Electrode assembly and lithium ion secondary battery

Abstract

The utility model relates to the technical field of batteries, and discloses an electrode assembly and a lithium ion secondary battery, the electrode assembly comprises: a first pole piece comprising a first current collector and a first active material layer; the first active material layer is provided with a first groove exposed out of the first current collector; the welding end of the first tab is arranged in the first groove, and the first tab is electrically connected with the first current collector; the second pole piece comprises a second current collector and a second active material layer; a second groove is formed in the second active material layer, and the second groove is opposite to the first groove in the third direction; a first adhesive tape and a second adhesive tape which are stacked are arranged on the second groove; the size of the first gummed paper in the first direction is F1, the size of the second gummed paper in the first direction is F2, and F1 is smaller than F2. According to the electrode assembly provided by the utility model, the loss of the energy density of the battery cell caused by thickness accumulation can be prevented under the condition that the gummed paper can be detected.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to an electrode assembly and a lithium-ion secondary battery. Background Technology

[0002] To reduce the internal resistance of the battery cell and improve the charging and discharging speed, the tabs are usually welded to the center of the electrode sheet. However, during the welding process, due to factors such as the inhomogeneity of the welding process and material properties, protrusions often appear at the welding position of the tabs. During the subsequent hot pressing of the battery cell, these protrusions can easily puncture the separator, causing a short circuit between the positive and negative electrodes, which greatly affects the safety and reliability of the battery. Utility Model Content

[0003] In view of this, the present invention provides an electrode assembly and a lithium-ion secondary battery to solve the problem that the protrusion at the electrode tab welding position can easily puncture the separator.

[0004] In a first aspect, this utility model provides an electrode assembly, comprising:

[0005] A first electrode and a second electrode with opposite polarities, and a separator disposed between the first electrode and the second electrode;

[0006] The first electrode includes a first current collector and a first active material layer disposed on the surface of the first current collector; the first active material layer is provided with a first groove exposing the first current collector.

[0007] The first electrode tab has its welding end placed in the first groove, and the first electrode tab is electrically connected to the first current collector.

[0008] The second electrode includes a second current collector and a second active material layer disposed on the surface of the second current collector;

[0009] A second groove is provided on the second active material layer, and the second groove is positioned opposite to the first groove along the third direction.

[0010] The second groove is provided with a first adhesive paper and a second adhesive paper stacked on top of each other. The first adhesive paper is located on the side of the second adhesive paper away from the second current collector. The dimension of the first adhesive paper along the first direction is F1, and the dimension of the second adhesive paper along the first direction is F2, where F1 < F2.

[0011] Beneficial Effects: The electrode assembly provided by this utility model, by setting a second groove on the second active material layer opposite to the first groove, and stacking the first adhesive tape and the second adhesive tape in the second groove, on the one hand, setting two layers of adhesive tape in the second groove can better play a buffering role, preventing the welding protrusion at the first electrode tab from puncturing the separator and causing a short circuit due to compression or collision during battery use; on the other hand, setting two layers of adhesive tape in the second groove has a better heat insulation effect, which can effectively disperse the excessive heat accumulated at the first electrode tab position due to excessive current during battery cycling, which can cause the battery to fail due to localized overheating. The groove can also accommodate at least part of the thickness of the adhesive tape, reducing the thickness accumulation at the first tab position in the battery and preventing the loss of cell energy density caused by the thickness accumulation; the stacked first and second adhesive tapes can also reduce the risk of lithium plating at the first tab position; and the dimension F1 of the first adhesive tape along the first direction is smaller than the dimension F2 of the second adhesive tape along the first direction, so that the second adhesive tape is at least partially located outside the first adhesive tape. This can achieve effective detection of the first and second adhesive tapes set in the second groove, avoiding the risk of missing adhesive tape, ensuring the safety performance of the battery, ensuring the effective setting of the two layers of adhesive tape, ensuring the safety performance of the battery, and improving the energy density of the battery.

[0012] In one alternative implementation, the second groove has a dimension of E1 along the first direction, where E1 satisfies F1 < F2 ≤ E1.

[0013] Beneficial effects: It can detect the second adhesive strip while detecting the first adhesive strip, avoiding the risk of missing adhesive strips and ensuring the safety performance of the battery. It also makes it easy to completely embed the first and second adhesive strips into the second groove, thereby reducing the accumulation of adhesive strip thickness and improving the energy density of the battery.

[0014] In one optional embodiment, the second groove includes a first sub-groove and a second sub-groove, with a first adhesive tape disposed in the first sub-groove and / or the second sub-groove, and a second adhesive tape disposed in the second sub-groove, with at least a portion of the second adhesive tape extending from the second sub-groove into the first sub-groove along a first direction. The first sub-groove includes a first portion connected to the second sub-groove along the first direction, and the second sub-groove is formed by the bottom wall of the first sub-groove being recessed towards the second current collector along a third direction. Along the third direction, the distance from the bottom wall of the second sub-groove to the surface of the second current collector is less than the distance from the bottom wall of the first sub-groove to the surface of the second current collector.

