Laser etching self-supporting graphene film, preparation method thereof and metal battery

Abstract

The invention provides a laser etching self-supporting graphene film, a preparation method thereof and a metal battery, and belongs to the technical field of electrochemical energy storage materials, and the preparation method comprises the following steps: adding a lamellar orientation improver into a dispersion liquid containing a graphene film precursor, and homogenizing to obtain a mixed solution; the graphene film precursor is at least one of graphene oxide and polyimide, and the lamellar orientation improver is at least one of phenylethylamine and polystyrolsulfon acid; coating the mixed solution to form a wet film, drying and stripping to obtain a graphene oxide film; carrying out high-temperature graphitization treatment on the graphene oxide film to obtain a graphene film; and performing laser etching and punching on the graphene film to form a vertical through hole array. The laser etching self-supporting graphene film as a negative electrode of a metal battery can store energy and guide uniform deposition and efficient stripping of metal, dendritic crystal growth is effectively inhibited, cycling stability and coulombic efficiency are improved, and the advantages of high area capacity and long cycle life are achieved.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage materials technology, and more specifically, relates to a laser-etched self-supporting graphene film, its preparation method, and a metal battery. Background Technology

[0002] Lithium-ion batteries are currently the most widely used rechargeable battery system, and graphite is often used as the anode material. Graphite anodes are commercialized due to their structural stability and high conductivity, but their theoretical capacity is limited, approximately 372 mAh g⁻¹. -1 This makes it difficult to meet the high energy density requirements of the next generation of high-specific-energy storage systems, such as new energy vehicles, low-altitude aircraft, and artificial intelligence equipment.

[0003] To improve battery energy density, researchers have proposed various high-capacity anode materials, including silicon-based anodes, lithium metal anodes, and anode-free lithium metal battery systems. While these systems significantly improve the theoretical energy density of batteries, they still face a series of technical challenges during cycling, such as uncontrolled volume expansion, lithium dendrite growth, dead lithium formation, and instability at the solid-state electrolyte interface (SEI). These problems lead to decreased anode coulombic efficiency, rapid capacity decay, and increased battery safety risks.

[0004] Existing technologies primarily improve lithium deposition behavior through electrolyte optimization, separator modification, and current collector structure control. Furthermore, introducing a lithium-affinity active layer or composite lithium storage coating onto the surface of the metal current collector can, to some extent, regulate lithium deposition and stripping. However, such strategies typically use a metal current collector (e.g., copper foil) as a substrate, requiring the additional construction of functional coatings on its surface. This not only increases the complexity of the electrode structure and the proportion of inactive mass but also easily introduces interfacial instability during cycling, leading to increased battery weight and limited energy density improvement.

[0005] Recent studies have shown that highly oriented dense graphene films possess high conductivity, low density, and good thermal diffusivity, making them a viable alternative to traditional metal current collectors such as lithium, zinc, manganese, and potassium, thereby improving battery energy density and safety. However, the inert surface of dense graphene films and insufficient interlayer sites make it difficult to effectively induce uniform deposition and suppress dendrite growth. Therefore, there is an urgent need to develop a graphene-based anode material that possesses both a self-supporting structure and active energy storage capabilities to achieve the fabrication of high specific capacity, long cycle life, and safe metal batteries. Summary of the Invention

[0006] The purpose of this invention is to provide a laser-etched self-supporting graphene film, its preparation method, and a metal battery, to solve the technical problems commonly found in existing high-capacity anodes, such as uncontrolled volume expansion, dendrite growth, dead lithium formation, and interface instability. This invention, through structural design, enables the graphene film anode material to simultaneously achieve ion intercalation energy storage and metal deposition energy storage, thereby obtaining a metal-free battery anode material with high areal capacity, long cycle life, no dendrites, and low volume expansion. The graphene film of this invention possesses self-supporting, high conductivity, and lightweight properties, and can also be used as a high-performance current collector to replace traditional metal foils in zinc, manganese, and aluminum metal battery systems, further broadening its application range.

