Composite current collector, composite pole piece comprising same, electrode assembly, secondary battery and electric device

Abstract

The invention provides a composite current collector, a composite pole piece comprising the composite current collector, a secondary battery and an electric device, the composite current collector comprises a first metal layer, an insulating layer and a second metal layer, and the insulating layer is located between the first metal layer and the second metal layer along the thickness direction of the composite current collector; in the width direction of the composite current collector, the composite current collector comprises a main body part and a plurality of convex parts extending out along the main body part, the plurality of convex parts are arranged at intervals in the length direction of the composite current collector, one part of the plurality of convex parts is used as a positive pole lug, and the other part of the plurality of convex parts is used as a negative pole lug; the single protruding part comprises a first area and a second area, and the first area is located between the second area and the main body part in the width direction; the first area serving as the protruding part of the positive electrode tab is a first metal layer, and the first area serving as the protruding part of the negative electrode tab is a second metal layer. The composite current collector is beneficial to improving the problems of short circuit and tab breakage between different tabs in an electrode assembly.

Description

Technical Field

[0001] The present application relates to the field of electrochemical technology, and in particular to a composite current collector and a composite pole piece, an electrode assembly, a secondary battery and an electrical device containing the same. Background Art

[0002] The bipolar composite current collector for secondary batteries is coated with a positive electrode material layer and a negative electrode material layer on both sides to obtain a bipolar composite pole piece. The bipolar composite pole piece and a separator are stacked and wound to form an electrode assembly. Bipolar composite pole pieces greatly simplify the production process, improve energy density, and reduce material costs. Therefore, they are widely used in secondary batteries, such as lithium-ion batteries and sodium-ion batteries.

[0003] For an electrode assembly composed of bipolar composite pole pieces, when used in a secondary battery, the different polarities on both sides of the bipolar composite pole pieces may easily cause a short circuit in the pole ears, thus affecting the safety of the secondary battery. Summary of the invention

[0004] The purpose of the present application is to provide a composite current collector and a composite pole piece, an electrode assembly, a secondary battery and an electrical device containing the same, so as to improve the problem of short circuit of the secondary battery tabs containing bipolar composite pole pieces, thereby improving the safety performance of the secondary battery. The specific technical solution is as follows:

[0005] The first aspect of the present application provides a composite current collector, characterized in that it includes: a first metal layer, an insulating layer and a second metal layer, along the thickness direction of the composite current collector, the insulating layer is located between the first metal layer and the second metal layer; along the width direction of the composite current collector, the composite current collector includes a main body and a plurality of protrusions extending along the main body, along the length direction of the composite current collector, the plurality of protrusions are arranged at intervals, a part of the plurality of protrusions serves as a positive electrode tab, and another part of the plurality of protrusions serves as a negative electrode tab; a single protrusion includes a first region and a second region, along the width direction, the first region is located between the second region and the main body; the first region of the protrusion serving as the positive electrode tab is the first metal layer, and the first region of the protrusion serving as the negative electrode tab is the second metal layer; the second region includes the first metal layer, the insulating layer, and the second metal layer. The composite current collector provided by the present application is conducive to improving the short circuit problem between different pole ears in the electrode assembly made of bipolar composite pole pieces; and the protrusion and the main body are an integrated structure, and there is no need to separately clean part of the positive electrode material layer or the negative electrode material layer for welding the positive electrode ear or the negative electrode ear, and there is no need to separately weld the positive electrode ear and the negative electrode ear, thus, it is conducive to simplifying the preparation process and reducing production costs. And the second region includes a first metal layer, an insulating layer, and a second metal layer, which is conducive to improving the strength of the second region and reducing the probability of ear breakage.

[0006] In some embodiments of the present application, along the width direction, the size of the positive electrode tab is the same as or different from the size of the negative electrode tab, which is beneficial to the processing of the composite current collector, or to distinguish the positive electrode tab and the negative electrode tab of the composite current collector, and further distinguish the positive electrode side and the negative electrode side of the composite electrode sheet.

[0007] In some embodiments of the present application, along the length direction, the size of the positive electrode tab is the same as or different from the size of the negative electrode tab, which is beneficial to the processing of the composite current collector, or to distinguish the positive electrode tab and the negative electrode tab of the composite current collector, and further distinguish the positive electrode side and the negative electrode side of the composite electrode sheet.

[0008] In some embodiments of the present application, along the width direction, the first regions of the plurality of protrusions have the same size, and the second regions of the plurality of protrusions have the same or different sizes. This is beneficial to the processing of the composite current collector, or to distinguish the positive electrode tab and the negative electrode tab of the composite current collector, and further distinguish the positive electrode side and the negative electrode side of the composite electrode sheet.

[0009] In some embodiments of the present application, along the width direction, the size of the first region accounts for 30% to 50% of the size of the protrusion. While improving the tab short circuit problem, it is also beneficial to improve the stability of the protrusion structure.

[0010] In some embodiments of the present application, the positive electrode tabs and the negative electrode tabs are alternately arranged along the length direction, which is beneficial to the processing of the electrode assembly.

[0011] In some embodiments of the present application, along the length direction, the positive electrode tabs and the negative electrode tabs are arranged alternately in two groups of tab combinations, namely, positive electrode tabs and negative electrode tabs, and negative electrode tabs and positive electrode tabs, which is beneficial to the processing of the electrode assembly.

[0012] In some embodiments of the present application, the positive electrode tab and the negative electrode tab are located on the same side in the width direction, and the electrode assembly made of the obtained composite current collector has universal applicability.

[0013] In some embodiments of the present application, the positive electrode tab and the negative electrode tab are independently located on two opposite sides in the width direction, and the electrode assembly made of the obtained composite current collector can adapt to different application scenarios.

