Functional current collector convenient for transfer welding, preparation method thereof and battery
By thickening the tab coating area in the functional current collector and employing a specific preparation method, the problems of weak welding and battery overheating were solved, thereby improving the rate performance and energy density of the battery.
Patent Information
- Application Number
- CN202511008735.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-10-28
AI Technical Summary
The reduced metal layer thickness of existing functional current collectors leads to weak welding, affecting the rate performance and heat generation of the battery. Furthermore, direct tab welding is not possible, requiring transfer welding, which is prone to weld breakage.
By setting a serrated underlayer and a metal layer on the polymer film, the tab coating area is thickened. A functional current collector is prepared by magnetron sputtering and water plating, forming a metal layer that is thin in the middle and thick at the edges. This facilitates the transfer welding process, enhances the welding strength, and improves the current carrying capacity at the tab position.
It improves the rate performance of the battery, reduces battery heat generation, enhances welding strength, avoids weak welding, and increases the energy density of the battery.
Smart Images
Figure CN120854562A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of battery manufacturing technology, and relates to a functional current collector, and more particularly to a functional current collector that is easy to transfer and solder, its preparation method and battery. Background Technology
[0002] Currently, functional current collectors are favored by the lithium battery industry due to their high safety, high energy density, and low cost. These current collectors have a sandwich structure, with a polymer film in the middle and a metal layer on the outside. The metal layer thickness of functional current collectors used in the lithium battery industry is generally around 1μm. The reduction in metal layer thickness leads to a decrease in rate performance and an increase in heat generation under high-rate charge and discharge compared to traditional metal current collectors. Based on the structure of the battery electrodes, the narrowest point is generally at the tab, where the current density is highest, making it a key location affecting rate performance and battery heat generation.
[0003] Furthermore, due to the presence of the polymer film, the functional current collector cannot be directly welded to the tabs. It requires an external metal foil layer to be attached via an adapter weld for subsequent super-welding or laser welding of the tabs. The adapter weld also uses the traditional roll super-welding method. If the metal layer is too thin, it is easy to break the weld or the weld is not strong. Moreover, if the metal layer is too thin, it will cause a large current density at the tab position after the battery is assembled, which will increase the battery impedance and cause severe heat generation at the tab position.
[0004] Therefore, how to provide a functional current collector that is easy to transfer and weld, avoids weld breakage or weak welding, and at the same time takes into account the rate performance of the battery and reduces the heat generation of the battery has become an urgent problem to be solved by those skilled in the art. Summary of the Invention
[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a functional current collector that is easy to transfer and weld, its preparation method and battery. By thickening the tab coating area, the phenomenon of weld breakage or weak welding is avoided, while taking into account the rate performance of the battery and reducing the heat generation of the battery, which is conducive to large-scale promotion and application.
[0006] To achieve this objective, the present invention employs the following technical solution:
[0007] In a first aspect, the present invention provides a functional current collector that facilitates transfer soldering, comprising a polymer film and a conductive layer disposed on at least one side surface of the polymer film, the conductive layer comprising a substrate and a metal layer stacked thereon, wherein the substrate is located between the polymer film and the metal layer, the two sides of the substrate are serrated, and the metal layer comprises an intermediate plating region and tabs disposed on the two sides of the intermediate plating region.
[0008] The electrode tabs are shaped like a city wall and include non-plated areas and electrode tab plating areas arranged at intervals, and the thickness of the electrode tab plating area is greater than the thickness of the middle plating area.
[0009] The functional current collector provided by this invention thickens the tab plating area, which facilitates the subsequent metal foil transfer welding process, increases the welding strength, and avoids the phenomenon of weld breakage or weak welding. Moreover, after the electrode sheet is made, since the thickness of the tab plating area is greater than the thickness of the middle plating area, the current carrying capacity at the tab position is greatly increased, thereby significantly improving the rate performance of the battery, reducing battery heat generation, and facilitating large-scale promotion and application.
[0010] Preferably, the ratio of the thickness of the tab coating area to the thickness of the intermediate coating area is (1.2-3):1.
[0011] Preferably, the thickness of the tab coating area is 1-3 μm.
[0012] Preferably, the thickness of the intermediate coating area is 0.5-1.2 μm.
