Metallo-naphthalocyanine-graphene oxide composite material, preparation method and application thereof

Abstract

The application provides a metal naphthalene phthalocyanine-graphene oxide composite material and a preparation method and application thereof, belongs to the field of chemical engineering, and is a nitrogen-doped graphene porous composite material modified by metal oxide particles obtained by bonding of tetra-t-butyl metal naphthalene phthalocyanine and graphene oxide. When the material is used as a negative electrode material of a lithium ion battery, the cycle performance and rate performance of the lithium ion battery can be significantly improved, so that an electrode material with high capacity and good cycle performance is obtained, the material has good application potential in the field of lithium ion batteries, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a metal naphthalene phthalocyanine-graphene oxide composite material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries (LIBs) possess characteristics such as high energy density, long cycle life, and environmental friendliness, making them important and widely used in portable electronic devices, electric vehicles, mobile communications, and smart grids. However, currently, most commercially available anode materials for lithium-ion batteries are graphite, which has relatively low capacity and cannot meet the growing demand for lithium-ion batteries, hindering their further development.

[0003] To address capacity issues, transition metal oxides (TMOs) have been extensively studied as promising anode materials. TMOs not only possess high theoretical capacity, low preparation cost, and simple manufacturing processes, but are also environmentally friendly and highly safe, meeting the future requirements of lithium-ion battery development. However, while TMOs exhibit excellent lithium storage capacity, they are often accompanied by significant volume changes and particle fragmentation during charging and discharging, leading to rapid capacity decay and deterioration in cycle performance. Additionally, graphene, due to its large specific surface area, excellent conductivity, and outstanding carrier mobility, has become a popular anode material for lithium-ion batteries. However, its high aspect ratio results in long lithium-ion transport paths and a tendency for aggregation, similarly limiting its application in lithium-ion batteries.

[0004] To address the above issues, developing metal oxide / carbon composites is considered a promising approach. Currently, the preparation of metal oxide / carbon composites typically involves methods such as directly mixing a metal salt aqueous solution with a GO (graphene oxide) solution, followed by hydrothermal reduction to obtain a metal oxide / reduced graphene oxide composite, which is then used as a negative electrode in lithium-ion batteries (Mai YJ, Wang XL, Xiang JY, et al. CuO / graphene composite as anode materials for lithium-ion batteries[J]. Electrochimica Acta, 2011, 56(5):2306-2311.). However, this method struggles to ensure uniform distribution of metal oxides on the graphene surface, and GO tends to aggregate during stirring and reduction, reducing its specific surface area. Introducing nitrogen atoms into the graphene framework can enhance the electrochemical performance of the material (Sheng ZH, Shao L, Chen JJ, et al. Catalyst-free synthesis of nitrogen-doped graphene via thermalannealing graphite oxide with melamine and its excellent electrocatalysis[J]. ACS nano, 2011, 5(6): 4350-4358.), but the steps to obtain metal oxide / nitrogen-doped graphene are relatively complicated. It is necessary to first dope the graphene and then introduce the metal oxide through the above methods; metal oxide / nitrogen-doped carbon materials can be directly obtained by high-temperature calcination of metal phthalocyanine compounds and graphene oxide (Xiao Huimin, Preparation and Performance Study of Anode Materials Based on Organometallic Compounds, University of Electronic Science and Technology of China, 2018.). Metal oxide / nitrogen-doped graphene anode materials can be obtained by compositing copper phthalocyanine and nickel phthalocyanine with graphene oxide and calcining at high temperature. Of the two schemes, one scheme does not introduce air during calcination and cooling, resulting in a composite of metallic copper and graphene. The other scheme introduces air during calcination and cooling to 450°C, resulting in a composite of copper oxide (nickel oxide) / graphene. However, the capacity of the active material is limited by factors such as the small size of the phthalocyanine conjugated structure and the types of metal atoms at the center of the complex. The highest initial discharge capacity at 0.1C is only 1056.6 mAh / g, and when the initial discharge capacity at 0.1C is 920 mAh / g, it remains at around 400 mAh / g after 100 cycles.

