process: take the samples of the cathode current collector second part 112 and the cathode pole tab connecting piece 51 after welding and put them into the tensile machine, along the width direction Y of the pole piece, the left clamp and the right clamp respectively clamp the cathode current collector second part 112 and the cathode pole tab connecting piece 51, the left clamp and the right clamp are separated by a suitable distance (for example, 20 mm), and the welding area (for example, the first welding mark 61 mentioned below) is set in the middle of the left clamp and the right clamp.
  • a suitable distance for example, 20 mm
  • the welding area for example, the first welding mark 61 mentioned below
  • the fracture strength of the cathode tab connecting piece 51 can also be tested in a similar manner to the above-mentioned test welding tension F. It is only necessary to take an appropriate width of the cathode tab connecting piece 51 (for example, 10 mm), clamp the cathode tab connecting piece 51 with the left and right clamps respectively, and then fix the left clamp, and pull the right clamp away from the left clamp at a suitable speed (for example, 1 mm/s), and then the fracture strength of the cathode tab connecting piece 51 can be tested.
  • the method of testing the fracture strength of each part of the cathode current collector 11 can be deduced by analogy, and will not be repeated here. Of course, this is only an example and not any limitation to the embodiments.
  • the welding between the cathode current collector second part 112 and the cathode tab connecting piece 51 can be performed by any welding method, such as welding by ultrasonic roll welding.
  • a welding method of ultrasonic roll welding is shown, in which the cathode current collector second part 112 is first overlapped with the cathode tab connecting piece 51 and placed on the roll welding seat 71, and then the roll welding head 72 is aligned with the cathode tab connecting piece 51 and the cathode current collector second part 112 above the roll welding seat 71 and ultrasonic welding is performed.
  • the roll welding head 72 emits high-frequency ultrasonic waves to the cathode tab connecting piece 51 and the cathode current collector second part 112.
  • the surfaces of the cathode tab connecting piece 51 and the cathode current collector second part 112 contact each other and generate heat energy, which causes the welding position of the cathode tab connecting piece 51 and the cathode current collector second part 112 to melt, so that the cathode tab connecting piece 51 and the cathode current collector second part 112 are finally welded.
  • this is merely an example of the embodiments of the present application and does not constitute any limitation to the present application.
  • the weld mark includes a first weld mark 61.
  • the first weld mark 61 is formed when the second part 112 of the cathode current collector is welded to the cathode pole tab connecting piece 51; along the width direction Y of the electrode piece, the first weld mark 61 includes a first side close to the first sub-part 1111 and a second side away from the first sub-part 1111; the second side of the first weld mark 61 is located on the cathode pole tab connecting piece 51, and there is a distance between the first weld mark 61 and the first sub-part 1111.
  • the second side of the first weld mark 61 is located on the cathode tab connecting piece 51, ensuring that the cathode tab connecting piece 51 can form a stable welding connection with the cathode current collector second part 112.
  • the first side of the first weld mark 61 can be located on the cathode current collector second part 112 or on the cathode tab connecting piece 51, which is not limited here.
  • the shape of the first weld mark 61 is not limited.
  • the first weld mark 61 can be a combination of multiple first sub-weld marks 611, and there is a spacing between each two adjacent first sub-weld marks 611.
  • the first sub-weld mark 611 can be composed of a plurality of small welds of regular or irregular shapes.
  • the shape of the small welds can be circular, rectangular, or other polygons.
  • the shape of the first sub-weld mark 611 formed by the arrangement of small welds can be a parallelogram, a rectangle (which can be a square), a triangle or other polygons, or can also be other irregular shapes.
  • the shape of the first sub-weld mark 611 is a rectangular shape composed of small welds, and the small welds are rectangular.
  • each first sub-weld mark 611 can be a complete weld mark. No limitation is made here.
  • the first weld mark 61 may also be a continuous weld mark.
  • the continuous weld mark may be a complete weld mark (the complete weld mark can be understood in conjunction with FIG9, and will not be described in detail here).
  • the continuous weld mark may also be composed of a plurality of small welds of regular or irregular shapes, for example, the shape of the small weld may be circular, rectangular, or other polygons, etc. (can be understood in conjunction with FIG8, and will not be described in detail here). This is not limited in this embodiment.
  • the welding area formed by welding the pole tab connecting piece to the surface of the second part of the current collector of the pole piece in the unfolded state of the pole piece refers to: the sum of the areas of all welding marks (i.e., small welding spots, complete welding marks, etc.) formed when the pole tab connecting piece is welded to the surface of the second part of the current collector of the pole piece;
  • the welding area refers to: the area of the minimum external area of all welding marks (i.e., small welding spots, complete welding marks, etc.) formed when the pole tab connecting piece is welded to the surface of the second part of the current collector of the pole piece;
  • the area where the pole tab connecting piece overlaps with the surface of the second part is the overlapping area (i.e., the area of the projection of the pole tab connecting piece on the surface of the second part along the thickness direction of the pole piece);
  • the welding area length refers to: the maximum distance between the two ends of the welding area along the length direction of the pole piece;
  • the overlapping area length refers to:
  • the weld area may refer to the sum of the areas of all welds (i.e., small welds, complete welds, etc.) included in the first weld 61 formed by welding the electrode tab connecting piece to the second part of the current collector of the electrode piece.
  • the weld area may refer to the area of the smallest circumscribed rectangular area of all welds (i.e., small welds, complete welds, etc.) included in the first weld 61.
  • the ratio of the weld area of the electrode piece to the weld area is greater than or equal to 20%, and the ratio of the weld area length to the overlap area length is greater than or equal to 60%.
  • the weld mark area is the area of the first weld mark 61.
  • the weld mark area (referred to as Sy1 here) is equal to the sum of the areas of each first sub-weld mark 611.
  • the continuous weld mark includes a combination of multiple small welds, and the weld mark area is equal to the sum of the areas of all the small welds; as shown in FIG9 , the continuous weld mark is a complete weld mark, and the weld mark area is equal to the area of the complete weld mark.
  • the length of the overlapping area is equal to the length of the pole piece, and the length of the welding area is h1. At this time, the ratio of the length of the welding area to the length of the overlapping area is greater than 60%; as shown in FIGS.
  • the length of the overlapping area is equal to the length of the pole piece, and the length of the welding area is h1, which is also equal to the length of the pole piece.
  • the ratio of the length of the welding area to the length of the overlapping area is equal to 60%;
  • d5 is the width of the first weld mark 61, that is, the distance between the first side of the first weld mark 61 and the second side of the first weld mark 61 along the width direction Y of the electrode piece.
  • the ratio of the weld area to the welding area is denoted as P.
  • the electrode is the cathode electrode 1
  • the situations in FIG. 6 and FIG. 8 should also satisfy P>20%.
  • the ratio of the length of the welding area to the length of the overlapping area cannot be too small, and must be at least greater than or equal to 60%, so as to ensure that the weld is evenly distributed in the welding area and the overlapping area, avoid the concentration of welds leading to excessive local strength or too low strength of other parts, and avoid the disadvantages of processing difficulties caused by the concentration of welds.
  • the ratio of the weld area to the weld area P>20%, and the ratio of the length of the weld area to the length of the overlap area is greater than or equal to 60%, which can meet the need for the tab connector of the electrochemical device to form a stable weld on the surface of the second part.
  • the width d5 of the first weld mark 61 satisfies: 0.1 mm ⁇ d5 ⁇ 10 mm. It can be understood that the width d5 of the first weld mark 61 is the distance between the first side of the first weld mark 61 and the second side of the first weld mark 61 along the width direction Y of the electrode sheet.
  • the width d5 of the first weld mark 61 can also be understood in conjunction with FIG. 6, FIG. 7, FIG. 8, and FIG. 9.
  • the width d5 of the first weld mark 61 is too small (i.e., d5 ⁇ 0.1mm), it is difficult to ensure that the welding tension between the cathode current collector second portion 112 and the cathode tab connecting sheet 51 meets the requirements, resulting in the aforementioned disadvantage of the welding tension F being too small; and when the width d5 of the first weld mark 61 is too large (i.e., d5>10mm), welding is difficult and the cost is increased.
  • the width d5 of the first weld mark 61 satisfies the above value range (0.1mm ⁇ d5 ⁇ 10mm), which can avoid the disadvantage of the first weld mark 61 being too small, and can also avoid the disadvantage of the first weld mark 61 being too large, thereby meeting the use requirements of the electrochemical device 10, and further improving the preparation rate of the electrochemical device 10.
  • the width d5 of the first weld mark 61 can be selected as a suitable value as needed.
  • d5 can be 0.1 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, etc., and no specific limitation is made here.
  • the spacing d6 between the first side of the first weld mark 61 and the first side of the cathode tab connecting piece 51 satisfies: 0mm ⁇ d6 ⁇ 5mm; or, if the first side of the first weld mark 61 is located on the cathode tab connecting piece 51, the spacing d6 between the first side of the first weld mark 61 and the first side of the cathode tab connecting piece 51 satisfies: 0mm ⁇ d6 ⁇ 20mm.
  • FIG. 4B an example is shown in which the first side of the first weld mark 61 is located on the second portion 112 of the cathode current collector (it should be noted that although the first side of the first weld mark 61 in FIG. 4B is not in contact with the second portion 112 of the cathode current collector, and there is a gap between the two, the style actually expressed in FIG. 4B is that the first side of the first weld mark 61 is in direct contact with the second portion 112 of the cathode current collector to be located on the second portion 112 of the cathode current collector so that the cathode tab connecting piece 5 and the second portion 112 of the cathode current collector are welded.
  • the first side of the first weld mark 61 is located on the second portion 112 of the cathode current collector.
  • 4A and 4C an example is shown in which the first side of the first weld mark 61 is located on the cathode tab connecting piece 51, which is equivalent to the first side of the first weld mark 61 exceeding the first side of the cathode tab connecting piece 51 along the opposite direction of the width direction Y of the electrode piece, and the first weld mark 61 covers the first side of the cathode tab connecting piece 51.
  • the spacing d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection sheet 51 satisfies: 0mm ⁇ d6 ⁇ 3mm; or, if the first side of the first weld mark 61 is located on the cathode tab connection sheet 51, the spacing d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection sheet 51 satisfies: 0mm ⁇ d6 ⁇ 10mm.
  • the disadvantages caused when the first side of the first weld mark 61 exceeds the first side of the cathode tab connection sheet 51 too much in the opposite direction of the width direction of the electrode sheet can be avoided, and the disadvantages caused when the first side of the first weld mark 61 exceeds the first side of the cathode tab connection sheet 51 too much in the width direction of the electrode sheet can be avoided, thereby further meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • d6 can select a suitable value as needed.
  • 0mm ⁇ d6 ⁇ 3mm is used as an example, and d6 can be 0mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3.0mm, etc., which is not limited here.
  • 0mm ⁇ d6 ⁇ 10mm is used as an example, and d6 can be 0mm, 1mm, 3mm, 5mm, 7mm, 8mm, 10mm, etc., which is not limited here.
  • the first projection can be the projection of the second side of the first weld mark 61 on the cathode tab connecting sheet 51 along the thickness direction of the cathode tab connecting sheet 51
  • the second projection can be the projection of the second part 112 of the cathode current collector on the cathode tab connecting sheet 51 along the thickness direction of the cathode tab connecting sheet 51.
  • the spacing d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second portion 112 is too large (for example, d7>15mm when the first projection and the second projection overlap), that is, when the second side of the cathode current collector second portion 112 exceeds the second side of the first weld mark 61 too much in the width direction of the electrode sheet, the unconstrained cathode current collector second portion 112 is too wide, which increases the process difficulty when preparing the cathode electrode sheet 1 and affects the preparation rate of the electrochemical device 10; and when the first projection and the second projection do not overlap, the first weld mark 61 is When the spacing d7 between the second side and the second side of the second part 112 of the cathode current collector is too large (for example, d7>7mm when there is no overlap between the first projection and the second projection), that is, when the second side of the first weld mark 61 exceeds the second
  • the spacing d7 between the second side of the first weld mark 61 and the second side of the second part 112 of the cathode current collector satisfies: 0mm ⁇ d7 ⁇ 10mm; or, if the first projection of the second side of the first weld mark 61 on the cathode tab connecting sheet 51 does not overlap with the second projection of the second part 112 of the cathode current collector on the cathode tab connecting sheet 51, then the spacing d7 between the second side of the first weld mark 61 and the second side of the second part 112 of the cathode current collector satisfies: 0mm ⁇ d7 ⁇ 3mm.
  • d7 can select a suitable value as needed.
