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Researchers Submit Patent Application, "Electrode Composite Material, Preparation Method Thereof, Cathode and Battery Including the Same", for...

June 19, 2014



Researchers Submit Patent Application, "Electrode Composite Material, Preparation Method Thereof, Cathode and Battery Including the Same", for Approval

By a News Reporter-Staff News Editor at Politics & Government Week -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Chen, Pu (Waterloo, CA); Zhang, Yongguang (Waterloo, CA); Bakenov, Zhumabay (Waterloo, CA); Konarov, Aishuak (Waterloo, CA); Doan, The Nam Long (Waterloo, CA), filed on December 11, 2013, was made available online on June 5, 2014.

The patent's assignee is Positec Power Tools (suzhou) Co., Ltd.

News editors obtained the following quote from the background information supplied by the inventors: "With the development of technology, energy especially renewable green energy is in great demand. Batteries as energy storage and conversion device are playing an irreplaceable role. Lithium-ion batteries are leading power sources due to their high weight and volume specific energy. The development of lithium-ion battery focuses on low cost, high energy density, long cycle life and green environmental protection.

"Currently, the commercialized cathode material is lithium intercalation compounds with a layer structure (lithium cobalt oxide), spinel structure (lithium manganese oxide) or olivine structure. Lithium cobalt oxide (LiCoO.sub.2) has high theoretical capacity of 275 mAh/g, along with high cost and toxicity, and its character of easy decomposition during overcharge may cause dramatically decrease of battery capacity and safety issues. Lithium manganese oxide (LiMn.sub.2O.sub.4) with theoretical capacity of 148 mAh/g, actually less than 130 mAh/g, is unstable, of which the crystal structure may deform during the charging and discharging process, resulting in low cycling efficiency; lithium iron phosphate (LiFePO.sub.4) with theoretical capacity of 172 mAh/g has poor conductivity and reducing reversible capacity. The above conventional lithium-ion battery cathode materials cannot satisfy the requirement of battery development due to their capacity and some other problems.

"Theoretical capacity of elemental sulfur is 1675 mAh/g which is much higher than those of commercialized cathode materials. The battery composed of sulfur and metal lithium has theoretical specific energy of 2600 mAh/g which is the main stream in battery development. Cathode materials containing elemental sulfur, sulfur-containing inorganic sulfides, organic sulfides, organic disulfides, organic polysulfides, or carbon-sulfur have been wildly researched by now, but some problems still exist therein.

"Firstly, conductive agents have to be added due to the poor conductivity of sulfur and sulphide; secondly, solubility of polysulfides as discharge products in electrolyte may affect the cyclability of battery. Thus, researches on sulfur based cathode material focus on how to improve the conductivity and cyclability of materials solve the solubility problem of polysulfides as discharge products.

"Chinese patent application CN101891930A provides a sulfur composite cathode material containing carbon nanotube, sulfur is embedded in the composite. The battery has enhanced capacity. But, the battery with high cost and complex process is not suitable for industrialization due to the use of high costly carbon nanotube."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "The present invention aims to provide an electrode composite material with high capacity and reversible electrochemical performance.

"Accordingly to one aspect, the invention provides an electrode composite material comprising AB.sub.xC.sub.yD.sub.z, A being selected from at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer; B being selected from sulfur; C being selected from carbon based materials; D being selected from metal oxides; l.ltoreq.x.ltoreq.20, 0.ltoreq.y
"Preferably, y=0, 0

"Preferably, 0

"Preferably, the polyacrylonitrile copolymer is selected from at least one of polyacrylonitrile methylmethacrylate copolymer, and polyacrylonitrile polypyrrole copolymer.

"Preferably, the carbon based material is selected from at least one of ketjen black, Acetylene black, active carbon, single wall carbon nano-tube, multi wall carbon nano-tube and graphene.

"Preferably, the metal oxide is selected from at least one of Mg.sub.aNi.sub.bO, MgO, NiO, V.sub.2O.sub.5, CuO, Mg.sub.cCu.sub.dO, La.sub.2O.sub.3, Zr.sub.2O.sub.3, Ce.sub.2O.sub.3, and Mn.sub.2O.sub.f; 0
"According to one aspect, the invention provides a cathode for battery, comprising an electrode composite material, the electrode composite material comprising AB.sub.xC.sub.yD.sub.z, A being selected from at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer; B being selected from sulfur; C being selected from carbon based materials; D being selected from metal oxides; l.ltoreq.x.ltoreq.20, 0.ltoreq.y
"Preferably, y=0, 0

"Preferably, 0

"Preferably, the polyacrylonitrile copolymer is selected from at least one of polyacrylonitrile methylmethacrylate copolymer, and polyacrylonitrile polypyrrole copolymer.