[0005] Therefore, the development of high-performance anode materials is crucial for the development of next-generation lithium-ion batteries. This invention proposes to carbonize metal naphthalene phthalocyanine as a single source of metal oxides and nitrogen-doped carbon materials. Currently, the preparation of metal naphthalene phthalocyanine compounds usually uses quinoline (Chen Liyuan, Synthesis of Vanadium Oxynaphthalene Phthalocyanine Compounds with Near-Infrared Absorption Properties, East China University of Science and Technology, 2014.) or n-pentanol (Liu Ying, Zuo Xia, Wu Yiqun et al. Synthesis and Nonlinear Optical Constriction Characteristics of Tetrabromo-2,3-Naphthalene Phthalocyanine Zinc (II) [J]. Applied Chemistry, 2000(05):569-571.) as reaction solvents. However, the former, quinoline, has a strong odor and a high boiling point, making it difficult to separate the product from the reaction system. The latter, n-pentanol, has a low boiling point, making it difficult to reach a high temperature during the reaction, and the reaction is difficult to proceed completely. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a metal naphthalene phthalocyanine-graphene oxide composite material, its preparation method, and its application. By calcining tetra-tert-butyl metal naphthalene phthalocyanine with graphene oxide, a nitrogen-doped graphene porous composite material modified with metal oxide particles can be obtained. The reaction process is green and environmentally friendly. When this composite material is used in lithium-ion batteries, it can significantly improve the cycle performance and rate performance of lithium-ion batteries.

[0007] The technical solution of this invention is as follows:

[0008] A metal-naphthalene phthalocyanine-graphene oxide composite material is a nitrogen-doped porous graphene composite material modified with metal oxide particles, formed by bonding tetra-tert-butyl metal-naphthalene phthalocyanine with graphene oxide. The XRD pattern of this metal-naphthalene phthalocyanine-graphene oxide composite material shows characteristic peaks of reduced graphene oxide and diffraction peaks of metal oxide located at 2θ = 25.6°–25.8°. The Raman spectrum shows I... D / I G The value is 1.02–1.06, indicating a higher defect level than that of pristine graphene oxide (I). D / I G =0.68); characteristic peaks of C, N, O and metal elements appeared in the XPS spectrum.

[0009] Preferably, the tetra-tert-butylnaphthalene phthalocyanine is tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper, the structural formula of the tetra-tert-butylnaphthalene phthalocyanine zinc is shown in formula (I), and the structural formula of the tetra-tert-butylnaphthalene phthalocyanine copper is shown in formula (II).

[0010]

[0011] Preferably, the mass ratio of the tetra-tert-butylnaphthalene phthalocyanine zinc to graphene oxide is 5:1.

[0012] Preferably, the mass ratio of the tetra-tert-butylnaphthalene phthalocyanine copper to graphene oxide is 1:1.

[0013] The preparation method of the metal naphthalene phthalocyanine-graphene oxide composite material includes the following steps:

[0014] (1) Preparation of tetra-tert-butylnaphthalene phthalocyanine: Using n-heptanol as the reaction solvent, 6-tert-butyl-2,3-dicyanonaphthalene was added to the reaction flask, followed by 1,8-diazabicycloundec-7-ene, zinc acetate or cuprous chloride. The mixture was stirred and heated to reflux for 10-14 h to obtain the reaction solution. The reaction solution was cooled to 140-150 °C and distilled under reduced pressure until more than 2 / 3 of the total reaction solution volume was distilled off. Methanol was added and refluxed for 1-1.5 h. After reflux, the liquid was cooled to 25-30 °C and filtered. The solution was then washed with methanol and water in sequence and freeze-dried to obtain tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper.

