CN116706448A - Method for welding composite current collector and tab - Google Patents
Method for welding composite current collector and tab Download PDFInfo
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- CN116706448A CN116706448A CN202310620099.4A CN202310620099A CN116706448A CN 116706448 A CN116706448 A CN 116706448A CN 202310620099 A CN202310620099 A CN 202310620099A CN 116706448 A CN116706448 A CN 116706448A
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- current collector
- welding
- composite current
- metal
- tab
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- 239000002131 composite material Substances 0.000 title claims abstract description 107
- 238000003466 welding Methods 0.000 title claims abstract description 85
- 238000000034 method Methods 0.000 title claims abstract description 27
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 67
- 229910052751 metal Inorganic materials 0.000 claims description 61
- 239000002184 metal Substances 0.000 claims description 61
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 41
- 229910052782 aluminium Inorganic materials 0.000 claims description 35
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 35
- 229910052759 nickel Inorganic materials 0.000 claims description 35
- 229920000642 polymer Polymers 0.000 claims description 31
- -1 polypropylene Polymers 0.000 claims description 29
- 238000004804 winding Methods 0.000 claims description 26
- 229910052802 copper Inorganic materials 0.000 claims description 22
- 239000010949 copper Substances 0.000 claims description 22
- 239000004743 Polypropylene Substances 0.000 claims description 17
- 229920001155 polypropylene Polymers 0.000 claims description 17
- 238000007493 shaping process Methods 0.000 claims description 13
- 229910001415 sodium ion Inorganic materials 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 7
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 4
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 4
- 239000004642 Polyimide Substances 0.000 claims description 3
- 239000004721 Polyphenylene oxide Substances 0.000 claims description 3
- 239000004734 Polyphenylene sulfide Substances 0.000 claims description 3
- 239000004793 Polystyrene Substances 0.000 claims description 3
- 229920003207 poly(ethylene-2,6-naphthalate) Polymers 0.000 claims description 3
- 229920001707 polybutylene terephthalate Polymers 0.000 claims description 3
- 239000011112 polyethylene naphthalate Substances 0.000 claims description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 claims description 3
- 239000005020 polyethylene terephthalate Substances 0.000 claims description 3
- 229920001721 polyimide Polymers 0.000 claims description 3
- 229920006380 polyphenylene oxide Polymers 0.000 claims description 3
- 229920000069 polyphenylene sulfide Polymers 0.000 claims description 3
- 229920002223 polystyrene Polymers 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 239000004800 polyvinyl chloride Substances 0.000 claims description 3
- 229920000915 polyvinyl chloride Polymers 0.000 claims description 3
- 229910000838 Al alloy Inorganic materials 0.000 claims description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 2
- 229910001416 lithium ion Inorganic materials 0.000 claims description 2
- 239000011889 copper foil Substances 0.000 description 19
- 238000004519 manufacturing process Methods 0.000 description 18
- 239000011888 foil Substances 0.000 description 11
- 238000007747 plating Methods 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000003475 lamination Methods 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 5
- 239000013543 active substance Substances 0.000 description 4
- 230000032683 aging Effects 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 229910021385 hard carbon Inorganic materials 0.000 description 4
- 238000002347 injection Methods 0.000 description 4
- 239000007924 injection Substances 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000004806 packaging method and process Methods 0.000 description 4
- 229920006255 plastic film Polymers 0.000 description 4
- 239000002985 plastic film Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000022131 cell cycle Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/50—Current conducting connections for cells or batteries
- H01M50/531—Electrode connections inside a battery casing
- H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Composite Materials (AREA)
- Connection Of Batteries Or Terminals (AREA)
- Secondary Cells (AREA)
Abstract
The application discloses a method for welding a composite current collector and a tab. The method for welding the composite current collector and the tab greatly reduces the internal resistance and simultaneously increases the structural strength, and avoids the attenuation of the subsequent battery performance caused by insufficient virtual welding or welding strength.
Description
Technical Field
The application relates to the technical field of secondary batteries, in particular to a method for welding a composite current collector and a tab.
