CN103456510B - A kind of electrode material of ultracapacitor - Google Patents

Abstract

The invention discloses an electrode material for a supercapacitor, wherein the electrode material is a polymerization product obtained by polymerization of aromatic nitrile compound monomers. The electrode material provided by the invention has high specific surface area, rich nitrogen content and porous network structure, and the supercapacitor assembled from the electrode material shows the advantages of high specific capacitance, fast charging and discharging, good cycle stability and the like. In addition, the electrode material provided by the invention can be applied to various types of supercapacitors such as acid systems, alkali systems and organic solution systems, and has a wide range of applications. Compared with the existing commercial activated carbon electrode materials or other electrode materials, the electrode material provided by the invention has the characteristics of simple preparation, high efficiency, environmental protection, low cost, excellent performance and the like.

Description

A kind of electrode material of supercapacitor

technical field

The invention relates to an electrode material, in particular to an electrode material for a supercapacitor.

Background technique

As an energy storage device, supercapacitor has relatively simple working principle, high charge and discharge rate (power density), good stability and service life, so it has become the object of extensive attention and research (Nat.Mater.,2008.7 (11): p.845-854; Chem.Soc.Rev., 2009.38(9):p.2520-2531.). However, compared with lithium batteries, the energy density of supercapacitors is still relatively small (Science, 2008.321(5889): p.651-652.), and its energy density can be calculated by E=0.5CU ² (C: specific capacitance, unit F/g; U: voltage, unit V), so when the voltage is the same, the energy density can be increased by increasing the specific capacitance. Therefore, it is very important to study substances with high specific capacitance characteristics as electrode materials for supercapacitors. At present, the research mainly focuses on increasing the specific surface area of the material, adjusting the pore size distribution, adding metal oxides to improve the pseudo-specific capacitance, or introducing heteroatoms (including nitrogen atoms, oxygen atoms, phosphorus atoms, boron atoms) to change the electron distribution state of the material, etc. The introduction of nitrogen-containing groups is not only conducive to changing the conductivity and wettability of the material, increasing the surface area with electronic activity, but also increasing the pseudospecific capacitance (EnergyEnviron.Sci., 2010.3(9):p.1238-1251.) . Therefore, the introduction of nitrogen-containing groups is an ideal method to improve the specific capacitance characteristics of materials.

The general commercial supercapacitor active material is activated carbon material after activation and modification. The raw materials they generally use are coconut shell, pitch, petroleum coke, etc. The specific capacitance of the supercapacitor assembled from it is generally less than 200F/g. Moreover, due to the high impurity content of this type of activated carbon, the leakage current is large and the voltage retention performance is poor (Carbon, 2007.45(7): p.1439-1445; Journal of Power Sources, 2008.175(1): p.675-679.). Therefore, the development of materials with controllable structure and stable performance is very important for the development of supercapacitors.

Contents of the invention

The purpose of the present invention is to provide a supercapacitor electrode material with good specific capacitance characteristics, controllable structure and stable performance.

In order to achieve the above object, the present invention provides an electrode material for a supercapacitor, wherein the electrode material is a polymerization product obtained by polymerization of aromatic nitrile compound monomers.

The supercapacitor electrode material provided by the invention has a large specific surface area, a network structure, rich nitrogen content and good conductivity. In addition, the electrode material provided by the present invention is formed by polymerizing small molecules (aromatic nitrile compound monomers). Therefore, the specific surface area, pore size distribution, and nitrogen content of the obtained material can be controlled by controlling the type of small molecules and reaction conditions, and then Adjust its specific capacitance characteristics. In addition, the preparation process of the electrode material provided by the invention is simple, efficient and environmentally friendly.

The electrode material of the present invention is subjected to assembly tests and applications of supercapacitors of different systems. The test results show that this type of material has excellent supercapacitor performance, and the electrode material provided by the invention can be applied to various types of supercapacitors such as acid system, alkali system and organic solution system, and has a wide range of applications.