[0015] (2) Dissolve the tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper from step (1) in N,N-dimethylformamide, sonicate to dissolve, then add graphene oxide aqueous solution, stir at room temperature for 20-28h to obtain reaction solution; filter and collect the solid reactants in the reaction solution, wash with water and freeze dry to obtain metal naphthalene phthalocyanine-graphene oxide composite material precursor;

[0016] (3) The metal naphthalene phthalocyanine-graphene oxide composite material precursor in step (2) was calcined at high temperature in an inert gas atmosphere for 8 hours at 800°C. After calcination, the temperature was lowered to 500-550°C and air was introduced to obtain the metal naphthalene phthalocyanine-graphene oxide composite material.

[0017] Preferably, in step (1), the molar ratio of 6-tert-butyl-2,3-dicyanonaphthalene, 1,8-diazabicycloundec-7-ene and zinc acetate is 4:3.15:1 to 1.05.

[0018] Preferably, in step (1), the molar ratio of 6-tert-butyl-2,3-dicyanonaphthalene, 1,8-diazabicycloundec-7-ene and cuprous chloride is 4:3.15:1 to 1.05.

[0019] Preferably, the calcination method in step (3) is to load the metal naphthalene phthalocyanine-graphene oxide composite material precursor into a ceramic boat and place it in a tube muffle furnace for calcination.

[0020] Preferably, the inert gas in step (3) is Ar.

[0021] Application of the metal naphthalene phthalocyanine-graphene oxide composite material in lithium-ion batteries.

[0022] A negative electrode material for lithium-ion batteries is prepared from the aforementioned metal naphthalene phthalocyanine-graphene oxide composite material.

[0023] The negative electrode material has an initial discharge capacity of 1431.2–1942.9 mAh / g at a current density of 100 mA / g, and a discharge specific capacity of 655.0–867.3 mAh / g after 60 charge-discharge cycles.

[0024] Preferably, it is used as a negative electrode material in lithium-ion batteries.

[0025] On the one hand, the present invention uses n-heptanol as a solvent in the preparation process of metal naphthalene phthalocyanine, which can maintain environmental cleanliness while increasing the reaction temperature and making the reaction more thorough, and avoid using solvents with strong odors.

[0026] On the other hand, the tetra-tert-butyl metal naphthalene phthalocyanine prepared in this invention has a unique large π-conjugated structure compared with traditional phthalocyanine materials, which is more conducive to electron conduction. The tert-butyl group can improve the solubility of naphthalene phthalocyanine, making it easier for naphthalene phthalocyanine to combine with graphene oxide. In the process of combining with monolayer graphene oxide, tetra-tert-butyl metal naphthalene phthalocyanine will be combined with each other by π-π stacking interaction. This interaction can not only prevent the aggregation of naphthalene phthalocyanine molecules and make them uniformly dispersed on the surface of graphene oxide, but also promote the separation of graphene oxide sheets.

[0027] In the preparation process of the metal naphthalene phthalocyanine-graphene oxide composite material described in this invention, a template-assisted method is employed: under high-temperature calcination conditions, metal naphthalene phthalocyanine grows along the surface of graphene oxide, forming a sheet-like structure similar to graphene; furthermore, metal naphthalene phthalocyanine releases divalent metal ions Zn during pyrolysis. 2+ or Cu 2+ At high temperatures, graphene oxide is reduced to monomers Zn or Cu. During the cooling process, Zn or Cu is oxidized again, eventually forming metal oxides ZnO or CuO. In addition, under high-temperature calcination conditions, graphene oxide is reduced at high temperatures, removing most of the oxygen-containing functional groups, increasing the degree of defects, thereby increasing the number of active sites. Furthermore, nitrogen atoms produced by the decomposition of metal naphthalene phthalocyanine enter the graphene network, forming nitrogen-doped graphene.

[0028] Therefore, the present invention obtains a nitrogen-doped graphene porous composite material modified with metal oxide particles by calcination. The presence of metal oxide can shorten the lithium-ion transport path and improve conductivity. The sheet structure of graphene can also suppress the volume expansion of metal oxide during lithiation / delithiation, preventing its separation and aggregation.

