Anthracene-pyrene / porous carbon composite material and preparation method and application thereof

Abstract

The application discloses anthracene-pyrene / porous carbon composite material and a preparation method and application thereof, relates to the technical field of new energy storage materials, and discloses a kind of anthracene-pyrene / porous carbon composite material and a preparation method and application thereof, utilize ZIF-8 and tannic acid as raw material, after reaction and carbonization treatment, ZIF-8 derived carbon material is obtained, then anthracene and pyrene are mixed and dispersed into toluene to obtain anthracene-pyrene mixed solution, ZIF-8 derived carbon material is added to anthracene-pyrene mixed solution and reacts, after toluene is removed by heating, with the removal of toluene, anthracene and pyrene molecules are driven to recrystallize and deposit on the skeleton structure of ZIF-8 derived carbon material to form a composite phase, finally, after purification treatment, anthracene-pyrene / porous carbon composite material is obtained.The prepared anthracene-pyrene / porous carbon composite material has good cycle stability and specific capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy storage materials, in particular to an anthracene-pyrene / porous carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] Potassium-ion batteries (PIBs) have attracted increasing attention due to their low cost. Compared with lithium, potassium is extremely abundant in the earth's crust and widely distributed, which gives PIBs a great price advantage. Moreover, compared with other alkali metals, potassium has a close redox potential to lithium, which enables PIBs to store more energy. In addition, potassium has weaker Lewis acidity, which makes K + diffuse more efficiently in the battery and has better conductivity. These advantages make PIBs an ideal alternative to lithium-ion batteries in energy storage systems.

[0003] Currently, the research on PIBs is still in its initial stage, and to achieve large-scale application of PIBs still faces the following challenges: (1) the large size (1.38 Å) of K + makes it difficult to embed / extract in the electrode material, the electrode volume changes greatly during charging and discharging, and the large K + radius leads to slow diffusion dynamics in the electrode, which will result in poor battery capacity and rate performance, and low cycle life; (2) the low potassium storage capacity of traditional electrode materials makes it difficult to meet the requirement of high energy density. Therefore, finding suitable positive electrode materials for PIBs is one of the current focuses of PIBs research.

[0004] As the core component of potassium-ion batteries, the cathode material is crucial in determining battery cost and performance. Organic compounds, with their advantages of good structural controllability, continuous renewability, low cost, and environmental friendliness, show great promise as cathode materials for potassium-ion batteries. In existing technologies, the paper "Research Progress of Potassium-ion Battery Cathode Materials" (Zhang Zhibo, *Journal of Chemical Industry and Engineering*) discloses that the small organic molecule pyrene-3,4,9,10-tetracarboxylic diimide (PTCDI), with a conjugated large π-pyrene structure, can be used as a cathode material for potassium-ion batteries. However, the active functional group of PTCDI as an active material is a carbonyl group, resulting in a large relative molecular mass, thus its theoretical specific capacity is lower compared to pyrene with its high-density energy storage functional group. The paper "Design of Large π Molecules of Different Sizes and Their Battery Application Properties" (Li Xiaohui, August 2022) discloses π-conjugated electrode materials 2,6-dimethoxy-9,10-anthraquinone (DMAQ) and anthraquinone (AQ) as cathode materials for potassium-ion batteries. However, the active functional group of anthraquinone is a carbonyl group, and each anthraquinone molecule has two carbon groups, while the active functional group of anthracene is a benzene ring π bond, and each anthracene molecule has three benzene ring π bonds. Compared to anthraquinone, anthracene has a higher density of active groups, and the relative molecular mass of anthraquinone is larger than that of anthracene. Therefore, the theoretical specific capacity provided by anthracene as a cathode material is not as high as that of anthracene.

