CN112234206B

CN112234206B - Method for preparing thin-layer graphene/transition metal fluoride composite positive active material by using antibiotic fungi residues

Info

Publication number: CN112234206B
Application number: CN202011118650.8A
Authority: CN
Inventors: 杨娟; 丁静; 唐晶晶; 周向阳; 刘晓剑; 王炯
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2022-03-29
Anticipated expiration: 2040-10-19
Also published as: CN112234206A

Abstract

The invention belongs to the technical field of fungus dreg solid waste treatment and battery materials, and particularly relates to a method for preparing a thin-layer graphene/transition metal fluoride composite positive electrode active material by using antibiotic fungus dregs, which comprises the following steps: carrying out hydrothermal liquefaction on an aqueous solution containing antibiotic bacteria residues and alkali, and then carrying out solid-liquid separation to obtain a bacteria residue solution; adding a transition metal M source into the fungus dreg solution, mixing liquid phases, performing dehydration treatment, and then performing heat treatment; the heat treatment comprises a first section of pretreatment and a second section of heat treatment which are sequentially carried out; and (3) carrying out fluorination and annealing treatment on the product obtained by the heat treatment and a fluorine source to obtain the thin-layer graphene/M metal fluoride composite positive electrode active material. The invention also provides the material prepared by the preparation method and application thereof in lithium batteries. The technical scheme of the invention can realize double synergy of chemical and physical structures, and is favorable for remarkably improving the performance of the material in the aspect of electrochemistry.

Description

Method for preparing thin-layer graphene/transition metal fluoride composite positive active material by using antibiotic fungi residues

Technical Field

The invention belongs to the technical field of lithium ion battery electrode materials, and particularly relates to a method for preparing a thin-layer graphene/transition metal fluoride composite anode from antibiotic fungi residues.

Background

Lithium ion batteries are widely used in the fields of portable electronic devices, new energy vehicles, energy storage power systems and the like due to the advantages of high working voltage, no memory effect, high energy density, low self-discharge rate and the like. With the development of new energy technologies such as electric vehicles and the like, the traditional lithium ion battery anode materials, such as lithium cobaltate, lithium iron phosphate, ternary materials and the like, are subject to a lithium de-intercalation mechanism, and the specific capacity of the traditional lithium ion battery anode materials is difficult to meet the requirements of the next generation of high energy density lithium ion batteries. Therefore, the development of alternative high capacity cathode materials has been a research hotspot in the field.

Transition metal fluoride such as ferric fluoride is used as a novel anode material based on two reaction mechanisms of intercalation-deintercalation reaction and chemical conversion reaction, and is considered to be a lithium ion battery anode material with great development prospect due to the advantages of high specific capacity, low cost, environmental friendliness and the like. However, the iron fluoride has problems of low conductivity, poor cycle stability, etc. due to the strong ionic bond characteristic between Fe and F and the wide energy band gap, which seriously hinders the practical application thereof. Therefore, the first problem of solving the ferric fluoride is to improve its conductivity. Modification by complexing with highly electron conductive carbon materials is the most common method. If graphene, carbon nano tubes, graphite and ferric fluoride are compounded, the conductivity of the ferric fluoride can be effectively improved, and the circulation stability is improved. However, graphene and carbon nanotubes are expensive, and the process of compounding graphene and carbon nanotubes with iron fluoride is not easy to control, resulting in uneven dispersion, which is not beneficial to the practical application of iron fluoride, so that a conductive agent with high conductivity, simple preparation process and low cost is sought, and the enhancement of the bonding strength between iron fluoride and the conductive agent is particularly important for the practical application of iron fluoride.

In addition, the antibiotic dregs are a waste material produced along with the production of antibiotics, and comprise terramycin dregs, penicillin dregs, cephalosporin dregs and the like, the main components of the antibiotic dregs are crude protein, crude fiber, crude fat, amino acid and the like, and the antibiotic dregs contain a large amount of carbon, nitrogen, oxygen and sulfur elements and a small amount of metal elements, such as iron, calcium, zinc, magnesium and the like. China is a large antibiotic producing country, and a large amount of fungus dreg waste materials are produced every year. In order to prevent the accumulation of the waste material in a large amount, the waste material is mainly treated by incineration and burial, which causes environmental pollution and waste of resources. Although people have been concerned about the disposal of the mushroom dregs with the enhancement of environmental awareness, a few technical means are available to convert the mushroom dregs into materials such as biochar and the like, and the technologies can achieve a certain solid waste disposal effect, but cannot effectively realize the high-value utilization of solid waste. Therefore, how to effectively and reasonably treat the mushroom dreg waste materials becomes a problem to be solved urgently at present.

Disclosure of Invention

The invention aims to solve the problems of low conductivity and poor cycle stability of transition metal fluoride, adopts antibiotic fungi residues as raw materials, realizes low-cost harmless and high-value utilization, and provides a method for preparing a thin-layer graphene/transition metal fluoride positive active material (also called a thin-layer graphene/transition metal fluoride composite positive electrode or a positive material for short) by using the antibiotic fungi residues.

The second purpose of the invention is to provide a thin-layer graphene/transition metal fluoride positive electrode active material prepared by the method.

The third purpose of the invention is to provide an application of the thin-layer graphene/transition metal fluoride positive electrode active material prepared by the method in a lithium battery.

The fourth object of the present invention is to provide a lithium ion battery comprising the thin-layer graphene/transition metal fluoride cathode active material.

The antibiotic fungi residues are the residual waste residues after microbial fermentation pharmacy and filtration extraction of fermentation filtrate, and are mainly divided into terramycin fungi residues, penicillin fungi residues, cephalosporin fungi residues and the like. The main components of the antibiotic fungi residues are mycelium, intermediate metabolites in the fermentation process, residual culture medium, degradation products of the culture medium, growth factors with unknown components, acidifier, flocculant, filter aid, protein precipitator and a very small amount of residual solution, and the antibiotic fungi residues are rich in a large amount of elements such as carbon, nitrogen, sulfur, metal and the like. Antibiotic fungi residues belong to dangerous solid wastes, and the environment is greatly influenced by improper treatment. However, the main idea for treating antibiotic fungi residues is to bury the residues in a pile or to use the residues as a carbon source to prepare an adsorbing material such as biochar. Although the existing means can achieve a certain treatment effect of antibiotic residues, the utilization value of the co-produced biochar material needs to be improved.

