WO2012040934A1 - Cathode material for li-s battery and method for forming the same - Google Patents

Cathode material for li-s battery and method for forming the same Download PDF

Info

Publication number
WO2012040934A1
WO2012040934A1 PCT/CN2010/077530 CN2010077530W WO2012040934A1 WO 2012040934 A1 WO2012040934 A1 WO 2012040934A1 CN 2010077530 W CN2010077530 W CN 2010077530W WO 2012040934 A1 WO2012040934 A1 WO 2012040934A1
Authority
WO
WIPO (PCT)
Prior art keywords
acrylonitrile
copolymer
cathode material
carbon nanotubes
battery
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/CN2010/077530
Other languages
French (fr)
Inventor
Jiulin Wang
Wei Wei
Jun Yang
Longjie Zhou
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Jiao Tong University
Robert Bosch GmbH
Original Assignee
Shanghai Jiao Tong University
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 Shanghai Jiao Tong University, Robert Bosch GmbH filed Critical Shanghai Jiao Tong University
Priority to PCT/CN2010/077530 priority Critical patent/WO2012040934A1/en
Publication of WO2012040934A1 publication Critical patent/WO2012040934A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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
    • 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
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0569—Liquid materials characterised by the solvents
    • 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
    • H01M4/139—Processes of manufacture
    • 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
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • 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
    • 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
    • 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 cathode material for rechargeable lithium-sulfur (Li-S) battery and the method for forming the same.
  • Li-S battery is a rechargeable cell with a very high energy density.
  • the theoretical specific energy density of lithium-sulfur batteries is 2600 Wh/kg, which is one of the highest energy densities for batteries.
  • Li-S batteries may become a successor of lithium-ion cells because of their higher energy density and the lower cost.
  • sulfur is also relatively non-toxic, making these batteries relatively safe for human contact. Therefore, there is much interest in using Li-S batteries for various applications.
  • Li-S battery's conventional cathode materials have a variety of problems, including low electronic conductivity, low utilizable rate of active material, poor circulatory stability, etc, which need to be solved in rechargeable lithium batteries.
  • a Chinese patent CN1396202A discloses a composite material comprising sulfur and an electrically conductive polymer, which is used as cathodes material for electrochemical cells, wherein the electrically conductive polymer is used as a matrix, and electrically active sulfur is incorporated therein.
  • CN1396202A also discloses that polypropylene, polyacrylonitrile, polystyrene, polyoxyethylene, polyvinyl alcohol etc, can be used as electrically conductive polymer precursors.
  • Another Chinese patent CN101577323A discloses a cathode material for Li-S battery, which is prepared by mixing a sulfur based composite material, cyclodextrin binder and carbon conductivity agent, coating the mixture on an aluminum foil current collector, which is dried and pressed to obtain a cathode.
  • the sulfur based composite material comprises carbon nanotubes, sulfur and polyacrylonitrile.
  • An object of the present invention is to provide cheaper polymer materials, which can be used in cathode materials for Li-S battery as matrixes and achieve desirable charge and discharge performances.
  • dehydrogenized acrylonitrile copolymer plays the role of polymer matrix that envelopes elemental sulfur.
  • the content of dehydrogenized acrylonitrile copolymer is higher than 70%, the energy density of the cathode material will be too low.
  • its content is lower than 20%, it is not enough to completely envelope all elemental sulfur.
  • the acrylonitrile copolymer may be bipolymer or terpolymer.
  • the acrylonitrile copolymer may be preferably selected from a group consisting of acrylonitrile-butadiene copolymer, acrylonitrile-vinyl chloride copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-methyl methacrylate copolymer, and acrylonitrile-styrene copolymer, and in the acrylonitrile copolymer the molar percentage of acrylonitrile unit is 90%-99%.
  • the acrylonitrile copolymer may be acrylonitrile-butadiene-styrene copolymer or acrylonitrile-butadiene-methyl methacrylate copolymer, and in the acrylonitrile copolymer the molar percentage of acrylonitrile unit is 60%-95%, the molar percentage of butadiene unit is 2.5%-20%, and the molar percentage of other units is 2.5%-20%.
  • Elemental sulfur is an active species in the inventive cathode material.
  • the carbon nanotubes used in the present invention may be multi-wall carbon nanotubes or single wall carbon nanotubes, with outer diameters of 1 0nm-60nm and lengths of 1 ⁇ -50 ⁇ . Specifically, the outer diameter of carbon nanotubes may be 10nm-30nm, 20nm-40nm or 40nm-60nm.
  • carbon nanotubes are used to enhance the electronic conductivity of the cathode material and to stabilize the frame of said cathode material.
  • the present inventors found that it is desirable to control the content of carbon nanotubes at 0-20 wt%.
  • the present invention also provides a cathode and a Li-S battery using said cathode material.