[0005] Therefore, how to develop and design materials that can accommodate K using anthracene as a matrix material is a key question. + Insertion and extraction of cathode materials are particularly necessary to improve battery capacity, rate performance, and cycle life. Summary of the Invention

[0006] To address the aforementioned limitations of the prior art, the present invention aims to provide anthracene-pyrene / porous carbon composite material, its preparation method, and its applications. This invention utilizes ZIF-8 and tannic acid as raw materials. After reaction and carbonization, a ZIF-8-derived carbon material is obtained. Anthracene and pyrene are then mixed and dispersed in toluene to obtain an anthracene-pyrene mixture. The ZIF-8-derived carbon material is added to the anthracene-pyrene mixture for reaction. After heating to remove toluene, as toluene is removed, anthracene and pyrene molecules are driven to recrystallize and deposit on the framework structure of the ZIF-8-derived carbon material to form a composite phase. Finally, after purification, the anthracene-pyrene / porous carbon composite material is obtained. This anthracene-pyrene / porous carbon composite material exhibits good cycling stability and specific capacity.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing anthracene-pyrene / porous carbon composite material, comprising the following steps:

[0009] (1) adding the ZIF-8 dispersion liquid into the tannic acid solution, stirring to react, centrifuging after the reaction, collecting the solid, and carbonizing the solid to obtain the ZIF-8 derived carbon material;

[0010] (2) dissolving anthracene and pyrene in toluene to obtain an anthracene-pyrene mixed solution; adding the ZIF-8 derived carbon material into the anthracene-pyrene mixed solution, stirring, and washing after heating to obtain an anthracene-pyrene / porous carbon composite material.

[0011] Preferably, in step (1), the ZIF-8 dispersion liquid is prepared by mixing ZIF-8 and water, and the concentration is 2-5 mg / mL.

[0012] Further, the ZIF-8 is prepared by the following method:

[0013] Dimethyl imidazole and cetyltrimethylammonium bromide are sequentially added into deionized water to obtain a mixed solution; zinc acetate solution is added into the mixed solution to react for 10-30 s, and after standing, the precipitate is collected by centrifugation, washed and dried to obtain ZIF-8.

[0014] Further, the zinc acetate solution is prepared by mixing zinc acetate and water, and the concentration is 0.03-0.1 g / mL.

[0015] Further, in the mixed solution, the concentration of dimethyl imidazole is 0.1-0.5 g / mL, and the concentration of cetyltrimethylammonium bromide is 0.05-0.25 mg / mL.

[0016] Further, the mass ratio of zinc acetate, dimethyl imidazole and cetyltrimethylammonium bromide in the zinc acetate solution is (0.24-0.8) g:(0.8-4) g:(0.4-2) mg.

[0017] Further, the standing time is 2-4 h, the drying method is vacuum drying, and the drying temperature is 50-70°C.

[0018] Preferably, in step (1), the tannic acid solution is prepared by mixing tannic acid and deionized water, and the concentration is 3-15 mg / mL.

[0019] Preferably, in step (1), the mass ratio of tannic acid in the tannic acid solution to ZIF-8 in the ZIF-8 dispersion liquid is 1 g:(300-500) mg.

[0020] Preferably, in step (1), the stirring time is 30-50 min.

[0021] Preferably, in step (1), the heating temperature is 900-1200°C, and the carbonization time is 6-9 h.

[0022] Preferably, in step (2), the feed ratio of anthracene, pyrene and toluene is 1 mol: (0.1-3) mol: (5-15) mL.

[0023] Preferably, in step (2), the mass ratio of anthracene and ZIF-8 derived carbon material is (1-5): 1.

[0024] Preferably, in step (2), the stirring time is 1.5-2.5 h.

[0025] Preferably, in step (2), the heating temperature is 40-60℃ and the heating time is 24-72 h.

[0026] Preferably, in step (2), the specific operation of washing is: using toluene with a temperature of -10℃~0℃ to wash the heated solid.

[0027] In a second aspect of the present application, the anthracene-pyrene / porous carbon composite material prepared by the above preparation method is provided.

