Electrochemical equipment and power consumers

Abstract

The present invention provides an electrochemical device and an electric power consuming device, comprising an electrode plate including a current collector, an active material layer, and a tab connection piece, wherein, when the electrode plate is unfolded, the current collector has a first portion and a second portion along the width direction of the electrode plate, the active material layer is disposed on a surface of the first portion, the tab connection piece overlaps with a surface of the second portion to form an overlapping region, and the tab connection piece is welded to the surface of the second portion to be electrically connected to the second portion, and along the length direction of the electrode plate, the ratio of the area of ​​the weld mark to the area of ​​the welded region is 20% or more, and the ratio of the length of the welded region to the length of the overlapping region is 60% or more.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present application relates to the field of electrochemical technology, and more particularly to electrochemical devices and power consumers. [Background technology]

[0002] With the continuous development of science and technology, electrochemical devices (including but not limited to lithium-ion batteries, sodium-ion batteries, etc.) are widely used, providing convenience for people when using devices such as tablet computers, mobile phones, electric vehicles, and energy storage devices.

[0003] One type of electrochemical device in the related art is composed of a cathode plate, an anode plate, and a separator disposed between them, and in the manufacturing process, it is necessary to electrically connect tabs to the free edge areas of the current collectors of the cathode plate and the anode plate. How to improve the yield rate of such electrochemical devices is a technical issue that needs to be resolved. Summary of the Invention

[0004] In view of this, embodiments of the present application provide an electrochemical device and a power consuming device to at least partially solve the above problems.

[0005] According to a first aspect of the present invention, there is provided an electrochemical device comprising a plate including a current collector, an active material layer, and a tab connection piece, wherein, when the plate is unfolded, the current collector has a first portion and a second portion along the width direction of the plate, the active material layer is provided on a surface of the first portion, the second portion is a non-coated area where the active material layer is not provided, the tab connection piece overlaps with the surface of the second portion to form an overlapping area, and the tab connection piece is welded to the surface of the second portion to be electrically connected to the second portion, and along the length direction of the plate, the ratio of the area of ​​the weld mark to the area of ​​the welded area is 20% or more, and the ratio of the length of the welded area to the length of the overlapping area is 60% or more.

[0006] In the embodiment of the present application, the electrode plates include a cathode plate and an anode plate. In the electrochemical device, the cathode tab connection piece of the cathode plate is welded to the surface of the second portion of the cathode current collector (i.e., the uncoated edge region of the cathode current collector), and the anode tab connection piece of the anode plate is welded to the surface of the second portion of the anode current collector (i.e., the uncoated edge region of the anode current collector). Therefore, when the cathode tab is led out from the cathode current collector in the present application, the cathode tab can be electrically connected via the cathode tab connection piece welded to the second portion of the cathode current collector without directly electrically connecting the cathode tab to the second portion of the cathode current collector. Furthermore, when the anode tab is led out from the anode current collector in the present application, the anode tab can be electrically connected via the anode tab connection piece welded to the second portion of the anode current collector without directly electrically connecting the anode tab to the second portion of the anode current collector. Based on this, when the cathode plate of the electrochemical device of the present application is fabricated, if the cathode plate is cold-rolled, wrinkles are less likely to occur in the cathode plate, and when the anode plate of the electrochemical device of the present application is fabricated, if the anode plate is cold-rolled, wrinkles are less likely to occur in the anode plate. Therefore, by manufacturing an electrochemical device using such cathode plates and anode plates, the manufacturing yield of the electrochemical device can be effectively improved.

[0007] In addition, in the electrochemical device of the present application, the ratio of the area of ​​the weld marks to the area of ​​the welded region along the length of the electrode plate is 20% or more, thereby ensuring the formation of a stable welded connection between the second part and the tab connection piece. And, the ratio of the length of the welded region to the length of the overlapping region is 60% or more, ensuring the uniform distribution of the weld marks in the welded region and the overlapping region, preventing localized excessive strength or insufficient strength in other parts due to the concentration of weld marks, and thereby avoiding the resulting difficulties in processing.

[0008] Preferably, the electrode plate is a negative electrode plate, 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 provided in the first sub-part, and the insulating layer is provided in the second sub-part, and along the width direction of the electrode plate, the second part includes a first side close to the first sub-part and a second side remote from the first sub-part, and the tab connection piece includes a first side close to the first sub-part and a second side remote from the first sub-part, where there is a gap between the tab connection piece and the first sub-part, and the second side of the second part is located between the first side of the tab connection piece and the second side of the tab connection piece.

[0009] In related art, one method for preventing wrinkles from forming in a cathode plate during cold rolling in the cathode plate manufacturing process is as follows: First, a cathode plate provided with a cathode active material layer and an insulating layer is cold-rolled. Before cold rolling, the uncoated edge region of the cathode current collector of the cathode plate is stretched so that the deformation degree of the uncoated edge region of the cathode current collector and the deformation degree of the insulating layer are approximately the same. This prevents wrinkles from forming in the cathode plate when the cathode plate is subsequently cold-rolled. However, while this method can alleviate the problem of wrinkles forming in the cathode plate during cold rolling, the cold-rolling tension of the cathode plate is increased, making the cathode plate more susceptible to fracture during the cold-rolling process and reducing the yield rate of electrochemical devices. In contrast, in the examples of the present application, when the cathode tab is pulled out from the second portion of the cathode current collector (i.e., the uncoated edge area of ​​the cathode current collector), the cathode tab is not directly electrically connected to the second portion of the cathode current collector, but is instead electrically connected via a cathode tab connection piece welded to the second portion of the cathode current collector. This eliminates the need to stretch the second portion of the cathode current collector (i.e., the uncoated edge area of ​​the cathode current collector) of the cathode plate before cold-rolling the cathode plate when producing a cathode plate for an electrochemical device, thereby alleviating the problem of wrinkles occurring in the cathode plate when cold-rolling the cathode plate. Furthermore, because it is not necessary to stretch the second portion of the cathode current collector (i.e., the uncoated edge area of ​​the cathode current collector), the cold-rolling tension of the cathode plate is reduced, thereby alleviating the problem of cathode plate breakage during the cold-rolling process and improving the yield rate of electrochemical devices. In addition, the insulating layer in the present application can insulate and separate the second sub-part from the anode plate, and can effectively prevent short circuits between the cathode plate and the anode plate.

[0010] Preferably, the width d1 of the tab connecting piece along the width direction of the electrode plate satisfies 3 mm≦d1≦25 mm.

[0011] For example, if the electrode plate is a cathode plate, if the width d1 of the cathode tab connecting piece is too small, it will be more difficult to weld the cathode tab connecting piece to the second part of the cathode current collector during the manufacture of the electrochemical device. If the width d1 of the cathode tab connecting piece is too large, the edge of the cathode tab connecting piece will be more likely to crumble and the cathode tab connecting piece will be more likely to break suddenly during the manufacture of the cathode plate. By ensuring that the width of the cathode tab connecting piece in this embodiment satisfies the above numerical range (i.e., 3 mm≦d1≦25 mm), it is possible to effectively avoid the disadvantages of a cathode tab connecting piece that is too small and also to effectively avoid the disadvantages of a cathode tab connecting piece that is too large, thereby meeting the needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0012] Preferably, the width d2 of the second portion along the width direction of the electrode plate satisfies 1 mm≦d2≦20 mm.

[0013] For example, if the electrode plate is a cathode plate, if the width of the second part of the cathode current collector is too small, it will be difficult to ensure the required welding width during the manufacture of the electrochemical device, making it more difficult to weld the cathode tab connecting piece and the second part of the cathode current collector. Meanwhile, if the width of the second part of the cathode current collector is too large, wrinkles will be more likely to occur in the second part of the cathode current collector after cold rolling during the manufacture of the cathode plate, which will increase the loss of energy density and increase costs. By ensuring that the width of the second part of the cathode current collector in this embodiment falls within the above range, it is possible to effectively avoid the disadvantages of a cathode current collector second part that is too small and to effectively avoid the disadvantages of a cathode current collector second part that is too large, thereby meeting the needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0014] Preferably, the width d3 of the insulating layer along the width direction of the electrode plate satisfies 0.5 mm≦d3≦5 mm.

[0015] In this embodiment, the use of an insulating layer within this width range effectively insulates and isolates the second sub-portion of the cathode current collector from the anode plate 2, preventing short circuits between them, and meeting the needs of the electrochemical device without increasing costs.

[0016] Preferably, along the width direction of the electrode plate, the insulating layer includes a first side close to the first sub-portion and a second side away from the first sub-portion, and when the first side of the tab connecting piece is located in the insulating layer, the distance d4 between the first side of the tab connecting piece and the second side of the insulating layer satisfies 0 mm≦d4≦8 mm, or when the first side of the tab connecting piece is located in the second portion, the distance d4 between the first side of the tab connecting piece and the second side of the insulating layer satisfies 0 mm≦d4≦10 mm.

[0017] For example, if the electrode plate is a cathode plate, when the first side of the cathode tab connection piece is located on the insulating layer, after the cathode tab connection piece is welded to the cathode current collector second part, the first end of the cathode tab connection piece will extend beyond the first side of the cathode current collector second part in the direction opposite to the width direction of the electrode plate. If the extension is too large (e.g., d4 > 8 mm), the thickness of the manufactured electrochemical device 10 will be too thick. If the first side of the cathode tab connection piece is located on the cathode current collector second part and the gap between the first side of the cathode tab connection piece and the second side of the insulating layer is too large (e.g., d4 > 10 mm), the problem of the cathode current collector second part being folded back after being welded to the cathode tab connection piece cannot be effectively solved. In this embodiment, d4 satisfying this numerical range makes it possible to effectively avoid disadvantages caused by the first end of the cathode tab connecting piece excessively extending beyond the first side of the second part of the cathode current collector in the direction opposite to the width direction of the electrode plate, and also makes it possible to effectively avoid disadvantages caused by the first side of the cathode tab connecting piece being located in the second part of the cathode current collector and d4 being too large, thereby meeting the use needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0018] Preferably, the weld mark includes a first weld mark formed when the second portion and the tab connection piece are welded, and along the width direction of the electrode plate, the first weld mark includes a first side close to the first sub-portion and a second side away from the first sub-portion, the second side of the first weld mark is located on the tab connection piece, and there is a gap between the first weld mark and the first sub-portion.

[0019] For example, if the electrode plate is a cathode plate, the second side of the first weld mark in the present application is positioned on the cathode tab connection piece, thereby ensuring that a stable welded connection can be formed between the cathode tab connection piece and the cathode current collector second part.

[0020] Preferably, a width d5 ​​of the first weld mark along the width direction of the electrode plate satisfies 0.1 mm≦d5≦10 mm.

