Pole piece, battery cell and electric device

Abstract

The embodiment of the application relates to the battery technical field, and particularly discloses a pole piece, a battery cell and an electric device. The pole piece comprises a current collector, a first adapter layer and a second adapter layer, and the pole piece is provided with a welding part. The current collector comprises a first metal layer, a support layer and a second metal layer arranged along a first direction. The first adapter layer and the second adapter layer are connected to two sides of the current collector. The welding part is located at the connection between the first adapter layer and the first metal layer, and the welding part is located at the connection between the second adapter layer and the second metal layer. Along the first direction, the thickness of the welding part embedded in the support layer is D1 on one side of the first adapter layer, the thickness of the welding part embedded in the support layer is D2 on one side of the second adapter layer, and the thickness of the support layer is H1; the ratio of D1 and D2 to the thickness of the support layer satisfies 0.1 <= (D1+D2) / H1 <= 0.8, D1 / H1 >= 0.05, and D2 / H1 >= 0.05. Through the above structure, the range of the thickness of the welding part embedded in the support layer is optimized, and false welding or overwelding of the welding part is reduced.

Description

TECHNICAL FIELD

[0001] The embodiment of the present application relates to the battery technical field, in particular to a pole piece, a battery cell and an electric device. BACKGROUND

[0002] The composite current collector is a sandwiched pole piece composed of metal, polymer and metal structure, which is widely concerned by battery developers. The current collector uses polymer as the skeleton of the pole piece, thereby reducing the thickness of the metal layer. Such a pole piece structure can reduce the metal burrs when the battery cell is mechanically damaged, thereby solving the safety hazards caused by mechanical damage of the battery cell.

[0003] The inventors found that, in the metal-polymer-metal structure of the composite current collector, the metal and non-metal materials are included, and when the current collector and the aluminum foil are ultrasonically welded, the polymer layer cannot be well co-melted with the metal, and the problems of overwelding or false welding are prone to occur. SUMMARY

[0004] The embodiment of the present application aims to provide a pole piece, a battery cell and an electric device, which can improve the current situation that overwelding or false welding is prone to occur when the current collector and the aluminum foil are ultrasonically welded.

[0005] To solve the above technical problems, the following technical solutions are adopted in the present application:

[0006] In a first aspect, a pole piece is provided, comprising a current collector, a first adapter layer and a second adapter layer, wherein the pole piece is further provided with a welding portion. The current collector comprises a first metal layer, a support layer and a second metal layer arranged along a first direction. The first adapter layer is connected to a side of the first metal layer away from the support layer. The second adapter layer is connected to a side of the second metal layer away from the support layer. The pole piece is further provided with a welding portion, the welding portion is located at the connection between the first adapter layer and the first metal layer, and the welding portion is located at the connection between the second adapter layer and the second metal layer. Along the first direction, the welding portion is embedded in the thickness of the support layer on one side of the first adapter layer, the thickness of the welding portion embedded in the support layer on one side of the second adapter layer is D2, and the thickness of the support layer is H1; the ratio of D1 and D2 to the thickness of the support layer satisfies: 0.1 <= (D1+D2) / H1 <= 0.8. D1 / H1 >= 0.05, D2 / H1 >= 0.05.

[0007] In the above scheme, the welding portion is arranged to weld the first adapter layer and the second adapter layer to the current collector, wherein the first adapter layer is welded to the first metal layer of the current collector, and the second adapter layer is welded to the second metal layer of the current collector, so as to facilitate co-melting. Wherein the welding portion obtained after the welding of the pole piece is embedded towards the support layer, and further by optimizing the thickness of the welding portion embedded in the support layer, the thickness of the welding portion embedded in the support layer from both sides of the support layer and the thickness of the support layer itself satisfy: 0.1≤(D1+D2) / H1≤0.8, thereby reducing the virtual welding phenomenon caused by the too small embedding of the welding portion into the support layer, reducing the influence of the welding instability on the pole piece, or reducing the overwelding phenomenon caused by the too much embedding of the welding portion into the support layer, reducing the influence of the overwelding phenomenon on the pole piece which destroys the mechanical properties of the support layer. D1 / H1≥0.05, D2 / H1≥0.05, limiting the lower limit of D1 and D2, which can reduce the virtual welding phenomenon caused by the too small welding portion on one side.

[0008] In one or more embodiments, along the first direction, the ratio of D1 and D2 to the thickness of the support layer satisfies: 0.4≤(D1+D2) / H1≤0.6. Further reducing the virtual welding or overwelding of the welding portion.