[0028] In a third aspect of the present application, the anthracene-pyrene / porous carbon composite material is applied as a positive electrode material of a potassium ion battery.

[0029] The present application has the following beneficial effects:

[0030] 1. The present application uses ZIF-8 and tannic acid as raw materials, and after reaction and carbonization treatment, ZIF-8 derived carbon material is obtained. Then anthracene and pyrene are mixed and dispersed in toluene to obtain an anthracene-pyrene mixed solution. ZIF-8 derived carbon material is added to the anthracene-pyrene mixed solution for reaction. After heating to remove toluene, with the removal of toluene, anthracene and pyrene molecules are driven to recrystallize and deposit on the framework structure of ZIF-8 derived carbon material to form a composite phase. Finally, after purification treatment, an anthracene-pyrene / porous carbon composite material is obtained. The anthracene-pyrene / porous carbon composite material has good cycle stability and specific capacity. Specifically, the discharge specific capacity after 20 cycles can still be maintained at 173 mAh·g -1 .

[0031] 2. The present application uses anthracene with a planar π conjugated system as a basic material, and uses the intercalation effect of pyrene to further expand the interlayer spacing of anthracene, which not only provides a wide transmission path for potassium ions, but also meets the requirement of large-size potassium ions for storage space, thereby improving the specific capacity and rate performance of the potassium ion battery. At the same time, the adsorption effect of ZIF-8 derived carbon material can effectively alleviate the loss of active material anthracene in the electrolyte, thereby improving the cycle stability of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 : Electron microscope image of ZIF-8 derived carbon material prepared in Example 1;

[0033] Figure 2 Electron micrograph of the anthracene-pyrene / porous carbon composite material prepared in Example 1;

[0034] Figure 3 Example 1: XRD patterns of the anthracene-pyrene / porous carbon composite material, anthracene, and pyrene;

[0035] Figure 4 Specific capacity analysis diagrams of ZIF-8 derived carbon materials, anthracene-pyrene / porous carbon composite materials prepared in Example 1, and composite materials prepared in Comparative Examples 1-2;

[0036] Figure 5 Specific capacity analysis diagrams of the anthracene-pyrene / porous carbon composite material prepared in Example 1 and the composite materials prepared in Comparative Examples 3-4;

[0037] Figure 6 Cyclic stability diagram of the anthracene-pyrene / porous carbon composite material prepared in Example 1. Detailed Implementation

[0038] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0040] In existing technologies, potassium-ion batteries are considered one of the most promising alternatives to lithium-ion batteries, but K... + The large size of the potassium-ion cathode (1.38 Å) not only leads to excessive electrode volume expansion during charging and discharging but also results in slow diffusion kinetics within the electrode, leading to poor battery specific capacity and rate performance, as well as low cycle life. Therefore, developing potassium-ion cathode batteries with high potassium storage capacity, high rate performance, and excellent cycle life is currently a research hotspot.

[0041] The inventors have found that anthracene has a relatively stable structure because it has three benzene rings fused by sharing two adjacent carbon atoms, and anthracene is a planar pi conjugated system, and the pi electrons can be delocalized in the entire conjugated system to provide a large number of electron carriers and excellent charge transfer capacity. In addition, based on the energy storage mechanism of the pi conjugated system as an energy storage active group, anthracene as an electrode material for potassium ion batteries can provide high-density active sites for potassium ion storage, and has outstanding energy storage potential. Therefore, anthracene is used as a basic material. However, it is found in the research process that the interlayer spacing of anthracene is insufficient, which cannot meet the requirement of large-size potassium ions for storage space, thereby limiting the specific capacity and rate performance of the battery. Based on this, the inventors further study how to increase the interlayer spacing of anthracene, and finally use pyrene to intercalate anthracene. The principle is analyzed as follows:

[0042] Both anthracene and pyrene are planar conjugated direction molecules, and there is a pi-pi interaction between the molecules. After mixing anthracene and pyrene, heating and volatilizing the solvent (toluene), anthracene and pyrene will recrystallize. In the recrystallization process, the molecular planarity enables them to be stably combined through pi-pi stacking interaction to form an anthracene-pyrene-anthracene structure, so that pyrene intercalates anthracene to increase the interlayer spacing of anthracene, thereby meeting the requirement of large-size potassium ions for storage space and providing a wide transmission path for potassium ions.

