Preparation method of fungal mycelium-based electrode material

Abstract

The invention belongs to the technical field of biological materials, and particularly relates to a preparation method of a fungal mycelium-based electrode material. The porous carbon material is obtained through low-temperature carbonization by taking the phanerochaete chrysosporium mycelium of a mode strain of white-rot fungi as a carbon source and KOH as an activating agent, and is used as the negative electrode material of the lithium ion battery. The used carbon source phanerochaete chrysosporium mycelium has the following advantages of being fast in propagation, easy to obtain and high in prepared material strength, and having a natural net structure. According to the invention, the carbonization temperature is 500-900 DEG C, which is far lower than the carbonization temperature (2200-3000 DEG C) of the graphite negative electrode of the lithium ion battery. The mycelium-based derived carbon material which is high in specific surface area (2000-3000m < 2 > / g), developed in pore structure, excellent in lithium storage performance, high in theoretical specific capacity and good in cycling stability is prepared by adopting a low-cost, low-energy-consumption, simple and controllable method, and has a good application prospect in the aspect of electrochemical energy storage.

Description

Technical Field

[0001] The invention belongs to the technical field of biomaterials, and in particular relates to a method for preparing a fungal mycelium-based electrode material. Background Art

[0002] Carbon materials are widely used in the development of clean energy and the control of environmental pollution due to their porous structure, high specific surface area, high conductivity and high environmental stability. Based on the concepts of green chemistry and sustainable development, the introduction of living biological systems into the field of materials science and the acquisition of materials from biological resources in a controllable manner are current research hotspots. Natural materials such as cellulose, lignin, and pectin can be used as carbon sources for the preparation of high-performance carbon materials due to their advantages such as wide sources, large quantities, low prices, easy processing and unique natural structures. However, the preparation of high-performance carbon materials using these natural materials has the disadvantages of difficult raw material processing, low yield, and long time consumption, which limits their large-scale application. In order to solve the above problems, it is urgent to develop a simple, economical, efficient and controllable carbon material preparation process.

[0003] LIB is a widely used energy storage device, and the commonly used negative electrode material is graphite. However, the graphitization process of graphite needs to be carried out at a high temperature of 2200-3000℃. This high temperature condition places stringent requirements on the equipment, limiting the industrialization process. In addition, the current maximum theoretical specific capacity of LIB is only 372 mAh / g. Therefore, it is urgent to develop new negative electrode materials to overcome the defects of high-temperature preparation and improve its theoretical specific capacity.

[0004] As a renewable resource, biomass has the advantages of wide sources, large quantities and low prices. Using biomass as a carbon source for the preparation of high-performance carbon materials is an inevitable choice for environmental protection and sustainable development. Studies have found that raw materials and preparation methods are key factors affecting the performance of biomass-derived carbon materials. Fungal mycelium, as a commonly used biomass carbon source, can cross-link with each other to form a unique three-dimensional network structure, which provides a rich pore structure for the preparation of porous carbon materials. Studies have found that the increase in the specific surface area and microporous structure of LIB negative electrode carbon materials can make the contact between the electrode and the electrolyte more sufficient, thereby improving its energy storage performance. Studies have found that the extracellular polymers produced by fungi during metabolism will cover the surface of the mycelium and are not easy to remove. During the carbonization process, tar-like substances can be formed to cover and block the network structure formed by the mycelium. Physical or chemical activation is an effective way to solve this problem. Phanerochaete chrysosporium As a model species of white rot fungi, it is often used in the preparation of porous carbon materials due to its well-developed mycelium, unique three-dimensional network structure and high strength of the prepared materials. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide an economical, efficient, simple and environmentally friendly method for preparing fungal mycelium-based electrode materials for LIB. The present invention adopts a low-cost, low-energy, simple and controllable method to prepare a fungal mycelium-based electrode material with a high specific surface area (2000-3000m 2 / g), mycelium-based electrode materials with well-developed pore structure, excellent lithium storage performance, high theoretical specific capacity and excellent cycle stability have good application prospects in electrochemical energy storage.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] The present invention provides a method for preparing a fungal mycelium-based electrode material, and the specific steps are as follows: (1) Preparation of fungal mycelium Will Phanerochaete chrysosporium The spore suspension was inoculated into a conical flask filled with sterilized potato extract powder-glucose medium and cultured in a shaker to form mycelium; (2) Freeze-drying of fungal mycelium The mycelium was washed with deionized water and then pre-frozen in a refrigerator, and then dried using a vacuum freeze dryer; (3) Preparation of precursor carbon material-I The freeze-dried sample was placed in a tube furnace, heated to 500-700°C at a rate of 3-5°C / min in an inert atmosphere and kept at this temperature for 1-3 h to obtain a precursor carbon material-I; (4) Preparation of precursor carbon material-II Precursor carbon material-I and KOH powder are mixed in a certain mass ratio, and then ground in an agate mortar for 10-30 minutes; the ground activated mixture is placed in a tube furnace, heated to 700-900°C at a rate of 5-10°C / min in an inert atmosphere and kept warm for 1-3 hours to obtain precursor carbon material-II; (5) Preparation of precursor carbon material-III The precursor carbon material-II is acidified, washed with water and dried in sequence to obtain the precursor carbon material-III; (6) Preparation of electrode materials First, the precursor carbon material-III, the conductive agent carbon black, and the binder polyvinylidene fluoride PVDF are mixed in a certain mass ratio to form a slurry, and then the slurry is coated on a copper current collector and vacuum dried, and finally the electrode sheet is punched out.

