CN114927830B - Fold MXene modified diaphragm for lithium ion battery and preparation method thereof - Google Patents

Fold MXene modified diaphragm for lithium ion battery and preparation method thereof Download PDF

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Publication number
CN114927830B
CN114927830B CN202210589891.3A CN202210589891A CN114927830B CN 114927830 B CN114927830 B CN 114927830B CN 202210589891 A CN202210589891 A CN 202210589891A CN 114927830 B CN114927830 B CN 114927830B
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mxene
nano
diaphragm
pmma
corrugated
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CN114927830A (en
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李帆
张立斌
赵海玉
沈亚定
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Jiangsu Housheng New Energy Technology Co Ltd
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Jiangsu Housheng New Energy Technology Co Ltd
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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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • 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 provides a corrugated MXene modified diaphragm for a lithium ion battery and a preparation method thereof, wherein the corrugated MXene@Mg (OH) 2 The mechanical strength and heat resistance of the diaphragm are greatly improved by introducing the nano-sheet, the adhesiveness of the diaphragm to the pole piece and the electrolyte wettability are greatly improved, and the problem of PMMA coating powder removal in the early-stage coating and the later-stage cell manufacturing process is greatly solved; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, limiting the concentration of wetting agent in the coating layer to 2.5X10 ‑5 ‑1.5×10 ‑3 mol/L, the mechanical strength of the diaphragm and the infiltration viscosity of the diaphragm to the base film are improved, and the effective service life of the diaphragm is prolonged; the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder are blended by adopting a solution blending method, and the PMMA powder is blended, so that the mass ratio of the hyperbranched grafted multi-arm polymer to the ionic liquid block copolymer to the PMMA powder is limited, the ionic conductivity is greatly improved, and meanwhile, the heat shrinkage of the diaphragm is improved, so that the heat resistance of the diaphragm is further improved.

Description

Fold MXene modified diaphragm for lithium ion battery and preparation method thereof
Technical Field
The invention relates to the field of battery diaphragms, in particular to a corrugated MXene modified diaphragm for a lithium ion battery and a preparation method thereof.
Background
Along with the rapid development of new energy industry, the lithium battery has the advantages of high energy density and long cycle life in the vigorous period of development, so that the lithium battery is widely applied to various energy applications. The separator in the lithium battery can effectively prevent the risk of short circuit between the positive electrode contact and the negative electrode contact, so that the separator has higher requirements on the performance of the lithium battery in order to improve the safe usability of the lithium battery.
The most widely used lithium battery separator at present is a polyolefin separator, however, the use of a polyolefin separator often suffers from the following problems: because the single polyolefin diaphragm has insufficient performance of the electrophilic solution and poor adhesion performance to the polar plate, the lithium battery has poor cycle performance, poor hardness, low thermal stability and the like, and the development path of the lithium battery to a high ultrathin battery is limited; the mechanical strength and puncture resistance of the single polyolefin membrane are poor, and the single polyolefin membrane is easy to puncture to form thermal runaway; polyolefin separators have a low melting point and are susceptible to film rupture when thermal runaway occurs, thereby exacerbating thermal runaway and causing the battery to burn or even explode.
The problem that the adhesion of the polyolefin diaphragm to the pole piece and the electrolyte wettability are poor is solved by coating a water-based PVDF glue layer on one side or two sides of the polyolefin diaphragm in the prior market, but the problem of easy falling off exists at the same time; the problem of poor mechanical property and heat resistance of the polyolefin membrane is solved by coating a high-temperature resistant ceramic coating on one side or both sides of the polyolefin membrane, although the membrane can be closed to 150 ℃, the closed pore temperature of 150 ℃ also has the danger of short circuit or spontaneous combustion at high temperature, so that the current research hot spot is how to further improve the heat resistance of the membrane, reduce the membrane rupture risk of the membrane and improve the safety usability of a lithium battery.
Disclosure of Invention
The invention aims to provide a corrugated MXene modified diaphragm for a lithium ion battery and a preparation method thereof, which are used for solving the problems in the prior art.
In order to solve the technical problems, the invention provides the following technical scheme:
a corrugated MXene modified diaphragm for a lithium ion battery comprises a base film and a coating layer formed on the surface of the base film; the coating comprises the following components in parts by weight: 0.6 to 1.6 percent of dispersing agent, 15 to 25 percent of PMMA powder and 13 to 23 percent of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 7% -10% of thickener, 2% -4% of binder, 0.2% -0.5% of wetting agent, 0.05% -0.2% of defoaming agent and the balance of ultrapure water.
The MXene nano-sheets are selected as the coating material to be added into the slurry component, wherein the pleated MXene nano-sheets have good high temperature resistance and heat conduction performance, and the heat resistance of the coating is improved, so that the heat resistance of the diaphragm is improved;
further, the preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing titanium hydride, titanium carbide and aluminum powder, ball milling for 3-4 hours, calcining for 2 hours at 1440-1450 ℃ in an argon atmosphere, cooling, ball milling for 2-3 hours, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX, lithium fluoride and hydrochloric acid at 25-30 ℃ for 22-24h, centrifuging, washing with water until the pH is more than 6, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treatment is carried out on the three-dimensional MXene and deionized water for 160-180min under the argon atmosphere, supernatant fluid is centrifugally taken, and freeze drying is carried out, thus obtaining the stripped MXene nano-sheet;
(4) Mixing the stripped MXene nano-sheets with hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 90-95 ℃ for 5-6 hours, cooling to 18-25 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets.
Further, the mass-volume ratio of the powdery MAX to the lithium fluoride to the hydrochloric acid is 1g to 20mL; the mass-volume ratio of the three-dimensional MXene to the deionized water is 1g to 15mL.
Further, the base film is a polyolefin separator; the dispersing agent is aliphatic amide dispersing agent, the thickening agent is hydroxymethyl cellulose sodium thickening agent, the adhesive is polyacrylic adhesive, and the defoaming agent is polyether type defoaming agent; the wetting agent is alkyl sulfate wetting agent.