In the prior art, no technical report that the mushroom dregs are used for the thin-layer graphene/metal fluoride cathode material exists. However, the difficulty of achieving the technical goal and filling the technical gap is huge, and the main obstacles are that: (1) the components of the antibiotic fungi residues are complex, and a large number of factors which are unfavorable to the electrochemical performance are not lacked, so that the selective utilization of the electrochemical beneficial components is realized, and the synchronous utilization of the unfavorable factors is avoided; (2) how to realize the in-situ uniform compounding of the metal fluoride, avoid agglomeration, control the grain size and avoid peeling. Therefore, in order to successfully realize the preparation of the cathode material with excellent electrochemical performance by the mushroom dregs, the component selectivity of the antibiotic mushroom dregs needs to be properly treated, adverse factors are selectively eliminated as much as possible on the premise of selectively and efficiently utilizing the chemical modification and the structure control of the electrical beneficial components in the mushroom dregs, and how to realize the uniform in-situ compounding of the metal fluoride and control the grain size; therefore, the inventor of the invention has conducted extensive research and provides the following technical scheme, specifically:

a method for preparing a thin-layer graphene/transition metal fluoride composite positive active material by using antibiotic fungi residues comprises the following steps:

step (1): hydrothermal liquefaction

Carrying out hydrothermal liquefaction on an aqueous solution containing antibiotic bacteria residues and alkali, and then carrying out solid-liquid separation to obtain a bacteria residue solution;

step (2): thermal treatment

Adding a transition metal M source into the fungus dreg solution, mixing, dehydrating, and then performing heat treatment; the heat treatment comprises a first section of pretreatment and a second section of heat treatment which are sequentially carried out; wherein the temperature of the first stage heat treatment is 400-600 ℃; the temperature of the second-stage heat treatment is 700-900 ℃; and the heating rate in the heat treatment process is 2-10 ℃/min;

and (3): in situ fluorination

And (3) carrying out fluorination and annealing treatment on the product obtained by the heat treatment in the step (2) and a fluorine source to obtain the thin-layer graphene/M metal fluoride composite positive electrode active material.

The invention provides a technical idea for preparing a thin-layer graphene/metal fluoride active material by using antibiotic fungi residues for the first time. In order to realize the technical idea of the invention and improve the electrochemical performance of the prepared material, the invention innovatively discovers that the hydrothermal liquefaction means under the assistance of alkali is matched with the liquid phase action of the bacteria liquid-transition metal and the subsequent two-stage heat treatment means under the combined assistance of an alkali-transition metal source, so that the electrically beneficial components of the antibiotic bacteria residues can be unexpectedly and selectively utilized to carry out chemical hybridization modification on the material, the synchronous hybridization of electrochemical harmful components is reduced, and the morphology of the material can be regulated and controlled, thereby being beneficial to obtaining the graphene material which has good doping property, high crystallinity, thin-layer structure and in-situ embedded metal simple substances; further, by matching with the fluorination and degradation processes, in-situ fluorination of a transition metal simple substance in the graphene structure can be realized, so that in-situ mosaic of metal fluoride is realized, agglomeration is avoided, and the conductivity of the material is improved.

The research of the invention also finds that based on the preparation method and based on the conditions such as the alkali and the transition metal source in the step (2) and the combined control of the dosage thereof and the mechanism of the two-stage heat treatment, the selective leaching behavior of the chemical components in the mushroom dregs can be further regulated and controlled unexpectedly, the synchronous leaching of the electrically harmful components is favorably reduced, the doping of the electrically beneficial components in the mushroom dregs is favorably realized, and the morphology of the material is favorably regulated and controlled, such as obtaining the graphene material with hierarchical holes, a thin layer structure and in-situ embedded metal simple substances; thus, the subsequent fluorination treatment is further matched, so that the in-situ uniform mosaic of the metal fluoride can be realized, and the grain size of the metal fluoride can be controlled. Researches show that based on the technical scheme of the invention, double synergy of chemical and physical structures can be realized, which is beneficial to remarkably improving the performance of the material in the aspect of electrochemistry. In addition, the method has simple flow, low preparation cost, large-scale production and good commercial application prospect, and realizes the purpose of changing harmful solid wastes into valuables.

The invention innovatively provides a hydrothermal liquefaction process under the assistance of alkali to realize the selective leaching of electrochemical beneficial components in the mushroom dregs and realize the selective utilization of the electrochemical beneficial components of the antibiotic mushroom dregs, so that the negative influence of harmful components in the mushroom dregs on the electrochemistry can be effectively avoided on the premise of fully utilizing the beneficial components in the mushroom dregs; the method is favorable for realizing chemical modification of graphene, in-situ mosaic of transition metal M and structure reconstruction, and is favorable for obtaining the material with the structure appearance of the thin-layer graphene and the in-situ mosaic of transition metal simple substance.

The antibiotic bacteria residue is at least one of terramycin bacteria residue, penicillin bacteria residue and cephalosporin bacteria residue;

preferably, the carbon content is 30-53 wt%, the nitrogen content is 3-16 wt%, the oxygen content is 10-25 wt%, the phosphorus content is 0.2-10 wt%, and the sulfur content is 0.3-12 wt% based on the dry weight of the antibiotic residues;

the grain diameter of the antibiotic fungi residues is 1-30 μm.

Preferably, in the step (1), the antibiotic fungi residues are pretreated by acid in advance and then are subjected to hydrothermal liquefaction.

Further research of the invention finds that acid liquor pretreatment is carried out on the antibiotic fungi residues in advance to obtain acid pretreatment residues, and then the acid pretreatment residues, alkali and water are slurried and then hydrothermal liquefaction treatment is carried out. Researches show that the acid pretreatment is carried out in advance, and the hydrothermal liquefaction process under the assistance of alkali is matched, so that the selective liquefaction leaching of electrochemical beneficial components in the mushroom dregs is further improved, and the subsequent chemical modification of graphene and the construction of a thin-layer structure are facilitated.

