CN111099574A

CN111099574A - Preparation method of hierarchical porous carbon aerogel for lithium ion battery cathode

Info

Publication number: CN111099574A
Application number: CN201911382346.1A
Authority: CN
Inventors: 郭兴忠; 梁浩; 王金田; 杨辉
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2019-12-27
Filing date: 2019-12-27
Publication date: 2020-05-05

Abstract

The invention discloses a method for preparing a hierarchical porous carbon aerogel used for a negative electrode of a lithium ion battery, comprising the following steps: dissolving resorcinol in a dilute hydrochloric acid solution to obtain a resorcinol solution; Adding (or not adding) a pore-forming agent to the phenol solution, adding a formaldehyde solution and uniformly mixing to obtain a resorcinol-formaldehyde solution; after sealing the resorcinol-formaldehyde solution, the gel is aged; the obtained resorcinol-formaldehyde solution The formaldehyde organic wet gel is subjected to solvent replacement and drying; under the protection of an inert gas, the obtained organic aerogel is carbonized to obtain a hierarchical porous carbon aerogel. The carbon aerogel is used as a negative electrode material for lithium ion batteries, and is expected to improve various properties of carbon negative electrode materials for lithium ion batteries.

Description

Preparation method of hierarchical porous carbon aerogel for lithium ion battery cathode

Technical Field

The invention relates to the field of lithium ion battery cathode materials, in particular to a preparation method of a hierarchical porous structure carbon aerogel as a lithium ion battery cathode material.

Background

With the continuous development of modern society, the excessive consumption of fossil energy and the serious environmental pollution caused by the accelerated consumption of fossil energy are more and more emphasized by people, so that the development and utilization of cleaner and greener energy sources such as wind energy, solar energy, biological energy and the like are urgently needed, and meanwhile, battery storage equipment with excellent cycle performance and large capacity is also needed to convert and store the energy sources. In addition, the electric vehicle needs a battery with good enough cycle performance and high enough energy density to provide power; the continuous upgrade of mobile electronic devices also places higher demands on the performance of batteries. Since the commercialization of lithium ion batteries as new high-efficiency energy storage devices, power foundations have been provided for many electronic devices such as smart phones and notebook computers, but development bottlenecks are gradually emerging, and how to further improve specific capacity, improve cycle stability, prolong service life, improve safety performance and reduce cost becomes a current major concern.

The capacity of a lithium ion battery is mainly limited by its positive and negative electrode materials. The cathode industrialized material mainly comprises graphite carbon materials, and the materials have good conductivity, good cycling stability and low cost, so the materials always occupy the leading position of the commercialized cathode materials. However, the theoretical specific capacity of the graphite material is lower (374 mAh.g)^-1) And because the redox potential of the de-intercalated lithium is low, lithium precipitation is easy to occur on the surface in the charging and discharging process, lithium dendrite is generated, the cycle stability is influenced, and even a diaphragm can be penetrated to cause short circuit, so that the safety performance of the battery is greatly reduced. Therefore, the development of a novel lithium ion battery cathode material with high energy density and high power density is a hot spot of current research.

Research indicates that the synergistic effect of different pore diameters and different particle sizes of the porous carbon material with the hierarchical pore diameter structure is beneficial to improving the lithium storage performance of the active electrode. During charging and discharging of the battery, Li⁺The graphite microcrystalline region of porous carbon can be embedded and then stored in abundant micropores, and the small-size micropores can effectively increase the contact area of an active substance and electrolyte and increase lithium storage active sites; the mesopores can be used as Li⁺The transmission channel of (2) can also promote the permeation of the electrolyte; the presence of the macroporous structure greatly mitigates the effect of volume expansion during cycling. Therefore, compared with the graphite-based material,the porous carbon has better application prospect.