[0013] Preferably, the shape of the non-plated area is any one or a combination of at least two of the following: rectangle, semicircle, trapezoid, or triangle, and more preferably a rectangle, wherein the size of the rectangle is (10-100) mm × (30-200) mm.
[0014] Preferably, the ratio of the width of the tab-coated area to the width of the uncoated area is (1-2):1.
[0015] Preferably, the thickness of the underlayer is 10-50 nm.
[0016] Preferably, the polymer film is made of any one or a combination of at least two of polypropylene, polyethylene terephthalate, polyimide, polyphenylene sulfide, or polystyrene.
[0017] Preferably, the thickness of the polymer film is 4-5 μm.
[0018] In a second aspect, the present invention provides a method for preparing a functional current collector as described in the first aspect, the method comprising the following steps:
[0019] (1) Set baffles arranged at intervals on both sides of the polymer film, and use magnetron sputtering to deposit a base layer with serrated edges on at least one side of the polymer film.
[0020] (2) A metal layer is deposited on the surface of the base layer by water plating, and the functional current collector is obtained after slicing.
[0021] The preparation method provided by this invention includes two processes: magnetron sputtering and water plating for thickening. First, a base layer is prepared by magnetron sputtering to provide the necessary electronic pathway for the subsequent water plating process. During the magnetron sputtering deposition process, baffles are arranged at intervals to form a base layer with serrated edges on both sides. During the metal layer thickening process of the water plating process, the current of the current collector passes through the serrated areas on both sides of the edge and enters the middle region of the film. Since the width of the serrated area is small, the current density is greater than that in the middle region of the film, resulting in a higher metal layer deposition rate in the serrated area. This produces a metal layer that is "thin in the middle and thick at the edges", and the electrode positions at the edges are shaped like a city wall, which facilitates the subsequent metal foil transfer and welding process, while also improving the energy density of the battery.
[0022] Preferably, the shape of the baffle in step (1) is any one or a combination of at least two of the following: rectangle, semicircle, trapezoid or triangle, and more preferably a rectangle, wherein the size of the rectangle is (10-100)mm × (30-200)mm.
[0023] Preferably, in step (1), during the deposition process, the baffle and the polymer film are in a relatively static state.
[0024] Preferably, the distance between the baffle and the adjacent baffle in step (1) is 10-100mm.
[0025] Preferably, the water plating method in step (2) includes: using a conductive clamp to hold the positions on both sides of the current collector where the underlayer is deposited, and applying electricity to perform water plating, that is, depositing a metal layer on the surface of the underlayer.
[0026] Preferably, the cutting in step (2) includes: cutting off the water-plating clamping area on both sides of the current collector.
[0027] Thirdly, the present invention provides a battery having a functional current collector as described in the first aspect, which facilitates transfer welding.
[0028] Compared with the prior art, the present invention has the following beneficial effects:
[0029] (1) The functional current collector provided by the present invention thickens the tab coating area, which facilitates the subsequent metal foil transfer welding process, increases the welding strength, avoids the phenomenon of weld breakage or weak welding, and after the electrode sheet is made, since the thickness of the tab coating area is greater than the thickness of the middle coating area, the current carrying capacity at the tab position is greatly increased, thereby significantly improving the rate performance of the battery, reducing the heat generation of the battery, and facilitating large-scale promotion and application.
[0030] (2) The preparation method provided by the present invention includes two processes: magnetron sputtering and water plating for thickening. First, a base layer is prepared by magnetron sputtering to provide the required electronic path for the subsequent water plating process. During the magnetron sputtering deposition process, baffles are arranged at intervals to form a base layer with serrated edges on both sides. During the metal layer thickening process of the current collector in the water plating process, the current passes through the serrated areas on both sides of the edge and enters the middle area of the film. Since the width of the serrated area is small, the current density is greater than that in the middle area of the film, which makes the metal layer deposition rate in the serrated area higher, thereby obtaining a metal layer that is "thin in the middle and thick at the edges". The electrode position at the edge is in the shape of a city wall, which facilitates the subsequent metal foil transfer welding process and improves the energy density of the battery. Attached Figure Description
[0031] Figure 1 These are schematic diagrams of the cross-section of the functional current collector provided in Examples 1-6;
[0032] Figure 2 These are schematic diagrams of the functional current collector plane provided in Examples 1-6;
[0033] Figure 3 This is a schematic diagram of the cross-section of the functional current collector provided in Example 1.