[0014] In some embodiments of the present application, the thickness of the first metal layer is 1 μm to 8 μm, and the thickness of the second metal layer is 3 μm to 10 μm, which is conducive to obtaining a composite current collector with appropriate thickness, thereby obtaining a secondary battery with higher energy density.

[0015] In some embodiments of the present application, the material of the first metal layer includes aluminum or an aluminum alloy, and the material of the second metal layer includes copper or a copper alloy.

[0016] In some embodiments of the present application, the materials of the first metal layer and the second metal layer each independently include aluminum or an aluminum alloy.

[0017] The second aspect of the present application provides a composite pole piece, which includes the composite current collector in any of the aforementioned embodiments, which is beneficial to improving the pole ear short circuit problem and pole ear breakage problem of the bipolar composite pole piece, and is beneficial to simplifying the preparation process and has strong operability.

[0018] In some embodiments of the present application, the composite current collector also includes a positive electrode material layer arranged on the surface of the first metal layer and a negative electrode material layer arranged on the surface of the second metal layer; the positive electrode material layer includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate or lithium titanate; the negative electrode material layer includes at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon, silicon-carbon composite or silicon-oxygen composite.

[0019] In some embodiments of the present application, the composite current collector also includes a positive electrode material layer disposed on the surface of the first metal layer and a negative electrode material layer disposed on the surface of the second metal layer; the positive electrode material layer includes at least one of sodium nickel iron manganese oxide, sodium nickel copper manganese oxide, sodium iron pyrophosphate, sodium iron sulfate, Prussian white or Prussian blue; the negative electrode material layer includes at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon, silicon-carbon composite or silicon-oxygen composite.

[0020] The third aspect of the present application provides an electrode assembly, which includes the composite pole piece in any of the above embodiments. The composite pole piece made by the composite current collector of the present application is conducive to improving the short circuit problem of the pole ear of the bipolar composite pole piece, improving the strength of the pole ear, and simplifying the preparation process, and has strong operability, thereby improving the safety performance of the secondary battery and simplifying the preparation process of the secondary battery.

[0021] In some embodiments of the present application, the electrode assembly is a winding structure, and each turn of the electrode assembly includes a positive electrode tab and a negative electrode tab. Along the thickness direction of the positive electrode tab, the orthographic projections of each of the multiple positive electrode tabs at least partially overlap, and along the thickness direction of the negative electrode tab, the orthographic projections of each of the multiple negative electrode tabs at least partially overlap. It is beneficial to electrically connect multiple positive electrode tabs and electrically connect multiple negative electrode tabs. Multiple positive electrode tabs are stacked and electrically connected, which is beneficial to improve the strength of the positive electrode tab. Multiple negative electrode tabs are stacked and electrically connected, which is beneficial to improve the strength of the negative electrode tab.

[0022] In some embodiments of the present application, the positive electrode tabs and the negative electrode tabs of each circle of the electrode assembly constitute a tab group; along the length direction after the composite current collector is unfolded, the spacing between the positive electrode tabs and the negative electrode tabs in different tab groups is the same, the spacing between the positive electrode tabs in one tab group and the positive electrode tabs in another adjacent tab group is different, and the spacing between the negative electrode tabs in one tab group and the negative electrode tabs in another adjacent tab group is different.

[0023] In some embodiments of the present application, the electrode assembly is an S-shaped folded structure, and each layer of the electrode assembly includes a positive electrode tab and a negative electrode tab. Along the thickness direction of the electrode assembly, the orthographic projections of each of the multiple positive electrode tabs at least partially overlap, and the orthographic projections of each of the multiple negative electrode tabs at least partially overlap. It is beneficial to electrically connect multiple positive electrode tabs and electrically connect multiple negative electrode tabs. Multiple positive electrode tabs are stacked and electrically connected, which is beneficial to improve the strength of the positive electrode tab. Multiple negative electrode tabs are stacked and electrically connected, which is beneficial to improve the strength of the negative electrode tab.

[0024] In some embodiments of the present application, the positive electrode tabs and the negative electrode tabs of each layer of the electrode assembly form a tab group; along the length direction after the composite current collector is unfolded, the spacing between the positive electrode tabs and the negative electrode tabs in different tab groups is the same, the spacing between the positive electrode tabs in one tab group and the positive electrode tabs in another adjacent tab group is the same or different, and the spacing between the negative electrode tabs in one tab group and the negative electrode tabs in another adjacent tab group is the same or different.

[0025] The fourth aspect of the present application provides a secondary battery, which includes the electrode assembly of any of the aforementioned embodiments, which is beneficial to improving the problem of short circuit of the pole ear, increasing the strength of the pole ear, and simplifying the preparation process. It has strong operability, and thus is beneficial to improving the safety performance of the secondary battery and simplifying the preparation process of the secondary battery.

[0026] A fifth aspect of the present application provides an electrical device, which includes a secondary battery in any of the aforementioned embodiments, so that the electrical device provided by the present application has good performance.

[0027] Beneficial effects of this application:

[0028] The present application provides a composite current collector, which includes a first metal layer, an insulating layer and a second metal layer. Along the thickness direction of the composite current collector, the insulating layer is located between the first metal layer and the second metal layer; along the width direction of the composite current collector, the composite current collector includes a main body and a plurality of protrusions extending along the main body, along the length direction of the composite current collector, the plurality of protrusions are arranged at intervals, a part of the plurality of protrusions serves as a positive electrode tab, and another part of the plurality of protrusions serves as a negative electrode tab; a single protrusion includes a first region and a second region, along the width direction, the first region is located between the second region and the main body; the first region of the protrusion serving as the positive electrode tab is the first metal layer, and the first region of the protrusion serving as the negative electrode tab is the second metal layer; the second region includes the first metal layer, the insulating layer, and the second metal layer. The composite current collector provided by the present application is conducive to improving the short circuit problem between different pole ears in the electrode assembly made of bipolar composite pole pieces; and the protrusion and the main body are an integrated structure, and there is no need to separately clean part of the positive electrode material layer or the negative electrode material layer for welding the positive electrode ear or the negative electrode ear, and there is no need to separately weld the positive electrode ear and the negative electrode ear, thus, it is conducive to simplifying the preparation process and reducing production costs. And the second region includes a first metal layer, an insulating layer, and a second metal layer, which is conducive to improving the strength of the second region and reducing the probability of ear breakage.