The carbon aerogel material is an amorphous porous carbon material containing rich microporous structures, has high porosity and large specific surface area, and is widely researched and applied in the fields of supercapacitors, electric adsorption, fuel cells and the like. The preparation of the carbon aerogel generally comprises the steps of condensing resorcinol and formaldehyde serving as precursors into organic wet gel under the action of alkalescent catalysts such as sodium carbonate and the like, and then aging, drying, carbonizing and the like to prepare the carbon aerogel. Under the alkalescent catalysis condition, the organic condensation reaction rate is low, the strength of the obtained organogel framework is not high, and the obtained organogel framework is easy to have obvious volume shrinkage in the subsequent drying and carbonization processes, so that the density and hardness of the carbon aerogel material are high, the application is difficult, the pore diameter of the carbon aerogel material is mainly micropores and mesopores (the micropore size is less than 1nm, and the mesopore diameter is 2-50 nm) with small sizes, although the carbon aerogel material has a high specific surface, the utilization rate is not high, and the application of the carbon aerogel material in the aspect of lithium ion battery cathodes is greatly limited. Resorcinol: when the molar ratio of formaldehyde is 1:2, the specific capacity of the lithium ion battery prepared from the carbon aerogel prepared by using a weakly alkaline catalyst such as sodium carbonate is about 120mAh/g under the condition of 0.2C constant current charge and discharge, and the specific capacity of the lithium ion battery is attenuated after about 50 cycles. In the process of drying the organogel, in order to reduce the influence of surface tension, a supercritical drying or freeze drying technology is mostly used, the process is complex, and the cost is high; if the method adopts normal pressure drying, the shrinkage generated in the carbonization process is more serious, and finally the prepared carbon aerogel has high density and large volume density, and a large amount of pore structures disappear, thereby losing application value.

Disclosure of Invention

The invention mainly solves the technical problem of providing a preparation method of hierarchical porous carbon aerogel for a lithium ion battery cathode, which can improve the cycling stability of a porous carbon material cathode in the charging and discharging processes, improve the safety performance and simultaneously have higher specific capacity.

In order to solve the technical problem, the invention provides a preparation method of a hierarchical porous carbon aerogel for a lithium ion battery cathode, which comprises the following steps:

1) dissolving resorcinol in a dilute hydrochloric acid solution to obtain a resorcinol solution;

the dilute hydrochloric acid solution is obtained by mixing a hydrochloric acid solution with the concentration of 0.1M and deionized water according to the volume ratio of 1: 6-30 (preferably 1: 13-15);

generally, every 2.75g of resorcinol is mixed with 7-9 mL of dilute hydrochloric acid solution;

2) and preparing the resorcinol-formaldehyde solution by any one of the following methods:

the method A comprises the following steps: adding a pore-forming agent into the resorcinol solution, stirring until the pore-forming agent is dissolved, then adding a formaldehyde solution, and uniformly mixing (stirring for about 30min) to obtain a resorcinol-formaldehyde solution; pore-forming agent: resorcinol in a mass ratio of 0.001 to 3:11 (preferably 0.7 to 1: 11);

the method B comprises the following steps: directly adding a formaldehyde solution into the resorcinol solution, and uniformly mixing (stirring for about 30min) to obtain a resorcinol-formaldehyde solution;

resorcinol: formaldehyde in a molar ratio of 1: 2;

3) sealing the resorcinol-formaldehyde solution, and aging the solution for 24-30 h at the temperature of (60 +/-10) DEG C to obtain resorcinol-formaldehyde organic wet gel;

4) carrying out solvent replacement on the resorcinol-formaldehyde organic wet gel, and drying to obtain an organic aerogel;

5) and under the protection of inert gas (high-purity argon), carbonizing the organic aerogel at 900-1000 ℃ for 1 +/-0.2 h to obtain the hierarchical porous carbon aerogel (a carbon aerogel block with a hierarchical porous structure).

The carbonization may be carried out in a tube furnace.

The improvement of the preparation method of the hierarchical porous carbon aerogel for the lithium ion battery cathode is as follows: the pore-forming agent in the step 2) is polyoxyethylene, and the molecular weight of the polyoxyethylene is 800, 2000, 10000 and 20000.

The preparation method of the hierarchical porous carbon aerogel for the lithium ion battery cathode is further improved as follows: in the method A of the step 2), the pore-forming agent is added into the resorcinol solution and stirred for 2 +/-0.5 hours at the constant temperature of 55 +/-10 ℃, so that the pore-forming agent is dissolved.

The preparation method of the hierarchical porous carbon aerogel for the lithium ion battery cathode is further improved as follows: in the step 2), the mass concentration of the formaldehyde solution is 37 wt%.

The preparation method of the hierarchical porous carbon aerogel for the lithium ion battery cathode is further improved as follows: in the step 4), the resorcinol-formaldehyde organic wet gel is subjected to solvent replacement for 24-48 h by using absolute ethyl alcohol, and then is dried for 2d at the temperature of (45 +/-5) in an open manner to obtain the organic aerogel.

