Preparation Process of a Nickel Cobalt Oxide Carbon Aerogel Electrode Material

Abstract

The present invention relates to the technical field of supercapacitors, and discloses a preparation process of a cobalt nickel oxide-carbon aerogel electrode material. Cobalt nitrate, nickel nitrate, and modified phenolic aerogel are added to water, stirred for adsorption, then urea and ethylene glycol are added for reaction, and finally high-temperature calcination is carried out to obtain the cobalt nickel oxide-carbon aerogel electrode material. After the cobalt nickel oxide particles of the present invention are coated with carbon aerogel, during charge and discharge, the cobalt nickel oxide particles are not prone to volume expansion and deformation, and can maintain good structural stability, inhibiting phenomena such as pulverization and shedding of the active electrode material. After multiple cycles, the electrode material still has a high specific capacitance, showing excellent cycle stability. The modified phenolic aerogel of the present invention contains a thiazole structure, and when high-temperature calcined, it forms a nitrogen and sulfur co-doped carbon aerogel, which is beneficial to improving the electrochemical performance and specific capacitance of the carbon aerogel electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of supercapacitors, and specifically to a preparation process of a nickel cobaltate carbon aerogel electrode material. Background Art

[0002] In recent years, the development of new electrochemical energy storage devices has been a research hotspot. Among them, compared with traditional capacitors, supercapacitors have higher power density, energy density, charge and discharge speed, and cycle life, and are a very promising energy storage device.

[0003] Nickel cobaltate is a metal composite oxide with mixed valence states, which has multiple active centers and can generate higher pseudocapacitance, and has been widely studied and applied in supercapacitor electrode materials. However, nickel cobaltate is prone to volume expansion during long-term charge and discharge processes, resulting in poor structural stability of the electrode material, and prone to problems such as pulverization and shedding of active substances, leading to poor cycle stability of the electrode material.

[0004] Carbon aerogel has advantages such as large pore volume and high conductivity, and can be compounded with transition metal oxides to form electrode active materials, which are widely used in electrode materials such as supercapacitors. Common precursors of carbon aerogel mainly include phenolic aerogel, sodium alginate aerogel, cellulose aerogel, etc. Introducing heteroatoms such as nitrogen, phosphorus, and sulfur into the carbon aerogel matrix can improve its wettability, conductivity, and pseudocapacitance effect. Summary of the Invention

[0005] Technical Problem to be Solved: The present invention provides a nickel cobaltate carbon aerogel electrode material with high specific capacitance and cycle stability and a preparation process.

[0006] Technical Solution: A preparation process of a nickel cobaltate carbon aerogel electrode material includes the following steps:

[0007] Step A: Add resorcinol, 5-(imino-6-hydroxybenzothiazole)resorcinol, and water into a reaction vessel, stir, then add aqueous formaldehyde solution and sodium carbonate, seal the reaction vessel, first react at 40-50 °C for 24-36 h, then react at 80-90 °C for 72-84 h, place the generated gel product in acetone for 48 h, change acetone every 12 h, filter and dry to obtain modified phenolic aerogel.

[0008] Step B: Add water, cobalt nitrate, and nickel nitrate into a container, stir, then add modified phenolic aerogel, stir and adsorb at 20-35 °C for 3-6 h, then add urea and ethylene glycol, pour the solution into a hydrothermal reaction kettle, react at 110-125 °C for 12-18 h, filter and wash successively with water and ethanol, place the dried product in an electric resistance furnace for calcination to obtain a nickel cobaltate carbon aerogel electrode material.

[0009] Among them, in step A, the ratio of resorcinol, 5-(imino-6-hydroxybenzothiazole)resorcinol, formaldehyde, and sodium carbonate is (0.6 - 0.8) mol : (0.2 - 0.4) mol : (4.2 - 5.4) mol : (0.003 - 0.005) mol.

[0010] Among them, in step B, the ratio of cobalt nitrate, nickel nitrate, modified phenolic aerogel, and urea is (30 - 60 mmol) : (15 - 30) mmol : (90 - 220) mmol : 1 g.

