Pole piece, battery cell and battery

Abstract

The utility model discloses a pole piece which comprises a composite current collector which is provided with a coating area and an empty foil area, each of the coating area and the empty foil area comprises a first conducting layer, a base material layer and a second conducting layer which are laminated, and the empty foil area is at least divided into a non-cutting area, a first cutting area and a second cutting area, the first cutting area and the second cutting area are oppositely folded from the two ends of the non-cutting area to correspondingly form a first folding part and a second folding part, and the first folding part extends into the folding space of the second folding part and is overlapped with the second folding part; the active material layer is arranged on the first conductive layer of the coating area and / or the second conductive layer of the coating area; and the tab is respectively connected with the first conductive layer at the first folding part and the second conductive layer at the second folding part, so that the first conductive layer and the second conductive layer are electrically conducted. The pole piece solves the problem that the upper metal layer and the lower metal layer cannot be conducted simultaneously when the composite current collector is used as an electrode current collector, and the utilization rate of the conducting layer of the composite current collector is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium batteries, and particularly relates to an electrode sheet, a battery cell and a battery. Background Art

[0002] With the continuous development of mobile energy storage technology, the requirements for the reliability and safety of its compatible batteries are more extreme. It is expected that the battery can broaden the usage scenarios and reduce geographical restrictions while ensuring safety. Based on this, the conventional metal foil current collectors used in batteries can no longer meet the above requirements at the same time, and composite current collectors emerge as the times require. They integrate the advantages of metal foils and polymers and can meet the comprehensive performance requirements of batteries.

[0003] The structure of the composite current collector is similar to a "sandwich" structure. The inner layer is a substrate layer made of polymer polymers (such as polymer materials like PP / PET / PI, etc.). Conductive layers (such as Al or Cu) are provided on both surfaces of the substrate layer. On the electrode sheet, the tab is usually arranged on one side of the electrode sheet, and the conductive layer of the composite current collector on the corresponding side is welded to the tab and cooperates with the tab to perform charge and discharge. However, the conductive layer on the other side of the composite current collector is not electrically connected to the tab, resulting in the "idle" of the non-conductive conductive layer on that side, which is not fully utilized, wasting materials and occupying space, and the energy density of the battery cell is low. Summary of the Utility Model

[0004] The main purpose of the utility model is to propose an electrode sheet, aiming to solve the technical problems that the utilization rate of the conductive layer of the composite current collector in the current electrode sheet is low, resulting in waste of materials and occupation of space, and the energy density of the battery cell is low.

[0005] To achieve the above purpose, the utility model proposes an electrode sheet, which includes:

[0006] A composite current collector, the composite current collector has a coating area and a bare foil area arranged in sequence along its length direction. Both the coating area and the bare foil area include a first conductive layer, a substrate layer and a second conductive layer arranged in a stacked manner. The bare foil area is at least divided into a non-cutting area, a first cutting area and a second cutting area. The first cutting area and the second cutting area are respectively folded inwards from both ends of the non-cutting area to correspondingly form a first folding part and a second folding part. The first folding part extends into the folding space of the second folding part and is at least partially overlapped with the second folding part;

[0007] An active material layer, the active material layer is arranged on the first conductive layer and / or the second conductive layer of the coating area;

[0008] The tab is clamped between the first conductive layer at the first folding portion and the second conductive layer at the second folding portion, and the tab is respectively connected to the first conductive layer at the first folding portion and the second conductive layer at the second folding portion, so that the first conductive layer and the second conductive layer are electrically connected.

[0009] In some embodiments, the width of the non-cutting area is greater than the width of the tab; and / or,

[0010] The widths of the folded portions of the first folding portion and the second folding portion are both less than the width of the non-cutting area; and / or,

[0011] The width of the overlapping portion of the first folding portion and the second folding portion is greater than the width of the tab.

[0012] In some embodiments, the positive projection of the end of the first folding portion in the thickness direction of the composite current collector is located within the non-cutting area;

[0013] The positive projection of the end of the second folding portion in the thickness direction of the composite current collector is located within the non-cutting area.

