WO2016019897A1 - A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite - Google Patents

A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite Download PDF

Info

Publication number
WO2016019897A1
WO2016019897A1 PCT/CN2015/086358 CN2015086358W WO2016019897A1 WO 2016019897 A1 WO2016019897 A1 WO 2016019897A1 CN 2015086358 W CN2015086358 W CN 2015086358W WO 2016019897 A1 WO2016019897 A1 WO 2016019897A1
Authority
WO
WIPO (PCT)
Prior art keywords
sulfur
polyacrylonitrile
composite
carbon
fibers
Prior art date
Application number
PCT/CN2015/086358
Other languages
French (fr)
Inventor
Nahong ZHAO
Joerg Thielen
Bernd Schumann
Yunhua Chen
Chuanling LI
Original Assignee
Robert Bosch Gmbh
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 Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Priority to CN201580042511.2A priority Critical patent/CN106575750A/en
Publication of WO2016019897A1 publication Critical patent/WO2016019897A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/06—Sulfur
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C08K3/041—Carbon nanotubes
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/18—Homopolymers or copolymers of nitriles
    • C08L33/20—Homopolymers or copolymers of acrylonitrile
    • 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
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • 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 sulfur-polyacrylonitrile composite, which comprises sulfur as well as polyacrylonitrile fibers.
  • the present invention further relates to a method for preparing said sulfur-polyacrylonitrile composite, and an electrode and a lithium-sulfur battery comprising said sulfur-polyacrylonitrile composite.
  • Li-Sulfur (Li-S) batteries have attracted considerable attention for their high energy density and low cost.
  • the theoretical energy density of 2600 Wh/kg cannot be reached because of sulfur’s insulating nature.
  • conductive additives have to be added and consequently the theoretical value is reduced to a realistic 600 Wh/kg.
  • elemental sulfur forms polysulfides, S x 2- , during reduction, which is soluble in the electrolyte. Therefore, several concepts have been elaborated upon that focus on retaining sulfur in the cathode matrix.
  • One of the most promising concepts is to embed sulfur into a conductive matrix of pyrolized polyacrylonitrile (PAN) .
  • PAN pyrolized polyacrylonitrile
  • the present invention provides a sulfur-polyacrylonitrile (SPAN) composite, which provides a high sulfur content and a favorable electrical conductivity. It is promising to deliver a high cathode capacity and a good rate capability when discharging under a large current density.
  • SPAN sulfur-polyacrylonitrile
  • a sulfur-polyacrylonitrile composite which comprises sulfur as well as polyacrylonitrile fibers.
  • a method for preparing a sulfur-polyacrylonitrile composite including the following steps:
  • the present invention relates an electrode, which comprises the sulfur-polyacrylonitrile composite according to the present invention.
  • the present invention relates a lithium-sulfur battery, which comprises the electrode according to the present invention.
  • FIG. 1 shows schematic diagrams of the PAN fibers
  • Figure 2 shows schematic diagrams of the PAN fibers without carbon conductive additives (a) , with coaxial oriented or randomly oriented CNTs embedded (b) , and with carbon black embedded (c) ;
  • Figure 3 shows a schematic diagram of the electrospinning process for pure PAN fibers
  • Figure 4 shows the Scanning Electron Microscopy (SEM) images of the PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm, prepared in Example 1 (E1) ;
  • Figure 5 shows the SEM images of the sulfur-polyacrylonitrile composite in the form of fibers (SPAN fiber composite) having diameters of about 300 nm, 500 nm, and 1000 nm, prepared in Example 1 (E1) ;
  • Figure 6 shows the charge and discharge performances of the cathodes made from the SPAN fiber composite of Example 1 (E1) and from the sulfur-polyacrylonitrile composite in the form of particles (SPAN particle composite) of Comparison Example 1 (CE1) ;
  • Figure 7 shows a schematic diagram of the electrospinning process for PAN fibers comprising carbon conductive additives embedded
  • Figure 8 shows the SEM images of the PAN fibers with CNT contents of 1 wt. % (a) , 2 wt. % (b) , 4 wt. % (c) , and 8 wt. % (d) , prepared in Example 2 (E2) ;
  • Figure 9 shows the SEM image of the cross section of the PAN fibers with CNTs embedded, prepared in Example 2 (E2) ;
  • Figure 10 shows the SEM image of the SPAN fiber composite with CNTs embedded, prepared in Example 2 (E2) ;
  • Figure 11 shows the SEM image of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) ;
  • Figure 12 shows an optical photograph of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) ;
  • Figure 13 shows the SEM images of the PAN fibers with carbon black contents of 1 wt. %(a) , 2 wt. % (b) , 4 wt. % (c) , and 8 wt. % (d) , prepared in Example 3 (E3) ;
  • Figure 14 shows a schematic diagram of the PAN in the form of fibers and particles
  • Figure 15 shows the SEM image of the PAN in the form of fibers and particles prepared in Example 4 (E4) ;
  • Figure 16a is a schematic diagram of a synthesis route for the SPAN composite comprising carbon conductive additives by loading sulfur first and then applying carbon conductive additives;
  • Figure 16b is a schematic diagram of another synthesis route for the SPAN composite comprising carbon conductive additives by applying carbon conductive additives first and then loading sulfur;
  • Figure 17 shows the SEM image of the SPAN fiber composite comprising carbon black in the empty space of the composite, prepared in Example 5 (E5) ;
  • Figure 18 shows the 4 th charge and discharge performances of the cathodes made in Example 5 (E5, solid line) and made in Comparison Example 2 (CE2, broken line) ;
  • Figure 19 shows the 4 th charge and discharge performances of the cathode made in Example 6 (E6) .
  • the present invention relates to a sulfur-polyacrylonitrile composite, which comprises sulfur as well as polyacrylonitrile fibers.
  • fiber shall be understood as having a substantially uniform diameter over its full length and having a smooth surface.
  • a substantially uniform diameter and a smooth surface are favorable to prevent tangling up when being dispersed and to ensure a stable product quality.
  • polyacrylonitrile fibers according to the present invention can be prepared by electrospinning.
  • the molecular weight of the polyacrylonitrile used here is not particularly limited, and can be for example 50 000–800 000 g/mol, 100 000–500 000 g/mol (Mn) .
  • said sulfur-polyacrylonitrile composite can further comprise polyacrylonitrile particles.
  • the diameter of said polyacrylonitrile particles can be between 100 nm and 10 ⁇ m, preferably between 100 nm and 2 ⁇ m.
  • said sulfur-polyacrylonitrile composite can be formed in such a way that said polyacrylonitrile fibers and/or particles are dehydrogenated and cyclized in the presence of sulfur and bonded with sulfur or polysulfide.
  • the diameter of said polyacrylonitrile fibers can be 50 nm–2 ⁇ m, preferably 100 nm–1.5 ⁇ m, for example about 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 ⁇ m, or 1.2 ⁇ m.
  • a preferred average distance from fiber to fiber can be 0.1–2 times the fiber diameter.
  • the aspect ratio of said polyacrylonitrile fibers can be 10–1,000,000, preferably 10–500, more preferably 10–100.
  • the aspect ratio of the fibers is defined as the ratio of the length to the diameter of the fibers.
  • Figure 1b shows the schematic diagram of the PAN fibers with a relatively low aspect ratio.
  • a relatively low aspect ratio for the PAN fibers means relatively short PAN fibers.
  • Preferably shorter PAN fibers can prevent tangling up and obtain a monodisperse mixture when being dispersed, and can enhance the contact with sulfur during the SPAN synthesis.
  • said sulfur-polyacrylonitrile composite can further comprise one or more carbon conductive additives, as illustrated in Figures 2b and 2c.
  • the content of said one or more carbon conductive additives is less than or equal to 15 wt. %, preferably less than or equal to 10 wt. %, more preferably less than or equal to 8 wt. %, most preferably less than or equal to 5 wt. %, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
  • said one or more carbon conductive additives can be preferably adopted and embedded in the polyacrylonitrile fibers and/or particles.
  • said one or more carbon conductive additives can bridge from one polyacrylonitrile fiber or particle to another polyacrylonitrile fiber or particle, so as to bridge the electron conductive network in-between the polyacrylonitrile fibers and/or particles, as illustrated in Figures 16a (iii) and 16b (iii) .
  • Said one or more carbon conductive additives can be placed in the empty space of said sulfur-polyacrylonitrile composite, so as to attach the carbon conductive additives onto the outer surface of the polyacrylonitrile fibers and/or particles.
  • said one or more carbon conductive additives can be preferably adopted and embedded in the polyacrylonitrile fibers and/or particles.
  • one end of the carbon conductive additive can be embedded in one polyacrylonitrile fiber or particle, and the other end of the same carbon conductive additive can be embedded in another polyacrylonitrile fiber or particle.
  • said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black.
  • CNT carbon nanotube
  • graphite graphite
  • carbon nanoparticle such as acetylene black, SuperP carbon black or ketjen black.
  • the carbon nanotube (CNT) which can be used in the sulfur-polyacrylonitrile composite according to the present invention preferably has a diameter of 1–100 nm, for example about 2 nm, 3 nm, 5 nm, 10 nm, 30 nm, 40 nm, 60 nm, or 80 nm.
  • the length of the carbon nanotube (CNT) used here is not particularly limited, for example less than 5 ⁇ m, 5–15 ⁇ m, or more than 15 ⁇ m.
  • a preferable length of the CNT can be 0.3–6 times the PAN fiber diameter.
  • CNT carbon nanotube
  • SWNT Single-walled carbon nanotube