[0008] In the above step (1), the strain of Phanerochaete chrysosporium is Phanerochaete chrysosporium(USANDM3-2), which was purchased from Guangdong Microbial Culture Collection Center; under sterile conditions, the prepared fungal spore suspension was added to the sterilized potato-glucose medium.

[0009] In the above step (1), the spore count of the spore suspension is 1×10 5 -3×10 5 spores / mL, the amount of spore suspension added is 1-5mL, and the volume of potato powder-glucose medium is 100mL; the components of the potato-glucose medium include: 100-150g / L potato powder and 5-15g / L glucose, and the pH value of the medium is adjusted to 4.50-5.50 with sulfuric acid solution; the culture temperature of the fungus is 25-35°C, the shaking speed is 120-180rpm, and the culture time is 2-4 days.

[0010] In the above step (2), the sample is placed in a refrigerator and pre-frozen at -10--20°C for 2-4 hours, and then dried in a vacuum freeze dryer at -45--50°C for 24-36 hours; before vacuum freeze drying, the mycelium is washed with deionized water to remove the mucus on the surface of the mycelium.

[0011] In the above steps (3) and (4), the inert atmosphere is a nitrogen atmosphere.

[0012] In the above step (4), the precursor carbon material and KOH powder are mixed in a mass ratio of 1:3-1:5.

[0013] In the above step (5), the precursor carbon material-II after acidification is soaked in a 1-3 mol / L sulfuric acid solution for 10-30 min, washed with deionized water until neutral, and dried in an oven at 50-80° C. for 10-30 h.

[0014] In the above step (5), the BET specific surface area of ​​the precursor carbon material-III is 2000-3000m 2 / g, and the average pore size is 2-5nm.

[0015] In the above step (6), the mass ratio of the precursor carbon material-III to the conductive agent carbon black and the binder PVDF is 7:1:1-9:1:1.

[0016] Furthermore, the present invention provides an application of the fungal mycelium-based electrode material as a negative electrode material for LIB in assembling a lithium-ion battery; the application method is as follows: The fungal mycelium-based electrode material is mixed with the conductive agent carbon black and the binder PVDF in a mass ratio of 7:1:1-9:1:1 to form a slurry, which is coated on the copper current collector and vacuum dried. The electrode sheet is then punched out by a punching machine. The vacuum drying conditions of the coated slurry are 50-80°C and the drying time is 12-24h.

[0017] The present invention conducts specific surface area-pore size analysis (BET) and scanning electron microscope (SEM) analysis on the prepared precursor carbon material-III to characterize its structure and performance. The electrochemical performance of the prepared battery is characterized from the perspectives of resistance, conductivity and theoretical specific capacity.

[0018] The present invention is characterized by fast reproduction, easy acquisition, and natural network structure. Phanerochaete chrysosporium Mycelium is used as a carbon source and KOH is used as an activator to prepare a LIB negative electrode material with a large specific surface area, a developed pore structure, abundant micropores, and excellent conductive properties. Compared with the prior art, the present invention has the following advantages: The present invention uses fungal mycelium as a carbon source to prepare a porous carbon material that can be used as a negative electrode material for LIB, and its specific surface area is as high as 2000-3000m 2 / g, and the average pore size is 2-5nm.