The preparation method of the hierarchical porous carbon aerogel for the lithium ion battery cathode is further improved as follows: in the step 5), the temperature is increased to 900-1000 ℃ at the speed of 1 ℃/min for carbonization.

The invention has the following technical advantages:

1) the invention uses dilute hydrochloric acid to catalyze the condensation process of resorcinol and formaldehyde, adds polyoxyethylene as a pore-forming agent to regulate the pore structure, introduces mesoporous and macroporous apertures into the microporous rich carbon aerogel material, forms the characteristic structure of hierarchical porous, has wide aperture distribution, and can be regulated and controlled within a certain range. The carbon aerogel material prepared by the invention has a hierarchical porous structure. Spherical particles with the particle size of 3-8 mu m are connected into a chain to form a macroporous framework, the spherical particles are formed by stacking small-size carbon particles (20-40 nm), abundant micropores and mesoporous structures exist on the framework, the pore diameter of the micropores is less than 1nm, the pore diameter of the mesopores is 2-50 nm, the pore diameter of the macropores is 500-10 mu m, and the specific surface area is 400-1000 m²/g。

2) The carbon aerogel material prepared by the invention has a hierarchical porous structure, and can be used for preparing a negative electrode of a lithium ion battery to perform constant current charge and discharge tests, and the synergistic effect of different pore diameters and different particle diameters can improve the lithium storage performance of an active electrode. During charging and discharging, Li⁺The graphite microcrystalline region capable of being embedded into the carbon aerogel is stored in the micropores, so that the contact area of the active substance and the electrolyte can be effectively increased, and the lithium storage active sites can be increased; the mesopores can be used as Li < + > transmission channels and can also promotePenetration of the electrolyte; the presence of the macroporous structure greatly mitigates the effect of volume expansion during cycling.

Namely, the invention not only can improve the cycling stability of the porous carbon material negative electrode in the charging and discharging process and improve the safety performance, but also has higher specific capacity.

3) The method realizes simple preparation of the carbon aerogel material by means of normal pressure drying, simplifies the process flow and greatly reduces the cost and energy consumption compared with supercritical drying and freeze drying. The prepared carbon aerogel block material can keep the integral shape and the skeleton structure of the organogel, is kept complete in the drying and carbonizing processes, and does not break or crack.

In conclusion, the invention can introduce abundant mesopore and macropore diameters into the carbon aerogel under the normal pressure drying condition by regulating the type and proportion of the catalyst in the preparation process of the carbon aerogel and simultaneously introducing the additive for pore forming, thereby forming a characteristic structure of hierarchical porous, and the invention has wide density variation range and adjustable pore diameter distribution in a certain range. And the carbon aerogel has the advantages of simple preparation process, convenient synthesis, short period, low cost and integration of the above advantages, and the carbon aerogel material with the hierarchical pore size is expected to be widely applied to the field of lithium ion battery cathode materials. Namely, the carbon aerogel with the hierarchical porous structure is prepared and used as the lithium ion battery cathode material, and various performances of the lithium ion battery carbon cathode material are hopefully improved.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 is a macroporous framework SEM photograph of the carbon aerogel prepared in example 1;

FIG. 2 is an SEM photograph of spherical particles on the carbon aerogel skeleton prepared in example 1;

FIG. 3 is a graph of the cycle performance of the lithium ion battery prepared in example 1;

FIG. 4 is an SEM photograph of the carbon aerogel material prepared in example 2;

FIG. 5 is an SEM photograph of the carbon aerogel material prepared in comparative example 1;

FIG. 6 is an SEM photograph of the carbon aerogel material prepared in comparative example 2-1;

FIG. 7 is an SEM photograph of the carbon aerogel material prepared in comparative example 2-2;

FIG. 8 is an SEM photograph of the carbon aerogel material prepared in comparative example 3;

fig. 9 is an SEM photograph of the carbon aerogel material prepared in comparative example 4.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

example 1, a method for preparing a carbon aerogel having a hierarchical porous structure that can be used as a negative electrode material of a lithium ion battery (in this case, no pore-forming agent is added), includes the following steps:

1) weighing 2.75g of resorcinol, adding the resorcinol into 7.05mL of deionized water, adding 0.5mL of 0.1M HCl solution, and magnetically stirring for 1h at the constant temperature of 55 ℃ until the resorcinol is fully dissolved to obtain resorcinol solution;