[0034] Wherein: 10-polymer film; 20-conductive layer; 21-undercoat layer; 22-metal layer; 30-intermediate plating area; 40-tab position; 41-non-plating area; 42-tab plating area. Detailed Implementation
[0035] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0036] One embodiment of the present invention provides a functional current collector that facilitates transfer soldering, comprising a polymer film and a conductive layer disposed on at least one side surface of the polymer film. The conductive layer comprises a substrate and a metal layer stacked together, wherein the substrate is located between the polymer film and the metal layer, and the two sides of the substrate are serrated. The metal layer comprises an intermediate plating region and tabs disposed on the two sides of the intermediate plating region.
[0037] The electrode tabs are shaped like a city wall and include non-plated areas and electrode tab plating areas arranged at intervals, and the thickness of the electrode tab plating area is greater than the thickness of the middle plating area.
[0038] The functional current collector provided by this invention thickens the tab plating area, which facilitates the subsequent metal foil transfer welding process, increases the welding strength, and avoids the phenomenon of weld breakage or weak welding. Moreover, after the electrode sheet is made, since the thickness of the tab plating area is greater than the thickness of the middle plating area, the current carrying capacity at the tab position is greatly increased, thereby significantly improving the rate performance of the battery, reducing battery heat generation, and facilitating large-scale promotion and application.
[0039] In some embodiments, the functional current collector is a functional copper current collector, and the corresponding metal layer is a copper layer.
[0040] In some embodiments, the functional current collector is a functional aluminum current collector, and the corresponding metal layer is an aluminum layer.
[0041] In some embodiments, the ratio of the thickness of the tab coating region to the thickness of the intermediate coating region is (1.2-3):1, for example, it can be 1.2:1, 1.4:1, 1.6:1, 1.8:1, 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0042] In some embodiments, the thickness of the tab coating region is 1-3 μm, for example, it can be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm or 3 μm, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0043] In some embodiments, the thickness of the intermediate coating region is 0.5-1.2 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm or 1.2 μm, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0044] In some embodiments, the shape of the non-plated area is any one or a combination of at least two of the following: rectangle, semicircle, trapezoid, or triangle, more preferably rectangle, and the dimensions of the rectangle are (10-100) mm × (30-200) mm, wherein the width is 10-100 mm, for example, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, or 100 mm, and the length is 30-200 mm, for example, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 190 mm, or 200 mm, but is not limited to the listed values, and other unlisted values within this range are also applicable.
[0045] In some embodiments, the ratio of the width of the tab-plated area to the width of the unplated area is (1-2):1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0046] In some embodiments, the thickness of the underlay layer is 10-50nm, for example, it can be 10nm, 15nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm or 50nm, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0047] In some embodiments, the polymer film is made of any one or a combination of at least two of polypropylene, polyethylene terephthalate, polyimide, polyphenylene sulfide, or polystyrene. Typical but non-limiting combinations include a combination of polypropylene and polyethylene terephthalate, a combination of polyethylene terephthalate and polyimide, a combination of polyimide and polyphenylene sulfide, or a combination of polyphenylene sulfide and polystyrene.
[0048] In some embodiments, the thickness of the polymer film is 4-5 μm, for example, it can be 4 μm, 4.1 μm, 4.2 μm, 4.3 μm, 4.4 μm, 4.5 μm, 4.6 μm, 4.7 μm, 4.8 μm, 4.9 μm or 5 μm, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0049] One embodiment of the present invention also provides a method for preparing the functional current collector described in any of the above embodiments, the preparation method comprising the following steps:
[0050] (1) Set baffles arranged at intervals on both sides of the polymer film, and use magnetron sputtering to deposit a base layer with serrated edges on at least one side of the polymer film.
[0051] (2) A metal layer is deposited on the surface of the base layer by water plating, and the functional current collector is obtained after slicing.