[0029] Beneficial effects:

[0030] The present invention has a simple preparation process, is easy to operate, and the reaction process is green and environmentally friendly. It prepares a nitrogen-doped graphene porous composite material modified with metal oxide particles. When used as a negative electrode material for lithium-ion batteries, it can significantly improve the cycle performance and rate performance of lithium-ion batteries, thereby obtaining an electrode material with high capacity and good cycle performance. It has good application potential in the field of lithium-ion batteries and is suitable for industrial production. Attached Figure Description

[0031] Figure 1 The X-ray diffraction pattern of the naphthalene phthalocyanine copper-graphene oxide composite material in Example 1 is shown below.

[0032] Figure 2 The Raman spectrum of the naphthalene phthalocyanine copper-graphene oxide composite material in Example 1;

[0033] Figure 3 The image shows the SEM image of the naphthalene phthalocyanine copper-graphene oxide composite material in Example 1.

[0034] Figure 4 The TEM image of the naphthalene phthalocyanine copper-graphene oxide composite material in Example 1;

[0035] Figure 5 The XPS spectrum of the naphthalene phthalocyanine copper-graphene oxide composite material in Example 1;

[0036] Figure 6 The graph shows the cycle performance of the naphthalene phthalocyanine copper-graphene oxide composite material used as a negative electrode material in Example 1.

[0037] Figure 7 This is a rate performance diagram of the naphthalene phthalocyanine copper-graphene oxide composite material used as a negative electrode material in Example 1.

[0038] Figure 8 The X-ray diffraction pattern of the zinc phthalocyanine-graphene oxide composite material in Example 6;

[0039] Figure 9 The Raman spectrum of the zinc phthalocyanine-graphene oxide composite material in Example 6;

[0040] Figure 10 The image shows the SEM image of the zinc phthalocyanine-graphene oxide composite material in Example 6.

[0041] Figure 11 The TEM image of the naphthalene phthalocyanine zinc-graphene oxide composite material in Example 6;

[0042] Figure 12 XPS spectra of the naphthalene phthalocyanine zinc-graphene oxide composite material in Example 6;

[0043] Figure 13 The graph shows the cycle performance of the naphthalene phthalocyanine zinc-graphene oxide composite material used as a negative electrode material in Example 6.

[0044] Figure 14 The graph shows the rate performance of the naphthalene phthalocyanine zinc-graphene oxide composite material used as the negative electrode material of a lithium-ion battery in Example 6. Detailed Implementation

[0045] The following description is based on specific embodiments:

[0046] Example 1:

[0047] Preparation of Naphthalenephthalocyanine Copper-Graphene Oxide Composite Material

[0048] (1) Add 2.34 g of 6-tert-butyl-2,3-dicyanonaphthalene to a 250 mL round-bottom flask, then add 1.2 g of 1,8-diazabicycloundec-7-ene (DBU) and 0.26 g of cuprous chloride. Use 50 mL of n-heptanol as the reaction solvent, stir, and slowly heat to reflux for 12 h to obtain the reaction solution. Cool the reaction solution to 145 °C, and distill under reduced pressure until 2 / 3 of the total reaction solution volume is distilled off. Add 30 mL of methanol and reflux for 1 h. After reflux, let the liquid cool to 25 °C and filter. Then wash with methanol and water in sequence, freeze dry to obtain 1.61 g of tetratert-butylnaphthalene copper phthalocyanine (CuNc).

[0049] (2) Dissolve 0.1g of tetra-tert-butylnaphthalene copper phthalocyanine from step (1) in 30mL of N,N-dimethylformamide, sonicate to dissolve, then add 25mL of GO aqueous solution (graphene oxide aqueous solution) with a concentration of 4mg / mL, stir at room temperature for 24h to obtain a reaction solution; filter and collect the solid reactants in the reaction solution, wash with a large amount of deionized water, freeze dry to obtain the precursor of naphthalene copper phthalocyanine-graphene oxide composite material;

[0050] (3) The naphthalene phthalocyanine copper-graphene oxide composite material precursor from step (2) was loaded into a ceramic boat and placed in a tube muffle furnace. It was calcined at high temperature under Ar atmosphere for 800℃ for 8 hours. After calcination, the temperature was lowered to 530℃ and air was introduced to obtain the naphthalene phthalocyanine copper-graphene oxide composite material.