[0014] In some embodiments, after the first cutting area of the empty foil area is folded, a first cutting hole is formed, and the first cutting hole has a plurality of first inner corners, and all of the plurality of first inner corners are chamfered; and / or,

[0015] After the second cutting area of the empty foil area is folded, a second cutting hole is formed, and the second cutting hole has a plurality of second inner corners, and all of the plurality of second inner corners are chamfered.

[0016] In some embodiments, the first cutting area, the non-cutting area and the second cutting area are located at the edge position of the empty foil area along the length direction of the composite current collector; or,

[0017] The first cutting area, the non-cutting area and the second cutting area are located at the edge position of the empty foil area along the width direction of the composite current collector.

[0018] In some embodiments, the tab has a welding portion for welding connection with the first conductive layer at the first folding portion and the second conductive layer at the second folding portion;

[0019] The lengths of the first folding portion and the second folding portion are both greater than the length of the welding portion, and the lengths of the first folding portion and the second folding portion are both less than 1 / 4 of the width of the composite current collector.

[0020] In some embodiments, the tensile strength of the tab welded to the first conductive layer is greater than the peel strength of the first conductive layer from the substrate layer; and / or,

[0021] the tensile strength of the tab welded to the second conductive layer is greater than the peel strength of the second conductive layer from the substrate layer.

[0022] In some embodiments, the thickness of the tab is greater than or equal to the thickness of the composite current collector.

[0023] The present utility model further provides an electric core, which includes a positive electrode tab, a negative electrode tab and a separator disposed between the positive electrode tab and the negative electrode tab;

[0024] wherein, at least one of the positive electrode tab and the negative electrode tab adopts the tab as described above.

[0025] The present utility model further provides a battery, which includes a housing and the electric core as described above, and the electric core is disposed in the housing.

[0026] In the tab of the present utility model, the composite current collector has a coating area and a bare foil area arranged in sequence along its length direction. Both the coating area and the bare foil area include a first conductive layer, a substrate layer and a second conductive layer arranged in a stacked manner. The active material layer is disposed on the first conductive layer and / or the second conductive layer in the coating area. Among them, the bare foil area is at least divided into a non-cutting area, a first cutting area and a second cutting area, and the first cutting area and the second cutting area are folded from both ends of the non-cutting area towards each other to correspondingly form a first folding part and a second folding part. The first folding part extends into the folding space of the second folding part and is at least partially overlapped with the second folding part. By connecting the tab between the first conductive layer at the first folding part and the second conductive layer at the second folding part, the first conductive layer and the second conductive layer are electrically connected, so that both the first conductive layer and the second conductive layer of the composite current collector cooperate with the tab to perform charge and discharge, solving the problem that the upper and lower metal layers of the composite current collector cannot be simultaneously conducted when used as an electrode current collector, improving the utilization rate of the conductive layer of the composite current collector, thereby avoiding waste of materials and occupation of space, and improving the energy density of the electric core. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic structural diagram of a tab in an embodiment of the present utility model;

[0028] Figure 2 is a schematic structural diagram of a tab in another embodiment of the present utility model;

[0029] Explanation of the reference numerals in the drawings:

[0030] Label Name Label Name 100 Composite current collector 200 Active material layer 300 Tab 110 Coated area 120 Empty foil area 101 First conductive layer 102 Substrate layer 103 Second conductive layer 121 Non-cutting area 122 First cutting area 123 Second cutting area 122F First folding part 123F Second folding part K1 First cutting hole K2 Second cutting hole 310 Welding part

[0031] The realization, functional features and advantages of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0032] The following will clearly and completely describe the solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0034] It should also be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time.

[0035] In addition, the descriptions involving "first", "second", etc. in the present utility model are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions appears to be contradictory or unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0036] An electrode tab is proposed in the embodiments of the present utility model, referring to Figure 1 and Figure 2, the electrode includes: a composite current collector 100, an active material layer 200, and a tab 300; the composite current collector 100 has a coating area 110 and a bare foil area 120 arranged in sequence along its length direction. Both the coating area 110 and the bare foil area 120 include a first conductive layer 101, a substrate layer 102, and a second conductive layer 103 arranged in a stacked manner. The bare foil area 120 is at least divided into a non-cutting area 121, a first cutting area 122, and a second cutting area 123. The first cutting area 122 and the second cutting area 123 are respectively folded inward from both ends of the non-cutting area 121 to correspondingly form a first folding portion 122F and a second folding portion 123F. The first folding portion 122F extends into the folding space of the second folding portion 123F and is at least partially overlapped with the second folding portion 123F; the active material layer 200 is disposed on the first conductive layer 101 and / or the second conductive layer 103 of the coating area 110; the tab 300 is clamped between the first conductive layer 101 at the first folding portion 122F and the second conductive layer 103 at the second folding portion 123F. The tab 300 is respectively connected to the first conductive layer 101 at the first folding portion 122F and the second conductive layer 103 at the second folding portion 123F, so that the first conductive layer 101 and the second conductive layer 103 are electrically connected.

