Electrochemical equipment and power consumers

Abstract

An embodiment of the present invention provides an electrochemical device and a power consuming appliance, the electrochemical device including a pole piece, the pole piece including a current collector and an active material layer disposed on a surface of the current collector, a plurality of uncoated areas extending from an edge of the current collector along the width direction of the pole piece when the pole piece is unfolded, a tab connection piece disposed on a surface of each uncoated area, and the tab connection piece is electrically connected to the uncoated areas, the thickness L1 of the tab connection piece satisfying 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connection piece satisfying 200 MPa≦S1≦880 MPa.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention 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 tablets, mobile phones, electric vehicles, and energy storage equipment.

[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 multiple 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 the manufacturing process of this type of electrochemical device, one form of electrode piece is to cold-press the electrode piece with the active material layer applied thereto before die-cutting. Because the thickness difference between the active material layer and the uncoated edge area of ​​the current collector makes the electrode piece prone to wrinkling during the cold-pressing process, the uncoated edge area of ​​the current collector is generally stretched before cold-pressing to match the degree of deformation of the uncoated edge area of ​​the current collector and the active material layer, thereby preventing wrinkling during subsequent cold-pressing of the electrode piece. However, during the stretching process, the strength of each part of the uncoated edge area of ​​the current collector varies depending on the degree of stretching. Furthermore, when the uncoated edge area of ​​the current collector passes through the rollers, it tends to pass at a high speed and not fit quickly enough to the roller surface of the cold-pressing roller, which further deforms the uncoated edge area of ​​the current collector. This makes the die-cut tab structure from the uncoated edge area of ​​the current collector more likely to fold back, significantly reducing the yield rate of electrochemical devices. Summary of the Invention [Problem to be solved by the invention]

[0005] Accordingly, embodiments of the present invention provide electrochemical devices and power consuming equipment that at least partially address the above-mentioned problems.

[0006] A first embodiment of the present invention provides an electrochemical device comprising a pole piece, the pole piece including a current collector and an active material layer disposed on the surface of the current collector, wherein, when the pole piece is unfolded, a plurality of uncoated areas extend from the edge of the current collector along the width direction of the pole piece, and a tab connection piece is disposed on the surface of each uncoated area and electrically connected to the uncoated area, wherein the thickness L1 of the tab connection piece satisfies 3 μm≦L1≦35 μm and / or the breaking strength S1 of the tab connection piece satisfies 200 MPa≦S1≦880 MPa.

[0007] In an embodiment of the present invention, the electrochemical device has an uncoated area of ​​the current collector of the pole piece electrically connected to the tab connection piece, so that when the tab is pulled out from the uncoated area of ​​the current collector (i.e., the uncoated area extending from the edge of the current collector), the tab is not electrically connected to the uncoated area directly but is electrically connected to the tab by the tab connection piece welded to the uncoated area. This eliminates the need to stretch the uncoated area of ​​the pole piece before cold-pressing the pole piece in the manufacture of the electrochemical device, and can also alleviate the problem of wrinkling of the pole piece when the pole piece is subsequently cold-pressed. In this embodiment, the thickness L1 of the tab connection piece satisfies 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connection piece satisfies 200 MPa≦S1≦880 MPa. Therefore, the tab connection piece welded to the uncoated area corresponds to an extension of the uncoated area. Compared with a single uncoated area, the welded uncoated area and tab connection piece can fit better on the roller surface of the cold press roller when passing through the roller. The welded uncoated area and tab connection piece are less likely to deform, thereby solving the problem of easy folding back and improving the yield rate of electrochemical devices.

[0008] In some preferred embodiments, the thickness L1 of the tab connection piece satisfies 8 μm≦L1≦20 μm. When the thickness L1 of the tab connection piece in the present invention satisfies this range, the yield rate of the electrochemical device can be further improved without excessively increasing costs under conventional process conditions (i.e., without upgrading or modifying the process or equipment), and defects caused by the tab connection piece being too thick or too thin can also be better avoided.

[0009] In some preferred embodiments, the breaking strength S1 of the tab connection piece satisfies 420 MPa≦S1≦800 MPa. When the breaking strength S1 of the tab connection piece of the present invention satisfies this range, the yield rate of the electrochemical device can be further improved without excessively increasing costs under conventional process conditions, and defects caused by the tab connection piece having too high or too low breaking strength can be better avoided.

[0010] In some preferred embodiments, the thickness L2 of the uncoated area satisfies 2 μm≦L2≦18 μm.

[0011] If the thickness of the uncoated area is too thin, it increases the difficulty and cost of manufacturing the anode piece. Furthermore, if the thickness is too thin, it reduces the strength and makes it difficult to meet the structural strength requirements of the anode piece. If the thickness of the uncoated area is too thick, it increases the material cost and the overall volume of the electrochemical device, thereby reducing the energy density of the electrochemical device and placing higher requirements on welding equipment and processes. Therefore, by ensuring that the thickness L2 of the uncoated area in this range in the present invention not only effectively avoids the disadvantages of an uncoated area that is too thin, but also effectively avoids the disadvantages of an uncoated area that is too thick. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical device manufacturing.

[0012] In some preferred embodiments, the thickness L2 of the uncoated area satisfies 3 μm≦L2≦10 μm, which allows the energy requirements of the electrochemical device to be met even under conventional process conditions.

[0013] In some preferred embodiments, the breaking strength S2 of the uncoated area satisfies 150 MPa≦S2≦650 MPa.

[0014] If the breaking strength S2 of the uncoated area is too low, it will be prone to breakage during manufacturing, making it difficult to meet the structural strength requirements of the anode piece. If the breaking strength S2 of the uncoated area is too high, it will increase the difficulty and cost of manufacturing the anode piece. In this embodiment, the breaking strength S2 of the uncoated area satisfies the above range (i.e., 150 MPa≦S2≦650 MPa), which not only effectively avoids the disadvantages of an uncoated area having a breaking strength that is too low, but also effectively avoids the disadvantages of an uncoated area having a breaking strength that is too high. This meets the use needs of electrochemical devices and further improves the yield rate of electrochemical device manufacturing.

[0015] In some preferred embodiments, the breaking strength S2 of the uncoated area satisfies the range 280 MPa≦S2≦550 MPa, which allows the energy requirements of the electrochemical device to be met even under conventional process conditions.

[0016] In some preferred embodiments, the width W1 of the tab connecting piece along the width direction of the pole piece satisfies 3 mm≦W1≦35 mm.

[0017] If the width of the tab connection piece is too small, it is difficult to weld the tab connection piece to the uncoated area during the manufacture of an electrochemical device. If the width of the tab connection piece is too large, the edge of the tab connection piece is likely to be indented during die cutting in the process of manufacturing an anode piece, affecting the accuracy of the die cutting, especially when the die cutting operation is performed using a laser cutting method, as the laser focus is far from the cutting surface. In serious cases, cutting is often impossible, and the tab connection piece is prone to unintentional breakage. In this embodiment, the width of the tab connection piece satisfies the above range (i.e., 3 mm≦W1≦35 mm), which not only effectively avoids the disadvantages of a tab connection piece that is too small in width, but also effectively avoids the disadvantages of a tab connection piece that is too large in width. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0018] In some preferred embodiments, the width W1 of the tab connection piece satisfies 5 mm≦W1≦25 mm, which can further avoid the drawbacks caused by a tab connection piece having a width that is too small, and can also effectively avoid the drawbacks caused by a tab connection piece having a width that is too large, thereby meeting the application needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0019] In some preferred embodiments, the width W2 of the uncoated area along the width direction of the pole piece satisfies 0.5 mm≦W2≦15 mm.

[0020] If the width of the uncoated area is too small, it is difficult to ensure the required welding width during the manufacture of electrochemical devices, making it difficult to weld the tab connection piece to the uncoated area. If the width of the uncoated area is too large, wrinkles are more likely to occur in the uncoated area after cold pressing during the manufacture of the anode piece, which affects the assembly of the die-cut tab connection piece to be welded to the uncoated area, increasing energy density loss and costs. In this embodiment, the width of the uncoated area is within the above range (i.e., 0.5 mm≦W2≦15 mm), which not only effectively avoids the disadvantages of an uncoated area that is too small, but also effectively avoids the disadvantages of an uncoated area that is too large. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0021] In some preferred embodiments, the width W2 of the uncoated area satisfies the following relationship: 1 mm≦W2≦10 mm. This range can further avoid the drawbacks of an uncoated area being too small, and can also effectively avoid the drawbacks of an uncoated area being too large, thereby meeting the needs of electrochemical devices and improving the yield rate of electrochemical device production.

[0022] In some preferred embodiments, along the width direction of the pole piece, the active material layer includes a first side away from the uncoated area and a second side close to the uncoated area, and the tab connection piece includes a first side and a second side, where the first side of the tab connection piece is close to the first side of the active material layer and the second side of the tab connection piece is away from the first side of the active material layer. When the first side of the tab connection piece is located in the active material layer, the distance W3 between the first side of the tab connection piece and the second side of the active material layer satisfies 0 mm≦W3≦8 mm, or when the first side of the tab connection piece is located in the uncoated area, the distance W3 between the first side of the tab connection piece and the second side of the active material layer satisfies 0 mm≦W3≦10 mm.

[0023] When the first side of the tab connection piece is located in the active material layer, after welding the tab connection piece to the uncoated area, the first end of the tab connection piece extends beyond the first side of the uncoated area in the opposite direction to the width of the pole piece. If the distance W3 is too large (e.g., W3 > 8 mm), the resulting electrochemical device is likely to be too thick. On the other hand, if the first side of the tab connection piece is located in the uncoated area and the distance W3 between the first side of the tab connection piece and the second side of the active material layer is too large (e.g., W3 > 10 mm), the problem of the uncoated area being easily folded back after welding to the tab connection piece cannot be effectively resolved. By satisfying the above-mentioned range for W3 in the present invention, not only can the drawback of the first end of the tab connection piece extending beyond the first side of the uncoated area in the opposite direction to the width of the pole piece be effectively avoided, but also the drawback of the first side of the tab connection piece being located in the uncoated area and W3 being too large can be effectively avoided. This satisfies the needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0024] In some preferred embodiments, the first side of the tab connecting piece is located in the uncoated area, and the distance W3 between the first side of the tab connecting piece and the second side of the active material layer satisfies 0 mm≦W3≦5 mm. This range further ensures that the first side of the tab connecting piece is located in the uncoated area and avoids the drawbacks of W3 being too large, thereby meeting the application needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0025] In some preferred embodiments, a first weld mark is formed when the uncoated area is welded to the tab connection piece, and the active material layer has a first side away from the uncoated area and a second side close to the uncoated area along the width direction of the pole piece, and the first weld mark has a first side and a second side, where the first side of the first weld mark is close to the first side of the active material layer and the second side of the first weld mark is away from the first side of the active material layer. Here, the second side of the first weld mark is located on the tab connection piece. This ensures that the tab connection piece can be stably welded to the uncoated area.