Other features and advantages of the present invention will be described in detail in the following detailed description.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

Figure 1 is a transmission electron microscope (TEM) image of the electrode material prepared by the method of Example 1 (using terephthalonitrile (p-DCB) as a raw material, and the polymerization temperature is 550°C);

Figure 2 is the isothermal adsorption-desorption curve and pore size distribution diagram of the electrode material prepared by the method of Example 1 (using terephthalonitrile (p-DCB) as the raw material, the polymerization temperature is 550°C);

Figure 3 is the specific capacitance-current of the supercapacitor assembled with the electrode material prepared by the method of Example 1 (using terephthalonitrile (p-DCB) as the raw material and the polymerization temperature at 550°C) by constant current charge and discharge test Density graph;

Figure 4 is the measured current density of the supercapacitor assembled from the electrode material prepared by the method of Example 1 (using terephthalonitrile (p-DCB) as the raw material and the polymerization temperature at 550°C) when the current density is 10A/g. Specific capacitance-cycle number curve.

detailed description

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

The invention provides an electrode material for a supercapacitor, wherein the electrode material is a polymerization product obtained by polymerization of aromatic nitrile compound monomers.

The inventors of the present invention found that, so far, in the prior art, there is no disclosure that the polymerization product obtained by polymerization of aromatic nitrile compound monomer as a raw material is applied to the electrode material of a supercapacitor.

In the electrode material provided by the present invention, the types of aromatic nitrile compounds can be selected in a wide range, and the aromatic nitrile compounds may include cyano-substituted aromatic ring compounds and/or cyano-substituted aromatic heterocyclic compounds. Because of containing cyano groups, the aromatic nitrile compound is prone to polymerization and rearrangement reactions; and because it contains aromatic rings or aromatic heterocycles, the product structure after polymerization and rearrangement is a continuous large π system structure, which is beneficial to electronic transmission. Preferably, the cyano-substituted aromatic ring compound is cyanobenzene and/or cyanobiphenyl, and the number of cyano substituents is at least 2, preferably 2-4; the cyano-substituted The aromatic heterocyclic compound is a cyano-substituted six-membered aromatic heterocyclic compound, the heteroatom is N, more preferably cyano-substituted pyridine, and the number of cyano substituents is at least 2, preferably 2-4. Further preferably, the aromatic nitrile compound is selected from terephthalonitrile (p-DCB), isophthalonitrile (m-DCB), phthalonitrile (o-DCB), 1,3,5-tri Cyanobenzene (TCB), 2,6-dicyanopyridine (2,6-DCP), 2,4-dicyanopyridine (2,4-DCP) and 4,4'-dicyanopyridine ( DCBP), but not limited to.

In the electrode material provided by the present invention, the polymer product preferably has a porous network structure, and the porous network structure can increase the specific surface area of the polymer product, thereby improving the specific capacitance characteristics of the polymer product, so that it can be used as an electrode material for a supercapacitor with better performance. Further preferably, the polymer product has a specific surface area of 300-3000m ² /g, preferably 1000-2800m ² /g, and a pore size distribution of 0.5-10nm. In the present invention, the specific surface and pore size distribution of the polymerized product are measured by the isothermal adsorption-desorption method of nitrogen at 77K, the specific surface area is calculated by the BET method, and the pore size distribution is calculated by the DFT method.

In the electrode material provided by the present invention, the preparation method includes contacting the aromatic nitrile compound with a molten metal salt under polymerization reaction conditions.

In the electrode material provided by the present invention, the role of the molten metal salt in the preparation method is as a solvent and a catalyst in the reaction, as long as it can remain stable and not decompose in a molten state, so the metal The type of salt can be selected in a wide range. Preferably, the metal salt is a metal halide, more preferably, the metal halide is a metal chloride, and even more preferably, the metal chloride is selected from zinc chloride, chlorine One or more of copper chloride, ferrous chloride and manganese chloride. The amount of the metal salt can be selected in a wide range, preferably, the molar ratio of the metal salt to the aromatic nitrile compound monomer is 1-10:1, more preferably 2-8:1.

In the preparation method of the electrode material of the present invention, the polymerization reaction conditions generally include the temperature of contact and the time of contact, and the temperature of the contact only needs to ensure that the metal salt is in a molten state, so the contact The temperature can be from the melting point of the metal salt to lower than the boiling point of the metal salt, preferably, the temperature is 400-700° C.; the optional range of the contact time is wide, and in order to carry out the polymerization reaction more completely, the The contact time may be more than 20 hours, preferably, the contact time is 20-80 hours, more preferably, the contact time is 40-50 hours.

