Preparation method of graphene modified mushroom mycelium lithium battery separator
The preparation of graphene-modified mushroom mycelium lithium battery separator solves the problems of non-degradability, poor thermal stability and insufficient electrolyte wettability of existing lithium battery separators, and improves the safety and performance of lithium batteries, especially the battery performance in low-temperature environments.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YANTAI LIHUA ELECTRIC POWER TECHNOLOGY CO LTD
- Filing Date
- 2025-08-28
- Publication Date
- 2026-06-26
AI Technical Summary
Existing lithium battery separators suffer from problems such as non-degradability, insufficient thermal stability, poor electrolyte wettability, and insufficient adaptability to new electrode systems, which limits the improvement of battery safety and performance.
By using graphene-modified mushroom mycelium material, a graphene-modified mushroom mycelium lithium battery separator was prepared. Utilizing the high conductivity of graphene and the porous structure of mushroom mycelium, combined with cellulose derivatives and cross-linking agents, a synergistic three-dimensional network structure was formed, improving the mechanical properties and conductivity of the separator. Furthermore, the biodegradability of mushroom mycelium addresses environmental issues.
It achieves high mechanical stability, good conductivity and biodegradability of the separator, improves electrolyte wettability, and enhances the safety and performance of lithium batteries, especially with a significant improvement in ion conductivity at low temperatures.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a lithium battery separator, and more particularly to a method for preparing a graphene-modified mushroom mycelium lithium battery separator. Background Technology
[0002] In the current era of rapid development in the new energy industry, lithium battery separators, as the "safety guardians" of battery systems, have seen their performance defects become a key bottleneck restricting industry development. While the current mainstream polyolefin separators dominate the market due to their cost advantage, their non-degradable nature creates a sharp contradiction with increasingly stringent environmental requirements: approximately 500,000 tons of waste separators are generated globally each year, and traditional landfill disposal methods are no longer sustainable. Regarding thermal stability, polyolefin separators undergo irreversible shrinkage at around 130℃, leading to a sharp increase in the risk of internal short circuits in the battery. According to industry statistics, nearly 30% of battery safety accidents originate from separator thermal failure. Insufficient electrolyte wettability directly leads to increased battery internal resistance. Actual measurements show that the ionic conductivity of unmodified separators decreases by more than 40% at low temperatures, severely impacting the range performance of electric vehicles in cold regions. Furthermore, existing separators lack compatibility with new electrode systems such as high-nickel ternary and silicon-based anodes, becoming a major obstacle to improving battery energy density. These technical pain points are driving the industry to accelerate the research and development of innovative solutions such as ceramic composite coatings and bio-based biodegradable materials. Summary of the Invention
[0003] In order to overcome the shortcomings of the existing technology, the present invention provides a method for preparing a graphene-modified mushroom mycelium lithium battery separator.
[0004] To achieve the above objectives, this invention discloses a method for preparing a graphene-modified mushroom mycelium lithium battery separator, comprising the following steps:
[0005] (S1) Raw material ratio: 50-85 parts mushroom mycelium, 1-8 parts graphene, 5-15 parts cellulose derivative, 3-10 parts water-soluble polymer, 1-5 parts crosslinking agent;
[0006] (S2) Purification of mushroom mycelium: Mycelium powder was prepared by pretreatment of mushroom mycelium. The mycelium powder was added to an alkaline solution with a mass fraction of 2-6%, stirred, filtered, and washed until neutral to obtain purified mycelium powder.
[0007] (S3) Preparation of graphene dispersion: Add graphene to deionized water or alcohol solvent and disperse to obtain a graphene dispersion with a concentration of 0.1-2 mg / mL; the amount of deionized water or alcohol solvent is 150-300 parts.
[0008] (S4) Mixing: Add the purified mycelium powder, cellulose derivative, and water-soluble polymer to the graphene dispersion, and introduce inert gas to stir evenly to form a mixture;
[0009] (S5) Crosslinking treatment: Add crosslinking agent to the above solution and stir to complete the crosslinking reaction.
[0010] (S6) Molding and drying: The cross-linked mixture is used to prepare a film by casting, scraping or dip coating. The film is cast or scraped onto any of the substrates of stainless steel plate, glass plate or polytetrafluoroethylene plate. For dip coating, non-woven fabric or porous film is used as the substrate. After drying, the substrate is peeled off to form a graphene modified mushroom mycelium lithium battery separator.
[0011] Preferably, the mushroom mycelium is one or more of the mycelium of oyster mushroom, shiitake mushroom, enoki mushroom, and king oyster mushroom; the pretreatment method of the mushroom mycelium is as follows: take fresh mushroom mycelium, wash and dry it, and then crush the dried mushroom mycelium to obtain mycelium powder.
