Electrochemical equipment and power consumers

Abstract

The present application discloses an electrochemical device and a power consuming device, the electrochemical device including a pole piece, the pole piece including a current collector, an active material layer disposed on a surface of the current collector, and a plurality of tab connections, each of which includes a first portion and a second portion, and when the pole piece is unfolded, the first portions of the plurality of tab connections extend from an edge of the current collector in the width direction of the pole piece and are disposed at intervals, and the second portions are disposed on the surface of the first portion and are electrically connected to the first portion.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present embodiments relate to the field of electrochemical technology, and more particularly to electrochemical devices and power consuming equipment. [Background technology]

[0002] With the development of science and technology, electrochemical devices (including, but not limited to, lithium-ion batteries, sodium-ion batteries, etc.) have been widely applied, providing convenience for devices such as tablet computers, smartphones, electric vehicles, and energy storage devices.

[0003] One type of electrochemical device according to the related art is composed of a cathode piece, an anode piece, and a separator placed between them. During the manufacturing process, it is necessary to die-cut a number of structures for pulling out tabs in the uncoated areas on the edges of the current collectors of the cathode piece and the anode piece, and electrically connect the tabs to the structures.

[0004] In such electrochemical devices, an insulating layer is typically provided between the active material layer of the current collector on the cathode piece and the uncoated edge area of ​​the current collector to prevent short circuits between the cathode piece and the anode piece. In one form of manufacturing such cathode pieces, cold rolling is performed on the cathode piece on which the active material layer and insulating layer are provided before die cutting. Since the thickness of the insulating layer and the uncoated edge area of ​​the current collector are different, wrinkles are likely to occur in the uncoated edge area of ​​the current collector during the cold rolling process. Therefore, before cold rolling, the uncoated edge area of ​​the current collector on the cathode piece is typically stretched to match the degree of deformation of the uncoated edge area of ​​the current collector and the insulating layer. This prevents wrinkles from occurring in the cathode piece during the subsequent cold rolling of the cathode piece. However, although this structure can alleviate the problem of wrinkles occurring in the cathode pieces during cold rolling, the cold rolling tension of the cathode pieces increases, making the cathode pieces more susceptible to fracture during the cold rolling process, which seriously reduces the yield rate of electrochemical devices. Summary of the Invention

[0005] In view of this, the present embodiments provide an electrochemical device and a power consuming device that alleviate at least some of the above problems.

[0006] According to a first aspect of the present invention, there is provided an electrochemical device including a pole piece, the pole piece including a current collector, an active material layer disposed on a surface of the current collector, and a plurality of tab connections, each of which includes a first portion and a second portion, and when the pole piece is unfolded, the plurality of tab connections have first portions extending from an edge of the current collector in the width direction of the pole piece and disposed at intervals, and second portions disposed on the surface of the first portion and electrically connected to the first portion.

[0007] In the electrochemical device provided in the present embodiment, the pole pieces of the electrochemical device include multiple tab connections, each of which includes a first portion (i.e., an uncoated area extending from the edge of the current collector) and a second portion, with the first portion electrically connected to the second portion. Rather than directly electrically connecting the first portion to the tab, the second portion is placed on the surface of the first portion, a tab connection is formed, and the tab is welded to the tab through the tab connection. In this way, when manufacturing the pole pieces of the electrochemical device, the tab connection is not directly formed on the first portion, which reduces the width of the first portion and alleviates the problem of wrinkles occurring during cold rolling. Meanwhile, because the first portion (i.e., the uncoated area extending from the edge of the current collector) is not stretched before cold rolling the pole pieces, the problem of wrinkles occurring in the cathode pieces when cold rolling the cathode pieces subsequently is similarly alleviated. Furthermore, since there is no need to stretch the first portion of the pole piece (i.e., the uncoated area extending from the edge of the current collector), the cold rolling tension of the pole piece is reduced, which solves the problem of the pole piece being prone to breakage during the cold rolling process, thereby improving the yield of electrochemical devices.

[0008] In some preferred embodiments, the width W1 of the second portion along the width direction of the pole piece satisfies 3 mm≦W1≦35 mm.

[0009] If the width of the second portion is too small, it is difficult to weld the second portion to the first portion during the fabrication of an electrochemical device. On the other hand, if the width of the second portion is too large, the edge of the second portion is likely to be indented during die-cutting during the fabrication of a pole piece (e.g., a cathode piece), affecting the accuracy of the die-cutting. In particular, when performing die-cutting using a laser, the laser focus may be significantly removed from the cutting surface, resulting in an unsuccessful cut and even unintentional breakage of the second portion. By ensuring that the width of the second portion in this embodiment satisfies the above numerical range (i.e., 3 mm ≦ W1 ≦ 35 mm), the drawbacks of a second portion being too small and the drawbacks of a second portion being too large are effectively avoided. This meets the needs of electrochemical devices and improves the yield rate of electrochemical devices.

[0010] In some preferred embodiments, the width W1 of the second portion along the width direction of the pole piece satisfies the range 5 mm≦W1≦25 mm. By setting the width of the second portion in this range, the disadvantage of the second portion being too small can be further avoided, and the disadvantage of the second portion being too large can be better avoided. This meets the usage needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0011] In some preferred embodiments, the width W2 of the first portion along the width direction of the pole piece satisfies 0.5 mm≦W2≦20 mm.

[0012] If the width of the first portion is too small, it is difficult to ensure a sufficient welding width during the fabrication of an electrochemical device, making it difficult to weld the second portion and the first portion together. On the other hand, if the width of the first portion is too large, wrinkles are likely to occur in the first portion after cold rolling during the fabrication of an electrode piece (e.g., a cathode piece), affecting the integration of the second portion welded to the die-cut first portion, increasing energy density loss and increasing costs. By ensuring that the width of the first portion in this embodiment satisfies the above numerical range (i.e., 0.5 mm≦W2≦20 mm), the disadvantages of a first portion being too small and the disadvantages of a first portion 131 being too large are effectively avoided. This satisfies the needs of electrochemical devices and improves the yield rate of electrochemical devices.

[0013] In some preferred embodiments, the width W2 of the first portion along the width direction of the pole piece satisfies 1 mm≦W2≦10 mm. By setting the width of the first portion in this range, the disadvantage of the first portion being too small can be further avoided, and the disadvantage of the first portion being too large can be better avoided. This meets the usage needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0014] In some preferred embodiments, the electrode piece includes a cathode piece, and an insulating layer is further disposed on the surface of the current collector, with the active material layer and the insulating layer arranged along the width direction of the electrode piece. Thus, when the electrode piece is a cathode piece, the insulating layer can insulate and separate the cathode piece from the current collector and the anode piece, effectively preventing the occurrence of a short circuit between the cathode piece and the anode piece.

[0015] In some preferred embodiments, the width W3 of the insulating layer along the width direction of the pole piece satisfies 0.5 mm≦W3≦5 mm, and this embodiment uses an insulating layer with a width in this range to effectively insulate and separate the current collector of the cathode piece from the anode piece, preventing short circuits between them, and meeting the needs of the electrochemical device without increasing extra costs.

[0016] In some preferred embodiments, the insulating layer is made of at least one of alumina and silicon oxide, and the insulating layer insulates and separates the cathode current collector from the anode current collector, thereby effectively preventing short circuits between the cathode current collector and the anode current collector.

[0017] In some preferred embodiments, along the width direction of the pole piece, the insulating layer includes a first side close to the active material layer and a second side away from the active material layer, the first side of the second portion is located on the insulating layer, and a distance W4 between the first side of the second portion and the second side of the insulating layer satisfies 0 mm≦W4≦8 mm; or the first side of the second portion is located on the surface of the first portion, and a distance W4 between the first side of the first portion and the second side of the insulating layer satisfies 0 mm≦W4≦10 mm.

[0018] Because the pole piece is a cathode, if the first side of the second part is located on the insulating layer, after the second part is welded to the first part, the first end of the second part will extend beyond the first side of the first part in the opposite direction of the pole piece's width. If the distance exceeds too much, the resulting electrochemical device is likely to be too thick. Furthermore, because the pole piece is a cathode, the first side of the second part is located on the surface of the first part. If the distance between the first side of the second part and the second side of the insulating layer is too large, the problem of the first and second parts being folded back after welding cannot be effectively solved. In this application, by ensuring that W4 satisfies the above numerical range, the drawback of the first end of the second part extending beyond the first side of the first part in the opposite direction of the pole piece's width and the drawback of the first side of the second part being located on the first part and the distance between the first side of the second part and the second side of the insulating layer being too large can be effectively avoided. This meets the needs of electrochemical devices and improves the yield rate of electrochemical devices.

[0019] In some preferred embodiments, the first side of the second part is located on the surface of the first part, and the distance W4 between the first side of the second part and the second side of the insulating layer satisfies 0 mm≦W4≦5 mm. In the present application, W4 satisfies this numerical range, which further avoids the drawbacks that would occur if the first side of the second part were located on the first part and the distance between the first side of the second part and the second side of the insulating layer were too large. This meets the usage needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0020] In some preferred embodiments, the pole pieces include anode pieces. The use of the pole piece structure of the present invention can effectively alleviate the problem of the anode pieces being prone to fracture during the cold rolling process, thereby improving the yield of electrochemical devices.

[0021] In some preferred embodiments, the first and second parts are electrically connected by welding, and a first weld mark is formed when the first and second parts are welded together, and the first weld mark has a first side close to the active material layer and a second side away from the active material layer along the width direction of the pole piece, and the second side of the first weld mark is located on the second part, and there is a gap between the first side of the first weld mark and the active material layer. Based on this, electrically connecting the first and second parts by welding in the present application can ensure the stability of the electrical connection between the second part and the first part, and having the second side of the first weld mark located on the second part ensures that the second part and the first part can be stably connected by welding.

[0022] In some preferred embodiments, the width W5 of the first weld mark along the width direction of the pole piece satisfies 0.1 mm≦W5≦10 mm.

[0023] If the width of the first weld mark is too small, it is difficult to ensure that the weld tensile strength between the first and second parts meets the requirements, resulting in the disadvantages of too small a weld tensile strength. Furthermore, if the width of the first weld mark is too large, it is difficult to assemble the die-cut second part after die-cutting the first part (i.e., the uncoated area extending from the edge of the current collector) and the second part of the electrode piece (e.g., cathode piece), resulting in additional costs. By ensuring that the width of the first weld mark in this application satisfies the above numerical range (0.1 mm≦W5≦10 mm), the disadvantages of a first weld mark that is too small and the disadvantages of a first weld mark that is too large can be avoided. This meets the usage needs of electrochemical devices and improves the yield rate of electrochemical devices.

