Disclosure of Invention
The first purpose of the invention is to provide a composite energy storage material which has excellent conductive performance and good energy storage density and energy storage efficiency.
The second purpose of the invention is to provide a preparation method of the composite energy storage material.
A third object of the present invention is to provide an electrode material.
A fourth object of the present invention is to provide an energy storage device.
In order to achieve the above purpose of the present invention, the following technical solutions are adopted:
in a first aspect, the invention provides a composite energy storage material, which comprises a hierarchical pore nitrogen-oxygen carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen carbon material; the hierarchical pore nitrogen-oxygen carbon material comprises a nitrogen-oxygen carbon material, macropores and mesopores, wherein the macropores are distributed in the nitrogen-oxygen carbon material, and the mesopores are distributed around the macropores; the lignin material comprises lignin and/or oxidized lignin.
In a more preferable embodiment, the content of nitrogen in the hierarchical pore carbon oxynitride material is 1 to 5% and the content of oxygen is 8 to 12%.
As a further preferable technical scheme, the specific surface area of the composite energy storage material is 400-650 m 2 /g;
Preferably, the sum of the specific surface areas of the macropores and the mesopores accounts for 75-82% of the specific surface area of the composite energy storage material;
preferably, the volume of total pores in the composite energy storage material is 0.9-1.4 cm 3 /g;
Preferably, the sum of the volumes of the macropores and the mesopores accounts for 90-95% of the volume of the composite energy storage material;
preferably, macropores are uniformly distributed in the carbon oxynitride material, and mesopores are uniformly distributed around the macropores.
In a second aspect, the invention provides a preparation method of the composite energy storage material, which comprises the following steps:
and uniformly mixing the hierarchical pore carbon-nitrogen-oxygen material and the organic solvent, then uniformly mixing the mixed solution of the hierarchical pore carbon-nitrogen-oxygen material and the organic solvent with the lignin material, and carrying out solid-liquid separation to obtain the composite energy storage material.
As a further preferred embodiment, the organic solvent comprises a nitrile, preferably acetonitrile;
preferably, the mixing means is ultrasonic dispersion;
preferably, the means of solid-liquid separation comprises centrifugal separation.
As a further preferable technical scheme, the hierarchical pore nitrogen-oxygen carbon material is prepared by adopting the following method:
(a) Uniformly mixing water, ethanol, ammonia water and tetraethoxysilane, and stirring for reaction to obtain a silicon ball solution;
(b) Providing a mesoporous template; uniformly mixing the silicon sphere solution, the mesoporous template and the buffer solution to obtain a solution A; uniformly mixing the solution A with dopamine to obtain a solution B;
(c) Stirring the solution B for 12-36 h at 25-35 ℃ under a sealed condition, and drying to obtain a solid C;
(d) And roasting the solid C in an inert atmosphere, and then washing and drying to obtain the hierarchical pore nitrogen-oxygen carbon material.
As a further preferable technical scheme, in the step (a), the volume ratio of water, ethanol, ammonia water and tetraethoxysilane is (0.4-0.6), (1.5-2), (0.8-1.2) and (2.2-2.8);
preferably, in the step (a), the stirring speed is 300-500 rpm, the stirring temperature is 25-35 ℃, and the stirring time is 18-28 h;
preferably, step (a) comprises: uniformly mixing water, part of ethanol and ammonia water to obtain a first solution; uniformly mixing tetraethoxysilane and the rest ethanol to obtain a second solution; pouring the second solution into the first solution, and stirring for reaction to obtain the silicon ball solution;
preferably, the concentration of the ammonia water is 25-28%;
preferably, the mesoporous template comprises silicon spheres with the diameter of 2-50 nm;
preferably, the buffer solution comprises tris;
preferably, the pH of solution A is 8 to 9;
preferably, the content of the dopamine in the solution B is 0.01-0.02 g/mL;
preferably, in step (c), the stirring speed is 600-800rpm;
preferably, the inert atmosphere comprises a nitrogen atmosphere or an argon atmosphere;
preferably, the roasting temperature is 400-900 ℃, and the roasting time is 3-6 h;
preferably, the washing is carried out by sequentially adopting an alkali solution and water;
preferably, the alkali solution comprises a sodium hydroxide solution and/or a potassium hydroxide solution;
preferably, the concentration of the alkali solution is 2 to 4moL/L.
As a further preferred technical solution, the lignin material is oxidized lignin, and the oxidized lignin is prepared by the following method: mixing and stirring the lignin solution and hydrogen peroxide for 1-6 h, and then sequentially carrying out solid-liquid separation and vacuum drying to obtain oxidized lignin;
preferably, the mass concentration of the hydrogen peroxide is 25 to 35wt%;
preferably, the concentration of the lignin solution is 3-6mg/mL.
In a third aspect, the invention provides an electrode material, which comprises the composite energy storage material or the composite energy storage material obtained by the preparation method;
preferably, the electrode material is a positive electrode material or a negative electrode material.
In a fourth aspect, the present invention provides an energy storage device comprising the electrode material described above.