Preferably, the acid solution adopted in the acid pretreatment process is one or more of hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, phosphoric acid and acetic acid; preferably at a concentration of 10-20 wt.%; further preferred is 15-20 wt.%.

In the invention, the acid pretreatment comprises a first stage of acid treatment and a second stage of acid treatment which are sequentially carried out, wherein the acid of the first stage of acid treatment is a hydrofluoric acid solution; the second stage of acid treatment is hydrochloric acid solution.

Preferably, the acid pretreatment time is 2-8 h; further preferably 4 to 8 hours.

In the invention, the temperature of the acid pretreatment process is not particularly required, and can be room temperature, for example, 5-35 ℃.

In the invention, the acid pretreated mushroom dregs are selectively washed to be neutral, and then are subjected to hydrothermal liquefaction.

In the invention, hydrothermal liquefaction is carried out with the assistance of alkali, and the liquid part is collected by solid-liquid separation, namely the fungus dreg solution prepared subsequently by the invention. According to the research of the invention, under the preferable acid pretreatment thought, the hydrothermal liquefaction thought and the combined control of the alkali dosage are further matched, the leaching of electrochemical beneficial components in the mushroom dregs is further improved, and the chemical modification and physical structure of graphene are improved.

Preferably, the base is an alkali metal hydroxide, and more preferably at least one of sodium hydroxide and potassium hydroxide.

Preferably, the weight ratio of the alkali to the antibiotic residues is 0.5-2: 1 based on dry weight of the antibiotic residues. Research finds that the control of the optimal dosage is beneficial to further selectively controlling the liquefaction leaching of the electrochemical beneficial components in the mushroom dregs, so that the subsequent chemical modification and physical structure control of graphene are facilitated, and the electrochemical performance of the positive electrode material is improved.

More preferably, the weight ratio of the alkali to the antibiotic residues is 1-1.5: 1 based on the dry weight of the antibiotic residues; more preferably 1.4 to 1.5: 1.

research finds that the control of the hydrothermal temperature is helpful for further regulating and controlling the selective liquefaction of the electrochemical beneficial components in the mushroom dregs. Preferably, the temperature of the hydrothermal reaction is 120-210 ℃; further preferably 190-210 ℃; further preferably 190 to 200 ℃.

Preferably, the hydrothermal treatment is carried out for 8 to 20 hours.

In the present invention, the hydrothermal reaction system is subjected to solid-liquid separation to obtain a liquid fraction, and the liquid fraction is newly added with a transition metal source, and after dissolution and removal of water, the two-stage heat treatment is performed, and the water removal is, for example, evaporation under normal pressure or negative pressure.

In the invention, the transition metal M source is a salt of a transition metal M element, and preferably one or more of nitrate, sulfate, chloride and phosphate of the transition metal M element.

Preferably, the transition metal M is at least one of iron, cobalt, nickel, copper and zinc; further preferred is iron.

The research of the invention finds that under the combined action of the transition metal salt and the alkali in the bacterial liquid, the construction of a graphitized structure can be realized, the structure of graphene can be regulated, a thin layer and a material with a hierarchical pore structure can be obtained, and moreover, the chemical modification of graphene can be realized, for example, the in-situ doping modification of heteroatoms and the in-situ mosaic of transition metal M particles are realized, and the aggregation of transition metal and the control of the size of crystal particles are avoided; therefore, the method is beneficial to in-situ fluorination of the metal simple substance to obtain the cathode material with excellent electrochemical performance.

The research of the invention also finds that the control of the type and the dosage of the transition metal M source is beneficial to further realizing the regulation and control of the structure of the graphene and is beneficial to obtaining the material with a thin-layer structure and the transition metal M elementary substance embedded in situ.

Preferably, the weight ratio of the transition metal source to the antibiotic fungi residues is 0.5-3: 1 based on the dry weight of the antibiotic fungi residues; further preferably 1-2: 1; more preferably 1 to 1.5: 1.

in the invention, under the combined action of the hydrothermal liquefaction and the transition metal M source, the two-stage heat treatment process and the combined control of the temperature and the heating rate of the heat treatment process are further matched, so that the physical structure of graphene is improved, in-situ doping of heteroatoms and crystal grains of a transition metal M simple substance and in-situ uniform inlaying are facilitated, and the subsequent fluorination and annealing are facilitated to obtain the high-electrochemical-performance anode material.

In the step (2), the heat treatment process is carried out in an oxygen-free atmosphere, wherein the oxygen-free atmosphere is at least one of nitrogen, inert gas and hydrogen.

Preferably, the temperature of the first stage heat treatment is 450-550 ℃.

Preferably, the time of the first stage of heat treatment is 1-6 h; further preferably 1 to 4 hours.

Preferably, the temperature of the second-stage heat treatment is 700-.

Preferably, the time of the second stage of heat treatment is 1-6 h; further preferably 1 to 4 hours.

In the invention, the heating rate of the heat treatment is 2-10 ℃/min. Preferably, the heating rate of the heat treatment is 2-5 ℃/min

Preferably, in step (3), the heat-treated product is subjected to water washing and organic solvent washing in advance and then dried, followed by the subsequent fluorination and annealing treatment. Preferably, the organic solvent is ethanol.

In the invention, the transition metal simple substance is embedded into the material in advance, and the fluoride of the transition metal is formed in situ based on the fluorination of the simple substance, so that the crystal grains can be controlled, the agglomeration can be avoided, the composite form can be improved, the de-complexation can be avoided, the conductivity and the structural stability can be effectively improved, and the electrochemical performance of the obtained cathode material can be improved.

Preferably, the fluorine source is one or more of hydrofluoric acid, hydrogen fluoride, fluorine gas and nitrogen fluoride.

Preferably, the temperature of the fluorination process is 60-130 ℃; preferred fluorination times are from 1 to 36 h.

Preferably, the annealing temperature is 200-300 ℃; the preferred annealing time is 3-12 hours.

