CN115101353A

CN115101353A - Polyatomic-doped lignin carbon-based electrode material and preparation method thereof

Info

Publication number: CN115101353A
Application number: CN202210605640.XA
Authority: CN
Inventors: 吴文娟; 李鹏辉; 魏雨濛; 吴彩文; 张佳芮; 陈薇; 陶雨婷
Original assignee: Nanjing Forestry University
Current assignee: Nanjing Forestry University
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2022-09-23

Abstract

The invention belongs to the field of electrode material preparation, and particularly relates to a polyatomic-doped lignin carbon-based electrode material and a preparation method thereof. The method comprises the steps of adding lignosulfonate into an aniline solution, uniformly mixing, reacting under the action of an oxidant, filtering, washing and drying to obtain a lignin/polyaniline precursor, and sequentially pre-carbonizing and activating to obtain the polyatomic lignin carbon-based electrode material. Polyaniline and lignosulfonate with rich nitrogen content are used as raw materials to prepare a carbon-based electrode material, O, N, S multi-element doped layered porous carbon material with rich mesopores and high surface area can be prepared, the carbon material provides electron acceptor graphite N and S elements capable of generating lattice defects, the charge mobility is improved, the nitrogen or adjacent functional group redox reaction is promoted, and the obtained lignin carbon-based electrode material has high specific capacitance and good cycle stability.

Description

Polyatomic-doped lignin carbon-based electrode material and preparation method thereof

Technical Field

The invention belongs to the field of electrode material preparation, and particularly relates to a polyatomic lignin carbon-based electrode material and a preparation method thereof.

Background

Carbonaceous materials have received great attention due to their large specific surface area, adjustable pore size, excellent physicochemical stability, easy processability, and relatively low cost. Currently, many researchers are working on developing novel carbon-based electrode materials, such as porous carbon, carbon nanotubes, carbon spheres, carbon aerogel, graphene, and the like. Among them, porous carbon electrode materials have attracted researchers' interest as capacitor electrode materials.

Generally, the pure porous carbon material has lower activity, and if an activating agent is added, the specific surface area of the material can be effectively enlarged, and the pore structure and the properties are improved. And because the lignin has a natural and abundant pore structure, the lignin is beneficial to an activating agent to enter a carbon precursor matrix and promotes the formation of pores, when the lignin is used for preparing the porous electrode material, micropores of the lignin can provide abundant sites as charge accumulation positions, mesopores can be used as channels for shortening ion diffusion distance, and macropores can be used as reservoirs for buffering electrolyte ions, so the lignin is an electrode raw material with good performance.

The Chinese patent with publication number CN202110729967.3, 11/16/2021, discloses an in-situ doped polyaniline gel electrode, which is prepared by dissolving microcrystalline cellulose and dealkalized lignin in NaOH/urea solution, adding epichlorohydrin, transferring to a polytetrafluoroethylene culture dish, and placing in an oven at 80-100 ℃ for cross-linking reaction to obtain cellulose/dealkalized lignin hydrogel; and then, obtaining the crosslinked composite electrode material by using cellulose/dealkalized lignin aerogel and aniline through an oxidative polymerization method. The preparation method is complex and the process is complicated. How to simply and efficiently prepare the carbon-based electrode material with excellent performance by utilizing lignin is a problem which needs to be solved urgently.

Disclosure of Invention

The invention provides a polyatomic-doped lignin carbon-based electrode material and a preparation method thereof, aiming at simply and efficiently preparing a carbon-based electrode material with excellent performance by using lignin.

A preparation method of a multi-atom doped lignin carbon-based electrode material comprises the following steps:

s1: dissolving aniline in hydrochloric acid to obtain an aniline solution, then adding lignosulfonate into the aniline solution, uniformly mixing, reacting under the action of an oxidant, filtering, washing and drying to obtain a lignin/polyaniline precursor;

s2: and sequentially pre-carbonizing and activating the lignin/polyaniline precursor to obtain the polyatomic lignin carbon-based electrode material.