[0043] The experimental materials used in the embodiments of the present application are all conventional experimental materials in the art and can be purchased through commercial channels.

[0044] Example 1: Preparation of anthracene-pyrene / porous carbon composite material

[0045] (1) Zinc acetate was dispersed in deionized water and ultrasonically dispersed to obtain a zinc acetate solution with a concentration of 0.06 g / mL;

[0046] Dimethylimidazole and cetyltrimethylammonium bromide were sequentially added to deionized water and ultrasonically dispersed to obtain a mixed solution, in which the concentration of dimethylimidazole was 0.3 g / mL and the concentration of cetyltrimethylammonium bromide was 0.15 mg / mL; the zinc acetate solution was added to the mixed solution, stirred for 20 s for reaction, and after reaction, the mixture was left to stand for 3 h, centrifuged, and the precipitate was collected, washed with deionized water for 3 times, and then vacuum dried at 60°C to obtain ZIF-8; wherein the mass ratio of zinc acetate, dimethylimidazole and cetyltrimethylammonium bromide in the zinc acetate solution was 0.65 g:2.4 g:1.2 mg;

[0047] (2) ZIF-8 and deionized water were mixed uniformly to obtain a ZIF-8 dispersion solution with a concentration of 3.5 mg / mL; tannic acid and deionized water were mixed to obtain a tannic acid solution with a concentration of 10 mg / mL; the ZIF-8 dispersion solution was added to the tannic acid solution, and stirred for 40 min for reaction, wherein the mass ratio of tannic acid in the tannic acid solution to ZIF-8 in the ZIF-8 dispersion solution was 1 g:400 mg; after reaction, centrifugation was performed, and the solid was collected and placed in a tube furnace for carbonization at 1050℃ for 7.5 h to obtain a ZIF-8 derived carbon material;

[0048] (3) anthracene, pyrene and toluene were mixed according to a liquid feed ratio of 1 mol:1.05 mol:10 mL to obtain an anthracene-pyrene mixed solution; the ZIF-8 derived carbon material was added to the anthracene-pyrene mixed solution and stirred for 2 h to obtain a mixed system, wherein the mass ratio of anthracene to the ZIF-8 derived carbon material was 5:1; the mixed system was placed in a ventilated environment and heated at 50℃ for 48 h, so that anthracene and pyrene were deposited on the ZIF-8 derived carbon material by crystallization; then, the solid after drying was washed with toluene at -5℃ to obtain an anthracene-pyrene / porous carbon composite material, which was denoted as anthracene-pyrene / carbon.

[0049] Example 2: Preparation of an anthracene-pyrene / porous carbon composite material

[0050] (1) zinc acetate was dispersed in deionized water, and ultrasonic dispersion was performed uniformly to obtain a zinc acetate solution with a concentration of 0.03 g / mL; dimethylimidazole and cetyltrimethylammonium bromide were sequentially added to deionized water, and ultrasonic dispersion was performed uniformly to obtain a mixed solution, wherein the concentration of dimethylimidazole in the mixed solution was 0.1 g / mL, and the concentration of cetyltrimethylammonium bromide in the mixed solution was 0.05 mg / mL;

[0051] The zinc acetate solution was added to the mixed solution, and stirring was performed for 10 s for reaction; after reaction, standing was performed for 2 h, and centrifugation was performed to collect the precipitate; after washing with deionized water for 3 times, vacuum drying was performed at 50℃ to obtain ZIF-8; wherein the mass ratio of zinc acetate in the zinc acetate solution to dimethylimidazole to cetyltrimethylammonium bromide was 0.24 g:0.8 g:0.4 mg