The invention discloses a preferable preparation method, which comprises the following steps:

the first step is as follows: purifying and liquefying, namely crushing antibiotic mushroom dregs, adding the obtained powder into water, adding dilute acid, washing, removing impurities, purifying, filtering until the pH value is neutral, drying at 80-120 ℃ for later use, adding the dried mushroom dregs powder into an alkaline solution, and performing hydrothermal treatment to obtain a liquefied mushroom dregs solution. The hydrothermal temperature is 120-210 ℃. The diluted acid is one or more of hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, phosphoric acid and acetic acid, the concentration of the diluted acid is 10-20 wt.%, and the washing time is 2-8 h. In a further preferred embodiment, the dilute acid is hydrochloric acid and hydrofluoric acid. The concentration is 15-20 wt.%, and the washing time is 4-8 h. The liquefaction temperature is 120-210 ℃, and the heat preservation time is 8-20 h. As a further preferable scheme, the liquefaction temperature is 200 ℃, and the heat preservation time is 12 h. The alkali is one of sodium hydroxide and potassium hydroxide. The mass ratio of the mushroom dregs to the alkali in the mixture is 2 (1-4). In a further preferable scheme, the mass ratio of the mushroom dregs to the alkali in the mixture is 2 (1-3). Most preferably, the mass ratio of the mushroom dregs to the alkali in the mixture is 2: 3.

The second step is that: mixing the mushroom dreg liquid with inorganic iron salt, drying at 80-120 ℃, and carrying out two-stage calcination under a protective atmosphere. The mass ratio of the bacteria residue (dry weight basis), the alkali and the inorganic ferric salt in the mixture is 2 (1-4) to (1-6), the calcining temperature ranges from 400 ℃ to 600 ℃ and 700 ℃ to 900 ℃, the heating rate is 5-10 ℃/min, and the heat preservation time is 1-6 h. The inorganic ferric salt is one or more of ferric nitrate, ferric sulfate, ferric chloride and ferric phosphate. In a further preferred embodiment, the inorganic iron salt is ferric nitrate. The mass ratio of the bacteria residue to the inorganic ferric salt is 2 (1-6). In a further preferable scheme, the mass ratio of the bacteria residue to the inorganic ferric salt in the mixture is 2 (1-3). Most preferably, the mass ratio of the bacteria residue to the inorganic iron salt in the mixture is 2: 2.

The third step: and (4) performing fluorination annealing treatment, namely washing and drying the powder obtained in the step two by using water and alcohol, performing fluorination treatment, drying, and performing annealing treatment in a protective atmosphere to obtain a final product. The fluorination temperature is 60-130 ℃, the fluorination time is 1-36h, the annealing temperature is 200-300 ℃, and the annealing time is 3-12 h. The annealing temperature is 200-300 ℃, and the annealing time is 3-12 h. As a further preferable scheme, the annealing temperature is 220-250 ℃, and the annealing time is 9-11h

The invention also provides a thin-layer graphene/transition metal fluoride composite positive active material prepared by the method; the composite material comprises thin-layer graphene and transition metal M fluoride which is uniformly dispersed and embedded on the surface of the graphene and in a substrate (graphene carbon substrate) in situ; the thin-layer graphene is doped with heteroatoms such as N, O, P, S in situ and has hierarchical pore structures of micropores, mesopores and macropores.

According to the technical scheme, the material comprises the thin-layer graphene, the thin-layer graphene is doped with heteroatoms and has a hierarchical hole and thin-layer structure, and the surface of the thin-layer graphene is embedded and/or inlaid with transition metal sulfides in situ.

The invention also provides application of the thin-layer graphene/transition metal fluoride composite positive active material prepared by the method, and the thin-layer graphene/transition metal fluoride composite positive active material is used as a positive active material of a lithium ion battery.

The invention also provides a lithium ion battery, which comprises the thin-layer graphene/transition metal fluoride composite positive active material prepared by the method;

preferably, the positive electrode of the lithium ion battery comprises the thin-layer graphene;

preferably, the positive active material of the lithium ion battery is the thin-layer graphene/transition metal fluoride composite positive active material.

Has the advantages that:

1. the invention provides a technical idea for preparing a composite cathode material with a thin layer and hierarchical holes, which is embedded with transition metal fluoride in situ, from antibiotic mushroom dregs, and fills up the technical blank of the antibiotic mushroom dregs in the aspect of graphene-based cathode materials.

2. According to the invention, antibiotic mushroom dregs are used as raw materials, the hydrothermal liquefaction process under the assistance of alkali is innovatively utilized, and the two-stage heat treatment process in the transition metal source is further matched, so that the electrochemical beneficial components in the mushroom dregs can be selectively utilized, the chemical modification of graphene, the in-situ mosaic of a transition metal M simple substance and the control of a physical structure are facilitated, and the subsequent fluorination and annealing processes are further matched, so that the positive electrode material which is doped with heteroatoms in situ, is inlaid with the transition metal M fluoride in situ and has a thin layer and a hierarchical pore structure can be obtained.

In the invention, the mushroom dreg waste is hydrothermally liquefied in an alkaline environment to obtain a uniform mushroom dreg solution. After drying, in a protective atmosphere, in-situ self-doping of electrochemical beneficial components of the mushroom dregs can be realized through two-stage calcination, and moreover, the effects of catalyzing graphitization and changing the structure of the carbon material can be realized, so that the ordered degree of the atomic arrangement of carbon is greatly improved, the electric conductivity is further improved, and meanwhile, the structure of the carbon material can be further changed, so that the three-dimensional cross-linked sheet graphene is formed; including hierarchical pore structures of macropores, mesopores and micropores. Moreover, the method is also beneficial to realizing in-situ uniform inlaying of the transition metal simple substance, and avoiding peeling and agglomeration; further matching with subsequent fluorination and annealing treatment, metal fluoride can be formed in situ on the surface of the graphene with the thin layer and hierarchical pore structure, and the conductivity and structural stability of the material are improved, so that the positive active material with excellent electrochemical performance is obtained.

By taking transition metal as iron as an example, the raw material for preparing the thin-layer graphene/ferric fluoride composite anode material carbon is antibiotic waste residue, belongs to solid waste in the pharmaceutical industry, and is high in yield, harmful and difficult to treat. The mushroom dreg waste material contains a certain amount of elements such as nitrogen, sulfur, oxygen and the like, which is beneficial to realizing the self-doping of heterogeneous atoms, greatly improving the conductivity of the carbon material and being beneficial to the rapid transmission of electric charges. The precursor obtained by catalytic pyrolysis is directly fluorinated, so that the in-situ synthesis of ferric fluoride is realized, the ferric fluoride formed in situ is embedded in the mutually-crosslinked thin graphene sheets, the conductivity of the ferric fluoride is effectively improved, the structural stability is guaranteed, and the excellent electrochemical performance is obtained.

