CN113871792A - Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof - Google Patents

Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof Download PDF

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CN113871792A
CN113871792A CN202111135744.0A CN202111135744A CN113871792A CN 113871792 A CN113871792 A CN 113871792A CN 202111135744 A CN202111135744 A CN 202111135744A CN 113871792 A CN113871792 A CN 113871792A
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lithium
mos
sulfur battery
temperature
molybdenum disulfide
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李帆
张立斌
沈亚定
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Jiangsu Housheng New Energy Technology Co Ltd
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    • H—ELECTRICITY
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    • 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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    • B82—NANOTECHNOLOGY
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    • H—ELECTRICITY
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    • 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
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    • 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
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
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Abstract

The invention discloses a folded molybdenum disulfide composite diaphragm for a lithium-sulfur battery and a preparation method thereof. The base film is commercialPolypropylene diaphragm, filtering the folded MoS on a filter device by a low-speed suction filtration method2Nanosheet @ polydopamine-derived porous carbon layer/SnO2The nano particle composite material is filtered on the basement membrane in a suction way, so that the folded MoS is prepared2@C/SnO2And (4) modifying the composite diaphragm. The prepared composite diaphragm has excellent lithium ion conductivity, can effectively fix polysulfide, can obviously improve the capacity of a lithium-sulfur battery and increase the rate performance of the battery under the same rate condition compared with the existing commercial polypropylene diaphragm, and well solves the problem caused by shuttle effect. Greatly improves the utilization rate of active sulfur and further improves the electrochemical performance of the lithium-sulfur battery.

Description

Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof
Technical Field
The invention relates to the technical field of composite diaphragms for batteries, in particular to a folded molybdenum disulfide composite diaphragm for a lithium-sulfur battery and a preparation method thereof.
Background
With the increasing environmental and energy problems, the development of new generation of high energy density energy storage devices to fully utilize clean energy is urgent. Lithium-sulfur battery systems are considered to be one of the most promising battery technologies due to their advantages of high energy density, low cost, etc.
The lithium-sulfur battery diaphragm has great influence on the performance and the service life of the battery, and is a bottleneck for restricting the commercial popularization of the lithium-sulfur battery. In the liquid lithium-sulfur battery, polysulfide is continuously generated in the battery in the charging and discharging processes, and the porosity of the diaphragm provides possibility for the diffusion of the polysulfide, so that a severe shuttle effect is finally caused, the specific capacity of the battery is rapidly attenuated, and the service life of the battery is reduced.
Therefore, the preparation of the folded molybdenum disulfide composite diaphragm for the lithium-sulfur battery and the preparation method thereof have important significance in solving the problems.
Disclosure of Invention
The invention aims to provide a folded molybdenum disulfide composite diaphragm for a lithium-sulfur battery and a preparation method thereof, so as 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 folded molybdenum disulfide composite diaphragm for a lithium-sulfur battery comprises the following steps:
step 1: adding ultrapure water into trihydroxymethyl aminomethane, adjusting the pH value to 8-9 with dilute hydrochloric acid, stirring for 20-24 min to obtain a solution, and preparing the folded MoS2Immersing the nanosheets into the solution, adding dopamine hydrochloride, and reacting at room temperature for 10-14 h to obtain polydopamine modified MoS2Nanosheets; then transferring to a nitrogen environment, carbonizing at high temperature, and cooling to obtain the MoS modified by the carbon layer2Nanosheets;
step 2: will be described in detail1 resulting carbon layer modified MoS2Stirring and dissolving the nanosheets in deionized water, and uniformly stirring; ultrasonically dispersing for 1.5-2.5 h, and adding SnCl4·5H2Stirring O and NaOH for 18-22 min, and reacting the obtained mixed solution in an autoclave at the reaction temperature of 170-190 ℃ for 16-20 h; cooling to room temperature, filtering, collecting precipitate, fully washing the obtained precipitate with absolute ethyl alcohol and deionized water, and drying for 8-12 h after washing to obtain loaded SnO2Carbon layer MoS of nanoparticles2Nanosheets;
and step 3: loading SnO obtained in the step 22Carbon layer MoS of nanoparticles2Uniformly spreading the nanosheets in a crucible, then placing the crucible in a tubular furnace filled with argon/oxygen mixed gas, heating for reaction, cooling to room temperature to obtain loaded SnO2Porous carbon layer MoS of nanoparticles2A composite material;
and 4, step 4: under the condition of continuous stirring, the loaded SnO obtained in the step 32Porous carbon layer MoS of nanoparticles2Adding the composite material into 5-15 mL of ethanol water solution, stirring for 50-60 min, carrying out vacuum filtration and depositing on the surface of a polypropylene diaphragm, and drying in a vacuum drying oven at 40-80 ℃ for 8-24 h to obtain the folded molybdenum disulfide composite material for the lithium-sulfur battery.