[0012] Preferably, the alkaline solution is a sodium hydroxide, potassium hydroxide, or sodium carbonate solution, wherein the liquid-to-solid ratio is 10:1-30:1 (ml / g).
[0013] Preferably, the graphene is one or more of graphene oxide, reduced graphene oxide, and graphene nanosheets, with a sheet diameter of 0.5-10 μm.
[0014] Preferably, the cellulose derivative is one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose.
[0015] Preferably, the water-soluble polymer is one or more of polyvinyl alcohol, polyethylene glycol, and polyacrylamide.
[0016] Preferably, the crosslinking agent is one or more of boric acid, glutaraldehyde, citric acid, and epichlorohydrin.
[0017] Preferably, in step (S3), the alcohol solvent is one or more of methanol, ethanol, or propanol; the dispersion treatment method is any one of ultrasonic dispersion, mechanical stirring dispersion, or high-pressure homogenization dispersion; a dispersant may be added during the dispersion process, and the amount of dispersant is 0.5-5% of the graphene mass; the dispersant is any one of sodium dodecyl sulfate or Tween 80.
[0018] Preferably, in step (S5), the crosslinking agent can be added at once or in multiple portions, with each portion being 20-50% of the total amount.
[0019] Preferably, in step (S6), the film thickness is controlled to be 10-50 μm, and the film is treated by vacuum drying, hot air drying or freeze drying. The vacuum drying conditions are 30-70℃ and 0.05-0.1MPa for 6-24 hours, the hot air drying conditions are 40-90℃ for 4-10 hours, and the freeze drying conditions are -40 to -10℃ for 24-48 hours.
[0020] The present invention has the following technical effects:
[0021] 1. Excellent mechanical properties and good electrical conductivity: Graphene and mushroom mycelium work synergistically. The three-dimensional network structure formed by graphene nanoribbons enhances the mechanical stability of the membrane, preventing mycelium breakage during charging and discharging. Simultaneously, graphene's high conductivity serves as an efficient electron transport channel, compensating for the poor conductivity of the mycelium itself. According to testing, the tensile strength can reach 25-30 MPa, and the electrical conductivity is increased to 1.5-2 S / m.
[0022] 2. Good biodegradability: Mushroom mycelium is mainly composed of natural macromolecules such as chitin and β-glucan. These substances are easily decomposed into water, carbon dioxide and organic matter by microbial enzymes in the natural environment. The naturally formed three-dimensional porous structure of the mycelium provides attachment sites for microorganisms. When combined with graphene, the oxygen-containing functional groups of graphene oxide can promote hydrolysis.
[0023] 3. Good electrolyte wettability: The porous structure of mushroom mycelium combined with the hydrophilicity of sodium carboxymethyl cellulose results in an electrolyte absorption rate of over 320% and an ionic conductivity of 3.0 × 10⁻³ s / cm. Detailed Implementation
[0024] The principles and features of the present invention are described below with reference to embodiments; the examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.
[0025] Example 1
[0026] A method for preparing a graphene-modified mushroom mycelium lithium battery separator includes the following steps:
[0027] (S1) Raw material ratio: 60 parts of oyster mushroom mycelium, 3 parts of graphene oxide (2μm in diameter), 8 parts of sodium carboxymethyl cellulose, 5 parts of polyvinyl alcohol, and 2 parts of boric acid.
[0028] (S2) Purification of mushroom mycelium: Take fresh oyster mushroom mycelium, wash it and dry it with hot air at 60℃ for 8 hours; pulverize the dried mycelium through a 100-mesh sieve to obtain mycelium powder; add the powder to a 4% sodium hydroxide solution, with the liquid-solid ratio of the alkaline solution to the mycelium powder being 20:1 (mL / g), stir at 50℃ for 2 hours, filter and wash until neutral to obtain purified mycelium powder.
[0029] (S3) Preparation of graphene dispersion: Add graphene oxide to 200 parts of deionized water and disperse it by ultrasonication for 30 minutes to obtain a graphene dispersion with a concentration of 1 mg / mL. Add sodium dodecyl sulfate at 2% of the mass of graphene oxide as a dispersant.
[0030] (S4) Mixing: Add purified mycelium powder, sodium carboxymethyl cellulose and polyvinyl alcohol to graphene dispersion and stir at 70°C for 2 hours to form a uniform mixture; nitrogen gas is introduced during stirring to prevent oxidation.
[0031] (S5) Crosslinking treatment: Add boric acid to the mixture all at once and stir at 50°C for 1.5 hours to complete the crosslinking reaction.
[0032] (S6) Molding and drying: The cross-linked mixture is cast onto a glass plate to prepare a thin film with a thickness of 20 μm. The film is dried at 50 °C and 0.08 MPa for 12 hours using a vacuum drying method. After drying, the glass plate is peeled off to obtain a graphene-modified mushroom mycelium lithium battery separator.
