Composite current collector, pole piece and battery

Abstract

The utility model discloses a composite current collector, a pole piece and a battery. The composite current collector comprises a macromolecule layer and metal layers deposited on the two side faces of the macromolecule layer, and the two metal layers are connected at at least one end of the macromolecule layer so that the two metal layers can be conducted. The end face of the composite current collector is provided with the metal layer, and the metal layer is connected with the metal layers on the upper and lower surfaces of the polymer layer, so that the metal layers on the upper and lower surfaces of the current collector are electronically conducted. After the battery pole piece is prepared, a metal foil tab does not need to be subjected to transfer welding, and an external tab can be directly welded.

Description

Technical Field

[0001] The utility model relates to the technical field of current collectors, in particular to a composite current collector, a pole piece and a battery. Background Art

[0002] The composite current collector has a special "sandwich structure" and is composed of a polymer layer and metal layers on both sides thereof. Among them, the polymer layer serves as a support layer, which can improve the mechanical and mechanical properties of the foil, reduce the weight of the current collector, and thus increase the energy density of the battery cell. At the same time, since the polymer layer is not conductive, the composite current collector can simultaneously improve the safety performance of the battery and help the lithium-ion battery pass the nail penetration test. The existing composite current collector structure is as Figure 1 , the middle polymer layer 101 is not conductive. When welding the battery tab, the metal layers 102 on both sides of the polymer layer 101 cannot be electrically connected, so welding cannot be completed. When welding the composite current collector, an external foil needs to be welded on each of the upper and lower surfaces of the composite foil as a tab. To solve the welding problem, currently, Y-shaped tabs are used in wound batteries. In stacked batteries, a transfer welding technique is required. The transfer welding technique requires leaving a blank foil area along the edge of the pole piece after the electrode is coated and rolled. As Figure 2 shown, an active material layer 103 is coated on the upper and lower surfaces of the current collector. At the blank foil position, a metal foil 104 is added to each of the upper and lower sides of the composite current collector. First, the upper and lower metal layers of the composite current collector are welded together with two external tab foils, which will form a 3-8 mm welding transition zone. The transition zone ensures that the external tab foils are welded to the metal layers on the upper and lower surfaces of the composite current collector; then these two tab foils are welded to an aluminum tab, a copper tab, a nickel-plated copper tab, etc. (see Appendix Figure 3 ). Taking a common (4.5+1+1) micron composite copper foil and using a 6 micron copper foil as the external tab foil as an example, the thickness of the external tab foil after transfer welding is 12 microns, which is 5.5 microns thicker than the original thickness of the composite tab foil, and the thickness increases by 85%. When the number of stacked battery layers is large, the thickness increase is more obvious. For example, when stacking 20 layers, 40 layers of external tab foils are required, which greatly increases the risks of poor welding and foil cracking; when the number of stacked battery layers is 40 layers, the number of external tab foil layers reaches 80 layers, and welding cannot be performed. In addition, in general transfer welding processes, a 3-8 mm welding transition zone for external tab foils is required. This distance can neither be coated with positive and negative active materials nor conduct the two metal layers above and below the polymer layer. At the same time, it causes problems such as the need to modify the battery assembly process and greatly increasing the battery processing difficulty.

[0003] In the existing composite current collector transfer welding technology, first of all, the production line needs to add transfer welding equipment, and the price of this equipment is more than 2 million, which increases the battery cost; at the same time, it increases the battery preparation process and prolongs the battery preparation cycle; secondly, the currently used external foil tab is relatively thick, such as 6 microns for copper foil and 10 microns for aluminum foil, etc., while the total thickness of the composite copper foil and composite aluminum foil itself is about 6.5 microns and 8 microns, and the thickness of the entire foil tab after transfer welding increases significantly; in addition, two layers of external foil tabs need to be added to each layer of composite foil, increasing the material cost; at the same time, it increases the welding difficulty, and problems such as poor foil welding and foil fracture are more serious; in addition, due to the addition of a welding transition zone, the assembly processes such as battery punching and casing need to be adjusted, which has a greater impact on the battery yield. Since the metal layer on the surface of the composite current collector is very thin, generally 1 micron on each of the two surfaces, its current-carrying capacity is poor, which limits the fast charging performance and high-rate discharge performance of the battery. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies and defects of the prior art, and provide a composite current collector, a pole piece and a battery. The end face of the composite current collector is provided with a metal layer by itself, and this metal layer connects the metal layers on the upper and lower surfaces of the polymer layer, so that the metal layers on the upper and lower surfaces of the current collector are electronically conducted. After preparing the battery pole piece, there is no need to transfer weld the metal foil tab, and the external pole piece can be directly welded.