Compared with the prior art, the invention has the beneficial effects that:
the composite energy storage material provided by the invention takes the hierarchical pore nitrogen-oxygen carbon material as a conductive substrate, the hierarchical pore carbon material has high specific surface area, high porosity and good conductivity, the hierarchical pore structure can provide a continuous electronic channel to ensure good contact, and the diffusion channel is shortened to promote the transmission of ions, and the doping of heteroatom nitrogen and oxygen plays an important role in improving the conductivity, wettability and the like of the hierarchical pore carbon material, so that the hierarchical pore nitrogen-oxygen carbon material has more excellent performances such as conductivity, wettability and the like. The lignin material is loaded on the hierarchical pore nitrogen-oxygen carbon material, and due to the conductive lifting effect of the high-performance hierarchical pore nitrogen-oxygen carbon material, the energy storage effect of the lignin can be effectively exerted, and the energy storage density and the energy storage efficiency of the composite energy storage material are further improved.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer.
According to an aspect of the present invention, there is provided in at least one embodiment a composite energy storage material comprising a multi-stage pore carbon-nitrogen material and a lignin material supported on the multi-stage pore carbon-nitrogen material; the hierarchical pore nitrogen-oxygen carbon material comprises a nitrogen-oxygen carbon material, macropores and mesopores, wherein the macropores are distributed in the nitrogen-oxygen carbon material, and the mesopores are distributed around the macropores; the lignin material comprises lignin and/or oxidized lignin.
The composite energy storage material takes the multi-level pore nitrogen-oxygen carbon material as a conductive substrate, the multi-level pore carbon material has high specific surface area, high porosity and good conductivity, the multi-level pore system structure can provide a continuous electronic channel to ensure good contact, the diffusion channel is shortened to promote the transmission of ions, and the doping of heteroatom nitrogen and oxygen plays an important role in improving the conductivity, wettability and other aspects of the multi-level pore carbon material, so that the multi-level pore nitrogen-oxygen carbon material has more excellent performances such as conductivity, wettability and the like. The lignin material is loaded on the hierarchical pore nitrogen-oxygen carbon material, and due to the conductive lifting effect of the high-performance hierarchical pore nitrogen-oxygen carbon material, the energy storage effect of the lignin can be effectively exerted, and the energy storage density and the energy storage efficiency of the composite energy storage material are further improved.
It should be noted that:
the "loading" can also be called as attaching, and means that the lignin material is attached to the surface of the hierarchical pore nitrogen-oxygen carbon material.
The "nitrogen-oxygen carbon material" refers to a carbon material in which nitrogen, oxygen, and carbon are present in the form of simple substances, and nitrogen may be present, for example, as oxidized nitrogen or pyridine nitrogen.
The term "macropore" refers to pores having a pore diameter of greater than 50nm, and the term "mesopore" refers to pores having a pore diameter of 2 to 50 nm.
The 'hierarchical pore nitrogen-oxygen carbon material' can also contain a very small amount of micropores besides nitrogen-oxygen carbon materials, macropores and mesopores, and the pore diameter of each micropore is less than 2nm.
In a preferred embodiment, the content of nitrogen in the hierarchical pore carbon oxynitride material is 1 to 5% and the content of oxygen is 8 to 12%. The "nitrogen ratio" refers to the percentage of nitrogen to the amount of the substance of the nitrogen-oxygen carbon material, and the "oxygen ratio" refers to the percentage of oxygen to the amount of the substance of the nitrogen-oxygen carbon material. The nitrogen proportion is typically, but not limited to, 1%, 2%, 3%, 4% or 5%, and the oxygen proportion is typically, but not limited to, 8%, 9%, 10%, 11% or 12%. The proportion of nitrogen and oxygen is not too large or too small, and if the proportion of nitrogen and oxygen is too large, the content of nitrogen and oxygen is too large, so that the content of carbon in the material is too small, and the conductivity of the material is poor; if the content is too small, the content of nitrogen and oxygen is too small, and the effect of improving the conductivity is not obvious. When the ratio of the two is within the above range, the performance of the hierarchical pore nitrocarb material is optimal.
In a preferred embodiment, the specific surface area of the composite energy storage material is 400-650 m 2 (iv) g. The specific surface area is typically, but not limited to, 400, 450, 500, 550, 600 or 650m 2 (ii) in terms of/g. The specific surface area is not too large or too small, and too large the porosity of the material is too high, which is not beneficial to the transmission of the electrolyte; if the porosity is too small, the conductivity is too low. When the specific surface area is within the above rangeWhen used, promote the rapid charge transfer and the efficient transport of electrolytes.
Preferably, the sum of the specific surface areas of the macropores and the mesopores accounts for 75-82% of the specific surface area of the composite energy storage material. Such percentages are typically, but not limited to, 75%, 76%, 77%, 78%, 79%, 80%, 81% or 82%. The ratio should not be too large or too small, where too large is not conducive to charge transfer, and too small is not conducive to electrolyte transport.
Preferably, the volume of total pores in the composite energy storage material is 0.9-1.4 cm 3 (ii) in terms of/g. The total pore includes macropores, mesopores, micropores and the like. The volume is typically, but not limited to, 0.9, 1, 1.1, 1.2, 1.3 or 1.4cm 3 /g。
Preferably, the sum of the volumes of the macropores and the mesopores accounts for 90-95% of the volume of the composite energy storage material. The above proportions are typically, but not limited to, 90%, 91%, 92%, 93%, 94% or 95%.