Wherein the fold MXene@Mg (OH) 2 The introduction of the nano-sheet benefits from the excellent performance of the nano-sheet, so that the mechanical strength of the diaphragm is greatly improved; and the folded MXene nano-sheet, PMMA and Mg (OH) with flame retardant property 2 The three components cooperate to improve the heat resistance of the diaphragm;
further, the wrinkles MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to prepare magnesium sulfate solution, adding the folded MXene nano-sheets under stirring, performing ultrasonic dispersion for 1-2h, heating to 70-75 ℃, adding 2mol/L ammonia water at a flow rate of 55ml/min, stopping the reaction at a pH of 8-10, filtering, washing with absolute ethyl alcohol and ultrapure water in sequence, and performing vacuum drying for 10-12h to obtain folded MXene@Mg (OH) 2 A nano-sheet.
Further, the molar concentration to mass ratio of the magnesium sulfate solution, the ammonia water and the wrinkled MXene nano-sheet was 1.85mol/L to 2mol/L to 2.36g.
MXene@Mg(OH) 2 The fold structure of the nano-sheet surface enables PMMA particles to be firmly adhered to MXene@Mg (OH) 2 The surface of the nano sheet greatly improves the adhesiveness of the diaphragm to the pole piece and the electrolyte wettability, and greatly improves the problem of PMMA coating powder removal in the early-stage coating and the later-stage cell manufacturing process;
and the fold MXene@Mg (OH) 2 The nano-sheet is introduced by Mg (OH) 2 A charring layer formed by heating, decomposing and absorbing crystal water; when the temperature rises to the decomposition temperature, mg (OH) 2 The decomposition releases water vapor, absorbs latent heat, dilutes the concentration of oxygen and combustible gas near the surface of the combustion object, and makes surface combustion difficult to carry out; the charring layer formed on the surface prevents oxygen and heat from entering, and magnesium oxide generated by decomposition of the charring layer is also a good refractory material, has good high temperature resistance and heat conduction performance, and can improve the capability of the material for resisting open fire.
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano sheet and ultrapure water for 10-30min, wherein the rotating speed is 100-300rpm; adding thickener, stirring for 20-60min at 200-500rpm; adding binder, and stirring for 30-50min at 350-500rpm; adding wetting agent and defoaming agent, stirring for 20-40min at 400-600rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
s2: and (3) adopting a micro-gravure roll coating process, roll-coating the prepared coating slurry on two sides of a base film, drying at 70-75 ℃, and rolling to obtain the corrugated MXene modified diaphragm for the lithium ion battery.
Branched dodecyl (polyoxy isopropenyl) 8 Sodium sulfate (G-C) 12 PO 8 S) is offered by Sasol, south Africa;
the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate (G-C) 12 PO 8 S) a polyoxypropylene chain (PO) is inserted between the hydrophobic alkyl and the hydrophilic polar groups, the PO group can lead toThe surface wetting agent molecules are obviously in a rugby shape on a gas-liquid interface, so that the surface wetting agent has excellent interface characteristics, polar groups and nonpolar groups, can be adsorbed on the surface of the modified PMMA through polar interaction and hydrophobic interaction, and can interact with the surface wetting agent molecules through adsorption modes such as hydrogen bond, polar interaction, hydrophobic interaction and the like, so that the wettability to the modified PMMA is improved, and the ion conductivity of the diaphragm is improved.
By defining the concentration of wetting agent in the coating layer to be 2.5X10 -5 -1.5×10 -3 mol/L to further improve ion conductivity and heat resistance of the separator because at 1X 10 -7 -2.5×10 -5 The mol/L increases along with the increase of the concentration, the adsorption quantity of wetting agent molecules at a gas-liquid interface and a solid-liquid interface is increased, the influence on a contact angle is counteracted, the contact angle is not changed greatly, the molecules are adsorbed at the solid-liquid interface by means of an ion head, and a hydrophobic tail chain points to a solution; when the concentration is 2.5X10 -5 -1.5×10 -3 The adsorption quantity of the wetting agent molecules at the gas-liquid interface tends to be saturated, so that the contact angle is rapidly reduced, at the moment, the wetting agent molecules are adsorbed on the PMMA surface through hydrophobic interaction, and an aggregate is formed at the solid-liquid interface, so that the steric hindrance of the wetting agent is reduced by limiting the concentration and the branching degree of the wetting agent, the wetting agent forms an aggregate, the solid-liquid interface tension is reduced, the hydrophilic modification capacity of the wetting agent is enhanced, the ionic conductivity of the diaphragm is greatly improved, and the heat resistance of the diaphragm is improved.
Further, the PMMA powder is modified PMMA, and the preparation method comprises the following steps:
1) Mixing and stirring 2, 2-bipyridine, cuprous chloride, hyperbranched poly-p-chloromethyl styrene, methyl methacrylate and toluene under the argon atmosphere, and reacting for 8-9h at 65-68 ℃ to obtain a hyperbranched grafted multi-arm polymer;
2) Under the protection of argon, mixing and stirring S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate, azodiisobutyronitrile, methyl methacrylate and toluene, and reacting for 4-5 hours at 65-68 ℃ to obtain the trithiocarbonate end-capped polymethyl methacrylate;
3) In a nitrogen environment, polymethyl methacrylate, azodiisobutyronitrile, vinylbenzyl chloride and toluene which are end-capped by the trithiocarbonate end group are mixed and stirred, and react for 16-18 hours at 65-68 ℃ to obtain an ionic liquid block copolymer;
4) And mixing and stirring the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer, the PMMA powder and the tetrahydrofuran to obtain the modified PMMA.
