Pole piece and battery cell
By setting multiple recesses on the active material layer of the electrode sheet and the current collector in the ear groove of the electrode sheet, the problem of excessive density of the negative electrode sheet of the lithium-ion battery is solved, the rate performance and utilization rate are improved, the risk of lithium extraction is reduced, and more efficient battery performance is achieved.
Patent Information
- Application Number
- CN202420619283.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-27
- Publication Date
- 2025-05-13
- Estimated Expiration
- 2034-03-27
AI Technical Summary
The negative electrode sheets of existing lithium-ion batteries lead to denser density and less porosity during the rolling process, which increases the electrolyte migration path, resulting in a decrease in rate performance, low utilization rate, and high risk of lithium evolution.
A plurality of recesses are provided on the active material layer of the electrode sheet and on the current collector in the electrode groove to improve the rate performance and utilization of the electrode sheet and reduce the risk of lithium evolution.
By setting up the recesses, the problem of excessive density of the electrode sheet is solved, the storage space of the electrolyte is increased, the problems of polarization and uneven electrolyte concentration are alleviated, the risk of lithium excretion is reduced, and the utilization rate of the electrode sheet and the performance of the battery are improved.
Smart Images
Figure CN222867696U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to a pole piece and a battery cell. Background Art
[0002] The negative electrode sheets in existing lithium-ion batteries will have a denser density and lower porosity near the side of the diaphragm in the thickness direction of the sheet during the rolling process, which will increase the migration path of the electrolyte in the sheet, and the increase in the migration path will lead to a decrease in the rate performance of the sheet. In addition, among the electrode sheets, the potential of the negative electrode sheet is lower near the diaphragm surface, and the polarization and electrolyte concentration are uneven, resulting in low sheet utilization and a high risk of lithium plating. Utility Model Content
[0003] In view of this, the present application provides a method of improving the rate performance and utilization of the pole piece and reducing the risk of lithium plating by setting a plurality of recesses on the active material layer of the pole piece and on the current collector in the pole lug groove.
[0004] In order to achieve the above objectives, this application provides the following technical solutions:
[0005] A pole piece, comprising:
[0006] A current collector, and active material layers respectively arranged on both sides of the current collector; the pole piece has a first direction and a second direction;
[0007] The pole piece is provided with a pole ear groove at the edge of the first direction, the current collector is exposed in the pole ear groove, and the pole ear is connected to the surface of the current collector in the pole ear groove;
[0008] A plurality of recesses are formed on the active material layer and on the current collector in the tab groove, respectively.
[0009] Optionally, the side of the pole tab groove away from the edge of the pole piece in the first direction is the bottom of the pole tab groove, and the recess in the pole tab groove extends to the bottom of the pole tab groove to form a protrusion on the active material layer.
[0010] Optionally, the width of the concave portion protruding toward the active material layer in the first direction is W. 1 , the width of the concave portion in the second direction is W 2 , W 1 and W 2 The relationship satisfies: W 2 / 50≤W 1 ≤W 2 / 10.
[0011] Optionally, there is a first region on one side of the pole tab groove away from the edge of the pole piece in the first direction, and the current collector of the pole tab groove also includes a second region adjacent to the first region in the first direction, and the thickness of the first region is less than the thickness of the second region.
[0012] Optionally, the depths of the recesses formed in the second region, the first region, and the active material layer satisfy:
[0013] The depth of the recess formed in the active material layer is greater than or equal to the depth of the recess formed in the second region, and / or the depth of the recess formed in the second region is greater than or equal to the depth of the recess formed in the first region.
[0014] Optionally, the cross-sectional shape of the recess is arc-shaped or parabolic.
[0015] Optionally, the first region has a region D where the recess is formed and a region E where the recess is not formed, alternately in the second direction of the pole piece, and the thickness of the current collector in the region D and the region E are T respectively. 4 and T 5 , T 4 and T 5 The relationship is satisfied: 0.6T 4 <T 5 <0.9T 4 .
[0016] Optionally, along the first direction of the pole piece, the welding tensile force value at region E is N 1 , the welding tensile force value at area D is N 2 , N 1 and N 2 The relationship satisfies: 0.05N≤N 2 -N 1 ≤1N.
[0017] Optionally, along the first direction of the pole piece, the distance between the pole ear and the first region is L 1 , the distance between the tab and the active material layer is L 2 , the width of the first region is W 3 , L 1 , L 2 , W 3 The relationship between satisfaction: 8W 3 ≤L 1 ≤39W 3 , and / or, 0.8L 2 ≤L 1 ≤0.95L 2 , and / or, 0.4mm≤L2 ≤4mm, and / or, 0.05mm≤W 3 ≤0.2mm.