2) according to the formula of resorcinol: adding a formaldehyde solution with the mass fraction of 37 wt% into the resorcinol solution obtained in the step 1) according to the molar ratio of formaldehyde to be 1:2, and magnetically stirring for 30min at the constant temperature of 55 ℃; obtaining resorcinol-formaldehyde solution (which is uniform mixed solution);

3) sealing the resorcinol-formaldehyde solution, and placing the sealed resorcinol-formaldehyde solution into a 60 ℃ forced air drying oven for gel aging for 24 hours to obtain resorcinol-formaldehyde organic wet gel;

in the step, the time required for gelling is about 30-45 minutes;

4) and (3) firstly carrying out solvent replacement on the resorcinol-formaldehyde organic wet gel obtained in the step 3) by using absolute ethyl alcohol for 24 hours, and then placing the gel in a 45 ℃ forced air drying oven for drying for 2 days under normal pressure to obtain the organic aerogel.

The resorcinol-formaldehyde organic wet gel must be immersed in anhydrous ethanol all the time during the above solvent replacement.

5) And using high-purity argon as a protective gas, heating the organic aerogel obtained in the step 4) to 900 ℃ at the speed of 1 ℃/min, then carrying out heat preservation and carbonization for 1h, and cooling along with the furnace to obtain the block-shaped carbon aerogel with the hierarchical porous structure.

The carbon aerogel has a hierarchical porous characteristic structure, and the block density is less than 200cm³Per g, BET specific surface area of about 500m²The mesoporous silicon material has rich micropores, wherein the pore diameter of a mesopore is 2-30 nm, the pore diameter of a macropore is mainly about 6 mu m, and a small amount of the macropore is 2-3 mu m.

The SEM photograph of the macroporous skeleton of the carbon aerogel is shown in FIG. 1, and the SEM photograph of the spherical particles on the carbon aerogel skeleton is shown in FIG. 2.

Experiment 1,

1) And preparing the lithium ion battery cathode with the carbon aerogel component:

grinding the carbon aerogel blocks with the hierarchical porous structure into powder (sieving the powder by a sieve with 400 meshes), and uniformly mixing the carbon aerogel powder, carbon black serving as a conductive agent and sodium carboxymethylcellulose (CMC) aqueous solution serving as an adhesive to form slurry; the mass concentration of the CMC aqueous solution is 5 wt%, and the mass ratio of the carbon aerogel powder, the carbon black and the CMC is 8:1: 1; magnetically stirring the slurry for 12h, uniformly coating the slurry on a copper foil with the thickness of 90 μm, and drying the copper foil in a vacuum oven at the constant temperature of 60 ℃ for 8h (after drying, the thickness of the slurry layer is 100 μm); and then, cutting the copper foil coated with the slurry into a circular sheet with the diameter of 14mm by using a slicing machine to finally obtain the lithium ion battery cathode of the hierarchical porous structure carbon aerogel component, and placing the lithium ion battery cathode in a vacuum glove box for later use.

2) Assembling the lithium ion battery:

assembling in a vacuum glove box; firstly, placing a metal lithium sheet in a negative electrode shell, dripping 25 mu L of electrolyte, covering the negative electrode shell with a diaphragm, dripping 25 mu L of electrolyte, placing a copper foil (namely, the lithium ion battery negative electrode with the hierarchical porous structure carbon aerogel component obtained in the step 1), contacting the side coated with an active substance (namely, a slurry layer on the copper foil) with the electrolyte, finally placing a gasket and an elastic sheet, covering the positive electrode shell, sealing the positive electrode shell by using a sealing machine, and standing for 12 hours; and carrying out cycle performance test after the electrolyte is fully contacted with the active electrode.

The lithium ion battery prepared from the carbon aerogel in example 1 has a first-cycle specific capacity of 625mAh/g and a specific capacity of 170mAh/g under a 0.2C constant-current charging and discharging condition, and can still be stable after 400 cycles (the specific capacity is basically kept unchanged). As shown in fig. 3.