  • the Li-S battery may comprises a negative electrode made of Li, EC-DMC-1 M LiPF 6 as the electrolyte, and a porous polyethylene membrane as a separator.
  • the present invention also provides a method for preparing a cathode material for Li-S battery, including: mixing carbon nanotubes and acrylonitrile copolymer in a ball mill, wherein ethanol is used as a dispersant; adding sulfur into the ball mill and further mixing; drying the mixture under vacuum to remove ethanol ; heat-treating the mixture under a inert atmosphere; and cooling at ambient temperature, so as to obtain a cathode material.
  • the heat-treating process is preferably conducted at a temperature of 200 ° C-450 ° C .
  • the material it is preferable to dwell the material at a constant temperature for 1 -20 hours, after the heat treating step and before the cooling step.
  • acrylonitrile copolymers commonly used in other sectors are suitable matrix materials for Li-S batteries. These acrylonitrile copolymers are usually used as textile materials or engineering plastics. Therefore, the acrylonitrile copolymers used in the present invention are preferably those commonly used as textile materials or engineering plastics. These materials are commercially available at relatively cheaper prices.
  • the present invention dramatically broadens the range of materials that are suitable as matrix materials for Li-S batteries and reduces the cost of raw materials, hence facilitates the commercial application of Li-S batteries.
  • Fig. 1 is a SEM picture of the cathode material obtained from Example 1 .
  • Fig. 2 shows charge-discharge curves obtained using a cathode made of the cathode material obtained from Example 1 .
  • Fig. 3 shows cycling response of a cathode made of the cathode material obtained from Example 1 at various current rates.
  • Embodyments 1 -4 respectively illustrate four specific acrylonitrile copolymers, which are widely used as textile materials or engineering plastics and hence, acrylonitrile copolymers are available at reasonable prices.
  • 0.1 g multi-wall carbon nanotubes with a diameter of 10-30nm were mixed with 1 g acrylonitrile-methyl methacrylate copolymer (wherein the molar percentage of methyl methacrylate unit is 5%) in a ball mill for 10 hours, using ethanol as a dispersant.
  • the mixture was then heated to 320 ° C and dwelled under a nitrogen atmosphere. After that it was kept at a constant temperature for 6 hours, and then cooled at ambient temperature.
  • the cathode material thus prepared had a sulfur content of 39 wt%.
  • Fig.1 shows the microstructure of this cathode material, wherein carbon nanotubes were homogeneously dispersed.
  • the cathode material thus prepared was made into a cathode, which used polytetrafluoroethylene as a binder, acetylene black as a conductive agent, ethanol as a dispersant, and nickel foam as a current collector.
  • This cathode was then fitted into a battery, which comprised a negative electrode made of Li, EC-DMC-1 M LiPF 6 as the electrolyte, and a porous polyethylene membrane as a separator.
  • Fig. 2 shows that the battery thus prepared demonstrated a first capacity of 775 mAh/g and a reversible capacity of 588 mAh/g.
  • Fig. 3 shows that the cathode material had a capacity of 430 mAh/g at a high current (5C).
  • 0.05g single wall carbon nanotubes with a diameter of 20-40nm were mixed with 1 g acrylonitrile-butadiene copolymer (wherein the molar percentage of butadiene unit is 1 0%) in a ball mill for 5 hours, using ethanol as a dispersant.
  • 0.15g multi-wall carbon nanotubes with a diameter of 40-60nm were mixed with 1 g acrylonitrile-butadiene-styrene copolymer (wherein the molar percentage of butadiene unit is 5%, and the molar percentage of styrene unit is 5%) in a ball mill for 15 hours, using ethanol as a dispersant.
  • the mixture was then heated to 400 ° C and dwelled under an argon atmosphere. After that it was kept at a constant temperature for 5 hours, and then cooled at ambient temperature.
  • the cathode material thus prepared had a sulfur content of 35 wt%.
  • 0.1 g single wall carbon nanotubes with a diameter of 40-60nm were mixed with 1 g acrylonitrile-butadiene- methyl methacrylate copolymer (wherein the molar percentage of butadiene unit is 5%, and the molar percentage of methyl methacrylate unit is 10%) in a ball mill for 5 hours, using ethanol as a dispersant.
  • the cathode material thus prepared had a sulfur content of 50 wt%.
  • acrylonitrile copolymers also allow better control of the morphology of cathode materials.
  • commercially available acrylonitrile copolymers with micrometer scale particle sizes may be ground by a ball mill to form particles with particle sizes of hundreds of nanometers, so as to improve the electrochemical activity of cathode materials and increase their energy density.
  • the acrylonitrile copolymer used in the present invention forms a homogeneous mixture with carbon nanotubes.
  • Carbon nanotubes play important roles in the inventive cathode materials. As conductive materials they improve the rate capability of cathode materials. Also the framework formed of carbon nanotubes buffers the expansion of cathode materials during charge and discharge cycles, and hence extends the cycle life of batteries. As a result, the inventive cathode material can work at power rate as high as 7C and achieve stable charge and discharge cycles, which meets the requirement for commercial utilization in lithium-sulfur (Li-S) batteries.
  • Li-S lithium-sulfur