Since the temperature required to keep the metal salt in a molten state is generally high, the reaction in an open system may cause some unstable factors due to the difference in the environment. Preferably, the contact is carried out under an inert atmosphere, so as to better avoid unstable factors caused by high temperature, and the inert atmosphere can be separated from the aromatic nitrile compound monomer, molten metal salt and The gas for the polymerization product reaction, preferably, the inert atmosphere is at least one selected from nitrogen, the zero-group gas of the periodic table, more preferably, the contact is carried out in a closed environment, and the closed system can not only avoid high temperature The unstable factors brought about can also avoid the loss caused by volatilization of raw materials due to high temperature in the open system, and can maintain a certain pressure, which is conducive to the progress of the reaction.

In the electrode material provided by the present invention, the preparation method may also include a series of post-treatment steps on the polymer product, these steps can further remove impurities and purify the polymer product, which is beneficial for the polymer product to be used as a supercapacitor electrode material Applications. Preferably, the preparation method further includes cooling the obtained polymer product, and then washing and drying the cooled polymer product. The cooling can adopt a conventional method conceivable by those skilled in the art, and the cooling can be to room temperature (such as 20-30° C.). The purpose of the washing is to remove small molecules that are easily soluble in conventional solvents produced by the metal salt and the rearrangement reaction and/or decomposition reaction that occur during the polymerization reaction. The washing can use water, hydrochloric acid or tetrahydrofuran, etc. conventional reagents. The purpose of the drying is to remove the reagents used for washing, so conventional methods conceivable by those skilled in the art can be used, such as natural drying, drying, etc., and the drying temperature can be 20-200°C.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

The present invention will be described in detail below by way of examples.

p-DCB, m-DCB, o-DCB, DCBP, anhydrous zinc chloride (ZnCl ₂ ), anhydrous copper chloride (CuCl ₂ ), anhydrous ferrous chloride (FeCl ₂ ), anhydrous Manganese chloride (MnCl ₂ ) was purchased from Alfa Aisha; TCB was purchased from Nanjing Kangmanlin Chemical Industry Co., Ltd.; 2,4-DCP and 2,6-DCP were purchased from Bailingwei Technology Company.

In the embodiment, the structure of the prepared electrode material is observed with a transmission electron microscope (TEM);

The isothermal adsorption-desorption test of nitrogen at 77K is used, and then the specific surface area of the electrode material is calculated by the BET method, and the pore size distribution of the electrode material is calculated by the DFT method;

The specific capacitance of the supercapacitor assembled with electrode materials was determined by galvanostatic charge-discharge test method.

Example 1

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

Mix 1g (7.81mmol) of terephthalonitrile (p-DCB) and 5.32g (39.04mmol) of anhydrous zinc chloride, and transfer to a 10ml glass tube, replace the air in the glass tube with argon, After sealing it, put it in a muffle furnace, react at 550°C for 40 hours, cool it down to room temperature (25°C) naturally, open the glass tube, take out the polymerized product, and wash it with 5% by weight hydrochloric acid, purified water, tetrahydrofuran After washing, put it into an oven, and dry it at 120° C. for 10 hours to obtain an electrode material.

It can be seen from Figure 1 that the electrode material prepared by this embodiment has a loose and porous network structure.

Calculated from the data in Figure 2, the BET specific surface area of the prepared electrode material is 1724.74m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.7-10nm.

Example 2

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that 1 g (7.81 mmol) of isophthalonitrile (m-DCB) was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB). The BET specific surface area of the prepared electrode material is 1622m ² /g, and the pore size distribution of the electrode material is calculated by DFT method to be between 0.6-9nm.

Example 3

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that 1 g (7.81 mmol) of phthalonitrile (o-DCB) was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB). The BET specific surface area of the prepared electrode material is 1512m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.5-8.5nm.

Example 4

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that 1 g (6.53 mmol) of 1,3,5-tricyanobenzene (TCB) was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB) , the amount of anhydrous zinc chloride is 4.45g (32.65mmol). The BET specific surface area of the prepared electrode material is 1223m ² /g, and the pore size distribution of the electrode material is calculated by DFT method to be between 0.5-7nm.