[0007] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a laser-etched self-supporting graphene film, comprising the following steps: A layer orientation improver is added to a dispersion containing a graphene film precursor, and the mixture is homogenized to obtain a mixed solution; the graphene film precursor is at least one of graphene oxide and polyimide, and the layer orientation improver is at least one of phenylethylamine and polystyrene sulfonic acid. The mixed solution is coated to form a wet film, which is then dried and peeled off to obtain a graphene oxide film. The graphene oxide film is subjected to high-temperature graphitization treatment to obtain a graphene film. The graphene film is laser-etched to create a vertical through-hole array, resulting in a laser-etched self-supporting graphene film.

[0008] Furthermore, the mass concentration of the graphene film precursor is 20-40 mg / mL. -1 The amount of the sheet orientation improver added is 1 wt.%-5 wt.% of the mass of the dispersion.

[0009] Furthermore, the high-temperature graphitization treatment is carried out at a temperature of 2600-3000℃ for a time of 30-60 min.

[0010] Furthermore, the laser etching is any one of ultraviolet laser etching, visible laser etching, or infrared laser etching.

[0011] Furthermore, the laser etching is ultraviolet laser etching, which uses a pulse frequency of 50-500 kHz, a power of 0.5-5 W, and a laser scanning speed of 10-400 mm / s. -1 The laser-etched pattern consists of an array of circular holes with a diameter of 10-1000 μm.

[0012] Furthermore, the laser etching is infrared laser etching, which uses a pulse frequency of 20-800 kHz, a power of 0.2-5 W, and a laser scanning speed of 50-1000 mm / s. -1 The laser-etched pattern consists of an array of circular holes with a diameter of 10-1000 μm.

[0013] In a second aspect, the present invention provides a laser-etched self-supporting graphene film, which is obtained by any of the preparation methods described above.

[0014] Furthermore, the thickness of the laser-etched self-supporting graphene film is 5-3000 μm.

[0015] In a third aspect, the present invention provides a lithium metal battery or a negative electrode-free lithium metal battery, which uses the laser-etched self-supporting graphene film described above as the negative electrode.

[0016] Furthermore, the positive electrode active material can be any one of lithium manganese oxide, lithium iron phosphate, lithium cobalt oxide, or ternary lithium.

[0017] Compared with the prior art, the present invention has the following technical effects: This invention discloses a method for preparing a laser-etched self-supporting graphene film. By adding a layer orientation improver to the dispersion containing the graphene film precursor, the film-forming quality and interlayer network stability of the graphene film precursor can be improved, significantly enhancing the graphene sheet orientation. This facilitates the construction of a uniform sheet structure and enhances the strength and processability of the resulting graphene film. After the graphene sheet orientation structure is improved, the prepared self-supporting graphene film exhibits superior electrical properties. Furthermore, this invention further utilizes laser etching to form uniformly distributed micropore channels or active sites on and inside the graphene film, thereby achieving spatial optimization of the electrode structure and homogenization of the reaction interface. The through-holes penetrate the entire graphene film in the thickness direction, forming a continuous three-dimensional vertical conductive structure, significantly improving ion diffusion rate and electron transport capability. In addition, during the laser etching process, vacancies, oxygen-containing and nitrogen-containing functional groups, and other active defects are formed in the edge region of the pores. In the early stages of electrochemical cycling, these defective active sites can undergo intercalation reactions with lithium ions, generating LiC with intrinsic lithiophilic activity in situ. x (NaC) x KC x The skeletal structure uniformly induces lithium nucleation and deposition during subsequent charge and discharge processes, effectively suppressing dendrite formation and stabilizing the electrode interface, thus realizing a hybrid lithium storage mechanism. The laser-etched self-supporting graphene film of this invention is lightweight, highly conductive, and exhibits excellent mechanical stability. It is compatible with ether-based, carbonate-based, and other systems, making it suitable for various high-energy-density metal battery designs.