[0024] In some preferred embodiments, the first side of the first weld mark is located on the first portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦5 mm; or the first side of the first weld mark is located on the surface of the second portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦30 mm.

[0025] If the first side of the first weld mark extends too far beyond the first side of the second portion along the opposite width of the pole piece, there will be many areas without active material (e.g., cathode active material), and the occupied space of areas that cannot supply energy will be large, resulting in a significant loss of energy density. This will affect the subsequent electrical connection between the tab (e.g., cathode tab) and the second portion (e.g., electrically connecting the tab (e.g., cathode tab) and the second portion by welding), affecting the assembly of the die-cut second portion, making the second portion susceptible to damage during this process and affecting the electrical performance of the final electrochemical device. Furthermore, if the first side of the first weld mark extends too far beyond the first side of the second portion along the width of the pole piece, the second portion may be too wide in an unconstrained state, affecting the die-cutting process during pole piece (e.g., cathode piece) manufacturing, making the process more difficult and affecting the yield rate of electrochemical devices. In the present application, using this numerical range for W6 can avoid the drawback that occurs when the first side of the first weld mark exceeds the first side of the second part along the opposite width direction of the pole piece, and can also avoid the drawback that occurs when the first side of the first weld mark exceeds the first side of the second part along the width direction of the pole piece, thereby meeting the usage needs of electrochemical devices and improving the yield rate of electrochemical devices.

[0026] In some preferred embodiments, the first side of the first weld mark is located on the first portion, and the distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦3 mm; alternatively, the first side of the first weld mark is located on the surface of the second portion, and the distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦10 mm. By setting W6 in this range, it is possible to effectively avoid the drawback of the first side of the first weld mark extending too far beyond the first side of the second portion along the opposite width direction of the pole piece, and further avoid the drawback of the first side of the first weld mark extending too far beyond the first side of the second portion along the width direction of the pole piece. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0027] In some preferred embodiments, there is an overlapping portion between the first projection of the first weld mark onto the second portion of the second side and the second projection of the first portion onto the second portion, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦15 mm; or there is no overlapping portion between the first projection of the first weld mark onto the second portion of the second side and the second projection of the first portion onto the second portion, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦7 mm.

[0028] When there is an overlap between the first projection and the second projection, if the distance W7 between the second side of the first weld mark and the second side of the first part is too large, that is, if the second side of the first part exceeds the second side of the first weld mark along the width direction of the pole piece, the first part may be too wide in an unconstrained state, which will affect the die cutting when manufacturing the pole piece (e.g., cathode piece), making the process more difficult and affecting the yield rate of the electrochemical device. Furthermore, if the first projection and the second projection do not overlap, and the distance W7 between the second side of the first weld mark and the second side of the first portion is too large, i.e., the second side of the first weld mark extends beyond the second side of the first portion along the width direction of the pole piece, this will result in a significant loss of energy density, affect the subsequent electrical connection between the tab (e.g., the cathode tab) and the second portion (e.g., electrically connecting the tab (e.g., the cathode tab) and the second portion by welding), affect the assembly of the die-cut second portion, and during this process, the second portion is likely to be damaged, ultimately affecting the electrical performance of the manufactured electrochemical device. In this application, using this numerical range for W7 can avoid the drawbacks that occur when the second side of the first portion extends beyond the second side of the first weld mark along the width direction of the pole piece, as well as the drawbacks that occur when the second side of the first weld mark extends beyond the second side of the first portion along the width direction of the pole piece. This meets the needs of electrochemical devices and improves the yield rate of manufactured electrochemical devices.

[0029] In some preferred embodiments, there is an overlapping portion between the first projection of the second side of the first welding trace onto the second portion and the second projection of the first portion onto the second portion. The distance W7 between the second side of the first welding trace and the second side of the first portion satisfies 0 mm ≤ W7 ≤ 10 mm. Alternatively, there is no overlapping portion between the first projection of the second side of the first welding trace onto the second portion and the second projection of the first portion onto the second portion, and the distance W7 between the second side of the first welding trace and the second side of the first portion satisfies 0 mm ≤ W7 ≤ 3 mm. By having W7 of the present application satisfy such a numerical range, the drawback when the second side of the first portion extends too far beyond the second side of the first welding trace along the width direction of the electrode tab can be further avoided, and the drawback when the second side of the first welding trace extends too far beyond the second side of the first portion along the width direction of the electrode tab can be further avoided. Thereby, the usage needs of the electrochemical device are met, and the manufacturing yield rate of the electrochemical device is further improved.

[0030] In some preferred embodiments, the electrochemical device further includes a case and a tab extending from the case. The tab is electrically connected to the second portion by welding, and a second welding trace is formed on the second portion. Along the width direction of the electrode tab, the second welding trace includes a first side close to the first portion and a second side away from the first portion. The distance W8 between the second side of the first welding trace and the first side of the second welding trace satisfies 0 mm < W8 ≤ 10 mm.

[0031] When the tab (for example, the cathode tab) is electrically connected to the second portion by welding, the second welding trace formed on the second portion and the first welding trace do not overlap. If they overlap, it will affect the welding effect between the tab (for example, the cathode tab) and the second portion and reduce the tensile strength of the welding between the two. Also, if the distance W8 between the second side of the first welding trace and the first side of the second welding trace is too large, it is likely to affect the energy density of the electrochemical device. In the present application, by using such a numerical range of W8, the drawback when the second welding trace and the first welding trace overlap can be avoided, and the drawback when the distance W8 between the second side of the first welding trace and the first side of the second welding trace is too large can be avoided. Thereby, the usage needs of the electrochemical device are met, and the manufacturing yield rate of the electrochemical device is improved.

[0032] In some preferred embodiments, the weld tensile strength F between the first part and the second part satisfies 5N≦F≦1000N.

[0033] If the weld tensile strength F between the first and second parts is too small, the second part will easily come off the first part during use of the electrochemical device. Furthermore, if the weld tensile strength F between the first and second parts is too large, it will affect the cost of manufacturing the electrochemical device. By ensuring that the weld tensile strength F satisfies the above numerical range (i.e., 5N≦F≦1000N), the drawback of a weld tensile strength F between the first and second parts being too small can be effectively avoided, while the drawback of a weld tensile strength F between the first and second parts being too large can also be effectively avoided. This meets the needs of electrochemical devices and improves the yield rate of manufactured electrochemical devices.

[0034] In some preferred embodiments, the weld tensile strength F between the first and second parts satisfies 10 N≦F≦500 N. In the present application, by making the weld tensile strength F satisfy this numerical range, the drawback of the weld tensile strength F between the first and second parts being too small can be better avoided, and the drawback of the weld tensile strength F between the first and second parts being too large can be better avoided, thereby meeting the usage needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0035] In some preferred embodiments, the first and / or second parts are conductive foil materials, and the resistance R per square millimeter of the conductive foil material satisfies R<20 mΩ, thereby improving the conductive performance of the first and / or second parts of the present invention and meeting the requirements of electrochemical devices.

[0036] In some preferred embodiments, the conductive foil material includes at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil, and the conductive foil material of such a material can be used to ensure the conductive performance of the first and / or second parts of the electrode piece (especially the cathode piece) and meet the requirements of the electrochemical device.

[0037] In some preferred embodiments, the aluminum-plated foil material includes at least one of a foil material obtained by aluminum-plating the surface of a thin polypropylene film and a foil material obtained by aluminum-plating the surface of a thin polyethylene terephthalate film. Using such conductive foil material ensures the conductive performance of the first and / or second parts of the electrode piece (especially the cathode piece) and meets the requirements of the electrochemical device.

[0038] In some preferred embodiments, the thickness L of the second portion satisfies 4 μm≦L≦25 μm.

[0039] If the thickness of the second part is too thin, the manufacturing process for the pole piece (e.g., cathode piece) becomes difficult and costs increase. Furthermore, the thickness is too thin, resulting in low strength, making it difficult to meet the structural strength requirements for the pole piece (e.g., cathode piece) and the second part. On the other hand, if the thickness of the second part is too thick, material costs increase and the energy density efficiency of the electrochemical device decreases. In this application, by ensuring that the thickness of the second part satisfies the above numerical range (i.e., 4 μm≦L≦25 μm), the disadvantages of having a second part that is too thin and the disadvantages of having a second part that is too thick can be effectively avoided. This meets the usage needs of electrochemical devices and improves the yield rate of electrochemical devices.

[0040] In some preferred embodiments, the thickness L of the second portion satisfies 5 μm≦L≦20 μm. In the present application, the thickness L of the second portion satisfies this numerical range, which can better avoid the disadvantage of the second portion being too thin and the disadvantage of the second portion being too thick, thereby meeting the usage needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0041] In some preferred embodiments, the breaking strength S of the second portion satisfies 80 MPa≦S≦800 MPa.

[0042] If the breaking strength of the second part is too low, it will be prone to fracture during the manufacturing process, making the manufacturing process of the pole piece (e.g., cathode piece) more difficult and increasing costs. If the breaking strength is too low, it will be difficult to meet the structural strength requirements of the pole piece (e.g., cathode piece) and the second part. On the other hand, if the breaking strength of the second part is too high, the manufacturing process of the pole piece (e.g., cathode piece) will be more difficult and increasing costs. In this embodiment, the breaking strength of the second part satisfies the above numerical range (i.e., 80 MPa≦S≦800 MPa), which effectively avoids the disadvantages of the second part having too low a breaking strength and also effectively avoids the disadvantages of the second part having too high a breaking strength. This satisfies the use needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0043] In some preferred embodiments, the breaking strength S of the second portion satisfies the range 100 MPa≦S≦450 MPa. In the present application, the breaking strength S of the second portion satisfies this range, which can better avoid the drawback of the second portion having an excessively low breaking strength and the drawback of the second portion having an excessively high breaking strength, thereby meeting the needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0044] In some preferred embodiments, the electrochemical device is fabricated by winding together a cathode piece, a separator, and an anode piece.

[0045] According to a second aspect of the present invention, there is provided an electric power consuming device including the electrochemical device provided in the first aspect.

[0046] The power consuming device of the present embodiment includes the electrochemical device provided in the first aspect, and therefore the yield of the electrochemical device is high, and therefore the yield of the power consuming device is also high.

