CN115000623A - Composite lithium battery diaphragm and preparation method thereof - Google Patents
Composite lithium battery diaphragm and preparation method thereof Download PDFInfo
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- CN115000623A CN115000623A CN202210885001.3A CN202210885001A CN115000623A CN 115000623 A CN115000623 A CN 115000623A CN 202210885001 A CN202210885001 A CN 202210885001A CN 115000623 A CN115000623 A CN 115000623A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a composite lithium battery diaphragm and a preparation method thereof. And adding POSS grafted with polyethylene glycol into the polymethyl methacrylate solution to obtain the modified polymethyl methacrylate solution. And then soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution to modify the polyethylene diaphragm, and forming a uniform alumina coating layer on the modified polyethylene diaphragm by using an atomic layer deposition technology, so that the prepared composite lithium battery diaphragm has good wettability to electrolyte and heat resistance, and meanwhile, the thickness of the composite film is thinner, thereby being beneficial to the light weight of the battery.
Description
Technical Field
The invention relates to the technical field of diaphragms, in particular to a composite lithium battery diaphragm and a preparation method thereof.
Background
The polyolefin diaphragm has the advantages of good puncture resistance, chemical resistance and the like, and has higher porosity and lower internal resistance. Technicians commonly use polyolefin microporous membranes as lithium battery separators to separate the positive and negative electrodes. For example, polyethylene separator PE, polypropylene separator PP.
However, the polyolefin separator can shrink under high temperature conditions, and when the polyolefin separator is applied to the field of battery separators, the risk of battery short circuit can be increased. In addition, the polyolefin diaphragm has low surface energy, strong hydrophobicity and poor wettability to electrolyte, thereby affecting the charge-discharge and cycle characteristics of the battery.
In the prior art, industrial polyolefin separators are often modified to improve wettability and heat resistance of the separators. For example, inorganic ceramics, e.g. Al, on polyolefin separators 2 O 3 、SiO 2 、MgO、ZrO 2 And TiO 2 The coating is made to improve the thermal shrinkage performance of the separator and the wettability of the electrolyte. However, when the inorganic ceramic coating is coated, the thickness of the diaphragm is increased more, which does not meet the requirement of thinning the diaphragm, and the inorganic ceramic coating is hard, which easily causes the coating to fall off and affects the service performance.
In order to solve the above problems, the present invention provides a composite lithium battery separator and a method for preparing the same.
Disclosure of Invention
The invention aims to provide a composite lithium battery diaphragm and a preparation method thereof, which aim to solve the problems in the background technology.
In order to solve the technical problems, the invention provides the following technical scheme:
a preparation method of a composite lithium battery diaphragm comprises the following steps:
the method comprises the following steps: soaking the polyethylene diaphragm in a polymethyl methacrylate solution for 50-70s, taking out, draining, and drying at 45-55 ℃ for 22-24h to obtain a modified polyethylene diaphragm;
step two: and (2) placing the modified polyethylene diaphragm on an atomic layer deposition instrument, vacuumizing and heating at 50-60 ℃, introducing trimethylaluminum, introducing inert gas nitrogen for purging for 20-30s, introducing water vapor, introducing inert gas nitrogen for purging for 40-50s, and repeating the steps for 45-50 cycles to obtain the composite lithium battery diaphragm.
Preferably, in the third step, the concentration of the polymethyl methacrylate solution is 0.1 wt% to 5 wt%.
Preferably, the thickness of the composite lithium battery diaphragm is 12-15 μm.
Preferably, the polymethyl methacrylate is modified polymethyl methacrylate, and the preparation method comprises the following steps: taking methyl methacrylate and POSS grafted with polyethylene glycol, stirring for 30-40min, dropwise adding chloroplatinic acid catalyst, reacting for 2-3h at 76-82 ℃, cooling to 25-27 ℃, continuously heating to 86-90 ℃, and reacting for 1-2h to obtain the modified polymethyl methacrylate.