[0026] In some preferred embodiments, the width W4 of the first weld mark along the width direction of the pole piece satisfies 0.1 mm≦W4≦10 mm.

[0027] If the width of the first weld mark is too small, it is difficult to ensure that the weld tensile strength between the uncoated area and the tab connection piece meets the requirements, resulting in the drawbacks of low weld tensile strength. On the other hand, if the width of the first weld mark is too large, it is difficult to assemble the die-cut tab connection piece after die-cutting the uncoated area of ​​the anode piece and the tab connection piece, which increases costs. In this embodiment, the width of the first weld mark satisfies the above range (0.1 mm≦W4≦10 mm), which avoids the drawbacks of a first weld mark that is too small and also avoids the drawbacks of a first weld mark that is too large. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical device manufacturing.

[0028] In some preferred embodiments, the tab connection piece includes a first side and a second side along the width direction of the pole piece, wherein the first side of the tab connection piece is close to the first side of the active material layer and the second side of the tab connection piece is far from the first side of the active material layer. When the first side of the first weld mark is located in an uncoated area, the distance W5 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦W5≦5 mm, or when the first side of the first weld mark is located in a tab connection piece, the distance W5 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦W5≦25 mm.

[0029] If the first side of the first weld mark extends too far beyond the first side of the tab connecting piece in the opposite width direction of the pole piece (e.g., W5 > 5 mm when the first side of the first weld mark is located in an uncoated area), there will be a large area without anode active material, resulting in a large space occupation rate where energy cannot be provided, resulting in a significant loss of energy density, which will affect the assembly of the die-cut tab connecting piece and further affect the subsequent welding of the anode tab and tab connecting piece. During this process, the tab connecting piece is likely to be damaged, ultimately affecting the electrical performance of the manufactured electrochemical device. On the other hand, if the first side of the first weld mark extends too far beyond the first side of the tab connecting piece in the width direction of the pole piece (e.g., W5 > 25 mm when the first side of the first weld mark is located on the tab connecting piece), the unconstrained tab connecting piece may be too wide, which will affect the die-cutting during the manufacture of the anode piece, increasing the difficulty of the process and affecting the yield rate of the manufactured electrochemical device. In the embodiment of the present invention, by setting W5 in this range, it is possible to avoid the drawback that occurs when the first side of the first weld mark exceeds the first side of the tab connecting piece in the direction opposite to the width direction of the tab, and also to avoid the drawback that occurs when the first side of the first weld mark exceeds the first side of the tab connecting piece in the width direction of the tab, thereby meeting the usage needs of electrochemical devices and further improving the yield rate of electrochemical devices.

[0030] In some preferred embodiments, when the first side of the first weld mark is located in an uncoated area, the distance W5 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦W5≦3 mm, or when the first side of the first weld mark is located in the tab connection piece, the distance W5 between the first side of the first weld mark and the first side of the tab connection piece satisfies 0 mm≦W5≦10 mm. By setting the distance W5 within these ranges, defects caused when the first side of the first weld mark extends too far beyond the first side of the tab connection piece in the direction opposite to the width direction of the tab can be avoided, and defects caused when the first side of the first weld mark extends too far beyond the first side of the tab connection piece in the width direction of the tab can also be avoided, thereby meeting the requirements for use of electrochemical devices and further improving the yield rate of electrochemical devices.

[0031] In some preferred embodiments, the uncoated area includes a first side and a second side along the width direction of the pole piece, wherein the first side of the uncoated area is close to the first side of the active material layer and the second side of the uncoated area is far from the first side of the active material layer. When the first projection of the second side of the first weld mark onto the tab connection piece and the second projection of the uncoated area onto the tab connection piece overlap, the distance W6 between the second side of the first weld mark and the second side of the uncoated area satisfies 0 mm≦W6≦15 mm, or when the first projection of the second side of the first weld mark onto the tab connection piece and the second projection of the uncoated area onto the tab connection piece do not overlap, the distance W6 between the second side of the first weld mark and the second side of the uncoated area satisfies 0 mm≦W6≦7 mm.

[0032] When the first projection and the second projection overlap, if the distance W6 between the second side of the first weld mark and the second side of the uncoated area is too large (for example, W6 > 15 mm when the first projection and the second projection overlap), that is, if the second side of the uncoated area extends too far beyond the second side of the first weld mark along the width direction of the anode piece, the uncoated area in an unconstrained state may be too wide, which will affect the die cutting when manufacturing the anode piece, increase the difficulty of the process, and affect the yield rate of the electrochemical device. When the first projection and the second projection do not overlap, if the distance between the second side of the first weld mark and the second side of the uncoated area is too large (e.g., W6 > 7 mm when the first projection and the second projection do not overlap), i.e., if the second side of the first weld mark extends too far beyond the second side of the uncoated area along the width direction of the pole piece, it will result in a significant loss of energy density, affect the subsequent electrical connection between the anode tab and the tab connection piece (e.g., the anode tab and the tab connection piece are electrically connected by welding), affect the assembly of the die-cut tab connection piece, and easily damage the tab connection piece during this process, ultimately affecting the electrical performance of the manufactured electrochemical device. By setting W6 in this range, the present invention not only avoids the drawbacks caused when the second side of the uncoated area extends too far beyond the second side of the first weld mark along the width direction of the pole piece, but also avoids the drawbacks caused when the second side of the first weld mark extends too far beyond the second side of the uncoated area along the width direction of the pole piece. This satisfies the needs of electrochemical devices and improves the yield of electrochemical devices.

[0033] In some preferred embodiments, when there is an overlap between the first projection of the first side of the first weld mark on the tab connection piece and the second projection of the non-coated area on the tab connection piece, the distance W6 between the second side of the first weld mark and the second side of the non-coated area satisfies 0 mm ≤ W6 ≤ 10 mm. Or, when there is no overlap between the first projection of the first side of the first weld mark on the tab connection piece and the second projection of the non-coated area on the tab connection piece, the distance W6 between the second side of the first weld mark and the second side of the non-coated area satisfies 0 mm ≤ W6 ≤ 3 mm. By setting it within such a range, it is possible to avoid the drawbacks caused when the second side of the non-coated area extends too far beyond the second side of the first weld mark along the width direction of the electrode tab. Furthermore, it is also possible to avoid the drawbacks caused when the second side of the first weld mark extends too far beyond the second side of the non-coated area along the width direction of the electrode tab. Thereby, the requirements for the use of the electrochemical device are met, and furthermore, the yield rate of the manufacture of the electrochemical device is improved.

[0034] In some preferred embodiments, the electrochemical device further includes a tab, the tab is electrically connected to the tab connection piece by welding, a second weld mark is formed on the tab connection piece, and along the width direction of the electrode tab, the second weld mark includes a first side and a second side. The first side of the second weld mark is close to the first side of the active material layer, and the second side of the second weld mark is away from the first side of the active material layer. Here, the distance W7 between the second side of the first weld mark and the first side of the second weld mark satisfies 0 mm < W7 ≤ 10 mm.

[0035] When the anode tab is electrically connected to the tab connection piece by welding, the second weld mark and the first weld mark formed on the tab connection piece do not overlap. If there is an overlap, the effectiveness of the weld between the anode tab and the tab connection piece is affected, reducing the tensile strength of the weld. If the distance W7 between the second side of the first weld mark and the first side of the second weld mark is too large (e.g., W7 > 10 mm), the energy density of the electrochemical device is likely to be affected. In this embodiment, by setting W7 within this range, not only can the drawbacks caused by overlap between the second weld mark and the first weld mark be avoided, but also the drawbacks caused by an excessively large distance W7 between the second side of the first weld mark and the first side of the second weld mark can be avoided. This meets the needs of electrochemical devices and further improves the yield rate of electrochemical devices.

[0036] In some preferred embodiments, the weld tensile strength F between the uncoated area and the tab connection piece satisfies 50N≦F≦1000N.

[0037] If the weld tensile strength between the uncoated area and the tab connection piece is too small, the tab connection piece will easily fall off from the uncoated area during use of the electrochemical device. If the weld tensile strength between the uncoated area and the tab connection piece is too high, it will affect the cost of manufacturing the electrochemical device. In this embodiment, the weld tensile strength F satisfies the above range (i.e., 50 N≦F≦1000 N), which not only effectively avoids the disadvantages of a weld that is too small between the uncoated area and the tab connection piece, but also effectively avoids the disadvantages of a weld that is too high between the uncoated area and the tab connection piece. This meets the needs of electrochemical devices and further improves the yield rate of manufactured electrochemical devices.

[0038] In some preferred embodiments, the weld tensile strength F between the uncoated area and the tab connection piece satisfies 280 N≦F≦500 N. Within this range, it is possible to effectively avoid the drawbacks caused by an excessively low weld tensile strength between the uncoated area and the tab connection piece, and also to effectively avoid the drawbacks caused by an excessively high weld tensile strength between the uncoated area and the tab connection piece, thereby meeting the application needs of electrochemical devices and improving the yield rate of electrochemical devices.

[0039] In some preferred embodiments, the uncoated area and / or the tab connection piece are made of conductive foil material, and the resistance R per square millimeter of the conductive foil material satisfies R<20 mΩ, thereby improving the conductive performance of the uncoated area and / or the tab connection piece and meeting the needs of electrochemical devices.

[0040] In some preferred embodiments, the conductive foil material includes at least one of copper foil and copper-plated foil, which can ensure the conductive performance of the uncoated area of ​​the anode piece and / or the tab connection piece, and meet the needs of the electrochemical device.

[0041] In some preferred embodiments, the pole pieces include a cathode piece and an anode piece, which makes the cathode piece and the anode piece of the electrochemical device less prone to folding problems, thereby improving the yield rate of the electrochemical device.

[0042] Another aspect of the present invention provides a power consuming device, comprising an electrochemical device as provided in the first aspect above.

[0043] The power consuming device in the embodiment of the present invention includes the electrochemical device provided in the first aspect above, and since the yield rate of the electrochemical device is high, the yield rate of the power consuming device is also high.