[0052] The preparation method provided by this invention includes two processes: magnetron sputtering and water plating for thickening. First, a base layer is prepared by magnetron sputtering to provide the necessary electronic pathway for the subsequent water plating process. During the magnetron sputtering deposition process, baffles are arranged at intervals to form a base layer with serrated edges on both sides. During the metal layer thickening process of the water plating process, the current of the current collector passes through the serrated areas on both sides of the edge and enters the middle region of the film. Since the width of the serrated area is small, the current density is greater than that in the middle region of the film, resulting in a higher metal layer deposition rate in the serrated area. This produces a metal layer that is "thin in the middle and thick at the edges", and the electrode positions at the edges are shaped like a city wall, which facilitates the subsequent metal foil transfer and welding process, while also improving the energy density of the battery.
[0053] In some embodiments, the shape of the baffle in step (1) is any one or a combination of at least two of the following: rectangular, semi-circular, trapezoidal or triangular, more preferably rectangular, and the size of the rectangle is (10-100)mm × (30-200)mm, wherein the width is 10-100mm, for example, it can be 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, and the length is 30-200mm, for example, it can be 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm or 200mm, but is not limited to the listed values, other unlisted values within this range are also applicable.
[0054] In some embodiments, during the deposition process of the underlayer in step (1), the baffle and the polymer film are in a relatively stationary state.
[0055] In some embodiments, the distance between the baffle and the adjacent baffle in step (1) is 10-100mm, for example, it can be 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, but is not limited to the listed values. Other unlisted values within this range are also applicable.
[0056] In some embodiments, the water plating method in step (2) includes: using a conductive clamp to hold the positions on both sides of the current collector where the underlayer is deposited, and applying electricity to perform water plating, that is, depositing a metal layer on the surface of the underlayer.
[0057] In some embodiments, the cutting in step (2) includes cutting off the water-plating clamping area on both sides of the current collector.
[0058] One embodiment of the present invention also provides a battery having a current collector that facilitates transfer welding as described in any of the above embodiments.
[0059] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0060] Example 1
[0061] This embodiment provides a functional copper current collector that facilitates transfer soldering, such as... Figure 1 As shown, the functional copper current collector includes a polymer film 10 and conductive layers 20 disposed on both sides of the polymer film 10. The conductive layer 20 includes a substrate 21 and a metal layer 22 stacked together, with the substrate 21 located between the polymer film 10 and the metal layer 22. The two sides of the substrate 21 are serrated. The metal layer 22 includes an intermediate plating region 30 and tabs 40 disposed on both sides of the intermediate plating region 30. The tabs 40 are wall-shaped, including non-plated regions 41 and tab-plated regions 42 arranged at intervals, and the thickness of the tab-plated regions 42 is greater than the thickness of the intermediate plating region 30 (see...). Figure 2 ).
[0062] Specifically, the polymer film 10 is made of PET and has a thickness of 4.5 μm; the underlayer 21 includes a stacked nickel-chromium layer (5 nm) and a copper layer (40 nm), and the nickel-chromium layer is located on the surface of the polymer film 10 (not shown in the figure); the metal layer 22 is made of copper, the thickness of the middle plating area 30 is 1 μm, and the thickness of the two tab plating areas 42 is 1.6 μm, that is, the ratio of the thickness of the tab plating area 42 to the thickness of the middle plating area 30 is 1.6:1; the non-plating area 41 is rectangular in shape and has a size of 20 mm × 30 mm.
[0063] This embodiment also provides a method for preparing the above-mentioned functional copper current collector, which specifically includes the following steps:
[0064] (1) Vacuum magnetron continuous coating is adopted. Multiple retractable and rotatable baffles are arranged on both sides of the main drum and the baffles are located between the main drum and the target material. When the coating tape is moving, the baffles rotate with the main drum. When the polymer film 10 exits the main drum, the baffles retract sequentially. When it enters the main drum, the baffles are inserted to ensure that the baffles and the polymer film 10 are relatively stationary during the deposition process, so that the metal ions on the target material are deposited only in the area not blocked by the baffles, and finally the baffles 21 with serrated edges are obtained. The serrated edges of the baffles 21 are divided into a coating area and a blank area. The coating area is 30 mm wide and the blank area is 20 mm wide. The coating area is used to generate the tab coating area 42 later and the blank area is used to generate the non-coated area 41 later. The baffles are rectangular in shape and have a size of 20 mm × 30 mm. The distance between the baffles and the adjacent baffles is 30 mm.