Preferably, macropores are uniformly distributed in the carbon oxynitride material, and mesopores are uniformly distributed around the macropores. The term "uniformly distributed" as used herein means that the probability of macropores or mesopores appearing throughout the nitrocarb material is the same. When macropores and mesopores are uniformly distributed, the performance of each part of the obtained composite energy storage material is uniform, and the performance reliability and the service life of the material are favorably improved.
According to another aspect of the present invention, in at least one embodiment, there is provided a method for preparing the composite energy storage material, comprising the following steps:
and uniformly mixing the hierarchical pore carbon-nitrogen-oxygen material and the organic solvent, then uniformly mixing the mixed solution of the hierarchical pore carbon-nitrogen-oxygen material and the organic solvent with the lignin material, and carrying out solid-liquid separation to obtain the composite energy storage material.
The preparation method is simple and easy to implement and low in cost, the hierarchical pore nitrogen-oxygen-carbon material, the organic solvent and the lignin material are respectively and sequentially mixed uniformly, and then the composite energy storage material can be obtained after solid-liquid separation, and the material has a required structure and has good conductivity, energy storage density and energy storage efficiency.
In a preferred embodiment, the organic solvent comprises a nitrile, preferably acetonitrile. Acetonitrile is widely available, can be mixed and dissolved with water, and can be dissolved in most organic solvents such as ethanol, diethyl ether and the like.
Optionally, water may also be added during mixing.
Preferably, the mixing means is ultrasonic dispersion. The mixing mode refers to a mixing mode of the hierarchical pore nitrogen-oxygen carbon material and the organic solvent, or a mixing mode of a mixed solution of the hierarchical pore nitrogen-oxygen carbon material and the organic solvent and the lignin material. The ultrasonic dispersion efficiency is high, and the mixing effect is good.
Preferably, the means of solid-liquid separation comprises centrifugal separation.
In a preferred embodiment, the hierarchical porous carbon oxynitride material is prepared by the following method:
(a) Uniformly mixing water, ethanol, ammonia water and tetraethoxysilane, and stirring for reaction to obtain a silicon ball solution;
(b) Providing a mesoporous template; uniformly mixing the silicon sphere solution, the mesoporous template and the buffer solution to obtain a solution A; uniformly mixing the solution A with dopamine to obtain a solution B;
(c) Stirring the solution B for 12-36 h at 25-35 ℃ under a sealed condition, and drying to obtain a solid C;
(d) And roasting the solid C in an inert atmosphere, and then washing and drying to obtain the hierarchical porous nitrogen-oxygen carbon material.
The method is scientific in process, wide in raw material source and safe and controllable in preparation process, the silicon ball solution prepared in the step (a) is used as a macroporous template, then the macroporous template and the buffer solution are mixed to obtain a solution A, the solution A is mixed with dopamine (nitrogen-carbon-oxygen source), and then sealed stirring, roasting, washing and drying are carried out, wherein carbon, oxygen and nitrogen in the dopamine can be decomposed into carbon materials containing oxygen and nitrogen in the roasting process, and finally the hierarchical pore nitrogen-oxygen carbon material is obtained.
It should be noted that:
the temperature of the stirred reaction in step (c) is typically, but not limited to, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35 ℃ and the reaction time is typically, but not limited to, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34 or 36h.
The drying in step (c) may optionally be room temperature evaporation. The drying mode in the step (d) can be vacuum drying.
In a preferred embodiment, in step (a), the volume ratio of the water, the ethanol, the ammonia water and the tetraethoxysilane is (0.4-0.6): 1.5-2): 0.8-1.2): 2.2-2.8. The above volume ratio is typically but not limited to 0.4. The parts by volume of water are, for example, 0.4 part, 0.5 part or 0.6 part; the volume part of ethanol is, for example, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts or 2 parts; the part by volume of the aqueous ammonia is, for example, 0.8 part, 0.9 part, 1 part, 1.1 part or 1.2 parts; the parts by volume of ethyl orthosilicate are, for example, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts or 2.8 parts. The parts of the water, the ethanol, the ammonia water and the tetraethoxysilane can be selected from the parts and are matched with one another, so that the volume ratio of the water, the ethanol, the ammonia water and the tetraethoxysilane is (0.4-0.6), (1.5-2), (0.8-1.2) and (2.2-2.8).
Preferably, in step (a), the stirring speed is 300-500 rpm, the stirring temperature is 25-35 ℃, and the stirring time is 18-28 h. The temperature of the agitation reaction in step (a) is typically, but not limited to, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35 ℃, the reaction time is typically, but not limited to, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 or 28 hours, and the agitation speed is typically, but not limited to, 300, 350, 400, 450 or 500rpm.
Preferably, step (a) comprises: uniformly mixing water, part of ethanol and ammonia water to obtain a first solution; uniformly mixing ethyl orthosilicate and residual ethanol to obtain a second solution; and pouring the second solution into the first solution, and stirring for reaction to obtain the silicon ball solution.
Preferably, the concentration of ammonia is 25% to 28%. This concentration is typically, but not limited to, 25%, 26%, 27% or 28%.
Preferably, the mesoporous template comprises silicon spheres with a diameter of 2-50 nm. The diameter of the silicon spheres is typically, but not limited to, 2nm, 6nm, 12nm, 20nm, 25nm, 30nm, 35nm, 40nm, 45nm, 50nm, or the like. The "diameter" mentioned above means the median diameter of the silicon sphere.