[0021] For example, if the electrode plate is a cathode plate, if the width d5 ​​of the first weld mark is too small (i.e., d5<0.1 mm), it is difficult to ensure that the welding tensile strength between the second part of the cathode current collector and the cathode tab connecting piece meets the requirements, resulting in disadvantages due to the welding tensile strength being too low between the second part of the cathode current collector and the cathode tab connecting piece. Furthermore, if the width d5 ​​of the first weld mark is too large (i.e., d5>10 mm), welding becomes difficult and costs increase. By ensuring that the width d5 ​​of the first weld mark in this embodiment falls within the above numerical range (0.1 mm≦d5≦10 mm), the disadvantages due to a first weld mark width being too small and the disadvantages due to a first weld mark width being too large can be avoided, thereby meeting the needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0022] Preferably, when the first side of the first weld mark is located in the second part, the distance d6 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦d6≦5 mm, or when the first side of the first weld mark is located in the tab connection piece, the distance d6 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦d6≦20 mm.

[0023] For example, if the first side of the first weld mark extends beyond the first side of the cathode tab connection piece along the width direction of the electrode plate (e.g., if the first side of the first weld mark is located on the second portion of the cathode current collector, d6 > 5 mm), many areas will be devoid of cathode active material, resulting in a large spatial occupancy rate of areas unable to supply energy, resulting in a significant loss of energy density. This will affect the subsequent electrical connection between the cathode tab and the cathode tab connection piece (e.g., when the cathode tab and the cathode tab connection piece are electrically connected by welding), potentially damaging the cathode tab connection piece during this process, which in turn will affect the electrical characteristics of the resulting electrochemical device. On the other hand, if the first side of the first weld mark extends beyond the first side of the cathode tab connection piece along the width direction of the electrode plate (e.g., if the first side of the first weld mark is located on the cathode tab connection piece, d6 > 30 mm), the unconstrained cathode tab connection piece may be too wide, increasing the difficulty of the cathode plate fabrication process and impacting the yield rate of electrochemical devices. In the present application, by setting d6 within this numerical range, it is possible to avoid disadvantages caused by the first side of the first weld mark excessively extending beyond the first side of the cathode tab connecting piece in the direction opposite to the width direction of the electrode plate, and also to avoid disadvantages caused by the first side of the first weld mark excessively extending beyond the first side of the cathode tab connecting piece in the width direction of the electrode plate, thereby meeting the usage needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0024] Preferably, when the first projection of the second side of the first weld mark onto the tab connection piece overlaps with the second projection of the second part onto the tab connection piece, the distance d7 between the second side of the first weld mark and the second side of the second part satisfies 0 mm≦d7≦15 mm, or when the first projection of the second side of the first weld mark onto the tab connection piece does not overlap with the second projection of the second part of the electrode plate onto the tab connection piece, the distance d7 between the second side of the first weld mark and the second side of the second part satisfies 0 mm≦d7≦7 mm.

[0025] Taking the case where the electrode plate is a cathode plate as an example, when the first projection overlaps with the second projection, if the distance 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, when the first projection overlaps with the second projection, d7>15 mm), that is, when the second side of the second part of the cathode current collector extends too far beyond the second side of the first weld mark along the width direction of the electrode plate, the second part of the cathode current collector in the non-regulated state may be too wide. When manufacturing the cathode plate, the process difficulty increases, which affects the manufacturing yield rate of the electrochemical device. On the other hand, when the first projection does not overlap with the second projection, if the distance 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, when the first projection does not overlap with the second projection, d7>7 mm), that is, when the second side of the first weld mark extends too far beyond the second side of the second part of the cathode current collector along the width direction of the electrode plate, the loss of energy density increases, which affects the subsequent electrical connection between the cathode tab and the cathode tab connection piece (for example, the cathode tab and the cathode tab connection piece are electrically connected by welding). In this process, the cathode tab connection piece is also likely to be damaged. As a result, it affects the electrical characteristics of the manufactured electrochemical device. In the present application, by setting d7 within such a numerical range, it is possible to avoid the disadvantages caused by the second side of the second part of the cathode current collector extending too far beyond the second side of the first weld mark along the width direction of the electrode plate, and at the same time, avoid the disadvantages caused by the second side of the first weld mark extending too far beyond the second side of the second part of the cathode current collector along the width direction of the electrode plate. Thereby, it meets the usage needs of the electrochemical device and further improves the manufacturing yield rate of the electrochemical device.

[0026] Preferably, the electrochemical device further includes a tab that is electrically connected to the tab connection piece by welding and forms a second weld mark on the tab connection piece. Along the width direction of the electrode plate, the second weld mark includes a first side close to the first sub-part and a second side away from the first sub-part. The distance d8 between the second side of the first weld mark and the first side of the second weld mark satisfies 0 mm < d8 ≤ 10 mm.

[0027] For example, if the electrode plate is a cathode plate, when the cathode tab is electrically connected to the cathode tab connection piece by welding, the second weld mark formed on the cathode tab connection piece cannot overlap the first weld mark. Such overlap would affect the welding effect between the cathode tab and the cathode tab connection piece and reduce the welding tensile strength between them. If the distance d8 between the second side of the first weld mark and the first side of the second weld mark is too large (e.g., d8 > 10 mm), the energy density of the electrochemical device is likely to be affected. In this embodiment, by setting d8 within this range, the disadvantages caused by the second weld mark overlapping the first weld mark and the disadvantages caused by the distance d8 between the second side of the first weld mark and the first side of the second weld mark being too large can be avoided, thereby meeting the needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0028] Preferably, the welding tensile force between the second portion and the tab connection piece is 70N or more and 1000N or less.

[0029] If the welding tensile force between the second part and the tab connection piece is too small, the tab connection piece will be more likely to come off the second part when the electrochemical device is in use. On the other hand, if the welding tensile force between the second part and the tab connection piece is too large, it will affect the manufacturing cost of the electrochemical device. By ensuring that the welding tensile force in this embodiment satisfies the above numerical range, it is possible to effectively avoid the disadvantages caused by a welding tensile force between the second part and the tab connection piece being too small, and also to effectively avoid the disadvantages caused by a welding tensile force between the second part and the tab connection piece being too large, thereby meeting the needs of electrochemical devices and further improving the manufacturing yield of electrochemical devices.

[0030] According to another aspect of the present invention, there is provided a power consuming device including the electrochemical device described above.

[0031] The power consuming device in the embodiment of the present application includes the electrochemical device provided by the first aspect above, and since the yield of the electrochemical device is high, the yield of the power consuming device is also high. [Brief explanation of the drawings]

[0032] In order to more clearly explain the technical solutions according to the embodiments of the present application, the drawings used in the present application will be briefly described below. The drawings described below are only a part of the technical solutions according to the embodiments of the present application, and it is obvious that those skilled in the art can obtain other drawings based on these drawings.

[0033] [Figure 1] FIG. 1 is a schematic diagram of an electrochemical device according to an example of the present invention. [Figure 2] FIG. 2 is a diagram showing a process for producing a cathode plate in an electrochemical device according to an example of related art. [Figure 3A] FIG. 3A is a diagram showing a process for producing a cathode plate in an electrochemical device according to an example of the present invention. [Figure 3B] FIG. 3B is an enlarged schematic view of a portion T in FIG. 3A. [Figure 4A] FIG. 4A is a schematic cross-sectional view taken along the thickness direction of a cathode plate in an electrochemical device according to an example of the present application. [Figure 4B] FIG. 4B is a schematic cross-sectional view taken along the thickness direction of the cathode plate in an electrochemical device according to another example of the present invention. [Figure 4C] FIG. 4C is a schematic cross-sectional view taken along the thickness direction of the cathode plate in an electrochemical device according to yet another example of the present invention. [Figure 5] FIG. 5 is a schematic diagram of a welding method for ultrasonic seam welding according to an example of the present invention. [Figure 6] FIG. 6 is a schematic diagram of a first welding mark according to an example of an embodiment of the present application. [Figure 7] FIG. 7 is a schematic diagram of a first welding mark according to another example of the embodiment of the present application. [Figure 8] FIG. 8 is a schematic diagram of a first welding mark according to still another example of an embodiment of the present application. [Figure 9] FIG. 9 is a schematic diagram of a first welding mark according to still another example of an embodiment of the present application. [Figure 10]FIG. 10 is a schematic diagram of a power consumption device according to an example embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0034] In the following, in order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present application, the technical solutions of the embodiments of the present application will be described clearly and in detail with reference to the drawings of the embodiments of the present application. It is clear that the described embodiments are only a part of the embodiments of the present application, not all of the embodiments of the present application. All other embodiments that those skilled in the art can obtain based on the embodiments of the present application are all included in the protection scope of the embodiments of the present application.

[0035] In the following description, we first provide a detailed description of the electrochemical devices and power consuming devices in the examples of the present application, and then provide some related experimental examples and comparative examples to demonstrate that the electrochemical devices and power consuming devices provided by the examples of the present application have significant advantages over the prior art.

[0036] Specific embodiments of the electrochemical device and the power consuming device according to the present invention will be described below with reference to the drawings. For convenience of illustration, the structures in the drawings are not necessarily drawn to actual scale.

[0037] In the contents of the examples of the present application, the present application is described using a lithium ion battery as an example of the electrochemical device 10, but the electrochemical device 10 in the present application is not limited to a lithium ion battery and may be, for example, a sodium ion battery.

[0038] In a first aspect of the present application, there is provided an electrochemical device comprising a plate including a current collector, an active material layer, and a tab connection piece, wherein, when the plate is unfolded, the current collector has a first portion and a second portion along the width direction of the plate, the active material layer is provided on the surface of the first portion, the second portion is a non-coated region where no active material layer is provided, the tab connection piece and the surface of the second portion overlap to form an overlapping region, the tab connection piece is welded to the surface of the second portion so as to be electrically connected to the second portion, and along the length direction of the plate, the ratio of the area of ​​the weld mark to the area of ​​the welded region is 20% or more, and the ratio of the length of the welded region to the length of the overlapping region is 60% or more.

[0039] The electrode plates in the electrochemical device of the present application may include a cathode plate and an anode plate. In any preferred embodiment of the present application, when the electrode plate is a cathode plate, the current collector is a cathode current collector, the active material layer is a cathode active material layer, the tab connection piece is a cathode tab connection piece 51, and the tab electrically connected to the tab connection piece is a cathode tab. When the electrode plate is a cathode plate, the current collector is an anode current collector, the active material layer is a cathode active material layer, the tab connection piece is an anode tab connection piece, and the tab electrically connected to the tab connection piece is an anode tab. To facilitate explanation of the electrochemical device in the embodiments of the present application, the electrochemical device of the present application will mainly be described as an example in which the electrode plate is a cathode plate, and explanation of the anode plate will be omitted. Hereinafter, the description will be made with reference to FIGS. 1 to 9. Referring to FIGS. 1 to 9, the embodiments of the present application exemplarily disclose an electrochemical device 10. The electrochemical device 10 includes a cathode plate 1, an anode plate 2, a separator 3, a cathode tab 41, and an anode tab, with the separator 3 disposed between the cathode plate 1 and the anode plate 2. The cathode plate 1 includes a cathode current collector 11, a cathode active material layer 12, and a cathode tab connection piece 51. The cathode current collector 11 includes a first portion and a second portion along the width direction Y of the electrode plate. The cathode active material layer 12 is disposed on the surface of the first portion of the cathode current collector. The second portion of the cathode current collector is an uncoated region where the cathode active material layer 12 is not disposed. The cathode tab connection piece 51 and the surface of the second portion overlap to form an overlapping region, and the cathode tab connection piece 51 is welded to the surface of the second portion of the cathode current collector so as to be electrically connected to the second portion of the cathode current collector. The ratio of the area of ​​the weld mark to the area of ​​the welded region is 20% or more, and the ratio of the length of the welded region to the length of the overlap region along the length of the electrode plate is 60% or more.

