Molecular catalyst / activated carbon composite material, and preparation method and use thereof

Abstract

The application belongs to the technical field of electrochemical energy storage, and particularly relates to a molecular catalyst / activated carbon composite material, a preparation method and application thereof. A macrocyclic compound containing metal is highly dispersed on activated carbon to prepare a composite material. The prepared molecular catalyst / activated carbon composite material has excellent electrochemical performance as a positive electrode material of a zinc-iodine battery. In the prepared zinc-iodine battery, the iodine storage capacity and zinc storage capacity reach 510 mAh / g at a small current density of 0.5 A / g, and the specific capacity is still 313 mAh / g when the current density is 20 A / g. The specific capacity reaches 400 mAh / g in the first discharge process at a current density of 2 A / g, and the capacity retention rate is 90% after 2000 reversible cycles, indicating that the prepared zinc battery has a high specific capacity and good cycle life. Therefore, the application provides a novel zinc-iodine battery electrode material with high energy storage capacity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical energy storage, and particularly relates to a molecular catalyst / activated carbon composite material and a preparation method and application thereof. BACKGROUND

[0002] The electrochemical energy storage system directly converted into electric energy through chemical reaction is applied throughout the entire power system of the smart grid and the energy internet, and has wide application in power generation, power transmission, power consumption and the like. The aqueous zinc battery has important application prospects in the field of large-scale energy storage (such as the smart grid) due to the advantages of zinc metal, such as rich and cheap raw materials, safety and environment, and high theoretical specific capacity.

[0003] The rechargeable aqueous zinc-iodine battery is considered to be a potential energy storage system due to excellent energy density, low cost and environmental friendliness. Iodine as a reactive substance is abundant in nature, and the conversion type energy storage mechanism avoids lattice distortion and conversion, and thus has good structural stability and cycle life. However, there are still some problems to be solved in the aqueous zinc-iodine battery, such as the dissolution of the positive active material caused by the shuttle side reaction of multiple iodine ions, and the corrosion of the zinc negative electrode. In addition, there are problems of low utilization rate of active iodine and slow reaction kinetics in the reaction process. The introduction of the molecular catalyst with electrocatalytic activity realizes high-speed kinetics and efficient conversion of active iodine by adsorbing polyiodide, and effectively improves the reversibility, utilization rate and kinetics of iodine / polyiodide.

[0004] In order to solve the above problems, the application is proposed. SUMMARY

[0005] The application provides a high-efficiency aqueous zinc-iodine battery catalytic positive electrode material, so as to realize fast and reversible conversion of iodine active substance, improve the reaction kinetics of the system, inhibit the problems of positive electrode material dissolution and zinc negative electrode corrosion caused by the shuttle phenomenon of polyiodide compound, and improve the electrochemical performance of the zinc-iodine battery.

[0006] The first aspect of the application provides a molecular catalyst / activated carbon composite material, which comprises: activated carbon and a molecular catalyst loaded on the activated carbon, and the molecular catalyst is selected from one or more of iron phthalocyanine, nickel phthalocyanine, cobalt phthalocyanine and manganese phthalocyanine.

[0007] The composite material has a sheet-shaped stacking structure.

[0008] Preferably, the activated carbon surface of the composite material has molecular catalyst particles, and is in a uniform distribution state.

[0009] In the molecular catalyst / activated carbon composite material, the doping amount of the molecular catalyst is 1 / 7-1 / 2.

[0010] Doping amount: refers to the mass ratio of the molecular catalyst in the composite material.

[0011] The second aspect of the present application provides a preparation method of the molecular catalyst / activated carbon composite material of the first aspect, and the preparation method comprises the following steps:

[0012] Step (1), mixing the molecular catalyst, activated carbon and solvent to obtain a mixture;

[0013] The mixing temperature is 5-45 ℃; the molecular catalyst is selected from one or more of phthalocyanine iron, phthalocyanine nickel, phthalocyanine cobalt, phthalocyanine manganese and phthalocyanine zinc;

[0014] In the mixture, the concentration of the molecular catalyst is 1-5 g / L, and the mass ratio of the molecular catalyst to activated carbon is 1 / 6-1;

[0015] Step (2), after stirring the mixture for 15-35 h, solid-liquid separation is performed, and the obtained solid is the composite material;

[0016] or stirring the mixture for 0.5-2 h, then microwave heating at a power of 500-700 W for 0.5-10 min, and then solid-liquid separation, and the obtained solid is the composite material.