Preferably, the method comprises the following steps: and (3) during high-temperature carbonization in the step (1), raising the temperature from room temperature to 750-850 ℃ at a heating rate of 4-8 ℃/min, and keeping the temperature for 120-160 min.
Preferably, in step 1, the folds MoS2The preparation method of the nano sheet comprises the following steps: mixing Na2MoO4·2H2Adding O into ultrapure water, and uniformly mixing; adding L-cysteine, and performing ultrasonic dispersion for 5-15 minutes to obtain a suspension; heating the suspension for 22-26 h at 200-240 ℃ by using an autoclave, cooling, centrifuging, collecting precipitates in the suspension, alternately washing by using deionized water and absolute ethyl alcohol, and drying for 10-14 h to obtain powder; uniformly mixing the powder with hydrazine hydrate, keeping the mixture at the temperature of 90-100 ℃ for 4-6h by using an autoclave, cooling, filtering, collecting precipitate, washing, and annealing for 1-3h to obtain folded MoS2Nanosheets.
Preferably, the annealing temperature is 780-820 ℃.
Preferably, in the step 3, the volume ratio of the argon gas to the oxygen gas mixture is 97.5:2.5, and the reaction temperature is 430-470 ℃ during the temperature rise reaction, and the reaction lasts for 1-2 hours.
Preferably, in the step 3, during the heating reaction, the temperature is increased from 20-30 ℃ to 290-310 ℃ at a heating rate of 10 ℃/min, and then is increased from 290-310 ℃ to 430-470 ℃ at a heating rate of 3 ℃/min.
Preferably, in step 4, the volume ratio of the ethanol aqueous solution is 3: 7.
Preferably, in the step 4, the vacuum degree of the vacuum filtration is 0.03-0.08 Mpa, and the vacuum degree of the vacuum drying is 0.03-0.08 Mpa.
In the technical scheme, the prepared composite diaphragm for the lithium-sulfur battery comprises a base film and a modification layer, wherein the modification layer is used for performing unilateral modification on the base film, and one side of the composite diaphragm, which is provided with the modification layer, faces to the positive electrode of the battery and is arranged in the lithium-sulfur battery. The method can effectively fix polysulfide, inhibit shuttle effect of polysulfide, accelerate polysulfide electrochemical oxidation reduction kinetics, greatly improve active sulfur utilization rate, and further improve electrochemical performance of the lithium-sulfur battery.
(1) In the composite diaphragm, fold MoS is added2The nano-sheet has extremely large polar surface area and highly exposed active edge positions, so that polysulfide intermediates in the lithium sulfur battery can be effectively captured to inhibit the shuttle effect. Meanwhile, the catalyst can perform catalytic conversion on polysulfide and has higher capacity.
(2) The carbon layer is introduced into the composite diaphragm, so that the composite diaphragm is light in weight, the mechanical property of the material is improved, the conductive performance of the material is enhanced, the structure of an electrode is stabilized, the rapid transmission of lithium ions is facilitated, and the performance of a battery is optimized;
(3) wherein the carbon layer is a porous carbon layer, further improves the ion transmission rate, increases the specific surface area of the material, and enhances MoS2Active site exposure for preventing lithium atom aggregation during long-term use of batteryOn the negative electrode, dendrites are formed, which can increase the service life of the lithium-sulfur battery.