[0037] The electrode involved in this embodiment can be a positive electrode or a negative electrode, and there is no limitation in this regard. The electrode is applied to an electric core, and the electrode, another electrode with the opposite polarity thereto, and a separator, etc. are combined to form an electric core.

[0038] In this electrode, the composite current collector 100 has a coating area 110 and a bare foil area 120. Taking the length direction of the composite current collector 100 as a reference direction, the coating area 110 and the bare foil area 120 are arranged in sequence, and the bare foil area 120 is located on one side of the coating area 110. Moreover, the composite current collector 100 has a multi-layer structure. Both the coating area 110 and the bare foil area 120 of the composite current collector 100 include a first conductive layer 101, a substrate layer 102, and a second conductive layer 103. The substrate layer 102 is a polymer layer, such as a PE polyethylene polymer layer or a PP polypropylene polymer layer, etc. The first conductive layer 101 and the second conductive layer 103 are metal conductive layers, such as metal layers like an aluminum layer, a copper layer, a nickel layer, etc., or other alloy layers, etc. Moreover, the first conductive layer 101 and the second conductive layer 103 can be the same metal or different metals.

[0039] The active material layer 200 is disposed in the coating area 110 of the composite current collector 100. Correspondingly, the bare foil area 120 of the composite current collector 100 is not coated with the active material. The active material layer 200 may be provided with one layer, and this active material layer 200 is coated on the first conductive layer 101 of the coating area 110 or coated on the second conductive layer 103 of the coating area 110; alternatively, the active material layer 200 may be provided with two layers, one active material layer 200 is coated on the first conductive layer 101 of the coating area 110, and the other active material layer 200 is coated on the second conductive layer 103 of the coating area 110.

[0040] Among them, as Figure 1 and Figure 2 shown, the bare foil area 120 is divided into regions, and at least divided into a non-cutting region 121, a first cutting region 122, and a second cutting region 123. The non-cutting region 121 is located between the first cutting region 122 and the second cutting region 123, and the first cutting region 122 and the second cutting region 123 are separated by the intermediate non-cutting region 121. Within the area of the bare foil area 120, in addition to the divided non-cutting region 121, first cutting region 122, and second cutting region 123, other regions may also be included, and no restrictions are imposed on this. The cutting methods of the first cutting region 122 and the second cutting region 123 may be knife cutting, laser cutting, etc., and no restrictions are imposed on this. As Figure 1 shown, the first cutting region 122 is folded from one end of the non-cutting region 121 to correspondingly form a first folding portion 122F, and the second cutting region 123 is folded from the other end of the non-cutting region 121 to correspondingly form a second folding portion 123F. Among them, the first cutting region 122 and the second cutting region 123 are folded towards each other, that is, the first cutting region 122 is folded towards the direction where the second cutting region 123 is located, and the second cutting region 123 is folded towards the direction where the first cutting region 122 is located, so that the formed first folding portion 122F and the second folding portion 123F are overlapped in alignment.

[0041] Specifically, the first folding portion 122F extends into the folding space of the second folding portion 123F and is at least partially overlapped with the second folding portion 123F. That is, the first cutting region 122 is first folded to form the first folding portion 122F, one side of the first folding portion 122F faces the non-cutting region 121, the second cutting region 123 is then folded to form the second folding portion 123F and covers the first folding portion 122F, and the other side of the first folding portion 122F faces the second folding portion 123F, so that the first folding portion 122F extends into the folding space of the second folding portion 123F and is at the same time in an overlapping relationship with the second folding portion 123F where they are at least partially overlapped.

