Composite current collector, pole piece, battery cell, battery and vehicle

Abstract

The invention provides a composite current collector, a pole piece, a battery cell, a battery and a vehicle, the composite current collector comprises an insulating layer, a first conductive layer and a second conductive layer, the first conductive layer and the second conductive layer are respectively located at two sides of the insulating layer in the thickness direction; the thickness of the insulating layer in the direction from one end of the insulating layer to the other end of the insulating layer is gradually reduced, and the first conductive layer and the second conductive layer extend towards each other in the direction from one end of the insulating layer to the other end of the insulating layer and intersect to form a tab. The tab is formed by intersecting a part of the first conductive layer and a part of the second conductive layer of the composite current collector structure, that is, the tab, the first conductive layer and the second conductive layer are of an integrated structure, so that the production efficiency and the yield can be improved, and the tab does not need to be externally connected by adopting processes such as welding, so that the cost can be effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a composite current collector, a pole piece, a battery cell, a battery and a vehicle. Background Art

[0002] The battery cell is an important component of the battery, and the battery cell includes a pole piece, wherein the pole piece includes a current collector and an active material layer arranged on the current collector.

[0003] In the related art, the current collector is usually a composite current collector with a sandwich structure, which includes an insulating layer and a conductive layer located on both sides of the insulating layer in the thickness direction. The composite current collector is not only lightweight but also can effectively improve the energy density of the battery, so it has been widely used.

[0004] In the process of preparing batteries, the composite current collector and the pole ear are usually connected by ultrasonic roll welding. This method is not only costly, but also has low efficiency and finished product quality rate, and cannot meet actual production needs. Summary of the invention

[0005] In view of this, the present invention is committed to providing a composite current collector, a pole piece, a battery cell, a battery and a vehicle to solve the problems of high connection cost, low efficiency and low quality rate of the composite current collector and the pole piece.

[0006] In a first aspect, the present invention provides a composite current collector, comprising an insulating layer, a first conductive layer and a second conductive layer; in a thickness direction of the insulating layer, the first conductive layer and the second conductive layer are disposed on opposite sides of the insulating layer;

[0007] The thickness of the insulating layer gradually decreases from one end of the insulating layer to the other end of the insulating layer, and the first conductive layer and the second conductive layer extend toward each other and meet at the other end of the insulating layer to form a tab.

[0008] In some embodiments, in a direction from one end of the insulating layer to the other end of the insulating layer, the thickness of the first conductive layer gradually increases, and a surface of the first conductive layer away from the insulating layer is horizontally arranged;

[0009] And / or, in a direction from one end of the insulating layer to the other end of the insulating layer, the thickness of the second conductive layer gradually increases, and a surface of the second conductive layer away from the insulating layer is arranged horizontally.

[0010] In some embodiments, the composite current collector structure further includes a first primer layer and a second primer layer, wherein the first primer layer is disposed on a side of the first conductive layer away from the insulating layer, and the second primer layer is disposed on a side of the second conductive layer away from the insulating layer.

[0011] In some embodiments, in a direction from one end of the insulating layer to the other end of the insulating layer, the thickness of at least one of the first conductive layer and the first primer layer gradually increases, and a surface of the first primer layer away from the first conductive layer is horizontally arranged;

[0012] And / or, in the direction from one end of the insulating layer to the other end of the insulating layer, the thickness of at least one of the second conductive layer and the second primer layer gradually increases, and the side of the second primer layer away from the second conductive layer is horizontally arranged.

[0013] In some embodiments, a plurality of rough structures are provided on a side of the first conductive layer close to the first primer layer and / or a side of the second conductive layer close to the second primer layer, and the plurality of rough structures are spaced apart in a direction from one end of the insulating layer to the other end of the insulating layer.

[0014] In some embodiments, the roughness structure includes a groove formed by being recessed in a direction approaching the insulating layer.

[0015] In some embodiments, a dimension h1 of the groove in a direction from one end of the insulating layer to the other end of the insulating layer satisfies: 0.8 μm≤h1≤1.2 μm;

[0016] And / or, a dimension h2 of the groove along the thickness direction of the insulating layer satisfies: 0.3 μm≤h2≤0.7 μm.