[0009] In one or more embodiments, the thickness of the support layer along the first direction is H1, the thickness of the first metal layer along the first direction is H2, and the thickness of the second metal layer along the first direction is H3. 4μm≤H1≤18.4μm, 0.8μm≤H2≤3μm, 0.8μm≤H3≤3μm; and 6.5μm≤H1+H2+H3≤20μm. So that the support layer of the current collector has stable mechanical properties, and the first metal layer and the second metal layer are arranged to facilitate welding with the above-mentioned first adapter layer and second adapter layer.

[0010] In one or more embodiments, along the first direction, the support layer, the first metal layer and the second metal layer satisfy: 13μm≤H1≤16μm, 1μm≤H2≤3μm, 1μm≤H3≤3μm. Through this structure, the current collector has better mechanical properties and current carrying capacity.

[0011] In one or more embodiments, along the first direction, the thickness of the first adapter layer is Z1, 8μm≤Z1≤20μm. The thickness of the second adapter layer is Z2, 8μm≤Z2≤20μm. So as to reduce the thickness and space occupation of the pole piece.

[0012] In one or more embodiments, the width of the first adapter layer is Z3, 10mm≤Z3≤20mm; the width of the second adapter layer is Z4, 10mm≤Z4≤20mm. Thus, the width of the pole piece and the occupied space are reduced.

[0013] In one or more embodiments, the welding portion is provided with a plurality of welding leg portions, the plurality of welding leg portions are point-spaced in the area of the welding portion; the ratio of the area of the welding leg portion to the area of the welding portion is B, 0.3≤B≤0.7. When the ratio B is less than 0.3, the area of the welding leg portion is too small in the area of the welding portion, which is easy to cause false welding; when the ratio is greater than 0.7, the area of the welding leg portion is too large in the area of the welding portion, which is easy to cause overwelding.

[0014] In one or more embodiments, along the second direction, the width D3 of the welding leg portion satisfies: 10μm≤D3≤50μm; the second direction is perpendicular to the first direction and extends along the length of the current collector. Reduce the false welding or overwelding of the welding leg portion.

[0015] In one or more embodiments, the projection of the first adapter layer along the first direction at least partially coincides with the current collector, the projection of the second adapter layer along the first direction at least partially coincides with the current collector, and the welding portion is located in the projection overlap area of the first adapter layer, the current collector and the second adapter layer. Thus, the welding portion relatively welds the first adapter layer and the second adapter layer on both sides of the current collector, so as to facilitate the welding of the first adapter layer and the second adapter layer with other external metal materials.

[0016] In one or more embodiments, along the first direction, the thickness of the part where the welding portion, the first adapter layer, the current collector, and the second adapter layer coincide on the pole piece is A1; the thickness of the part where the first adapter layer, the current collector, and the second adapter layer coincide is A2; the difference between A1 and A2 is: 10μm≤A1-A2≤30μm. Through the above structure, the part of the pole piece with a thickness of A1 is thicker, which improves the structural strength of the pole piece and improves the structural stability of the pole piece.

[0017] In one or more embodiments, along the first direction, the current collector is provided with a hollow foil area in the area where the projections of the first adapter layer and the second adapter layer coincide, and the hollow foil area is used for welding the first adapter layer and / or the second adapter layer.

[0018] In one or more embodiments, the length of the empty foil region in the second direction is K1, and 1mm≤K1≤5mm. The second direction is perpendicular to the first direction and extends along the length of the current collector. Thus, space is left to facilitate welding.

[0019] In one or more embodiments, the length of the empty foil region in the second direction is K1, and 2.5mm≤K1≤3.5mm. Thus, space is further left to facilitate welding.

[0020] In one or more embodiments, the material of the support layer comprises polypropylene, polyethylene, polyurethane, polyethylene terephthalate, etc. so that the support layer has good mechanical properties.

[0021] In a second aspect, an electric core is provided, comprising an electrode assembly, wherein the electrode assembly comprises the electrode tab.

[0022] In a third aspect, a use electric device is provided, comprising the electric core.

[0023] The above description is only a summary of the technical solutions of the present application. In order to enable the technical means of the present application to be more clearly understood, and to be implemented according to the content of the description, and in order to enable the above and other purposes, characteristics and advantages of the present application to be more apparent and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the drawings.

[0025] Figure 1 is a schematic diagram provided by one or more embodiments of the present application;

[0026] Figure 2 is another schematic diagram provided by one or more embodiments of the present application;

[0027] Figure 3 is still another schematic diagram provided by one or more embodiments of the present application;

[0028] Figure 4 is a schematic diagram of a test method provided by the present application.

[0029] The reference signs are as follows:

[0030]

[0031] Detailed Implementation

[0032] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0033] It should be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component, or there may be one or more intermediate components in between. When a component is described as "connected to" or "welded" to another component, it can be directly connected / welded to the other component, or there may be one or more intermediate components in between.

