Roll core using composite current collector and lithium battery

Abstract

The invention discloses a roll core using a composite current collector and a lithium battery. The battery comprises a negative plate, a positive plate, a diaphragm, foils, a connection position of composite foils, the pole plate, the composite foils, a coating material, a welding line width, a distance between the composite foils and a welding position, a distance between the foils and the welding position, a foil width, a blank area of the composite foils, and a distance between the foils and the coating material. According to the invention, the composite foil is applied to the large cylindrical battery, so that the safety performance problem of the battery is solved, and the energy density of the battery is improved; and the composite current collector is applied to a large cylindrical battery, so that the problem that the composite current collector cannot be subjected to laser welding on a current collecting plate is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and in particular to a winding core and a lithium battery using a composite current collector. Background Art

[0002] With the popularity of battery cars and two-wheeled vehicles, people are paying more and more attention to the safety of lithium batteries. At present, compared with traditional current collector materials, composite current collectors have been greatly developed and applied. Composite current collectors are sandwich structures, with PP or PET materials in the middle and a layer of copper or aluminum electroplated on both sides. When an internal short circuit occurs in the battery, it can be immediately melted to prevent the battery from continuing to react and ensure the safety of the battery.

[0003] At present, most large cylindrical batteries have full-ear structures, and the two sides of the core are flattened or cut and stacked, and then laser welded with the collector plate. However, due to the sandwich structure of the composite current collector, the composite current collector is not suitable for this welding method. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a winding core and a lithium battery using a composite current collector.

[0005] The present invention proposes a winding core using a composite current collector, comprising a negative electrode sheet, a positive electrode sheet, a separator, a foil, a composite foil and a foil connection position, a pole sheet, a composite foil, a coating material, a welding line width, a distance between the composite foil and the welding position, a distance between the foil and the welding position, a foil width, a blank area of ​​the composite foil, and a distance between the foil and the coating material;

[0006] The production steps are as follows:

[0007] S1: Negative electrode slurry: Mix graphite and other materials to form slurry;

[0008] S2: Negative electrode coating: coating the slurry on both sides of the negative electrode composite foil, and forming the negative electrode coating material after the slurry is dried, and the distance between the coating material and the edge of the composite foil is E;

[0009] S3: Negative electrode rolling: rolling the negative electrode sheet to the thickness required by the process;

[0010] S4: Negative electrode cutting: Cut the negative electrode sheet into the required width and make it into electrode sheets;

[0011] S5: Negative electrode connection: Negative electrode foils are arranged on both sides of the negative electrode composite foil, and the distance between the negative electrode foils and the negative electrode coating material is F; the composite foils and the foils are connected in area A, and the connection method can be ultrasonic roll welding or riveting; after the connection is completed, a negative electrode sheet is formed;

[0012] S6: Repeat the above steps to make a positive electrode sheet, and finally form a positive electrode sheet;

[0013] S7: Winding: Wind the prepared negative electrode sheet, positive electrode sheet and separator to finally make a winding core.

[0014] A lithium battery comprising the following steps:

[0015] S1: Lithium iron phosphate material is coated on the positive electrode composite foil, and the slurry is dried and then rolled and cut to obtain a pole piece; the coating width of the pole piece is 97.5 mm, and the width of the empty foil area of ​​the composite foil is 4.5 mm;

[0016] S2: coating the graphite material on the negative electrode foil, drying the slurry, rolling and slitting to obtain the electrode; the coating width of the electrode is 100.5 mm, and the width of the empty foil area of ​​the composite foil is 4.5 mm;

[0017] S3: Positive electrode welding foil: 12μm aluminum foil with a width of 10mm is used. It is welded on both sides of the composite foil and connected by ultrasonic roll welding. The aluminum foil is 0.5mm away from the material area and the roll welding head width is 3mm.