[0017] In some embodiments, the thickness h3 of the insulating layer satisfies: 0 μm≤h3≤50 μm;

[0018] and / or, the thickness h4 of the first conductive layer satisfies: 0.5 μm≤h4≤25 μm; and / or,

[0019] The thickness h5 of the second conductive layer satisfies: 0.5 μm≤h5≤25 μm;

[0020] And / or, the thickness h6 of the tab satisfies: 1 μm≤h6≤50 μm;

[0021] And / or, the thickness h7 of the first primer layer satisfies: 0 μm<h7≤5 μm;

[0022] And / or, the thickness h8 of the second primer layer satisfies: 0 μm<h8≤5 μm.

[0023] In some embodiments, the first conductive layer and the second conductive layer are symmetrically arranged relative to the central axis of the insulating layer;

[0024] And / or, the first primer layer and the second primer layer are symmetrically arranged relative to the central axis of the insulating layer.

[0025] In a second aspect, the present invention provides a pole piece comprising the composite current collector as described above.

[0026] In a third aspect, the present invention provides a battery cell comprising the pole piece as described above.

[0027] In a fourth aspect, the present invention provides a battery, comprising the battery cell as described above.

[0028] In a fifth aspect, the present invention provides a vehicle comprising the battery as described above.

[0029] The present invention provides a composite current collector, a pole piece, a battery cell, a battery and a vehicle. The composite current collector includes an insulating layer, a first conductive layer and a second conductive layer. The first conductive layer and the second conductive layer are respectively located on both sides of the insulating layer in the thickness direction thereof, and the thickness of the insulating layer is gradually reduced along the direction from one end of the insulating layer to the other end, so that the first conductive layer and the second conductive layer can be extended in the direction from one end of the insulating layer to the other end of the insulating layer toward each other, and then it is convenient to intersect at the other end of the insulating layer to form a pole ear, that is, the first conductive layer and the second conductive layer can be intersected together without bending, so that the operation can be simplified, and the problem of stress concentration at the bending point due to bending and intersection can be avoided. At the same time, the pole ear in the present invention is formed by the intersection of part of the first conductive layer and part of the second conductive layer of the composite current collector structure, that is, the pole ear, the first conductive layer and the second conductive layer are an integrated structure, so that not only the production efficiency and the superior rate can be improved, but also the cost can be effectively reduced because there is no need to use welding and other processes to connect the pole ear. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The structure of the composite current collector according to the embodiment of the present invention is shown as follows Figure 1 ;

[0031] Figure 2 The structure of the composite current collector according to the embodiment of the present invention is shown as follows Figure 2 ;

[0032] Figure 3 The structure of the composite current collector according to the embodiment of the present invention is shown as follows Figure 3 .

[0033] Among them, 100, insulating layer; 200, first conductive layer; 300, second conductive layer; 400, tab; 500, first primer layer; 600, second primer layer; 700, rough structure; 710, groove. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Reference Figures 1 to 3 As shown, this embodiment provides a composite current collector, including an insulating layer 100, a first conductive layer 200 and a second conductive layer 300. In the thickness direction of the insulating layer 100, the first conductive layer 200 and the second conductive layer 300 are disposed on opposite sides of the insulating layer 100.

[0036] In the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the thickness of the insulating layer 100 gradually decreases, and in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the first conductive layer 200 and the second conductive layer 300 extend toward each other and meet at the other end of the insulating layer 100 to form a pole ear 400.

[0037] In a specific implementation, the composite current collector may include: Figure 1 The first conductive layer 200, the insulating layer 100 and the second conductive layer 300 are arranged in sequence in the y direction as shown, that is, the insulating layer 100 is located between the first conductive layer 200 and the second conductive layer 300, so as to avoid the problem that the composite current collector is easily short-circuited or catches fire in the puncture and impact tests due to the direct contact and conduction between the first conductive layer 200 and the second conductive layer 300.

[0038] In the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the specific Figure 1 In the x direction shown, the thickness of the insulating layer 100 gradually decreases, so that the first conductive layer 200 and the second conductive layer 300 located on opposite sides of the insulating layer 100 can be inclined and extended in a direction close to each other so as to intersect together to form the tab 400. Compared with the method of not setting the thickness change of the insulating layer 100 and requiring at least one of the first conductive layer 200 and the second conductive layer 300 to be bent to achieve the intersection, the first conductive layer 200 and the second conductive layer 300 of this embodiment can intersect naturally without bending, so there is no bending point, thereby avoiding the problem of stress concentration at the bending point that easily causes strength damage.