(4) In the composite diaphragm, SnO grows in situ on the surface of a carbon layer through hydrothermal reaction2Nanoparticles with enhanced binding energy and affinity to sulfur and polysulfide intermediates by S-Sn-O chemical bonds, SnO2The nanoparticles and the polar polysulfide have stronger adsorption effect, so that shuttling of the polysulfide is further inhibited, and the cycle performance of the lithium-sulfur battery is remarkably improved. The ionic conductivity and the migration number of the diaphragm are improved, the interfacial impedance between the diaphragm and an electrode is reduced, and the composite diaphragm has better rate performance.
(5) The invention takes a polypropylene diaphragm as a basal membrane, and SnO is adhered on a filter device by a low-speed suction filtration method2Porous carbon layer MoS of nanoparticles2And carrying out suction filtration on the base film by using the composite material so as to prepare the composite diaphragm for the lithium-sulfur battery. Due to the advantages of the modified material structure and composition, compared with the existing polypropylene diaphragm, the composite diaphragm obtained by the invention can obviously improve the capacity of the lithium-sulfur battery and the rate capability of the battery under the same rate condition, and well solve the problems caused by the shuttle effect.
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.
Example 1:
step 1: mixing Na2MoO4·2H2O (0.06mol/L) was added to 45mL of ultrapure water and mixed well. Then, carrying out ultrasonic dispersion on L-cysteine (0.46mol/L) for 10 minutes to obtain a suspension; the suspension was heated at 220 ℃ for 24h with an autoclave. Cooling, centrifuging, collecting precipitate, washing with deionized water and anhydrous ethanol for several times, drying for 12 hr, and mixing the powder with waterHydrazine (80%) in a ratio of 1: 20, keeping the mixture at 95 ℃ for 5 hours by using a high-pressure kettle, cooling to room temperature, filtering, collecting precipitate, washing, annealing at 800 ℃ for 2 hours to obtain folded MoS2Nanosheets.
Step 2: weighing 200mg of tris (hydroxymethyl) aminomethane, adding 100mL of ultrapure water, adding 0.1mol/L dilute hydrochloric acid to adjust pH to 8.5, stirring for 22min to obtain solution, and adding fold MoS2Immersing the nano-sheets into the prepared solution, then adding 167mg of dopamine hydrochloride, and reacting for 12h at room temperature to obtain poly-dopamine-modified folded MoS2Nanosheets; in N2And (3) carrying out high-temperature carbonization under protection, raising the temperature from room temperature to 800 ℃ at the heating rate of 6 ℃/min, keeping the temperature for 140min, and cooling to room temperature to obtain the carbon-layer-modified MoS2Nanosheets.
And step 3: the resulting carbon layer-modified MoS2Dissolving 0.1g of nano-sheets in 78ml of deionized water, and uniformly stirring; ultrasonic dispersion is carried out for 2 hours; after dispersion, 0.4381g of SnCl was added4·5H2Stirring O and 0.3498g NaOH for 20min, transferring the obtained mixed solution into a stainless steel autoclave with a PTFE liner for reaction at 180 ℃ for 18 h; cooling to room temperature, filtering, collecting precipitate, washing the obtained precipitate with anhydrous ethanol and deionized water, and drying for 10h to obtain adhered SnO2Carbon layer MoS of nanoparticles2Nanosheets.
And 4, step 4: will adhere to SnO2Carbon layer MoS of nanoparticles20.2g of nano-sheets are evenly paved in a corundum crucible with the thickness of 5cm multiplied by 2cm, then the corundum crucible is placed in a tubular furnace filled with argon/oxygen mixed gas, the volume ratio of argon to oxygen is 97.5:2.5, the reaction is carried out for 1.5 hours at the temperature of 450 ℃, the temperature is increased from 25 ℃ to 300 ℃ at the temperature increasing rate of 10 ℃/min, then the temperature is increased from 300 ℃ to 450 ℃ at the temperature increasing rate of 3 ℃/min, and the reaction is cooled to the room temperature, so that the adhered SnO is obtained2Porous carbon layer MoS of nanoparticles2A composite material.