[0011] Among them, in step B, the calcination is first carried out in an air atmosphere, heated to 240 - 280 °C, and calcined for 4 - 7 h; then in a nitrogen atmosphere, heated to 950 - 1100 °C, and calcined for 4 - 6 h.

[0012] Among them, the preparation method of 5-(imino-6-hydroxybenzothiazole)resorcinol is as follows: Add ethanol, 2-amino-6-hydroxybenzothiazole with a ratio of 1 mol : (1 - 1.1) mol, and 3,5-dihydroxybenzaldehyde to the reaction vessel, heat to 70 - 80 °C, carry out a condensation reflux reaction for 5 - 8 h, heat and evaporate until a precipitate appears, cool and filter, wash the filter cake with petroleum ether, and then recrystallize in ethanol to obtain 5-(imino-6-hydroxybenzothiazole)resorcinol. The preparation reaction formula is as follows:

[0013] .

[0014] (III) Technical effects: The present invention uses 5-(imino-6-hydroxybenzothiazole)resorcinol as a functional monomer to replace part of resorcinol and carry out a polycondensation reaction with formaldehyde. 5-(imino-6-hydroxybenzothiazole)resorcinol contains both phenol and resorcinol structures, and there are more ortho-polymerization sites of phenolic hydroxyl groups. It cross-links and polycondenses with formaldehyde to form a modified phenolic aerogel with a three-dimensional porous network structure. After carbonization, the pores are more abundant and the specific surface area is large.

[0015] The modified phenolic aerogel of the present invention contains a Schiff base thiazole structure, which can have a coordination interaction with cobalt and nickel ions, thereby uniformly adsorbing cobalt and nickel ions into the phenolic aerogel matrix. After the hydrothermal reaction, the cobalt nickel oxide precursor is uniformly dispersed in the aerogel matrix. After high-temperature calcination, cobalt nickel oxide particles are uniformly dispersed in the carbon aerogel matrix, reducing the agglomeration of cobalt nickel oxide particles, being beneficial to increasing electrochemical sites, and showing a higher pseudocapacitance effect and specific capacitance.

[0016] After the nickel cobaltate particles of the present invention are coated with carbon aerogel, during charge and discharge, the nickel cobaltate particles are not prone to volume expansion and deformation, and can maintain good structural stability, inhibiting phenomena such as pulverization and shedding of the active electrode material. After multiple cycles, the electrode material still has a high specific capacitance, showing excellent cycle stability.

[0017] The carbon aerogel of the present invention has a large pore volume and specific surface area, which is beneficial to the contact between the electrode material and the electrolyte, promotes the transmission of ions and electrons, and the modified phenolic aerogel contains a thiazole structure. During high-temperature calcination, a nitrogen and sulfur co-doped carbon aerogel is formed, generating active structures such as pyridine nitrogen and thiophene, which can provide an additional pseudocapacitance effect and charge storage capacity, and is beneficial to improving the electrochemical performance and specific capacitance of the carbon aerogel electrode material. Detailed implementation mode

[0018] To make the purpose, technical solution and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be clearly and completely described below in conjunction with the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure. It should be noted that, without conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other arbitrarily.

[0019] Example 1:

[0020] (1) Add 60 mL of ethanol, 40 mmol of 2-amino-6-hydroxybenzothiazole, and 40 mmol of 3,5-dihydroxybenzaldehyde to the reaction vessel, heat up to 80 °C, and carry out a condensation reflux reaction for 5 h. Heat and evaporate until a precipitate precipitates, cool and filter, wash the filter cake with petroleum ether, and then recrystallize in ethanol to obtain 5-(imino-6-hydroxybenzothiazole) resorcinol.

[0021] (2) Add 40 mmol of resorcinol, 10 mmol of 5-(imino-6-hydroxybenzothiazole) resorcinol, 40 mL of water, an aqueous solution containing 240 mmol of formaldehyde (mass fraction 37%), and 0.22 mmol of sodium carbonate to the reaction vessel, seal the reaction vessel, first react at 50 °C for 24 h, and then react at 80 °C for 72 h. Place the generated gel product in acetone for 48 h, change the acetone every 12 h, filter and dry to obtain the modified phenolic aerogel.