[0044] In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings required for the present invention will be briefly described below. However, the drawings in the following description are only some of the embodiments described in the embodiments of the present invention, and it is obvious that those skilled in the art can also obtain other drawings from these drawings. [Brief explanation of the drawings]

[0045] [Figure 1] FIG. 1 is a schematic diagram of an electrochemical device according to an embodiment of the present invention. [Figure 2] FIG. 2 shows a manufacturing process for an anode piece of an electrochemical device, which is an example of related art. [Figure 3A] FIG. 3A shows a manufacturing process of an anode piece for an electrochemical device according to an example of the present invention. [Figure 3B] FIG. 3B is an enlarged schematic view of Q in FIG. 3A. [Figure 4A] FIG. 4A is a schematic cross-sectional view of an example of an electrochemical device according to the present invention, taken along the thickness direction of an anode piece. [Figure 4B] FIG. 4B is a schematic cross-sectional view of an anode piece in the thickness direction of an electrochemical device according to another embodiment of the present invention. [Figure 4C] FIG. 4C is a schematic cross-sectional view of an anode piece in the thickness direction of an electrochemical device according to still another embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram of an ultrasonic seam welding method according to an embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram of a first welding mark in one example of the embodiment of the present invention. [Figure 7] FIG. 7 is a schematic diagram of a first welding mark in another example of the present invention. [Figure 8] FIG. 8 is a schematic diagram of a first welding mark in yet another example of the present invention. [Figure 9] FIG. 9 is a schematic diagram of a first welding mark in yet another example of the present invention. [Figure 10] FIG. 10 is a schematic diagram of an example of a power consumption device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0046] In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be described in detail below with reference to the drawings of the embodiments of the present invention, but it is obvious that the described embodiments are only some embodiments of the present invention and do not cover all of the embodiments, and all other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention fall within the scope of protection of the embodiments of the present invention.

[0047] Specific embodiments of electrochemical devices and power consuming devices according to examples of the present invention will be described below with reference to the drawings. Note that, in the drawings, components are not necessarily drawn to actual scale in order to facilitate explanation.

[0048] In the contents 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 of the present invention is not limited to a lithium ion battery and may be, for example, a sodium ion battery.

[0049] A first embodiment of the present invention provides an electrochemical device comprising a pole piece, the pole piece including a current collector and an active material layer disposed on a surface of the current collector, wherein, when the pole piece is unfolded, a plurality of uncoated areas extend from an edge of the current collector along the width direction of the pole piece, and a tab connection piece is disposed on a surface of each uncoated area, and the tab connection piece is electrically connected to the uncoated areas.

[0050] In the present embodiment, the electrode piece may be either a cathode piece or an anode piece. As shown in FIG. 1 , an electrochemical device 10 may be manufactured by winding an anode piece 1, a cathode piece 2, and a separator 3. It should be understood that this is merely an example and should not be considered a limitation of this embodiment. Specifically, after the electrochemical device 10 is manufactured by winding, a separator 3 is installed between the cathode piece 2 and the anode piece 1, isolating the cathode piece 2 and the anode piece 1, preventing short-circuiting between the cathode and anode within the electrochemical device 10, allowing ions to pass through, and maintaining the function of the electrolyte between the cathode piece 2, the separator 3, and the anode piece 1. Referring to FIGS. 1 to 9 , taking the electrode piece as an example, an anode piece 1, a current collector 11 includes a main body region 111 and an uncoated region 112 connected to each other, an active material layer 12 installed in the main body region 111, the uncoated region 112 welded to a tab connection piece 5, and a tab 4 electrically connected to the tab connection piece 5. Here, the thickness L1 of the tab connecting piece 5 satisfies 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connecting piece 5 satisfies 200 MPa≦S1≦880 MPa.

[0051] In this embodiment of the present invention, the electrochemical device 10 has the uncoated area 112 of the current collector 11 of the anode piece 1 welded to the tab connection piece 5. Therefore, in this embodiment of the present invention, when the anode tab 4 is pulled out from the uncoated area 112 of the current collector 11 (i.e., the uncoated area extending from the edge of the current collector 11), the anode tab 4 is not electrically connected directly to the uncoated area 112, but is electrically connected to the anode tab 4 using the tab connection piece 5 welded to the uncoated area 112. This eliminates the need to stretch the uncoated area 112 of the anode piece 1 (i.e., the uncoated area at the edge of the current collector 11) before cold-pressing the anode piece 1 when manufacturing the anode piece 1 of the electrochemical device 10, which also alleviates the problem of wrinkles occurring in the anode piece 1 when cold-pressing the anode piece 1 later. In this embodiment, the thickness L1 of the tab connection piece 5 satisfies 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connection piece 5 satisfies 200 MPa≦S1≦880 MPa. Therefore, the tab connection piece 5 welded to the uncoated area 112 corresponds to an extended portion of the uncoated area 112. Compared with a single uncoated area, the uncoated area 112 and the tab connection piece 5 welded together can fit better to the roller surface of the cold press roller when they pass through the roller. The uncoated area 112 and the tab connection piece 5 welded together are less likely to deform, thereby solving the problem of being easily folded over and improving the yield rate of electrochemical devices.

[0052] Specifically, as shown in Figures 4A, 4B, and 4C, cross-sectional schematic diagrams of the anode piece 1 in Figure 3A taken along the thickness direction are shown, along with schematic diagrams of the width direction Z of the anode piece (when the anode piece is unfolded). When viewed from the perspective of the current collector 11 in Figures 4A, 4B, and 4C, the main body region 111 and the uncoated region 112 are arranged in that order along the width direction Z of the anode piece, and the two are integrally formed.

[0053] 4A, 4B, and 4C also schematically show the position of the anode tab 4 electrically connected to the tab connection piece 5. It should be understood that FIGS. 4A, 4B, and 4C are provided to schematically explain this embodiment and are not intended to be a limitation on this embodiment.

[0054] The uncoated area 112 is welded to the tab connection piece 5 , and the tab connection piece 5 corresponds to an extension of the uncoated area 112 .

[0055] It should be understood that in one embodiment of the present invention, when the electrode piece is a positive electrode piece 1, the active material layer 12 is the positive electrode active material layer, and the current collector 11 is the positive electrode current collector, as can be seen in Figures 4A, 4B, and 4C. When the electrode piece is a negative electrode piece 2, the active material layer 12 is the negative electrode active material layer, and the current collector 11 is the negative electrode current collector.

[0056] In this embodiment, the active material layer 12 disposed on the main body region 111 of the anode piece 1 includes an anode active material, and the type of the anode active material is not limited and may be, for example, a graphite material, a silicon-based material, etc. In some preferred embodiments, the active material layer 12 may be a coating layer, i.e., the active material layer 12 may be applied to the main body region 111, thereby ensuring the stability of the structure in which the active material layer 12 is disposed on the main body region 111.

[0057] Preferably, in the anode piece 1, the width of the main body region 111 is equal to the width of the active material layer 12 along the width direction of the electrode piece.

[0058] The cathode piece 2 in this embodiment may be any suitable cathode piece in the related art or may be an electrode piece in an embodiment of the present invention. For example, the cathode piece 2 may be provided with a cathode active material layer (e.g., the cathode active material layer may include lithium iron phosphate, lithium manganese oxide, lithium iron phosphate, etc.), the cathode piece 2 may include a cathode current collector, which may include an aluminum material, and the cathode piece 2 may be further electrically connected to a cathode tab. Furthermore, for example, the cathode active material layer may be a coating layer applied to the cathode current collector, and the cathode current collector may include an uncoated area of ​​the current collector, with an insulating coating layer provided between the uncoated area of ​​the current collector and the cathode active material layer. Of course, these are examples for ease of understanding, and the embodiment is not specifically limited. In this embodiment, the anode tab 4 and the cathode tab of the electrochemical device 10 may be located on the same side of the electrochemical device 10 or on different sides of the electrochemical device 10.

[0059] Hereinafter, the electrochemical device 10 according to the embodiment of the present invention will be briefly described with reference to the manufacture of anode pieces of electrochemical devices in the related art. It should be understood that this is for ease of understanding and is not a limitation on the embodiment.

[0060] FIG. 2 illustrates the manufacturing process of an anode piece 1' of an electrochemical device according to the related art. In this example, the active material layer of the anode piece is a coating layer applied to a current collector. Referring to structure C1 in FIG. 2, structure C1 is actually a plurality of anode pieces without further processing. (Simply put, structure C1 is cut along dotted line c1, and then cut along dotted lines c2 and c3 to divide structure C1 into four anode pieces 1'. This process is described in detail below.) After applying active material layer 12' to current collector 11', structure C1 is obtained. Structure C1 is then cold-pressed (for example, using a stepped roller (i.e., a special cold-press roller) that is compatible with structure C1. When using a stepped roller, different sizes of stepped rollers must be designed for different types and sizes of structure C1). For specific details, refer to related art that uses stepped rollers to cold-press pole pieces; a detailed description is omitted here. During the cold pressing process, the thickness of the uncoated edge area 13' of the current collector 11' differs from the thickness of the coated area (i.e., the active material layer 12'), resulting in wrinkles easily forming in the structure C1 during the cold pressing process, which in turn results in wrinkles easily forming in the subsequently manufactured anode pieces 1'. Therefore, the uncoated edge area 13' is typically stretched first to match the deformation during the cold pressing process, thereby preventing wrinkles from forming in the anode pieces when the structure C1 is subsequently cold pressed. After the stretching and cold pressing steps are completed, the cold-pressed structure C1 is cut along the dotted line c1 (e.g., by laser cutting) to obtain two structures C2 (each structure C2 corresponds to two undie-cut anode pieces 1'). Furthermore, die cutting is performed on both sides of the uncoated edge area 13' of the two structures C2 to obtain two structures C3 (each structure C3 corresponds to two die-cut anode pieces 1').Further, the two structures C3 are cut along the dotted lines c2 and c3 (for example, the cutting method can be laser cutting technology) to obtain four anode pieces 1' as shown in FIG. 2 . The anode pieces 1' have multiple tab lead structures 14' for leading out tabs, which are formed by die-cutting from the edge uncoated area 13'. In this example, the tab lead structures 14' are trapezoidal, but this is just an example. Thereafter, when manufacturing an electrochemical device using the finally obtained anode pieces 1', the anode pieces 1' are wound with separators, cathode pieces, etc., and the multiple tab lead structures 14' are assembled and electrically connected to the anode tabs (for example, by welding). Finally, the electrochemical device is manufactured.

[0061] In contrast, the electrochemical device 10 in the embodiment of the present invention will be briefly described with reference to the fabrication of the pole pieces of the electrochemical device 10 in the embodiment of the present invention, and it should be understood that this is for ease of understanding and is not intended to be a limitation on the embodiment.