  • DWNT double-walled carbon nanotube
  • MWNT multi-walled carbon nanotube
  • said carbon nanotube (CNT) can be open-ended, and the inner voids of the carbon nanotube (CNT) can be filled with 1–30 wt. %, preferably 10–20 wt. %of sulfur to form a sulfur-carbon nanotube composite (S/CNT) , based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
  • the sulfur load amount of said sulfur-polyacrylonitrile composite can be 20–55 wt. %, preferably 30–50 wt. %, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
  • the present invention relates to a method for preparing a sulfur-polyacrylonitrile composite, said method including the following steps:
  • Polyacrylonitrile fibers can be prepared by electrospinning from a polyacrylonitrile solution or dispersion, as illustrated in Figure 3.
  • concentration of polyacrylonitrile in said solution or dispersion is not particularly limited, for example 3–20 wt. %, preferably 5–15 wt. %, more preferably 6–10 wt. %, and can be determined according to the desired diameter of polyacrylonitrile fibers.
  • the solvent for said polyacrylonitrile solution or dispersion is not particularly limited, for example DMF.
  • the molecular weight of the polyacrylonitrile used here is not particularly limited, and can be for example 50 000–800 000 g/mol, 100 000–500 000 g/mol (Mn) .
  • polyacrylonitrile particles can also be prepared by electrospraying from a polyacrylonitrile solution or dispersion.
  • the polyacrylonitrile in a combination form of fibers and particles can be prepared by mixing the PAN fibers and the PAN particles.
  • the polyacrylonitrile in a combination form of fibers and particles can also be prepared at the same time by electrospinning and electrospraying.
  • the PAN particles can be prepared by electrospraying at the same time through a nozzle close to the nozzle for electrospinning the PAN fibers.
  • one or more carbon conductive additives can be additionally applied to the polyacrylonitrile fibers and/or particles.
  • the content of said one or more carbon conductive additives is less than or equal to 15 wt. %, preferably less than or equal to 10 wt. %, more preferably less than or equal to 8 wt. %, most preferably less than or equal to 5 wt. %, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
  • said one or more carbon conductive additives can be applied to the polyacrylonitrile fibers and/or particles already formed in step 1) , as illustrated in Figure 16b.
  • said one or more carbon conductive additives can also be applied to the polyacrylonitrile fibers and/or particles in the course of the preparation of polyacrylonitrile fibers and/or particles, as illustrated in Figure 7.
  • said one or more carbon conductive additives can be applied by electrospinning, spraying, milling and/or coating.
  • said polyacrylonitrile solution or dispersion can additionally contain one or more carbon conductive additives, as illustrated in Figure 7, so that polyacrylonitrile fibers and/or particles with carbon conductive additives adopted and embedded therein can be prepared at the same time by electrospinning and/or electrospraying.
  • a solution or dispersion of one or more carbon conductive additives can be sprayed at the same time through a nozzle close to the nozzle for said fiber electrospinning and/or said electrospraying, so that said one or more carbon conductive additives can bridge from one polyacrylonitrile fiber or particle to another polyacrylonitrile fiber or particle, so as to bridge the electron conductive network in-between the polyacrylonitrile fibers and/or particles, as illustrated in Figures 16a (ii) and 16b (iii) .
  • the solvent for said solution or dispersion of one or more carbon conductive additives is not particularly limited.
  • Said one or more carbon conductive additives can be placed in the empty space of said sulfur-polyacrylonitrile composite, so as to attach the carbon conductive additives onto the outer surface of the polyacrylonitrile fibers and/or particles.
  • said one or more carbon conductive additives can be preferably adopted and embedded in the polyacrylonitrile fibers and/or particles.
  • one end of the carbon conductive additive can be embedded in one polyacrylonitrile fiber or particle, and the other end of the same carbon conductive additive can be embedded in another polyacrylonitrile fiber or particle.
  • said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black.
  • CNT carbon nanotube
  • graphite graphite
  • carbon nanoparticle such as acetylene black, SuperP carbon black or ketjen black.
  • the carbon nanotube (CNT) which can be used in the polyacrylonitrile solution or dispersion additionally containing carbon conductive additives or in the solution or dispersion of carbon conductive additives preferably has a diameter of 1–100 nm, for example about 2 nm, 3 nm, 5 nm, 10 nm, 30 nm, 40 nm, 60 nm, or 80 nm.
  • the length of the carbon nanotube (CNT) used here is not particularly limited, for example less than 5 ⁇ m, 5–15 ⁇ m, or more than 15 ⁇ m.
  • a preferable length of the CNT can be 0.3–6 times the PAN fiber diameter.
  • CNT carbon nanotube
  • SWNT Single-walled carbon nanotube
  • DWNT double-walled carbon nanotube
  • MWNT multi-walled carbon nanotube
  • said carbon nanotube (CNT) can be open-ended, and before the carbon nanotube (CNT) is used in the polyacrylonitrile solution or dispersion additionally containing carbon conductive additives or in the solution or dispersion of carbon conductive additives, it can be calcined together with sulfur in vacuo at 550–700°C, preferably at about 600°C, for about 48 hours, so that the inner voids or cavities of the carbon nanotube (CNT) can be filled with 1–30 wt. %, preferably 10–20 wt. %of sulfur to form a sulfur-carbon nanotube composite (S/CNT) , in each case based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
  • said polyacrylonitrile fibers can be cut, for example by low temperature milling or by supersonic treatment, to have an aspect ratio of 10–1,000,000, preferably 10–500, more preferably 10–100.
  • the low temperature milling can be carried out by ball milling or hand grinding, wherein liquid nitrogen can be used as the dispersing agent.
  • Figure 1b shows the schematic diagram of the PAN fibers with a relatively low aspect ratio.
  • a relatively low aspect ratio for the PAN fibers means relatively short PAN fibers.
  • Preferably shorter PAN fibers can prevent tangling up and obtain a monodisperse mixture when being dispersed, and can enhance the contact with sulfur during the SPAN synthesis.
  • step 2) the product prepared from step 1) together with sulfur can be heated at a temperature of 280–460°C, preferably 390–460°C, for 0.5–6 hours, preferably 0.5–4 hours, more preferably 0.5–3 hours, in a protective atmosphere, such as argon, so that the polyacrylonitrile can be dehydrogenated and cyclized in the presence of sulfur and bonded with sulfur or polysulfide.
  • a protective atmosphere such as argon
  • one or more carbon conductive additives can be additionally applied, for example by spraying, milling and/or coating, to the product prepared from step 2) , as illustrated in Figure 16a.
  • the content of said one or more carbon conductive additives is less than or equal to 15 wt. %, preferably less than or equal to 10 wt. %, more preferably less than or equal to 8 wt. %, most preferably less than or equal to 5 wt. %, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
  • said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black.
  • the carbon nanotube (CNT) used in step 1) can also be used here.
  • the sulfur load amount of said sulfur-polyacrylonitrile composite can be 20–55 wt. %, preferably 30–50 wt. %, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
  • Figure 16a is a schematic diagram of a synthesis route for the SPAN composite comprising carbon conductive additives by loading sulfur first and then applying carbon conductive additives.
  • PAN fibers were heated with sulfur at 450°Cfor 2 hours to obtain SPAN fibers.
  • Carbon nanoparticles (C*) were sprayed to the SPAN fibers to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) .
  • SPAN fibers were milled with carbon nanoparticles (C*) to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) .
  • a dispersion or slurry of graphite (C**) was coated to the SPAN fibers, and then dried to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) .
  • Figure 16b is a schematic diagram of another synthesis route for the SPAN composite comprising carbon conductive additives by applying carbon conductive additives first and then loading sulfur.
  • carbon nanoparticles (C*) were sprayed to PAN fibers to obtain PAN fibers comprising carbon (PAN/C) .
  • PAN fibers were milled with carbon nanoparticles (C*) to obtain PAN fibers comprising carbon (PAN/C) .
  • PAN fibers comprising carbon (PAN/C) were heated with sulfur at 450°Cfor 2 hours to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) .
  • a dispersion or slurry of graphite (C**) was coated to the sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) , and then dried.
  • Fabric shaped SPAN those of containing SPAN fibers, or those of containing the combination of SPAN fibers and carbon conductive additives, or those of containing the combination of SPAN fibers and SPAN particles, can be used as a working electrode for charging and discharging directly in a Li-Sbattery.
  • the SPAN nanoparticle alone needs to be mixed with carbon black and poly- (vinyl difluoride) (PVDF) and be pasted on an Al foil.
  • PVDF poly- (vinyl difluoride)
  • Lithium foil can be used as the counter electrode, and assembled with a separator and carbonate electrolyte consisted of LiPF 6 salt and ethylene carbonate solvent.
  • the present invention relates to an electrode, which comprises the sulfur-polyacrylonitrile composite according to the present invention.
  • said electrode can consist of the sulfur-polyacrylonitrile composite according to the present invention.
  • PAN fibers can form a fiber film, as illustrated in Figures 16a and 16b, the sulfur-polyacrylonitrile composite obtained according to the present invention from PAN fibers or from PAN fibers and particles can be directly used as an electrode, especially in case that said sulfur-polyacrylonitrile composite comprises one or more carbon conductive additives.
