Method for punching Bessel laser electrode material for high-performance battery

Abstract

The invention discloses a method for punching a Bessel laser electrode material for a high-performance battery, and belongs to the field of laser processing of electrode materials. The implementation method comprises the following steps: an ultrasonic spraying instrument is adopted to spray ion conductive and electron non-conductive slurry on the surface of an electrode material, and the slurry can conduct lithium ions when being applied to a battery due to high ion conductivity, so that the excellent performance of the battery is kept; due to low electron conductivity, the material can be coated on an electrode as a protective layer to absorb energy at a Bessel side lobe so as to inhibit side lobe damage of an electrode material, and the electrode material at the side lobe is reserved, so that the capacity of the electrode is not influenced. An adopted Bessel laser processing system comprises a femtosecond laser, a diaphragm, an ultrafast laser reflection group, a mechanical switch, a computer, a dichroscope, a Bessel cutting head, an electrode material, a three-dimensional precision displacement table, a beam splitter, white light and a CCD dynamic imaging unit. According to the invention, the sidelobe damage caused when the Bessel laser punches a hole in the high-absorption electrode material can be obviously inhibited, and the power density of the battery is improved.

Description

Technical Field

[0001] The invention discloses a method for drilling a Bessel laser electrode material for a high-performance battery, belonging to the technical field of electrode material laser processing Background Art

[0002] Bessel beams have the advantages of extremely small central spot diameter, no diffraction, and long focal depth, and are more suitable for processing structures with high aspect ratios. However, Bessel lasers will cause a large proportion of sidelobe damage to the material during processing, and the intensity of the first-order sidelobe is about 16% of the central beam. In practical applications, Bessel lasers are often used to process materials with poor electronic conductivity, such as glass, polymers, etc., because these materials have weak absorption of femtosecond lasers, and the loss problem caused by Bessel sidelobes is almost non-existent and can play the advantages of high aspect ratios. When Bessel beams process materials with strong absorption, such as electrodes, metals and other materials with good electronic conductivity, these sidelobes will cause excess loss to the sample.

[0003] In the actual processing of electrodes, machining through holes with high aspect ratio and low loss helps to improve the rate performance of electrodes. Traditional methods of manufacturing pore structures, such as calendering, are incompatible with battery processes. The advantage of the long focal depth of Bessel laser is conducive to the processing of through holes, and the small spot diameter can meet the advantage of low loss. It is a very favorable electrode through-hole processing tool and is compatible with existing battery preparation methods. However, in actual through-hole processing, the loss caused by Bessel side lobes will lead to additional loss of electrode materials. Therefore, for Bessel laser processing of electrode materials, a method that can suppress sidelobe damage but does not affect the properties of the electrode material itself is needed, which is ultimately used to improve the capacity and rate performance of the battery. Summary of the invention

[0004] In order to meet and solve the problem of unnecessary damage to materials caused by side lobes during Bessel processing of high-absorption electrode materials in existing methods and the demand of batteries for high power density, the present invention adopts an ultrasonic sprayer to spray ion-conductive and electron-non-conductive slurry on the surface of the electrode material, and uses Bessel laser to focus on the surface of the electrode material to manufacture the pore structure, thereby suppressing side lobe damage during Bessel laser electrode pore manufacturing, reducing unnecessary electrode loss, and improving the power density of the battery.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention discloses a method for drilling Bessel laser electrode materials for high-performance batteries, which adopts an ultrasonic sprayer to spray ion-conductive and electron-non-conductive slurry on the surface of the electrode material, and focuses the Bessel laser on the surface of the electrode material to manufacture the pore structure, thereby suppressing the side lobe damage during the Bessel laser electrode pore manufacturing, reducing the unnecessary electrode loss, and improving the power density of the battery.

[0007] Furthermore, the ion-conductive and electron-non-conductive slurry is mainly obtained by ultrasonically mixing a solid electrolyte, a binder and a solvent, and the added amounts thereof are 500 mg of a solid electrolyte, 5% of a binder by mass and 5 mL of a solvent, respectively.

[0008] Furthermore, the solid electrolyte is LLZTO, LATP or LAGP; the binder is PVDF, PEO or PAN; and the solvent is ethanol or acetone.