[0052] (2) ZIF-8 and deionized water were mixed uniformly to obtain a ZIF-8 dispersion solution with a concentration of 2 mg / mL; tannic acid and deionized water were mixed to obtain a tannic acid solution with a concentration of 3 mg / mL; the ZIF-8 dispersion solution was added to the tannic acid solution, and stirring was performed for 30 min for reaction, wherein the mass ratio of tannic acid in the tannic acid solution to ZIF-8 in the ZIF-8 dispersion solution was 1 g:300 mg; after reaction, centrifugation was performed, and the solid was collected and placed in a tube furnace for carbonization at 900℃ for 6 h to obtain a ZIF-8 derived carbon material;

[0053] (3) mixing anthracene, pyrene and toluene according to a solid-liquid ratio of 1 mol: 1.05 mol: 10 mL to obtain an anthracene-pyrene mixed solution; adding the ZIF-8 derived carbon material into the anthracene-pyrene mixed solution and stirring for 1.5 h to obtain a mixed system, wherein the mass ratio of anthracene to the ZIF-8 derived carbon material is 1:1; placing the mixed system in a ventilated environment and heating at 40°C for 24 h to enable anthracene and pyrene to be crystallized and deposited on the ZIF-8 derived carbon material; and then washing the dried solid with toluene at -10°C to obtain an anthracene-pyrene / porous carbon composite material.

[0054] Example 3: Preparation of an anthracene-pyrene / porous carbon composite material

[0055] (1) dispersing zinc acetate in deionized water to obtain a zinc acetate solution with a concentration of 0.1 g / mL; adding dimethylimidazole and cetyltrimethylammonium bromide into deionized water in sequence and uniformly dispersing by ultrasonic to obtain a mixed solution, wherein the concentration of dimethylimidazole in the mixed solution is 0.5 g / mL and the concentration of cetyltrimethylammonium bromide is 0.25 mg / mL; adding the zinc acetate solution into the mixed solution and stirring for 30 s to react; after the reaction, standing for 4 h, centrifuging, collecting the precipitate after centrifugation, washing with deionized water for 3 times, and then placing in a vacuum dryer at 70°C to obtain ZIF-8; wherein the mass ratio of zinc acetate in the zinc acetate solution, dimethylimidazole and cetyltrimethylammonium bromide is 0.8 g: 4 g: 2 mg

[0056] (2) mixing ZIF-8 and deionized water uniformly to obtain a ZIF-8 dispersion with a concentration of 5 mg / mL; mixing tannic acid and deionized water to obtain a tannic acid solution with a concentration of 15 mg / mL; adding the ZIF-8 dispersion into the tannic acid solution and stirring for 50 min to react, wherein the mass ratio of tannic acid in the tannic acid solution to ZIF-8 in the ZIF-8 dispersion is 1 g: 500 mg; after the reaction, centrifuging, collecting the solid, and placing it into a tube furnace to carbonize at 1200°C for 9 h to obtain a ZIF-8 derived carbon material;

[0057] (3) mixing anthracene, pyrene and toluene according to a solid-liquid ratio of 1 mol: 1.05 mol: 10 mL to obtain an anthracene-pyrene mixed solution; adding the ZIF-8 derived carbon material into the anthracene-pyrene mixed solution and stirring for 1.5 h to obtain a mixed system, wherein the mass ratio of anthracene to the ZIF-8 derived carbon material is 1:1; placing the mixed system in a ventilated environment and heating at 40°C for 24 h to enable anthracene and pyrene to be crystallized and deposited on the ZIF-8 derived carbon material; and then washing the dried solid with toluene at -10°C to obtain an anthracene-pyrene / porous carbon composite material.