  • the present invention relates to a lithium-sulfur battery, which comprises the electrode according to the present invention.
  • the SPAN obtained according to the present invention has a higher electronic conductivity compared to the SPAN synthesized from the conventional PAN and sulfur only.
  • Carbon additives which are embedded in the fibers can enhance the inner electroconductivity, and carbon additives which adhere to the outer surface of the PAN can provide a conductive coating.
  • This SPAN composite electrode thus shows a high cathode capacity, a low resistance, an excellent cycling stability, and a favorable rate performance.
  • the inventors have investigated the chemical process of the dehydrogenation of polyacrylonitrile in the presence of sulfur, and revealed the chemical structure of the polyacrylonitrile-derived cyclized backbone. It has been found that a higher synthesis temperature results in a higher degree of graphitization of the polymer backbone and eventually in a higher C-rate capability and a higher cycling stability. However, the composite degrades when prepared at a higher temperature which results in a lower sulfur content and eventually in a lower cathode capacity. At the same time, the SPAN composite prepared at a higher temperature displays a larger specific surface area, which also supports the higher C-rate performance. Despite of this trade off in between the capacity and the high C-rate capability, an optimum synthesis temperature can be selected from 390 to 460°C.
  • DMF N, N–dimethylformamide
  • the PAN solutions (1) were electrospun with a 0.5 mm diameter capillary, a 25 kV applied voltage, and a distance of 200 mm between the sample collector and the spinning jet.
  • the PAN fibers (2) were collected on a 160 mm diameter drum rotating at a speed of 50 rpm at room temperature.
  • PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm were obtained respectively.
  • the PAN fibers having a diameter of about 500 nm were milled with sulfur powder (Aldrich, with a purity of>99.995%) in a mass ratio (m PAN :m S ) of 1:10, and heated in a tube furnace with Ar atomosphere at 450°Cfor 2 hours, so as to obtain a SPAN fiber composite.
  • the Elemental Analysis showed that the sulfur load amount of the SPAN fiber composite obtained was 45 wt. %based on the total weight of the SPAN fiber composite.
  • FIGS. 1 and 2a show schematic diagrams of the PAN fibers.
  • Figure 4 shows the SEM images of the PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm, prepared in Example 1 (E1) .
  • Figure 5 shows the SEM images of the SPAN fiber composites having diameters of about 300 nm, 500 nm, and 1000 nm, prepared in Example 1 (E1) .
  • the electrochemical performance of the as-prepared composites was evaluated using two electrode coin-type cells.
  • the working electrodes were prepared by pasting a mixture of active material (SPAN fiber composite having a diameter of about 500 nm) , Super P conductive carbon black (40 nm, Timical) , and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 70:15:15. After coating the mixture onto Al foil, the electrodes were dried, cut to ⁇ 12mm disks, and finally dried at 80°Cin vacuum for 4h.
  • active material SPAN fiber composite having a diameter of about 500 nm
  • Super P conductive carbon black 40 nm, Timical
  • Solef Polyvinylidene Fluoride
  • the CR2016 coin cells were assembled in an argon-filled glove box (MB-10 compact, MBraun) using 1M LiPF 6 in dimethyl carbonate (DMC) , diethyl carbonate (DEC) and ethylene carbonate (EC) mixed solvent of 1:1:1 by volume, Celgard 2400 as separator, and lithium metal as counter electrode.
  • the cycling performance was evaluated on an Arbin battery test system at 25°Cwith constant current densities.
  • the cut-off voltage was 0.9 V versus Li + /Li for discharge (Li insertion) and 3.1 V versus Li + /Li for charge (Li extraction) .
  • Figure 6 shows the charge and discharge performances of the cathode made from the SPAN fiber composite having a diameter of about 500 nm of Example 1 (E1) .
  • the Elemental Analysis showed that the sulfur load amount of the SPAN particle composite obtained was 40 wt. %based on the total weight of the SPAN particle composite.
  • FIG. 6 shows the charge and discharge performances of the cathode made from the sulfur-polyacrylonitrile (SPAN) composite in the form of particles (SPAN particle composite) of Comparison Example 1 (CE1) .
  • SPAN sulfur-polyacrylonitrile
  • Example 2 was carried out similar to Example 1, except that in step 1) carbon nanotubes as carbon conductive additive (3) were additionally dispersed into the PAN solution before the electrospinning, so as to obtain PAN fibers (2) with CNTs, as illustrated in Figure 7.
  • Figure 2b shows the schematic diagram of the PAN fibers with coaxial oriented or randomly oriented CNTs embedded.
  • Figure 8 shows the SEM images of the PAN fibers with CNT contents of 1 wt. % (a) , 2 wt. %(b) , 4 wt. % (c) , and 8 wt. % (d) , prepared in Example 2 (E2) .
  • Figure 9 shows the SEM image of the cross section of the PAN fibers with a CNT content of 8 wt. %, prepared in Example 2 (E2) .
  • Figure 10 shows the SEM image of the SPAN fiber composite with a CNT content of 8 wt. %, based on the total weight of the PAN fibers and CNTs, prepared in Example 2 (E2) .
  • the PAN fibers with a CNT content of 8 wt. %prepared in Example 2 were treated by supersonic cutting for 1 hour (Branson S-450D, with 40%amptitude) .
  • Figure 11 shows the SEM image of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) .
  • Figure 12 shows an optical photograph of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) .
  • Example 3 was carried out similar to Example 1, except that in step 1) carbon black as carbon conductive additive (3) was additionally dispersed into the PAN solution before the electrospinning, so as to obtain PAN fibers (2) with carbon black, as illustrated in Figure 7.
  • Figure 2c shows the schematic diagram of the PAN fibers with carbon black embedded.
  • Figure 13 shows the SEM images of the PAN fibers with carbon black contents of 1 wt. % (a) , 2 wt. % (b) , 4 wt. % (c) , and 8 wt. % (d) , prepared in Example 3 (E3) .
  • Example 4 was carried out similar to Example 1, except that the PAN fibers as prepared in Example 1 were mixed with the PAN particles before step 2) .
  • polyacrylonitrile particles with a particle size of about 1 ⁇ m were prepared by electrospraying from the PAN solution as prepared in Example 1 with a PAN concentration of 10 wt. %.
  • the PAN particles obtained were mixed with the PAN fibers having a diameter of about 1000 nm as prepared in Example 1 in a weight ratio of 30:70.
  • Figure 14 shows a schematic diagram of the PAN in the form of fibers and particles.
  • Figure 15 shows the SEM image of the PAN in the form of fibers and particles prepared in Example 4 (E4) .
  • the SPAN fiber composite having a diameter of about 300 nm as prepared in Example 1 was mixed by ball-milling with carbon black ( ECP-600JD, Lion Corporation, Japan) at a weight ratio of 85:15, so as to obtain a SPAN fiber composite comprising carbon black in the empty space of the composite, as illustrated in Figure 16a.
  • the Elemental Analysis showed that the sulfur load amount was 44 wt. %based on the total weight of the SPAN fiber composite obtained.
  • Example 5 The cell assembling and electrochemical evaluation were carried out similar to Example 1, except that the working electrodes were prepared by pasting a mixture of the active material (the SPAN fiber composite comprising carbon black, obtained in Example 5) and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 95:5.
  • the active material the SPAN fiber composite comprising carbon black, obtained in Example 5
  • Solef Polyvinylidene Fluoride
  • Figure 17 shows the SEM image of the SPAN fiber composite comprising carbon black in the empty space of the composite, prepared in Example 5 (E5) .
  • Figure 18 shows the 4 th charge and discharge performances of the cathode made in Example 5 (E5, solid line) .
  • Comparative Example 2 was carried out similar to Example 5, except that the SPAN particle composite as prepared in Comparative Example 1 was used instead of the SPAN fiber composite as prepared in Example 1.
  • the SPAN particle composite as prepared in Comparative Example 1 was mixed by ball-milling with carbon black ( ECP-600JD, Lion Corporation, Japan) at a weight ratio of 80:10, so as to obtain a SPAN particle composite comprising carbon black in the empty space of the composite.
  • the Elemental Analysis showed that the sulfur load amount was 40 wt. %based on the total weight of the SPAN particle composite obtained.
  • the cell assembling and electrochemical evaluation were carried out similar to Example 1, except that the working electrodes were prepared by pasting a mixture of the active material (the SPAN particle composite comprising carbon black, obtained in Comparison Example 2) and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 90:10.
  • the active material the SPAN particle composite comprising carbon black, obtained in Comparison Example 2
  • Solef Polyvinylidene Fluoride
  • Figure 18 shows the 4 th charge and discharge performances of the cathode made in Comparison Example 2 (CE2, broken line) .
  • Example 6 was carried out similar to Example 5, except that during the cell assembling and electrochemical evaluation, no binder was used, and the SPAN fiber composite comprising carbon black as prepared in Example 5 was directly used as the working electrode and pressed onto a Ni foam.
  • Figure 19 shows the 4 th charge and discharge performances of the cathode made in Example 6 (E6) .
  • Potential applications of the composite according to the present invention include high-energy-density lithium ion batteries with acceptable high power density for energy storage applications, such as power tools, photovoltaic cells and electric vehicles.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Nanotechnology (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