Preferably, the preparation method of the POSS grafted with the polyethylene glycol comprises the following steps: taking modified polyethylene glycol and deionized water, stirring for 30-40min, adding modified POSS, stirring for 18-20h at 60-70 ℃, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
Preferably, the preparation method of the modified polyethylene glycol comprises the following steps: uniformly stirring polyethylene glycol, triphenylphosphine, phthalimide and tetrahydrofuran, reacting at-2-2 ℃ for 50-70min, continuing to react at 25-27 ℃ for 10-14h, performing chromatography to obtain a solution, adding ethanol and hydrazine hydrate, reacting for 1-2h, extracting, and drying to obtain the modified polyethylene glycol.
Preferably, the preparation method of the modified POSS comprises the following steps: the method comprises the following steps:
s1: uniformly stirring vinyl triethoxysilane and acetone, dropwise adding hydrochloric acid, heating to 36-42 ℃, reacting for 44-50h, performing suction filtration, washing, adding acetone and dichloromethane for recrystallization, performing suction filtration, and drying to obtain POSS;
s2: stirring POSS, chloroform, glacial acetic acid and concentrated sulfuric acid at 66-72 ℃ for 1-2h, dropwise adding hydrogen peroxide, condensing and refluxing for 5-7h, adding sodium carbonate, reacting for 10-15min, washing, filtering and drying to obtain the modified POSS.
Preferably, the mass ratio of the modified polyethylene glycol to the modified POSS is (5-7): 1.
compared with the prior art, the invention has the following beneficial effects:
(1) the modified polyethylene glycol is prepared from polyethylene glycol and phthalimide, and has amino groups, so that the hydrophilicity of the polyethylene glycol is improved, and the wettability of the polyethylene diaphragm to the electrolyte is improved.
Glacial acetic acid and hydrogen peroxide are used to generate peracetic acid, and the peracetic acid converts vinyl groups of the POSS into epoxy groups to generate modified POSS with epoxy groups.
The epoxy group of the modified POSS reacts with the amino group of the modified polyethylene glycol, so that the stability of the POSS grafted with the polyethylene glycol in the polymethyl methacrylate solution is enhanced, more modified POSS and modified polyethylene glycol can be adhered to the polyethylene diaphragm, and the performance of the composite diaphragm is improved. The mass ratio of the modified polyethylene glycol to the modified POSS is controlled to be (5-7): 1, the composite lithium battery diaphragm has the best hydrophilic effect, the thermal shrinkage rate can reach 0.3%, and the composite lithium battery diaphragm has good heat resistance.
(2) The atomic layer deposition technology can plate substances on a substrate material in the form of a monoatomic film, and deposit aluminum oxide on the surface of the polyethylene diaphragm. The unmodified polyethylene diaphragm surface is lack of reactive groups, so that the consumption of trimethyl aluminum as a precursor is high, the growth rate is low, and the thickness of the film is increased more. According to the invention, the surface of the polyethylene diaphragm is soaked and coated with the modified polymethyl methacrylate coating layer, so that the atomic layer reaction deposition is effectively prevented from being directly carried out on the surface of the polyethylene diaphragm. The modified polymethyl methacrylate has strong van der Waals force, and can more easily and uniformly adsorb trimethyl aluminum to deposit on the surface of the fiber for growth, so that a uniform aluminum oxide coating layer is formed on the polyethylene diaphragm.