[0039] It can be seen that in this embodiment, by making the first conductive layer 200 and the second conductive layer 300 extend obliquely toward each other in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100 and intersect to form the pole ear 400, not only can the electrical connection between the first conductive layer 200 and the second conductive layer 300 be achieved, but the pole ear 400 is an integrated structure with the first conductive layer 200 and the second conductive layer 300, so there is no need for additional welding of the pole ear, which can effectively reduce the production cost and improve the production efficiency and quality rate.

[0040] In addition, in the present embodiment, by making the first conductive layer 200, the second conductive layer 300 and the tab 400 an integrated structure, there is no need to weld the two by ultrasonic roller welding, that is, there is no welding point between the two, which can also avoid the problems of large overcurrent and high temperature at the welding point, and then optimize the performance of the battery cell with the composite current collector.

[0041] For example, the cross-sectional shape of the insulating layer 100 may be a triangle shape, or the cross-sectional shape of the insulating layer 100 may be as follows: Figures 1 to 3 Trapezoid shape shown.

[0042] In addition, in the present embodiment, the insulating layer 100 is disposed between the first conductive layer 200 and the second conductive layer 300, which can not only provide reliable support for the first conductive layer 200 and the second conductive layer 300, but also avoid problems such as short circuits caused by direct contact between the first conductive layer 200 and the second conductive layer 300, thereby effectively improving the safety performance of the battery cell.

[0043] In addition, by disposing the insulating layer 100 between the first conductive layer 200 and the second conductive layer 300, the insulating layer 100 can be made of a material with low density and light weight, so as to improve the energy density of the battery cell having the composite current collector.

[0044] Exemplarily, the material of the insulating layer 100 can be selected from at least one of polyethylene terephthalate, polyimide, polybutylene terephthalate, polyetheretherketone, polyamide, polycarbonate, cyclic polyolefin, polyphenylene sulfide, polyethylene naphthalate, polypropylene carbonate, polyvinylidene fluoride-hexafluoropropylene, polyvinyl acetate, polytetrafluoroethylene, polymethylene naphthalene, polyvinylidene fluoride, polyethylene glycol, polyamideimide, polyethylene naphthalate, poly(vinylidene fluoride-co-chlorotrifluoroethylene), silicone, vinylon, polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyether nitrile, polyurethane, polyphenylene ether, polyester and polysulfone and their derivatives.

[0045] For example, the first conductive layer 200 and the second conductive layer 300 may be disposed on the surfaces of the insulating layer 100 at opposite sides by using any one of sputtering, vacuum deposition, ion plating, and laser pulse deposition.

[0046] Exemplarily, the material of the first conductive layer 200 and the second conductive layer 300 can be selected from at least one of Ni (nickel), Ti (titanium), Cu (copper), Ag (silver), Au (gold), Pt (platinum), Fe (iron), Co (cobalt), Cr (chromium), W (tungsten), Mo (molybdenum), Al (aluminum), Mg (magnesium), K (potassium), Na (sodium), Ca (calcium), Sr (strontium), Ba (barium), Si (silicon), Ge (germanium), Sb (antimony), Pb (lead), In (indium), Zn (zinc) and their combinations (alloys).

[0047] For example, in order to ensure the processing yield, the processing materials of the composite current collector usually leave a certain processing margin, so the composite current collector is Figure 1 The dimension in the x-direction shown is equivalent to the sum of the dimension of the insulating layer 100 in the x-direction, the dimension of the tab 400 in the x-direction, and the dimension of the machining allowance in the x-direction.

[0048] The composite current collector of this embodiment includes an insulating layer 100, a first conductive layer 200 and a second conductive layer 300, wherein the first conductive layer 200 and the second conductive layer 300 are respectively located on both sides of the insulating layer 100 in the thickness direction thereof, and by setting the thickness of the insulating layer 100 to gradually decrease in the direction from one end to the other end thereof, the first conductive layer 200 and the second conductive layer 300 can be extended toward each other in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, so that they can easily intersect at the other end of the insulating layer 100 to form a pole ear 400, that is, the first conductive layer 200 and the second conductive layer 300 can intersect together without bending, thereby simplifying the operation and avoiding the problem of stress concentration at the bending point due to bending and intersection, which may lead to damage to the structural strength. That is to say, the pole tab 400 in this embodiment is formed by the intersection of part of the first conductive layer 200 and part of the second conductive layer 300 of the composite current collector structure, that is, the pole tab 400, the first conductive layer 200 and the second conductive layer 300 are an integrated structure, which can not only improve production efficiency and quality rate, but also effectively reduce costs because there is no need to use welding and other processes to externally connect the pole tab.