And 5: SnO is adhered under continuous stirring2Porous carbon layer MoS of nanoparticles2CompoundingAdding the material into 10mL of ethanol aqueous solution, continuously stirring for 55min, carrying out vacuum filtration and deposition on the surface of the polypropylene diaphragm, controlling the vacuum degree of the vacuum filtration at 0.06MPa, drying in a vacuum drying oven at 60 ℃ for 12h, and controlling the vacuum degree of the vacuum drying at 0.06MPa to obtain the composite diaphragm for the lithium-sulfur battery. When the MoS is wrinkled2When the concentration of the nano sheet is 0.1mg/mL, the thickness of the corresponding modification layer is 320 nm.
Example 2:
step 1: mixing Na2MoO4·2H2O (0.06mol/L) was added to 45mL of ultrapure water and mixed well. Then, carrying out ultrasonic dispersion on L-cysteine (0.46mol/L) for 5 minutes to obtain a suspension; the suspension was heated at 200 ℃ for 22h with an autoclave. The precipitate in suspension was cooled, centrifuged, collected and washed several times with deionized water and absolute ethanol alternately, dried for 10h, and the powder was mixed with hydrazine hydrate (80%) in a ratio of 1: 20, keeping the mixture at 95 ℃ for 4 hours by using a high-pressure kettle, cooling the mixture to room temperature, filtering the mixture, collecting precipitates, washing and annealing the precipitates, wherein the annealing temperature is 780 ℃ and the annealing time is 1 hour, and obtaining folded MoS after the treatment2Nanosheets.
Step 2: weighing 200mg of tris (hydroxymethyl) aminomethane, adding 100mL of ultrapure water, adding 0.1mol/L dilute hydrochloric acid to adjust pH to 8, stirring for 20min to obtain a solution, and adding MoS to the wrinkles2Immersing the nano-sheets into the prepared solution, then adding 167mg of dopamine hydrochloride, and reacting for 10h at room temperature to obtain poly-dopamine-modified folded MoS2Nanosheets; in N2And (3) carrying out high-temperature carbonization under protection, raising the temperature from room temperature to 750 ℃ at a heating rate of 4 ℃/min, keeping the temperature for 120min, and cooling to room temperature to obtain the carbon-layer-modified MoS2Nanosheets.
And step 3: the resulting carbon layer-modified MoS2Dissolving 0.1g of nano-sheets in 78ml of deionized water, and uniformly stirring; ultrasonic dispersion is carried out for 1.5 h; after dispersion, 0.4381g of SnC was addedl4·5H2Stirring O and 0.3498g NaOH for 18min, transferring the obtained mixed solution into a stainless steel autoclave with a PTFE liner for reaction at the temperature of 170 ℃ for 16 h; cooling to room temperature, filtering and collectingCollecting precipitate, washing the precipitate with anhydrous ethanol and deionized water, and drying for 8 hr to obtain adhered SnO2Carbon layer MoS of nanoparticles2Nanosheets.
And 4, step 4: will adhere to SnO2Carbon layer MoS of nanoparticles20.2g of nano-sheets are evenly paved in a corundum crucible with the thickness of 5cm multiplied by 2cm, then the corundum crucible is placed in a tubular furnace filled with argon/oxygen mixed gas, the volume ratio of argon to oxygen is 97.5:2.5, the reaction is carried out for 1 hour at the temperature of 430 ℃, the temperature is increased from 20 ℃ to 290 ℃ at the temperature increasing rate of 10 ℃/min, then the temperature is increased from 290 ℃ to 430 ℃ at the temperature increasing rate of 3 ℃/min, and the reaction is cooled to the room temperature, so that the adhered SnO is obtained2Porous carbon layer MoS of nanoparticles2A composite material.