[0065] (2) The conductive clamp is used to hold the positions where the bottom layer 21 is deposited on both sides of the current collector (i.e., the plating area), and the clamping depth of the conductive clamp is controlled to be 20nm. Water plating is performed by passing through the sawtooth areas on both sides and entering the middle area of the film. Since the width of the sawtooth area is small, the current density is greater than that of the middle area of the film, the copper deposition rate is higher, and the copper layer thickness in the sawtooth area is greater. After the water plating is completed, the water plating clamping area on both sides of the current collector is cut off to obtain a functional copper current collector with a tab length of 15mm and a width of 30mm.
[0066] In this embodiment, since the specific process conditions of magnetron sputtering and water plating have no significant impact on the structure of the current collector, as long as the underlying layer 21 and metal layer 22 of the corresponding thickness and material are deposited, the specific parameters and conditions are not specifically described here.
[0067] Example 2
[0068] This embodiment provides a functional copper current collector that is easy to transfer and solder. Except for adjusting the thickness of the plating area 42 on both sides of the electrode by adjusting the water plating conditions to 1.2μm, the rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.
[0069] Example 3
[0070] This embodiment provides a functional copper current collector that is easy to transfer and solder. Except for adjusting the water plating conditions to change the thickness of the plating area 42 on both sides of the electrode to 3μm, the other structure and conditions are the same as in Embodiment 1, so they will not be described in detail here.
[0071] Example 4
[0072] This embodiment provides a functional copper current collector that is easy to transfer and solder. Except for adjusting the thickness of the plating area 42 on both sides of the electrode by adjusting the water plating conditions to 3.5μm, the rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.
[0073] Example 5
[0074] This embodiment provides a functional copper current collector that is easy to transfer and solder. Except that the shape of the baffle is changed to a semi-circle, the shape of the corresponding non-plated area 41 is also changed to a semi-circle, and the radius of the semi-circle is 25mm. The rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.
[0075] Example 6
[0076] This embodiment provides a functional copper current collector that is easy to transfer and solder. Except for adjusting the size of the baffle to change the width of the plating area at the edge of the base layer 21 to 15mm and keeping the width of the blank area at 20mm, the rest of the structure and conditions are the same as in embodiment 1, so they will not be described in detail here.
[0077] Comparative Example 1
[0078] This comparative example provides a functional copper current collector, such as... Figure 3 As shown, the functional copper current collector includes a polymer film 10 and conductive layers 20 disposed on both sides of the polymer film 10. The conductive layers 20 include a substrate 21 and a metal layer 22 stacked together, and the substrate 21 is located between the polymer film 10 and the metal layer 22.
[0079] Specifically, the polymer film 10 is made of PET and has a thickness of 4.5 μm; the underlayer 21 includes a nickel-chromium layer (5 nm) and a copper layer (40 nm) stacked together, and the nickel-chromium layer is located on the surface of the polymer film 10 (not shown in the figure); the metal layer 22 is made of copper and has a thickness of 1 μm.
[0080] This comparative example also provides a method for preparing the above-mentioned functional copper current collector, specifically including the following steps:
[0081] (1) A nickel-chromium layer and a copper layer are sequentially deposited on both sides of the polymer film 10 using a vacuum magnetron continuous deposition method to form an underlayer 21;
[0082] (2) The current collector is held on both sides by a conductive clamp, and water plating is performed by applying an electric current. Copper is deposited on the surface of the underlayer 21 to form a metal layer 22, and the metal layer 22 is uniformly deposited on the surface of the underlayer 21. After the water plating is completed, the water plating clamping area on both sides of the current collector is cut off to obtain a functional copper current collector.
[0083] In this comparative example, since the specific process conditions of magnetron sputtering and water plating have no significant impact on the structure of the current collector, as long as the appropriate thickness and material of the underlayer 21 and metal layer 22 are deposited, the specific parameters and conditions are not specifically explained here.
[0084] Comparative Example 2
[0085] This comparative example provides a functional copper current collector. Except for changing the thickness of the non-plated metal layer to 10 nm, the structure and conditions are the same as in Example 1, so they will not be described in detail here.