[0049] Reference Figures 1 to 3 As shown, in some embodiments, the thickness of the first conductive layer 200 gradually increases from one end of the insulating layer 100 to the other end of the insulating layer 100 , and a surface of the first conductive layer 200 away from the insulating layer 100 is horizontally arranged.

[0050] Specifically, refer to Figure 1 In the x direction shown, in addition to setting the thickness of the insulating layer 100 to gradually decrease, the thickness of the first conductive layer 200 can also be set to gradually increase. In this case, the side of the first conductive layer 200 away from the insulating layer 100 can be set horizontally, which is beneficial to improving the flatness of the entire composite current collector. At the same time, by setting the thickness of the insulating layer 100 and the first conductive layer 200 to change, the size or weight ratio of the insulating layer 100 and the first conductive layer 200 can be adjusted to optimize the lightweight design of the composite current collector.

[0051] For example, the cross-sectional shape of the first conductive layer 200 may be as follows: Figure 1 Trapezoid shape shown.

[0052] In some embodiments, the thickness of the second conductive layer 300 gradually increases from one end of the insulating layer 100 to the other end of the insulating layer 100 , and a surface of the second conductive layer 300 away from the insulating layer 100 is horizontally disposed.

[0053] Specifically, refer to Figure 1 In the x direction shown, in addition to setting the thickness of the insulating layer 100 to gradually decrease, the thickness of the second conductive layer 300 can also be set to gradually increase. In this case, the side of the second conductive layer 300 away from the insulating layer 100 can be set horizontally, which is beneficial to improving the flatness of the entire composite current collector. At the same time, by setting the thickness of the insulating layer 100 and the second conductive layer 300 to change, the size or weight ratio of the insulating layer 100 and the second conductive layer 300 can be adjusted to optimize the lightweight design of the composite current collector.

[0054] For example, the cross-sectional shape of the second conductive layer 300 may be as follows: Figure 1 Trapezoid shape shown.

[0055] In addition, when the thickness of the first conductive layer 200 and the second conductive layer 300 gradually increases from one end of the insulating layer 100 to the other end of the insulating layer 100, the first conductive layer 200 and the second conductive layer 300 meet at the other end of the insulating layer 100 to form a larger tab 400, that is, the tab 400 is Figure 1 The thickness dimension in the y direction shown is relatively large, which can not only effectively improve the current carrying capacity of the tab 400 to improve the performance of the battery cell and help achieve high-rate charge and discharge of the battery, but also further optimize the lightweight design of the composite current collector.

[0056] For example, the cross-sectional shape of the tab 400 may be a rectangle, so that the appearance of the entire composite current collector is more regular and it is also convenient to splice and connect different composite current collectors.

[0057] Reference Figure 2 and Figure 3 As shown, in some embodiments, the composite current collector structure also includes a first primer layer 500 and a second primer layer 600, the first primer layer 500 is arranged on a side of the first conductive layer 200 away from the insulating layer 100, and the second primer layer 600 is arranged on a side of the second conductive layer 300 away from the insulating layer 100.

[0058] In a specific implementation, a first primer layer 500 is arranged on a side of the first conductive layer 200 away from the insulating layer 100 and a second primer layer 600 is arranged on a side of the second conductive layer 300 away from the insulating layer 100. The first primer layer 500 and the second primer layer 600 are carbon and binder mixtures coated on the corresponding first conductive layer 200 and the second conductive layer 300 by coating, and have a high surface roughness, which can improve the peeling strength between the composite current collector and the active material of the battery cell, and improve the contact resistance between the composite current collector and the active material, thereby effectively reducing the internal resistance of the battery having the composite current collector, so as to improve the compaction density and energy density of the battery.

[0059] Reference Figure 2 and Figure 3 As shown, in some embodiments, in a direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the thickness of at least one of the first conductive layer 200 and the first primer layer 500 gradually increases and a side of the first primer layer 500 away from the first conductive layer 200 is horizontally arranged.

[0060] For example, only the thickness of the first conductive layer 200 can be set to gradually increase in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100 while the thickness of the first primer layer 500 remains unchanged. In this case, the entire first primer layer 500 can also be horizontally set on one side away from the first conductive layer 200 to ensure the flatness of the composite current collector.

[0061] Of course, only the thickness of the first primer layer 500 may gradually increase in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100 while the thickness of the first conductive layer 200 remains unchanged. In this case, the side of the entire first primer layer 500 away from the first conductive layer 200 may be horizontally arranged to ensure the flatness of the composite current collector.