[0019] The carbonization temperature of the present invention is 500-900°C, which is much lower than the carbonization temperature of LIB graphite negative electrode 2200-3000°C.

[0020] The LIB assembled from the fungal mycelium-based electrode material prepared in the present invention has a theoretical specific capacity of up to 389-531 mAh / g after 100 cycles at 0.1C, which is much higher than the theoretical specific capacity of 327 mAh / g of the LIB prepared from the graphite negative electrode.

[0021] The present invention uses low-cost and renewable fungal mycelium as a carbon source. The fungus can form a unique three-dimensional network structure due to the interconnection of mycelium, which provides abundant pore resources for the subsequent preparation of porous carbon materials. In addition, the present invention uses KOH to activate the precursor carbon material at low temperature, which significantly increases the specific surface area of ​​the material and provides more active sites for LIB. The developed pore structure and abundant active sites of fungal mycelium-based electrode materials are conducive to the penetration of electrolytes and the rapid transmission of lithium ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0023] In the embodiment, the culture Phanerochaete chrysosporium(USA NDM3-2) The liquid culture medium used is an improved potato-glucose culture medium, whose ingredients include: 100-150 g / L potato extract and 5-15 g / L glucose; and the pH value of the culture medium is adjusted to 4.50-5.50 with 3 mol / L sulfuric acid solution.

[0024] Phanerochaete chrysosporium (USA NDM3-2) was purchased from Guangdong Microbial Culture Collection Center.

[0025] The model of the shaker is: full-temperature oscillating incubator ZHWY-2112B produced by Jintan Jingda Instrument Manufacturing Co., Ltd., Changzhou City, Jiangsu Province.

[0026] Example 1

[0027] Prepare potato-glucose medium, which includes: 100g / L potato powder and 5g / L glucose; and 3mol / L The pH value of the culture medium was adjusted to 4.50 with sulfuric acid solution and then sterilized by high pressure steam at 121°C for 30 min.

[0028] The number of spores in 1 mL is 1 × 10 5 Spores / mL Phanerochaete chrysosporium The spore suspension of (USA NDM3-2) was inoculated into a 250 mL conical flask containing 100 mL of sterilized potato extract powder-glucose medium and cultured with shaking at 25°C and 120 rpm for 2 days to form mycelium.

[0029] The mycelium washed with deionized water was first placed in a -10--20℃ refrigerator for pre-freezing for 2 hours, and then dried in a vacuum freeze dryer at -45--50℃ for 24 hours.

[0030] The freeze-dried sample was placed in a tube furnace, heated to 500 °C at a rate of 3 °C / min in a N2 atmosphere and kept at this temperature for 1 h to prepare the precursor carbon material-I.

[0031] The obtained precursor carbon material-I was mixed with KOH powder at a mass ratio of 1:3, and then ground in an agate mortar for 10 min. The mixture was placed in a tube furnace, heated to 700°C at a rate of 5°C / min in a N2 atmosphere and kept at this temperature for 1 h to obtain the precursor carbon material-II.

[0032] After the precursor carbon material-II was naturally cooled to room temperature, it was soaked in 1 mol / L sulfuric acid solution for 10 min. The acidified biochar was washed with deionized water to pH = 7, and dried in an oven at 50°C for 10 h to obtain the precursor carbon material-III.

[0033] The precursor carbon material-III, carbon black and PVDF obtained in step (6) are mixed in a mass ratio of 7:1:1 to form a slurry, and then the slurry is coated on a copper current collector, vacuum dried at 50° C. for 12 hours, and then punched by a punching machine to obtain an electrode sheet.

[0034] Characterization of the electrochemical performance of batteries The electrochemical performance of the prepared battery was characterized from the perspectives of resistance, conductivity and theoretical specific capacity: BET analysis of the prepared precursor carbon material-III showed that the specific surface area was 2619 m 2 / g, with an average pore size of 2nm. SEM analysis shows that after KOH activation, the pore structure and defect sites of fungus-derived carbon materials are significantly increased. The present invention also measures the electrochemical performance of LIBs prepared with fungal mycelium-based carbon materials as negative electrodes, and the resistance, conductivity and theoretical specific capacity are 32.10Ω / m, 4.96S / cm and 530.81mAh / g, respectively.