[0034] In the description of the embodiments of this application, the technical terms "upper", "lower", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0035] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0036] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. Furthermore, the technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0038] In the first aspect, please refer to Figure 1 and Figure 2The application provides a pole piece 1000, which comprises a current collector 100, a first adapter layer 200, and a second adapter layer 300. The pole piece 1000 is provided with a welding portion 400. The current collector 100 comprises a first metal layer 110, a support layer 120, and a second metal layer 130 arranged along a first direction X. The first adapter layer 200 is connected to one side of the first metal layer 110 away from the support layer 120. The second adapter layer 300 is connected to one side of the second metal layer 130 away from the support layer 120. The welding portion 400 is located at the connection between the first adapter layer 200 and the first metal layer 110, and the welding portion 400 is also located at the connection between the second adapter layer 300 and the second metal layer 130. Along the first direction X, the welding portion 400 is embedded in the support layer 120 with a thickness of D1 on one side of the first adapter layer 200, and the welding portion 400 is embedded in the support layer 120 with a thickness of D2 on one side of the second adapter layer 300. The thickness of the support layer 120 is H1. The ratio of D1 and D2 to the thickness of the support layer 120 satisfies 0.1≤(D1+D2) / H1≤0.8. The welding portion 400 is arranged to weld the first adapter layer 200 and the second adapter layer 300 to the current collector 100, wherein the first adapter layer 200 is welded to the first metal layer 110 of the current collector 100, and the second adapter layer 300 is welded to the second metal layer 130 of the current collector 100, so as to facilitate co-melting. After welding, the welding portion 400 obtained from the pole piece 1000 penetrates through the first metal layer 110 and the second metal layer 130 from both sides and is embedded towards the support layer 120, and the thickness of the welding portion 400 embedded in the support layer 120 is further optimized, so that the thickness of the welding portion 400 embedded in the support layer 120 and the thickness of the support layer 120 itself satisfy 0.1≤(D1+D2) / H1≤0.8, thereby reducing the virtual welding phenomenon caused by the too small thickness of the welding portion 400 embedded in the support layer 120 when the ratio of the welding portion 400 embedded in the support layer 120 is less than 0.1, reducing the influence of the insecure welding on the pole piece 1000, or reducing the over-welding phenomenon caused by the too large thickness of the welding portion 400 embedded in the support layer 120 when the ratio of the welding portion 400 embedded in the support layer 120 is greater than 0.8, reducing the influence of the over-welding phenomenon on the pole piece 1000 which destroys the mechanical properties of the support layer 120. That is, when (D1+D2) / H1 is greater than 0.8, the welding portion 400 is prone to over-welding, thereby destroying the mechanical properties of the support layer 120, increasing the resistance of the current collector 100, and reducing the current carrying capacity of the current collector 100. When (D1+D2) / H1 is less than 0.1, the welding portion 400 after welding is not connected with the support layer 120, which is prone to the virtual welding phenomenon, resulting in insufficient bonding strength between the first adapter layer 200, the second adapter layer 300, and the current collector 100, and reducing the current carrying capacity and the mechanical properties of the current collector 100.

[0039] It needs to be further explained that the current collector 100 is a composite structure composed of various structural combinations, the materials of the first metal layer 110 and the second metal layer 130 are the same, on the one hand, the current-carrying capacity of the pole piece 1000 is stable, and the resistance of the current collector 100 is not uneven due to different metal materials, which affects the passage of current; on the other hand, the physical properties of the same metal material are the same during the welding process, so that the welding is stable and efficient. In the present application, the first adapter layer 200 and the first metal layer 110 are welded by roll welding, and the second adapter layer 300 and the second metal layer 130 are welded by roll welding. The advantage of this welding method is that the welding efficiency is high, the roll welding is a solid-phase welding, the metal is heated to a certain temperature, then the plastic deformation of the joint surface is generated by using the roller to apply pressure to produce metal bonding, and the internal resistance after welding is low, so that the conductivity of the pole piece 1000 is good. Alternatively, the materials of the first metal layer 110 and the second metal layer 130 include aluminum, copper and the like. It is worth mentioning that the materials of the first adapter layer 200 and the second adapter layer 300 include aluminum and copper, and in order to facilitate the welding between the first adapter layer 200 and the first metal layer 110 and the welding between the second adapter layer 300 and the second metal layer 130, the materials of the first metal layer 110, the second metal layer 130, the first adapter layer 200 and the second adapter layer 300 are the same, so that the first adapter layer 200 and the first metal layer 110 and the second adapter layer 300 and the second metal layer 130 can be co-melted during the roll welding process, which improves the welding efficiency while ensuring the current-carrying capacity.

