Composite current collector, electrode and battery
By setting metal layers with different surface roughness on both sides of the composite current collector and using an interlaced groove design, the problems of wrinkles and bulging caused by stress concentration during the winding process of composite aluminum foil are solved, thus achieving high-quality cell performance and improved production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2026-03-24
AI Technical Summary
During the winding process, the difference in elongation between the metal layer and the substrate layer of composite aluminum foil leads to surface stress concentration, resulting in appearance defects such as wrinkles and ridges, which affect product quality and production efficiency.
By setting metal layers with different surface roughness on both sides of the composite current collector, combined with the staggered groove design, the winding stress is released, and the problems of wrinkles and ridges are improved.
It effectively releases winding stress, improves the appearance quality of composite current collectors, increases production yield, and meets the performance requirements of battery cells.
Smart Images
Figure CN224036360U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the technical field of current collector, especially to a composite current collector, electrode and battery. BACKGROUND
[0002] The composite current collector is a new type of material of lithium battery current collector, and has better performance than traditional metal foil. The composite current collector usually has a "sandwich" structure of "metal layer - substrate layer - metal layer", and has the application advantages of high safety, long service life, high energy density and low cost, and is expected to replace the traditional current collector and become the main material of the future lithium battery current collector.
[0003] At present, the composite aluminum foil is large-width evaporation (the original film width is 1650mm), and the film length is greater than 4000m each time. The product of the composite aluminum foil is a three-layer structure, and because the ductility of the metal layer and the substrate layer is different, the elongation of the metal layer and the substrate layer is different after being subjected to the winding tension in the evaporation process, so that if the winding length is longer and the winding diameter is larger during the winding of the current collector, the surface stress of the wound composite aluminum foil is higher, and wrinkles, bulging and other adverse phenomena are easily generated. UTILITARIAN CONTENT
[0004] In order to overcome the above-mentioned defects, the purpose of the utility model is to provide a composite current collector, the surface roughness of the two surfaces on the thickness direction of the composite current collector is set to be different, and the winding stress can be released in real time during the winding of the finished product roll of the composite current collector, so as to improve or eliminate the appearance problems such as wrinkles, bulging and the like of the finished product roll.
[0005] In order to achieve the above purpose, the utility model adopts the technical scheme that a composite current collector comprises a substrate layer and a first metal layer and a second metal layer arranged on the two sides of the thickness direction of the substrate layer respectively, one side of the first metal layer away from the substrate layer is a first surface, one side of the second metal layer away from the substrate layer is a second surface, the surface roughness of the first surface and the second surface is different, and the difference of the surface roughness Rz of the first surface and the second surface is in the range of 0.2-0.5μm.
[0006] The utility model has the advantages that:
[0007] The substrate layer and the first metal layer and the second metal layer arranged on the two sides of the thickness direction of the substrate layer, one side of the first metal layer away from the substrate layer is a first surface, one side of the second metal layer away from the substrate layer is a second surface, the surface roughness of the first surface and the second surface is set to be different, that is, there is a difference in the grain size of the first surface and the second surface, so that the surface tension of the first surface and the second surface is different, and the winding stress can be released in real time during the winding of the finished product roll of the composite current collector. Thus, the appearance problems such as wrinkles, bulging and the like of the finished product roll are improved or eliminated.
[0008] In the winding process, the surface with large surface roughness faces outward, and the surface with small surface roughness faces inward, and the surface roughness of the first surface and the second surface is in the range of 0.2-0.5 μm, which is beneficial to ensure the performance of the battery cell using the composite current collector while meeting the winding requirements.
[0009] Further, a first adhesive layer is further arranged between the first metal layer and the substrate layer, and a second adhesive layer is further arranged between the second metal layer and the substrate layer. The added first adhesive layer and second adhesive layer serve as adhesive layers to improve the bonding force of the substrate layer and the first metal layer and the second metal layer.