[0029] Of course, implementing any product or method of the present application does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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 some embodiments of the present application, and for ordinary technicians in this field, other embodiments can also be obtained based on these drawings.

[0031] Figure 1 A schematic diagram of the cross-sectional structure of a composite current collector along its thickness direction in one embodiment of the present application;

[0032] Figure 2 A schematic diagram of the structure of a surface of a composite current collector in one embodiment of the present application;

[0033] Figure 3 for Figure 2 A schematic diagram of the structure of another surface of the composite current collector;

[0034] Figure 4 for Figure 2 Schematic diagram of the cross-sectional structure of the composite current collector along AA;

[0035] Figure 5 for Figure 2Schematic diagram of the cross-sectional structure of the composite current collector along BB;

[0036] Figure 6 A schematic diagram of the structure of a composite current collector in another embodiment of the present application;

[0037] Figure 7 A schematic diagram of the structure of an electrode assembly in one embodiment of the present application;

[0038] Figure 8 A schematic diagram of the structure of an electrode assembly in another embodiment of the present application;

[0039] Fig. 9 This is a schematic structural diagram of an electrode assembly in another embodiment of the present application;

[0040] Fig.10 This is a schematic structural diagram of an electrode assembly in another embodiment of the present application;

[0041] Fig.11 This is a schematic diagram of the structure of a composite current collector in another embodiment of the present application.

[0042] The reference numerals of the specific embodiments are as follows:

[0043] Composite current collector 01, first metal layer 10, second metal layer 20, insulating layer 30, main body 41, protrusion 42, first region 421, second region 422, positive electrode tab 11, negative electrode tab 21, composite pole piece 02, electrode assembly 03, positive electrode material layer 100, negative electrode material layer 200, separator 300, tab group 400, first tab group 401, second tab group 402, third tab group 403, fourth tab group 404, fifth tab group 405;

[0044] The width direction of the composite current collector is X, the length direction of the composite current collector is Y, and the thickness direction of the composite current collector is Z. DETAILED DESCRIPTION

[0045] The following will be combined with the embodiments of the present application and the accompanying drawings to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0046] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0047] In the description of the embodiments or implementation schemes of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0048] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. The various embodiments in the present application may be combined with each other in the absence of conflict.

[0049] For ease of understanding, in this application, a three-dimensional rectangular coordinate system is established with the width direction of the composite current collector as the X direction, the length direction as the Y direction, and the thickness direction as the Z direction. The above direction limitation is only used to understand the technical solution of this application and does not limit the protection scope of this application.

[0050] The first aspect of the present application provides a composite current collector, such as Figure 1 As shown, the composite current collector 01 includes a first metal layer 10, an insulating layer 30 and a second metal layer 20. Along the thickness direction Z of the composite current collector 01, the insulating layer 30 is located between the first metal layer 10 and the second metal layer 20. Figures 2 to 5As shown, along the width direction X of the composite current collector 01, the composite current collector 01 includes a main body 41 and a plurality of protrusions 42 extending along the main body 41. Along the length direction Y of the composite current collector 01, the plurality of protrusions 42 are arranged at intervals, a portion of the plurality of protrusions 42 serves as the positive electrode tab 11, and another portion of the plurality of protrusions 42 serves as the negative electrode tab 21. A single protrusion 42 includes a first region 421 and a second region 422. Along the width direction X, the first region 421 is located between the second region 422 and the main body 41; the first region 421 of the protrusion 42 serving as the positive electrode tab 11 is the first metal layer 10, and the first region 421 of the protrusion 42 serving as the negative electrode tab 21 is the second metal layer 20; the second region 422 includes the first metal layer 10, the insulating layer 30, and the second metal layer 20, and the stacking order is the same as that of the main body 41.

[0051] In the present application, the width direction of the composite current collector 01 is also the direction in which the protrusion 42 extends along the main body 41, the length direction of the composite current collector 01 is also the direction in which the plurality of protrusions 42 are arranged at intervals, and the thickness direction of the composite current collector 01 is also the direction perpendicular to both the width direction and the length direction.

[0052] The composite current collector 01 provided in the present application is used for a secondary battery with multiple tabs. It can be used as a positive tab of a secondary battery by stacking multiple protrusions 42 of the positive tab 11, electrically connecting the first metal layers 10 of multiple first regions 421, and then leading them out of the shell of the secondary battery through a conductive connector. In addition, the stacking of multiple first regions 421 can improve the structural stability of the positive tab 11. In addition, the second metal layer 20 in the second region 422 is not electrically connected to the main body 41 of the composite current collector 01, which is beneficial to improving the short circuit problem between different tabs, and the second region 422 has a three-layer structure, which is beneficial to improving the overall structural stability of the protrusion 42. Similarly, multiple protrusions 42 serving as negative electrode tabs 21 are stacked, and the second metal layers 20 of multiple first regions 421 are electrically connected, and then led out of the shell of the secondary battery through a conductive connector, so that they can serve as negative electrode tabs of the secondary battery, and the stacking of multiple first regions 421 can improve the structural stability of the negative electrode tab 21; in addition, the first metal layer 10 in the second region 422 is not electrically connected to the main body 41 of the composite current collector 01, which is beneficial to improving the short circuit problem between different tabs, and the second region 422 has a three-layer structure, which is beneficial to improving the overall structural stability of the protrusion 42. At the same time, the protrusion 42 and the main body 41 are an integrated structure. The composite current collector 01 of the above structure is used to prepare the bipolar composite pole piece 02. The positive electrode material layer 100 and the negative electrode material layer 200 are coated on the main body 41. There is no need to separately clean part of the positive electrode material layer 100 or the negative electrode material layer 200 for welding the positive electrode tab 11 or the negative electrode tab 21, and there is no need to separately weld the positive electrode tab 11 and the negative electrode tab 21. Therefore, the composite current collector 01 provided in the present application is conducive to simplifying the preparation process and reducing production costs.