Compared with the method for directly performing atomic layer deposition on the surface of the polyethylene diaphragm, the thermal shrinkage performance of the composite film can be improved under the condition of using less precursor trimethyl aluminum, and meanwhile, the thickness of the composite film is thinner. The thickness of the coating of the composite film can be accurately controlled, the wettability of the diaphragm is improved, the reduction of the internal resistance of the battery is facilitated, the performance of the battery is improved, the heat shrinkage performance of the composite film can be improved under the condition that fewer precursors are used, and meanwhile, the thickness of the composite film is thinner, and the light weight of the battery is facilitated.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The trimethyl aluminum in the embodiment of the invention is purchased from Shanghai nation chemical industry Co., Ltd;
polyethylene glycol (PEG-600) was purchased from Wuhan Yaozhou chemicals, Inc.;
triphenylphosphine was purchased from Shanghai Bangheng chemical industry Co., Ltd;
phthalimide was purchased from Shanghai nation chemical Co., Ltd;
vinyltriethoxysilane is available from Shanghai Ji to Biochemical technology, Inc.;
methyl methacrylate is available from Shanghai Pont chemical industries, Inc.
Example 1
Polymethyl methacrylate and acetone are taken to prepare a polymethyl methacrylate solution with the concentration of 0.5 weight percent.
And soaking the polyethylene diaphragm in a polymethyl methacrylate solution with the concentration of 0.5 wt% for 50s, taking out, draining the polymethyl methacrylate solution remained on the surface, and drying at 50 ℃ for 23h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 55 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 25s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; inert gas nitrogen was introduced for purging 45 s. And repeating the steps for 50 cycles to obtain the composite lithium battery diaphragm.
Example 2
Polymethyl methacrylate and acetone are taken to prepare a polymethyl methacrylate solution with the concentration of 1 wt%.
And soaking the polyethylene diaphragm in a polymethyl methacrylate solution with the concentration of 1 wt% for 70s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying at 45 ℃ for 22h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 50 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 30s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 50 s. And repeating the steps for 48 cycles to obtain the composite lithium battery diaphragm.
Example 3
Polymethyl methacrylate and acetone are taken to prepare a polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out and draining the polymethyl methacrylate solution remained on the surface, and drying at 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity to perform a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Example 4
Preparing polymethyl methacrylate solution with the concentration of 5 wt% by taking polymethyl methacrylate and acetone.
And soaking the polyethylene diaphragm in a polymethyl methacrylate solution with the concentration of 5 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying the solution at the temperature of 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Example 5: the same modified polymethyl methacrylate solution as in example 3 was used.
The method comprises the following steps: preparing modified polyethylene glycol:
taking 12g of polyethylene glycol (PEG-600), 10g of triphenylphosphine, 8g of phthalimide and 100mL of tetrahydrofuran, uniformly stirring, reacting at 0 ℃ for 60min, continuing to react at 26 ℃ for 12h, performing chromatography to obtain a solution, adding 100mL of ethanol and 5mL of hydrazine hydrate, reacting for 1.5h, extracting, and drying to obtain the modified polyethylene glycol.
Step two: preparation of modified POSS:
2g of vinyltriethoxysilane and 25g of acetone are taken, uniformly stirred, 10g of hydrochloric acid of 5mol/L is dripped, the temperature is raised to 39 ℃, reaction is carried out for 47 hours, suction filtration and washing are carried out, 30mL of acetone and 10mL of dichloromethane are added for recrystallization, suction filtration and drying are carried out, and POSS is obtained.
And (3) stirring 3g of POSS, 60mL of chloroform, 30mL of glacial acetic acid and 3mL of concentrated sulfuric acid at 69 ℃ for 1.5h, dropwise adding 100mL of hydrogen peroxide, carrying out condensation reflux for 6h, adding 20mL of sodium carbonate, reacting for 13min, washing, filtering and drying to obtain the modified POSS.
Step three: preparation of POSS grafted with polyethylene glycol:
and (3) taking 12g of modified polyethylene glycol and 100mL of deionized water, stirring for 35min, adding 2g of modified POSS, stirring for 19h at 65 ℃, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
The mass ratio of the modified polyethylene glycol to the modified POSS is 6: 1.
step four: preparation of modified polymethyl methacrylate:
taking 100g of methyl methacrylate and 10g of POSS grafted with polyethylene glycol, stirring for 35min, dropwise adding 0.3g of chloroplatinic acid catalyst, reacting for 2.5h at 79 ℃, cooling to 26 ℃, continuously heating to 88 ℃, and reacting for 1.5h to obtain the modified polymethyl methacrylate.