3. In the innovative process, the combined control of acid pretreatment, alkali dosage, hydrothermal condition, transition metal source and dosage thereof, secondary heat treatment temperature, fluorination and annealing condition of the mushroom residue is further matched, the regulation and control of electrochemical beneficial components of the mushroom residue can be realized unexpectedly, the realization of physical structure and chemical modification of graphene and in-situ mosaic of metal fluoride are facilitated, and the electrochemical performance of the material is further improved.

Drawings

Fig. 1 is an X-ray diffraction pattern of the thin graphene/iron fluoride composite positive electrode prepared in example 1 of the present invention.

Fig. 2 is an SEM image of a thin graphene/iron fluoride composite positive electrode prepared in example 1 of the present invention; as can be seen from the figure, the layered graphene structure is not changed after the in-situ fluorination annealing treatment, and the iron fluoride particles are embedded on the surface of the lamellar graphite.

Fig. 3 is a TEM image of a thin graphene/iron fluoride composite positive electrode prepared in example 1 of the present invention;

as can be seen from the figure, the graphene/iron fluoride composite positive electrode prepared by the present invention exhibits a typical graphene lamellar structure, and iron fluoride is closely attached to the surface thereof.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the present invention is not limited to the following examples.

In the examples and comparative examples of the present invention, the dried terramycin dregs used had a carbon content of 41 wt.%, a nitrogen content of 8 wt.%, an oxygen content of 30 wt.%, a phosphorus content of 1.8 wt.%, and a sulfur content of 0.9 wt.%.

In the used dry penicillin fungi residue, the carbon content is 44 wt.%, the nitrogen content is 9.5 wt.%, the oxygen content is 36.1 wt.%, the phosphorus content is 1.2 wt.%, and the sulfur content is 1.4 wt.%.

The dry cephalosporin dregs contain C45 wt.%, N10 wt.%, O36 wt.%, P0.8 wt.% and S1.3 wt.%.

Example 1:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration and washing (water washing, and the washing in the following case of acid treatment process refers to water washing) for neutrality, and then drying to obtain dry bacterial dregs (pretreated bacterial dregs).

2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

As can be seen from the attached figure 1, the obtained product corresponds to ferric fluoride and graphite PDF card, which shows that the target product is successfully prepared, and as can be seen from the attached figure 2, after the in-situ fluorination annealing treatment by the technology disclosed by the invention, the structure of the layered graphene is not changed, and ferric fluoride particles are embedded on the surface of the flake-layer graphite. Fig. 3 further shows that the lamellar graphene/ferric fluoride composite positive electrode prepared by the invention has a typical graphene lamellar structure, and ferric fluoride is tightly adhered to the surface of the lamellar graphene/ferric fluoride composite positive electrode. Wherein the content of doped nitrogen element is 1.2 wt.%, the content of sulfur element is 0.8 wt.%, and the specific surface area is 33.5m²(ii)/g, having hierarchical pores and an average pore diameter of 8.9 nm.

Dispersing the obtained sheet layer graphene/ferric fluoride composite positive electrode material, conductive carbon black and polyvinylidene fluoride (PVD) in N-methyl pyrrolidone (NMP) according to the mass ratio of 8:1:1, uniformly mixing, coating on an aluminum foil to prepare a positive electrode, taking a metal lithium sheet as a negative electrode, and taking 1MLiPF₆The 2025 type lithium ion battery button cell is assembled by using/EC + DMC + EMC (1:1:1) as electrolyte and polypropylene porous membrane Celgard2400 as separator, and the cell is charged and discharged at normal temperature under the voltage range of 2-4.5V and with the current of 40mA/g (in the following cases, except for special statement, the test methods are allThe same as the method), the first discharge specific capacity is 218mAh/g, after 100 cycles, the capacity retention rate is 91.3%, and the capacity retention rate under the current density of 800mA/g is 89%.

Example 2:

compared with the embodiment 1, the difference is mainly that the alkali in the liquefaction process and the dosage of the ferric salt in the heat treatment process are controlled, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and then drying to obtain dry bacterial dregs (pretreated bacterial dregs).

2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, added with 1g of NaOH, and subjected to hydrothermal treatment at 200 ℃ for 12 h. After cooling, 1gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to perform electrochemical performance detection (the test method is the same as that in embodiment 1), and the first discharge specific capacity at 40mA/g is 189mAh/g, the capacity retention rate after 100 cycles is 76.7%, and the capacity retention rate at 800mA/g is 74.3% under the current density is recorded.

Example 3:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, carrying out suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h,and (4) filtering, washing, filtering, drying after neutrality to obtain dry mushroom dregs (pretreated mushroom dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and added with 4g of NaOH, and hydrothermal at 200 ℃ for 12 h. After cooling 6gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is 234mAh/g, the capacity retention rate after 100 cycles is 74.5%, and the capacity retention rate under the current density of 800mA/g is 69.3% are recorded.

Example 4:

compared with the embodiment 1, the difference is mainly that the temperature of the liquefaction process is controlled to be 120 ℃, and specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 120 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. Vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon gas to obtain the graphene with thin sheetsThe/ferric fluoride composite anode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the first discharge under 40mA/g is 193mAh/g, the capacity retention rate is 86.3 percent after 100 cycles, and the capacity retention rate under the current density of 800mA/g is 82.4 percent.

Example 5:

compared with the embodiment 1, the difference is mainly that the temperature of the liquefaction process is controlled to be 210 ℃, and specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 210 ℃ for 8 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 209mAh/g, the capacity retention rate after 100 cycles is 87.8%, and the capacity retention rate under the current density of 800mA/g is recorded to be 84.4%.