[0051] The naphthalene phthalocyanine copper-graphene oxide composite material prepared in Example 1 was subjected to XRD (X-ray diffraction), Raman (Raman scattering), SEM (scanning electron microscopy), TEM (transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy) measurements, respectively. The test spectra are shown below. Figures 1-5 As shown.

[0052] Figure 1The X-ray diffraction pattern shows a broad peak at 2θ = 25.8°, indicating that graphene oxide was reduced to reduced graphene oxide after high-temperature annealing. Cu atoms released from the high-temperature decomposition of CuNc were oxidized. The characteristic reflections (-110), (002), (111), (200), (-112), (-202), (112), (020), (202), (-113), (022), (-311), (113), (-220), (311), (004), and (-222) in the resulting composite material correspond to monoclinic CuO (JCPSD PDF#:45-0937).

[0053] Figure 2 Raman spectroscopy is the most direct technique used to determine the degree of defects, order, and disorder in graphite materials. For example... Figure 2 As shown, the graphite material at 1337cm -1 and 1597cm -1 Significant peaks appear nearby, corresponding to the D-band and G-band, respectively; the D-band indicates the degree of disorder and defects in the structure, while the G-band can be used to interpret the degree of graphitization. Therefore, the intensity ratio (Ig) of the D-band and G-band is usually used. D / I G To characterize defects in GO or graphene, the original GO and the composite material's I D / I G They are 0.68 and 1.06 respectively. (By...) Figure 2 It can be seen that as the disorder of graphite materials increases, the carbon in the composite material contains more defects, and lithium ions can diffuse vertically from the outside of the graphite layer to the inside of the graphite layer through these defects, thereby providing more storage areas.

[0054] Figure 3 The SEM images show that the prepared composite material has a relatively uniform morphology and exhibits an overall sheet-like structure. This is because the naphthalene phthalocyanine compounds bind together with monolayer graphene oxide through π-π stacking interactions during mixing. This interaction not only prevents the aggregation of naphthalene phthalocyanine molecules, ensuring their uniform dispersion on the graphene oxide surface, but also promotes the separation of graphene oxide sheets. During pyrolysis, this special structure allows copper naphthalene phthalocyanine to grow along the graphene surface, forming a graphene-like sheet-like structure. Furthermore, numerous irregular particles can be observed on the graphene surface, which is due to the release of Cu during the pyrolysis of copper naphthalene phthalocyanine. 2+ Cu 2+ After being reduced to Cu monomer, it is oxidized again to eventually form CuO, which provides a buffer matrix to mitigate the volume changes caused by electrochemical cycling.

[0055] Figure 4The image is a TEM image. By observing the morphology of the composite material through TEM, it was found that the graphene exhibits a wrinkled, paper-like structure, with CuO particles distributed on the graphene.

[0056] Figure 5 The image shows an XPS spectrum, an effective surface chemical analysis technique that reveals the elemental composition and chemical state of a surface. As can be seen from the image, four typical peaks appear at 285 eV, 401 eV, 532 eV, and 934 eV, corresponding to C1s, N 1s, O 1s, and Cu 2p, respectively.

[0057] The naphthalene phthalocyanine copper-graphene oxide composite material prepared in Example 1 was used as the negative electrode material for a lithium-ion battery for electrochemical performance testing. The test results are as follows: Figures 6-7 As shown, where Figure 6 The graph shows the cycling performance of the naphthalene phthalocyanine copper-graphene oxide composite material. Figure 7 This is a rate performance diagram of the naphthalene phthalocyanine copper-graphene oxide composite material.

[0058] Depend on Figure 6 It can be seen that the initial discharge capacity at a current density of 100 mA / g is 1431.2 mAh / g, and after 100 charge-discharge cycles, its discharge specific capacity is 655.0 mAh / g. This indicates that it can significantly improve the cycle performance of lithium-ion batteries when used as a negative electrode material.