Background
As the cycle performance and energy density of the battery are continuously improved, the battery safety is increasingly prominent. A composite current collector obtained by compositing a polymer film and a metal plating layer has been attracting attention. The current collector adopting the high polymer metal coating structure can effectively improve the material strength, simultaneously prevent the battery from needling, extrusion and heavy impact, greatly enhance the safety of the battery, and further has the advantages of light weight of high polymer and improvement of the energy density of the battery. However, the composite current collector takes the polymer as a carrier, and conductive metal layers are plated on two sides of the composite current collector, and as the middle polymer is an insulating layer, the metal plating layers on two sides cannot be conducted, and the electrode lugs of the multilayer composite current collector are directly welded in a traditional welding mode, so that the welding strength is poor and the internal resistance is high.
The Chinese patent application with publication number of CN110936010A discloses a welding method for a composite current collector lug. The composite current collector A is clamped by the metal lugs to be pre-welded to form B, then the pole pieces B and the pole pieces A are laminated at intervals from bottom to top, and finally the multi-layer metal lugs and the positive pole lugs or the negative pole lugs corresponding to the lithium battery are subjected to final welding.
The application discloses a method for welding a composite current collector tab of a lithium battery, which is disclosed in Chinese patent application with publication number of CN111900413A, wherein two metal tabs are used for clamping and pre-welding the composite current collector tab on a conventional tab spacing lamination, and finally, the conducting effect is improved in a multi-layer tab final welding mode.
The method of the two patents can solve the problem that the welding process of the composite current collector cannot be conducted in a communicating way, but the pre-welding effect of the metal sheet and the composite current collector is poor, the internal resistance is high and the strength is low in the actual operation process.
Disclosure of Invention
The application provides a method for welding a composite current collector and a tab, aiming at the defects in the prior art.
The method for welding the composite current collector and the tab comprises the following steps of:
s1: the composite current collector is wound several turns,
s2: shaping and pre-welding the overlapped part of the wound composite current collector to fix different layers after winding,
s3: stacking the composite current collectors obtained by the treatment of a plurality of steps S2, then clamping the stacked composite current collectors by using two metal current collecting sheets,
s4: two metal current collecting plates are fixed by using a fixing mechanism,
s5: and (3) welding and fixing the two metal current collecting sheets on the composite current collector obtained in the step (S4) with the lugs of the battery.
Preferably, the polymer layer is at least one of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyimide or derivatives thereof, the metal layer is at least one of copper, copper alloy, aluminum alloy, nickel and nickel alloy, and the metal current collecting sheet is at least one of copper, copper alloy, aluminum, nickel and nickel alloy.
Preferably, the winding turns in the step S1 are 1-5 turns; in the step S3, 10 to 100 composite current collectors processed in the step S2 are stacked. Preferably, the winding width in step S1 is 5 to 10mm.
Preferably, the fixing mechanism is a rivet penetrating through two metal sheets, the rivet is made of one of metal copper, aluminum or alloy thereof, and the size and the diameter of the rivet are 1-5 mm. The rivet is used for fixing each composite current collector and two metal current collecting sheets at two sides in series. The length of the rivet is selected according to actual needs.
Preferably, the thickness of the polymer layer is 2-6 μm; the thickness of the metal layer is 20-500 nm; the thickness of the metal current collecting sheet is 0.2-2 mm.
Preferably, in step S5, one ends of the two metal current collecting sheets protrude from the composite current collector, and the protruding ends clamp the tab and are welded and fixed with the tab.
Preferably, in the step S2, ultrasonic welding is adopted for shaping and pre-welding, the amplitude is 15 mu m, the energy is 80J, and the welding pressure is 20PSI; in the step S4, ultrasonic welding is adopted, the amplitude is 30 mu m, the energy is 250J, and the welding pressure is 30PSI.
The application also provides a welding structure of the composite current collector and the tab, which is prepared by using the method.
The application also provides a sodium ion or lithium ion battery, which comprises a positive plate and a negative plate, wherein the positive plate is provided with a positive lug, the negative plate is provided with a negative lug, and at least one of the positive plate and the negative plate uses the welding structure of the composite current collector and the lug.
The method for welding the composite current collector and the tab greatly reduces the internal resistance and simultaneously increases the structural strength, and avoids the attenuation of the subsequent battery performance caused by insufficient virtual welding or welding strength.
Drawings
Fig. 1 is a schematic structural view of a composite current collector of the present application after winding.
Fig. 2 is a schematic structural diagram of a plurality of composite current collectors stacked and fixed.
Fig. 3 is a schematic diagram of a welding structure of the stacked composite current collector and the tab.
