WO2024069635A1 - Method for producing a separator and a metal-sulfur battery comprising the separator - Google Patents

Method for producing a separator and a metal-sulfur battery comprising the separator Download PDF

Info

Publication number
WO2024069635A1
WO2024069635A1 PCT/IN2022/051095 IN2022051095W WO2024069635A1 WO 2024069635 A1 WO2024069635 A1 WO 2024069635A1 IN 2022051095 W IN2022051095 W IN 2022051095W WO 2024069635 A1 WO2024069635 A1 WO 2024069635A1
Authority
WO
WIPO (PCT)
Prior art keywords
separator
coating
coupling agent
group
nanoparticles
Prior art date
Application number
PCT/IN2022/051095
Other languages
French (fr)
Inventor
Malay PRAMANIK
Krishnamurthy Narayanan
Bojja RAMACHANDRARAO
Original Assignee
Hindustan Petroleum Corporation Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hindustan Petroleum Corporation Limited filed Critical Hindustan Petroleum Corporation Limited
Publication of WO2024069635A1 publication Critical patent/WO2024069635A1/en

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • 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
    • H01M50/443—Particulate material
    • 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
    • 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
    • H01M2300/00—Electrolytes
    • H01M2300/0085—Immobilising or gelification of electrolyte
    • 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

Definitions

  • the present invention relates to a method for producing a separator for providing electrical isolation in a metal-sulfur battery. Further, the present invention also relates to a separator and a metal-sulfur battery comprising the separator.
  • Metal-sulfur batteries are attracting increasing research interest for the next generation energy storage devices owing to their high theoretical specific capacity as well as high natural abundance and low toxicity of sulfur. Apart from natural resources such as pyrites, million metric tons of sulfur is produced as byproduct in petroleum refineries globally. Despite the attractive merits of high abundance, low cost, and high specific capacity, the large-scale production of sulfurbased batteries is hindered mainly due to the uncontrolled diffusion of soluble polysulfide intermediates between cathode and anode through separators in the battery. This causes irreversible battery capacity loss known as polysulfide shuttle effect or polysulfide shuttling.
  • Separators also known as diaphragm, in a metal-sulfur battery function as a physical barrier between anode and cathode.
  • the separators also function as an electrolyte reservoir for ionic transport.
  • Traditional separators which are made of polypropylene have been found to be less effective in mitigating polysulfide shuttling.
  • Various strategies have been developed to improve the performance of metal-sulfur batteries, such as the structure of the sulfur cathode, the electrolyte, the modified separator, and metal protection. In these strategies, the improvement of separator not only ensures unhindered transport of metal ions, but also prevents dissolution of polysulfides into the electrolyte, further increasing the utilization of the active sulfur cathode in lithium sulfur batteries.
  • CN 113690546 A discloses a lithium-sulfur battery diaphragm and a preparation method thereof.
  • the lithium-sulfur battery consists of an interlayer and a diaphragm which are laminated.
  • the interlayer is a reticular film formed by carbon nanofibers
  • the diaphragm is a reticular film formed by non-conductive polymer nanofibers.
  • preparation of TiCL and SiCh modified film in presence of non-conducting polymers such as polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and polyvinylpyrrolidone by electrospinning and subsequent high temperature sintering is disclosed.
  • the film thus obtained is used as a separator for lithiumsulfur battery.
  • the complex electrospinning methodology and energy intensive (high temperature) sintering render the separator less commercially viable.
  • CN111370620 A describes a functional diaphragm of a lithium-sulfur battery and a preparation method thereof.
  • the functional diaphragm is a modified diaphragm of a non-polar diaphragm, namely, nanomaterials with different charges with porous structures being coated on two sides of the non-polar lithium-sulfur battery diaphragm.
  • the functional diaphragm has been synthesized using ex-situ method. For this, mesoporous silica is obtained under high temperature calcination process (500°C to 700°C) by removing an organic template. Subsequently, the mesoporous silica is functionalized using aminosilane at refluxing condition.
  • the high temperature process disclosed herein is energy intensive and is an additional step for functionalizing the separator. Further, the ex-situ method is less efficient due to the phase difference between reactant molecules - silica in solid phase whereas aminosilane and solvent in liquid phase.
  • the presently claimed invention relates to a method for producing a separator for providing electrical isolation in a metal-sulfur battery.
  • the method comprises obtaining functionalized silica nanoparticles at a temperature ranging between 20°C to 50°C by reacting a silica precursor and a coupling agent.
  • the weight ratio between the silica precursor and the coupling agent is in the range of 1.0:6.0 to 6.0: 1.0.
  • the method also comprises coating on a polymeric material with dispersed nanoparticles to obtain the separator.
  • the dispersed nanoparticles are obtained by dispersing the functionalized silica nanoparticles in a binder solution.
  • the method comprises mixing a pH adjusting agent with an aqueous solvent to obtain a reaction solvent having a pH ranging between 10 to 13.
  • the pH adjusting agent is added in an amount ranging between 0.1 vol.% to 10.0 vol.% based on the total volume of the reaction solvent.
  • the method also comprises reacting the silica precursor and the coupling agent in the reaction solvent at a temperature ranging between 20°C to 50°C to obtain a solution comprising the functionalized silica nanoparticles.
  • the method further comprises isolating the functionalized silica nanoparticles from the solution.
  • the silica precursor is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate.
  • the silica precursor is tetraethyl orthosilicate.
  • the coupling agent is a silane coupling agent selected from the group consisting of 3-aminopropyl triethoxysilane, 3 -mercaptopropyl trimethoxysilane, 3- cyanopropyl triethoxysilane, and triethoxy(ethyl)silane.
  • the polymeric material comprises polypropylene, polyethylene or a composite thereof.
  • the binder is selected from the group consisting of carboxymethyl cellulose, styrene -butadiene rubber and polyvinylidene fluoride, in at least one solvent selected from the group consisting of water, ethanol, propanol, N-methyl-2-pyrrolidone, and acetone.
  • the pH adjusting agent is selected from the group consisting of sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethyl ammonium hydroxide.
  • no surfactant is present.
  • the coating is selected from doctor’s blade coating, dip coating, spin coating, microgravure coating, electrospinning, comma coating, or reverse comma coating.