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The present invention provides a novel cathode material for Li-S battery, which is consisted of a dehydrogenized acrylonitrile copolymer, sulfur and carbon nanotubes, wherein the weight percentages of these components are as below: 20%≤dehydrogenized acrylonitrile copolymer ≤80%, 20%≤ sulfur ≤80%, 1%≤ carbon nanotubes ≤30%. Also provided are a cathode and a Li-S battery using said cathode material, as well as a method for preparing said cathode material.

Description

Cathode Material for Li-S Battery and method for formi ng the same
Field of the Invention
The present invention relates to a cathode material for rechargeable lithium-sulfur (Li-S) battery and the method for forming the same.
Backgrou nd Art
The lithium-sulfur (Li-S) battery is a rechargeable cell with a very high energy density. The theoretical specific energy density of lithium-sulfur batteries is 2600 Wh/kg, which is one of the highest energy densities for batteries. Li-S batteries may become a successor of lithium-ion cells because of their higher energy density and the lower cost. In contrast with most cathode materials, sulfur is also relatively non-toxic, making these batteries relatively safe for human contact. Therefore, there is much interest in using Li-S batteries for various applications.
However, Li-S battery's conventional cathode materials have a variety of problems, including low electronic conductivity, low utilizable rate of active material, poor circulatory stability, etc, which need to be solved in rechargeable lithium batteries.
A Chinese patent CN1396202A discloses a composite material comprising sulfur and an electrically conductive polymer, which is used as cathodes material for electrochemical cells, wherein the electrically conductive polymer is used as a matrix, and electrically active sulfur is incorporated therein. CN1396202A also discloses that polypropylene, polyacrylonitrile, polystyrene, polyoxyethylene, polyvinyl alcohol etc, can be used as electrically conductive polymer precursors.
Another Chinese patent CN101577323A discloses a cathode material for Li-S battery, which is prepared by mixing a sulfur based composite material, cyclodextrin binder and carbon conductivity agent, coating the mixture on an aluminum foil current collector, which is dried and pressed to obtain a cathode. The sulfur based composite material comprises carbon nanotubes, sulfur and polyacrylonitrile.
Although the cathode materials using pure polyacrylonitrile as their matrixes have desirable charge and discharge performances, the high price of pure polyacrylonitrile renders the Li-S batteries too expensive to be competitive on the market.
It is an object of the present invention to reduce the cost of polymer materials that are used as cathode materials of Li-S battery, while remaining desirable charge and discharge performances.
Su mmary of the Invention
An object of the present invention is to provide cheaper polymer materials, which can be used in cathode materials for Li-S battery as matrixes and achieve desirable charge and discharge performances.
This object is achieved via the following technical solutions.
In one aspect, the present invention provides a cathode material for Li-S battery, which is consisted of a dehydrogenized acrylonitrile copolymer, sulfur and carbon nanotubes, wherein the weight percentages of these components are as below: 20%=¾dehydrogenized acrylonitrile copolymer =¾70%, 20%=¾ sulfur =¾80%, 0%=¾ carbon nanotubes =¾20%.
In the present invention, dehydrogenized acrylonitrile copolymer plays the role of polymer matrix that envelopes elemental sulfur. On one hand, if the content of dehydrogenized acrylonitrile copolymer is higher than 70%, the energy density of the cathode material will be too low. On the other hand, if its content is lower than 20%, it is not enough to completely envelope all elemental sulfur.
In the cathode material of the present invention, the acrylonitrile copolymer may be bipolymer or terpolymer.
As bipolymer, the acrylonitrile copolymer may be preferably selected from a group consisting of acrylonitrile-butadiene copolymer, acrylonitrile-vinyl chloride copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-methyl methacrylate copolymer, and acrylonitrile-styrene copolymer, and in the acrylonitrile copolymer the molar percentage of acrylonitrile unit is 90%-99%.