[0053] In some embodiments of the present application, along the width direction X, the size of the positive electrode tab 11 is the same as the size of the negative electrode tab 21. Figure 6 As shown, along the width direction X, the size of the positive electrode tab 11 is h1, the size of the negative electrode tab 21 is h2, and h1=h2. For lithium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 are usually different. Along the width direction X, the size of the positive electrode tab 11 is the same as the size of the negative electrode tab 21, which is beneficial to the processing of the composite current collector 01. This application does not limit the size of the positive electrode tab 11 and the size of the negative electrode tab 21 along the width direction X, and can be selected according to actual conditions. In this application, when h1=h2, there may be tolerances caused by human or mechanical processing, which should also belong to h1=h2.

[0054] In some embodiments of the present application, along the width direction X, the size of the positive electrode tab 11 is different from the size of the negative electrode tab 21. Along the width direction X, the size of the positive electrode tab 11 is h1, and the size of the negative electrode tab 21 is h2, which can be h1>h2 or h1<h2. For sodium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 can be the same or similar, and along the width direction X, the size of the positive electrode tab 11 is different from the size of the negative electrode tab 21, which is conducive to distinguishing the positive electrode tab 11 and the negative electrode tab 21 of the composite current collector 01, and then distinguishing the positive side and the negative side of the composite electrode sheet 02. The present application does not limit the size of the positive electrode tab 11 and the size of the negative electrode tab 21 along the width direction X, as well as the difference between the two, and can be selected according to actual conditions.

[0055] In some embodiments of the present application, along the length direction Y, the size of the positive electrode tab 11 is the same as the size of the negative electrode tab 21. Figure 6 As shown, along the length direction Y, the size of the positive electrode tab 11 is w1, the size of the negative electrode tab 21 is w2, and w1=w2. For lithium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 are usually different. Along the length direction Y, the size of the positive electrode tab 11 is the same as the size of the negative electrode tab 21, which is beneficial to the processing of the composite current collector 01. This application does not limit the size of the positive electrode tab 11 and the size of the negative electrode tab 21 along the length direction Y, and can be selected according to actual conditions. In this application, when w1=w2, there may be tolerances caused by human or mechanical processing, which should also belong to w1=w2.

[0056] In some embodiments of the present application, along the length direction Y, the size of the positive electrode tab 11 is different from the size of the negative electrode tab 21. Along the length direction Y, the size of the positive electrode tab 11 is w1, and the size of the negative electrode tab 21 is w2, which can be w1>w2 or w1<w2. For sodium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 can be the same or similar, and along the length direction Y, the size of the positive electrode tab 11 is different from the size of the negative electrode tab 21, which is conducive to distinguishing the positive electrode tab 11 and the negative electrode tab 21 of the composite current collector 01, and then distinguishing the positive side and the negative side of the composite electrode sheet 02. The present application does not limit the size of the positive electrode tab 11 and the size of the negative electrode tab 21 along the length direction Y, as well as the difference between the two, and can be selected according to actual conditions.

[0057] In some embodiments of the present application, along the width direction X, the first regions 421 of the plurality of protrusions 42 have the same size, and the second regions 422 of the plurality of protrusions 42 have the same size. Figure 6As shown, along the width direction X, the size of the first region 421 is H1, the size of the second region 422 is H2, and multiple H1s are the same, and multiple H2s are also the same. For lithium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 are usually different. Along the width direction X, the sizes of multiple first regions 421 are the same, and the sizes of multiple second regions 422 are the same, which is beneficial to the processing of the composite current collector 01. This application does not limit the size of the first region 421 and the size of the second region 422 along the width direction X, and can be selected according to actual conditions. In this application, when multiple H1s are the same, there may be tolerances caused by human or mechanical processing, which should also belong to the same multiple H1s; when multiple H2s are the same, there may be tolerances caused by human or mechanical processing, which should also belong to the same multiple H2s.

[0058] In some embodiments of the present application, along the width direction X, the size of the first area 421 of the plurality of protrusions 42 is the same, and the size of the second area 422 of the plurality of protrusions 42 is different. Along the width direction X, the size of the first area 421 is H1, the size of the second area 422 is H2, and the plurality of H1s are the same, and the plurality of H2s are different. For sodium-ion secondary batteries, the materials of the first metal layer 10 and the second metal layer 20 are usually different. Along the width direction X, the sizes of the plurality of first areas 421 are the same, and the sizes of the plurality of second areas 422 are different, which is conducive to distinguishing the positive pole tab 11 and the negative pole tab 21 of the composite current collector 01, and then distinguishing the positive side and the negative side of the composite pole piece 02. The present application does not limit the size of the first area 421 and the size of the second area 422 along the width direction X, and can be selected according to actual conditions. In the present application, when multiple H1s are the same, there may be tolerances caused by human or mechanical processing, which should also belong to multiple H1s being the same.