Preferably, the buffer solution comprises tris.
Preferably, the pH of solution A is between 8 and 9. The pH can be, for example, 8, 8.5 or 9.
Preferably, the content of the dopamine in the solution B is 0.01-0.02 g/mL. The above amount is typically, but not limited to, 0.01, 0.012, 0.014, 0.016, 0.018, or 0.02g/mL.
Preferably, in step (c), the stirring speed is 600-800rpm. The agitation speed is typically, but not limited to, 600, 620, 640, 660, 680, 700, 720, 740, 760, 780, or 800rpm.
Preferably, the inert atmosphere includes a nitrogen atmosphere or an argon atmosphere.
Preferably, the roasting temperature is 400-900 ℃, and the roasting time is 3-6 h. The above firing temperatures are typically, but not limited to, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, or 900 ℃. The above-mentioned calcination times are typically, but not limited to, 3, 3.5, 4, 4.5, 5, 5.5 or 6 hours.
Preferably, the washing is carried out by sequentially washing with an alkaline solution and water. The above-mentioned "alkali solution" means a solution in which the solute is an alkaline substance.
Preferably, the alkali solution comprises a sodium hydroxide solution and/or a potassium hydroxide solution.
Preferably, the concentration of the alkali solution is 2 to 4moL/L. Typical but not limiting concentrations are 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8 or 4moL/L.
In a preferred embodiment, the lignin material is oxidized lignin, and the oxidized lignin is prepared by the following method: mixing and stirring the lignin solution and hydrogen peroxide for 1-6 h, and then sequentially carrying out solid-liquid separation and vacuum drying to obtain oxidized lignin. The "lignin solution" refers to an organic solution of lignin.
Preferably, the concentration by mass of hydrogen peroxide is between 25 and 35 wt.%. The above mass concentration is typically, but not limited to, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35wt%.
Preferably, the concentration of the lignin solution is 3-6mg/mL. Such concentrations are typically, but not limited to, 3, 3.5, 4, 4.5, 5, 5.5 or 6mg/mL.
Alternatively, the stirring is carried out at room temperature.
Optionally, the solid-liquid separation means comprises filtration.
According to another aspect of the present invention, there is provided an electrode material comprising the composite energy storage material described above; preferably, the electrode material is a positive electrode material or a negative electrode material. The electrode material comprises the composite energy storage material and thus has at least the same advantages as the composite energy storage material.
It should be noted that: the composite energy storage material can be selected as a positive electrode material or a negative electrode material according to the requirements of the energy storage device, and the selection can be known by the skilled person according to experience, experiments and the like.
According to another aspect of the present invention, there is provided an energy storage device comprising the above electrode material. The energy storage device comprises the electrode material and thus has at least the same advantages as the electrode material.
It should be noted that: the "energy storage device" refers to an electrochemical device capable of storing and releasing electric energy, and includes, but is not limited to, a lithium ion battery or a capacitor, etc.
The present invention will be described in further detail with reference to examples and comparative examples.
Example 1
A composite energy storage material comprises a hierarchical pore nitrogen-oxygen carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen carbon material; the hierarchical pore carbon oxynitride material comprises a carbon oxynitride material, macropores and mesopores, wherein the macropores are uniformly distributed in the carbon oxynitride material, and the mesopores are uniformly distributed around the macropores; the lignin material is lignin.
The nitrogen proportion of the hierarchical pore nitrogen-oxygen carbon material is 0.87%, and the oxygen proportion is 6.87%;
the specific surface area of the composite energy storage material is 313.74m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 89.22 percent of the specific surface area of the composite energy storage material;
the volume of the total hole in the composite energy storage material is 1.76cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 96.71 percent of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparing 100nm silicon spheres with uniform size: mixing 12mL of deionized water, 42mL of absolute ethyl alcohol and 2.4mL of ammonia water in a round-bottom flask, and uniformly stirring by magnetic force (the stirring speed is 500 rpm) to prepare a first solution; then 12mL of ethyl orthosilicate and 30mL of absolute ethyl alcohol are mixed and stirred uniformly to prepare a second solution. And quickly pouring the second solution into the first solution under stirring, taking care of the process to avoid the second solution from contacting the wall of the flask as much as possible, continuously stirring for 2min, reducing the stirring speed to 300rpm, sealing the flask opening by using a sealing film, and stirring and reacting at 30 ℃ for 24h to obtain the 100nm silicon ball solution.
2) Taking 60mL of the 100nm silicon sphere solution (serving as a macroporous template) prepared in the step 1) into a round-bottom flask, adding 1.0mL of 40nm silicon spheres (directly purchased and serving as a mesoporous template), and uniformly stirring. Subsequently, tris buffer was added to the silica sphere mixture, the pH was adjusted to 8.5, and then 1.12g dopamine (as a carbon and nitrogen source) was added with continuous stirring, and stirred for 26h at 30 ℃ under sealed conditions. And fully volatilizing the reacted mixed solution at room temperature to obtain a solid, placing the solid in a tubular furnace, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min in the nitrogen atmosphere, keeping the temperature for 6 hours, and raising the temperature to 900 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 6 hours to obtain the nitrogen-doped carbon material containing the silicon template. Placing the mixture into 3mol/L sodium hydroxide solution at 90 ℃, repeating the process for multiple times, washing and filtering the mixture by using distilled water and ethanol for multiple times, and drying the mixture in a vacuum drying oven to obtain the NC material.