  • the presently claimed invention relates to the separator as obtained hereinabove.
  • the present invention relates to a metal-sulfur battery comprising the above separator.
  • the separator is disposed between at least one positive electrode and at least one negative electrode.
  • Figure 1 shows a Fourier Transform Infrared Spectroscopy (FTIR) spectrum of amine functional silica nanoparticles.
  • FTIR Fourier Transform Infrared Spectroscopy
  • Figures 2(a) and 2(b) show Scanning Electron Microscope (SEM) images of conventional polypropylene separator.
  • Figures 2(c) and 2(d) show Scanning Electron Microscope (SEM) images of amine functional silica nanoparticle modified polypropylene separator.
  • Figure 3(a) shows Galvanostatic charge-discharge profile of a lithium-sulfur cell with a conventional polypropylene separator (a-1) and amine functional silica nanoparticle modified polypropylene separator (a-2).
  • Figure 3(b) shows Galvanostatic charge-discharge profile of a lithium- sulfur cell with conventional polypropylene separator.
  • Figure 3(c) Galvanostatic charge-discharge profile of amine functional silica nanoparticle modified polypropylene separator.
  • Figure 4 shows long term cycling performance of lithium-sulfur cell with (a) a conventional polypropylene separator, and (b) amine functional silica nanoparticles modified polypropylene separator.
  • steps of a method or use or assay there is no time or time interval coherence between the steps, that is, the steps may be carried out simultaneously or there may be intervals of seconds, minutes, hours, days, weeks, months, or even years between such steps, unless otherwise indicated in the application as set forth hereinabove or below.
  • An aspect of the presently claimed invention is directed to a method for producing a separator for providing electrical isolation in a metal-sulfur battery.
  • the method comprises the steps of:
  • the terms "separator” and “diaphragm” are synonymous. Further, the present invention contains no surfactant. Said otherwise, no surfactant is added, in any manner and at any stage or steps of the method described herein.
  • step of obtaining functionalized silica nanoparticle by reacting the silica precursor and the coupling agent in step (A), as above, is referred as in-situ grafting technique.
  • functionalization of silica precursor with coupling agent is conducted in same phase or in a single step.
  • any reference to "battery” in the present context also includes portable batteries such as, but not limited to, different types and kinds of cells.
  • the metal-sulfur battery includes rechargeable batteries such as, but not limited to, lithium-sulfur battery, sodium-sulfur battery, and potassium-sulfur battery. In another embodiment, the metal-sulfur battery is lithium-sulfur battery.
  • the silica precursor is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate. In another embodiment, the silica precursor is tetraethyl orthosilicate.
  • the coupling agent is used to increase adhesive strength and is characterized by having two or more functional groups.
  • the coupling agent may be a material in which one functional group forms a chemical bond via reaction with a hydroxyl or carboxyl group present on the surface of the silicon-, tin- or graphite -based active material, and the other functional group forms a chemical bond via reaction with the polymer binder.
  • the coupling agent may include, but are not limited to, silane-based coupling selected from the group consisting of triethoxysilylpropyl tetrasulfide, 3 -mercaptopropyl triethoxysilane, 3-aminopropyl triethoxysilane, chloropropyl triethoxysilane, vinyl triethoxysilane, methacryloxypropyl triethoxysilane, glycidoxypropyl triethoxysilane, isocyanatopropyl triethoxy silane, 3-cyanopropyl triethoxysilane and triethoxy(ethyl)silane.
  • silane-based coupling selected from the group consisting of triethoxysilylpropyl tetrasulfide, 3 -mercaptopropyl triethoxysilane, 3-aminopropyl triethoxysilane, chloropropyl triethoxysilane, vinyl tri
  • the coupling agent is selected from the group consisting of 3- aminopropyl triethoxysilane, 3 -mercaptopropyl trimethoxysilane, 3-cyanopropyl triethoxysilane, and triethoxy(ethyl)silane.
  • the coupling agent is 3-aminopropyl triethoxysilane.
  • the functional groups from the coupling agent are grafted on the surface of the dispersed nanoparticles.
  • the amount of the functional groups on the dispersed nanoparticles is in the range of 20 wt.% to 70 wt.% determined using CHNS (Carbon Nitrogen Hydrogen Sulfur) analysis.
  • the step (A), as described herein, comprises the following sub-steps: (Al) mixing a pH adjusting agent with an aqueous solvent to obtain a reaction solvent having a pH ranging between 10 to 13, wherein the pH adjusting agent is added in an amount ranging between 0.1 vol.% to 10.0 vol.% based on the total volume of the reaction solvent,
  • step (A3) isolating the functionalized silica nanoparticles from the solution obtained in step (A2).
  • the pH adjusting agent is selected from the group consisting of sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethyl ammonium hydroxide.
  • the pH adjusting agent is sodium hydroxide or ammonium hydroxide.
  • Suitable amounts of the pH adjusting agents are mixed with the aqueous solvent to obtain the reaction solvent at a pH ranging between 10 to 13, or in between 11 to 13.
  • the pH adjusting agent is added in an amount ranging between 0.5 vol.% to 10.0 vol.%, or in between 0.5 vol.% to 8.0 vol.%, or in between 1.0 vol.% to 8.0 vol.% based on the total volume of the reaction solvent.
  • the pH adjusting agent is added in amounts ranging between 1.0 vol.% to 7.0 vol.%, or in between 2.0 vol.% to 7.0 vol.%, or in between 3.0 vol.% to 7.0 vol.%, or in between 4.0 vol.% to 7.0 vol.%.
  • mixing is carried out using suitable mixing means such as, but not limited to, a stirrer.
  • suitable stirring rate or rpm is known to persons skilled in the art and hence the presently claimed invention is not limited by the same.
  • the aqueous solvent comprises at least one solvent in water.
  • the solvent is selected from the group consisting of ethanol, propanol, N-methyl-2-pyrrolidone, and acetone. Suitable amounts of solvent are known to persons skilled in the art and hence the presently claimed invention is not limited by the same.
  • Solution comprising functionalized silica nanoparticles is obtained upon reacting the silica precursor with the coupling agent in the reaction solvent.
  • the weight ratio between the silica precursor and the coupling agent is in the range of 1.0:5.5 to 5.5: 1.0, or in between 1.0:5.0 to 5.0:1.0, or in between 1.0:4.5 to 4.5: 1.0, or in between 1.0:4.0 to 4.0:1.0, or in between 1.0:3.5 to 3.5: 1.0.
  • the weight ratio is in between 1.0:3.0 to 3.0: 1.0, or in between 1.0:2.5 to 2.5:1.0, or in between 1.0:2.0 to 2.0:1.0.
  • the reaction is carried out at moderate temperature ranging between 20°C to 50°C for obtaining the solution comprising the functionalized silica nanoparticles.
  • the solution obtained is a homogeneous suspension of dispersed nanoparticles.
  • the functionalized silica nanoparticles are isolated and subjected to step (B), described herein.