[0059] In some embodiments of the present application, along the width direction X, the size of the first region 421 accounts for 30% to 50% of the size of the protrusion 42. For example, the size of the first region 421 accounts for 30%, 32%, 34%, 35%, 37%, 39%, 40%, 42%, 44%, 45%, 47%, 49%, 50% of the size of the protrusion 42, or a range consisting of any two values ​​therebetween. Specifically, as Figure 6 As shown, along the width direction X, the size of the first region 421 is H1, the size of the protrusion 42 is H, and 30%≤H1 / H×100%≤50%. Along the width direction X, the size of the first region 421 and the size of the protrusion 42 satisfy the above relationship, which not only improves the tab short circuit problem, but also helps to improve the stability of the protrusion 42 structure.

[0060] In some embodiments of the present application, the positive electrode tabs 11 and the negative electrode tabs 21 are alternately arranged along the length direction Y, so that the electrode assembly 03 obtained by winding or S-shaped folding is conducive to electrically connecting multiple positive electrode tabs 11 and electrically connecting multiple negative electrode tabs 21, which is conducive to the processing of the electrode assembly 03.

[0061] In some embodiments of the present application, Figure 6 As shown, along the length direction Y, the positive electrode tab 11 and the negative electrode tab 21 are arranged alternately in two groups of tab combinations, namely, the positive electrode tab 11 and the negative electrode tab 21, and the negative electrode tab 21 and the positive electrode tab 11. Thus, the electrode assembly 03 obtained by winding or S-shaped folding is conducive to electrically connecting multiple positive electrode tabs 11 and electrically connecting multiple negative electrode tabs 21, which is conducive to the processing of the electrode assembly 03.

[0062] In some embodiments of the present application, Figure 6 As shown, the positive electrode tab 11 and the negative electrode tab 21 are located on the same side in the width direction X. In this way, the electrode assembly 03 made of the obtained composite current collector 01 has universal applicability.

[0063] In some embodiments of the present application, the positive electrode tab 11 and the negative electrode tab 21 are independently located on two opposite sides in the width direction X. Specifically, all the positive electrode tabs 11 may be on one side in the width direction X, and all the negative electrode tabs 21 may be on the other side in the width direction X; or part of the positive electrode tabs 11 and part of the negative electrode tabs 21 may be on one side in the width direction X, and the remaining positive electrode tabs 11 and the remaining negative electrode tabs 21 may be on the other side in the width direction X. In this way, the electrode assembly 03 made of the obtained composite current collector 01 can adapt to different application scenarios.

[0064] In some embodiments of the present application, Figure 1 As shown, along the thickness direction Z, the thickness of the first metal layer 10 is T1, and the thickness of the second metal layer 20 is T2. The thickness T1 of the first metal layer 10 is 1 μm to 8 μm, and the thickness T2 of the second metal layer 20 is 3 μm to 10 μm. For example, the thickness T1 of the first metal layer 10 can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, or a range consisting of any two values ​​therebetween. For example, the thickness T2 of the second metal layer 20 can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or a range consisting of any two values ​​therebetween. By regulating the thickness T1 of the first metal layer 10 and the thickness T2 of the second metal layer 20 within the above range, it is beneficial to obtain a composite current collector 01 with a suitable thickness, and then obtain a secondary battery with a higher energy density.

[0065] In some embodiments of the present application, the thickness of the insulating layer 30 may be 2 μm to 20 μm. In some embodiments of the present application, the thickness of the composite current collector 01 may be 6 μm to 35 μm.

[0066] In some embodiments of the present application, the composite current collector 01 is used in a lithium-ion secondary battery, the material of the first metal layer 10 includes aluminum or an aluminum alloy, and the material of the second metal layer 20 includes copper or a copper alloy.

[0067] In some embodiments of the present application, the composite current collector 01 is used for a sodium ion secondary battery, and the materials of the first metal layer 10 and the second metal layer 20 each independently include aluminum or an aluminum alloy.

[0068] The present application has no particular restrictions on the preparation method of the composite current collector 01, as long as the purpose of the present application can be achieved. Exemplarily, the preparation method of the composite current collector 01 may include but is not limited to the following preparation steps: a first metal layer 10 is provided on one surface of the insulating layer 30, a second metal layer 20 is provided on another surface of the insulating layer 30, and then the main body 41 and a plurality of protrusions 42 of the composite current collector 01 are obtained by cutting, and according to the required arrangement of the positive electrode tab 11 and the negative electrode tab 21, the insulating layer 30 and the second metal layer 20 in the first area 421 of some protrusions 42 are removed to obtain the positive electrode tab 11; the insulating layer 30 and the first metal layer 10 in the first area 421 of the remaining protrusions 42 are removed to obtain the negative electrode tab 21. The present application has no particular restrictions on the manner of setting the first metal layer 10 and the second metal layer 20, as long as the purpose of the present application can be achieved. Exemplarily, the first metal layer 10 and the second metal layer 20 are set by magnetron sputtering. The present application has no particular limitation on the method of removing the insulating layer 30 and the first metal layer 10 , the insulating layer 30 and the second metal layer 20 , as long as the purpose of the present application can be achieved. Exemplarily, laser cleaning is used for removal.

[0069] The second aspect of the present application provides a composite pole piece 02, which includes the composite current collector 01 in any of the above embodiments. The composite pole piece 02 made by using the composite current collector 01 of the present application is conducive to improving the tab short circuit problem of the bipolar composite pole piece 02, and is conducive to simplifying the preparation process and having strong operability.