[0058] Comparative Example 1: Anthracene / porous carbon composite material

[0059] The difference between the present comparative example and Example 1 is that pyrene is not used in the preparation of the composite material. The specific steps are as follows:

[0060] The ZIF-8 derived carbon material is prepared according to the method of Example 1; anthracene and toluene are mixed at a solid-liquid ratio of 1 mol: 10 mL to obtain an anthracene solution; the ZIF-8 derived carbon material is added to the anthracene solution and stirred for 2 h to obtain a mixed system, wherein the mass ratio of anthracene to ZIF-8 derived carbon material is 5:1; the mixed system is placed in a ventilated environment and heated at 50°C for 48 h, and then the solid after drying is washed with toluene at -5°C to obtain an anthracene / porous carbon composite material, which is denoted as anthracene / carbon.

[0061] Comparative Example 2: Pyrene / porous carbon composite material

[0062] The difference between the present comparative example and Example 1 is that anthracene is not used in the preparation of the composite material. The specific steps are as follows:

[0063] The ZIF-8 derived carbon material is prepared according to the method of Example 1; pyrene and toluene are mixed at a solid-liquid ratio of 0.1 mol: 10 mL to obtain a pyrene solution; the ZIF-8 derived carbon material is added to the pyrene solution and stirred for 2 h to obtain a mixed system, wherein the mass ratio of pyrene to ZIF-8 derived carbon material is 202:35.6; the mixed system is placed in a ventilated environment and heated at 50°C for 48 h, and then the solid after drying is washed with toluene at -5°C to obtain a pyrene / porous carbon composite material, which is denoted as pyrene / carbon.

[0064] Comparative Example 3:

[0065] The difference between the present comparative example and Example 1 is that the molar ratio of anthracene to pyrene is 1:0.08 during the reaction. The specific steps are as follows:

[0066] The ZIF-8 derived carbon material is prepared according to the method of Example 1; anthracene, pyrene and toluene are mixed at a solid-liquid ratio of 1 mol: 0.08 mol: 10 mL to obtain an anthracene-pyrene mixed solution; the ZIF-8 derived carbon material is added to the anthracene-pyrene mixed solution and stirred for 2 h to obtain a mixed system, wherein the mass ratio of anthracene to ZIF-8 derived carbon material is 5:1; the mixed system is placed in a ventilated environment and heated at 50°C for 48 h, so that anthracene and pyrene are deposited on the ZIF-8 derived carbon material by crystallization, and then the solid after drying is washed with toluene at -5°C to obtain an anthracene-pyrene / porous carbon composite material.

[0067] Comparative Example 4:

[0068] The difference between the present comparative example and Example 1 is that the molar ratio of anthracene to pyrene is 1:3.1 during the reaction. The specific steps are as follows:

[0069] The ZIF-8 derived carbon material was prepared by the method of Example 1; anthracene, pyrene and toluene were mixed in a liquid ratio of 1 mol:3.1 mol:10 mL to obtain an anthracene-pyrene mixed solution; the ZIF-8 derived carbon material was added to the anthracene-pyrene mixed solution and stirred for 2 h to obtain a mixed system, wherein the mass ratio of anthracene to the ZIF-8 derived carbon material was 5:1; the mixed system was placed in a ventilated environment and heated at 50°C for 48 h, so that anthracene and pyrene were deposited on the ZIF-8 derived carbon material by crystallization, and then the solid after drying was washed with toluene at -5°C to obtain an anthracene-pyrene / porous carbon composite material.

[0070] Test Example 1: Structural characterization

[0071] 1. The ZIF-8 derived carbon material and the anthracene-pyrene / porous carbon composite material prepared in Example 1 were subjected to electron microscope analysis, and the results are shown in Figures 1-2 .

[0072] As shown in Figure 1 , the ZIF-8 derived carbon material after etching and annealing treatment showed a standard and relatively uniform cubic structure with a size of about 200-300 nm. Careful analysis of the cubes in Figure 1 showed that the ZIF-8 derived carbon after this treatment had a hollow structure. This structure can reduce the mass proportion of the carrier as a non-energy storage active component under the condition of providing sufficient loading area, which is conducive to improving the mass specific capacity of the anthracene-pyrene / porous carbon composite material.