[0015] And / or, along a third direction, the distance from the bottom wall of the first sub-slot to the surface of the second current collector is less than the thickness of the second active material layer in other areas of the single-sided surface of the second electrode plate, excluding the areas where the first and second sub-slots are located.

[0016] And / or, at least a portion of the second sub-slot is an exposed second current collector.

[0017] Beneficial effects: It can detect the second adhesive strip while detecting the first adhesive strip, avoiding the risk of missing adhesive strips and ensuring the safety performance of the battery. It can also accommodate the thickness of the first and second adhesive strips through the first and second sub-slots, thereby ensuring that the first and second adhesive strips are not missed and preventing the loss of cell energy density caused by the accumulation of thickness.

[0018] In one optional implementation, the dimension of the first sub-slot along the first direction is E2, and the dimension of the second sub-slot along the first direction is E3, wherein E2 and E3 satisfy: E2≤E3.

[0019] Beneficial effects: E2≤E3, on the one hand, it can ensure that as much of the stacked first and second adhesive tapes as possible are located in the second sub-groove, which can minimize the cumulative thickness of the adhesive tape in the electrode assembly, improve the overall flatness and energy density of the battery. On the other hand, when the area of ​​the second sub-groove is the exposed second current collector, the adhesion effect between the adhesive tape and the second current collector is better, so that the second adhesive tape can have a larger area to bond with the second current collector, thereby further ensuring the adhesion effect of the second adhesive tape and reducing the risk of the second adhesive tape falling off.

[0020] In one optional embodiment, the first sub-slot further includes a second portion connected to the left side wall of the second sub-slot along the second direction and a third portion connected to the right side wall of the second sub-slot along the second direction. The first portion is connected to the second portion and the third portion respectively to form the first sub-slot. The first sub-slot surrounds the second sub-slot. Along the third direction, the second sub-slot is connected to the first sub-slot. The dimension of the first sub-slot along the first direction is E4, and the dimension of the second sub-slot along the first direction is E5. E4 and E5 satisfy: E4 > E5.

[0021] Beneficial effects: On the one hand, the first and second sub-slots can completely accommodate the first and second adhesive strips, ensuring that the adhesive strips can be detected and preventing the loss of cell energy density caused by thickness accumulation. On the other hand, by having the first adhesive strip cover the first part, the second part, and the third part simultaneously, the projection of the first adhesive strip along the third direction completely covers the second sub-slot. In this way, even if the second current collector is exposed in the second sub-slot, the adhesive strip can still completely cover the exposed second current collector in the second sub-slot, reducing the risk of contact between the two electrodes with opposite polarities and avoiding affecting the safety performance of the battery.

[0022] In one alternative implementation, the dimension W1 of the first sub-slot along the second direction is greater than or equal to the dimension W2 of the second sub-slot along the second direction;

[0023] The dimension of the first adhesive tape along the second direction is W3, and W3 and W2 satisfy: W3≥W2;

[0024] And / or, the dimension of the second adhesive tape along the second direction is W4, and W4 and W2 satisfy: W4≤W2;

[0025] And / or, W3 and W4 satisfy: W4≤W3;

[0026] And / or, W1 and W3 satisfy 1.0 ≤ W1 / W3 ≤ 2.0,

[0027] And / or, the dimension of the first electrode tab along the second direction of the first electrode plate is W5, and W5 and W2 satisfy: W2≥W5.

[0028] Beneficial effects: The dimension W1 of the first sub-slot along the second direction is greater than or equal to the dimension W2 of the second sub-slot along the second direction, ensuring that the two sub-slots can flexibly match the dimensions of the first and second adhesive strips, reducing the loss of active material and improving battery energy density while ensuring battery safety performance; The dimension W3 of the first adhesive strip along the second direction is greater than or equal to the dimension W2 of the second sub-slot along the second direction, thus ensuring that the projection of the first adhesive strip along the third direction completely covers the second sub-slot. This ensures that even if the second current collector is exposed in the second sub-slot, the adhesive strip can completely cover the exposed second current collector, preventing short circuit risk and avoiding affecting battery safety performance; At the same time, the dimension W3 of the first adhesive strip along the second direction and the dimension W1 of the first sub-slot along the second direction satisfy 1.0≤W1 / W3≤2.0, thus ensuring that the thickness of the first adhesive strip is completely hidden in the first sub-slot, further reducing the accumulation of adhesive strip thickness and improving battery energy density. The dimension W4 of the second adhesive tape along the second direction is less than or equal to the dimension W2 of the second sub-groove along the second direction, thereby ensuring that the second adhesive tape can be built into the second sub-groove, ensuring the adhesion effect between the second adhesive tape and the second current collector, while hiding the thickness of the second adhesive tape and improving the energy density of the battery; in addition, the dimension of the first tab along the second direction of the first electrode is W5, and W5 and W2 satisfy: W2≥W5, thereby ensuring that the projection of the first tab is completely located within the second sub-groove, avoiding the first tab being located outside the second sub-groove due to production fluctuations, and avoiding the accumulation of increased thickness.

