Preparation method and application of laser-induced ZnO / ZnF2 heterogeneous carbon cloth

Abstract

The invention belongs to the technical field of lithium metal batteries, and particularly relates to a preparation method and application of laser-induced ZnO / ZnF2 heterogeneous carbon cloth. The preparation method comprises the following steps: adding zinc trifluoroacetate powder into N, N-dimethylformamide, uniformly stirring to obtain a precursor solution containing ZnO / ZnF2, soaking carbon cloth (CC) in the precursor solution, standing at room temperature to obtain a ZnO / ZnF2-coated CC precursor, drying overnight, carrying out laser treatment, and forming ZnO / ZnF2-containing composite nanoparticles by laser induction to obtain the laser-induced ZnO / ZnF2 heterogeneous carbon cloth. The ZnO / ZnF2 heterogeneous interface and a built-in electric field formed by the ZnO / ZnF2 heterogeneous interface can induce ordered and uniform deposition of metal lithium and inhibit growth of lithium dendrites. Meanwhile, the prepared ZnO / ZnF2 composite nanoparticles can be used as a host material of a negative electrode of a lithium metal battery, the nucleation overpotential is reduced, the cycling stability is improved, the cycle life of the lithium metal battery is prolonged, and the stability of the lithium metal battery is improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery technology, specifically relating to a method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth and its application. Background Technology

[0002] Lithium-metal batteries are considered ideal candidates for next-generation rechargeable battery anode materials. Compared to traditional lithium-ion batteries, lithium-metal batteries offer significantly higher energy density. Their extremely high theoretical specific capacity and low electrochemical potential result in longer driving ranges for the same weight, demonstrating immense potential in electric vehicles, aerospace, portable electronic devices, and large-scale energy storage. However, despite these significant advantages, the commercial application of lithium-metal batteries faces numerous technical challenges, particularly in terms of safety, stability, and long-term cycle performance. The main issue lies in the instability of the lithium-metal anode during charge and discharge. For example, lithium metal is prone to dendrite formation, the generation of "dead lithium," and volume expansion during charge and discharge. These problems not only reduce the battery's cycle stability but also pose serious safety hazards. Therefore, these technical challenges must be overcome to bring lithium-metal batteries to practical application.

[0003] To address the aforementioned problems in lithium-ion batteries, researchers have proposed solutions such as using solid-state electrolytes, constructing interfacial protective layers and artificial SEI layers, and modifying liquid electrolytes with additives. Recent research has found that constructing a three-dimensional framework structure on or within the battery, providing uniform lithium deposition sites as a "host" material to accommodate lithium metal, can effectively improve the uneven deposition of lithium metal and slow down lithium dendrite growth. It can also alleviate internal battery stress caused by volume expansion of lithium metal during charging and discharging, thereby improving battery stability. However, when the deposition capacity is too large, a large number of "dead lithium" may accumulate near the lithiophilic sites, causing these sites to fail and affecting the uniform deposition of lithium metal. Therefore, to further improve the performance and stability of lithium-ion batteries, the stability and protection strategies of the lithiophilic sites in the three-dimensional framework structure have become critical issues that urgently need to be addressed. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a method for preparing laser-induced ZnO / ZnF2 heterostructure carbon cloth and its application. This invention utilizes the strong adsorption effect of the ZnO / ZnF2 heterostructure on metallic lithium and the built-in electric field generated at the ZnO / ZnF2 heterostructure interface to accelerate the adsorption of lithium. + The diffusion of lithium ions prevents their accumulation at adsorption sites, thereby effectively inducing uniform lateral deposition of metallic lithium and solving the problem of poor restriction of lithium dendrites by the host material in the existing technology.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth, the method comprising the following steps: (1) Add zinc trifluoroacetate powder to N,N-dimethylformamide and stir to obtain a precursor solution containing ZnO / ZnF2; (2) Carbon cloth (CC) was soaked in the precursor solution and allowed to stand at room temperature to obtain ZnO / ZnF2@CC precursor; (3) Arrange the soaked charcoal in a glass container and let it dry overnight; (4) Laser scribing is performed on the surface of the dried carbon cloth to induce the formation of ZnO / ZnF2 composite nanoparticles, which are then loaded into the carbon cloth to obtain laser-induced ZnO / ZnF2 heterogeneous carbon cloth (ZnO / ZnF2@CC).

