Current collector, method for manufacturing the same, electrode sheet, and battery

Abstract

The application relates to the field of batteries, in particular to a current collector, a preparation method thereof, a pole piece and a battery. The current collector comprises: a middle layer, the middle layer comprising an insulating layer; a first conductive layer, the first conductive layer being arranged at both ends of the middle layer or at recessed areas close to both ends of the middle layer and recessed from the surfaces of the middle layer inwardly; and two second conductive layers, the two second conductive layers being respectively arranged on the surfaces on both sides of the middle layer and the first conductive layer. The current collector can improve safety and the current passing capacity of the tab area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a current collector, a preparation method thereof, a pole piece and a battery. BACKGROUND

[0002] With the development of batteries towards high energy density and high safety, battery systems and various battery auxiliary materials are developing towards lightweight, and composite current collectors are gradually applied to power batteries.

[0003] The plating layer of the foil in the existing composite current collector is thin and the welding flow capacity is insufficient, which often causes a large resistance and energy consumption during charging and discharging in the battery. SUMMARY

[0004] In view of the above problems of the prior art, the purpose of the present application is to provide a current collector, a preparation method thereof, a pole piece and a battery, which can improve safety and also improve the current carrying capacity of the tab area.

[0005] To solve the above problems, the first aspect of the present application provides a current collector, which comprises:

[0006] an intermediate layer, the intermediate layer comprising an insulating layer;

[0007] a first conductive layer, the first conductive layer being arranged at both ends of the intermediate layer or at the recessed area near both ends of the intermediate layer;

[0008] two second conductive layers, the two second conductive layers being respectively arranged on the surfaces on both sides of the intermediate layer and the first conductive layer.

[0009] Further, the intermediate layer further comprises a foil layer arranged on both sides of the insulating layer.

[0010] Further, the insulating layer comprises a first insulating layer and a second insulating layer arranged on both sides of the first insulating layer.

[0011] Further, the second insulating layer has a solid structure or a porous structure.

[0012] Further, the thickness of the intermediate layer is 3-20um.

[0013] Further, the first conductive layer is arranged at the recessed area near both ends of the intermediate layer, and the depth of the recessed area is less than the thickness of the intermediate layer.

[0014] Further, the first conductive layer comprises two, and the two first conductive layers are respectively arranged at the recessed area near both ends on both sides of the intermediate layer.

[0015] Furthermore, the structure of the second conductive layer is a solid structure or a porous structure.

[0016] A second aspect of the present invention provides a method for preparing a current collector, the method comprising:

[0017] Step S1: Provide an intermediate layer;

[0018] Step S2: The first conductive layer is disposed at both ends of the intermediate layer, or in a recessed area near both ends of the intermediate layer that is recessed inward from its surface.

[0019] Step S3: Cover the surfaces of the intermediate layer and both sides of the first conductive layer with two second conductive layers respectively.

[0020] Further, step S2 includes:

[0021] Step S211: The recessed region is formed near both ends of the intermediate layer, and the depth of the recessed region is less than the thickness of the intermediate layer;

[0022] Step S212: Fill the recessed area with the first conductive layer.

[0023] Further, step S2 includes:

[0024] Step S221: The first conductive layer is disposed in a local area of ​​the surface of the intermediate layer near both ends;

[0025] Step S222: The first conductive layer is squeezed or penetrated into the intermediate layer by applying external force. The method of applying external force includes one or more of the following: hot pressing, heating, squeezing, and tapping.

[0026] A third aspect of the present invention provides an electrode sheet, the electrode sheet comprising:

[0027] The current collector is any of the current collectors described above;

[0028] The active material is disposed on both sides of the current collector.

[0029] A fourth aspect of the present invention provides an electrode sheet, wherein the battery comprises:

[0030] The electrode is the electrode described above.