[0059] Depend on Figure 7 It can be seen that at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, and 1 A / g, the discharge capacities of the electrode are 591.4 mAh / g, 480.9 mAh / g, 371.7 mAh / g, and 309.4 mAh / g, respectively. When the current density returns to 0.1 A / g, the discharge capacity of the electrode recovers to 615.7 mAh / g. This indicates that when used as a negative electrode material for lithium-ion batteries, it can significantly improve the rate performance of lithium-ion batteries, thereby obtaining an electrode material with high capacity and good cycle performance.

[0060] Comparative Examples 2-5:

[0061] The only difference between Comparative Examples 2-5 and Example 1 is the mass ratio of tetra-tert-butylnaphthalene copper phthalocyanine to graphene oxide. The naphthalene copper phthalocyanine-graphene oxide composite materials prepared in Comparative Examples 2-5 were used as negative electrode materials for lithium-ion batteries for electrochemical performance testing. The specific settings and electrochemical test results of each comparative example are shown in Table 1 below.

[0062] Table 1. Setup of Comparative Examples 2–5 and Electrochemical Test Results of Their Products

[0063]

[0064] As shown in Table 1, Comparative Examples 2–5 varied the mass ratio of tetra-tert-butylnaphthalene copper phthalocyanine to graphene oxide, and the tested lithium-ion batteries exhibited poor cycle performance and rate performance. This indicates that the performance is optimal when the mass ratio of tetra-tert-butylnaphthalene copper phthalocyanine to graphene oxide is 1:1.

[0065] Example 6:

[0066] Preparation of Naphthalene Phthalocyanine Zinc-Graphene Oxide Composite Material

[0067] (1) Add 2.34 g of 6-tert-butyl-2,3-dicyanonaphthalene to a 250 mL round-bottom flask, then add 1.2 g of 1,8-diazabicycloundec-7-ene (DBU) and 0.482 g of zinc acetate. Use 50 mL of n-heptanol as the reaction solvent, stir, and slowly heat to reflux for 12 h to obtain the reaction solution. Cool the reaction solution to 150 °C, and distill under reduced pressure until 2 / 3 of the total reaction solution volume is distilled off. Add 30 mL of methanol and reflux for 1 h. After reflux, let the liquid cool to 30 °C and filter. Then wash with methanol and water in sequence, freeze dry to obtain 1.52 g of tetratert-butylnaphthalene zinc phthalocyanine (ZnNc).

[0068] (2) Dissolve 0.5g of tetra-tert-butylnaphthalene phthalocyanine zinc from step (1) in 30mL of N,N-dimethylformamide, sonicate to dissolve, then add 25mL of GO aqueous solution (graphene oxide aqueous solution) with a concentration of 4mg / mL, stir at room temperature for 24h to obtain reaction solution; filter and collect the solid reactants in the reaction solution, wash with a large amount of deionized water, freeze dry to obtain naphthalene phthalocyanine zinc-graphene oxide composite material precursor;

[0069] (3) The precursor of the naphthalene phthalocyanine zinc-graphene oxide composite material in step (2) was loaded into a ceramic boat and placed in a tube muffle furnace. It was calcined at high temperature in an Ar atmosphere for 800°C for 8 hours. After calcination, the temperature was lowered to 530°C and air was introduced to obtain the naphthalene phthalocyanine zinc-graphene oxide composite material.

[0070] The naphthyl phthalocyanine zinc-graphene oxide composite material prepared in Example 6 was subjected to XRD, Raman, SEM, TEM, and XPS tests, respectively. The test spectra are shown below. Figures 8-12 As shown.

[0071] Figure 8 The X-ray diffraction pattern shows that the composite material contains a ZnO crystal structure. The peaks at 2θ = 31.7°, 34.4° and 36.2° correspond to the (100), (002) and (101) crystal planes of hexagonal wurtzite, respectively (JCPSD PDF#:99-0111); the peak at 2θ = 25.6° indicates the formation of graphene.