[0017] Preferably, the molecular catalyst and activated carbon can be mixed first and then mixed with the solvent. In this way, the molecular catalyst and activated carbon can be mixed more uniformly, which is more conducive to the reaction.

[0018] Preferably, the solvent is selected from water, formamide, N-methyl pyrrolidone, ethanol or N,N-dimethylformamide.

[0019] Preferably, after the solid-liquid separation, there are still steps of washing and drying.

[0020] Preferably, the molecular catalyst is selected from one, two, three, four or five of phthalocyanine iron, phthalocyanine nickel, phthalocyanine cobalt, phthalocyanine manganese and phthalocyanine zinc.

[0021] The third aspect of the present application provides the use of the molecular catalyst / activated carbon composite material of the first aspect as a positive electrode material of a zinc-iodine battery.

[0022] The fourth aspect of the present application provides a zinc-iodine battery, wherein the positive electrode of the zinc-iodine battery comprises the molecular catalyst / activated carbon composite material of any one of the first aspect.

[0023] The activated carbon material can be prepared by a commercially available method.

[0024] Preferably, the zinc-iodine battery is a water-based zinc-iodine battery.

[0025] The fifth aspect of the present application provides a preparation method of a zinc-iodine battery, wherein the positive electrode sheet of the zinc-ion battery is prepared by the following method: the molecular catalyst / activated carbon composite material of any one of the first aspect is made into a slurry and coated on a current collector, and after drying in a vacuum drying box, the positive electrode sheet of the zinc-ion battery is prepared.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] 1. The molecular catalyst / activated carbon composite material prepared by the present application has excellent electrochemical performance as a positive electrode material of a zinc-iodine battery. In the prepared zinc-iodine battery, the specific capacity of the iodine storage and zinc storage capacity is 510 mAh / g at a small current density of 0.5 A / g, and the specific capacity is still 313 mAh / g when the current density is 20 A / g (Example 14). The capacity reaches 400 mAh / g during the first discharge process at a current density of 2 A / g, and the capacity retention rate is 90% after 2000 cycles (Example 2). This indicates that the prepared zinc battery has a high specific capacity and good cycle life.

[0028] 2. The material of the present application has the following unexpected technical effects:

[0029] 1) The use of the molecular catalyst / activated carbon composite material further improves its conductivity. The iron atoms in the iron phthalocyanine material provide a large number of energy storage active sites through adsorption of iodine ions / polyiodine compounds, thereby improving the capacity of the material. This is because the iron in the structure of the iron atom is in the valence state of divalent iron ions, and the iodine ions / polyiodine compounds have strong electronegativity, which will have strong interaction with the iron atom, thereby producing adsorption catalysis effect.

[0030] 2) The specific surface area of the material is high, and the porous structure not only provides more storage sites, which is beneficial to the improvement of the capacity of the material, but also is beneficial to the adsorption and desorption kinetics of iodine ions on the surface of the electrode.

[0031] 3) In the preferred technical solution, the molecular catalyst / activated carbon composite material is prepared by the microwave method. Through the short heating characteristics of the microwave method, the arrangement and stacking mode of the iron phthalocyanine on the surface of the activated carbon is controlled, and the catalytic activity of the composite material for iodine is improved. The stirring time can be shortened from 15-35h to 0.5-2h by the microwave method.

[0032] 3, The preparation process of the application has the following characteristics: the material is prepared by solvent mixing method, commercial porous high specific surface activated carbon (AC) is used as the carrier, and commercial phthalocyanine iron (FePC) is uniformly mixed in N,N-dimethylformamide solvent. During the microwave reaction process, the porous activated carbon provides more sites for the doping of phthalocyanine iron, and the active catalytic sites of iron single atoms are well dispersed, thereby avoiding the aggregation of molecular catalysts. Moreover, the material preparation process is simple and the energy consumption is low.

[0033] 4, The water-based zinc-iodine battery assembled by the molecular catalyst / activated carbon composite material prepared by the application has the following characteristics: the molecular catalyst / activated carbon composite material is made into a positive electrode sheet, the composite material loading is 2-3 mg / cm 2 , zinc metal is used as the negative electrode sheet, the electrolyte is a mixed solution of 3 mol / L zinc sulfate and 0.5 mol / L potassium iodide, the KI solution in the electrolyte is used as the electrochemically active iodine source, the iron ions in the positive electrode sheet molecular catalyst phthalocyanine iron doped composite material have strong adsorption on iodine ions / polyiodine compounds, which improves the utilization rate of active iodine, promotes the conversion reversibility of iodine ions / polyiodine compounds, and improves the kinetic performance.