Step five: preparing a modified polyethylene diaphragm:
taking modified polymethyl methacrylate and acetone to prepare a modified polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying the solution at the temperature of 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Example 6: the same modified polymethyl methacrylate solution as in example 3 was used.
The method comprises the following steps: preparing modified polyethylene glycol:
taking 12g of polyethylene glycol (PEG-600), 10g of triphenylphosphine, 8g of phthalimide and 100mL of tetrahydrofuran, uniformly stirring, reacting at-2 ℃ for 50min, continuing to react at 25 ℃ for 10h, performing chromatography to obtain a solution, adding 100mL of ethanol and 5mL of hydrazine hydrate, reacting for 1h, extracting, and drying to obtain the modified polyethylene glycol.
Step two: preparation of modified POSS:
2g of vinyltriethoxysilane and 25g of acetone are taken, uniformly stirred, 10g of hydrochloric acid of 5mol/L is dripped, the temperature is raised to 36 ℃, reaction is carried out for 44 hours, suction filtration and washing are carried out, 30mL of acetone and 10mL of dichloromethane are added for recrystallization, suction filtration and drying are carried out, and POSS is obtained.
And (3) stirring 3g of POSS, 60mL of chloroform, 30mL of glacial acetic acid and 3mL of concentrated sulfuric acid at 66 ℃ for 1h, dropwise adding 100mL of hydrogen peroxide, carrying out condensation reflux for 5h, adding 20mL of sodium carbonate, reacting for 10min, washing, filtering and drying to obtain the modified POSS.
Step three: preparation of POSS grafted with polyethylene glycol:
and (3) taking 10g of modified polyethylene glycol and 100mL of deionized water, stirring for 30min, adding 2g of modified POSS, stirring for 18h at 60 ℃, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
The mass ratio of the modified polyethylene glycol to the modified POSS is 5: 1.
step four: preparation of modified polymethyl methacrylate:
taking 100g of methyl methacrylate and 10g of POSS grafted with polyethylene glycol, stirring for 30min, dropwise adding 0.3g of chloroplatinic acid catalyst, reacting for 2h at 76 ℃, cooling to 25 ℃, continuously heating to 86 ℃, and reacting for 1h to obtain the modified polymethyl methacrylate.
Step five: preparing a modified polyethylene diaphragm:
taking modified polymethyl methacrylate and acetone to prepare a modified polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying at 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Example 7: the same modified polymethyl methacrylate solution as in example 3 was used.
The method comprises the following steps: preparing modified polyethylene glycol:
taking 12g of polyethylene glycol (PEG-600), 10g of triphenylphosphine, 8g of phthalimide and 100mL of tetrahydrofuran, uniformly stirring, reacting at 2 ℃ for 70min, continuing to react at 27 ℃ for 14h, performing chromatography to obtain a solution, adding 100mL of ethanol and 5mL of hydrazine hydrate, reacting for 2h, extracting, and drying to obtain the modified polyethylene glycol.
Step two: preparation of modified POSS:
2g of vinyltriethoxysilane and 25g of acetone are taken, uniformly stirred, 10g of hydrochloric acid of 5mol/L is dripped, the temperature is raised to 42 ℃, the reaction is carried out for 50 hours, the mixture is filtered, washed, added with 30mL of acetone and 10mL of dichloromethane for recrystallization, filtered and dried, and POSS is obtained.
And (3) stirring 3g of POSS, 60mL of chloroform, 30mL of glacial acetic acid and 3mL of concentrated sulfuric acid at 72 ℃ for 2h, dropwise adding 100mL of hydrogen peroxide, carrying out condensation reflux for 7h, adding 20mL of sodium carbonate, reacting for 15min, washing, filtering and drying to obtain the modified POSS.