As terpolymer, the acrylonitrile copolymer may be acrylonitrile-butadiene-styrene copolymer or acrylonitrile-butadiene-methyl methacrylate copolymer, and in the acrylonitrile copolymer the molar percentage of acrylonitrile unit is 60%-95%, the molar percentage of butadiene unit is 2.5%-20%, and the molar percentage of other units is 2.5%-20%.
Elemental sulfur is an active species in the inventive cathode material. The higher the content of sulfur, the higher the energy density of the cathode material. But if its content is higher than 80%, part of the elemental sulfur will be left out of the polymer matrix formed of dehydrogenized acrylonitrile copolymer.
The carbon nanotubes used in the present invention may be multi-wall carbon nanotubes or single wall carbon nanotubes, with outer diameters of 1 0nm-60nm and lengths of 1 μηΊ-50μηι. Specifically, the outer diameter of carbon nanotubes may be 10nm-30nm, 20nm-40nm or 40nm-60nm.
In the present invention, carbon nanotubes are used to enhance the electronic conductivity of the cathode material and to stabilize the frame of said cathode material. The present inventors found that it is desirable to control the content of carbon nanotubes at 0-20 wt%.
The present invention also provides a cathode and a Li-S battery using said cathode material.
Preferably, the Li-S battery may comprises a negative electrode made of Li, EC-DMC-1 M LiPF6 as the electrolyte, and a porous polyethylene membrane as a separator.
The present invention also provides a method for preparing a cathode material for Li-S battery, including: mixing carbon nanotubes and acrylonitrile copolymer in a ball mill, wherein ethanol is used as a dispersant; adding sulfur into the ball mill and further mixing; drying the mixture under vacuum to remove ethanol ; heat-treating the mixture under a inert atmosphere; and cooling at ambient temperature, so as to obtain a cathode material.
The heat-treating process is preferably conducted at a temperature of 200 °C-450°C .
Further, it is preferable to dwell the material at a constant temperature for 1 -20 hours, after the heat treating step and before the cooling step.
The inventors noticed that it is important to control the morphology of acrylonitrile copolymers. Also it is desirable to mix acrylonitrile copolymers with carbon nanotubes homogeneously. In the field of electrochemistry, the performaces of batteries are largely determined by the morphologies of materials used therein.
In order to accelerate the commercial utilization of Li-S batteries, the cost of cell materials must be further reduced while remaining the high performances of the battery.
In this connection, after numerous experiments, the inventors of the present invention surprisingly found that some acrylonitrile copolymers commonly used in other sectors are suitable matrix materials for Li-S batteries. These acrylonitrile copolymers are usually used as textile materials or engineering plastics. Therefore, the acrylonitrile copolymers used in the present invention are preferably those commonly used as textile materials or engineering plastics. These materials are commercially available at relatively cheaper prices.
Thus the present invention dramatically broadens the range of materials that are suitable as matrix materials for Li-S batteries and reduces the cost of raw materials, hence facilitates the commercial application of Li-S batteries.
Brief Description of the Drawings
Fig. 1 is a SEM picture of the cathode material obtained from Example 1 .
Fig. 2 shows charge-discharge curves obtained using a cathode made of the cathode material obtained from Example 1 .
Fig. 3 shows cycling response of a cathode made of the cathode material obtained from Example 1 at various current rates.
Detailed Description of the Invention
The present invention is further described by way of embodyment below without any intention that the scope of the present invention is limited to the embodyments.
Embodyments 1 -4 respectively illustrate four specific acrylonitrile copolymers, which are widely used as textile materials or engineering plastics and hence, acrylonitrile copolymers are available at reasonable prices.
Embodyment 1
0.1 g multi-wall carbon nanotubes with a diameter of 10-30nm were mixed with 1 g acrylonitrile-methyl methacrylate copolymer (wherein the molar percentage of methyl methacrylate unit is 5%) in a ball mill for 10 hours, using ethanol as a dispersant.
1 0g sulfur was added into the ball mill, and the mixing was continued for another 10 hours. The mixture thus obtained was dried under vacuum to remove ethanol.