[0010] Further, the outer surface of the first adhesive layer away from the substrate layer is uniformly provided with a plurality of first grooves in the width direction, and the first metal layer fills the first grooves. The outer surface of the second adhesive layer away from the substrate layer is uniformly provided with a plurality of second grooves in the width direction, and the second metal layer fills the second grooves.
[0011] The first grooves and the second grooves are designed to fill the first metal layer and the second metal layer into the first adhesive layer and the second adhesive layer respectively, forming a staggered structure buffer zone, so that the stress can be stably released during the stress diffusion process of the first metal layer and the first adhesive layer and the second metal layer and the second adhesive layer, avoiding abnormal changes in grain size caused by differences in stress release.
[0012] Further, the first grooves and the second grooves are symmetrically arranged on both sides of the thickness direction of the substrate layer or the first grooves and the second grooves are staggered in the width direction. The first grooves and the second grooves can be adjusted in the width direction according to the thickness of the first metal layer and the second metal layer, to improve the stress release effect.
[0013] Further, the first grooves and the second grooves have the same structure, the depth-width ratio of the first grooves and the second grooves is 1:2, and the groove spacing is 0.02-0.05 μm. The size structure of the first grooves and the second grooves allows the stress to be stably released.
[0014] Further, the first metal layer and the second metal layer have the same thickness and the thickness is 0.8-1.5 μm, and the first grooves and the second grooves are square grooves with the same structure.
[0015] Or, the first metal layer and the second metal layer have the same thickness and the thickness is less than 0.8 μm, and the first groove and the second groove are both triangular grooves with the same structure. The thinner the first metal layer and the second metal layer are, the smaller the stress between the film layers is, and in the deposition process, the second metal layer and the second adhesive layer are filled along the inclined edges of the triangular grooves, and through the interlocking structure, the bonding force of the first metal layer and the first adhesive layer and the second metal layer and the second adhesive layer is improved.
[0016] Or, the first metal layer and the second metal layer have the same thickness and the thickness is greater than 1.5 μm, and the first groove and the second groove are both semicircular grooves with the same structure. When the first metal layer and the second metal layer are relatively thick, the bonding force of the first metal layer and the first adhesive layer and the second metal layer and the second adhesive layer is better, but the stress of the first metal layer and the second metal layer is too large, and the semicircular grooves can make the first metal layer and the second metal layer better fit in the semicircular grooves, so that the stress of the relatively thick first metal layer and the second metal layer and the relatively thin first adhesive layer and the second adhesive layer reaches a relatively balanced state, facilitating the release of the overall stress of the composite current collector.
[0017] Further, the substrate layer has a thickness of 4-8 μm, and the first adhesive layer and the second adhesive layer have the same thickness and the thickness is 0.01-0.10 μm.
[0018] Further, the first metal layer and the second metal layer are both aluminum layers, and the first adhesive layer and the second adhesive layer are both aluminum oxide layers.
[0019] Further, an electrode is provided, comprising the composite current collector.
[0020] Further, a battery is provided, comprising the electrode. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 It is a structural schematic view of an embodiment of the utility model;
[0022] Figure 2 It is a structural schematic view of the first adhesive layer in an embodiment of the utility model;
[0023] Figure 3 It is a structural schematic view of another embodiment of the utility model;
[0024] Figure 4 It is a structural schematic view of another embodiment of the utility model;
[0025] Figure 5 It is a structural schematic view of another embodiment of the utility model;
[0026] Figure 6 It is a winding state schematic view of an embodiment of the utility model.
[0027] In the drawings:
[0028] 1, substrate layer; 2, first metal layer; 21, first surface; 3, second metal layer; 31, second surface; 4, first adhesive layer; 41, first groove; 5, second adhesive layer; 51, second groove. DETAILED DESCRIPTION
[0029] The preferred embodiments of the present application will be described in detail with reference to the drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.
[0030] The following disclosure provides many different embodiments, or examples, for implementing different structures of the embodiments of the present application. For the purpose of simplifying the disclosure of the embodiments of the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. The embodiments of the present application can refer to the same reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the embodiments of the present application provide examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.
