Pole piece structure and single battery

Abstract

The utility model relates to the technical field of battery pole pieces, and discloses a pole piece structure and a single battery, the pole piece structure has a length direction, a width direction and a thickness direction, the pole piece structure comprises a current collector, a first active layer and a second active layer, and the current collector has a first side surface and a second side surface opposite to each other along the thickness direction; the first active layer is coated on the first side surface, a first groove is formed in the first active layer, and the first side surface forms a tab connecting part corresponding to the first groove; the second active layer is coated on the second side surface, and a second groove is formed in the second active layer; the first grooves and the second grooves are distributed in a staggered manner in the length direction, and / or the first grooves and the second grooves are distributed in a staggered manner in the width direction; transition structures are arranged on the edges of the first groove and the second groove; the thickness of the transition structure is gradually reduced along the length direction and close to the inner side of the groove, so that smooth transition between the active layer and the current collector at the edge of the groove position is ensured, the ductility difference of the pole piece structure at the edge of the groove position is reduced, and pole piece cracking and belt breakage caused by rolling are effectively prevented.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery pole piece technical field, especially a kind of pole piece structure and single cell. BACKGROUND

[0002] In order to improve the charging speed of battery, the battery pole piece will generally use the design form of tab centering or multiple tabs. At present, high-energy laser technology is used to clean and remove the active coating of the pole piece, thereby forming a tab welding groove on the local surface of the pole piece foil.

[0003] With the continuous increase of battery energy density, the thickness of the pole piece foil is becoming thinner, and the coating and compaction density are also increasing. However, during the rolling process, there is a difference in extension between the active coating and the pole piece foil in the groove area, which can easily cause the pole piece to crack and break. SUMMARY

[0004] The technical problem to be solved by the utility model is that, during the rolling process, due to the difference in extension between the active coating and the pole piece foil in the groove area, the pole piece is prone to cracking and breaking.

[0005] To solve the above technical problems, the utility model provides a technical scheme of a pole piece structure:

[0006] The pole piece structure has length direction, width direction and thickness direction intersecting with each other, and includes:

[0007] The current collector has a first side and a second side opposite along the thickness direction;

[0008] The first active layer is coated on the first side, and the first active layer is provided with a first groove, and the first side forms a tab connecting part corresponding to the first groove;

[0009] The second active layer is coated on the second side, and the second active layer is provided with a second groove;

[0010] The first groove and the second groove are distributed in staggered positions in the length direction, and / or the first groove and the second groove are distributed in staggered positions in the width direction;

[0011] The edges of the first groove and the edges of the second groove are provided with a transition structure; along the length direction and close to the inner side of the groove, the thickness of the transition structure gradually decreases.

[0012] Further, the first groove has a first excess material edge close to the length edge of the current collector, and the second groove has a second excess material edge close to the length edge of the current collector.

[0013] Further, the first slot further has two first side edges opposite along the length direction, and the second slot further has two second side edges opposite along the length direction; in the length direction, at least one of the first side edges is arranged apart from at least one of the second side edges.

[0014] Further, the maximum distance between the two first side edges in the length direction is D1, the size of the tab connecting part in the length direction is D2, and the distance between the first side edge and the second side edge in the length direction is d1, which satisfies d1≤(D1-D2) / 2.

[0015] Further, the distance between the first side edge and the second side edge in the length direction is d1, which satisfies 0.1mm≤d1≤3mm.

[0016] Further, the first slot further has a first bottom edge away from the first excess material edge along the width direction, and the second slot further has a second bottom edge away from the second excess material edge along the width direction; in the width direction, the first bottom edge is arranged apart from the second bottom edge.

[0017] Further, the distance between the first bottom edge and the second bottom edge in the width direction is d2, which satisfies 0.2mm≤d2≤2mm.

[0018] Further, the transition structure includes at least two stepped portions, and the at least two stepped portions are arranged apart from each other in the thickness direction away from the tab connecting part.

[0019] Further, the transition structure further includes a chamfer portion, and the chamfer portion is arranged on the side of the stepped portion away from the current collector.

[0020] Further, the opening width of the first slot is greater than the opening width of the second slot.

[0021] Further, the tab connecting part is provided with a tab, and the thickness of the tab is H; in the length direction, the minimum distance between the tab and the first slot edge is L1, and the minimum distance between the projection of the tab and the second slot edge is L2, which satisfies: H

[0022] To solve the above technical problems, the utility model provides a kind of single battery technical scheme:

[0023] Single battery, comprising: pole piece structure;

[0024] Pole piece structure, with length direction, width direction and thickness direction intersecting each other, comprising:

[0025] A current collector having a first side surface and a second side surface opposite each other along the thickness direction;

[0026] A first active layer is coated on the first side surface, and a first groove is formed in the first active layer. A tab connection portion is formed on the first side surface corresponding to the first groove.

