CN117996370B - Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece - Google Patents
Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece Download PDFInfo
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- CN117996370B CN117996370B CN202410399082.5A CN202410399082A CN117996370B CN 117996370 B CN117996370 B CN 117996370B CN 202410399082 A CN202410399082 A CN 202410399082A CN 117996370 B CN117996370 B CN 117996370B
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- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 5
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- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 5
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- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 4
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 8
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Abstract
The invention relates to the technical field of batteries, and discloses a manufacturing method of a composite current collector pole piece and an evaluating method of the composite current collector pole piece, wherein two negative electrode metal foil current collector pole lugs are welded on two sides of a pole lug of a composite negative electrode current collector body through ultrasonic waves during pole piece manufacturing, the welding amplitude is 90% -100%, and the welding pressure is 0.5Mpa-1Mpa; and welding two positive metal foil current collector lugs on two sides of the lug of the composite positive current collector body through ultrasonic waves to form a composite positive current collector pole piece, wherein the welding amplitude is 30-35%, and the welding pressure is 0.3-0.8 Mpa. By controlling welding amplitude and welding pressure, the tensile bearing force of the welded composite current collector pole piece in a welding printing area can be ensured; meanwhile, the resistance of the welding area can be controlled in a proper range, and the composite current collector pole piece is ensured to have good conductivity and current collecting performance, so that the cycle and multiplying power performance of the battery are improved.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a manufacturing method of a composite current collector pole piece and an evaluation method of the composite current collector pole piece.
Background
The composite current collector has thinner thickness and lighter weight, is favorable for improving the energy density of the lithium ion battery, is in compliance with the development trend of current collector cost reduction, thinning and weight reduction, and has important significance for improving the safety, the energy density and the cycle performance of the battery.
The composite current collector comprises an intermediate polymer layer and metal layers arranged on two sides of the polymer layer, wherein the metal layers on two sides of the intermediate polymer layer cannot be conducted in the charge and discharge process due to the fact that the intermediate polymer layer is made of an insulating material. Preventing the transmission of the cell current to the electrode terminals. In order to solve the current transmission problem of the battery core, the method commonly adopted at present is to clamp a layer of electrode lug of the composite current collector by using two layers of conventional metal foil current collector electrode lugs, and weld the metal foil current collector electrode lugs on the electrode lugs of the composite current collector in an ultrasonic welding or laser welding mode.
In the prior art, when the composite current collector pole piece is manufactured, after the metal foil current collector pole lug is welded with the composite current collector pole lug, the welding effect is difficult to ensure, and the electrochemical performance of the battery is influenced.
Disclosure of Invention
In view of the above, the invention provides a method for manufacturing a composite current collector pole piece and a method for evaluating the composite current collector pole piece, so as to solve the problem that the welding effect of a metal foil current collector pole lug and a composite current collector pole lug is difficult to ensure when the composite current collector pole piece is manufactured in the prior art, and the electrochemical performance of a battery is further affected.
In a first aspect, the invention provides a method for manufacturing a composite current collector pole piece, wherein the composite current collector pole piece comprises a composite current collector body and a metal foil current collector lug, and the composite current collector body comprises a composite negative current collector body and a composite positive current collector body; the metal foil current collector tab comprises a negative metal foil current collector tab and a positive metal foil current collector tab; the manufacturing method of the composite current collector pole piece comprises the following steps:
Manufacturing a composite anode current collector body;
Two negative electrode metal foil current collector lugs are welded on two sides of the lug of the composite negative electrode current collector body through ultrasonic waves to form a composite negative electrode current collector pole piece, wherein the welding amplitude is 90% -100%, and the welding pressure is 0.5 Mpa-1 Mpa;
Manufacturing a composite positive current collector body;
and welding two positive metal foil current collector lugs on two sides of the lug of the composite positive current collector body through ultrasonic waves to form a composite positive current collector pole piece, wherein the welding amplitude is 30-35%, and the welding pressure is 0.3-0.8 Mpa.