[0031] A composite current collector of the present application, see Fig. 1 Figure 1 As shown, it comprises a substrate layer 1 and a first metal layer 2 and a second metal layer 3 respectively arranged on both sides of the substrate layer 1 in the thickness direction, the side of the first metal layer 2 away from the substrate layer 1 is the first surface 21, and the side of the second metal layer 2 away from the substrate layer 1 is the second surface 31.
[0032] In the prior art, the surface roughness of the first surface 21 and the second surface 31 is the same, which results in the same surface tension of the first surface 21 and the second surface 31, and the winding stress generated when the composite current collector is wound into a finished product is too concentrated, which can cause the slight wrinkles in the composite current collector during the evaporation process to be unable to flatten naturally, and with the increase of the winding diameter, the slight wrinkles can develop into dead wrinkles or bulging. After the evaporation of the large-width long-meter composite current collector is completed, it still needs to be treated by standing for 3-5 days to reduce the winding stress, which prolongs the delivery time.
[0033] Therefore, in the embodiment, the surface roughness of the first surface 21 and the second surface 31 is set to be different, that is, the grain size of the first surface 21 and the second surface 31 is different, and then the surface tension of the first surface 21 and the second surface 31 is different, so that the winding stress can be released in real time during the winding of the finished product roll, thereby improving or eliminating the appearance problems such as wrinkles and bulging of the finished product roll.
[0034] During winding, the surface with large surface roughness is outward, and the surface with small surface roughness is inward. At this time, the two surfaces will contact. Because the surface roughness is different, the surface tension of the outward surface is larger, thereby improving or eliminating the appearance problems such as wrinkles and bulging of the finished product roll. For example, the surface roughness of the first surface 21 is greater than that of the second surface 31, so that during winding, referring to FIG. 2, the first surface 21 faces outward, and the second surface 31 faces inward. Of course, the surface roughness of the second surface 31 can be greater than that of the first surface 21, and at this time, during winding, the second surface 31 faces outward. Figure 6
[0035] Therefore, the difference between the surface roughness Rz of the first surface 21 and the second surface 31 is in the range of 0.2-0.5 μm, the difference between the surface roughness Ra of the first surface 21 and the second surface 31 is in the range of 0.01-0.25 μm, and the difference between the grain size of the first surface 21 and the second surface 31 is in the range of 3-6 nm.
[0036] The difference between the surface roughness of the first surface 21 and the second surface 31 needs to be in the range of 0.2-0.5 μm, that is, the difference between the grain size is in the range of 3-6 nm, which is beneficial to guarantee the performance of the battery cell using the composite current collector while meeting the winding requirement. If the difference between the surface roughness of the first surface 21 and the second surface 31 is too large, the electrical performance of the battery cell using the composite current collector will be reduced. However, if the difference between the surface roughness of the first surface 21 and the second surface 31 is too small, the winding stress release effect during the winding of the finished product roll cannot be achieved.
[0037] The composite current collector plays a role in transmitting electrons in the battery cell, and the grain boundary between the grains plays a role in resisting the transmission of electrons. If the grain size difference between the first surface 21 and the second surface 31 is too large, that is, the grain of the outward surface during winding is large, the grain boundary density is low, the resistivity is low, and the electron transmission rate is higher. The grain of the inward surface is small, and the small grain size will lead to high grain boundary density, which will increase the resistivity, thereby slowing down the electron transmission rate. The difference between the grain sizes of the two sides is too large, which leads to a large difference between the electron transmission rates of the two sides. On the one hand, the electron transmission rate is limited by the smaller grain side, which leads to a decrease in overall conductivity. On the other hand, the large resistance difference between the two sides of the composite current collector makes the composite current collector difficult to be wound, and the winding stress is difficult to be released.
[0038] The electrochemical reaction rates differ between the two sides during charging and discharging, affecting the cell performance. Therefore, the difference in surface roughness Rz between the first surface 21 and the second surface 31 is no greater than 0.5 μm, and the difference in grain size between the first surface 21 and the second surface 31 is no greater than 6 nm.