[0072] Figure 9 The Raman spectrum shows the D band (~1330 cm⁻¹) associated with graphite materials. -1 ) and G-band (~1580cm) -1 ), original GO and composite material I D / I G The values ​​are 0.68 and 1.02 respectively, indicating that the degree of defects in graphene increases and the number of active sites increases, which helps to improve the performance of active materials for lithium-ion batteries.

[0073] Figure 10 The image shows a SEM image. As can be seen, after ZnNc is combined with GO, the overall structure exhibits a sheet-like and porous structure. This is because GO can hinder the one-dimensional re-aggregation of naphthalene phthalocyanine molecules during their self-assembly process in solution. The two molecules bind through π-π interactions, forming an intercalated structure. Therefore, during high-temperature pyrolysis, naphthalene phthalocyanine molecules use graphene as a template to grow along its framework and form a graphene-like sheet-like structure. Furthermore, a large number of irregular particles can be observed on the graphene surface, which is due to the release of Zn during the pyrolysis of zinc naphthalene phthalocyanine. 2+ Zn 2+ After being reduced to Zn monomers, it is oxidized again to eventually form ZnO, which provides a buffer matrix to mitigate the volume changes caused by electrochemical cycling.

[0074] Figure 11 The TEM image revealed that the graphene exhibited a wrinkled, paper-like structure, with ZnO particles distributed on the graphene.

[0075] Figure 12 The XPS spectrum shows that the composite material contains the elements C, N, O, and Zn.

[0076] The naphthalene phthalocyanine zinc-graphene oxide composite material prepared in Example 6 was used as the negative electrode material for a lithium-ion battery for electrochemical performance testing. The test results are as follows: Figures 13-14 As shown, where Figure 13 The graph shows the cycling performance of the zinc phthalocyanine-graphene oxide composite material. Figure 14 This is a rate performance diagram of the zinc phthalocyanine-graphene oxide composite material.

[0077] Depend on Figure 13 It can be seen that the initial discharge capacity at a current density of 100 mA / g is 1942.9 mAh / g, and after 60 charge-discharge cycles, its discharge specific capacity is 867.3 mAh / g. This indicates that it can significantly improve the cycle performance of lithium-ion batteries when used as a negative electrode material.

[0078] Depend on Figure 14It can be seen that at current densities of 0.1 A / g, 0.2 A / g, 0.5 A / g, and 1 A / g, the discharge capacities of the electrode are 826.8 mAh / g, 616.9 mAh / g, 459.2 mAh / g, and 368.4 mAh / g, respectively. When the current density returns to 0.1 A / g, the discharge capacity of the electrode recovers to 882.5 mAh / g. This indicates that when used as a negative electrode material for lithium-ion batteries, it can significantly improve the rate performance of lithium-ion batteries, thereby obtaining an electrode material with high capacity and good cycle performance.

[0079] Comparative Examples 7-10:

[0080] The only difference between Comparative Examples 7-10 and Example 6 is the mass ratio of tetra-tert-butylnaphthalene phthalocyanine zinc to graphene oxide. The naphthalene phthalocyanine zinc-graphene oxide composite materials prepared in Comparative Examples 7-10 were used as negative electrode materials for lithium-ion batteries for electrochemical performance testing. The specific settings and electrochemical test results of each comparative example are shown in Table 2 below.

[0081] Table 2. Setup of Comparative Examples 7–10 and Electrochemical Test Results of Their Products

[0082]

[0083] As shown in Table 2, Comparative Examples 7–10 varied the mass ratio of zinc tetra-tert-butylnaphthalene phthalocyanine to graphene oxide, and the tested lithium-ion batteries exhibited poor cycle performance and rate performance. This indicates that the performance is optimal when the mass ratio of zinc tetra-tert-butylnaphthalene phthalocyanine to graphene oxide is 5:1.