Provided is a sulfur-polyacrylonitrile composite comprising sulfur as well as polyacrylonitrile fibers. Further provided are a method for preparing the sulfur-polyacrylonitrile composite, and an electrode and a lithium-sulfur battery comprising the sulfur-polyacrylonitrile composite.

Description

A SULFUR-PAN COMPOSITE, A METHOD FOR PREPARING SAID COMPOSITE, AND AN ELECTRODE AND A LITHIUM-SULFUR BATTERY COMPRISING SAID COMPOSITE Technical Field
The present invention relates to a sulfur-polyacrylonitrile composite, which comprises sulfur as well as polyacrylonitrile fibers. The present invention further relates to a method for preparing said sulfur-polyacrylonitrile composite, and an electrode and a lithium-sulfur battery comprising said sulfur-polyacrylonitrile composite.
Background Art
Lithium-Sulfur (Li-S) batteries have attracted considerable attention for their high energy density and low cost. However, the theoretical energy density of 2600 Wh/kg cannot be reached because of sulfur’s insulating nature. Thus, conductive additives have to be added and consequently the theoretical value is reduced to a realistic 600 Wh/kg. Additionally, elemental sulfur forms polysulfides, Sx 2-, during reduction, which is soluble in the electrolyte. Therefore, several concepts have been elaborated upon that focus on retaining sulfur in the cathode matrix. One of the most promising concepts is to embed sulfur into a conductive matrix of pyrolized polyacrylonitrile (PAN) . This appealing sulfur-polyacrylonitrile (SPAN) composite has been used as an active cathode material showing a high specific capacity, a good efficiency, a low self-discharge, an excellent cycling stability and an improved rate performance. In view of the status quo in high energy density battery applications, the energy density of this Li-sulfur system has to be improved essentially. To do so, many researches have been conducted to improve the material capacity of SPAN composite.
Summary of Invention
The present invention provides a sulfur-polyacrylonitrile (SPAN) composite, which provides a high sulfur content and a favorable electrical conductivity. It is promising to deliver a high cathode capacity and a good rate capability when discharging under a large current density.
According to one aspect of the present invention, a sulfur-polyacrylonitrile composite is provided, which comprises sulfur as well as polyacrylonitrile fibers.
According to another aspect of the present invention, a method for preparing a sulfur-polyacrylonitrile composite is provided, said method including the following steps:
1) preparation of polyacrylonitrile fibers by electrospinning from a polyacrylonitrile solution or dispersion；
2) heating the product prepared from step 1) together with sulfur.
According to another aspect, the present invention relates an electrode, which comprises the sulfur-polyacrylonitrile composite according to the present invention.
According to a further aspect, the present invention relates a lithium-sulfur battery, which comprises the electrode according to the present invention.
Brief Description of Drawings
Each aspect of the present invention will be illustrated in more detail in conjunction with the accompanying drawings, wherein :
Figure 1 shows schematic diagrams of the PAN fibers；
Figure 2 shows schematic diagrams of the PAN fibers without carbon conductive additives (a) , with coaxial oriented or randomly oriented CNTs embedded (b) , and with carbon black embedded (c) ；
Figure 3 shows a schematic diagram of the electrospinning process for pure PAN fibers；
Figure 4 shows the Scanning Electron Microscopy (SEM) images of the PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm, prepared in Example 1 (E1) ；
Figure 5 shows the SEM images of the sulfur-polyacrylonitrile composite in the form of fibers (SPAN fiber composite) having diameters of about 300 nm, 500 nm, and 1000 nm, prepared in Example 1 (E1) ；
Figure 6 shows the charge and discharge performances of the cathodes made from the SPAN fiber composite of Example 1 (E1) and from the sulfur-polyacrylonitrile composite in the form of particles (SPAN particle composite) of Comparison Example 1 (CE1) ；
Figure 7 shows a schematic diagram of the electrospinning process for PAN fibers comprising carbon conductive additives embedded；
Figure 8 shows the SEM images of the PAN fibers with CNT contents of 1 wt. ％ (a) , 2 wt. ％ (b) , 4 wt. ％ (c) , and 8 wt. ％ (d) , prepared in Example 2 (E2) ；
Figure 9 shows the SEM image of the cross section of the PAN fibers with CNTs embedded, prepared in Example 2 (E2) ；
Figure 10 shows the SEM image of the SPAN fiber composite with CNTs embedded, prepared in Example 2 (E2) ；
Figure 11 shows the SEM image of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) ；
Figure 12 shows an optical photograph of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) ；
Figure 13 shows the SEM images of the PAN fibers with carbon black contents of 1 wt. ％(a) , 2 wt. ％ (b) , 4 wt. ％ (c) , and 8 wt. ％ (d) , prepared in Example 3 (E3) ；
Figure 14 shows a schematic diagram of the PAN in the form of fibers and particles；
Figure 15 shows the SEM image of the PAN in the form of fibers and particles prepared in Example 4 (E4) ；
Figure 16a is a schematic diagram of a synthesis route for the SPAN composite comprising carbon conductive additives by loading sulfur first and then applying carbon conductive additives；
Figure 16b is a schematic diagram of another synthesis route for the SPAN composite comprising carbon conductive additives by applying carbon conductive additives first and then loading sulfur；
Figure 17 shows the SEM image of the SPAN fiber composite comprising carbon black in the empty space of the composite, prepared in Example 5 (E5) ；
Figure 18 shows the 4th charge and discharge performances of the cathodes made in Example 5 (E5, solid line) and made in Comparison Example 2 (CE2, broken line) ； and
Figure 19 shows the 4th charge and discharge performances of the cathode made in Example 6 (E6) .
Detailed Description of Preferred Embodiments
All publications, patent applications, patents and other references mentioned herein, if not otherwise indicated, are explicitly incorporated by reference herein in their entirety for all purposes as if fully set forth.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.
When an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.
The present invention, according to one aspect, relates to a sulfur-polyacrylonitrile composite, which comprises sulfur as well as polyacrylonitrile fibers.
It is generally accepted in the relevant technical field or defined in the context of the present invention, that the term “fiber” shall be understood as having a substantially uniform diameter over its full length and having a smooth surface. A substantially uniform diameter and a smooth surface are favorable to prevent tangling up when being dispersed and to ensure a stable product quality.
Preferably the polyacrylonitrile fibers according to the present invention can be prepared by electrospinning.
The molecular weight of the polyacrylonitrile used here is not particularly limited, and can be for example 50 000–800 000 g/mol, 100 000–500 000 g/mol (Mn) .
In accordance with an embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said sulfur-polyacrylonitrile composite can further comprise polyacrylonitrile particles. The diameter of said polyacrylonitrile particles can be between 100 nm and 10 μm, preferably between 100 nm and 2 μm.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said sulfur-polyacrylonitrile composite can be formed in such a way that said polyacrylonitrile fibers and/or particles are dehydrogenated and cyclized in the presence of sulfur and bonded with sulfur or polysulfide.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, the diameter of said polyacrylonitrile fibers can be 50 nm–2 μm, preferably 100 nm–1.5 μm, for example about 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1 μm, or 1.2 μm. A preferred average distance from fiber to fiber can be 0.1–2 times the fiber diameter.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, the aspect ratio of said polyacrylonitrile fibers can be 10–1,000,000, preferably 10–500, more preferably 10–100. In the context of the present invention, the aspect ratio of the fibers is defined as the ratio of the length to the diameter of the fibers. Figure 1b shows the schematic diagram of the PAN fibers with a relatively low aspect ratio. A relatively low aspect ratio for the PAN fibers means relatively short PAN fibers. Preferably shorter PAN fibers can prevent tangling up and obtain a monodisperse mixture when being dispersed, and can enhance the contact with sulfur during the SPAN synthesis.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said sulfur-polyacrylonitrile composite can further comprise one or more carbon conductive additives, as illustrated in Figures 2b and 2c. Preferably the content of said one or more carbon conductive additives is less than or equal to 15 wt. ％, preferably less than or equal to 10 wt. ％, more preferably less than or equal to 8 wt. ％, most preferably less than or equal to 5 wt. ％, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said one or more carbon conductive additives can be preferably adopted and embedded in the polyacrylonitrile fibers and/or particles.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said one or more carbon conductive additives can bridge from one polyacrylonitrile fiber or particle to another polyacrylonitrile fiber or particle, so as to bridge the electron conductive network in-between the polyacrylonitrile fibers and/or particles, as illustrated in Figures 16a (iii) and 16b (iii) . Said one or more carbon conductive additives can be placed in the empty space of said sulfur-polyacrylonitrile composite, so as to attach the carbon conductive additives onto the outer surface of the polyacrylonitrile fibers and/or particles. Alternatively or additionally, said one or more carbon conductive additives can be preferably adopted and embedded in the polyacrylonitrile fibers and/or particles. In particular, one end of the carbon conductive additive can be embedded in one  polyacrylonitrile fiber or particle, and the other end of the same carbon conductive additive can be embedded in another polyacrylonitrile fiber or particle.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black.
The carbon nanotube (CNT) which can be used in the sulfur-polyacrylonitrile composite according to the present invention preferably has a diameter of 1–100 nm, for example about 2 nm, 3 nm, 5 nm, 10 nm, 30 nm, 40 nm, 60 nm, or 80 nm. The length of the carbon nanotube (CNT) used here is not particularly limited, for example less than 5 μm, 5–15 μm, or more than 15 μm. A preferable length of the CNT can be 0.3–6 times the PAN fiber diameter.
There is no limit to the specific form of the carbon nanotube (CNT) used here. Single-walled carbon nanotube (SWNT) , double-walled carbon nanotube (DWNT) and multi-walled carbon nanotube (MWNT) can be used.
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, said carbon nanotube (CNT) can be open-ended, and the inner voids of the carbon nanotube (CNT) can be filled with 1–30 wt. ％, preferably 10–20 wt. ％of sulfur to form a sulfur-carbon nanotube composite (S/CNT) , based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
In accordance with another embodiment of the sulfur-polyacrylonitrile composite according to the present invention, the sulfur load amount of said sulfur-polyacrylonitrile composite can be 20–55 wt. ％, preferably 30–50 wt. ％, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
The present invention, according to another aspect, relates to a method for preparing a sulfur-polyacrylonitrile composite, said method including the following steps:
1) preparation of polyacrylonitrile fibers by electrospinning from a polyacrylonitrile solution or dispersion；
2) heating the product prepared from step 1) together with sulfur.
1) Preparation of polyacrylonitrile fibers
Polyacrylonitrile fibers can be prepared by electrospinning from a polyacrylonitrile solution or dispersion, as illustrated in Figure 3. The concentration of polyacrylonitrile in said solution or dispersion is not particularly limited, for example 3–20 wt. ％, preferably 5–15 wt. ％, more preferably 6–10 wt. ％, and can be determined according to the desired diameter of polyacrylonitrile fibers. The solvent for said polyacrylonitrile solution or dispersion is not particularly limited, for example DMF. The molecular weight of the polyacrylonitrile used here is not particularly limited, and can be for example 50 000–800 000 g/mol, 100 000–500 000 g/mol (Mn) .
In accordance with an embodiment of the method according to the present invention, during step 1) , polyacrylonitrile particles can also be prepared by electrospraying from a polyacrylonitrile solution or dispersion.
In case of the sulfur-polyacrylonitrile composite further comprising polyacrylonitrile particles, the polyacrylonitrile in a combination form of fibers and particles can be prepared by mixing the PAN fibers and the PAN particles. Alternatively, the polyacrylonitrile in a combination form of fibers and particles can also be prepared at the same time by electrospinning and electrospraying. In particular, the PAN particles can be prepared by electrospraying at the same time through a nozzle close to the nozzle for electrospinning the PAN fibers.
In accordance with another embodiment of the method according to the present invention, during step 1) , one or more carbon conductive additives can be additionally applied to the polyacrylonitrile fibers and/or particles. Preferably the content of said one or more carbon conductive additives is less than or equal to 15 wt. ％, preferably less than or equal to 10 wt. ％, more preferably less than or equal to 8 wt. ％, most preferably less than or equal to 5 wt. ％, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
In particular, said one or more carbon conductive additives can be applied to the polyacrylonitrile fibers and/or particles already formed in step 1) , as illustrated in Figure 16b. Alternatively, said one or more carbon conductive additives can also be applied to the polyacrylonitrile fibers and/or particles in the course of the preparation of polyacrylonitrile fibers and/or particles, as illustrated in Figure 7.
In accordance with another embodiment of the method according to the present invention, said one or more carbon conductive additives can be applied by electrospinning, spraying, milling and/or coating.
In accordance with another embodiment of the method according to the present invention, said polyacrylonitrile solution or dispersion can additionally contain one or more carbon conductive additives, as illustrated in Figure 7, so that polyacrylonitrile fibers and/or particles with carbon conductive additives adopted and embedded therein can be prepared at the same time by electrospinning and/or electrospraying.
In accordance with another embodiment of the method according to the present invention, a solution or dispersion of one or more carbon conductive additives can be sprayed at the same time through a nozzle close to the nozzle for said fiber electrospinning and/or said electrospraying, so that said one or more carbon conductive additives can bridge from one polyacrylonitrile fiber or particle to another polyacrylonitrile fiber or particle, so as to bridge the electron conductive network in-between the polyacrylonitrile fibers and/or particles, as illustrated in Figures 16a (iii) and 16b (iii) . The solvent for said solution or dispersion of one or more carbon conductive additives is not particularly limited. Said one or more carbon conductive additives can be placed in the empty space of said sulfur-polyacrylonitrile composite, so as to attach the carbon conductive additives onto the outer surface of the polyacrylonitrile fibers and/or particles. Alternatively or additionally, said one or more carbon conductive additives can be preferably adopted and embedded in the  polyacrylonitrile fibers and/or particles. In particular, one end of the carbon conductive additive can be embedded in one polyacrylonitrile fiber or particle, and the other end of the same carbon conductive additive can be embedded in another polyacrylonitrile fiber or particle.
In accordance with another embodiment of the method according to the present invention, said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black.
The carbon nanotube (CNT) which can be used in the polyacrylonitrile solution or dispersion additionally containing carbon conductive additives or in the solution or dispersion of carbon conductive additives preferably has a diameter of 1–100 nm, for example about 2 nm, 3 nm, 5 nm, 10 nm, 30 nm, 40 nm, 60 nm, or 80 nm. The length of the carbon nanotube (CNT) used here is not particularly limited, for example less than 5 μm, 5–15 μm, or more than 15 μm. A preferable length of the CNT can be 0.3–6 times the PAN fiber diameter.
There is no limit to the specific form of the carbon nanotube (CNT) used here. Single-walled carbon nanotube (SWNT) , double-walled carbon nanotube (DWNT) and multi-walled carbon nanotube (MWNT) can be used.
In accordance with another embodiment of the method according to the present invention, said carbon nanotube (CNT) can be open-ended, and before the carbon nanotube (CNT) is used in the polyacrylonitrile solution or dispersion additionally containing carbon conductive additives or in the solution or dispersion of carbon conductive additives, it can be calcined together with sulfur in vacuo at 550–700℃, preferably at about 600℃, for about 48 hours, so that the inner voids or cavities of the carbon nanotube (CNT) can be filled with 1–30 wt. ％, preferably 10–20 wt. ％of sulfur to form a sulfur-carbon nanotube composite (S/CNT) , in each case based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
In accordance with another embodiment of the method according to the present invention, after step 1) and before step 2) , said polyacrylonitrile fibers can be cut, for example by low temperature milling or by supersonic treatment, to have an aspect ratio of 10–1,000,000, preferably 10–500, more preferably 10–100. In particular, the low temperature milling can be carried out by ball milling or hand grinding, wherein liquid nitrogen can be used as the dispersing agent. Figure 1b shows the schematic diagram of the PAN fibers with a relatively low aspect ratio. A relatively low aspect ratio for the PAN fibers means relatively short PAN fibers. Preferably shorter PAN fibers can prevent tangling up and obtain a monodisperse mixture when being dispersed, and can enhance the contact with sulfur during the SPAN synthesis.
2) Heating the product prepared from step 1) together with sulfur
In accordance with another embodiment of the method according to the present invention, during step 2) , the product prepared from step 1) together with sulfur can be heated at a  temperature of 280–460℃, preferably 390–460℃, for 0.5–6 hours, preferably 0.5–4 hours, more preferably 0.5–3 hours, in a protective atmosphere, such as argon, so that the polyacrylonitrile can be dehydrogenated and cyclized in the presence of sulfur and bonded with sulfur or polysulfide.
In accordance with another embodiment of the method according to the present invention, after step 2) , one or more carbon conductive additives can be additionally applied, for example by spraying, milling and/or coating, to the product prepared from step 2) , as illustrated in Figure 16a. Preferably the content of said one or more carbon conductive additives is less than or equal to 15 wt. ％, preferably less than or equal to 10 wt. ％, more preferably less than or equal to 8 wt. ％, most preferably less than or equal to 5 wt. ％, in each case based on the total weight of the PAN fibers and/or particles as well as the carbon conductive additives.
In accordance with another embodiment of the method according to the present invention, said one or more carbon conductive additives can be selected from carbon nanotube (CNT) , graphite, and carbon nanoparticle, such as acetylene black, SuperP carbon black or ketjen black. The carbon nanotube (CNT) used in step 1) can also be used here.
In accordance with another embodiment of the method according to the present invention, the sulfur load amount of said sulfur-polyacrylonitrile composite can be 20–55 wt. ％, preferably 30–50 wt. ％, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
Synthesis Route Example 1
Figure 16a is a schematic diagram of a synthesis route for the SPAN composite comprising carbon conductive additives by loading sulfur first and then applying carbon conductive additives.
In particular, PAN fibers were heated with sulfur at 450℃for 2 hours to obtain SPAN fibers. Carbon nanoparticles (C*) were sprayed to the SPAN fibers to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) . Alternatively or additionally, SPAN fibers were milled with carbon nanoparticles (C*) to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) . Alternatively or additionally, a dispersion or slurry of graphite (C**) was coated to the SPAN fibers, and then dried to obtain a sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) .
Synthesis Route Example 2
Figure 16b is a schematic diagram of another synthesis route for the SPAN composite comprising carbon conductive additives by applying carbon conductive additives first and then loading sulfur.
In particular, carbon nanoparticles (C*) were sprayed to PAN fibers to obtain PAN fibers comprising carbon (PAN/C) . Alternatively or additionally, PAN fibers were milled with carbon nanoparticles (C*) to obtain PAN fibers comprising carbon (PAN/C) . PAN fibers comprising carbon (PAN/C) were heated with sulfur at 450℃for 2 hours to obtain a  sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) . Alternatively or additionally, a dispersion or slurry of graphite (C**) was coated to the sulfur-polyacrylonitrile composite comprising carbon (SPAN/C) , and then dried.
Preparation of working electrode
Fabric shaped SPAN, those of containing SPAN fibers, or those of containing the combination of SPAN fibers and carbon conductive additives, or those of containing the combination of SPAN fibers and SPAN particles, can be used as a working electrode for charging and discharging directly in a Li-Sbattery. The SPAN nanoparticle alone needs to be mixed with carbon black and poly- (vinyl difluoride) (PVDF) and be pasted on an Al foil. Lithium foil can be used as the counter electrode, and assembled with a separator and carbonate electrolyte consisted of LiPF6 salt and ethylene carbonate solvent.
The present invention, according to another aspect, relates to an electrode, which comprises the sulfur-polyacrylonitrile composite according to the present invention.
In accordance with an embodiment of the electrode according to the present invention, said electrode can consist of the sulfur-polyacrylonitrile composite according to the present invention. As PAN fibers can form a fiber film, as illustrated in Figures 16a and 16b, the sulfur-polyacrylonitrile composite obtained according to the present invention from PAN fibers or from PAN fibers and particles can be directly used as an electrode, especially in case that said sulfur-polyacrylonitrile composite comprises one or more carbon conductive additives.
The present invention, according to another aspect, relates to a lithium-sulfur battery, which comprises the electrode according to the present invention.