The beneficial effects are that: when the manufacturing method is adopted to manufacture the composite current collector pole piece, the metal foil current collector pole lugs are welded on the two sides of the pole lug of the composite current collector body through ultrasonic welding, and in the process of welding the negative electrode metal foil current collector pole lug and the positive electrode metal foil current collector pole lug, the negative electrode metal foil current collector pole lug and the positive electrode metal foil current collector pole lug can be effectively welded on the pole lug of the composite current collector body through controlling welding amplitude and welding pressure, so that the tensile bearing capacity of the welded composite current collector pole piece in a welding area is ensured, and the firmness of a welding area is ensured; meanwhile, by controlling welding amplitude and welding pressure, the resistance of a welding area can be controlled in a proper range, and the composite current collector pole piece is ensured to have good conductivity and current collecting performance, so that the cycle and multiplying power performance of the battery are improved.
In an alternative embodiment, when two negative electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite negative electrode current collector body, the welding amplitude is 100% and the welding pressure is 0.6Mpa.
In an alternative embodiment, when two positive electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite positive electrode current collector body, the welding amplitude is 35% and the welding pressure is 0.4Mpa.
In an alternative embodiment, the length of the composite current collector body on the side where the metal foil current collector tab is located is L1, and the length of the welded area formed after the metal foil current collector tab is welded is L2, where 25% L1 is equal to or less than L2 is equal to or less than L1.
The beneficial effects are that: the length of the welding area between the metal foil current collector lug and the composite current collector body can be ensured, so that the welding firmness between the metal foil current collector lug and the composite current collector body is ensured, and the tensile strength of a welded printing area is improved.
In an alternative embodiment, the width W of the welding mark area formed after the welding of the metal foil current collector lugs is 3mm < W < 4.5mm.
The beneficial effects are that: the width of the welding area is controlled in a proper range, so that the influence of the too small welding area on the welding strength is avoided, meanwhile, the resistance is increased due to the too small welding area, and the welding resistance can be reduced; and the width of the welding area is moderate, so that the electrode lugs of the metal foil current collector and the electrode lugs of the composite current collector body are prevented from being damaged due to overlarge welding, and the welding quality and the stability of welding resistance are ensured.
In an alternative embodiment, fabricating a composite anode current collector body includes:
Preparing a composite negative electrode current collector;
Uniformly stirring graphite, conductive carbon black, sodium carboxymethyl cellulose and styrene-butadiene rubber emulsion in deionized water according to the mass ratio of 96.5:1.0:1.0:1.5 to form negative electrode slurry;
Coating the negative electrode slurry on a composite negative electrode current collector, and drying to obtain a composite negative electrode current collector body;
and/or, fabricating a composite positive current collector body comprising:
preparing a composite positive electrode current collector;
Mixing and uniformly stirring nickel-rich ternary layered oxide, conductive carbon black and polyvinylidene fluoride in a mass ratio of 96.8:2:1.2 in a proper amount of N-methylpyrrolidone solvent to form positive electrode slurry;
And coating the positive electrode slurry on the composite positive electrode current collector, and drying to obtain the composite positive electrode current collector body.
In an alternative embodiment, in preparing a composite current collector, the method comprises:
Preparing an insulating base film layer by adopting an insulating material, wherein the insulating material comprises at least one of polyamide, polyterephthalate, polyimide, polypropylene, polybutylene terephthalate and polycarbonate;
and respectively paving metal conductive layers on the upper surface and the lower surface of the insulating base film layer.
In an alternative embodiment, the thickness of the insulating base film layer is D 0,1μm≤D0. Ltoreq.12 μm;
and/or the thickness of the metal conductive layer is D 1,0.5μm≤D1 -3 μm.
In an alternative embodiment, the metallic conductive layer is laid on the insulating base film layer by at least one of hot pressing, mechanical rolling, bonding, vapor deposition, electroless plating.