Fig. 4 is a cycle curve of the battery capacity retention test.
Fig. 5 is a cycle curve of the battery capacity retention test in test example 2.
Detailed Description
Example 1
The composite current collector can be an anode composite current collector or a cathode composite current collector, the anode composite current collector and the cathode composite current collector are collectively called as a composite current collector in the application, the anode composite current collector is used for being welded and connected with an anode lug, and the cathode composite current collector is used for being welded and connected with a cathode lug.
As shown in fig. 1 to 3, the composite current collector of the present application includes a polymer layer 2 in the middle, and a metal layer 1 and a metal layer 3 located at both sides of the polymer layer 2. The middle polymer layer 2 is used as a carrier of the whole composite current collector, and the polymer layer 2 is made of insulating materials. While the metal layer 1 and the metal layer 3 on both sides are able to achieve electrical conduction.
The polymer layer 2 may be made of at least one of the following materials: polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyimide, or derivatives of these polymer materials may be used. The thickness of the polymer layer 2 is 2 to 6 μm.
The material of the metal layer 1 and the metal layer 3 may be at least one of copper, aluminum, and nickel, or an alloy of these metals. The thickness of each of the metal layer 1 and the metal layer 3 is 20 to 500nm. The metal layer may be formed on both sides of the polymer layer 2 by electroplating.
As shown in fig. 1, the single composite current collector is wound several times, and after winding, one end is positioned in the winding center and the other end is free. Preferably, the number of windings is 1 to 5. After winding, the metal layers 1 and 3 are overlapped and conducted in partial areas, so that a conductive contact surface 4 is formed, and the metal layers 1 and 3 positioned on two sides of the polymer layer 2 can be conducted through winding, so that the overall internal resistance of the composite current collector after the welding and combination of the lugs is reduced. The width d of the conductive contact surface 4 is preferably 5 to 10mm.
After each composite current collector is wound, the overlapped part is required to be shaped and pre-welded, so that different layers are fixed after winding, and the composite current collector is not easy to scatter.
As shown in fig. 2, a plurality of wound composite current collectors are stacked, and then the stacked composite current collectors are sandwiched by two metal current collecting sheets 6, and then the two metal current collecting sheets 6 are fixed by a fixing mechanism to form an integral structure.
The metal current collector 6 may be made of at least one of copper, aluminum, and nickel, or an alloy of these metals. The thickness of the metal current collecting plate 6 is 0.2-2 mm. The number of stacks of the composite current collector is preferably 10 to 100. The number of composite current collectors stacked in the two metal current collecting sheets 6 can be comprehensively considered according to the condition of the electrode lugs to be welded, the winding number of the composite current collectors and the thickness of the composite current collectors, and in general, the distance between the two metal current collecting sheets 6 needs to be matched with the thickness of the electrode lugs.
The fixing mechanism can use a common structure, for example, rivets 5 can be used for fixing each composite current collector and metal current collecting sheets 6 on two sides, and mounting holes for the rivets 5 to penetrate through are needed to be reserved on the metal current collecting sheets 6, and the composite current collector can be directly penetrated through by the rivets 5 due to the fact that the thickness of each layer is thinner and the overall hardness is lower, so that the mounting holes for the rivets can not be reserved, and of course, if the rivets are reserved in advance, the complexity of preparing the composite current collector can be increased. The rivet 5 is made of one of metallic copper, aluminum or alloy thereof, and the dimension diameter of the rivet 5 is 1-5 mm.
The structure shown in fig. 2 is welded with the tab, and the welded structure is shown in fig. 3. The two metal current collecting plates 6 are used for being free when being wound away from the composite current collector at one end welded with the electrode lugs, one end welded with the metal current collecting plates 6 protrudes out of the stacking area of each composite current collector, the end parts of the electrode lugs extend into the space between the two metal current collecting plates 6, and then the electrode lugs are respectively welded with the two metal current collecting plates 6.
Example 2
The embodiment provides a sodium ion battery, which is used for manufacturing a sodium ion battery core 3V3Ah battery core with the thickness of 5mm, the height of 200mm and the width of 163mm, wherein a welding structure of a composite current collector and a tab is used for a negative electrode, and an aluminum foil current collector is used for a positive electrode instead of the composite current collector. The method specifically comprises the following steps:
s1) manufacturing a pole piece:
wherein the positive electrode adopts aluminum foil with the thickness of 15 mu m, the negative electrode adopts composite copper foil with the thickness of 6 mu m (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm respectively); wherein the active substance: the mass ratio of the positive electrode components is NNFM to SP to PVDF to NMP=96 to 2 to 55; the mass ratio of each component of the negative electrode is hard carbon to SP to binder (SBR) to CMC to water=94:1.5:3:1.5:80.