[0042] On this basis, the tab 300 is clamped between the first conductive layer 101 at the first folding part 122F and the second conductive layer 103 at the second folding part 123F, and is respectively connected to the first conductive layer 101 at the first folding part 122F and the second conductive layer 103 at the second folding part 123F, so that electrical conduction is achieved between the first conductive layer 101 and the second conductive layer 103. In this way, the tab 300 is electrically connected to both the first conductive layer 101 and the second conductive layer 103 at the same time. Both the first conductive layer 101 and the second conductive layer 103 cooperate with the tab 300 to perform charge and discharge, improving the utilization rate of the conductive layers of the composite current collector 100, thereby avoiding waste of materials and occupation of space, and increasing the energy density of the battery cell. Optionally, the connection method between the tab 300 and the first conductive layer 101 at the first folding part 122F can be a welding connection, and the connection method between the tab 300 and the second conductive layer 103 at the second folding part 123F can be a welding connection.

[0043] It should be noted that the so-called electrical conduction between the first conductive layer 101 and the second conductive layer 103 refers to the electrical conduction of the first conductive layer 101 and the second conductive layer 103 in the coating area 110 and the first conductive layer 101 and the second conductive layer 103 in the bare foil area 120.

[0044] In some embodiments, the width of the non-cutting area 121 is greater than the width of the tab 300. In this embodiment, by setting the width of the non-cutting area 121 to be greater than the width of the tab 300, the folding width of the first folding part 122F and the second folding part 123F corresponding to the non-cutting area 121 is greater than the width of the tab 300 when they are folded, so that the tab 300 can be accommodated and adapted, realizing the connection setting between the first folding part 122F and the second folding part 123F and the tab 300.

[0045] And / or, in some embodiments, the width of the folded portion of the first folding portion 122F and the width of the folded portion of the second folding portion 123F are both smaller than the width of the non-cutting area 121; in this embodiment, the width direction of the folded portion of the first folding portion 122F, the width direction of the folded portion of the second folding portion 123F, and the width direction of the non-cutting area 121 are the same as the length direction of the composite current collector 100. Among them, by making the width of the folded portion of the first folding portion 122F smaller than the width of the non-cutting area 121, thus, the extending position of the first folding portion 122F extending into the folding space of the second folding portion 123F is defined, and a spacing is formed between the outer end of the folded first folding portion 122F and the corner position of the folded second folding portion 123F, so as to avoid structural interference with the second folding portion 123F. And, the width of the folded portion of the second folding portion 123F is smaller than the width of the non-cutting area 121, thus, the folding position of the second folding portion 123F is defined, so that a relatively wide folding space is formed inside for the arrangement of the first folding portion 122F, such that a spacing is formed between the corner position of the folded second folding portion 123F and the outer end of the folded first folding portion 122F, so as to avoid structural interference with the first folding portion 122F.

[0046] And / or, in some embodiments, the width of the overlapping portion of the first folding portion 122F and the second folding portion 123F is greater than the width of the tab 300. In this embodiment, by setting the width of the overlapping portion of the first folding portion 122F and the second folding portion 123F to be greater than the width of the tab 300, when the tab 300 is clamped between the first folding portion 122F and the second folding portion 123F, in the common width direction, the tab 300 can be completely welded to the first folding portion 122F and the second folding portion 123F, realizing the maximization of the connection width of the tab 300, thereby ensuring the connection strength of the tab 300 and enhancing the connection stability between the tab 300 and the first folding portion 122F and the second folding portion 123F.

[0047] In some embodiments, the positive projection of the end of the first folding portion 122F in the thickness direction of the composite current collector 100 is located within the non-cutting area 121;

[0048] The positive projection of the end of the second folding portion 123F in the thickness direction of the composite current collector 100 is located within the non-cutting area 121.