In a second aspect, the present invention further provides a method for evaluating a composite current collector pole piece, where the composite current collector pole piece is manufactured by using the method for manufacturing a composite current collector pole piece according to any one of the above steps, and the method for evaluating a composite current collector pole piece includes:
obtaining a test sample of the composite current collector pole piece;
Placing a test sample into a testing machine, wherein one clamp of the testing machine clamps the composite current collector body of the test sample, and the other clamp of the testing machine clamps the metal foil current collector lug of the test sample;
carrying out tensile test on the test sample until the welding area of the metal foil current collector tab breaks, and recording the maximum tensile force F born by the test sample when the test sample breaks;
measuring the welding resistance of the welding area of the pole piece of the composite current collector to obtain a welding resistance R;
The larger the evaluation coefficient s=f/R is calculated, the better the welding effect between the composite current collector body and the metal foil current collector tab is.
The beneficial effects are that: when the maximum welding tension F which can be borne by the composite current collector pole piece is larger, the welding resistance S is smaller, the welding effect of the composite current collector pole piece is more ideal, the welding effect between the composite current collector body and the metal foil current collector pole lug can be intuitively evaluated through the evaluation coefficient S value, the optimal welding amplitude and welding pressure can be screened according to the evaluation coefficient S value, the composite current collector pole piece with better performance is prepared according to the optimal welding amplitude and welding pressure, and the electrochemical performance of the battery is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic view of a composite current collector pole piece fabricated by a fabrication method of a composite current collector pole piece according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a composite current collector pole piece fabricated by a method for fabricating a composite current collector pole piece according to an embodiment of the present invention when a tensile test is performed;
Fig. 3 is a schematic diagram of a composite current collector pole piece manufactured by the manufacturing method of the composite current collector pole piece according to the embodiment of the invention when resistance test is performed.
Reference numerals illustrate:
1. A composite current collector pole piece; 11. a composite current collector body; 12. metal foil current collector tab; 13. and a welding printing area.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Embodiments of the present invention are described below with reference to fig. 1 to 3.
According to an embodiment of the present invention, in one aspect, there is provided a method for manufacturing a composite current collector pole piece 1, wherein the composite current collector pole piece 1 includes a composite current collector body 11 and a metal foil current collector tab 12, and the composite current collector body 11 includes a composite negative current collector body and a composite positive current collector body; the metal foil current collector tab 12 includes a negative metal foil current collector tab and a positive metal foil current collector tab; the manufacturing method of the composite current collector pole piece 1 comprises the following steps:
Manufacturing a composite anode current collector body;
Two negative electrode metal foil current collector lugs are welded on two sides of the lug of the composite negative electrode current collector body through ultrasonic waves to form a composite negative electrode current collector pole piece, wherein the welding amplitude is 90% -100%, and the welding pressure is 0.5 Mpa-1 Mpa;
Manufacturing a composite positive current collector body;
and welding two positive metal foil current collector lugs on two sides of the lug of the composite positive current collector body through ultrasonic waves to form a composite positive current collector pole piece, wherein the welding amplitude is 30-35%, and the welding pressure is 0.3-0.8 Mpa.
When the manufacturing method is adopted to manufacture the composite current collector pole piece 1, the metal foil current collector pole lugs 12 are welded on the two sides of the pole lugs of the composite current collector body 11 through ultrasonic welding, and in the process of welding the negative electrode metal foil current collector pole lugs and the positive electrode metal foil current collector pole lugs, the negative electrode metal foil current collector pole lugs and the positive electrode metal foil current collector pole lugs can be effectively welded on the pole lugs of the composite current collector body 11 through controlling welding amplitude and welding pressure, so that the tensile bearing force of the welded composite current collector pole piece 1 in a welding area 13 is ensured, and the firmness of the welding area is ensured; meanwhile, by controlling the welding amplitude and the welding pressure, the resistance of the welding area 13 can be controlled in a proper range, and the composite current collector pole piece 1 is ensured to have good conductivity and current collecting performance, so that the cycle and the multiplying power performance of the battery are improved.