[0029] In one optional embodiment, the second adhesive tape includes a first segment and a second segment connected to each other along a first direction, the first segment being located in a first sub-groove and the second segment being located in a second sub-groove;

[0030] The distance between the end of the first adhesive tape near the first segment along the first direction and the edge of the first sub-groove away from the first adhesive tape is M, where M satisfies M≥2.0mm.

[0031] Beneficial effects: It provides sufficient space for the second adhesive tape to be inspected, effectively avoiding the risk of missing adhesive tape and ensuring the safety performance of the battery. At the same time, it ensures that the second adhesive tape overlaps with the first sub-slot or the first adhesive tape as little as possible, reducing the area of ​​thickness accumulation in the battery and ensuring the flatness of the battery.

[0032] In one alternative implementation, the dimension of the first segment along the first direction is F3, where F3 satisfies F3≥1.5mm.

[0033] Beneficial effects: This ensures that the second adhesive strip has sufficient protrusion relative to the first adhesive strip for subsequent inspection, thereby effectively avoiding the risk of missed application and ensuring the safety performance of the battery.

[0034] In one alternative embodiment, along the first direction, the second adhesive tape extends beyond the first adhesive tape by a dimension F4, where F4 satisfies F4≥0.3mm.

[0035] Beneficial effects: This ensures the accuracy of the second adhesive tape detection, effectively avoids the risk of missed application, and guarantees the safety performance of the battery.

[0036] In one alternative implementation, when the dimension W1 of the first sub-slot along the second direction is greater than the dimension W2 of the second sub-slot along the second direction, W1 and W2 satisfy W1 / W2=K, 1.1≤K≤2.5.

[0037] Beneficial effects: This allows the first adhesive tape to be completely embedded in the first sub-slot, further reducing the cumulative thickness of the adhesive tape and increasing the energy density of the battery. It also ensures that the projection of the first adhesive tape along a third direction completely covers the second sub-slot. In this way, even if the second current collector is exposed in the second sub-slot, the first and second adhesive tapes can completely cover and double-protect the exposed second current collector, preventing it from coming into contact with the first electrode and causing a short circuit risk, thus avoiding affecting the safety performance of the battery.

[0038] In one alternative implementation, the projection of the welding end of the first electrode along a third direction is completely located within the projection area of ​​the second adhesive tape along a third direction.

[0039] And / or, the projection of the first groove along a third direction is completely located within the projection area of ​​the first adhesive paper along a third direction.

[0040] Beneficial effects: Ensures that the first tab is protected by both the first and second adhesive layers; prevents the first tab from lifting off due to external force or from puncturing the separator due to protrusion of the first tab, thus avoiding battery short circuit failure.

[0041] Secondly, this utility model also provides a lithium-ion secondary battery, including: a packaging shell, and an electrode assembly as described above, wherein the electrode assembly is built into the packaging shell.

[0042] Beneficial effects: The lithium-ion secondary battery of the second aspect includes the electrode assembly of the first aspect, and therefore, the lithium-ion secondary battery of the second aspect includes all the beneficial effects of the electrode assembly of the first aspect. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a top view of the first type of second electrode sheet of the electrode assembly according to an embodiment of the present utility model;

[0045] Figure 2 for Figure 1 A cross-sectional view of the second pole piece shown along a third direction;

[0046] Figure 3 for Figure 1 A top view of the second active material layer of the second electrode shown in the diagram;

[0047] Figure 4 for Figure 1 A top view of the second active material layer of the second electrode and the second adhesive paper shown;

[0048] Figure 5 This is a top view of the second active material layer of the second electrode sheet in an embodiment of the present invention.

[0049] Figure 6 This is a top view of the second type of second electrode sheet of the electrode assembly according to an embodiment of the present utility model;

[0050] Figure 7 This is a cross-sectional view of the electrode assembly along a third direction according to an embodiment of the present invention.