  • 0mm ⁇ d7 ⁇ 10mm is used as an example, and d7 can be 0mm, 1mm, 3mm, 5mm, 8mm, 9mm, 10mm, etc., and no specific restrictions are made here.
  • 0mm ⁇ d7 ⁇ 3mm is used as an example, and d7 can be 0mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc., and no specific restrictions are made here.
  • the electrochemical device further includes a pole ear, which is electrically connected to the pole ear connecting piece of the pole piece by welding.
  • the electrochemical device further includes a shell, and the pole ear portion extends out of the shell.
  • the cathode pole piece 1, the separator 3, and the anode pole piece 2 can be arranged in the shell, and the shell can protect them.
  • the shell can be made of a metal plastic film, and the metal plastic film can be a steel plastic film, an aluminum plastic film, etc.
  • the pole piece of the electrochemical device 10 can be a cathode pole piece 1 and/or an anode pole piece 2.
  • pole piece of the electrochemical device When the pole piece of the electrochemical device is a cathode pole piece 1, the pole ear 4 electrically connected to the cathode pole ear connecting piece of the cathode pole piece 1 by welding is a cathode pole ear; and when the pole piece of the electrochemical device is an anode pole piece 2, the pole ear 4 electrically connected to the anode pole ear connecting piece of the anode pole piece 2 by welding is an anode pole ear.
  • the cathode electrode ear 41 is electrically connected to the cathode electrode ear connecting piece 51 by welding, and a second weld mark 62 is formed on the cathode electrode ear connecting piece 51; along the width direction Y of the electrode piece, the second weld mark 62 includes a first side close to the first sub-part 1111 and a second side away from the first sub-part 1111; wherein, the spacing d8 between the second side of the first weld mark 61 and the first side of the second weld mark 62 satisfies: 0mm ⁇ d8 ⁇ 10mm.
  • the specific welding process for welding the cathode tab 41 and the cathode tab connecting piece 51 is not limited in the present application.
  • the welding process may be transfer welding
  • the second weld mark 62 may be a transfer welding weld mark.
  • the second weld mark 62 formed on the cathode tab connecting sheet 51 cannot overlap with the first weld mark 61. If they overlap, the welding effect between the cathode tab 41 and the cathode tab connecting sheet 51 will be affected, so that the welding tension between the two will be reduced; and if the spacing d8 between the second side of the first weld mark 61 and the first side of the second weld mark 62 is too large (for example, when d8>10mm), it is easy to affect the energy density of the electrochemical device 10.
  • d8 can also select a suitable value as needed.
  • d8 can be 1mm, 3mm, 5mm, 7mm, 9mm, 10mm, etc., and no specific limitation is made here.
  • the width d1 of the cathode tab connecting piece 51 is not limited (refer to FIG. 4A, FIG. 4B, and FIG. 4C, that is, the width d1 of the cathode tab connecting piece 51 is the distance between the first side of the cathode tab connecting piece 51 and the second side of the cathode tab connecting piece 51 along the width direction Y of the electrode piece), and the needs of the electrochemical device 10 can be met.
  • the width d1 of the cathode tab connecting piece 51 satisfies: 3mm ⁇ d1 ⁇ 25mm.
  • the width d1 of the cathode tab connecting piece 51 is too small, it is difficult to weld the cathode tab connecting piece 51 to the cathode current collector second portion 112 when preparing the electrochemical device 10; and when the width d1 of the cathode tab connecting piece 51 is too large, the edge of the cathode tab connecting piece 51 is prone to collapse during the preparation of the cathode tab 1, and it is also easy to accidentally cause the cathode tab connecting piece 51 to break.
  • the width of the cathode tab connecting piece 51 in this embodiment meets the above-mentioned value range (i.e., 3mm ⁇ d1 ⁇ 25mm), which can better avoid the disadvantages of the cathode tab connecting piece 51 being too small and the disadvantages of the cathode tab connecting piece 51 being too large, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • the width d1 of the cathode tab connecting piece 51 satisfies: 5mm ⁇ d1 ⁇ 25mm.
  • the disadvantage of the cathode tab connecting piece 51 being too small can be avoided, and the disadvantage of the cathode tab connecting piece 51 being too large can be avoided better, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • the width d1 of the cathode tab connecting piece 51 can be selected as a suitable value as needed.
  • d1 can be 5mm, 10mm, 15mm, 18mm, 20mm, 23mm, 25mm, etc., which is not limited here.
  • the width d2 of the cathode current collector second part 112 of the cathode current collector 11 is not limited (refer to FIG. 4A, FIG. 4B, and FIG. 4C, the width d2 of the cathode current collector second part 112 is the distance between the first side of the cathode current collector second part 112 and the second side of the cathode current collector second part 112 along the width direction Y of the electrode sheet), and the requirements of the electrochemical device 10 can be met.
  • the width d2 of the cathode current collector second part 112 satisfies: 1mm ⁇ d2 ⁇ 20mm.
  • the width of the second part 112 of the cathode current collector is too small, it is difficult to ensure the welding width when preparing the electrochemical device 10, resulting in greater difficulty in welding the cathode tab connecting sheet 51 and the second part 112 of the cathode current collector; and when the width of the second part 112 of the cathode current collector is too large, in the process of preparing the cathode electrode sheet 1, the second part 112 of the cathode current collector is more likely to wrinkle after cold pressing, which is easy to increase the energy density loss and increase the cost.
  • the width of the second part 112 of the cathode current collector in this embodiment meets the above-mentioned value range (i.e., 1mm ⁇ d2 ⁇ 20mm), which can better avoid the disadvantages of the second part 112 of the cathode current collector being too small, and can better avoid the disadvantages of the second part 112 of the cathode current collector being too large, thereby meeting the use requirements of the electrochemical device 10, and further improving the preparation rate of the electrochemical device 10.
  • the width d2 of the second cathode current collector portion 112 satisfies: 1mm ⁇ d2 ⁇ 10mm.
  • the disadvantage of the second cathode current collector portion 112 being too small can be avoided, and the disadvantage of the second cathode current collector portion 112 being too large can be avoided, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • the width d2 of the cathode current collector second portion 112 can be selected as a suitable value as needed. For example, if 1 mm ⁇ d2 ⁇ 10 mm, d2 can be 1 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., which is not limited here.
  • the insulating layer 13 includes a first side close to the first sub-portion 1111 and a second side away from the first sub-portion 1111; if the first side of the cathode pole tab connecting piece 51 is located on the insulating layer 13, the spacing d4 between the first side of the cathode pole tab connecting piece 51 and the second side of the insulating layer 13 satisfies: 0mm ⁇ d4 ⁇ 8mm; or, if the first side of the cathode pole tab connecting piece 51 is located on the cathode current collector second portion 112, the spacing d4 between the first side of the cathode pole tab connecting piece 51 and the second side of the insulating layer 13 satisfies: 0mm ⁇ d4 ⁇ 10mm.
  • the excess exceeds too much (for example, d4>8mm), it is easy to cause the thickness of the manufactured electrochemical device 10 to be too large; referring to Figures 4A and 4B, the first side of the cathode tab connecting piece 51 is located on the cathode current collector second part 112, and when the distance d4 between the first side of the cathode tab connecting piece 51 and the second side of the insulating layer 13 is too large (for example, d4>10mm), it is impossible to effectively solve the problem of folding after the cathode current collector second part 112 and the cathode tab connecting piece 51 are welded.
  • the d4 in this embodiment satisfies the above-mentioned value range, which can better avoid the disadvantage that the first end of the cathode tab connecting piece 51 exceeds the first side of the second part 112 of the cathode current collector too much in the opposite direction of the width direction Y of the electrode piece, and can also better avoid the disadvantage that the first side of the cathode tab connecting piece 51 is located on the second part 112 of the cathode current collector and d4 is too large, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation efficiency of the electrochemical device 10.
  • the gap d4 between the first side of the cathode tab connector 51 and the second side of the insulating layer 13 satisfies: 0mm ⁇ d4 ⁇ 5mm.
  • the first side of the cathode tab connector 51 is located on the second part 112 of the cathode current collector, and the disadvantage of d4 being too large can be avoided, thereby meeting the use requirements of the electrochemical device 10 and further improving the preparation rate of the electrochemical device 10.
  • the electrode piece includes a cathode electrode piece and an anode electrode piece. Since the cathode electrode piece of the electrochemical device is welded to the surface of the second part of the cathode current collector (i.e., the edge empty foil area on the cathode current collector), and the anode electrode piece of the anode electrode piece is welded to the surface of the second part of the anode current collector (i.e., the edge empty foil area on the anode current collector), when the cathode electrode piece is led out from the cathode current collector in the present application, it is no longer necessary to electrically connect the cathode electrode piece directly to the second part of the cathode current collector, but it can be electrically connected to the cathode electrode piece through the cathode electrode piece welded to the second part of the cathode current collector, and in the present invention, When the anode tab is led out from the anode current collector in the application, the anode tab may no longer
  • the cathode tab when preparing the cathode tab of the electrochemical device in the present application, the cathode tab is not easy to wrinkle when the cathode tab is cold pressed, and when preparing the anode tab of the electrochemical device in the present application, the anode tab is not easy to wrinkle when the anode tab is cold pressed. Therefore, the electrochemical device is made by using such cathode tab and anode tab, which can effectively improve the preparation efficiency of the electrochemical device.
  • the embodiment of the present application provides an electrical device 20 , which includes any one of the electrochemical devices 10 provided above.
  • the electrochemical device 10 can be used to supply power to various electrical devices in the electrical equipment 20 .
  • the preparation rate of the electrochemical device 10 is relatively high, and therefore the preparation rate of the electrical equipment 20 is also relatively high.
  • the electrochemical device 10 is a lithium-ion battery as an example.
  • the electrochemical device of Comparative Example 1 is a conventional winding structure.
  • the difference between Comparative Example 2 and Example 1 is that the ratio of the weld print area to the weld zone area is less than 20%, and the ratio of the weld zone length to the overlap zone length is less than 60%. Since the welding strength does not meet the requirements, during the preparation process of the electrochemical device, the welding strength is unstable, the pole ear connecting piece is partially separated from the surface of the second part of the cathode, and it is inconvenient to measure.
  • Embodiment 1 is formed by winding the cathode electrode sheet of embodiment 1 in Table 1 and the anode electrode sheet of conventional structure, and in the cathode electrode sheet, the ratio of the weld area to the weld area is greater than or equal to 20%, and the ratio of the weld area length to the overlap area length is greater than or equal to 60%, so as to meet the welding stability requirements.
  • Embodiments 2-16 are the same as embodiment 1. In addition, compared with Comparative Example 1, in Examples 1-16, the stretching of the empty foil area at the edge of the cathode collector is cancelled before cold pressing when preparing the cathode electrode sheet.
  • the cathode ear connecting piece is welded on the empty foil area at the edge of the cathode collector (i.e., the second part of the cathode collector), and the step roller is cancelled during the cold pressing process, and the other parameters are the same; and in Examples 1-18, compared with Comparative Example 1, the stretching of the empty foil area at the edge of the cathode collector is cancelled before cold pressing when preparing the cathode electrode sheet. Instead, the cathode ear connecting piece is welded on the empty foil area at the edge of the cathode collector (i.e., the second part of the cathode collector), and the step roller is cancelled during the cold pressing process, and the other parameters are the same. In Comparative Example 2, the experimental data cannot be measured because the ratio of the weld print area to the welding area and the ratio of the welding area length to the overlapping area length do not meet the requirements.
  • the tab folding ratio may refer to the ratio of the folding of the cathode tab connecting piece 51 and the cathode current collector second portion 112 (which can be understood in conjunction with Figures 3A, 3B and 4A, 4B, and 4C), while for Comparative Examples 1 to 2, the tab folding ratio may refer to the ratio of the folding of the edge empty foil area 14' (which can be understood in conjunction with Figure 2).
  • the electrochemical device 10 in the embodiments of the present application significantly improves the wrinkling of the cathode electrode sheet 1 after cold pressing, and also significantly improves the folding of the electrode ear, compared with the electrochemical device in the related art. Therefore, by making the electrochemical device 10 with such a cathode electrode sheet 1, the preparation efficiency of the electrochemical device 10 can be effectively improved.