[0006] The preparation method of this invention is simple, convenient, environmentally friendly, and pollution-free. It is easy to operate, requires minimal equipment, has a suitable reaction temperature, and is cost-effective, making it suitable for large-scale production. The unique feature of this invention is that the ZnO / ZnF2 heterostructure formed after carbonization significantly improves the deposition capacity of lithium metal. Through the formation of an internal electric field, it effectively regulates the transport of ions and electrons, promoting the orderly and uniform deposition of lithium metal and effectively suppressing the growth of lithium dendrites. Simultaneously, the graphite-carbon-coated ZnO / ZnF2 composite nanoparticles significantly increase the specific surface area and conductivity of the electrode, further accelerating lithium-ion transport and providing more space for lithium metal storage, effectively mitigating the volume expansion of the electrode during charging and discharging. Therefore, the synergistic effect of the ZnO / ZnF2 heterostructure and carbon coating significantly improves the cycle life and stability of lithium metal batteries.

[0007] Further, in step (1), the concentration of zinc trifluoroacetate in N,N-dimethylformamide is 0.1-0.15 g / mL, the stirring time is 0.5-1 h, and the stirring speed is 300-600 rpm.

[0008] Furthermore, in step (2), the carbon cloth is first washed with concentrated nitric acid, concentrated sulfuric acid, and acetone in sequence before use, and then washed repeatedly with anhydrous ethanol and deionized water alternately.

[0009] Furthermore, the concentration of the concentrated nitric acid is 65-68%, the concentration of the concentrated sulfuric acid is 98%, the washing time is 15-30 min, the washing time of the acetone is 5-10 min, and the number of times the anhydrous ethanol and deionized water are alternately washed is 1-6 times.

[0010] Furthermore, in step (2), the time for standing at room temperature is 3-5 h.

[0011] Furthermore, in step (3), the temperature for overnight drying is 50-80 ℃, and the time for overnight drying is 8-12 h.

[0012] Furthermore, in step (4), the laser scribing is CO2 laser engraving, and the laser scribing spot size is 0.2 mm.

[0013] Further, in step (4), the processing area of ​​the laser scribing is the size of the carbon cloth during cutting and soaking, and the parameters of the laser scribing process are: scanning power 6.5-8 W, engraving speed 80-120 mm / s, scribing spacing 0.02-0.05 mm.

[0014] A second aspect of the present invention provides a ZnO / ZnF2 heterogeneous carbon cloth prepared by the above-described preparation method.

[0015] The laser-induced ZnO / ZnF2 heterocarbon cloth prepared by the method of this invention exhibits good affinity for lithium metal when used as a host material for lithium metal anodes. The transport of Li ions and electrons can be effectively regulated through the built-in electric field at the heterostructure interface. Simultaneously, it can effectively buffer the massive volume expansion of lithium metal during charging and discharging. The three-dimensional structure of the carbon cloth and the partially laser-induced laser-induced graphene (LIG) provide growth sites for ZnO / ZnF2. Utilizing the lithium-affinity properties of the ZnO / ZnF2 composite nanoparticles can effectively reduce the nucleation overpotential of lithium metal, ultimately improving the deposition behavior of lithium metal and effectively suppressing the growth of lithium dendrites, thus maintaining good cycling stability under practical conditions.

[0016] A third aspect of the present invention provides an application of the above-mentioned ZnO / ZnF2 heterogeneous carbon cloth in a lithium metal battery, wherein the laser-induced ZnO / ZnF2 heterogeneous carbon cloth serves as a negative electrode host material or a negative electrode material of a lithium metal battery.

[0017] The laser-induced ZnO / ZnF2 heterocarbon cloth prepared by the method of this invention exhibits excellent lithium affinity. When used as a host material in the anode of lithium metal batteries, it effectively suppresses the formation of lithium dendrites, resulting in batteries with low nucleation overpotential, high coulombic efficiency, ultra-long cycle life, and stability. Importantly, the half-cell assembled using the laser-induced ZnO / ZnF2 heterocarbon cloth maintains a coulombic efficiency close to 100% after multiple cycles (more than 60 cycles), with almost no significant efficiency degradation.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth and its application. In this invention, zinc trifluoroacetate powder is added to N,N-dimethylformamide and stirred until homogeneous to obtain a precursor solution containing ZnO / ZnF2. Carbon cloth (CC) is immersed in the precursor solution and allowed to stand at room temperature to obtain a ZnO / ZnF2@CC precursor. After drying overnight, it is laser-treated to induce the formation of ZnO / ZnF2 composite nanoparticles, thus obtaining laser-induced ZnO / ZnF2 heterogeneous carbon cloth. The ZnO / ZnF2 hetero interface and the built-in electric field it forms can induce the orderly and uniform deposition of lithium metal and inhibit the growth of lithium dendrites. Simultaneously, the prepared ZnO / ZnF2 composite nanoparticles can serve as a host material for the negative electrode of lithium metal batteries, reducing nucleation overpotential, improving cycle stability, and enhancing the cycle life and stability of lithium metal batteries. Specifically, the present invention has the following advantages: (1) The preparation method of the present invention is simple and easy to carry out, requires a low temperature, is convenient for post-processing, does not require high equipment, has a moderate cost, and is suitable for large-scale production.