[0031] Due to the above technical solution, the present invention has the following beneficial effects:

[0032] According to an embodiment of the present invention, the current collector includes an intermediate layer, a first conductive layer, and a second conductive layer. That is, in addition to the conventional second conductive layer disposed on the outermost surface to collect the current generated by the active material, the thickness of the conductive layer is increased by superimposing the first conductive layer and the second conductive layer at both ends of the intermediate layer or near the two ends of the intermediate layer (corresponding to the tab area). This increases the proportion of metal in the tab area, reduces resistance, reduces energy consumption during charging and discharging, and improves the current carrying capacity of the tab area. The intermediate layer avoids short circuits in the battery using this current collector and the resulting thermal runaway and battery spontaneous combustion, thereby improving safety and the current carrying capacity of the tab area. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the present invention, the accompanying drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the intermediate layer according to an embodiment of the present invention;

[0035] Figure 2 Based on Figure 1 A schematic diagram of the current collector obtained from the intermediate layer is shown.

[0036] Figure 3 Is Figure 2 A schematic diagram of the electrode structure obtained based on this;

[0037] Figure 4 This is a structural diagram of the intermediate layer according to another embodiment of the present invention;

[0038] Figure 5 Is Figure 4 The structural diagram obtained by adding a first conductive layer on the basis;

[0039] Figure 6 Is Figure 5 A schematic diagram of the current collector structure obtained based on the above.

[0040] Figure 7 Is Figure 6 A schematic diagram of the electrode structure obtained based on this;

[0041] Figure 8 This is a structural diagram of the intermediate layer according to another embodiment of the present invention;

[0042] Figure 9 Is Figure 8 A structural diagram with a first conductive layer added to the basic structure;

[0043] Figure 10 Is Figure 9 A schematic diagram of the current collector structure obtained based on the above.

[0044] Figure 11 Is Figure 10 A schematic diagram of the electrode structure obtained based on this;

[0045] Figure 12 These are corresponding structural schematic diagrams for comparison, where (a) is a structural schematic diagram of the intermediate layer; (b) is a structural schematic diagram of the current collector; and (c) is a structural schematic diagram of the electrode.

[0046] Figure 13 This is a flowchart of the current collector preparation method according to an embodiment of the present invention.

[0047] 100, Intermediate layer; 110, Insulating layer; 120, Foil layer; 200, First conductive layer; 300, Second conductive layer; 400, Active material. Detailed Implementation

[0048] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0050] The current collector of an embodiment of the present invention will be described below.

[0051] like Figures 1 to 11 As shown, the current collector in this embodiment of the invention includes: an intermediate layer 100, a first conductive layer 200, and a second conductive layer 300.

[0052] First, let's describe the intermediate layer 100. The intermediate layer 100 includes the insulating layer 110.

[0053] like Figure 1 and Figure 8As shown, the intermediate layer 100 in this embodiment is an insulator.

[0054] like Figure 4 As shown, the intermediate layer 100 in this embodiment is a composite layer, that is, foil layers are also provided on both sides of the intermediate insulating layer 110.

[0055] The middle insulating layer 110 can effectively prevent short circuits in this current collector battery and the resulting thermal runaway and battery spontaneous combustion.

[0056] Furthermore, as an example, the insulating layer may include a first insulating layer located in the middle and second insulating layers located on both sides of the first insulating layer. For example, the material of the second insulating layer may be selected to have a melting point lower than that of the first insulating layer material. The low melting point of the second insulating layer can cut off the electron path at a relatively low temperature, preventing thermal runaway and increasing safety. The first insulating layer with a high melting point sandwiched between the two second insulating layers can result in higher processing performance and throughput for the current collector, as well as the electrodes and batteries using this current collector. Thus, it is possible to achieve high processing performance and throughput while simultaneously better preventing thermal runaway, thereby increasing safety.

[0057] Furthermore, the elongation at break of the second insulating layer can be set to be lower than that of the first insulating layer. The lower elongation at break of the second insulating layer, in addition to its easier melting properties, also increases its susceptibility to mechanical fracture, further reducing the electronic conduction transition time and improving the efficiency of switching on and off. Moreover, it is more prone to failure during short circuits caused by mechanical forces (external compression or puncture), quickly severing the connection between the first insulating layer and the conductive layer. This results in enhanced safety for the electrodes and batteries using this current collector. Simultaneously, the high elongation at break of the first insulating layer ensures high processing performance and throughput for the current collector, as well as the electrodes and batteries using it.