[0022] (3) Add 150 mL of water, 30 mmol of cobalt nitrate, and 15 mmol of nickel nitrate to a container. After stirring, add 1 g of modified phenolic aerogel, and stir and adsorb at 20 °C for 4 h. Then add 90 mmol of urea and 40 mL of ethylene glycol. Pour the solution into a hydrothermal reactor and react at 125 °C for 18 h. After filtration, wash successively with water and ethanol. After drying, place the product in an electric resistance furnace. First, in an air atmosphere, heat up to 250 °C and calcine for 7 h. Then, in a nitrogen atmosphere, heat up to 950 °C and calcine for 6 h to obtain the nickel cobalt carbon aerogel electrode material.

[0023] Example 2:

[0024] (1) Add 80 mL of ethanol, 40 mmol of 2-amino-6-hydroxybenzothiazole, and 44 mmol of 3,5-dihydroxybenzaldehyde to a reaction vessel. Heat up to 70 °C and carry out a condensation reflux reaction for 8 h. Heat and evaporate until a precipitate forms. After cooling, filter, wash the filter cake with petroleum ether, and then recrystallize in ethanol to obtain 5-(imino-6-hydroxybenzothiazole)resorcinol.

[0025] (2) Add 35 mmol of resorcinol, 15 mmol of 5-(imino-6-hydroxybenzothiazole)resorcinol, 40 mL of water, an aqueous solution containing 210 mmol of formaldehyde (mass fraction 37%), and 0.15 mmol of sodium carbonate to the reaction vessel. Seal the reaction vessel and first react at 40 °C for 36 h, then react at 90 °C for 72 h. Place the resulting gel product in acetone for 48 h, changing the acetone every 12 h. After filtration, dry to obtain the modified phenolic aerogel.

[0026] (3) Add 200 mL of water, 40 mmol of cobalt nitrate, and 20 mmol of nickel nitrate to a container. After stirring, add 1 g of modified phenolic aerogel, and stir and adsorb at 35 °C for 3 h. Then add 130 mmol of urea and 60 mL of ethylene glycol. Pour the solution into a hydrothermal reactor and react at 110 °C for 18 h. After filtration, wash successively with water and ethanol. After drying, place the product in an electric resistance furnace. First, in an air atmosphere, heat up to 240 °C and calcine for 7 h. Then, in a nitrogen atmosphere, heat up to 1100 °C and calcine for 4 h to obtain the nickel cobalt carbon aerogel electrode material.

[0027] Example 3:

[0028] (1) Add 60 mL of ethanol, 40 mmol of 2-amino-6-hydroxybenzothiazole, and 40 mmol of 3,5-dihydroxybenzaldehyde to a reaction vessel. Heat up to 75 °C and carry out a condensation reflux reaction for 8 h. Heat and evaporate until a precipitate forms. After cooling, filter, wash the filter cake with petroleum ether, and then recrystallize in ethanol to obtain 5-(imino-6-hydroxybenzothiazole)resorcinol.

[0029] (2) Add 30 mmol of resorcinol, 20 mmol of 5-(imino-6-hydroxybenzothiazole)resorcinol, 30 mL of water, an aqueous solution containing 270 mmol of formaldehyde (mass fraction 37%), and 0.25 mmol of sodium carbonate into the reaction vessel. Seal the reaction vessel and react at 50 °C for 24 h first, then react at 80 °C for 84 h. Place the resulting gel product in acetone for 48 h, change the acetone every 12 h, filter and dry to obtain the modified phenolic aerogel.

[0030] (3) Add 200 mL of water, 50 mmol of cobalt nitrate, and 25 mmol of nickel nitrate into the container. After stirring, add 1 g of the modified phenolic aerogel, stir and adsorb at 25 °C for 5 h. Then add 170 mmol of urea and 70 mL of ethylene glycol. Pour the solution into a hydrothermal reaction kettle and react at 120 °C for 18 h. Filter and wash successively with water and ethanol. Place the dried product in an electric resistance furnace. First, in an air atmosphere, heat up to 280 °C and calcine for 4 h. Then, in a nitrogen atmosphere, heat up to 1000 °C and calcine for 4 h to obtain the cobalt nickel carbon aerogel electrode material.