[0009] A method for drilling a Bessel laser electrode material for a high-performance battery comprises the following steps:

[0010] Step 1: preparing an ion conductive and electronically non-conductive slurry, dissolving a solid electrolyte and a binder in a solvent by ultrasonic rotation to prepare a uniformly mixed ion conductive and electronically non-conductive slurry;

[0011] Step 2: using an ultrasonic sprayer to atomize the pre-prepared ion conductive and electronically non-conductive slurry into fine particles through an ultrasonic atomization device, and then evenly coating the fine particles on the electrode surface through a carrier gas, thereby forming an ion conductive and electronically non-conductive slurry coating of a predetermined thickness on the electrode surface;

[0012] Step 3: Use the Bessel cutting head and the lighting system to build a Bessel laser processing system, place the electrode coated with the ion conductive and electronic non-conductive slurry on the mobile platform, and set the program to impact punch to prepare the pore array;

[0013] Step 4: Assemble the electrode with pore structure prepared by this method and the untreated electrode into batteries respectively, and test and compare the performance of the batteries using a blue battery tester. The results show that the electrode processed with pore array exhibits better rate performance.

[0014] Furthermore, the Bessel laser processing system includes: a femtosecond laser, an aperture, an ultrafast laser reflection group, a mechanical switch, a computer, a dichroic mirror, a Bessel cutting head, an electrode material, a three-dimensional precision displacement stage, a beam splitter, white light, and a CCD dynamic imaging unit; the femtosecond laser emitted by the femtosecond laser is collimated by the aperture, and then passes through the reflection mirror group and the mechanical switch, and is reflected by the dichroic mirror into the Bessel cutting head and focused onto the electrode sample located on the precision displacement stage; the white light source passes through the beam splitter, the dichroic mirror, and the CCD dynamic imaging unit to jointly realize the real-time imaging and monitoring of the Bessel laser drilling on the electrode surface; wherein the mechanical switch and the CCD dynamic imaging unit are connected to the computer to realize linkage control.

[0015] Furthermore, the Bessel cutting head can convert Gaussian laser into Bessel laser and can withstand relatively high laser energy. It uses a 2° conical lens, a 100mm plano-convex lens, and a 20x objective lens.

[0016] Beneficial effects:

[0017] 1. The present invention discloses a method for drilling holes in electrode materials using Bessel lasers for high-performance batteries, and uses a Bessel laser processing system, including a femtosecond laser, an aperture, an ultrafast laser reflection group, a mechanical switch, a dichroic mirror, a Bessel cutting head, a three-dimensional precision translation stage, electrode materials, white light, a beam splitter, and a CCD dynamic imaging unit. The Bessel laser generated by the system has the advantages of extremely small spot diameter, no diffraction, and long focal depth. The advantage of long focal depth is conducive to processing through holes, and the small spot diameter can meet the advantage of low loss, which is compatible with the existing battery preparation process. Therefore, the Bessel laser processing system can be used for the manufacture of pore structures of electrode materials.

[0018] 2. The present invention discloses a method for drilling electrode materials using a Bessel laser for high-performance batteries, which uses an ultrasonic sprayer to spray an ion-conductive and electron-non-conductive slurry on the surface of the electrode material. The high ionic conductivity enables the slurry to conduct lithium ions when applied to the battery, thereby maintaining the excellent performance of the battery; the low electronic conductivity enables it to be coated on the electrode and act as a protective layer to absorb the energy at the Bessel side lobes, suppress the side lobe damage of the electrode material, and retain the electrode material at the side lobes, thereby not affecting the capacity of the electrode.

[0019] 3. The present invention discloses a method for punching holes in Bessel laser electrode materials for high-performance batteries. An electrode with a porous structure prepared by the method and an untreated electrode are assembled into batteries respectively. The introduction of the porous structure is beneficial to the penetration of the electrolyte and the migration of lithium ions, thereby reducing the internal resistance. The electrode processed by the method exhibits higher capacity and rate performance, and improves the power density of the electrode, thereby making the method applicable to high-performance batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a schematic flow chart of a method for drilling holes in Bessel laser electrode materials for high-performance batteries in the present invention.

[0021] Figure 2 The invention relates to a method for preparing an ion-conducting and electron-non-conducting slurry.

[0022] Figure 3 The ultrasonic sprayer is used to spray ion-conductive and electron-non-conductive slurry on the electrode.

[0023] Figure 4 Schematic diagram of the Bessel laser processing system.

[0024] Figure 5 The figure shows the morphology comparison results of Bessel laser drilling on sprayed and unsprayed slurry electrodes.

[0025] Figure 6is the light intensity distribution of Bessel laser at different positions.

[0026] Figure 7 This is a comparison chart of the rate performance of batteries assembled with Bessel laser punched and non-punched electrodes.