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Abstract

本申请实施例提供了一种电化学装置及用电设备。该电化学装置包括：极片，极片包括集流体、活性材料层及极耳连接片，在极片展开状态下，集流体沿极片的宽度方向包括第一部分及第二部分，活性材料层设置在第一部分的表面，极耳连接片与第二部分的表面重叠形成重叠区，极耳连接片焊接在第二部分的表面以与第二部分形成电连接，沿极片的长度方向，焊印面积与焊接区面积之比大于或等于20％，焊接区长度与重叠区长度之比大于或等于60％。

Description

电化学装置及用电设备 技术领域
本申请实施例涉及电化学技术领域，尤其涉及一种电化学装置及用电设备。
背景技术
随着科技的不断发展，电化学装置(包括但不限于锂离子电池、钠离子电池等)得到了广泛的应用，其为人们使用平板电脑、手机、电动交通工具、储能设备等设备提供了便利。
在相关技术中的一类电化学装置中，其由阴极极片、阳极极片以及设置于两者之间的隔离膜构成，其在制备过程中，需在阴极极片和阳极极片上的集流体的边缘空白区域电连接极耳。对于这类电化学装置而言，如何提高其制备优率是一个需要解决的技术问题。
发明内容
有鉴于此，本申请实施例提供一种电化学装置及用电设备，以至少部分解决上述问题。
根据本申请实施例的第一方面，提供一种电化学装置，包括：极片，极片包括集流体、活性材料层及极耳连接片，在极片展开状态下，集流体沿极片的宽度方向包括第一部分及第二部分，活性材料层设置在第一部分的表面，第二部分为未设置活性材料层的空箔区，极耳连接片与第二部分的表面重叠形成重叠区，极耳连接片焊接在第二部分的表面以与第二部分形成电连接，沿极片的长度方向，焊印面积与焊接区面积之比大于或等于20％，焊接区长度与重叠区长度之比大于或等于60％。
本申请实施例中，极片包括阴极极片和阳极极片，由于该电化学装置的阴极极片的阴极极耳连接片焊接在阴极集流体的第二部分(即阴极集流体上的边缘空箔区)的表面，阳极极片的阳极极耳连接片焊接在阳极集流体的第二部分(即阳极集流体上的边缘空箔区)的表面，因此在本申请中将阴极极耳从阴极集流体上引出时，可以不再是直接在阴极集流体的第二部分上电连接阴极极耳，而可以通过与阴极集流体的第二部分相焊接的阴极极耳连接片与阴极极耳电连接，并且在本申请中将阳极极耳从阳极集流体上引出时，可以不再是直接在阳极集流体的第二部分上电连接阳极极耳，而可以通过与阳极集流体的第二部分相焊接的阳极极耳连接片与阳极极耳电连接，基于此，在制备本申请中的电化学装置的阴极极片时，在对阴极极片进行冷压时阴极极片不易打皱，且在制备本申请中的电化学装置的阳极极片时，在对阳极极片进行冷压时阳极极片不易打皱，因而通过这样的阴极极片和阳极极片制成电化学装置，能够有效地提高电化学装置的制备优率。
此外，本申请的电化学装置沿极片的长度方向，焊印面积与焊接区面积之比大于或等于20％，可以保证第二部分可以与极耳连接片能够形成稳定焊接，且焊接区长度与重叠区长度之比大于或等于60％，可以保证焊印在焊接区在重叠区分布均匀，避免焊印集中导致局部强度过大或者其他部分的强度过小，避免由此导致的加工困难。
可选地，极片为阴极极片，第一部分包括相连接的第一子部分和第二子部分，第二子部分与第二部分相连接，活性材料层设置于第一子部分上，第二子部分上设置有绝缘层；沿极片的宽度方向，第二部分包括靠近第一子部分的第一侧和远离第一子部分的第二侧，极耳连接片包括靠近第一子部分的第一侧和远离第一子部分的第二侧；其中，极耳连接片与第一子部分存在间距，且第二部分的第二侧，位于极耳连接片的第一侧和极耳连接片的第二侧之间。
在相关技术中，在阴极极片制备过程中，其中一种防止阴极极片在冷压时打皱的方式是：先将设置好阴极活性材料层和绝缘层的阴极极片进行冷压，在进行冷压前先将阴极极片的阴极集流体的边缘空箔区进行拉伸，使得阴极集流体的边缘空箔区和绝缘层的变形程度趋于一致，从而防止后续对阴极极片进行冷压时阴极极片打皱。但是，这样虽能减缓冷压时阴极极片的打皱问题，但由于增加了阴极极片的冷压张力，导致冷压过程中的阴极极片容易出现断裂现象，也降低了电化学装置的制备优率。而本申请实施例中，在将阴极极耳从阴极集流体的阴极集流体第二部分(即阴极集流体的边缘空箔区)上引出时，可以不再是直接在阴极集流体第二部分上电连接阴极极耳，而可以通过与阴极集流体第二部分相焊接的阴极极耳连接片与阴极极耳电连接，这样就使得在制备电化学装置 的阴极极片时，在对阴极极片进行冷压前可以不必对该阴极极片的阴极集流体第二部分(即阴极集流体的边缘空箔区)进行拉伸，也同样能够改善后续对阴极极片进行冷压时阴极极片打皱的问题，并且由于可以不必对阴极极片的阴极集流体第二部分(即阴极集流体的边缘空箔区)进行拉伸，也减小了阴极极片的冷压张力，从而改善了冷压过程中的阴极极片容易出现断裂的问题，因此能够提高电化学装置的制备优率。另外本申请的绝缘层能够对第二子部分和阳极极片进行绝缘和隔离，可以有效防止阴极极片和阳极极片之间发生短路。
可选地，沿极片的宽度方向，极耳连接片的宽度d1满足：3mm≤d1≤25mm。
以极片为阴极极片为例，由于阴极极耳连接片的宽度d1过小时，在制备电化学装置时，将阴极极耳连接片与阴极集流体第二部分进行焊接时难度较大；而阴极极耳连接片的宽度d1过大时，在制备阴极极片的过程中，阴极极耳连接片的边缘容易发生塌陷，还容易意外导致阴极极耳连接片断裂。本实施例中的阴极极耳连接片的宽度满足上述的取值范围(即3mm≤d1≤25mm)，既能够较好地避免阴极极耳连接片的宽度过小的弊端，又能较好地避免阴极极耳连接片的宽度过大的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，沿极片的宽度方向，第二部分的宽度d2满足：1mm≤d2≤20mm。
以极片为阴极极片为例，由于阴极集流体第二部分的宽度过小时，在制备电化学装置时，难以保证焊接宽度，导致将阴极极耳连接片与阴极集流体第二部分进行焊接时难度较大；而阴极集流体第二部分的宽度过大时，在制备阴极极片的过程中，在冷压后阴极集流体第二部分更容易打皱，容易增大能量密度损失，导致成本增加。本实施例中的阴极集流体第二部分的宽度满足上述的取值范围，既能够较好地避免阴极集流体第二部分的宽度过小的弊端，又能较好地避免阴极集流体第二部分的宽度过大的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，沿极片的宽度方向，绝缘层的宽度d3满足：0.5mm≤d3≤5mm。
本实施例采用这种宽度范围内的绝缘层，可以有效将阴极集流体的第二子部分与阳极极片进行绝缘和隔离，防止两者之间短路，在满足电化学装置的使用需求的基础上，不会额外增加成本。
可选地，沿极片的宽度方向，绝缘层包括靠近第一子部分的第一侧和远离第一子部分的第二侧；若极耳连接片的第一侧位于绝缘层上，则极耳连接片的第一侧与绝缘层的第二侧之间的间距d4满足：0mm≤d4≤8mm；或者，若极耳连接片的第一侧位于第二部分上，则极耳连接片的第一侧与绝缘层的第二侧之间的间距d4满足：0mm≤d4≤10mm。
以极片为阴极极片为例，阴极极耳连接片的第一侧位于绝缘层上时，相当于阴极极耳连接片焊接到阴极集流体第二部分后，阴极极耳连接片的第一端沿极片的宽度方向的反方向超出阴极集流体第二部分的第一侧，当超出过多时(例如d4＞8mm)，易导致制成的电化学装置厚度过大；阴极极耳连接片的第一侧位于阴极集流体第二部分上，阴极极耳连接片的第一侧与绝缘层的第二侧的间距过大时(例如d4＞10mm)，则无法有效地解决阴极集流体第二部分与阴极极耳连接片相焊接后发生翻折的问题。本实施例中的d4满足这样的取值范围，既能够较好地避免阴极极耳连接片的第一端沿极片的宽度方向的反方向超出阴极集流体第二部分的第一侧过多时的弊端，又能较好地避免阴极极耳连接片的第一侧位于阴极集流体第二部分上，d4过大时的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，焊印包括第一焊印，第一焊印为第二部分与极耳连接片相焊接时形成；沿极片的宽度方向，第一焊印包括靠近第一子部分的第一侧和远离第一子部分的第二侧；第一焊印的第二侧位于极耳连接片上，且第一焊印与第一子部分存在间距。
以极片为阴极极片为例，本申请的第一焊印的第二侧位于阴极极耳连接片上，保证阴极极耳连接片能够与阴极集流体第二部分形成稳定的焊接连接。
可选地，沿极片的宽度方向，第一焊印的宽度d5满足：0.1mm≤d5≤10mm。
以极片为阴极极片为例，由于第一焊印的宽度d5过小时(即d5<0.1mm)，难以保证阴极集流体第二部分与阴极极耳连接片之间的焊接拉力满足需求，从而造成阴极集流体第二部分与阴极极耳连接片之间的焊接拉力焊接拉力过小时的弊端；而第一焊印的宽度d5过大时(即d5>10mm)，焊接难度大，且额外增加了成本。本实施例中的第一焊印的宽度d5满足上述取值范围(0.1mm≤d5≤10mm)内，可以避免第一焊印的宽度过小的弊端，也能避免第一焊印的宽度过大的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，若第一焊印的第一侧位于第二部分上，则第一焊印的第一侧与极耳连接片的第一侧之间的间距d6满足：0mm≤d6≤5mm；或者，若第一焊印的第一侧位于极耳连接片上，则第一焊印的第一侧与极耳连接片的第一侧之间的间距d6满足：0mm≤d6≤20mm。
以极片为阴极极片为例，由于在第一焊印的第一侧沿极片的宽度方向的反方向超出阴极极耳连接片的第一侧过多时(例如第一焊印的第一侧位于阴极集流体第二部分上时的d6>5mm)，不存在阴极活性材料的部分较多，因此不能提供能量的部分的空间占比也较大，使得能量密度损失严重，影响后续将阴极极耳与阴极极耳连接片进行电连接(例如阴极极耳与阴极极耳连接片以焊接的形式形成电连接)，在这过程中也容易对阴极极耳连接片造成损伤，最终影响制成的电化学装置的电性能；而在第一焊印的第一侧沿极片的宽度方向超出阴极极耳连接片的第一侧过多时(例如第一焊印的第一侧位于阴极极耳连接片上时的d6>30mm时)，则存在无约束状态的阴极极耳连接片过宽的情况，在制备阴极极片时，增加了工艺难度，影响电化学装置的制备优率。本申请通过采取这样的d6的取值范围，既能够避免在第一焊印的第一侧沿极片的宽度方向的反方向超出阴极极耳连接片的第一侧过多时产生的弊端，又能够避免在第一焊印的第一侧沿极片的宽度方向超出阴极极耳连接片的第一侧过多时产生的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，若第一焊印的第二侧在极耳连接片上的第一投影，与第二部分在极耳连接片上的第二投影存在重叠，则第一焊印的第二侧与第二部分的第二侧之间的间距d7满足：0mm≤d7≤15mm；或者，若第一焊印的第二侧在极耳连接片上的第一投影，与极片上的第二部分在极耳连接片上的第二投影不存在重叠，则第一焊印的第二侧与第二部分的第二侧之间的间距d7满足：0mm≤d7≤7mm。
以极片为阴极极片为例，由于在第一投影与第二投影存在重叠时，第一焊印的第二侧与阴极集流体第二部分的第二侧之间的间距d7过大(例如在第一投影与第二投影存在重叠时的d7>15mm)，也即阴极集流体第二部分的第二侧沿极片的宽度方向超出第一焊印的第二侧过多时，则存在无约束状态的阴极集流体第二部分过宽的情况，在制备阴极极片时，增加了工艺难度，影响电化学装置的制备优率；而在第一投影与第二投影不存在重叠时，第一焊印的第二侧与阴极集流体第二部分的第二侧之间的间距d7过大(例如在第一投影与第二投影不存在重叠时的d7>7mm)，也即第一焊印的第二侧沿极片的宽度方向超出阴极集流体第二部分的第二侧过多时，则使得能量密度损失严重，影响后续在将阴极极耳与阴极极耳连接片进行电连接(例如阴极极耳与阴极极耳连接片以焊接的形式形成电连接)，在这过程中也容易对阴极极耳连接片造成损伤，最终影响制成的电化学装置的电性能。本申请通过采取这样的d7的取值范围，既能够避免在阴极集流体第二部分的第二侧沿极片的宽度方向超出第一焊印的第二侧过多时产生的弊端，又能够避免第一焊印的第二侧沿极片的宽度方向超出阴极集流体第二部分的第二侧过多时产生的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，电化学装置还包括极耳，极耳通过焊接与极耳连接片形成电连接，并在极耳连接片上形成第二焊印；沿极片的宽度方向，第二焊印包括靠近第一子部分的第一侧和远离第一子部分的第二侧；其中，第一焊印的第二侧与第二焊印的第一侧之间的间距d8满足：0mm＜d8≤10mm。