"Preferably, the carbon based material is selected from at least one of ketjen black, Acetylene black, active carbon, single wall carbon nano-tube, multi wall carbon nano-tube and graphene.

"Preferably, the metal oxide is selected from at least one of Mg.sub.aNi.sub.bO, MgO, NiO, V.sub.2O.sub.5, CuO, Mg.sub.cCu.sub.dO, La.sub.2O.sub.3, Zr.sub.2O.sub.3, Ce.sub.2O.sub.3, and Mn.sub.2O.sub.f; 0
"According to one aspect, the invention provides a battery, comprising a cathode, an anode and an electrolyte provided between the cathode and anode, the cathode comprising a cathode current collector and an electrode composite material, the electrode composite material comprising AB.sub.xC.sub.yD.sub.z, A being selected from at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer; B being selected from sulfur; C being selected from carbon based materials; D being selected from metal oxides; l.ltoreq.x.ltoreq.20, 0.ltoreq.y
"Preferably, y=0, 0

"Preferably, 0

"Preferably, the polyacrylonitrile copolymer is selected from at least one of polyacrylonitrile methylmethacrylate copolymer, and polyacrylonitrile polypyrrole copolymer.

"Preferably, the carbon based material is selected from at least one of ketjen black, Acetylene black, active carbon, single wall carbon nano-tube, multi wall carbon nano-tube and graphene.

"Preferably, the metal oxide is selected from at least one of Mg.sub.aNi.sub.bO, MgO, NiO, V.sub.2O.sub.5, CuO, Mg.sub.cCu.sub.dO, La.sub.2O.sub.3, Zr.sub.2O.sub.3, Ce.sub.2O.sub.3, and Mn.sub.2O.sub.f; 0
"Preferably, the electrolyte is selected from one of polyvinylidene fluoride, polyvinylidene fluoride-poly(methyl methacrylate) copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyethylene glycol boric acid ester polymers.

"Preferably, the cathode current collector is selected from one of Aluminum foil, Nickel foam, and stainless steel net.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising the following steps:

"dispersing sulfur in a first solvent to get a first solution; adding at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer into a second solvent to get a second solution; mixing the first solution, the second solution and at least one of a metal oxide by ball milling in an inert atmosphere to get a mixture; drying the mixture to remove the solvents therein; and then, heat-treating the mixture in a protective gas, cooling to get the electrode composite material; the first solvent being selected from one of carbon disulfide, toluene, and liquid hydrocarbon; the second solvent being selected from one of dimethylformamide, dimethyl acrylamide, a mixture of dimethyl acrylamide and lithium chloride, and dimethyl sulfoxide.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising the following steps:

"dispersing sulfur in a first solvent to get a first solution; soaking carbon based material into the first solution and vacuum drying to remove the solvent therein to get a first mixture; mixing the first mixture, at least one of a metal oxide, at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer by ball milling in an inert atmosphere to get a second mixture; vacuum drying the second mixture to remove the solvents therein; heat-treating the second mixture in a protective gas and then cooling to get the electrode composite material; the first solvent being selected from one of carbon disulfide, toluene, and liquid hydrocarbon.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising the following steps:

"dispersing sulfur in a first solvent to get a first solution; soaking carbon based material into the first solution and vacuum drying to remove the solvent therein to get a first mixture; adding at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer into a second solvent to get a second solution; mixing at least one of a metal oxide, the first mixture and the second solution by ball milling in inert atmosphere to get a second mixture; drying the second mixture to remove the solvents therein; heat-treating the second mixture in a protection gas, then cooling to get the electrode composite material; the first solvent being selected from one of carbon disulfide, toluene, and liquid hydrocarbon; the second solvent being selected from one of dimethylformamide, dimethyl acrylamide, a mixture of dimethyl acrylamide and lithium chloride, and dimethyl sulfoxide.

"Preferably, the metal oxide is Mg.sub.aNi.sub.bO, 0
"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising the following steps:

"mixing at least one of polypyrrole, polyacrylonitrile, and polyacrylonitrile copolymer, and at least one of metal oxides in solvent to get a first mixture; ball milling the first mixture to get a second mixture, vacuum drying the second mixture, and then heat-treating in protective gas or vacuum atmosphere, cooling to get the electrode composite material.

"Preferably, the metal oxide comprises a mixture of MgO and NiO, or a mixture of MgO and CuO.

"Preferably, the rotation speed range of the ball milling is 200-1300 rpm, the duration of ball milling is 0.5-12 h.

"Preferably, the temperature of the heat-treating is 150-450.degree. C., the duration of the heat-treating is 1-20 h.

"Preferably, the temperature of the vacuum drying is 35-75.degree. C., the duration of the vacuum drying time is 3-12 h.

"Preferably, the protective gas is selected from one of Ar, N.sub.2, a reductive gas mixture of Ar and H.sub.2, and a reductive gas mixture of N.sub.2 and H.sub.2.