[0051] Explanation of reference numerals in the attached figures:

[0052] 10. First electrode; 11. First current collector; 12. First active material layer; 121. First groove;

[0053] 20. Second electrode; 21. Second current collector; 22. Second active material layer; 220. Second groove; 221. First sub-groove; 2211. First part; 2212. Second part; 2213. Third part; 222. Second sub-groove;

[0054] 30. Separating membrane;

[0055] 40. First pole ear;

[0056] 50. First adhesive tape;

[0057] 60. Second adhesive tape; 61. First section; 62. Second section. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0059] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0060] According to an embodiment of the present invention, in one aspect, an electrode assembly is provided, comprising:

[0061] A first electrode 10 and a second electrode 20 with opposite polarities, and a separator 30 disposed between the first electrode 10 and the second electrode 20;

[0062] Please see Figure 7 As shown, the first electrode 10 includes a first current collector 11 and a first active material layer 12 disposed on the surface of the first current collector 11; the first active material layer 12 is provided with a first groove 121 exposing the first current collector 11;

[0063] The first electrode tab 40 has its welding end placed in the first groove 121, and the first electrode tab 40 is electrically connected to the first current collector 11.

[0064] The second electrode 20 includes a second current collector 21 and a second active material layer 22 disposed on the surface of the second current collector 21;

[0065] A second groove 220 is provided on the second active material layer 22, and the second groove 220 is disposed opposite to the first groove 121 along the third direction;

[0066] The second groove 220 is provided with a first adhesive tape 50 and a second adhesive tape 60 stacked together, with the first adhesive tape 50 disposed on the side of the second adhesive tape 60 facing away from the second current collector 21; please refer to Figure 1 As shown, the dimension of the first adhesive tape 50 along the first direction is F1. Please refer to [link / reference]. Figure 4 As shown, the dimension of the second adhesive tape 60 along the first direction is F2, where F1 < F2.

[0067] It should be noted that the first electrode 10 can be either a positive or negative electrode, and the second electrode 20 has the opposite polarity to the first electrode 10. The first direction in this text refers to the direction of the maximum dimension of the first adhesive tape 50 and / or the second adhesive tape 60; the second direction refers to the direction of the second largest dimension of the first adhesive tape 50 and / or the second adhesive tape 60; and the third direction refers to the direction of the minimum dimension of the first adhesive tape 50 and / or the second adhesive tape 60. At the electrode level, the first direction can refer to the direction of the maximum dimension of the first electrode 10 and the second electrode 20, specifically the length direction; the second direction refers to the direction of the second largest dimension of the first electrode 10 and the second electrode 20, specifically the electrode width direction; and the third direction refers to the direction of the minimum dimension of the first electrode 10 and the second electrode 20, specifically the electrode thickness direction. The third direction is perpendicular to both the second and first directions.

[0068] The electrode assembly provided by this utility model has a second groove 220 on the second active material layer 22, which is opposite to the first groove 121. The first adhesive tape 50 and the second adhesive tape 60 are stacked within the second groove 220. On one hand, the two layers of adhesive tape in the second groove 220 provide better cushioning, preventing the welding protrusion at the first tab 40 from puncturing the separator and causing a short circuit due to compression or impact during battery use. On the other hand, the two layers of adhesive tape in the second groove 220 provide better heat insulation, effectively dispersing the excessive heat accumulated at the first tab 40 due to excessive current during battery cycling, which could lead to localized overheating and battery failure. By setting the second groove 220... The second groove 20 can also accommodate at least part of the thickness of the adhesive tape, reducing the thickness accumulation at the first tab 40 position in the battery and preventing the loss of cell energy density caused by the thickness accumulation; the stacked arrangement of the first adhesive tape 50 and the second adhesive tape 60 can also reduce the risk of lithium plating at the first tab 40 position; and the dimension F1 of the first adhesive tape 50 along the first direction is smaller than the dimension F2 of the second adhesive tape 60 along the first direction, so that the second adhesive tape 60 is at least partially located outside the first adhesive tape 50. This can achieve effective detection of the first adhesive tape 50 and the second adhesive tape 60 set in the second groove 220, avoid the risk of missing adhesive tape, ensure the safety performance of the battery, ensure the effective setting of the two layers of adhesive tape, ensure the safety performance of the battery, and improve the cell energy density.

[0069] Furthermore, the electrode assembly also includes a second tab (not shown), which is electrically connected to the second current collector 21.

[0070] Furthermore, the total depth of the second groove 220 along a third direction can be less than the thickness of the second active material layer 22.

[0071] The second active material layer 22 on the surface of the second current collector 21 can be cleaned to form a second groove 220. During the cleaning process, part of the second active material layer 22 can be retained in the second groove 220, or the second current collector 21 can be completely cleaned and exposed to form the second groove 220. The total depth of the second groove 220 along the third direction is less than or equal to the thickness of the second active material layer 22. This ensures that the second groove 220 can fully accommodate the entire thickness of the second adhesive paper 60, while avoiding short circuit problems caused by the exposure of the second current collector 21.