[0049] In this embodiment, the positive projection of the end of the first folding portion 122F in the thickness direction of the composite current collector 100 is located within the non-cutting area 121, that is, the extending position of the end of the first folding portion 122F in the folding space of the second folding portion 123F does not exceed the area where the non-cutting area 121 is located. A spacing is formed between the end of the first folding portion 122F and the inner corner of the second folding portion 123F, so as to avoid structural interference with the second folding portion 123F. At the same time, the positive projection of the end of the second folding portion 123F in the thickness direction of the composite current collector 100 is located within the non-cutting area 121, that is, the extending position of the end of the second folding portion 123F does not exceed the area where the non-cutting area 121 is located, so as to form a relatively wide folding space inside itself for arranging the first folding portion 122F, so that a spacing is formed between the inner corner of the second folding portion 123F and the end of the first folding portion 122F, so as to avoid structural interference with the first folding portion 122F.

[0050] In some embodiments, after the first cutting area 122 of the empty foil area 120 is folded, a first cutting hole K1 is formed. The first cutting hole K1 has a plurality of first inner corners, and all the plurality of first inner corners are chamfered. The first cutting hole K1 penetrates through the empty foil area 120 and has the same contour shape as the first cutting area 122. For example, the first cutting hole K1 is a square hole and has four first inner corners, and the four first inner corners are respectively distributed at the four corners of the first cutting hole K1 and are all chamfered. Among them, the chamfer can be a rounded corner, etc. By chamfering each first inner corner of the first cutting hole K1, it is beneficial to reduce the stress concentration at the inner corner position of the first cutting hole K1, and the stress can be better dispersed and balanced. And / or, in some embodiments, after the second cutting area 123 of the empty foil area 120 is folded, a second cutting hole K2 is formed. The second cutting hole K2 has a plurality of second inner corners, and all the plurality of second inner corners are chamfered. The second cutting hole K2 penetrates through the empty foil area 120 and has the same contour shape as the second cutting area 123. For example, the second cutting hole K2 is a square hole and has four second inner corners, and the four second inner corners are respectively distributed at the four corners of the second cutting hole K2 and are all chamfered. Among them, the chamfer can be a rounded corner, etc. By chamfering each second inner corner of the second cutting hole K2, it is beneficial to reduce the stress concentration at the inner corner position of the second cutting hole K2, and the stress can be better dispersed and balanced.

[0051] In some embodiments, the first cutting area 122, the non-cutting area 121, and the second cutting area 123 are located at the edge position of the empty foil area 120 along the length direction of the composite current collector 100; or,

[0052] The first cutting area 122, the non-cutting area 121, and the second cutting area 123 are located at the edge position of the empty foil area 120 along the width direction of the composite current collector 100.

[0053] In the empty foil area, the positions of the first cutting area 122, the non-cutting area 121, and the second cutting area 123 can be set in multiple places. For example, the first cutting area 122, the non-cutting area 121, and the second cutting area 123 can be set at the edge positions of the empty foil area 120 along the length direction of the composite current collector 100. Also, for example, the first cutting area 122, the non-cutting area 121, and the second cutting area 123 can be set at the edge positions of the empty foil area 120 along the width direction of the composite current collector 100. Among them, when the first cutting area 122, the non-cutting area 121, and the second cutting area 123 are set at the edge positions of the empty foil area 120, the first cutting area 122 and the second cutting area 123 are formed by cutting inward from the edge line of the empty foil area 120.

[0054] As a preferred solution, as Figure 2 shown, the first cutting area 122, the non-cutting area 121, and the second cutting area 123 can be set at the edge positions of the empty foil area 120 along the length direction of the composite current collector 100, which has less impact on the tensile strength of the pole piece compared to being set at other positions.

[0055] In some embodiments, referring to Figure 2 , the pole ear 300 has a welding portion 310 for welding connection with the first conductive layer 101 at the first folding portion 122F and the second conductive layer 103 at the second folding portion 123F;

[0056] The lengths of both the first folding portion 122F and the second folding portion 123F are greater than the length of the welding portion 310, and the lengths of both the first folding portion 122F and the second folding portion 123F are less than 1 / 4 of the width of the composite current collector 100.

[0057] In this embodiment, the pole ear 300 extends between the first folding portion 122F and the second folding portion 123F through its welding portion 310 and is welded to the first conductive layer 101 at the first folding portion 122F and the second conductive layer 103 at the second folding portion 123F. Among them, by setting the lengths of both the first folding portion 122F and the second folding portion 123F to be greater than the length of the welding portion 310, when the welding portion 310 of the pole ear 300 is clamped between the first folding portion 122F and the second folding portion 123F, in the common length direction, the welding portion 310 of the pole ear 300 can be fully welded to the first folding portion 122F and the second folding portion 123F, maximizing the welding length of the welding portion 310 of the pole ear 300, thereby ensuring the welding strength of the pole ear 300 and enhancing the connection stability between the pole ear 300 and the first folding portion 122F and the second folding portion 123F.