[0058] The first insulating layer material and the second insulating layer material may be selected from, for example, polyethylene terephthalate, polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyimide or polyamide, and simultaneously satisfy the condition that the melting point of the second insulating layer material is lower than that of the first insulating layer.

[0059] Once the first insulating layer material has been selected, you can choose from the materials mentioned above based on the melting point and elongation.

[0060] Furthermore, the thickness of the second insulating layer can be set to be less than that of the first insulating layer. A thinner second insulating layer is easier to melt and break, which can increase the safety of the electrode and battery using this current collector. A thicker first insulating layer can increase the processing performance and throughput of the current collector, as well as the electrode and battery using this current collector.

[0061] Furthermore, the second insulating layer has a solid structure or a porous structure.

[0062] The hollow structure of the second insulating layer makes it easier for the first conductive layer 200 to enter its interior, thus facilitating its implementation. Figure 6 The current collector in this embodiment increases the ease of manufacturing.

[0063] Furthermore, the thickness of the intermediate layer 100 is 3-20 μm.

[0064] The 3-20µm intermediate layer can effectively prevent thermal runaway in batteries using this current collector, and also facilitates the setting of the first conductive layer 200.

[0065] Next, the first conductive layer 200 will be described. The first conductive layer 200 is disposed at both ends of the intermediate layer 100, or in recessed areas of the intermediate layer 100 near both ends, recessed inward from its surface.

[0066] like Figure 2 and Figure 6 As shown, in the first embodiment and the second embodiment, the first conductive layer 200 in the current collector is disposed in a recessed region of the intermediate layer 100 near both ends, recessed inward from its surface.

[0067] like Figure 10 As shown, in the third embodiment, the current collector first conductive layer 200 is disposed at both ends of the intermediate layer 100.

[0068] The two ends or near the two ends of the intermediate layer 100 can correspond to the subsequent connection tab area, which improves the current carrying capacity of the tab area, while avoiding the situation of directly increasing the thickness of the tab, which would cause difficulties in winding and unwinding and damage to the surface layer of the current collector.

[0069] According to some embodiments of the present invention, a first conductive layer 200 is disposed in a recessed region near both ends of an intermediate layer 100, the depth of which is less than the thickness of the intermediate layer 100.

[0070] like Figure 1 As shown, the intermediate layer 100 forms a recessed area, which facilitates the first conductive layer 200 filling the recessed area. The depth of the recessed area is less than the thickness of the intermediate layer 100, which avoids the situation where the recessed area penetrates the intermediate layer 100, thus increasing the manufacturing difficulty of the first conductive layer 200.

[0071] Furthermore, the first conductive layer 200 may include two layers, and the two first conductive layers 200 are respectively disposed in the recessed areas near both ends on both sides of the intermediate layer 100.

[0072] like Figure 3 and Figure 7 As shown, a first conductive layer 200 is disposed on both sides of the intermediate layer 100 near the first end, and a second conductive layer 200 is disposed on both sides of the intermediate layer 100 near the second end. This reduces the resistance of the current collector and further improves the current-carrying capacity of the tab region.

[0073] Finally, the two second conductive layers 300 are described. The two second conductive layers 300 respectively cover the surfaces of the intermediate layer 100 and the first conductive layer 200 on both sides.

[0074] like Figure 3 , Figure 6 and Figure 10 As shown, two second conductive layers 300 are covered on both sides of the first conductive layer 200.

[0075] The second conductive layer 300 collects the current generated by the battery active material 400 to form a larger current output.

[0076] According to some embodiments of the present invention, the structure of the second conductive layer 300 can be a solid structure or a porous structure.

[0077] In other words, the second conductive layer 300, whether solid or hollow, can be used in this application, increasing the versatility of the invention.

[0078] The current collector, through the second conductive layer 300, collects the current generated by the active material 400. At both ends of the intermediate layer 100 or near the ends of the intermediate layer 100 (corresponding to the tab area), the superposition of the first conductive layer 200 and the second conductive layer 300 increases the thickness of the conductive layer, increases the metal content of the tab area, reduces resistance, reduces energy consumption during charging and discharging, and improves the current carrying capacity of the tab area. The intermediate layer 100 avoids short circuits in the battery using this current collector and the resulting thermal runaway and battery spontaneous combustion. Therefore, it improves both safety and the current carrying capacity of the tab area.