[0019] (2) The ZnO / ZnF2 heterostructure formed after wetting has a strong adsorption effect on lithium metal, and the built-in electric field formed can regulate the rapid transport of ions and electrons, induce uniform lateral deposition of lithium metal, and thus effectively inhibit the growth of lithium dendrites.

[0020] (3) The laser-induced ZnO / ZnF2 heterocarbon cloth synthesized by the method of the present invention can be used as a negative electrode skeleton material for lithium metal batteries. It can reduce the nucleation barrier of lithium metal by undergoing an alloying reaction with lithium ions, thereby reducing the deposition resistance and promoting the uniform deposition of lithium metal.

[0021] (4) This invention generates ZnO / ZnF2 composite nanoparticles through laser induction. This method is simple and efficient, and composite nanoparticles are generated in situ on carbon cloth. This process not only improves the conductivity and stability of the composite material, but also achieves precise control over the deposition behavior of lithium metal ions, which in turn helps to achieve uniform deposition and dendrite suppression in lithium metal batteries.

[0022] (5) The laser-induced ZnO / ZnF2 heterocarbon cloth synthesized using the method of this invention exhibits excellent coulombic efficiency and good cycle stability. This composite material can effectively regulate lithium metal deposition, thereby improving the charge-discharge efficiency and long-term stability of lithium metal batteries. Attached Figure Description

[0023] Figure 1 Scanning electron microscope image of ZnO / ZnF2@CC; Figure 2 High-resolution transmission electron microscopy (TEM) image and selected area electron diffraction (SED) pattern of ZnO / ZnF2@CC; Figure 3 The energy dispersive spectral image of ZnO / ZnF2@CC; Figure 4 X-ray diffraction pattern of ZnO / ZnF2@CC; Figure 5 XPS fine spectrum of ZnO / ZnF2@CC; Figure 6 Raman spectrum of ZnO / ZnF2@CC; Figure 7 The overpotential diagram for laser-induced nucleation of ZnO / ZnF2 heterostructured carbon cloth; Figure 8 Coulombic efficiency diagram of laser-induced lithium deposition / stripping in ZnO / ZnF2 heterostructured carbon cloth; Figure 9 This is a graph showing the long-cycle performance of a laser-induced ZnO / ZnF2 heterostructured carbon cloth symmetric cell. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0026] Example 1: Preparation of a laser-induced ZnO / ZnF2 heterogeneous carbon cloth The commercial CO2 laser used in this embodiment is a 3020 laser engraving machine, purchased from Shanghai Fengtuo Trading Co., Ltd.

[0027] (1) Cleaning carbon cloth: First, soak the carbon cloth (CC) in concentrated nitric acid (about 65%-68%) and concentrated sulfuric acid (98%) in turn. Clean each for 15 min under ultrasonic conditions of 600 W. Then, ultrasonically wash with acetone for 5 min. Finally, clean with anhydrous ethanol and deionized water alternately 5 times. After cleaning, place it in an oven to dry.

[0028] (2) Preparation of ZnO / ZnF2@CC precursor: 1.5 g of zinc trifluoroacetate was dissolved in 10 mL of N,N-dimethylformamide to form a precursor solution. After the solution was fully dissolved under magnetic stirring (400 rpm for 30 min), the cleaned and dried carbon cloth (CC) was completely immersed in the precursor solution. After standing at room temperature for 4 h, it was placed in an oven to dry overnight (60 ℃ for 12 h) to obtain ZnO / ZnF2@CC precursor.

[0029] (3) The precursor in step (2) was laser scribing was performed using a commercial CO2 laser. The processing area covered the entire surface of the precursor. The laser parameters used were: scanning power 14 W, engraving speed 120 mm / s, and engraving accuracy 0.05 mm. ZnO / ZnF2 composite nanoparticles were formed and loaded onto carbon cloth to obtain laser-induced ZnO / ZnF2 heterogeneous carbon cloth (ZnO / ZnF2@CC).