[0027] Among them: 1—femtosecond laser, 2—aperture, 3—ultrafast laser reflection group, 4—mechanical switch, 5—computer, 6—dichroic mirror, 7—Bessel cutting head, 8—electrode material, 9—three-dimensional precision translation stage, 10—beam splitter, 11—white light, 12—CCD dynamic imaging unit. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not therefore limited to the following embodiments.

[0029] like Figure 1 As shown, the method for drilling a Bessel laser electrode material for a high-performance battery disclosed in this embodiment uses an ultrasonic sprayer to spray an ion-conductive and electron-non-conductive slurry on the surface of the electrode material, and uses the Bessel laser to focus on the surface of the electrode material to manufacture the pore structure, thereby suppressing the sidelobe damage during the Bessel laser electrode pore manufacturing, reducing the unnecessary electrode loss, and improving the power density of the battery. The method for drilling a Bessel laser electrode material for a high-performance battery disclosed in this embodiment has the following specific implementation steps:

[0030] Step 1: Dissolve 500 mg of LATP solid electrolyte and 5% of binder by mass in 5 ml of ethanol solvent by ultrasonic rotation. Figure 2 As shown, a uniformly mixed ion conductive and electronically non-conductive slurry is finally prepared.

[0031] The solid electrolyte can be a ceramic powder such as lithium lanthanum zirconium tantalum oxide (LLZTO), lithium aluminum titanium phosphate (LATP) or lithium aluminum germanium phosphate (LAGP), the binder can be a polymer such as polyvinylidene fluoride (PVDF), polyethylene oxide (PEO) or polyacrylonitrile (PAN), and the solvent can be ethanol or acetone.

[0032] Step 2: Use an ultrasonic sprayer to spray the pre-prepared ion conductive and electronic non-conductive slurry, such as Figure 3 As shown, it is atomized into fine particles by an ultrasonic atomization device, and then evenly coated on the surface of a 60μm thick lithium iron phosphate (LFP) electrode by a carrier gas, thereby forming a certain thickness (~5μm) of LATP ion-conductive and electronically non-conductive slurry coating on the electrode surface.

[0033] The thickness of the ion-conductive electronic non-conductive slurry film needs to be determined according to the thickness of the electrode. Too thick is not conducive to Bessel laser drilling, and too thin cannot completely absorb the energy at the side lobe. The optimal thickness should meet the following requirements: the thickness of the coating can absorb 16% of the energy at the Bessel side lobe, and 84% of the energy of the central spot can drill a hole with the common thickness of the ion-conductive electronic non-conductive slurry and the electrode.

[0034] Step 3: The Bessel laser processing system includes: a femtosecond laser 1, an aperture 2, an ultrafast laser reflection group 3, a mechanical switch 4, a computer 5, a dichroic mirror 6, a Bessel cutting head 7, an electrode material 8, a three-dimensional precision displacement stage 9, a beam splitter 10, white light 11, and a CCD dynamic imaging unit 12; the femtosecond laser emitted by the femtosecond laser 1 is collimated by the aperture 2, passes through the reflection mirror group 3 and the mechanical switch 4, is reflected by the dichroic mirror 6 into the Bessel cutting head 7 and is focused onto the electrode sample 8 located on the precision displacement stage 9; the white light source 11 passes through the beam splitter 10, the dichroic mirror 6, and the CCD dynamic imaging unit 12 to jointly realize the real-time imaging and monitoring of the Bessel laser drilling on the electrode surface; wherein the mechanical switch and the CCD dynamic imaging unit are connected to the computer to realize linkage control.

[0035] The Bessel cutting head can convert Gaussian laser into Bessel laser and can withstand relatively high laser energy. It is equipped with a 2° conical lens, a 100mm plano-convex lens, and a 20x objective lens.

[0036] Step 4: Use Bessel laser to impact-drill the electrode coated with LATP ion-conductive and electron-non-conductive slurry and the uncoated electrode, and characterize the surface morphology of the sample by optical microscopy and scanning electron microscopy. Figure 5 As shown in the figure, the untreated electrode is processed with concentric rings around the processed pores, which is the result of sidelobe damage when Bessel laser processes high-absorption electrode materials. The pore structure on the electrode coated with LATP ion-conductive and electronically non-conductive slurry is significantly reduced, and the pore size can be controlled to 5μm. The sidelobe damage of the electrode material by Bessel is suppressed, reducing the unnecessary electrode loss.