[0072] In some embodiments, please combine Figure 1 , Figure 3 and Figure 4 As shown, the dimension of the second groove 220 along the first direction is E1, where E1 satisfies F1 < F2 ≤ E1. By satisfying F1 < F2 ≤ E1, the second adhesive tape 60 can be detected while the first adhesive tape 50 is being detected, avoiding the risk of missed application and ensuring battery safety. Furthermore, it facilitates the complete integration of the first and second adhesive tapes 50 and 60 within the second groove 220, thereby reducing the cumulative thickness of the adhesive tape and increasing the battery's energy density.

[0073] Preferably, F2 = E1, thereby effectively avoiding the lithium plating problem caused by the exposure of the second current collector 21.

[0074] In some embodiments, see Figure 7 As shown, the second groove 220 includes a first sub-groove 221 and a second sub-groove 222. A first adhesive tape 50 is disposed in the first sub-groove 221 and / or the second sub-groove 222. A second adhesive tape 60 is disposed in the second sub-groove 222, and at least a portion of the second adhesive tape 60 extends from the second sub-groove 222 into the first groove 221 along a first direction. Please refer to the diagram for further details. Figure 3 As shown, the first sub-slot 221 includes a first portion 2211 connected to the second sub-slot 222 along a first direction. The second sub-slot 222 is formed by the bottom wall of the first sub-slot 221 being recessed towards the second current collector 21 along a third direction. Along the third direction, the distance from the bottom wall of the second sub-slot 222 to the surface of the second current collector 21 is less than the distance from the bottom wall of the first sub-slot 221 to the surface of the second current collector 21.

[0075] And / or, along a third direction, the distance from the bottom wall of the first sub-groove 221 to the surface of the second current collector 21 is less than the thickness of the second active material layer 22 in the other areas of the single-sided surface of the second electrode 20, excluding the areas where the first sub-groove 221 and the second sub-groove 222 are located.

[0076] And / or, at least a portion of the second sub-slot 222 is an exposed second current collector 21.

[0077] In this embodiment, by providing a first sub-groove 221 and a second sub-groove 222 in the second active material layer 22, the second adhesive tape 60 is embedded in the second sub-groove 222, and the first adhesive tape 50 is embedded in the first sub-groove 221, with at least a portion of the second adhesive tape 60 extending into the first sub-groove 221. The dimension F1 of the first adhesive tape 50 along the first direction is smaller than the dimension F2 of the second adhesive tape 60 along the first direction, so that at least a portion of the second adhesive tape 60 is exposed in the first sub-groove 221. This allows for the detection of the second adhesive tape 60 while detecting the first adhesive tape 50, avoiding the risk of missed application and ensuring the safety performance of the battery. Furthermore, the first sub-groove 221 and the second sub-groove 222 can accommodate the thickness of the first adhesive tape 50 and the second adhesive tape 60, thereby ensuring that the first adhesive tape 50 and the second adhesive tape 60 are not missed, and preventing the loss of cell energy density caused by the accumulation of thickness.

[0078] In some embodiments, see Figure 3 As shown, the dimension of the first sub-slot 221 along the first direction is E2, and the dimension of the second sub-slot 222 along the first direction is E3. E2 and E3 satisfy: E2≤E3.

[0079] It should be noted that, in this embodiment, at least a portion of the second sub-groove 222 can expose the surface of the second current collector 21, and the second adhesive tape 60 is bonded to the second current collector 21. The portion of the second adhesive tape 60 extending into the first sub-groove 221 is bonded to the first portion 2211. Since the bonding effect between the adhesive tape and the current collector is better than the bonding effect between the adhesive tape and the active material layer, E2 and E3 must satisfy E2≤E3. On the one hand, this ensures that as much of the stacked first adhesive tape 50 and second adhesive tape 60 as possible is located in the second sub-groove 222, thereby minimizing the cumulative thickness of the adhesive tape in the electrode assembly and improving the overall flatness and energy density of the battery. On the other hand, when the area of ​​the second sub-groove 222 is the exposed second current collector 21, the bonding effect between the adhesive tape and the second current collector 21 is better. This allows the second adhesive tape 60 to have a larger area to bond with the second current collector 21, further ensuring the bonding effect of the second adhesive tape 60 and reducing the risk of the second adhesive tape 60 falling off.

[0080] In some embodiments, see Figure 5As shown, the first sub-slot 221 further includes a second part 2212 connected to the left side wall of the second sub-slot 222 along the second direction and a third part 2213 connected to the right side wall of the second sub-slot 222 along the second direction. The first part 2211 is connected to the second part 2212 and the third part 2213 respectively, forming the first sub-slot 221. The first sub-slot 221 surrounds the second sub-slot 222. Along the third direction, the second sub-slot 222 is connected to the first sub-slot 221. The dimension of the first sub-slot 221 along the first direction is E4, and the dimension of the second sub-slot 222 along the first direction is E5. E4 and E5 satisfy: E4 > E5.