[0027] A second active layer is coated on the second side surface, and the second active layer has a second groove.

[0028] The first slot and the second slot are staggered in the length direction, and / or the first slot and the second slot are staggered in the width direction;

[0029] The edges of the first groove and the second groove are provided with transition structures; along the length direction and near the inside of the groove, the thickness of the transition structure gradually decreases.

[0030] Furthermore, the first groove has a first excess material edge near the length edge of the current collector, and the second groove has a second excess material edge near the length edge of the current collector.

[0031] Furthermore, the first groove also has two first sides opposite each other along the length direction, and the second groove also has two second sides opposite each other along the length direction; in the length direction, at least one first side and at least one second side are arranged at intervals.

[0032] Furthermore, the maximum distance between the two first sides in the length direction is D1, the dimension of the tab connection in the length direction is D2, and the distance between the first side and the second side in the length direction is d1, satisfying d1≤(D1-D2) / 2.

[0033] Furthermore, the distance between the first side and the second side in the length direction is d1, which satisfies 0.1mm≤d1≤3mm.

[0034] Furthermore, the first groove also has a first bottom edge that is away from the first surplus material edge along the width direction, and the second groove also has a second bottom edge that is away from the second surplus material edge along the width direction; the first bottom edge and the second bottom edge are arranged at intervals in the width direction.

[0035] Furthermore, the distance between the first bottom edge and the second bottom edge in the width direction is d2, which satisfies 0.2mm≤d2≤2mm.

[0036] Furthermore, the transition structure includes at least two stepped portions, which are arranged at intervals along the thickness direction, gradually moving away from the tab connection portion.

[0037] Furthermore, the transition structure also includes a chamfered portion, which is located on the side of the stepped portion away from the current collector.

[0038] Furthermore, the opening width of the first groove is greater than the opening width of the second groove.

[0039] Furthermore, the electrode connection portion is provided with an electrode tab, the thickness of which is H; along the length direction, the minimum distance between the electrode tab and the edge of the first groove is L1, and the minimum distance between the projection of the electrode tab and the edge of the second groove is L2, satisfying: H < L2 < 1.5 * H, L2 < L1 < 2 * L2.

[0040] Compared with the prior art, the electrode structure and single cell of this utility model have the following advantages: the electrode structure adopts a current collector, a first active layer and a second active layer. The current collector has a first side and a second side opposite to each other along the thickness direction. The first active layer is coated on the first side and the second active layer is coated on the second side. The first active layer and the second active layer can improve the conductivity of the electrode structure, reduce the internal resistance of the battery, and thus improve the overall performance of the single cell.

[0041] The first active layer has a first groove, and a tab connection portion for matching the tab is reserved on the first side corresponding to the first groove. This enables electrical connection between the tab and the first side of the current collector, and allows the tab to be smoothly led out of the current collector along the width direction. Correspondingly, the second active layer has a second groove. The first groove and the second groove are staggered in the length direction, and / or staggered in the width direction. It is precisely this staggered arrangement of the first groove and the second groove in the planar direction that reduces the thickness difference between the current collector and the active layer near the tab groove.

[0042] Meanwhile, transition structures are provided at the edges of both the first and second slots. Along the length direction X and close to the inner side of the slot, the thickness of these transition structures gradually decreases, ensuring a smooth transition between the active layer and the current collector at the slot edges. This reduces the difference in ductility of the electrode structure at the slot edges, effectively preventing electrode cracking and strip breakage due to ductility differences during rolling. Furthermore, it reduces the cleaning area of ​​the slot markings, which helps reduce dust generation and improves Hi-pot throughput and K-value yield. Simultaneously, the misalignment of the slot markings on both sides helps reduce the difference in cell thickness, avoiding lithium plating during cycling. Attached Figure Description

[0043] Figure 1 This is a cross-sectional schematic diagram of the electrode structure in the thickness direction in an embodiment of this utility model;

[0044] Figure 2 yesFigure 1 A top view of the mid-electrode structure;

[0045] Figure 3 This is a cross-sectional schematic diagram of the electrode structure in the thickness direction in another embodiment of this utility model;

[0046] Figure 4 yes Figure 3 A top view of the mid-electrode structure;

[0047] Figure 5 This is a top view schematic diagram of the electrode structure in another embodiment two of this utility model;

