CN115101724A - Laser in-situ alloying method for enhancing bonding strength of tin negative active material and copper current collector of lithium ion battery - Google Patents
Laser in-situ alloying method for enhancing bonding strength of tin negative active material and copper current collector of lithium ion battery Download PDFInfo
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- CN115101724A CN115101724A CN202210756067.2A CN202210756067A CN115101724A CN 115101724 A CN115101724 A CN 115101724A CN 202210756067 A CN202210756067 A CN 202210756067A CN 115101724 A CN115101724 A CN 115101724A
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- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- 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
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- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
- H01M4/387—Tin or alloys based on tin
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- 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
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- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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Abstract
The invention discloses a laser in-situ alloying method for enhancing the bonding strength of a tin negative active material and a copper current collector of a lithium ion battery, which utilizes laser to carry out in-situ alloying treatment on the interface bonding position of the copper current collector and the tin negative active material to generate copper-tin alloy, wherein the tin-copper alloy formed in situ by the laser can provide an interlocking interface between an active material and the copper current collector and can inhibit the tin active material from falling off from the copper current collector; in addition, the oxide of the surface layer and the inactive substances such as Cu of the bottom layer can play a role of buffering, and the volume expansion of Sn in the repeated charging/discharging process is relieved, so that good cycle performance is obtained.
Description
Technical Field
The invention relates to a preparation method of an electrode material of a lithium ion battery, in particular to a laser in-situ alloying method for enhancing the bonding strength of a tin negative electrode active substance and a copper current collector of the lithium ion battery.
Background
The lithium ion battery has the advantages of high voltage, high energy density, good safety, light weight, small self-discharge, long cycle life, no memory effect, no pollution and the like, thereby being widely concerned by the world. Lithium ion battery electrode materials have also become a hot spot for worldwide battery industry research. Graphite is a negative electrode material of lithium ion batteries which are commercialized at present, and has good cycle performance. However, the graphite has low capacity, the electrode potential after lithium storage is similar to that of metallic lithium, and when the battery is overcharged, metallic lithium is easily precipitated on the surface of the carbon electrode, and dendrite is formed to cause short circuit.
Tin-based materials are considered to be one of the candidates for a potential replacement for carbon negative electrode materials because of their high capacity, good processability, good conductivity, no problem of solvent co-intercalation, rapid charge and discharge capability, and the like. However, the reversible generation and decomposition of Li-Sn alloy is accompanied by a large volume change, which easily causes pulverization of tin particles, causing the active material to fall off from the current collector, resulting in poor cycle life of tin-based materials. Meanwhile, when the tin particles are exposed in the electrolyte, an unstable SEI film is formed on the tin surface, and the cycle performance of the electrode material is reduced.
Therefore, if the problems of pulverization, conductivity, unstable SEI formation and the like of the tin cathode in the lithium intercalation and deintercalation process can be solved, the application of the tin cathode in the fields of electronic products and new energy automobiles is paved, and the improvement of the life and the environment of people is facilitated. This is the biggest problem that tin-based materials need to overcome.
Disclosure of Invention
In order to make up for the defects of the prior art, the invention aims to provide a laser in-situ alloying method for enhancing the bonding strength of a tin negative electrode active material and a copper current collector of a lithium ion battery, so as to relieve the phenomenon that the tin negative electrode material is separated due to poor bonding of the active material and the current collector caused by volume expansion in the charging and discharging processes, and improve the structural stability and the cycle performance of the tin negative electrode.