[0081] In this embodiment, the first sub-slot 221 is formed by connecting a first part 2211, a second part 2212, and a third part 2213. Please refer to [link / reference needed]. Figure 6 As shown, the second adhesive tape 60 is built into the second sub-slot 222, and at least a portion of the second adhesive tape 60 extends into the first sub-slot 221. The first adhesive tape 50 is built into the first sub-slot 221. On the one hand, the first sub-slot 221 and the second sub-slot 222 can completely accommodate the first adhesive tape 50 and the second adhesive tape 60, ensuring that the adhesive tape can be detected and preventing the loss of cell energy density caused by thickness accumulation. On the other hand, by covering the first part 2211, the second part 2212 and the third part 2213 simultaneously, the projection of the first adhesive tape 50 along the third direction completely covers the second sub-slot 222. In this way, even if the second current collector 21 is exposed in the second sub-slot 222, the adhesive tape can still completely cover the second current collector 21 exposed in the second sub-slot 222, reducing the risk of contact between the two electrodes with opposite polarities and avoiding affecting the safety performance of the battery.

[0082] In some embodiments, see Figure 3 and Figure 5 As shown, the dimension W1 of the first sub-slot 221 along the second direction is greater than or equal to the dimension W2 of the second sub-slot 222 along the second direction;

[0083] Please combine them together Figure 1 and Figure 6 As shown, the dimension of the first adhesive tape 50 along the second direction is W3, and W3 and W2 satisfy: W3≥W2;

[0084] And / or, please combine them together. Figure 4 As shown, the dimension of the second adhesive tape 60 along the second direction is W4, and W4 and W2 satisfy: W4≤W2;

[0085] And / or, W3 and W4 satisfy: W4≤W3;

[0086] And / or, W1 and W3 satisfy: 1.0 ≤ W1 / W3 ≤ 2.0,

[0087] And / or, the dimension of the first electrode tab 40 along the second direction of the first electrode plate 10 is W5, and W5 and W2 satisfy: W2≥W5.

[0088] It should be noted that, Figure 1 , Figure 3 and Figure 4 The structural form of W1 = W2 is shown. Figure 5 and Figure 6 The structure with W1 > W2 is shown. The dimension W1 of the first sub-slot 221 along the second direction is greater than or equal to the dimension W2 of the second sub-slot 222 along the second direction, ensuring that the two sub-slots can flexibly match the dimensions of the first adhesive tape 50 and the second adhesive tape 60, thereby reducing the loss of active material and improving the battery energy density while ensuring battery safety performance.

[0089] Please see Figure 5 and Figure 6 As shown, the dimension W3 of the first adhesive tape 50 along the second direction is greater than or equal to the dimension W2 of the second sub-groove 222 along the second direction, thereby ensuring that the projection of the first adhesive tape 50 along the third direction completely covers the second sub-groove 222. In this way, even if the second current collector 21 is exposed in the second sub-groove 222, the adhesive tape can still completely cover the exposed second current collector 21 in the second sub-groove 222, preventing the risk of short circuit and avoiding affecting the safety performance of the battery. At the same time, the dimension W3 of the first adhesive tape 50 along the second direction and the dimension W1 of the first sub-groove 221 along the second direction satisfy 1.0≤W1 / W3≤2.0, thereby ensuring that the thickness of the first adhesive tape 50 is completely hidden in the first sub-groove 221, further reducing the accumulation of adhesive tape thickness and improving the energy density of the battery. The dimension W4 of the second adhesive tape 60 along the second direction is less than or equal to the dimension W2 of the second sub-groove 222 along the second direction, thereby ensuring that the second adhesive tape 60 can be built into the second sub-groove 222, ensuring the adhesion effect between the second adhesive tape 60 and the second current collector 21, while hiding the thickness of the second adhesive tape 60 and improving the energy density of the battery; in addition, the dimension of the first electrode tab 40 along the second direction of the first electrode 10 is W5, and W5 and W2 satisfy: W2≥W5, thereby ensuring that the projection of the first electrode tab 40 is completely located within the second sub-groove 222, avoiding the first electrode tab 40 being located outside the second sub-groove 222 due to production fluctuations, and avoiding the accumulation of increased thickness.

[0090] In some embodiments, see Figure 4 As shown, the second adhesive tape 60 includes a first segment 61 and a second segment 62 that are connected to each other along a first direction. The first segment 61 is located in the first sub-groove 221, and the second segment 62 is located in the second sub-groove 222.

[0091] Please combine them together Figure 2As shown, the distance between the end of the first adhesive tape 50 near the first segment 61 along the first direction and the edge of the first sub-groove 221 away from the first adhesive tape 50 is M, where M ≥ 2.0 mm. This provides sufficient space for the second adhesive tape 60 to be inspected, effectively avoiding the risk of missed application and ensuring the safety performance of the battery. At the same time, it ensures that the second adhesive tape 60 overlaps with the first sub-groove 221 or the first adhesive tape 50 as little as possible, reducing the area of ​​thickness accumulation in the battery and ensuring the flatness of the battery.