[0039] The difference in surface roughness between the first surface 21 and the second surface 31 can compensate for the stress difference during winding. If the difference in surface roughness is too small, the stress release effect during winding cannot be achieved. Therefore, the difference in surface roughness Rz between the first surface 21 and the second surface 31 is not less than 0.2 μm, and at this time, the difference in grain size between the first surface 21 and the second surface 31 is not less than 3 nm.
[0040] The composite current collector includes a substrate layer 1 and a first metal layer 2 and a second metal layer 3 respectively disposed on both sides of the substrate layer 1 in the thickness direction. The side of the first metal layer 2 away from the substrate layer 1 is a first surface 21, and the side of the second metal layer 2 away from the substrate layer 1 is a second surface 31. In this case, the composite current collector has a three-layer structure. The surface roughness difference between the outer surfaces of the first metal layer 2 and the second metal layer 3 is used to reduce or eliminate the winding stress of the finished composite current collector roll.
[0041] The first metal layer 2 and the second metal layer 3 have the same thickness and are formed by vapor deposition of a conductive metal material, which is aluminum. In this embodiment, the first metal layer 2 and the second metal layer 3 are aluminum layers of the same thickness.
[0042] The substrate layer 1 can be made of a polymer material, and the thickness of the substrate layer 1 is 4-8 μm. This polymer material can be polyamide, polyethylene terephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, propylene, etc. For example, in this embodiment, the substrate layer 1 is made of polyethylene terephthalate.
[0043] In one embodiment, see Appendix Figure 1 As shown, a first adhesive layer 4 is disposed between the first metal layer 2 and the substrate layer 1, and a second adhesive layer 5 is disposed between the second metal layer 3 and the substrate layer 1. At this point, the composite current collector has a five-layer structure. The substrate layer 1 serves as the substrate, and the first adhesive layer 4 and the second adhesive layer 5 serve as adhesive layers, improving the bonding strength between the substrate and the first metal layer 2 and the second metal layer 3. The first metal layer 2 and the second metal layer 3 serve as vapor-deposited layers, acting as sites for carrier movement within the battery.
[0044] See appendix Figure 1As shown, the first adhesive layer 4 has a plurality of first grooves 41 uniformly formed along the width direction on its outer surface away from the substrate layer 1, and the first metal layer 2 fills the first grooves 41. The second adhesive layer 5 has a plurality of second grooves 51 uniformly formed along the width direction on its outer surface away from the substrate layer 1, and the second metal layer 3 fills the second grooves 51. Each first groove 41 and second groove 51 is formed along the thickness direction, filling the first metal layer 2 into the interior of the first adhesive layer 4 and the second metal layer 3 into the interior of the second adhesive layer 5, forming a buffer zone with an interlaced structure between the first metal layer 2 and the first adhesive layer 4, and between the second metal layer 3 and the second adhesive layer 5. After the composite current collector is prepared, an annealing phenomenon will occur, specifically manifested as stress release and grain growth, by making the first metal layer 2 and the first adhesive layer 4, and the second metal layer 3 and the second adhesive layer 5 interlaced.
[0045] The staggered structure between the metal layer 3 and the second adhesive layer 5 facilitates the stable release of stress between the first metal layer 2 and the first adhesive layer 4, and between the second metal layer 3 and the second adhesive layer 5 during the annealing process. This allows for more synchronized stress release in each layer, thereby maintaining the uniformity of grain size and avoiding abnormal changes in grain size caused by differences in stress release.
[0046] The first adhesive layer 4 and the second adhesive layer 5 have the same thickness and are formed by vapor deposition of a conductive metal material and oxygen permeation to form an oxide metal layer. For example, in this embodiment, the first adhesive layer 4 and the second adhesive layer 5 are aluminum oxide layers.
[0047] In one embodiment, see Appendix Figure 1 As shown, the first groove 41 and the second groove 51 are symmetrically arranged on both sides of the thickness direction of the substrate layer 1, so that the first groove 41 and the second groove 51 correspond one-to-one and form a symmetrical structure.