The mixture was then heated to 320°C and dwelled under a nitrogen atmosphere. After that it was kept at a constant temperature for 6 hours, and then cooled at ambient temperature. The cathode material thus prepared had a sulfur content of 39 wt%. Fig.1 shows the microstructure of this cathode material, wherein carbon nanotubes were homogeneously dispersed.
The cathode material thus prepared was made into a cathode, which used polytetrafluoroethylene as a binder, acetylene black as a conductive agent, ethanol as a dispersant, and nickel foam as a current collector.
This cathode was then fitted into a battery, which comprised a negative electrode made of Li, EC-DMC-1 M LiPF6 as the electrolyte, and a porous polyethylene membrane as a separator.
Fig. 2 shows that the battery thus prepared demonstrated a first capacity of 775 mAh/g and a reversible capacity of 588 mAh/g.
Fig. 3 shows that the cathode material had a capacity of 430 mAh/g at a high current (5C).
Embodyment 2
0.05g single wall carbon nanotubes with a diameter of 20-40nm were mixed with 1 g acrylonitrile-butadiene copolymer (wherein the molar percentage of butadiene unit is 1 0%) in a ball mill for 5 hours, using ethanol as a dispersant.
20g sulfur was added into the ball mill, and the mixing was continued for another 5 hours. The mixture thus obtained was dried under vacuum to remove ethanol.
The mixture was then heated to 280 °C and dwelled under an argon atmosphere. After that it was kept at a constant temperature for 1 0 hours, and then cooled at ambient temperature. The cathode material thus prepared had a sulfur content of 45 wt%. Embodyment 3
0.15g multi-wall carbon nanotubes with a diameter of 40-60nm were mixed with 1 g acrylonitrile-butadiene-styrene copolymer (wherein the molar percentage of butadiene unit is 5%, and the molar percentage of styrene unit is 5%) in a ball mill for 15 hours, using ethanol as a dispersant.
15g sulfur was added into the ball mill, and the mixing was continued for another 15 hours. The mixture thus obtained was dried under vacuum to remove ethanol.
The mixture was then heated to 400 °C and dwelled under an argon atmosphere. After that it was kept at a constant temperature for 5 hours, and then cooled at ambient temperature. The cathode material thus prepared had a sulfur content of 35 wt%.
Embodyment 4
0.1 g single wall carbon nanotubes with a diameter of 40-60nm were mixed with 1 g acrylonitrile-butadiene- methyl methacrylate copolymer (wherein the molar percentage of butadiene unit is 5%, and the molar percentage of methyl methacrylate unit is 10%) in a ball mill for 5 hours, using ethanol as a dispersant.
6g sulfur was added into the ball mill, and the mixing was continued for another 5 hours. The mixture thus obtained was dried under vacuum to remove ethanol.
The mixture was then heated to 450 °C and dwelled under an argon atmosphere. After that it was kept at a constant temperature for 3 hours, and then cooled at ambient temperature. The cathode material thus prepared had a sulfur content of 50 wt%.
Performances of cathode materials prepared in Examples 2-4 were measured in a similar way as in Example 1 . Results of these measurements showed that these cathode materials were as good as those made of polyacrylonitrile in terms of charge and discharge performances.
Beside the aforementioned advantages, acrylonitrile copolymers also allow better control of the morphology of cathode materials. In the present invention, commercially available acrylonitrile copolymers with micrometer scale particle sizes may be ground by a ball mill to form particles with particle sizes of hundreds of nanometers, so as to improve the electrochemical activity of cathode materials and increase their energy density.
Also, when being mixed with carbon nanotubes in a ball mill, the acrylonitrile copolymer used in the present invention forms a homogeneous mixture with carbon nanotubes. Carbon nanotubes play important roles in the inventive cathode materials. As conductive materials they improve the rate capability of cathode materials. Also the framework formed of carbon nanotubes buffers the expansion of cathode materials during charge and discharge cycles, and hence extends the cycle life of batteries. As a result, the inventive cathode material can work at power rate as high as 7C and achieve stable charge and discharge cycles, which meets the requirement for commercial utilization in lithium-sulfur (Li-S) batteries.