[0018] The laser-etched self-supporting graphene film of the present invention can be used as the negative electrode of lithium metal battery or negative electrodeless lithium metal battery. It can store energy and guide uniform metal deposition and efficient stripping, effectively suppress dendrite growth and improve cycle stability and coulombic efficiency, and has the advantages of high areal capacity and long cycle life. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 X-ray scattering images of the graphene oxide film and the pure graphene oxide film in Example 1 of the present invention; Figure 2 This is a scanning electron microscope image of the surface of the laser-etched self-supporting graphene film prepared in Example 1 of the present invention; Figure 3 This is a cross-sectional scanning electron microscope image of the laser-etched self-supporting graphene film prepared in Example 1 of the present invention; Figure 4 Raman spectra of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching. Figure 5 Comparison of X-ray diffraction patterns of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching. Figure 6 Comparison of X-ray photoelectron spectra of the laser-etched self-supporting graphene film prepared in Example 1 of the present invention and the graphene film before laser etching. Figure 7 Comparison of X-ray diffraction patterns of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching after discharge to 0 V; Figure 8 The images show the surface and cross-sectional scanning electron microscope (SEM) images of the laser-etched self-supporting graphene film anode prepared in Example 1 of this invention after deposition of 4 mAh lithium metal. Figure 9 The image shows a comparison of the coulombic efficiency of the laser-etched self-supporting graphene film prepared in Example 1 of this invention, the graphene film before laser etching, and the copper foil for lithium-ion assembled half-cells. Figure 10 The charge-discharge curves of the laser-etched self-supporting graphene film anode and the lithium-assembled half-cell prepared in Example 1 of this invention are shown. Figure 11The graph shows a comparison of the rate performance of the laser-etched self-supporting graphene film anode, the graphene film and copper foil before laser etching, and the high-load lithium iron phosphate cathode assembled into a full cell, as shown in Example 1 of this invention. Figure 12 The graph shows a comparison of the cycle performance of a laser-etched self-supporting graphene film anode, the graphene film and copper foil before laser etching, and a high-load lithium iron phosphate cathode assembled into a full cell, as shown in Example 1 of this invention. Detailed Implementation

[0021] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0022] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0023] Example 1 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1 Phenylethylamine (PEA) was added at a mass fraction of 3 wt.% to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and peeled off to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using a UV laser etching device. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting sample was used as the anode of the laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3. As a control group, un-laser-etched graphene films (i.e., pristine graphene films) and copper foil (Cu) were used for testing.

[0024] Example 2 In this embodiment, polyimide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The polyimide dispersion (with a polyimide mass concentration of 30 mg / mL) was then prepared. -1 Phenylethylamine (PEA) was added at a mass fraction of 3 wt.% to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and exfoliated to obtain a large-area graphene oxide film. After heat treatment at 3000 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using a UV laser etching system. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting sample was used as the anode of a laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full-cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3.

[0025] Example 3 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1 Phenylethylamine (PEA) was added at a mass fraction of 3 wt.% to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and exfoliated to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using an infrared laser etching device. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting sample was used as the anode of a laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full-cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3.

[0026] Example 4 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1To improve film uniformity and precursor sheet stability, 3 wt.% phenylethylamine (PEA) was added to the solution. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and peeled off to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, the film was compacted by rolling at 200 MPa to obtain a graphene film with a thickness of approximately 20 μm. The graphene film was then perforated using a UV laser etching system. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting sample was used as the anode of a laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full-cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3.

[0027] Example 5 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1 Phenylethylamine (PEA) was added at a mass fraction of 3 wt.% to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and exfoliated to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using a UV laser etching system. The laser parameters were: frequency 50 Hz, power 5 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting laser-etched self-supporting graphene film was used as the negative electrode current collector, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate positive electrode to form a full cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3.

[0028] Example 6 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1Phenylethylamine (PEA) was added at a mass fraction of 3 wt.% to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and peeled off to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using a UV laser etching device. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 500 μm. The resulting sample was used as the anode of the laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3. As a control group, tests were conducted using untreated graphene film (GF) and copper foil (Cu), and the laser-etched self-supporting graphene film anode performed better than the control group.