Embodiment 2, a method for preparing a carbon aerogel with a hierarchical porous structure as a negative electrode material of a lithium ion battery, comprising the following steps:

1) same as in step 1) of example 1;

2) adding 0.2g of polyoxyethylene (Mn ═ 2000) serving as a pore-forming agent into the resorcinol solution obtained in the step 1), and magnetically stirring for 2 hours at the constant temperature of 55 ℃ until the polyoxyethylene is completely dissolved;

then, according to the ratio of resorcinol: adding a formaldehyde solution with the mass fraction of 37 wt% into the solution at the molar ratio of 1:2, and magnetically stirring the mixture for 30min at the constant temperature of 55 ℃; obtaining resorcinol-formaldehyde solution (which is uniform mixed solution);

3) sealing the resorcinol-formaldehyde solution, and placing the sealed resorcinol-formaldehyde solution into a 60 ℃ forced air drying oven for gel aging for 30 hours to obtain resorcinol-formaldehyde organic wet gel;

in the step 3), the time required for gelling is about 30-45 minutes;

4) and (3) firstly carrying out solvent replacement on the resorcinol-formaldehyde organic wet gel obtained in the step 3) by using absolute ethyl alcohol, wherein the replacement time is 24h each time, carrying out replacement for 2 times (updating the absolute ethyl alcohol during replacement each time), and then, opening the room and placing the room in a 45 ℃ forced air drying oven for drying for 2 days under normal pressure to obtain the organic aerogel.

5) The same procedure as in step 5) of example 1.

SEM photograph of the prepared carbon aerogel (block shape) is shown in FIG. 4, and the carbon aerogel has a hierarchical porous characteristic structure, and the block density is less than 200cm³Per g, BET specific surface area of about 450m²The mesoporous silicon material has rich micropores, wherein the pore diameter of a mesopore is 10-30 nm, and the pore diameter of a macropore is mainly about 10 mu m. The prepared carbon aerogel material had a larger pore size compared to example 1.

The carbon aerogel prepared in example 2 was tested according to the method described in experiment 1, and the results were: under the condition of 0.2C constant current charge and discharge, the specific capacity of the first loop is 500mAh/g, the specific capacity is 150mAh/g, and the first loop can still keep stable after 1000 cycles. Therefore, although the specific capacity is slightly lower than that of example 1, the cycle stability performance is significantly better than that of example 1.

Comparative example 1, the "0.1M HCl solution 0.5mL, deionized water 7.05 mL" in step 1) of example 1 was changed to "0.1M HCl solution 2mL, deionized water 5.55 mL", and the rest was identical to example 1.

In the step 3), after the formaldehyde solution is added, the mixed solution releases heat obviously, the gelling time is short (about 2-3 minutes), the hardness of the organic gel is high, and the organic gel shrinks remarkably after being carbonized. The microstructure is shown in FIG. 5.

In fig. 5, carbon particles are tightly packed and micropores are rich, but the prepared carbon aerogel block has high density, no large-size pores, high hardness and high grinding difficulty, and the negative electrode material prepared by the method in experiment 1 has high surface roughness and poor uniformity after being coated and dried on copper foil.

The carbon aerogel prepared in comparative example 1 was tested according to the method described in experiment 1, and the results were: the specific capacity is lower in the charge and discharge test of the lithium ion battery, the cycle performance is poor, the capacity is continuously attenuated to a small extent along with the increase of the cycle times, and after about 400 cycles, the specific capacity is attenuated to 50mAh/g from 75 mAh/g.

Comparative example 2-1, the molecular weight of polyethylene oxide in step 2) of example 2 was changed from "Mn 2000" to "Mn 800", and the rest was identical to example 2.

The microstructure of the prepared carbon aerogel material is shown in figure 6. In FIG. 6, the particle size is not uniform, the concentrated pore size distribution is not generated, and the controllability of the whole microstructure is poor.

The carbon aerogel prepared in comparative example 2-1 was tested according to the method described in experiment 1, and the results were: in the initial 50 times of circulation, the specific capacity floats between 100 and 120mAh/g, the specific capacity is continuously reduced in subsequent tests, and the circulation stability is poor.

Comparative example 2-2, the molecular weight of the polyethylene oxide in step 2) of example 2 was changed from "Mn 2000" to "Mn 20000", and the rest was identical to example 2.

The microstructure of the prepared carbon aerogel material is shown in figure 7. In FIG. 7, the particle size distribution is not uniform, the particle size difference is significant, both large diameter (> 10 μm) carbon sphere particles and small diameter (< 100nm) particles exist, and the controllability of the whole microstructure is poor.

The carbon aerogel prepared in comparative examples 2-2 was tested according to the method described in experiment 1, and the results were: in the initial 50 times of circulation, the specific capacity has no stable value, floats between 50 and 80mAh/g, is continuously reduced in the subsequent test, and has poor circulation stability.