[0033] Example 2
[0034] A method for preparing a graphene-modified mushroom mycelium lithium battery separator includes the following steps:
[0035] (S1) Raw material ratio: 70 parts of mixed mycelium of shiitake mushrooms and enoki mushrooms (weight ratio 1:1), 5 parts of reduced graphene oxide (sheet diameter 5μm), 12 parts of hydroxyethyl cellulose, 7 parts of polyethylene glycol, 3 parts of glutaraldehyde, and 250 parts of deionized water.
[0036] (S2) Purification of mushroom mycelium: Fresh shiitake and enoki mushroom mycelium were taken, washed, and freeze-dried at -20℃ for 48 hours; the dried mycelium was crushed and passed through a 120-mesh sieve to obtain mycelium powder; the powder was added to a 5% potassium hydroxide solution, with the liquid-solid ratio of the alkaline solution to the mycelium powder being 25:1 (mL / g), stirred at 60℃ for 2.5 hours, filtered, and washed until neutral to obtain purified mycelium powder.
[0037] (S3) Preparation of graphene dispersion: Reduced graphene oxide was added to ethanol and treated for 40 minutes by a combination of mechanical stirring and ultrasonic dispersion to obtain a graphene dispersion with a concentration of 1.5 mg / mL. Tween 80 was added as a dispersant at 3% by mass of reduced graphene oxide.
[0038] (S4) Mixing: Reduced graphene oxide was added to ethanol and treated for 40 minutes by a combination of mechanical stirring and ultrasonic dispersion to obtain a graphene dispersion with a concentration of 1.5 mg / mL. Tween 80 was added as a dispersant at 3% by mass of the reduced graphene oxide.
[0039] (S5) Crosslinking treatment: Add glutaraldehyde to the mixture in two portions, each time adding 50% of the total amount. Stir at 60°C for 2 hours to complete the crosslinking reaction.
[0040] (S6) Molding and drying: The cross-linked mixture is coated onto a stainless steel plate to form a thin film with a thickness of 30 μm. The film is dried at 70°C for 6 hours using hot air drying. After drying, the stainless steel plate is peeled off to obtain a graphene-modified mushroom mycelium lithium battery separator.
[0041] Example 3
[0042] A method for preparing a graphene-modified mushroom mycelium lithium battery separator includes the following steps:
[0043] (S1) Raw material ratio: 80 parts of king oyster mushroom mycelium, 7 parts of graphene nanosheets (8μm in diameter), 10 parts of methylcellulose, 9 parts of polyacrylamide, 4 parts of citric acid, and 280 parts of deionized water.
[0044] (S2) Purification of mushroom mycelium: Take fresh king oyster mushroom mycelium, wash it and dry it with hot air at 70℃ for 7 hours; pulverize the dried mycelium through a 140-mesh sieve to obtain mycelium powder; add the powder to a 6% sodium carbonate solution, with the liquid-solid ratio of the alkaline solution to the mycelium powder being 30:1 (mL / g), stir at 70℃ for 3 hours, filter and wash until neutral to obtain purified mycelium powder.
[0045] (S3) Preparation of graphene dispersion: Add graphene nanosheets to deionized water and perform high-pressure homogenization dispersion for 50 minutes to obtain a graphene dispersion with a concentration of 2 mg / mL. Add sodium dodecyl sulfate and Tween 80 (weight ratio 1:1) mixed dispersant, which accounts for 5% of the mass of graphene nanosheets.
[0046] (S4) Mixing: Add purified mycelium powder, methylcellulose and polyacrylamide to graphene dispersion and stir at 90°C for 4 hours to form a uniform mixture; nitrogen gas is introduced for protection during stirring.
[0047] (S5) Crosslinking treatment: Add glutaraldehyde to the mixture in two portions, each time adding 50% of the total amount. Stir at 60°C for 2 hours to complete the crosslinking reaction.
[0048] (S6) Molding and drying: The cross-linked mixture is dip-coated onto a non-woven fabric substrate to prepare a film with a thickness of 40 μm; the film is then freeze-dried at -30°C for 36 hours; after drying, the non-woven fabric is peeled off to obtain a graphene-modified mushroom mycelium lithium battery separator.
[0049] For the diaphragms obtained in Examples 1 to 3 above, their thickness, air permeability, puncture strength, tensile strength and heat shrinkage rate were tested. The test methods were carried out in accordance with the national standard GB / T 36363-2018. The test results are shown in Table 1.
[0050] Specifically:
[0051] (1) Thickness test: Use a thickness gauge with a resolution of ≤0.1μm. Take ≥3 points at equal intervals in the horizontal direction as a group, and take 1 group every 200mm in the vertical direction for a total of 5 groups. Calculate the average value and deviation.