[0029] Example 7 In this embodiment, graphene oxide was selected as the precursor for preparing the laser-etched self-supporting graphene film anode. The graphene oxide dispersion (with a graphene oxide mass concentration of 30 mg / mL) was then added. -1 3 wt.% polystyrene sulfonic acid (PSS) was added to the mixture to improve film uniformity and precursor sheet stability. The homogenized graphene oxide precursor mixture was coated to form a wet film, which was then dried at 70 °C and peeled off to obtain a large-area graphene oxide film. After heat treatment at 2900 °C for 30 min, a graphene film with a thickness of approximately 100 μm was obtained. The graphene film was then perforated using a UV laser etching system. The laser parameters were: frequency 50 Hz, power 2 W, and scanning speed 100 mm·s. -1 The laser-etched pattern consisted of a periodic array of circular vias with a diameter of 100 μm and a spacing of 100 μm. The resulting sample was used as the anode of the laser-etched self-supporting graphene film, assembled with lithium metal foil to form a half-cell, and with a commercial lithium iron phosphate cathode to form a full cell. The electrolyte was a commercial 1.0 M LiTFSI (DME:DOL = 1:1 v / v) + 1 wt% LiNO3. As a control group, tests were conducted using untreated graphene film (GF) and copper foil (Cu), and the laser-etched self-supporting graphene film anode performed better than the control group.

[0030] Example 8 The difference between this and Example 1 is that the high-temperature heat treatment temperature is increased from 2900 ℃ to 3000 ℃, while the other steps remain unchanged.

[0031] Figure 1 The X-ray scattering pattern of the graphene oxide film of Example 1 of the present invention is shown. Furthermore, as a comparison, the present invention also provides an X-ray scattering pattern of a pure graphene oxide film, i.e., a pure graphene oxide film obtained by drying a wet film without the addition of phenylethylamine to the dispersion at 70 °C and then peeling it off. Figure 1 As observed, the graphene oxide film of Example 1 exhibits a clearer equatorial fringe scattering characteristic in the small-angle X-ray scattering pattern, and its intensity distribution in the azimuth direction is significantly narrowed, indicating a significant enhancement in the orientation of its graphene oxide sheets. In contrast, the orientation distribution of the pure graphene oxide film without the addition of phenylethylamine modifier is more dispersed. Further comparison with the sintered graphene film shows that the improved orientation of the graphene oxide film is beneficial for forming a graphene film with higher orientation, better structure, and better electrical properties during high-temperature processing.

[0032] Figure 2 This is a scanning electron microscope (SEM) image of the surface of the laser-etched self-supporting graphene film prepared in Example 1 of this invention. Figure 3 This is a cross-sectional scanning electron microscope (SEM) image of the laser-etched self-supporting graphene film prepared in Example 1 of this invention. From... Figure 2 , Figure 3 As observed, the laser-etched self-supporting graphene film exhibits a regular array of through-hole structures, with abundant interlayer voids inside the film, resulting in a uniform overall structure and good mechanical stability.

[0033] Figure 4 The images show the Raman spectra of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching. Figure 4 As seen in the image, the graphene film before laser etching, i.e., the original graphene film (GF), has an I... D / I G The ratio was 0.02, while the ratio increased to 0.18 in the un-perforated area after laser etching, and further increased to 0.7 at the hole edge, indicating that the laser etching process significantly increased the defect density.

[0034] Figure 5 This is a comparison of the X-ray diffraction patterns of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching. Figure 5 As observed, the (002) peak of GF is located at 26.6° (interlayer spacing 3.35 Å), while the (002) peak of the laser-etched sample is slightly shifted to a lower angle (interlayer spacing approximately 3.36 Å), indicating that the interlayer spacing is slightly increased, providing more lithium insertion sites.

[0035] Figure 6 This is a comparison of the X-ray photoelectron spectra of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching. Figure 6 The study observed that the C content in the laser-etched self-supporting graphene film was 82.2%, while the O and N contents were 4.4% and 13.4%, respectively, which were significantly higher than those in the original GF. The C1s spectrum showed enhanced peaks for C=O (288.6 eV), C–O (286.5 eV), and C–N (285.6 eV), and a vacancy-type defect characteristic peak appeared at 283.7 eV, proving that laser etching introduced heteroatom functional groups and vacancy defects on the film surface while forming through-holes, which is beneficial for forming a lithiophilic framework structure that homogenizes ion transport and current density.