[0047] In order to more clearly explain the technical solutions of the embodiments of the present application, the following will briefly describe the drawings required for the present application. However, the drawings described below are only some embodiments described in the embodiments of the present application, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings. [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 is a schematic diagram of an electrochemical device according to an example of the present invention. [Figure 2] FIG. 2 shows a process for fabricating a cathode piece for an electrochemical device according to an example of the related art. [Figure 3A] FIG. 3A illustrates a process for fabricating a cathode piece for an electrochemical device according to an embodiment of the present invention. [Figure 3B] FIG. 3B is an enlarged schematic view of T in FIG. 3A. [Figure 4A] FIG. 4A is a schematic cross-sectional view of a cathode piece of an electrochemical device according to an example of the present invention, taken along the thickness direction. [Figure 4B] FIG. 4B is a schematic cross-sectional view of a cathode piece of an electrochemical device according to another embodiment of the present invention, taken along the thickness direction thereof. [Figure 4C] FIG. 4C is a schematic cross-sectional view of a cathode piece in the thickness direction of an electrochemical device according to still another embodiment of the present invention. [Figure 4D] FIG. 4D is a schematic cross-sectional view of an anode piece of an electrochemical device according to an example of the present invention, taken along the thickness direction. [Figure 5] FIG. 5 is a schematic diagram of an ultrasonic seam welding method 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 the present invention. [Figure 7] FIG. 7 is a schematic diagram of a first welding mark according to another example of the present invention. [Figure 8] FIG. 8 is a schematic diagram of a first welding mark according to still another example of the present invention. [Figure 9] FIG. 9 is a schematic diagram of a first welding mark according to yet another example of the present invention. [Figure 10] FIG. 10 is a schematic diagram of a power consuming device according to an example embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0049] In order to allow those skilled in the art to more fully understand the technical solutions of the embodiments of the present application, the technical solutions of the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application. Of course, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present application are all included in the protection scope of the embodiments of the present application.

[0050] Specific embodiments of the electrochemical device and the power consuming device of the present invention will be described below with reference to the accompanying drawings. Note that for the sake of convenience, the structures in the accompanying drawings are not necessarily drawn to scale.

[0051] In the summary of the embodiments of the present invention, the present invention will be described using a lithium ion battery as an example of the electrochemical device 10, but the electrochemical device 10 of the present invention is not limited to a lithium ion battery and may be, for example, a sodium ion battery.

[0052] An electrochemical device provided in a first aspect of the present embodiment includes a pole piece, the pole piece including a current collector, an active material layer disposed on a surface of the current collector, and a plurality of tab connections, each of which includes a first portion and a second portion, and when the pole piece is unfolded, the first portions of the plurality of tab connections extend from an edge of the current collector in the width direction of the pole piece and are disposed at intervals, and the second portions are disposed on the surface of the first portion and are electrically connected to the first portion.

[0053] Referring to FIG. 1 , an electrochemical device 10 is manufactured by winding a cathode piece 1, a separator 3, and an anode piece 2. This is merely an example and should not be construed as a limitation on this embodiment. Specifically, after winding into the electrochemical device 10, a separator 3 is disposed between the cathode piece 1 and the anode piece 2 to isolate the cathode piece 1 and the anode piece 2, prevent short-circuiting between the cathode and anode pieces inside the electrochemical device 10, allow ions to pass through, and maintain the function of an electrolyte between the cathode piece 1, the separator 3, and the anode piece 2. Preferably, the electrode piece of the present application may be the cathode piece 1 or the anode piece 2. As shown in Figures 1 to 9, for example, the pole piece is a cathode piece 1, and includes a current collector 11, an active material layer 12 disposed on the surface of the current collector 11, and a plurality of tab connection portions 13, each of which includes a first portion 131 and a second portion 132. When the pole piece is unfolded, the first portion 131 extends from the edge of the current collector 11 in the width direction Y of the pole piece and is disposed at an interval, and the second portion 132 is disposed on the surface of the first portion 131 and is electrically connected to the first portion 131.

[0054] In the present embodiment, the pole pieces for an electrochemical device include a plurality of tab connections, each of which includes a first portion (i.e., an uncoated area extending from the edge of the current collector) and a second portion, with the first portion electrically connected to the second portion. Rather than directly electrically connecting the first portion to the tab, the second portion is placed on the surface of the first portion, a tab connection is formed, and the tab is welded to the tab through the tab connection. In this way, when manufacturing the pole pieces for an electrochemical device, the tab connection is not directly formed on the first portion, thereby reducing the width of the first portion and improving the problem of wrinkles occurring during cold rolling. Meanwhile, because the first portion (i.e., the uncoated area extending from the edge of the current collector) is not stretched before cold rolling the pole pieces, the problem of wrinkles occurring in the cathode pieces when cold rolling the cathode pieces thereafter is also improved. Furthermore, since there is no need to stretch the first portion of the pole piece (i.e., the uncoated area extending from the edge of the current collector), the cold rolling tension of the pole piece is reduced, which solves the problem of the pole piece being prone to breakage during the cold rolling process, thereby improving the yield of electrochemical devices.

[0055] Preferably, in this embodiment, the first portion 131 and the second portion 132 of the tab connection portion 13 of the pole piece may be made of a conductive foil material.

[0056] Preferably, there is a gap between the second portion 132 and the active material layer 12 to prevent the thickness of the manufactured electrochemical device from becoming too thick. Furthermore, since ions can pass through the separator and the active material layer but cannot pass through the second portion 132 (which, as described below, may be a conductive foil material, such as an aluminum-plated foil material), the gap between the second portion and the active material layer 12 prevents the second portion 132 from being sandwiched between the active material layer 12 (including the cathode active material) of the cathode piece 1 and the anode active material of the anode piece 2, which would hinder ion transmission between the cathode and the anode.

[0057] Furthermore, the second side of the first portion 131 is located between the first side of the second portion 132 and the second side of the second portion 132, which means that the second portion 132 may be an extension of the first portion 131.

[0058] Preferably, the electrochemical device herein further includes a case and a tab 4 extending from the case, the tab 4 being electrically connected to the second portion 132 of the pole piece by welding.

[0059] In any embodiment of the present application, when the electrode piece is a cathode piece 1, tab 4 is understood to be a cathode tab, active material layer 12 is a cathode active material layer, and current collector 11 is a cathode current collector, which can be understood specifically with reference to Figures 4A, 4B, and 4C. When the electrode piece 4 is a cathode piece, tab 4 is an anode tab, active material layer 12 is a cathode active material layer, and current collector 11 is a cathode current collector, which can be understood specifically with reference to Figure 4D.

[0060] The anode piece 2 of this embodiment may be any suitable anode piece in the related art. Alternatively, the anode piece 2 may be the anode piece of the present application. For example, the anode piece 2 may be provided with an anode active material layer (e.g., the anode active material layer may include a graphite material, a silicon-based material, etc.), the anode piece 2 may include an anode current collector, which may include a copper material, and the anode piece 2 may further be electrically connected to an anode tab. Of course, these are merely examples for ease of understanding, and this embodiment is not specifically limited. The anode tab and the cathode tab of the electrochemical device 10 of this embodiment may be located on the same side of the electrochemical device 10 or on different sides of the electrochemical device 10.

[0061] The electrochemical device 10 of the present embodiment will be briefly described below with reference to the fabrication of pole pieces of electrochemical devices in the related art, but it will be understood that this is merely for the purpose of facilitating understanding of the present application and does not constitute any limitation on the present embodiment.

[0062] FIG. 2 shows the manufacturing process of a cathode piece 1' for an electrochemical device in the related art. In this example, the active material layer and insulating layer of the cathode piece are coating layers applied to a current collector. Referring to structure A1 in FIG. 2, structure A1 is actually a plurality of cathode pieces that have not undergone further processing. (Simply put, structure A1 is divided into four cathode pieces 1' by cutting it along dashed line a1, then along dashed lines a2 and a3. This process will be described in detail later.) Structure A1 is obtained by applying active material layer 12' and insulating layer 13' to current collector 11', and structure A1 is then cold-rolled. (For example, a stepped roller (i.e., a special cold-rolling roller) that fits structure A1 may be used. When using stepped rollers, different sizes of stepped rollers must be designed to fit each different size of structure A1. For specific details, please refer to the related art of cold-rolling pole pieces using stepped rollers, and a description will not be repeated here.) During the cold rolling process, the thickness of the uncoated edge area 14' of the current collector 11' differs from the degree of deformation of the coated area (i.e., the insulating layer 13' and the active material layer 12'). This makes the structure A1 prone to wrinkling during the cold rolling process, which in turn makes the cathode piece 1' manufactured thereafter prone to wrinkling. For this reason, the uncoated edge area 14' is typically stretched to make the deformation consistent during the cold rolling process, thereby preventing wrinkling in the cathode piece when the structure A1 is subsequently cold rolled. After the stretching and cold rolling steps are completed, the cold-rolled structure A1 is cut along the dashed line a1 (e.g., the cutting method can be laser cutting) to obtain two structures A2 (each structure A2 corresponds to two uncut cathode pieces 1'). Then, both sides of the two structures A2 near the edge uncoated areas 14' are die-cut to obtain two structures A3 (each structure A3 corresponds to two die-cut cathode pieces 1').The two structures A3 are then cut along the dashed lines a2 and a3 (for example, the cutting method may be laser cutting) to obtain four cathode pieces 1' shown in FIG. 2, each of which has a plurality of tab pull-out structures 15' for pulling out tabs, which are formed by die-cutting the edge uncoated areas 14'.In this example, the tab lead structure 15' is trapezoidal, but this is merely an example. When fabricating an electrochemical device using the finally obtained cathode piece 1', the cathode piece 1' is wound with a separator, an anode piece, etc. to assemble a plurality of tab lead structures 15', and the assembled tab lead structures 15' are electrically connected to the cathode tabs (for example, by welding). Finally, the electrochemical device is fabricated.

[0063] Accordingly, the electrochemical device 10 in the present embodiment will be briefly described with reference to the fabrication of the pole pieces of the electrochemical device 10 in the present embodiment, but it will be understood that this is merely for the purpose of facilitating understanding of the present application and does not constitute any limitation on the present embodiment.