"The method provided in the present invention for preparing an electrode composite material comprises solution method and mechanical ball milling, so that each component of the electrode composite material can be more uniformly dispersed. The conductivity and electrochemical performance of sulfur based electrode composite material is obviously enhanced due to the addition of carbon based material and metal oxides.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising element sulfur, at least one of polyacrylonitrile and polyacrylonitrile copolymer, comprising the following steps:

"Mixing sulfur, at least one of polyacrylonitrile and polyacrylonitrile copolymer, the resultant being heat-treated in an inert gas or vacuum atmosphere at the temperature range of 250-350.degree. C., for no less than 1 h, then the electrode composite material being obtained.

"Preferably, the polyacrylonitrile copolymer is selected from at least one of polyacrylonitrile methylmethacrylate copolymer and polyacrylonitrile polypyrrole copolymer.

"Preferably, the weight ratio range of sulfur in the electrode composite material is 70-80%.

"Preferably, the weight ratio of sulfur and at least one of polyacrylonitrile and polyacrylonitrile copolymer is 4:1.

"Preferably, the inert gas is selected from Ar, or N.sub.2.

"Preferably, the sulfur and at least one of polyacrylonitrile and polyacrylonitrile copolymer are manually mixed.

"Preferably, the duration of manual mixing is 1-30 minutes.

"Ball milling which is time and energy consuming is skipped from the method provided in the present invention for preparing the electrode composite material, which prevent the structure of polymer from damaging. The method is simple and easy to operate, and the electrode composite material prepared thereby exhibits excellent property.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising element sulfur and polyacrylonitrile, comprising the following steps:

"Sulfur and polyacrylonitrile being mechanically mixed, then dried in a vacuum atmosphere, the resultant being heat-treated in an inert gas or a vacuum atmosphere at 250-350.degree. C. for 0.5-4 h, then the electrode composite material being obtained.

"Preferably, the mechanical mixing is conducted by ball milling.

"Preferably, the duration of the heat-treatment is 2.5 h.

"Preferably, the weight ration of sulfur and polyacrylonitrile is 4:1.

"Preferably, the temperature of vacuum drying is 50-80.degree. C.

"Preferably, the duration of vacuum drying is 1-3 hours.

"The electrode composite material obtained by the method in the present invention exhibits excellent electrochemical properties and thermal stability, and the method is simple and suitable for industrialization.

"Accordingly to one aspect, the invention provides a method for preparing an electrode composite material comprising element sulfur and polypyrrole, comprising the following steps:

"Sulfur and polypyrrole being mechanically mixed, and then the electrode composite material being obtained.

"Preferably, Sulfur has a nano or micro particles.

"Preferably, polypyrrole has a branched nanostructure.

"Preferably, the diameter distribution range of polypyrrole is 25-150 nm.

"Preferably, the duration of ball-milling is 1-6 h.

"Preferably, the rotation speed of the ball-milling is 200-1200 rpm.

"Preferably, polypyrrole is synthesized as described below: pyrrole monomer is added into the cetyltrimethylammonium bromide solution, and stirred. Subsequently, aqueous solution of ammonium persulfate is added, and the solution is stirred for 12-24 h. All synthesis procedures are carried out at a temperature range between 0-5.degree. C. The final precipitate of PPy is separated via filtration, thoroughly washed and then dried.

"Preferably, the drying is carried out in a vacuum atmosphere.

"Preferably, the temperature range of the drying is 50-100.degree. C.

"Preferably, the duration of the drying is 12-24 h.

"The method of preparing the electrode composite material provided in the present invention comprises a simple one-step ball-milling without heat-treatment which may cause the loss of sulfur. As a result, the utilization of the electrode composite material is improved and the method process is simplified, the method provided in the present invention for preparing lithium ion battery with high performance sulfur based cathode has promising prospect.

BRIEF DESCRIPTION OF THE DRAWINGS

"The features of the invention will become more apparent in the following detailed description in which reference is made to the appended drawings wherein:

"FIG. 1 shows the XRD spectra of sulfur, KB and the composites S/KB and PAN/S/KB;

"FIG. 2 shows the SEM image of the composite material PAN/S;

"FIG. 3 shows the SEM image of the composite material PAN/S/Mg.sub.0.6Ni.sub.0.4O;

"FIG. 4 shows the SEM images of the composite material PAN/S/KB/Mg.sub.0.6Ni.sub.0.4O;

"FIG. 5 shows the cyclic voltammetry curves of the batteries provided in example 4 and 5;

"FIG. 6 shows the charge-discharge profiles of the battery containing S/PAN composite cathode at 0.2 C provided in example 4;

"FIG. 7 shows the charge-discharge profiles of the battery containing PAN/S/Mg.sub.0.6Ni.sub.0.4O composite cathode at 0.2 C provided in example 5;