[0079] The method for preparing the current collector according to an embodiment of the present invention will be described below.

[0080] like Figure 13 As shown, the method for preparing the current collector according to an embodiment of the present invention includes:

[0081] Step S1, provide intermediate layer 100.

[0082] like Figure 1 , Figure 4 and Figure 8 The intermediate layer 100 in the embodiment.

[0083] Step S2: The first conductive layer 200 is disposed at both ends of the intermediate layer 100, or in a recessed area near both ends of the intermediate layer 100 that is recessed inward from its surface.

[0084] like Figure 9 As shown, the first conductive layer 200 is disposed at both ends of the intermediate layer 100.

[0085] like Figure 2 and Figure 6 As shown, the first conductive layer 200 is disposed in a recessed region of the intermediate layer 100 near both ends, recessed inward from its surface.

[0086] Step S3: Two second conductive layers 300 are respectively covered on the surfaces of the intermediate layer 100 and the two sides of the first conductive layer 200.

[0087] like Figure 3 , Figure 6 and Figure 10 As shown, two second conductive layers 300 are covered on both sides of the first conductive layer 200.

[0088] The above method can effectively produce current collectors that meet safety requirements while also improving the current carrying capacity of the tab region.

[0089] Further, step S2 includes: step S211, forming a recessed region near both ends of the intermediate layer 100, the depth of the recessed region being less than the thickness of the intermediate layer 100; step S212, filling the recessed region with the first conductive layer 200.

[0090] like Figure 2 As shown, a recessed region is formed near both ends of the intermediate layer 100, and the first conductive layer 200 fills the recessed region.

[0091] This method involves fewer steps and is simpler to produce, making it easier to manufacture current collectors.

[0092] Further, step S2 includes: setting a first conductive layer 200 in a local area of ​​the surface near both ends of the intermediate layer 100; step S222, squeezing or penetrating the first conductive layer 200 into the intermediate layer 100 by applying external force, the external force including one or more of hot pressing, heating, squeezing and tapping.

[0093] like Figure 5As shown, a first conductive layer 200 is provided in a local area of ​​the surface near both ends of the intermediate layer 100. The first conductive layer 200 can be provided on the intermediate layer 100 by means of vapor deposition, printing, imprinting, etc.

[0094] like Figure 6 As shown, the first conductive layer 200 is squeezed or penetrated into the middle by applying external force. The method of applying external force includes one or more of the following: hot pressing, heating, extrusion, and impact.

[0095] Therefore, this application can be implemented on the general intermediate layer 100.

[0096] The electrode sheet of the present invention will now be described.

[0097] The electrode in this embodiment of the invention includes a current collector and an active material 400. The current collector is any of the current collectors described above. The active material 400 is disposed on both sides of the current collector.

[0098] By using the aforementioned current collector on the electrode, the safety of the electrode can be improved, and the current carrying capacity of the tab area can also be increased.

[0099] The battery of an embodiment of the present invention will be described below.

[0100] The battery of this invention includes electrode sheets, which utilize the aforementioned current collector. The battery is assembled by methods such as winding or stacking.

[0101] Battery applications using electrodes with the aforementioned current collectors can improve battery safety while also increasing the current carrying capacity of the tab area.

[0102] The present invention will now be described through specific embodiments and comparative examples.

[0103] Example 1

[0104] like Figures 1 to 3 As shown, the intermediate layer 100 is an insulating layer 110 with a thickness of 6 μm, forming a recess with a depth of 1 μm. The first conductive layer 200 is an aluminum layer with a thickness of 1 μm, deposited on the intermediate layer 100 by vapor deposition. The second conductive layer 300 is an aluminum layer with a thickness of 1 μm, deposited on both sides of the intermediate layer 100 and the first conductive layer 200 by vapor deposition, thus forming a current collector. An active material 400 is then coated onto the current collector to obtain the desired result. Figure 3 The electrodes shown are used to assemble a battery.