[0005] In the first aspect of the present invention, a composite current collector is provided, which includes a polymer layer and metal layers deposited on two side surfaces of the polymer layer, and the two metal layers are connected at at least one end of the polymer layer to make the two metal layers conduct.

[0006] Wherein, at least one end of the polymer layer is connected by an end face metal layer formed when metal is deposited on the surface of the polymer layer.

[0007] Wherein, the thickness of the end face metal layer is greater than the thickness of each metal layer.

[0008] Wherein, the thickness of the polymer layer is 2-10 μm.

[0009] Wherein, the thickness of the metal layer is 0.3-2 μm.

[0010] Wherein, the metal layer is one of aluminum, copper, chromium, iron, nickel, and titanium;

[0011] When the metal layer adopts copper or iron, a chromium layer or a nickel layer is deposited on the surface of the copper or iron metal layer as a protective layer; the thickness of the chromium layer is 1-10 nm, and the thickness of the nickel layer is 1-100 nm.

[0012] The polymer layer is one or more of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyetheretherketone and polymethyl methacrylate. The second aspect of the utility model provides a pole piece, comprising the composite current collector of the first aspect of the utility model, and an active material coating on the surface of the composite current collector.

[0013] Wherein, the pole piece includes a positive pole piece, a negative pole piece or a positive and negative pole piece. The active material coating includes a positive active material coating and a negative active material coating; the composite current collector has positive active material coatings on both surfaces to form a positive pole piece; the composite current collector has negative active material coatings on both surfaces to form a negative pole piece; the composite current collector has positive active material coatings on one surface and negative active material coatings on the other surface to form positive and negative pole pieces.

[0014] The third aspect of the present invention provides a battery, including the electrode sheet of the second aspect of the present invention, which may include the positive electrode sheet, or include the negative electrode sheet, or include the positive electrode sheet and the negative electrode sheet at the same time, or include the positive and negative electrode sheets.

[0015] Among them, the batteries include lithium-ion batteries, sodium-ion batteries, lithium metal batteries, solid-state batteries, etc.

[0016] The composite current collector of the utility model has a metal layer on its end surface. Since the metal layer connects the metal layers on the upper and lower surfaces of the polymer layer, the metal layers on the upper and lower surfaces of the composite current collector are electronically conductive, and there is no need to transfer-weld the metal foil ears. The composite current collector of the utility model reduces the transfer-welding process, simplifies the structure of the external foil ears, reduces production costs, improves production efficiency, and improves the fast charging performance and high-rate discharge performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a composite current collector structure of the prior art;

[0018] Figure 2 It is a structure after preparing battery pole pieces with composite current collectors in the prior art and transferring and welding external foil pole ears;

[0019] Figure 3 It is the structure after the existing composite current collector pole piece is welded with the external pole ear;

[0020] Figure 4 This is a schematic diagram of the structure formed after the first step of preparing the composite current collector in Example 1 of the utility model;

[0021] Figure 5 This is a schematic diagram of the structure of the composite current collector after preparation in Example 1 of the utility model;

[0022] Figure 6 It is a schematic diagram of the electrode structure in Embodiment 1 of the present utility model;

[0023] Figure 7 It is a schematic diagram of the structure formed after the first step of preparing the composite current collector in Embodiment 2 of the present utility model;

[0024] Figure 8 It is a schematic diagram of the structure of the composite current collector after preparation in Embodiment 2 of the present utility model;

[0025] Figure 9 It is a schematic diagram of the electrode structure in Embodiment 2 of the present utility model;

[0026] Figure 10 It is a schematic diagram of the structure formed after the first step of preparing the composite current collector in Embodiment 3 of the present utility model;

[0027] Figure 11 It is a schematic diagram of the structure of the composite current collector after preparation in Embodiment 3 of the present utility model;

[0028] Figure 12 It is a schematic diagram of the electrode structure in Embodiment 3 of the present utility model;

[0029] Figure 13 It is a schematic diagram of the structure formed after the first step of preparing the composite current collector in Embodiment 4 of the present utility model;

[0030] Figure 14 It is a schematic diagram of the structure of the composite current collector after preparation in Embodiment 4 of the present utility model;

[0031] Figure 15 It is a schematic diagram of the electrode structure in Embodiment 4 of the present utility model. Detailed implementation manners

[0032] The present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0033] Embodiment 1

[0034] A composite current collector includes a polymer layer 101' and metal layers 102' deposited on two side surfaces of the polymer layer. The two metal layers 102' are connected at one end of the polymer layer to conduct the two metal 102' layers. Its manufacturing process is as follows:

[0035] The first step is to deposit the first layer of metal layer 102' on one surface of the polymer layer 101'. At one end face position of the polymer layer 101', by adjusting parameters such as deposition speed and time, the deposition thickness of the first end face metal layer formed by the first deposition = (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' formed by the first deposition), as Figure 4 shown.