As shown in table 1, the maximum welding tension F that can be borne by the composite current collector pole piece 1 manufactured by the present application during the tensile test satisfies: f is more than or equal to 5 and less than or equal to 30N. The welding resistance R satisfies: 0.01 mΩ is less than or equal to R is less than or equal to 5m Ω. The welding resistance R is preferably in the range of 0.2mΩ less than or equal to R less than or equal to 1.1mΩ, and the battery manufactured by adopting the composite current collector pole piece 1 has low internal resistance and stable electrochemical performance, and can prolong the service life of the battery.
Alternatively, in one embodiment, when two negative electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite negative electrode current collector body, the welding amplitude is 100% and the welding pressure is 0.6Mpa. The tensile tolerance of the composite anode current collector pole piece in the welding area 13 is further improved by further optimizing the welding amplitude and the welding pressure when the anode metal foil current collector pole lug is welded; and meanwhile, the welding resistance of the welding area 13 can be further reduced, and the conductivity and the current collecting performance of the composite anode current collector pole piece are further improved.
Alternatively, in one embodiment, when two positive electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite positive electrode current collector body, the welding amplitude is 35% and the welding pressure is 0.4Mpa. The tensile bearing capacity of the composite positive current collector pole piece in the welding area 13 is further improved by further optimizing the welding amplitude and the welding pressure when the positive metal foil current collector pole lug is welded; and meanwhile, the welding resistance of the welding area 13 can be further reduced, and the conductivity and the current collecting performance of the composite positive current collector pole piece are further improved.
As shown in fig. 1, optionally, in an embodiment, the length of the composite current collector body 11 on the side where the metal foil current collector tab 12 is located is L1, the length of the welded area 13 formed after the metal foil current collector tab 12 is welded is L2, and L1 is 25% L2 is less than or equal to L1, so that the length of the welded area between the metal foil current collector tab 12 and the composite current collector body 11 can be ensured, thereby ensuring the welding firmness between the metal foil current collector tab 12 and the composite current collector body 11, and further improving the tensile strength of the welded area 13 after welding.
Alternatively, in one embodiment, as shown in FIG. 1, the width of the land 13 is W,3 mm.ltoreq.W.ltoreq.4.5 mm. By controlling the width of the welding area 13 in a proper range, the influence of the too small welding area 13 on the welding strength is avoided, and meanwhile, the resistance is increased due to the too small welding area, so that the welding resistance can be reduced; the width of the welding area 13 is moderate, and the electrode lugs of the metal foil current collector electrode lug 12 and the composite current collector body 11 are prevented from being damaged due to overlarge welding, so that the welding quality and the stability of welding resistance are ensured.
The composite current collector body 11 includes a composite current collector and an active material layer. The composite anode current collector body comprises a composite anode current collector and an anode active material layer; the composite positive electrode current collector body includes a composite positive electrode current collector and a positive electrode active material layer.
In one embodiment, fabricating a composite anode current collector body includes:
Preparing a composite negative electrode current collector;
Uniformly stirring graphite, conductive carbon black, sodium carboxymethyl cellulose and styrene-butadiene rubber emulsion in deionized water according to the mass ratio of 96.5:1.0:1.0:1.5 to form negative electrode slurry;
Coating the negative electrode slurry on a composite negative electrode current collector, and drying to obtain a composite negative electrode current collector body;
the manufacturing of the composite positive current collector body comprises the following steps:
preparing a composite positive electrode current collector;
Mixing and uniformly stirring nickel-rich ternary layered oxide, conductive carbon black and polyvinylidene fluoride in a mass ratio of 96.8:2:1.2 in a proper amount of N-methylpyrrolidone solvent to form positive electrode slurry;
And coating the positive electrode slurry on the composite positive electrode current collector, and drying to obtain the composite positive electrode current collector body.
Alternatively, in other embodiments, the active material in the negative electrode slurry may also be at least one of carbon, silicon oxygen, silicon carbon, and the like. The active material in the positive electrode slurry may be at least one of LiMPO 4 (M may be at least one of Fe, mn, co), ternary LiMn1-x-yNixCoyO2(0<x<1,0<y<1,0<x+y<1)、LiMn2O4, and the like.