Claims

What is clai med is :
1 . A cathode material for Li-S battery, comprising a dehydrogenized acrylonitrile copolymer, sulfur and carbon nanotubes, wherein the weight percentages of these components are as below: 20% dehydrogenized acrylonitrile copolymer 70%, 20% sulfur 80%, 0% carbon nanotubes =¾20%.
2. The cathode material for Li-S battery according to claim 1 , wherein the acrylonitrile copolymer is acrylonitrile-butadiene copolymer, acrylonitrile-vinyl chloride copolymer, acrylonitrile-methyl acrylate copolymer, acrylonitrile-methyl methacrylate copolymer, or acrylonitrile-styrene copolymer, and molar percentage of acrylonitrile unit in the acrylonitrile copolymer is 90%-99%.
3. The cathode material for Li-S battery according to claim 1 , wherein the acrylonitrile copolymer is acrylonitrile-butadiene-styrene copolymer or acrylonitrile-butadiene- methyl methacrylate copolymer, and in the acrylonitrile copolymer the molar percentage of acrylonitrile unit is 60%-95%, the molar percentage of butadiene unit is 2.5%-20%, and the molar percentage of other units is 2.5%-20%.
4. The cathode material for Li-S battery according to claim 1 , wherein the carbon nanotubes are multi-wall carbon nanotubes or single wall carbon nanotubes, with outer diameters of 10nm-60nm and lengths of 1 μηπ-δθμηι.
5. Cathode material for Li-S battery, which comprises the cathode material for Li-S battery according to anyone of claims 1 -4.
6. A Li-S battery, which uses the cathode material for Li-S battery according to anyone of claims 1 -4.
7. A Li-S battery according to claim 6, which comprises a negative electrode made of Li, EC-DMC-1 M LiPF6 as the electrolyte, and a porous polyethylene membrane as a separator.
8. A method for preparing a cathode material for Li-S battery, including: mixing carbon nanotubes and acrylonitrile copolymer in a ball mill, wherein ethanol is used as a dispersant;
adding sulfur into the ball mill and further mixing;
drying the mixture under vacuum to remove ethanol;
heat treating and dwelling the mixture under a inert atmosphere; and cooling at ambient temperature, so as to obtain a cathode material.
9. The method of claim 8, wherein the heat treating is conducted at a temperature of 200°C-450°C .
10. The method of claim 8, wherein the heat treated material is kept at a constant temperature for 1 -20 hours after the heat treating step and before the cooling step.
PCT/CN2010/077530 2010-09-30 2010-09-30 Cathode material for li-s battery and method for forming the same Ceased WO2012040934A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/CN2010/077530 WO2012040934A1 (en) 2010-09-30 2010-09-30 Cathode material for li-s battery and method for forming the same

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/CN2010/077530 WO2012040934A1 (en) 2010-09-30 2010-09-30 Cathode material for li-s battery and method for forming the same

Publications (1)

Publication Number Publication Date
WO2012040934A1 true WO2012040934A1 (en) 2012-04-05