And 5: SnO is adhered under continuous stirring2Porous carbon layer MoS of nanoparticles2Adding the composite material into 5mL of ethanol aqueous solution, continuously stirring for 50min, performing vacuum filtration and deposition on the surface of a polypropylene diaphragm, controlling the vacuum degree of the vacuum filtration at 0.03Mpa, drying in a vacuum drying oven at 40 ℃ for 10h, controlling the vacuum degree of the vacuum drying at 0.03Mpa to obtain the composite diaphragm for the lithium-sulfur battery, and when the MoS is folded, performing vacuum filtration on the composite diaphragm2When the concentration of the nano sheet is 0.2mg/mL, the thickness of the corresponding modification layer is 430 nm.
Example 3:
step 1: mixing Na2MoO4·2H2O (0.06mol/L) was added to 45mL of ultrapure water and mixed well. Then, carrying out ultrasonic dispersion on L-cysteine (0.46mol/L) for 15 minutes to obtain a suspension; the suspension was heated at 240 ℃ for 26h with an autoclave. The precipitate in suspension was cooled, centrifuged, collected and washed several times with deionized water and absolute ethanol alternately, dried for 14h, and the powder was mixed with hydrazine hydrate (80%) in a ratio of 1: 20, keeping the mixture at 100 ℃ for 6 hours by using a high-pressure kettle, cooling the mixture to room temperature, filtering the mixture, collecting precipitates, washing and annealing the precipitates, wherein the annealing temperature is 800 ℃, the annealing time is 3 hours, and the folded MoS is obtained after the treatment2Nanosheets.
Step 2: weighing 200mg of tris (hydroxymethyl) aminomethane, adding 100mL of ultrapure water, and adding 0.1mol/L diluted hydrochloric acid to adjust pH valueStirring for 24min to obtain solution, and mixing the solution with MoS2Immersing the nano-sheets into the prepared solution, then adding 167mg of dopamine hydrochloride, and reacting for 14h at room temperature to obtain poly-dopamine-modified folded MoS2Nanosheets; in N2And (3) carrying out high-temperature carbonization under protection, raising the temperature from room temperature to 850 ℃ at the heating rate of 8 ℃/min, keeping the temperature for 160min, and cooling to room temperature to obtain the carbon-layer-modified MoS2Nanosheets.
And step 3: the resulting carbon layer-modified MoS2Dissolving 0.1g of nano-sheets in 78ml of deionized water, and uniformly stirring; ultrasonic dispersion is carried out for 2.5 h; after dispersion, 0.4381g of SnC was addedl4·5H2Stirring O and 0.3498g NaOH for 22min, transferring the obtained mixed solution into a stainless steel autoclave with a PTFE liner for reaction at the temperature of 190 ℃ for 20 h; cooling to room temperature, filtering, collecting precipitate, washing the obtained precipitate with anhydrous ethanol and deionized water, and drying for 12h to obtain adhered SnO2Carbon layer MoS of nanoparticles2Nanosheets.
And 4, step 4: will adhere to SnO2Carbon layer MoS of nanoparticles20.2g of nanosheet is evenly paved in a corundum crucible with the thickness of 5cm multiplied by 2cm, then the crucible is placed in a tubular furnace filled with argon/oxygen mixed gas, the volume ratio of argon to oxygen is 97.5:2.5, the nanosheet reacts for 2 hours at the temperature of 470 ℃, the temperature is increased from 30 ℃ to 310 ℃ at the temperature increasing rate of 10 ℃/min, and then the nanosheet is increased from 310 ℃ to 470 ℃ at the temperature increasing rate of 3 ℃/min. Cooling to room temperature to obtain adhered SnO2Porous carbon layer MoS of nanoparticles2A composite material.
And 5: SnO is adhered under continuous stirring2Porous carbon layer MoS of nanoparticles2Adding the composite material into 15mL of ethanol aqueous solution, continuously stirring for 70min, carrying out vacuum filtration and deposition on the surface of the polypropylene diaphragm, controlling the vacuum degree of the vacuum filtration at 0.08MPa, drying in a vacuum drying oven at 70 ℃ for 14h, and controlling the vacuum degree of the vacuum drying at 0.08MPa to obtain the composite diaphragm for the lithium-sulfur battery. When the MoS is wrinkled2When the concentration of the nanosheet is 0.3mg/mL, the thickness of the corresponding modified layer is 580 nm.