[0040] In the examples of the present application, the cathode tab connection piece of the cathode plate in the electrochemical device is welded to the surface of the second portion of the cathode current collector (i.e., the uncoated edge area on the cathode current collector). Therefore, when the cathode tab is pulled out from the cathode current collector in the present application, the cathode tab can be electrically connected via the cathode tab connection piece welded to the second portion of the cathode current collector, rather than being directly electrically connected to the second portion of the cathode current collector. Based on this, when the cathode plate in the electrochemical device of the present application is fabricated, if the cathode plate is cold-rolled, wrinkles are less likely to occur in the cathode plate, and the yield of the electrochemical device can be effectively improved.

[0041] 1, an electrochemical device 10 can be preferably fabricated by winding a cathode plate 1, a separator 3, and an anode plate 2. This is merely an example and should not be construed as limiting the present embodiment. Specifically, after winding into the electrochemical device, a separator 3 is disposed between the cathode plate 1 and the anode plate 2 to isolate the cathode plate 1 and the anode plate 2, prevent short-circuiting between the cathode and anode in the electrochemical device, and allow ions to pass through, maintaining the function of the electrolyte between the cathode plate 1, the separator 3, and the anode plate 2.

[0042] For ease of explanation, the first portion of the cathode current collector will be abbreviated as cathode current collector first portion (denoted by reference numeral 111 in the drawings), and the second portion of the cathode current collector will be abbreviated as cathode current collector second portion (denoted by reference numeral 112 in the drawings). In the cathode plate 1 of this embodiment, the cathode current collector first portion 111 and the cathode current collector second portion 112 may be made of a conductive foil material.

[0043] In some embodiments, when the electrode plate is a cathode plate 1, 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 provided on the first sub-portion, and the insulating layer 13 is provided on the second sub-portion. Along the width direction Y of the electrode plate, 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 connection piece 51 includes a first side close to the first sub-portion 1111 and a second side away from the first sub-portion 1111. There is a gap between the cathode tab connecting piece 51 and the first sub-part 1111, and the second side of the cathode current collector second part 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.

[0044] Specifically, in the related art, one method for preventing the occurrence of wrinkles in a cathode plate during cold rolling in the cathode plate manufacturing process is as follows: First, a cathode plate provided with a cathode active material layer and an insulating layer is cold-rolled. Before cold rolling, the uncoated edge region of the cathode current collector of the cathode plate is stretched so that the degree of deformation of the uncoated edge region of the cathode current collector and the degree of deformation of the insulating layer are approximately the same. This prevents the occurrence of wrinkles in the cathode plate when the cathode plate is subsequently cold-rolled. However, while this method can alleviate the problem of wrinkles in the cathode plate during cold rolling, the cold-rolling tension of the cathode plate is increased, making the cathode plate more susceptible to fracture during the cold-rolling process and reducing the yield rate of electrochemical devices.

[0045] In contrast to this, in the examples of the present application, when the cathode tab 41 is pulled out from the cathode current collector second portion 112 of the cathode current collector 11 (i.e., the uncoated edge region of the cathode current collector 11), the cathode tab 41 is not directly electrically connected to the cathode current collector second portion 112, but is electrically connected via the cathode tab connection piece 51 welded to the cathode current collector second portion 112. This eliminates the need to pull the cathode current collector second portion 112 of the cathode plate 1 (i.e., the uncoated edge region of the cathode current collector 11) of the cathode plate 1 before cold-rolling the cathode plate 1 in the electrochemical device 10, thereby improving the problem of wrinkles occurring in the cathode plate 1 when the cathode plate 1 is subsequently cold-rolled. Furthermore, since there is no need to pull the cathode current collector second portion 112 of the cathode plate 1 (i.e., the uncoated edge region of the cathode current collector 11), the cold-rolling tension of the cathode plate 1 is also reduced, which alleviates the problem of the cathode plate 1 being prone to breakage during the cold-rolling process, thereby improving the yield of electrochemical devices.

[0046] The insulating layer 13 can insulate and separate the second sub-portion 1112 from the anode plate 2, and can effectively prevent a short circuit between the cathode plate 1 and the anode plate 2.

[0047] Since the cathode current collector first portion 111 may be a conductive foil material, the first sub-portion 1111 and the second sub-portion 1112 may both be conductive foil materials. In the cathode current collector 11, the first sub-portion 1111 and the cathode current collector second portion 112 are connected to either side of the second sub-portion 1112 in the width direction of the electrode plate.

[0048] 4A, 4B, and 4C, these drawings schematically show a cross section of the cathode plate 1 in FIG. 3A taken along the thickness direction.

[0049] 4A, 4B, and 4C also schematically show the position of the cathode tab 41 electrically connected to the cathode tab connection piece 51. FIGS. 4A, 4B, and 4C are provided to exemplarily explain the present embodiment and are not intended to limit the present embodiment.

[0050] The presence of a gap between the cathode tab connection piece 51 and the first sub-portion 1111 prevents the manufactured electrochemical device 10 from being too thick. Ions can pass through the separator 3, the cathode active material layer 12, and the anode active material layer 22, but cannot pass through the cathode tab connection piece 51 (which may be a conductive foil material such as an aluminum-plated foil material, as will be described later). Therefore, the presence of a gap between the cathode tab connection piece 51 and the cathode current collector first portion 111 prevents the cathode tab connection piece 51 from being sandwiched between the cathode active material layer 12 (containing a cathode active material) of the cathode plate 1 and the anode active material layer 22 (containing an anode active material) of the anode plate 2, thereby preventing the transmission of ions between the cathode and the anode from being hindered.

[0051] The second side of the cathode current collector second part 112 is located between the first side of the cathode tab connection piece 51 and the second side of the cathode tab connection piece 51, which means that the cathode tab connection piece 51 can be used as an extension of the cathode current collector second part 112.

[0052] 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 on different sides of the electrochemical device 10 .

[0053] In this embodiment, the cathode active material layer 12 provided on the first sub-portion 1111 of the cathode plate 1 includes a cathode active material such as lithium cobalt oxide, lithium manganese oxide, or lithium iron phosphate, but the type of the cathode active material is not limited thereto. In some embodiments, the cathode active material layer 12 may be a coating, i.e., the cathode active material layer 12 is coated on the first sub-portion 1111. In this manner, the stability of the structure in which the cathode active material layer 12 is provided on the first sub-portion 1111 can be ensured.

[0054] Below, we will briefly explain the electrochemical device 10 in the examples of the present application, combining it with the fabrication of a cathode plate of an electrochemical device in related art. However, it should be understood that this is for ease of understanding and does not limit the present example.

[0055] Referring to FIG. 2, FIG. 2 shows a process for fabricating a cathode plate 1′ of an electrochemical device in the related art. In this example, the cathode active material layer and insulating layer of the cathode plate are both coatings applied to a cathode current collector. Referring to structure A1 in FIG. 2, structure A1 is actually a plurality of cathode plates that have not yet undergone further processing. (Simply put, structure A1 is cut along dotted line a1, and then cut along dotted lines a2 and a3, respectively, to divide structure A1 into four cathode plates 1′. This process will be described in detail below.) After the cathode active material layer 12′ and the insulating layer 13′ are applied to the cathode current collector 11′, the structure A1 is obtained and cold-rolled. (For example, the structure A1 may be cold-rolled using a stepped roll (i.e., a special cold-rolling roll) that is compatible with the structure A1. When using a stepped roll, different sizes of stepped rolls must be designed to accommodate different sizes of structures A1. For details, see related art for cold-rolling electrode plates using stepped rolls, but the description thereof is omitted here.) During the cold-rolling process, the thickness of the uncoated edge region 14′ of the cathode current collector 11′ differs from the deformation degree of the coated region (i.e., the insulating layer 13′ and the cathode active material layer 12′). This makes the structure A1 prone to wrinkles during the cold-rolling process, which results in wrinkles in the cathode plate 1′ produced subsequently. Therefore, the uncoated edge regions 14' are typically stretched first during the cold rolling process to ensure that the deformation of the uncoated edge regions 14' is approximately uniform. This prevents wrinkles from forming in the cathode plate when the structure A1 is subsequently cold-rolled. After the stretching and cold-rolling processes are completed, the cold-rolled structure A1 is cut along dotted line a1 (e.g., using laser cutting) to obtain two structures A2 (each structure A2 corresponds to two cathode plates 1'). Next, the two structures A2 are cut along dotted lines a2 and a3 (e.g., using laser cutting) to obtain four cathode plates 1' as shown in FIG. 2. When the finally obtained cathode plates 1' are used to manufacture an electrochemical device, the cathode plates 1' are wound with separators and anode plates, and the uncoated edge regions 14' can be electrically connected to cathode tabs (e.g., by welding).Finally, the electrochemical device was fabricated.

[0056] In response to this, the electrochemical device 10 in the examples of the present application will be briefly described in combination with the fabrication of the cathode plate 1 of the electrochemical device 10 in the examples of the present application, but it should be understood that this is for ease of understanding and does not limit the present example.

[0057] 3A illustrates the manufacturing process of a cathode plate 1 of one electrochemical device 10 in this example, and FIG. 3B is an enlarged schematic view of portion T in FIG. 3A. In the example illustrated in FIG. 3A, the cathode active material layer 12 and insulating layer 13 of the cathode plate 1 are coatings applied to the first sub-portion 1111 and the second sub-portion 1112 of the cathode current collector 11, respectively. Referring to structure B1 in FIG. 3A, structure B1 is actually a plurality of cathode plates 1 that have not yet undergone further processing. (Simply put, structure B1 is divided into four cathode plates 1 by cutting along dotted line b1, and then cutting along dotted lines b2 and b3, respectively. This process is described in detail below.) After the cathode active material layer 12 and the insulating layer 13 are applied to the cathode current collector 11, a structure B1 is obtained, and the structure B1 is then cold-rolled (how cold rolling is realized can be understood with reference to related art for cold-rolling an electrode plate using a cold rolling roll, but the description thereof is omitted here). Comparing the structure B1 of FIG. 3A with the structure A1 of FIG. 2, it can be seen that the width of the uncoated edge region of the cathode current collector 11 in the structure B1 of FIG. 3A is significantly smaller than that of the structure A1 of FIG. 2 because there is no need to stretch the uncoated edge region of the structure B1 (the uncoated edge region is the cathode current collector second portion 112) before cold-rolling. After the cold-rolling process is completed, the cold-rolled structure B1 is cut along dotted line b1 (for example, laser cutting) to obtain two structures B2. Cathode tab connection pieces 51 are welded to the uncoated edge areas (i.e., the cathode current collector second portions 112) of the structure B2, respectively. After the welding is completed, two structures B3 are obtained (each structure B3 corresponds to two cathode plates 1). Next, the two structures B3 are cut along dotted lines b2 and b3 (for example, laser cutting) to obtain four cathode plates 1 as shown in FIG. 3A (the structure can be further understood with reference to FIG. 3B). The finally obtained cathode plates 1 are then wound with the separator 3 and the anode plate 2, etc., and the cathode tab connection pieces 51 can be electrically connected to the cathode tabs 41 (for example, by welding). Finally, the electrochemical device 10 is completed.