S2) manufacturing a composite current collector assembly structure:
the copper foil composite current collector (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm each) is wound for 1 circle, and the winding width is 5mm;
shaping and pre-welding the overlapped part after winding, wherein the amplitude is 15 mu m, the energy is 80J, and the welding pressure is 20PSI, so that 1 group of wound composite current collectors are obtained, and 11 groups are prepared in total;
two nickel plates with the thickness of 0.5mm (the width of the nickel plates is 5mm, the length of the nickel plates is 12mm, the surfaces of the nickel plates are provided with holes with the thickness of 1.5mm, and the hole spacing is 6 mm) are used for clamping 11 groups of shaping parts of the composite current collector, and the shaping parts are formed from top to bottom: nickel current collector-each group of composite current collector-nickel current collector sandwich structure;
rivet is used to pass through the holes of the two current collecting sheets and 11 groups of composite current collectors, then ultrasonic riveting is carried out, the rivet is made of copper, and the diameter is 1.2mm; and manufacturing to obtain the composite current collector assembly structure.
S3) manufacturing a battery winding core:
and stacking the positive electrode sheet, the polypropylene diaphragm (with the thickness of 16 mu m) +the negative electrode sheet together in a lamination mode, wherein the positive electrode sheet is 10 layers, and the negative electrode sheet is 11 layers.
S4) placing a metal nickel tab (the length of the nickel tab is 45mm, the width of the nickel tab is 12 mm) on a negative pole piece in the battery winding core between two nickel current collecting pieces of the composite current collector assembly structure, and performing ultrasonic welding, wherein the amplitude is 20 mu m, the energy is 280J, and the welding pressure is 30PSI.
S5) pre-welding the positive electrode current collector 9 layers (15 mu m aluminum foil), wherein the amplitude is 18 mu m, the energy is 100J, and the welding pressure is 25PSI.
S6) using an aluminum tab as a positive electrode tab (the aluminum tab is 45mm long and 12mm wide), and carrying out ultrasonic welding on the aluminum tab and the current collector subjected to the pre-welding in the step S5, wherein the amplitude is 20 mu m, the energy is 200J, and the welding pressure is 25PSI.
S7) carrying out aluminum plastic film packaging and liquid injection on the battery core, standing, forming, aging, capacity dividing and offline.
Example 3
The embodiment provides a sodium ion battery, which is used for manufacturing a sodium ion battery core 3V3Ah battery core with the thickness of 5mm, the height of 200mm and the width of 163mm, wherein a welding structure of a composite current collector and a tab is used for both a negative electrode and a positive electrode. The method specifically comprises the following steps:
s1) manufacturing a pole piece:
wherein the positive electrode adopts aluminum foil with the thickness of 15 mu m, the negative electrode adopts composite copper foil with the thickness of 6 mu m (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm respectively); wherein the active substance: the mass ratio of the positive electrode components is NNFM to SP to PVDF to NMP=96 to 2 to 55; the mass ratio of each component of the negative electrode is hard carbon to SP to binder (SBR) to CMC to water=94:1.5:3:1.5:80.
S2) manufacturing a negative electrode composite current collector assembly structure:
the copper foil composite current collector (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm each) is wound for 1 circle, and the winding width is 5mm;
shaping and pre-welding the overlapped part after winding, wherein the amplitude is 15 mu m, the energy is 80J, and the welding pressure is 20PSI, so that 1 group of wound composite current collectors are obtained, and 11 groups are prepared in total;
two nickel plates with the thickness of 0.5mm (the width of the nickel plates is 5mm, the length of the nickel plates is 12mm, the surfaces of the nickel plates are provided with holes with the thickness of 1.5mm, and the hole spacing is 6 mm) are used for clamping 11 groups of shaping parts of the composite current collector, and the shaping parts are formed from top to bottom: nickel current collector-each group of composite current collector-nickel current collector sandwich structure;
rivet is used to pass through the holes of the two current collecting sheets and 11 groups of composite current collectors, then ultrasonic riveting is carried out, the rivet is made of copper, and the diameter is 1.2mm; and manufacturing and obtaining the composite negative electrode current collector assembly structure.