[0040] In some preferred embodiments, along the first direction X, the thickness of the welding portion 400 embedded in the support layer 120 is D1, the thickness of the welding portion 400 embedded in the support layer 120 is D2, and 0.1≤(D1+D2) / H1≤0.8. Further reduce the virtual welding phenomenon or overwelding phenomenon of the welding portion 400. D1 / H1≥0.05, D2 / H1≥0.05. Through the above structure, in one or more embodiments of the present application, an embodiment with better current-carrying capacity and better mechanical properties can be obtained, which can be seen from the analysis of the embodiments and comparative examples below. Thus, reduce the virtual welding phenomenon or overwelding phenomenon of the welding portion 400, so as to reduce the insufficient connection strength between the current collector 100, the first adapter layer 200 and the second adapter layer 300 caused by the virtual welding of the welding portion 400, which affects the current-carrying capacity of the current collector 100, or reduce the damage to the structure of the support layer 120 in the current collector 100 caused by the overwelding of the welding portion 400, which affects the mechanical properties of the current collector 100. D1 / H1≥0.05, D2 / H1≥0.05, limit the lower limit of D1 and D2, which can reduce the over-small of one side of D1 and D2, which leads to the virtual welding phenomenon.

[0041] For the above-mentioned current collector 100, please refer to Figure 1 and Figure 2The thickness of the support layer 120 along the first direction X is H1, the thickness of the first metal layer 110 along the first direction X is H2, and the thickness of the second metal layer 130 along the first direction X is H3; 4pm≤H1≤18.4pm, 0.8pm≤H2≤3pm, 0.8pm≤H3≤3pm, and 6.5pm≤H1+H2+H3≤20pm. In order to ensure the mechanical properties of the current collector 100, the thickness of the support layer 120 is between 4pm and 18.4pm. If the thickness is too small, the support performance of the current collector 100 is insufficient, and the stress capacity of the current collector 100 is poor. If the thickness is too large, the volume of the current collector 100 is affected, which increases the thickness of the pole piece 1000, or in the case of a certain overall thickness of the current collector 100, the thickness of the support layer 120 occupies too much of the thickness of the current collector 100, which reduces the thickness of the first metal layer 110 and the second metal layer 130, and easily leads to a decrease in the current-carrying capacity of the current collector 100 and an increase in the resistance.

[0042] Preferably, referring to Figure 1 and Figure 2 . Along the first direction X, the support layer 120, the first metal layer 110, and the second metal layer 130 satisfy: 13pm≤H1≤16pm, 1pm≤H2≤3pm, and 1pm≤H3≤3pm. Thus, the mechanical properties of the support layer 120 are further improved, and the electrical conductivity of the first metal layer 110 and the second metal layer 130 is better.

[0043] In one or more embodiments of the present application, referring to Figure 1 and Figure 2 . For the above-mentioned first adapter layer 200 and second adapter layer 300, along the first direction X, the thickness of the first adapter layer 200 is Z1, 8pm≤Z1≤20pm; the thickness of the second adapter layer 300 is Z2, 8pm≤Z2≤20pm. The width of the first adapter layer 200 is Z3, 10mm≤Z3≤20mm; the width of the second adapter layer 300 is Z4, 10mm≤Z4≤20mm. It is worth mentioning that the thickness of the first adapter layer 200 and the width of the second adapter layer 300 arranged on both sides of the current collector 100 can be equal or unequal, and the thickness of the first adapter layer 200 and the thickness of the second adapter layer 300 arranged on both sides of the current collector 100 can be equal or unequal. When multiple pole pieces 1000 need to be stacked, the thickness of the first adapter layer 200 and / or the second adapter layer 300 of adjacent two pole pieces 1000 can be reduced to reduce the overall thickness and further improve the space utilization.