以极片为阴极极片为例，由于阴极极耳通过焊接与阴极极耳连接片形成电连接时，在阴极极耳连接片上形成的第二焊印与第一焊印不能重叠，若重叠则会影响阴极极耳与阴极极耳连接片之间的焊接效果，使得两者的焊接拉力降低；而若第一焊印的第二侧与第二焊印的第一侧之间的间距d8过大时(例如d8>10mm时)，则容易影响电化学装置的能量密度。本实施例中通过采取这样的d8的取值范围，既能够避免第二焊印与第一焊印重叠时产生的弊端，又能够避免第一焊印的第二侧与第二焊印的第一侧之间的间距d8过大时产生的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
可选地，第二部分与极耳连接片之间的焊接拉力大于等于70N且小于等于1000N。
由于第二部分与极耳连接片之间的焊接拉力过小时，容易在使用电化学装置时导致极耳连接片从第二部分上脱落；而第二部分与极耳连接片之间的焊接拉力过大时，影响在制备电化学装置时的成本。本实施例中的焊接拉力满足上述的取值范围，既能够较好地避免第二部分与极耳连接片之间的焊接拉力过小的弊端，又能较好地避免第二部分与极耳连接片之间的焊接拉力过大的弊端，从而满足电化学装置的使用需要，进而提高电化学装置的制备优率。
根据本申请实施例的另一方面，提供了一种用电设备，其包括上述的电化学装置。
本申请实施例中的用电设备包括上述第一方面提供的电化学装置，由于该电化学装置的制备优率较高，因此该用电设备的制备优率也较高。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请实施例中记载的一些实施例，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的附图。
图1为根据本申请实施例的一个示例的电化学装置的示意图。
图2为根据相关技术中一个示例的电化学装置的阴极极片的制备过程。
图3A为根据本申请实施例一种示例的电化学装置的阴极极片的制备过程。
图3B为根据图3A中的T处的放大示意图。
图4A为根据本申请实施例一种示例的电化学装置的阴极极片的沿厚度方向的截面示意图。
图4B为根据本申请实施例另一种示例的电化学装置的阴极极片的沿厚度方向的截面示意图。
图4C为根据本申请实施例再一种示例的电化学装置的阴极极片的沿厚度方向的截面示意图。
图5为根据本申请实施例的一种示例的超声波滚焊的焊接方式的示意图。
图6为根据本申请实施例的一种示例的第一焊印的示意图。
图7为根据本申请实施例的另一种示例的第一焊印的示意图。
图8为根据本申请实施例的再一种示例的第一焊印的示意图。
图9为根据本申请实施例的再一种示例的第一焊印的示意图。
图10为根据本申请实施例的一种示例的用电设备的示意图。
具体实施方式
为了使本领域的人员更好地理解本申请实施例中的技术方案，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、详细地描述，显然，所描述的实施例仅是本申请实施例一部分实施例，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所获得的所有其他实施例，都应当属于本申请实施例保护的范围。
在下面的描述中，先对本申请实施例中的电化学装置及用电设备进行具体说明，然后给出本申请实施例中的的一些相关的实验例和对比例，用于说明本申请实施例中提供的电化学装置及用电设备相对于现有技术的显著优势。
下面结合附图说明本申请实施例的电化学装置及用电设备的具体实现。需要说明的是，下面各个附图中为便于进行示意，各结构其未必是按照实际比例绘制的。
需要说明的是，本申请实施例的内容中，以锂离子电池作为电化学装置10的例子来解释本申请，但是本申请的电化学装置10并不仅限于锂离子电池，例如还可以为钠离子电池等。
本申请的第一方面，提供一种电化学装置，包括：极片，极片包括集流体、活性材料层及极耳连接片，在极片展开状态下，集流体沿极片的宽度方向包括第一部分及第二部分，活性材料层设置在第一部分的表面，第二部分为未设置活性材料层的空箔区，极耳连接片与第二部分的表面重叠形成重叠区，极耳连接片焊接在第二部分的表面以与第二部分形成电连接，沿极片的长度方向，焊印面积与焊接区面积之比大于或等于20％，焊接区长度与重叠区长度之比大于或等于60％。
本申请的电化学装置的极片可以包括阴极极片和阳极极片。在本申请的任一可选实施例中，极片为阴极极片时，集流体为阴极集流体，活性材料层为阴极活性材料层，极耳连接片为阴极极耳连接片，与极耳连接片电连接的极耳为阴极极耳；极片为阳极极片时，集流体为阳极集流体，活性材料层为阳极活性材料层，极耳连接片为阳极极耳连接片，与极耳连接片电连接的极耳为阳极极耳。为便于说明本申请实施例中的电化学装置，本申请电化学装置主要以极片为阴极极片为例，不再赘述阳极极片。下面结合图1-图9进行说明。参照图1-图9所示，本申请实施例中公开了一种示例性的电化学装置10，其包括：阴极极片1、阳极极片2、隔离膜3、阴极极耳41、阳极极耳；隔离膜3设置于阴极极片1和阳极极片2之间；阴极极片1包括阴极集流体11、阴极活性材料层12、阴极极耳连接片51，阴极集流体11沿极片的宽度方向Y包括第一部分及第二部分，阴极活性材料层12设置在阴极集流体的第一部分的表面，阴极集流体的第二部分为未设置阴极活性材料层12的空箔区，阴极极耳连接片51与第二部分的表面重叠形成重叠区，阴极极耳连接片51焊接在阴极 集流体的第二部分表面上以与阴极集流体的第二部分形成电连接，焊印面积与焊接区面积之比大于或等于20％，沿极片的长度方向，焊接区长度与重叠区长度之比大于或等于60％。
本申请实施例中，由于该电化学装置的阴极极片的阴极极耳连接片焊接在阴极集流体的第二部分(即阴极集流体上的边缘空箔区)的表面，因此在本申请中将阴极极耳从阴极集流体上引出时，可以不再是直接在阴极集流体的第二部分上电连接阴极极耳，而可以通过与阴极集流体的第二部分相焊接的阴极极耳连接片与阴极极耳电连接，基于此，在制备本申请中的电化学装置的阴极极片时，在对阴极极片进行冷压时阴极极片不易打皱，能够有效地提高电化学装置的制备优率。
可选地，参照图1，电化学装置10可以由阴极极片1、隔离膜3、阳极极片2卷绕制成。应理解，这仅作为示意，而不应视为对本实施例的限制。具体地，在卷绕成电化学装置后，隔离膜3设置于阴极极片1和阳极极片2之间，可以隔离阴极极片1和阳极极片2，防止电化学装置内部阴阳极短路，并可使离子通过，并可保持阴极极片1、隔离膜3、阳极极片2之间的电解液的功能。
为便于表述，下文中将阴极集流体的第一部分简称为阴极集流体第一部分(图中标号为111)，将阴极集流体的第二部分简称为阴极集流体第二部分(图中标号为112)，本实施例的阴极极片1中，阴极集流体第一部分111和阴极集流体第二部分112可以是导电箔材。
在一些实施例中，极片为阴极极片1时，阴极集流体第一部分111包括相连接的第一子部分1111和第二子部分1112，第二子部分1112与阴极集流体第二部分112相连接，阴极活性材料层12设置于第一子部分上，第二子部分上设置有绝缘层13；沿极片的宽度方向Y，阴极集流体第二部分112包括靠近第一子部分1111的第一侧和远离第一子部分1111的第二侧，阴极极耳连接片51包括靠近第一子部分1111的第一侧和远离第一子部分1111的第二侧；其中，阴极极耳连接片51与第一子部分1111存在间距，且阴极集流体第二部分112的第二侧，位于阴极极耳连接片51的第一侧和阴极极耳连接片51的第二侧之间。
具体地，在相关技术中，在阴极极片制备过程中，其中一种防止阴极极片在冷压时打皱的方式是：先将设置好阴极活性材料层和绝缘层的阴极极片进行冷压，在进行冷压前先将阴极极片的阴极集流体的边缘空箔区进行拉伸，使得阴极集流体的边缘空箔区和绝缘层的变形程度趋于一致，从而防止后续对阴极极片进行冷压时阴极极片打皱。但是，这样虽能减缓冷压时阴极极片的打皱问题，但由于增加了阴极极片的冷压张力，导致冷压过程中的阴极极片容易出现断裂现象，也降低了电化学装置的制备优率。
而本申请实施例中，在将阴极极耳41从阴极集流体11的阴极集流体第二部分112(即阴极集流体11的边缘空箔区)上引出时，可以不再是直接在阴极集流体第二部分112上电连接阴极极耳41，而可以通过与阴极集流体第二部分112相焊接的阴极极耳连接片51与阴极极耳41电连接，这样就使得在制备电化学装置10的阴极极片1时，在对阴极极片1进行冷压前可以不必对该阴极极片1的阴极集流体第二部分112(即阴极集流体11的边缘空箔区)进行拉伸，也同样能够改善后续对阴极极片1进行冷压时阴极极片1打皱的问题，并且由于可以不必对阴极极片1的阴极集流体第二部分112(即阴极集流体11的边缘空箔区)进行拉伸，也减小了阴极极片1的冷压张力，从而改善了冷压过程中的阴极极片1容易出现断裂的问题，因此能够提高电化学装置的制备优率。
绝缘层13能够对第二子部分1112和阳极极片2进行绝缘和隔离，可以有效防止阴极极片1和阳极极片2之间发生短路。
由于阴极集流体第一部分111可以为导电箔材，因此第一子部分1111和第二子部分1112均可以为导电箔材。阴极集流体11中，第一子部分1111和阴极集流体第二部分112分别连接于第二子部分1112沿极片的宽度方向上的两侧。
参照图4A、图4B、图4C，示出了图3A中的阴极极片1的沿厚度方向的截面示意图的示意。
图4A、图4B、图4C中也示意性地示出了与阴极极耳连接片51形成电连接的阴极极耳41的位置。图4A、图4B、图4C仅用于便于示意性地说明本实施例，而并不作为对本实施例的限制。
阴极极耳连接片51与第一子部分1111存在间距，可以避免制成的电化学装置10厚度过厚。并且由于离子可以穿过隔离膜3和阴极活性材料层12、阳极活性材料层22，但不能穿过阴极极耳连接片51(下文中会介绍，阴极极耳连接片51可以是导电箔材等，导电箔材例如镀铝箔材等)，因此阴极极耳连接片51与阴极集流体第一部分111存在间距可以防止阴极极耳连接片51夹在阴极极片1的阴极活性材料层12(包括阴极活性材料)和阳极极片2的阳极活性材料层22(包括阳极 活性材料)之间，阻碍阴阳极离子传输。
阴极集流体第二部分112的第二侧位于阴极极耳连接片51的第一侧与阴极极耳连接片51的第二侧之间，相当于阴极极耳连接片51可作为阴极集流体第二部分112的延长部分。
本实施例中的电化学装置10的阴极极耳41和阳极极耳42可以位于电化学装置10的同一侧，也可以是位于电化学装置10的不同侧。
本实施例中，阴极极片1的第一子部分1111上设置的阴极活性材料层12包括阴极活性材料，在此不限制阴极活性材料的种类，例如可以是钴酸锂、锰酸锂、磷酸铁锂等。在一些实施例中，阴极活性材料层12可以是涂层，也即阴极活性材料层12涂覆于第一子部分1111上。这样可以保证阴极活性材料层12设置在第一子部分1111上的结构稳定性。
下面再结合相关技术中电化学装置的阴极极片的制备，对本申请实施例中的电化学装置10进行简单说明，应理解，其仅用于便于理解，而不作为对本实施例中的任何限制。
参照图2，示出了相关技术中的一个电化学装置的阴极极片1’的制备过程，在这一示例中，阴极极片的阴极活性材料层和绝缘层为涂布于阴极集流体上的涂层。参照图2中的结构A1，该结构A1实际上也即未进行进一步加工的多个阴极极片(简单来说，将结构A1沿虚线a1切开，之后再分别沿虚线a2、a3切开，从而将结构A1分开为4个阴极极片1’，下面会具体说明这个过程)。在将阴极活性材料层12’和绝缘层13’涂布到阴极集流体11’上后获得该结构A1，对结构A1进行冷压(例如可以采用与该结构A1相适配的台阶辊(即一种特殊的冷压辊)进行冷压。使用台阶辊时，对于每一种不同尺寸的结构A1都要设计不同的台阶辊的尺寸与之适配。具体细节参照利用台阶辊对极片进行冷压的相关技术，在此不进行赘述)。在冷压过程中，由于阴极集流体11’的边缘空箔区14’的厚度与涂布区(即绝缘层13’和阴极活性材料层12’)的变形程度不同，所以易导致冷压过程中结构A1打皱，也即后续制备的阴极极片1’打皱。因此一般先对边缘空箔区14’进行拉伸，使其在冷压的过程中变形趋于一致，从而防止后续对结构A1进行冷压时阴极极片打皱。在拉伸以及冷压的步骤结束后，将冷压后的结构A1沿虚线a1切开(例如切割的方式可以采用激光切割技术)，得到两个结构A2(每个结构A2相当于两个的阴极极片1’)。再分别沿虚线a2、a3将两个结构A2切开(例如切割的方式可以采用激光切割技术)，得到如图2中所示的4个阴极极片1’。之后在用该最后得到的阴极极片1’制备电化学装置时，可将该阴极极片1’与隔离膜、阳极极片等进行卷绕，并将边缘空箔区14’与阴极极耳电连接(例如以焊接形式形成电连接)。最终成功制备电化学装置。