S3) manufacturing an anode composite current collector assembly structure:
the aluminum foil composite current collector (wherein the polymer layer is 11.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm each) is wound for 1 circle, and the winding width is 5mm;
shaping and pre-welding the overlapped part after winding, wherein the amplitude is 15 mu m, the energy is 80J, and the welding pressure is 20PSI, so that 1 group of wound composite current collectors are obtained, and 10 groups are prepared in total;
two aluminum sheets (nickel sheets with the width of 5mm and the length of 12mm, and the surfaces of 1.5mm holes and the hole spacing of 6 mm) with the thickness of 0.5mm are used for clamping 11 groups of shaping parts of the composite current collector, and the shaping parts are formed from top to bottom: nickel current collector-each group of composite current collector-nickel current collector sandwich structure;
using rivets to penetrate through the hole sites of the two current collecting sheets and 10 groups of composite current collectors, and then performing ultrasonic riveting, wherein the rivets are made of aluminum and have a diameter of 1.2mm; and manufacturing and obtaining the composite anode current collector assembly structure.
S4) manufacturing a battery winding core:
and stacking the positive electrode sheet, the polypropylene diaphragm (with the thickness of 16 mu m) +the negative electrode sheet together in a lamination mode, wherein the positive electrode sheet is 10 layers, and the negative electrode sheet is 11 layers.
S5) placing a metal nickel tab (the length of the nickel tab is 45mm, the width of the nickel tab is 12 mm) on a negative pole piece in a battery winding core between two nickel current collecting pieces of a composite negative current collector assembly structure, and performing ultrasonic welding, wherein the amplitude is 20 mu m, the energy is 280J, and the welding pressure is 30PSI.
S6) placing a metal aluminum tab (the length of a nickel tab is 45mm, the width of the nickel tab is 12 mm) on the positive electrode plate in the battery winding core between two aluminum current collecting plates of the composite positive electrode current collecting body assembly structure, and performing ultrasonic welding, wherein the amplitude is 20 mu m, the energy is 200J, and the welding pressure is 25PSI.
S7) carrying out aluminum plastic film packaging and liquid injection on the battery core, standing, forming, aging, capacity dividing and offline.
Comparative example 1
And manufacturing a sodium ion cell 3V3Ah cell with the thickness of 5mm, the height of 200mm and the width of 163mm, wherein a composite current collector is used as a negative current collector, but is not wound, but is directly welded, and an aluminum foil current collector is used as a positive current collector. The method comprises the following steps:
s1) manufacturing a pole piece:
wherein the positive electrode adopts aluminum foil with the thickness of 15 mu m, the negative electrode adopts composite copper foil with the thickness of 6 mu m (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, and the two copper plating layers are 250nm respectively);
wherein the active substance: the mass ratio of the positive electrode components is NNFM to SP to PVDF to NMP=96 to 2 to 55; the mass ratio of each component of the negative electrode is hard carbon to SP to binder (SBR) to CMC to water=94:1.5:3:1.5:80.
S2) pre-welding copper foil composite current collectors (wherein the polymer layer is 5.5 mu m, the material of the polymer layer is polypropylene, the two copper plating layers are 250nm each) by clamping two layers of copper foil (the thickness of the copper foil is 6 mu m, the width of the copper foil is 12mm, and the length of the copper foil is 12 mm) on two sides, wherein the amplitude of the copper foil is 15 mu m, the energy is 80J, and the welding pressure is 20PSI, so that 1 group of negative electrode is obtained, one end of the copper foil protrudes out of the copper foil composite current collectors and is used for welding between a follow-up electrode lug.
S3) repeating the step S2) to prepare 11 groups of negative electrodes.
S4) stacking 11 groups of negative electrodes in the step S3 up and down, and then pre-welding 22 layers of copper foils at one end welded with the tab by ultrasonic welding, wherein the amplitude is 18 mu m, the energy is 150J, and the welding pressure is 25PSI. For the copper plating layers on the two lower sides of the same copper foil composite current collector, the copper plating layers on the two sides realize conduction because the copper foils on the two sides are welded together.
S5) manufacturing a battery winding core, and stacking the positive electrode plate, the polypropylene diaphragm (with the thickness of 16 mu m) and the negative electrode plate together in a lamination mode.