[0018] Optionally, the width of the concave portion formed on the active material layer and closest to the side edge of the electrode tab groove in the second direction and the width of the concave portion next closest to the electrode tab groove are W and W, respectively. 4 With W 5 , W 4 With W 5 The relationship satisfies: W 4 <W 5 .
[0019] Optionally, the recessed portion closest to the pole tab slot and the two side edges of the pole tab slot in the second direction at least partially overlap.
[0020] Optionally, the recesses form an array parallel to the first direction and an array parallel to the second direction on the pole piece, and the depth of the recesses in the array parallel to the first direction is D 1 , the depth of the recess in the array parallel to the second direction is D 2 , D 1 and D 2 The relationship is satisfied: 5μm≤D 1 -D 2 ≤20μm.
[0021] The present application also provides a battery cell, comprising the pole piece, and also comprising a second pole piece and a diaphragm. The pole piece, the diaphragm and the second pole piece are stacked in sequence to form the battery cell, or the pole piece, the diaphragm and the second pole piece are stacked in sequence and wound into the battery cell.
[0022] The pole piece and battery cell provided in the present application have multiple recesses formed on the active material layer of the pole piece and the current collector of the pole lug groove, and the active material layer at these recesses is removed, which, on the one hand, solves the problem of denser density near the side of the diaphragm in the thickness direction of the pole piece after rolling; on the other hand, the recesses on the active material layer and the recesses on the current collector in the pole lug groove can also store a portion of the electrolyte, thereby alleviating the problems of polarization and uneven electrolyte concentration, reducing the risk of lithium plating of the pole piece, improving the utilization rate of the pole piece, and also improving the performance of the battery cell and the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.
[0024] Figure 1 A schematic diagram of a pole piece of the present application;
[0025] Figure 2 A schematic diagram of another embodiment of a pole piece of the present application;
[0026] Figure 3 for Figure 2 Section view at A Figure 1 ;
[0027] Figure 4 for Figure 2 Section view at A Figure 2 ;
[0028] Figure 5 A schematic diagram showing a comparison of thicknesses of a first region with a recessed portion and a first region without a recessed portion;
[0029] Figure 6 A schematic diagram of the positional relationship between the electrode tab in the electrode tab groove, the first region, and the active material layer in the first direction;
[0030] Figure 7 A schematic diagram showing a comparison of the widths of the concave portion formed on the active material layer, which is closest to the side edge of the electrode tab groove in the second direction and the concave portion which is second closest to the side edge of the electrode tab groove in the second direction;
[0031] Figure 8 Schematic diagram of the distribution array of recesses on the pole piece.
[0032] exist Figure 1-Figure 8 middle:
[0033] 1. Pole piece; 11. Current collector; 12. Active paste coating area; 2. Pole ear groove; 21. First area; 22. Second area; 3. Pole ear; 4. Recess. DETAILED DESCRIPTION
[0034] The present application provides a pole piece and a battery cell including the pole piece, which improves the pole piece rate performance and pole piece utilization and reduces the risk of lithium plating by arranging a plurality of recesses on the active material layer of the pole piece and on the current collector in the pole lug groove.
[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0036] like Figure 1 As shown, the embodiment of the present application provides a pole piece 1, comprising:
[0037] The current collector 11 and the active material layers are respectively arranged on both sides of the current collector 11; the pole piece 1 has a first direction (i.e. Figure 1 The X direction in the second direction (i.e. Figure 1 The thickness direction of the pole piece 1 is Figure 2 The Z direction in the
[0038] The pole piece 1 is provided with a pole tab groove 2 at the edge in the first direction, the active material layer in the pole tab groove 2 is removed to expose the current collector 11, and the pole tab 3 is connected to the surface of the current collector 11 in the pole tab groove 2;
[0039] A plurality of recesses 4 are formed on the active material layer and on the current collector 11 in the tab groove 2 .