Preferably, the pre-carbonization process in S2 specifically includes: and (3) putting the lignin/polyaniline precursor dried to constant weight into a tubular furnace, carbonizing at 380-450 ℃ for 1-2h, and grinding to obtain a powder sample.

Preferably, the activation process in S2 specifically includes the following steps: dissolving an activating agent in deionized water, adding the powder sample, stirring, mixing and drying; then placing the mixture in a tube furnace to obtain N ₂ Heating to 500-900 ℃ at the heating rate of 5 ℃/min in the atmosphere, and preserving the heat for 2 h; and cooling to room temperature after heat preservation is finished, repeatedly washing to be neutral by using hydrochloric acid and distilled water, and drying to obtain the polyatomic-doped lignin carbon-based electrode material.

Preferably, the activating agent is KOH or NaOH, and the temperature rise in the activation process in S2 is 700 ℃.

Preferably, the drying in S1 is performed by freeze drying.

Preferably, the molar ratio of the aniline to the oxidant in S1 is (1-4): 1.

Preferably, the mass ratio of the aniline to the lignosulfonate in S1 is 1 (2.5-6).

Preferably, the oxidant is ammonium persulfate.

Preferably, the reaction temperature in S1 is 0-4 ℃, and the reaction time is 24 h.

A multi-atom doped lignin carbon-based electrode material is prepared by adopting the method.

Compared with the prior art, the invention has the beneficial effects that:

polyaniline and lignosulfonate with rich nitrogen content are used as raw materials to prepare a carbon-based electrode material, so that an O, N, S multi-element doped layered porous carbon material with rich mesopores and high surface area can be prepared;

when polyaniline is synthesized in the presence of lignin, similar nanorod aggregates can be generated, and due to the fact that the layered porous carbon has more nucleation sites, polyaniline nanoparticles have good dispersibility and compatibility;

the electrode material is prepared from the lignin/polyaniline precursor prepared from lignin and polyaniline, and the carbon material provides electron acceptor graphite N and S elements capable of generating lattice defects, so that the improvement of charge mobility is facilitated, and oxidation-reduction reaction of nitrogen or adjacent functional groups is promoted, so that the obtained lignin carbon-based electrode material is high in specific capacitance and good in cycling stability.

Drawings

FIG. 1 is a scanning electron microscope image of the materials obtained in examples 1 to 3 and example 6 of the present application: NC700(a-b), SNC500(c-d), SNC700(e-f), SNC900 (g-h);

FIG. 2 is a transmission electron microscope image of the materials obtained in examples 1 to 3 and example 6 of the present application: NC700(a-b), SNC500(c), SNC700(e-f), SNC900 (d);

FIG. 3 is XPS survey spectrum and C1S, N1S, S2p fine spectrum of the material obtained in examples 1-3 of the present application;

FIG. 4 is a graph of electrochemical AC impedance spectra of materials obtained in examples 1-3 and example 6 of the present application;

FIG. 5 shows specific capacitance and capacitance retention after 5000 cycles of the material obtained in example 1 of the present application.

Detailed Description

The invention is further described with reference to specific examples.

Source of raw materials

Sodium lignosulfonate, product code L0098, CAS number 8061-51-6, purchased from Chinesia elegans (Shanghai) chemical industry development Co., Ltd.;

the alkaline lignin was purchased from shanghai alatin biochemical science and technology, inc, CAS No.: 8068-05-1.

Example 1

Uniformly dispersing 0.91mL of purified aniline in 100mL of 1M HCl, adding 4g of sodium lignosulfonate into the aniline solution, and magnetically stirring at 0 ℃ for 2 hours to obtain a lignin/aniline mixed solution; weighing 2.28g of ammonium persulfate, placing the ammonium persulfate in 100mL of 1M HCl, and stirring for 24 hours to obtain a uniform ammonium persulfate solution; mixing the lignin/aniline mixed solution with an ammonium persulfate solution according to the molar ratio of 1: 1 of aniline to ammonium persulfate, and carrying out magnetic stirring reaction at 4 ℃ for 24 hours. And filtering the reaction product, repeatedly washing the reaction product with deionized water and ethanol, drying the reaction product in a freeze dryer for 48 hours until the weight of the reaction product is constant to obtain a dark green solid, namely the lignin/polyaniline precursor.