3) Taking the lignin (KL) obtained in the step 2), dissolving the lignin (KL) in acetonitrile and water (7: 3,v/v) to obtain 60mL of a 5mg/mL KL solution, and further adding 30mg of NC to the above solution to obtain a KL/NC suspension. And magnetically stirring the suspension for 30min, performing ultrasound treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge for 15min at 9000rmp, pouring out supernatant, and drying in a drying oven for 12h to obtain the KL/NC material, wherein the KL/NC material is the composite energy storage material.
All parameters in this example are outside the preferred range of the present invention.
Example 2
A composite energy storage material comprises a hierarchical pore nitrogen-oxygen-carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen-carbon material; the hierarchical pore carbon oxynitride material comprises a carbon oxynitride material, macropores and mesopores, wherein the macropores are uniformly distributed in the carbon oxynitride material, and the mesopores are uniformly distributed around the macropores; the lignin material is lignin. The nitrogen proportion of the hierarchical pore nitrogen-oxygen carbon material is 3.01%, and the oxygen proportion is 11.11%;
the specific surface area of the composite energy storage material is 324.87m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 87.68 percent of the specific surface area of the composite energy storage material;
the total pore volume in the composite energy storage material is 1.595cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 96.77% of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparing 100nm silicon spheres with uniform size: mixing 12mL of deionized water, 42mL of absolute ethyl alcohol and 2.4mL of ammonia water in a round-bottom flask, and uniformly stirring by magnetic force (the stirring speed is 500 rpm) to prepare a first solution; then 12mL of ethyl orthosilicate and 30mL of absolute ethyl alcohol are mixed and stirred uniformly to prepare a second solution. And quickly pouring the second solution into the first solution under stirring, taking care to avoid the second solution from contacting the wall of the flask as much as possible, continuously stirring for 2min, reducing the stirring speed to 300rpm, sealing the flask opening with a sealing film, and stirring at 30 ℃ for 24h to react to obtain the 100nm silicon ball solution.
2) Taking 60mL of the 100nm silicon ball solution (serving as a macroporous template) prepared in the step 1) into a round-bottom flask, adding 1.0mL of 20nm silicon balls (directly purchased and serving as a mesoporous template), and uniformly stirring. Subsequently, tris buffer was added to the silica sphere mixture, the pH was adjusted to 8.5, then 0.84g dopamine (as a carbon and nitrogen source) was added with constant stirring, and the mixture was stirred for 26h at 30 ℃ under sealed conditions. And fully volatilizing the reacted mixed solution at room temperature to obtain a solid, placing the solid in a tubular furnace, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min in the nitrogen atmosphere, keeping the temperature for 2 hours, and raising the temperature to 900 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 4 hours to obtain the nitrogen-doped carbon material containing the silicon template. Placing the mixture into 3mol/L sodium hydroxide solution at 90 ℃, repeating the process for multiple times, washing and filtering the mixture by using distilled water and ethanol for multiple times, and drying the mixture in a vacuum drying oven to obtain the NC material.
3) Dissolving lignin (KL) in acetonitrile and water (7: 3,v/v) to obtain 60mL of a 5mg/mL KL solution, and further adding 30mg NC to the above solution to obtain a KL/NC suspension. And magnetically stirring the suspension for 30min, performing ultrasound treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge for 15min at 9000rmp, pouring out supernatant, and drying in a drying oven for 12h to obtain the KL/NC material, wherein the KL/NC material is the composite energy storage material.
In this example, the other parameters except the ratio of nitrogen to oxygen are out of the preferable range of the present invention.
Example 3
A composite energy storage material comprises a hierarchical pore nitrogen-oxygen-carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen-carbon material; the hierarchical pore carbon oxynitride material comprises a carbon oxynitride material, macropores and mesopores, wherein the macropores are uniformly distributed in the carbon oxynitride material, and the mesopores are uniformly distributed around the macropores; the lignin material is lignin.
The nitrogen proportion of the hierarchical pore nitrogen-oxygen carbon material is 3.03%, and the oxygen proportion is 11.61%;
the specific surface area of the composite energy storage material is 499.24m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 64.36 percent of the specific surface area of the composite energy storage material;
the volume of total pores in the composite energy storage material is 0.822cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 87.68 percent of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparing 100nm silicon spheres with uniform size: mixing 12mL of deionized water, 42mL of absolute ethyl alcohol and 2.4mL of ammonia water in a round-bottom flask, and uniformly stirring by magnetic force (the stirring speed is 500 rpm) to prepare a first solution; then 12mL of ethyl orthosilicate and 30mL of absolute ethyl alcohol are mixed and stirred uniformly to prepare a second solution. And quickly pouring the second solution into the first solution under stirring, taking care to avoid the second solution from contacting the wall of the flask as much as possible, continuously stirring for 2min, reducing the stirring speed to 300rpm, sealing the flask opening with a sealing film, and stirring at 30 ℃ for 24h to react to obtain the 100nm silicon ball solution.