[0062] Or, refer to Figure 2 and Figure 3As shown, in this embodiment, the first conductive layer 200 and the first primer layer 500 can be simultaneously arranged to gradually increase in thickness in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100. This can be beneficial for adjusting the proportion of the first conductive layer 200 and the insulating layer 100 to achieve a lightweight design, and can also be beneficial for the first conductive layer 200 to intersect with the second conductive layer 300 at the other end of the insulating layer 100 to form a larger-sized pole ear 400 to improve the current carrying capacity.

[0063] Reference Figure 2 and Figure 3 As shown, in some embodiments, in a direction from one end of the insulating layer 100 to the other end of the insulating layer 100 , the thickness of at least one of the second conductive layer 300 and the second primer layer 600 gradually increases.

[0064] For example, only the thickness of the second conductive layer 300 can be set to gradually increase in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100 while the thickness of the second primer layer 600 remains unchanged. In this case, the entire second primer layer 600 can also be horizontally arranged on one side away from the second conductive layer 300 to ensure the flatness of the composite current collector.

[0065] Of course, only the thickness of the second primer layer 600 may gradually increase in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100 while the thickness of the second conductive layer 300 remains unchanged. In this case, the side of the entire second primer layer 600 away from the second conductive layer 300 may be horizontally set to ensure the flatness of the composite current collector.

[0066] Or, refer to Figure 2 and Figure 3 As shown, in this embodiment, the second conductive layer 300 and the second primer layer 600 can be simultaneously arranged to gradually increase in thickness in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100. This can be beneficial for adjusting the proportion of the second conductive layer 300 and the insulating layer 100 to achieve a lightweight design, and can also be beneficial for the second conductive layer 300 to intersect with the first conductive layer 200 at the other end of the insulating layer 100 to form a larger-sized pole ear 400 to improve the current carrying capacity.

[0067] For example, refer to Figure 2 and Figure 3 As shown, in order to balance the flatness design requirements of the composite current collector, the lightweight design requirements, and the design requirements of the current carrying capacity of the tab 400, the thickness of the first conductive layer 200 and the first primer layer 500 can be gradually increased in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, and the thickness of the second conductive layer 300 and the second primer layer 600 can be gradually increased in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100.

[0068] Reference Figure 3 As shown, in some embodiments, a plurality of rough structures 700 are provided on a side of the first conductive layer 200 close to the first primer layer 500 and / or a side of the second conductive layer 300 close to the second primer layer 600, and the plurality of rough structures 700 are spaced apart in a direction from one end of the insulating layer 100 to the other end of the insulating layer 100.

[0069] By providing the roughness structure 700, the adhesion between one of the first conductive layer 200 and the second conductive layer 300 provided with the roughness structure 700 and the corresponding first primer layer 500 or second primer layer 600 can be increased to improve structural stability.

[0070] For example, the roughness structure 700 may be provided only on one side of the first conductive layer 200 close to the first primer layer 500, or the roughness structure may be provided only on one side of the second conductive layer 300 close to the second primer layer 600, or Figure 3 As shown, the roughness structure 700 can be provided on both the side of the first conductive layer 200 close to the first primer layer 500 and the side of the second conductive layer 300 close to the second primer layer 600 to further improve the bonding reliability of the entire structure.

[0071] Reference Figure 3 As shown, in some embodiments, the roughness structure 700 includes a groove 710 that is recessed in a direction close to the insulating layer 100 .

[0072] When the rough structure 700 is set as a groove 710, the rough structure 700 can not only increase the adhesion between the two, but also reduce the weight of the first conductive layer 200 or the second conductive layer 300 provided with the groove 710, so as to realize the lightweight design of the composite current collector and improve the energy density of the battery cell.

[0073] Alternatively, in other implementations, the rough structure 700 may be, for example, tiny protrusions or rough lines.

[0074] Reference Figure 3 As shown, in some embodiments, a dimension h1 of the groove 710 in a direction from one end of the insulating layer 100 to the other end of the insulating layer 100 satisfies: 0.8 μm≤h1≤1.2 μm.

[0075] Exemplarily, by reasonably setting the dimension h1 of the groove 710 in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the setting of the groove 710 can reduce the weight of the corresponding first conductive layer 200 and the second conductive layer 300, and will not affect the adhesion between the first conductive layer 200, the second conductive layer 300 and the corresponding first primer layer 500 and the second primer layer 600.