And (3) taking 2g of lignin/polyaniline precursor, carbonizing the lignin/polyaniline precursor for 1.5h at 400 ℃ in a tubular furnace to obtain a powder sample, and fully grinding the powder sample. Mixing the ground powder with a solid activating agent KOH according to the impregnation mass ratio of 1: 1, stirring for 5h to be uniform, drying for 12h in a vacuum drying oven at 80 ℃, and then in a tube furnace N ₂ Heating to 700 ℃ at the heating rate of 5 ℃/min under the atmosphere, preserving the heat for 2h, annealing for 4h, and cooling to the room temperature. And then the carbon-based electrode material is placed in 1M HCl for washing to remove a KOH activating agent, then distilled water is used for repeatedly washing until the pH value is neutral, and the washed filter residue is dried in a 105 ℃ forced air drying oven to constant weight, so that the polyatomic lignin carbon-based electrode material is obtained, and the label of the polyatomic lignin carbon-based electrode material is SNC 700.

Example 2

And (3) taking 2g of lignin/polyaniline precursor, carbonizing the lignin/polyaniline precursor for 1.5h at 400 ℃ in a tubular furnace to obtain a powder sample, and fully grinding the powder sample. Mixing the ground powder with a solid activating agent KOH according to the impregnation mass ratio of 1: 1, stirring for 5h to be uniform, drying for 12h in a vacuum drying oven at 80 ℃, and then in a tube furnace N ₂ Heating to 500 ℃ at the heating rate of 5 ℃/min under the atmosphere, preserving the heat for 2h, annealing for 4h, and cooling to room temperature. And then washing the electrode material in 1M HCl to remove a KOH activating agent, repeatedly washing the electrode material with distilled water until the pH value is neutral, and drying the washed filter residue in a 105 ℃ forced air drying oven to constant weight to obtain the polyatomic lignin carbon-based electrode material which is marked as SNC 500.

Example 3

Uniformly dispersing 0.91mL of purified aniline in 100mL of 1M HCl, adding 4g of sodium lignosulfonate into the aniline solution, and magnetically stirring for 2 hours at the temperature of 0 ℃ to obtain lignin/aniline mixed solution; weighing 2.28g of ammonium persulfate, placing the ammonium persulfate in 100mL of 1M HCl, and stirring for 24 hours to obtain a uniform ammonium persulfate solution; mixing the lignin/aniline mixed solution with an ammonium persulfate solution according to the molar ratio of 1: 1 of aniline to ammonium persulfate, and carrying out magnetic stirring reaction at 4 ℃ for 24 hours. And filtering the reaction product, repeatedly washing the reaction product with deionized water and ethanol, drying the reaction product for 48 hours in a freeze dryer until the weight of the reaction product is constant to obtain a dark green solid, namely the lignin/polyaniline precursor.

And (3) taking 2g of lignin/polyaniline precursor, carbonizing the lignin/polyaniline precursor for 1.5h at 400 ℃ in a tubular furnace to obtain a powder sample, and fully grinding the powder sample. Mixing the ground powder with a solid activating agent KOH according to the impregnation mass ratio of 1: 1, stirring for 5h to be uniform, drying for 12h in a vacuum drying oven at 80 ℃, and then in a tube furnace N ₂ At 5 ℃/m under atmosphereAnd in, heating to 900 ℃ at the heating rate, keeping the temperature for 2h, annealing for 4h, and cooling to room temperature. And then washing the electrode material in 1M HCl to remove a KOH activating agent, repeatedly washing the electrode material with distilled water until the pH value is neutral, and drying the washed filter residue in a 105 ℃ forced air drying oven to constant weight to obtain the polyatomic lignin carbon-based electrode material which is marked as SNC 900.