Step three: preparation of POSS grafted with polyethylene glycol:
and (3) taking 14g of modified polyethylene glycol and 100mL of deionized water, stirring for 40min, adding 2g of modified POSS, stirring for 20h at 70 ℃, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
The mass ratio of the modified polyethylene glycol to the modified POSS is 7: 1.
step four: preparation of modified polymethyl methacrylate:
taking 100g of methyl methacrylate and 10g of POSS grafted with polyethylene glycol, stirring for 40min, dropwise adding 0.3g of chloroplatinic acid catalyst, reacting for 3h at 82 ℃, cooling to 27 ℃, continuously heating to 90 ℃, and reacting for 2h to obtain the modified polymethyl methacrylate.
Step five: preparing a modified polyethylene diaphragm:
taking modified polymethyl methacrylate and acetone to prepare a modified polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying the solution at the temperature of 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Comparative example 1: the polyethylene separator was not modified, and the rest was the same as in example 1.
Placing an unmodified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Comparative example 2: the polyethylene glycol was not modified, and the rest was the same as in example 4.
The method comprises the following steps: preparation of modified POSS:
2g of vinyltriethoxysilane and 25g of acetone are taken, uniformly stirred, 10g of hydrochloric acid of 5mol/L is dripped, the temperature is raised to 39 ℃, reaction is carried out for 47 hours, suction filtration and washing are carried out, 30mL of acetone and 10mL of dichloromethane are added for recrystallization, suction filtration and drying are carried out, and POSS is obtained.
And (3) stirring 3g of POSS, 60mL of chloroform, 30mL of glacial acetic acid and 3mL of concentrated sulfuric acid at 69 ℃ for 1.5h, dropwise adding 100mL of hydrogen peroxide, carrying out condensation reflux for 6h, adding 20mL of sodium carbonate, reacting for 13min, washing, filtering and drying to obtain the modified POSS.
Step two: preparation of POSS grafted with polyethylene glycol:
and (3) stirring 12g of polyethylene glycol and 100mL of deionized water for 35min, adding 2g of modified POSS, stirring at 65 ℃ for 19h, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
The mass ratio of the polyethylene glycol to the modified POSS is 6: 1.
step three: preparation of modified polymethyl methacrylate:
taking 100g of methyl methacrylate and 10g of POSS grafted with polyethylene glycol, stirring for 35min, dropwise adding 0.3g of chloroplatinic acid catalyst, reacting for 2.5h at 79 ℃, cooling to 26 ℃, continuously heating to 88 ℃, and reacting for 1.5h to obtain the modified polymethyl methacrylate.
Step four: preparing a modified polyethylene diaphragm:
taking modified polymethyl methacrylate and acetone to prepare a modified polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying the solution at the temperature of 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Comparative example 3: the polyethylene glycol grafted POSS was not prepared and the rest was the same as in example 4.
The method comprises the following steps: preparing modified polyethylene glycol:
taking 12g of polyethylene glycol (PEG-600), 10g of triphenylphosphine, 8g of phthalimide and 100mL of tetrahydrofuran, uniformly stirring, reacting at 0 ℃ for 60min, continuing to react at 26 ℃ for 12h, performing chromatography to obtain a solution, adding 100mL of ethanol and 5mL of hydrazine hydrate, reacting for 1.5h, extracting, and drying to obtain the modified polyethylene glycol.
Step two: preparation of modified POSS:
2g of vinyltriethoxysilane and 25g of acetone are taken, uniformly stirred, 10g of hydrochloric acid of 5mol/L is dripped, the temperature is raised to 39 ℃, reaction is carried out for 47 hours, suction filtration and washing are carried out, 30mL of acetone and 10mL of dichloromethane are added for recrystallization, suction filtration and drying are carried out, and POSS is obtained.