[0030] Morphological characterization of ZnO / ZnF2@CC was performed. Figure 1 Scanning electron microscopy (SEM) images reveal the formation of ZnO / ZnF2 composite nanoparticles. These nanoparticles construct spherical clusters, generating numerous interstitial pores and intraparticle pores, forming a well-developed porous network. The ZnO / ZnF2 composite nanoparticles are orderly arranged along a specific direction and are relatively uniform in size, adhering to the carbon cloth (CC). By providing uniform lithium deposition sites, they effectively induce uniform lithium deposition.

[0031] Figure 2 The high-resolution transmission electron microscope (TEM) image and selected area electron diffraction (SED) pattern of ZnO / ZnF2@CC are shown. The lattice spacing of 0.26 nm corresponds to the (002) crystal plane of ZnO, and the lattice spacing of 0.21 nm is consistent with the (210) crystal plane of ZnF2. This indicates that a ZnO / ZnF2 heterojunction was successfully established at the interface.

[0032] Figure 3 The energy dispersive spectroscopy (EDS) image of ZnO / ZnF2@CC shows that the elements C, O, N, F and Zn are relatively uniformly distributed in ZnO / ZnF2@CC.

[0033] Figure 4 The image shows the X-ray diffraction pattern of ZnO / ZnF2@CC. It can be seen that the diffraction peaks of ZnO / ZnF2@CC match well with the standard peaks of ZnO and ZnF2, indicating that the heterojunction was successfully constructed and formed a stable structure.

[0034] Figure 5The XPS fine spectrum of ZnO / ZnF2@CC shows that Zn exists in the forms of Zn-O and Zn-F, and F exists in the forms of Zn-F and CF, further demonstrating the stable existence of the ZnO / ZnF2 heterojunction.

[0035] Figure 6 The image shows the Raman spectrum of ZnO / ZnF2@CC. The characteristic peak of the 2D peak reflects the partial formation of laser-induced graphene in ZnO / ZnF2@CC under laser induction.

[0036] Example 2: Performance characterization of lithium metal batteries using ZnO / ZnF2@CC as the negative electrode host material The ZnO / ZnF2@CC from Example 1 was cut into circular electrode sheets with a diameter of 12 mm and used as the host material for the negative electrode of lithium metal batteries for electrochemical performance testing.

[0037] (1) Characterization of nucleation overpotential Half-cell assembly: 12 mm diameter ZnO / ZnF2@CC circular electrodes and lithium metal foil of the same size were assembled into Li|ZnO / ZnF2@CC half-cells in a glove box filled with argon gas and with water and oxygen content below 0.1 ppm. The electrolyte system was a 1,3-dioxolane (DOL) / ethylene glycol dimethyl ether (DME) solution containing 2 wt% lithium nitrate (LiNO3) and 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (v / v = 1:1). A commercially available polypropylene porous membrane was used as the separator.

[0038] Electrochemical testing: The Li|ZnO / ZnF2@CC half-cell initially measured at 0.05 mA cm⁻¹ -2 Cycled 5 times at a current between 0.01 and 3 V, then at 1 mAh cm⁻¹. -2 Repeated deposition / stripping of 3 mAh cm under current -2 The nucleation overpotential of metallic lithium is as follows: Figure 7 As shown, the nucleation overpotential is the difference between the minimum voltage during lithium deposition and the stable voltage. The nucleation overpotential of the Li|ZnO / ZnF2@CC half-cell is 8.5 mV, indicating that the lithium-affinity properties of the ZnO / ZnF2 composite nanoparticles can effectively reduce the nucleation overpotential of metallic lithium.

[0039] (2) Characterization of cycle performance Half-cell assembly: 12 mm diameter ZnO / ZnF2@CC circular electrodes and lithium metal foil of the same size were assembled into Li|ZnO / ZnF2@CC half-cells in a glove box filled with argon gas and with water and oxygen content below 0.1 ppm. The electrolyte system was a 1,3-dioxolane (DOL) / ethylene glycol dimethyl ether (DME) solution containing 2 wt% lithium nitrate (LiNO3) and 1 mol / L lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) (v / v = 1:1). A commercially available polypropylene porous membrane was used as the separator.