[0073] Figure 2 is a scanning electron microscope image of the anthracene-pyrene / porous carbon composite material. By comparing the size of the derived carbon in Figure 1 , it can be found that anthracene-pyrene compounds are loaded on the surface of the derived carbon, and the size is generally still distributed in 200-500 nm. The large particles in the electron microscope image may be anthracene-pyrene compounds or impurities accumulated during the preparation process.

[0074] 2. The anthracene-pyrene / porous carbon composite material, anthracene and pyrene prepared in Example 1 were subjected to XRD analysis, and the results are shown in Figure 3 .

[0075] As can be seen from Figure 3 , the XRD characteristic peaks of the anthracene-pyrene / porous carbon composite material include the XRD characteristic peaks of anthracene and the characteristic peaks of pyrene. According to the Bragg equation: 2d*sinθ = nλ (n is the diffraction order, λ is the incident wavelength, d is the interplanar spacing, and θ is the diffraction angle), the interplanar spacing is inversely proportional to the diffraction angle. As shown in Figure 3As shown in the XRD characteristic peaks of the anthracene-pyrrole / porous carbon composite material and the XRD characteristic peaks of anthracene, it can be found that the characteristic peaks of anthracene in the anthracene-pyrrole / porous carbon composite material have a phenomenon of shifting to a small angle, indicating that the interlayer spacing of anthracene is increased to a certain extent by the intercalation of pyrrole.

[0076] Test Example 2: Electrochemical performance test

[0077] (1) 16 mg of the anthracene-pyrrole / porous carbon composite material prepared in Example 1, the composite materials prepared in Comparative Examples 1-4 were weighed as active materials, respectively, and an equal amount of ZIF-8 derived carbon material was weighed as a control group; 2 mg of acetylene black and 2 mg of polyvinylidene fluoride were added to the active material and ground for 30 min, and then dispersed in 800 μL of N-methyl pyrrolidone and ultrasonically dispersed for 2 h to obtain a dispersion liquid, 50 uL of the dispersion liquid was dropped on a stainless steel gasket, and vacuum drying was performed at 60°C for 12 h to obtain an electrode sheet.

[0078] (2) The battery assembly was performed using a CR2032 type button cell mold, the above electrode sheet was used as a positive electrode sheet, metallic potassium was used as a negative electrode sheet, a glass fiber membrane was used as a separator, and 1-ethyl-3-methylimidazolium bisfluorosulfonylimide salt (EMIMFSI) / potassium bisfluorosulfonylimide (KFSI) type room temperature ionic liquid was used as an electrolyte to assemble a potassium ion battery.

[0079] (3) The experiment was performed on a Shanghai Chenhua CHI660D electrochemical workstation and a LANHE CT2001A type battery charge-discharge instrument; the parameter setting of the CV test was: a voltage range of 1-3.8 V; the parameter setting of the constant current charge-discharge test was: a voltage range of 1-3.8 V and a current density of 200-500 mA g -1 Figures 4-6

[0080] Figure 4 As can be seen from the above table, under the same test conditions, the discharge specific capacity of the ZIF-8 derived carbon material is 44 mAh / g, the discharge specific capacity of the composite material prepared by loading anthracene and pyrrole on the ZIF-8 derived carbon material is 311 mAh / g and 140 mAh / g, respectively. The discharge specific capacity of the composite material prepared by loading anthracene and pyrrole on the ZIF-8 derived carbon material in the present application is 376 mAh / g. It can be seen that the anthracene-pyrrole / porous carbon composite material prepared in the present application has excellent discharge specific capacity performance.