S6) taking a metal nickel tab as a negative electrode tab (the nickel tab is 45mm long and 12mm wide), overlapping the 22 layers of copper current collectors after the pre-welding in the step S4, putting the current collectors under, and carrying out ultrasonic welding with the amplitude of 20 mu m, the energy of 280J and the welding pressure of 30PSI on the overlapped part, wherein the electrode tab is 8mm wide.
S7) pre-welding the positive electrode current collector 10 layer (15 mu m aluminum foil), wherein the amplitude is 18 mu m, the energy is 100J, and the welding pressure is 25PSI.
S8) using an aluminum tab as a positive electrode tab (the aluminum tab is 45mm long and 12mm wide), and carrying out ultrasonic welding on the aluminum tab and the current collector subjected to the pre-welding in the step S7, wherein the amplitude is 20 mu m, the energy is 200J, and the welding pressure is 25PSI.
S9) carrying out aluminum plastic film packaging and liquid injection on the battery core, standing, forming, aging, capacity dividing and offline.
Comparative example 2
And manufacturing a sodium ion cell 3V3Ah cell with the thickness of 5mm, the height of 200mm and the width of 163mm, wherein a copper foil current collector is used as a negative current collector, an aluminum foil current collector is used as a positive current collector, and both the positive and negative electrodes are not composite current collectors. The method specifically comprises the following steps:
s1) manufacturing a pole piece, wherein an anode adopts aluminum foil with the thickness of 15 mu m, and a cathode adopts copper foil with the thickness of 6 mu m;
wherein the active substance: the mass ratio of the positive electrode components is NNFM to SP to PVDF to NMP=96 to 2 to 55; the mass ratio of each component of the negative electrode is hard carbon to SP to binder (SBR) to CMC to water=94:1.5:3:1.5:80.
S2) manufacturing a battery winding core, and stacking the positive electrode plate, the polypropylene diaphragm (with the thickness of 16 mu m) and the negative electrode plate together in a lamination mode.
S3) performing ultrasonic welding pre-welding on the 11 layers of copper foils, wherein the amplitude is 15 mu m, the energy is 130J, and the welding pressure is 25PSI.
S4) using a metal nickel tab as a negative electrode tab (the nickel tab is 45mm long and 12mm wide), and carrying out ultrasonic welding with the amplitude of 20 mu m, the energy of 250J and the welding pressure of 28PSI on the 11-layer copper current collector subjected to the pre-welding in the step S3).
S5) pre-welding the positive electrode current collector 10 layer (15 mu m aluminum foil), wherein the amplitude is 18 mu m, the energy is 100J, and the welding pressure is 25PSI.
S6) using an aluminum tab as a positive electrode tab (the aluminum tab is 45mm long and 12mm wide), and carrying out ultrasonic welding on the aluminum tab and the current collector subjected to the pre-welding in the step S5, wherein the amplitude is 20 mu m, the energy is 200J, and the welding pressure is 25PSI.
S7) carrying out aluminum plastic film packaging and liquid injection on the battery core, standing, forming, aging, capacity dividing and offline.
Detection example 1
Performing a battery internal resistance test and a negative electrode post temperature rise test on the battery of the example 2 (the negative electrode adopts a composite current collector assembly structure) and the comparative example 1, wherein the test steps are that the battery is fully charged with 0.5C constant current and constant voltage to 3.95V cutoff current of 0.05C, and after standing for 6 hours, the battery is discharged to 1.5V at 0.5C; circulation test the battery is fully charged to 3.95V cutoff current of 0.05C at constant current and constant voltage, after standing for 10min, 0.5C is discharged to 1.5V, after standing for 10min, circulation is carried out 696 times, the battery capacity retention rate is tested, the test result is shown in table 1, and the circulation curve is shown in fig. 4.
Table 1 test results
| Test item | Example 2 | Comparative example 1 |
| Internal resistance of battery cell | 1.5mΩ | 8mΩ |
| Circulating anode Wen Sheng | 1.5 | 10 |
| Cycle life retention% @696 weeks | 96.89 | 87.86 |
Example 2 has low internal resistance and low temperature rise compared to comparative example 1, and the battery cell cycle performance of comparative example 1 is reduced due to the temperature rise.