[0036] Figure 7 This is a comparison of the X-ray diffraction patterns of the laser-etched self-supporting graphene film prepared in Example 1 of this invention and the graphene film before laser etching, after being discharged to 0 V. Figure 7 The X-ray diffraction analysis of the laser-etched self-supporting graphene film anode after discharge to 0 V revealed the presence of LiC and LiC after discharge. 12 LiC 24 The presence of diffraction peaks such as LiC6 indicates that a relatively deep LiC layer was formed during the lithium intercalation process. x The structure indicates that the vacancies and heteroatom defects introduced by laser etching effectively promote the intercalation of lithium ions between graphene layers, transforming the graphene framework in situ into LiC with high lithium conductivity. x frame.

[0037] Figure 8 These are scanning electron microscope (SEM) images of the surface and cross-section of the laser-etched self-supporting graphene film anode prepared in Example 1 of this invention after deposition of 4 mAh lithium metal. Figure 8 The results show that even with high areal capacity, the laser-etched self-supporting graphene film anode still provides a stable and uniform reaction interface for subsequent lithium metal deposition.

[0038] Figure 9 This is a comparison of the coulombic efficiencies of the laser-etched self-supporting graphene film prepared in Example 1 of this invention, the graphene film before laser etching, and the copper foil, respectively, for lithium-ion assembled half-cells. Figure 9 As observed, the half-cell assembled using a laser-etched self-supporting graphene film anode exhibits excellent cycle stability and high reversibility. Compared with the original graphene film and copper foil control samples, the laser-etched self-supporting graphene film anode prepared in Example 1 of this invention maintains stable coulombic efficiency during long-term cycling without significant fluctuations, demonstrating good lithium deposition / stripping reversibility and electrochemical stability.

[0039] Figure 10 This is a charge-discharge curve of a laser-etched self-supporting graphene film anode and a lithium-assembled half-cell prepared in Example 1 of this invention. Figure 10As observed, the negative electrode exhibits a distinct two-stage reaction behavior during charge and discharge. Initially, lithium-ion intercalation occurs to form LiC. x A framework was constructed, and then lithium metal was deposited on the framework. During the discharge process, the LiC... x The structure enables solid-state conversion of residual lithium, significantly reducing the accumulation of "dead lithium" and improving reversible efficiency. Thus, the laser-etched self-supporting graphene film prepared in Example 1 of this invention forms a self-converting active lithium storage framework during discharge, achieving a synergistic lithium storage mechanism of lithium-ion intercalation and metallic lithium deposition, while maintaining low polarization and a stable interface even under long-term cycling.

[0040] Figure 11 This is a comparison of the rate performance of a full cell assembled with a laser-etched self-supporting graphene film anode, the graphene film before laser etching, and the copper foil, and a high-load lithium iron phosphate cathode, prepared in Example 1 of this invention. Figure 11 As observed, the laser-etched self-supporting graphene film anode can operate stably between 0.1 C and 5 C, and still maintains 93.6 mAh g⁻¹ at a high rate of 5 C. -1 Its reversible capacity is much higher than that of GF (42.0 mAh g-1) and Cu (18.5 mAh g-1).

[0041] Figure 12 This image shows a comparison of the cycle performance of a full cell assembled with a laser-etched self-supporting graphene film anode, the graphene film before laser etching, and the copper foil, compared to a high-load lithium iron phosphate cathode, as prepared in Example 1 of this invention. Figure 12 As observed, after 500 cycles, the laser-etched self-supporting graphene film anode still retains about 45% of its initial capacity, and the coulombic efficiency remains stable at 99.9%, proving that the laser-etched graphene film anode still possesses excellent structural integrity and cycle life under high load and high rate conditions.

[0042] Compared with Example 1, Example 3 uses infrared laser for laser etching. Due to the obvious thermal effect of infrared laser, burrs and thermal damage appear at the edges of the etched holes, affecting the mechanical stability of the self-supporting graphene film.

[0043] Compared with Example 1, Example 4 shows that the thickness of the graphene film is reduced after rolling, which may reduce the energy and time required for laser drilling and enhance the film flexibility. However, the areal capacity is slightly reduced due to the lack of interlayer sites.