[0058] Meanwhile, the lengths of the first folding portion 122F and the second folding portion 123F are both less than 1 / 4 of the width of the composite current collector 100. That is, in the width direction of the composite current collector 100, the first cutting area 122 and the second cutting area 123 are both cut with relatively small lengths, so as to prevent the structural strength of the composite current collector 100 from being affected due to excessive cutting lengths of the first cutting area 122 or the second cutting area 123, and to prevent the pole piece from breaking.

[0059] In some embodiments, the tensile strength of the tab 300 welded to the first conductive layer 101 is greater than the peel strength of the first conductive layer 101 from the substrate layer 102. Here, the tensile strength of the tab 300 welded to the first conductive layer 101 refers to the maximum tensile force that the tab 300 and the first conductive layer 101 can withstand after welding. When the external tensile force applied to the tab 300 is less than the tensile strength of the tab 300 welded to the first conductive layer 101, the tab 300 will not detach from the first conductive layer 101. When the external tensile force applied to the tab 300 is greater than the tensile strength of the tab 300 welded to the first conductive layer 101, the tab 300 will detach from the first conductive layer 101. The peel strength of the first conductive layer 101 from the substrate layer 102 refers to the force value at which the first conductive layer 101 peels off from the substrate layer 102. When the peeling force applied to the first conductive layer 101 reaches this force value, the first conductive layer 101 will peel off from the substrate layer 102. In this embodiment, by setting the tensile strength of the tab 300 welded to the first conductive layer 101 to be greater than the peel strength of the first conductive layer 101 from the substrate layer 102, when the tab 300 is subjected to an external force and the external force is large, first, the first conductive layer 101 will peel off from the substrate layer 102, and the tab 300 will not detach from the first conductive layer 101, thus ensuring the welding strength of the tab 300. And / or, the tensile strength of the tab 300 welded to the second conductive layer 103 is greater than the peel strength of the second conductive layer 103 from the substrate layer 102. Here, the tensile strength of the tab 300 welded to the second conductive layer 103 refers to the maximum tensile force that the tab 300 and the second conductive layer 103 can withstand after welding. When the external tensile force applied to the tab 300 is less than the tensile strength of the tab 300 welded to the second conductive layer 103, the tab 300 will not detach from the second conductive layer 103. When the external tensile force applied to the tab 300 is greater than the tensile strength of the tab 300 welded to the second conductive layer 103, the tab 300 will detach from the second conductive layer 103. The peel strength of the second conductive layer 103 from the substrate layer 102 refers to the force value at which the second conductive layer 103 peels off from the substrate layer 102. When the peeling force applied to the second conductive layer 103 reaches this force value, the second conductive layer 103 will peel off from the substrate layer 102. In this embodiment, by setting the tensile strength of the tab 300 welded to the second conductive layer 103 to be greater than the peel strength of the second conductive layer 103 from the substrate layer 102, when the tab 300 is subjected to an external force and the external force is large, first, the second conductive layer 103 will peel off from the substrate layer 102, and the tab 300 will not detach from the second conductive layer 103, thus ensuring the welding strength of the tab 300.

[0060] In some embodiments, the thickness of the tab 300 is greater than or equal to the thickness of the composite current collector 100. By setting the thickness of the tab 300 to be greater than or less than the thickness of the composite current collector 100, sufficient strength is ensured during the welding of the electrode tab and the composite current collector 100, thereby improving the welding stability of the tab 300.

[0061] An embodiment of the present invention further provides an electric core, which includes a positive electrode tab, a negative electrode tab, and a separator disposed between the positive electrode tab and the negative electrode tab;

[0062] Wherein, at least one of the positive electrode tab and the negative electrode tab is an electrode tab as described in the foregoing embodiments.

[0063] Specifically, it may be that the positive electrode tab adopts the foregoing electrode tab, or the negative electrode tab adopts the foregoing electrode tab, or both the positive electrode tab and the negative electrode tab adopt the foregoing electrode tab.