Detection example 2
For example 2 (the negative electrode adopts a composite current collector assembly structure), example 3 (the positive electrode and the negative electrode adopt a composite current collector assembly structure) and comparative example 2 (the positive electrode and the negative electrode adopt normal current collectors), carrying out battery internal resistance test and negative electrode post temperature rise test, fully charging the battery with 0.5C constant current and constant voltage to 3.95V cutoff current of 0.05C, and discharging the battery with 0.5C to 1.5V after standing for 6 hours; circulation test the battery is fully charged to 3.95V cutoff current of 0.05C at constant current and constant voltage, after standing for 10min, 0.5C is discharged to 1.5V, after standing for 10min, circulation is carried out 696 times, the battery capacity retention rate is tested, the test result is shown in table 2, and the circulation curve is shown in fig. 5.
Table 2 test results
In example 2, example 3 showed little difference in cycle performance, while the internal resistance temperature rise was increased, as compared with comparative example 2, while improving the energy density and safety of the battery cell.
The metal current collector has good conductivity and lower internal resistance of the battery cell, and the composite current collector has improved internal resistance of the battery cell due to the existence of the middle polymer layer, so that the overall performance of the battery cell is influenced. The use of composite current collectors, while better in safety than metal current collectors, sacrifices a portion of the performance. After the welding structure of the composite current collector and the electrode lugs is used, the performance is also greatly close to that of a metal current collector on the basis of improving the safety, and the welding structure has better application value.
Claims (10)
1. The method for welding the composite current collector and the tab is characterized by comprising the following steps of:
s1: the composite current collector is wound several turns,
s2: shaping and pre-welding the overlapped part of the wound composite current collector to fix different layers after winding,
s3: stacking the composite current collectors obtained by the treatment of a plurality of steps S2, then clamping the stacked composite current collectors by using two metal current collecting sheets,
s4: two metal current collecting plates are fixed by using a fixing mechanism,
s5: and (3) welding and fixing the two metal current collecting sheets on the composite current collector obtained in the step (S4) with the lugs of the battery.
2. The method of claim 1, wherein the polymer layer is at least one of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polypropylene, polyvinyl chloride, polyvinylidene fluoride, polytetrafluoroethylene, polyphenylene sulfide, polyphenylene oxide, polystyrene, polyimide, or derivatives thereof, the metal layer is at least one of copper, copper alloy, aluminum alloy, nickel, and nickel alloy, and the metal current collector is at least one of copper, copper alloy, aluminum, nickel, and nickel alloy.
3. The method according to claim 1, wherein the number of windings in step S1 is 1-5; in the step S3, 10 to 100 composite current collectors processed in the step S2 are stacked.
4. The method according to claim 1, wherein the winding width in step S1 is 5 to 10mm.
5. The method according to claim 1, wherein the fixing mechanism is a rivet passing through two metal sheets, the rivet is made of one of copper, aluminum or alloy thereof, and the rivet has a size of 1-5 mm in diameter.
6. The method according to claim 1, wherein the polymer layer has a thickness of 2 to 6 μm;
the thickness of the metal layer is 20-500 nm;
the thickness of the metal current collecting sheet is 0.2-2 mm.
7. The method according to claim 1, wherein in step S5, one ends of the two metal current collecting sheets protrude from the composite current collector, and the protruding ends clamp and are welded to the tabs.
8. The method according to claim 1, wherein the shaping pre-welding in step S2 is performed by ultrasonic welding with an amplitude of 15 μm, an energy of 80J and a welding pressure of 20PSI;
in the step S4, ultrasonic welding is adopted, the amplitude is 30 mu m, the energy is 250J, and the welding pressure is 30PSI.
9. A welded structure of a composite current collector and a tab, characterized in that it is prepared by the method of any one of claims 1 to 8.
10. A sodium ion or lithium ion battery comprising a positive plate and a negative plate, wherein the positive plate is provided with a positive lug, the negative plate is provided with a negative lug, and at least one of the positive plate and the negative plate uses the welding structure of the composite current collector and the lug according to claim 9.
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| CN202310620099.4A CN116706448A (en) | 2023-05-29 | 2023-05-29 | Method for welding composite current collector and tab |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117996370A (en) * | 2024-04-03 | 2024-05-07 | 蜂巢能源科技股份有限公司 | Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117996370A (en) * | 2024-04-03 | 2024-05-07 | 蜂巢能源科技股份有限公司 | Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece |
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