Further, in the step 1), the molar mass ratio of the 2, 2-bipyridine, the methyl methacrylate, the cuprous chloride and the hyperbranched poly-p-chloromethyl styrene is 0.8 mmol/0.04 mol/0.04 g/0.5 g, and the number average molecular weight of the hyperbranched poly-p-chloromethyl styrene is 2500g/mol; the molar mass ratio of azobisisobutyronitrile, methyl methacrylate, S-dodecyl-S '- (α, α' -dimethyl- α "-acetic acid) trithiocarbonate in step 2) was 2mmol:0.07mol:0.37g; the molar mass ratio of azobisisobutyronitrile, trithiocarbonate end-capped polymethyl methacrylate and vinylbenzyl chloride in step 3) was 0.01 mmol:0.6g:1.54g.
Further, in the step 4), the mass ratio of the hyperbranched grafted multi-arm polymer to the ionic liquid block copolymer to the PMMA powder is 1 (1-3): 4.
According to the invention, the hyperbranched grafted multi-arm polymer and the ionic liquid block copolymer are blended into PMMA powder by adopting a solution blending method, so that the ion conductivity of the diaphragm is synergistically improved; the invention modifies the surface of hyperbranched poly-p-chloromethyl styrene and grafts PMMA to prepare hyperbranched grafted multi-arm polymer; then preparing a functional block copolymer by using a RAFT method, and then preparing an ionic liquid block copolymer;
Preparing an ionic liquid block copolymer polymeric ionic liquid containing both polymeric ionic liquid chain segments and general polymer chain segments, so as to greatly improve the mechanical properties of the diaphragm, but only doping the non-conductive general polymer chain segments can reduce the ionic conductivity of the ionic liquid block copolymer; therefore, the three-dimensional spherical space structure of the hyperbranched polymer can be utilized, the molecular chain is not easy to be entangled, the ionic liquid segmented copolymer is modified, a large number of active end groups existing on the surface of the hyperbranched polymer are utilized, and the polymeric ionic liquid chain segment or ionic group is introduced into the hyperbranched polymer in a blending mode, so that the migration rate of ions is improved.
The mass ratio of the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder is limited, so that the ionic conductivity is greatly improved, and meanwhile, the heat shrinkage of the diaphragm is improved, and the heat resistance of the diaphragm is further improved.
The invention has the beneficial effects that:
the invention provides a corrugated MXene modified diaphragm for a lithium ion battery and a preparation method thereof, wherein the lithium ion battery diaphragm with good heat resistance, high flame retardance and high safety is prepared through component definition and process adjustment;
Wherein the fold MXene@Mg (OH) 2 The introduction of the nano-sheet benefits from the excellent performance of the nano-sheet, so that the mechanical strength of the diaphragm is greatly improved; and the folded MXene nano-sheet, PMMA and Mg (OH) with flame retardant property 2 The three components cooperate to improve the heat resistance of the diaphragm; MXene@Mg (OH) 2 The fold structure of the nano-sheet surface enables PMMA particles to be firmly adhered to MXene@Mg (OH) 2 The surface of the nano sheet greatly improves the adhesiveness of the diaphragm to the pole piece and the electrolyte wettability, and greatly improves the problem of PMMA coating powder removal in the early-stage coating and the later-stage cell manufacturing process;
and the fold MXene@Mg (OH) 2 The nano-sheet is introduced by Mg (OH) 2 A charring layer formed by heating, decomposing and absorbing crystal water; when the temperature rises to the decomposition temperature, mg (OH) 2 The decomposition releases water vapor, absorbs latent heat, dilutes the concentration of oxygen and combustible gas near the surface of the combustion object, and makes surface combustion difficult to carry out; the charring layer formed on the surface prevents oxygen and heat from entering, and magnesium oxide generated by decomposition of the charring layer is also a good refractory material, has good high temperature resistance and heat conduction performance, and can improve the capability of the material for resisting open fire;
the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, limiting the concentration of wetting agent in the coating layer to 2.5X10 -5 -1.5×10 -3 The ionic conductivity of the diaphragm is further improved by mol/L, the wetting agent molecules are adsorbed on the PMMA surface through hydrophobic interaction, aggregates are formed at a solid-liquid interface, the solid-liquid interface tension is reduced, the hydrophilic modification capability of the solid-liquid interface is enhanced, the ionic conductivity of the diaphragm is greatly improved, the mechanical strength of the diaphragm and the infiltration viscosity of a base film are improved, and the effective service life of the diaphragm is prolonged;
the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder are blended by adopting a solution blending method, so that the PMMA powder is blended, and the ion conductivity of the diaphragm is synergistically improved; the invention modifies the surface of hyperbranched poly-p-chloromethyl styrene and grafts PMMA to prepare hyperbranched grafted multi-arm polymer; preparing a functional block copolymer, and then preparing an ionic liquid block copolymer; the mass ratio of the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder is limited, so that the ionic conductivity is greatly improved, and meanwhile, the heat shrinkage of the diaphragm is improved, and the heat resistance of the diaphragm is further improved.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, if directional indications such as up, down, left, right, front, and rear … … are involved in the embodiment of the present invention, the directional indications are merely used to explain a relative positional relationship, a movement condition, and the like between a certain posture such as the respective components, and if the certain posture is changed, the directional indications are changed accordingly. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
The following description of the embodiments of the present invention will be presented in further detail with reference to the examples, which should be understood as being merely illustrative of the present invention and not limiting.
Example 1
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano-sheets and ultrapure water for 10min, wherein the rotating speed is 300rpm; adding the thickener, and continuously stirring for 20min at 500rpm; adding the binder, and continuing stirring for 30min at 500rpm; adding a wetting agent and a defoaming agent, and stirring for 20min at 600rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 0.6% of dispersing agent, 15% of PMMA powder and 13% of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 7% of thickener, 2% of binder, 0.2% of wetting agent, 0.05% of defoamer and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide, the thickening agent is sodium hydroxymethyl cellulose, the adhesive is polyacrylic acid, and the defoaming agent is polyether type defoaming agent; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 2.5X10 -5 mol/L；
Fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to prepare 250ml of magnesium sulfate solution with the concentration of 1.85mol/L, adding 2.36g of wrinkling MXene nano-sheets under the stirring condition, ultrasonically dispersing for 1h, heating to 75 ℃, adding 2mol/L ammonia water with the flow rate of 55ml/min, stopping the reaction when the pH is 8, filtering, washing by adopting absolute ethyl alcohol and ultrapure water in sequence, and vacuum drying for 10h to obtain the wrinkling MXene@Mg (OH) 2 A nano-sheet.
The preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball-milling for 3 hours, calcining for 2 hours at 1440 ℃ in an argon atmosphere, cooling, ball-milling for 2 hours, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL for 24h at 25 ℃, centrifuging, washing with water until the pH value is=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water in an argon atmosphere for 160min, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 90 ℃ for 6 hours, cooling to 18 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets;
s2: and (3) adopting a micro-gravure roller coating process, rolling the prepared coating slurry on two sides of a base film, and drying at 70 ℃ and then rolling to obtain the corrugated MXene modified diaphragm for the lithium ion battery.
Example 2
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano-sheets and ultrapure water for 20min, wherein the rotating speed is 200rpm; adding the thickener, and continuously stirring for 40min at the rotating speed of 300rpm; adding the binder, and continuously stirring for 40min at the rotating speed of 400rpm; adding a wetting agent and a defoaming agent, and stirring for 30min at a rotating speed of 500rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 1.2% of dispersing agent, 20% of PMMA powder and 15% of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 9% of thickener, 3% of binder, 0.4% of wetting agent, 0.1% of defoamer and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide and thickenerThe adhesive is polyacrylic acid, and the defoamer is polyether defoamer; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 5X 10 -4 mol/L；
Fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
the magnesium sulfate powder was dissolved in ultrapure water to prepare 250ml of a magnesium sulfate solution having a concentration of 1.85mol/L, and 2.36g of the folded MXene nanoplatelets were added under stirring to ultrasonically disperse 1.5h, heating to 72 ℃, adding 2mol/L ammonia water at a flow rate of 55ml/min, stopping the reaction at the pH of 9, filtering, washing by adopting absolute ethyl alcohol and ultrapure water in sequence, and vacuum drying for 11h to obtain the wrinkle MXene@Mg (OH) 2 A nano-sheet.
The preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball-milling for 3.5h, calcining for 2h at 1440-1450 ℃ in an argon atmosphere, cooling, ball-milling for 2.5h, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL at 28 ℃ for 23h, centrifugally washing with water until pH=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water in an argon atmosphere for 170min, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 92 ℃ for 5.5h, cooling to 20 ℃, filtering, washing with absolute ethyl alcohol and deionized water, placing in a vacuum at 80 ℃ for drying for 24h, and controlling the vacuum degree of the vacuum drying at 0.08Mpa to obtain the pleated MXene nano-sheets;
s2: and (3) adopting a micro-gravure roller coating process, rolling the prepared coating slurry on two sides of a base film, drying at 73 ℃, and rolling to obtain the corrugated MXene modified diaphragm for the lithium ion battery.
Example 3
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano-sheets and ultrapure water for 30min, wherein the rotating speed is 100rpm; adding the thickener, and continuously stirring for 60min at the rotating speed of 200rpm; adding the binder, and continuing stirring for 50min at the rotating speed of 350rpm; adding a wetting agent and a defoaming agent, and stirring for 40min at 400rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 1.6% of dispersing agent, 25% of PMMA powder and 23% of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 10% of thickener, 4% of binder, 0.5% of wetting agent, 0.2% of defoaming agent and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide, the thickening agent is sodium hydroxymethyl cellulose, the adhesive is polyacrylic acid, and the defoaming agent is polyether type defoaming agent; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 1.5X10 -3 mol/L；
Fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to prepare 250ml of magnesium sulfate solution with the concentration of 1.85mol/L, adding 2.36g of wrinkling MXene nanosheets under the stirring condition, performing ultrasonic dispersion for 2 hours, heating to 75 ℃, adding 2mol/L ammonia water with the flow rate of 55ml/min, stopping the reaction when the pH is 10, filtering, washing by adopting absolute ethyl alcohol and ultrapure water in sequence, and performing vacuum drying for 12 hours to obtain the wrinkling MXene@Mg (OH) 2 A nanosheet;
the preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball milling for 3-4h, calcining for 2h at 1450 ℃ in an argon atmosphere, cooling, ball milling for 3h, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL at 30 ℃ for 22h, centrifugally washing with water until pH=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water for 180min in an argon atmosphere, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 95 ℃ for 6 hours, cooling to 25 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets;
s2: and (3) adopting a micro-gravure roller coating process, rolling the prepared coating slurry on two sides of a base film, drying at 75 ℃, and rolling to obtain the corrugated MXene modified diaphragm for the lithium ion battery.
Example 4
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: premixing a dispersing agent, PMMA powder, a wrinkled MXene@Mg (OH) 2 nanosheets and ultrapure water for 10min, wherein the rotating speed is 300rpm; adding the thickener, and continuously stirring for 20min at 500rpm; adding the binder, and continuing stirring for 30min at 500rpm; adding a wetting agent and a defoaming agent, and stirring for 20min at 600rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 0.6% of dispersing agent, 15% of PMMA powder, 13% of wrinkling MXene@Mg (OH) 2 nanosheets, 7% of thickening agent, 2% of binder, 0.2% of wetting agent, 0.05% of defoaming agent and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide, the thickening agent is sodium hydroxymethyl cellulose, the adhesive is polyacrylic acid, and the defoaming agent is polyether type defoaming agent; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 2.5X10 -5 mol/L；
The preparation of the folded MXene@Mg (OH) 2 nanosheets comprises the following steps:
dissolving magnesium sulfate powder in ultrapurePreparing 250ml of magnesium sulfate solution with the concentration of 1.85mol/L in water, adding 2.36g of wrinkling MXene nano-sheet under stirring, performing ultrasonic dispersion for 1h, heating to 75 ℃, adding 2mol/L ammonia water with the flow rate of 55ml/min, stopping the reaction at the pH of 8, filtering, washing by adopting absolute ethyl alcohol and ultrapure water in sequence, and performing vacuum drying for 10h to obtain the wrinkling MXene@Mg (OH) 2 A nano-sheet.
The preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball-milling for 3 hours, calcining for 2 hours at 1440 ℃ in an argon atmosphere, cooling, ball-milling for 2 hours, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL for 24h at 25 ℃, centrifuging, washing with water until the pH value is=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water in an argon atmosphere for 160min, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 90 ℃ for 6 hours, cooling to 18 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets;
s2: the prepared coating slurry is coated on two sides of a base film by adopting a micro gravure roller coating process, and is rolled after being dried at 70 ℃ to obtain a fold MXene modified diaphragm for the lithium ion battery;
the PMMA powder is modified PMMA, and the preparation method comprises the following steps:
1) Under argon atmosphere, 0.8mmol of 2, 2-bipyridine, 0.04g of cuprous chloride and hyperbranched poly-p-chloromethyl styrene (0.5 g, the number average molecular weight is 2500 g/mol), 0.04mol of methyl methacrylate and 10mL of toluene are mixed and stirred, and react for 9 hours at 65 ℃ to obtain hyperbranched grafted multi-arm polymer;
2) Under the protection of argon, 0.37g of S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate, 2mmol of azodiisobutyronitrile, 0.07mol of methyl methacrylate and 9mL of toluene are mixed and stirred, and reacted for 5 hours at 65 ℃ to obtain the polymethyl methacrylate with end-capped trithiocarbonate;
3) Under the nitrogen environment, 0.6g of polymethyl methacrylate with end-capped trithiocarbonate groups, 0.011mmol of azodiisobutyronitrile, 1.54g of vinylbenzyl chloride and 6mL of toluene are mixed and stirred, and the mixture is reacted for 18 hours at 65 ℃ to obtain an ionic liquid block copolymer;
4) 5g of hyperbranched grafted multi-arm polymer, 5g of ionic liquid block copolymer, 20g of PMMA powder and 10mL of tetrahydrofuran are mixed and stirred to obtain the modified PMMA.
Example 5
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano-sheets and ultrapure water for 20min, wherein the rotating speed is 200rpm; adding the thickener, and continuously stirring for 40min at the rotating speed of 300rpm; adding the binder, and continuously stirring for 40min at the rotating speed of 400rpm; adding a wetting agent and a defoaming agent, and stirring for 30min at a rotating speed of 500rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 1.2% of dispersing agent, 20% of PMMA powder and 15% of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 9% of thickener, 3% of binder, 0.4% of wetting agent, 0.1% of defoamer and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide, the thickening agent is sodium hydroxymethyl cellulose, the adhesive is polyacrylic acid, and the defoaming agent is polyether type defoaming agent; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 5X 10 -4 mol/L；
Fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to prepare 250ml of magnesium sulfate solution with the concentration of 1.85mol/L, and adding the wrinkled MXene nanometer under the stirring condition2.36g of tablet and 1 by ultrasonic dispersion. 5h, heating to 72 ℃, adding 2mol/L ammonia water at a flow rate of 55ml/min, stopping the reaction at the pH of 9, filtering, washing by adopting absolute ethyl alcohol and ultrapure water in sequence, and vacuum drying for 11h to obtain the wrinkle MXene@Mg (OH) 2 A nano-sheet.
The preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball-milling for 3.5h, calcining for 2h at 1440-1450 ℃ in an argon atmosphere, cooling, ball-milling for 2.5h, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL at 28 ℃ for 23h, centrifugally washing with water until pH=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water in an argon atmosphere for 170min, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 92 ℃ for 5.5h, cooling to 20 ℃, filtering, washing with absolute ethyl alcohol and deionized water, placing in a vacuum at 80 ℃ for drying for 24h, and controlling the vacuum degree of the vacuum drying at 0.08Mpa to obtain the pleated MXene nano-sheets;
s2: the prepared coating slurry is coated on two sides of a base film by adopting a micro gravure roller coating process, and is rolled after being dried at 73 ℃ to obtain a fold MXene modified diaphragm for the lithium ion battery;
the PMMA powder is modified PMMA, and the preparation method comprises the following steps:
1) Under argon atmosphere, 0.8mmol of 2, 2-bipyridine, 0.04g of cuprous chloride and hyperbranched poly-p-chloromethyl styrene (0.5 g, the number average molecular weight is 2500 g/mol), 0.04mol of methyl methacrylate and 10mL of toluene are mixed and stirred, and react for 8.5 hours at 66 ℃ to obtain hyperbranched grafted multi-arm polymer;
2) Under the protection of argon, 0.37g of S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate, 2mmol of azodiisobutyronitrile, 0.07mol of methyl methacrylate and 9mL of toluene are mixed and stirred, and reacted for 4.5 hours at 66 ℃ to obtain the polymethyl methacrylate with end group end capped by trithiocarbonate;
3) Under the nitrogen environment, 0.6g of polymethyl methacrylate with end-capped trithiocarbonate groups, 0.011mmol of azodiisobutyronitrile, 1.54g of vinyl benzyl chloride and 6mL of toluene are mixed and stirred, and the mixture is reacted for 17 hours at the temperature of 65-68 ℃ to obtain an ionic liquid block copolymer;
4) 5g of hyperbranched grafted multi-arm polymer, 10g of ionic liquid block copolymer, 20g of PMMA powder and 10mL of tetrahydrofuran are mixed and stirred to obtain the modified PMMA.