[0081] Figure 5 ​​​​It can be seen that the molar ratio of anthracene and pyrene is crucial to the specific discharge capacity of the anthracene-pyrene / porous carbon composite material. Due to the limitation of voltage upper limit, although pyrene has one more benzene ring than anthracene, all four benzene rings cannot be combined with potassium ions to provide capacity, and the relative molecular mass of pyrene is larger than that of anthracene, so when the content of pyrene is too large, the specific capacity will decrease; on the other hand, when the content of pyrene is low, it cannot fully play its role in expanding the interlayer spacing of anthracene, resulting in low utilization rate of anthracene as the main energy storage active material, thus the specific capacity decreases. Specifically, after 2 cycles, when the molar ratio of anthracene and pyrene is 1:0.08, the prepared anthracene-pyrene / porous carbon composite material has a specific discharge capacity of 205 mAh / g; when the molar ratio of anthracene and pyrene is 1:3.1, the prepared anthracene-pyrene / porous carbon composite material has a specific discharge capacity of 254 mAh / g. By adjusting the molar ratio of anthracene and pyrene, the prepared anthracene-pyrene / porous carbon composite material of the application has a specific discharge capacity of 376 mAh / g.

[0082] By Figure 6 It can be seen that the prepared anthracene-pyrene / porous carbon composite material has a specific discharge capacity of 173 mAh / g after 20 cycles, and the capacity retention rate is 32% of the initial capacity, which has good cycle stability.

[0083] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an anthracene-pyrene / porous carbon composite material, characterized by, The method comprises the following steps: (1) adding the ZIF-8 dispersion liquid into the tannic acid solution, stirring to react, centrifuging after the reaction, collecting the solid, and carbonizing the solid to obtain the ZIF-8 derived carbon material; (2) dissolving anthracene and pyrene in toluene to obtain an anthracene-pyrene mixed solution; adding the ZIF-8 derived carbon material into the anthracene-pyrene mixed solution, stirring, and washing after heating to obtain the anthracene-pyrene / porous carbon composite material; wherein the material-liquid ratio of anthracene, pyrene and toluene is 1 mol:(0.1-3) mol:(5-15) mL; and the mass ratio of anthracene and the ZIF-8 derived carbon material is (1-5):

1.

2. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 1, characterized in that, In step (1), the ZIF-8 dispersion liquid is prepared by mixing ZIF-8 and water, and the concentration is 2-5 mg / mL; The ZIF-8 is prepared by the following method: sequentially adding dimethyl imidazole and cetyltrimethylammonium bromide into deionized water to obtain a mixed solution; adding zinc acetate solution into the mixed solution and reacting for 10-30 s, centrifuging after standing, collecting the precipitate, and washing and drying to obtain the ZIF-8.

3. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 2, characterized in that, The concentration of the zinc acetate solution is 0.03-0.1 g / mL; in the mixed solution, the concentration of dimethyl imidazole is 0.1-0.5 g / mL, and the concentration of cetyltrimethylammonium bromide is 0.05-0.25 mg / mL.

4. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 2, characterized in that, The mass ratio of zinc acetate, dimethyl imidazole and cetyltrimethylammonium bromide in the zinc acetate solution is (0.24-0.8) g:(0.8-4) g:(0.4-2) mg; and the standing time is 2-4 h.

5. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 1, characterized in that, In step (1), the concentration of the tannic acid solution is 3-15 mg / mL; and the mass ratio of tannic acid in the tannic acid solution and ZIF-8 in the ZIF-8 dispersion liquid is 1 g:(300-500) mg.

6. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 1, characterized in that, In step (1), the stirring time is 30-50 min, the heating temperature is 900-1200℃, and the carbonization time is 6-9 h.

7. The preparation method of anthracene-pyrene / porous carbon composite material according to claim 1, characterized in that, In step (2), the stirring time is 1.5-2.5 h, the heating temperature is 40-60℃, and the heating time is 24-72 h.

8. The anthracene-pyrene / porous carbon composite material prepared by the preparation method in any one of claims 1-7.

9. The use of the anthracene-pyrene / porous carbon composite material in claim 8 as a positive electrode material for a potassium ion battery.

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