[0058] In FIG. 3A , to make it easier to illustrate the schematic structure, a first weld mark 61 formed by welding the cathode tab connection piece 51 and the cathode current collector second part 112 together is omitted. However, the enlarged schematic view in FIG. 3B schematically illustrates the first weld mark 61, and it should be understood that FIGS. 3A and 3B do not limit the present application.

[0059] In some preferred embodiments, the cathode current collector second portion 112 is a conductive foil material, and the resistance R per square millimeter of the conductive foil material (i.e., the cathode current collector second portion 112) satisfies R<20 mΩ, so that the conductivity of the cathode current collector second portion 112 is good and meets the usage needs of the electrochemical device 10.

[0060] As described above, the first sub-portion 1111 and / or the second sub-portion 1112 of the cathode current collector first portion 111 may be made of a conductive foil material. For example, the resistance per square millimeter of the conductive foil material of the first sub-portion 1111 and / or the second sub-portion 1112 is less than 20 mΩ. In this way, the first sub-portion 1111 and / or the second sub-portion 1112 have good electrical conductivity, which meets the needs of the electrochemical device 10.

[0061] In this embodiment, the cathode current collector second part 112 is welded to the cathode tab connection piece 51, and the cathode tab 41 is electrically connected to the cathode tab connection piece 51. The cathode tab connection piece 51 may be made of a conductive foil material. Preferably, the resistance R per square millimeter of the cathode tab connection piece 51 satisfies R<20 mΩ. In this way, the cathode tab connection piece 51 has good conductivity and meets the requirements of the electrochemical device 10.

[0062] Preferably, when actually measuring the resistance R per square millimeter of the cathode current collector second part 112 or the cathode tab connection piece 51 of the manufactured electrochemical device 10, the electrochemical device 10 is first disassembled, and then a clean portion (i.e., a portion not adhered with insulating material or cathode active material) of the cathode current collector second part 112 or the cathode tab connection piece 51 is taken and measured using a resistance meter. If this is not possible, the insulating material or cathode active material adhered to the cathode current collector second part 112 or the cathode tab connection piece 51 may be washed with an organic solvent such as alcohol, and then the cleaned portion may be taken and measured using a resistance meter, or other methods may be used for measurement, but the method is not limited thereto.

[0063] When the electrode plate is a cathode plate 1, the cathode current collector second part 112 and / or the cathode tab connecting piece 51 are made of a conductive foil material. The present embodiment does not limit the specific material of the conductive foil material, and any material can be used as long as it ensures the conductive properties and structural strength. For example, the conductive foil material includes at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil. Such conductive foil material can ensure the conductive properties of the cathode current collector second part 112 and / or the cathode tab connecting piece 51 of the cathode plate 1 and meet the usage needs of the electrochemical device 10.

[0064] Preferably, when the conductive foil is an aluminum-plated foil, the aluminum-plated foil includes at least one of a foil made of a polypropylene film with an aluminum-plated surface and a foil made of a polyethylene terephthalate film with an aluminum-plated surface. Such a conductive foil can ensure the conductive properties of the cathode current collector second part 112 of the cathode plate 1 and / or the cathode tab connection piece 51, and meet the requirements of the electrochemical device 10.

[0065] Preferably, the cathode current collector second part 112 and the cathode tab connection piece 51 in the present application may be made of the same conductive foil material or different conductive foil materials, but this is not limited thereto.

[0066] Preferably, the thickness L of the cathode tab connecting piece 51 satisfies the range 4 μm≦L≦25 μm. If the thickness of the cathode tab connecting piece 51 is too thin, the manufacturing process of the cathode plate 1 becomes more difficult, increasing costs. The thin thickness also reduces strength, making it difficult to meet the structural strength requirements of the cathode plate 1 and the cathode tab connecting piece 51. On the other hand, if the thickness of the cathode tab connecting piece 51 is too thick, it increases material costs and reduces the energy density of the electrochemical device 10. By ensuring that the thickness L in this embodiment satisfies the above range (i.e., 4 μm≦L≦25 μm), the disadvantages of an excessively thin cathode tab connecting piece 51 and an excessively thick cathode tab connecting piece 51 can be effectively avoided, while the disadvantages of an excessively thick cathode tab connecting piece 51 can be effectively avoided, thereby meeting the needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10. Preferably, the thickness L of the cathode tab connection piece 51 satisfies 5 μm≦L≦20 μm while satisfying 4 μm≦L≦25 μm. Keeping the thickness within this preferred range effectively avoids disadvantages caused by an excessively thin cathode tab connection piece 51 and also avoids disadvantages caused by an excessively thick cathode tab connection piece 51, thereby satisfying the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10. Within the above range, an appropriate value for L can be selected as needed. For example, assuming 5 μm≦L≦20 μm, L may be 5 μm, 7 μm, 10 μm, 15 μm, 18 μm, 20 μm, or the like, but is not particularly limited thereto.

[0067] Preferably, when actually measuring the thickness L of the cathode tab connection piece 51 of the manufactured electrochemical device 10, the electrochemical device 10 is first disassembled, and then the unwelded portion between the first weld mark 61 and the second weld mark 62 in the cathode tab connection piece 51 is removed (the first weld mark 61 and the second weld mark 62 will be described later), and measurement may be performed using a micrometer or another method, but this is not limited thereto.

[0068] Preferably, to ensure the strength of the cathode tab connecting piece 51, the breaking strength S of the cathode tab connecting piece 51 satisfies 80 MPa≦S≦800 MPa. If the breaking strength of the cathode tab connecting piece 51 is too low, it is prone to breakage during the manufacturing process, increasing the difficulty of the manufacturing process of the cathode plate 1 and increasing costs. Furthermore, because the breaking strength is too low, it is difficult to meet the structural strength requirements of the cathode plate 1 and the cathode tab connecting piece 51. On the other hand, if the breaking strength S of the cathode tab connecting piece 51 is too high, the difficulty of the manufacturing process of the cathode plate 1 also increases and increasing costs. In the present embodiment, the breaking strength S satisfies the above numerical range (i.e., 80 MPa≦S≦800 MPa), thereby favorably avoiding disadvantages caused by an excessively low breaking strength of the cathode tab connecting piece 51 and favorably avoiding disadvantages caused by an excessively high breaking strength of the cathode tab connecting piece 51, thereby meeting the use needs of the electrochemical device 10 and further improving the yield of the electrochemical device 10. Preferably, after satisfying 80 MPa≦S≦800 MPa, the breaking strength S of the cathode tab connecting piece 51 also satisfies 100 MPa≦S≦450 MPa. Being within this preferred numerical range favorably avoids disadvantages caused by an excessively low breaking strength of the cathode tab connecting piece 51 and favorably avoiding disadvantages caused by an excessively high breaking strength of the cathode tab connecting piece 51, thereby meeting the use needs of the electrochemical device 10 and further improving the yield of the electrochemical device 10. Within the above numerical range, an appropriate value can be selected as needed for the breaking strength S of the cathode tab connecting piece 51. For example, in the case where 100 MPa≦S≦450 MPa is taken as an example, the breaking strength S may be 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, etc., but is not limited thereto.

[0069] Preferably, the thickness of the cathode current collector second part 112 of the cathode current collector 11 of the cathode plate 1 may be in the same range as the thickness of the cathode tab connection piece 51, i.e., the thickness of the cathode current collector second part 112 may be in the same range as the breaking strength of the cathode tab connection piece 51, i.e., the breaking strength ...

[0070] Furthermore, when the cathode current collector second part 112 and the cathode tab connection piece 51 are both made of a conductive foil material, the thickness of the cathode current collector second part 112 and the thickness of the cathode tab connection piece 51 may be the same as or different from each other, and the breaking strength of the cathode current collector second part 112 and the breaking strength of the cathode tab connection piece 51 may be the same as or different from each other.

[0071] Preferably, when the first sub-portion 1111 and / or the second sub-portion 1112 of the cathode current collector 11 of the cathode plate 1 are made of a conductive foil material, they may 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. That is, when the first sub-portion 1111 and / or the second sub-portion 1112 are made of a conductive foil material, they may be at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil, and the aluminum-plated foil material includes at least one of foil material obtained by plating aluminum on a polypropylene film and foil material obtained by plating aluminum on a polyethylene terephthalate film. The thickness of the first sub-portion 1111 and / or the second sub-portion 1112 ranges from 4 μm to 25 μm, preferably from 5 μm to 20 μm. The breaking strength of the first sub-portion 1111 and / or the second sub-portion 1112 ranges from 80 MPa to 800 MPa, preferably from 100 MPa to 450 MPa, to meet the corresponding usage needs of the electrochemical device 10.

[0072] In this embodiment, the insulating layer 13 is provided on the second sub-portion 1112 of the cathode plate 1. In this embodiment, the material of the insulating layer 13 is not particularly limited, but may be, for example, at least one of alumina and silica. By using the insulating layer 13 made of such a material to insulate and separate the second sub-portion 1112 from the anode plate 2, it is possible to effectively prevent a short circuit between the cathode plate 1 and the anode plate 2.

[0073] Preferably, the insulating layer 13 may be a coating (e.g., an alumina coating, a silica coating, etc.), that is, the insulating layer 13 is applied to the second sub-portion 1112 of the cathode plate 1. In this way, the stability of the structure in which the insulating layer 13 is provided on the second sub-portion 1112 can be ensured.

[0074] In this embodiment, the width d3 of the insulating layer 13 along the width direction Y of the electrode plate satisfies 0.5 mm≦d3≦5 mm.

[0075] 4A, 4B, and 4C, 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 along the width direction Y of the electrode plate. In this embodiment, the use of the insulating layer 13 within this width range effectively insulates and isolates the second sub-portion 1112 of the cathode current collector 11 from the anode plate 2, preventing a short circuit between them, thereby meeting the needs of the electrochemical device 10 without increasing costs.