In one embodiment, in preparing a composite current collector, comprising:
Preparing an insulating base film layer by adopting an insulating material, wherein the insulating material comprises at least one of polyamide, polyterephthalate, polyimide, polypropylene, polybutylene terephthalate and polycarbonate;
And respectively paving metal conductive layers on the upper surface and the lower surface of the insulating base film layer. The composite current collector can obviously reduce the material cost, weight and thickness of the current collector by replacing part of metal materials with polymer insulating materials.
Optionally, in one embodiment, the thickness of the insulating base film layer is D 0,1μm≤D0. Ltoreq.12 μm;
The thickness of the metal conductive layer is D 1,0.5μm≤D1 -3 μm.
In one embodiment, the metal conductive layer may be laid on the insulating base film layer by at least one of hot pressing, mechanical rolling, bonding, vapor deposition, electroless plating.
According to an embodiment of the present invention, on the other hand, there is also provided a method for evaluating a composite current collector pole piece 1, where the composite current collector pole piece 1 is manufactured by using the method for manufacturing a composite current collector pole piece 1 described above, and the method for evaluating a composite current collector pole piece 1 includes:
obtaining a test sample of the composite current collector pole piece 1;
placing the test sample into a testing machine, wherein one clamp of the testing machine clamps the composite current collector body 11 of the test sample, and the other clamp of the testing machine clamps the metal foil current collector tab 12 of the test sample;
Carrying out tensile test on the test sample until the welding area 13 of the metal foil current collector tab 12 breaks, and recording the maximum tensile force F born by the test sample when the test sample breaks;
measuring the welding resistance of the welding area 13 of the composite current collector pole piece 1 to obtain a welding resistance R;
the larger the evaluation coefficient s=f/R, the better the welding effect between the composite current collector body 11 and the metal foil current collector tab 12 is calculated.
When the maximum welding tension F which can be borne by the composite current collector pole piece 1 is larger, and the welding resistance S is smaller, the welding effect of the composite current collector pole piece 1 is more ideal, the welding effect between the composite current collector body 11 and the metal foil current collector pole lug 12 can be intuitively evaluated through the evaluation coefficient S value, the optimal welding amplitude and welding pressure can be screened according to the evaluation coefficient S value, the composite current collector pole piece 1 with better performance is prepared according to the optimal welding amplitude and welding pressure, and meanwhile, the electrochemical performance of a battery is improved.
Specifically, in this embodiment, when the composite current collector pole piece 1 is subjected to tensile test, the welded composite current collector pole piece 1 is punched and cut into test samples with a width of 15mm and a length of 100mm, then the test samples are mounted in an upper clamp and a lower clamp of an electronic universal tester, the initial length is set to be 50mm, the tensile test is performed at a tensile rate of 10mm/min until the tensile is stopped when the welding area 13 of the test sample breaks, and the maximum welding tensile force F born by the test sample when the test sample breaks is recorded.
In one embodiment, when a welding resistance test is performed, a direct current resistance meter is used for measuring the welding resistance, a composite current collector pole piece 1 is cut to form a test sample with the width of 15mm and the welding width of 3mm, the test sample is horizontally placed on a test bench, test chucks of the direct current resistance meter are fixed on two sides of the welding mark, and the welding resistance R is recorded under different currents.
The following describes the manufacturing process of the composite current collector pole piece 1 with reference to specific embodiments:
Example 1
Preparation of a composite negative electrode current collector:
and selecting an insulating base film layer, and paving copper conducting layers on the upper surface and the lower surface of the insulating base film layer through a magnetron sputtering process to obtain the composite copper current collector body which is used as the negative electrode of the battery.
The preparation process of the composite negative current collector pole piece comprises the following steps:
Uniformly stirring graphite, conductive carbon black, sodium carboxymethylcellulose (CMC) and styrene-butadiene rubber emulsion (SBR) in deionized water according to the mass ratio of 96.5:1.0:1.0:1.5 to form negative electrode slurry; and coating the negative electrode slurry on a composite copper current collector body, and drying to obtain the composite negative electrode current collector pole piece.