[0086] Performance testing
[0087] (1) Preparation of pouch cells: Negative electrode sheets were prepared using the functional copper current collectors obtained in Examples 1-6 and Comparative Example 1, and then combined with conventional positive aluminum current collectors to form 10Ah stacked pouch cells. The positive current collector used 10μm thick aluminum foil, and the positive electrode material was commercially available NCM532. The mass ratio of the positive electrode active material was NCM:CNT:PVDF = 97.5:1:1.5. The negative electrode current collector used functional copper current collectors, and the negative electrode material was artificial graphite. The mass ratio of the negative electrode active material was artificial graphite:conductive carbon black:CMC:SBR = 95.5:1.5:1.2:1.8. The active materials were coated, rolled, bonded, and slit to form positive and negative electrode sheets. The areal density of the positive electrode was 400 g / m³. 2 The compacted density is 3.4 g / m³. 3 The negative electrode surface density is 198 g / m³. 2 The compacted density is 1.7 g / m³. 3 The negative electrode is bonded with a 6μm thick copper foil as an external tab, with a tab width of 30mm. The electrode sheets are then die-cut and stacked to form a core. A portion of the plating on the negative electrode is die-cut away, leaving a 20mm tab width. The prepared core undergoes tab welding, encapsulation, electrolyte injection, and formation to obtain a finished 10Ah soft-pack battery.
[0088] (2) Battery performance test:
[0089] (a) High-rate charge-discharge test at room temperature (1C / 3C / 5C / 7C): The above-mentioned soft-pack battery was charged at room temperature (25°C) with a current of 1cA. After charging to 4.2V, constant voltage charging was performed. When the current dropped to 500mA, the charging was terminated. Then, the battery was discharged to 2.75V with currents of 1cA / 3cA / 5cA / 7cA respectively, and the discharge capacity retention rate was recorded.
[0090] (b) Temperature rise test during rate discharge: A temperature sensing probe is attached to the negative electrode tab of the battery in test (a) and wrapped with tape to ensure it is in close contact with the battery surface. The battery temperature rise is recorded during the rate charge and discharge process, and the highest temperature on the battery surface is recorded.
[0091] (c) Battery DC internal resistance (DCR) test: After fully charging the battery, discharge it to 50% of the battery's rated capacity, discharge it with a current of 10cA for 6s, and record the voltage drop of the battery. The calculation formula is: DCR = voltage drop ΔU / current I.
[0092] The test results of the pouch cells corresponding to the functional copper current collectors obtained in Examples 1-6 and Comparative Example 1 are shown in Table 1 below.
[0093] Table 1
[0094]
[0095] As shown in Table 1:
[0096] (1) The thickness of the tab coating area has a significant impact on battery performance: Based on Example 1, Examples 2-4 reduced or increased the thickness of the tab coating area, respectively, which resulted in a decrease in the capacity retention rate to varying degrees. However, the battery temperature rise and DC resistance were lower than those of Example 1.
[0097] (2) The shape of the non-plated area also affects battery performance to some extent: Based on Example 1, Example 5 changes the shape of the baffle to a semi-circle, and the shape of the corresponding non-plated area is also changed to a semi-circle. In comparison, the capacity retention rate of the functional copper current collector obtained in Example 5 is not as good as that in Example 1, but its battery temperature rise and DC resistance are also lower than those in Example 1.
[0098] (3) The width ratio of the plated area and the blank area (i.e., the tab plated area and the non-plated area) also affects the battery performance to some extent: Based on Example 1, Example 6 changes the width and ratio of the plated area and the blank area. In comparison, the capacity retention rate of the functional copper current collector obtained in Example 6 is not as good as that in Example 1, but its battery temperature rise and DC resistance are also lower than those in Example 1.
[0099] (4) Compared with Example 1, Comparative Example 1 uses a conventional current collector, and Comparative Example 2 changes the thickness of the non-plated metal layer. Both of these result in a lower capacity retention rate than Example 1, and their battery temperature rise and DC resistance are significantly higher than those of Example 1.