[0018] S4: Negative electrode welding foil: Use 6μm copper foil, 8.5mm width, weld on both sides of the composite foil, use ultrasonic roll welding to connect, the copper foil is 0.5mm away from the material area, and the roll welding head width is 3mm;

[0019] S5: Winding: The separator, the positive electrode sheet and the negative electrode sheet are wound;

[0020] S6: core flattening: flattening the positive and negative electrode foils of the core;

[0021] S7: Weld the positive and negative current collectors to the positive and negative electrodes of the winding core respectively, and wrap the positive electrode with a high-temperature tape for one week;

[0022] S8: Enter the shell;

[0023] S9: Bottom penetration welding: laser penetration welding of the steel shell and the negative electrode collector of the core;

[0024] S10: Steel shell rolling groove;

[0025] S11: Liquid injection: Liquid injection process for the battery cell;

[0026] S12: Cap welding: laser welding the core positive electrode current collector and the cap;

[0027] S13: Put the cap on and seal;

[0028] S14: Cleaning, oiling, heat shrinking and coding the battery.

[0029] Preferably, the winding core, the positive and negative electrode sheets can both use composite foils, or one can use composite foils and the other can use traditional foils; the composite foil is a prior art and will not be described; the material of the foil matches the composite foil: when the composite foil is a composite aluminum foil, the foil is made of pure aluminum with a thickness of 6-12 μm; when the composite foil is a composite copper foil, the foil is made of pure aluminum with a thickness of 4-8 μm; the connection between the foil and the composite foil can be ultrasonic roll welding, riveting, conductive adhesive bonding, etc.; the foil can be set on one side of the composite foil or on both sides, and the width A of the connecting line has different size definitions according to different connection methods:

[0030] Ultrasonic roll welding: A = 3-5mm, the width dimension is mainly defined according to the welding width;

[0031] Riveting: A = 2-4mm;

[0032] Conductive adhesive: A = 3-5mm;

[0033] The blank area E of the composite foil has a size of E=A+B+C+F, wherein the size of B is 0-1mm, the size of C is 0-1mm, and the size of F is 0.5-1mm;

[0034] The width D of the foil material, the width of the positive electrode foil material is D=A+B+C+6-8mm; the width of the negative electrode foil material is D=A+B+C+4-6mm.

[0035] In the present invention, the composite foil is applied to large cylindrical batteries to solve the safety performance problem of the batteries and improve the battery energy density; the battery material cost is reduced, and the composite current collector is applied to large cylindrical batteries to solve the problem that the composite current collector cannot be laser welded to the current collector plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of the winding core in the present invention;

[0037] Figure 2 For the present invention Figure 1 Schematic diagram of the local structure;

[0038] Figure 3 For the present invention Figure 2 Schematic diagram of the local structure.

[0039] In the figure: 1, negative electrode sheet; 2, positive electrode sheet; 3, diaphragm; 110, foil material; 120, composite foil material and foil material connection position; 130, electrode sheet; 131, composite foil material; 132, coating material. DETAILED DESCRIPTION

[0040] The present invention will be further explained below in conjunction with specific embodiments.

[0041] Example

[0042] refer to Figure 1-Figure 3 As shown, the present invention proposes a roll core using a composite current collector, including a negative electrode sheet 1, a positive electrode sheet 2, a separator 3, a foil 110, a composite foil and a foil connection position 120, a pole sheet 130, a composite foil 131, a coating material 132, a welding line width A, a distance B between the composite foil and the welding position, a distance C between the foil and the welding position, a foil width D, a blank area E of the composite foil, and a distance F between the foil and the coating material;

[0043] The production steps are as follows:

[0044] S1: Negative electrode slurry: Mix graphite and other materials to form slurry;

[0045] S2: Negative electrode coating: coating the slurry on both sides of the negative electrode composite foil 131, and forming the negative electrode coating material 132 after the slurry is dried. The distance between the coating material 132 and the edge of the composite foil 131 is E;

[0046] S3: negative electrode rolling: rolling the negative electrode sheet 1 to a thickness required by the process;

[0047] S4: Negative electrode cutting: cutting the negative electrode sheet 1 into a width required by the process to produce a negative electrode sheet 130;