Example 4:
step 1: mixing Na2MoO4·2H2O (0.06mol/L) was added to 45mL of ultrapure water and mixed well. Then, uniformly mixing L-cysteine (0.46mol/L) to obtain a suspension; the suspension was heated at 220 ℃ for 24h with an autoclave. The precipitate in suspension was cooled, centrifuged, collected and washed several times with deionized water and absolute ethanol alternately, dried for 12h, and the powder was mixed with hydrazine hydrate (80%) in a ratio of 1: 20, keeping the mixture at 95 ℃ for 5 hours by using a high-pressure kettle, cooling to room temperature, filtering, collecting precipitate, washing, annealing at 800 ℃ for 2 hours to obtain folded MoS2Nanosheets.
Step 2: under the condition of continuous stirring, the folds MoS2Adding the nanosheets into 10mL of ethanol water solution, continuously stirring for 60min, carrying out vacuum filtration and deposition on the surface of the polypropylene diaphragm, controlling the vacuum degree of the vacuum filtration to be 0.06MPa, drying in a vacuum drying oven at 60 ℃ for 12h, and controlling the vacuum degree of the vacuum drying to be 0.06MPa, thereby obtaining the composite diaphragm for the lithium-sulfur battery.
When the MoS is wrinkled2When the concentration of the nanosheet is 0.1mg/mL, the thickness of the corresponding modified layer is 245 nm.
Example 5:
the specific methods and parameters were as in example 4, with the following differences: when the MoS is wrinkled2When the concentration of the nano sheet is 0.2mg/mL, the thickness of the corresponding modification layer is 360 nm.
Example 6:
the specific methods and parameters were as in example 4, with the following differences: when the MoS is wrinkled2When the concentration of the nanosheet is 0.3mg/mL, the thickness of the corresponding modified layer is 515 nm.
Example 7:
step 1: mixing Na2MoO4·2H2O (0.06mol/L) was added to 45mL of ultrapure water and mixed well. Then, carrying out ultrasonic dispersion on L-cysteine (0.46mol/L) for 10 minutes to obtain a suspension; the suspension was heated at 220 ℃ for 24h with an autoclave. Cooling, centrifuging, collecting precipitate in suspension, and mixing with deionized water and anhydrous ethanolInstead of washing several times, drying for 12h, the powder was mixed with hydrazine hydrate (80%) in a 1: 20, keeping the mixture at 95 ℃ for 5 hours by using a high-pressure kettle, cooling to room temperature, filtering, collecting precipitate, washing, annealing at 800 ℃ for 2 hours to obtain folded MoS2Nanosheets.
Step 2: weighing 200mg of tris (hydroxymethyl) aminomethane, adding 100mL of ultrapure water, adding 0.1mol/L dilute hydrochloric acid to adjust pH to 8.5, stirring for 22min to obtain solution, and adding fold MoS2Immersing the nano-sheets into the prepared solution, then adding 167mg of dopamine hydrochloride, and reacting for 12h at room temperature to obtain poly-dopamine-modified folded MoS2Nanosheets; in N2And (3) carrying out high-temperature carbonization under protection, raising the temperature from room temperature to 800 ℃ at the heating rate of 6 ℃/min, keeping the temperature for 140min, and cooling to room temperature to obtain the carbon-layer-modified MoS2Nanosheets.
And step 3: MoS modified with carbon layer20.2g of nano-sheets are evenly paved in a corundum crucible with the thickness of 5cm multiplied by 2cm, then the corundum crucible is placed in a tubular furnace filled with argon/oxygen mixed gas, the volume ratio of argon to oxygen is 97.5:2.5, the reaction is carried out for 1.5 hours at the temperature of 450 ℃, the temperature is increased from 25 ℃ to 300 ℃ at the temperature increasing rate of 10 ℃/min, then the temperature is increased from 300 ℃ to 450 ℃ at the temperature increasing rate of 3 ℃/min, and the reaction is cooled to the room temperature, so that the porous carbon layer MoS is obtained2A composite material.