[0034] The porous structure and high specific surface area of the material are also beneficial to the storage of iodine ions / polyiodine compounds, and the shuttling phenomenon of polyiodine compounds is inhibited through the physical confinement of micropores, so that the system obtains excellent and stable electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The scanning electron microscope (SEM) images of the different metal phthalocyanine molecular catalyst / activated carbon composite materials and activated carbon of examples 3-7.

[0036] Figure 2 The Mapping image of the molecular catalyst / activated carbon composite material obtained in example 3.

[0037] Figure 3 The Mapping image of the molecular catalyst / activated carbon composite material obtained in example 4.

[0038] Figure 4 The Mapping image of the molecular catalyst / activated carbon composite material obtained in example 5.

[0039] Figure 5 The Mapping image of the molecular catalyst / activated carbon composite material obtained in example 6.

[0040] Figure 6 The Mapping image of the molecular catalyst / activated carbon composite material obtained in example 7.

[0041] Figure 7 Long cycle plots for the molecular catalyst / activated carbon composites obtained for Examples 3-7 as positive electrodes for zinc batteries.

[0042] Figure 8 Long cycle plots for the molecular catalyst / activated carbon composites obtained for Examples 3, 8-11 as positive electrodes for zinc batteries.

[0043] Figure 9 Long cycle plots for the molecular catalyst / activated carbon composites of Examples 1-3 as positive electrodes for zinc batteries.

[0044] Figure 10 Differentiated capacitance plots for the molecular catalyst / activated carbon composites of Examples 1-3 and activated carbon as positive electrodes for zinc batteries, respectively.

[0045] Figure 11 XRD plots for the molecular catalyst / activated carbon composites obtained for Examples 1-3, iron phthalocyanine and activated carbon.

[0046] Figure 12 Scanning electron microscope (SEM) plots for the molecular catalyst / activated carbon composites and activated carbon obtained for Examples 12-17.

[0047] Figure 13 Long cycle plots for the molecular catalyst / activated carbon composites obtained for Examples 12-17 as positive electrodes for zinc batteries.

[0048] Figure 14 Differentiated capacitance plots for the molecular catalyst / activated carbon composites obtained for Examples 12-17 as positive electrodes for zinc batteries, respectively.

[0049] Figure 15 Rate capability plots for the molecular catalyst / activated carbon composites obtained for Example 14 as positive electrodes for zinc batteries. DETAILED DESCRIPTION

[0050] The present application will be described with respect to the following examples, but the scope of the application is not limited to these examples. Unless otherwise indicated, the experimental methods in the examples were conducted under conventional conditions, and the general equipment, materials, reagents, etc. used in the examples were obtained from commercial sources unless otherwise indicated. The starting materials used in the following examples and comparative examples were commercially available.

[0051] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions. Unless otherwise specified, all steps of this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0053] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0054] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B".

[0055] The molecular catalysts (phthalocyanine iron, phthalocyanine nickel, phthalocyanine cobalt, phthalocyanine manganese, phthalocyanine zinc) and activated carbon (AC) materials in the embodiments can be purchased on the market.

[0056] The water-based zinc-iodine battery assembled by the molecular catalyst / activated carbon composite material prepared in the embodiments is assembled in the following manner: the prepared molecular catalyst / activated carbon composite material is made into a positive electrode sheet, the active composite material loading is 2-3 mg / cm 2 , the zinc metal is a negative electrode sheet, and the electrolyte is a mixed solution of 3 mol / L zinc sulfate and 0.5 mol / L potassium iodide.

[0057] Embodiment 1

[0058] The molecular catalyst / activated carbon composite positive electrode material prepared by the non-microwave method is prepared by the following method:

[0059] 10 mg of phthalocyanine iron (FePC) and 60 mg of activated carbon are uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature is room temperature 20°C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material. In the molecular catalyst / activated carbon composite material, the doping amount of the molecular catalyst is 1 / 7.