[0048] S5: Negative electrode connection: Negative electrode foil 110 is arranged on both sides of negative electrode composite foil 131, and the distance between negative electrode foil 110 and negative electrode coating material 132 is F; composite foil 131 and foil 110 are connected in region A, and the connection method can be ultrasonic roll welding or riveting; after the connection is completed, a negative electrode sheet 1 is formed;

[0049] S6: Repeat the above steps to make the positive electrode sheet 2, and finally form the positive electrode sheet 2;

[0050] S7: Winding: Wind the prepared negative electrode sheet 1, positive electrode sheet 2, and separator 3 to finally make a winding core.

[0051] A lithium battery comprising the following steps:

[0052] S1: Lithium iron phosphate material is coated on the positive electrode composite foil 131, and the slurry is dried and then rolled and cut to obtain the electrode 130; the coating width of the electrode 130 is 97.5 mm, and the width of the empty foil area of ​​the composite foil 131 is 4.5 mm;

[0053] S2: coating the graphite material on the negative electrode foil 110, and performing rolling and slitting steps after drying the slurry to obtain the electrode piece 130; the coating width of the electrode piece 130 is 100.5 mm, and the width of the empty foil area of ​​the composite foil 131 is 4.5 mm;

[0054] S3: Positive electrode sheet 2 welding foil 110: Use 12μm aluminum foil with a width of 10mm, weld on both sides of the composite foil 131, and use ultrasonic roll welding to connect. The aluminum foil is 0.5mm away from the material area, and the width of the roll welding head is 3mm;

[0055] S4: welding the negative electrode sheet 1 foil 110: using 6μm copper foil with a width of 8.5mm, welding on both sides of the composite foil 131, using ultrasonic roll welding to connect, the copper foil is 0.5mm away from the material area, and the roll welding head width is 3mm;

[0056] S5: Winding: The separator 3, the positive electrode sheet 2, and the negative electrode sheet 1 are wound;

[0057] S6: Flattening the core: Flattening the core positive and negative electrode foils 110;

[0058] S7: Weld the positive and negative current collectors to the positive and negative electrodes of the winding core respectively, and wrap the positive electrode with a high-temperature tape for one week;

[0059] S8: Enter the shell;

[0060] S9: Bottom penetration welding: laser penetration welding of the steel shell and the negative electrode collector of the core;

[0061] S10: Steel shell rolling groove;

[0062] S11: Liquid injection: Liquid injection process for the battery cell;

[0063] S12: Cap welding: laser welding the core positive electrode current collector and the cap;

[0064] S13: Put the cap on and seal;

[0065] S14: Cleaning, oiling, heat shrinking and coding the battery.

[0066] The winding core, positive and negative electrode sheets can both use the composite foil 131, or one uses the composite foil 131 and the other uses the traditional foil 110; the composite foil 131 is a prior art and will not be described again; the material of the foil 110 matches the composite foil 131: when the composite foil 131 is a composite aluminum foil, the foil 110 is made of pure aluminum with a thickness of 6-12μm; when the composite foil 131 is a composite copper foil, the foil 110 is made of pure aluminum with a thickness of 4-8μm; the connection method of the foil 110 and the composite foil 131 can be ultrasonic rolling welding, riveting, conductive adhesive bonding, etc.; the foil 110 can be set on one side of the composite foil 131, or on both sides, and the width A of the connecting line has different size definitions according to different connection methods:

[0067] Ultrasonic roll welding: A = 3-5mm, the width dimension is mainly defined according to the welding width;

[0068] Riveting: A = 2-4mm;

[0069] Conductive adhesive: A = 3-5mm;

[0070] The blank area E of the composite foil 131 has a size of E=A+B+C+F, wherein the size of B is 0-1mm, the size of C is 0-1mm, and the size of F is 0.5-1mm;

[0071] The width D of the foil material 110 is D=A+B+C+6-8 mm for the positive electrode foil material 110 and D=A+B+C+4-6 mm for the negative electrode foil material 110 .