[0052] (2) Air permeability test: Take 3 samples at 150mm intervals along the longitudinal direction of the sample (100mm×100mm if the width is ≥100mm, otherwise 100mm×width), test with an air permeability meter, and take the average value of 3 times.
[0053] (3) Puncture strength test: Using a puncture strength tester (load sensor resolution 0.01N, puncture needle Φ1.0mm, tip R0.5mm, clamp inner diameter 10mm), puncture at a rate of (100±10) mm / min, measure the average thickness of 4 points around the needle hole, and calculate the puncture strength F=F0 / DF as the puncture strength (N / μm), where F0 is the force (N) measured when the diaphragm is punctured, and d is the average thickness of the diaphragm (μm).
[0054] (4) Tensile strength test:
[0055] Referring to GB / T 36363-2018, use a type 2 specimen with a width of 15±0.1mm, an initial clamping distance of 100±5mm, and a test rate of 250±10mm / min, stretching until fracture, and record the tensile strength.
[0056] (5) Heat shrinkage rate test:
[0057] Take three 100mm×100mm samples (if the width is less than 100mm, then take 100mm×width), treat them at (90±1)℃ / 2h or (120±1)℃ / 1h, measure the longitudinal and transverse lengths before and after heating, calculate the shrinkage rate and take the average value.
[0058] Comparative Example 1
[0059] Comparative Example 1 is a commercially available single-phase dry-stretched 18μm PP base film + 2μm ceramic diaphragm, and its measurement data are shown in the table.
[0060] Table 1 Performance test results in the embodiments
[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A method for preparing a graphene-modified mushroom mycelium lithium battery separator, characterized in that, Includes the following steps: (S1) Raw material ratio: 50-85 parts mushroom mycelium, 1-8 parts graphene, 5-15 parts cellulose derivative, 3-10 parts water-soluble polymer, 1-5 parts crosslinking agent; (S2) Purification of mushroom mycelium: Mycelium powder was prepared by pretreatment of mushroom mycelium. The mycelium powder was added to an alkaline solution with a mass fraction of 2-6%, stirred, filtered, and washed until neutral to obtain purified mycelium powder. (S3) Preparation of graphene dispersion: Add graphene to deionized water or alcohol solvent and disperse to obtain a graphene dispersion with a concentration of 0.1-2 mg / mL; the amount of deionized water or alcohol solvent is 150-300 parts. (S4) Mixing: Add the purified mycelium powder, cellulose derivative, and water-soluble polymer to the graphene dispersion, and introduce inert gas to stir evenly to form a mixture; (S5) Crosslinking treatment: Add crosslinking agent to the above solution and stir to complete the crosslinking reaction; (S6) Molding and drying: The cross-linked mixture is used to prepare a film by casting, scraping or dip coating. The film is cast or scraped onto any of the substrates of stainless steel plate, glass plate or polytetrafluoroethylene plate. For dip coating, non-woven fabric or porous film is used as the substrate. After drying, the substrate is peeled off to form a graphene modified mushroom mycelium lithium battery separator.
2. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The mushroom mycelium is one or more of the mycelium of oyster mushroom, shiitake mushroom, enoki mushroom, and king oyster mushroom; the pretreatment method of the mushroom mycelium is as follows: take fresh mushroom mycelium, wash and dry it, and then crush the dried mushroom mycelium to obtain mycelium powder.
3. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The alkaline solution is a sodium hydroxide, potassium hydroxide, or sodium carbonate solution, wherein the liquid-to-solid ratio is 10:1-30:1 (ml / g).
4. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The graphene is one or more of graphene oxide, reduced graphene oxide, and graphene nanosheets, with a sheet diameter of 0.5-10 μm.
5. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The cellulose derivative is one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and methyl cellulose.
6. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The water-soluble polymer is one or more of polyvinyl alcohol, polyethylene glycol, and polyacrylamide.
7. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, The crosslinking agent is one or more of boric acid, glutaraldehyde, citric acid, and epichlorohydrin.
8. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, In step (S3), the alcohol solvent is one or more of methanol, ethanol or propanol; the dispersion treatment method is any one of ultrasonic dispersion, mechanical stirring dispersion or high pressure homogenization dispersion; a dispersant may be added during the dispersion process, and the amount of dispersant is 0.5-5% of the mass of graphene; the dispersant is any one of sodium dodecyl sulfate or Tween 80.
9. The method for preparing the graphene-modified mushroom mycelium lithium battery separator according to claim 1, characterized in that, In step (S5), the crosslinking agent can be added all at once or in multiple portions. When added in multiple portions, the amount added each time is 20-50% of the total amount.