[0062] Referring to FIG. 3A, the manufacturing process of a pole piece (using an anode piece 1 as an example) of an electrochemical device 10 in this embodiment is shown. FIG. 3B is an enlarged schematic view of Q in FIG. 3A. In this example shown in FIG. 3A, the active material layer 12 of the anode piece 1 is a coating layer applied to each of the main body regions 111 of the current collector 11. Referring to structure D1 in FIG. 3A, structure D1 is actually a plurality of anode pieces 1 without further processing. (Simply put, structure C1 is cut along dotted line d1, and then cut along dotted lines d2 and d3 to divide structure D1 into four anode pieces 1. This process will be described in detail below.) After the active material layer 12 is applied to the current collector 11, structure D1 is obtained, and then cold-pressed. Here, the method of cold-pressing can be understood by referring to related techniques for cold-pressing pole pieces using cold press rollers, and therefore will not be described here. 3A and 2, Structure D1 and Structure C1 show that the width of the uncoated edge area of ​​the current collector 11 before die-cutting in Structure D1 in FIG. 3A is much smaller than that of Structure C1 in FIG. 2 because there is no need to stretch the uncoated edge area of ​​Structure D1 before cold-pressing. After the cold-pressing step is completed, the cold-pressed Structure D1 is cut along dotted line d1 (for example, the cutting method can be laser cutting technology) to obtain two Structures D2. A tab connection piece 5 is welded to each of the uncoated edge areas on both sides of Structure D2. After the welding is completed, two Structures D3 are obtained (each Structure D3 corresponds to two undie-cut anode pieces 1). Then, the two Structures D3 are die-cut on both sides near the tab connection piece 5 to obtain two Structures D4 (each Structure D4 corresponds to two die-cut anode pieces 1'). Then, the two structures D4 were cut along the dotted lines d2 and d3, respectively (for example, the cutting method may be laser cutting technology), to obtain four anode pieces 1 as shown in FIG. 3A (the structure can be further understood by referring to FIG. 3B).Thereafter, when manufacturing an electrochemical device 10 using the finally obtained anode piece 1, the anode piece 1 is wound together with a separator 3, a cathode piece 2, etc., and a plurality of die-cut tab connection pieces 5 are collected and electrically connected to the anode tab (for example, by welding). Finally, the electrochemical device 10 is manufactured.

[0063] In this embodiment, since there is no need to stretch the structure D1 (i.e., the plurality of anode pieces 1 that have not been further processed), cold pressing can be performed without using a stepped roller, and there is no need to design stepped rollers of corresponding sizes for different sizes of structures D1 to match the two. This improves the service life of the cold press roller, eliminates the need to frequently replace the cold press roller, and reduces the cost of cold pressing.

[0064] The thickness L1 of the tab connection piece 5 in the present invention satisfies the range of 3 μm≦L1≦35 μm. The reason for using a tab connection piece 5 having such a thickness is as follows: If the thickness of the tab connection piece 5 is too thin, it is difficult to effectively solve the folding problem. If the thickness of the tab connection piece 5 is too thick, it increases material costs. Furthermore, it is relatively difficult to achieve conventional welding standards during the subsequent manufacturing of the electrochemical device 10, placing high demands on the welding process. Furthermore, the die-cut tab connection piece 5 is difficult to assemble and bend, which increases process costs and increases the loss of energy density of the electrochemical device 10. In this embodiment, the thickness L1 of the tab connection piece 5 satisfies the above range (i.e., 3 μm≦L1≦35 μm), which not only effectively avoids the drawbacks of a tab connection piece 5 that is too thin, but also effectively avoids the drawbacks of a tab connection piece 5 that is too thick. This satisfies the needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0065] Preferably, the thickness L1 of the tab connection piece 5 satisfies 8 μm≦L1≦20 μm, in addition to 3 μm≦L1≦35 μm. When the thickness L1 is within this preferred range, the yield rate of the electrochemical device 10 can be further improved without excessively increasing costs under conventional process conditions (i.e., without upgrading or modifying the process or equipment).

[0066] Within the above range, an appropriate value can be selected as needed for the thickness L1 of the tab connection piece 5. For example, assuming that 8 μm≦L1≦20 μm, the thickness L1 of the tab connection piece 5 may be 8 μm, 10 μm, 15 μm, 18 μm, 20 μm, etc., and is not specifically limited thereto.

[0067] Preferably, when actually measuring the thickness L1 of the tab connection piece 5 of the manufactured electrochemical device 10, the electrochemical device 10 is first disassembled, and the unwelded portion between the first weld mark 61 and the second weld mark 62 in the tab connection piece 5 is taken and measured using a micrometer or a high-precision micrometer, or other methods may be used, and are not specifically limited herein.

[0068] The tab connection piece 5 in the present invention may be a conductive foil material, which will be described in detail later.

[0069] The breaking strength S1 of the tab connection piece 5 in the present invention satisfies the range of 200 MPa≦S1≦880 MPa. The reason for using a tab connection piece 5 with a breaking strength in this range is as follows: If the breaking strength S1 of the tab connection piece 5 is too small, it is difficult to effectively improve the folding problem. If the breaking strength S1 of the tab connection piece 5 is too large, it is difficult to assemble and bend the die-cut tab connection piece 5 during the subsequent manufacturing of the electrochemical device 10, making it difficult to achieve the required results using conventional processes, thereby increasing process costs and increasing the loss of energy density of the electrochemical device 10. The breaking strength S1 of the tab connection piece 5 in this embodiment satisfies the above range (i.e., 200 MPa≦S1≦880 MPa), which not only effectively avoids the disadvantages caused by a tab connection piece 5 with a breaking strength S1 that is too small, but also effectively avoids the disadvantages caused by a tab connection piece 5 with a breaking strength S1 that is too large. This satisfies the needs of the electrochemical device 10 and improves the yield of the electrochemical device 10.

[0070] Preferably, the breaking strength S1 of the tab connecting piece 5 satisfies 200 MPa≦S1≦880 MPa, and 420 MPa≦S1≦800 MPa. When the breaking strength S1 is within this preferred range, the yield rate of the electrochemical device 10 can be further improved without excessively increasing costs under conventional process conditions.

[0071] Within the above range, an appropriate value can be selected as needed for the breaking strength S1 of the tab connection piece 5. For example, taking 420 MPa≦S1≦800 MPa as an example, the breaking strength S1 of the tab connection piece 5 may be 420 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, etc., and is not specifically limited thereto.

[0072] In some preferred embodiments, the thickness L2 of the uncoated area 112 satisfies the range 2 μm≦L2≦18 μm. If the thickness of the uncoated area 112 is too thin, the manufacturing process for the anode piece 1 becomes more difficult and increases costs. Furthermore, if the thickness is too thin, the strength decreases, making it difficult to meet the structural strength requirements of the anode piece 1. If the thickness of the uncoated area 112 is too thick, it increases material costs and the overall volume of the electrochemical device, thereby reducing the energy density of the electrochemical device 10 and placing greater demands on welding equipment and processes. In this embodiment, the thickness L2 of the uncoated area 112 satisfies the above range (i.e., 2 μm≦L2≦18 μm), which not only effectively avoids the drawbacks of an uncoated area 112 being too thin, but also effectively avoids the drawbacks of an uncoated area 112 being too thick. This satisfies the needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0073] Preferably, the thickness L2 of the uncoated area 112 satisfies 3 μm≦L2≦10 μm, with 2 μm≦L2≦18 μm. Within this preferred range, the energy requirements of the electrochemical device can be met under conventional process conditions.

[0074] Within the above range, an appropriate value can be selected as needed for the thickness L2 of the uncoated area 112. For example, assuming 3 μm≦L2≦10 μm, the thickness L2 of the uncoated area 112 may be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., and is not specifically limited thereto.

[0075] Preferably, when actually measuring the thickness L2 of the uncoated area 112 of the manufactured electrochemical device 10, the electrochemical device 10 is first disassembled, and the unwelded portion in the uncoated area 112 is removed and measured using a micrometer or a high-precision micrometer, or other methods may be used, and the method is not specifically limited here.

[0076] The uncoated area 112 in the present invention may be a conductive foil material, as will be described in more detail below.

[0077] In some preferred embodiments, the breaking strength S2 of the uncoated area 112 satisfies the range 150 MPa≦S2≦650 MPa. If the breaking strength S2 of the uncoated area 112 is too low, the anode piece 1 is prone to breakage during manufacturing, making it difficult to meet the structural strength requirements. On the other hand, if the breaking strength S2 of the uncoated area 112 is too high, the manufacturing process of the anode piece 1 increases in difficulty and costs. In this embodiment, the breaking strength S2 of the uncoated area 112 satisfies the above range (i.e., 150 MPa≦S2≦650 MPa), which not only effectively avoids the drawbacks of the uncoated area 112 having a breaking strength that is too low, but also effectively avoids the drawbacks of the uncoated area 112 having a breaking strength that is too high. This satisfies the use needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0078] Preferably, the breaking strength S2 of the uncoated area 112 satisfies 280 MPa ≦ S2 ≦ 550 MPa, while maintaining 150 MPa ≦ S2 ≦ 650 MPa. Within this preferred range, the breaking strength S2 of the uncoated area 112 can be selected as needed, as long as it satisfies the energy requirements of the electrochemical device under conventional process conditions. For example, assuming 280 MPa ≦ S2 ≦ 550 MPa, the breaking strength S2 of the uncoated area 112 may be 280 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa, 550 MPa, etc., without being limited thereto.

[0079] In some preferred embodiments, the uncoated area 112 may be a conductive foil material, and the resistance R per square millimeter of the conductive foil material (i.e., the uncoated area 112) satisfies R<20 mΩ, thereby improving the conductive performance of the uncoated area 112 and meeting the usage needs of the electrochemical device 10.

[0080] Preferably, the main body region 111 may be a conductive foil material, for example, the resistance per square millimeter of the conductive foil material of the main body region 111 is less than 20 mΩ, thereby improving the conductive performance of the main body region 111 and meeting the use needs of the electrochemical device 10.

[0081] Preferably, the tab connection piece 5 in the present invention may be a conductive foil material, and the resistance R per square millimeter of the tab connection piece 5 preferably satisfies R<20 mΩ, thereby improving the conductive performance of the tab connection piece 5 and meeting the application needs of the electrochemical device 10.

[0082] Preferably, when measuring the resistance R per square millimeter of the uncoated area 112 or tab connection piece 5 of the manufactured electrochemical device 10, the electrochemical device 10 is first disassembled, and a clean portion (i.e., a portion without active material) of the uncoated area 112 or tab connection piece 5 is taken and measured using a resistance meter. If this is not possible, the active material adhering to the uncoated area 112 or tab connection piece 5 can be washed with an organic solvent such as alcohol, and the clean portion after washing can be taken and measured using a resistance meter. Alternatively, other methods of measurement may be used, and the method is not specifically limited herein.

[0083] When the uncoated area 112 and / or the tab connection piece 5 are made of a conductive foil, the specific material of the conductive foil is not particularly limited in this embodiment, and any material may be used as long as it ensures electrical conductivity and structural strength. For example, the conductive foil may include at least one of copper foil and copper-plated foil. Such a conductive foil material can ensure the electrical conductivity of the uncoated area 112 and / or the tab connection piece 5 of the anode piece 1 and meet the requirements of the electrochemical device 10.