Example 6:

compared with the embodiment 1, the difference is mainly that the heat treatment mechanism is regulated and controlled, and specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, and then adding 120mL of 18 wt.% HCl acid solution for dissolutionStirring for 4h, filtering, washing to neutrality, filtering, and drying to obtain dried mushroom residue (pretreated mushroom residue). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 400 ℃ for 4h, continuously heating to 700 ℃, calcining for 4h (the heating rate is 2 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 192mAh/g under 40mA/g, the capacity retention rate of 79.6 percent after 100 cycles and the capacity retention rate of 76.9 percent under the current density of 800mA/g are recorded.

Example 7:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, calcining at 600 ℃ for 2h, continuously heating to 900 ℃, calcining for 2h (the heating rate is 10 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. Vacuum drying at 80 deg.C, annealing at 220 deg.C for 10 hr in a tube furnace under the protection of argon gas to obtain lamellar layer stoneThe graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 226mAh/g under 40mA/g, the capacity retention rate of 82.3 percent after 100 cycles and the capacity retention rate of 79.9 percent under the current density of 800mA/g are recorded.

Example 8:

compared with the example 1, the difference is mainly that the fluorination conditions are controlled, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a water-heated tank containing 10ml of acid (40 wt.%) of polytetrafluoroethylene and fluorinated at 60 ℃ for 36 hours. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 211mAh/g, the capacity retention rate is 90.7% after 100 cycles, and the capacity retention rate under the current density of 800mA/g is recorded to be 88.5%.

Example 9:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution,stirring for 4h, filtering, washing to neutrality, filtering, and drying to obtain dried mushroom residue (pretreated mushroom residue). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 130 ℃ for 1 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 203mAh/g, the capacity retention rate is 88.9% after 100 cycles, and the capacity retention rate under the current density of 800mA/g is recorded to be 86.6%.

Example 10:

compared with the embodiment 1, the difference is mainly that the annealing conditions are controlled, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. Vacuum drying at 80 ℃, then annealing for 12 hours at 200 ℃ in a tube furnace under the protection of argon gas to obtain sheet graphene/bamboo cell/cellAnd (3) iron fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 207mAh/g, the capacity retention rate is 90.4% after 100 cycles, and the capacity retention rate under the current density of 800mA/g is recorded to be 87.9%.

Example 11:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 3h at 300 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 216mAh/g under 40mA/g, the capacity retention rate of 91% after 100 cycles and the capacity retention rate of 88.8% under the current density of 800mA/g are recorded.

Example 12:

compared with the embodiment 1, the difference is mainly that the mushroom dregs are penicillin mushroom dregs, and the concrete steps are as follows:

taking 30g of dry antibiotic mushroom dreg raw material as a carbon precursor, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, and stirringAnd 4h, performing suction filtration, washing to be neutral, and performing suction filtration and drying to obtain dry mushroom dregs (pretreated mushroom dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of KOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 212mAh/g, the capacity retention rate is 90.2% after 100 cycles, and the capacity retention rate under the current density of 800mA/g is 88.7%.

Example 13:

compared with the embodiment 1, the difference is mainly that the mushroom dregs are cephalosporin mushroom dregs, and the mushroom dregs specifically comprise:

taking cephalosporium residues as a carbon precursor, taking 30g of dry antibiotic residues as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry residues (pretreated residues). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. Vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the lamellar graphene/ferric fluoride compositeAnd mixing the positive electrode material.

The sample in the embodiment is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is 215mAh/g, the capacity retention rate after 100 cycles is 91.1%, and the capacity retention rate under the current density of 800mA/g is 88.9% are recorded.

Comparative example 1:

the main difference from example 1 is that no liquefaction process is used, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). Adding 2g of dried mushroom residue powder (pretreated mushroom residue) into 20mL of water, stirring for 5min, and adding 3g of NaOH and 2g of Fe (NO)₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the blocky carbon/ferric fluoride composite anode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 192mAh/g under 40mA/g, the capacity retention rate of 73.4 percent after 100 times of circulation and the capacity retention rate of 68.5 percent under the current density of 800mA/g are recorded.

Comparative example 2:

the main difference from example 1 is that no alkali is added during liquefaction, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration and drying to obtain dry bacterial dregs (pre-prepared bacterial dregs)Treatment of the mushroom dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then hydrothermally treated at 200 ℃ for 12 hours. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water, vacuum drying, grinding 0.2g of powder with iron powder, placing on the liquid surface of a water heating tank filled with 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the blocky carbon/ferric fluoride composite anode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 186mAh/g under 40mA/g, the capacity retention rate of 67.1 percent after 100 times of circulation and the capacity retention rate of 62.3 percent under the current density of 800mA/g are recorded.

Comparative example 3:

the main difference from example 1 is that the amount of alkali used in the liquefaction process exceeds the limits of the present invention, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and then drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, added with 8g of NaOH, and subjected to hydrothermal treatment at 200 ℃ for 12 h. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. Vacuum drying at 80 deg.C in a tube furnaceAnd annealing at 220 ℃ for 10h under the protection of argon to obtain the porous carbon/ferric fluoride composite cathode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the first discharge under 40mA/g is recorded to be 161mAh/g, the capacity retention rate is recorded to be 63.2 percent after 100 times of circulation, and the capacity retention rate is recorded to be 54.7 percent under the current density of 800 mA/g.

Comparative example 4:

the main difference from the embodiment 1 is that a two-step carbonization process is not adopted, specifically:

taking oxytetracycline slag as a carbon precursor, taking 30g of dry antibiotic bacteria slag raw material, firstly dispersing into 120mL of 20 wt.% HF acid solution, stirring for 4h, then carrying out solid-liquid separation, washing to neutrality, carrying out suction filtration, then adding into 120mL of 18 wt.% HCl acid solution, stirring for 4h, carrying out suction filtration, washing to neutrality, carrying out suction filtration and drying to obtain dry bacteria slag (pretreated bacteria slag). Adding 2g of dried mushroom residue powder into 20mL of water, stirring for 5min, adding 3g of NaOH, and performing hydrothermal treatment at 200 ℃ for 12 h. After cooling, 2g Fe (NO) were added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, directly heating to 800 ℃, calcining for 4h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the blocky carbon/ferric fluoride composite anode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the capacity retention rate of the lithium ion button cell under 40mA/g for the first discharge is 191mAh/g, 73.2 percent after 100 times of circulation and 68.3 percent under 800mA/g current density are recorded.