[0064] 3A shows the manufacturing process of a pole piece of the electrochemical device 10 of this embodiment (for example, the pole piece is a cathode piece 1 in FIGS. 3A and 3B), and FIG. 3B is an enlarged schematic view of T in FIG. 3A. In the example shown in FIG. 3A, the active material layer 12 and insulating layer 14 of the cathode piece 1 are each applied to a current collector 11, and a first portion 131 extends from the current collector 11. Referring to structure B1 in FIG. 3A, structure B1 is actually a plurality of cathode pieces 1 that have not been further processed (simply put, structure B1 is divided into four cathode pieces 1 by cutting along dashed line b1 and then along dashed lines b2 and b3. This process will be described in detail later). The active material layer 12 and the insulating layer 14 are applied to the current collector 11 to obtain the structure B1, which is then cold-rolled (the cold-rolling embodiment can be understood with reference to the related art of cold-rolling a pole piece with a cold rolling roller, and will not be described again here). Comparing the structure B1 in Fig. 3A with the structure A1 in Fig. 2, it can be seen that the width of the uncoated edge area of ​​the current collector 11 that was not die-cut in the structure B1 in Fig. 3A is obviously smaller than that of the structure A1 in Fig. 2 because there is no need to stretch the uncoated edge area of ​​the structure B1 (the uncoated edge area is actually the first portion 131 before die-cutting) before cold-rolling. After the cold-rolling step is completed, the cold-rolled structure B1 is cut along the dashed line b1 (for example, the cutting method can be laser cutting technology) to obtain two structures B2. A second portion 132 is welded to each of the uncoated areas (i.e., the first portion) extending from the edges on both sides of the structure B2, and the welding is completed to obtain two structures B3 (each structure B3 corresponds to two undie-cut cathode pieces 1). Then, the two structures B3 are die-cut on both sides near the second portion to obtain two structures B4 (each structure B4 corresponds to two die-cut cathode pieces 1, and in this case, the cathode pieces 1 have multiple tab connection portions 13). The two structures B4 are then cut along the dashed lines b2 and b3 (for example, the cutting method can be laser cutting technology) to obtain four cathode pieces 1 shown in FIG. 3A (the structure can also be further understood with reference to FIG. 3B).Thereafter, when the electrochemical device 10 is fabricated using the finally obtained cathode piece 1, the cathode piece 1 is wound together with the separator 3, the anode piece 2, etc., to collect the plurality of die-cut second portions 132, and the collected second portions 132 are electrically connected (for example, electrically connected by welding) to the tab 4 (here, the cathode tab). Finally, the electrochemical device 10 is fabricated.

[0065] In this embodiment, since there is no need to stretch the structure B1 (i.e., the plurality of cathode pieces 1 that have not been further processed), cold rolling using a stepped roller is not necessary. In this case, there is no need to design stepped rollers of different sizes to accommodate each of the different sized structures B1. In this way, the service life of the cold rolling rollers is improved, there is no need to frequently replace the cold rolling rollers, and the cost of cold rolling is reduced.

[0066] Preferably, the first portion 131 is a conductive foil material, and the resistance R per square millimeter of the conductive foil material (i.e., the first portion 131) satisfies R<20 mΩ, thus making the conductive performance of the first portion 131 good and meeting the use needs of the electrochemical device 10.

[0067] As mentioned above, the current collector 11 and the tab connection portion 13 may be made of a conductive foil material, for example, the resistance per square millimeter of the conductive foil material of the current collector 11 and the tab connection portion 13 is less than 20 mΩ, thus making the conductive performance of the current collector 11 and the tab connection portion 13 good and meeting the use needs of the electrochemical device 10.

[0068] Preferably, in this embodiment, the first part 131 and the second part 132 are electrically connected by welding, and the tab 4 is electrically connected to the second part 132. The second part 132 may be a conductive foil material, and preferably, the resistance R per square millimeter of the second part 132 satisfies R<20 mΩ, so that the conductive performance of the second part 132 is good and meets the usage needs of the electrochemical device 10.

[0069] Preferably, when measuring the resistance R per square millimeter of the first portion 131 or the second portion 132 of the fabricated electrochemical device 10, the electrochemical device 10 is disassembled to obtain a clean portion of the first portion 131 or the second portion 132 (i.e., a portion where no insulating material or active material is present) and measure the resistance using a resistance measuring device. If this is not possible, the insulating material or active material attached to the first portion 131 or the second portion 132 is washed with an organic solvent such as alcohol, and the clean portion after washing is obtained and measured using a resistance measuring device, or other methods may be used for measurement, and are not limited thereto.

[0070] Although the first portion 131 and / or the second portion 132 are made of a conductive foil, the present embodiment does not limit the specific material of the conductive foil, and any material may be used that ensures electrical conductivity and structural strength, such as at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil. Such conductive foil ensures the electrical conductivity of the first portion 131 and / or the second portion 132 of the electrode piece (especially the cathode piece 1) and meets the requirements of the electrochemical device 10.

[0071] Preferably, when the conductive foil material is an aluminum-plated foil material, the aluminum-plated foil material includes at least one of a foil material formed by aluminum plating the surface of a thin polypropylene film and a foil material formed by aluminum plating the surface of a thin polyethylene terephthalate film. These types of conductive foil materials ensure the conductive performance of the first portion 131 and / or the second portion 132 of the electrode piece (especially the cathode piece 1) and meet the usage needs of the electrochemical device 10.

[0072] Preferably, the first portion 131 and the second portion 132 of the present invention may be made of the same conductive foil material, or may be made of different conductive foil materials, and there is no limitation here.

[0073] Preferably, the thickness L of the second portion 132 satisfies the range 4 μm≦L≦25 μm. If the thickness of the second portion 132 is too thin, the manufacturing process for the pole piece (e.g., cathode piece 1) becomes difficult, increasing costs. Furthermore, the thickness is too thin, resulting in reduced strength, making it difficult to meet the structural strength requirements of the pole piece (e.g., cathode piece 1) and the second portion 132. On the other hand, if the thickness of the second portion 132 is too thick, material costs increase and the energy density efficiency of the electrochemical device 19 decreases. In this embodiment, the thickness L satisfies the above range (i.e., 4 μm≦L≦25 μm), which effectively avoids the disadvantages of the second portion 132 being too thin and also avoids the disadvantages of the second portion 132 being too thick. This satisfies the usage needs of the electrochemical device 10 and improves the yield rate of the electrochemical device 10.

[0074] Preferably, 4 μm≦L≦25 μm, and the thickness L of the second portion 132 satisfies 5 μm≦L≦20 μm. This preferred numerical range can better avoid the drawback of the second portion 132 being too thin, and can also better avoid the drawback of the second portion 132 being too thick. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0075] Within the above numerical range, the thickness L of the second portion 132 may be an appropriate value selected as needed. For example, when 5 μm≦L≦20 μm is taken as an example, the thickness L may be 5 μm, 7 μm, 10 μm, 15 μm, 18 μm, 20 μm, etc., and is not limited thereto.

[0076] Preferably, when measuring the thickness L of the second part of the manufactured electrochemical device 10, the electrochemical device 10 is disassembled to obtain the unwelded portion between the first weld mark 61 and the second weld mark 62 of the second part 132, and the thickness L may be measured using a micrometer or a millimeter meter, or by other methods, and the method is not limited thereto.

[0077] Preferably, to ensure the strength of the second portion 132, the breaking strength S of the second portion 132 satisfies the range 80 MPa≦S≦800 MPa. If the breaking strength of the second portion 132 is too low, it will be prone to breakage during the manufacturing process, making the manufacturing process of the pole piece (e.g., cathode piece 1) more difficult and increasing costs. If the breaking strength is too low, it will be difficult to meet the structural strength requirements of the pole piece (e.g., cathode piece 1) and the second portion. On the other hand, if the breaking strength S of the second portion is too high, the manufacturing process of the pole piece (e.g., cathode piece 1) will be more difficult and increasing costs. By ensuring that the breaking strength S of this embodiment satisfies the above range (i.e., 80 MPa≦S≦800 MPa), the disadvantages of the second portion having too low a breaking strength and the disadvantages of the second portion having too high a breaking strength can be effectively avoided. This meets the needs of the electrochemical device 10 and improves the yield rate of the electrochemical device 10.

[0078] Preferably, the breaking strength S of the second portion 132 satisfies 80 MPa≦S≦800 MPa, and 100 MPa≦S≦450 MPa. This preferred range of values ​​can better avoid the drawback of the second portion having an excessively low breaking strength and the drawback of the second portion having an excessively high breaking strength. This satisfies the needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0079] Within the above numerical range, the breaking strength S of the second portion 132 may be an appropriate value selected as needed. For example, assuming that 100 MPa≦S≦450 MPa, the breaking strength S may be 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, etc., and is not specifically limited here.

[0080] Preferably, the thickness of the first portion 131 extending from the current collector 11 of the pole piece may have the same numerical range as the thickness of the second portion described above, i.e., the thickness of the first portion 131 may have a numerical range of 4 μm to 25 μm, more preferably 5 μm to 20 μm, and the breaking strength of the first portion 131 may have the same numerical range as the breaking strength of the second portion described above, i.e., the breaking strength of the first portion 131 may have a numerical range of 80 MPa to 800 MPa, more preferably 100 MPa to 450 MPa.

[0081] When the first portion 131 and the second portion 132 are both made of conductive foil material, the thickness of the first portion 131 and the thickness of the second portion 132 may be the same or different, and the breaking strength of the first portion 131 and the breaking strength of the second portion 132 may be the same or different.

[0082] Preferably, when the current collector 11 of the pole piece is made of a conductive foil material, it may be made of the same material as the first portion 131 of the tab connection portion 13, and the thickness of the first portion 131 may satisfy the same numerical range. That is, the conductive foil material of the current collector 11 and / or the first portion 131 of the tab connection portion 13 may be at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil. The aluminum-plated foil material includes at least one of foil material formed by aluminum plating on the surface of a polypropylene thin film and foil material formed by aluminum plating on the surface of a polyethylene terephthalate thin film. The thickness of the current collector 11 ranges from 4 μm to 25 μm, preferably from 5 μm to 20 μm, and the breaking strength of the current collector 11 ranges from 80 MPa to 800 MPa, preferably from 100 MPa to 450 MPa, thereby meeting the corresponding usage needs of the electrochemical device 10.

[0083] In the present embodiment, when the electrode piece is a cathode piece 1, the active material layer 12 disposed on the current collector 11 includes a cathode active material, and the type of the cathode active material is not limited, and may be, for example, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, etc.

[0084] In some embodiments, when the electrode piece is a cathode piece 1, the cathode piece 1 further includes an insulating layer 14, which is disposed on the surface of the current collector 11. When the electrode piece is unfolded, the active material layer 12 and the insulating layer 14 are aligned in the width direction Y of the electrode piece. The insulating layer 14 can insulate and separate the current collector 11 of the cathode piece 1 from the anode piece 2, and can effectively prevent short circuits from occurring between the cathode piece 1 and the anode piece 2.