[0076] In some embodiments, a dimension h2 of the groove 710 along the thickness direction of the insulating layer 100 satisfies: 0.3 μm≤h2≤0.7 μm.

[0077] Exemplarily, by reasonably setting the dimension h2 of the groove 710 along the thickness direction of the insulating layer 100, the setting of the groove 710 can reduce the weight of the corresponding first conductive layer 200 and the second conductive layer 300, and will not affect the adhesion between the first conductive layer 200, the second conductive layer 300 and the corresponding first primer layer 500 and the second primer layer 600.

[0078] In some embodiments, reference Figure 3 As shown, the thickness h3 of the insulating layer 100 satisfies: 0 μm≤h3≤50 μm.

[0079] Illustratively, in the direction from one end of the insulating layer 100 to the other end of the insulating layer 100, the thickness h3 of one end of the insulating layer 100 can be any value less than or equal to 50 μm and greater than 0 μm, and the thickness of the other end of the insulating layer 100 can be reduced to zero or other values.

[0080] By properly setting the thickness h3 of the insulating layer 100 , the cost and weight of the entire composite current collector can be effectively reduced, and the insulating layer 100 can fully play the role of isolating the first conductive layer 200 and the second conductive layer 300 .

[0081] In some embodiments, the thickness h4 of the first conductive layer 200 satisfies: 0.5 μm≤h4≤25 μm.

[0082] By properly setting the thickness h4 of the first conductive layer 200, the first conductive layer 200 itself can have a certain structural strength, and the weight of the composite current collector can also be controlled within a suitable range, thereby ultimately ensuring that the battery has sufficient energy density.

[0083] In some embodiments, the thickness h5 of the second conductive layer 300 satisfies: 0.5 μm≤h5≤25 μm.

[0084] By reasonably setting the thickness h5 of the second conductive layer 300, the second conductive layer 300 itself can have a certain structural strength, and the weight of the composite current collector can also be controlled within a suitable range, so as to ultimately ensure that the battery has sufficient energy density.

[0085] For example, the thicknesses of the first conductive layer 200 and the second conductive layer 300 may be consistent or inconsistent.

[0086] In some embodiments, reference Figure 3 As shown, the thickness h6 of the tab 400 satisfies: 1 μm≤h6≤50 μm.

[0087] By reasonably setting the thickness h6 of the tab 400, it is possible to ensure that the weight of the composite current collector is small and that the tab 400 has sufficient current flow capacity to prevent excessive temperature rise from affecting the performance of the battery cell.

[0088] In some embodiments, reference Figure 3 As shown, the thickness h7 of the first primer layer 500 satisfies: 0 μm<h7≤5 μm.

[0089] By reasonably setting the thickness h7 of the first base coating layer 500, the weight of the composite current collector can be effectively ensured to be small, the peeling strength between the composite current collector and the active material of the battery cell can be improved, and the contact resistance between the composite current collector and the active material can be improved, thereby effectively reducing the internal resistance of the battery having the composite current collector to improve the compaction density and energy density of the battery.

[0090] In some embodiments, reference Figure 3 As shown, the thickness h8 of the second primer layer 600 satisfies: 0 μm<h8≤5 μm.

[0091] By reasonably setting the thickness h8 of the second base coating layer 600, the weight of the composite current collector can be effectively ensured to be small, the peeling strength between the composite current collector and the active material of the battery cell can be improved, and the contact resistance between the composite current collector and the active material can be improved, thereby effectively reducing the internal resistance of the battery having the composite current collector to improve the compaction density and energy density of the battery.

[0092] Reference Figures 1 to 3 As shown, in some embodiments, the first conductive layer 200 and the second conductive layer 300 are symmetrically arranged relative to the central axis of the insulating layer 100, and the first primer layer 500 and the second primer layer 600 are symmetrically arranged relative to the central axis of the insulating layer 100 to form a regular composite current collector.

[0093] Reference Figures 1 to 3 As shown, this embodiment also provides a pole piece, including the above-mentioned composite current collector.

[0094] The specific structure and implementation principle of the composite current collector in this embodiment are the same as those of the composite current collector provided in the above embodiment, and can bring the same or similar technical effects, which will not be described one by one here, and the details can be referred to the description of the above embodiment.

[0095] Reference Figures 1 to 3 As shown, this embodiment further provides a battery cell, including a positive electrode sheet and a negative electrode sheet. In a specific implementation, a separator is provided between the positive electrode sheet and the negative electrode sheet.