[0048] In one embodiment, see Appendix Figure 3 As shown, the first groove 41 and the second groove 51 are staggered in the width direction. In this case, the first groove 41 and the second groove 51 have the same structure and size, but are asymmetrically distributed. This staggered arrangement is specifically adjusted according to the thickness of the first metal layer 2 and the second metal layer 3 to improve stress relief.
[0049] In one embodiment, see Appendix Figure 2As shown, the first metal layer 2 and the second metal layer 3 have the same thickness and the thickness is 0.8-1.5 μm, and the first groove 41 and the second groove 51 are square grooves with the same structure. At this time, the first groove 41 and the second groove 51 can be symmetrically arranged or staggered arranged in the width direction according to the thickness of the first metal layer 2 and the second metal layer 3. For example, when the thickness of the first metal layer 2 and the second metal layer 3 is 1.2-1.5 μm, the thickness of the metal layer is relatively thick, and the stress between the film layers is relatively large. If the first groove 41 and the second groove 51 are symmetrically arranged, the stress on the opposite sides is concentrated on the same straight line perpendicular to the symmetric surface, which is not conducive to stress release. By staggering the first groove 41 and the second groove 51, the stress concentration is reduced, which is conducive to the stable release of stress.
[0050] The ratio of the depth a and the width b of the first groove 41 and the second groove 51 is 1:2, and the groove spacing L is 0.02-0.05 μm.
[0051] At this time, the depth a is 2 nm-4 nm, and the width b is 4 nm-8 nm. For example, the depth a is 3 nm, and the width b is 6 nm.
[0052] In one embodiment, referring to FIG. 1, the first metal layer 2 and the second metal layer 3 have the same thickness and the thickness is greater than 1.5 μm. When the first metal layer 2 and the second metal layer 3 are relatively thick, the adhesion between the aluminum layer and the aluminum oxide layer is good, but the stress of the aluminum layer is too large. At this time, referring to FIG. 2, the first groove 41 and the second groove 51 are semicircular grooves with the same structure. By using a wavy groove structure, the aluminum atoms can better fit in the semicircular groove during deposition into the groove, so that the stress between the thick aluminum layer and the thin aluminum oxide layer is relatively balanced, which is conducive to the release of the overall stress of the composite current collector. Figure 4 As shown, the first metal layer 2 and the second metal layer 3 have the same thickness and the thickness is less than 0.8 μm. The thinner the first metal layer 2 and the second metal layer 3, the smaller the stress between the film layers. At this time, the first groove 41 and the second groove 51 are triangular grooves with the same structure. During deposition, aluminum atoms fill along the hypotenuse of the triangular groove, and through the interlocking structure, the adhesion between the aluminum layer and the aluminum oxide layer is improved.
[0053] At this time, the depth a of the triangular groove is 1 nm-3 nm, and the width b is 2 nm-6 nm. For example, the depth a is 2 nm, and the width b is 4 nm. The depth-width ratio a:b is 1:2, and the groove spacing L is 0.02-0.05 μm.
[0054] In one embodiment, referring to FIG. 1, the first metal layer 2 and the second metal layer 3 have the same thickness and the thickness is greater than 1.5 μm. When the first metal layer 2 and the second metal layer 3 are relatively thick, the adhesion between the aluminum layer and the aluminum oxide layer is good, but the stress of the aluminum layer is too large. At this time, referring to FIG. 2, the first groove 41 and the second groove 51 are semicircular grooves with the same structure. By using a wavy groove structure, the aluminum atoms can better fit in the semicircular groove during deposition into the groove, so that the stress between the thick aluminum layer and the thin aluminum oxide layer is relatively balanced, which is conducive to the release of the overall stress of the composite current collector. Figure 5 As shown, the first metal layer 2 and the second metal layer 3 have the same thickness and the thickness is greater than 1.5 μm. When the first metal layer 2 and the second metal layer 3 are relatively thick, the adhesion between the aluminum layer and the aluminum oxide layer is good, but the stress of the aluminum layer is too large. At this time, referring to FIG. 2, the first groove 41 and the second groove 51 are semicircular grooves with the same structure. By using a wavy groove structure, the aluminum atoms can better fit in the semicircular groove during deposition into the groove, so that the stress between the thick aluminum layer and the thin aluminum oxide layer is relatively balanced, which is conducive to the release of the overall stress of the composite current collector.