Example 4

Uniformly dispersing 0.91mL of purified aniline in 100mL of 1M HCl, adding 5.5g of sodium lignosulfonate into an aniline solution, and magnetically stirring at 0 ℃ for 2 hours to obtain a lignin/aniline mixed solution; weighing 2.28g of ammonium persulfate, placing the ammonium persulfate in 100mL of 1M HCl, and stirring for 24 hours to obtain a uniform ammonium persulfate solution; mixing the lignin/aniline mixed solution with an ammonium persulfate solution according to the molar ratio of aniline to ammonium persulfate of 4: 1, and carrying out magnetic stirring reaction at 4 ℃ for 24 hours. And filtering the reaction product, repeatedly washing the reaction product with deionized water and ethanol, drying the reaction product for 48 hours in a freeze dryer until the weight of the reaction product is constant to obtain a dark green solid, namely the lignin/polyaniline precursor.

And (3) taking 2g of lignin/polyaniline precursor, carbonizing the lignin/polyaniline precursor for 1.5h at 400 ℃ in a tubular furnace to obtain a powder sample, and fully grinding the powder sample. Mixing the ground powder with a solid activating agent NaOH according to the impregnation mass ratio of 1: 1, stirring for 5h to be uniform, drying for 12h in a vacuum drying oven at 80 ℃, and then drying in a tube furnace N ₂ Heating to 700 ℃ at the heating rate of 5 ℃/min under the atmosphere, preserving the heat for 2h, annealing for 4h, and cooling to the room temperature. And then washing the electrode material in 1M HCl to remove NaOH activating agent, repeatedly washing the electrode material with distilled water until the pH value is neutral, and drying the washed filter residue in a 105 ℃ forced air drying oven to constant weight to obtain the polyatomic lignin carbon-based electrode material.

Example 5

Uniformly dispersing 0.91mL of purified aniline in 100mL of 1M HCl, adding 2.5g of sodium lignosulfonate into an aniline solution, and magnetically stirring at 0 ℃ for 2 hours to obtain a lignin/aniline mixed solution; weighing 2.28g of ammonium persulfate, placing the ammonium persulfate in 100mL of 1M HCl, and stirring for 24 hours to obtain a uniform ammonium persulfate solution; mixing the lignin/aniline mixed solution with an ammonium persulfate solution according to the molar ratio of aniline to ammonium persulfate of 3: 1, and carrying out magnetic stirring reaction at 4 ℃ for 24 hours. And filtering the reaction product, repeatedly washing the reaction product with deionized water and ethanol, drying the reaction product in a freeze dryer for 48 hours until the weight of the reaction product is constant to obtain a dark green solid, namely the lignin/polyaniline precursor.

2g of lignin/polyaniline precursor is taken and placed in a tube furnace for carbonization at 400 ℃ for 1.5h to obtain a powder sample, and the powder sample is fully ground. Mixing the ground powder with a solid activating agent KOH according to the impregnation mass ratio of 1: 1, stirring for 5h to be uniform, drying for 12h in a vacuum drying oven at 80 ℃, and then in a tube furnace N ₂ Heating to 700 ℃ at a heating rate of 5 ℃/min under the atmosphere, preserving heat for 2h, annealing for 4h, and cooling to room temperature. And then washing the electrode material in 1M HCl to remove a KOH activating agent, repeatedly washing the electrode material with distilled water until the pH value is neutral, and drying the washed filter residue in a 105 ℃ forced air drying oven to constant weight to obtain the polyatomic lignin carbon-based electrode material.

Example 6

The present embodiment is different from embodiment 1 in that: in this example, sodium lignosulfonate was not added, the procedure was otherwise the same as in example 1, and the obtained electrode material was designated as NC 700.

Example 7

The present embodiment is different from embodiment 1 in that: in this example, sodium lignosulfonate was replaced with an equal amount of alkaline lignin and the rest was the same as in example 1.

Example 8

The present embodiment is different from embodiment 1 in that: in this example, vacuum drying at 60 ℃ was used instead of freezer drying.