[0085] In this embodiment, the material of the insulating layer 14 is not specifically limited and may be, for example, at least one of alumina and silicon oxide. The insulating layer 14 made of such a material insulates and separates the current collector 11 of the cathode piece 1 from the anode piece 2, thereby effectively preventing short circuits from occurring between the cathode piece 1 and the anode piece 2. Preferably, the insulating layer 14 is a coating layer (e.g., an alumina coating layer, a silicon oxide coating layer, etc.).

[0086] In the present embodiment, along the width direction Y of the pole piece, the insulating layer 14 includes a first side close to the active material layer 12 and a second side away from the active material layer 12, and along the width direction Y of the pole piece, the width W3 of the insulating layer 14 satisfies 0.5 mm≦W3≦5 mm.

[0087] 4A, 4B, and 4C are schematic diagrams of several examples of the configuration of the electrode piece cathode piece 1, in which the width direction Y of the electrode piece is the width direction of the current collector 11, and therefore the width W3 of the insulating layer 14 may be understood as the distance between the first side of the insulating layer 14 and the second side of the insulating layer 14. In this embodiment, the insulating layer 14 having a width within this range is used to effectively insulate and isolate the current collector 11 of the cathode piece 1 and the anode piece 2, preventing short circuits between them, and meeting the needs of the electrochemical device 10 without increasing extra costs.

[0088] In the present embodiment, the first portion 131 and the second portion 132 are welded together. In some preferred embodiments, the weld tensile strength F between the first portion 131 and the second portion 132 satisfies 5N≦F≦1000N. If the weld tensile strength F between the first portion 131 and the second portion 132 is too small, the second portion 132 is likely to come off from the first portion 131 during use of the electrochemical device 10. On the other hand, if the weld tensile strength F between the first portion 131 and the second portion 132 is too large, it will affect the cost of manufacturing the electrochemical device 10. By ensuring that the weld tensile strength F satisfies the above numerical range (i.e., 5N≦F≦1000N) in the present embodiment, the disadvantage of a weld tensile strength F between the first portion 131 and the second portion 132 being too small and the disadvantage of a weld tensile strength F between the first portion 131 and the second portion 132 being too large can be effectively avoided. This satisfies the needs of the electrochemical device 10 and improves the yield of the electrochemical device 10 .

[0089] Preferably, 5N≦F≦1000N, and the weld tensile strength F between the first portion 131 and the second portion 132 satisfies 10N≦F≦500N. This preferred numerical range can better avoid the drawback of the weld tensile strength between the first portion 131 and the second portion 132 being too small, and can also better avoid the drawback of the weld tensile strength between the first portion 131 and the second portion 132 being too large. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0090] Within the above numerical range, the weld tensile strength F may be an appropriate value selected as needed. For example, assuming that 10N≦F≦500N, the weld tensile strength F may be 10N, 50N, 100N, 200N, 300N, 350N, 400N, 500N, etc., and is not specifically limited here.

[0091] The method for measuring the weld tensile strength F can be found in the related art and is not limited thereto. For example, an exemplary method for measuring the weld tensile strength F may be as follows: A sample of the welded first portion 131 and second portion 132 is placed in a tensile machine, and the left and right clips clamp the first portion 131 and the second portion 132, respectively, along the width direction Y of the pole piece. The left and right clips are spaced apart by an appropriate distance (e.g., 20 mm), and the welded area (e.g., the first weld mark 61 described below) is positioned between the left and right clips. During the measurement process, the left and right clips are kept out of contact with the welded area (e.g., the first weld mark 61 described below). Then, while the left clip is fixed, the right clip is pulled away from the left clip at an appropriate speed (e.g., 1 mm / s) to check whether the welded area is broken after tearing. If the welded area is broken, the corresponding weld tensile strength F is checked. If the welded area is not broken, the sample is replaced and remeasured. Of course, this is merely an example and is not a limitation on the embodiments.

[0092] In this embodiment, the first portion 131 and the second portion 132 may be welded by any welding method, such as ultrasonic seam welding. FIG. 5 illustrates an ultrasonic seam welding method. The first portion 131 and the second portion 132 are placed on a seam welding holder 71 with a partial overlap, and a seam welding head 72 is positioned above the seam welding holder 71 and the second portion 132 and the first portion 131 to perform ultrasonic welding. During the welding process, the seam welding head 72 generates high-frequency ultrasonic waves on the second portion 132 and the first portion 131. When the seam welding head 72 applies pressure to the second portion 132 and the first portion 131, the contacting surfaces of the second portion 132 and the first portion 131 rub against each other, generating thermal energy. This thermal energy melts the welded portion of the second portion 132 and the first portion 131, thereby finally welding the second portion 132 and the first portion 131 together. Of course, this is merely an example of the present invention and does not limit the present invention in any way.

[0093] In some preferred embodiments, in the electrochemical device 10, the first portion 131 and the second portion 132 are electrically connected by welding, and a first weld mark 61 is formed when the first portion 131 and the second portion 132 are welded together. Along the width direction Y of the pole piece, the first weld mark 61 includes a first side close to the active material layer 12 and a second side away from the active material layer 12, the second side of the first weld mark 61 is located in the second portion 132, and there is a gap between the first weld mark 61 and the active material layer 12.

[0094] Specifically, the first part 131 and the second part 132 are electrically connected by welding, which ensures the stability of the electrical connection between the second part 132 and the first part 131, and the second side of the first weld mark 61 being located on the second part 132 ensures a stable welded connection between the second part 132 and the first part 131.

[0095] In the present 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 composed of multiple sub-weld marks 611, with a gap between two adjacent sub-weld marks 611. The sub-weld marks 611 may be composed of multiple small weld joints of regular or irregular shapes. For example, the small weld joints may be shaped like a circle, a rectangle, or another polygon. Preferably, the shape of the sub-weld mark 611 formed by a series of small weld joints may be a polygon such as a parallelogram, a rectangle (which may be a square), a triangle, or another irregular shape. For example, as shown in FIG. 6, the shape of the sub-weld mark 611 is a rectangle composed of small weld joints, and the small weld joints are rectangular. Alternatively, as shown in FIG. 7, each sub-weld mark 611 may be a single weld mark. This is not limited thereto.

[0096] 8 and 9, the first weld mark 61 may be a continuous weld mark. The continuous weld mark may be an integral weld mark (integral weld marks can be understood by referring to FIG. 9, and therefore will not be described again here). Alternatively, the continuous weld mark may be composed of small welded joints including a plurality of regular or irregular shapes, for example, the small welded joints may be circular, rectangular, or other polygonal shapes (which can be understood by referring to FIG. 8, and therefore will not be described again here). This embodiment is not limited thereto.

[0097] Preferably, in the embodiment of the present application, in the case where the above-mentioned "first weld mark 61 is composed of a plurality of sub-weld marks 611, and there is a gap between two adjacent sub-weld marks 611," the weld mark area ratio P is greater than 20%, and the weld mark area ratio P = Sy / Sz, where Sy is the total area of ​​all the sub-weld marks 611 of the first weld mark 61, and Sz is the total area of ​​the welded region (i.e., the total area of ​​all the sub-weld marks 611 and the area of ​​the gap region between all the sub-weld marks 611).

[0098] Specifically, Sy and Sz can be understood with reference to the case where the sub-weld mark 611 in Figure 7 is an integral weld mark. Here, Sz = h*W5, Sy = s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8, where s1, s2, s3, s4, s5, s6, s7, and s8 are the areas of the sub-weld marks, and the weld mark area ratio P = Sy / Sz = (s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8) / (h*W5) > 20%. Also, as described below, W5 is the distance between the first side of the first weld mark 61 and the second side of the first weld mark 61, i.e., the width of the first weld mark 61.

[0099] Similarly, since each sub-weld spot 611 in Fig. 6 is composed of multiple small weld joints with regular or irregular shapes, Sz = h * W5, and Sy is equal to the total area of ​​all the small weld joints. The explanation of Fig. 7 can be understood, so it will not be repeated.

[0100] Of course, in other embodiments, the area ratio P of the welded area may be less than 20% to meet the requirements of the electrochemical device 10, and is not particularly limited herein.

[0101] 4A, 4B, 4C, and 4D, the width W5 of the first weld mark 61 along the width direction Y of the pole piece satisfies 0.1 mm≦W5≦10 mm. It should be understood that the width W5 of the first weld mark 61 is the distance between the first side of the first weld mark 61 and the second side of the first weld mark 61 along the width direction Y of the pole piece. The width of the first weld mark 61 (i.e., W5) can also be understood with reference to FIGS. 6, 7, 8, and 9.

[0102] If the width of the first weld mark 61 is too small (i.e., W5<0.1 mm), it is difficult to ensure that the weld tensile strength between the first portion 131 and the second portion 132 meets the requirements, resulting in the disadvantage of the weld tensile strength F being too small. On the other hand, if the width of the first weld mark 61 is too large (i.e., W5>10 mm), it is difficult to assemble the die-cut second portion 132 after the first portion 131 (i.e., the uncoated area extending from the edge of the current collector 11) and the second portion 132 of the pole piece (e.g., cathode piece 1) are die-cut, resulting in increased costs. By ensuring that the width of the first weld mark 61 (i.e., W5) satisfies the above numerical range (0.1 mm≦W5≦10 mm), the disadvantage of the first weld mark 61 being too small and the disadvantage of the first weld mark 61 being too large can be avoided. This satisfies the needs of the electrochemical device 10 and improves the yield of the electrochemical device 10 .

[0103] It should be noted that the pole pieces shown in Figures 4A, 4B, and 4C are cathode pieces 1, and the pole piece shown in Figure 4D is anode piece 2. It should be understood that these are merely for the purpose of explaining the pole pieces of the electrochemical device of this embodiment and do not constitute any limitation on the present application.

[0104] Within the above numerical range, the width W5 of the first weld mark 61 may be an appropriate value selected as needed. For example, W5 may be 0.1 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, etc., assuming that 0.1 mm≦W5≦10 mm. This is not a limitation.

[0105] In some preferred embodiments, referring to Figures 4A, 4B, 4C, and 4D, when the first side of the first weld mark 61 is located on the first portion 131, the distance W6 between the first side of the first weld mark 61 and the first side of the second portion 132 satisfies 0 mm ≦ W6 ≦ 5 mm, or when the first side of the first weld mark 61 is located on the surface of the second portion 132, the distance W6 between the first side of the first weld mark 61 and the first side of the second portion 132 satisfies 0 mm ≦ W6 ≦ 30 mm.