[0040] Electrochemical testing: The Li|ZnO / ZnF2@CC half-cell was first tested at 0.05 mA cm⁻¹. -2 The circuit was cyclically run 5 times between 0.01 and 3V at a current density of 1 mA cm⁻¹. -2 The discharge capacity is 3 mAh cm⁻¹ -2 The current density is 1 mA cm⁻¹ -2 The discharge capacity is 4 mAh cm⁻¹ -2 The current density is 2 mA cm⁻¹ -2 The discharge capacity is mAh cm -2 There are three sets of conditions, and their coulomb efficiency is as follows: Figure 8 As shown, under all test conditions, the coulombic efficiency of the battery was close to 100%, specifically 99.13%, 99.18%, and 98.82%. Under different current densities and charge / discharge capacities, and with increasing cycle number, the coulombic efficiency in the figure showed almost no significant decrease, remaining close to 100%. This indicates that the battery exhibits extremely low capacity decay during charge and discharge, with virtually no lithium loss or "dead lithium" formation, demonstrating good reversibility and an efficient lithium deposition / stripping process. This indicates that the ZnO / ZnF2 composite nanoparticles possess excellent lithiophilic properties and high stability, effectively preventing lithium dendrite formation or capacity decay, and promoting uniform lithium metal deposition.

[0041] (3) Characterization of long-cycle performance Assembly of symmetrical cells: First, electrodeposition was performed on the Li|ZnO / ZnF2@CC half-cell, with a discharge current of 0.05 mAcm. -2 Pre-deposition 5 mAh cm -2 The half-cell was then disassembled in a glove box filled with argon gas and with water and oxygen content both below 0.1 ppm. The composite lithium metal anode ZnO / ZnF2@CC was removed, and the residual electrolyte on the surface was cleaned with excess DME. Two composite lithium metal anodes ZnO / ZnF2@CC with the same lithium metal capacity were assembled into a Li@ZnO / ZnF2 ||Li@ZnO / ZnF2 symmetric cell. The electrolyte system was the same as characterized above.

[0042] Electrochemical testing: Li@ZnO / ZnF2@LIG||Li@ZnO / ZnF2@LIG symmetric cell at 1 mA cm⁻¹ -2 Repeated deposition / stripping of 1 mAh cm under current -2 Lithium metal, its cycle performance is as follows Figure 9 As shown, the symmetrical cell exhibits a stable cycling curve within 300 h.

[0043] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth, characterized in that, The preparation method includes the following steps: (1) Add zinc trifluoroacetate powder to N,N-dimethylformamide and stir to obtain a precursor solution containing ZnO / ZnF2; (2) The carbon cloth was soaked in the precursor solution and allowed to stand at room temperature to obtain the ZnO / ZnF2@CC precursor; (3) Arrange the soaked charcoal in a glass container and let it dry overnight; (4) Laser scribing is performed on the surface of the dried carbon cloth to induce the formation of ZnO / ZnF2 composite nanoparticles, which are then loaded into the carbon cloth to obtain laser-induced ZnO / ZnF2 heterogeneous carbon cloth.

2. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (1), the concentration of zinc trifluoroacetate in N,N-dimethylformamide is 0.1-0.15 g / mL, the stirring time is 0.5-1 h, and the stirring speed is 300-600 rpm.

3. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (2), the carbon cloth is first washed with concentrated nitric acid, concentrated sulfuric acid and acetone in sequence before use, and then washed repeatedly with anhydrous ethanol and deionized water.

4. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 3, characterized in that, The concentration of the concentrated nitric acid is 65-68%, the concentration of the concentrated sulfuric acid is 98%, the washing time is 15-30 min, the washing time of the acetone is 5-10 min, and the number of times the anhydrous ethanol and deionized water are used for alternating washing is 1-6 times.

5. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (2), the time for standing at room temperature is 3-5 h.

6. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (3), the temperature for overnight drying is 50-80 ℃, and the time for overnight drying is 8-12 h.

7. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (4), the laser scribing is CO2 laser engraving, and the laser scribing spot size is 0.2 mm.

8. The method for preparing laser-induced ZnO / ZnF2 heterogeneous carbon cloth according to claim 1, characterized in that, In step (4), the processing area of ​​the laser scribing is the size of the carbon cloth during cutting and soaking, and the parameters of the laser scribing process are: scanning power 6.5-8 W, engraving speed 80-120 mm / s, scribing spacing 0.02-0.05 mm.

9. A ZnO / ZnF2 heterogeneous carbon cloth prepared by the preparation method according to any one of claims 1-8.

10. An application of the ZnO / ZnF2 heterogeneous carbon cloth as described in claim 9 in a lithium metal battery, characterized in that, The laser-induced ZnO / ZnF2 heterostructured carbon cloth serves as the negative electrode host material or negative electrode material for lithium metal batteries.

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