"FIG. 8 shows the AC impedance plots of S/PAN composite provided in example 4 and PAN/S/Mg.sub.0.6Ni.sub.0.4O composite provided in example 5;

"FIG. 9 shows the capacity retention data for the battery containing PAN/S/Mg.sub.0.6Ni.sub.0.4O composite cathode at 0.2 C provided in example 5;

"FIG. 10 shows the charge-discharge profiles of the battery at 0.2 C provided in example 6;

"FIG. 11 shows the XRD spectra of the starting components S, Mg.sub.0.6Ni.sub.0.4O, and PAN/S/KB/Mg.sub.0.6Ni.sub.0.4O composite;

"FIG. 12 shows the galvanostatic charge-discharge profiles of the battery containing PAN/S/KB/Mg.sub.0.6Ni.sub.0.4O composite cathode at 0.2 C provided in example 9;

"FIG. 13 shows cyclability data along with the cycling efficiency at 0.5 C for batteries containing PAN/S/KB/Mg.sub.0.6Ni.sub.0.4O composite provided in example 5 and PAN/S/Mg.sub.0.6Ni.sub.0.4O composite provided in example 9;

"FIG. 14 shows the rate capability data for the batteries containing PAN/S/KB/Mg.sub.0.6Ni.sub.0.4O composite provided in example 5 and PAN/S/Mg.sub.0.6Ni.sub.0.4O composite provided in example 9;

"FIG. 15 shows the capacity retention data for the battery at 0.2 C provided in example 11;

"FIG. 16 shows the XRD patterns of pure S, pure PPy and PPy/S composite;

"FIG. 17 shows the TEM data of PPy/S composite;

"FIG. 18 shows the CV curves of the batteries containing PPy/S composite, S and PPy, used as a cathode active material in the lithium half-battery provided in example 21, comparative example 1 and 2;

"FIG. 19 shows the initial profiles of galvanostatic charge-discharge tests of the battery with PPy/S composite cathode provided in example 21;

"FIG. 20 shows the cyclability of batteries provided in example 21 and comparative example 1;

"FIG. 21 shows AC impedance behavior of the batteries containing S and PPy/S cathode provided in example 21 and comparative example 1;

"FIG. 22 shows SEM images of the PAN/S composite without heat treatment;

"FIG. 23 shows SEM images of the PAN/S composite with heat treatment;

"FIG. 24 shows the charge/discharge profiles of the battery at 0.2 C provided in example 23;

"FIG. 25 shows the charge/discharge profiles of the battery provided in comparative example 3 at 0.2 C;

"FIG. 26 shows the cycle ability of the battery provided in example 23;

"FIG. 27 shows the cycle ability of the battery provided in comparative example 3;

"FIG. 28 shows the cycle ability of the battery containing PAN/S composite provided in example 23 at different current density;

"FIG. 29 shows the FTIR spectra of PAN and the composites provided in the example 24-26 and comparative example 4;

"FIG. 30 shows the surface morphology of the composite S/DPAN provided in example 26 by FE-SEM;

"FIG. 31 shows the surface morphology of the composite S/PAN provided in comparative example 4 by FE-SEM;

"FIG. 32 shows the thermal behavior of S, PAN, composites S/DPAN and S/PAN by TG-DTA and its time derivative DTG;

"FIG. 33 shows the thermal behavior of S/PAN composites provided in example 24-26 and comparative example 4;

"FIG. 34 shows the variation of specific discharge capacity at 5th cycle upon changing the heat treatment time, at 0.2 C;

"FIG. 35 shows the CV curves of the battery provided in example 25 with the scanning rate of 0.1 mV/s;

"FIG. 36 shows the charge/discharge profiles of the battery provided in example 25 at the 1.sup.st, 2.sup.nd, 5.sup.th and 10.sup.th cycles;

"FIG. 37 shows the cycle ability of the battery provided in example 25."

For additional information on this patent application, see: Chen, Pu; Zhang, Yongguang; Bakenov, Zhumabay; Konarov, Aishuak; Doan, The Nam Long. Electrode Composite Material, Preparation Method Thereof, Cathode and Battery Including the Same. Filed December 11, 2013 and posted June 5, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=2416&p=49&f=G&l=50&d=PG01&S1=20140529.PD.&OS=PD/20140529&RS=PD/20140529

Keywords for this news article include: Anions, Oxides, Sulfur, Alkynes, Toluene, Polyenes, Acetylene, Chemistry, Fluorides, Chalcogens, Polyvinyls, Acrylamides, Electrolytes, Hydrocarbons, Electrochemical, Vinyl Compounds, Carbon Disulfide, Carboxylic Acids, Oxygen Compounds, Hydrofluoric Acid, Benzene Derivatives, Inorganic Chemicals, Methylmethacrylates.

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