[0106] Specifically, FIG. 4B shows an example in which the first side of the first weld mark 61 is located on the first portion 131 (note that in FIG. 4B the first side of the first weld mark 61 does not contact the first portion 131 and there is a gap between them, but in the form actually shown in FIG. 4B , the first side of the first weld mark 61 and the first portion 131 are in direct contact with each other and are located on the first portion 131, thereby welding the second portion 132 to the first portion 131. This structure is shown here for ease of understanding and is not a limitation on the present application), and when the first side of the first weld mark 61 is located on the first portion 131, this corresponds to the first side of the first weld mark 61 exceeding the first side of the second portion 132 along the opposite direction of the width direction Y of the pole piece, and the first weld mark 61 covers the first side of the second portion 132. 4A, 4C, and 4D, when the first side of the first weld mark 61 is located on the surface of the second portion 132, it corresponds to the first side of the first weld mark 61 exceeding the first side of the second portion 132 along the width direction Y of the pole piece, and the first side of the second portion 132 is not covered by the first weld mark 61, and the first side of the second portion 132 may be in an unconstrained state, that is, the first side of the second portion 132 is not welded to the first portion 131. The pole piece shown in FIGS. 4A, 4B, and 4C is the cathode piece 1, and the pole piece shown in FIG. 4D is the anode piece 2, which is understood to be merely for the purpose of describing the pole piece of the electrochemical device of this embodiment and does not constitute any limitation on the present application.

[0107] If the first side of the first weld mark 61 extends beyond the first side of the second portion 132 in the opposite direction of the width direction Y of the pole piece (for example, W6 > 5 mm when the first side of the first weld mark 61 is located on the first portion 131), there will be many areas where active material (e.g., cathode active material) is not present, and the spatial occupation rate of the areas where energy cannot be supplied will be large, resulting in serious loss of energy density, which will affect the subsequent electrical connection between tab 4 (e.g., cathode tab) and the second portion 132 (for example, electrically connecting tab 4 (e.g., cathode tab) and the second portion 132 by welding), affecting the assembly of the die-cut second portion 132, and the second portion 132 will be easily damaged in this process, which will affect the electrical performance of the final 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 second portion 132 along the width direction Y of the pole piece (for example, if W6>30 mm when the first side of the first weld mark is located on the surface of the second portion 132), the second portion 132 may be too wide in an unconstrained state, which will affect the die cutting when manufacturing the pole piece (e.g., cathode piece 1), making the process more difficult and affecting the yield rate of the electrochemical device 10.

[0108] In the present embodiment, by using such a numerical range of W6, it is possible to avoid the drawback that occurs when the first side of the first weld mark 61 exceeds the first side of the second portion 132 in the direction opposite to the width direction Y of the pole piece, and also to avoid the drawback that occurs when the first side of the first weld mark 61 exceeds the first side of the second portion 132 in the width direction of the pole piece, thereby meeting the usage needs of the electrochemical device 10 and improving the yield rate of the electrochemical device 10.

[0109] Preferably, in addition to the above numerical range, when the first side of the first weld mark 61 is located on the first portion 131, the distance W6 between the first side of the first weld mark 61 and the first side of the second portion 132 satisfies 0 mm≦W6≦3 mm; or when the first side of the first weld mark 61 is located on the surface of the second portion 132, the distance W6 between the first side of the first weld mark 61 and the first side of the second portion 132 satisfies 0 mm≦W6≦10 mm. This preferable numerical range further avoids the drawback that occurs when the first side of the first weld mark 61 extends too far beyond the first side of the second portion 132 in the direction opposite to the width direction Y of the pole piece, and further avoids the drawback that occurs when the first side of the first weld mark 61 extends too far beyond the first side of the second portion 132 in the width direction Y of the pole piece. This meets the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0110] Within the above numerical range, W6 may be an appropriate value selected as needed. For example, when the first side of the first weld mark 61 is located on the first portion 131, and 0 mm≦W6≦3 mm is assumed, W6 may be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3.0 mm, etc., and is not specifically limited thereto. For example, when the first side of the first weld mark 61 is located on the surface of the second portion 132, and 0 mm≦W6≦10 mm is assumed, W6 may be 0 mm, 1 mm, 3 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., and is not specifically limited thereto.

[0111] In some preferred embodiments, referring to Figures 4A, 4B, 4C, and 4D, when there is an overlapping portion between the first projection of the second side of the first weld mark 61 onto the second portion 132 of the first portion 131 and the second projection of the first portion 131 onto the second portion 132, the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 141 satisfies 0 mm ≦ W7 ≦ 15 mm, or when there is no overlapping portion between the first projection of the second side of the first weld mark 161 onto the second portion 132 of the first portion 141 and the second projection of the first portion 141 onto the second portion 132, the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 131 satisfies 0 mm ≦ W7 ≦ 7 mm.

[0112] It is easy to understand that the first projection may be a projection onto the second part 132 along the thickness direction of the second part 132 on the second side of the first weld mark 61, and the second projection may be a projection onto the second part 132 along the thickness direction of the second part 132 of the first part 131.

[0113] 4B and 4C, when there is an overlap between the first projection and the second projection, this corresponds to the second side of the first portion 131 extending beyond the second side of the first weld mark 61 along the width direction Y of the pole piece, and the second side of the first portion 131 is in an unconstrained state, i.e., the second side of the first portion 131 is not welded to the second portion 132. With reference to FIGS. 4A and 4D, when there is no overlap between the first projection and the second projection, this corresponds to the second side of the first portion 131 not extending beyond the second side of the first weld mark 61 along the width direction Y of the pole piece, and the second side of the first portion 131 is welded to the second portion 132. The pole piece shown in FIGS. 4A, 4B, and 4C is the cathode piece 1, and the pole piece shown in FIG. 4D is the anode piece 2. It should be understood that this is merely for the purpose of describing the pole piece of the electrochemical device of this embodiment and does not constitute any limitation on the present application.

[0114] When there is an overlapping portion between the first projection and the second projection, if the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 131 is too large (for example, W7 > 15 mm when there is an overlapping portion between the first projection and the second projection), that is, if the second side of the first portion 131 extends too far beyond the second side of the first weld mark 61 along the width direction Y of the pole piece, the first portion 131 may be too wide in an unconstrained state, which will affect the die cutting when manufacturing the pole piece (for example, the cathode piece 1), making the process more difficult and affecting the yield rate of the electrochemical device 10. On the other hand, when there is no overlap between the first projection and the second projection, if the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 131 is too large (for example, W7 > 7 mm when there is no overlap between the first projection and the second projection), that is, if the second side of the first weld mark 61 extends too far beyond the second side of the first portion 131 along the width direction Y of the pole piece, there will be a serious loss of energy density, which will affect the subsequent electrical connection between the tab 4 (e.g., the cathode tab) and the second portion 132 (for example, the electrical connection between the tab 4 (e.g., the cathode tab) and the second portion 132 by welding), and will affect the assembly of the die-cut second portion 132, and the second portion 132 will also be easily damaged in this process, which will affect the electrical performance of the final electrochemical device 10.

[0115] In the present embodiment, by using such a numerical range of W7, it is possible to avoid the drawback that occurs when the second side of the first portion 131 exceeds the second side of the first weld mark 61 in the width direction Y of the pole piece, and also to avoid the drawback that occurs when the second side of the first weld mark 61 exceeds the second side of the first portion 131 in the width direction Y of the pole piece, thereby satisfying the usage needs of the electrochemical device 10 and improving the yield rate of the electrochemical device 10.

[0116] Preferably, within the above numerical range, when there is an overlapping portion between the first projection onto the second portion on the second side of the first weld mark 61 and the second projection onto the second portion 132 of the first portion 131, the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 141 satisfies 0 mm ≦ W7 ≦ 10 mm. Or, when there is no overlapping portion between the first projection onto the second portion 132 on the second side of the first weld mark 161 and the second projection onto the second portion 132 of the first portion 141, the distance W7 between the second side of the first weld mark 61 and the second side of the first portion 131 satisfies 0 mm ≦ W7 ≦ 3 mm. In this preferred numerical range, the drawbacks when the second side of the first portion 131 extends too far beyond the second side of the first weld mark 61 along the width direction of the pole piece can be further avoided, and the drawbacks when the second side of the first weld mark 61 extends too far beyond the second side of the first portion 131 along the width direction of the pole piece can be further avoided. Thereby, the usage needs of the electrochemical device 10 are satisfied and the production yield rate of the electrochemical device 10 is improved.

[0117] Within the above numerical range, W7 may be an appropriate value selected as needed. For example, when there is an overlapping portion between the first projection and the second projection, taking 0 mm ≦ W7 ≦ 10 mm as an example, W7 may be 0 mm, 1 mm, 3 mm, 5 mm, 8 mm, 9 mm, 10 mm, etc., and is not specifically limited here. For example, when there is no overlapping portion between the first projection and the second projection, taking 0 mm ≦ W7 ≦ 3 mm as an example, W7 may be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., and is not specifically limited here.

[0118] In some preferred embodiments, referring to FIGS. 4A, 4B, 4C, and 4D, the electrochemical device 10 further includes a case and a tab extending from the case. The tab 4 is electrically connected to the second portion 132 by welding. A second weld mark 62 is formed on the second portion 132. Along the width direction Y of the pole piece, the second weld mark 62 includes a first side close to the active material layer 12 and a second side away from the active material layer 12. The distance W8 between the second side of the first weld mark 61 and the first side of the second weld mark 62 satisfies 0 mm < W8 ≦ 10 mm.

[0119] The present application does not limit the specific welding process when the tab 4 and the second portion 132 are welded together; for example, the welding process may be a roll welding process, and the second weld mark 62 may be a roll welding process.

[0120] The pole pieces shown in Figures 4A, 4B, and 4C are cathode pieces 1, and the pole piece shown in Figure 4D is anode piece 2. It is understood that these are merely for the purpose of explaining the pole pieces of the electrochemical device of this embodiment and do not constitute any limitation on the present application.

[0121] In any embodiment of the present application, the pole piece of the electrochemical device 10 may be a cathode piece 1 and / or an anode piece 2. When the pole piece of the electrochemical device is a cathode piece 1, the tab 4 electrically connected to the second portion 132 of the cathode piece 1 by welding is a cathode tab, whereas when the pole piece of the electrochemical device is an anode piece 2, the tab 4 electrically connected to the second portion 132 of the anode piece 2 by welding is an anode tab.