[0092] In some embodiments, see Figure 4 As shown, the dimension of the first segment 61 along the first direction is F3, and F3 satisfies F3≥1.5mm.

[0093] The first segment 61 extends from the second segment 62 into the first sub-groove 221. The dimension F3 of the first segment 61 along the first direction satisfies F3≥1.5mm, thereby ensuring that the second adhesive tape 60 has sufficient protrusion size relative to the first adhesive tape 50 for subsequent inspection, thus effectively avoiding the risk of missing adhesive tape and ensuring the safety performance of the battery.

[0094] In some embodiments, see Figure 1 As shown, along the first direction, the second adhesive tape 60 extends beyond the first adhesive tape 50 by a dimension of F4, where F4 ≥ 0.3 mm. This ensures the accuracy of the detection of the second adhesive tape 60, effectively avoids the risk of missed application, and guarantees the safety performance of the battery.

[0095] In some embodiments, see Figure 5 As shown, when the dimension W1 of the first sub-slot 221 along the second direction is greater than the dimension W2 of the second sub-slot 222 along the second direction, W1 and W2 satisfy W1 / W2=K, 1.1≤K≤2.5.

[0096] When the dimension W1 of the first sub-slot 221 along the second direction is greater than the dimension W2 of the second sub-slot 222 along the second direction, the dimension W3 of the first adhesive tape 50 along the second direction and the dimension W1 of the first sub-slot 221 along the second direction satisfy 1.0≤W1 / W3≤2.0. At the same time, W1 and W2 satisfy W1 / W2=K, 1.1≤K≤2.5. This ensures that the first adhesive tape 50 is completely embedded in the first sub-slot 221, further reducing the cumulative thickness of the adhesive tape and improving the energy density of the battery. It also ensures that the projection of the first adhesive tape 50 along the third direction completely covers the second sub-slot 222. In this way, even if the second current collector 21 is exposed in the second sub-slot 222, the first adhesive tape 50 and the second adhesive tape 60 can completely cover and double-protect the exposed second current collector 21, preventing contact with the first electrode 40 and the risk of short circuit, thus avoiding affecting the safety performance of the battery.

[0097] In some embodiments, see Figure 7 As shown, the projection of the welding end of the first electrode 40 along the third direction is completely located within the projection area of ​​the second adhesive tape 60 along the third direction.

[0098] And / or, the projection of the first groove 121 along a third direction is completely located within the projection area of ​​the first adhesive paper 50 along a third direction.

[0099] It should be noted that the projection of the welding end of the first tab 40 along the third direction is completely located within the projection area of ​​the second adhesive tape 60 along the third direction, thereby ensuring that the first tab 40 can be protected by the double layer of the first adhesive tape 50 and the second adhesive tape 60 at the same time; and / or, the projection of the first groove 121 along the third direction is completely located within the projection area of ​​the first adhesive tape 50 along the third direction, that is, the edge of the first adhesive tape 50 near the first segment 61 along the first direction extends beyond the edge of the first groove 121 near the first segment 61 along the first direction, thereby preventing the first tab 40 from lifting off due to external force or the first tab 40 from protruding and piercing the separator, thus avoiding battery short circuit failure.

[0100] According to an embodiment of the present invention, another aspect provides a lithium-ion secondary battery, comprising: a packaging shell, and an electrode assembly as described above, wherein the electrode assembly is embedded within the packaging shell.

[0101] The lithium-ion secondary battery provided in this embodiment includes the electrode assembly described above. Therefore, the lithium-ion secondary battery provided in this embodiment includes all the beneficial effects of the electrode assembly described above.

[0102] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electrode assembly, characterized in that, include: A first electrode (10) and a second electrode (20) with opposite polarities, and a separator (30) disposed between the first electrode (10) and the second electrode (20); The first electrode (10) includes a first current collector (11) and a first active material layer (12) disposed on the surface of the first current collector (11); the first active material layer (12) is provided with a first groove (121) exposing the first current collector (11); The first electrode (40) has its welding end placed in the first groove (121), and the first electrode (40) is electrically connected to the first current collector (11). The second electrode (20) includes a second current collector (21) and a second active material layer (22) disposed on the surface of the second current collector (21); The second active material layer (22) is provided with a second groove (220), and along the third direction, the second groove (220) is disposed opposite to the first groove (121); The second groove (220) is provided with a first adhesive tape (50) and a second adhesive tape (60) stacked on it. The first adhesive tape (50) is disposed on the side of the second adhesive tape (60) away from the second current collector (21). The first adhesive tape (50) has a dimension of F1 along the first direction, and the second adhesive tape (60) has a dimension of F2 along the first direction, where F1 < F2.