  • Suitable techniques for isolating functionalized silica nanoparticles include, but are not limited to, one or more of centrifugation, washing, drying, and filtering.
  • the size of the functionalized silica nanoparticles obtained in accordance with the presently claimed invention is less than 400 nm. In another embodiment, the size ranges in between 200 nm to 350 nm as determined using Scanning Electron Microscopy (SEM) technique. The size can further be controlled by varying the weight ratio between the silica precursor and the coupling agent.
  • the dispersed nanoparticles in step (B) are obtained by dispersing the functionalized silica nanoparticles in the binder.
  • Suitable binders for this purpose are selected from the group consisting of carboxymethyl cellulose, styrene-butadiene rubber and polyvinylidene fluoride.
  • the binder is pre-mixed with at least one solvent to obtain the binder solution.
  • the solvent used herein is selected from the group consisting of water, ethanol, propanol, N-methyl-2- pyrrolidone, and acetone.
  • the polymeric material comprises polypropylene (PP), polyethylene (PE) or a combination thereof.
  • PP polypropylene
  • PE polyethylene
  • the polymeric material is permeable to ions and polysulfides.
  • the resulting separator is permeable to ions but the polysulfide permeability is arrested significantly.
  • Suitable techniques for coating the polymeric material are selected from doctor’s blade coating, dip coating, spin coating, microgravure coating, electrospinning, comma coating, or reverse comma coating. Subsequently, the coated polymeric material is dried and the separator is obtained.
  • Still another aspect of the presently claimed invention is directed to a metal-sulfur battery comprising the separator described herein.
  • the separator is disposed between at least one positive electrode and at least one negative electrode.
  • Suitable electrolytes and materials of construction for the electrodes are well known to the person skilled in the art and hence, the presently claimed invention is not limited in terms of the choice and selection of the same.
  • suitable cathode may be made from a composite material obtained from, such as but not limited to, sulfur and activated carbon using known techniques.
  • electrolyte may be a mixture of various metals such as, but not limited to, lithium, sodium and the likes, in suitable salt forms such as, but not limited to, fluorosulphonamide, trifluorosulphonamide, nitrates, and the like in a suitable solvent.
  • suitable metal such as lithium may be used as anode material.
  • the separator obtained in accordance with the presently claimed invention is effective in mitigating poly sulfide shuttling and results in acceptable battery performance such as, but not limited to, improvement in cycle life, rate capability, polarization and overall capacity. Further, the separator obtained in accordance with the present invention consumes less energy and time and is cost effective, which renders it easy for carrying out scale up activities.
  • Silica precursor Tetraethyl orthosilicate obtained from Cisco Research Coupling agent 3 -aminopropyl triethoxysilane obtained from Aldrich Binder Carboxymethyl cellulose (CMC) obtained from SD Fine Chem
  • Galvanostatic charge/discharge experiments were carried out under a constant charge/discharge current density of 0.1 C within an applied voltage window ranging from 1.6 V to 2.8 V.
  • the capacitance retention experiments were carried out at a constant current density of 0.3 C in the applied voltage window of 1.6 V to 2.8 V for 100 charge/discharge cycles.
  • FTIR Fourier transform infrared spectroscopy
  • Figures 2(a) and 2(b) show the SEM image of the conventional polypropylene separator (PP) whereas the SEM image of AFSN-23A in accordance with the present invention is shown in Figures 2(c) and 2(d). From these SEM images, elliptical pores of 100 nm to 200 nm are clearly visible on the surface of the conventional separator which is not suitable to arrest the polysulfide shuttling. On the contrary, these pores are blocked with the amine functionalized silica nanoparticles which can store more electrolyte and restrict the polysulfide shuttling between the cathode and the anode of the lithium sulfur battery.
  • a cathode was prepared by mixing the above composite cathode material, super phosphorus and poly vinylidenedifluoride (PVDF) in a mass ratio of 8:1: 1 in N-methyl-2- pyrrolidone (NMP) solvent for 2-3 h. A slurry was obtained which was subsequently coated on an aluminum foil using doctor's blade technique and dried at 100-120°C for 2 h. The cathode was cut into 15 mm diameter with sulfur loading ranging between 2-5 mg/cm 2 .
  • PVDF poly vinylidenedifluoride
  • Coin-type cells (2032) were fabricated inside an argon-filled glovebox using the conventional separator and AFSN-23A separator in accordance with the present invention.
  • Several different metal foils (Li, Na etc.) were used as counter and reference electrode.
  • the electrolyte was a mixture of various metal (Li, Na etc.) salts such as flurosulphonamide (-Fsl), triflurosulphonamide (-TfSI) and nitrate (-NO3) in a solvent mixture of 1,2-dimethoxy ethane (DME) and 1,3-dioxalane (DOL) for different metal-sulfur batteries having the metal salt concentration ranging between 0.2 M to 1.0 M. Cycling tests were performed with these batteries within the potential window of 1.6 V-2.8 V at 0.3 C current rates over 100 cycles.
  • Electrochemical performance of the conventional separator and the AFSN-23A separator were carried out by Galvanostatic cycling performance experiment using the composite cathode and lithium metal as anode. The results are shown in Figures 3(a) to 3(c).
  • the initial discharge capacity was 1030 mAh/g and 730 mAh/g for the conventional separator and the AFSN-23A separator, respectively, at 0.1 C charging-discharging rate (refer Figure 3(a)).
  • the discharge capacity increases from 698 mAh/g to 745 mAh/g using the AFSN-23 A separator over the conventional separator when tested at 0.3 C charging-discharging rate (refer Figures 3(b) and 3(c)).
  • the presence of characteristic two voltage plateaus in the discharge curves can be ascribed to the two-step reaction of sulfur with lithium during the discharge process.
  • the cycling properties of the S/AC composite cathode in presence of different separators in Li-S cells at a rate of 0.3 C is shown in Figure 4.
  • the discharge capacity values varied between 745 mAh/g and 595 mAh/g for the first and hundredth cycle, respectively, using the AFSN-23A separator.
  • the discharge capacity values varied between 698 and 453 mAh/g for the first and hundredth cycles, respectively.
  • the decrease in specific capacity was observed as a smooth and gradual process, losing only 1.50 mAh/g per cycle for the AFSN-23A separator compared to 2.45 mAh/g for the conventional PP separator.
  • the improved capacity retention using the AFSN-23A separator can be attributed to the presence of amine functionalized silica nanoparticle in the polypropylene separator that retained the polysulfides, and inhibited the shuttle effect.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Cell Separators (AREA)