Due to the high surface area of the PAN according to the present invention which provides a huge reaction interphase to sulfur, a higher sulfur content can be achieved compared to the conventional synthesis procedure starting with conventional crude PAN. At the same time, the SPAN obtained according to the present invention has a higher electronic conductivity compared to the SPAN synthesized from the conventional PAN and sulfur only. Carbon additives which are embedded in the fibers can enhance the inner electroconductivity, and carbon additives which adhere to the outer surface of the PAN can provide a conductive coating. This SPAN composite electrode thus shows a high cathode capacity, a low resistance, an excellent cycling stability, and a favorable rate performance.
The inventors have investigated the chemical process of the dehydrogenation of polyacrylonitrile in the presence of sulfur, and revealed the chemical structure of the polyacrylonitrile-derived cyclized backbone. It has been found that a higher synthesis temperature results in a higher degree of graphitization of the polymer backbone and eventually in a higher C-rate capability and a higher cycling stability. However, the composite degrades when prepared at a higher temperature which results in a lower sulfur content and eventually in a lower cathode capacity. At the same time, the SPAN composite  prepared at a higher temperature displays a larger specific surface area, which also supports the higher C-rate performance. Despite of this trade off in between the capacity and the high C-rate capability, an optimum synthesis temperature can be selected from 390 to 460℃.
Example 1 (E1) :
1) Preparation of polyacrylonitrile fibers
Polyacrylonitrile particles (purchased from Polysciences, Mn ＝ 200 000 g/mol, with a particle size of about 30 μm) were dissolved in N, N–dimethylformamide (DMF, purchased from Aldrich) to produce PAN solutions with respective concentrations of 6 wt. ％, 7 wt. ％, 8 wt. ％, and 10 wt. ％. As illustrated in Figure 3, the PAN solutions (1) were electrospun with a 0.5 mm diameter capillary, a 25 kV applied voltage, and a distance of 200 mm between the sample collector and the spinning jet. The PAN fibers (2) were collected on a 160 mm diameter drum rotating at a speed of 50 rpm at room temperature. PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm (corresponding to the PAN concentrations of 6 wt. ％, 7 wt. ％, 8 wt. ％, and 10 wt. ％) were obtained respectively.
2) Heating the product prepared from step 1) together with sulfur
The PAN fibers having a diameter of about 500 nm were milled with sulfur powder (Aldrich, with a purity of>99.995％) in a mass ratio (mPAN:mS) of 1:10, and heated in a tube furnace with Ar atomosphere at 450℃for 2 hours, so as to obtain a SPAN fiber composite. The Elemental Analysis showed that the sulfur load amount of the SPAN fiber composite obtained was 45 wt. ％based on the total weight of the SPAN fiber composite.
Figure 1 and 2a show schematic diagrams of the PAN fibers.
Structural evaluation:
Scanning Electron Microscopy (SEM) was employed to characterize the size and structure of the products.
Figure 4 shows the SEM images of the PAN fibers having diameters of about 300 nm, 500 nm, 800 nm, and 1000 nm, prepared in Example 1 (E1) . Figure 5 shows the SEM images of the SPAN fiber composites having diameters of about 300 nm, 500 nm, and 1000 nm, prepared in Example 1 (E1) .
Cell assembling and electrochemical evaluation:
The electrochemical performance of the as-prepared composites was evaluated using two electrode coin-type cells. The working electrodes were prepared by pasting a mixture of active material (SPAN fiber composite having a diameter of about 500 nm) , Super P conductive carbon black (40 nm, Timical) , and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 70:15:15. After coating the mixture onto Al foil, the electrodes were dried, cut toΦ12mm disks, and finally dried at 80℃in vacuum for 4h. The CR2016 coin cells were assembled in an argon-filled glove box (MB-10 compact, MBraun) using 1M LiPF6 in  dimethyl carbonate (DMC) , diethyl carbonate (DEC) and ethylene carbonate (EC) mixed solvent of 1:1:1 by volume, Celgard 2400 as separator, and lithium metal as counter electrode. The cycling performance was evaluated on an Arbin battery test system at 25℃with constant current densities. The cut-off voltage was 0.9 V versus Li+/Li for discharge (Li insertion) and 3.1 V versus Li+/Li for charge (Li extraction) .
Figure 6 shows the charge and discharge performances of the cathode made from the SPAN fiber composite having a diameter of about 500 nm of Example 1 (E1) .
Comparative Example 1 (CE1) :
The polyacrylonitrile particles (purchased from Polysciences, Mn ＝ 200 000 g/mol, with a particle size of about 30 μm) were milled with sulfur powder (Aldrich, with a purity of>99.995％) in a mass ratio (mPAN:mS) of 1:5, and heated in a tube furnace with Ar atomosphere at 450℃for 2 hours, so as to obtain a SPAN particle composite. The Elemental Analysis showed that the sulfur load amount of the SPAN particle composite obtained was 40 wt. ％based on the total weight of the SPAN particle composite.
The cell assembling and electrochemical evaluation were carried out similar to Example 1. Figure 6 shows the charge and discharge performances of the cathode made from the sulfur-polyacrylonitrile (SPAN) composite in the form of particles (SPAN particle composite) of Comparison Example 1 (CE1) .
Example 2 (E2) :
Example 2 was carried out similar to Example 1, except that in step 1) carbon nanotubes as carbon conductive additive (3) were additionally dispersed into the PAN solution before the electrospinning, so as to obtain PAN fibers (2) with CNTs, as illustrated in Figure 7.
In particular, carbon nanotubes (MWCNTs, Shenzhen Nanotech Port Co., Ltd, China, with a diameter of 20–40 nm and a length of<2 μm) were treated by a mixture of 98 wt. ％H2SO4 and 65 wt. ％HNO3 with a volume ratio of H2SO4:HNO3 ＝ 1:2 for 12 hours. Before the electrospinning, 1 wt. ％, 2 wt. ％, 4 wt. ％, and 8 wt. ％of CNTs as treated, based on the total weight of the PAN fibers and CNTs, were dispersed respectively into the PAN solution (1) as prepared in Example 1 with a PAN concentration of 10 wt. ％, so as to obtain PAN fibers with CNTs, as illustrated in Figure 7.
Figure 2b shows the schematic diagram of the PAN fibers with coaxial oriented or randomly oriented CNTs embedded.
Figure 8 shows the SEM images of the PAN fibers with CNT contents of 1 wt. ％ (a) , 2 wt. ％(b) , 4 wt. ％ (c) , and 8 wt. ％ (d) , prepared in Example 2 (E2) . Figure 9 shows the SEM image of the cross section of the PAN fibers with a CNT content of 8 wt. ％, prepared in Example 2 (E2) . Figure 10 shows the SEM image of the SPAN fiber composite with a CNT content of 8 wt. ％, based on the total weight of the PAN fibers and CNTs, prepared in Example 2 (E2) .
Example 2a (E2a) :
The PAN fibers with a CNT content of 8 wt. ％prepared in Example 2 were treated by supersonic cutting for 1 hour (Branson S-450D, with 40％amptitude) .
Figure 11 shows the SEM image of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) . Figure 12 shows an optical photograph of the short PAN fibers with CNTs embedded, prepared in Example 2a (E2a) .
Example 3 (E3) :
Example 3 was carried out similar to Example 1, except that in step 1) carbon black as carbon conductive additive (3) was additionally dispersed into the PAN solution before the electrospinning, so as to obtain PAN fibers (2) with carbon black, as illustrated in Figure 7.
In particular, before the electrospinning, 1 wt. ％, 2 wt. ％, 4 wt. ％, and 8 wt. ％of carbon black (
Figure PCTCN2015086358-appb-000001
ECP-600JD, Lion Corporation, Japan) , based on the total weight of the PAN fibers and carbon black, was dispersed respectively into the PAN solution (1) as prepared in Example 1 with a PAN concentration of 10 wt. ％, so as to obtain PAN fibers with carbon black, as illustrated in Figure 7.
Figure 2c shows the schematic diagram of the PAN fibers with carbon black embedded. Figure 13 shows the SEM images of the PAN fibers with carbon black contents of 1 wt. ％ (a) , 2 wt. ％ (b) , 4 wt. ％ (c) , and 8 wt. ％ (d) , prepared in Example 3 (E3) .
Example 4 (E4) :
Example 4 was carried out similar to Example 1, except that the PAN fibers as prepared in Example 1 were mixed with the PAN particles before step 2) .
In particular, polyacrylonitrile particles with a particle size of about 1 μm were prepared by electrospraying from the PAN solution as prepared in Example 1 with a PAN concentration of 10 wt. ％. Before step 2) , the PAN particles obtained were mixed with the PAN fibers having a diameter of about 1000 nm as prepared in Example 1 in a weight ratio of 30:70.
Figure 14 shows a schematic diagram of the PAN in the form of fibers and particles. Figure 15 shows the SEM image of the PAN in the form of fibers and particles prepared in Example 4 (E4) .
Example 5 (E5) :
The SPAN fiber composite having a diameter of about 300 nm as prepared in Example 1 was mixed by ball-milling with carbon black (
Figure PCTCN2015086358-appb-000002
ECP-600JD, Lion Corporation, Japan) at a weight ratio of 85:15, so as to obtain a SPAN fiber composite comprising carbon black in the empty space of the composite, as illustrated in Figure 16a. The Elemental Analysis showed that the sulfur load amount was 44 wt. ％based on the total weight of the SPAN fiber composite obtained.
The cell assembling and electrochemical evaluation were carried out similar to Example 1, except that the working electrodes were prepared by pasting a mixture of the active material (the SPAN fiber composite comprising carbon black, obtained in Example 5) and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 95:5.
Figure 17 shows the SEM image of the SPAN fiber composite comprising carbon black in the empty space of the composite, prepared in Example 5 (E5) . Figure 18 shows the 4th charge and discharge performances of the cathode made in Example 5 (E5, solid line) .
Comparative Example 2 (CE2) :
Comparative Example 2 was carried out similar to Example 5, except that the SPAN particle composite as prepared in Comparative Example 1 was used instead of the SPAN fiber composite as prepared in Example 1.
In particular, the SPAN particle composite as prepared in Comparative Example 1 was mixed by ball-milling with carbon black (
Figure PCTCN2015086358-appb-000003
ECP-600JD, Lion Corporation, Japan) at a weight ratio of 80:10, so as to obtain a SPAN particle composite comprising carbon black in the empty space of the composite. The Elemental Analysis showed that the sulfur load amount was 40 wt. ％based on the total weight of the SPAN particle composite obtained.
The cell assembling and electrochemical evaluation were carried out similar to Example 1, except that the working electrodes were prepared by pasting a mixture of the active material (the SPAN particle composite comprising carbon black, obtained in Comparison Example 2) and Polyvinylidene Fluoride (Solef) as binder at a weight ratio of 90:10.
Figure 18 shows the 4th charge and discharge performances of the cathode made in Comparison Example 2 (CE2, broken line) .
Example 6 (E6) :
Example 6 was carried out similar to Example 5, except that during the cell assembling and electrochemical evaluation, no binder was used, and the SPAN fiber composite comprising carbon black as prepared in Example 5 was directly used as the working electrode and pressed onto a Ni foam.
Figure 19 shows the 4th charge and discharge performances of the cathode made in Example 6 (E6) .
Potential applications of the composite according to the present invention include high-energy-density lithium ion batteries with acceptable high power density for energy storage applications, such as power tools, photovoltaic cells and electric vehicles.