[0048] Figure 6 This is a cross-sectional schematic diagram of the electrode structure in the thickness direction in another embodiment three of this utility model;

[0049] In the figure: 1-current collector, 11-first side surface, 12-second side surface, 2-first active layer, 20-first groove, 200-tab connection part, 21-first side edge, 22-first excess material edge, 23-first bottom edge, 24-transition structure, 241-step part, 242-chamfer part, 3-second active layer, 30-second groove, 31-second side edge, 32-second excess material edge, 33-second bottom edge, 4-tab, X-length direction, Y-width direction, Z-thickness direction. Detailed Implementation

[0050] The specific embodiments of this utility model will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate this utility model, but are not intended to limit its scope.

[0051] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or component 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 this utility model.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0053] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood according to the specific circumstances.

[0054] like Figure 1 , Figure 2 As shown, an electrode structure of this utility model has two intersecting length directions X, width directions Y and thickness directions Z, including: a current collector 1, a first active layer 2 and a second active layer 3. The current collector 1 has a first side surface 11 and a second side surface 12 that are opposite each other along the thickness direction Z. The first active layer 2 is coated on the first side surface 11 and has a first groove 20. The first side surface 11 forms an electrode tab connection portion 200 corresponding to the first groove 20.

[0055] The second active layer 3 is coated on the second side surface 12, and the second active layer 3 has a second groove 30; the first groove 20 and the second groove 30 are staggered in the length direction X, and / or the second groove 30 and the second groove 30 are staggered in the width direction Y; the edges of the first groove 20 and the edges of the second groove 30 are provided with transition structures 24, which are located along the length direction X and close to the inside of the groove, and the thickness of the transition structure 24 gradually decreases.

[0056] The electrode structure adopts a current collector 1, a first active layer 2 and a second active layer 3. The current collector 1 has a first side 11 and a second side 12 opposite to each other along the thickness direction Z. The first active layer 2 is coated on the first side 11 and the second active layer 3 is coated on the second side 12. The first active layer 2 and the second active layer 3 can improve the conductivity of the electrode structure, reduce the internal resistance of the battery, and thus improve the overall performance of the single cell.

[0057] The first active layer 2 has a first groove 20, and a tab connection portion 200 for matching the tab is reserved on the first side 11 corresponding to the first groove 20. This enables electrical connection between the tab and the first side 11 of the current collector 1, and allows the tab to be smoothly led out of the current collector 1 along the width direction Y. Correspondingly, the second active layer 3 has a second groove 30. The first groove 20 and the second groove 30 are staggered in the length direction X, and / or, the first groove 20 and the second groove 30 are staggered in the width direction Y. It is precisely because the first groove 20 and the second groove 30 are staggered in the planar direction that the thickness difference between the current collector 1 and the active layer near the tab groove is reduced.

[0058] Meanwhile, transition structures 24 are provided at the edges of the first groove 20 and the second groove 30, along the length direction X and close to the inner side of the groove. The thickness of the transition structure 24 gradually decreases, ensuring a smooth transition between the active layer and the current collector 1 at the edge of the groove. This reduces the difference in ductility of the electrode structure at the edge of the groove, effectively preventing electrode cracking and strip breakage due to ductility differences during rolling. Furthermore, it reduces the cleaning area of ​​the groove markings, which helps reduce dust generation and improve Hi-pot throughput and K-value yield. At the same time, the misalignment of the groove markings on both sides helps to reduce the difference in cell thickness and avoid lithium plating during cycling.

[0059] In this embodiment, the first groove 20 has a first excess material edge 22 near the length edge of the current collector 1, and the second groove 30 has a second excess material edge 32 near the length edge of the current collector 1. Specifically, the width of the first excess material edge 22 and the second excess material edge 32 is designed to be any size between 0.1 mm and 1 mm.

[0060] Furthermore, the first groove 20 also has two opposing first sides 21 along the length direction X, and the second groove 30 also has two opposing second sides 31 along the length direction X; in the length direction X, at least one first side 21 and at least one second side 31 are arranged at intervals. As a further preferred embodiment, one first side 21 and the corresponding second side 31 are arranged at intervals along the length direction X, and the other first side 21 and the other second side 31 are arranged coincidentally along the length direction X. The first groove 20 and the second groove 30 have one side misaligned and the other side flush, which can improve the electrode damage caused by the difference in ductility.

[0061] To meet different usage requirements, another embodiment of the electrode structure of this utility model differs from the above embodiment in that the two first side edges 21 and the two second side edges 31 are arranged at intervals along the length direction X, such as... Figure 3 , Figure 4 As shown, the first groove 20 and the second groove 30 are designed with the two sides offset, which can also protect the electrode sheet during the rolling process.