The technical scheme of the invention is as follows:
a laser in-situ alloying method for enhancing the bonding strength of tin cathode active materials and a copper current collector of a lithium ion battery comprises the following steps:
(1) preparation work in advance: vacuum drying the tin negative pole piece (120 ℃, 6h) for later use; selecting a small tin negative pole piece sample for preliminary exploration testing, and observing the depth of the laser ablated pole piece through a light mirror or a scanning electron microscope so as to determine the power and the scanning speed of the laser;
the tin negative pole piece is prepared by the procedures of material mixing, pulping, coating, drying, rolling and the like; the negative pole piece has two layers, the upper layer is a tin active substance, and the lower layer is a copper current collector; the tin active material layer is about 90 μm thick, and the copper current collector is about 10 μm thick;
the preliminary exploration test adopts a control variable method for testing, and is specifically divided into two types: 1) controlling the scanning speed to be constant, and carrying out pole piece ablation by increasing or decreasing the laser power so as to determine a proper laser power parameter; 2) when a certain power of the laser is appropriate, the pole pieces are ablated at different scanning speeds to obtain related test parameters;
the selected laser is a femtosecond laser, and the laser power range is 0-50W; the laser power is determined to be 10W through preliminary exploration test, and the laser scanning speed is 15 mm/s;
(2) pasting the tin negative pole piece dried in the step (1) on a working table, and filling inert gas Ar in a working space; according to the laser power and the laser scanning speed determined in the step (1), setting the scanning mode of the laser to be # -shaped scanning (preferably, the scanning interval is 200 mu m), and carrying out laser in-situ alloying treatment on the tin cathode pole piece;
in the laser in-situ alloying process, the tin atoms and the copper atoms are mutually permeated and combined to form copper-tin alloy;
the laser generates copper-tin alloy in situ at the interface combination position of the tin cathode active material and the copper current collector, and the specific reaction equation is as follows:
(3) carrying out electrochemical performance test on the tin negative pole piece subjected to the laser in-situ alloying treatment in the step (2);
before the electrochemical performance test, drying, slicing, weighing and assembling the tin negative pole piece; the specific assembly process is as follows:
taking a metal lithium sheet as a counter electrode, taking a tin cathode material subjected to laser in-situ alloying treatment as a cathode, selecting a polypropylene microporous diaphragm (Celgard2500), and adopting 1mol L of a porous diaphragm -1 A half cell is assembled by taking a mixed solution of ethylene carbonate and dimethyl carbonate (volume ratio is 1:1) of lithium hexafluorophosphate as an electrolyte;
the installation environment of the half cell requires assembly in an argon glove box;
the internal material of the half battery comprises a positive electrode shell, a positive electrode plate, electrolyte, a diaphragm, a lithium plate, foamed nickel, a negative electrode shell and a sealing rubber ring.
The invention has the beneficial effects that:
the laser technology is adopted to carry out in-situ alloying treatment on the interface of the tin cathode active substance and the copper current collector to generate copper-tin alloy, thereby enhancing the structural stability and the cycle reliability of the tin cathode. The tin-copper alloy formed in situ by laser can provide an interlocking interface between the active material and the copper current collector, can inhibit the tin active material from falling off from the copper current collector, and can play a buffer role in the oxide of the surface layer and the inactive material such as the bottom layer Cu and the like, and relieve the volume expansion of Sn in the repeated charging/discharging process, thereby obtaining good cycle performance. The copper-tin alloy generated by in-situ alloying can also be used as an active substance to participate in the oxidation-reduction process of electrochemical charging and discharging, so that the service life of the lithium ion battery is prolonged. Meanwhile, the laser technology has the characteristics of fineness and rapidness, can accurately process the area to be processed at fixed points, and is high in efficiency.
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FIG. 1 is a schematic diagram of the principle of a laser in-situ alloying method for enhancing the bonding strength of tin negative active material and copper current collector of a lithium ion battery according to the invention;
wherein, 1-femtosecond laser; 2-tin negative active material tin; 3-a copper current collector; 4-copper-tin alloy.
Detailed Description
The present invention will be further described with reference to the following examples. It is to be understood that the following examples are illustrative only and are not intended to limit the scope of the invention, which is to be given the full breadth of the appended claims and any and all insubstantial modifications and variations thereof which can be made by one skilled in the art based on the teachings of the invention as described above.
Example 1
Preparing a tin negative pole piece: mixing an active substance tin, a conductive agent (conductive carbon black) and a binder (polyvinylidene fluoride PVDF) according to a mass ratio of 8: 1:1, mixing and grinding uniformly to prepare slurry; and selecting a film coater with the size of 100 mu m, scraping the slurry on a copper current collector, placing the copper current collector on a large-surface dish bottom, and drying the dish bottom in a blast oven to obtain the tin negative pole piece. The tin active material layer has a thickness of 90 μm and the copper current collector has a thickness of 10 μm.