The preparation process of the composite positive electrode current collector body is as follows:
And selecting an insulating base film layer, placing the insulating base film layer in a vacuum plating chamber, and depositing aluminum metal layers on the upper and lower surfaces of the insulating base film layer in a high-temperature evaporation mode to form a composite aluminum current collector body which is used as a positive electrode of the battery.
The preparation process of the composite positive current collector pole piece is as follows:
Mixing and stirring nickel-rich ternary layered oxide (LiNi0.8Co0.1Mn0.1O2 (NCM 811)), conductive carbon black and polyvinylidene fluoride (PVDF) in a mass ratio of 96.8:2:1.2 in a proper amount of N-methylpyrrolidone (NMP) solvent uniformly to form positive electrode slurry; and coating the positive electrode slurry on a positive electrode current collector, and drying to obtain the composite positive electrode current collector body.
The welding steps of the composite negative current collector pole piece and the composite positive current collector pole piece are as follows:
under the action of an ultrasonic welding head, welding amplitude of 95% and welding pressure of 0.55 Mpa are selected, and copper metal foil current collector lugs are welded on the upper surface and the lower surface of a pole piece of the composite negative current collector body; under the action of an ultrasonic welding head, welding amplitude is selected to be 35%, welding pressure is 0.3 Mpa, and aluminum metal foil current collector lugs are welded on the upper surface and the lower surface of the lugs of the composite positive current collector pole piece.
Example 2
This embodiment differs from embodiment 1 in that:
Selecting 100% of welding amplitude and 0.55 Mpa% of welding pressure, and welding copper metal foil current collector lugs on the upper surface and the lower surface of the pole piece of the composite negative current collector body; under the action of an ultrasonic welding head, welding amplitude is selected to be 35%, welding pressure is 0.3 Mpa, and aluminum metal foil current collector lugs are welded on the upper surface and the lower surface of the lugs of the composite positive current collector pole piece.
Example 3
This embodiment differs from embodiment 1 in that:
Selecting 100% of welding amplitude and 0.6 Mpa of welding pressure, and welding copper metal foil current collector lugs on the upper surface and the lower surface of the pole piece of the composite negative current collector body; under the action of an ultrasonic welding head, welding amplitude is selected to be 35%, welding pressure is 0.3 Mpa, and aluminum metal foil current collector lugs are welded on the upper surface and the lower surface of the lugs of the composite positive current collector pole piece.
Example 4
This embodiment differs from embodiment 1 in that:
Selecting 100% of welding amplitude and 0.6 Mpa of welding pressure, and welding copper metal foil current collector lugs on the upper surface and the lower surface of the pole piece of the composite negative current collector body; under the action of an ultrasonic welding head, welding amplitude is selected to be 35%, welding pressure is 0.4 Mpa, and aluminum metal foil current collector lugs are welded on the upper surface and the lower surface of the lugs of the composite positive current collector pole piece.
Example 5
This embodiment differs from embodiment 1 in that:
Selecting 100% of welding amplitude and 0.6 Mpa of welding pressure, and welding copper metal foil current collector lugs on the upper surface and the lower surface of the pole piece of the composite negative current collector body; under the action of an ultrasonic welding head, welding amplitude is selected to be 30%, welding pressure is 0.4 Mpa, and aluminum metal foil current collector lugs are welded on the upper surface and the lower surface of the lugs of the composite positive current collector pole piece.
The composite current collector electrode sheet 1 fabricated in examples 1 to 5 was subjected to preparation and performance test of a secondary battery according to the following procedures, respectively:
Sequentially stacking the composite positive current collector pole piece, the diaphragm and the composite negative current collector pole piece in sequence to form a pole group, assembling the pole group into a battery shell, then injecting electrolyte into the shell and sealing to obtain the lithium ion secondary battery.