[0062] The maximum distance between the two first side edges 21 in the length direction X is D1, the dimension of the electrode connecting part 200 in the length direction X is D2, and the distance between the first side edge 21 and the second side edge 31 in the length direction X is d1, satisfying d1≤(D1-D2) / 2. By controlling the misalignment range of the first groove 20 and the second groove 30 to be moderate, the electrode connecting part 200 is aligned along the length direction X, ensuring the accuracy of the electrode welding position.

[0063] Specifically, the distance d1 between the first side 21 and the second side 31 in the length direction X satisfies 0.1mm ≤ d1 ≤ 3mm. For example, the distance d1 between the first side 21 and the second side 31 in the length direction X can be selected as 0.1mm, 0.2mm, 0.5mm, 1mm, 2mm, 3mm, or any other size between 0.1mm and 3mm. If the distance is too small, it will be difficult to effectively protect the electrode sheet during the rolling process.

[0064] Furthermore, the first groove 20 also has a first bottom edge 23 that is away from the first surplus material edge 22 along the width direction Y, and the second groove 30 also has a second bottom edge 33 that is away from the second surplus material edge 32 along the width direction Y. The first bottom edge 23 and the second bottom edge 33 are arranged to coincide in the width direction Y.

[0065] Other embodiments of the electrode structure of this utility model, such as Figure 5 As shown, the two first sides 21 of the first groove 20 and the two second sides 31 of the second groove 30 are arranged at intervals along the length direction X, and the first groove 20 and the second groove 30 are designed with staggered sides. Furthermore, the first groove 20 also has a first bottom edge 23 that is away from the first excess material edge 22 along the width direction Y, and the second groove 30 also has a second bottom edge 33 that is away from the second excess material edge 32 along the width direction Y; the first bottom edge 23 and the second bottom edge 33 are arranged at intervals along the width direction Y. Specifically, the distance between the first bottom edge 23 and the second bottom edge 33 in the width direction Y is d2, satisfying 0.2mm≤d2≤2mm. The second groove 20 and the second groove 30 are also staggered in the width direction Y, increasing the staggered area of ​​the two grooves and further improving the protection effect of the electrode sheet.

[0066] As a further preferred embodiment, the transition structure 24 includes at least two stepped portions 241, which are arranged at intervals along the thickness direction Z, gradually moving away from the tab connection portion 200. This multi-stage stepped portion 241 design achieves a smooth and extensible change in the electrode structure at the groove edge. The transition structure 24 also includes a chamfered portion 242, located on the side of the stepped portion 241 away from the current collector 1. The chamfered portion 242 improves the structural smoothness of the groove edge, preventing the risk of punctures due to sharp corners during the rolling process.

[0067] The transition structure 24 in this design is equivalent to having multiple small steps, making the slot area closer to an arc. Compared to having only one step, the thickness difference is smaller, making the transition smoother and solving the problem of tape breakage, as well as improving Hi-pot throughput and K-value yield. Furthermore, the first slot 20 has a reserved first excess material edge 22, and the second slot 30 has a reserved second excess material edge 32, i.e., stacked without die-cutting. The reserved excess material edges can prevent the risk of tape breakage due to the edge area of ​​the slot being torn during tape transport.

[0068] The statistics of the number of times the band broke during testing are as follows:

[0069] Keeping the winding equipment parameters constant (PPM = 6, i.e., 6 cells produced per minute), the number of tape breaks and the tape travel length (~3000m) during the winding process of different cathode sheets were statistically analyzed and converted to the unit: tape break times / km. Hi-pot defect rate: The produced cells were tested using parameters of 50V / 2MΩ, and the proportion with internal resistance <2MΩ was statistically analyzed. K-value defect rate: The produced cells were tested using the same method (high temperature for 2 days + room temperature for 2 days to measure OCV1 + room temperature for 2 days to measure OCV2), and the proportion with K value >0.06mV / h was statistically analyzed.

[0070]

[0071] Based on the above examples, it can be seen that any two or three of the following three features, when combined: setting a transition structure at the edge of the slot, misaligning the edge of the slot, and die-cutting at the top of the slot (without leaving any excess material edge), can significantly improve the problem of tape breakage and increase the Hi-pot throughput and K-value yield.