Comparative example 5:

compared with the example 1, the difference is mainly that the temperature rising rate is too fast, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, carrying out suction filtration,and adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and drying to obtain dried mushroom dregs (pretreated mushroom dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃ for 2h (the heating rate is 20 ℃/min), cooling to room temperature, and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon gas to obtain the graphene/nickel fluoride composite cathode material with serious agglomeration.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity of 186mAh/g under 40mA/g, the capacity retention rate of 63.5 percent after 100 times of circulation and the capacity retention rate of 59.2 percent under 800mA/g current density are recorded.

Comparative example 6:

compared with the example 1, the difference is mainly that the calcination temperature is too high, specifically:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and then drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, calcining at 500 ℃ for 2h, continuously heating to 1000 ℃, calcining for 2h (the heating rate is 5 ℃/min), and coolingCooling to room temperature and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon gas to obtain the graphene/nickel fluoride composite cathode material with serious agglomeration.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the initial discharge under 40mA/g is 184mAh/g, the capacity retention rate is 64.6 percent after 100 times of circulation, and the capacity retention rate under the current density of 800mA/g is 60.3 percent.

Comparative example 7:

compared with the example 1, the difference is mainly that no inorganic iron salt catalyst is added, and the specific steps are as follows:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, performing suction filtration, and drying to obtain dry bacterial dregs (pretreated bacterial dregs). Adding 2g of dried mushroom residue powder into 20mL of water, stirring for 5min, adding 3g of NaOH, and performing hydrothermal treatment at 200 ℃ for 12 h. Stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, calcining at 500 ℃ for 2h, continuously heating to 800 ℃ for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water, vacuum drying, grinding 0.2g of powder with iron powder, placing on the liquid surface of a water heating tank filled with 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the blocky carbon/ferric fluoride composite anode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the capacity retention rate of 183mAh/g under 40mA/g for the first time, 65.2% after 100 times of circulation and 59.6% under 800mA/g current density are recorded.

Comparative example 8:

compared with example 1, the difference is mainly that the fluorination is incomplete, specifically:

taking cephalosporium residues as a carbon precursor, taking 30g of dry antibiotic residues as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and drying to obtain dry residues (pretreated residues). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 0.5 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the graphene/ferric fluoride/iron carbide composite cathode material with the thin layer.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the initial discharge under 40mA/g is 163mAh/g, the capacity retention rate is 69.3 percent after 100 times of circulation, and the capacity retention rate under the current density of 800mA/g is 54.9 percent.

Comparative example 9:

compared with the example 1, the difference is mainly that the annealing temperature is too high, specifically:

taking cephalosporium residues as a carbon precursor, taking 30g of dry antibiotic residues as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and drying to obtain dry residues (pretreated residues). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 450 ℃ in a tubular furnace under the protection of argon gas to obtain the thin graphene/ferric fluoride/ferric oxide composite cathode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the initial discharge under 40mA/g is 145mAh/g, the capacity retention rate is 59.4 percent after 100 times of circulation, and the capacity retention rate under the current density of 800mA/g is 44.3 percent.

Comparative example 10:

compared with the example 1, the difference is mainly that the acid-washing heat treatment product is recombined, and specifically comprises the following steps:

taking oxytetracycline bacterial dregs as a carbon precursor, taking 30g of dry antibiotic bacterial dregs as a raw material, firstly dispersing the raw material into 120mL of 20 wt.% HF acid solution, stirring for 4h, performing suction filtration, then adding the mixture into 120mL of 18 wt.% HCl acid solution, stirring for 4h, performing suction filtration, washing to be neutral, and then drying to obtain dry bacterial dregs (pretreated bacterial dregs). 2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (a dreg liquid), and adding 2gFe (NO) into the dreg liquid₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. Washing with acid, washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, mechanically mixing 0.2g powder (acid-washed heat-treated product) with 0.2g iron powder, placing on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. Vacuum drying at 80 deg.C, annealing at 220 deg.C for 10 hr in a tube furnace under the protection of argon gas to obtainTo a thin-layer graphene/ferric fluoride composite cathode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the specific capacity of the first discharge under 40mA/g is recorded to be 188mAh/g, the capacity retention rate is 69.5 percent after 100 times of circulation, and the capacity retention rate under the current density of 800mA/g is recorded to be 62.5 percent.

Comparative example 11:

compared with the embodiment 1, the difference is mainly that the conventional graphene is adopted, specifically:

2g of conventional graphene is taken and added into 20mL of water, stirred for 5min, added with 3g of NaOH and hydrothermally treated at 200 ℃ for 12 h. After cooling, 2gFe (NO) was added₃)₃.9H₂And O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, firstly calcining at 500 ℃ for 2h, continuously heating to 800 ℃, calcining for 2h (the heating rate is 5 ℃/min), cooling to room temperature, and taking out. After washing with water and vacuum drying, 0.2g of the powder was placed on the surface of a hot pot containing 10ml of acid (40 wt.%) polytetrafluoroethylene and fluorinated at 110 ℃ for 4 h. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon gas to obtain the graphene/ferric fluoride composite cathode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the capacity retention rate of the lithium ion button cell under 40mA/g for the first discharge is 190mAh/g, 73.5% after 100 times of circulation and 68.3% under 800mA/g current density are recorded.

Comparative example 12

In comparison with example 1, the difference is only Fe (NO)₃)₃.9H₂The amount of O used was 8g (iron to slag ratio 4:1).

2g of dried mushroom residue powder (pretreated mushroom residue) was added to 20mL of water, stirred for 5min, and then 3g of NaOH was added thereto, and hydrothermal treatment was carried out at 200 ℃ for 12 hours. Performing solid-liquid separation on the hydrothermal system to obtain a solution part (bacteria residue liquid), and adding 8gFe (NO) into the bacteria residue liquid₃)₃.9H₂O, stirring for 10min, stirring at 100 ℃, evaporating to dryness, placing in a tubular furnace filled with argon, calcining at 500 ℃ for 2h, continuously heating to 800 ℃ for 2h (the heating rate is 5 ℃/min), cooling to room temperature, taking out. Washing with water to neutrality, washing with ethanol, vacuum drying to obtain heat-treated product, placing 0.2g powder (heat-treated product) on the liquid surface of a water heating tank containing 10mLHF acid (40 wt.%), and fluorinating at 110 deg.C for 4 hr. And (3) after vacuum drying at 80 ℃, annealing for 10 hours at 220 ℃ in a tube furnace under the protection of argon to obtain the sheet graphene/ferric fluoride composite cathode material.