[0060] Embodiment 2

[0061] The molecular catalyst / activated carbon composite positive electrode material prepared by the non-microwave method is prepared by the following method:

[0062] 10 mg of phthalocyanine iron (FePC) and 20 mg of activated carbon are uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature is room temperature 20°C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material.

[0063] Embodiment 3

[0064] The molecular catalyst / activated carbon composite positive electrode material prepared by the non-microwave method is prepared by the following method:

[0065] 10 mg of phthalocyanine iron (FePC) and 10 mg of activated carbon are uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature is room temperature 20°C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material. In the molecular catalyst / activated carbon composite material, the doping amount of the molecular catalyst is 1 / 2.

[0066] Embodiment 4

[0067] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material is prepared by the following method:

[0068] 10 mg of nickel phthalocyanine (NiPC) and 10 mg of activated carbon are uniformly mixed and placed in 10 mL of N,N-dimethylformamide solvent for further mixing, wherein the mixing temperature is room temperature 20 DEG C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material.

[0069] Example 5

[0070] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material is prepared by the following method:

[0071] 10 mg of cobalt phthalocyanine (CoPC) and 10 mg of activated carbon are uniformly mixed and placed in 10 mL of N,N-dimethylformamide solvent for further mixing, wherein the mixing temperature is room temperature 20 DEG C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material.

[0072] Example 6

[0073] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material is prepared by the following method:

[0074] 10 mg of zinc phthalocyanine (ZnPC) and 10 mg of activated carbon are uniformly mixed and placed in 10 mL of N,N-dimethylformamide solvent for further mixing, wherein the mixing temperature is room temperature 20 DEG C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material.

[0075] Example 7

[0076] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material is prepared by the following method:

[0077] 10 mg of manganese phthalocyanine (MnPC) and 10 mg of activated carbon are uniformly mixed and placed in 10 mL of N,N-dimethylformamide solvent for further mixing, wherein the mixing temperature is room temperature 20 DEG C, the stirring time is 20 h, after stirring, the mixture is taken out, centrifuged, washed and dried to obtain the composite material.

[0078] Example 8

[0079] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material is prepared by the following method:

[0080] 10 mg of phthalocyanine iron (FePC) and 10 mg of activated carbon were mixed uniformly and placed in 10 mL of deionized water for further mixing, wherein the mixing temperature was 45 °C, the stirring time was 15 h, after stirring, the mixture was taken out, washed, dried and centrifuged to obtain a composite material.

[0081] Example 9

[0082] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material was prepared by the following method:

[0083] 10 mg of phthalocyanine iron (FePC) and 10 mg of activated carbon were mixed uniformly and placed in 10 mL of formamide solvent for further mixing, wherein the mixing temperature was 5 °C, the stirring time was 35 h, after stirring, the mixture was taken out, washed, dried and centrifuged to obtain a composite material.

[0084] Example 10

[0085] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material was prepared by the following method:

[0086] 10 mg of phthalocyanine iron (FePC) and 10 mg of activated carbon were mixed uniformly and placed in 10 mL of N-methyl pyrrolidone solvent for further mixing, wherein the mixing temperature was room temperature 20 °C, the stirring time was 20 h, after stirring, the mixture was taken out, washed, dried and centrifuged to obtain a composite material.

[0087] Example 11

[0088] The non-microwave method prepared molecular catalyst / activated carbon composite positive electrode material was prepared by the following method:

[0089] 10 mg of phthalocyanine iron (FePC) and 10 mg of activated carbon were mixed uniformly and placed in 10 mL of ethanol for further mixing, wherein the mixing temperature was room temperature 20 °C, the stirring time was 20 h, after stirring, the mixture was taken out, washed, dried and centrifuged to obtain a composite material.

[0090] Example 12

[0091] The preparation method of the microwave method prepared molecular catalyst / activated carbon composite positive electrode material is as follows:

[0092] 10 mg of phthalocyanine iron and 20 mg of activated carbon were mixed uniformly and placed in 10 mL of N,N-dimethylformamide solvent for further mixing, wherein the mixing temperature was room temperature 20 °C, the stirring time was 0.5 h, after stirring, the mixture was taken out, washed, dried and centrifuged to obtain a composite material.

[0093] Example 13

[0094] The preparation method of the molecular catalyst / activated carbon composite positive electrode material prepared by the microwave method is as follows:

[0095] 10 mg of phthalocyanine iron, 10 mg of phthalocyanine manganese, and 40 mg of activated carbon were uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature was room temperature 20 ℃, the stirring time was 1 h, after stirring, the mixture was taken out after microwave heating for 3 min at a power of 600 W, and the composite material was obtained after centrifugal washing and drying.