Claims (30)

  1. A sulfur-polyacrylonitrile composite, characterized in that said sulfur-polyacrylonitrile composite comprises sulfur as well as polyacrylonitrile fibers.
  2. The sulfur-polyacrylonitrile composite of claim 1, characterized in that polyacrylonitrile is dehydrogenated and cyclized in the presence of sulfur and bonded with sulfur or polysulfide.
  3. The sulfur-polyacrylonitrile composite of claim 1 or 2, characterized in that said polyacrylonitrile fibers have a diameter of 50 nm–2 μm, preferably 100 nm–1.5 μm.
  4. The sulfur-polyacrylonitrile composite of any one of claims 1 to 3, characterized in that said polyacrylonitrile fibers have an aspect ratio of 10–1,000,000, preferably 10–500, more preferably 10–100.
  5. The sulfur-polyacrylonitrile composite of any one of claims 1 to 4, characterized in that said sulfur-polyacrylonitrile composite further comprises polyacrylonitrile particles.
  6. The sulfur-polyacrylonitrile composite of claim 5, characterized in that said polyacrylonitrile particles have a diameter of between 100 nm and 10 μm, preferably between 100 nm and 2 μm.
  7. The sulfur-polyacrylonitrile composite of any one of claims 1 to 6, characterized in that said sulfur-polyacrylonitrile composite further comprises one or more carbon conductive additives.
  8. The sulfur-polyacrylonitrile composite of claim 7, characterized in that said one or more carbon conductive additives are adopted and embedded in the polyacrylonitrile fibers.
  9. The sulfur-polyacrylonitrile composite of claim 7 or 8, characterized in that said one or more carbon conductive additives bridge from one polyacrylonitrile fiber to another polyacrylonitrile fiber.
  10. The sulfur-polyacrylonitrile composite of any one of claims 7 to 9, characterized in that said one or more carbon conductive additives are selected from carbon nanotube (CNT) , carbon nanoparticle and graphite.
  11. The sulfur-polyacrylonitrile composite of claim 10, characterized in that the carbon nanotube (CNT) is open-ended, and the inner voids of the carbon nanotube (CNT) are filled with 1–30 wt. ％, preferably 10–20 wt. ％ of sulfur to form a sulfur-carbon  nanotube composite (S/CNT) , based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
  12. The sulfur-polyacrylonitrile composite of any one of claims 1 to 11, characterized in that said sulfur-polyacrylonitrile composite has a sulfur load amount of 20–55 wt. ％, preferably 30–50 wt. ％, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
  13. A method for preparing a sulfur-polyacrylonitrile composite, said method including the following steps:
    1) preparation of polyacrylonitrile fibers by electrospinning from a polyacrylonitrile solution or dispersion；
    2) heating the product prepared from step 1) together with sulfur.
  14. The method of claim 13, characterized in that during step 1) , polyacrylonitrile particles are also prepared by electrospraying from a polyacrylonitrile solution or dispersion.
  15. The method of claim 14, characterized in that polyacrylonitrile particles are prepared by electrospraying at the same time through a nozzle close to the nozzle for said electrospinning.
  16. The method of any one of claims 13 to 15, characterized in that during step 1) , one or more carbon conductive additives are additionally applied to the polyacrylonitrile fibers.
  17. The method of claim 16, characterized in that said one or more carbon conductive additives are applied by spraying, milling and/or coating.
  18. The method of claim 16, characterized in that the polyacrylonitrile solution or dispersion additionally contains one or more carbon conductive additives.
  19. The method of claim 16, characterized in that a solution or dispersion of one or more carbon conductive additives is sprayed at the same time through a nozzle close to the nozzle for said electrospinning.
  20. The method of any one of claims 16 to 19, characterized in that said one or more carbon conductive additives are selected from carbon nanotube (CNT) , carbon nanoparticle and graphite.
  21. The method of claim 20, characterized in that the carbon nanotube (CNT) is open-ended, and the inner voids of the carbon nanotube (CNT) are filled with 1–30 wt. ％, preferably  10–20 wt. ％ of sulfur to form a sulfur-carbon nanotube composite (S/CNT) , based on the weight of the sulfur-carbon nanotube composite (S/CNT) .
  22. The method of any one of claims 13 to 21, characterized in that after step 1) and before step 2) , said polyacrylonitrile fibers are cut to have an aspect ratio of 10–1,000,000, preferably 10–500, more preferably 10–100.
  23. The method of any one of claims 13 to 22, characterized in that during step 2) , the product prepared from step 1) together with sulfur is heated at a temperature of 280–460℃, preferably 390–460℃, for 0.5–6 hours, preferably 0.5–4 hours, more preferably 0.5–3 hours, in a protective atmosphere.
  24. The method of any one of claims 13 to 23, characterized in that after step 2) , one or more carbon conductive additives are additionally applied to the product prepared from step 2) .
  25. The method of claim 24, characterized in that said one or more carbon conductive additives are applied by spraying, milling and/or coating.
  26. The method of claim 24 or 25, characterized in that said one or more carbon conductive additives are selected from carbon nanotube (CNT) , carbon nanoparticle and graphite.
  27. The method of any one of claims 13 to 26, characterized in that said sulfur-polyacrylonitrile composite has a sulfur load amount of 20–55 wt. ％, preferably 30–50 wt. ％, in each case based on the total weight of the sulfur-polyacrylonitrile composite.
  28. An electrode, characterized in that the electrode comprises the sulfur-polyacrylonitrile composite of any one of claims 1 to 12 or the sulfur-polyacrylonitrile composite prepared by the method of any one of claims 13 to 27.
  29. The electrode of claim 28, characterized in that the electrode consists of said sulfur-polyacrylonitrile composite.
  30. A lithium-sulfur battery, characterized in that the lithium-sulfur battery comprises the electrode of claim 28 or 29.
PCT/CN2015/086358 2014-08-07 2015-08-07 A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite WO2016019897A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201580042511.2A CN106575750A (en) 2014-08-07 2015-08-07 A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CNPCT/CN2014/083884 2014-08-07
PCT/CN2014/083884 WO2016019544A1 (en) 2014-08-07 2014-08-07 Sulfur-polyacrylonitrile composite, preparation and use thereof

Publications (1)

Publication Number Publication Date
WO2016019897A1 true WO2016019897A1 (en) 2016-02-11

Family

ID=55263023

Family Applications (3)

Application Number Title Priority Date Filing Date
PCT/CN2014/083884 WO2016019544A1 (en) 2014-08-07 2014-08-07 Sulfur-polyacrylonitrile composite, preparation and use thereof
PCT/CN2015/086358 WO2016019897A1 (en) 2014-08-07 2015-08-07 A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite
PCT/CN2015/086370 WO2016019901A1 (en) 2014-08-07 2015-08-07 A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite

Family Applications Before (1)

Application Number Title Priority Date Filing Date
PCT/CN2014/083884 WO2016019544A1 (en) 2014-08-07 2014-08-07 Sulfur-polyacrylonitrile composite, preparation and use thereof

Family Applications After (1)

Application Number Title Priority Date Filing Date
PCT/CN2015/086370 WO2016019901A1 (en) 2014-08-07 2015-08-07 A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite

Country Status (3)