Example 5

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that 1 g (7.75 mmol) of 2,6-dicyanopyridine (2,6-DCP) was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB). mmol), the dosage of anhydrous zinc chloride is 5.28g (38.74mmol). The BET specific surface area of the prepared electrode material is 1315m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.6-8nm.

Example 6

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The material was prepared according to the method of Example 1, except that 1 g (7.75 mmol) of 2,4-dicyanopyridine (2,4-DCP) was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB) ), the dosage of anhydrous zinc chloride is 5.28g (38.74mmol). The BET specific surface area of the prepared electrode material is 1392m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.6-8nm.

Example 7

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The material was prepared according to the method of Example 1, except that 1 g (4.9 mmol) of 4,4'-dicyanobiphenyl was used as the raw material instead of 1 g (7.81 mmol) of terephthalonitrile (p-DCB), anhydrous chlorine The amount of zinc chloride is 3.34g (24.5mmol). The BET specific surface area of the prepared electrode material is 1583m ² /g, and the pore size distribution of the electrode material is calculated by DFT method to be between 0.9-10nm.

Example 8

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

Prepare the electrode material according to the method of Example 1, the difference is that anhydrous copper chloride is used instead of anhydrous zinc chloride, the amount of anhydrous copper chloride is 2.10g (15.62mmol), the reaction temperature is 600°C, and the reaction time for 20 hours. The BET specific surface area of the prepared electrode material is 1860m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.7-10nm.

Example 9

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that manganese chloride was used instead of anhydrous zinc chloride, the dosage was 3.93g (31.24mmol), the reaction temperature was 650°C, and the reaction time was 60 hours. The BET specific surface area of the prepared electrode material is 2183m ² /g, and the pore size distribution of the electrode material is calculated by DFT method to be between 0.7-10nm.

Example 10

This example is used to illustrate the preparation of the supercapacitor electrode material provided by the present invention.

The electrode material was prepared according to the method of Example 1, except that ferrous chloride was used instead of anhydrous zinc chloride, the dosage was 6.93g (54.67mmol), the reaction temperature was 700°C, and the reaction time was 80 hours. The BET specific surface area of the prepared electrode material is 2790m ² /g, and the pore size distribution of the electrode material is calculated by the DFT method to be between 0.7-10nm.

Performance Testing:

1. Constant current charge and discharge test the specific capacitance of the supercapacitor assembled from the above electrode materials.

The electrode materials prepared in Examples 1-10 were mixed uniformly with conductive carbon black and binder (polytetrafluoroethylene aqueous solution) according to the ratio of mass ratio 8:1.5:0.5, rolled into thin sheets by a roller machine, and then Dry at 120°C for 10 hours, then cut into discs with a diameter of 1 cm and a mass of about 2.5 mg, and then press them on the stainless steel mesh current collector to obtain a supercapacitor.

The test uses a three-electrode system: the working electrode is an electrode material supported by a stainless steel mesh, the counter electrode is a platinum sheet electrode, the reference electrode is an Ag/AgCl electrode, and the electrolyte is a 1mol/L sulfuric acid solution. After assembly, carry out the constant current charge and discharge test. The voltage range of the test (relative to the Ag/AgCl electrode) is -0.2V to 0.8V. Record the specific capacitance of the capacitor when the current density is 0.2A/g and 10A/g (as shown in the table below 1).

Table 1

Example Current density (A/g) Specific capacitance (F/g) Current density (A/g) Specific capacitance (F/g) Example 1 0.2 300 10 220 Example 2 0.2 280 10 200 Example 3 0.2 295 10 215 Example 4 0.2 250 10 170 Example 5 0.2 230 10 160 Example 6 0.2 235 10 165 Example 7 0.2 260 10 185 Example 8 0.2 270 10 195 Example 9 0.2 250 10 180 Example 10 0.2 230 10 165

Taking Example 1 as an example, as can be seen from Figure 3, when the current density is 0.2A/g, the specific capacitance of the supercapacitor assembled by the electrode material is 300F/g, and when the current density is 10A/g, the supercapacitor assembled by the electrode material The specific capacitance is 220F/g, it can be seen that the electrode material has good specific capacitance characteristics.

It can be seen from Figure 4 that after 5000 constant current charge and discharge cycles at a current density of 10A/g, the specific capacitance of the supercapacitor assembled with electrode materials is stable at about 220F/g without significant attenuation, indicating that the cycle of the supercapacitor is stable. sex is good.