[0070] In some embodiments of the present application, the composite pole piece 02 further includes a positive electrode material layer 100 disposed on the surface of the first metal layer 10 and a negative electrode material layer 200 disposed on the surface of the second metal layer 20. The composite pole piece 02 is used for a lithium-ion secondary battery, and the positive electrode material layer 100 includes at least one of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based materials, lithium cobalt oxide, lithium manganese oxide, lithium iron manganese phosphate, or lithium titanate; the negative electrode material layer 200 includes at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon, silicon-carbon composite, or silicon-oxygen composite.

[0071] In some embodiments of the present application, the composite current collector 01 further includes a positive electrode material layer 100 disposed on the surface of the first metal layer 10 and a negative electrode material layer 200 disposed on the surface of the second metal layer 20. The composite pole piece 02 is used for a sodium ion secondary battery, and the positive electrode material layer 100 includes at least one of sodium nickel iron manganese oxide, sodium nickel copper manganese oxide, sodium iron pyrophosphate, sodium iron sulfate, Prussian white or Prussian blue; the negative electrode material layer 200 includes at least one of natural graphite, artificial graphite, hard carbon, soft carbon, silicon, silicon-carbon composite or silicon-oxygen composite.

[0072] The present application has no particular limitation on the thickness of the positive electrode material layer 100, as long as the purpose of the present application can be achieved. For example, the thickness of the positive electrode material layer 100 is 30 μm to 120 μm. The present application has no particular limitation on the thickness of the negative electrode material layer 200, as long as the purpose of the present application can be achieved. For example, the thickness of the negative electrode material layer 200 is 30 μm to 120 μm.

[0073] In the present application, the positive electrode material layer 100 and the negative electrode material layer 200 may also include a conductive agent and a binder, as well as optional additives. The present application does not limit the types of the above conductive agents, binders and additives, and conventional conductive agents, binders and additives in the art may be used as long as the purpose of the present application can be achieved.

[0074] Exemplarily, the conductive agent may include but is not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, graphene, metal materials or conductive polymers. The above-mentioned carbon nanotubes may include but are not limited to single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The above-mentioned carbon fibers may include but are not limited to vapor-grown carbon fibers (VGCF) and / or nano-carbon fibers. The above-mentioned metal materials may include but are not limited to metal powders and / or metal fibers, and specifically, the metal may include but is not limited to at least one of copper, nickel, aluminum or silver. The above-mentioned conductive polymers may include but are not limited to at least one of polyphenylene derivatives, polyaniline, polythiophene, polyacetylene or polypyrrole.

[0075] Exemplarily, the binder may include, but is not limited to, at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyimide, polyamide-imide, styrene-butadiene rubber, or polyvinylidene fluoride.

[0076] The third aspect of the present application provides an electrode assembly 03, which includes the composite pole piece 02 in any of the above embodiments. The electrode assembly 03 made using the composite pole piece 02 of the present application is conducive to improving the tab short circuit and tab breakage problems of the bipolar composite pole piece 02, and is conducive to simplifying the preparation process and having strong operability.

[0077] In the present application, the thickness direction of the positive electrode tab 11 and the negative electrode tab 21 is also the thickness direction Z of the composite current collector 01 .

[0078] In some embodiments of the present application, Figure 7 and Figure 8 As shown, the electrode assembly 03 is a winding structure, which includes a composite electrode sheet 02 and a separator 300. Each turn of the electrode assembly 03 includes a positive electrode tab 11 and a negative electrode tab 21. Along the thickness direction of the positive electrode tab 11, the orthographic projections of each of the plurality of positive electrode tabs 11 at least partially overlap, and along the thickness direction of the negative electrode tab 21, the orthographic projections of each of the plurality of negative electrode tabs 21 at least partially overlap. That is, along the thickness direction Z, it can be as follows Figure 7 As shown, the orthographic projections of each of the plurality of positive electrode tabs 11 completely overlap, and the orthographic projections of each of the plurality of negative electrode tabs 21 completely overlap; it may also be as follows Figure 8 As shown, the orthographic projections of each of the multiple positive pole tabs 11 partially overlap, and the orthographic projections of each of the multiple negative pole tabs 21 partially overlap; it can also be that the orthographic projections of each of the multiple positive pole tabs 11 completely overlap, and the orthographic projections of each of the multiple negative pole tabs 21 partially overlap; it can also be that the orthographic projections of each of the multiple positive pole tabs 11 partially overlap, and the orthographic projections of each of the multiple negative pole tabs 21 completely overlap. In this way, it is beneficial to electrically connect multiple positive pole tabs 11 and multiple negative pole tabs 21. Multiple positive pole tabs 11 are stacked and electrically connected, which is beneficial to improve the strength of the positive pole tabs 11 and reduce the probability of fracture. Multiple negative pole tabs 21 are stacked and electrically connected, which is beneficial to improve the strength of the negative pole tabs 21 and reduce the probability of fracture.

[0079] In some embodiments of the present application, Figure 6 and Figure 7As shown, the electrode assembly 03 is a winding structure, and the positive electrode tab 11 and the negative electrode tab 21 of each circle of the electrode assembly 03 form a tab group 400. Along the length direction Y after the composite current collector 01 is unfolded, the spacing L between the positive electrode tabs 11 and the negative electrode tabs 21 in different tab groups 400 is the same, that is, L in different tab groups 400 is the same. The spacing between the positive electrode tab 11 in one tab group 400 and the positive electrode tab 11 in another adjacent tab group 400 is different, that is, L1 and L2 are different. The spacing between the negative electrode tab 21 in one tab group 400 and the negative electrode tab 21 in another adjacent tab group 400 is different, that is, L3 and L4 are different. In this way, along the thickness direction Z, the orthographic projections of each of the multiple positive electrode tabs 11 are at least partially overlapped, and the orthographic projections of each of the multiple negative electrode tabs 21 are at least partially overlapped, thereby achieving electrical connection between the multiple positive electrode tabs 11 and the multiple negative electrode tabs 21.

