Preparation method of biomass hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material
Technical Field
The invention belongs to the technical field of preparation of electrode materials of supercapacitors, and particularly relates to a preparation method of a biomass hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material.
Background
Energy is an important material basis on which human society relies for survival and sustained development. As a novel energy storage device, the super capacitor can complete the charging and discharging process within several seconds based on high power, is free from maintenance for a long time, can be used within a wide temperature range, has high safety and other excellent energy storage performances, has huge application value and market potential in the fields of new energy electric vehicles, uninterruptible power supplies, intelligent start-stop, aerospace, transportation, electric power energy, engineering machinery, military industry and national defense and the like, and the key factor determining the performance of the super capacitor is an electrode material. The hierarchical porous carbon material is one of the ideal carbon-based electrode materials of the super capacitor. The structure of the material is distributed with interconnected micropores, mesopores and macropores. The micropores determine the capacitance effect of the electric double layer, the mesopores provide channels for the transmission of ions, and the macropores are equivalent to an ion storage bank, so that the diffusion distance of the ions is shortened. The macroporous-mesoporous-microporous interconnected structural material overcomes the defects of single-level pore structures such as the traditional activated carbon. The oxygen, nitrogen and other doped atomic groups can improve the wetting capacity, the conductivity and the Faraday effect of the surface of the carbon material and the electrolyte solution to increase the specific capacity of the electrode material. At present, a template method is a commonly used main technology for preparing a hierarchical pore structure carbon material, but has the series problems of long preparation process period, complex process, environmental friendliness and the like. The invention prepares the oxygen-nitrogen heteroatom-doped hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material with excellent capacitance performance by using an economic, environment-friendly, simple and feasible process technology.
Disclosure of Invention
The invention solves the technical problem of providing a preparation method of a biomass multilevel pore nano ring microstructure carbon-based supercapacitor electrode material with simple process and low cost.
The invention adopts the following technical scheme for solving the technical problems, and the preparation method of the biomass hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material is characterized by comprising the following specific processes:
step S1: cleaning waste sweet potato stems, stems and leaves with deionized water, placing the cleaned waste sweet potato stems, stems and leaves in a forced air drying oven, drying the waste sweet potato stems, stems and leaves for 24 hours at 65 ℃ to remove water in a sample, and crushing dried biomass into biomass powder by a crusher for later use;
step S2: putting the biomass powder obtained in the step S1 into a tubular furnace, heating the biomass powder from room temperature to 600 ℃ at a heating rate of 5 ℃/min under the protection of inert gas, pyrolyzing the biomass powder for 2 hours at a constant temperature, and naturally cooling the biomass powder to room temperature to obtain biomass carbide;
step S3: mixing the biomass carbide obtained in the step S2 with an activating agent potassium hydroxide according to a mass ratio of 1: 3-5, adding water to soak the mixture, placing the mixture in a blast drying oven for drying, placing the mixture in a tubular furnace, heating the mixture from room temperature to 600-900 ℃ at a heating rate of 10 ℃/min under the protection of inert gas, carrying out constant-temperature activation treatment for 2 hours, and then naturally cooling the mixture to room temperature to obtain a crude product;
step S4: and (4) soaking the crude product obtained in the step (S3) in a 2mol/L hydrochloric acid solution for 24h, washing with deionized water until the filtrate is neutral, and then placing in a forced air drying oven to dry to obtain the electrode material of the multistage pore nano-ring microstructure carbon-based supercapacitor.
Preferably, the inert gas in steps S2 and S3 is nitrogen or argon.
Preferably, the mass ratio of the biomass carbide to the activator potassium hydroxide in the step S3 is 1: 4.
Preferably, the constant temperature activation treatment temperature in step S3 is 700 ℃.
Preferably, the preparation method of the biomass hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material is characterized by comprising the following specific steps:
step S1: cleaning waste sweet potato stems, stems and leaves with deionized water, placing the cleaned waste sweet potato stems, stems and leaves in a forced air drying oven, drying the waste sweet potato stems, stems and leaves for 24 hours at 65 ℃ to remove water in a sample, and crushing dried biomass into biomass powder by a crusher for later use;
step S2: placing 9g of the biomass powder obtained in the step S1 in a tubular furnace, heating the biomass powder from room temperature to 600 ℃ at a heating rate of 5 ℃/min under the protection of inert gas, carrying out constant-temperature pyrolysis for 2h, and naturally cooling the biomass powder to room temperature to obtain biomass carbide;
step S3: mixing 1g of the biomass carbide obtained in the step S2 with 4g of activating agent potassium hydroxide, adding 10mL of water, soaking for 24h, placing in a forced air drying oven, drying at 120 ℃, placing the mixture in a tubular furnace, heating from room temperature to 700 ℃ at a heating rate of 10 ℃/min under the protection of inert gas, carrying out constant-temperature activation treatment for 2h, and then naturally cooling to room temperature to obtain a crude product;
step S4: soaking the crude product obtained in the step S3 in 2mol/L hydrochloric acid solution for 24h, washing with deionized water until the filtrate is neutral, and then drying in a forced air drying oven at 80 ℃ to obtain the electrode material of the multistage pore nano-ring microstructure carbon-based supercapacitor;
the specific surface area of the electrode material of the multistage-hole nano-ring microstructure carbon-based supercapacitor is up to 3115m2In a constant current charge and discharge test, the specific capacitance of 1A/g under a constant current density is 532.5F/g, the specific capacitance of 264F/g can be released under a large current density of 30A/g, and the specific capacitance retention rate reaches 95.1 percent after 10000 cycles when the current density is 30A/g.