Example 6
A preparation method of a corrugated MXene modified diaphragm for a lithium ion battery comprises the following steps:
s1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano-sheets and ultrapure water for 30min, wherein the rotating speed is 100rpm; adding the thickener, and continuously stirring for 60min at the rotating speed of 200rpm; adding the binder, and continuing stirring for 50min at the rotating speed of 350rpm; adding a wetting agent and a defoaming agent, and stirring for 40min at 400rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
the coating slurry comprises the following components in parts by mass: 1.6% of dispersing agent, 25% of PMMA powder and 23% of wrinkling MXene@Mg (OH) 2 The nano-sheet comprises 10% of thickener, 4% of binder, 0.5% of wetting agent, 0.2% of defoaming agent and the balance of ultrapure water;
the base film is a polyolefin diaphragm; the dispersing agent is aliphatic amide, the thickening agent is sodium hydroxymethyl cellulose, the adhesive is polyacrylic acid, and the defoaming agent is polyether type defoaming agent; the wetting agent is branched dodecyl (polyoxypropylene) 8 Sodium sulfate, the concentration of the wetting agent in the coating layer being 1.5X10 -3 mol/L；
Fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to obtain 250ml of magnesium sulfate solution with concentration of 1.85mol/L, adding 2.36g of folded MXene nano-sheets under stirring, performing ultrasonic dispersion for 2h, heating to 75deg.C, and adding 2mol at flow rate of 55ml/minAmmonia water of/L, pH 10, stopping reaction, filtering, washing with absolute ethyl alcohol and ultrapure water in sequence, and vacuum drying for 12h to obtain the wrinkle MXene@Mg (OH) 2 A nanosheet;
the preparation of the folded MXene nano-sheets comprises the following steps:
(1) Mixing 7.1321g of titanium hydride, 17.3623g of titanium carbide and 4.6916g of aluminum powder, ball milling for 3-4h, calcining for 2h at 1450 ℃ in an argon atmosphere, cooling, ball milling for 3h, and sieving to obtain powdery MAX;
(2) Stirring powdery MAX1g, lithium fluoride 1g and 9M hydrochloric acid 20mL at 30 ℃ for 22h, centrifugally washing with water until pH=7, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treating 1g of three-dimensional MXene and 25mL of deionized water for 180min in an argon atmosphere, centrifuging to obtain supernatant, and freeze-drying to obtain stripped MXene nano-sheets;
(4) Mixing 1g of stripped MXene nano-sheets with 20mL of 80% hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 95 ℃ for 6 hours, cooling to 25 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets;
s2: the prepared coating slurry is coated on two sides of a base film by adopting a micro gravure roller coating process, and is rolled after being dried at 75 ℃ to obtain a fold MXene modified diaphragm for the lithium ion battery;
the PMMA powder is modified PMMA, and the preparation method comprises the following steps:
1) Under argon atmosphere, 0.8mmol of 2, 2-bipyridine, 0.04g of cuprous chloride and hyperbranched poly-p-chloromethyl styrene (0.5 g, the number average molecular weight is 2500 g/mol), 0.04mol of methyl methacrylate and 10mL of toluene are mixed and stirred, and react for 8 hours at 68 ℃ to obtain hyperbranched grafted multi-arm polymer;
2) Under the protection of argon, 0.37g of S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate, 2mmol of azodiisobutyronitrile, 0.07mol of methyl methacrylate and 9mL of toluene are mixed and stirred, and reacted for 4 hours at 68 ℃ to obtain the polymethyl methacrylate with end-capped trithiocarbonate;
3) Under the nitrogen environment, 0.6g of polymethyl methacrylate with end-capped trithiocarbonate groups, 0.011mmol of azodiisobutyronitrile, 1.54g of vinylbenzyl chloride and 6mL of toluene are mixed and stirred, and the mixture is reacted for 16 hours at 68 ℃ to obtain an ionic liquid block copolymer;
4) 5g of hyperbranched grafted multi-arm polymer, 15g of ionic liquid block copolymer, 20g of PMMA powder and 10mL of tetrahydrofuran are mixed and stirred to obtain the modified PMMA.
Comparative example 1
As a control, example 3 was used without the addition of wrinkles MXene@Mg (OH) 2 The nano-sheet and other working procedures are normal.
Comparative example 2
The same polypropylene base film as in examples 1 to 6 was used, and the other steps were normal.
Comparative example 3
Using example 6 as a control, the wetting agent concentration in the coating layer was 2X 10 -5 mol/L, other working procedures are normal.
Comparative example 4
Using example 6 as a control, the wetting agent concentration in the coating layer was 2X 10 -3 mol/L, other working procedures are normal.
Comparative example 5
Taking the example 6 as a control group, the mass ratio of the hyperbranched grafted multi-arm polymer to the ionic liquid block copolymer to the PMMA powder is 1:0.8:4, and other procedures are normal.
Comparative example 6
Taking the example 6 as a control group, the mass ratio of the hyperbranched grafted multi-arm polymer to the ionic liquid block copolymer to the PMMA powder is 1:3.1:4, and other procedures are normal.