[0122] Preferably, the case is configured so that the cathode piece 1, the separator 3, and the anode piece 2 are placed in the case, and the case can protect them. Preferably, for the soft pack cell, the case is made of a metal film, and the metal film may be a steel film, an aluminum film, or the like.

[0123] When the tab 4 (e.g., the cathode tab) is electrically connected to the second part 132 by welding, the second welding mark 62 formed on the second part 132 and the first welding mark 61 do not overlap. If they overlap, it will affect the welding effect between the tab 4 (e.g., the cathode tab) and the second part 132, and reduce the welding tensile strength of both. On the other hand, if the distance W8 between the second side of the first welding mark 61 and the first side of the second welding mark 62 is too large (e.g., when W8 > 10 mm), it is likely to affect the energy density of the electrochemical device 10. In this embodiment, such a numerical range of W8 is used to avoid the disadvantages when the second welding mark 62 and the first welding mark 61 overlap, and also avoid the disadvantages when the distance W8 between the second side of the first welding mark 61 and the first side of the second welding mark 62 is too large. Thereby, the usage needs of the electrochemical device 10 are met and the production yield rate of the electrochemical device 10 is improved.

[0124] In the above numerical range, W8 may be an appropriate value selected as needed. For example, taking 0 mm < W8 ≤ 10 mm as an example, W8 may be 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, etc., and no specific limitation is made here.

[0125] In the embodiment of the present application, the width of the second part 132 (referring to FIGS. 4A, 4B, 4C, and 4D, the width W1 of the second part 132 is the distance between the first side and the second side of the second part 132 along the width direction Y of the electrode tab) is not restricted, and it only needs to meet the demand of the electrochemical device 10. In some preferred embodiments, along the width direction Y of the electrode tab, the width W1 of the second part 132 satisfies 3 mm ≤ W1 ≤ 35 mm.

[0126] If the width of the second portion 132 is too small, it is difficult to weld the second portion 132 and the first portion 131 together during the fabrication of the electrochemical device 10. On the other hand, if the width of the second portion 132 is too large, the edge of the second portion 132 is likely to be indented during die-cutting during the fabrication of the pole piece (e.g., cathode piece 1), affecting the accuracy of the die-cutting. In particular, when performing die-cutting using laser cutting, the laser focus may be far away from the cutting surface, resulting in an incomplete cut. Furthermore, the second portion 132 may be easily broken unintentionally. By ensuring that the width of the second portion 132 in this embodiment satisfies the above-mentioned numerical range (i.e., 3 mm≦W1≦35 mm), the drawback of a narrow width of the second portion 132 is effectively avoided, and the drawback of a wide width of the second portion 132 is also effectively avoided. This meets the needs of the electrochemical device 10 and improves the yield rate of the electrochemical device 10.

[0127] It should be noted that the pole pieces shown in Figures 4A, 4B, and 4C are cathode pieces 1, and the pole piece shown in Figure 4D is anode piece 2. It should be understood that these are merely for the purpose of explaining the pole pieces of the electrochemical device of this embodiment and do not constitute any limitation on the present application.

[0128] Preferably, W1 satisfies 3 mm≦W1≦35 mm, and the width W1 of the second portion 132 along the width direction Y of the pole piece satisfies 5 mm≦W1≦25 mm. This preferred range of values ​​can further avoid the drawback of the second portion 132 being too small in width and can better avoid the drawback of the second portion 132 being too large in width, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0129] Within the above numerical range, the width W1 of the second portion 132 may be an appropriate value selected as needed. For example, W1 may be 5 mm, 10 mm, 15 mm, 18 mm, 20 mm, 23 mm, 25 mm, etc., assuming that 5 mm≦W1≦25 mm, and is not limited thereto.

[0130] In the present embodiment, the width (see FIGS. 4A, 4B, 4C, and 4D, the width W2 of the first portion 131, i.e., the distance between the first side of the first portion 131 and the second side of the first portion 131 along the width direction Y of the pole piece) of the first portion 131 extending from the current collector 11 (i.e., the first portion 131 of the tab connection portion 13) is not limited as long as it meets the requirements of the electrochemical device 10. In some preferred embodiments, the width W2 of the first portion 131 along the width direction Y of the pole piece satisfies 0.5 mm≦W2≦20 mm.

[0131] If the width of the first portion 131 is too small, it is difficult to ensure a sufficient welding width during the fabrication of the electrochemical device 10, making it difficult to weld the second portion 132 and the first portion 131 together. On the other hand, if the width of the first portion 131 is too large, wrinkles are more likely to occur in the first portion 131 after cold rolling during the fabrication of the pole piece (e.g., cathode piece 1), which may affect the alignment of the second portion 132 welded to the die-cut first portion 131, resulting in increased energy density loss and increased costs. By ensuring that the width of the first portion 131 in this embodiment satisfies the above numerical range (i.e., 0.5 mm≦W2≦20 mm), the disadvantages of having a too small width of the first portion 131 and the disadvantages of having a too large width of the first portion 131 are both effectively avoided. This satisfies the needs of the electrochemical device 10 and improves the yield rate of the electrochemical device 10.

[0132] It should be noted that the pole pieces shown in Figures 4A, 4B, and 4C are cathode pieces 1, and the pole piece shown in Figure 4D is anode piece 2. It should be understood that these are merely for the purpose of explaining the pole pieces of the electrochemical device of this embodiment and do not constitute any limitation on the present application.

[0133] Preferably, 0.5 mm≦W2≦20 mm, and the width W2 of the first portion 131 along the width direction Y of the pole piece satisfies 1 mm≦W2≦10 mm. This preferred range of values ​​can further avoid the drawback of the first portion 131 being too small in width and can better avoid the drawback of the first portion 131 being too large in width. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0134] Within the above numerical range, the width of the first portion 131 (i.e., W2) may be an appropriate value selected as needed. For example, W2 may be 1 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., assuming that 1 mm≦W2≦10 mm, and is not limited thereto.

[0135] In some preferred embodiments, referring to Figures 4A, 4B, and 4C, along the width direction Y of the pole piece, the insulating layer 14 includes a first side close to the active material layer 12 and a second side away from the active material layer 12, and when the first side of the second portion 132 is located on the insulating layer 14, the distance W4 between the first side of the second portion 132 and the second side of the insulating layer 14 satisfies 0 mm≦W4≦8 mm; or when the first side of the second portion 132 is located on the surface of the first portion 131, the distance W4 between the first side of the second portion 132 and the second side of the insulating layer 14 satisfies 0 mm≦W4≦10 mm.

[0136] 4C , when the pole piece is a cathode piece 1 and the first side of the second portion 132 is located on the insulating layer 14, after the second portion 132 is welded to the first portion 131, the first end of the second portion 132 extends beyond the first side of the first portion 131 in the direction opposite to the width direction Y of the pole piece. If the distance W4 is too large (e.g., W4>8 mm), the thickness of the fabricated electrochemical device 10 is likely to be too large. Referring to FIGS. 4A and 4B , when the pole piece is a cathode piece 1 and the first side of the second portion 132 is located on the surface of the first portion 131, if the distance W4 between the first side of the second portion 132 and the second side of the insulating layer 14 is too large (e.g., W4>10 mm), the problem of the first portion 131 and the second portion 132 being folded back after welding cannot be effectively solved.

[0137] When W4 in this embodiment satisfies the above numerical range, it is possible to effectively avoid the drawback that occurs when the first end of the second portion 132 extends too far beyond the first side of the first portion 131 in the direction opposite to the pole piece width direction Y, and also to effectively avoid the drawback that occurs when W4 is too large because the first side of the second portion 132 is located at the first portion 131. This satisfies the usage needs of the electrochemical device 10 and improves the yield rate of the electrochemical device 10.

[0138] A preferred embodiment is one in which there is a gap between the first side of the second portion 132 and the insulating layer 14. Preferably, the first side of the second portion 132 is located on the surface of the first portion 131, and the gap W4 between the first side of the second portion 132 and the second side of the insulating layer 14 satisfies 0 mm≦W4≦5 mm. Within this preferred range, the first side of the second portion 132 is located on the first portion 131, further avoiding the drawbacks that would occur if W4 were too large. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0139] It should be understood that the above-described contents are merely preferred examples of the electrochemical device 10 in the embodiments of the present invention, and do not impose any limitations on the electrochemical device 10 in the embodiments of the present invention.

[0140] As can be seen from the above, in the electrochemical device provided herein, the pole pieces of the electrochemical device include multiple tab connections, each of which includes a first portion (i.e., an uncoated area extending from the edge of the current collector) and a second portion. The first portion is electrically connected to the second portion; rather than directly electrically connecting the first portion to the tab, the second portion is placed on the surface of the first portion, a tab connection is formed, and the tab is welded through the tab connection. In this way, when manufacturing the pole pieces of the electrochemical device, the tab connection is not directly formed on the first portion, thereby reducing the width of the first portion and improving the problem of wrinkles occurring during cold rolling. Meanwhile, because the first portion (i.e., the uncoated area extending from the edge of the current collector) is not stretched before cold rolling the pole pieces, the problem of wrinkles occurring in the cathode pieces when cold rolling the cathode pieces subsequently is also improved. In addition, since the first portion of the pole piece (i.e., the uncoated area extending from the edge of the current collector) is not pulled, the cold rolling tension of the pole piece is reduced, thereby alleviating the problem of the pole piece being prone to breakage during the cold rolling process, thereby improving the yield of electrochemical devices.

[0141] According to a second aspect of the present embodiment, with reference to the block diagram of FIG. 10, the present embodiment provides an electric power consuming device 20 including any one of the electrochemical devices 10 provided in the first aspect above.

[0142] Specifically, the electrochemical apparatus 10 can supply power to each electrical device in the power consumption equipment 20 .

[0143] The power consuming device 20 in the present embodiment includes the electrochemical device 10 described above, and since the yield of the electrochemical device 10 is high, the yield of the power consuming device 20 is also high.

[0144] The following description will be given with reference to several examples of actual electrochemical devices 10 in the present application examples and several comparative examples of electrochemical devices in the related art, and the beneficial effects of the electrochemical device 10 in the present application examples over the related art can be more clearly understood by comparing these examples and comparative examples. In these comparative examples and examples, the electrochemical device is exemplified as a lithium ion battery.