Compared with the prior art, the invention has the following beneficial effects:
1. the raw materials used in the invention are cheap, the preparation process is simple, and the specific surface area and the pore size distribution of the carbon material can be controlled by regulating the proportion of the biomass and the activating agent and the activation temperature;
2. the biomass hierarchical pore nano-ring microstructure carbon-based supercapacitor electrode material prepared by the method has the advantages of stable structure, excellent electrochemical performance, long cycle life, high specific capacitance and the like, and is very suitable for being used as a supercapacitor electrode material;
3. the oxygen-nitrogen co-doped nano-ring microstructure carbon material is obtained by self-doping in biomass and externally doping activated oxygen, and the specific surface area is as high as 3115m2G, in constant current charge and discharge test, at a constant current density of 1A/gThe specific capacitance of the electrode is 532.5F/g, the 264F/g specific capacitance can still be released under the large current density of 30A/g, the specific capacitance retention rate of the electrode reaches 95.1 percent after 10000 cycles when the current density is 30A/g, and the carbon supercapacitor electrode material prepared by the method has potential application prospects.
Drawings
FIG. 1 is a field emission scanning electron microscope image of the electrode material of the carbon-based supercapacitor with the hierarchical porous nanoring microstructure prepared in example 4;
FIG. 2 is a transmission electron microscope image of the electrode material of the carbon-based supercapacitor with the hierarchical porous nanoring microstructure prepared in example 4;
FIG. 3 is a pore size distribution diagram of the electrode material of the carbon-based supercapacitor with the multilevel pore nano-ring microstructure prepared in example 4;
FIG. 4 is an infrared spectrum of the multi-level pore nanoring microstructure carbon-based supercapacitor electrode material prepared in examples 2 to 5 and 7;
FIG. 5 is a mass specific capacitance diagram of the multi-level pore nano-ring microstructure carbon-based supercapacitor electrode material prepared in examples 3 to 5 under different current densities.
Detailed Description
The present invention is described in further detail below with reference to examples, but it should not be construed that the scope of the above subject matter of the present invention is limited to the following examples, and that all the technologies realized based on the above subject matter of the present invention belong to the scope of the present invention.
Example 1
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 3g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a biomass BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tubular furnace, vacuumizing the nickel boat, replacing air in the tubular furnace with nitrogen, heating the mixture from room temperature to 600 ℃ at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the mixture to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-1 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 2
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 3g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tube furnace, vacuumizing the tube furnace, replacing air in the tube furnace with nitrogen, heating the tube furnace to 700 ℃ from room temperature at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the tube furnace to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-2 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 3
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 4g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tubular furnace, vacuumizing the nickel boat, replacing air in the tubular furnace with nitrogen, heating the mixture from room temperature to 600 ℃ at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the mixture to room temperature to obtain a crude product;
the above example describes that in the step (4), the crude product is added into a container containing 2mol/L hydrochloric acid solution to be soaked for 24 hours, filtered, washed by high-purity water until the filtrate is neutral, and then dried for 24 hours at 80 ℃ to obtain the electrode material BLSC-3 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 4
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 4g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tube furnace, vacuumizing the tube furnace, replacing air in the tube furnace with nitrogen, heating the tube furnace to 700 ℃ from room temperature at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the tube furnace to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-4 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 5
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 4g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tube furnace, vacuumizing the tube furnace, replacing air in the tube furnace with nitrogen, heating the tube furnace to 800 ℃ from room temperature at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the tube furnace to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-5 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 6
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 4g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tubular furnace, vacuumizing the nickel boat, replacing air in the tubular furnace with nitrogen, heating the mixture from room temperature to 900 ℃ at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the mixture to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-6 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
Example 7
(1) Putting 9g of sweet potato stem leaf powder into a porcelain boat, putting the porcelain boat into a tubular furnace, vacuumizing the porcelain boat, replacing air in the tubular furnace with nitrogen, heating the porcelain boat to 600 ℃ from room temperature at a heating rate of 5 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature pyrolysis treatment for 2 hours, and naturally cooling the porcelain boat to room temperature to obtain biomass carbide, which is recorded as BLSC-0;
(2) putting 1g of BLSC-0 and 5g of solid KOH into a container, adding 10mL of deionized water, fully stirring and mixing uniformly, standing at room temperature for 24h, and drying at 120 ℃ to obtain a BLSC-0/KOH mixture;
(3) transferring the BLSC-0/KOH mixture into a nickel boat, placing the nickel boat into a tube furnace, vacuumizing the tube furnace, replacing air in the tube furnace with nitrogen, heating the tube furnace to 700 ℃ from room temperature at a heating rate of 10 ℃/min under the protection of normal-pressure nitrogen, carrying out constant-temperature activation treatment for 2 hours, and naturally cooling the tube furnace to room temperature to obtain a crude product;
(4) and adding the crude product into a container containing 2mol/L hydrochloric acid solution, soaking for 24h, filtering, washing with high-purity water until the filtrate is neutral, and drying at 80 ℃ for 24h to obtain the electrode material BLSC-7 of the hierarchical pore nano-ring microstructure carbon supercapacitor.
The basic principles, principal features and advantages of the invention, it should be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only for the purpose of illustrating the principles of the invention, and that various changes and modifications may be made therein without departing from the scope of the principles of the invention, which fall within the scope of the invention.