[0076] Preferably, in the cathode plate 1, 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 in the width direction Y of the electrode plate). The first side of the second sub-portion 1112 can be understood to be the side of the second sub-portion 1112 closer to the first sub-portion 1111 in the width direction Y of the electrode plate, and the second side of the second sub-portion 1112 can be understood to be the side of the second sub-portion 1112 away from the first sub-portion 1111 in the width direction Y of the electrode plate.

[0077] In some preferred embodiments of the present application, the welding tensile force between the second part of the current collector of the electrode plate and the tab connection piece is 70N or more and 1000N or less.

[0078] For example, in some preferred embodiments, when the electrode plate is a cathode plate 1, the cathode current collector second part 112 and the cathode tab connection piece 51 are welded together, and the welding tensile force F between the cathode current collector second part 112 and the cathode tab connection piece 51 satisfies 70 N≦F≦1000 N. If the welding tensile force F between the cathode current collector second part 112 and the cathode tab connection piece 51 is too small, the cathode tab connection piece 51 is likely to come off from the cathode current collector second part 112 when the electrochemical device 10 is in use. On the other hand, if the welding tensile force F between the cathode current collector second part 112 and the cathode tab connection piece 51 is too large, the manufacturing cost of the electrochemical device 10 will be affected. In the present embodiment, the welding tensile force F satisfies the above numerical range (i.e., 70 N≦F≦1000 N), thereby effectively avoiding disadvantages resulting from an excessively small welding tensile force F between the cathode current collector second part 112 and the cathode tab connecting piece 51 and also effectively avoiding disadvantages resulting from an excessively large welding tensile force F between the cathode current collector second part 112 and the cathode tab connecting piece 51, thereby satisfying the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0079] Preferably, 70 N≦F≦1000 N is satisfied, and the welding tensile force F between the cathode current collector second part 112 and the cathode tab connection piece 51 satisfies 150 N≦F≦500 N. Being within this preferred numerical range makes it possible to effectively avoid disadvantages resulting from an excessively small welding tensile force between the cathode current collector second part 112 and the cathode tab connection piece 51, and also effectively avoid disadvantages resulting from an excessively large welding tensile force between the cathode current collector second part 112 and the cathode tab connection piece 51, thereby satisfying the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0080] Within the above numerical range, an appropriate value can be selected as the welding tension F as needed. For example, in the case of 150 N≦F≦500 N, the welding tension F may be 150 N, 200 N, 300 N, 350 N, 400 N, 500 N, etc., but is not particularly limited thereto.

[0081] The test method for the welding tensile force F may refer to the related art, but is not limited thereto. For example, one exemplary test method for the welding tensile force F may be the following process: A sample of the welded cathode current collector second part 112 and cathode tab connection piece 51 is taken and placed in a tensile machine. The left and right clamps respectively clamp the cathode current collector second part 112 and the cathode tab connection piece 51 along the width direction Y of the electrode plate. The left and right clamps are spaced apart by an appropriate distance (e.g., 20 mm), and the weld area (e.g., the first weld mark 61 described below) is positioned in the middle between the left and right clamps. During the test, the left and right clamps are kept away from the weld area (e.g., the first weld mark 61 described below). Then, while the left clamp is fixed, the right clamp is pulled away from the left clamp at an appropriate speed (e.g., 1 mm / s) to fracture the weld area, and it is confirmed whether the weld area fractures. If the fractured area is the welded area, check the corresponding welding tension F at this time, and if the fractured area is not the welded area, replace the sample and retest. Of course, this is only an example and is not intended to limit the scope of the invention.

[0082] The breaking strength of the cathode tab connection piece 51 can also be tested using a method similar to the above-mentioned method for testing the welding tensile force F. The cathode tab connection piece 51 is cut to an appropriate width (e.g., 10 mm), and the cathode tab connection piece 51 is clamped between the left and right clamps. Then, while the left clamp is still fixed, the right clamp is pulled in a direction away from the left clamp at an appropriate speed (e.g., 1 mm / s) to test the cathode tab connection piece 51 and obtain its breaking strength. The method for testing the breaking strength of each part of the cathode current collector 11 can be performed in a similar manner, and therefore, a description thereof will be omitted here. Of course, this is merely an example and is not intended to limit the scope of the present invention.

[0083] In the present embodiment, the cathode current collector second portion 112 and the cathode tab connection piece 51 can be welded using any welding method, such as ultrasonic seam welding. Referring to FIG. 5 , this shows a welding method for ultrasonic seam welding. In this method, the cathode current collector second portion 112 and the cathode tab connection piece 51 are first placed on a seam welding anvil 71 with a partial overlap. Then, a seam welding horn 72 is placed over the cathode tab connection piece 51 and the cathode current collector second portion 112 on the seam welding anvil 71 to perform ultrasonic welding. During the welding process, the seam welding horn 72 emits high-frequency ultrasonic waves to the cathode tab connection piece 51 and the cathode current collector second portion 112. When the seam welding horn 72 applies pressure to the cathode tab connection piece 51 and the cathode current collector second portion 112, the contact surfaces of the cathode tab connection piece 51 and the cathode current collector second portion 112 rub against each other, generating heat energy. The thermal energy melts the welded portion between the cathode tab connection piece 51 and the cathode current collector second part 112, thereby finally forming a welded connection between the cathode tab connection piece 51 and the cathode current collector second part 112. Of course, this is merely an example in the embodiments of the present application and is not intended to limit the present application.

[0084] In some preferred embodiments, the welding mark includes a first welding mark 61. Taking the electrode plate as an example, in the electrochemical device 10, the first welding mark 61 is formed when the cathode current collector second part 112 and the cathode tab connection piece 51 are welded together. Along the width direction Y of the electrode plate, the first welding 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 welding mark 61 is located on the cathode tab connection piece 51, and there is a gap between the first welding mark 61 and the first sub-part 1111.

[0085] Specifically, positioning the second side of the first weld mark 61 on the cathode tab connection piece 51 ensures that a stable welded connection can be formed between the cathode tab connection piece 51 and the cathode current collector second part 112. The first side of the first weld mark 61 may be positioned on either the cathode current collector second part 112 or the cathode tab connection piece 51, but is not limited thereto.

[0086] In this embodiment, the shape of the first weld mark 61 is not limited. For example, as shown in FIGS. 6 and 7, the first weld mark 61 may be a combination of multiple first sub-weld marks 611, with a gap between two adjacent first sub-weld marks 611. The first sub-weld mark 611 may be a combination of multiple small welds of regular or irregular shapes, and the small weld marks may have a shape such as a circle, a rectangle, or another polygon. Preferably, the shape of the first sub-weld mark 611 formed by an array of small weld marks may be a polygon such as a parallelogram, a rectangle (or a square), a triangle, or another irregular shape. For example, as shown in FIG. 6, the shape of the first sub-weld mark 611 is a rectangle formed by small weld marks, and the small weld marks are rectangular. Alternatively, as shown in FIG. 7, each first sub-weld mark 611 may be a complete weld mark. This is not limited here.

[0087] 8 and 9, the first weld mark 61 may be a continuous weld mark. This continuous weld mark may be a complete weld mark (complete weld marks can be understood by referring to FIG. 9, but a description thereof will be omitted here). Alternatively, this continuous weld mark may be composed of a combination of multiple small weld points of regular or irregular shape, and the shape of the small weld points may be, for example, a circle, a rectangle, or another polygon (this can be understood by referring to FIG. 8, but a description thereof will be omitted here). This embodiment is not limited thereto.

[0088] In the electrochemical device of the present application, the area of ​​the weld mark formed when the tab connection piece is welded to the second surface of the current collector of the electrode plate in an unfolded state refers to the total area of ​​all weld marks (i.e., small weld spots, complete weld marks, etc.) formed when the tab connection piece is welded to the second surface of the current collector of the electrode plate. The area of ​​the weld region refers to the area of ​​the smallest circumscribed region of all weld marks (i.e., small weld spots, complete weld marks, etc.) formed when the tab connection piece is welded to the second surface of the current collector of the electrode plate. The area where the tab connection piece and the second surface overlap is the overlap region (i.e., the area of ​​the tab connection piece projected onto the second surface along the thickness direction of the electrode plate). The length of the weld region refers to the maximum distance between both ends of the weld region along the length of the electrode plate. The length of the overlap region refers to the distance between both ends of the overlap region along the length of the electrode plate. In the present application, the ratio of the area of ​​the weld mark to the area of ​​the weld region of the electrode plate is 20% or more, and the ratio of the length of the weld region to the length of the overlap region is 60% or more.

[0089] Therefore, when the electrode plate is a cathode plate 1, the area of ​​the weld mark may refer to the total area of ​​all weld marks (i.e., small weld spots, complete weld marks, etc.) included in the first weld mark 61 formed by welding the tab connection piece and the second part of the current collector of the electrode plate. The area of ​​the welded region may refer to the area of ​​the smallest circumscribed rectangular region of all weld marks (i.e., small weld spots, complete weld marks, etc.) included in the first weld mark 61. In the present application, the ratio of the area of ​​the weld mark on the electrode plate to the area of ​​the welded region is 20% or more, and the ratio of the length of the welded region to the length of the overlap region is 60% or more.

[0090] Taking the first weld 61 as an example, the area of ​​the weld is the area of ​​the first weld 61. If the first weld 61 is a combination of multiple first sub-welds 611, and there is a gap between two adjacent first sub-welds 611, the area of ​​the weld (denoted here as Sy1) is equal to the sum of the areas of the first sub-welds 611. Here, with regard to the area of ​​each first sub-weld 611 in FIG. 6, because each first sub-weld 611 includes multiple small welds, the area of ​​the first sub-weld 611 in FIG. 6 is the sum of the areas of the small welds within the first sub-weld 611. For example, if each of the first sub-weld marks 611 in FIG. 7 is a complete weld, the area of ​​the weld mark Sy1 is s11 + s12 + s13 + s14 + s15 + s16 + s17 + s18, where s11, s12, s13, s14, s15, s16, s17, and s18 are the areas of each of the first sub-weld marks 611. If the first weld mark 61 is a continuous weld, as shown in FIG. 8, this continuous weld mark is composed of multiple small welds, and the area of ​​the weld mark is equal to the sum of the areas of all the small welds. As shown in FIG. 9, this continuous weld mark is a complete weld, and the area of ​​the weld mark is equal to the area of ​​the complete weld. As shown in FIGS. 6 and 7, the length of the overlapping region is equal to the length of the electrode plate, and the length of the welded region is h1. In this case, the ratio of the length of the welded region to the length of the overlapping region is greater than 60%. As shown in Figures 8 and 9, the length of the overlapping area is equal to the length of the electrode plate, and the length of the welding area is equal to the length of the electrode plate, i.e., h1. In this case, the ratio of the length of the welding area to the length of the overlapping area is equal to 60%.

[0091] 6, 7, 8, and 9, if the area of ​​the welded region is denoted as Sz1, then Sz1 = h1 * d5, where h1 is the length of the minimum circumscribing rectangular region (i.e., the length of the welded region) and d5 is the width of the minimum circumscribing rectangular region. As will be described later, d5 is the width of the first weld mark 61, i.e., 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 plate.