Family

ID=45891831

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2010/077530 Ceased WO2012040934A1 (en) 2010-09-30 2010-09-30 Cathode material for li-s battery and method for forming the same

Country Status (1)

Country Link
WO (1) WO2012040934A1 (en)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103794764A (en) * 2012-10-26 2014-05-14 苏州宝时得电动工具有限公司 Preparation method of electrode composite material, positive electrode, battery with the positive electrode
WO2014118547A1 (en) * 2013-01-30 2014-08-07 Cambridge Enterprise Limited A cathode structure for an electrical energy storage device and the method of fabricating the cathode structure
JP2014179179A (en) * 2013-03-13 2014-09-25 National Institute Of Advanced Industrial & Technology Sulfur-modified nitrile group-containing copolymer resin, and application thereof
CN104904040A (en) * 2012-11-30 2015-09-09 上海交通大学 Cathode material for a li-s battery and the method for preparing the same, a cathode made of the cathode material and a li-s battery comprising the cathode
CN109616619A (en) * 2017-09-15 2019-04-12 原子能和替代能源委员会 Method for preparing lithium-sulfur battery electrodes with large active surface area
EP4060764A1 (en) * 2021-03-18 2022-09-21 William Marsh Rice University Sulfurized carbon cathodes
US11605817B2 (en) 2019-09-24 2023-03-14 William Marsh Rice University Sulfurized carbon cathodes
WO2025098946A1 (en) 2023-11-10 2025-05-15 Arlanxeo Deutschland Gmbh Electrode composition for electrodes for electrochemical energy storage devices
EP4482882A4 (en) * 2022-02-25 2026-03-04 Airboss Of America Corp LITHIUM-CONTAINING CARBOXYLATED NITRIL BUTADIA RUBBER AND ITS USE AS A BINDING AGENT IN SULFUR CATHODS

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1337753A (en) * 2001-09-21 2002-02-27 中国科学院上海冶金研究所 Organic sulfide positive pole for thin film battery and its prepn
CN1495937A (en) * 2002-08-07 2004-05-12 ����Sdi��ʽ���� Positive electrode for lithium-sulfur battery, manufacturing method thereof, and lithium-sulfur battery
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
CN101891930A (en) * 2010-08-17 2010-11-24 上海交通大学 A sulfur-based composite cathode material containing carbon nanotubes and its preparation method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1337753A (en) * 2001-09-21 2002-02-27 中国科学院上海冶金研究所 Organic sulfide positive pole for thin film battery and its prepn
CN1495937A (en) * 2002-08-07 2004-05-12 ����Sdi��ʽ���� Positive electrode for lithium-sulfur battery, manufacturing method thereof, and lithium-sulfur battery
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
CN101891930A (en) * 2010-08-17 2010-11-24 上海交通大学 A sulfur-based composite cathode material containing carbon nanotubes and its preparation method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WANG, JIULIN ET AL.: "Sulfur Composite Cathode Materials for Rechargeable Lithium Batteries.", ADVANCED FUNCTIONAL MATERIALS., vol. 13, no. 6, June 2003 (2003-06-01), pages 487 - 492 *