Example 9

The present embodiment is different from embodiment 1 in that: in this example, aniline was dispersed in 100mL of 1M p-toluenesulfonic acid, with the equivalent amount of hydrochloric acid being replaced by p-toluenesulfonic acid.

Example 10

The present embodiment is different from embodiment 1 in that: in this example aniline was dispersed in 100mL of 1M sulfuric acid, and the equivalent amount of hydrochloric acid was replaced with sulfuric acid.

The electrode materials obtained in examples 1 to 3 and 6 were subjected to relevant tests such as scanning electron microscopy, transmission electron microscopy, XPS, electrochemical AC impedance and the like, and the electrode materials obtained in examples 1 to 10 were subjected to specific capacitance and capacitance retention rate, and the test results are shown in FIGS. 1 to 5 and tables 1 to 2.

As shown in fig. 1, the sem images of the materials obtained in examples 1-3 and 6 show that pure polyaniline in example 6 forms a fiber form twisted, interpenetrating, or kink-crosslinked with each other after carbonization at 700 ℃. After KOH hole expanding activation, the activator is not penetrated into the pure polyaniline material, and the form of the carbonized polyaniline is not changed. In examples 1-3, the surface topography of the material was significantly changed after lignin incorporation, as can be seen in fig. 1 (c-h): the roasted products of SNC500, SNC700 and SNC900 have mesopores and micropores. At 700 ℃ carbonization in example 1, as shown in FIG. 1(e), the polymer is cracked to generate more pores of different sizes due to dehydration dehydrogenation and the aggravation of pore-enlarging effect of the activator. Macropores tend to form channels that are interconnected vertically or laterally (1(f) arrows), lignosulfonate functional groups generate more sulfur species and introduce more defects in the carbon backbone, and during activation these sulfur functional groups generate additional narrow micropores, resulting in a large increase in the ratio of micropores (< 2nm) to mesopores (2-50nm) (fig. 1(f) black box).

FIG. 2 is a transmission electron micrograph of the materials obtained in examples 1 to 3 and example 6 of the present application, and as can be seen from FIG. 2(a), the pure polyaniline in example 6 after carbonization was large-sized agglomerated particles having a diameter of about 150nm and a length of about 600nm, which is consistent with the SEM analysis result. Whereas in examples 1-3 the fibers become thinner after lignin incorporation, between 50-100nm in diameter, probably due to volume shrinkage caused by the thermal degradation of LS/PANI into carbon. Nanoparticles of about 30nm in diameter are uniformly dispersed in a layered carbon structure to form an interpenetrating network (fig. 2(e)), and as can be seen from fig. 2(e) and 2(f), the hexagonal torus of SNC700 carbon atoms forms a disordered, irregular lamellar structure with associated crystal defects, and fig. 2(f) shows ordered and disordered graphitic carbon, which can provide defects and active sites for the adsorption and intercalation of ions or electrons. In addition, the lattice defects are more numerous than in polyaniline carbon materials not doped with lignin. Fig. 2(b) shows the structure of pyrrole nitrogen, while fig. 2(f) shows that the pyrrole nitrogen content is further increased, which promotes the electrochemical performance of nitrogen-doped carbon. The comparison shows that when polyaniline is synthesized in the presence of lignin, similar nanorod aggregates are generated, but the circles with smaller lignin particles are embedded in the interpenetrating network, and the polyaniline nanoparticles have good dispersibility and compatibility due to more nucleation sites in the layered porous carbon. With the increase of the carbonization temperature, the morphology of the porous carbon is changed, and the stacking phenomenon of the SNC900 material is the most serious, probably because polyaniline is decomposed by heat, and a part of the polyaniline is collapsed and stacked disorderly.

TABLE 1 element content C, N, O, S and composition of different samples under XPS test

FIG. 3 shows XPS survey spectra and C1S, N1S, S2p fine spectra of the materials obtained in examples 1-3 of the present application, and FIG. 3(a) shows XPS survey spectra of SNC500, SNC700 and SNC900, which contains C, N, O and S elements, wherein S content is low and almost not recognized in the survey spectra, and the contents of the three elements in the carbon material are shown in Table 1.