2) Taking 60mL of the 100nm silicon ball solution prepared in the step 1) as a macroporous template, adding 2.6mL of 6nm silicon balls (directly purchased as a mesoporous template), and uniformly stirring. Subsequently Tris buffer was added to the silica spheres mixture, the pH was adjusted to 8.5, then 0.84g dopamine (as a carbon and nitrogen source) was added with constant stirring and stirred for 28h at 30 ℃ under sealed conditions. And fully volatilizing the reacted mixed solution at room temperature to obtain a solid, placing the solid in a tubular furnace, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min in the nitrogen atmosphere, keeping the temperature for 2 hours, raising the temperature to 900 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 3 hours to obtain the nitrogen-doped carbon material containing the silicon template. Placing the mixture into 3mol/L sodium hydroxide solution at 90 ℃, repeating the process for multiple times, washing and filtering the mixture by using distilled water and ethanol for multiple times, and drying the mixture in a vacuum drying oven to obtain the NC material.
3) Taking the lignin (KL) obtained in the step 2), dissolving the lignin (KL) in acetonitrile and water (7: 3,v/v) to obtain 60mL of a 5mg/mL KL solution, and further adding 30mg NC to the above solution to obtain a KL/NC suspension. And magnetically stirring the suspension for 30min, performing ultrasound treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge for 15min at 9000rmp, pouring out supernatant, and drying in a drying oven for 12h to obtain the KL/NC material, wherein the KL/NC material is the composite energy storage material.
In the present example, the parameters other than the ratio of nitrogen to oxygen and the specific surface area were out of the preferable range of the present invention.
Example 4
A composite energy storage material comprises a hierarchical pore nitrogen-oxygen-carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen-carbon material; the hierarchical pore nitrogen-oxygen carbon material comprises a nitrogen-oxygen carbon material, macropores and mesopores, wherein the macropores are uniformly distributed in the nitrogen-oxygen carbon material, and the mesopores are uniformly distributed around the macropores; the lignin material is lignin.
The proportion of nitrogen in the hierarchical porous nitrogen-oxygen carbon material is 1.07%, and the proportion of oxygen is 9.33%;
the specific surface area of the composite energy storage material is 409.91m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 70.10 percent of the specific surface area of the composite energy storage material;
the volume of the total hole in the composite energy storage material is 1.203cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 88.13 percent of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparing 100nm silicon spheres with uniform size: mixing 12mL of deionized water, 42mL of absolute ethyl alcohol and 2.4mL of ammonia water in a round-bottom flask, and uniformly stirring by magnetic force (the stirring speed is 500 rpm) to prepare a first solution; then 12mL of tetraethoxysilane and 30mL of absolute ethyl alcohol are mixed and stirred evenly to prepare a second solution. And quickly pouring the second solution into the first solution under stirring, taking care to avoid the second solution from contacting the wall of the flask as much as possible, continuously stirring for 2min, reducing the stirring speed to 300rpm, sealing the flask opening with a sealing film, and stirring at 30 ℃ for 24h to react to obtain the 100nm silicon ball solution.
2) Taking 60mL of the 100nm silicon ball solution (serving as a macroporous template) prepared in the step 1) into a round-bottom flask, adding 2.0mL of 15nm silicon balls (directly purchased and serving as a mesoporous template), and uniformly stirring. Subsequently, tris buffer was added to the silica sphere mixture, the pH was adjusted to 8.5, then 0.84g dopamine (as a carbon and nitrogen source) was added with constant stirring, and stirred under sealed conditions at 30 ℃ for 24h. And fully volatilizing the reacted mixed solution at room temperature to obtain a solid, placing the solid in a tubular furnace, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min in the nitrogen atmosphere, keeping the temperature for 2 hours, raising the temperature to 900 ℃ at the heating rate of 5 ℃/min, and keeping the temperature for 3 hours to obtain the nitrogen-doped carbon material containing the silicon template. Placing the mixture into 3mol/L sodium hydroxide solution at 90 ℃, repeating the process for multiple times, washing and filtering the mixture by using distilled water and ethanol for multiple times, and drying the mixture in a vacuum drying oven to obtain the NC material.
3) Dissolving lignin (KL) in acetonitrile and water (7: 3,v/v) to obtain 60mL of a 5mg/mL KL solution, and further adding 30mg NC to the above solution to obtain a KL/NC suspension. And magnetically stirring the suspension for 30min, performing ultrasonic treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge at 9000rmp for 15min, pouring out supernatant, and drying in a drying box for 12h to obtain the KL/NC material, wherein the KL/NC material is the composite energy storage material.
In this example, the parameters other than the nitrogen-oxygen ratio, the specific surface area and the total pore volume were out of the preferable ranges of the present invention.
Example 5
A composite energy storage material comprises a hierarchical pore nitrogen-oxygen carbon material and a lignin material loaded on the hierarchical pore nitrogen-oxygen carbon material; the hierarchical pore nitrogen-oxygen carbon material comprises a nitrogen-oxygen carbon material, macropores and mesopores, wherein the macropores are uniformly distributed in the nitrogen-oxygen carbon material, and the mesopores are uniformly distributed around the macropores; the lignin material is lignin.