Performance test: the separators prepared in examples 1 to 6 and comparative examples 1 to 6 were subjected to performance tests, and the films were tested for thickness, air permeation value, needling strength, anodic-hot press peeling, ionic conductivity, and heat shrinkage with reference to GB/T36363-2018;
oxygen index measurement: reference IOS4589-2 assay: oxygen-nitrogen mixed gas with the temperature of 22 ℃; when the top surface is ignited, the flame is moved away every 5s, the time when the flame contacts the top surface is 20s, whether the membrane burns or not is observed, and the oxygen index is the minimum oxygen concentration required for just maintaining the combustion; the results are shown in Table 1;
TABLE 1
As can be seen by comparing example 3 with comparative example 1, comparative example 2, wherein the wrinkles MXene@Mg (OH) 2 The introduction of the nano-sheet benefits from the excellent performance of the nano-sheet, so that the mechanical strength of the diaphragm is greatly improved; and the folded MXene nano-sheet, PMMA and Mg (OH) with flame retardant property 2 The three components cooperate to improve the heat resistance of the diaphragm; MXene@Mg (OH) 2 The fold structure of the nano-sheet surface enables PMMA particles to be firmly adhered to MXene@Mg (OH) 2 The surface of the nano sheet greatly improves the adhesiveness of the diaphragm to the pole piece and the electrolyte wettability, and greatly improves the problem of PMMA coating powder removal in the early-stage coating and the later-stage cell manufacturing process;
and the fold MXene@Mg (OH) 2 The nano-sheet is introduced by Mg (OH) 2 A charring layer formed by heating, decomposing and absorbing crystal water; when the temperature rises to the decomposition temperature, mg (OH) 2 The decomposition releases water vapor, absorbs latent heat, dilutes the concentration of oxygen and combustible gas near the surface of the combustion object, and makes surface combustion difficult to carry out; the charring layer formed on the surface prevents oxygen and heat from entering, and magnesium oxide generated by decomposition of the charring layer is also a good refractory material, has good high temperature resistance and heat conduction performance, and can improve the capability of the material for resisting open fire;
as can be seen from a comparison of example 6 with comparative example 3 and comparative example 4, the wetting agent was branched dodecyl (polyoxypropylene) 8 Sodium sulfate, a section of polyoxypropylene chain (PO) is inserted between hydrophobic alkyl and hydrophilic polar groups, the PO groups can lead the surface wetting agent molecules to show obvious rugby shape on a gas-liquid interface, so that the surface wetting agent has excellent interface characteristics, the wetting agent has polar groups and nonpolar groups, the polar groups and the nonpolar groups can be adsorbed on the surface of modified PMMA through polar interaction and hydrophobic interaction, and adsorption modes such as hydrogen bond, polar interaction, hydrophobic interaction and the like are adopted The adhesive interacts with the adhesive to improve the wettability to the modified PMMA, the mechanical strength of the diaphragm and the wettability to the base film, and the effective service life of the diaphragm;
by defining the concentration of wetting agent in the coating layer to be 2.5X10 -5 -1.5×10 -3 mol/L to further enhance ion conductivity of the separator because at 1X 10 -7 -2.5×10 -5 The mol/L increases along with the increase of the concentration, the adsorption quantity of wetting agent molecules at a gas-liquid interface and a solid-liquid interface is increased, the influence on a contact angle is counteracted, the contact angle is not changed greatly, the molecules are adsorbed at the solid-liquid interface by means of an ion head, and a hydrophobic tail chain points to a solution; when the concentration is 2.5X10 -5 -1.5×10 -3 The adsorption quantity of the wetting agent molecules at the gas-liquid interface tends to be saturated, so that the contact angle is rapidly reduced, at the moment, the wetting agent molecules are adsorbed on the PMMA surface through hydrophobic interaction, and an aggregate is formed at the solid-liquid interface, so that the steric hindrance of the wetting agent is reduced by limiting the concentration and the branching degree of the wetting agent, the wetting agent forms an aggregate, the solid-liquid interface tension is reduced, the hydrophilic modification capacity of the wetting agent is enhanced, and the ionic conductivity of the diaphragm is greatly improved;
comparing example 6 with example 3, comparative example 5 and comparative example 6, it is known that the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder are blended by adopting a solution blending method, and the PMMA powder is blended to synergistically improve the ion conduction performance of the diaphragm; the invention modifies the surface of hyperbranched poly-p-chloromethyl styrene and grafts PMMA to prepare hyperbranched grafted multi-arm polymer; then preparing a functional block copolymer by using a RAFT method, and then preparing an ionic liquid block copolymer; the mass ratio of the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer and the PMMA powder is limited, so that the ionic conductivity is greatly improved, and meanwhile, the heat shrinkage of the diaphragm is improved, and the heat resistance of the diaphragm is further improved.
In conclusion, the diaphragm prepared by the method has good application prospect in the field of diaphragms.
The foregoing description is only exemplary embodiments of the present invention and is not intended to limit the scope of the invention, but rather, the equivalent structural changes made by the present invention in the light of the inventive concept, or the direct/indirect application in other related technical fields are included in the scope of the present invention.

Claims (7)

1. The corrugated MXene modified diaphragm for the lithium ion battery is characterized by comprising a base film and a coating layer formed on the surface of the base film; the coating comprises the following components in parts by weight: 0.6 to 1.6 percent of dispersing agent, 15 to 25 percent of PMMA powder and 13 to 23 percent of wrinkling MXene@Mg (OH) 2 Nano-sheet, 7% -10% of thickener, 2% -4% of binder, 0.2% -0.5% of wetting agent, 0.05% -0.2% of defoaming agent and the balance of ultrapure water;
fold MXene@Mg (OH) 2 The preparation of the nano-sheet comprises the following steps:
dissolving magnesium sulfate powder in ultrapure water to prepare magnesium sulfate solution, adding the folded MXene nano-sheets under stirring, performing ultrasonic dispersion for 1-2h, heating to 70-75 ℃, adding ammonia water, stopping the reaction at the pH of 8-10, filtering, washing with absolute ethyl alcohol and ultrapure water in sequence, and performing vacuum drying for 10-12h to obtain the folded MXene@Mg (OH) 2 A nanosheet;
the wetting agent is branched dodecyl (polyoxypropylene) 8 sodium sulfate, and the concentration of the wetting agent in the coating layer is 2.5X10 -5 -1.5×10 -3 mol/L；
The PMMA powder is modified PMMA, and the preparation method comprises the following steps:
1) Mixing and stirring 2, 2-bipyridine, cuprous chloride, hyperbranched poly-p-chloromethyl styrene, methyl methacrylate and toluene in an argon atmosphere, and reacting for 8-9h at 65-68 ℃ to obtain a hyperbranched grafted multi-arm polymer;
2) Under the protection of argon, mixing and stirring S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate, azodiisobutyronitrile, methyl methacrylate and toluene, and reacting for 4-5 hours at 65-68 ℃ to obtain the trithiocarbonate end-capped polymethyl methacrylate;
3) In a nitrogen environment, polymethyl methacrylate, azodiisobutyronitrile, vinylbenzyl chloride and toluene which are end-capped by the trithiocarbonate end group are mixed and stirred, and react for 16-18 hours at 65-68 ℃ to obtain an ionic liquid block copolymer;
4) The mass ratio is 1 (1-3), and the hyperbranched grafted multi-arm polymer, the ionic liquid block copolymer, the PMMA powder and the tetrahydrofuran of 4 are mixed and stirred to obtain the modified PMMA.