Using Avantage software separately for C1 _S The fine spectrum is subjected to peak separation, as shown in FIG. 3 (b). The small peak at 284.09eV is assigned to sp ² The C-C, namely the graphite carbon, shows that graphite exists in the prepared material, and peaks of the graphite at 283.7, 285.06 and 287.51eV correspond to C-S, C ═ N, C ═ O respectively, which shows that strong interaction exists between carbon and nitrogen and sulfur dopants, and further shows that N, S and O elements are also doped into the crystal lattice of the carbon material. Wherein the peak area corresponding to C-S of SNC700 is the largest, and the S element in LS is the most embedded at the temperature.

The fine spectrum of XPS N1s shown in FIG. 3(c) clearly shows the effect of carbonization temperature on the bonding pattern of the nitrogen family. The fine structure spectrogram of the carbon material in the N1s can be divided into three types of nitrogen, the binding energy of the nitrogen is distributed in 398.63eV, 399.98eV and 401.48eV, and the nitrogen corresponds to pyridine nitrogen (N-6), pyrrole nitrogen (N-5) and graphite nitrogen (N-Q), wherein the nitrogen group improves the wettability and the conductivity of the electrode material, enhances ion transmission, and is beneficial to further improving the electrical activity specific surface area of the capacitor. Pyrrole/pyridine type nitrogen (N-5) and pyridine type nitrogen (N-6) can provide pseudo capacitance to the electrode material by the formulas (1) and (2).

As can be seen from table 1, each sample contained a certain amount of pyridine nitrogen, pyrrole nitrogen, and graphite nitrogen. With the increase of the carbonization temperature, the N content of the material is increased and then gradually reduced, possibly due to the decomposition caused by the instability of C-N under high temperature. The prepared SNC700 material contains more graphite nitrogen, and the content of pyridine nitrogen and pyrrole nitrogen is less than that of the other two materials. Graphite nitrogen can be used as an electron acceptor or used for attracting protons or electrons to improve the conductivity of the electrode carbon material and promote the redox reaction of nitrogen or adjacent functional groups, so that the performance of the supercapacitor is further improved, and the SNC700 conductivity is optimal.

In addition, from the fine spectrum of XPS S2p in FIG. 3(d), it can be seen that the presence of sulfur in the prepared carbon material is poor due to the low content of sulfur. Sulfur exists in two chemical forms in carbon materials, with the peak near 168.1eV corresponding to sulfur oxide (-C-SOx-C-) (x ═ 2, 3, 4), and the characteristic peaks at 163.5 and 164.5eV corresponding to thiophenic sulfur (C-S), the electronegativity of the carbon atom (2.55) and sulfur being very close, and the addition of sulfur to the carbon matrix results in the generation of defects, which contributes to the improvement of the electrochemical performance of the material. Doping with lignosulfonate effectively binds together sulfur with the carbon lattice, which serves as an active site for the redox reaction, but results in a significant reduction in the relative amount of sulfur due to severe heterocyclic ring cleavage of the molecule during pyrolysis.

For the XPS O1s spectra shown in FIG. 3(e), the samples all have three peaks in the BE values, corresponding to C ═ O (532.19eV), -CO (533.03eV) and-OH (535.49 eV). It can be seen that oxygen elements in the 3 kinds of SNC materials are mainly connected with carbon atoms, and oxygen-containing groups can improve the wettability of the surface of the carbon material and can also be connected with H in an acid solution ⁺ Reversible reaction occurs, and the effect of improving the electrochemical performance and capacitance value of the material is further achieved.

Electrochemical Impedance Spectroscopy (EIS) has been widely used to study the redox processes of electrode materials, the internal resistance of composite materials, charge transfer kinetics, and to evaluate their ionic and electronic conductivities during electrode/electrolyte interface diffusion. FIG. 4 is an electrochemical AC impedance spectrum of materials obtained in examples 1 to 3 and example 6 of the present application, and Nyquist plots of NC and SNC show a small approximate semicircle in a high frequency region and then transition to linearity in a low frequency region, which is a typical feature of a carbon material. In addition, the value of the diameter of the half circle on the real axis is approximately equal to the charge transfer resistance in the nyquist plot, comparing examples 1-3 and example 6, the intersection point of the resulting SNC700 of example 1 with the x axis is smallest. The results show that SNC700 has very good electron transport and low impedance compared to other electrode materials.