[0055] The semicircular groove has a depth a of 1-3 nm and a width b of 2-6 nm, and an example has a depth a of 2 nm and a width b of 4 nm.
[0056] In the embodiment, the first surface 21 and the second surface 31 are set to have different roughnesses, so that the surface tensions of the first surface 21 and the second surface 31 are different, and the five-layer structure of the composite current collector is matched, especially the matching grooves and the protrusions deposited in the grooves are arranged between the first metal layer 2 and the first adhesive layer 4 and between the second metal layer 3 and the second adhesive layer 5, so that the stress between the aluminum layer and the aluminum oxide layer is in a relatively balanced state, and the overall stress of the composite aluminum foil is released conveniently. In the winding process of the finished product roll of the composite current collector, the winding stress can be released in real time, so that the appearance defects such as wrinkles and bulges of the finished product roll are improved or eliminated, the appearance quality of the finished product roll is improved, and the production yield of the product is improved.
[0057] The above embodiment is only used for illustrating the technical concept and characteristics of the present application, and the purpose is to enable the person skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.
Claims
1. A composite current collector, comprising a substrate layer and a first metal layer and a second metal layer respectively disposed on both sides of the substrate layer in the thickness direction, characterized in that, The side of the first metal layer away from the substrate layer is the first surface, and the side of the second metal layer away from the substrate layer is the second surface. The surface roughness of the first surface and the second surface is different, and the difference in surface roughness Rz between the first surface and the second surface is in the range of 0.2-0.5 μm.
2. The composite current collector according to claim 1, characterized in that: A first adhesive layer is provided between the substrate layer and the first metal layer, and a second adhesive layer is provided between the substrate layer and the second metal layer.
3. The composite current collector according to claim 2, characterized in that: A plurality of first grooves are uniformly formed along the width direction on the outer surface of the first adhesive layer away from the substrate layer, and the first metal layer is filled in the first grooves. A plurality of second grooves are uniformly formed on the outer surface of the second adhesive layer away from the substrate layer along the width direction, and the second metal layer fills the second grooves.
4. The composite current collector according to claim 3, characterized in that: The first groove and the second groove are symmetrically arranged on both sides of the thickness direction of the substrate layer, or the first groove and the second groove are staggered in the width direction of the substrate layer.
5. The composite current collector according to claim 3 or 4, characterized in that: The first groove and the second groove have the same structure, and the depth-to-width ratio of the first groove and the second groove are both 1:2 and the groove spacing is both 0.02 to 0.05 μm.
6. The composite current collector according to claim 3 or 4, characterized in that: The first metal layer and the second metal layer have the same thickness, which is 0.8-1.5 μm. The first groove and the second groove are square grooves with the same structure. or, The first metal layer and the second metal layer have the same thickness and the thickness is less than 0.8 μm. The first groove and the second groove are both triangular grooves with the same structure. or, The first metal layer and the second metal layer have the same thickness and are greater than 1.5 μm. The first groove and the second groove are both semi-circular grooves with the same structure.
7. The composite current collector according to claim 2, characterized in that: The substrate layer has a thickness of 4-8 μm, and the first adhesive layer and the second adhesive layer have the same thickness of 0.01-0.10 μm.
8. The composite current collector according to claim 2, characterized in that: Both the first metal layer and the second metal layer are aluminum layers, and both the first adhesive layer and the second adhesive layer are aluminum oxide layers.
9. An electrode, characterized in that: Includes the composite current collector as described in any one of claims 1-8.
10. A battery, characterized in that: Includes the electrode as described in claim 9.