Abstract

The present invention relates to a method for producing a separator for providing electrical isolation in a metal-sulfur battery. Further, the present invention also relates to a separator and a metal-sulfur battery comprising the separator.

Description

METHOD FOR PRODUCING A SEPARATOR AND A METAL-SULFUR BATTERY
COMPRISING THE SEPARATOR
FIELD OF THE INVENTION:
[0001] The present invention relates to a method for producing a separator for providing electrical isolation in a metal-sulfur battery. Further, the present invention also relates to a separator and a metal-sulfur battery comprising the separator.
BACKGROUND OF THE INVENTION:
[0002] Metal-sulfur batteries are attracting increasing research interest for the next generation energy storage devices owing to their high theoretical specific capacity as well as high natural abundance and low toxicity of sulfur. Apart from natural resources such as pyrites, million metric tons of sulfur is produced as byproduct in petroleum refineries globally. Despite the attractive merits of high abundance, low cost, and high specific capacity, the large-scale production of sulfurbased batteries is hindered mainly due to the uncontrolled diffusion of soluble polysulfide intermediates between cathode and anode through separators in the battery. This causes irreversible battery capacity loss known as polysulfide shuttle effect or polysulfide shuttling.
[0003] Separators, also known as diaphragm, in a metal-sulfur battery function as a physical barrier between anode and cathode. The separators also function as an electrolyte reservoir for ionic transport. Traditional separators which are made of polypropylene have been found to be less effective in mitigating polysulfide shuttling. Various strategies have been developed to improve the performance of metal-sulfur batteries, such as the structure of the sulfur cathode, the electrolyte, the modified separator, and metal protection. In these strategies, the improvement of separator not only ensures unhindered transport of metal ions, but also prevents dissolution of polysulfides into the electrolyte, further increasing the utilization of the active sulfur cathode in lithium sulfur batteries.
[0004] CN 113690546 A discloses a lithium-sulfur battery diaphragm and a preparation method thereof. The lithium-sulfur battery consists of an interlayer and a diaphragm which are laminated. The interlayer is a reticular film formed by carbon nanofibers, and the diaphragm is a reticular film formed by non-conductive polymer nanofibers. In particular, preparation of TiCL and SiCh modified film in presence of non-conducting polymers such as polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and polyvinylpyrrolidone by electrospinning and subsequent high temperature sintering is disclosed. The film thus obtained is used as a separator for lithiumsulfur battery. The complex electrospinning methodology and energy intensive (high temperature) sintering render the separator less commercially viable.
[0005] CN111370620 A describes a functional diaphragm of a lithium-sulfur battery and a preparation method thereof. The functional diaphragm is a modified diaphragm of a non-polar diaphragm, namely, nanomaterials with different charges with porous structures being coated on two sides of the non-polar lithium-sulfur battery diaphragm. The functional diaphragm has been synthesized using ex-situ method. For this, mesoporous silica is obtained under high temperature calcination process (500°C to 700°C) by removing an organic template. Subsequently, the mesoporous silica is functionalized using aminosilane at refluxing condition. The high temperature process disclosed herein is energy intensive and is an additional step for functionalizing the separator. Further, the ex-situ method is less efficient due to the phase difference between reactant molecules - silica in solid phase whereas aminosilane and solvent in liquid phase.
[0006] Jing Li. et al. [ACS Appl. Mater. Interfaces, 2017] studied the fabrication of silica functionalized polypropylene separator by immersing polypropylene separator in hydrolysis solution of tetraethyl orthosilicate with assistance of TWEEN-80 which is a non-ionic surfactant. The presence of TWEEN-80 results in the silica nanoparticles being tightly clung to the polypropylene separator.
[0007] Other solutions for addressing polysulfide shuttling include placing a barrier layer between the positive electrode and diaphragm. This improves the utilization rate of the positive electrode active material of the metal-sulfur battery. Nevertheless, most of the barrier layers arranged at present have several limitations such as poor conductivity, unsatisfactory adsorption effect on polysulfide, poor wettability of electrolyte, poor thermal stability, and poor mechanical property. Further, the arrangement of a single barrier layer can also increase the assembly difficulty of the metal-sulfur battery, thereby increasing extra assembly cost and difficulty in scaling up for increased production. [0008] As evident above, the existing solutions for minimizing polysulfide shuttling have several limitations. For instance, the use of complicated material synthesis is either energy intensive or time consuming or costly due to the use of expensive rare earth elements which render difficulty while scaling up. Further, the existing solutions degrade the battery parameters such as cycle life, rate capability and overall capacity.
[0009] It was, therefore, an object of the presently claimed invention to provide a method for producing a separator effective in mitigating polysulfide shuttling and resulting in acceptable or improved metal-sulfur battery parameters such as cycle life, rate capability, polarization and overall capacity.
SUMMARY OF INVENTION:
[0010] Surprisingly, it has been found that the above object is met by providing a method for producing a separator modified with functionalized silica nanoparticles obtained by in-situ grafting technique at moderate temperature.
[0011] Accordingly, in one aspect, the presently claimed invention relates to a method for producing a separator for providing electrical isolation in a metal-sulfur battery. The method comprises obtaining functionalized silica nanoparticles at a temperature ranging between 20°C to 50°C by reacting a silica precursor and a coupling agent. The weight ratio between the silica precursor and the coupling agent is in the range of 1.0:6.0 to 6.0: 1.0. The method also comprises coating on a polymeric material with dispersed nanoparticles to obtain the separator. The dispersed nanoparticles are obtained by dispersing the functionalized silica nanoparticles in a binder solution.
[0012] In an embodiment, the method comprises mixing a pH adjusting agent with an aqueous solvent to obtain a reaction solvent having a pH ranging between 10 to 13. The pH adjusting agent is added in an amount ranging between 0.1 vol.% to 10.0 vol.% based on the total volume of the reaction solvent. The method also comprises reacting the silica precursor and the coupling agent in the reaction solvent at a temperature ranging between 20°C to 50°C to obtain a solution comprising the functionalized silica nanoparticles. The method further comprises isolating the functionalized silica nanoparticles from the solution. [0013] In another embodiment, the silica precursor is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate.