And 5: stirring the porous carbon layer MoS continuously2Adding the composite material into 10mL of ethanol aqueous solution, continuously stirring for 55min, carrying out vacuum filtration and deposition on the surface of the polypropylene diaphragm, controlling the vacuum degree of the vacuum filtration at 0.06MPa, drying in a vacuum drying oven at 60 ℃ for 12h, and controlling the vacuum degree of the vacuum drying at 0.06MPa to obtain the composite diaphragm for the lithium-sulfur battery. When the MoS is wrinkled2When the concentration of the nano sheet is 0.1mg/mL, the thickness of the corresponding modification layer is 278 nm.
Example 8:
the specific methods and parameters were as in example 7, with the following differences: when the MoS is wrinkled2When the concentration of the nano sheet is 0.2mg/mL, the thickness of the corresponding modification layer is 399 nm.
Example 9:
the specific methods and parameters were as in example 7, with the following differences: when the MoS is wrinkled2When the concentration of the nanosheet is 0.3mg/mL, the thickness of the corresponding modified layer is 546 nm.
Example 10:
lithium sulfur batteries were made using unmodified polypropylene separators.
Experiment:
the separator prepared in examples 1 to 10 was used to assemble a lithium sulfur battery, and the specific method was:
fully mixing conductive carbon black SuperP and sublimed sulfur in a mass ratio of 1:3, and treating the mixture at the high temperature of 155 ℃ for 12 hours to obtain a product recorded as CB/S. Fully mixing CB/S, SuperP and LA133 in a mass ratio of 8:1:1 in a ball mill to obtain slurry, coating the slurry on an aluminum foil by using a blade coater, and controlling the thickness to ensure that the area sulfur loading is about 2mg cm-2Drying to obtain a positive electrode; the cathode was a commercial lithium plate and the electrolyte was 1M lithium bistrifluoromethanesulfonimide +2 wt% lithium nitrate +1M1, 2-dimethoxyethane +1M1, 3-dioxolane. 1, 2-dimethoxyethane and 1, 3-dioxolane were mixed in equal volumes.
The test is carried out on a Wuhan blue electricity test system, the charging and discharging voltage range is 1.7-2.8V, and the current density is 0.2C (1C is 1675 mAh.g)-1). The results obtained are as follows:
the following tables show the initial capacity and the capacity after 100 cycles at 0.2C for examples 1-10:
Figure BDA0003282315490000081
the following tables show the capacities of examples 1 to 10 under different multiplying power conditions:
Figure BDA0003282315490000091
and (4) conclusion: as can be seen from the data in the table: unmodified polypropylene diaphragm battery capacity is less than that of use example 1 to3, preparing the lithium-sulfur battery; the rate capability was inferior to that of the lithium-sulfur batteries prepared in examples 1 to 3. Ultra-thin (2-5 nm) folded MoS2The nano-sheet has extremely large polar surface area and highly exposed active edge positions, so that polysulfide intermediates in the lithium-sulfur battery can be effectively captured to inhibit shuttle effect, and polysulfide can be catalytically converted.