[0064] For the specific structure of the electrode tab, reference may be made to the above embodiments. Since this electric core adopts all the technical solutions of the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0065] An embodiment of the present invention further provides a battery, which includes a housing and an electric core as described in the foregoing embodiments, and the electric core is disposed in the housing. For the specific structure of this electric core, reference may be made to the above embodiments. Since this battery adopts all the technical solutions of the above embodiments, it at least has all the technical effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one. Among them, the type of the battery may be a lithium battery.

[0066] The above are only partial or preferred embodiments of the present invention. Whether in terms of words or drawings, the scope of protection of the present invention cannot be limited thereby. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the overall concept of the present invention, or any direct / indirect application in other related technical fields is included in the scope of protection of the present invention.

Claims

1. A pole piece, characterized in that, Comprising: A composite current collector, the composite current collector having a coated area and a bare foil area arranged in sequence along its length direction, both the coated area and the bare foil area including a first conductive layer, a substrate layer, and a second conductive layer arranged in a stacked manner, the bare foil area being at least divided into a non-cutting area, a first cutting area, and a second cutting area, the first cutting area and the second cutting area being respectively folded from both ends of the non-cutting area towards each other to correspondingly form a first folding portion and a second folding portion, the first folding portion extending into the folding space of the second folding portion and being at least partially overlapped with the second folding portion; An active material layer, the active material layer being disposed on the first conductive layer of the coated area and / or the second conductive layer of the coated area; A tab, the tab being clamped between the first conductive layer at the first folding portion and the second conductive layer at the second folding portion, the tab being respectively connected to the first conductive layer at the first folding portion and the second conductive layer at the second folding portion, such that electrical conduction is achieved between the first conductive layer and the second conductive layer.

2. The electrode tab according to claim 1, wherein, The width of the non-cutting area is greater than the width of the tab; and / or, The widths of the folded portions of the first folding portion and the second folding portion are both less than the width of the non-cutting area; and / or, The width of the overlapping portion of the first folding portion and the second folding portion is greater than the width of the tab.

3. The pole piece according to claim 1, wherein The projection of the end of the first folding portion in the thickness direction of the composite current collector is located within the non-cutting area; The projection of the end of the second folding portion in the thickness direction of the composite current collector is located within the non-cutting area.

4. The electrode tab according to claim 1, characterized in that, After the first cutting area of the bare foil area is folded, a first cutting hole is formed, the first cutting hole having a plurality of first inner corners, and all of the plurality of first inner corners are chamfered; and / or, After the second cutting area of the bare foil area is folded, a second cutting hole is formed, the second cutting hole having a plurality of second inner corners, and all of the plurality of second inner corners are chamfered.

5. The pole piece according to claim 1, characterized in that, The first cutting area, the non-cutting area, and the second cutting area are located at the edge position of the bare foil area along the length direction of the composite current collector; or, The first cutting area, the non-cutting area, and the second cutting area are located at the edge position of the bare foil area along the width direction of the composite current collector.

6. The electrode sheet according to claim 1, wherein The tab has a welding portion for welding connection with the first conductive layer at the first folding portion and the second conductive layer at the second folding portion; The lengths of both the first folding portion and the second folding portion are greater than the length of the welding portion, and the lengths of both the first folding portion and the second folding portion are less than 1 / 4 of the width of the composite current collector.

7. The pole piece according to claim 1, characterized in that The tensile force value of the welding of the tab with the first conductive layer is greater than the peeling force value of the first conductive layer from the substrate layer; and / or, The tensile force value of the welding of the tab with the second conductive layer is greater than the peeling force value of the second conductive layer from the substrate layer.

8. The pole piece according to claim 1, wherein, The thickness of the tab is greater than or equal to the thickness of the composite current collector.

9. A battery cell, characterized in that, Including a positive electrode tab, a negative electrode tab, and a separator, the separator being disposed between the positive electrode tab and the negative electrode tab; Wherein, at least one of the positive electrode sheet and the negative electrode sheet adopts the electrode sheet described in any one of claims 1 to 8.

10. A battery, characterized in that, It includes a housing and the battery cell described in claim 9, and the battery cell is disposed in the housing.

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