The proportion of nitrogen in the hierarchical pore nitrogen-oxygen carbon material is 2.63 percent, and the proportion of oxygen is 10.13 percent;
the specific surface area of the composite energy storage material is 422.34m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 75.45 percent of the specific surface area of the composite energy storage material;
the total pore volume in the composite energy storage material is 0.904cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 93.58 percent of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparing 100nm silicon spheres with uniform size: mixing 12mL of deionized water, 42mL of absolute ethyl alcohol and 2.4mL of ammonia water in a round-bottom flask, and uniformly stirring by magnetic force (the stirring speed is 500 rpm) to prepare a first solution; then 12mL of ethyl orthosilicate and 30mL of absolute ethyl alcohol are mixed and stirred uniformly to prepare a second solution. And quickly pouring the second solution into the first solution under stirring, taking care to avoid the second solution from contacting the wall of the flask as much as possible, continuously stirring for 2min, reducing the stirring speed to 300rpm, sealing the flask opening, and stirring at 30 ℃ for 24h to obtain the 100nm silicon ball solution.
2) Taking 60mL of the 100nm silicon sphere solution (serving as a macroporous template) prepared in the step 1) into a round-bottom flask, adding 2.4mL of 12nm silicon spheres (directly purchased and serving as a mesoporous template), and uniformly stirring. Subsequently, tris buffer was added to the silica sphere mixture, the pH was adjusted to 8.5, then 0.84g dopamine (as a carbon and nitrogen source) was added with constant stirring, and stirred under sealed conditions at 30 ℃ for 24h. And fully volatilizing the reacted mixed solution at room temperature to obtain a solid, placing the solid in a tubular furnace, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min in the nitrogen atmosphere, keeping the temperature for 2 hours, and raising the temperature to 900 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 3 hours to obtain the nitrogen-doped carbon material containing the silicon template. Placing the mixture into 3mol/L sodium hydroxide solution at 90 ℃, repeating the process for multiple times, washing and filtering the mixture by using distilled water and ethanol for multiple times, and drying the mixture in a vacuum drying oven to obtain the NC material.
3) Taking lignin obtained in step 2)(KL) was dissolved in a mixed solution of acetonitrile and water (7,3,v/v) to prepare 60mL of a 5mg mL solution -1 And further adding 30mg of NC to the above solution to obtain a KL/NC suspension. And magnetically stirring the suspension for 30min, performing ultrasonic treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge at 9000rmp for 15min, pouring out supernatant, and drying in a drying box for 12h to obtain the KL/NC material, wherein the KL/NC material is the composite energy storage material.
All parameters in this example are within the preferred ranges of the present invention.
It can be seen from fig. 1 (a) and 1 (c) that NC is a honeycomb-shaped porous material, pore channels are uniformly distributed in a circular shape, the diameter is about 200nm, mesopores with the diameter of about 15nm are uniformly distributed on macropores, the mesopores are formed by pore-forming of 12nm silicon spheres, and the mesopores are communicated with the macropores to form a multi-level pore structure. It can be seen from fig. 1 (b) and fig. 1 (d) that in OKL/NC, the macropore and mesopore channels remain.
As can be seen from FIGS. 2 (a) and 2 (b), the specific surface area of NC was 640.20m 2 Per g, wherein the specific surface area of the micropores is 123.92m 2 (iv)/g, total pore volume 1.344cm 3 (ii) each mesoporous structure (1.265 cm) 3 (ii)/g; the specific surface area of KL/NC was 422.34m 2 Per g, pore volume 0.904cm 3 Both are reduced compared with NC.
As can be seen from fig. 3 (a) and 3 (b), four peaks of high-resolution N1s spectral decomposition of NC and KL/NC correspond to pyridine type nitrogen, pyrrole type nitrogen, graphite type nitrogen, and pyridine oxide type nitrogen, respectively, where the pyridine type nitrogen, the pyrrole type nitrogen, and the pyridine oxide type nitrogen are all located at the edge of the graphite layer; the graphite nitrogen and the pyridine nitrogen have good electrochemical activity; the KL/NC ratio of pyridine nitrogen to pyrrole nitrogen is improved compared with NC.
Electrochemical testing Using CHI 760D electrochemical workstation at 1mol/L H 2 SO 4 The method is carried out in the electrolyte by adopting a conventional three-electrode configuration, namely a working electrode, a counter electrode and a reference electrode, a platinum net is used as the counter electrode, and a Saturated Calomel Electrode (SCE) is used as the reference electrode. The Cyclic Voltammetry (CV) test was performed at a voltage window of 0-0.8V (vs. SCE) with scan rates of 1, 10, 20, respectively50, 100mV/s. Charging and Discharging (GCD) are also carried out in a voltage window of 0-0.8V (vs. SCE), and the discharge multiplying power is 0.5, 1, 2, 5, 10 and 20A/g respectively.
As can be seen from fig. 4, the CV curve of NC exhibits a rectangular shape with a pronounced hump, which is formed by the double layer of carbon doped with nitrogen in combination with the pseudocapacitance; two pairs of obvious reversible redox peaks appear on a CV curve of KL/NC, which shows that the pseudocapacitance of a sample in the energy storage process is triggered by two mechanisms, namely a peak triggered by an NC oxygen-containing group at 0.3V and a peak caused by a quinone group in lignin at 0.52V; the CV curve of KL/NC is obviously larger than that of NC, and the KL/NC is obviously improved in capacitance compared with NC.
From the charge-discharge curves of FIG. 5, it was calculated that the specific capacitances of NC and KL/NC were 154F/g and 412F/g, respectively.