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 folded molybdenum disulfide composite diaphragm for a lithium-sulfur battery is characterized by comprising the following steps: the method comprises the following steps:
step 1: adding ultrapure water into trihydroxymethyl aminomethane, adjusting the pH value to 8-9 with dilute hydrochloric acid, stirring for 20-24 min to obtain a solution, and preparing the folded MoS2Immersing the nanosheets into the solution, adding dopamine hydrochloride, and reacting at room temperature for 10-14 h to obtain polydopamine modified MoS2Nanosheets; then transferring to a nitrogen environment, carbonizing at high temperature, and cooling to obtain the MoS modified by the carbon layer2Nanosheets;
step 2: MoS modified by the carbon layer obtained in the step 12Stirring and dissolving the nanosheets in deionized water, and uniformly stirring; ultrasonically dispersing for 1.5-2.5 h, and adding SnCl4·5H2Stirring O and NaOH for 18-22 min, and reacting the obtained mixed solution in an autoclave at the reaction temperature of 170-190 ℃ for 16-20 h; cooling to room temperature, filtering, collecting precipitate, fully washing the obtained precipitate with absolute ethyl alcohol and deionized water, and drying for 8-12 h after washing to obtain loaded SnO2Carbon layer MoS of nanoparticles2Nanosheets;
and step 3: loading SnO obtained in the step 22Carbon layer MoS of nanoparticles2Uniformly spreading the nanosheets in a crucible, then placing the crucible in a tubular furnace filled with argon/oxygen mixed gas, heating for reaction, cooling to room temperature to obtain loaded SnO2Porous carbon layer MoS of nanoparticles2A composite material;
and 4, step 4: under the condition of continuous stirring, the loaded SnO obtained in the step 32Porous carbon layer MoS of nanoparticles2Adding the composite material into 5-15 mL of ethanol water solution, stirring for 50-60 min, carrying out vacuum filtration and depositing on the surface of a polypropylene diaphragm, and drying in a vacuum drying oven at 40-80 ℃ for 8-24 h to obtain the folded molybdenum disulfide composite material for the lithium-sulfur battery.
2. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 1, wherein: and (3) during high-temperature carbonization in the step (1), raising the temperature from room temperature to 750-850 ℃ at a heating rate of 4-8 ℃/min, and keeping the temperature for 120-160 min.
3. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 1, wherein: in step 1, the folded MoS2The preparation method of the nano sheet comprises the following steps: mixing Na2MoO4·2H2Adding O into ultrapure water, and uniformly mixing; adding L-cysteine, and performing ultrasonic dispersion for 5-15 minutes to obtain a suspension; heating the suspension for 22-26 h at 200-240 ℃ by using an autoclave, cooling, centrifuging, collecting precipitates in the suspension, alternately washing by using deionized water and absolute ethyl alcohol, and drying for 10-14 h to obtain powder; uniformly mixing the powder with hydrazine hydrate, keeping the mixture at the temperature of 90-100 ℃ for 4-6h by using an autoclave, cooling, filtering, collecting precipitate, washing, and annealing for 1-3h to obtain folded MoS2Nanosheets.
4. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 3, wherein: the annealing temperature is 780-820 ℃.
5. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 1, wherein: in the step 3, the volume ratio of the argon gas to the oxygen gas mixture is 97.5:2.5, and the reaction temperature is 430-470 ℃ for 1-2 hours during the heating reaction.
6. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 5, wherein: in the step 3, during the heating reaction, the temperature is increased from 20-30 ℃ to 290-310 ℃ at a heating rate of 10 ℃/min, and then is increased from 290-310 ℃ to 430-470 ℃ at a heating rate of 3 ℃/min.
7. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 1, wherein: in the step 4, the volume ratio of the ethanol aqueous solution is that the ratio of water to ethanol is 3: 7.
8. The method for preparing the wrinkled molybdenum disulfide composite membrane for the lithium-sulfur battery according to claim 1, wherein: in the step 4, the vacuum degree of the vacuum filtration is 0.03-0.08 MPa, and the vacuum degree of the vacuum drying is 0.03-0.08 MPa.
9. The separator prepared by the method for preparing the corrugated molybdenum disulfide composite separator for the lithium-sulfur battery according to any one of claims 1 to 8.
CN202111135744.0A 2021-09-27 2021-09-27 Folded molybdenum disulfide composite diaphragm for lithium-sulfur battery and preparation method thereof Withdrawn CN113871792A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114927830A (en) * 2022-05-26 2022-08-19 江苏厚生新能源科技有限公司 Folded MXene modified diaphragm for lithium ion battery and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114927830A (en) * 2022-05-26 2022-08-19 江苏厚生新能源科技有限公司 Folded MXene modified diaphragm for lithium ion battery and preparation method thereof
CN114927830B (en) * 2022-05-26 2023-09-01 江苏厚生新能源科技有限公司 Fold MXene modified diaphragm for lithium ion battery and preparation method thereof

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