FIG. 5 shows specific capacitance and capacitance retention after 5000 cycles of the material obtained in example 1 of the present application. The stability and cycle life of the electrode material are also major factors in evaluating the material. As shown in fig. 5, the SNC700 electrode showed good cycling stability under high current density conditions by being within the potential window of-1-0V. When the charge-discharge current density is 5A/g, after 5000 cycles of charge-discharge, the capacity of the carbon material is about 95.14% of the initial capacity, and the effectiveness of heteroatom doping is proved, so that the carbon material provides potential practical application value in a super capacitor.

Table 2 shows the results of the specific capacitance and the capacitance retention rate tests of the electrode materials obtained in examples 1 to 9. Compared with example 6, the specific capacitance of the electrode materials obtained in comparative examples 1-5 is obviously improved, which shows that doping lignin is beneficial to improving the specific capacitance and the cycling stability of the electrode materials. Example 7 uses alkali lignin without S element, and the obtained material has lower specific capacitance than the electrode material obtained in example 1, and also has poor cycle stability. The specific capacitance of the material obtained in example 8 is lower than that of example 1, which shows that the structure of the precursor can be better maintained under freeze drying, the pore diameter and the specific surface area are larger, and the effect of freeze drying the lignin/polyaniline precursor is better than that of vacuum drying at a certain temperature. Compared with example 9, the specific capacitance and the capacitance retention rate of example 1 are both higher, which indicates that the kind of the doping acid also has a larger influence on the performance of the electrode material, and the hydrochloric acid has a better effect as the dispersion liquid of aniline and sodium lignosulfonate in the preparation process of the lignin/polyaniline precursor.

TABLE 2 sample specific capacitance and capacitance Retention Rate test

The above detailed description is only for explaining the present application and not for limiting the present application, and those skilled in the art can make modifications to the present embodiment without inventive contribution as required after reading the present specification, but all of them are protected by patent laws within the scope of the claims of the present application.

Claims

1. A preparation method of a multi-atom doped lignin carbon-based electrode material is characterized by comprising the following steps: the method comprises the following steps:

2. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the pre-carbonization process in S2 specifically comprises the following steps: and (3) putting the lignin/polyaniline precursor dried to constant weight into a tubular furnace, carbonizing at 380-450 ℃ for 1-2h, and grinding to obtain a powder sample.

3. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the activation process in S2 specifically includes the following steps: dissolving an activating agent in deionized water, adding the powder sample, stirring, mixing and drying; then placing the mixture in a tube furnace to obtain N ₂ Heating to 500-900 ℃ at the heating rate of 5 ℃/min in the atmosphere, and keeping the temperature for 2 h; and cooling to room temperature after heat preservation is finished, repeatedly washing to be neutral by using hydrochloric acid and distilled water, and drying to obtain the polyatomic-doped lignin carbon-based electrode material.

4. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 3, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the activating agent in S2 is KOH or NaOH, and the temperature rise temperature in the activating process is 700 ℃.

5. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the drying in S1 adopts freeze drying mode.

6. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the molar ratio of the aniline to the oxidant in S1 is (1-4): 1.

7. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the mass ratio of the aniline to the lignosulfonate in the S1 is 1 (2.5-6).

8. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the oxidant is ammonium persulfate.

9. The method for preparing the polyatomic-doped lignin carbon-based electrode material according to claim 1, wherein the polyatomic-doped lignin carbon-based electrode material comprises the following steps: the reaction temperature in S1 is 0-4 ℃, and the reaction time is 24 h.

10. A polyatomic doped lignin carbon-based electrode material obtainable by the method according to any one of claims 1 to 9.