[0092] Let P be the ratio of the area of ​​the weld mark to the area of ​​the welded region. For example, in the case of Figures 7 and 9, when the electrode plate is cathode plate 1, P = Sy1 / Sz1 = (s11 + s12 + s13 + s14 + s15 + s16 + s17 + s18) / (h1*d5) > 20% in Figure 7, and P = Sy1 / Sz1 = (h1*d5) / (h1*d5) = 100% > 20% in Figure 9. The ratio of the length of the welded region to the length of the overlap region should also be greater than 20%. At the same time, the ratio of the length of the welded region to the length of the overlap region should not be too small and should be at least 60% or greater. This ensures uniform distribution of the weld marks in the welded region and the overlap region, avoiding localized overstrength or understrength in other areas due to the concentration of weld marks, and avoiding the resulting disadvantage of processing difficulties.

[0093] In the present application, the ratio of the area of ​​the weld mark to the area of ​​the welded region is P>20%, and the ratio of the length of the welded region to the length of the overlapping region is 60% or more, so that the requirement that the tab connection piece of the electrochemical device forms a stable weld on the surface of the second part can be met.

[0094] 4A, 4B, and 4C, the width d5 ​​of the first weld mark 61 along the width direction Y of the electrode plate satisfies 0.1 mm≦d5≦10 mm. The width d5 ​​of the first weld mark 61 can be understood to be 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 plate. The width d5 ​​of the first weld mark 61 can also be understood with reference to FIGS. 6, 7, 8, and 9.

[0095] If the width d5 ​​of the first weld mark 61 is too small (i.e., d5<0.1 mm), it is difficult to ensure that the welding tensile force between the cathode current collector second part 112 and the cathode tab connection piece 51 meets the requirements, resulting in disadvantages due to the welding tensile force F being too small. On the other hand, if the width d5 ​​of the first weld mark 61 is too large (i.e., d5>10 mm), welding becomes difficult and costs increase. In this embodiment, by ensuring that the width d5 ​​of the first weld mark 61 satisfies the above numerical range (0.1 mm≦d5≦10 mm), it is possible to avoid disadvantages due to the width of the first weld mark 61 being too small and also avoid disadvantages due to the width of the first weld mark 61 being too large, thereby meeting the usage needs of the electrochemical device 10 and further improving the manufacturing yield of the electrochemical device 10.

[0096] Within the above numerical range, an appropriate value can be selected as needed for the width d5 ​​of the first weld mark 61. For example, assuming that 0.1 mm≦d5≦10 mm, d5 may be 0.1 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, etc., but is not particularly limited thereto.

[0097] 4A , 4B, and 4C , when the first side of the first weld mark 61 is located in the cathode current collector second part 112, the distance d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection piece 51 satisfies 0 mm≦d6≦5 mm. Alternatively, when the first side of the first weld mark 61 is located in the cathode tab connection piece 51, the distance d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection piece 51 satisfies 0 mm≦d6≦20 mm.

[0098] 4B illustrates an example in which a first side of the first weld mark 61 is located in the cathode current collector second part 112. (Note that although FIG. 4B illustrates that the first side of the first weld mark 61 is not in contact with the cathode current collector second part 112 and there is a gap between them, FIG. 4B actually illustrates that the first side of the first weld mark 61 is in direct contact with the cathode current collector second part 112 and is located in the cathode current collector second part 112 so as to form a weld between the cathode tab connection piece 51 and the cathode current collector second part 112. This is for ease of illustrating the structure and is not intended to limit the present application.) When the first side of the first weld mark 61 is located in the cathode current collector second part 112, the first side of the first weld mark 61 extends beyond the first side of the cathode tab connection piece 51 in the direction opposite to the width direction Y of the electrode plate, which corresponds to the first weld mark 61 covering the first side of the cathode tab connection piece 51. 4A and 4C , an example in which the first side of the first weld mark 61 is located on the cathode tab connection piece 51 corresponds to the first side of the first weld mark 61 extending beyond the first side of the cathode tab connection piece 51 in the width direction Y of the electrode plate and the first side of the cathode tab connection piece 51 not being covered by the first weld mark 61. The first side of the cathode tab connection piece 51 may be in an unrestricted state, i.e., the first side of the cathode tab connection piece 51 is not welded to the cathode current collector second part 112.

[0099] If the first side of the first weld mark 61 extends too far beyond the first side of the cathode tab connecting piece 51 in the direction opposite to the width direction Y of the electrode plate (for example, if the first side of the first weld mark 61 is located on the cathode current collector second part 112, d6 > 5 mm), there will be many areas where the cathode active material is absent, and the spatial occupation rate of the areas where energy cannot be supplied will be large, resulting in a large loss of energy density. This will affect the subsequent electrical connection between the cathode tab 41 and the cathode tab connecting piece 51 (for example, electrically connecting the cathode tab 41 and the cathode tab connecting piece 51 by welding), and the cathode tab connecting piece 51 will also be easily damaged in the process, which will result in an impact on the electrical characteristics of the manufactured electrochemical device 10. On the other hand, if the first side of the first weld mark 61 extends too far beyond the first side of the cathode tab connection piece 51 along the width direction Y of the electrode plate (for example, if the first side of the first weld mark is located on the cathode tab connection piece 51, d6>30 mm), the cathode tab connection piece 51 in an unrestricted state may be too wide, which increases the difficulty of the process when manufacturing the cathode plate 1 and affects the yield of the electrochemical device 10.

[0100] In the examples of the present application, by setting d6 within this numerical range, it is possible to avoid disadvantages caused by the first side of the first weld mark 61 excessively extending beyond the first side of the cathode tab connection piece 51 in the direction opposite to the width direction Y of the electrode plate, and it is also possible to avoid disadvantages caused by the first side of the first weld mark 61 excessively extending beyond the first side of the cathode tab connection piece 51 in the width direction Y of the electrode plate, thereby meeting the usage needs of the electrochemical device 10 and further improving the manufacturing yield of the electrochemical device 10.

[0101] Preferably, while satisfying the above numerical range, when the first side of the first weld mark 61 is located in the cathode current collector second portion 112, the distance d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection piece 51 satisfies 0 mm≦d6≦3 mm. Alternatively, when the first side of the first weld mark 61 is located in the cathode tab connection piece 51, the distance d6 between the first side of the first weld mark 61 and the first side of the cathode tab connection piece 51 satisfies 0 mm≦d6≦10 mm. Keeping the distance within this preferable numerical range further avoids disadvantages caused by the first side of the first weld mark 61 excessively extending beyond the first side of the cathode tab connection piece 51 in the direction opposite to the width direction of the electrode plate, and also avoids disadvantages caused by the first side of the first weld mark 61 excessively extending beyond the first side of the cathode tab connection piece 51 in the width direction of the electrode plate, thereby better meeting the use needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0102] Within the above numerical range, an appropriate value for d6 can be selected as needed. For example, when the first side of the first weld mark 61 is located in the cathode current collector second portion 112, assuming that 0 mm≦d6≦3 mm, d6 may be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3.0 mm, etc., but is not limited thereto. When the first side of the first weld mark 61 is located in the cathode tab connection piece 51, assuming that 0 mm≦d6≦10 mm, d6 may be 0 mm, 1 mm, 3 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., but is not limited thereto.

[0103] 4A , 4B, and 4C , when a first projection of the second side of the first weld mark 61 onto the cathode tab connection piece 51 overlaps with a second projection of the cathode current collector second portion 112 onto the cathode tab connection piece 51, a distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second portion 112 satisfies 0 mm≦d7≦15 mm. Alternatively, when the first projection of the second side of the first weld mark 61 onto the cathode tab connection piece 51 does not overlap with the second projection of the cathode current collector second portion 112 onto the cathode tab connection piece 51, a distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second portion 112 satisfies 0 mm≦d7≦7 mm.

[0104] It can be understood that the first projection may be a projection of the first weld mark 61 on the second side of the cathode tab connection piece 51 along the thickness direction of the cathode tab connection piece 51, and the second projection may be a projection of the cathode current collector second part 112 on the cathode tab connection piece 51 along the thickness direction of the cathode tab connection piece 51.

[0105] 4B and 4C , when the first projection overlaps with the second projection, the second side of the cathode current collector second portion 112 extends beyond the second side of the first weld mark 61 along the width direction of the electrode plate, and the second side of the cathode current collector second portion 112 is in an unrestricted state, i.e., the second side of the cathode current collector second portion 112 is not welded to the cathode tab connection piece 51. As shown in FIG. 4A , when the first projection does not overlap with the second projection, the second side of the cathode current collector second portion 112 does not extend beyond the second side of the first weld mark 61 along the width direction of the electrode plate, and the second side of the cathode current collector second portion 112 is welded to the cathode tab connection piece 51.

[0106] When the first projection overlaps with the second projection, if the distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second part 112 is too large (for example, when the first projection overlaps with the second projection, d7 > 15 mm), that is, if the second side of the cathode current collector second part 112 extends too far beyond the second side of the first weld mark 61 along the width direction of the electrode plate, the cathode current collector second part 112 in an unregulated state may be too wide, which will increase the process difficulty when manufacturing the cathode plate 1 and affect the manufacturing yield of the electrochemical device 10. On the other hand, when the first projection does not overlap the second projection, if the distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second part 112 is too large (for example, when the first projection does not overlap the second projection, d7 > 7 mm), that is, if the second side of the first weld mark 61 extends too far beyond the second side of the cathode current collector second part 112 along the width direction of the electrode plate, the loss of energy density will be significant, which will subsequently affect the electrical connection between the cathode tab 41 and the cathode tab connection piece 51 (for example, the cathode tab 41 and the cathode tab connection piece 51 are electrically connected by welding), and the cathode tab connection piece 51 will also be easily damaged in the process, which will result in an impact on the electrical characteristics of the manufactured electrochemical device 10.

[0107] In the examples of the present application, by setting d7 within this numerical range, it is possible to avoid the disadvantages caused by the second side of the cathode current collector second part 112 excessively extending beyond the second side of the first weld mark 61 along the width direction of the electrode plate, and it is also possible to avoid the disadvantages caused by the second side of the first weld mark 61 excessively extending beyond the second side of the cathode current collector second part 112 along the width direction of the electrode plate, thereby meeting the usage needs of the electrochemical device 10 and further improving the manufacturing yield of the electrochemical device 10.

[0108] Preferably, while the above-described numerical ranges are satisfied, when a first projection of the second side of the first weld mark 61 onto the cathode tab connection piece 51 overlaps with a second projection of the cathode current collector second part 112 onto the cathode tab connection piece 51, a distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second part 112 satisfies 0 mm≦d7≦10 mm. Alternatively, when the first projection of the second side of the first weld mark 61 onto the cathode tab connection piece 51 does not overlap with the second projection of the cathode current collector second part 112 onto the cathode tab connection piece 51, a distance d7 between the second side of the first weld mark 61 and the second side of the cathode current collector second part 112 satisfies 0 mm≦d7≦3 mm. Being within this preferred numerical range further avoids the disadvantages caused by the second side of the cathode current collector second part 112 extending too far beyond the second side of the first weld mark 61 along the width direction of the electrode plate, and further avoids the disadvantages caused by the second side of the first weld mark 61 extending too far beyond the second side of the cathode current collector second part 112 along the width direction of the electrode plate, thereby meeting the usage needs of the electrochemical device 10 and further improving the manufacturing yield of the electrochemical device 10.