对应地，再结合本申请实施例中电化学装置10的阴极极片1的制备，对本申请实施例中的电化学装置10进行简单说明，应理解，其仅用于便于理解，而不作为对本实施例中的任何限制。
参照图3A，示出了本实施例中的一个电化学装置10的阴极极片1的制备过程，另外，图3B示出了图3A中的T处的放大示意图。在图3A示出的这一示例中，阴极极片1的阴极活性材料层12和绝缘层13为分别涂布于阴极集流体11的第一子部分1111和第二子部分1112上的涂层。参照图3A中的结构B1，该结构B1实际上也即未进行进一步加工的多个阴极极片1(简单来说，将结构A1沿虚线b1切开，之后再分别沿虚线b2、b3切开，从而将结构B1分开为4个阴极极片1，下面会具体说明这个过程)。在将阴极活性材料层12和绝缘层13涂布到阴极集流体11上后获得该结构B1，对结构B1进行冷压(此处冷压的实现方式，可参照利用冷压辊对极片进行冷压的相关技术进行理解，在此不进行赘述)。对比图3A和图2中的结构B1以及结构A1可以看出，由于在冷压前不用对结构B1的边缘空箔区(该边缘空箔区也即阴极集流体第二部分112)进行拉伸，图3A中结构B1相较于图2中结构A1，结构B1中的阴极集流体11的边缘空箔区的宽度显著变小。在冷压的步骤结束后，将冷压后的结构B1沿虚线b1切开(例如切割的方式可以采用激光切割技术)，得到两个结构B2，在结构B2两侧的边缘空箔区(即阴极集流体第二部分112)上分别焊接阴极极耳连接片51，在焊接完成后得到两个结构B3(每个结构B3相当于两个阴极极片1)。再分别沿虚线b2、b3将两个结构B3切开(例如切割的方式可以采用激光切割技术)，得到如图3A中所示的4个阴极极片1(另外可参照图3B对结构进行进一步理解)。之后在用该最后得到的阴极极片1制备电化学装置10时，可将该阴极极片1与隔离膜3、阳极极片2等进行卷绕，并将阴极极耳连接片51与阴极极耳41电连接(例如以焊接形式形成电连接)。最终成功制备电化学装置10。
应理解，图3A中为更便于示意地显示结构将阴极极耳连接片51与阴极集流体第二部分112 相焊接形成的第一焊印61省略，而在图3B的放大示意图中则示意性地示出了第一焊印61，图3A和图3B并不作为对本申请的任何限制。
在一些可选的实施例中，阴极集流体第二部分112为导电箔材，且导电箔材(即阴极集流体第二部分112)的每平方毫米电阻R满足：R<20mΩ，这样使得阴极集流体第二部分112的导电性能良好，满足电化学装置10的使用需要。
如前述，阴极集流体第一部分111的第一子部分1111和/或第二子部分1112也可以为导电箔材，例如，第一子部分1111和/或第二子部分1112的导电箔材的每平方毫米电阻小于20mΩ，这样也使得第一子部分1111和/或第二子部分1112的导电性能良好，满足电化学装置10的使用需要。
本实施例中，阴极集流体第二部分112与阴极极耳连接片51相焊接，阴极极耳41电连接于阴极极耳连接片51。该阴极极耳连接片51也可以是导电箔材，可选地，该阴极极耳连接片51的每平方毫米电阻R满足：R<20mΩ，这样使得阴极极耳连接片51的导电性能良好，满足电化学装置10的使用需要。
可选地，在实际测量制备好的电化学装置10的阴极集流体第二部分112或阴极极耳连接片51的每平方毫米电阻R时，可以先将电化学装置10拆解，再取阴极集流体第二部分112或阴极极耳连接片51的洁净部分(即无绝缘材料或阴极活性材料的部分)利用电阻测试仪进行测量，若无法取到，则可以用酒精等有机溶剂将阴极集流体第二部分112或阴极极耳连接片51上附着的绝缘材料或者阴极活性材料洗去，再取洗去后的洁净部分利用电阻测试仪进行测量，或者也可以用其他方式进行测量，在此不进行限制。
极片为阴极极片1时，对于阴极集流体第二部分112和/或阴极极耳连接片51为导电箔材而言，本实施例中不具体限制导电箔材的具体材质，其在保证导电性能和结构强度的基础上，可以采用任意的材质，例如导电箔材包括：铝箔、镀铝箔材、镍箔、镀镍箔材中的至少之一。这样材质的导电箔材，可以保证阴极极片1的阴极集流体第二部分112和/或阴极极耳连接片51的导电性能，满足电化学装置10的使用需要。
可选地，对于导电箔材为镀铝箔材时，则镀铝箔材包括：聚丙烯类薄膜表面镀铝的箔材、聚对苯二甲酸二乙酯类薄膜表面镀铝的箔材中的至少之一。这些类型的导电箔材，可以保证阴极极片1的阴极集流体第二部分112和/或阴极极耳连接片51的导电性能，满足电化学装置10的使用需要。
可选地，本申请中的阴极集流体第二部分112和阴极极耳连接片5可以采用相同材质的导电箔材，也可以采用不同材质的导电箔材，在此不进行限制。
可选地，对于阴极极耳连接片51的厚度L满足：4μm≤L≤25μm。由于阴极极耳连接片51的厚度过薄时，会增加制造阴极极片1的工艺难度，并造成成本增加，并且由于厚度过薄，导致强度较低，也难以符合阴极极片1和阴极极耳连接片51的结构强度的要求；而阴极极耳连接片51的厚度过厚时，也会导致材料成本增加、电化学装置10的能量密度收益减少。本实施例中的厚度L满足上述的取值范围(即4μm≤L≤25μm)，既能够较好地避免阴极极耳连接片51厚度过薄的弊端，又能较好地避免阴极极耳连接片51厚度过厚的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。可选地，在4μm≤L≤25μm的基础上，阴极极耳连接片51的厚度L满足：5μm≤L≤20μm。在这一优选的取值范围内，更能较好地避免阴极极耳连接片51厚度过薄的弊端，更能较好地避免阴极极耳连接片51厚度过厚的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。在上述的取值范围内，L可以依据需要选择合适的值。例如以5μm≤L≤20μm进行举例，则L可以为5μm、7μm、10μm、15μm、18μm、20μm等等，在此不进行具体限制。
可选地，在实际测量制备好的电化学装置10的阴极极耳连接片51的厚度L时，可以先将电化学装置10拆解，再取阴极极耳连接片5位于第一焊印61和第二焊印62之间的未焊接部分(对于第一焊印61和第二焊印62，下文中会介绍)，利用千分尺或者万分尺进行测量，或者也可以用其他方式进行测量，在此不进行限制。
可选地，为了保证阴极极耳连接片51的强度，阴极极耳连接片51的断裂强度S满足：80MPa≤S≤800MPa。由于阴极极耳连接片51的断裂强度过小时，容易在制备过程中出现断裂，会增加制造阴极极片1的工艺难度，并造成成本增加，并且断裂强度过小也难以符合阴极极片1和阴极极耳连接片51的结构强度的要求；而阴极极耳连接片51的断裂强度S过大时，也会导致增加制造阴极 极片1的工艺难度，并造成成本增加。本实施例中的断裂强度S满足上述的取值范围(即80MPa≤S≤800MPa)，既能够较好地避免阴极极耳连接片51的断裂强度过小的弊端，又能较好地避免阴极极耳连接片51的断裂强度过大的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。可选地，在80MPa≤S≤800MPa的基础上，阴极极耳连接片51的断裂强度S满足：100MPa≤S≤450MPa。在这一优选的取值范围内，更能较好地避免阴极极耳连接片51的断裂强度过小的弊端，更能较好地避免阴极极耳连接片51的断裂强度过大的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。在上述的取值范围内，阴极极耳连接片51的断裂强度S可以依据需要选择合适的值。例如以100MPa≤S≤450MPa举例，则断裂强度S可以为100MPa、150MPa、200MPa、250MPa、300MPa、350MPa、400MPa、450MPa等等，在此不进行限制。
可选地，阴极极片1的阴极集流体11的阴极集流体第二部分112的厚度的取值范围可以与上述的阴极极耳连接片51的厚度的取值范围相同，即阴极集流体第二部分112的厚度的取值范围可以为4μm～25μm，进一步可选的为5μm～20μm，阴极集流体第二部分112的断裂强度的取值范围可以与上述的阴极极耳连接片51的断裂强度的取值范围相同，即阴极集流体第二部分112的断裂强度的取值范围可以为80MPa～800MPa，进一步可选的为100MPa～450MPa。
此外，阴极集流体第二部分112和阴极极耳连接片51均为导电箔材时，阴极集流体第二部分112的厚度和阴极极耳连接片51的厚度可以相同也可以不同，阴极集流体第二部分112的断裂强度和阴极极耳连接片51的断裂强度可以相同也可以不同。
可选地，阴极极片1的阴极集流体11的第一子部分1111和/或第二子部分1112为导电箔材时，可以与阴极集流体第二部分112采取同样材质，且与阴极集流体第二部分112的厚度满足同样取值范围。即，第一子部分1111和/或第二子部分1112为导电箔材时可以为铝箔、镀铝箔材、镍箔、镀镍箔材中的至少之一；且镀铝箔材包括聚丙烯类薄膜表面镀铝的箔材、聚对苯二甲酸二乙酯类薄膜表面镀铝的箔材中的至少之一；第一子部分1111和/或第二子部分1112的厚度的取值范围为4μm到25μm，优选为5μm到20μm；第一子部分1111和/或第二子部分1112的断裂强度的取值范围为80MPa到800MPa，优选为100MPa到450MPa，从而满足电化学装置10的相应的使用需要。
本实施例中，绝缘层13设置于阴极极片1的第二子部分1112。本实施例不对该绝缘层13的材质进行具体限制，例如可以是氧化铝、氧化硅中的至少之一。采用这样材质的绝缘层13对第二子部分1112和阳极极片2进行绝缘和隔离，可以有效防止阴极极片1和阳极极片2之间发生短路。
可选地，绝缘层13可以是涂层(例如氧化铝涂层、氧化硅涂层等)，也即绝缘层13涂覆于阴极极片1的第二子部分1112上。这样可以保证绝缘层13设置在第二子部分1112上的结构稳定性。
本实施例中，沿极片的宽度方向Y，绝缘层13的宽度d3满足：0.5mm≤d3≤5mm。
参照图4A、图4B、图4C，绝缘层13的宽度d3也即极片的宽度方向Y绝缘层13的第一侧和绝缘层13的第二侧之间的距离d3。本实施例采用这种宽度范围内的绝缘层13，可以有效将阴极集流体11的第二子部分1112与阳极极片2进行绝缘和隔离，防止两者之间短路，在满足电化学装置10的使用需求的基础上，不会额外增加成本。
可选地，对于该阴极极片1而言，绝缘层13的宽度d3与第二子部分1112的宽度(即沿极片的宽度方向Y第二子部分1112的第一侧和第二子部分1112的第二侧之间的距离)相等。可以理解的是，第二子部分1112的第一侧，是沿极片的宽度方向Y第二子部分1112的靠近第一子部分1111的一侧；第二子部分1112的第二侧，是沿极片的宽度方向Y第二子部分1112的远离第一子部分1111的一侧。
本申请实施例中，在一些可选的实施例中，极片的集流体的第二部分与极耳连接片之间的焊接拉力大于等于70N且小于等于1000N。
例如在一些可选的实施例中，极片为阴极极片1时，阴极集流体第二部分112和阴极极耳连接片51相焊接，阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力F满足：70N≤F≤1000N。由于阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力F过小时，容易在使用电化学装置10时导致阴极极耳连接片51从阴极集流体第二部分112上脱落；而阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力F过大时，影响在制备电化学装置10时的成本。本实施例中的焊接拉力F满足上述的取值范围(即70N≤F≤1000N)，既能够较好地避免阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力F过小的弊端，又能较好地避免阴极集流体第二 部分112与阴极极耳连接片51之间的焊接拉力F过大的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