[0072] In this embodiment, the battery adopts a steel shell structure, and may also adopt an aluminum shell structure, which will not be described in detail here.

[0073] In this embodiment, the weight of the battery is greatly reduced due to the use of the composite foil 131, from the original weight of 473.8g to the current weight of 454.7g, and the energy density is increased by about 4.5%. At the same time, the safety performance tests such as the needle puncture test, the short circuit test, and the thermal runaway test can all be carried out without fire or explosion, and the safety performance of the battery is guaranteed.

[0074] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A winding core using a composite current collector, characterized in that: It includes a negative electrode sheet (1), a positive electrode sheet (2), a separator (3), a foil (110), a composite foil and a foil connection position (120), a pole sheet (130), a composite foil (131), a coating material (132), a welding line width (A), a distance between the composite foil and the welding position (B), a distance between the foil and the welding position (C), a foil width (D), a blank area of ​​the composite foil (E), and a distance between the foil and the coating material (F); The production steps are as follows: S1: Negative electrode slurry: Mix graphite and other materials to form slurry; S2: negative electrode coating: coating the slurry on both sides of the negative electrode composite foil (131), and forming a negative electrode coating material (132) after the slurry is dried. The distance between the coating material (132) and the edge of the composite foil (131) is E; S3: negative electrode rolling: rolling the negative electrode sheet (1) to a thickness required by the process; S4: Negative electrode cutting: cutting the negative electrode sheet (1) into a width required by the process to produce electrode sheets (130); S5: negative electrode connection: negative electrode foils (110) are arranged on both sides of the negative electrode composite foil (131), and the distance between the negative electrode foils (110) and the negative electrode coating material (132) is F; the composite foil (131) and the foil (110) are connected in region A, and the connection method can be ultrasonic rolling welding or riveting; after the connection is completed, a negative electrode sheet (1) is formed; S6: Repeat the above steps to make the positive electrode sheet (2), and finally form the positive electrode sheet (2); S7: Winding: Winding the prepared negative electrode sheet (1), positive electrode sheet (2), and separator (3) to finally form a winding core.

2. A lithium battery according to claim 1, characterized in that: The following steps are involved: S1: coating a lithium iron phosphate material on a positive electrode composite foil (131), drying the slurry, and then rolling and slitting to obtain a pole piece (130); the coating width of the pole piece (130) is 97.5 mm, and the width of the empty foil area of ​​the composite foil (131) is 4.5 mm; S2: coating the graphite material on the negative electrode foil (110), drying the slurry, and then rolling and slitting to obtain the electrode piece (130); the coating width of the electrode piece (130) is 100.5 mm, and the width of the empty foil area of ​​the composite foil (131) is 4.5 mm; S3: Positive electrode sheet (2) welding foil (110): Use 12 μm aluminum foil with a width of 10 mm, weld on both sides of the composite foil (131), and use ultrasonic roll welding to connect. The aluminum foil is 0.5 mm away from the material area, and the width of the roll welding head is 3 mm; S4: negative electrode sheet (1) welding foil (110): use 6μm copper foil, width 8.5mm, welded on both sides of the composite foil (131), connected by ultrasonic roll welding, the copper foil is 0.5mm away from the material area, and the roll welding head width is 3mm; S5: Winding: The separator (3), the positive electrode sheet (2), and the negative electrode sheet (1) are wound; S6: rolling the core flat: rolling the core positive and negative electrode foils (110) flat; S7: Weld the positive and negative current collectors to the positive and negative electrodes of the winding core respectively, and wrap the positive electrode with a high-temperature tape for one week; S8: Enter the shell; S9: Bottom penetration welding: laser penetration welding of the steel shell and the negative electrode collector of the core; S10: Steel shell rolling groove; S11: Liquid injection: Liquid injection process for the battery cell; S12: Cap welding: laser welding the core positive electrode current collector and the cap; S13: Close the cap and seal; S14: Cleaning, oiling, heat shrinking and coding the battery.

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