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103794764A (en) * 2012-10-26 2014-05-14 苏州宝时得电动工具有限公司 Preparation method of electrode composite material, positive electrode, battery with the positive electrode
CN107768654A (en) * 2012-10-26 2018-03-06 苏州宝时得电动工具有限公司 The preparation method of electrode composite material, positive pole, the battery with the positive pole
CN104904040A (en) * 2012-11-30 2015-09-09 上海交通大学 Cathode material for a li-s battery and the method for preparing the same, a cathode made of the cathode material and a li-s battery comprising the cathode
EP2926393A4 (en) * 2012-11-30 2016-06-01 Univ Shanghai Jiaotong CATHODE MATERIAL FOR LITHIUM / SULFUR BATTERY AND METHOD FOR PREPARING SAME, CATHODE COMPRISING SAME, CATHODE MATERIAL, AND LITHIUM / SULFUR BATTERY COMPRISING SAID CATHODE
US9773581B2 (en) 2012-11-30 2017-09-26 Robert Bosch Gmbh Cathode material for a Li—S battery and the method for preparing the same, a cathode made of the cathode material and a Li—S battery comprising the cathode
WO2014118547A1 (en) * 2013-01-30 2014-08-07 Cambridge Enterprise Limited A cathode structure for an electrical energy storage device and the method of fabricating the cathode structure
JP2014179179A (en) * 2013-03-13 2014-09-25 National Institute Of Advanced Industrial & Technology Sulfur-modified nitrile group-containing copolymer resin, and application thereof
CN109616619A (en) * 2017-09-15 2019-04-12 原子能和替代能源委员会 Method for preparing lithium-sulfur battery electrodes with large active surface area
US11605817B2 (en) 2019-09-24 2023-03-14 William Marsh Rice University Sulfurized carbon cathodes
US12300818B2 (en) 2019-09-24 2025-05-13 William Marsh Rice University Sulfurized carbon cathodes
EP4060764A1 (en) * 2021-03-18 2022-09-21 William Marsh Rice University Sulfurized carbon cathodes
EP4482882A4 (en) * 2022-02-25 2026-03-04 Airboss Of America Corp LITHIUM-CONTAINING CARBOXYLATED NITRIL BUTADIA RUBBER AND ITS USE AS A BINDING AGENT IN SULFUR CATHODS
WO2025098946A1 (en) 2023-11-10 2025-05-15 Arlanxeo Deutschland Gmbh Electrode composition for electrodes for electrochemical energy storage devices

Similar Documents

Publication Publication Date Title
WO2012040934A1 (en) Cathode material for li-s battery and method for forming the same
KR101236453B1 (en) Silicon Negative Electrode, Lithium Ion Battery and a Method of Preparing the Same
Bao et al. Enhanced cyclability of sulfur cathodes in lithium-sulfur batteries with Na-alginate as a binder
CN102522560B (en) Lithium ion secondary battery and preparation method thereof
CN112786971B (en) A preparation method of negative electrode pre-lithiated lithium-ion battery and negative electrode pre-lithiated lithium-ion battery
CN109119592B (en) Lithium titanate negative electrode piece, preparation method and lithium titanate battery
WO2012149672A1 (en) Cathode material containing graphene for li-s battery and method for forming the same
CN101515640A (en) Cathode and lithium ion secondary battery containing same
CN107026262B (en) High-capacity spherical hard carbon negative electrode material coated with graphene on surface
EP4456229A1 (en) Separator, electrochemical device, and electronic device
WO2022140978A1 (en) Negative electrode plate, electrochemical device comprising negative electrode plate, and electronic device
CN112599719A (en) Negative plate, preparation method of negative plate and battery
WO2026011670A1 (en) Composite lithium iron phosphate, preparation method therefor and use thereof
US20150303457A1 (en) Cathode Material for a Li-S Battery and the Method for Preparing the Same, a Cathode Made of the Cathode Material and a Li-S Battery Comprising the Cathode
KR101657742B1 (en) Positive electrode for secondary battery and the method for manufacturing the same
JP2023538140A (en) Cathode material, and electrochemical and electronic devices containing the same
KR100758383B1 (en) Carbon Coated Sulfur Electrode for Lithium / Sulfur Secondary Battery
CN119361663B (en) A modified graphite negative electrode material for lithium ion battery and its preparation method and application
CN115394951A (en) Negative electrode active material of secondary battery and secondary battery
EP4379852A1 (en) Anode active material, method of preparing the same, and lithium secondary battery including the same
CN117117294A (en) Lithium ion battery, passivation negative electrode plate and preparation method thereof
AU2021105810A4 (en) A Preparation Method for High-performance Composite Binder of Batteries in the Energy Storage Charging System
CN111170294A (en) Preparation method of low-cost lithium iron phosphate composite material
CN116435497B (en) A blue niobium oxide negative electrode material and preparation method thereof and application in fast-charging lithium-ion batteries
CN223023282U (en) Battery cell

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: 10857697

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

32PN Ep: public notification in the ep bulletin as address of the adressee cannot be established

Free format text: NOTING OF LOSS OF RIGHTS PURSUANT TO RULE 112(1) EPC (EPO FORM 1205A DATED 07/08/2013)

122 Ep: pct application non-entry in european phase

Ref document number: 10857697

Country of ref document: EP

Kind code of ref document: A1