可选地，在70N≤F≤1000N的基础上，阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力F满足：150N≤F≤500N。在这一优选的取值范围内，更能较好地避免阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力过小的弊端，更能较好地避免阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力过大的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。
在上述的取值范围内，焊接拉力F可以依据需要选择合适的值。例如以150N≤F≤500N进行举例，则焊接拉力F可以为150N、200N、300N、350N、400N、500N等等，在此不进行具体限制。
测试焊接拉力F的方式，可以参照相关技术，在此不进行限制。例如，一种示例性的测试焊接拉力F的方式可以是如下流程：取焊接后的阴极集流体第二部分112和阴极极耳连接片51的样品放入拉力机内，沿极片的宽度方向Y，左夹和右夹分别夹住阴极集流体第二部分112和阴极极耳连接片51，左夹和右夹相距合适距离(例如为20mm)，将焊接区(例如下文中提到的第一焊印61)设置于左夹和右夹正中间，测试过程中，保持左夹和右夹不接触焊接区(例如下文中提到的第一焊印61)，之后将左夹固定不动，将右夹沿远离左夹的方向以合适速度(例如为1mm/s)进行拉动，拉断后确认是否是焊接区断裂，如果是焊接区断裂，则确认此时对应的焊接拉力F，若不是焊接区断裂，则换样品重新测试。当然这仅作为示例，而非对实施例中的任何限制。
通过上述测试焊接拉力F的类似方式也可以测试阴极极耳连接片51的断裂强度，只需取阴极极耳连接片51的适当宽度(例如10mm)，将左夹和右夹分别夹住阴极极耳连接片51，之后将左夹固定不动，将右夹沿远离左夹的方向以合适速度(例如为1mm/s)进行拉动，之后可以测试得到阴极极耳连接片51的断裂强度。测试阴极集流体11的各部分的断裂强度的方式可以以此类推，在此不在赘述。当然这仅作为示例，而非对实施例中的任何限制。
本申请实施例中，阴极集流体第二部分112和阴极极耳连接片51之间的焊接，可以由任意的焊接方式进行，例如利用超声波滚焊的方式进行焊接等。参照图5所示，其示出了一种超声波滚焊的焊接方式，在这其中，首先将阴极集流体第二部分112与阴极极耳连接片51部分重叠，并置于滚焊焊座71上，再将滚焊焊头72对准滚焊焊座71上方的阴极极耳连接片51和阴极集流体第二部分112和进行超声波焊接。焊接过程中，滚焊焊头72对阴极极耳连接片51和阴极集流体第二部分112发出高频的超声波，在滚焊焊头72对两者进行加压的情况下，使得阴极极耳连接片51和阴极集流体第二部分112两者接触的表面相互摩擦产生热能，该热能使得阴极极耳连接片51和阴极集流体第二部分112的焊接位置发生熔化，从而使得阴极极耳连接片51与阴极集流体第二部分112最终形成焊接连接。当然，这仅为对本申请实施例中的一个示例，而并不作为对本申请的任何限制。
在一些可选的实施例中，焊印包括第一焊印61，以极片为阴极极片1为例，该电化学装置10中，第一焊印61为阴极集流体第二部分112与阴极极耳连接片51相焊接时形成；沿极片的宽度方向Y，第一焊印61包括靠近第一子部分1111的第一侧和远离第一子部分1111的第二侧；第一焊印61的第二侧位于阴极极耳连接片51上，且第一焊印61与第一子部分1111存在间距。
具体地，第一焊印61的第二侧位于阴极极耳连接片51上，保证阴极极耳连接片51能够与阴极集流体第二部分112形成稳定的焊接连接。而该第一焊印61的第一侧可以位于阴极集流体第二部分112上，也可以位于阴极极耳连接片51上，在此不进行限制。
本实施例中，不限制第一焊印61的形状。例如图6、图7所示，第一焊印61可以是多个第一子焊印611的组合且每相邻两个第一子焊印611之间存在间距。第一子焊印611可以由多个规则形状或者不规则形状的小焊点组合而成，例如小焊点的形状可以是圆形、矩形、或其他多边形等等。可选地，小焊点排列所形成的第一子焊印611的形状可以是平行四边形、矩形(可以是正方形)、三角形等多边形，或者也可以是其他不规则形状。例如图6所示，示出了第一子焊印611的形状为小焊点组成的矩形的形状，并且小焊点为矩形。或者例如图7所示，每个第一子焊印611可以都是一个完整的焊印。在此不进行限制。
又例如图8、图9所示，第一焊印61也可以是连续的焊印。该连续的焊印可以是一个完整的焊印(完整的焊印可以结合图9进行理解，在此不进行赘述)。或者该连续的焊印也可以是包括多个规则形状或者不规则形状的小焊点组合而成，例如小焊点的形状可以是圆形、矩形、或其他多边 形等等(可以结合图8进行理解，在此不进行赘述)。本实施例中在此不进行限制。
本申请中的电化学装置中，在极片展开状态下，极耳连接片焊接在极片的集流体的第二部分的表面而形成的焊印面积是指：极耳连接片焊接在极片的集流体的第二部分的表面时形成的所有焊印(即小焊点、完整焊印等)的面积之和；焊接区面积是指：极耳连接片焊接在极片的集流体的第二部分的表面时形成的所有焊印(即小焊点、完整焊印等)的最小外接区域的面积；极耳连接片与第二部分的表面重叠的区域为重叠区(即沿极片厚度方向上，极耳连接片的投影在第二部分表面上的面积)；焊接区长度是指：沿极片的长度方向，焊接区两端之间的最大距离；重叠区长度是指：沿极片的长度方向，重叠区两端的距离。本申请中，极片的焊印面积与焊接区面积之比大于或等于20％；焊接区长度与重叠区长度之比大于或等于60％。
因此对于极片为阴极极片1来说，焊印面积可以是指极耳连接片与极片的集流体的第二部分相焊接而形成的第一焊印61中包括的所有焊印(即小焊点、完整焊印等)的面积之和。焊接区面积可以是指第一焊印61中包括的所有焊印(即小焊点、完整焊印等)的最小外接矩形区域的面积。本申请中，极片的焊印面积与焊接区面积之比大于或等于20％，且焊接区长度与重叠区长度之比大于或等于60％。
以第一焊印61为例，则焊印面积为第一焊印61的面积。对于第一焊印61为多个第一子焊印611的组合且每相邻两个第一子焊印611之间存在间距的情形来说，焊印面积(在此记为Sy1)等于各第一子焊印611的面积之和。其中，对于图6中的每个第一子焊印611的面积而言，由于每个第一子焊印611均包括多个小焊点，因此图6中的第一子焊印611的面积为该第一子焊印611中的每个小焊点的面积之和；再以图7中第一子焊印611都是一个完整的焊印进行举例，焊印面积Sy1＝s11+s12+s13+s14+s15+s16+s17+s18，其中s11、s12、s13、s14、s15、s16、s17、s18为各个第一子焊印611的面积。而对于第一焊印61为连续的焊印的情形来说，参照图8所示，该连续的焊印包括多个小焊点组合而成，焊印面积等于所有小焊点的面积之和；参照图9所示，该连续的焊印为一个完整的焊印，焊印面积等于该完整焊印的面积。参照图6和图7所示，重叠区的长度此时等于极片的长度，焊接区的长度为h1，此时，焊接区的长度与重叠区的长度之比大于60％；参照图8和图9所示，重叠区的长度此时等于极片的长度，焊接区的长度为h1，也等于极片的长度，此时，焊接区的长度与重叠区的长度之等于60％；
参照图6、图7、图8、图9所示的示例中，将焊接区面积记为Sz1，则Sz1＝h1*d5，其中h1为最小外接矩形区域的长度(也即焊接区的长度)，d5是最小外接矩形区域的宽度。此外，下文中会介绍，d5是第一焊印61的宽度，也即沿极片的宽度方向Y第一焊印61的第一侧与第一焊印61的第二侧之间的距离。
将焊印面积与焊接区面积之比记为P，极片为阴极极片1时，以图7和图9中的情形分别举例：则图7中，P＝Sy1/Sz1＝(s11+s12+s13+s14+s15+s16+s17+s18)/(h1*d5)>20％；则图9中，P＝Sy1/Sz1＝(h1*d5)/(h1*d5)＝100％>20％。图6和图8中的情形也应满足P>20％。同时，焊接区的长度与重叠区的长度比不能太小，至少要大于或等于60％，这样能保证焊印在焊接区在重叠区分布均匀，避免焊印集中导致局部强度过大或者其他部分的强度过小，避免由此导致的加工困难的弊端。
本申请中，焊印面积与焊接区面积之比P>20％，且焊接区的长度与重叠区的长度比大于或等于60％能够满足电化学装置的极耳连接片在第二部分的表面形成稳定焊接的需要。
在一些可选实施例中，参照图4A、图4B、图4C所示，沿极片的宽度方向Y，第一焊印61的宽度d5满足：0.1mm≤d5≤10mm。可以理解的是，第一焊印61的宽度d5也即沿极片的宽度方向Y第一焊印61的第一侧与第一焊印61的第二侧之间的距离。对于第一焊印61的宽度d5，也可以结合图6、图7、图8和图9进行理解。
由于第一焊印61的宽度d5过小时(即d5<0.1mm)，难以保证阴极集流体第二部分112与阴极极耳连接片51之间的焊接拉力满足需求，从而造成前述焊接拉力F过小时的弊端；而第一焊印61的宽度d5过大时(即d5>10mm)，焊接难度大，且额外增加了成本。本实施例中的第一焊印61的宽度d5满足上述取值范围(0.1mm≤d5≤10mm)内，可以避免第一焊印61的宽度过小的弊端，也能避免第一焊印61的宽度过大的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
在上述的取值范围内，第一焊印61的宽度d5可以依据需要选择合适的值。例如以0.1mm≤d5 ≤10mm进行举例，则d5可以为0.1mm、1mm、3mm、5mm、8mm、10mm等等，在此不进行具体限制。
在一些可选的实施例中，参照图4A、图4B、图4C所示，若第一焊印61的第一侧位于阴极集流体第二部分112上，则第一焊印61的第一侧与阴极极耳连接片51的第一侧之间的间距d6满足：0mm≤d6≤5mm；或者，若第一焊印61的第一侧位于阴极极耳连接片51上，则第一焊印61的第一侧与阴极极耳连接片51的第一侧之间的间距d6满足：0mm≤d6≤20mm。
具体地，参照图4B所示，示出了第一焊印61的第一侧位于阴极集流体第二部分112上的示例(需要说明的是，图4B中第一焊印61的第一侧虽然未与阴极集流体第二部分112接触，两者之间呈间隔状，但图4B实际表达的样式是第一焊印61的第一侧与阴极集流体第二部分112直接接触以位于阴极集流体第二部分112上使得阴极极耳连接片5和阴极集流体第二部分112形成焊接，这里示出是为了便于示出结构，并不作为对本申请的限制)，第一焊印61的第一侧位于阴极集流体第二部分112上时，相当于第一焊印61的第一侧沿极片的宽度方向Y的反方向超出阴极极耳连接片51的第一侧，第一焊印61将阴极极耳连接片51的第一侧覆盖；参照图4A和图4C所示，示出了第一焊印61的第一侧位于阴极极耳连接片51上的示例，相当于第一焊印61的第一侧沿极片的宽度方向Y超出阴极极耳连接片51的第一侧，则阴极极耳连接片51的第一侧未被第一焊印61覆盖，阴极极耳连接片51的第一侧可以是处于无约束状态，即阴极极耳连接片51的第一侧未与阴极集流体第二部分112形成焊接。
由于在第一焊印61的第一侧沿极片的宽度方向Y的反方向超出阴极极耳连接片51的第一侧过多时(例如第一焊印61的第一侧位于阴极集流体第二部分112上时的d6>5mm)，不存在阴极活性材料的部分较多，因此不能提供能量的部分的空间占比也较大，使得能量密度损失严重，影响后续将阴极极耳41与阴极极耳连接片51进行电连接(例如阴极极耳41与阴极极耳连接片51以焊接的形式形成电连接)，在这过程中也容易对阴极极耳连接片51造成损伤，最终影响制成的电化学装置10的电性能；而在第一焊印61的第一侧沿极片的宽度方向Y超出阴极极耳连接片51的第一侧过多时(例如第一焊印的第一侧位于阴极极耳连接片51上时的d6>30mm时)，则存在无约束状态的阴极极耳连接片51过宽的情况，在制备阴极极片1时，增加了工艺难度，影响电化学装置10的制备优率。