Example 6
Different from the embodiment 1, the composite energy storage material is prepared by the following steps of: mixing and stirring the lignin solution and hydrogen peroxide for 6 hours, and then sequentially carrying out solid-liquid separation and vacuum drying to obtain oxidized lignin; wherein the mass concentration of the hydrogen peroxide is 30wt%, and the concentration of the lignin solution is 5mg/L. The rest is the same as in example 1.
Comparative example 1
A composite energy storage material comprises a hierarchical pore oxygen-carbon material and a lignin material loaded on the hierarchical pore oxygen-carbon material; the hierarchical porous carbon material comprises an oxygen carbon material, macropores and mesopores; the lignin material is lignin.
The oxygen content of the hierarchical pore nitrogen-oxygen carbon material is 6.63%;
the specific surface area of the composite energy storage material is 811.73m 2 /g;
The sum of the specific surface areas of the macropores and the mesopores accounts for 62.89% of the specific surface area of the composite energy storage material;
the total pore volume in the composite energy storage material is 2.03cm 3 /g;
The sum of the volumes of the macropores and the mesopores accounts for 88.10 percent of the volume of the composite energy storage material.
The preparation method of the composite energy storage material comprises the following steps:
1) Preparation of resol: 15.6g of phenol was put in a flask, heated in a water bath at 45 ℃ to melt, and then 2g of a sodium hydroxide solution (20 wt% in concentration) was added to the flask, and magnetically stirred uniformly (stirring speed 500 rpm), and then 20g of a formaldehyde solution (37 wt% in solution concentration) was added to the flask (stirring speed increased to 800 rpm), and heated to 70 ℃ and held for 1 hour to obtain a bright yellow aqueous solution of a resol resin.
2) Preparation of porous carbon: mixing the resol prepared in the step 1) with 2mol/L of ammonium chloride aqueous solution according to the volume ratio of 3. The mixed solution was transferred to a porcelain boat, followed by freeze-drying at-40 ℃. And (3) placing the dried sample in a tube furnace, heating to 400 ℃ at a heating rate of 1 ℃/min in a nitrogen atmosphere, heating to 750 ℃ at a heating rate of 5 ℃/min, keeping for 2 hours, cooling to room temperature, washing and filtering the sample for multiple times by using distilled water and ethanol, and drying in a vacuum drying oven to obtain the porous carbon.
3) Activation of the carbon material: mixing the porous carbon prepared in the step 2) with a potassium hydroxide solid according to a mass ratio of 4. And then placing the porous carbon material in a tubular furnace, raising the temperature to 800 ℃ at a heating rate of 5 ℃/min in a nitrogen atmosphere, keeping the temperature for 1h, cooling to room temperature, placing the porous carbon material in a hydrochloric acid solution of 1mol/L, repeating the steps for multiple times, washing and filtering the solution for multiple times by using distilled water and ethanol, and drying the solution in a vacuum drying oven to obtain the porous carbon material (PC).
4) Lignin (KL) was dissolved in acetonitrile and water (7: 3,v/v) to obtain 60mL of a 5mg/mL KL solution, and further adding 30mg of porous carbon to the above solution to obtain a KL/PC suspension. And magnetically stirring the suspension for 30min, performing ultrasonic treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge at 9000rmp for 15min, pouring out supernatant, and drying in a drying oven for 12h to obtain the KL/PC material, wherein the KL/PC material is the composite energy storage material.
Comparative example 2
A composite energy storage material comprises carbon nanotubes and a lignin material loaded on the carbon nanotubes; the carbon nanotube is directly purchased and is not subjected to other treatment; the lignin material is lignin.
The preparation method of the composite energy storage material comprises the following steps:
lignin (KL) was dissolved in a mixed solution of acetonitrile and water (7,3,v/v) to prepare 60mL of a 5mg mL solution containing 60mL of lignin (KL) -1 And then 30mg of Carbon Nanotubes (CNT) was added to the above solution to obtain a KL/CNT suspension. And magnetically stirring the suspension for 30min, performing ultrasonic treatment in an ultrasonic instrument for 5min, centrifuging the suspension in a centrifuge for 15min at 9000rmp, pouring out supernatant, and drying in a drying oven for 12h to obtain the KL/CNT material, wherein the KL/CNT material is the composite energy storage material.
Comparative example 3
A composite energy storage material comprises graphene and a lignin material loaded on the graphene; the graphene is prepared by a physical method of direct purchase, and is not subjected to other treatment; the lignin material is lignin. The rest is the same as comparative example 2.
Comparative example 4
A composite energy storage material comprises activated carbon and a lignin material loaded on the activated carbon; the activated carbon was purchased directly and without further treatment; the lignin material is lignin. The rest is the same as comparative example 2.
The composite energy storage materials of examples 1 to 4, example 6 and comparative examples 1 to 4 were subjected to electrochemical performance tests in the same manner as in example 5, and the results are shown in table 1.
TABLE 1
Group of
|
Specific capacitance
|
Example 1
|
198F/g
|
Example 2
|
257F/g
|
Example 3
|
303F/g
|
Example 4
|
348F/g
|
Example 5
|
412F/g
|
Example 6
|
317F/g
|
Comparative example 1
|
223F/g
|
Comparative example 2
|
138F/g
|
Comparative example 3
|
191F/g
|
Comparative example 4
|
120F/g |
While particular embodiments of the present invention have been illustrated and described, it would be obvious that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.