[0014] In yet another embodiment, the silica precursor is tetraethyl orthosilicate.
[0015] In still another embodiment, the coupling agent is a silane coupling agent selected from the group consisting of 3-aminopropyl triethoxysilane, 3 -mercaptopropyl trimethoxysilane, 3- cyanopropyl triethoxysilane, and triethoxy(ethyl)silane.
[0016] In a further embodiment, the polymeric material comprises polypropylene, polyethylene or a composite thereof.
[0017] In a still further embodiment, the binder is selected from the group consisting of carboxymethyl cellulose, styrene -butadiene rubber and polyvinylidene fluoride, in at least one solvent selected from the group consisting of water, ethanol, propanol, N-methyl-2-pyrrolidone, and acetone.
[0018] In another embodiment, the pH adjusting agent is selected from the group consisting of sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethyl ammonium hydroxide.
[0019] In still another embodiment, no surfactant is present.
[0020] In a further embodiment, the coating is selected from doctor’s blade coating, dip coating, spin coating, microgravure coating, electrospinning, comma coating, or reverse comma coating.
[0021] In another aspect, the presently claimed invention relates to the separator as obtained hereinabove. [0022] In another aspect, the present invention relates to a metal-sulfur battery comprising the above separator. The separator is disposed between at least one positive electrode and at least one negative electrode.
BRIEF DESCRIPTION OF FIGURES:
[0023] Figure 1 shows a Fourier Transform Infrared Spectroscopy (FTIR) spectrum of amine functional silica nanoparticles.
[0024] Figures 2(a) and 2(b) show Scanning Electron Microscope (SEM) images of conventional polypropylene separator.
[0025] Figures 2(c) and 2(d) show Scanning Electron Microscope (SEM) images of amine functional silica nanoparticle modified polypropylene separator.
[0026] Figure 3(a) shows Galvanostatic charge-discharge profile of a lithium-sulfur cell with a conventional polypropylene separator (a-1) and amine functional silica nanoparticle modified polypropylene separator (a-2).
[0027] Figure 3(b) shows Galvanostatic charge-discharge profile of a lithium- sulfur cell with conventional polypropylene separator.
[0028] Figure 3(c) Galvanostatic charge-discharge profile of amine functional silica nanoparticle modified polypropylene separator.
[0029] Figure 4 shows long term cycling performance of lithium-sulfur cell with (a) a conventional polypropylene separator, and (b) amine functional silica nanoparticles modified polypropylene separator.
DETAILED DESCRIPTION OF THE INVENTION:
[0030] Before the present method is described, it is to be understood that the terminology used herein is not intended to be limiting since the scope of the presently claimed invention will be limited only by the appended claims. [0031] The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. It will be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein comprise the terms "consisting of", "consists" and "consists of".
[0032] Furthermore, the terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. In case the terms "first", "second", "third" or "(A)", "(B)", and "(C)" or "(a)", "(b)", "(c)", "(d)", "I", "ii", etc. relate to steps of a method or use or assay, there is no time or time interval coherence between the steps, that is, the steps may be carried out simultaneously or there may be intervals of seconds, minutes, hours, days, weeks, months, or even years between such steps, unless otherwise indicated in the application as set forth hereinabove or below.
[0033] In the following passages, different aspects of the invention are defined in more detail. Each aspect so defined may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.
[0034] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the presently claimed invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Further, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of this invention, and form different embodiments, as would be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments can be used in any combination.
[0035] Furthermore, the ranges defined throughout the specification include the end values as well, i.e., a range of 1 to 10 implies that both 1 and 10 are included in the range. For the avoidance of doubt, the applicant shall be entitled to any equivalents according to applicable law.
[0036] An aspect of the presently claimed invention is directed to a method for producing a separator for providing electrical isolation in a metal-sulfur battery.
[0037] In an embodiment, the method comprises the steps of:
(A) obtaining functionalized silica nanoparticles at a temperature ranging between 20°C to 50°C by reacting a silica precursor and a coupling agent, wherein the weight ratio between the silica precursor and the coupling agent is in the range of 1.0:6.0 to 6.0:1.0, and
(B) coating on a polymeric material with dispersed nanoparticles to obtain the separator, wherein the dispersed nanoparticles is obtained by dispersing the functionalized silica nanoparticles in a binder solution.
[0038] For the purpose of the present invention, the terms "separator" and "diaphragm" are synonymous. Further, the present invention contains no surfactant. Said otherwise, no surfactant is added, in any manner and at any stage or steps of the method described herein.
[0039] Also, in the present context, the step of obtaining functionalized silica nanoparticle by reacting the silica precursor and the coupling agent in step (A), as above, is referred as in-situ grafting technique. In this technique, functionalization of silica precursor with coupling agent is conducted in same phase or in a single step.
[0040] Moreover, any reference to "battery" in the present context also includes portable batteries such as, but not limited to, different types and kinds of cells. [0041] In one embodiment, the metal-sulfur battery includes rechargeable batteries such as, but not limited to, lithium-sulfur battery, sodium-sulfur battery, and potassium-sulfur battery. In another embodiment, the metal-sulfur battery is lithium-sulfur battery.
[0042] In an embodiment, the silica precursor is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate. In another embodiment, the silica precursor is tetraethyl orthosilicate.
[0043] The coupling agent is used to increase adhesive strength and is characterized by having two or more functional groups. The coupling agent may be a material in which one functional group forms a chemical bond via reaction with a hydroxyl or carboxyl group present on the surface of the silicon-, tin- or graphite -based active material, and the other functional group forms a chemical bond via reaction with the polymer binder. Specific examples of the coupling agent that can be used in the present invention may include, but are not limited to, silane-based coupling selected from the group consisting of triethoxysilylpropyl tetrasulfide, 3 -mercaptopropyl triethoxysilane, 3-aminopropyl triethoxysilane, chloropropyl triethoxysilane, vinyl triethoxysilane, methacryloxypropyl triethoxysilane, glycidoxypropyl triethoxysilane, isocyanatopropyl triethoxy silane, 3-cyanopropyl triethoxysilane and triethoxy(ethyl)silane.