The test steps of the cycle performance of the battery are as follows:
1. constant-current charging is carried out to the voltage of 4.2V at the rate of 1/3C, and then constant-voltage charging is carried out until the current is less than or equal to 0.05C;
2. constant-current discharge is carried out to 2.5V at the 1/3C multiplying power;
3. recording a first discharge capacity C 0;
4. repeating the steps 1 to 3 for 1000 times, and recording the discharge capacity C 1 of 1000 times of cycles;
5. The discharge capacity retention (%) =c 1/C0 ×100% after 1000 cycles was calculated.
The rate performance test steps of the battery are as follows:
1. constant-current charging is carried out to the voltage of 4.2V at the rate of 1/3C, and then constant-voltage charging is carried out until the current is less than or equal to 0.05C;
2. constant-current discharge is carried out to 2.5V at the 1/3C multiplying power;
3. recording the discharge capacity C 2 of the 1/3C multiplying power;
4. constant-current charging is carried out to the voltage of 4.2V at the rate of 1/3C, and then constant-voltage charging is carried out until the current is less than or equal to 0.05C;
5. constant-current discharge is carried out to 2.5V at the 3C multiplying power;
6. Recording discharge capacity C 3 of 3C multiplying power;
7. Battery 3C rate capacity retention (%) =c 3/C2 ×100% was calculated.
The test results of the welding tension F, welding resistance R, and the cycle 1000-turn capacity retention rate and 3C-rate capacity retention rate of the battery of the composite current collector electrode sheet 1 are shown in table 1.
TABLE 1
As can be seen from table 1, when welding the negative electrode metal foil current collector tab, the welding amplitude was 100%, the welding pressure was 0.6Mpa, and when welding the positive electrode metal foil current collector tab, the welding amplitude was 35%, the welding pressure was 0.4Mpa, that is, the evaluation coefficient S value of the composite current collector pole piece 1 manufactured in example 4 was the largest, and the welding effect was the best; the battery fabricated by the composite current collector electrode sheet 1 in example 4 was optimal in terms of 1000-cycle capacity retention and 3C rate capacity retention.
As shown in table 1, the maximum welding tension F that can be borne by the composite current collector pole piece 1 manufactured by the present application during the tensile test satisfies: f is more than or equal to 5 and less than or equal to 30N. The welding resistance R satisfies: 0.01 mΩ is less than or equal to R is less than or equal to 5m Ω. The welding tension and welding resistance of the composite current collector satisfy the following conditions: S=F/R, 1N/mΩ.ltoreq.S.ltoreq.3000N/mΩ. When the welding tension is larger, the welding resistance is smaller, the S value is larger, and the welding effect of the composite current collector pole piece 1 is more ideal. The excellent welding effect can ensure that the composite current collector pole piece 1 has good electric conduction and current collection performance, thereby improving the cycle and rate performance of the battery.
Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope of the invention as defined by the appended claims.
Claims (7)
1. The manufacturing method of the composite current collector pole piece is characterized in that the composite current collector pole piece comprises a composite current collector body and a metal foil current collector lug, and the composite current collector body comprises a composite negative current collector body and a composite positive current collector body; the metal foil current collector tab comprises a negative metal foil current collector tab and a positive metal foil current collector tab; the manufacturing method of the composite current collector pole piece comprises the following steps:
Manufacturing a composite anode current collector body;
two negative electrode metal foil current collector lugs are welded on two sides of the lug of the composite negative electrode current collector body through ultrasonic waves to form a composite negative electrode current collector pole piece, wherein the welding amplitude is 90% -100%, and the welding pressure is 0.5Mpa-1Mpa;
Manufacturing a composite positive current collector body;
two positive metal foil current collector lugs are welded on two sides of the lug of the composite positive current collector body through ultrasonic waves to form a composite positive current collector pole piece, wherein the welding amplitude is 30% -35%, and the welding pressure is 0.3Mpa-0.8Mpa;
the width of a welding printing area formed after welding the lugs of the metal foil current collector is W, and W is more than or equal to 3mm and less than or equal to 4.5mm;
the length of the composite current collector body at the side where the metal foil current collector lug is positioned is L1, and the length of a welding printing area formed after the metal foil current collector lug is welded is L2, wherein L1 is more than or equal to 25% and L2 is less than or equal to L1;
the composite current collector body comprises a composite current collector and an active material layer, and the composite current collector comprises an insulating base film layer and a metal conductive layer;
The thickness of the insulating base film layer is D 0,1μm≤D0 -12 mu m;
the thickness of the metal conductive layer is D 1,0.5μm≤D1 -3 mu m.