Claims

1. A metal naphthalene phthalocyanine-graphene oxide composite material, characterized in that, This is a nitrogen-doped graphene porous composite material modified with metal oxide particles, formed by bonding tetra-tert-butyl metal naphtholcyanine to graphene oxide. The XRD pattern of this metal naphtholcyanine-graphene oxide composite material shows characteristic peaks of reduced graphene oxide and diffraction peaks of the metal oxide located at 2θ = 25.6°–25.8°. The Raman spectrum shows I... D / I G The value ranges from 1.02 to 1.06, indicating a higher degree of defect than that of pristine graphene oxide; characteristic peaks of C, N, O, and metal elements appear in the XPS spectrum.

2. The composite material as described in claim 1, characterized in that, The tetra-tert-butylnaphthalene phthalocyanine is tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper, the structural formula of tetra-tert-butylnaphthalene phthalocyanine zinc is shown in formula (I), and the structural formula of tetra-tert-butylnaphthalene phthalocyanine copper is shown in formula (II).

3. The composite material as described in claim 2, characterized in that, The mass ratio of the tetra-tert-butylnaphthalene phthalocyanine zinc to graphene oxide is 5:1; the mass ratio of the tetra-tert-butylnaphthalene phthalocyanine copper to graphene oxide is 1:

1.

4. The preparation method of the metal naphthalene phthalocyanine-graphene oxide composite material according to claim 1, characterized in that, The steps include the following: (1) Preparation of tetra-tert-butylnaphthalene phthalocyanine: Using n-heptanol as the reaction solvent, 6-tert-butyl-2,3-dicyanonaphthalene was added to the reaction flask, followed by 1,8-diazabicycloundec-7-ene, zinc acetate or cuprous chloride. The mixture was stirred and heated to reflux for 10-14 h to obtain the reaction solution. The reaction solution was cooled to 140-150 °C and distilled under reduced pressure until more than 2 / 3 of the total reaction solution volume was distilled off. Methanol was added and refluxed for 1-1.5 h. After reflux, the liquid was cooled to 25-30 °C and filtered. The solution was then washed with methanol and water in sequence and freeze-dried to obtain tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper. (2) Dissolve the tetra-tert-butylnaphthalene phthalocyanine zinc or tetra-tert-butylnaphthalene phthalocyanine copper from step (1) in N,N-dimethylformamide, sonicate to dissolve, then add graphene oxide aqueous solution, stir at room temperature for 20-28h to obtain reaction solution; filter and collect the solid reactants in the reaction solution, wash with water and freeze dry to obtain metal naphthalene phthalocyanine-graphene oxide composite material precursor; (3) The metal naphthalene phthalocyanine-graphene oxide composite material precursor in step (2) was calcined at high temperature in an inert gas atmosphere for 8 hours at 800°C. After calcination, the temperature was lowered to 500-550°C and air was introduced to obtain the metal naphthalene phthalocyanine-graphene oxide composite material.

5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of 6-tert-butyl-2,3-dicyanonaphthalene, 1,8-diazabicycloundec-7-ene and zinc acetate is 4:3.15:1 to 1.05; the molar ratio of 6-tert-butyl-2,3-dicyanonaphthalene, 1,8-diazabicycloundec-7-ene and cuprous chloride is 4:3.15:1 to 1.

05.

6. The preparation method according to claim 4, characterized in that, The calcination method in step (3) is to load the metal naphthalene phthalocyanine-graphene oxide composite material precursor into a ceramic boat and place it in a tube muffle furnace for calcination.

7. The preparation method according to claim 4, characterized in that, The inert gas in step (3) is Ar.

8. The application of the metal naphthalene phthalocyanine-graphene oxide composite material according to any one of claims 1 to 3, or the application of the metal naphthalene phthalocyanine-graphene oxide composite material prepared by the method according to any one of claims 4 to 7, characterized in that, It is used in lithium-ion batteries.

9. A negative electrode material for a lithium-ion battery, characterized in that, It is prepared from the metal naphthalene phthalocyanine-graphene oxide composite material according to claim 1.

10. The negative electrode material as described in claim 9, characterized in that, The negative electrode material has an initial discharge capacity of 1431.2–1942.9 mAh / g at a current density of 100 mA / g, and a discharge specific capacity of 655.0–867.3 mAh / g after 60 charge-discharge cycles.

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