[0109] Within the above numerical range, an appropriate value for d7 can be selected as needed. For example, if 0 mm≦d7≦10 mm is satisfied when the first projection overlaps with the second projection, d7 may be 0 mm, 1 mm, 3 mm, 5 mm, 8 mm, 9 mm, 10 mm, etc., but is not particularly limited thereto. For example, if 0 mm≦d7≦3 mm is satisfied when the first projection does not overlap with the second projection, d7 may be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., but is not particularly limited thereto.

[0110] In some preferred embodiments, the electrochemical device further comprises a tab electrically connected to the tab connection piece of the electrode plate by welding. Specifically, the electrochemical device further comprises a housing, and a part of the tab extends from the housing. Preferably, for the housing, the cathode plate 1, the separator 3, and the anode plate 2 may be provided in the housing, and the housing can protect them. Preferably, in the case of a soft pack battery cell, the housing can be manufactured from a metal plastic film, and the metal plastic film may be a steel plastic film, an aluminum plastic film, or the like. In any one of the embodiments of the present application, the electrode plate of the electrochemical device 10 may be the cathode plate 1 and / or the anode plate 2. When the electrode plate of the electrochemical device is the cathode plate 1, the tab 4 electrically connected to the cathode tab connection piece 51 of the cathode plate 1 by welding is the cathode tab. On the other hand, when the electrode plate of the electrochemical device is the anode plate 2, the tab 4 electrically connected to the anode tab connection piece of the anode plate 2 by welding is the anode tab.

[0111] Taking the case where the electrode plate is the cathode plate 1 as an example, the tab is the cathode tab 41. As shown in FIGS. 4A, 4B, and 4C, the cathode tab 41 is electrically connected to the cathode tab connection piece 51 by welding, and a second weld mark 62 is formed on the cathode tab connection piece 51. 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 along the width direction Y of the electrode plate. Here, the distance d8 between the second side of the first weld mark 61 and the first side of the second weld mark 62 satisfies 0 mm < d8 ≦ 10 mm.

[0112] In the present application, the specific welding method for welding the cathode tab 41 and the cathode tab connection piece 51 is not limited. For example, the welding method may be transition welding. In this case, the second weld mark 62 may be a weld mark by transition welding.

[0113] When the cathode tab 41 is electrically connected to the cathode tab connection piece 51 by welding, the second weld mark 62 formed on the cathode tab connection piece 51 cannot overlap with the first weld mark 61. If the two overlap, it will affect the welding effect between the cathode tab 41 and the cathode tab connection piece 51, and the welding tensile force between the two will decrease. If the distance 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, d8 > 10 mm), it is likely to affect the energy density of the electrochemical device 10. In this embodiment, by setting d8 within such a numerical range, it is possible to avoid the demerits caused by the overlap of the second weld mark 62 with the first weld mark 61, and also avoid the demerits caused by the distance d8 between the second side of the first weld mark 61 and the first side of the second weld mark 62 being too large. Thereby, the usage needs of the electrochemical device 10 are satisfied, and the manufacturing yield rate of the electrochemical device 10 is further improved.

[0114] Within the above numerical range, d8 can also be selected as an appropriate value as needed. For example, taking 0 mm < d8 ≤ 10 mm as an example, d8 can be 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, etc., but it is not particularly limited here.

[0115] In the embodiment of the present application, the width d1 of the cathode tab connection piece 51 (referring to FIGS. 4A, 4B, and 4C, that is, the width d1 of the cathode tab connection piece 51 is the distance between the first side and the second side of the cathode tab connection piece 51 along the width direction Y of the electrode plate) is not limited, as long as it can meet the needs of the electrochemical device 10. In some preferred embodiments, along the width direction Y of the electrode plate, the width d1 of the cathode tab connection piece 51 satisfies 3 mm ≤ d1 ≤ 25 mm.

[0116] If the width d1 of the cathode tab connecting piece 51 is too small, it becomes more difficult to weld the cathode tab connecting piece 51 and the cathode current collector second part 112 together during the manufacture of the electrochemical device 10. If the width d1 of the cathode tab connecting piece 51 is too large, the edge of the cathode tab connecting piece 51 is more likely to crumble and the cathode tab connecting piece 51 is more likely to break suddenly during the manufacture of the cathode plate 1. In this embodiment, the width of the cathode tab connecting piece 51 satisfies the above numerical range (i.e., 3 mm≦d1≦25 mm), thereby effectively avoiding the disadvantages caused by an excessively small width of the cathode tab connecting piece 51 and also avoiding the disadvantages caused by an excessively large width of the cathode tab connecting piece 51, thereby meeting the use needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0117] Preferably, the relationship 3 mm≦d1≦25 mm is satisfied, and the width d1 of the cathode tab connection piece 51 satisfies the relationship 5 mm≦d1≦25 mm. When the width d1 is within this preferred numerical range, disadvantages caused by an excessively small width of the cathode tab connection piece 51 can be further avoided, and disadvantages caused by an excessively large width of the cathode tab connection piece 51 can also be effectively avoided, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield of the electrochemical device 10.

[0118] Within the above numerical range, the width d1 of the cathode tab connection piece 51 can be selected as needed. For example, if 5 mm≦d1≦25 mm is taken as an example, d1 may be 5 mm, 10 mm, 15 mm, 18 mm, 20 mm, 23 mm, 25 mm, etc., but is not limited thereto.

[0119] In the embodiments of the present application, the width d2 of the cathode current collector second portion 112 of the cathode current collector 11 (referring to FIGS. 4A, 4B, and 4C, the width d2 of the cathode current collector second portion 112 is the distance between the first side of the cathode current collector second portion 112 and the second side of the cathode current collector second portion 112 along the width direction Y of the electrode plate) is not limited as long as it meets the needs of the electrochemical device 10. In some preferred embodiments, the width d2 of the cathode current collector second portion 112 along the width direction Y of the electrode plate satisfies 1 mm≦d2≦20 mm.

[0120] If the width of the cathode current collector second part 112 is too small, it is difficult to ensure the required welding width during manufacturing of the electrochemical device 10, making it more difficult to weld the cathode tab connection piece 51 and the cathode current collector second part 112. On the other hand, if the width of the cathode current collector second part 112 is too large, wrinkles are more likely to occur in the cathode current collector second part 112 after cold rolling during manufacturing of the cathode plate 1, which increases the loss of energy density and increases costs. By ensuring that the width of the cathode current collector second part 112 in this embodiment satisfies the above numerical range (i.e., 1 mm≦d2≦20 mm), it is possible to effectively avoid the disadvantages of a cathode current collector second part 112 that is too small and also to effectively avoid the disadvantages of a cathode current collector second part 112 that is too large, thereby meeting the needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0121] Preferably, the relationship 1 mm≦d2≦20 mm is satisfied, and the width d2 of the cathode current collector second portion 112 satisfies the relationship 1 mm≦d2≦10 mm. By being within this preferred range, it is possible to avoid disadvantages caused by a width of the cathode current collector second portion 112 that is too small, and it is also possible to suitably avoid disadvantages caused by a width of the cathode current collector second portion 112 that is too large, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0122] Within the above numerical range, an appropriate value can be selected as needed for the width d2 of the cathode current collector second portion 112. For example, assuming that 1 mm≦d2≦10 mm, d2 may be 1 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., but is not limited thereto.

[0123] 4A, 4B, and 4C, the insulating layer 13 includes a first side closer to the first sub-portion 1111 and a second side farther from the first sub-portion 1111 along the width direction Y of the electrode plate. When the first side of the cathode tab connection piece 51 is located on the insulating layer 13, the distance d4 between the first side of the cathode tab connection piece 51 and the second side of the insulating layer 13 satisfies 0 mm≦d4≦8 mm. Alternatively, when the first side of the cathode tab connection piece 51 is located on the cathode current collector second portion 112, the distance d4 between the first side of the cathode tab connection piece 51 and the second side of the insulating layer 13 satisfies 0 mm≦d4≦10 mm.

[0124] Specifically, referring to FIG. 4C , when the first side of the cathode tab connection piece 51 is located on the insulating layer 13, after the cathode tab connection piece 51 is welded to the cathode current collector second portion 112, the first end of the cathode tab connection piece 51 extends beyond the first side of the cathode current collector second portion 112 in the direction opposite to the width direction Y of the electrode plate. If the distance d4 exceeds the first side (e.g., d4 > 8 mm), the thickness of the manufactured electrochemical device 10 may be too large. As shown in FIGS. 4A and 4B , when the first side of the cathode tab connection piece 51 is located on the cathode current collector second portion 112, if the distance d4 between the first side of the cathode tab connection piece 51 and the second side of the insulating layer 13 is too large (e.g., d4 > 10 mm), the problem of the cathode current collector second portion 112 folding back after being welded to the cathode tab connection piece 51 cannot be effectively resolved.

[0125] In the present embodiment, d4 satisfying the above range of values ​​makes it possible to effectively avoid disadvantages caused by the first end of the cathode tab connection piece 51 excessively extending beyond the first side of the cathode current collector second part 112 in the direction opposite to the width direction Y of the electrode plate, and also makes it possible to effectively avoid disadvantages caused by d4 being too large when the first side of the cathode tab connection piece 51 is located on the cathode current collector second part 112, thereby satisfying the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0126] It is a more preferred embodiment that there is a gap between the first side of the cathode tab connection piece 51 and the insulating layer 13 and the cathode current collector second portion 112. Preferably, when the first side of the cathode tab connection piece 51 is located on the cathode current collector second portion 112, the gap d4 between the first side of the cathode tab connection piece 51 and the second side of the insulating layer 13 satisfies 0 mm≦d4≦5 mm. Having d4 within this preferred numerical range further avoids the disadvantages caused by d4 being too large when the first side of the cathode tab connection piece 51 is located on the cathode current collector second portion 112, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0127] It is understood that the above contents are merely some preferred examples of the electrochemical device 10 in the embodiments of the present application, and are not intended to limit the electrochemical device 10 in the embodiments of the present application.