2. Constant current charging and discharging in alkaline system to test the specific capacitance of supercapacitors assembled with electrode materials

Test the performance of the supercapacitor made by the electrode material prepared in Example 1 according to the method of the above-mentioned constant current charge and discharge test, the difference is that the electrolyte is replaced with a 6mol/L NaOH solution, and the current collector is replaced with nickel foam. Replace the reference electrode with a Hg/HgO electrode, and the test voltage range is: -0.9V to 0V.

Test results: when the current density is 0.2A/g, the specific capacitance of the supercapacitor assembled with electrode materials is 280F/g; when the current density is 10A/g, the specific capacitance of the supercapacitor assembled with electrode materials is 200F/g.

3. Constant current charging and discharging in organic solution system to test the specific capacitance of supercapacitors assembled with electrode materials

Mix the electrode material prepared in Example 1 with conductive carbon black and binder (polytetrafluoroethylene aqueous solution) according to the mass ratio of 8:1.5:0.5, roll it into thin sheets through a roller machine, and dry at 120°C 10 hours, then cut into 1 cm diameter discs, which were pressed onto aluminum foil. The test uses a two-electrode system: the two electrodes are materials supported by two pieces of aluminum foil with the same quality, and the electrolyte is 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and acetonitrile in a volume ratio of 1:1 The resulting solution was mixed uniformly. After assembly, carry out the constant current charge and discharge test, the voltage range of the test is: 0V to 3.5V.

Test results: when the current density is 0.2A/g, the specific capacitance of the supercapacitor assembled with electrode materials is 140F/g; when the current density is 5A/g, the specific capacitance of the supercapacitor assembled with electrode materials is 110F/g.

From the test results shown in Examples 1-10 and Table 1, it can be seen that the electrode material provided by the present invention has a high specific surface area, a rich porous network structure, and the assembled supercapacitor shows high specific capacitance, fast charge and discharge and Good cycle stability and other advantages. From the test results of constant current charge and discharge in alkali system and organic solution system, it can be seen that the electrode material provided by the present invention is not only applicable to supercapacitors in acid systems, but also in various types of supercapacitors such as alkali systems and organic solution systems. Wide range.

Claims (11)

1. the electrode material of a ultracapacitor, it is characterized in that, this electrode material is the polymerizate obtained by aromatic nitrile compounds monomer polymerization, described aromatic nitrile compounds monomer is selected from para-Phthalonitrile, isophthalodinitrile, phthalonitrile, 1,3,5-tricyano benzene, 2,6-dicyanopyridines, 2,4-dicyanopyridine and 4, one or more in 4 '-DCNBP.

2. electrode material according to claim 1, wherein, described polymerizate has porous network structure.

3. electrode material according to claim 1 and 2, wherein, the specific area of described polymerizate is 300-3000m ²/ g, pore-size distribution is 0.5-10nm.

4. electrode material according to claim 1, wherein, the method for being polymerized the polymerizate obtained by aromatic nitrile compounds comprises: under the polymerization conditions, by the metal salt contacts of described aromatic nitrile compounds monomer and melting.

5. electrode material according to claim 4, wherein, described slaine is metal halide; The mol ratio of described slaine and described aromatic nitrile compounds monomer is 1-10:1.

6. electrode material according to claim 5, wherein, described slaine is metal chloride, described metal chloride be selected from zinc chloride, copper chloride, frerrous chloride and manganese chloride one or more, the mol ratio of described slaine and described aromatic nitrile compounds monomer is 2-8:1.

7. electrode material according to claim 4, wherein, the temperature that described polymeric reaction condition comprises contact be described slaine fusing point to the boiling point lower than slaine, time of contact is 20-80 hour.

8. electrode material according to claim 7, wherein, described time of contact is 40-50 hour.

9. electrode material according to claim 4, wherein, described contact is carried out under an inert atmosphere, and described inert atmosphere is selected from least one in nitrogen, periodic table of elements zero group gas.

10. according to the electrode material in claim 4 and 7-9 described in any one, wherein, described contact is carried out in closed environment.

11. electrode materials according to claim 4, wherein, described method also comprises the polymerizate cooling and obtain, then washing, the dry polymerizate through cooling.