[0096] The specific structure and implementation principle of at least one of the positive electrode plate and the negative electrode plate are the same as the structure of the electrode plate provided in the above embodiment, and can bring the same or similar technical effects, which will not be described one by one here, and the details can be referred to the description of the above embodiment.

[0097] Reference Figures 1 to 3 As shown, this embodiment also provides a battery, including the battery cell as described above.

[0098] The specific structure and implementation principle of the battery cell in this embodiment are the same as the structure of the battery cell provided in the above embodiment, and can bring the same or similar technical effects, which will not be described one by one here, and the details can be referred to the description of the above embodiment.

[0099] Reference Figures 1 to 3 As shown, this embodiment also provides a vehicle, comprising the battery as described above.

[0100] The specific structure and implementation principle of the battery in this embodiment are the same as the structure of the battery provided in the above embodiment, and can bring the same or similar technical effects, which will not be described one by one here, and the details can be referred to the description of the above embodiment.

[0101] The embodiments of the present invention are further described below in conjunction with experimental results.

[0102] The preparation method of the positive electrode sheet and the negative electrode sheet of the battery cell is briefly described as follows:

[0103] 1. Preparation of positive electrode sheet: LFP (Lithium Iron Phosphate, lithium iron phosphate, lithium iron phosphorus), conductive carbon black and polyvinylidene fluoride are mixed in a mass ratio of 96.5:1.5:2, and the LFP mixed slurry is evenly coated on the composite current collector. After drying, the electrode ears are cut 400, and the strips and cuts are obtained to obtain the positive electrode sheet.

[0104] 2. Preparation of negative electrode sheet: Negative electrode graphite formula: active material (graphite): conductive carbon black: styrene-butadiene rubber: sodium hydroxycellulose (CMC) = mixed according to the mass ratio of 96:1:1.8:1.2; the mixed slurry is evenly coated on the 6um Cu current collector, and after drying, the tabs are cut 400, striped and cut to obtain the negative electrode sheet.

[0105] 3. Preparation of battery cells: Place a separator between the positive electrode and the negative electrode, and make a battery cell by winding.

[0106] The pole tab 400 is welded by ultrasonic or transfer welding to obtain a dry cell, which is then filled with liquid, packaged, and formed into a cell. After the cell is completed, the capacity test can be carried out: at room temperature (25±3℃), a test current of 0.33C is used, and a simulated constant current and constant voltage charge and discharge test is carried out in the voltage range of 2.0V-3.65V, with a cut-off current of 0.05C, to obtain the capacity data.

[0107] Specifically, the experimental comparison groups include comparative example, example one, example two and example three.

[0108] The current collector of the positive electrode sheet in the battery cell of the comparative example is made of 10 μm aluminum foil, and the current collector of the positive electrode sheet in the battery cell of Example 1 is made of Figure 1 The composite current collector shown in the embodiment 2 is used as the current collector of the positive electrode sheet of the battery cell Figure 2 The composite current collector shown in the figure, the current collector of the positive electrode sheet in the battery cell of Example 3 is Figure 3 The current collectors of the negative electrode sheets of the cells in the comparative example, example 1, example 2 and example 3 all use 6 μm copper foil.

[0109] Table 1

[0110]

[0111] Referring to Table 1, we can see that:

[0112] 1) The battery cell of the comparative example cannot pass the needle puncture test, while the composite current collectors of Examples 1, 2 and 3 can all pass the needle puncture test.

[0113] 2) According to the comparison of the performance of the battery cells of Example 1, Example 2 and Example 3, it can be seen that when the first primer layer 500 and the second primer layer 600 are disposed on the composite current collector, the performance of the battery cell is significantly improved.

[0114] 3) According to the comparison between Example 2 and Example 3, after the roughness structure 700 is further provided on the first conductive layer 200 and the second conductive layer 300, the performance of the battery cell is further improved.

[0115] Specifically, the thickness of the tab 400 of the composite current collector used in the battery cells of Example 1, Example 2 and Example 3 along the y direction is 8 μm.

[0116] For example, for Example 1, the thickness of one end of the insulating layer 100 may be 6 μm, the thickness of the first conductive layer 200 and the second conductive layer 300 at the position corresponding to one end of the insulating layer 100 is 1 μm respectively, and the thickness of the tab 400 is 8 μm. For Example 2 and Example 3, the thickness of one end of the insulating layer 100 is 6 μm, the thickness of the first conductive layer 200 and the second conductive layer 300 at the position corresponding to one end of the insulating layer 100 is 1 μm respectively, the thickness of the first primer layer 500 and the second primer layer 600 at the position corresponding to one end of the insulating layer 100 is 0 μm, and the thickness of the tab 400 is 8 μm.