[0031] Example 4:

[0032] (1) Add 200 mL of water, 60 mmol of cobalt nitrate, and 30 mmol of nickel nitrate into the container. After stirring, add 1 g of the modified phenolic aerogel (prepared in Example 1), stir and adsorb at 25 °C for 6 h. Then add 220 mmol of urea and 70 mL of ethylene glycol. Pour the solution into a hydrothermal reaction kettle and react at 120 °C for 18 h. Filter and wash successively with water and ethanol. Place the dried product in an electric resistance furnace. First, in an air atmosphere, heat up to 250 °C and calcine for 6 h. Then, in a nitrogen atmosphere, heat up to 1000 °C and calcine for 4 h to obtain the cobalt nickel carbon aerogel electrode material.

[0033] Comparative Example 1:

[0034] (1) Add 50 mmol of resorcinol, 40 mL of water, an aqueous solution containing 240 mmol of formaldehyde (mass fraction 37%), and 0.22 mmol of sodium carbonate into the reaction vessel. Seal the reaction vessel and react at 50 °C for 24 h first, then react at 80 °C for 72 h. Place the resulting gel product in acetone for 48 h, change the acetone every 12 h, filter and dry to obtain the phenolic aerogel.

[0035] (2) Add 150 mL of water, 30 mmol of cobalt nitrate, and 15 mmol of nickel nitrate to a container. After stirring, add 1 g of phenolic aerogel, and stir and adsorb at 20 °C for 4 h. Then add 90 mmol of urea and 40 mL of ethylene glycol. Pour the solution into a hydrothermal reactor and react at 125 °C for 18 h. After filtration, wash successively with water and ethanol. After drying, place the product in an electric resistance furnace. First, in an air atmosphere, heat up to 250 °C and calcine for 7 h. Then, in a nitrogen atmosphere, heat up to 950 °C and calcine for 6 h to obtain the nickel cobaltite carbon aerogel electrode material.

[0036] Comparative Example 2

[0037] (1) Add 60 mL of ethanol, 40 mmol of 2-aminobenzothiazole ( ), and 40 mmol of 3,5-dihydroxybenzaldehyde to a reaction vessel. Heat up to 80 °C and carry out a condensation reflux reaction for 5 h. Heat and evaporate until a precipitate precipitates out. After cooling, filter, wash the filter cake with petroleum ether, and then recrystallize in ethanol to obtain 5-(iminobenzothiazole)resorcinol. The structural formula is .

[0038] (2) Add 40 mmol of resorcinol, 10 mmol of 5-(iminobenzothiazole)resorcinol, 40 mL of water, an aqueous solution containing 240 mmol of formaldehyde (mass fraction 37%), and 0.22 mmol of sodium carbonate to a reaction vessel. Seal the reaction vessel. First, react at 50 °C for 24 h, and then react at 80 °C for 72 h. Place the resulting gel product in acetone for 48 h, changing the acetone every 12 h. After filtration, dry to obtain the modified phenolic aerogel.

[0039] (3) Add 150 mL of water, 30 mmol of cobalt nitrate, and 15 mmol of nickel nitrate to a container. After stirring, add 1 g of the modified phenolic aerogel, and stir and adsorb at 20 °C for 4 h. Then add 90 mmol of urea and 40 mL of ethylene glycol. Pour the solution into a hydrothermal reactor and react at 125 °C for 18 h. After filtration, wash successively with water and ethanol. After drying, place the product in an electric resistance furnace. First, in an air atmosphere, heat up to 250 °C and calcine for 7 h. Then, in a nitrogen atmosphere, heat up to 950 °C and calcine for 6 h to obtain the nickel cobaltite carbon aerogel electrode material.

[0040] Use the nitrogen adsorption-desorption method to measure the pore volume and specific surface area of the nickel cobaltite carbon aerogel electrode material through a specific surface area and porosity analyzer. Before testing, the electrode material is vacuum degassed at 150 °C for 12 h.