[0044] In one or more embodiments of the present application, referring to Figure 1 and Figure 2The welding portion 400 is provided with a plurality of welding leg portions 410, which are point-like and spaced apart within the area of the welding portion 400. The ratio of the area of the welding leg portion 410 to the area of the welding portion 400 is B, and 0.3≤B≤0.7. When the ratio B is less than 0.3, the area of the welding leg portion 410 is too small in the area of the welding portion 400, which is easy to cause a virtual weld; when the ratio is greater than 0.7, the area of the welding leg portion 410 is too large in the area of the welding portion 400, which is easy to cause an overweld. The welding leg portion 410 is located at the junction of the first metal layer 110, the first adapter layer 200 and at least part of the support layer 120, and the junction of the second metal layer 130, the second adapter layer 300 and at least part of the support layer 120. Among them, the welding leg portion 410 can be cylindrical along the first direction X, the diameter of the welding leg portion 410 is between 1mm to 5mm, preferably, the diameter of the welding leg portion 410 is 2mm, thereby improving the connection ability of the welding leg portion 410, improving the connection stability of the first adapter layer 200 and the first metal layer 110, and improving the connection stability of the second adapter layer 300 and the second metal layer 130. It can be understood that the point-like and spaced apart welding leg portions 410 deform the first adapter layer 200 and / or the second adapter layer 300 by embedding without overall compression, thereby improving the efficiency of roll welding and reducing the waste of materials. And when the ratio B is less than or equal to 0.7, the efficiency of roll welding can be further improved, and the cost of roll welding is reduced. Specifically, when the ratio B is greater than 0.7, on the one hand, it will cause the welding portion 400 to be overwelded, and on the other hand, the number of welding leg portions 410 needs to be increased, and then the number of welding points for roll welding the welding leg portions 410 needs to be increased in the roll welding process, thereby reducing the efficiency of roll welding.

[0045] Further, along the second direction Y, the width D3 of the welding leg portion 410 satisfies: 10μm≤D3≤50μm; the second direction Y is perpendicular to the first direction X and extends along the length of the current collector 100. It should be noted that the width of the welding leg portion 410 in the second direction Y includes the distance between two adjacent welding leg portions 410, thereby preventing the distance between the two welding leg portions 410 from being too close to cause overwelding. Through the above structure, when the width of the welding leg portion 410 is less than 10μm, it is easy to cause the welding leg portion 410 to be overwelded, which affects the mechanical properties of the current collector 100 and reduces the ability to withstand local stress; when the width of the welding leg portion 410 is greater than 50μm, it is easy to cause the welding leg portion 410 to be virtual welded, which affects the connection stability between the current collector 100 and the first adapter layer 200 and / or the second adapter layer 300.

[0046] In one or more embodiments of the present application, please refer to Figure 1 and Figure 2The projection of the first adapter layer 200 along the first direction X at least partially coincides with the current collector 100, the projection of the second adapter layer 300 along the first direction X at least partially coincides with the current collector 100, and the welding portion 400 is located in the projection overlapping area of the first adapter layer 200, the current collector 100 and the second adapter layer 300. Thus, the welding portion 400 relatively welds the first adapter layer 200 and the second adapter layer 300 to the two sides of the current collector 100, so as to facilitate the welding of the first adapter layer 200 and the second adapter layer 300 with other external metal materials. It can be understood that the projection of the first adapter layer 200 along the first direction X at least partially coincides with the current collector 100 means that the first adapter layer 200 is at least partially connected with the current collector 100 in the first direction X, while in the second direction Y, the current collector 100 leaves other areas not connected with the first adapter layer 200, for other external parts to be connected to the current collector 100, and the area of the first adapter layer 200 not connected with the current collector 100 in the second direction Y can be used to connect other metal materials; correspondingly, the projection of the second adapter layer 300 along the first direction X at least partially coincides with the current collector 100 means that the second adapter layer 300 is at least partially connected with the current collector 100 in the first direction X, while in the second direction Y, the current collector 100 leaves other areas not connected with the second adapter layer 300, for other external parts to be connected to the current collector 100, and the area of the second adapter layer 300 not connected with the current collector 100 in the second direction Y can be used to connect other metal materials. Alternatively, the area of the first adapter layer 200 and the second adapter layer 300 not connected with the current collector 100 can facilitate the connection between multiple pole pieces 1000.

[0047] In one or more embodiments of the present application, referring to FIG. 3, along the first direction X, the thickness of the portion where the welding portion 400, the first adapter layer 200, the current collector 100, and the second adapter layer 300 overlap is A1; the thickness of the portion where the first adapter layer 200, the current collector 100, and the second adapter layer 300 overlap is A2; and the difference between A1 and A2 is 10 pm≤A1-A2≤30 pm. Through the above structure, the portion of the pole piece 1000 with a thickness of A1 is thicker, which improves the structural strength of the pole piece 1000 and improves the structural stability of the pole piece. In combination with the above structure, before the pole piece 1000 is roll-welded, the thickness of the pole piece 1000 is the sum of the thickness of the current collector 100, the thickness of the first adapter layer 200, and the thickness of the second adapter layer 300. After the roll-welding of the pole piece 1000 is completed, the pole piece 1000 is compressed by roll-welding, and the solder leg portion 410 is embedded in the current collector 100, the first adapter layer 200, and the second adapter layer 300, so that the first adapter layer 200 and the second adapter layer 300 are deformed around the solder leg portion 410, that is, the difference between the thickness of the portion of the welding portion 400 and the thickness of the portion of the pole piece 1000 outside the welding portion 400 is 10 pm to 30 pm, which is the deformation amount of the pole piece 1000 before and after welding. Through the above structure, when the deformation amount is less than 10 pm, it indicates that the embedded thickness of the solder leg portion 410 is insufficient, which is easy to cause false welding; when the deformation amount is greater than 30 pm, it indicates that the embedded thickness of the solder leg portion 410 is excessive, which is easy to cause overwelding.