Comparative example 3, the amount of polyethylene oxide (Mn ═ 2000) used in step 2) of example 2 was changed from "0.2 g" to "1.0 g", and the rest was the same as in example 2.

In the step 2), a uniform solution can be formed after adding formaldehyde, but dark red hard precipitate is slowly formed at the bottom in the gelling process, so that the gel is obviously layered, the organic gel has non-uniform color, and the organic gel is easy to crack after carbonization. The microstructure of the prepared carbon aerogel material is shown in figure 8.

In fig. 8, the uniformity of particle size is poor, the large pores formed by the framework are filled and blocked by a large number of small particles, the structure controllability is poor, and the porosity is not high. Therefore, it cannot be used for preparing a lithium ion battery anode.

Comparative example 4, the "open air at 45 ℃ in the forced air drying oven at atmospheric pressure 2 d" in step 4) of example 2 was changed to "use CO" as described in the conventional technique₂Supercritical drying ", the rest is equivalent to example 2.

The microstructure of the prepared carbon aerogel material is shown in figure 9. The results show that under the conditions of using dilute hydrochloric acid as a catalyst and adding polyoxyethylene as a pore-forming agent, the finally prepared carbon aerogel is prepared by the processes of drying at normal pressure and the like and using CO₂The micro-morphology prepared by supercritical drying is basically consistent, and the pore structure is not obviously different. The carbon aerogel material prepared by supercritical drying also has a hierarchical porous characteristic structure, and the block density is less than 200cm³Per g, BET specific surface area of about 520m²A little above atmospheric drying.

The carbon aerogel block prepared in comparative example 4 was tested according to the method described in experiment 1, and the results were: the specific capacity is basically the same as that of the embodiment 2, is about 170mAh/g, and can still keep stable after 400 cycles.

Finally, it is also noted that the above-mentioned lists merely illustrate a few specific embodiments of the invention. It is obvious that the invention is not limited to the above embodiments, but that many variations are possible. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.

Claims

1. The preparation method of the hierarchical porous carbon aerogel for the negative electrode of the lithium ion battery is characterized by comprising the following steps of:

the dilute hydrochloric acid solution is obtained by mixing a hydrochloric acid solution with the concentration of 0.1M and deionized water according to the volume ratio of 1: 6-30;

the method A comprises the following steps: adding a pore-forming agent into the resorcinol solution, stirring until the pore-forming agent is dissolved, and then adding a formaldehyde solution for uniform mixing to obtain a resorcinol-formaldehyde solution; pore-forming agent: resorcinol in a mass ratio of 0.001-3: 11;

the method B comprises the following steps: directly adding a formaldehyde solution into the resorcinol solution, and uniformly mixing to obtain a resorcinol-formaldehyde solution;

resorcinol: formaldehyde in a molar ratio of 1: 2;

5) and under the protection of inert gas, carbonizing the organic aerogel at 900-1000 ℃ for 1 +/-0.2 h to obtain the hierarchical porous carbon aerogel.

2. The method of preparing a hierarchical porous carbon aerogel for a lithium ion battery negative electrode according to claim 1, wherein: the pore-forming agent in the step 2) is polyoxyethylene, and the molecular weight of the polyoxyethylene is 800, 2000, 10000 and 20000.

3. The method of preparing a hierarchical porous carbon aerogel for a lithium ion battery negative electrode according to claim 2, wherein: in the method A of the step 2), the pore-forming agent is added into the resorcinol solution and stirred for 2 +/-0.5 hours at the constant temperature of 55 +/-10 ℃, so that the pore-forming agent is dissolved.

4. The preparation method of the hierarchical porous carbon aerogel for the negative electrode of the lithium ion battery according to any one of claims 1 to 3, characterized by comprising the following steps: in the step 2), the mass concentration of the formaldehyde solution is 37 wt%.

5. The preparation method of the hierarchical porous carbon aerogel for the negative electrode of the lithium ion battery according to any one of claims 1 to 3, characterized by comprising the following steps: in the step 4), the resorcinol-formaldehyde organic wet gel is subjected to solvent replacement for 24-48 h by using absolute ethyl alcohol, and then is dried for 2d at the temperature of (45 +/-5) in an open manner to obtain the organic aerogel.

6. The preparation method of the hierarchical porous carbon aerogel for the negative electrode of the lithium ion battery according to any one of claims 1 to 3, characterized by comprising the following steps: in the step 5), the temperature is increased to 900-1000 ℃ at the speed of 1 ℃/min for carbonization.