[0041] Table 1 Pore volume and specific surface area test

[0042] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Pore volume (cm3 / g) 0.536 0.720 0.685 0.514 0.363 0.397 Specific surface area (m2 / g) 706.9 920.2 852.0 670.8 476.5 517.6

[0043] The nickel cobaltate carbon aerogel electrode material, conductive carbon black, and polytetrafluoroethylene were added to ethanol in a mass ratio of 8:1:1, stirred and mixed evenly. Then the slurry was coated on the surface of nickel foam, dried and pressed into tablets to make a working electrode. An Ag / AgCl electrode was used as the reference electrode, a platinum electrode was used as the counter electrode, and a 1 mol / L potassium hydroxide solution was used as the electrolyte. Through a three-electrode system, cyclic voltammetry tests and charge-discharge tests were carried out on an electrochemical workstation. During the test, the current density was 1 - 10 A / g.

[0044] Table 2 Specific capacitance test at a current density of 1 A / g

[0045] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Specific capacitance (F / g) 927.6 1160.8 1372.1 1459.2 659.2 845.4 Specific capacitance after 500 cycles (F / g) 844.5 1077.3 1223.0 1260.6 527.7 745.9 Retention rate (%) 91.04 92.81 89.13 86.39 80.04 88.23

[0046] Table 3 Specific capacitance test at a current density of 10 A / g

[0047] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Specific capacitance (F / g) 623.7 763.3 901.3 942.6 414.6 547.1 Specific capacitance after 500 cycles (F / g) 568.3 703.0 798.9 814.8 325.5 478.0 Retention rate (%) 91.12 92.10 88.64 86.44 78.51 87.37

[0048] After testing, the nickel cobaltate carbon aerogel electrode materials prepared in each example have a higher pore volume and specific surface area. This is because 5-(imino-6-hydroxybenzothiazole) resorcinol ( ) was used as a functional monomer to replace part of resorcinol for the polycondensation reaction with formaldehyde. 5-(imino-6-hydroxybenzothiazole) resorcinol contains both phenol ( ) and resorcinol structures ( ). There are more ortho-polymerization sites of phenolic hydroxyl groups, which crosslink and polycondense with formaldehyde to form a modified phenolic aerogel with a three-dimensional porous network structure. After carbonization, the pores are more abundant and the specific surface area is large. And the modified phenolic aerogel contains a Schiff base thiazole structure, which can have a coordination interaction with cobalt and nickel ions, so as to uniformly adsorb cobalt and nickel ions into the phenolic aerogel matrix. After the hydrothermal reaction, the nickel cobaltate precursor is uniformly dispersed in the aerogel matrix. After high-temperature calcination, nickel cobaltate particles are uniformly dispersed in the carbon aerogel matrix, reducing the agglomeration of nickel cobaltate particles, which is beneficial to increasing the electrochemical sites, showing a higher pseudocapacitance effect and specific capacitance. At the same time, after the nickel cobaltate particles are coated with carbon aerogel, during charge and discharge, the nickel cobaltate particles are not prone to volume expansion and deformation, and can maintain good structural stability, inhibiting phenomena such as pulverization and shedding of the active electrode material. After multiple cycles, the electrode material still has a high specific capacitance, showing excellent cycle stability. The large pore volume and specific surface area of the carbon aerogel are beneficial to the contact between the electrode material and the electrolyte, promoting the transmission of ions and electrons. And the modified phenolic aerogel contains a thiazole structure. During high-temperature calcination, a nitrogen and sulfur co-doped carbon aerogel is formed, generating active structures such as pyridine nitrogen and thiophene, which can provide an additional pseudocapacitance effect and charge storage capacity, being beneficial to improving the electrochemical performance and specific capacitance of the carbon aerogel electrode material.

[0049] Compared with Example 1, in Comparative Example 1, 5-(imino-6-hydroxybenzothiazole)resorcinol was not added. There were fewer ortho-polymerization sites of the phenolic hydroxyl group of resorcinol. It was difficult to form a good three-dimensional porous network structure of phenolic aerogel after polycondensation with formaldehyde. After carbonization, the pore volume and specific surface area of the carbon aerogel electrode material were small. Moreover, the phenolic aerogel did not contain Schiff base thiazole groups and could not undergo coordination interactions with cobalt and nickel ions, making it difficult to uniformly adsorb cobalt and nickel ions into the phenolic aerogel matrix. The formed nickel cobaltate particles were not uniformly dispersed in the carbon aerogel matrix, resulting in easy aggregation of nickel cobaltate particles, reducing the pore volume and specific surface area of the carbon aerogel. And due to the aggregation of nickel cobaltate particles, the electrochemical sites of the electrode material decreased, the pseudocapacitance effect and specific capacitance were low, and the cycle stability was poor.