[0048] In one or more embodiments of the present application, referring to Figure 1 and Figure 2 , along the first direction X, the current collector 100 is provided with a blank foil area 500 in the area where the projections of the first adapter layer 200 and the second adapter layer 300 overlap, and the blank foil area 500 is used for welding the first adapter layer 200 and / or the second adapter layer 300. By providing the blank foil area 500, it is convenient to perform roll-welding and connect other metal materials such as aluminum foil, copper foil, etc. Specifically, the blank foil area 500 is an area that is not coated with other materials, thereby reducing the influence of the coated materials on roll-welding.

[0049] Optionally, along the second direction Y, referring to Figure 1 and Figure 2 , the length of the blank foil area 500 is K1, and 1 mm≤K1≤5 mm. The second direction Y is perpendicular to the first direction X and extends along the length of the current collector 100. Thus, more space is left for connecting other metal materials.

[0050] Preferably, along the second direction Y, referring to Figure 1 and Figure 2The length of the empty foil area 500 is K1, where 2.5mm ≤ K1 ≤ 3.5mm. This allows for more space to be provided for the connection of other metal materials while saving some space and reducing the volume and area occupied by the electrode 1000.

[0051] Optionally, the material of the support layer 120 includes polypropylene, polyethylene, polyurethane, polyethylene terephthalate, etc. This gives the support layer 120 good insulation properties, mechanical support properties, heat resistance, and wear resistance.

[0052] In conjunction with one or more embodiments given above, this application specifically provides the following embodiments and comparative examples for testing. The testing methods include two methods: 1) By clamping the electrode 1000 in a high-speed rail tensile testing machine, with the two sides of the electrode 1000 having the welding portion 400 connected to the high-speed rail tensile testing machine, and setting the speed of the high-speed rail tensile testing machine to 50 mm / min, the tensile force that the welding portion 400 can withstand after welding is tested to obtain the "welding tensile force." The greater the welding tensile force, the stronger the mechanical properties of this embodiment or comparative example; 2) As... Figure 4 As shown, the aforementioned electrode 1000 is connected to the same conductive element (in... Figure 4 In the lowest structure, one side of the welding part 400 in the second direction Y is connected to the conductive element. The welding part 400 is then symmetrically cut into two identical "C"-shaped regions along the second direction Y, and the two identical regions are respectively connected to the positive and negative terminals of the same circuit to form a conductive path. By providing the same voltage between the positive and negative terminals of the conductive path in each embodiment and comparative example, the "welding resistance" is measured. The smaller the welding resistance, the stronger the current carrying capacity of the embodiment. It should be understood that the welding resistance is only the resistance value used in this test to indicate the current carrying capacity of the embodiment or comparative example, and is not the actual resistance value of the embodiment or comparative example. It should be noted that the thickness of the first metal layer 110 and the second metal layer 130 of the current collector 100 in the following embodiments and comparative examples is 2 μm, and the thickness of the polymer layer is 15 μm.

[0053] Example 1: The ratio of the thickness of the welded part 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.1; the ratio of the area of ​​the weld foot 410 to the area of ​​the welded part 400 is 0.5.

[0054] Example 2: The ratio of the thickness of the welded part 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.3; the ratio of the area of ​​the weld foot 410 to the area of ​​the welded part 400 is 0.5.

[0055] Example 3: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.4; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.5.

[0056] Example 4: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.5; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.5.

[0057] Example 5: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.5.

[0058] Example 6: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.8; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.5.

[0059] Example 7: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.3.

[0060] Example 8: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.4.

[0061] Example 9: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.6.

[0062] Example 10: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.7.

[0063] Example 11: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.2.

[0064] Example 11: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.8.

[0065] Comparative Example 1: The ratio of the thickness of the weld portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.05; the ratio of the area of the leg portion 410 to the area of the weld portion 400 is 0.5.

[0066] Comparative Example 2: the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.9; the ratio of the area of the welding leg portion 410 to the area of the welding portion 400 is 0.5.

[0067] Through the above comparative examples and examples, the welding tension and welding resistance of the pole piece 1000 after roll welding are measured to obtain Table 1.

