Title of Invention

"A PROCESS FOR THE PREPARATION OF AN ORGANO-INORGANIC HYBRID NANOCOMPOSITE"

Abstract

This invention relates a process for the preparation of a process for the preparation of an organo-inorganic hybrid nanocomposite prepared using a transition metal oxide/ dichalcogenides such as V2O5, M0O3, WO3, VS2, M0S2, WS2, ethylene dioxythiophene and a conducting polymer, useful for high energy density cathode materials for rechargeable lithium batteries, which comprise of mixing the oxide/dichalcogenides (M) with a monomer capable of conducting polymers such as Polyaniline (PANI), Polypyrole (PPY), Polythiophene (PTH), Poly (3,4-ethylenedioxythiophene) (PEDOT) (X) in a solvent (Y) such as distilled water under refluxing condition at temperature ranging from 110°C-125°C for a period in the range of 12-18 hrs followed by transferring to an autoclave under microwave solvothermal condition as herein described at temperature ranging from 120°C-150°C for the period of 5-10min.

Full Text

FIELD OF INVENTION This invention relates to a novel process for the preparation of nanostructured organo-inorganic hybrid materials as high energy density cathodes for rechargeable lithium batteries. BACKGROUND OF THE INVENTION The growing demand for portable power sources of high energy power density in recent years has stimulated a great deal of interest in rechargeable lithium batteries In particular, rechargeable lithium ion batteries have become increasingly important as power sources for a multitude of portable consumer electronics and "ceo-friendly" electric vehicles. Currently, one of the important materials of choice for the cathode is Lithium Cobalt Oxide, but attended with the disadvantage of high cost and environmental toxicity of cobalt despite good capacity and rechargeability Consequently, much effort has been put to develop new cathode materials with limitations. One successful approach is based on the development of conducting polymer nanocomposite with inorganic transition metal oxides/dichalcogenides, where light weight and flexibility are the essential advantages. Development of novel routes for the preparation of nanocomposite have attracted increased attention due to its fascinating aspects of materials chemistry possible. For example, development of techniques such as sol-gel and other soft chemical methods have lead to the preparation of engineered composite materials (K.Rajeshwar. US Patent 5 334292, 1994; H.Yoneyama, Japanese Patent JP 04136195 A2, 1992) The microwave assisted route is yet another novel method of synthesis and is a very rapidly developing area of materials research. Several reports have appeared where conventional preparative techniques have been substituted by microwave method (K J Rao, et al., Chem. Mater. 11(1999)882; A Vadivel Murugan, ct ai,, Materials Chemistry & Physics 71(2001)98.) Micrmvave-hydrothermal synthesis is generally quite faster, simpler and energy efficient If a liquid is exposed to microwave radiation, the microwaves induce rotation of the dipoles within the liquid, causing polar molecules to align and relax in the field of oscillating electromagnetic radiation. Energy is dissipated from these dipole rotations, which will cause the liquid to become hot. In such a way, the heat is produced within the liquid and not transferred from the vessel as in a hot-plate system In a microwave digestion, the liquid is therefore often at a higher temperature than the vessel in which it is held. This efficient way of localized heating has been reported to lead to the increase in reaction rates, improvement of the interaction of polymer with the host matrix and yields. One of the objectives of the present invention is to develop a successful method for the preparation of nanocomposite by soft method of microwave intercalation of a hetroaromatic thiophene monomer such as 3,4-ethylenedioxy thiophene (EDOT). It appears to be one of the most stable conducting polymers currently available (Bayer, AG Eur Patent 0 3339 340, 1989) and which is known to be more "eco-friendly" to undergo oxidative polymerization when intercalated into highly oxidizing materials such as V2O5 More significantly, Poly (3,4-ethylenedioxy thiophene, hitherto referred to as PEDOT, is one of the recently found excellent conducting polymers which has been attracting growing interest for