[0050] Compared with Example 1, in Comparative Example 2, 5-(iminobenzothiazole)resorcinol ( ) was used to carry out a polycondensation reaction with resorcinol and formaldehyde. It only contained a resorcinol structure and did not contain a phenol structure. There were fewer ortho-polymerization sites of the phenolic hydroxyl group. It was difficult to form a good three-dimensional porous network structure of phenolic aerogel after polycondensation with formaldehyde. After carbonization, the pore volume and specific surface area of the carbon aerogel electrode material were small, and the specific capacitance of the electrode material was less than that of Example 1.

Claims

1. A preparation process of a nickel cobaltate carbon aerogel electrode material, characterized in that, The preparation process includes the following steps: Step A: Add resorcinol, 5-(imino-6-hydroxybenzothiazole)resorcinol, water, stirred aqueous formaldehyde solution, and sodium carbonate into a reaction vessel. Seal the reaction vessel. After the reaction, place the gel product in acetone, filter, and dry to obtain modified phenolic aerogel; Step B: Add water, cobalt nitrate, and nickel nitrate into a container. After stirring, add the modified phenolic aerogel and stir for adsorption. Then add urea and ethylene glycol. Pour the solution into a hydrothermal reaction kettle for reaction. Filter and wash. Place the dried product in an electric resistance furnace for calcination to obtain a nickel cobalt oxide carbon aerogel electrode material; The preparation method of the 5-(imino-6-hydroxybenzothiazole)resorcinol is as follows: Add ethanol, 2-amino-6-hydroxybenzothiazole, and 3,5-dihydroxybenzaldehyde into a reaction vessel. Heat to 70-80 °C and carry out a condensation reflux reaction for 5-8 h. Heat and evaporate until a precipitate appears. Cool and filter. Wash the filter cake with petroleum ether. Then recrystallize in ethanol to obtain 5-(imino-6-hydroxybenzothiazole)resorcinol; The ratio of the 2-amino-6-hydroxybenzothiazole to the 3,5-dihydroxybenzaldehyde is 1 mol:(1-1.1) mol.

2. The preparation process of the nickel cobalt oxide-carbon aerogel electrode material according to claim 1, characterized in that, In the Step A, the ratio of the resorcinol, 5-(imino-6-hydroxybenzothiazole)resorcinol, formaldehyde, and sodium carbonate is (0.6-0.8) mol:(0.2-0.4) mol:(4.2-5.4) mol:(0.003-0.005) mol.

3. The preparation process of the nickel cobalt oxide-carbon aerogel electrode material according to claim 1, characterized in that In the Step A, the reaction is first carried out at 40-50 °C for 24-36 h, and then at 80-90 °C for 72-84 h.

4. The preparation process of the nickel cobaltate carbon aerogel electrode material according to claim 1, characterized in that, In the Step B, the adsorption is carried out at 20-35 °C for 3-6 h.

5. The preparation process of the nickel cobalt oxide-carbon aerogel electrode material according to claim 1, characterized in that, In the Step B, the ratio of the cobalt nitrate, nickel nitrate, modified phenolic aerogel, and urea is (30-60 mmol):(15-30) mmol:(90-220) mmol:1 g.

6. The preparation process of the nickel cobalt oxide-carbon aerogel electrode material according to claim 1, characterized in that, In the Step B, the reaction is carried out at 110-125 °C for 12-18 h.

7. The preparation process of the nickel cobaltate carbon aerogel electrode material according to claim 1, characterized in that, In the Step B, the calcination is first carried out in an air atmosphere, heated to 240-280 °C, and calcined for 4-7 h; then in a nitrogen atmosphere, heated to 950-1100 °C, and calcined for 4-6 h.