[0145] The list of relevant data is shown in Table 1 below. In Table 1, the electrochemical devices of Comparative Examples 1 and 2 have a general wound structure. In addition, in Examples 1 to 23 and Comparative Examples 3 to 4, compared to Comparative Examples 1 to 2, when manufacturing the cathode pieces, the uncoated area at the edge of the current collector is not stretched before cold rolling, and a second part is welded to the uncoated area (i.e., the first part) extending from the edge of the current collector, and a stepped roller is not used during the cold rolling process; all other parameters are the same.

[0146] JPEG2025531530000002.jpg111125

[0147] In Table 1 above, for ease of reading, in the W4 column, negative numbers indicate that the first side of the second portion 132 is located on the insulating layer 14 (for example, W4 in Table 1 is -2 mm, i.e., the first side of the second portion 132 is located on the insulating layer 14, and W4 = 2 mm), and positive numbers indicate that the first side of the second portion 132 is located on the surface of the first portion 131 (for example, W4 in Table 1 is 2 mm, i.e., the first side of the second portion 132 is located on the surface of the first portion 131, and W4 = 2 mm). In the W6 column, a negative number indicates that the first side of the first weld mark 61 is located on the first portion 131 (for example, W6 in Table 1 is -3 mm, i.e., the first side of the first weld mark 61 is located on the first portion 131, and W6 = 3 mm), and a positive number indicates that the first side of the first weld mark 61 is located on the surface of the second portion 132 (for example, W6 in Table 1 is 20 mm, i.e., the first side of the first weld mark 61 is located on the surface of the second portion 132, and W6 = 20 mm). Note that in Table 1, "\" indicates "none," and the number of "★" indicates the degree of wrinkles, with the more "★" the more serious the wrinkle occurrence. In Examples 1 to 23 and Comparative Examples 3 and 4, the tab folding ratio may be the ratio at which the second portion 132 and the first portion 131 are folded back (which may be understood with reference to FIGS. 3A, 3B, 4A, 4B, and 4C), while in Comparative Examples 1 to 2, the tab folding ratio may be the ratio at which the uncoated edge area (i.e., the tab pull-out structure 15′ in FIG. 2) is folded back (which may be understood with reference to FIG. 2).

[0148] By analyzing each set of data shown in Table 1 above, the following results can be seen.

[0149] A. Compared with Comparative Examples 1 and 2, Examples 1 to 23 in the present application significantly improved the situation of the electrochemical device tab folding, the situation of the cathode strip breaking, and the situation of the occurrence of wrinkles after cold rolling. Therefore, it can be seen that the present application effectively improved the yield rate of the electrochemical device.

[0150] B. In Examples 1 to 23 and Comparative Example 4, the width W2 of first portion 131 in each of Examples 1 to 23 and Comparative Example 4 satisfies 0.5 mm≦W2≦20 mm compared to Comparative Example 3. However, in Comparative Example 3, the width W2 of first portion 131 is 30 mm, which does not satisfy this range. As a result, the occurrence of wrinkles after cold rolling in the electrochemical device in Comparative Example 3 is more severe than in Examples 1 to 23 and Comparative Example 4. Therefore, 0.5 mm≦W2≦20 mm is a preferable range.

[0151] C. In Examples 1 to 23 and Comparative Example 3, the width W1 of second portion 132 in each of Examples 1 to 23 and Comparative Example 3 satisfies the range 3 mm≦W1≦35 mm compared to Comparative Example 4. However, in Comparative Example 4, the width W1 of second portion 132 is 40 mm, which does not satisfy this range. The condition of the tab folded back in the electrochemical device in Comparative Example 4 (tab folding ratio 0.4%) is more severe than in the electrochemical devices in Examples 1 to 23 and Comparative Example 3 (tab folding ratio up to 0.3%). Therefore, 3 mm≦W1≦35 mm is a preferable range.

[0152] As used herein, the term "comprises" and variations thereof are open inclusive, i.e., "including but not limited to." The term "based on" means "based at least in part on." The term "in one embodiment" means "at least one embodiment," the term "in another embodiment" means "at least one other embodiment," and the term "in some embodiments" means "at least some embodiments." Definitions related to other terms are explained below. Note that the terms "first," "second," etc., used herein merely distinguish between different devices, modules, or means, and do not limit the order or interdependence of functions performed by these devices, modules, or means.

[0153] It should be noted that the descriptions of "one" and "plurality" used in this application are exemplary and not limiting, and those skilled in the art should understand "one or more" unless the context clearly dictates otherwise.

[0154] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the disclosed invention. This application includes any modifications, uses, or adaptations of the present application, including those modifications, uses, or adaptations that conform to the general principles of the present application and incorporate common general knowledge or commonly used techniques in this field that are not disclosed herein. The specification and examples are exemplary only, with the true scope and spirit of the present application being indicated by the following claims.

Claims

1. 1. An electrochemical device comprising a pole piece, The pole piece includes a current collector, an active material layer disposed on a surface of the current collector, and a plurality of tab connection portions, each of which includes a first portion and a second portion, and when the pole piece is unfolded, the first portions of the plurality of tab connection portions extend from an edge of the current collector in the width direction of the pole piece and are disposed at intervals, and the second portions are disposed on the surface of the first portion and are electrically connected to the first portion. Electrochemical equipment.

2. Along the width direction of the pole piece, the width W1 of the second portion satisfies 3 mm≦W1≦35 mm. The electrochemical device of claim 1 .

3. Along the width direction of the pole piece, the width W1 of the second portion satisfies 5 mm≦W1≦25 mm. The electrochemical device of claim 2 .

4. Along the width direction of the pole piece, the width W2 of the first portion satisfies 0.5 mm≦W2≦20 mm. The electrochemical device of claim 1 .

5. Along the width direction of the pole piece, the width W2 of the first portion satisfies 1 mm≦W2≦10 mm.

5. The electrochemical device of claim 4.

6. The pole piece includes a cathode piece, an insulating layer is further provided on the surface of the current collector, and the active material layer and the insulating layer are aligned in the width direction of the pole piece. The electrochemical device of claim 1 .

7. Along the width direction of the pole piece, the width W3 of the insulating layer satisfies 0.5 mm≦W3≦5 mm; 7. The electrochemical device of claim 6.

8. the material of the insulating layer contains at least one of alumina and silicon oxide; The electrochemical device of claim 6.

9. Along the width of the pole piece, the insulating layer includes a first side proximate to the active material layer and a second side remote from the active material layer; a first side of the second portion is located on the insulating layer, and a distance W4 between the first side of the second portion and the second side of the insulating layer satisfies 0 mm≦W4≦8 mm; or a first side of the second portion is located on a surface of the first portion, and a distance W4 between the first side of the first portion and the second side of the insulating layer satisfies 0 mm≦W4≦10 mm; 7. The electrochemical device of claim 6.

10. a first side of the second portion is located on a surface of the first portion, and a distance W4 between the first side of the second portion and the second side of the insulating layer satisfies 0 mm≦W4≦5 mm; 10. The electrochemical device of claim 9.

11. The pole pieces include anode pieces. The electrochemical device of claim 1 .

12. the first portion and the second portion are electrically connected by welding, and a first weld mark is formed when the first portion and the second portion are welded together; along a width direction of the pole piece, the first weld mark includes a first side close to the active material layer and a second side away from the active material layer; a second side of the first weld mark is located in the second portion, and there is a gap between the first side of the first weld mark and the active material layer; The electrochemical device according to any one of claims 1 to 11.

13. Along the width direction of the pole piece, the width W5 of the first welding mark satisfies 0.1 mm≦W5≦10 mm.

13. The electrochemical device of claim 12.

14. a first side of the first weld mark is located in the first portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦5 mm; or a first side of the first weld mark is located on a surface of the second portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦30 mm; 13. The electrochemical device of claim 12.

15. a first side of the first weld mark is located in the first portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦3 mm; or a first side of the first weld mark is located on a surface of the second portion, and a distance W6 between the first side of the first weld mark and the first side of the second portion satisfies 0 mm≦W6≦10 mm; 15. The electrochemical device of claim 14.

16. a first projection of the second side of the first weld mark onto the second portion and a second projection of the first portion onto the second portion have an overlapping portion, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦15 mm; or a first projection of the second side of the first weld mark onto the second portion and a second projection of the first portion onto the second portion do not overlap, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦7 mm; 13. The electrochemical device of claim 12.

17. a first projection of the second side of the first weld mark onto the second portion and a second projection of the first portion onto the second portion have an overlapping portion, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦10 mm; or a first projection of the second side of the first weld mark onto the second portion and a second projection of the first portion onto the second portion do not overlap, and a distance W7 between the second side of the first weld mark and the second side of the first portion satisfies 0 mm≦W7≦3 mm; 17. The electrochemical device of claim 16.

18. the electrochemical device further includes a case and a tab extending from the case, the tab being electrically connected to the second portion by welding to form a second weld mark on the second portion; along the width of the pole piece, the second weld mark includes a first side proximate to the first portion and a second side away from the first portion; A distance W8 between the second side of the first weld mark and the first side of the second weld mark satisfies 0 mm < W8 ≦ 10 mm.

13. The electrochemical device of claim 12.

19. a weld tensile strength F between the first portion and the second portion satisfies 5N≦F≦1000N; The electrochemical device of claim 1 .

20. a weld tensile strength F between the first portion and the second portion satisfies 10N≦F≦500N; 20. The electrochemical device of claim 19.

21. the first portion and / or the second portion is a conductive foil material, and the resistance R per square millimeter of the conductive foil material satisfies R<20 mΩ; The electrochemical device of claim 1 .

22. The conductive foil material includes at least one of aluminum foil, aluminum-plated foil, nickel foil, and nickel-plated foil.

22. The electrochemical device of claim 21.

23. The aluminum-plated foil material includes at least one of a foil material obtained by aluminum-plating the surface of a thin film of polypropylenes and a foil material obtained by aluminum-plating the surface of a thin film of polyethylene terephthalates.

23. The electrochemical device of claim 22.

24. The thickness L of the second portion satisfies 4 μm≦L≦25 μm. The electrochemical device of claim 1 .

25. The thickness L of the second portion satisfies 5 μm≦L≦20 μm.

25. The electrochemical device of claim 24.

26. The breaking strength S of the second portion satisfies 80 MPa≦S≦800 MPa. The electrochemical device of claim 1 .

27. The breaking strength S of the second portion satisfies 100 MPa≦S≦450 MPa.

27. The electrochemical device of claim 26.

28. The electrochemical device is manufactured by winding a cathode piece, a separator, and an anode piece. The electrochemical device of claim 1 .

29. An electrochemical device comprising the electrochemical device according to any one of claims 1 to 28. Power consuming equipment.

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