本申请实施例中，通过采取这样的d6的取值范围，既能够避免在第一焊印61的第一侧沿极片的宽度方向Y的反方向超出阴极极耳连接片51的第一侧过多时产生的弊端，又能够避免在第一焊印61的第一侧沿极片的宽度方向Y超出阴极极耳连接片51的第一侧过多时产生的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
可选地，在前述取值范围的基础上，若第一焊印61的第一侧位于阴极集流体第二部分112上，则第一焊印61的第一侧与阴极极耳连接片51的第一侧之间的间距d6满足：0mm≤d6≤3mm；或者，若第一焊印61的第一侧位于阴极极耳连接片51上，则第一焊印61的第一侧与阴极极耳连接片51的第一侧之间的间距d6满足：0mm≤d6≤10mm。在这一优选的取值范围内，更能够在第一焊印61的第一侧沿极片的宽度方向的反方向超出阴极极耳连接片51的第一侧过多时产生的弊端，更能够避免在第一焊印61的第一侧沿极片的宽度方向超出阴极极耳连接片51的第一侧过多时产生的弊端，从而进一步满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。
在上述取值范围内，d6可以依据需要选择合适的值。例如以第一焊印61的第一侧位于阴极集流体第二部分112上时，0mm≤d6≤3mm，进行举例，则d6可以为0mm、0.5mm、1mm、1.5mm、2mm、2.5mm、3.0mm等，在此不进行限制。以第一焊印61的第一侧位于阴极极耳连接片51上时，0mm≤d6≤10mm，进行举例，则d6可以为0mm、1mm、3mm、5mm、7mm、8mm、10mm等，在此不进行限制。
在一些可选的实施例中，参照图4A、图4B、图4C所示，若第一焊印61的第二侧在阴极极耳连接片51上的第一投影，与阴极集流体第二部分112在阴极极耳连接片51上的第二投影存在重叠，则第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7满足：0mm≤d7≤15mm；或者，若第一焊印61的第二侧在阴极极耳连接片51上的第一投影，与阴极集流体第二部分112在阴极极耳连接片51上的第二投影不存在重叠，则第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7满足：0mm≤d7≤7mm。
容易理解的是，第一投影可以是第一焊印61的第二侧沿阴极极耳连接片51的厚度方向在阴极极耳连接片51上的投影，第二投影可以是阴极集流体第二部分112沿阴极极耳连接片51的厚度方 向在阴极极耳连接片51上的投影。
参照图4B和图4C所示，第一投影与第二投影存在重叠时，相当于阴极集流体第二部分112的第二侧沿极片的宽度方向超出第一焊印61的第二侧，阴极集流体第二部分112的第二侧处于无约束状态，即阴极集流体第二部分112的第二侧未与阴极极耳连接片51形成焊接；参照图4A所示，第一投影与第二投影不存在重叠时，相当于阴极集流体第二部分112的第二侧沿极片的宽度方向未超出第一焊印61的第二侧，阴极集流体第二部分112的第二侧与阴极极耳连接片51形成焊接。
由于在第一投影与第二投影存在重叠时，第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7过大(例如在第一投影与第二投影存在重叠时的d7>15mm)，也即阴极集流体第二部分112的第二侧沿极片的宽度方向超出第一焊印61的第二侧过多时，则存在无约束状态的阴极集流体第二部分112过宽的情况，在制备阴极极片1时，增加了工艺难度，影响电化学装置10的制备优率；而在第一投影与第二投影不存在重叠时，第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7过大(例如在第一投影与第二投影不存在重叠时的d7>7mm)，也即第一焊印61的第二侧沿极片的宽度方向超出阴极集流体第二部分112的第二侧过多时，则使得能量密度损失严重，影响后续在将阴极极耳41与阴极极耳连接片51进行电连接(例如阴极极耳41与阴极极耳连接片51以焊接的形式形成电连接)，在这过程中也容易对阴极极耳连接片51造成损伤，最终影响制成的电化学装置10的电性能。
本申请实施例中，通过采取这样的d7的取值范围，既能够避免在阴极集流体第二部分112的第二侧沿极片的宽度方向超出第一焊印61的第二侧过多时产生的弊端，又能够避免第一焊印61的第二侧沿极片的宽度方向超出阴极集流体第二部分112的第二侧过多时产生的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
可选地，在前述取值范围的基础上，若第一焊印61的第二侧在阴极极耳连接片51上的第一投影，与阴极集流体第二部分112在阴极极耳连接片51上的第二投影存在重叠，则第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7满足：0mm≤d7≤10mm；或者，若第一焊印61的第二侧在阴极极耳连接片51上的第一投影，与阴极集流体第二部分112在阴极极耳连接片51上的第二投影不存在重叠，则第一焊印61的第二侧与阴极集流体第二部分112的第二侧之间的间距d7满足：0mm≤d7≤3mm。在这一优选的取值范围内，更能够避免在阴极集流体第二部分112的第二侧沿极片的宽度方向超出第一焊印61的第二侧过多时产生的弊端，更能够避免第一焊印61的第二侧沿极片的宽度方向超出阴极集流体第二部分112的第二侧过多时产生的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
在上述的取值范围内，d7可以依据需要选择合适的值。例如以第一投影与第二投影存在重叠时，0mm≤d7≤10mm，进行举例，则d7可以为0mm、1mm、3mm、5mm、8mm、9mm、10mm等等，在此不进行具体限制。例如以第一投影与第二投影不存在重叠时，0mm≤d7≤3mm，进行举例，则d7可以为0mm、0.5mm、1mm、1.5mm、2mm、2.5mm、3mm等等，在此不进行具体限制。
在一些可选的实施例中，电化学装置还包括极耳，极耳通过焊接与极片的极耳连接片形成电连接。具体地，电化学装置还包括壳体，极耳部分伸出壳体。可选地，对于壳体而言，阴极极片1、隔离膜3、阳极极片2可以设置在壳体内，壳体可对其进行保护。可选地，对应于软包电芯来说，壳体可由金属塑膜制成，金属塑膜可以为钢塑膜、铝塑膜等等。在本申请的任一实施例中，电化学装置10的极片可以为阴极极片1和/或阳极极片2。当电化学装置的极片为阴极极片1时，与阴极极片1的阴极极耳连接片通过焊接形成电连接的极耳4为阴极极耳；而当电化学装置的极片为阳极极片2时，与阳极极片2的阳极极耳连接片通过焊接形成电连接的极耳4为阳极极耳。
以极片为阴极极片1为例，极耳为阴极极耳41，参照图4A、图4B、图4C所示，阴极极耳41通过焊接与阴极极耳连接片51形成电连接，并在阴极极耳连接片51上形成第二焊印62；沿极片的宽度方向Y，第二焊印62包括靠近第一子部分1111的第一侧和远离第一子部分1111的第二侧；其中，第一焊印61的第二侧与第二焊印62的第一侧之间的间距d8满足：0mm＜d8≤10mm。
本申请中不限制阴极极耳41与阴极极耳连接片51形成焊接时的具体焊接工艺，例如，焊接工艺可以是转接焊，则第二焊印62可以是转接焊焊印。
由于阴极极耳41通过焊接与阴极极耳连接片51形成电连接时，在阴极极耳连接片51上形成的第二焊印62与第一焊印61不能重叠，若重叠则会影响阴极极耳41与阴极极耳连接片51之间的 焊接效果，使得两者的焊接拉力降低；而若第一焊印61的第二侧与第二焊印62的第一侧之间的间距d8过大时(例如d8>10mm时)，则容易影响电化学装置10的能量密度。本实施例中通过采取这样的d8的取值范围，既能够避免第二焊印62与第一焊印61重叠时产生的弊端，又能够避免第一焊印61的第二侧与第二焊印62的第一侧之间的间距d8过大时产生的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
在上述的取值范围内，d8也可以依据需要选择合适的值。例如以0mm＜d8≤10mm举例，则d8可以为1mm、3mm、5mm、7mm、9mm、10mm等等，在此不进行具体限制。
本实施例中，本申请实施例中，不限制阴极极耳连接片51的宽度d1(参照图4A、图4B、图4C，即阴极极耳连接片51的宽度d1即沿极片的宽度方向Y阴极极耳连接片51的第一侧与阴极极耳连接片51的第二侧之间的距离)，满足电化学装置10的需要即可。在一些可选的实施例中，沿极片的宽度方向Y，阴极极耳连接片51的宽度d1满足：3mm≤d1≤25mm。
由于阴极极耳连接片51的宽度d1过小时，在制备电化学装置10时，将阴极极耳连接片51与阴极集流体第二部分112进行焊接时难度较大；而阴极极耳连接片51的宽度d1过大时，在制备阴极极片1的过程中，阴极极耳连接片51的边缘容易发生塌陷，还容易意外导致阴极极耳连接片51断裂。本实施例中的阴极极耳连接片51的宽度满足上述的取值范围(即3mm≤d1≤25mm)，既能够较好地避免阴极极耳连接片51的宽度过小的弊端，又能较好地避免阴极极耳连接片51的宽度过大的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
可选地，在3mm≤d1≤25mm的基础上，阴极极耳连接片51的宽度d1满足：5mm≤d1≤25mm。在这一优选的取值范围内，更能避免阴极极耳连接片51的宽度过小的弊端，更能较好地避免阴极极耳连接片51的宽度过大的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。
在上述取值范围内，阴极极耳连接片51的宽度d1可以依据需要选择合适的值。例如以5mm≤d1≤25mm举例，则d1可以为5mm、10mm、15mm、18mm、20mm、23mm、25mm等等，在此不进行限制。
本申请实施例中，不限制阴极集流体11的阴极集流体第二部分112的宽度d2(参照图4A、图4B、图4C，阴极集流体第二部分112的宽度d2即沿极片的宽度方向Y阴极集流体第二部分112的第一侧与阴极集流体第二部分112的第二侧之间的距离)，满足电化学装置10的需要即可。在一些可选的实施例中，沿极片的宽度方向Y，阴极集流体第二部分112的宽度d2满足：1mm≤d2≤20mm。
由于阴极集流体第二部分112的宽度过小时，在制备电化学装置10时，难以保证焊接宽度，导致将阴极极耳连接片51与阴极集流体第二部分112进行焊接时难度较大；而阴极集流体第二部分112的宽度过大时，在制备阴极极片1的过程中，在冷压后阴极集流体第二部分112更容易打皱，容易增大能量密度损失，导致成本增加。本实施例中的阴极集流体第二部分112的宽度满足上述的取值范围(即1mm≤d2≤20mm)，既能够较好地避免阴极集流体第二部分112的宽度过小的弊端，又能较好地避免阴极集流体第二部分112的宽度过大的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
可选地，在1mm≤d2≤20mm的基础上，阴极集流体第二部分112的宽度d2满足：1mm≤d2≤10mm。在这一优选的取值范围内，更能避免阴极集流体第二部分112的宽度过小的弊端，更能较好地避免阴极集流体第二部分112的宽度过大的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。
在上述取值范围内，阴极集流体第二部分112的宽度d2可以依据需要选择合适的值。例如以1mm≤d2≤10mm举例，则d2可以为1mm、3mm、4mm、5mm、7mm、8mm、10mm等等，在此不进行限制。
在一些可选的实施例中，参照图4A、图4B、图4C所示，沿极片的宽度方向Y，绝缘层13包括靠近第一子部分1111的第一侧和远离第一子部分1111的第二侧；若阴极极耳连接片51的第一侧位于绝缘层13上，则阴极极耳连接片51的第一侧与绝缘层13的第二侧之间的间距d4满足：0mm≤d4≤8mm；或者，若阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，则阴极极耳连接片51的第一侧与绝缘层13的第二侧之间的间距d4满足：0mm≤d4≤10mm。