[0044] In an embodiment, the coupling agent is selected from the group consisting of 3- aminopropyl triethoxysilane, 3 -mercaptopropyl trimethoxysilane, 3-cyanopropyl triethoxysilane, and triethoxy(ethyl)silane. In another embodiment, the coupling agent is 3-aminopropyl triethoxysilane.
[0045] The functional groups from the coupling agent are grafted on the surface of the dispersed nanoparticles. In an embodiment, the amount of the functional groups on the dispersed nanoparticles is in the range of 20 wt.% to 70 wt.% determined using CHNS (Carbon Nitrogen Hydrogen Sulfur) analysis.
[0046] In an embodiment, the step (A), as described herein, comprises the following sub-steps: (Al) mixing a pH adjusting agent with an aqueous solvent to obtain a reaction solvent having a pH ranging between 10 to 13, wherein the pH adjusting agent is added in an amount ranging between 0.1 vol.% to 10.0 vol.% based on the total volume of the reaction solvent,
(A2) reacting the silica precursor and the coupling agent in the reaction solvent at a temperature ranging between 20°C to 50°C to obtain a solution comprising the functionalized silica nanoparticles, and
(A3) isolating the functionalized silica nanoparticles from the solution obtained in step (A2).
[0047] The pH adjusting agent is selected from the group consisting of sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethyl ammonium hydroxide. In an embodiment, the pH adjusting agent is sodium hydroxide or ammonium hydroxide. Suitable amounts of the pH adjusting agents are mixed with the aqueous solvent to obtain the reaction solvent at a pH ranging between 10 to 13, or in between 11 to 13. In an embodiment, the pH adjusting agent is added in an amount ranging between 0.5 vol.% to 10.0 vol.%, or in between 0.5 vol.% to 8.0 vol.%, or in between 1.0 vol.% to 8.0 vol.% based on the total volume of the reaction solvent. In another embodiment, the pH adjusting agent is added in amounts ranging between 1.0 vol.% to 7.0 vol.%, or in between 2.0 vol.% to 7.0 vol.%, or in between 3.0 vol.% to 7.0 vol.%, or in between 4.0 vol.% to 7.0 vol.%.
[0048] In the present context, "mixing" is carried out using suitable mixing means such as, but not limited to, a stirrer. Suitable stirring rate or rpm is known to persons skilled in the art and hence the presently claimed invention is not limited by the same.
[0049] The aqueous solvent comprises at least one solvent in water. In an embodiment, the solvent is selected from the group consisting of ethanol, propanol, N-methyl-2-pyrrolidone, and acetone. Suitable amounts of solvent are known to persons skilled in the art and hence the presently claimed invention is not limited by the same.
[0050] Solution comprising functionalized silica nanoparticles is obtained upon reacting the silica precursor with the coupling agent in the reaction solvent. The weight ratio between the silica precursor and the coupling agent is in the range of 1.0:5.5 to 5.5: 1.0, or in between 1.0:5.0 to 5.0:1.0, or in between 1.0:4.5 to 4.5: 1.0, or in between 1.0:4.0 to 4.0:1.0, or in between 1.0:3.5 to 3.5: 1.0. In another embodiment, the weight ratio is in between 1.0:3.0 to 3.0: 1.0, or in between 1.0:2.5 to 2.5:1.0, or in between 1.0:2.0 to 2.0:1.0.
[0051] The reaction is carried out at moderate temperature ranging between 20°C to 50°C for obtaining the solution comprising the functionalized silica nanoparticles. In an embodiment, the solution obtained is a homogeneous suspension of dispersed nanoparticles. Subsequently, the functionalized silica nanoparticles are isolated and subjected to step (B), described herein. Suitable techniques for isolating functionalized silica nanoparticles include, but are not limited to, one or more of centrifugation, washing, drying, and filtering.
[0052] In an embodiment, the size of the functionalized silica nanoparticles obtained in accordance with the presently claimed invention is less than 400 nm. In another embodiment, the size ranges in between 200 nm to 350 nm as determined using Scanning Electron Microscopy (SEM) technique. The size can further be controlled by varying the weight ratio between the silica precursor and the coupling agent.
[0053] The dispersed nanoparticles in step (B) are obtained by dispersing the functionalized silica nanoparticles in the binder. Suitable binders for this purpose are selected from the group consisting of carboxymethyl cellulose, styrene-butadiene rubber and polyvinylidene fluoride. In an embodiment, the binder is pre-mixed with at least one solvent to obtain the binder solution. The solvent used herein is selected from the group consisting of water, ethanol, propanol, N-methyl-2- pyrrolidone, and acetone.
[0054] In an embodiment, the polymeric material comprises polypropylene (PP), polyethylene (PE) or a combination thereof. The polymeric material is permeable to ions and polysulfides. However, upon coating the polymeric material with the functionalized silica nanoparticles in accordance with the presently claimed invention, the resulting separator is permeable to ions but the polysulfide permeability is arrested significantly.
[0055] Suitable techniques for coating the polymeric material are selected from doctor’s blade coating, dip coating, spin coating, microgravure coating, electrospinning, comma coating, or reverse comma coating. Subsequently, the coated polymeric material is dried and the separator is obtained.
[0056] Another aspect of the presently claimed invention is directed to the above separator. The separator is obtained in accordance with the method disclosed herein.
[0057] Still another aspect of the presently claimed invention is directed to a metal-sulfur battery comprising the separator described herein.
[0058] In one embodiment, the separator is disposed between at least one positive electrode and at least one negative electrode. Suitable electrolytes and materials of construction for the electrodes are well known to the person skilled in the art and hence, the presently claimed invention is not limited in terms of the choice and selection of the same.
[0059] In an exemplary embodiment, suitable cathode may be made from a composite material obtained from, such as but not limited to, sulfur and activated carbon using known techniques. Similarly, electrolyte may be a mixture of various metals such as, but not limited to, lithium, sodium and the likes, in suitable salt forms such as, but not limited to, fluorosulphonamide, trifluorosulphonamide, nitrates, and the like in a suitable solvent. Further, suitable metal such as lithium may be used as anode material.
[0060] The separator obtained in accordance with the presently claimed invention is effective in mitigating poly sulfide shuttling and results in acceptable battery performance such as, but not limited to, improvement in cycle life, rate capability, polarization and overall capacity. Further, the separator obtained in accordance with the present invention consumes less energy and time and is cost effective, which renders it easy for carrying out scale up activities.
[0061] Examples
[0062] The present invention is illustrated by the non-restrictive examples which are as follows:
[0063] Compounds pH adjusting agent Ammonium hydroxide and sodium hydroxide obtained from Loba Chem Solvent Isopropanol obtained from Rankem