Taking a tin negative pole piece, attaching the tin negative pole piece on a working table, filling argon into a working space, carrying out focusing and homing treatment on femtosecond laser, setting the laser power to be 10W, the scanning speed to be 15mm/s, adopting a '#' shape in a scanning mode, carrying out laser in-situ alloying treatment on a tin negative pole, drying the treated tin negative pole piece (120 ℃), slicing the tin negative pole piece (with the size of 14mm and 10.5mg), assembling a positive pole shell, the tin negative pole piece, a diaphragm, a metal lithium piece, foamed nickel and a negative pole shell according to the sequence, and adopting an argon glove box as an assembling environment, wherein 2-3 drops of wetting electrolyte are required to be dripped between every two layers; after the assembly and the sealing are finished, the mixture needs to stand for more than 4 hours to be fully soaked, so that the charge and discharge test can be carried out.
And (3) carrying out constant-current charge and discharge performance test on the half-cell at room temperature by using a Xinwei cell test system, wherein the current density is 100mA/g, and the charge and discharge voltage range is 0.005-2.0V. The maximum reversible specific capacity of the negative plate obtained by the steps is 580.6mAh/g, the charging specific capacity (lithium removal) after 400 cycles is 286.4mAh/g, and the capacity retention rate is 49.32%. Compared with the tin cathode material prepared by other methods, the method has the advantages that the cycle life is greatly prolonged, and the structure is more stable in the electrode cycle process.
Claims (5)
1. A laser in-situ alloying method for enhancing the bonding strength of a tin negative active material and a copper current collector of a lithium ion battery is characterized by comprising the following steps of:
(1) preparation work in advance: vacuum drying the tin negative pole piece for later use; selecting a small tin negative pole piece sample for preliminary exploration test, and observing the depth of the laser ablated pole piece through a light mirror or a scanning electron microscope so as to determine the power and the scanning speed of the laser;
the laser power is determined to be 10W through preliminary exploration test, and the laser scanning speed is 15 mm/s;
(2) pasting the tin negative pole piece dried in the step (1) on a working table, and filling inert gas Ar in a working space; according to the laser power and the laser scanning speed determined in the step (1), setting the scanning mode of the laser to be # scanning, and carrying out laser in-situ alloying treatment on the tin negative pole piece;
(3) and (3) carrying out electrochemical performance test on the tin negative pole piece subjected to the laser in-situ alloying treatment in the step (2).
2. The laser in-situ alloying method for enhancing the bonding strength of the tin negative electrode active material and the copper current collector of the lithium ion battery as claimed in claim 1, wherein in the step (1), the tin negative electrode sheet has two layers, the upper layer is the tin active material, and the lower layer is the copper current collector.
3. The laser in-situ alloying method for enhancing the bonding strength of tin negative active material and copper current collector of lithium ion battery as claimed in claim 2, wherein the thickness of tin active material layer is 90 μm, and the thickness of copper current collector is 10 μm.
4. The laser in-situ alloying method for enhancing the bonding strength of the tin negative active material and the copper current collector of the lithium ion battery according to claim 1, wherein in the step (1), the selected laser is a femtosecond laser.
5. The laser in-situ alloying method for enhancing the bonding strength of tin negative active material and copper current collector of lithium ion battery according to claim 1, wherein in step (2), the scanning pitch of the "#" shaped scan is 200 μm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210756067.2A CN115101724A (en) | 2022-06-29 | 2022-06-29 | Laser in-situ alloying method for enhancing bonding strength of tin negative active material and copper current collector of lithium ion battery |
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| CN202210756067.2A CN115101724A (en) | 2022-06-29 | 2022-06-29 | Laser in-situ alloying method for enhancing bonding strength of tin negative active material and copper current collector of lithium ion battery |
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| CN115101724A true CN115101724A (en) | 2022-09-23 |
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| CN202210756067.2A Pending CN115101724A (en) | 2022-06-29 | 2022-06-29 | Laser in-situ alloying method for enhancing bonding strength of tin negative active material and copper current collector of lithium ion battery |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117913212A (en) * | 2024-03-20 | 2024-04-19 | 瑞浦兰钧能源股份有限公司 | Negative electrode plate, preparation method thereof and battery |
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- 2022-06-29 CN CN202210756067.2A patent/CN115101724A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117913212A (en) * | 2024-03-20 | 2024-04-19 | 瑞浦兰钧能源股份有限公司 | Negative electrode plate, preparation method thereof and battery |
| CN117913212B (en) * | 2024-03-20 | 2024-06-11 | 瑞浦兰钧能源股份有限公司 | Negative electrode plate, preparation method thereof and battery |
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