[0080] In some embodiments of the present application, Fig. 9 and Fig.10 As shown, the electrode assembly 03 is an S-shaped folded structure, which includes a composite electrode sheet 02 and a separator 300. Each layer of the electrode assembly 03 includes a positive electrode tab 11 and a negative electrode tab 21. Along the thickness direction of the electrode assembly 03, the orthographic projections of each of the plurality of positive electrode tabs 11 at least partially overlap, and the orthographic projections of each of the plurality of negative electrode tabs 21 at least partially overlap. That is, along the thickness direction Z, as shown in FIG. Fig. 9 As shown, the orthographic projections of each of the plurality of positive electrode tabs 11 completely overlap, and the orthographic projections of each of the plurality of negative electrode tabs 21 completely overlap; it may also be as follows Fig.10 As shown, the orthographic projections of each of the multiple positive pole tabs 11 completely overlap, and the orthographic projections of each of the multiple negative pole tabs 21 partially overlap; it can also be that the orthographic projections of each of the multiple positive pole tabs 11 partially overlap, and the orthographic projections of each of the multiple negative pole tabs 21 partially overlap; it can also be that the orthographic projections of each of the multiple positive pole tabs 11 partially overlap, and the orthographic projections of each of the multiple negative pole tabs 21 completely overlap. In this way, it is beneficial to electrically connect multiple positive pole tabs 11 and multiple negative pole tabs 21. In the present application, when the electrode assembly 03 is an S-shaped folding structure, the thickness direction of the electrode assembly 03 is also the thickness direction Z of the composite current collector 01. Multiple positive pole tabs 11 are stacked and electrically connected, which is beneficial to improve the strength of the positive pole tab 11 and reduce the probability of fracture. Multiple negative pole tabs 21 are stacked and electrically connected, which is beneficial to improve the strength of the negative pole tab 21 and reduce the probability of fracture.

[0081] In some embodiments of the present application, Figure 6 and Fig.11As shown, the electrode assembly 03 is an S-shaped folded structure, and the positive electrode tab 11 and the negative electrode tab 21 of each layer of the electrode assembly 03 form a tab group 400, and the tab group 400 includes a first tab group 401, a second tab group 402, a third tab group 403, a fourth tab group 404, and a fifth tab group 405. Fig.11 As shown, along the length direction Y after the composite current collector 01 is unfolded, the spacing S between the positive electrode tabs 11 and the negative electrode tabs 21 in different tab groups 400 is the same, that is, S in different tab groups 400 is the same. The spacing between the positive electrode tabs 11 in one tab group 400 and the positive electrode tabs 11 in another adjacent tab group 400 is the same or different, and the spacing between the negative electrode tabs 21 in one tab group 400 and the negative electrode tabs 21 in another adjacent tab group 400 is the same or different. Specifically, as Fig.11 As shown, the spacing between the positive electrode tab 11 in the first electrode tab group 401 and the positive electrode tab 11 in the adjacent second electrode tab group 402 is S11, the spacing between the positive electrode tab 11 in the third electrode tab group 403 and the positive electrode tab 11 in the adjacent fourth electrode tab group 404 is S12, the spacing between the positive electrode tab 11 in the second electrode tab group 402 and the positive electrode tab 11 in the adjacent third electrode tab group 403 is S21, and the spacing between the positive electrode tab 11 in the fourth electrode tab group 404 and the positive electrode tab 11 in the adjacent fifth electrode tab group 405 is S22, wherein S11=S12, S21=S22, S11≠S21, S12≠S22. The distance between the negative electrode tab 21 in the first tab group 401 and the negative electrode tab 21 in the adjacent second tab group 402 is S31, the distance between the negative electrode tab 21 in the third tab group 403 and the negative electrode tab 21 in the adjacent fourth tab group 404 is S32, the distance between the negative electrode tab 21 in the second tab group 402 and the negative electrode tab 21 in the adjacent third tab group 403 is S41, and the distance between the negative electrode tab 21 in the fourth tab group 404 and the negative electrode tab 21 in the adjacent fifth tab group 405 is S42, wherein S31=S32, S41=S42, S31≠S41, S32≠S42. In the present application, when the above dimensions are equal, there may be tolerances caused by human or mechanical processing, which should also belong to the equal situation.

[0082] The present application does not limit the separator in the electrode assembly, and a conventional separator known in the art can be used as long as the purpose of the present application can be achieved. Exemplarily, the material of the separator may include, but is not limited to, polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (e.g., polyethylene terephthalate (PET) films), cellulose, polyimide (PI), polyamide (PA), spandex or aramid. The type of separator may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane or a spun membrane.

[0083] In some embodiments of the present application, the isolation membrane may include a substrate layer and a surface treatment layer. The substrate layer may be a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate or polyimide. Optionally, a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric or a polypropylene-polyethylene-polypropylene porous composite film may be used. Optionally, a surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance. For example, the inorganic layer includes inorganic particles and a binder, and the inorganic particles are not particularly limited, for example, they may include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate. The binder is not particularly limited, for example, it may be at least one of the above-mentioned binders. The polymer layer contains polymers, and the polymer material includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinyl pyrrolidone, polyvinyl ether, polyvinylidene fluoride, or poly(vinylidene fluoride-hexafluoropropylene).

[0084] The fourth aspect of the present application provides a secondary battery, which includes the electrode assembly of any of the aforementioned embodiments, which is beneficial to improving the tab short circuit problem and tab breakage problem of the bipolar composite pole piece, and is beneficial to simplifying the preparation process and has strong operability, thereby helping to improve the safety performance of the secondary battery and simplify the preparation process of the secondary battery.