Silica precursor Tetraethyl orthosilicate obtained from Cisco Research Coupling agent 3 -aminopropyl triethoxysilane obtained from Aldrich Binder Carboxymethyl cellulose (CMC) obtained from SD Fine Chem
[0064] Galvanostatic cycling performance
[0065] Galvanostatic charge/discharge experiments were carried out under a constant charge/discharge current density of 0.1 C within an applied voltage window ranging from 1.6 V to 2.8 V. The capacitance retention experiments were carried out at a constant current density of 0.3 C in the applied voltage window of 1.6 V to 2.8 V for 100 charge/discharge cycles.
[0066] General synthesis of functionalized silica nanomaterial
[0067] Isopropanol and water were mixed in a volume ratio of 5.0: 1.0 to obtain reaction solvent. Thereafter, 5 ml of ammonium hydroxide (NH4OH) or sodium hydroxide (NaOH) was mixed to 100 ml of the reaction solvent under continuous stirring for 2-3 hours to raise the pH to 11-13. Subsequently, 10 mmol of 3-aminoprpyl) triethoxysilane (APTES) and 15 mmol of tetraethyl orthosilicate (TEOS) was slowly added to the solvent under continuous stirring at room temperature (298 K) to obtain a solution. The solution was stirred overnight to complete the condensation reaction among silica precursors. Finally, the organic amine (-NH2) functionalized silica nanoparticles (AFSN) was collected by centrifugation, washing and vacuum drying.
[0068] Several controlled experiments were carried out in accordance with the above method and by varying the concentrations of reactants such as APTES, TEOS and the pH adjusting agent. Results of the same are summarized in Table 1 below. Table 1 : Synthesis of AFSN with varying concentration of the reactants and pH adjusting agent.
Figure imgf000015_0001
[0069] Fourier transform infrared spectroscopy (FTIR) of the sample AFSN-23 A is shown in Figure 1. The spectrum shows different framework vibrations present in the amine functionalized silica nanoparticles. The appearance of peaks at 3304 cm'1 and 2993 cm'1 are attributed to N-H, C-H stretching vibration from amine (-NH2) and methylene groups (-CH2-), respectively, of the grafted APTES on the nanoparticle surfaces. The strong peaks located at 1068 cm'1 corresponds to the asymmetrical stretching vibration of the Si-O-Si derived from the cross-linked silica networks.
[0070] General synthesis of separator
[0071] 3 g of the AFSN-23 A sample was dispersed in the binder solution comprising 20 ml of water premixed with 30 mg of carboxymethyl cellulose, and stirred for over 10 h to obtain a homogeneous suspension of dispersed nanoparticles. The suspension was then coated on single side of a clean blank polypropylene separator using the doctor’s blade technique. Thereafter, the separator was dried under 50 °C in a constant temperature oven for 4 h.
[0072] Figures 2(a) and 2(b) show the SEM image of the conventional polypropylene separator (PP) whereas the SEM image of AFSN-23A in accordance with the present invention is shown in Figures 2(c) and 2(d). From these SEM images, elliptical pores of 100 nm to 200 nm are clearly visible on the surface of the conventional separator which is not suitable to arrest the polysulfide shuttling. On the contrary, these pores are blocked with the amine functionalized silica nanoparticles which can store more electrolyte and restrict the polysulfide shuttling between the cathode and the anode of the lithium sulfur battery.
[0073] Synthesis of sulfur/activated carbon composite cathode material [0074] Sulfur/activated carbon composites were prepared using melting diffusion method by heating a pre-mix of sulfur and activated carbon in a weight ratio of 4:1 for 12 h at a temperature ranging between 150-170°C. The composite material thus obtained was used as a cathode material in metal-sulfur battery. The sulfur used here was collected from an Indian petroleum refinery and used without any further purification.
[0075] Metal-sulfur battery and electrochemical test
[0076] A cathode was prepared by mixing the above composite cathode material, super phosphorus and poly vinylidenedifluoride (PVDF) in a mass ratio of 8:1: 1 in N-methyl-2- pyrrolidone (NMP) solvent for 2-3 h. A slurry was obtained which was subsequently coated on an aluminum foil using doctor's blade technique and dried at 100-120°C for 2 h. The cathode was cut into 15 mm diameter with sulfur loading ranging between 2-5 mg/cm2.
[0077] Coin-type cells (2032) were fabricated inside an argon-filled glovebox using the conventional separator and AFSN-23A separator in accordance with the present invention. Several different metal foils (Li, Na etc.) were used as counter and reference electrode. The electrolyte was a mixture of various metal (Li, Na etc.) salts such as flurosulphonamide (-Fsl), triflurosulphonamide (-TfSI) and nitrate (-NO3) in a solvent mixture of 1,2-dimethoxy ethane (DME) and 1,3-dioxalane (DOL) for different metal-sulfur batteries having the metal salt concentration ranging between 0.2 M to 1.0 M. Cycling tests were performed with these batteries within the potential window of 1.6 V-2.8 V at 0.3 C current rates over 100 cycles.
[0078] Electrochemical performance of the conventional separator and the AFSN-23A separator were carried out by Galvanostatic cycling performance experiment using the composite cathode and lithium metal as anode. The results are shown in Figures 3(a) to 3(c). The initial discharge capacity was 1030 mAh/g and 730 mAh/g for the conventional separator and the AFSN-23A separator, respectively, at 0.1 C charging-discharging rate (refer Figure 3(a)). The discharge capacity increases from 698 mAh/g to 745 mAh/g using the AFSN-23 A separator over the conventional separator when tested at 0.3 C charging-discharging rate (refer Figures 3(b) and 3(c)). The presence of characteristic two voltage plateaus in the discharge curves can be ascribed to the two-step reaction of sulfur with lithium during the discharge process.
[0079] Further, as shown in Figures 3(b) and 3(c), upon charging the cell a strong polarization was observed for the conventional separator (0.30 V) in comparison to the AFSN-23A separator (0.25 V), and the two plateaus merged to a single oxidation plateau. This confirms that the Li-S battery comprising the AFSN-23A separator has lower polarization, thereby indicating that the modified separator in accordance with the present invention is able to restrict the polysulfides shuttling to a substantial extent in comparison with the conventional separator.
[0080] The cycling properties of the S/AC composite cathode in presence of different separators in Li-S cells at a rate of 0.3 C is shown in Figure 4. The discharge capacity values varied between 745 mAh/g and 595 mAh/g for the first and hundredth cycle, respectively, using the AFSN-23A separator. For the conventional separator, the discharge capacity values varied between 698 and 453 mAh/g for the first and hundredth cycles, respectively. The decrease in specific capacity was observed as a smooth and gradual process, losing only 1.50 mAh/g per cycle for the AFSN-23A separator compared to 2.45 mAh/g for the conventional PP separator. The improved capacity retention using the AFSN-23A separator can be attributed to the presence of amine functionalized silica nanoparticle in the polypropylene separator that retained the polysulfides, and inhibited the shuttle effect.