Country Link
CN (2) CN106575750A (en)
DE (1) DE112015003654T5 (en)
WO (3) WO2016019544A1 (en)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10312509B2 (en) * 2014-11-10 2019-06-04 Robert Bosch Gmbh Electrode additive and an electrode comprising said electrode additive
DE102015200350A1 (en) * 2015-01-13 2016-07-14 Robert Bosch Gmbh Electrode, in particular cathodic electrode of a lithium-sulfur accumulator and method for the production
JP7053337B2 (en) * 2017-03-31 2022-04-12 株式会社Adeka Electrodes for non-aqueous electrolyte secondary batteries
WO2018187407A1 (en) * 2017-04-04 2018-10-11 University Of Pittsburgh-Of The Commonwealth System Of Higher Education Mg alloy mesh reinforced polymer/ecm hybrid scaffolds for critical-sized bone defect regeneration
US20200259207A1 (en) * 2017-09-12 2020-08-13 Qatar Foundation For Education, Science And Community Development Lithium-sulfur rechargeable battery
CN108091828B (en) * 2017-12-15 2020-05-08 苏州大学 Vulcanized polyacrylonitrile flexible positive electrode based on electrostatic spinning technology and preparation method thereof
CN109256554B (en) * 2018-09-28 2020-08-28 河南科技学院 Vulcanized polymer composite material and preparation method and application thereof
KR102150615B1 (en) * 2019-01-07 2020-09-01 경상대학교산학협력단 Composite sulfide/sulfur electrodes and manufacturing method thereof
CN109888215A (en) * 2019-02-19 2019-06-14 福建翔丰华新能源材料有限公司 A method of nucleocapsid structure lithium ion battery negative electrode material is prepared with electrostatic spinning
CN110350173B (en) * 2019-07-10 2020-08-04 南京海泰纳米材料有限公司 Lithium-sulfur soft package battery and preparation method thereof
US11355754B2 (en) 2020-01-14 2022-06-07 Phillips 66 Company Carbon-bound polysulfide positive electrode materials for batteries
CN113745477B (en) * 2021-08-25 2023-08-04 福建师范大学 Preparation method and application of sulfur-doped polyacrylonitrile-chlorella derived carbon composite potassium ion battery anode material
CN113823782B (en) * 2021-08-25 2023-08-04 福建师范大学 Preparation method and application of sulfur-doped polyacrylonitrile-chlorella-derived carbon composite sodium ion battery anode material
CN115160465A (en) * 2022-07-13 2022-10-11 长治医学院 Preparation method and application of high-sulfur-loading high-conductivity sulfurized polyacrylonitrile
CN116960313B (en) * 2023-09-20 2024-06-04 河南师范大学 Preparation method of vulcanized polyacrylonitrile anode material containing double-effect catalyst

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1396202A (en) * 2002-04-17 2003-02-12 中国科学院上海微系统与信息技术研究所 Sulfur/electric conducting polymer composition used as positive electrode of electrochemical power supply and its method
CN101577323A (en) * 2009-06-11 2009-11-11 上海交通大学 Sulfenyl anode of lithium-sulfur rechargeable battery and preparation method thereof
WO2013182360A1 (en) * 2012-06-08 2013-12-12 Robert Bosch Gmbh Method for the production of a polyacrylonitrile-sulfur composite material

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20050006540A (en) * 2003-07-09 2005-01-17 한국과학기술연구원 Lithium secondary battery comprising fine fibrous porous polymer separator and preparation method thereof
CN1569939A (en) * 2004-04-26 2005-01-26 东华大学 Carbon nanotube electrically conductive fibre and method for making same
CN100436493C (en) * 2005-08-03 2008-11-26 厦门大学 In situ polymerization one-dimensional electric high purity carbon/polyacrylonitrile composite polymer
CN101250770B (en) * 2008-03-11 2010-07-21 东华大学 Method for manufacturing polyacrylonitrile-based carbon fiber with enganced carbon nano-tube
KR101331382B1 (en) * 2008-10-17 2013-11-20 가부시키가이샤 도요다 지도숏키 Sulfur-modified polyacrylonitrile, manufacturing method therefor, and application thereof
EP2576682A4 (en) * 2010-05-28 2015-10-28 Basf Se Composite materials, production thereof and use thereof in electrical cells
CN101891930B (en) * 2010-08-17 2012-01-04 上海交通大学 Carbon nano tube-containing sulfur-based composite cathode material and preparation method thereof
WO2012070184A1 (en) * 2010-11-26 2012-05-31 株式会社アルバック Positive electrode for lithium sulfur secondary battery, and method for forming same
DE102011002720A1 (en) * 2011-01-14 2012-07-19 Robert Bosch Gmbh cathode composition
DE102011075056A1 (en) * 2011-05-02 2012-11-08 Robert Bosch Gmbh Polyacrylonitrile-sulfur composite
US8663840B2 (en) * 2011-04-12 2014-03-04 GM Global Technology Operations LLC Encapsulated sulfur cathode for lithium ion battery
DE102011075051A1 (en) * 2011-05-02 2012-11-08 Robert Bosch Gmbh Cathode material for alkali-sulfur cell
CN102208608B (en) * 2011-05-18 2013-05-29 刘剑洪 Preparation method of carbon-sulfur composite material for lithium ion battery carbon cathode material
CN102304786A (en) * 2011-07-18 2012-01-04 东华大学 Method for preparing CNT (carbon nano tube)-polyacrylonitrile fibre by melting spinning
US20150061598A1 (en) * 2012-03-14 2015-03-05 E I Du Pont De Nemours And Company Mcm-48 silica particle compositions, articles, methods for making and methods for using
CN103794764A (en) * 2012-10-26 2014-05-14 苏州宝时得电动工具有限公司 Electrode composite material preparation method, positive electrode and battery having positive electrode
CN103972480B (en) * 2014-03-26 2017-01-11 北京理工大学 Preparation method of carbon fiber/sulfur composite positive material with multilevel structure
CN103972510B (en) * 2014-05-09 2017-05-10 四川大学 Preparation method of sulfurized polyacrylonitrile anode material used for lithium secondary battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1396202A (en) * 2002-04-17 2003-02-12 中国科学院上海微系统与信息技术研究所 Sulfur/electric conducting polymer composition used as positive electrode of electrochemical power supply and its method
CN101577323A (en) * 2009-06-11 2009-11-11 上海交通大学 Sulfenyl anode of lithium-sulfur rechargeable battery and preparation method thereof
WO2013182360A1 (en) * 2012-06-08 2013-12-12 Robert Bosch Gmbh Method for the production of a polyacrylonitrile-sulfur composite material

Also Published As

Publication number Publication date
DE112015003654T5 (en) 2017-04-27
WO2016019544A1 (en) 2016-02-11
CN106661149A (en) 2017-05-10
CN106575750A (en) 2017-04-19
WO2016019901A1 (en) 2016-02-11

Similar Documents

Publication Publication Date Title
WO2016019897A1 (en) A sulfur-pan composite, a method for preparing said composite, and an electrode and a lithium-sulfur battery comprising said composite
JP6704626B2 (en) Sulfur-carbon composite and lithium-sulfur battery containing the same
US11038194B2 (en) Carbon-sulfur complex, method for producing same, and cathode and lithium-sulfur battery comprising same
JP6316949B2 (en) Carbon nanotube-sulfur composite containing carbon nanotube aggregate and method for producing the same
JP6088824B2 (en) Lithium battery electrode and lithium battery
JP7062166B2 (en) Sulfur-carbon composite, its manufacturing method and lithium secondary battery containing it
Liu et al. Binder-free Si nanoparticles@ carbon nanofiber fabric as energy storage material
KR20140128379A (en) Composition of si/c electro active material
JP6871167B2 (en) Negative electrode material, negative electrode and lithium ion secondary battery
KR20180017975A (en) Sulfur-carbon composite and lithium-sulfur battery including the same
JP2009016265A (en) Electrode for lithium battery, manufacturing method of electrode for lithium battery, lithium battery, and manufacturing method for lithium battery
JP6937908B2 (en) Sulfur-carbon complex, its manufacturing method, and lithium secondary battery containing it
KR102519438B1 (en) Composite anode active material, lithium battery comprising the same, and method of preparing the composite anode active material
US12034156B2 (en) Sulfur-carbon composite, preparation method therefor, and lithium secondary battery comprising same
Yao et al. Binder-free freestanding flexible Si nanoparticle–multi-walled carbon nanotube composite paper anodes for high energy Li-ion batteries
JP7062085B2 (en) Sulfur-carbon complex and its manufacturing method
KR102328259B1 (en) A carbon -surfur complex, manufacturing method thereof and lithium secondary battery comprising the same
KR102663583B1 (en) Manufacturing method of carbon -surfur complex
KR102081774B1 (en) Sulfur-carbon composite and lithium-sulfur battery including the same
CN116724423A (en) Metal-carbon-based composite anode active material for lithium secondary battery, method for preparing same, and secondary battery comprising same
JP5841805B2 (en) Method for producing composite material for positive electrode of lithium secondary battery
KR102363968B1 (en) A carbon -surfur complex, manufacturing method thereof and lithium secondary battery comprising the same
KR102415162B1 (en) A manufacturing method of sulfur-selenium-carbon complex, a cathode for lithium secondary battery comprising the sulfur-selenium-carbon complex manufactured by the same, and lithium sulfur-selenium battery comprising the same
KR102663584B1 (en) Manufacturing method of carbon -surfur complex
KR102639669B1 (en) A carbon -surfur complex, the manufacturing method of the same and lithium secondary battery using the same

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: 15830429

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 15830429

Country of ref document: EP

Kind code of ref document: A1