具体地，参照图4C，阴极极耳连接片51的第一侧位于绝缘层13上时，相当于阴极极耳连接片51焊接到阴极集流体第二部分112后，阴极极耳连接片51的第一端沿极片的宽度方向Y的反方向超出阴极集流体第二部分112的第一侧，当超出过多时(例如d4＞8mm)，易导致制成的电化学 装置10厚度过大；参照图4A和图4B所示，阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，阴极极耳连接片51的第一侧与绝缘层13的第二侧的间距d4过大时(例如d4＞10mm)，则无法有效地解决阴极集流体第二部分112与阴极极耳连接片51相焊接后发生翻折的问题。
本实施例中的d4满足上述的取值范围，既能够较好地避免阴极极耳连接片51的第一端沿极片的宽度方向Y的反方向超出阴极集流体第二部分112的第一侧过多时的弊端，又能较好地避免阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，d4过大时的弊端，从而满足电化学装置10的使用需要，进而提高电化学装置10的制备优率。
当阴极极耳连接片51的第一侧与绝缘层13以及阴极集流体第二部分112存在间距时，是其中较为优选的实施方式。可选地，当阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，阴极极耳连接片51的第一侧与绝缘层13的第二侧之间的间距d4满足：0mm≤d4≤5mm。在这一优选的取值范围内，更能避免阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，d4过大时的弊端，从而满足电化学装置10的使用需要，进一步提高电化学装置10的制备优率。
可以理解的是，上文中的内容仅作为对本申请实施例中的电化学装置10的一些可选的示例，而非对本申请实施例中的电化学装置10的任何限制。
本申请实施例中，极片包括阴极极片和阳极极片，由于该电化学装置的阴极极片的阴极极耳连接片焊接在阴极集流体的第二部分(即阴极集流体上的边缘空箔区)的表面，阳极极片的阳极极耳连接片焊接在阳极集流体的第二部分(即阳极集流体上的边缘空箔区)的表面，因此在本申请中将阴极极耳从阴极集流体上引出时，可以不再是直接在阴极集流体的第二部分上电连接阴极极耳，而可以通过与阴极集流体的第二部分相焊接的阴极极耳连接片与阴极极耳电连接，并且在本申请中将阳极极耳从阳极集流体上引出时，可以不再是直接在阳极集流体的第二部分上电连接阳极极耳，而可以通过与阳极集流体的第二部分相焊接的阳极极耳连接片与阳极极耳电连接，基于此，在制备本申请中的电化学装置的阴极极片时，在对阴极极片进行冷压时阴极极片不易打皱，且在制备本申请中的电化学装置的阳极极片时，在对阳极极片进行冷压时阳极极片不易打皱，因而通过这样的阴极极片和阳极极片制成电化学装置，能够有效地提高电化学装置的制备优率。
根据本申请实施例中的另一方面，参照图10的结构框图，本申请实施例提供了一种用电设备20，该用电设备20包括前面提供的任意一项的电化学装置10。
具体地，该电化学装置10可以用于对用电设备20中的各个用电器件进行供电。
由于本申请实施例中的用电设备20包括上述的电化学装置10，该电化学装置10的制备优率较高，因此该用电设备20的制备优率也较高。
下面再结合本申请实施例中的一些实际的电化学装置10的实施例、以及一些相关技术中的电化学装置的对比例进行说明，结合这些实施例以及对比例之间的对比，可以更容易看出本申请实施例中的电化学装置10相对于相关技术的有益效果。在这些对比例和实施例中，电化学装置都以锂离子电池为例。
对比例1的电化学装置为常规的卷绕结构，对比例2与实施例1不同的是，焊印面积与焊接区面积之比小于20％，焊接区长度与重叠区长度之比小于60％，由于焊接强度不满足要求，在电化学装置的制备过程中，焊接强度不稳定，极耳连接片与阴极第二部分表面局部分离，不便测量。
实施例1由表1中的实施例1的阴极极片和常规结构的阳极极片卷绕而成，且阴极极片中，焊印面积与焊接区面积之比大于或等于20％，所述焊接区长度与所述重叠区长度之比大于或等于60％，以满足焊接稳定性需求。实施例2-16均与实施例1同理。另外实施例1-16相比于对比例1，在制备阴极极片时进行冷压前取消了对阴极集流体的边缘空箔区的拉伸，而是在阴极集流体的边缘空箔区(即阴极集流体第二部分)上焊接阴极极耳连接片，并在冷压过程中取消台阶辊，其余各参数相同；并且实施例1-18相比于对比例1，在制备阴极极片时进行冷压前取消了对阴极集流体的边缘空箔区的拉伸，而是在阴极集流体的边缘空箔区(即阴极集流体第二部分)上焊接阴极极耳连接片，并在冷压过程中取消台阶辊，其余各参数相同，对比例2由于焊印面积与焊接区面积之比、焊接区长度与所述重叠区长度之比不满足要求，实验数据无法测量。
对比例1-2、实施例1-16的电化学装置的阴极极片的相关数据如下表1：
表1
Figure PCTCN2022122461-appb-000001
需要说明的是，上述表1中为了便于观看，其中d4那一列中，负数表示阴极极耳连接片51的第一侧位于绝缘层13上时的情况(以表1中d4为-2mm为例，即：阴极极耳连接片51的第一侧位于绝缘层13上，d4＝2mm)，而正数表示阴极极耳连接片51的第一侧位于阴极集流体第二部分112上时的情况(以表1中d4为2mm为例，即：阴极极耳连接片51的第一侧位于阴极集流体第二部分112上，d4＝2mm)；其中d6那一列中，负数表示第一焊印61的第一侧位于阴极集流体第二部分112上时的情况(以表1中d6为-3mm为例，即：第一焊印61的第一侧位于阴极集流体第二部分112上，d6＝3mm)，而正数表示第一焊印61的第一侧位于阴极极耳连接片51上时的情况(以表1中d6为20mm为例，即：第一焊印61的第一侧位于阴极极耳连接片51上，d6＝20mm)。另外，表1中的“\”表示“无”，“★”的数量表示打皱程度，“★”的数量越多表示打皱情况越严重。另外，对于实施例1-实施例18而言，极耳翻折比例可以是指阴极极耳连接片51和阴极集流体第二部分112发生翻折的比例(可以结合图3A、图3B以及图4A、图4B、图4C理解)，而对于对比例1-对比例2而言，极耳翻折比例可以是指边缘空箔区14’发生翻折的比例(可以结合图2理解)。
从上表1中示出的各组数据进行分析，可以看出本申请实施例中的电化学装置10(即实施例1-实施例18)相对于相关技术中的电化学装置来说，其显著改善了阴极极片1冷压后的打皱情况，也显著改善了极耳翻折的情况，因而通过这样的阴极极片1制成电化学装置10，能够有效地提高电化学装置10的制备优率。
本文使用的术语“包括”及其变形是开放性包括，即“包括但不限于”。术语“基于”是“至少部分地基于”。术语“一个实施例”表示“至少一个实施例”；术语“另一实施例”表示“至少一个另外的实施例”；术语“一些实施例”表示“至少一些实施例”。其他术语的相关定义将在下文描述中给出。需要注意，本申请中提及的“第一”、“第二”等概念仅用于对不同的装置、模块或单元进行区分，并非用于限定这些装置、模块或单元所执行的功能的顺序或者相互依存关系。
需要注意，本申请中提及的“一个”、“多个”的修饰是示意性而非限制性的，本领域技术人员应当理解，除非在上下文另有明确指出，否则应该理解为“一个或多个”。
本领域技术人员在考虑说明书及实践这里公开的发明后，将容易想到本申请的其它实施方案。本申请旨在涵盖本申请的任何变型、用途或者适应性变化，这些变型、用途或者适应性变化遵循本申请的一般性原理并包括本申请未公开的本技术领域中的公知常识或惯用技术手段。说明书和实施例仅被视为示例性的，本申请的真正范围和精神由所附的权利要求指出。

Claims (13)

  1. 一种电化学装置，包括：极片，所述极片包括集流体、活性材料层及极耳连接片，在极片展开状态下，所述集流体沿极片的宽度方向包括第一部分及第二部分，所述活性材料层设置在所述第一部分的表面，所述第二部分为未设置所述活性材料层的空箔区，所述极耳连接片与所述第二部分的表面重叠形成重叠区，所述极耳连接片焊接在所述第二部分的表面以与所述第二部分形成电连接，沿所述极片的长度方向，焊印面积与焊接区面积之比大于或等于20％，所述焊接区长度与所述重叠区长度之比大于或等于60％。
  2. 根据权利要求1所述的电化学装置，其中，所述极片为阴极极片，所述第一部分包括相连接的第一子部分和第二子部分，所述第二子部分与所述第二部分相连接，所述活性材料层设置于所述第一子部分上，所述第二子部分上设置有绝缘层；
    沿极片的宽度方向，所述第二部分包括靠近第一子部分的第一侧和远离第一子部分的第二侧，所述极耳连接片包括靠近第一子部分的第一侧和远离第一子部分的第二侧；
    其中，所述极耳连接片与所述第一子部分存在间距，且所述第二部分的第二侧，位于所述极耳连接片的第一侧和极耳连接片的第二侧之间。
  3. 根据权利要求2所述的电化学装置，其中，沿极片的宽度方向，所述极耳连接片的宽度d1满足：3mm≤d1≤25mm。
  4. 根据权利要求2所述的电化学装置，其中，沿极片的宽度方向，所述第二部分的宽度d2满足：1mm≤d2≤20mm。
  5. 根据权利要求2所述的电化学装置，其中，沿极片的宽度方向，所述绝缘层的宽度d3满足：0.5mm≤d3≤5mm。
  6. 根据权利要求2所述的电化学装置，其中，沿极片的宽度方向，所述绝缘层包括靠近第一子部分的第一侧和远离第一子部分的第二侧；
    若所述极耳连接片的第一侧位于所述绝缘层上，则所述极耳连接片的第一侧与所述绝缘层的第二侧之间的间距d4满足：0mm≤d4≤8mm；
    或者，
    若所述极耳连接片的第一侧位于所述第二部分上，则所述极耳连接片的第一侧与所述绝缘层的第二侧之间的间距d4满足：0mm≤d4≤10mm。
  7. 根据权利要求2所述的电化学装置，其中，所述焊印包括第一焊印，所述第一焊印为第二部分与所述极耳连接片相焊接时形成；
    沿极片的宽度方向，所述第一焊印包括靠近第一子部分的第一侧和远离第一子部分的第二侧；
    所述第一焊印的第二侧位于所述极耳连接片上，且所述第一焊印与所述第一子部分存在间距。
  8. 根据权利要求7所述的电化学装置，其中，沿所述极片的宽度方向，所述第一焊印的宽度d5满足：0.1mm≤d5≤10mm。
  9. 根据权利要求7所述的电化学装置，其中，若所述第一焊印的第一侧位于所述第二部分上，则所述第一焊印的第一侧与所述极耳连接片的第一侧之间的间距d6满足：0mm≤d6≤5mm；
    或者，
    若所述第一焊印的第一侧位于所述极耳连接片上，则所述第一焊印的第一侧与所述极耳连接片的第一侧之间的间距d6满足：0mm≤d6≤20mm。
  10. 根据权利要求7所述的电化学装置，其中，若所述第一焊印的第二侧在所述极耳连接片上的第一投影，与所述第二部分在所述极耳连接片上的第二投影存在重叠，则所述第一焊印的第二侧与所述第二部分的第二侧之间的间距d7满足：0mm≤d7≤15mm；
    或者，
    若所述第一焊印的第二侧在所述极耳连接片上的第一投影，与所述极片上的第二部分在所述极耳连接片上的第二投影不存在重叠，则所述第一焊印的第二侧与所述第二部分的第二侧之间的间距d7满足：0mm≤d7≤7mm。
  11. 根据权利要求7所述的电化学装置，其中，所述电化学装置还包括极耳，所述极耳通过焊接与所述极耳连接片形成电连接，并在所述极耳连接片上形成第二焊印；
    沿极片的宽度方向，所述第二焊印包括靠近第一子部分的第一侧和远离第一子部分的第二侧；
    其中，所述第一焊印的第二侧与所述第二焊印的第一侧之间的间距d8满足：0mm＜d8≤10mm。
  12. 根据权利要求1所述的电化学装置，其中，所述第二部分与所述极耳连接片之间的焊接拉力大于等于70N且小于等于1000N。
  13. 一种用电设备，包括：如权利要求1-12中任一项所述的电化学装置。
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