[0105] Example 2

[0106] like Figures 4 to 7As shown, the intermediate layer 100 is a composite layer. The insulating layer 110 in the composite layer has a thickness of 4 μm, the foil layers 120 on both sides of the insulating layer 110 have a thickness of 1 μm, and the first conductive layer 200 is an aluminum layer with a thickness of 1 μm. These layers are deposited on the intermediate layer 100 by vapor deposition, forming the structure shown. Figure 5 The structure, after being fixed by hot pressing, yields the following: Figure 6 The structure is obtained by coating the current collector with active material 400, resulting in a current collector with the structure described above. Figure 7 The electrodes shown are used to assemble a battery.

[0107] Comparative Example

[0108] like Figure 12 As shown, the intermediate layer 100 is an insulating layer 110 with a thickness of 6 μm, and the second conductive layer 300 is an aluminum layer with a thickness of 1 μm, which is deposited on the intermediate layer 100 by vapor deposition, thereby obtaining the desired result. Figure 13 The current collector shown is coated with active material 400 to obtain the electrode shown in Figure 14. The battery is obtained by assembling the electrode.

[0109] The resistance values ​​of the above embodiments and comparative examples were measured, and the results are shown in Table 1.

[0110] Table 1. Battery internal resistance of the examples and comparative examples

[0111]

[0112] The results above show that the resistance of Examples 1 and 2 is lower than that of the comparative example, indicating that the present invention can reduce the energy consumption of charging and discharging and improve the current carrying capacity of the tab region.

[0113] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A current collector, characterized in that, include: The intermediate layer includes an insulating layer, which includes a first insulating layer and a second insulating layer disposed on both sides of the first insulating layer. The second insulating layer has a porous structure, and the elongation at break of the second insulating layer is lower than that of the first insulating layer. The thickness of the second insulating layer is lower than that of the first insulating layer, and the melting point of the second insulating layer is lower than that of the first insulating layer. The second insulating layer can cut off the electronic path. The first conductive layer has tab regions near both ends of the intermediate layer. The first conductive layer is disposed in a recessed region that is recessed inward from its surface near both ends of the intermediate layer. The depth of the recessed region is less than the thickness of the intermediate layer, thereby preventing the recessed region from penetrating the intermediate layer. Two second conductive layers are respectively covering the surfaces of the intermediate layer and both sides of the first conductive layer, and the structure of the second conductive layer is a porous structure.

2. The current collector according to claim 1, characterized in that, The intermediate layer also includes foil layers disposed on both sides of the insulating layer.

3. The current collector according to claim 2, characterized in that, The thickness of the intermediate layer is 3-20 μm.

4. The current collector according to claim 1, characterized in that, The first conductive layer comprises two layers, which are respectively disposed on both sides of the intermediate layer near the two ends of the recessed area.

5. A method for preparing a current collector, used to prepare the current collector according to any one of claims 1 to 4, characterized in that, include: Step S1: Provide an intermediate layer; Step S2: The first conductive layer is disposed at both ends of the intermediate layer, or in a recessed area near both ends of the intermediate layer that is recessed inward from its surface. Step S3: Cover the surfaces of the intermediate layer and both sides of the first conductive layer with two second conductive layers respectively.

6. The method for preparing a current collector according to claim 5, characterized in that, Step S2 includes: Step S211: The recessed region is formed near both ends of the intermediate layer, and the depth of the recessed region is less than the thickness of the intermediate layer; Step S212: Fill the recessed area with the first conductive layer.

7. The method for preparing a current collector according to claim 5, characterized in that, Step S2 includes: Step S221: The first conductive layer is disposed in a local area of ​​the surface of the intermediate layer near both ends; Step S222: The first conductive layer is squeezed or penetrated into the intermediate layer by applying external force. The method of applying external force includes one or more of the following: hot pressing, heating, squeezing, and tapping.

8. An electrode sheet, characterized in that, include: The current collector is the current collector according to any one of claims 1 to 4; The active material is disposed on both sides of the current collector.

9. A battery, characterized in that, include: The electrode is the electrode as described in claim 8.

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