application in antistatic transparent films (Bayer AG, US Patent 5035926, 1991), electroplating (C.M.J.Mutsaers, et al Eur.Pat.Applic. No PHN 14.385 EP-P (1993) Supercapacitor and lithium batteries (O Inganas, et al Adv.Mater, 11(1999) 1214; A Vadivel Murugan, et al J Mater.Chem,l 1(2001)2470; P.Novak, et al Chem. Rev, 97 (1997) 207) Hence, we have been selected this to design a new nanocomposite cathode material by intercalation into V2O5 host and the results indicate that the nanocomposite is highly attractive for applications such as cathodes in lithium batteries due to several improved properties like room temperature conductivity and lithium ion transport. The resulting nanocomposite display higher discharge capacities and greater reversibility for Lithium insertion than those observed for V2O5 aloneOBJECTS OF THE INVENTION An object of this invention is to propose a novel process for the preparation of nanostructured organo-inorganic hybrid materials. Another object of this invention is to propose a novel process for the preparation of nanostructured organo-inorganic hybrid materials which can advantageously be used as high energy density cathodes for rechargeable lithium batteries. DESCRIPTION OF THE INVENTION According to this invention there is provided a process for the preparation of an organo-inorganic hybrid nanocomposite prepared using a transition metal oxide/ dichalcogenides such as V2O5, M0O3, WO3, VS2, M0S2, WS2, ethylene dioxythiophene and a conducting polymer, useful for high energy density cathode materials for rechargeable lithium batteries, which comprise of mixing the oxide/dichalcogenides (M) with a monomer capable of conducting polymers such as Polyaniline (PANI), Polypyrole (PPY), Polythiophene (PTH), Poly (3,4-ethylenedioxythiophene) (PEDOT) (X) in a solvent (Y) such as distilled water under refluxing condition at temperature ranging from 110°C-125°C for a period in the range of 12-18 hrs followed by transferring to an autoclave under microwave solvothermal condition as herein described at temperature ranging from 120°C-150°C for the period of 5-10min. The present invention provides the synthesis of nanocomposite by using Ethylene dioxythiophene (EDOT) and crystalline V2O5 powder in a solvents with time period of 5 to 10 min by the microwave irradiation at 150-180°C. Various aspects of the nanocomposite formations, like the effect of change of amount of organic molecules into the inorganic host and different conditions of nanocomposite have been described herein According to one preferred embodiment of the present invention, the PREDOT/V2O5 nanocomposite was obtained by refluxing an aqueous solution of dispersed crystalline V2O5 powder (80-82 gl ) and Ethylene dioxythiophene (EDOT) monomer under air for 12 to 18 hrs. After completion of the reaction, the solid was filtered off and washed repeatedly with water several times followed by acetone and dried at room temperature According to another feature of the present invention, the PREDOT/V2O5 nanocomposite materials were obtained by the soft process of Microwave-solvothermal method to appropriate amount of EDOT with V2O5 in aqueous medium The bluish black product obtained was dried at room temperature. The product was characterized by X-ray diffraction (XRD) patterns which confirmed the formation of polymer monolayer and double layers in the V2O5 frame work. According to the application feature of the present invention, electrochemical measurements were performed in galvanostatic mode using a computer controlled potentiostat/galvanostate. All manipulations of air sensitive materials as well "as the cell assemblies were carried out in an inert atmosphere of an argon filled glove box, where potential versus capacity curves for the first two cycles was observed up to a cut-off voltage of 2.0V (versus Li-r/Li), corresponding to the uptake of -2 Li per V2O5 unit, are presented in fig. 2 .Pristine V2O5 shows distinct plateau due to the structural change from a-V2O5 to e-U V2O5 and then finally to the y-LixV2O5 phase. By contrast, the potential decreases more smoothly without any sign of phase transformation for the nanostructured hybrid samples. The discharge capacity of the PEDOT/V2O5 nanocomposite is found to be 330mAhg-1 in which is significantly larger than that of 140mAhg-l for pristine V2O5. The improved performance is