[0096] Example 14

[0097] The preparation method of the molecular catalyst / activated carbon composite positive electrode material prepared by the microwave method is as follows:

[0098] 10 mg of phthalocyanine iron, 10 mg of phthalocyanine manganese, and 40 mg of activated carbon were uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature was room temperature 20 ℃, the stirring time was 1 h, after stirring, the mixture was taken out after microwave heating for 3 min at a power of 600 W, and the composite material was obtained after centrifugal washing and drying.

[0099] Example 15

[0100] The preparation method of the molecular catalyst / activated carbon composite positive electrode material prepared by the microwave method is as follows:

[0101] 10 mg of phthalocyanine iron, 10 mg of phthalocyanine manganese, and 40 mg of activated carbon were uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature was room temperature 20 ℃, the stirring time was 1 h, after stirring, the mixture was taken out after microwave heating for 3 min at a power of 600 W, and the composite material was obtained after centrifugal washing and drying.

[0102] Example 16

[0103] The preparation method of the molecular catalyst / activated carbon composite positive electrode material prepared by the microwave method is as follows:

[0104] 10 mg of phthalocyanine iron, 10 mg of phthalocyanine manganese, and 40 mg of activated carbon were uniformly mixed and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature was room temperature 20 ℃, the stirring time was 1 h, after stirring, the mixture was taken out after microwave heating for 3 min at a power of 600 W, and the composite material was obtained after centrifugal washing and drying.

[0105] Example 17

[0106] The preparation method of the molecular catalyst / activated carbon composite positive electrode material prepared by the microwave method is as follows:

[0107] 20 mg of iron phthalocyanine, 5 mg of nickel phthalocyanine, 5 mg of manganese phthalocyanine, 5 mg of zinc phthalocyanine, 5 mg of cobalt phthalocyanine and 40 mg of activated carbon are mixed uniformly, and further mixed in 10 mL of N,N-dimethylformamide solvent, wherein the mixing temperature is 28°C, the stirring time is 2 h, after stirring, the mixture is taken out after microwave heating at 700 W power for 3 min, and the composite material is obtained after centrifugal washing and drying.

[0108] Figure 1 The scanning electron microscope (SEM) images of the different metal phthalocyanine molecular catalyst / activated carbon composite materials and activated carbon of examples 3-7 are shown in the following table. By comparing the SEM images of the activated carbon (AC) and the composite material, it can be seen that the different metal phthalocyanine molecular catalysts are successfully loaded on the AC, and the different metal phthalocyanine molecular catalysts present a nanoparticle morphology and are uniformly distributed on the surface of the AC.

[0109] Figures 2-6 The Mapping images of the molecular catalyst / activated carbon composite materials obtained in examples 3-7 are shown in the following table. It can be seen from the images that the FePc, NiPc, CoPc, ZnPc and MnPc molecular catalysts are successfully loaded on the AC, and the doping is relatively uniform, which provides good catalytic sites for the catalytic conversion of iodine ions / polyiodine compounds.

[0110] Figure 7 The long cycle graphs of the different metal phthalocyanine molecular catalyst / activated carbon composite materials of examples 3-7 as zinc battery positive electrodes are shown in the following table. The small current density used in the constant current charge and discharge is 2 A / g, wherein the abscissa is the cycle number; the ordinate is the specific capacity, unit: mAh / g. By comparison, it is obtained that when FePC, NiPC, CoPC, ZnPC and MnPC are used as raw materials, the initial specific capacity of the molecular catalyst / activated carbon composite material as the positive electrode is 400, 370, 260, 180 and 370 mAh / g, respectively, and the capacity retention rate is 90% (2000 cycles), 86% (short circuit after 300 cycles), 77% (short circuit after 800 cycles), 55.5% (short circuit after 710 cycles) and 27% (700 cycles), respectively. Among them, the specific capacity and cycle performance of the molecular catalyst / activated carbon composite material corresponding to FePC are the best.