And (3) stirring 3g of POSS, 60mL of chloroform, 30mL of glacial acetic acid and 3mL of concentrated sulfuric acid at 69 ℃ for 1.5h, dropwise adding 100mL of hydrogen peroxide, carrying out condensation reflux for 6h, adding 20mL of sodium carbonate, reacting for 13min, washing, filtering and drying to obtain the modified POSS.
Step three: preparation of modified polymethyl methacrylate:
taking 100g of methyl methacrylate, 10g of modified polyethylene glycol and 2g of modified POSS, stirring for 40min, dropwise adding 0.3g of chloroplatinic acid catalyst, reacting for 2.5h at 79 ℃, cooling to 26 ℃, continuously heating to 88 ℃, and reacting for 1.5h to obtain the modified polymethyl methacrylate.
Step four: preparing a modified polyethylene diaphragm:
taking modified polymethyl methacrylate and acetone to prepare a modified polymethyl methacrylate solution with the concentration of 3 wt%.
And soaking the polyethylene diaphragm in a modified polymethyl methacrylate solution with the concentration of 3 wt% for 60s, taking out the solution, draining the residual polymethyl methacrylate solution on the surface, and drying at 55 ℃ for 24h to obtain the modified polyethylene diaphragm.
Placing the modified polyethylene diaphragm on an atomic layer deposition instrument, and vacuumizing and heating at 60 ℃; introducing a first reaction precursor trimethylaluminum for chemical adsorption; introducing inert gas nitrogen for purging for 20s to clean redundant precursors and reaction byproducts; introducing a second precursor vapor into the cavity, and performing a displacement reaction with the trimethylaluminum; purging with nitrogen as an inert gas for 40 s. And repeating the steps for 45 cycles to obtain the composite lithium battery diaphragm.
Comparative example 4: the mass ratio of the modified polyethylene glycol to the modified POSS is 3: 1, the rest is the same as example 4.
Experiment:
the composite lithium battery diaphragm prepared in the embodiment and the comparative example is subjected to performance detection, and the battery diaphragm is cut into 3 multiplied by 4cm 2 The square sheet of (1) was subjected to heat treatment at 120 ℃ to calculate the heat shrinkage; deionized water was dropped on the surface of the separator, and the contact angle was measured.
The data obtained are shown in the following table:
and (4) conclusion: as can be seen from the above data, examples 1-3 have better thermal stability than comparative example 1. Under the same conditions, the coated alumina of the examples 1-3 is more and has better performance. Comparative example 2 polyethylene glycol was not modified, amino group aggregation was reduced, and hydrophilicity was decreased. Comparative example 3 no POSS grafted with polyethylene glycol was prepared, the stability of modified polyethylene glycol, modified POSS in polymethyl methacrylate was not added, the amount of modified polyethylene glycol, modified POSS adhered to the polyethylene separator decreased, and the performance of the battery separator decreased. The mass ratio of the modified polyethylene glycol and the modified POSS added in the comparative example 4 is 3: 1, the number of amino groups is small, the hydrophilicity of the separator is lowered, and the contact angle is increased.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A preparation method of a composite lithium battery diaphragm is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: soaking the polyethylene diaphragm in a polymethyl methacrylate solution for 50-70s, taking out, draining, and drying at 45-55 ℃ for 22-24h to obtain a modified polyethylene diaphragm;
step two: and (2) placing the modified polyethylene diaphragm on an atomic layer deposition instrument, vacuumizing and heating at 50-60 ℃, introducing trimethylaluminum, introducing inert gas nitrogen for purging for 20-30s, introducing water vapor, introducing inert gas nitrogen for purging for 40-50s, and repeating the steps for 45-50 cycles to obtain the composite lithium battery diaphragm.
2. The method for preparing a composite lithium battery separator according to claim 1, characterized in that: in the third step, the concentration of the polymethyl methacrylate solution is 0.1 wt% -5 wt%.
3. The method for preparing a composite lithium battery separator according to claim 1, wherein: the thickness of the composite lithium battery diaphragm is 12-15 mu m.