[0040] In order to solve the problems of decreased rate performance of the pole piece 1 and low utilization rate of the pole piece 1 and high risk of lithium plating in the prior art, the present application provides a plurality of recesses 4 on the surface of the pole piece 1, that is, recesses 4 are formed on the active material layer of the pole piece 1 and the current collector 11 of the pole lug groove 2, respectively. These recesses 4 can be formed by laser punching or physical / chemical pore making. The removal of the active material layer at these recesses 4 solves, on the one hand, the problem of denser density of the pole piece 1 near the side of the diaphragm in the thickness direction after rolling; on the other hand, the recesses 4 on the active material layer and the recesses 4 on the current collector 11 in the pole lug groove 2 can also play the role of storing electrolyte, thereby alleviating the problems of polarization and uneven electrolyte concentration, reducing the risk of lithium plating of the pole piece 1, and improving the utilization rate of the pole piece 1.
[0041] In a preferred embodiment, Figure 1 As shown, the side of the pole tab slot 2 away from the edge of the pole piece 1 in the first direction is the bottom of the pole tab slot 2, and the recess 4 in the pole tab slot 2 extends to the area at the bottom of the pole tab slot 2 and forms a protrusion on the active material layer.
[0042] The recessed portion 4 here protrudes toward the active material layer, and the electrolyte stored in the recessed portion 4 can also flow toward the tab groove 2 more easily, which can further improve the electrolyte wettability at the tab 3 in the tab groove 2 .
[0043] In a preferred embodiment, Figure 1 As shown, the width of the concave portion 4 protruding toward the active material layer in the first direction is W 1 , the width of the concave portion 4 in the second direction is W 2 , W 1 and W 2 The relationship satisfies: W 2 / 50≤W 1 ≤W 2 / 10.
[0044] In this way, the size of the concave portion 4 in the second direction is greater than that in the first direction, and the projection of a single concave portion 4 in the thickness direction of the pole piece 1 forms a thin line parallel to the second direction of the pole piece 1. Multiple concave portions 4 are evenly distributed on the straight line parallel to the first direction of the pole piece 1 to form a straight line with a width of W. 2 4 arrays of recesses.
[0045] In a preferred embodiment, Figure 2 As shown, there is a first region 21 on one side of the pole tab slot 2 away from the edge of the pole piece 1 in the first direction, and the pole tab slot 2 also includes a second region 22 adjacent to the first region 21. The second region 22 is Figure 2 The other parts of the tab slot 2 except the first area 21; specifically, in this embodiment, the first area 21 may be a heat-affected area, and the second area 22 may be a non-heat-affected area, such as Figure 3 , the thickness of the first region 21 is less than the thickness of the second region 22, so that the heights of the active paste area 12 where the active material layer is located, the first region 21 and the second region 22 are H respectively 1 , H 2 and H 3 , H 1 >H 3 >H 2 Thus, the first region 21 located in the middle has the smallest height, and the second region 22, the first region 21 and the active material layer form an electrolyte storage tank.
[0046] The second area 22 on one side of the first area 21 is higher, while the active material layer on the surface of the current collector 11 on the other side is higher than the first area 21. There is a height difference between the three. The first area 21 in the middle is the lowest. The groove formed in this way can be used as an electrolyte storage tank, and the active material layer is the highest, which can block the electrolyte in the pole ear groove 2 to prevent insufficient electrolyte at the pole ear 3 from affecting the battery cycle life and improving battery performance.
[0047] In a preferred embodiment, Figure 4 As shown, the depth of the recess 4 formed in the second region 22, the first region 21 and the active material layer satisfies:
[0048] The depth of the recess 4 formed at the active material layer is greater than or equal to the depth of the recess 4 formed at the second region 22, and / or the depth of the recess 4 formed at the second region 22 is greater than or equal to the depth of the recess 4 formed at the first region 21, so that the recess 4 formed at the active material layer, the recess 4 formed at the first region 21, and the recess 4 formed at the second region 22 sequentially form steps. The step, that is, the height difference of the bottom of each recess 4, forms a recess 4 that is inclined along the body toward the pole ear 3, which can effectively release heat and ensure battery safety when the battery is overheated or in other abnormal conditions.
[0049] In addition, the recesses 4 formed in the second region 22, the first region 21 and the active material layer adjacent to the first region 21 partially overlap in the first direction of the electrode 1, so that they can be interconnected in the first direction, and the electrolyte can flow in the first direction, thereby improving conductivity, making the current more evenly distributed on the surface of the electrode ear 3, and improving the overall performance of the battery.
[0050] In a preferred embodiment, Figure 1 , 4 As shown in Figures 8 and 9, the cross-sectional shape of the recess 4 is arc-shaped or parabolic. The arc-shaped or parabolic recess 4 is more conducive to the flow of electrolyte between the recesses 4.