[0072] Another embodiment of the electrode structure of this utility model, in three ways, differs from the above embodiments in that, as follows: Figure 6 As shown, the opening width of the first groove 20 is greater than the opening width of the second groove 30, i.e., the larger groove covers the smaller groove. Specifically, the electrode connecting part 200 is provided with an electrode 4, the thickness of which is H; along the length direction X, the minimum distance between the electrode 4 and the edge of the first groove 20 is L1, and the minimum distance between the projection of the electrode 4 and the edge of the second groove 30 is L2, satisfying: H < L2 < 1.5 * H, L2 < L1 < 2 * L2.

[0073] The purpose of its design is to ensure that the tab 4 is accommodated in the first groove 20 along the thickness direction Z of the electrode structure, without wasting too much active material around the second groove 30, thereby improving the cell ED. At the same time, it can also improve the process of preventing strip breakage during production. According to the mechanical principle, the misaligned groove can accelerate the release of edge stress.

[0074] A specific embodiment of the single cell of this utility model includes an electrode structure, wherein the electrode structure is the same as the specific embodiments of the electrode structure in the above-described specific embodiments of the electrode structure of this utility model, and will not be repeated here.

[0075] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present utility model, and these improvements and substitutions should also be considered within the protection scope of the present utility model.

Claims

1. A pole piece structure having a length direction (X), a width direction (Y), and a thickness direction (Z) that intersect each other two by two, characterized by, The application relates to a battery electrode plate, comprising: a current collector (1) having a first side (11) and a second side (12) opposite to each other along a thickness direction (Z); a first active layer (2) coated on the first side (11), the first active layer (2) being provided with a first groove (20), and the first side (11) corresponding to the first groove (20) forming a tab connecting part (200); a second active layer (3) coated on the second side (12), the second active layer (3) being provided with a second groove (30); the first groove (20) and the second groove (30) are distributed in a staggered manner along a length direction (X) and / or a width direction (Y); an edge of the first groove (20) and an edge of the second groove (30) are provided with a transition structure (24), and the thickness of the transition structure (24) gradually decreases along the length direction (X) and close to the inner side of the groove.

2. The pole piece structure of claim 1, wherein The first groove (20) has a first excess material edge (22) close to a length edge of the current collector (1), and the second groove (30) has a second excess material edge (32) close to the length edge of the current collector (1).

3. The pole piece structure of claim 2, wherein The first groove (20) further has two first side edges (21) opposite to each other along the length direction (X), and the second groove (30) further has two second side edges (31) opposite to each other along the length direction (X); at least one of the first side edges (21) and at least one of the second side edges (31) are arranged in a spaced manner along the length direction (X).

4. The pole piece structure of claim 3, wherein The maximum distance between the two first side edges (21) along the length direction (X) is D1, the size of the tab connecting part (200) along the length direction (X) is D2, and the distance between the first side edge (21) and the second side edge (31) along the length direction (X) is d1, which satisfies d1 <= (D1-D2) / 2.

5. The pole piece structure of claim 4, wherein The distance between the first side edge (21) and the second side edge (31) along the length direction (X) is d1, which satisfies 0.1mm <= d1 <= 3mm.

6. The pole piece structure of claim 2, wherein The first groove (20) further has a first bottom edge (23) away from the first excess material edge (22) along the width direction (Y), and the second groove (30) further has a second bottom edge (33) away from the second excess material edge (32) along the width direction (Y); the first bottom edge (23) and the second bottom edge (33) are arranged in a spaced manner along the width direction (Y).

7. The pole piece structure of claim 6, wherein The distance between the first bottom edge (23) and the second bottom edge (33) along the width direction (Y) is d2, which satisfies 0.2mm <= d2 <= 2mm.

8. The pole piece structure of claim 1, wherein, The transition structure (24) comprises at least two stepped portions (241), and the at least two stepped portions (241) are arranged in a spaced manner away from the tab connecting part (200) along the thickness direction (Z).

9. The pole piece structure of claim 8, wherein, The transition structure (24) further comprises a chamfer (242) arranged on the side of the stepped portion (241) away from the current collector (1).

10. The pole piece structure of claim 1, wherein The opening width of the first slot (20) is greater than the opening width of the second slot (30).

11. The pole piece structure of claim 10, wherein, The tab connecting portion (200) is provided with a tab (4), the thickness of the tab (4) is H; along the length direction (X), the minimum distance between the tab (4) and the edge of the first slot (20) is L1, and the minimum distance between the projection of the tab (4) and the edge of the second slot (30) is L2, satisfying: H < L2 < 1.5*H, L2 < L1 < 2*L2.

12. A single cell, characterized by The tab structure comprises the tab structure according to any one of claims 1 to 11. The tab structure comprises the tab structure according to any one of claims 1 to 11.

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