[0085] A fifth aspect of the present application provides an electrical device, which includes a secondary battery in any of the aforementioned embodiments, so that the electrical device provided by the present application has good performance.

[0086] In the present application, the secondary battery also includes a shell for accommodating an electrode assembly and an electrolyte, as well as other components known in the field of secondary batteries, and the present application does not limit the above-mentioned other components. The present application has no particular restrictions on the shell, and it can be a shell known in the art, as long as the purpose of the present application can be achieved. For example, the shell can be a hard shell or a flexible shell. The material of the hard shell can be metal, and the present application does not limit the type of metal, and a metal hard shell known in the art can be used, as long as the purpose of the present application can be achieved. The flexible shell can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.

[0087] The present application does not limit the electrolyte, and any electrolyte known in the art may be used as long as the purpose of the present application can be achieved.

[0088] The present application does not specifically limit the type of electrical device, which may be any electrical device known in the prior art. For example, the electrical device may include, but is not limited to, a computer, a smart phone, a backup power supply, a two-wheeled vehicle, a drone, a power tool, or an energy storage device.

[0089] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A composite current collector, characterized in that: include: A first metal layer, an insulating layer and a second metal layer, wherein along the thickness direction of the composite current collector, the insulating layer is located between the first metal layer and the second metal layer; Along the width direction of the composite current collector, the composite current collector includes a main body and a plurality of protrusions extending along the main body, and along the length direction of the composite current collector, the plurality of protrusions are arranged at intervals, a part of the plurality of protrusions serves as a positive electrode tab, and another part of the plurality of protrusions serves as a negative electrode tab; a single protrusion includes a first region and a second region, and along the width direction, the first region is located between the second region and the main body; the first region of the protrusion serving as the positive electrode tab is the first metal layer, and the first region of the protrusion serving as the negative electrode tab is the second metal layer; the second region includes the first metal layer, the insulating layer, and the second metal layer.

2. The composite current collector according to claim 1, wherein: Along the width direction, the size of the positive electrode tab is the same as or different from the size of the negative electrode tab.

3. The composite current collector according to claim 1, wherein: Along the length direction, the size of the positive electrode tab is the same as or different from the size of the negative electrode tab.

4. The composite current collector according to claim 1, wherein: Along the width direction, the first regions of the plurality of protrusions have the same size, and the second regions of the plurality of protrusions have the same size or different sizes.

5. The composite current collector according to claim 1, wherein: Along the width direction, the size of the first region accounts for 30% to 50% of the size of the protruding portion.

6. The composite current collector according to claim 1, wherein: Along the length direction, the positive electrode tabs and the negative electrode tabs are arranged alternately.

7. The composite current collector according to claim 6, wherein: Along the length direction, the positive electrode tabs and the negative electrode tabs are arranged alternately in two groups of tab combinations: positive electrode tabs and negative electrode tabs, and negative electrode tabs and positive electrode tabs.

8. The composite current collector according to claim 1, wherein: The positive electrode tab and the negative electrode tab are located on the same side in the width direction.

9. The composite current collector according to claim 1, wherein: The positive electrode tab and the negative electrode tab are independently located on two opposite sides in the width direction.

10. The composite current collector according to any one of claims 1 to 9, wherein: The thickness of the first metal layer is 1 μm to 8 μm, and the thickness of the second metal layer is 3 μm to 10 μm.

11. The composite current collector according to any one of claims 1 to 9, wherein: The material of the first metal layer includes aluminum or an aluminum alloy, and the material of the second metal layer includes copper or a copper alloy.

12. The composite current collector according to any one of claims 1 to 9, wherein: The materials of the first metal layer and the second metal layer each independently include aluminum or an aluminum alloy.

13. A composite pole piece, comprising the composite current collector according to any one of claims 1 to 12.

14. An electrode assembly comprising the composite electrode sheet according to claim 13.

15. The electrode assembly according to claim 14 is a winding structure, each circle of the electrode assembly includes one positive electrode tab and one negative electrode tab, along the thickness direction of the positive electrode tab, the orthographic projections of each of the multiple positive electrode tabs at least partially overlap, and along the thickness direction of the negative electrode tab, the orthographic projections of each of the multiple negative electrode tabs at least partially overlap.

16. The electrode assembly according to claim 15, wherein: The positive electrode tab and the negative electrode tab of each circle of the electrode assembly form a tab group; Along the length direction of the composite current collector after unfolding, the spacing between the positive electrode tabs and the negative electrode tabs in different tab groups is the same, the spacing between the positive electrode tabs in one tab group and the positive electrode tabs in another adjacent tab group is different, and the spacing between the negative electrode tabs in one tab group and the negative electrode tabs in another adjacent tab group is different.

17. The electrode assembly according to claim 14 has an S-shaped folding structure, and each layer of the electrode assembly includes one positive electrode tab and one negative electrode tab, and along the thickness direction of the electrode assembly, the orthographic projections of each of the multiple positive electrode tabs at least partially overlap, and the orthographic projections of each of the multiple negative electrode tabs at least partially overlap.

18. The electrode assembly according to claim 17, wherein: The positive electrode tab and the negative electrode tab of each layer of the electrode assembly form a tab group; Along the length direction of the composite current collector after unfolding, the spacing between the positive electrode tabs and the negative electrode tabs in different tab groups is the same, the spacing between the positive electrode tabs in one tab group and the positive electrode tabs in another adjacent tab group is the same or different, and the spacing between the negative electrode tabs in one tab group and the negative electrode tabs in another adjacent tab group is the same or different. 19 . A secondary battery comprising the electrode assembly according to claim 14 .

20. An electric device comprising the secondary battery according to claim 19.

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