[0051] In a preferred embodiment, Figure 5 As shown, the first region 21 alternately has a region D with a recess 4 and a region E without a recess 4 in the second direction of the pole piece 1, and the thickness of the current collector 11 in the region D and the region E are T respectively. 4 and T 5 , T 4 and T 5 The relationship is satisfied: 0.6T 4 <T 5 <0.9T 4 In a more preferred embodiment, T 4 and T 5 The relationship is satisfied: 0.7T 4 <T 5 <0.8T 4 The regions D and E with different thicknesses are staggered in the second direction, which is the same as the stretching direction of the tab 3. The existence of the thickness difference can improve the tensile and compressive strength of the tab 3, thereby reducing the risk of the tab 3 breaking and thus improving the battery life.
[0052] Further, if Figure 5 As shown, along the first direction of the pole piece 1, the welding tensile force value at area E is N 1 , the welding tensile force value at area D is N 2 , N 1 and N 2 The relationship satisfies: 0.05N≤N 2 -N 1 ≤1N.
[0053] There is a welding tension difference between area D and area E, and this welding tension difference ensures the stability and consistency of the welding tension during welding.
[0054] In a preferred embodiment, Figure 6 As shown, along the first direction of the pole piece 1, the distance between the pole ear 3 and the first region 21 is L1 , the distance between the tab 3 and the active material layer is L 2 , the width of the first region 21 is W 3 , L 1 , L 2 , W 3 The relationship between satisfaction: 8W 3 ≤L 1 ≤39W 3 , and / or, 0.8L 2 ≤L 1 ≤0.95L 2 , and / or, 0.4mm≤L 2 ≤4mm, and / or, 0.05mm≤W 3 ≤0.2mm.
[0055] The distance between the tab 3 and the first region 21 is relatively large, and this ratio is conducive to ensuring that the welding position of the tab 3 is located in the second region 22, thereby improving the welding strength and yield.
[0056] In a preferred embodiment, Figure 7 As shown, the width of the concave portion 4 formed on the active material layer and closest to the side of the electrode tab groove 2 in the second direction and the width of the concave portion 4 next closest are W and W, respectively. 4 With W 5 , W 4 With W 5 The relationship satisfies: W 4 <W 5 In a more preferred embodiment, W 4 With W 5 Relationship satisfied: 0.1W 5 ≤W 4 ≤0.9W 5 Along the second direction of the electrode sheet 1, the width of the recess 4 on the active material layer is larger, while the width of the recess 4 at the two side boundaries of the electrode tab groove 2 is smaller, so that the contact resistance between the electrode tab 3 and the positive and negative electrodes can be reduced, thereby reducing the internal resistance of the battery and improving the battery charging and discharging efficiency.
[0057] Further, if Figure 7 As shown, the recess 4 closest to the pole tab groove 2 and the two side edges of the pole tab groove 2 in the second direction at least partially overlap, that is, a part of the recess 4 falls on the active material layer, and the other part falls on the current collector 11 in the pole tab groove 2, which can improve the yield of the processing process of the recess 4.
[0058] In a preferred embodiment, Figure 8 As shown, the recesses 4 form an array parallel to the first direction and an array parallel to the second direction on the pole piece 1, and the depth of the recesses 4 in the array parallel to the first direction is D 1, the depth of the recess 4 in the array parallel to the second direction is D 2 , D 1 and D 2 The relationship is satisfied: 5μm≤D 1 -D 2 ≤20μm.
[0059] Since the arrays of the recesses 4 in the first direction and the second direction of the pole piece 1 intersect, the depth difference can prevent the depth of the junctions in different directions from being too large, resulting in excessive loss of active materials and thus affecting the battery capacity.
[0060] The present application also provides a battery cell, including a pole piece 1, a second pole piece 1 and a diaphragm. The pole piece 1, the diaphragm and the second pole piece 1 are stacked in sequence to form a battery cell, or the pole piece 1, the diaphragm and the second pole piece 1 are stacked in sequence and wound into a battery cell.
[0061] The battery cell provided in the present application uses the electrode piece 1 provided in the present application, thereby also improving the performance of the battery cell and the battery.