[0044] Compared with Example 1, Example 5 shows that the laser etching power is increased, resulting in more burrs at the edge of the etched hole, enhanced heat accumulation, increased carbonization of the hole wall, and a slight decrease in the mechanical strength of the self-supporting graphene film.

[0045] Compared with Example 1, Example 6 shows that the increased spacing between laser-etched holes reduces hole density, decreases defect density, and reduces areal capacity, thus affecting the uniformity of lithium metal deposition and electrochemical stability.

[0046] Compared with Example 1, Example 7 uses polystyrene sulfonic acid as a sheet orientation improver. Since PSS has a weaker ability to regulate the viscoelasticity of the film, the sheet orientation and defect uniformity decrease, which in turn makes the capacity and cycle stability of the laser-etched self-supporting graphene film prepared lower than those of Example 1.

[0047] Compared with Example 1, increasing the graphitization temperature in Example 8 may lead to partial distortion of the graphene crystal structure and a decrease in the thermal diffusivity, resulting in a slight decrease in the electrochemical performance of the laser-etched self-supporting graphene film anode.

[0048] In this invention, a laser-etched self-supporting graphene film anode was assembled with a high-load lithium iron phosphate cathode to form a pouch cell for performance verification. The results showed that the cell could still function normally under mechanical deformation conditions such as bending and curling, exhibiting good flexibility and structural stability. Furthermore, the assembled cell demonstrated excellent rate performance and mechanical flexibility.

[0049] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for preparing a laser-etched self-supporting graphene film, characterized in that, Includes the following steps: A layer orientation improver is added to a dispersion containing a graphene film precursor, and the mixture is homogenized to obtain a mixed solution; the graphene film precursor is at least one of graphene oxide and polyimide, and the layer orientation improver is at least one of phenylethylamine and polystyrene sulfonic acid. The mixed solution is coated to form a wet film, which is then dried and peeled off to obtain a graphene oxide film. The graphene oxide film is subjected to high-temperature graphitization treatment to obtain a graphene film. The graphene film is laser-etched to create a vertical through-hole array, resulting in a laser-etched self-supporting graphene film.

2. The method for preparing a laser-etched self-supporting graphene film as described in claim 1, characterized in that, The mass concentration of the graphene film precursor is 20-40 mg / mL. -1 The amount of the sheet orientation improver added is 1 wt.%-5 wt.% of the mass of the dispersion.

3. The method for preparing a laser-etched self-supporting graphene film as described in claim 1, characterized in that, The high-temperature graphitization treatment is carried out at a temperature of 2600-3000℃ for a time of 30-60 minutes.

4. The method for preparing a laser-etched self-supporting graphene film as described in claim 1, characterized in that, The laser etching is any one of ultraviolet laser etching, visible laser etching, or infrared laser etching.

5. The method for preparing a laser-etched self-supporting graphene film as described in claim 4, characterized in that, The laser etching is ultraviolet laser etching, using a pulse frequency of 50-500 kHz, a power of 0.5-5 W, and a laser scanning speed of 10-400 mm / s. -1 The laser-etched pattern consists of an array of circular holes with a diameter of 10-1000 μm.

6. The method for preparing a laser-etched self-supporting graphene film as described in claim 4, characterized in that, The laser etching is infrared laser etching, which uses a pulse frequency of 20-800 kHz, a power of 0.2-5 W, and a laser scanning speed of 50-1000 mm / s. -1 The laser-etched pattern consists of an array of circular holes with a diameter of 10-1000 μm.

7. A laser-etched self-supporting graphene film, characterized in that, It is obtained by the preparation method described in any one of claims 1-6.

8. The laser-etched self-supporting graphene film as described in claim 7, characterized in that, The thickness of the laser-etched self-supporting graphene film is 5-3000 μm.

9. A lithium metal battery or a negative electrode-free lithium metal battery, characterized in that, The laser-etched self-supporting graphene film described in claim 7 was used as the negative electrode.

10. A lithium metal battery or a negative electrode-free lithium metal battery as described in claim 9, characterized in that, The positive electrode active material can be any one of lithium manganese oxide, lithium iron phosphate, lithium cobalt oxide, or ternary lithium.

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