2. The electrode assembly according to claim 1, characterized in that, The second groove (220) has a dimension of E1 along the first direction, and E1 satisfies F1<F2≤E1.

3. The electrode assembly according to claim 2, characterized in that, The second groove (220) includes a first sub-groove (221) and a second sub-groove (222). The first adhesive tape (50) is disposed in the first sub-groove (221) and / or the second sub-groove (222). The second sub-groove (222) is provided with a second adhesive tape (60), and at least a portion of the second adhesive tape (60) extends from the second sub-groove (222) into the first sub-groove (221) along a first direction. The first sub-groove (221) includes a first portion (2211) connected to the second sub-groove (222) along the first direction. The second sub-groove (222) is formed by the bottom wall of the first sub-groove (221) being recessed towards the second collector (21) along a third direction. Along the third direction, the distance from the bottom wall of the second sub-groove (222) to the surface of the second collector (21) is less than the distance from the bottom wall of the first sub-groove (221) to the surface of the second collector (21). And / or, along a third direction, the distance from the bottom wall of the first sub-groove (221) to the surface of the second current collector (21) is less than the thickness of the second active material layer (22) in the other areas of the single-sided surface of the second electrode (20) excluding the areas where the first sub-groove (221) and the second sub-groove (222) are located; And / or, at least a portion of the second sub-slot (222) is exposed to the second current collector (21).

4. The electrode assembly according to claim 3, characterized in that, The first sub-slot (221) has a dimension of E2 along the first direction, and the second sub-slot (222) has a dimension of E3 along the first direction. E2 and E3 satisfy: E2≤E3.

5. The electrode assembly according to claim 3, characterized in that, The first sub-slot (221) further includes a second part (2212) connected to the left side wall of the second sub-slot (222) along the second direction and a third part (2213) connected to the right side wall of the second sub-slot (222) along the second direction. The first part (2211) is connected to the second part (2212) and the third part (2213) respectively, forming the first sub-slot (221). The first sub-slot (221) surrounds the second sub-slot (222). Along the third direction, the second sub-slot (222) is connected to the first sub-slot (221). The dimension of the first sub-slot (221) along the first direction is E4, and the dimension of the second sub-slot (222) along the first direction is E5. E4 and E5 satisfy: E4 > E5.

6. The electrode assembly according to claim 3 or 5, characterized in that, The dimension W1 of the first sub-slot (221) along the second direction is greater than or equal to the dimension W2 of the second sub-slot (222) along the second direction; The first adhesive tape (50) has a dimension of W3 along the second direction, and W3 and W2 satisfy: W3≥W2; And / or, the second adhesive tape (60) has a dimension of W4 along the second direction, and W4 satisfies W4≤W2; And / or, W3 and W4 satisfy: W4≤W3; And / or, W1 and W3 satisfy 1.0 ≤ W1 / W3 ≤ 2.0, And / or, the dimension of the first electrode tab (40) along the second direction of the first electrode plate (10) is W5, and W5 and W2 satisfy: W2≥W5.

7. The electrode assembly according to claim 6, characterized in that, The second adhesive tape (60) includes a first segment (61) and a second segment (62) connected to each other along a first direction, wherein the first segment (61) is located in the first sub-groove (221) and the second segment (62) is located in the second sub-groove (222); The distance between the end of the first adhesive tape (50) close to the first segment (61) along the first direction and the edge of the first sub-groove (221) away from the first adhesive tape (50) is M, where M satisfies M≥2.0mm.

8. The electrode assembly according to claim 7, characterized in that, The first segment (61) has a dimension of F3 along the first direction, and F3 satisfies F3≥1.5mm.

9. The electrode assembly according to claim 5, characterized in that, Along the first direction, the second adhesive tape (60) extends beyond the first adhesive tape (50) by a dimension of F4, where F4 satisfies F4≥0.3mm.

10. The electrode assembly according to claim 6, characterized in that, When the dimension W1 of the first sub-slot (221) along the second direction is greater than the dimension W2 of the second sub-slot (222) along the second direction, W1 and W2 satisfy W1 / W2=K, 1.1≤K≤2.

5.

11. The electrode assembly according to any one of claims 1-5 or 9, characterized in that, The projection of the welding end of the first electrode (40) along the third direction is completely located within the projection area of ​​the second adhesive tape (60) along the third direction; And / or, the projection of the first groove (121) along a third direction is completely located within the projection area of ​​the first adhesive tape (50) along a third direction.

12. A lithium-ion secondary battery, characterized in that, include: The packaging housing, and the electrode assembly as described in any one of claims 1 to 11, wherein the electrode assembly is embedded within the packaging housing.

Images