[0084] The uncoated area 112 and the tab connection piece 5 may use the same type of conductive foil material, or different conductive foil materials. For example, in one preferred embodiment, the uncoated area 112 is copper foil, and the tab connection piece 5 is copper-plated foil material. In another preferred embodiment, the uncoated area 112 is copper-plated foil material, and the tab connection piece 5 is copper foil. In yet another preferred embodiment, the uncoated area 112 and the tab connection piece 5 are both copper foil. In yet another preferred embodiment, the uncoated area 112 and the tab connection piece 5 are both copper-plated foil. In these preferred embodiments, the thickness L1 of the tab connection piece 5 and the thickness L2 of the uncoated area 112 may be the same or different, and the breaking strength S1 of the tab connection piece 5 and the breaking strength S2 of the uncoated area 112 may be the same or different. Specific details can be understood by referring to the corresponding value ranges above, and further explanation will be omitted here.

[0085] Preferably, the main body region 111 of the current collector 11 of the anode piece 1 may be made of the same material as the uncoated region 112, and the thickness and breaking strength of the uncoated region 112 may be within the same ranges. That is, if the main body region 111 is made of a conductive foil material, it may be at least one of copper foil and copper-plated foil. The thickness of the main body region 111 may range from 2 μm to 15 μm, preferably from 3 μm to 10 μm. The breaking strength of the main body region 111 may range from 80 MPa to 800 MPa, preferably from 100 MPa to 550 MPa. This satisfies the requirements of the electrochemical device 10.

[0086] In some preferred embodiments, the uncoated area 112 and the tab connection piece 5 are welded to each other. In some preferred embodiments, the weld tensile strength F between the uncoated area 112 and the tab connection piece 5 satisfies the range 50 N≦F≦1000 N. If the weld tensile strength between the uncoated area 112 and the tab connection piece 5 is too small, the tab connection piece 5 will easily fall off from the uncoated area 112 when the electrochemical device 10 is in use. If the weld tensile strength F between the uncoated area 112 and the tab connection piece 5 is too large, it will affect the cost of manufacturing the electrochemical device 10. Therefore, the weld tensile strength F in this embodiment satisfies the above range (i.e., 50 N≦F≦1000 N), which not only effectively avoids the disadvantages caused by a weld being too small between the uncoated area 112 and the tab connection piece 5, but also effectively avoids the disadvantages caused by a weld tensile strength F between the uncoated area 112 and the tab connection piece 5 being too large. This satisfies the needs of the electrochemical device 10 and improves the yield of the electrochemical device 10.

[0087] Preferably, 50 N≦F≦1000 N, and the weld tensile strength F between the uncoated area 112 and the tab connection piece 5 satisfies 280 N≦F≦500 N. By keeping the value within this preferred range, defects caused by an excessively low weld tensile strength between the uncoated area 112 and the tab connection piece 5 can be better avoided, and defects caused by an excessively high weld tensile strength between the uncoated area 112 and the tab connection piece 5 can also be better avoided, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0088] Within the above range, the weld tensile strength F can be selected as appropriate as needed. For example, assuming 280N≦F≦500N, the weld tensile strength F may be 280N, 300N, 350N, 400N, 500N, etc., and is not specifically limited thereto.

[0089] The method for measuring the weld tensile strength F may refer to related art and is not specifically limited herein. For example, an exemplary method for measuring the weld tensile strength F may be as follows: A sample of the uncoated area 112 and the tab connection piece 5 after welding is taken and placed in a tensile strength tester. Along the width direction Z of the pole piece, a left clip and a right clip are placed to clamp the uncoated area 112 and the tab connection piece 5, respectively, with the left and right clips spaced apart by an appropriate distance (e.g., 20 mm). The welded area (e.g., the first weld mark 61 described below) is placed in the middle between the left and right clips. During the measurement, the left and right clips are kept so as not to come into contact with the welded area (e.g., the first weld mark 61 described below). Then, the left clip is fixed and held still, and 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 has broken. If the weld zone breaks, check the corresponding weld tensile strength F, and if the weld zone does not break, replace the sample and test again. Of course, this is merely an example and is not a limitation on the embodiment.

[0090] In the present embodiment, welding between the uncoated area 112 and the tab connection piece 5 may be performed by any welding method, such as ultrasonic seam welding. FIG. 5 illustrates a welding method for ultrasonic seam welding. First, the uncoated area 112 and the tab connection piece 5 are partially overlapped and placed on a seam welding holder 71. Then, a seam welding head 72 is positioned over the tab connection piece 5 and the uncoated area 112 above the seam welding holder 71 to perform ultrasonic welding. During the welding process, the seam welding head 72 generates high-frequency ultrasonic waves toward the tab connection piece 5 and the uncoated area 112. When the seam welding head 72 applies pressure to the tab connection piece 5 and the uncoated area 112, the contact surfaces of the tab connection piece 5 and the uncoated area 112 rub against each other, generating heat energy that melts the welded portion between the tab connection piece 5 and the uncoated area 112. Finally, a welded connection is formed between the tab connection piece 5 and the uncoated area 112. Of course, this is merely an example of an embodiment of the present invention and is not intended to be a limitation of the present invention.

[0091] 4A, 4B, and 4C, in the electrochemical device 10, a first weld mark 61 is formed when the uncoated area 112 is welded to the tab connection piece 5. Along the width direction Z of the pole piece, the active material layer 12 includes a first side away from the uncoated area 112 and a second side close to the uncoated area 112, and the first weld mark 61 includes a first side and a second side, where the first side of the first weld mark 61 is close to the first side of the active material layer 12 and the second side of the first weld mark 61 is away from the first side of the active material layer 12. The second side of the first weld mark 61 is located on the tab connection piece 5.

[0092] Specifically, the second side of the first weld mark 61 is located on the tab connection piece 5 to ensure that the tab connection piece 5 can form a stable weld connection with the uncoated area 112, which will be described in detail below.

[0093] In this embodiment, the shape of the first weld mark 61 is not limited. For example, as shown in FIGS. 6 and 7, the first weld mark 61 may be a combination of multiple sub-weld marks 611, with a distance between two adjacent sub-weld marks 611. The sub-weld marks 611 may be composed of multiple small welded joints with regular or irregular shapes. For example, the small welded joints may be shaped like a circle, a rectangle, or another polygon. Preferably, the shape of the sub-weld mark 611 formed by a row of small welded joints may be a polygon such as a parallelogram, a rectangle (which may be a square), or a triangle, or may be another irregular shape. For example, as shown in FIG. 6, the shape of the sub-weld mark 611 is a rectangle formed by the small welded joints, and the small welded joints are rectangular. Alternatively, as shown in FIG. 7, each sub-weld mark 611 may be an integral weld mark. This is not specifically limited.

[0094] 8 and 9, the first weld mark 61 may be a continuous weld mark. The continuous weld mark may be an integral weld mark (the integral weld mark can be understood by referring to FIG. 9, and therefore a description thereof will be omitted here). Alternatively, the continuous weld mark may be composed of a plurality of small welded joints having regular or irregular shapes. For example, the small welded joints may be circular, rectangular, or other polygonal shapes (the integral weld mark can be understood by referring to FIG. 8, and therefore a description thereof will be omitted here). This embodiment is not specifically limited.

[0095] Preferably, in this embodiment, in the case where the above-mentioned "first weld mark 61 is composed of multiple sub-weld marks 611, and there is a distance between two adjacent sub-weld marks 611," the area occupancy rate of the weld marks satisfies P>20%, and the weld mark area occupancy rate P=Sy / Sz, where Sy is the sum of the areas 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 sum of the sum of the areas of all the sub-weld marks 611 and the area of ​​the gap region between all the sub-weld marks 611).

[0096] Specifically, Sy and Sz are understood with reference to the case where the sub-weld mark 611 in Figure 7 is an integral weld mark. Here, Sz = h*W4, 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 occupancy rate P = Sy / Sz = (s1 + s2 + s3 + s4 + s5 + s6 + s7 + s8) / (h*W4) > 20%. Also, as will be described later, W4 is the width of the first weld mark 61.

[0097] Similarly, when each sub-weld mark 611 in Fig. 6 is a combination of multiple small weld joints with regular or irregular shapes, Sz = h * W4, and Sy is the sum of the areas of all the small weld joints. This can be understood by referring to the description of Fig. 7, and the description will be omitted here.

[0098] Of course, in other embodiments, the weld mark area occupancy rate P may be less than 20% while still satisfying the requirements of the electrochemical device 10, and is not particularly limited.

[0099] In some preferred embodiments, as shown in FIGS. 4A, 4B, and 4C, the width W4 of the first welded spot 61 along the width direction Z of the pole piece satisfies 0.1 mm≦W4≦10 mm.

[0100] The width W4 of the first weld mark 61 is the distance along the width direction Z of the pole piece between the first side of the first weld mark 61 and the second side of the first weld mark 61. The width of the first weld mark 61 (i.e., W4) can be understood with reference to Figures 6, 7, 8 and 9.

[0101] If the width of the first weld mark 61 is too small (i.e., W4<0.1 mm), it is difficult to ensure that the weld tensile strength F between the uncoated area 112 and the tab connection piece 5 meets the requirements, resulting in the drawbacks of a small weld tensile strength F. If the width of the first weld mark 61 is too large (i.e., W4>10 mm), it is difficult to assemble the die-cut tab connection piece 5 after die-cutting the uncoated area 112 of the anode piece 1 and the tab connection piece 5, resulting in additional costs. In this embodiment, the width W4 of the first weld mark 61 is within the above range (0.1 mm≦W4≦10 mm), which avoids the drawbacks of a too small width of the first weld mark 61 and also avoids the drawbacks of a too large width of the first weld mark 61. This meets the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0102] Within the above range, an appropriate value can be selected as needed for the width W4 of the first weld mark 61. For example, W4 may be 0.1 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, etc., assuming that 0.1 mm≦W4≦10 mm, but is not specifically limited thereto.

[0103] 4A, 4B, and 4C, along the width direction Z of the pole piece, the tab connection piece 5 includes a first side and a second side, wherein the first side of the tab connection piece 5 is close to the first side of the active material layer 12, and the second side of the tab connection piece 5 is away from the first side of the active material layer 12. When the first side of the first weld mark 61 is located in the uncoated area 112, the distance W5 between the first side of the first weld mark 61 and the first side of the tab connection piece 5 satisfies 0 mm≦W5≦5 mm, or when the first side of the first weld mark 61 is located in the tab connection piece 5, the distance W5 between the first side of the first weld mark 61 and the first side of the tab connection piece 5 satisfies 0 mm≦W5≦25 mm.