[0037] like Figure 6 As shown in the figure, the focal depth of the spot at the center of the Bessel laser is long and the energy is strong, which can drill holes in the total thickness of the ion-conducting and electron-non-conducting slurry and the electrode. The side lobes also have a certain amount of energy, accounting for about 16% of the total energy. This light field distribution makes a series of concentric rings around the electrode pores (such as Figure 5 c).

[0038] Step 5: Assemble the electrode with a porous structure prepared by the method and the untreated electrode into batteries respectively, and test the capacity of the battery at different current densities using a blue electric test system, such as Figure 7As shown. Due to the introduction of the pore structure in the electrode material, the electrolyte can penetrate into the pores, which is more conducive to the migration of lithium ions and reduces the internal resistance of the battery. Therefore, the electrode with a pore structure shows better capacity and rate performance than the untreated electrode above 5C, that is, the power density of the battery is improved. Specifically, the LFP electrode treated with a 60μm laser obtained 77, 49, 33, 26 and 22mAh g at 6C, 7C, 8C, 9C and 10C, respectively. -1 The specific capacities of the untreated electrodes were only 33, 16, 8, 4, and 2 mAh g -1 The capacity and power density are increased by ~60%.

[0039] The electrode material selected in the present invention is LFP electrode material, and the method can also be applied to pore manufacturing of other electrode materials.

[0040] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for drilling electrode materials using Bessel lasers for high-performance batteries, characterized in that: An ultrasonic sprayer is used to spray ion-conductive and electron-non-conductive slurry on the surface of the electrode material, and a Bessel laser is focused on the surface of the electrode material to manufacture the pore structure, thereby suppressing sidelobe damage during Bessel laser electrode pore manufacturing, reducing excess electrode loss, and improving the power density of the battery.

2. A method for drilling a Bessel laser electrode material for a high-performance battery as claimed in claim 1, characterized in that: The ion-conductive and electron-non-conductive slurry is mainly obtained by ultrasonically mixing a solid electrolyte, a binder and a solvent, and the added amounts thereof are 500 mg of a solid electrolyte, 5% of a binder by mass and 5 mL of a solvent, respectively.

3. A method for drilling a Bessel laser electrode material for a high-performance battery as claimed in claim 2, characterized in that: The solid electrolyte is LLZTO, LATP or LAGP; the binder is PVDF, PEO or PAN; and the solvent is ethanol or acetone.

4. The method according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: preparing an ion conductive and electronically non-conductive slurry, dissolving a solid electrolyte and a binder in a solvent by ultrasonic rotation to prepare a uniformly mixed ion conductive and electronically non-conductive slurry; Step 2: using an ultrasonic sprayer to atomize the pre-prepared ion conductive and electronically non-conductive slurry into fine particles through an ultrasonic atomization device, and then evenly coating the fine particles on the electrode surface through a carrier gas, thereby forming an ion conductive and electronically non-conductive slurry coating of a predetermined thickness on the electrode surface; Step 3: Use the Bessel cutting head and the lighting system to build a Bessel laser processing system, place the electrode coated with the ion conductive and electronic non-conductive slurry on the mobile platform, and set the program to impact punch to prepare the pore array; Step 4: Assemble the electrode with a pore structure prepared by this method and the untreated electrode into batteries respectively, and test and compare the battery performance using a blue battery tester. The results show that the electrode with processed pore array exhibits better rate performance.

5. The method according to claim 4, characterized in that: The Bessel laser processing system includes a femtosecond laser, an aperture, an ultrafast laser reflection group, a mechanical switch, a computer, a dichroic mirror, a Bessel cutting head, an electrode material, a three-dimensional precision displacement stage, a beam splitter, white light, and a CCD dynamic imaging unit; the femtosecond laser emitted by the femtosecond laser is collimated by the aperture, and then passes through a reflection mirror group and a mechanical switch, and is reflected by the dichroic mirror into the Bessel cutting head and focused onto an electrode sample located on the precision displacement stage; the white light source passes through the beam splitter, the dichroic mirror, and the CCD dynamic imaging unit to jointly realize real-time imaging and monitoring of the Bessel laser drilling on the electrode surface; wherein the mechanical switch and the CCD dynamic imaging unit are connected to a computer to realize linkage control.

6. The method according to claim 5, characterized in that: The Bessel cutting head can convert Gaussian laser into Bessel laser and can withstand relatively high laser energy. It is equipped with a 2° conical lens, a 100mm plano-convex lens, and a 20x objective lens.

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