[0035] Example 2

[0036] A potato-glucose culture medium was prepared, the ingredients of which included 130 g / L potato extract powder and 10 g / L glucose; the pH value of the culture medium was adjusted to 5.00 with 3 mol / L sulfuric acid solution, and sterilized by high-pressure steam at 121°C for 30 min.

[0037] The spore count in 3 mL is 2 × 10 5 Spores / mL Phanerochaete chrysosporium The spore suspension of (USA NDM3-2) was inoculated into a 250 mL conical flask containing 100 mL of sterilized potato extract powder-glucose medium and cultured at 30°C and 150 rpm for 3 days to form mycelium.

[0038] The mycelium washed with deionized water was first placed in a -10--20℃ refrigerator for pre-freezing for 3 hours, and then dried in a vacuum freeze dryer at -45--50℃ for 30 hours.

[0039] The freeze-dried sample was placed in a tube furnace, heated to 600 °C at a rate of 4 °C / min in a N2 atmosphere and kept at this temperature for 2 h to prepare the precursor carbon material-I.

[0040] The obtained precursor carbon material-I was mixed with KOH powder at a mass ratio of 1:4, and then ground in an agate mortar for 20 minutes. The mixture was placed in a tube furnace, heated to 800°C at a rate of 8°C / min in a N2 atmosphere and kept warm for 2 hours to obtain the precursor carbon material-II.

[0041] After the precursor carbon material-II was naturally cooled to room temperature, it was soaked in a 2 mol / L sulfuric acid solution for 20 min. The acidified biochar was washed with deionized water to pH = 7, and dried in an oven at 65°C for 20 h to obtain the precursor carbon material-III.

[0042] The precursor carbon material-III, carbon black and PVDF obtained in step (6) are mixed in a mass ratio of 8:1:1 to form a slurry, and then the slurry is coated on a copper current collector, vacuum dried at 65° C. for 18 hours, and then punched by a punching machine to obtain an electrode sheet.

[0043] Characterization of the electrochemical performance of batteries The electrochemical performance of the prepared battery was characterized from the perspectives of resistance, conductivity and theoretical specific capacity: BET analysis of the prepared precursor carbon material-III showed that the specific surface area was 2936m 2 / g, with an average pore size of 3nm. SEM analysis shows that after KOH activation, the pore structure and defect sites of the fungus-derived carbon material are significantly increased. The present invention also measures the electrochemical performance of LIB prepared with fungal mycelium-based carbon material as the negative electrode, and its resistance, conductivity and theoretical specific capacity are 39.50Ω, 4.03S / cm and 484.80mAh / g, respectively.

[0044] Example 3

[0045] A potato-glucose culture medium was prepared, the ingredients of which included 150 g / L potato extract and 15 g / L glucose. The pH value of the culture medium was adjusted to 5.50 with 3 mol / L sulfuric acid solution, and sterilized by high pressure steam at 121°C for 30 min.

[0046] The spore count in 5 mL is 3 × 10 5 Spores / mL Phanerochaete chrysosporium The spore suspension of (USA NDM3-2) was inoculated into a 250 mL conical flask containing 100 mL of sterilized potato extract powder-glucose medium and cultured at 35°C and 180 rpm for 4 days to form mycelium.

[0047] The mycelium washed with deionized water was first placed in a -10--20℃ refrigerator for pre-freezing for 4 hours, and then dried in a vacuum freeze dryer at -45--50℃ for 36 hours.

[0048] The freeze-dried sample was placed in a tube furnace, heated to 700 °C at a rate of 5 °C / min in a N2 atmosphere and kept at this temperature for 3 h to prepare the precursor carbon material-I.

[0049] The obtained precursor carbon material-I was mixed with KOH powder at a mass ratio of 1:5, and then ground in an agate mortar for 30 minutes. The mixture was placed in a tube furnace, heated to 900°C at a rate of 10°C / min in a N2 atmosphere and kept warm for 3 hours to obtain the precursor carbon material-II.

[0050] After the precursor carbon material-II was naturally cooled to room temperature, it was soaked in a 3 mol / L sulfuric acid solution for 30 min. The acidified biochar was washed with deionized water to pH = 7, and dried in an oven at 80°C for 30 h to obtain the precursor carbon material-III.