[0036] The second step is to deposit the metal layer 102' on the other surface of the polymer layer 101' after the deposition of the metal layer 102' in the first step is completed. This time, on the other surface and the end face of the polymer layer 101', the same deposition speed, time and other parameters are used, so that the deposition thickness of the second end face metal layer formed by the second deposition is the same as the thickness of the surface metal layer 102' formed by the second deposition, as Figure 5 shown. Finally, the deposition thickness of the end face metal layer is obtained = (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' formed by the two depositions), and the surface metal layers 102' formed by the two depositions are connected by the end face metal layer.

[0037] As Figure 6 shown, a pole piece includes the composite current collector shown in Embodiment 1, and an active material coating 103' located outside the composite current collector. The active material coating includes a positive electrode active material coating or a negative electrode active material coating.

[0038] The present invention also provides a battery, which includes a pole piece as Figure 6 shown, wherein the battery includes a lithium-ion battery, a sodium-ion battery, a lithium metal battery, a solid-state battery, etc.

[0039] Embodiment 2

[0040] A composite current collector includes a polymer layer 101' and metal layers 102' deposited on two side surfaces of the polymer layer. The two metal layers 102' are connected at one end of the polymer layer to make the two metal layers 102' conduct. The manufacturing process steps are as follows:

[0041] The first step is to deposit a metal layer 102' on one surface of the polymer layer 101'. At one end face position of the polymer layer 101', by adjusting parameters such as deposition speed and time, the deposition thickness of the first end face metal layer formed in the first step < (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' completed by the first deposition) to improve the preparation efficiency, as Figure 7 shown.

[0042] Step 2: Deposit a second metal layer 102' on the other surface of the polymer layer 101'. This time, use the same deposition speed, time, and other parameters on the other surface and the end face of the polymer layer 101' so that the deposition thickness of the second end-face metal layer formed in Step 2 is the same as the thickness of the surface metal layer 102' formed in Step 2, as Figure 8 shown. Finally, the deposition thickness of the end-face metal layer is < (the thickness of the polymer layer 101' + the thicknesses of the surface metal layers 102' deposited twice), and the surface metal layers 102' formed by the two depositions are connected through the end-face metal layer.

[0043] As Figure 9 shown, a pole piece includes the composite current collector shown in Embodiment 2 and an active material layer 103' located outside the composite current collector, which includes a positive electrode active material coating or a negative electrode active material coating.

[0044] The present utility model also provides a battery, which includes a pole piece as Figure 9 shown, wherein the battery includes a lithium-ion battery, a sodium-ion battery, a lithium metal battery, a solid-state battery, etc.

[0045] Embodiment 3

[0046] A composite current collector includes a polymer layer 101' and two metal layers 102' located outside the polymer layer. Its manufacturing process is as follows:

[0047] Step 1: Deposit a metal layer 102' on one layer of the polymer layer 101'. On one end face of the polymer layer 101', by adjusting deposition speed, time, and other parameters, make the deposition thickness of the first end-face metal layer formed in Step 1 > (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' deposited for the first time), so as to increase the current-carrying capacity of the metal layer of the composite current collector, and further improve its fast charging performance and high-rate discharging performance after assembling the battery, as Figure 10 shown.

[0048] Step 2: After the deposition of the metal layer 102' in Step 1 is completed, deposit another layer of the metal layer 102' on the other surface of the polymer layer 101'; this time, when depositing the metal layer on the other surface and the end face of the polymer layer 101', use different deposition speeds, times, and other parameters, so that the deposition thickness of the second end-face metal layer formed in Step 2 > the thickness of the metal layer 102' on the lower surface, as Figure 11 shown. The first end-face metal layer and the second end-face metal layer formed in the two steps are directly connected through the deposition process. Finally, the deposition thickness of the end-face metal layer > (the thickness of the polymer layer 101' + the thicknesses of the surface metal layers 102' deposited twice).

[0049] As Figure 12As shown, a pole piece includes a composite current collector shown in Embodiment 3 and an active material coating 103' located outside the composite current collector. The active material coating 103' includes a positive electrode active material coating or a negative electrode active material coating.

[0050] The present utility model also provides a battery, which includes a pole piece as shown in Figure 12 As shown. Among them, the battery includes a lithium-ion battery, a sodium-ion battery, a lithium metal battery, a solid-state battery, etc.