[0128] In the embodiment of the present application, the electrode plates include a cathode plate and an anode plate. The cathode tab connection piece of the cathode plate is welded to the surface of the second portion of the cathode current collector (i.e., the uncoated edge region of the cathode current collector), and the anode tab connection piece of the anode plate is welded to the surface of the second portion of the anode current collector (i.e., the uncoated edge region of the anode current collector). Therefore, in the present application, when the cathode tab is led out from the cathode current collector, the cathode tab can be electrically connected via the cathode tab connection piece welded to the second portion of the cathode current collector without directly electrically connecting the cathode tab to the second portion of the cathode current collector. In the present application, when the anode tab is led out from the anode current collector, the anode tab can be electrically connected via the anode tab connection piece welded to the second portion of the anode current collector without directly electrically connecting the anode tab to the second portion of the anode current collector. Based on this, when manufacturing the cathode plate of the electrochemical device of the present application, if the cathode plate is cold-rolled, wrinkles are less likely to occur in the cathode plate, and when manufacturing the anode plate of the electrochemical device of the present application, if the anode plate is cold-rolled, wrinkles are less likely to occur in the anode plate. Therefore, by manufacturing an electrochemical device using such cathode plates and anode plates, the manufacturing yield of the electrochemical device can be effectively improved.

[0129] According to another aspect of the present embodiment, and referring to the structural block diagram of FIG. 10, the present embodiment provides a power consuming device 20 comprising any one of the electrochemical devices 10 described above.

[0130] In particular, the electrochemical device 10 may be used to provide power to electrical components within a power consumer 20 .

[0131] The power consuming device 20 in the embodiment of the present application includes the electrochemical device 10 described above, and since the manufacturing yield of the electrochemical device 10 is high, the manufacturing yield of the power consuming device 20 is also high.

[0132] Below, several examples of the actual electrochemical device 10 in the examples of the present application and several comparative examples of electrochemical devices in the related art will be described. By comparing these examples and comparative examples, the beneficial effects of the electrochemical device 10 in the examples of the present application over the related art can be more easily understood. In these comparative examples and examples, a lithium ion battery will be described as the electrochemical device.

[0133] The electrochemical device in Comparative Example 1 has a conventional wound structure. The difference between Comparative Example 2 and Example 1 is that the ratio of the area of ​​the welded mark to the area of ​​the welded region is less than 20%, and the ratio of the length of the welded region to the length of the overlapping region is less than 60%. Because the weld strength does not meet the requirements, the weld strength becomes unstable during the manufacturing process of the electrochemical device, and the tab connection piece is partially separated from the surface of the second part of the cathode, making measurement difficult.

[0134] The electrochemical device in Example 1 is formed by winding the cathode plate in Example 1 in Table 1 and an anode plate of a conventional structure, and to meet the requirements for welding stability, the ratio of the area of ​​the weld mark to the area of ​​the welded region in the cathode plate is 20% or more, and the ratio of the length of the welded region to the length of the overlapping region is 60% or more. Examples 2 to 16 are all the same as Example 1. Furthermore, in Examples 1 to 16, compared to Comparative Example 1, when manufacturing the cathode plate, the cathode tab connection piece is welded to the uncoated edge region of the cathode current collector (i.e., the second portion of the cathode current collector) without stretching the uncoated edge region of the cathode current collector before cold rolling, and all parameters are the same except that the stepped roll is removed during the cold rolling process. In addition, in Examples 1 to 18, all parameters were the same as in Comparative Example 1 except that, when manufacturing a cathode plate, the uncoated edge region of the cathode current collector was not stretched before cold rolling, the cathode tab connection piece was welded to the uncoated edge region of the cathode current collector (i.e., the second part of the cathode current collector), and the stepped roll was removed during the cold rolling process. In Comparative Example 2, the ratio of the area of ​​the weld mark to the area of ​​the welded region and the ratio of the length of the welded region to the length of the overlapping region did not meet the requirements, so experimental data could not be measured.

[0135] Table 1 shows relevant data for the cathode plates of the electrochemical devices in Comparative Examples 1 and 2 and Examples 1 to 16.

[0136] [Table 1]

[0137] For ease of reading, Table 1 above is set as follows: In the column for d4, a negative number indicates that the first side of the cathode tab connection piece 51 is positioned on the insulating layer 13 (for example, when d4 in Table 1 is −2 mm, that is, the first side of the cathode tab connection piece 51 is positioned on the insulating layer 13, and d4 = 2 mm), and a positive number indicates that the first side of the cathode tab connection piece 51 is positioned on the cathode current collector second part 112 (for example, when d4 in Table 1 is 2 mm, that is, the first side of the cathode tab connection piece 51 is positioned on the cathode current collector second part 112, and d4 = 2 mm). In the d6 column, a negative number indicates that the first side of the first weld mark 61 is located on the cathode current collector second part 112 (for example, if d6 in Table 1 is -3 mm, that is, the first side of the first weld mark 61 is located on the cathode current collector second part 112, and d6 = 3 mm), and a positive number indicates that the first side of the first weld mark 61 is located on the cathode tab connection piece 51 (for example, if d6 in Table 1 is 20 mm, that is, the first side of the first weld mark 61 is located on the cathode tab connection piece 51, and d6 = 20 mm). Also, in Table 1, "\" indicates "none," and the number of "★" indicates the degree of wrinkles. The more "★" there are, the more severe the degree of wrinkles. In addition, in the case of Examples 1 to 18, the tab folding ratio refers to the folding ratio of cathode tab connection piece 51 and cathode current collector second portion 112 (this can be understood with reference to FIGS. 3A and 3B and 4A, 4B, and 4C). On the other hand, in the case of Comparative Examples 1 and 2, the tab folding ratio refers to the folding ratio of edge uncoated region 14' (this can be understood with reference to FIG. 2).

[0138] As can be seen from the analysis of the data for each group shown in Table 1 above, the electrochemical device 10 in the examples of the present application (i.e., Examples 1 to 18) significantly improves the occurrence of wrinkles after the cathode plate 1 is cold-rolled and also significantly improves the folding back of the tabs compared to electrochemical devices in the related art. Therefore, by manufacturing the electrochemical device 10 using such a cathode plate 1, the manufacturing yield rate of the electrochemical device 10 can be effectively improved.

[0139] As used herein, the term "comprises" and variations thereof are open-ended, meaning "including, but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment," the term "another embodiment" means "at least one other embodiment," and the term "some embodiments" means "at least some embodiments." Relevant definitions of other terms are provided below. Note that concepts such as "first," "second," etc., used in this application are only used to distinguish between different devices, modules, or units, and are not used to limit the order or interdependence of functions performed by these devices, modules, or units.

[0140] It should be noted that the modifiers "one" and "multiple" used herein are intended to be illustrative rather than limiting, and will be understood by those skilled in the art to mean "one or more" unless the context clearly indicates otherwise.

[0141] Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any modifications, uses, or adaptations of the present application. These modifications, uses, or adaptations comply with the general principles of the present application and include common general knowledge or customary technical means in the art that are not disclosed herein. The specification and examples are considered to be exemplary only. The true scope and spirit of the present application are indicated by the appended claims.

Claims

1. 1. An electrochemical device comprising: a plate including a current collector, an active material layer, and a tab connection piece; When the electrode plate is unfolded, the current collector includes a first portion and a second portion along the width direction of the electrode plate, the active material layer is provided on a surface of the first portion, the second portion is a non-coated region where the active material layer is not provided, the tab connection piece and a surface of the second part overlap to form an overlapping region, and the tab connection piece is welded to the surface of the second part so as to be electrically connected to the second part; Along the length direction of the electrode plate, the ratio of the area of ​​the weld mark to the area of ​​the welded region is 20% or more, and the ratio of the length of the welded region to the length of the overlapping region is 60% or more. Electrochemical device characterized by:

2. the electrode plate is a cathode plate, the first portion includes a first sub-portion and a second sub-portion connected to each other, the second sub-portion is connected to the second portion, the active material layer is provided on the first sub-portion, and an insulating layer is provided on the second sub-portion; Along the width direction of the electrode plate, the second portion includes a first side close to the first sub-portion and a second side away from the first sub-portion, and the tab connection piece includes a first side close to the first sub-portion and a second side away from the first sub-portion; a gap exists between the tab connection piece and the first sub-portion, and a second side of the second portion is located between the first side of the tab connection piece and the second side of the tab connection piece; 2. The electrochemical device according to claim 1.

3. Along the width direction of the electrode plate, the width d1 of the tab connection piece satisfies 3 mm ≦ d1 ≦ 25 mm; 3. The electrochemical device according to claim 2.

4. Along the width direction of the electrode plate, the width d2 of the second portion satisfies 1 mm ≦ d2 ≦ 20 mm.

3. The electrochemical device according to claim 2.

5. Along the width direction of the electrode plate, the width d3 of the insulating layer satisfies 0.5 mm≦d3≦5 mm.

3. The electrochemical device according to claim 2.

6. Along the width of the plate, the insulating layer includes a first side proximate to the first sub-portion and a second side remote from the first sub-portion; When the first side of the tab connection piece is located on the insulating layer, a distance d4 between the first side of the tab connection piece and the second side of the insulating layer satisfies 0 mm≦d4≦8 mm; Or, When the first side of the tab connection piece is located in the second portion, a distance d4 between the first side of the tab connection piece and the second side of the insulating layer satisfies 0 mm≦d4≦10 mm.

3. The electrochemical device according to claim 2.

7. the welding mark includes a first welding mark formed when the second portion and the tab connection piece are welded together, Along the width direction of the electrode plate, the first weld mark includes a first side close to the first sub-portion and a second side away from the first sub-portion, a second side of the first weld mark is located on the tab connection piece, and a gap exists between the first weld mark and the first sub-portion; 3. The electrochemical device according to claim 2.

8. Along the width direction of the electrode plate, the width d5 ​​of the first weld mark satisfies 0.1 mm≦d5≦10 mm.

8. The electrochemical device according to claim 7.

9. When the first side of the first weld mark is located in the second portion, a distance d6 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦d6≦5 mm, Or, When the first side of the first weld mark is located on the tab connection piece, a distance d6 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦d6≦20 mm.

8. The electrochemical device according to claim 7.

10. When a first projection of a second side of the first weld mark onto the tab connection piece overlaps with a second projection of the second portion onto the tab connection piece, a distance d7 between the second side of the first weld mark and the second side of the second portion satisfies 0 mm≦d7≦15 mm, Or, When a first projection of the second side of the first weld mark onto the tab connection piece does not overlap with a second projection of the second portion of the electrode plate onto the tab connection piece, a distance d7 between the second side of the first weld mark and the second side of the second portion satisfies 0 mm≦d7≦7 mm.

8. The electrochemical device according to claim 7.

11. the electrochemical device further includes a tab electrically connected to the tab connection piece by welding and forming a second weld mark on the tab connection piece; Along the width direction of the electrode plate, the second weld mark includes a first side close to the first sub-portion and a second side away from the first sub-portion, A distance d8 between the second side of the first weld mark and the first side of the second weld mark satisfies 0 mm < d8 ≦ 10 mm.

8. The electrochemical device according to claim 7.

12. The welding tensile force between the second part and the tab connection piece is 70 N or more and 1000 N or less.

2. The electrochemical device according to claim 1.

13. An electric power consuming device comprising the electrochemical device according to any one of claims 1 to 12.

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