[0104] Specifically, as shown in Fig. 4B, Fig. 4B shows an example in which the first side of the first weld mark 61 is located in the uncoated area 112 (note that in Fig. 4B, the first side of the first weld mark 61 does not contact the uncoated area 112 and there is a gap between them, but the embodiment actually shown in Fig. 4B is one in which the first side of the first weld mark 61 is in direct contact with the uncoated area 112 and is located in the uncoated area 112, thereby welding the tab connection piece 5 and the uncoated area 112. This structure is shown here for ease of understanding and is not intended to be a limitation on the present invention). When the first side of the first weld mark 61 is located in the uncoated area 112, this corresponds to the first side of the first weld mark 61 exceeding the first side of the tab connection piece 5 in the direction opposite to the width direction Z of the pole piece, and the first weld mark 61 covers the first side of the tab connection piece 5. As shown in Figures 4A and 4C, an example is shown in which the first side of the first welding mark 61 is located in the uncoated area 112, and the first side of the first welding mark 61 is located in the tab connection piece 5, which corresponds to the first side of the first welding mark 61 exceeding the first side of the tab connection piece 5 along the width direction Z of the tab, and the first side of the tab connection piece 5 is not covered by the first welding mark 61, and the first side of the tab connection piece 5 can be in an unconstrained state, that is, the first side of the tab connection piece 5 is not welded to the uncoated area 112.

[0105] If the first side of the first weld mark 61 extends too far beyond the first side of the tab connecting piece 5 along the width direction Z of the pole piece (for example, W5 > 5 mm when the first side of the first weld mark 61 is located in the uncoated area 112), a large area will be devoid of anode active material, resulting in a large space occupation rate that cannot provide energy and a significant loss of energy density. This will affect the assembly of the die-cut tab connecting piece 5 and the subsequent welding of the anode tab 4 and the tab connecting piece 5. This process may also easily damage the tab connecting piece 5, ultimately affecting the electrical performance of the resulting 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 tab connecting piece 5 along the width direction Z of the pole piece (for example, W5 > 25 mm when the first side of the first weld mark is located in the tab connecting piece 5), the unconstrained tab connecting piece 5 may be too wide, which will affect the die-cutting process during the manufacture of the anode piece 1, increasing the difficulty of the process and affecting the yield rate of the electrochemical device 10.

[0106] In the embodiment of the present invention, by setting W5 in this range, it is possible to avoid defects that may occur when the first side of the first weld mark 61 extends too far beyond the first side of the tab connecting piece 5 in the direction opposite to the width direction of the tab, and also to avoid defects that may occur when the first side of the first weld mark 61 extends too far beyond the first side of the tab connecting piece 5 in the width direction of the tab. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0107] Preferably, within the above range, when the first side of the first weld mark 61 is located in the uncoated area 112, the distance W5 between the first side of the first weld mark 61 and the first side of the tab connection piece 5 satisfies 0 mm≦W5≦3 mm, or when the first side of the first weld mark 61 is located in the tab connection piece 5, the distance W5 between the first side of the first weld mark 61 and the first side of the tab connection piece 5 satisfies 0 mm≦W5≦10 mm. By keeping the distance within this preferred range, defects caused when the first side of the first weld mark 61 extends too far beyond the first side of the tab connection piece 5 in the direction opposite to the width direction of the tab can be avoided, and defects caused when the first side of the first weld mark 61 extends too far beyond the first side of the tab connection piece 5 in the width direction of the tab can also be avoided, thereby satisfying the requirements for use of the electrochemical device 10 and improving the yield rate of the electrochemical device 10.

[0108] Within the above range, an appropriate value for W5 can be selected as needed. For example, when the first side of the first weld mark 61 is located in the uncoated area 112, W5 may be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., assuming 0 mm≦W5≦3 mm as an example, and is not specifically limited thereto. For example, when the first side of the first weld mark 61 is located in the tab connection piece 5, W5 may be 0 mm, 1 mm, 3 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., assuming 0 mm≦W5≦10 mm as an example, and is not specifically limited thereto.

[0109] 4A, 4B, and 4C, the uncoated area 112 includes a first side and a second side along the width direction Z of the pole piece, where the first side of the uncoated area 112 is close to the first side of the active material layer 12 and the second side of the uncoated area 112 is away from the first side of the active material layer 12. When the first projection of the second side of the first weld mark 61 onto the tab connection piece 5 and the second projection of the uncoated area 112 onto the tab connection piece 5 overlap, the distance W6 between the second side of the first weld mark 61 and the second side of the uncoated area 112 satisfies 0 mm≦W6≦15 mm, or when the first projection of the second side of the first weld mark 61 onto the tab connection piece 5 and the second projection of the uncoated area 112 onto the tab connection piece 5 do not overlap, the distance W6 between the second side of the first weld mark 61 and the second side of the uncoated area 112 satisfies 0 mm≦W6≦7 mm.

[0110] It should be understood that the first projection may be the projection of the second side of the first welding mark 61 onto the tab connection piece 5 along the thickness direction of the tab connection piece 5, and the second projection may be the projection of the uncoated area 112 onto the tab connection piece 5 along the thickness direction of the tab connection piece 5.

[0111] 4B and 4C, when there is an overlap between the first projection and the second projection, this corresponds to the second side of the uncoated area 112 extending beyond the second side of the first weld mark 61 along the width direction Z of the pole piece, and the second side of the uncoated area 112 is in an unconstrained state, that is, the second side of the uncoated area 112 is not welded to the tab connection piece 5. When there is no overlap between the first projection and the second projection, this corresponds to the second side of the uncoated area 112 not extending beyond the second side of the first weld mark 61 along the width direction Z of the pole piece, and the second side of the uncoated area 112 is welded to the tab connection piece 5.

[0112] When the first projection and the second projection overlap, if the distance W6 between the second side of the first weld mark 61 and the second side of the uncoated area 112 is too large (for example, W6 > 15 mm when the first projection and the second projection overlap), that is, if the second side of the uncoated area 112 extends too far beyond the second side of the first weld mark 61 along the width direction Z of the anode piece, the uncoated area 112 in an unconstrained state may be too wide, which will affect die cutting when manufacturing the anode piece 1, increase the difficulty of the process, and affect the yield rate of the electrochemical device 10. On the other hand, when the first projection and the second projection do not overlap, if the distance W6 between the second side of the first weld mark 61 and the second side of the uncoated area 112 is too large (e.g., W6 > 7 mm when the first projection and the second projection do not overlap), i.e., if the second side of the first weld mark 61 extends too far beyond the second side of the uncoated area 112 along the width direction Z of the pole piece, a significant loss of energy density will occur, which will affect the subsequent electrical connection between the anode tab 4 and the tab connection piece 5 (e.g., the anode tab 4 and the tab connection piece 5 are electrically connected by welding) and the assembly of the die-cut tab connection piece 5. In this process, the tab connection piece is likely to be damaged, ultimately affecting the electrical performance of the manufactured electrochemical device 10.

[0113] In the embodiment of the present invention, by setting W6 in this range, it is possible to avoid the drawback that occurs when the second side of the uncoated area 112 extends too far beyond the second side of the first weld mark 61 along the width direction of the pole piece, and also to avoid the drawback that occurs when the second side of the first weld mark 61 extends too far beyond the second side of the uncoated area 112 along the width direction of the pole piece, thereby satisfying the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0114] Preferably, above the above range, when there is an overlap between the first projection of the first welding trace 61 on the tab connection piece 5 on the second side and the second projection of the uncoated area 112 on the tab connection piece 5, the distance W6 between the second side of the first welding trace 61 and the second side of the uncoated area 112 satisfies 0 mm ≦ W6 ≦ 10 mm, or when there is no overlap between the first projection of the first welding trace 61 on the tab connection piece 5 on the second side and the second projection of the uncoated area 112 on the tab connection piece 5, the distance W6 between the second side of the first welding trace 61 and the second side of the uncoated area 112 satisfies 0 mm ≦ W6 ≦ 3 mm. When within this preferred range, it is possible to avoid the drawbacks caused when the second side of the uncoated area 112 exceeds the second side of the first welding trace 61 along the width direction of the electrode plate, and further, it is also possible to avoid the drawbacks caused when the second side of the first welding trace 61 exceeds the second side of the uncoated area 112 along the width direction of the electrode plate. Thereby, the requirements for the use of the electrochemical device 10 are satisfied, and further, the yield rate of the manufacture of the electrochemical device 10 is improved.

[0115] Within the above range, W6 can be selected as an appropriate value as needed. For example, when there is an overlap between the first projection and the second projection, taking 0 mm ≦ W6 ≦ 10 mm as an example, W6 can be 0 mm, 1 mm, 3 mm, 5 mm, 8 mm, 9 mm, 10 mm, etc., and here, it is not specifically limited. For example, when there is no overlap between the first projection and the second projection, taking 0 mm ≦ W6 ≦ 3 mm as an example, W6 can be 0 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., and here, it is not specifically limited.

[0116] [[ID=⑧]]In some preferred embodiments, as shown in FIGS. 4A, 4B, and 4C, the electrochemical device 10 further includes an anode tab 4, the anode tab 4 is electrically connected to the tab connection piece 5 by welding, a second welding trace 62 is formed on the tab connection piece 5, and along the width direction Z of the electrode plate, the second welding trace 62 includes a first side and a second side, the first side of the second welding trace 62 is close to the first side of the active material layer 12, and the second side of the second welding trace 62 is away from the first side of the active material layer 12. Here, the distance W7 between the second side of the first welding trace 61 and the first side of the second welding trace 62 satisfies 0 mm < W7 ≦ 10 mm.

[0117] In the present invention, the specific welding process when the anode tab 4 is welded to the tab connection piece 5 is not limited. For example, the welding process may be a transfer welding. Accordingly, the second welding mark 62 may be a welding mark of the transfer welding.

[0118] When the anode tab 4 is electrically connected to the tab connection piece 5 by welding, the second welding mark 62 formed on the tab connection piece 5 and the first welding mark 61 do not overlap. If there is an overlap, it will affect the welding effect between the anode tab 4 and the tab connection piece 5, and the welding tensile strength of both will decrease. If the distance W7 between the second side of the first welding mark 61 and the first side of the second welding mark 62 is too large (for example, W7>10 mm), it is likely to affect the energy density of the electrochemical device 10. In this embodiment, by setting W7 within such a range, not only can the disadvantages caused by the overlap between the second welding mark 62 and the first welding mark 61 be avoided, but also the disadvantages caused by the case where the distance W7 between the second side of the first welding mark 61 and the first side of the second welding mark 62 is too large can be avoided. Thereby, the usage needs of the electrochemical device 10 are satisfied, and furthermore, the yield rate of manufacturing the electrochemical device 10 is improved.