[0111] Figure 8The long cycle graph of the phthalocyanine iron molecular catalyst / activated carbon composite material prepared in different solvents for Examples 3, 8-11 as the positive electrode of the zinc battery is shown in FIG. 6, and the current density used in the constant current charge and discharge is 2 A / g. The abscissa is the cycle number, and the ordinate is the specific capacity, with the unit of milliampere-hour / gram. By comparison, it is obtained that the initial specific capacity of the molecular catalyst / activated carbon composite material as the positive electrode when water, formamide, N-methylpyrrolidone, ethanol, and N,N-dimethylformamide are used as the solvent is 280, 305, 330, 270, and 400 mAh / g, respectively, and the capacity retention rate is 44.4% (710 cycles), 65% (short circuit after 1350 cycles), 78.79% (short circuit after 910 cycles), 40% (short circuit after 800 cycles), and 90% (2000 cycles), respectively. The specific capacity and cycle performance of the molecular catalyst / activated carbon composite material corresponding to N,N-dimethylformamide are the best.

[0112] Figure 9 The long cycle graph of the molecular catalyst / activated carbon composite material of Examples 1-3 as the positive electrode of the zinc battery is shown in FIG. 5, and the small current density used in the constant current charge and discharge is 2 A / g. The abscissa is the cycle number, and the ordinate is the specific capacity, with the unit of milliampere-hour / gram. By comparison, it is obtained that the initial specific capacity of the molecular catalyst / activated carbon composite material of Examples 1-3 as the positive electrode is 400, 310, and 260 mAh / g, respectively, and the capacity retention rate is 90% (2000 cycles), 80% (2000 cycles), and 77% (short circuit after 520 cycles), respectively, which is higher than that of the activated carbon positive electrode. The zinc battery assembled by the molecular catalyst / activated carbon composite material has a high specific capacity and good cycle life.

[0113] Figure 10 The differential capacitance curve graph of the molecular catalyst / activated carbon composite material of Examples 1-3 and activated carbon as the positive electrode of the zinc battery is shown in FIG. 4, and the current density used in the constant current charge and discharge is 2 A / g. The abscissa is the voltage, with the unit of volt, and the ordinate is the differential capacitance, with the unit of milliampere-hour / volt. It is obtained from the differential capacitance curve that the reaction active substance in the battery is iodine, and as the doping ratio of FePC increases, a reduction peak with a discharge voltage of 1.3 V appears, which indicates that, compared with the I - / I3 - reaction in the activated carbon positive electrode, there is also an I - / I2 reaction in the composite material, which proves the catalytic conversion of I by the composite catalyst material.

[0114] Figure 11XRD patterns of the molecular catalyst / activated carbon composites obtained in Examples 1-3, iron phthalocyanine and activated carbon. It is found from the XRD characterization analysis that when the FePc doping amount is small, i.e. FePc:AC = 1:6 and 1:2, the material has no fixed crystal form. When FePc:AC = 1:1, a small amount of FePc signal appears in the XRD characterization. It is proved that with the increase of the doping amount of FePc, the crystal phase of FePc appears on the surface of AC, and it is also proved that FePc is successfully doped.

[0115] Figure 12 Scanning electron microscope images (SEM) of the molecular catalyst / activated carbon composites obtained in Examples 12-17 and activated carbon. It can be known from the comparison of the SEM images of activated carbon (AC) and the composites that the molecular catalyst is successfully loaded on the AC, and with the regulation of the mixed types of the molecular catalyst, the molecular catalyst presents a morphology of accumulation of nanoparticles on the surface of the AC.

[0116] Figure 13 Long cycle diagrams of the molecular catalyst / activated carbon composites obtained in Examples 12-17 as the positive electrode of zinc batteries, and the small current density used in the constant current charge and discharge is 2 A / g, wherein the abscissa is the cycle number; the ordinate is the specific capacity, unit: mAh / g. It is obtained by comparison that the initial specific capacity of the molecular catalyst / activated carbon composites obtained in Examples 12-14 as the positive electrode is 300, 500, 390 mAh / g respectively, and the capacity retention rate after 2000 reversible cycles is 67%, 40%, 85% respectively. The initial specific capacity of the molecular catalyst / activated carbon composite obtained in Example 15 as the positive electrode is 500 mAh / g, and the capacity retention rate after 600 reversible cycles is 45%. The initial specific capacity of the molecular catalyst / activated carbon composites obtained in Examples 16-17 as the positive electrode is 500, 510 mAh / g respectively, and the capacity retention rate after 1100 reversible cycles is 45%, 35% respectively. The assembled zinc batteries have high specific capacity and good cycle life.