The sample in the comparative example is assembled into a lithium ion button cell to carry out electrochemical performance detection, and the first discharge specific capacity under 40mA/g is recorded to be 235mAh/g, the capacity retention rate is 64.1 percent after 100 times of circulation, and the capacity retention rate under 800mA/g current density is recorded to be 53.2 percent.

Claims

1. A method for preparing a thin-layer graphene/transition metal fluoride composite positive active material by using antibiotic fungi residues is characterized by comprising the following steps:

step (1): hydrothermal liquefaction

Pretreating antibiotic residues with acid in advance, then carrying out hydrothermal liquefaction on an aqueous solution containing the antibiotic residues and alkali, and then carrying out solid-liquid separation to obtain a residue solution; the weight ratio of the alkali to the antibiotic fungi residues is 0.5-2: 1 based on the dry weight of the antibiotic fungi residues; the temperature of the hydrothermal reaction is 120-210 ℃;

step (2): thermal treatment

Adding a transition metal M source into the fungus dreg solution, mixing liquid phases, performing dehydration treatment, and then performing heat treatment; the heat treatment comprises a first section of pretreatment and a second section of heat treatment which are sequentially carried out; wherein the temperature of the first stage heat treatment is 400-600 ℃; the temperature of the second-stage heat treatment is 700-900 ℃; and the heating rate in the heat treatment process is 2-10 ℃/min; the transition metal M is at least one of iron, cobalt, nickel, copper and zinc; the weight ratio of the transition metal M source to the antibiotic fungi residues is 0.5-3: 1 based on the dry weight of the antibiotic fungi residues;

and (3): in situ fluorination

Fluorinating and annealing the product obtained by the heat treatment in the step (2) and a fluorine source to obtain the thin-layer graphene/M metal fluoride composite positive electrode active material;

the fluorine source is one or more of hydrofluoric acid, hydrogen fluoride, fluorine gas and nitrogen fluoride; the temperature of the fluorination process is 60-130 ℃; the fluorination time is 1-36 h; the annealing temperature is 200-300 ℃.

2. The method of claim 1, wherein the antibiotic mushroom dregs are at least one of terramycin mushroom dregs, penicillin mushroom dregs and cephalosporin mushroom dregs.

3. The method of claim 2, wherein the carbon content is 30-53 wt.%, the nitrogen content is 3-16 wt.%, the oxygen content is 10-25 wt.%, the phosphorus content is 0.2-10 wt.%, and the sulfur content is 0.3-12 wt.%, based on the dry weight of the antibiotic pomace.

4. The method of claim 2, wherein the antibiotic drag is at a particle size of 1-30 μm.

5. The method of claim 1, wherein in the step (1), the acid pretreatment process uses one or more of hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, phosphoric acid and acetic acid.

6. The method of claim 5, wherein the acid pretreatment process uses an acid solution having a concentration of 10 to 20 wt.%.

7. The method of claim 5, wherein the acid pretreatment time is 2 to 8 hours.

8. The method of claim 1, wherein in step (1), the base is an alkali metal hydroxide.

9. The method of claim 8, wherein the base is at least one of sodium hydroxide and potassium hydroxide.

10. The method according to claim 1, wherein the ratio of the base to the weight of the antibiotic pomace is 1-1.5: 1 based on dry weight of the antibiotic pomace.

11. The method as claimed in claim 1, wherein the temperature of the hydrothermal reaction is 190-210 ℃.

12. The method according to claim 1, wherein in the step (2), the transition metal M source is a salt of a transition metal M element.

13. The method according to claim 12, wherein in the step (2), the source of the transition metal M is one or more of nitrate, sulfate, chloride and phosphate of the transition metal M.

14. The method of claim 1, wherein the transition metal M is iron.

15. The method according to claim 1, wherein the ratio of the transition metal M source to the antibiotic pomace is 1-2: 1 by weight based on dry weight of the antibiotic pomace.

16. The method of claim 1, wherein the heat treatment process in step (2) is performed in an oxygen-free atmosphere, and the oxygen-free atmosphere is at least one of nitrogen, an inert gas, and hydrogen.

17. The method of claim 1, wherein the first stage heat treatment is performed for a period of 2 to 6 hours.

18. The method of claim 1, wherein the second heat treatment is performed for 2 to 6 hours.

19. The method according to claim 1, wherein in the step (3), the heat-treated product is subjected to water washing-organic solvent washing in advance and drying, and then subjected to subsequent fluorination and annealing treatments.

20. The method of claim 19, wherein the organic solvent is ethanol.

21. The method of claim 1 wherein the fluorine source is hydrofluoric acid.

22. The method of claim 1, wherein the annealing time is 3 to 12 hours.

23. A thin-layer graphene/transition metal fluoride composite positive electrode active material prepared by the method of any one of claims 1 to 22; the preparation method is characterized by comprising thin-layer graphene and transition metal M fluoride which is uniformly dispersed and embedded on the surface of the graphene and in a substrate in situ; the thin-layer graphene is doped with N, O, P, S heteroatoms in situ and has hierarchical pore structures of micropores, mesopores and macropores.

24. The application of the thin-layer graphene/transition metal fluoride composite positive active material prepared by the method of any one of claims 1 to 22 is characterized in that the thin-layer graphene/transition metal fluoride composite positive active material is used as a positive active material of a lithium ion battery.

25. A lithium ion battery, characterized by comprising the thin-layer graphene/transition metal fluoride composite positive electrode active material prepared by the method of any one of claims 1 to 22.

26. The lithium ion battery of claim 25, wherein the positive electrode of the lithium ion battery comprises the thin layer graphene.

27. The lithium ion battery of claim 25, wherein the positive active material of the lithium ion battery is the thin-layer graphene/transition metal fluoride composite positive active material.