[0068] Table 1:

[0069]

[0070] Through the above tests, it is found that in Comparative Example 1, when the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is less than 0.1, the welding tension is low and the welding resistance is high; and in Comparative Example 2, when the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is greater than 0.8, the welding tension is low and the welding resistance is high. Comparing Example 11 and Example 12 with any one of Examples 7 to 10, it is found that the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6, the ratio of the welding leg portion 410 to the welding portion 400 in Example 11 is less than 0.3, the mechanical properties are insufficient compared with any one of Examples 7 to 10, and the welding resistance is large; the ratio of the welding leg portion 410 to the welding portion 400 in Example 12 is greater than 0.7, the mechanical properties are insufficient compared with any one of Examples 7 to 10, and the welding resistance is high. In the above examples provided in the present application, Examples 4 and 10 are more preferred, but it does not mean that the examples and preferred examples provided in the present application are only the above 12 examples. That is, when the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.5; the ratio of the area of the welding leg portion 410 to the area of the welding portion 400 is 0.5, or the ratio of the thickness of the welding portion 400 embedded in the support layer 120 to the thickness of the support layer 120 is 0.6; the ratio of the area of the welding leg portion 410 to the area of the welding portion 400 is 0.7, a more preferred example can be obtained. Thus, the pole piece 1000 after roll welding has better mechanical properties and current carrying capacity.

[0071] In combination with the above, the application also provides, in another aspect, a tab welding method applied to a tab 1000, the tab 1000 comprising: a current collector 100, a first adapter layer 200, a second adapter layer 300, and a tab, the method comprising: disposing the first adapter layer 200 and the second adapter layer 300 on both sides of the current collector 100; welding one end of the first adapter layer 200 and / or one end of the second adapter layer 300 to the current collector 100 by roll welding; and welding the other end of the first adapter layer 200 and / or the other end of the second adapter layer 300 to the tab by ultrasonic welding or spot welding.

[0072] In a second aspect, the application also provides a battery cell, the battery cell comprising an electrode assembly, the electrode assembly comprising the tab 1000 described above.

[0073] In a third aspect, the application also provides an electric device, the electric device comprising the battery cell.

[0074] In the embodiment of the present application, an electrode piece 1000 is provided, which comprises a current collector 100, a first adapter layer 200, and a second adapter layer 300. The electrode piece 1000 is provided with a welding portion 400. The current collector 100 comprises a first metal layer 110, a support layer 120, and a second metal layer 130 arranged along a first direction X. The first adapter layer 200 is connected to a side of the first metal layer 110 away from the support layer 120. The second adapter layer 300 is connected to a side of the second metal layer 130 away from the support layer 120. The welding portion 400 is located at the connection between the first adapter layer 200 and the first metal layer 110, and the welding portion 400 is also located at the connection between the second adapter layer 300 and the second metal layer 130. Along the first direction X, the welding portion 400 is embedded in the support layer 120 by a thickness D1 on a side of the first adapter layer 200, and the welding portion 400 is embedded in the support layer 120 by a thickness D2 on a side of the second adapter layer 300. The thickness of the support layer 120 is H1. The ratio of D1 and D2 to the thickness of the support layer 120 satisfies 0.1≤(D1+D2) / H1≤0.8. The welding portion 400 is arranged to weld the first adapter layer 200 and the second adapter layer 300 to the current collector 100, wherein the first adapter layer 200 is welded to the first metal layer 110 of the current collector 100, and the second adapter layer 300 is welded to the second metal layer 130 of the current collector 100, so as to facilitate co-melting. After the welding of the electrode piece 1000, the welding portion 400 is embedded towards the support layer 120, and the thickness of the welding portion 400 embedded in the support layer 120 is further optimized, so that the thickness of the welding portion 400 embedded in the support layer 120 from both sides of the support layer 120 and the thickness of the support layer 120 itself satisfy 0.1≤(D1+D2) / H1≤0.8. Thus, when the ratio of the thickness of the welding portion 400 embedded in the support layer 120 is less than 0.1, the virtual welding phenomenon caused by the excessive embedding of the welding portion 400 in the support layer 120 is reduced, the influence of the insecure welding on the electrode piece 1000 is reduced, or when the ratio of the thickness of the welding portion 400 embedded in the support layer 120 is greater than 0.8, the overwelding phenomenon caused by the excessive embedding of the welding portion 400 in the support layer 120 is reduced, and the influence of the overwelding phenomenon on the mechanical properties of the support layer 120 is reduced.

[0075] Based on the same inventive concept, the present application further provides an electric core, which comprises an electrode assembly, and the electrode assembly comprises the electrode piece 1000, which has the same structure and effects as the electrode piece 1000 described above, and will not be described here.

[0076] Based on the same inventive concept, the present application further provides a power-using device, which comprises an electric core, and the electric core has the same structure and effects as the electric core described above, and will not be described here.