[0117] Figure 14 The differential capacitance curve diagrams of the molecular catalyst / activated carbon composites obtained in Examples 12-17 as the positive electrode of zinc batteries respectively, and the current density used in the constant current charge and discharge is 2 A / g, wherein the abscissa is the voltage, unit: volt; the ordinate is the differential capacitance, unit: mAh / V. It can be obtained from the differential capacitance curve diagram that the reaction active substance in the battery is iodine, and compared with only FePC molecular catalyst, with the doping of FePC, NiPc, CoPc, ZnPc, MnPc, etc., the reduction peak at a discharge voltage of 1.3 V is more obvious, which indicates that compared with the transfer of 2 / 3 electrons of I - / I3 -In terms of the reaction, the system is mainly I - / I2 reaction, which proves that the composite catalytic material has high efficient catalytic conversion of I. And the redox peak voltage difference is small, only 30mv, indicating that the battery has high reversibility, and the I conversion has high reversibility.

[0118] Figure 10 And Figure 14 Compared with it is proved that the single electron transfer reaction proportion of the composite material designed by microwave method is obviously improved compared with the composite material stirred at room temperature and the composite material by non-microwave method, which proves that the microwave method has obvious improvement on the catalytic performance of the composite material. That is, in the reaction process, the microwave process can further improve the catalytic effect of the composite material on I - / I2 reaction, the proportion of single electron transfer reaction is obviously improved, so as to improve the capacity, and the good rate performance also proves to improve the reaction kinetics performance.

[0119] Figure 15 The rate performance diagram of the molecular catalyst / activated carbon composite material obtained in Example 14 as the positive electrode of the zinc battery is shown in the figure, and the current density used in the constant current charge and discharge is 0.3, 0.5, 1, 2, 3, 4, 5, 7, 10, 20 A / g, wherein the abscissa is the cycle number; the ordinate is the specific capacity, unit: mAh / g. Figure 15 It is proved that the zinc battery with the composite material of Example 14 as the positive electrode has good rate performance, and the specific capacity reaches 510 mAh / g under the small current density of 0.5 A / g, and when the current density is 20 A / g, the specific capacity is still 313 mAh / g. The capacity retention rate is 61.4%.

Claims

1. A molecular catalyst / activated carbon composite material, characterized by, The composite material comprises activated carbon and a molecular catalyst loaded on the activated carbon, wherein the molecular catalyst is stacked on the activated carbon in the form of nanoparticles. The molecular catalyst is selected from one or more of phthalocyanine iron, phthalocyanine nickel, phthalocyanine manganese, and phthalocyanine zinc. The composite material is used as a positive electrode material of a zinc-iodine battery.

2. The composite material of claim 1, wherein, In the composite material, the doping amount of the molecular catalyst is 1 / 7-1 / 2, wherein the doping amount refers to the mass ratio of the molecular catalyst in the composite material.

3. The composite material of claim 1, wherein, The molecular catalyst is uniformly distributed on the activated carbon.

4. A method for producing the molecular catalyst / activated carbon composite material according to claim 1, characterized by, The preparation method comprises the following steps: Step (1), mixing the molecular catalyst, activated carbon, and a solvent to obtain a mixture; wherein the mixing temperature is 5-45 ℃, and the molecular catalyst is selected from one or more of phthalocyanine iron, phthalocyanine nickel, phthalocyanine manganese, and phthalocyanine zinc; In the mixture, the total concentration of the molecular catalyst and activated carbon is 2-7 g / L, and the mass ratio of the molecular catalyst to activated carbon is 1 / 6-1. Step (2), after stirring the mixture for 15-35 h, solid-liquid separation is performed, and the obtained solid is the composite material. Alternatively, after stirring the mixture for 0.5-2 h, microwave heating is performed at a power of 500-700 W for 0.5-20 min, solid-liquid separation is performed, and the obtained solid is the composite material.

5. The preparation method according to claim 4, characterized in that, The solvent is selected from water, formamide, N-methyl pyrrolidone, ethanol, or N,N-dimethylformamide.

6. A zinc-iodine cell characterized in that, The positive electrode of the zinc-iodine battery comprises the molecular catalyst / activated carbon composite material according to any one of claims 1-3.

7. Use of the molecular catalyst / activated carbon composite material according to any one of claims 1-3 as a positive electrode material of a zinc-iodine battery.

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