2. The method of manufacturing a composite current collector electrode sheet according to claim 1, wherein when two negative electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite negative electrode current collector body, the welding amplitude is 100%, and the welding pressure is 0.6Mpa.
3. The method of manufacturing a composite current collector sheet according to claim 1 or 2, wherein when two positive electrode metal foil current collector tabs are ultrasonically welded to both sides of the tab of the composite positive electrode current collector body, the welding amplitude is 35%, and the welding pressure is 0.4Mpa.
4. The method of manufacturing a composite current collector sheet according to claim 1 or 2, wherein manufacturing a composite negative current collector body comprises:
Preparing a composite negative electrode current collector;
Uniformly stirring graphite, conductive carbon black, sodium carboxymethyl cellulose and styrene-butadiene rubber emulsion in deionized water according to the mass ratio of 96.5:1.0:1.0:1.5 to form negative electrode slurry;
Coating the negative electrode slurry on a composite negative electrode current collector, and drying to obtain a composite negative electrode current collector body;
the manufacturing of the composite positive current collector body comprises the following steps:
preparing a composite positive electrode current collector;
Mixing and uniformly stirring nickel-rich ternary layered oxide, conductive carbon black and polyvinylidene fluoride in a mass ratio of 96.8:2:1.2 in a proper amount of N-methylpyrrolidone solvent to form positive electrode slurry;
And coating the positive electrode slurry on the composite positive electrode current collector, and drying to obtain the composite positive electrode current collector body.
5. The method for manufacturing a composite current collector sheet according to claim 1 or 2, wherein when manufacturing a composite current collector, comprising:
Preparing an insulating base film layer by adopting an insulating material, wherein the insulating material comprises at least one of polyamide, polyterephthalate, polyimide, polypropylene and polycarbonate;
and respectively paving metal conductive layers on the upper surface and the lower surface of the insulating base film layer.
6. The method of claim 5, wherein the metal conductive layer is laid on the insulating base film layer by at least one of hot pressing, mechanical rolling, bonding, vapor deposition, electroless plating.
7. The method for evaluating the composite current collector pole piece is characterized in that the composite current collector pole piece is manufactured by adopting the manufacturing method of the composite current collector pole piece according to any one of claims 1 to 6, and the method for evaluating the composite current collector pole piece comprises the following steps:
obtaining a test sample of the composite current collector pole piece;
Placing a test sample into a testing machine, wherein one clamp of the testing machine clamps the composite current collector body of the test sample, and the other clamp of the testing machine clamps the metal foil current collector lug of the test sample;
carrying out tensile test on the test sample until the welding area of the metal foil current collector tab breaks, and recording the maximum tensile force F born by the test sample when the test sample breaks;
measuring the welding resistance of the welding area of the pole piece of the composite current collector to obtain a welding resistance R;
The larger the evaluation coefficient s=f/R is calculated, the better the welding effect between the composite current collector body and the metal foil current collector tab is.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410399082.5A CN117996370B (en) | 2024-04-03 | Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece |
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| CN202410399082.5A CN117996370B (en) | 2024-04-03 | Manufacturing method of composite current collector pole piece and evaluating method of composite current collector pole piece |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114068862A (en) * | 2021-11-11 | 2022-02-18 | 苏州达牛新能源科技有限公司 | Battery pole piece based on composite current collector and preparation method thereof |
| CN114734641A (en) * | 2022-03-18 | 2022-07-12 | 江阴纳力新材料科技有限公司 | Pole lug welding device |
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114068862A (en) * | 2021-11-11 | 2022-02-18 | 苏州达牛新能源科技有限公司 | Battery pole piece based on composite current collector and preparation method thereof |
| CN114734641A (en) * | 2022-03-18 | 2022-07-12 | 江阴纳力新材料科技有限公司 | Pole lug welding device |
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