2. The corrugated MXene modified separator for a lithium ion battery of claim 1, wherein the base film is a polyolefin separator; the dispersing agent is an aliphatic amide dispersing agent, the thickening agent is a hydroxymethyl cellulose sodium thickening agent, the binder is a polyacrylic acid binder, the defoaming agent is a polyether defoaming agent, and the wetting agent is an alkyl sulfate wetting agent.
3. The corrugated MXene modified separator for lithium ion battery of claim 1, characterized in that the corrugated mxene@mg (OH) 2 In the preparation of the nano-sheets, the molar concentration and mass ratio of the magnesium sulfate solution, the ammonia water and the folded MXene nano-sheets are 1.85mol/L and 2mol/L and 2.36g.
4. The corrugated MXene modified separator for lithium ion battery of claim 1, characterized in that the corrugated mxene@mg (OH) 2 In the preparation of the nanosheets, the preparation of the folded MXene nanosheets comprises the following steps:
(1) Mixing titanium hydride, titanium carbide and aluminum powder, ball milling for 3-4 hours, calcining for 2 hours at 1440-1450 ℃ in an argon atmosphere, cooling, ball milling for 2-3 hours, and sieving to obtain powdery MAX;
(2) Mixing powdery MAX, lithium fluoride and hydrochloric acid, stirring at 25-30 ℃ for 22-24 hours, centrifuging, washing with water, and freeze-drying to obtain a three-dimensional product MXene;
(3) Ultrasonic treatment is carried out on the three-dimensional MXene and deionized water for 160-180min under the argon atmosphere, supernatant fluid is centrifugally taken, and freeze drying is carried out, thus obtaining the stripped MXene nano-sheet;
(4) Mixing the stripped MXene nano-sheets with hydrazine hydrate, transferring into a stainless steel autoclave with a PTFE lining, maintaining at 90-95 ℃ for 5-6 hours, cooling to 18-25 ℃, filtering, washing with absolute ethyl alcohol and deionized water, and vacuum drying at 80 ℃ for 24 hours, wherein the vacuum degree of vacuum drying is controlled at 0.08Mpa, thus obtaining the pleated MXene nano-sheets.
5. The corrugated MXene modified membrane for lithium ion battery according to claim 4, characterized in that in the preparation of corrugated MXene nanoplatelets, the mass-to-volume ratio of powdery MAX, lithium fluoride, hydrochloric acid is 1g:1g:20ml; the mass-volume ratio of the three-dimensional MXene to the deionized water is 1g to 15mL.
6. The corrugated MXene modified separator for lithium ion battery according to claim 1, characterized in that in the preparation of the modified PMMA, 1) the molar mass ratio of 2, 2-bipyridine, methyl methacrylate, cuprous chloride, hyperbranched poly-p-chloromethyl styrene is 0.8mmol:0.04mol:0.04g:0.5g, the hyperbranched poly-p-chloromethyl styrene has a number average molecular weight of 2500g/mol; 2) The molar mass ratio of the azodiisobutyronitrile, the methyl methacrylate and the S-dodecyl-S ' - (alpha, alpha ' -dimethyl-alpha ' -acetic acid) trithiocarbonate is 2mmol to 0.07mol to 0.37g; 3) The molar mass ratio of the azodiisobutyronitrile to the trithiocarbonate end-capped polymethyl methacrylate to the vinylbenzyl chloride is 0.01 mmol to 0.6g to 1.54g.
7. The method for producing a pleated MXene modified separator for a lithium ion battery according to any of claims 1 to 6, characterized by comprising the steps of:
S1: dispersing agent, PMMA powder, and wrinkling MXene@Mg (OH) 2 Premixing the nano sheet and ultrapure water for 10-30min, wherein the rotating speed is 100-300rpm; adding thickener, stirring for 20-60min at 200-500rpm; adding binder, and stirring for 30-50min at 350-500rpm; adding wetting agent and defoaming agent, stirring for 20-40min at 400-600rpm; filtering to remove iron to obtain PMMA-coated fold MXene@Mg (OH) 2 Coating slurry of nano-sheets;
s2: and (3) adopting a micro-gravure roll coating process, roll-coating the prepared coating slurry on two sides of a base film, drying at 70-75 ℃, and rolling to obtain the corrugated MXene modified diaphragm for the lithium ion battery.
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CN113871792A (en) * 2021-09-27 2021-12-31 江苏厚生新能源科技有限公司 Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof
CN113948816A (en) * 2021-10-18 2022-01-18 江苏厚生新能源科技有限公司 MXene composite material modified diaphragm for lithium-sulfur battery and preparation method thereof
CN114374051A (en) * 2021-11-02 2022-04-19 江苏厚生新能源科技有限公司 High-flame-retardance lithium dendrite growth-inhibiting coating diaphragm and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113871792A (en) * 2021-09-27 2021-12-31 江苏厚生新能源科技有限公司 Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof
CN113948816A (en) * 2021-10-18 2022-01-18 江苏厚生新能源科技有限公司 MXene composite material modified diaphragm for lithium-sulfur battery and preparation method thereof
CN114374051A (en) * 2021-11-02 2022-04-19 江苏厚生新能源科技有限公司 High-flame-retardance lithium dendrite growth-inhibiting coating diaphragm and preparation method thereof

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