4. The method for preparing a composite lithium battery separator according to claim 1, characterized in that: the polymethyl methacrylate is modified polymethyl methacrylate, and the preparation method comprises the following steps: taking methyl methacrylate and POSS grafted with polyethylene glycol, stirring for 30-40min, dropwise adding chloroplatinic acid catalyst, reacting for 2-3h at 76-82 ℃, cooling to 25-27 ℃, continuously heating to 86-90 ℃, and reacting for 1-2h to obtain the modified polymethyl methacrylate.
5. The method for preparing a composite lithium battery separator according to claim 4, characterized in that: the preparation method of the POSS grafted with the polyethylene glycol comprises the following steps: taking modified polyethylene glycol and deionized water, stirring for 30-40min, adding modified POSS, stirring for 18-20h at 60-70 ℃, filtering, washing and drying to obtain POSS grafted with polyethylene glycol.
6. The method for preparing a composite lithium battery separator according to claim 5, characterized in that: the preparation method of the modified polyethylene glycol comprises the following steps: taking polyethylene glycol, triphenyl phosphine, phthalimide and tetrahydrofuran, stirring uniformly, reacting at-2-2 ℃ for 50-70min, continuing to react at 25-27 ℃ for 10-14h, performing chromatography to obtain a solution, adding ethanol and hydrazine hydrate, reacting for 1-2h, extracting, and drying to obtain the modified polyethylene glycol.
7. The method for preparing a composite lithium battery separator according to claim 5, characterized in that: the preparation method of the modified POSS comprises the following steps: the method comprises the following steps:
s1: taking vinyltriethoxysilane and acetone, uniformly stirring, dropwise adding hydrochloric acid, heating to 36-42 ℃, reacting for 44-50h, performing suction filtration, washing, adding acetone and dichloromethane for recrystallization, performing suction filtration, and drying to obtain POSS;
s2: stirring POSS, chloroform, glacial acetic acid and concentrated sulfuric acid at 66-72 ℃ for 1-2h, dropwise adding hydrogen peroxide, condensing and refluxing for 5-7h, adding sodium carbonate, reacting for 10-15min, washing, filtering and drying to obtain the modified POSS.
8. The method for preparing a composite lithium battery separator according to claim 5, characterized in that: the mass ratio of the modified polyethylene glycol to the modified POSS is (5-7): 1.
9. a composite lithium battery separator prepared by the method for preparing a composite lithium battery separator according to any one of claims 1 to 8.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116454541A (en) * | 2023-06-15 | 2023-07-18 | 中南大学 | Lithium battery composite diaphragm and preparation method and application thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104377331A (en) * | 2014-11-19 | 2015-02-25 | 新乡市中科科技有限公司 | Separator for lithium ion battery and preparation method of separator |
| CN106848164A (en) * | 2017-03-22 | 2017-06-13 | 武汉理工大学 | A kind of low heat shrinkage lithium ion battery separator and preparation method thereof |
| CN110137416A (en) * | 2019-05-15 | 2019-08-16 | 武汉理工大学 | A kind of polyolefin lithium electric separator preparation method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104377331A (en) * | 2014-11-19 | 2015-02-25 | 新乡市中科科技有限公司 | Separator for lithium ion battery and preparation method of separator |
| CN106848164A (en) * | 2017-03-22 | 2017-06-13 | 武汉理工大学 | A kind of low heat shrinkage lithium ion battery separator and preparation method thereof |
| CN110137416A (en) * | 2019-05-15 | 2019-08-16 | 武汉理工大学 | A kind of polyolefin lithium electric separator preparation method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116454541A (en) * | 2023-06-15 | 2023-07-18 | 中南大学 | Lithium battery composite diaphragm and preparation method and application thereof |
| CN116454541B (en) * | 2023-06-15 | 2023-08-25 | 中南大学 | Lithium battery composite diaphragm and preparation method and application thereof |
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