[0119] Within the above range, W7 can select an appropriate value as needed. For example, taking 0 mm < W7 ≦ 10 mm as an example, W7 may be 1 mm, 3 mm, 5 mm, 7 mm, 9 mm, 10 mm, etc., where it is not specifically limited.

[0120] In this embodiment, the width W1 of the tab connection piece 5 (see FIGS. 4A, 4B, and 4C, the width W1 of the tab connection piece 5 is the distance between the first side of the tab connection piece 5 and the second side of the tab connection piece 5 along the width direction Z of the pole piece) is not limited as long as it meets the requirements of the electrochemical device 10. In some preferred embodiments, along the width direction Z of the pole piece, the active material layer 12 includes a first side away from the uncoated area 112 and a second side close to the uncoated area 112, the tab connection piece 5 includes a first side and a second side, and the uncoated area 112 includes a first side and a second side, where the first side of the tab connection piece 5 is close to the first side of the active material layer 12 and the second side of the tab connection piece 5 is away from the first side of the active material layer 12. Here, the width W1 of the tab connection piece 5 satisfies 3 mm≦W1≦35 mm.

[0121] If the width of the tab connection piece 5 is too small, it is difficult to weld the tab connection piece 5 to the uncoated area 112 during the manufacture of the electrochemical device 10. If the width of the tab connection piece 5 is too large, the edge of the tab connection piece 5 is likely to be indented during die cutting in the process of manufacturing the anode piece 1, affecting the accuracy of the die cutting, especially when the die cutting operation is performed using a laser cutting method, as the laser focus is far from the cutting surface. In serious cases, cutting is often impossible, and the tab connection piece is prone to unintentional breakage. In this embodiment, the width of the tab connection piece 5 satisfies the above range (i.e., 3 mm≦W1≦35 mm), which not only effectively avoids the disadvantages of a tab connection piece 5 that is too small, but also effectively avoids the disadvantages of a tab connection piece 5 that is too large. This meets the needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0122] Preferably, W1 satisfies 3 mm≦W1≦35 mm, and the width W1 of the tab connecting piece 5 satisfies 5 mm≦W1≦25 mm. By keeping the value within this preferred range, it is possible to further avoid the drawbacks caused by a tab connecting piece 5 having an excessively small width, and also to effectively avoid the drawbacks caused by a tab connecting piece 5 having an excessively large width, thereby meeting the usage needs of the electrochemical device 10 and further improving the yield rate of the electrochemical device 10.

[0123] Within the above range, the width W1 of the tab connection piece 5 can be selected as appropriate as needed. For example, W1 may be 5 mm, 10 mm, 15 mm, 18 mm, 20 mm, 23 mm, 25 mm, etc., taking 5 mm≦W1≦25 mm as an example, and is not specifically limited thereto.

[0124] In embodiments of the present invention, the width W2 of the uncoated area 112 of the current collector 11 (see FIGS. 4A, 4B, and 4C , the width W2 of the uncoated area 112 is the distance between the first side of the uncoated area 112 and the second side of the uncoated area 112 along the width direction Z of the pole piece) is not limited as long as it meets the requirements of the electrochemical device 10. In some preferred embodiments, along the width direction Z of the pole piece, the active material layer 12 includes a first side away from the uncoated area 112 and a second side closer to the uncoated area 112, the tab connection piece 5 includes a first side and a second side, and the uncoated area 112 includes a first side and a second side, where the first side of the uncoated area 112 is closer to the first side of the active material layer 12 and the second side of the uncoated area 112 is farther from the first side of the active material layer 12. Here, the width W2 of the uncoated area 112 satisfies 0.5 mm≦W2≦15 mm.

[0125] If the width of the uncoated area 112 is too small, it is difficult to ensure the required welding width during the manufacture of the electrochemical device 10, making it difficult to weld the tab connection piece 5 to the uncoated area 112. If the width of the uncoated area 112 is too large, wrinkles are more likely to occur in the uncoated area 112 after cold pressing during the manufacture of the anode piece 1, which affects the assembly of the die-cut tab connection piece 5 to be welded to the uncoated area 112, increases the loss of energy density, and increases costs. In this embodiment, the width of the uncoated area 112 satisfies the above range (i.e., 0.5 mm≦W2≦15 mm), which not only effectively avoids the disadvantages of an uncoated area 112 being too small, but also effectively avoids the disadvantages of an uncoated area 112 being too large. This satisfies the needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0126] Preferably, on the condition that 0.5 mm ≤ W2 ≤ 15 mm, the width W2 of the non-coated area 112 satisfies 1 mm ≤ W2 ≤ 10 mm. When within this preferred range, the drawbacks due to the width of the non-coated area 112 being too small can be further avoided, and the drawbacks due to the width of the non-coated area 112 being too large can be better avoided. Thereby, the usage needs of the electrochemical device 10 are satisfied, and the yield rate of the production of the electrochemical device 10 is further improved.

[0127] Within the above range, the width (i.e., W2) of the non-coated area 112 can be selected as an appropriate value as required. For example, taking 1 mm ≤ W2 ≤ 10 mm as an example, W2 may be 1 mm, 3 mm, 4 mm, 5 mm, 7 mm, 8 mm, 10 mm, etc., and here, it is not specifically limited.

[0128] In some preferred embodiments, as shown in FIGS. 4A, 4B, and 4C, along the width direction Z of the electrode plate, the active material layer 12 includes a first side away from the non-coated area 112 and a second side close to the non-coated area 112, and the tab connection piece 5 includes the first side and the second side. Here, the first side of the tab connection piece 5 is close to the first side of the active material layer 12, and the second side of the tab connection piece 5 is away from the first side of the active material layer 12. In this embodiment, when the first side of the tab connection piece 5 is located in the active material layer 12, the distance W3 between the first side of the tab connection piece 5 and the second side of the active material layer 12 satisfies 0 mm ≤ W3 ≤ 8 mm, or when the first side of the tab connection piece 5 is located in the non-coated area 112, the distance W3 between the first side of the tab connection piece 5 and the second side of the active material layer 12 satisfies 0 mm ≤ W3 ≤ 10 mm.

[0129]

[0130] ​Specifically, the width of the active material layer 12 may be the same as the width of the main body region 111 of the current collector, and the first side of the tab connecting piece 5 may be located on the active material layer 12. This is because the width of the active material layer 12 of the positive electrode piece 1 is generally greater than the width of the negative electrode active material layer of the negative electrode piece 2. Therefore, even if the tab connecting piece 5 is located on the active material layer 12, as long as it is ensured that the tab connecting piece 5 does not come into contact with the negative electrode active material layer of the negative electrode piece 2 after the positive electrode piece 1 and the negative electrode piece 2 are wound, the tab connecting piece 5 will not hinder ion transfer. This also meets the usage needs of the electrochemical device 10.

[0131] 4C , when the first side of the tab connection piece 5 is located in the active material layer 12, after the tab connection piece 5 is welded to the uncoated area 112, the first end of the tab connection piece 5 extends beyond the first side of the uncoated area 112 in the direction opposite to the width direction of the pole piece. If the distance W3 exceeds the first side (e.g., W3 > 8 mm), the thickness of the manufactured electrochemical device 10 is likely to be too large. As shown in FIGS. 4A and 4B , when the first side of the tab connection piece 5 is located in the uncoated area 112, if the distance W3 between the first side of the tab connection piece 5 and the second side of the active material layer 12 is too large (e.g., W3 > 10 mm), the problem of the tab connection piece 5 easily folding back after the uncoated area 112 is welded to the tab connection piece 5 cannot be effectively solved.

[0132] Therefore, in this embodiment, W3 satisfies the above range, which not only effectively avoids the drawback that occurs when the first end of the tab connecting piece 5 extends too far beyond the first side of the uncoated area 112 in the direction opposite to the width direction Z of the pole piece, but also effectively avoids the drawback that occurs when W3 is too large because the first side of the tab connecting piece 5 is located in the uncoated area 112. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0133] A preferred embodiment is one in which there is a distance between the first side of the tab connection piece 5 and the active material layer 12 (i.e., the first side of the tab connection piece 5 is located in the uncoated area 112). Preferably, when the first side of the tab connection piece 5 is located in the uncoated area 112, the distance W3 between the first side of the tab connection piece 5 and the second side of the active material layer 12 satisfies 0 mm≦W3≦5 mm. By keeping W3 within this preferred range, the first side of the tab connection piece 5 is located in the uncoated area 112, further avoiding the drawbacks of having W3 be too large. This satisfies the usage needs of the electrochemical device 10 and further improves the yield rate of the electrochemical device 10.

[0134] It should be understood that the above-mentioned contents are merely some preferred examples of the electrochemical device 10 in the embodiments of the present invention, and are not intended to be limitations on the electrochemical device 10 in the embodiments of the present invention.

[0135] As described above, the embodiments of the present invention provide an electrochemical device and a power consuming device, and in the embodiments of the present invention, the uncoated area of ​​the current collector of the pole piece of the electrochemical device is electrically connected to the tab connection piece. Therefore, in the embodiments of the present invention, when the tab is pulled out from the uncoated area of ​​the current collector (i.e., the uncoated area extending from the edge of the current collector), the tab is not electrically connected to the uncoated area directly, but is electrically connected to the tab by the tab connection piece welded to the uncoated area. This eliminates the need to stretch the uncoated area of ​​the pole piece before cold-pressing the pole piece in the manufacture of the electrochemical device, and can also alleviate the problem of wrinkling of the pole piece when cold-pressing the pole piece thereafter. In this embodiment, the thickness L1 of the tab connection piece satisfies 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connection piece satisfies 200 MPa≦S1≦880 MPa. Therefore, the tab connection piece welded to the uncoated area corresponds to an extension of the uncoated area. Compared to a single uncoated area, the welded uncoated area and tab connection piece fit better to the roller surface of the cold press roller when passing through the roller, and the welded uncoated area and tab connection piece are less likely to deform. This solves the problem of easy folding and improves the yield rate of electrochemical devices.

[0136] According to another aspect of the present invention, and referring to the structural block diagram of FIG. 10, the present invention provides a power consuming device 20, which includes any of the electrochemical devices 10 provided in the first aspect.

[0137] Specifically, the electrochemical device 10 may be configured to provide power to each power-consuming component in the power consuming device 20 .

[0138] The power consuming device 20 in the embodiment of the present invention includes the electrochemical device 10 described above, and since the yield rate of the electrochemical device 10 is high, the yield rate of the power consuming device 20 is also high.

[0139] The following description will be given with reference to some practical examples of the electrochemical device 10 in the present invention and some comparative examples of electrochemical devices in the related art, and the comparison between these examples and comparative examples will make it easier to understand the beneficial effects of the electrochemical device 10 in the present invention over the related art. In these comparative examples and examples, the electrochemical devices are all exemplified as lithium ion batteries.