[0062] The specific manufacturing process of the pole piece 1 of the present application is as follows:
[0063] 1. Rolling of the pole piece 1: Rolling the pole piece 1 coated with the active material layer by a roller to achieve the thickness and compaction density required by the process;
[0064] 2. Processing of the concave portion 4: by laser means, controlling the laser power, speed, filling spacing, frequency and other parameters, a concave portion 4 of target width, depth and spacing is formed on the pole piece 1. This can also be achieved by other physical, mechanical or chemical means;
[0065] 3. Laser cleaning: Laser cleaning is performed on the pole piece 1 with the concave portion 4 processed, so as to clean out the pole ear groove 2 for setting the pole ear 3;
[0066] 4. Laser die-cutting: The cleaned pole piece 1 needs to be die-cut. During die-cutting, the non-pole tab 3 area is along the lower edge of the pole tab slot 2. The width of the pole tab 3 and the width of the pole tab slot 2 need to match. The height of the pole tab 3 can be die-cut according to the height required by the specific battery cell.
[0067] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.
[0068] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.
[0069] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed or recombined, and these decompositions or recombinations should be regarded as equivalent solutions of the present application.
[0070] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
[0071] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.
[0072] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.
Claims
1. A pole piece, characterized in that: include: A current collector, and active material layers respectively arranged on both sides of the current collector; The pole piece has a first direction and a second direction; The pole piece is provided with a pole ear groove at the edge of the first direction, the current collector is exposed in the pole ear groove, and the pole ear is connected to the surface of the current collector in the pole ear groove; A plurality of recesses are formed on the active material layer and on the current collector in the tab groove, respectively.
2. The pole piece according to claim 1, characterized in that: The side of the pole tab groove away from the edge of the pole piece in the first direction is the bottom of the pole tab groove, and the recess in the pole tab groove extends to the bottom of the pole tab groove and forms a protrusion on the active material layer.
3. The pole piece according to claim 2, characterized in that: The width of the concave portion protruding toward the active material layer in the first direction is W1, and the width of the concave portion in the second direction is W2. The relationship between W1 and W2 satisfies: W2 / 50≤W1≤W2 / 10.
4. The pole piece according to claim 1, characterized in that: A first region exists on one side of the pole tab slot away from the edge of the pole piece in the first direction, and the current collector of the pole tab slot also includes a second region adjacent to the first region in the first direction, and the thickness of the first region is less than the thickness of the second region.
5. The pole piece according to claim 4, characterized in that: The depths of the recesses formed in the second region, the first region, and the active material layer satisfy: The depth of the recessed portion formed in the active material layer is greater than or equal to the depth of the recessed portion formed in the second region, and / or, The depth of the recessed portion formed in the second region is greater than or equal to the depth of the recessed portion formed in the first region.
6. The pole piece according to claim 5, characterized in that: The cross-sectional shape of the concave portion is arc-shaped or parabolic-shaped.
7. The pole piece according to claim 4, characterized in that: The first region has regions D forming the recess and regions E without the recess alternately disposed in the second direction of the pole piece, the thicknesses of the current collectors at the regions D and E are T4 and T5 respectively, and the relationship between T4 and T5 satisfies: 0.6T4<T5<0.9T4.
8. The pole piece according to claim 7, characterized in that: Along the first direction of the pole piece, the welding tension value at region E is N1, and the welding tension value at region D is N2. The relationship between N1 and N2 satisfies: 0.05N≤N2-N1≤1N.
9. The pole piece according to claim 4, characterized in that: Along the first direction of the pole piece, the spacing between the pole ear and the first region is L1, the spacing between the pole ear and the active material layer is L2, the width of the first region is W3, and the relationship among L1, L2, and W3 satisfies: 8W3≤L1≤39W3, and / or, 0.8L2≤L1≤0.95L2, and / or, 0.4mm≤L2≤4mm, and / or, 0.05mm≤W3≤0.2mm.
10. The pole piece according to claim 1, characterized in that: The width of the recess formed on the active material layer and closest to the side of the electrode tab groove in the second direction is W4 and the width of the recess next closest is W5 respectively, and the relationship between W4 and W5 satisfies: W4<W5.
11. The pole piece according to claim 10, characterized in that: The recessed portion closest to the tab slot at least partially overlaps with both side edges of the tab slot in the second direction.
12. The pole piece according to claim 1, characterized in that: The recesses form an array parallel to the first direction and an array parallel to the second direction on the pole piece. The depth of the recesses in the array parallel to the first direction is D1, and the depth of the recesses in the array parallel to the second direction is D2. The relationship between D1 and D2 satisfies: 5μm≤D1-D2≤20μm.
13. A battery cell, comprising the pole piece according to any one of claims 1 to 12, characterized in that: It also includes a second pole piece and a diaphragm. The pole piece, the diaphragm and the second pole piece are stacked in sequence to form the battery core, or the pole piece, the diaphragm and the second pole piece are stacked in sequence and wound into the battery core.