[0051] Embodiment 4

[0052] A composite current collector includes a polymer layer 101', two metal layers 102' located on both sides of the polymer layer, and the two metal layers 102' are connected by an end face metal layer. Its manufacturing process is as follows:

[0053] In the first step, a metal layer 102' is deposited on one surface of the polymer layer 101'. On both end faces of the polymer layer 101', by adjusting parameters such as deposition speed and time, two first end face metal layers are formed, and the deposition thickness of the two first end face metal layers = (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' completed in the first deposition), as Figure 13 shown.

[0054] In the second step, on the other surface of the polymer layer 101', the other metal layer 102' is deposited. This time, when depositing on the other surface and end faces of the polymer layer 101', the same deposition speed, time and other parameters are used to deposit and form a second end face metal layer, which is directly connected to the first end face metal layer formed in the first step, so that the deposition thickness of the second end face metal layer is the same as the thickness of the surface metal layer 102' deposited in the second step, as Figure 14 shown. Finally, the deposition thickness of the end face metal layer is obtained = (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' deposited twice).

[0055] As Figure 15 shown, a pole piece includes a composite current collector shown in Embodiment 4, and an active material coating 103' located outside the composite current collector, including a positive electrode active material coating or a negative electrode active material coating.

[0056] The present utility model also provides a battery, which includes a pole piece as shown in Figure 15 As shown. Among them, the battery includes a lithium-ion battery, a sodium-ion battery, a lithium metal battery, a solid-state battery, etc.

[0057] It should be noted that on the composite current collector with end face metal layers at both ends, it is also possible to adjust the deposition thickness of the end face metal layer > (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' completed by two depositions), or the deposition thickness of the end face metal layer < (the thickness of the polymer layer 101' + the thickness of the surface metal layer 102' completed by two depositions) of the current collector.

[0058] In the above several embodiments, the end face of the current collector is self - equipped with an end face metal layer. Since the end face metal layer connects the metal layers 102' on the upper and lower surfaces of the polymer layer 101', the metal layer on the upper surface of this current collector is electronically conductive, and there is no need to transfer - weld the metal foil tab.

[0059] Moreover, through the above - mentioned setting of the end face metal layer, when the composite current collector of the present invention is applied, the transfer - welding process is reduced, the foil tab in the transfer - welding transition area is no longer needed, the production cost is reduced, the production efficiency is improved, and the fast - charging performance and high - rate discharge performance of the battery are improved.

[0060] For the composite current collector with a self - contained metal foil tab of the present invention, the edge position of the polymer layer is provided with an end face metal layer, and this end face metal layer conducts the metal layers on the upper and lower sides of the polymer layer. Because there is no longer a need for the transfer - welding step, the battery assembly cycle is shortened; the external foil tab is eliminated, removing the cost of the external foil tab; the structure after transfer - welding is simplified; at the same time, the battery preparation process is accelerated, shortening the production cycle of the battery.

[0061] The thickness of the self - contained end face metal layer of the present invention can be equivalent to the thickness of the composite foil of the entire "sandwich structure", so as to improve its current - carrying capacity, thereby improving the fast - charging performance and high - rate discharge performance of the battery.

[0062] The above shows and describes the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic features of the present invention, the present invention can be implemented in other specific forms.

[0063] Therefore, from any point of view, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to include all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

[0064] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A composite current collector, characterized in that: It comprises a polymer layer and metal layers deposited on two sides of the polymer layer, wherein the two metal layers are connected at at least one end of the polymer layer to make the two metal layers conductive.

2. The composite current collector according to claim 1, characterized in that: At least one end of the polymer layer is connected via an end surface metal layer formed when metal is deposited on the surface of the polymer layer.

3. The composite current collector according to claim 2, characterized in that: The thickness of the end surface metal layer is greater than the thickness of each of the metal layers.

4. The composite current collector according to claim 1, characterized in that: The thickness of the polymer layer is 2-10 μm.

5. The composite current collector according to claim 1, characterized in that: The thickness of the metal layer is 0.3-2 μm.

6. The composite current collector according to claim 1, characterized in that: The metal layer is one of aluminum, copper, chromium, iron, nickel and titanium; when the metal layer is copper or iron, a chromium layer or a nickel layer is deposited on the surface of the copper or iron metal layer as a protective layer; the thickness of the chromium layer is 1-10 nm, and the thickness of the nickel layer is 1-100 nm.

7. The composite current collector according to claim 1, characterized in that: The polymer layer is one of polyethylene terephthalate, polyethylene, polypropylene, polyimide, polyetheretherketone and polymethyl methacrylate.

8. A pole piece, characterized in that: The pole piece comprises the composite current collector according to any one of claims 1 to 7.

9. The pole piece according to claim 8, characterized in that: The pole piece includes a positive pole piece, a negative pole piece, or a positive and negative pole piece.

10. A battery, characterized in that Including the pole piece as described in claim 8 or 9.

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