[0077] It should be noted that the preferred embodiments of the present application are described in the specification and its attached drawings, but the present application can be implemented in many different forms and is not limited to the embodiments described in the specification, and these embodiments are not intended to be additional limitations on the content of the present application, and the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Furthermore, each of the above technical features continues to combine to form various embodiments not listed above, which are considered to be within the scope of the present application specification; further, for those skilled in the art, the above description can be improved or changed, and all these improvements and changes shall fall within the scope of protection of the claims of the present application.

Claims

1. A pole piece, characterized in that, The pole piece comprises: a current collector comprising a first metal layer, a support layer and a second metal layer arranged along a first direction; a first adapter layer connected to a side of the first metal layer away from the support layer; a second adapter layer connected to a side of the second metal layer away from the support layer; wherein the pole piece is further provided with a welding portion, the welding portion is located at the connection between the first adapter layer and the first metal layer, and the welding portion is located at the connection between the second adapter layer and the second metal layer, along the first direction, on one side of the first adapter layer, the welding portion is embedded in the support layer with a thickness of D1, on one side of the second adapter layer, the welding portion is embedded in the support layer with a thickness of D2, and the thickness of the support layer is H1; The ratio of D1 and D2 to the thickness of the support layer satisfies: 0.1≤(D1+D2) / H1≤0.8, D1 / H1≥0.05, D2 / H1≥0.

05.

2. The pole piece of claim 1, wherein Along the first direction, the ratio of D1 and D2 to the thickness of the support layer satisfies: 0.4≤(D1+D2) / H1≤0.

6.

3. The pole piece of claim 1, wherein The thickness of the support layer along the first direction is H1, the thickness of the first metal layer along the first direction is H2, and the thickness of the second metal layer along the first direction is H3; 4μm≤H1≤18.4μm, 0.8μm≤H2≤3μm, 0.8μm≤H3≤3μm; And 6.5μm≤H1+H2+H3≤20μm.

4. The pole piece of claim 3, wherein Along the first direction, the support layer, the first metal layer and the second metal layer satisfy: 13μm≤H1≤16μm, 1μm≤H2≤3μm, 1μm≤H3≤3μm.

5. The pole piece of claim 1, wherein The thickness of the first adapter layer along the first direction is Z1, 8μm≤Z1≤20μm; The thickness of the second adapter layer is Z2, 8μm≤Z2≤20μm.

6. The pole piece of claim 5, wherein The width of the first adapter layer is Z3, 10mm≤Z3≤20mm; The width of the second adapter layer is Z4, 10mm≤Z4≤20mm.

7. The pole piece of claim 1, wherein The welding portion is provided with a plurality of welding leg portions, and a plurality of welding leg portions are arranged in a point-like interval in the area of the welding portion; The ratio of the area of the welding leg portion to the area of the welding portion is B, 0.3≤B≤0.

7.

8. The pole piece of claim 7, wherein Along the second direction, the width D3 of the welding leg portion satisfies: 10μm≤D3≤50μm; The second direction is perpendicular to the first direction and extends along the length of the current collector.

9. The pole piece according to any one of claims 1-8, characterized in that, The projection of the first adapter layer along the first direction at least partially coincides with the current collector, the projection of the second adapter layer along the first direction at least partially coincides with the current collector, and the welding portion is located in the projection overlap area of the first adapter layer, the current collector and the second adapter layer.

10. The pole piece of claim 9, wherein, Along the first direction, the thickness of the overlapping part of the welding portion, the first adapter layer, the current collector and the second adapter layer is A1; the thickness of the overlapping part of the first adapter layer, the current collector and the second adapter layer is A2; The difference between A1 and A2 is: 10μm≤A1-A2≤30μm.

11. The pole piece of claim 10, wherein, In the first direction, the current collector is provided with a hollow foil area in a region where the projections of the first and second adapter layers coincide, the hollow foil area being used for welding of the first and / or second adapter layer.

12. The pole piece of claim 11, wherein, In the second direction, the length of the hollow foil area is K1, 1mm≤K1≤5mm; The second direction is perpendicular to the first direction and extends along the length of the current collector.

13. The pole piece of claim 12, wherein, In the second direction, the length of the hollow foil area is K1, 2.5mm≤K1≤3.5mm.

14. The pole piece of any of claims 1-8, wherein, The material of the support layer comprises polypropylene, polyethylene, polyurethane, polyethylene terephthalate, etc.

15. An electric cell, characterized by An electrode assembly comprising the electrode tab as claimed in any one of claims 1 to 14.

16. An electrical device, characterized by An electric cell comprising the electrode tab as claimed in claim 15.

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