Claims

WE CLAIM:
1. A method for producing a separator for providing electrical isolation in a metal-sulfur battery, said method comprising the steps of:
(A) obtaining functionalized silica nanoparticles at a temperature ranging between 20°C to 50°C by reacting a silica precursor and a coupling agent, wherein the weight ratio between the silica precursor and the coupling agent is in the range of 1.0: 6.0 to 6.0: 1.0, and
(B) coating a polymeric material with dispersed nanoparticles to obtain the separator, wherein the dispersed nanoparticles is obtained by dispersing the functionalized silica nanoparticles in a binder solution.
2. The method as claimed in claim 1, wherein step (A) comprises following sub-steps:
(Al) mixing a pH adjusting agent with an aqueous solvent to obtain a reaction solvent having a pH ranging between 10 to 13, wherein the pH adjusting agent is added in an amount ranging between 0.1 vol.% to 10.0 vol.% based on the total volume of the reaction solvent,
(A2) reacting the silica precursor and the coupling agent in the reaction solvent at a temperature ranging between 20°C to 50°C to obtain a solution comprising the functionalized silica nanoparticles, and
(A3) isolating the functionalized silica nanoparticles from the solution obtained in step (A2).
3. The method as claimed in claim 1 or 2, wherein the silica precursor is selected from the group consisting of tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, and tetrabutyl orthosilicate.
4. The method as claimed in one or more of claims 1 to 3, wherein the silica precursor is tetraethyl orthosilicate.
5. The method as claimed in one or more of claims 1 to 4, wherein the coupling agent is a silane coupling agent selected from the group consisting of 3-aminopropyl triethoxy silane, 3- mercaptopropyl trimethoxysilane, 3-cyanopropyl triethoxysilane, and triethoxy(ethyl)silane.
6. The method as claimed in one or more of claims 1 to 5, wherein the polymeric material comprises polypropylene (PP), polyethylene (PE) or a composite thereof.
7. The method as claimed in one or more of claims 1 to 6, wherein the binder solution comprises of one or more selected from the group consisting of carboxymethyl cellulose, styrenebutadiene rubber and polyvinylidene fluoride, in at least one solvent selected from the group consisting of water, ethanol, propanol, N-methyl-2-pyrrolidone, and acetone.
8. The method as claimed in one or more of claims 2 to 7, wherein the pH adjusting agent is selected from the group consisting of sodium hydroxide, ammonium hydroxide, potassium hydroxide, lithium hydroxide and tetramethyl ammonium hydroxide.
9. The method as claimed in one or more of claims 1 to 8, wherein no surfactant is present.
10. The method as claimed in one or more of claims 1 to 9, wherein the coating in step (B) is selected from doctor’s blade coating, dip coating, spin coating, microgravure coating, electrospinning, comma coating, or reverse comma coating.
11. A separator obtained by the method as claimed in one or more of claims 1 to 10.
12. A metal-sulfur battery comprising the separator as obtained by the method as claimed in one or more of claims 1 to 10, wherein the separator is disposed between at least one positive electrode and at least one negative electrode.
PCT/IN2022/051095 2022-09-30 2022-12-19 Method for producing a separator and a metal-sulfur battery comprising the separator WO2024069635A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IN202241056185 2022-09-30
IN202241056185 2022-09-30

Publications (1)

Publication Number Publication Date
WO2024069635A1 true WO2024069635A1 (en) 2024-04-04

Family

ID=84981579

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IN2022/051095 WO2024069635A1 (en) 2022-09-30 2022-12-19 Method for producing a separator and a metal-sulfur battery comprising the separator

Country Status (1)

Country Link
WO (1) WO2024069635A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110571392A (en) * 2018-06-29 2019-12-13 华中科技大学 Functional interlayer material of lithium-sulfur battery and preparation method thereof
CN111370620A (en) 2020-02-26 2020-07-03 华中科技大学 Functional diaphragm of lithium-sulfur battery and preparation method thereof
CN113690546A (en) 2021-07-21 2021-11-23 华南理工大学 Lithium-sulfur battery diaphragm and preparation method and application thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110571392A (en) * 2018-06-29 2019-12-13 华中科技大学 Functional interlayer material of lithium-sulfur battery and preparation method thereof
CN111370620A (en) 2020-02-26 2020-07-03 华中科技大学 Functional diaphragm of lithium-sulfur battery and preparation method thereof
CN113690546A (en) 2021-07-21 2021-11-23 华南理工大学 Lithium-sulfur battery diaphragm and preparation method and application thereof

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JING LI ET AL., ACS APPL. MATER. INTERFACES, 2017
SU MIAOMIAO ET AL: "High safety separators for rechargeable lithium batteries", SCIENCE CHINA CHEMISTRY; THE FRONTIERS OF CHEMICAL BIOLOGY AND SYNTHESIS, SCIENCE CHINA PRESS, SIENCE CHINA PRESS, vol. 64, no. 7, 25 April 2021 (2021-04-25), pages 1131 - 1156, XP037504531, ISSN: 1674-7291, [retrieved on 20210425], DOI: 10.1007/S11426-021-1011-9 *

Similar Documents

Publication Publication Date Title
US10998552B2 (en) Lithium ion battery and battery materials
Yin et al. MXene debris modified eggshell membrane as separator for high-performance lithium-sulfur batteries
Xu et al. Carbon nanomaterials for advanced lithium sulfur batteries
An et al. MXenes for advanced separator in rechargeable batteries
JP6302249B2 (en) Sulfur-containing nanoporous materials, nanoparticles, methods and applications
US10026962B2 (en) Alginate-containing compositions for use in battery applications
US10727466B2 (en) Polyethyleneimine-attached carbonaceous material and separator for lithium-sulfur battery coated with the same
US11728543B2 (en) Electrospinning of PVdF-HFP: novel composite polymer electrolytes (CPES) with enhanced ionic conductivities for lithium-sulfur batteries
EP3345232B1 (en) Li-s battery with carbon coated separator
JP2014502405A5 (en)
KR20080021642A (en) Electrode material including a lithium/transition metal complex oxide
US20230207780A1 (en) Negative electrode material for lithium-ion secondary battery and use thereof
US10601030B2 (en) Functional polymer binder for sulfur cathode fabrication
KR20160045378A (en) Silicon-silicon oxycarbide glass composite, preparation method of thereof, and anode materials and lithium secondary battery comprising the same
Liu et al. Electrospun Silsequioxane-grafted PVDF hybrid membranes for high-performance rechargeable lithium batteries
Ma et al. To achieve controlled specific capacities of silicon-based anodes for high-performance lithium-ion batteries
CN110098367A (en) A kind of carbon nano-tube/titanic oxide nano lamella compound modified diaphragm and preparation method thereof
KR20190141392A (en) Coating composition for separator of secondary battery comprising P-doped graphitic carbon nitride, preparation method thereof and Li-S battery comprising the same
US20200274201A1 (en) Weavable, conformable, wearable and flexible components for advanced battery technology
WO2024069635A1 (en) Method for producing a separator and a metal-sulfur battery comprising the separator
CN113178561A (en) Negative electrode material modified by reactive two-dimensional molecular brush SEI film, and preparation method and application thereof
Sun et al. Improved ionic conductivity and cycling stability via composite separator constructed by coating organic-modified sepiolite/PVDF layer on PP via electrospinning technology
Xu et al. Fabrication of electrospun bilayer separators for lithium-sulfur batteries: A surface and structure dual modification strategy
WO2018183556A1 (en) Lithium-sulfur electrode and method
WO2023074592A1 (en) Potassium-ion battery electrolytic solution additive, potassium-ion battery electrolytic solution, potassium-ion battery, potassium-ion capacitor electrolytic solution additive, potassium-ion capacitor electrolytic solution, potassium-ion capacitor, and negative electrode

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22844296

Country of ref document: EP

Kind code of ref document: A1