[0117] The above example only compares the performance of the battery cell in a scenario where the thickness of the tab 400 is 8 μm and the composite current collector is used to make the positive electrode sheet. Of course, the composite current collector of this embodiment can also be used to make the negative electrode sheet, and the thickness of the tab 400 can also be selected to other sizes.

[0118] In this article, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In addition, the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0119] In this article, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0120] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite current collector, characterized in that: It comprises an insulating layer (100), a first conductive layer (200) and a second conductive layer (300); In a thickness direction of the insulating layer (100), the first conductive layer (200) and the second conductive layer (300) are arranged on opposite sides of the insulating layer (100); In a direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the thickness of the insulating layer (100) gradually decreases, and in a direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the first conductive layer (200) and the second conductive layer (300) extend in a direction close to each other and meet at the other end of the insulating layer (100) to form a pole ear (400).

2. The composite current collector according to claim 1, characterized in that: In a direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the thickness of the first conductive layer (200) gradually increases, and a surface of the first conductive layer (200) away from the insulating layer (100) is arranged horizontally; And / or, in a direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the thickness of the second conductive layer (300) gradually increases, and a side of the second conductive layer (300) away from the insulating layer (100) is horizontally arranged.

3. The composite current collector according to claim 1, characterized in that: The composite current collector structure also includes a first primer layer (500) and a second primer layer (600), wherein the first primer layer (500) is disposed on a side of the first conductive layer (200) away from the insulating layer (100), and the second primer layer (600) is disposed on a side of the second conductive layer (300) away from the insulating layer (100).

4. The composite current collector according to claim 3, characterized in that: In a direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the thickness of at least one of the first conductive layer (200) and the first primer layer (500) gradually increases, and a surface of the first primer layer (500) away from the first conductive layer (200) is arranged horizontally; And / or, in the direction from one end of the insulating layer (100) to the other end of the insulating layer (100), the thickness of at least one of the second conductive layer (300) and the second primer layer (600) gradually increases, and the side of the second primer layer (600) away from the second conductive layer (300) is horizontally arranged.

5. The composite current collector according to claim 3 or 4, characterized in that: A plurality of rough structures (700) are provided on one side of the first conductive layer (200) close to the first primer layer (500) and / or a side of the second conductive layer (300) close to the second primer layer (600), and the plurality of rough structures (700) are arranged at intervals in a direction from one end of the insulating layer (100) to the other end of the insulating layer (100).

6. The composite current collector according to claim 5, characterized in that: The rough structure (700) includes a groove (710) formed by being recessed in a direction approaching the insulating layer (100).

7. The composite current collector according to claim 6, characterized in that: A dimension h1 of the groove (710) in a direction from one end of the insulating layer (100) to the other end of the insulating layer (100) satisfies: 0.8 μm≤h1≤1.2 μm; And / or, a dimension h2 of the groove (710) along the thickness direction of the insulating layer (100) satisfies: 0.3 μm≤h2≤0.7 μm.

8. The composite current collector according to claim 3, characterized in that: The thickness h3 of the insulating layer (100) satisfies: 0 μm≤h3≤50 μm; And / or, the thickness h4 of the first conductive layer (200) satisfies: 0.5 μm≤h4≤25 μm; And / or, the thickness h5 of the second conductive layer (300) satisfies: 0.5 μm≤h5≤25 μm; And / or, the thickness h6 of the tab (400) satisfies: 1 μm≤h6≤50 μm; and / or, the thickness h7 of the first primer layer (500) satisfies: 0 μm<h7≤5 μm; And / or, the thickness h8 of the second primer layer (600) satisfies: 0 μm<h8≤5 μm.

9. The composite current collector according to claim 3, characterized in that: The first conductive layer (200) and the second conductive layer (300) are symmetrically arranged relative to the central axis of the insulating layer (100); And / or, the first primer layer (500) and the second primer layer (600) are symmetrically arranged relative to the central axis of the insulating layer (100).

10. A pole piece, characterized in that: Comprising the composite current collector according to any one of claims 1 to 9.

11. A battery cell, characterized in that: Comprising the pole piece as claimed in claim 10.

12. A battery, characterized in that: Comprising the battery cell as claimed in claim 11.

13. A vehicle, characterized in that: Comprising the battery of claim 12.

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