[0100] Therefore, the functional current collector provided by this invention thickens the tab plating area, which facilitates the subsequent metal foil transfer welding process, increases the welding strength, and avoids the phenomenon of weld breakage or weak welding. Moreover, after the electrode sheet is made, since the thickness of the tab plating area is greater than the thickness of the middle plating area, the current carrying capacity at the tab position is greatly increased, thereby significantly improving the rate performance of the battery, reducing battery heat generation, and facilitating large-scale promotion and application.
[0101] Furthermore, the preparation method provided by this invention includes two processes: magnetron sputtering and water plating for thickening. First, a base layer is prepared by magnetron sputtering to provide the necessary electronic pathway for the subsequent water plating process. During the magnetron sputtering deposition process, baffles are arranged at intervals to form a base layer with serrated edges on both sides. During the metal layer thickening process of the water plating process, the current of the current collector passes through the serrated areas on both sides of the edge and enters the middle region of the film. Since the width of the serrated area is small, the current density is greater than that in the middle region of the film, resulting in a higher metal layer deposition rate in the serrated area. This produces a metal layer that is "thin in the middle and thick at the edges", and the electrode positions at the edges are shaped like a city wall, which facilitates the subsequent metal foil transfer and welding process, while also improving the energy density of the battery.
[0102] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A functional current collector for easy transfer welding, comprising a polymer film and a conductive layer disposed on at least one surface of the polymer film, the conductive layer comprising a laminated underlayer and a metal layer, wherein the underlayer is located between the polymer film and the metal layer, characterized in that, The two sides of the underlayer are serrated, and the metal layer includes an intermediate plating area and tabs disposed on both sides of the intermediate plating area. The electrode tabs are shaped like a city wall and include non-plated areas and electrode tab plating areas arranged at intervals, and the thickness of the electrode tab plating area is greater than the thickness of the middle plating area.
2. The functional manifold for easy transfer welding according to claim 1, characterized in that, The ratio of the thickness of the tab coating area to the thickness of the intermediate coating area is (1.2-3):1; And / or, the thickness of the tab coating area is 1-3 μm; And / or, the thickness of the intermediate coating region is 0.5-1.2 μm.
3. The functional manifold for easy transfer welding according to claim 1 or 2, characterized in that, The shape of the non-plated area is any one or a combination of at least two of the following: rectangle, semicircle, trapezoid or triangle, more preferably rectangle, and the size of the rectangle is (10-100)mm×(30-200)mm. And / or, the ratio of the width of the tab-plated area to the width of the unplated area is (1-2):1; And / or, the thickness of the substrate is 10-50 nm.
4. The functional manifold for easy transfer welding according to claim 1 or 2, characterized in that, The polymer film is made of any one or a combination of at least two of the following: polypropylene, polyethylene terephthalate, polyimide, polyphenylene sulfide, or polystyrene. And / or, the thickness of the polymer film is 4-5 μm.
5. A method for preparing a functional current collector as described in any one of claims 1-4, characterized in that, The preparation method comprises the following steps: (1) Set baffles arranged at intervals on both sides of the polymer film, and use magnetron sputtering to deposit a base layer with serrated edges on at least one side of the polymer film. (2) A metal layer is deposited on the surface of the base layer by water plating, and the functional current collector is obtained after slicing.
6. The preparation method according to claim 5, characterized in that, The shape of the baffle in step (1) is any one or a combination of at least two of the following: rectangle, semicircle, trapezoid or triangle, and is more preferably a rectangle, with the dimensions of the rectangle being (10-100) mm × (30-200) mm.
7. The preparation method according to claim 5 or 6, characterized in that, In step (1), during the deposition process, the baffle and the polymer film are in a relatively stationary state. And / or, the distance between the baffle in step (1) and the adjacent baffle is 10-100mm.
8. The preparation method according to claim 5, characterized in that, The water plating method in step (2) includes: using a conductive clamp to hold the positions on both sides of the current collector where the underlayer is deposited, and then applying electricity to perform water plating, that is, depositing a metal layer on the surface of the underlayer.
9. The preparation method according to claim 5 or 8, characterized in that, Step (2) involves cutting off the water-plating clamping area on both sides of the current collector.
10. A battery, characterized in that, The battery contains a functional current collector that facilitates transfer welding as described in any one of claims 1-4.