[0051] The precursor carbon material-III, carbon black and PVDF obtained in step (6) are mixed in a mass ratio of 9:1:1 to form a slurry, and then the slurry is coated on a copper current collector, vacuum dried at 80° C. for 24 hours, and then punched by a punching machine to obtain an electrode sheet.

[0052] Characterization of the electrochemical performance of batteries The electrochemical performance of the prepared battery was characterized from the perspectives of resistance, conductivity and theoretical specific capacity: BET analysis of the prepared precursor carbon material-III showed that the specific surface area was 2447 m 2 / g, with an average pore size of 5nm. SEM analysis shows that after KOH activation, the pore structure and defect sites of the fungus-derived carbon material are significantly increased. The present invention also measures the electrochemical performance of the LIB prepared with fungal mycelium-based carbon material as the negative electrode, and its resistance, conductivity and theoretical specific capacity are 68.99Ω, 2.31S / cm and 389.56mAh / g, respectively.

Claims

1. A method for preparing a fungal mycelium-based electrode material, characterized in that: The specific steps are as follows: (1) Preparation of fungal mycelium Phanerochaete chrysosporium Phanerochaete chrysosporium ) inoculating the spore suspension into a conical flask filled with sterilized potato extract powder-glucose medium, and shaking and culturing in a shaker to form mycelium; (2) Freeze-drying of fungal mycelium The mycelium was washed with deionized water and then pre-frozen in a refrigerator, and then dried using a vacuum freeze dryer; (3) Preparation of precursor carbon material-I The freeze-dried sample was placed in a tube furnace, heated to 500-700°C at a rate of 3-5°C / min in an inert atmosphere and kept at this temperature for 1-3 h to obtain a precursor carbon material-I; (4) Preparation of precursor carbon material-II Precursor carbon material-I and KOH powder are mixed in a certain mass ratio, and then ground in an agate mortar for 10-30 minutes; the ground activated mixture is placed in a tube furnace, heated to 700-900°C at a rate of 5-10°C / min in an inert atmosphere and kept warm for 1-3 hours to obtain precursor carbon material-II; (5) Preparation of precursor carbon material-III The precursor carbon material-II is acidified, washed with water and dried in sequence to obtain the precursor carbon material-III; (6) Preparation of electrode materials First, the precursor carbon material-III, the conductive agent carbon black, and the binder polyvinylidene fluoride PVDF are mixed in a certain mass ratio to form a slurry, and then the slurry is coated on a copper current collector and vacuum dried, and finally the electrode sheet is punched out.

2. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (1), the spore count of the spore suspension is 1×10 5 -3×10 5 spores / mL, the amount of spore suspension added is 1-5mL, and the volume of potato powder-glucose medium is 100mL; the components of the potato-glucose medium include: 100-150g / L potato powder and 5-15g / L glucose, and the pH value of the medium is adjusted to 4.50-5.50 with sulfuric acid solution; the culture temperature of the fungus is 25-35°C, the shaking speed is 120-180rpm, and the culture time is 2-4 days.

3. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (2), the mixture is placed in a refrigerator for pre-freezing for 2-4 hours, and then dried in a vacuum freeze dryer for 24-36 hours.

4. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (3) and step (4), the inert atmosphere is a nitrogen atmosphere.

5. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (4), the precursor carbon material-I and KOH powder are mixed in a mass ratio of 1:3 to 1:

5.

6. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (5), the precursor carbon material-II after acidification is soaked in a 1-3 mol / L sulfuric acid solution for 10-30 min, washed with deionized water until neutral, and dried in an oven at 50-80° C. for 10-30 h.

7. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (5), the BET specific surface area of ​​the precursor carbon material-III is 2000-3000m 2 / g, and the average pore size is 2-5nm.

8. The method for preparing a fungal mycelium-based electrode material according to claim 1, characterized in that: In step (6), the mass ratio of the precursor carbon material-III to the conductive agent carbon black and the binder PVDF is 7:1:1-9:1:

1.

9. A fungal mycelium-based electrode material prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the fungal mycelium-based electrode material according to claim 9 as a negative electrode material for lithium-ion batteries in assembling lithium-ion batteries.

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