[0140] The relevant data are shown in Table 1 below. In Table 1, the electrochemical devices of Comparative Example 1 and Comparative Example 2 have a normal wound structure. In addition, in Examples 1 to 34, compared to Comparative Examples 1 to 3, when manufacturing the anode pieces, the uncoated area of ​​the edge of the current collector is not stretched before cold pressing, and a tab connection piece is welded to the uncoated area of ​​the edge of the current collector (i.e., uncoated area 112), and a stepped roller is not used during the cold pressing process, while the other parameters are the same.

[0141] Table 1 JPEG2025531528000002.jpg143125

[0142] In Table 1 above, for ease of reading, in the W3 column, a negative number indicates that the first side of the tab connection piece 5 is located in the active material layer 12 (for example, W3 in Table 1 is -2 mm, i.e., the first side of the tab connection piece 5 is located in the active material layer 12, and W3 = 2 mm), and a positive number indicates that the first side of the tab connection piece 5 is located in the uncoated area 112 (for example, W3 in Table 1 is 2 mm, i.e., the first side of the tab connection piece 5 is located in the uncoated area 112, and W3 = 2 mm). Here, in the W5 column, a negative number indicates that the first side of the first weld mark 61 is located in the uncoated area 112 (for example, W5 in Table 1 is -3 mm, i.e., the first side of the first weld mark 61 is located in the uncoated area 112, and W5 = 3 mm), and a positive number indicates that the first side of the first weld mark 61 is located in the tab connection piece 5 (for example, W5 in Table 1 is 20 mm, i.e., the first side of the first weld mark 61 is located in the tab connection piece 5, and W5 = 20 mm). Note that "\" in Table 1 represents "none." In addition, for Examples 1 to 33, the percentage of tab folding refers to the percentage of folding occurring in the tab connection piece 5 and the uncoated area 112 (which can be understood by referring to Figures 3A, 3B, 4A, 4B, and 4C), and for Comparative Examples 1 and 2, the percentage of tab folding refers to the percentage of folding occurring in the edge uncoated area (i.e., the tab withdrawal structure 14' in Figure 2) (which can be understood by referring to Figure 2).

[0143] By analyzing the data shown in Table 1 above, it was found that the electrochemical device 10 in the examples of the present invention (i.e., Examples 1 to 33) significantly improved the folding condition of the tabs of the anode pieces of the electrochemical device compared to the electrochemical devices in the related art (Comparative Examples 1 to 2), thereby effectively improving the yield rate of the electrochemical device.

[0144] As used herein, the term "including" and variations thereof are openly inclusive, i.e., "including, but not limited to." The term "based on" means "based at least in part on." The term "one embodiment" means "at least one embodiment." The term "another embodiment" means "at least one other embodiment." The term "some embodiments" means "at least some embodiments." Definitions of other terms are explained below. Note that the concepts of "first," "second," etc. in the present invention are merely intended to distinguish between different devices, modules, or means, and are not intended to limit the order or interdependence of functions performed by these devices, modules, or units.

[0145] It should be noted that the modifiers "one" and "multiple" used herein are illustrative rather than limiting, and unless otherwise specified in the context, those skilled in the art should understand them as "one or more."

[0146] Other embodiments of the present invention will readily occur to those skilled in the art after studying the specification and practicing the disclosed invention. The gist of the present invention includes any modification, use, or adaptation of the present invention, which modification, use, or adaptation follows the general principles of the present invention and includes common knowledge or customary technical means known in the art that are not disclosed in the present invention. The specification and examples are considered to be exemplary only, with the true scope and spirit of the invention being indicated by the appended claims.

Claims

1. An electrochemical device including a pole piece, the pole piece including a current collector and an active material layer disposed on a surface of the current collector, wherein, when the pole piece is unfolded, a plurality of uncoated areas extend from an edge of the current collector along a width direction of the pole piece, a tab connection piece is disposed on a surface of each of the uncoated areas, and the tab connection piece is electrically connected to the uncoated areas; An electrochemical device, wherein the thickness L1 of the tab connection piece satisfies 3 μm≦L1≦35 μm, and / or the breaking strength S1 of the tab connection piece satisfies 200 MPa≦S1≦880 MPa.

2. 2. The electrochemical device according to claim 1, wherein the thickness L1 of the tab connection piece satisfies 8 μm≦L1≦20 μm.

3. The electrochemical device according to claim 1 , wherein the breaking strength S1 of the tab connection piece satisfies 420 MPa≦S1≦800 MPa.

4. 2. The electrochemical device according to claim 1, wherein the thickness L2 of the uncoated area satisfies 2 μm≦L2≦18 μm.

5. 5. The electrochemical device according to claim 4, wherein the thickness L2 of the uncoated area satisfies 3 μm≦L2≦10 μm.

6. The electrochemical device according to claim 1 , wherein the breaking strength S2 of the uncoated area satisfies 150 MPa≦S2≦650 MPa.

7. The electrochemical device according to claim 6 , wherein the breaking strength S2 of the uncoated area satisfies 280 MPa≦S2≦550 MPa.

8. 2. The electrochemical device according to claim 1, wherein a width W1 of the tab connection piece along the width direction of the pole piece satisfies 3 mm≦W1≦35 mm.

9. 9. The electrochemical device according to claim 8, wherein the width W1 of the tab connection piece satisfies 5 mm≦W1≦25 mm.

10. 2. The electrochemical device according to claim 1, wherein a width W2 of the uncoated area along the width direction of the pole piece satisfies 0.5 mm≦W2≦15 mm.

11. The electrochemical device according to claim 10 , wherein the width W2 of the uncoated area satisfies 1 mm≦W2≦10 mm.

12. Along the width direction of the pole piece, the active material layer includes a first side away from the uncoated area and a second side close to the uncoated area, and the tab connection piece includes a first side and a second side, the first side of the tab connection piece being close to the first side of the active material layer and the second side of the tab connection piece being away from the first side of the active material layer; When the first side of the tab connecting piece is located on the active material layer, a distance W3 between the first side of the tab connecting piece and the second side of the active material layer satisfies 0 mm≦W3≦8 mm; or 2. The electrochemical device according to claim 1, wherein when the first side of the tab connection piece is located in the uncoated area, a distance W3 between the first side of the tab connection piece and the second side of the active material layer satisfies 0 mm≦W3≦10 mm.

13. 13. The electrochemical device according to claim 12, wherein a first side of the tab connection piece is located in the uncoated area, and a distance W3 between the first side of the tab connection piece and the second side of the active material layer satisfies 0 mm≦W3≦5 mm.

14. a first welding mark is formed when the uncoated area is welded to the tab connection piece; Along a width direction of the pole piece, the active material layer includes a first side away from the uncoated area and a second side close to the uncoated area, the first weld mark includes a first side and a second side, the first side of the first weld mark being close to the first side of the active material layer and the second side of the first weld mark being away from the first side of the active material layer, The electrochemical device of claim 1 , wherein the second side of the first weld site is located on the tab connection piece.

15. The electrochemical device according to claim 14, wherein a width W4 of the first weld mark along the width direction of the pole piece satisfies 0.1 mm≦W4≦10 mm.

16. Along a width direction of the pole piece, the tab connection piece includes a first side and a second side, the first side of the tab connection piece being close to the first side of the active material layer and the second side of the tab connection piece being far from the first side of the active material layer; When the first side of the first welding mark is located in the uncoated area, a distance W5 between the first side of the first welding mark and the first side of the tab connecting piece satisfies 0 mm≦W5≦5 mm; or 15. The electrochemical device according to claim 14, wherein when the first side of the first welding mark is located on the tab connection piece, a distance W5 between the first side of the first welding mark and the first side of the tab connection piece satisfies 0 mm≦W5≦25 mm.

17. When the first side of the first welding mark is located in the uncoated area, a distance W5 between the first side of the first welding mark and the first side of the tab connecting piece satisfies 0 mm≦W5≦3 mm; or 17. The electrochemical device according to claim 16, wherein when the first side of the first welding mark is located on the tab connection piece, a distance W5 between the first side of the first welding mark and the first side of the tab connection piece satisfies 0 mm≦W5≦10 mm.

18. along a width direction of the pole piece, the uncoated area includes a first side and a second side, the first side of the uncoated area being proximate to the first side of the active material layer and the second side of the uncoated area being distant from the first side of the active material layer; When a first projection of the second side of the first welding mark onto the tab connection piece and a second projection of the uncoated area onto the tab connection piece overlap, a distance W6 between the second side of the first welding mark and the second side of the uncoated area satisfies 0 mm≦W6≦15 mm, or 15. The electrochemical device according to claim 14, wherein when a first projection of the second side of the first weld mark onto the tab connection piece and a second projection of the uncoated area onto the tab connection piece do not overlap, a distance W6 between the second side of the first weld mark and the second side of the uncoated area satisfies 0 mm≦W6≦7 mm.

19. When a first projection of the second side of the first welding mark onto the tab connection piece and a second projection of the uncoated area onto the tab connection piece overlap, a distance W6 between the second side of the first welding mark and the second side of the uncoated area satisfies 0 mm≦W6≦10 mm, or 19. The electrochemical device of claim 18, wherein when a first projection of the second side of the first welding mark onto the tab connection piece and a second projection of the uncoated area onto the tab connection piece do not overlap, a distance W6 between the second side of the first welding mark and the second side of the uncoated area satisfies 0 mm≦W6≦3 mm.

20. the electrochemical device further comprises a tab; the tab is electrically connected to the tab connection piece by welding, and a second welding mark is formed on the tab connection piece; the second weld mark includes a first side and a second side along a width direction of the pole piece, the first side of the second weld mark being close to the first side of the active material layer and the second side of the second weld mark being far from the first side of the active material layer; The electrochemical device according to claim 14 , wherein a distance W7 between the second side of the first weld mark and the first side of the second weld mark satisfies 0 mm<W7≦10 mm.

21. 2. The electrochemical device according to claim 1, wherein a weld tensile strength F between the uncoated area and the tab connection piece satisfies 50N≦F≦1000N.

22. 22. The electrochemical device according to claim 21, wherein a weld tensile strength F between the uncoated area and the tab connection piece satisfies 280N≦F≦500N.

23. 2. The electrochemical device according to claim 1, wherein the uncoated area and / or the tab connection piece is a conductive foil material, and the resistance R per square millimeter of the conductive foil material satisfies R<20 mΩ.

24. 24. The electrochemical device of claim 23, wherein the conductive foil material comprises at least one of a copper foil, a copper-plated foil material.

25. 10. The electrochemical device of claim 1, wherein the pole pieces include a cathode piece and an anode piece.

26. An electric power consuming device comprising an electrochemical device according to any one of claims 1 to 25.

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