presumably due to the result of the larger separation between \anadium oxide lasers due to the presence of the polymer . which gives a structural stabilization. Therefore, the judicious conducting polymer incorporation into V2O5 is a way to improve its electrochemical properties by suppressing phase transformation and increasing the interlayer distance. The present invention is described and illustrated by the following examples which should not, however, be construed to limit the scope of the invention. EXAMPLE I 2.02 gm of Vanadium pentoxide was mixed with appropriate amount of Ethylenedioxy thiophene in the double distilled water in such a way that molar ratio of EDOT V2O5 was from 0.02 to 0.80. After the initial mixing, it was refluxed for 12-18 hrs in a round bottom flask followed by cooling to room temperature. The solid was filtered off and washed repeatedly with water and acetone until the initial light yellow color to the filtrate was totally absent, and the bluish black powder was dried in air. The product was characterized by X-ray diffraction (XRD), which confirmed the formation of polymer ionolayer in V2O5. The inter layer spacing of V2O5 expanded from 4.32 to 13.84A and the inici layer separation was consistent with the existence of a monolayer of PEDOT in the frame work. The application potential of these nanocomposites as high capacity cathode material in rechargeable lithium batteries was tested by coupling with a large area lithium incluide in 1M LiClO.4, dissolved in a mixture of ethylene carbonate and dimethyl carbonate( 50/50 by volume) to form the test electrochemical cell. All charge-discharge measurements were performed in galvanostatic mode using a computer controlled potentiostat/galvanostate. All manipulations of air sensitive materials as well as the cell assemblies were carried out in an inert atmosphere of an argon filled glove box. where an enhancement of the discharge capacity from 140mAhg-1to 330mAhg-1 was observed when pristine V2O5 was substituted by the nanocomposite. EXAMPLE II The PEDOT/V2O5 nanocomposite was obtained by the soft process of Micro wave-solvothermal method to 0.03-0.92ml of EDOT was mixed with 2.015-2.102g of V2O5 in aqueous solution of 60ml of up to 60% of capacity in a Teflon (TFM) lined container of JOOml capacity. The autoclave was maintained at 150°C from 5min to lOmin and then air cooled to room temperature. The precipitate was filtered off and thoroughly washed with distilled water and acetone. The characterization of the product as described in example I, had shown that the inter layer spacing of V2O5 expanded from 4.34 to 14.10A and finally had been increased upto 19.02 A. This interlayer separation was consistent with the existence of a mono and double layers of PEDOT in the V2O5 frame work. The application potential of these nanocomposite as high capacity cathode material in rechargeable lithium batteries were tested by coupling with a lithium foil anode in 1M LIClC4, dissolved in a mixture of ethylene carbonate and dimethyl carbonate(50/50 by volume) to form the electrochemical cell. All charge-discharge measurements were performed in galvanostatic mode using a computer controlled potentiostat/galvanostat. All manipulations of air sensitive materials as well as the cell assemblies were carried out in an inert atmosphere of an argon filled glove box. where an enhancement of discharge capacity from 14mAhg-1 to 330mAhg-1 and cycle life, which is larger than that of pristine V2O5. The improvement in electronic conductivity and discharge capacity results are summari/ed in the table-1. The intercalation of conducting polymer into transition metal oxide to form the nanocomposite with respect to the reaction time is shown in Figure 1 of the accompanying drawings. ADVANTAGES The hybrid Nan composite prepared according to the present invention has several advantages. First, since the present material is light weight, flexible and high capacity cathode material for lithium batteries. Significantly, the most successful preparation of theNPEDOT/V2O5 Nan composite are obtained by the versatile process of Microwave-solvothermal method. Moreover, our microwave assisted preparation is much faster, cleaner and more economical than the reflux method. Finally, the improved performance is presumably due to structural stabilization which results from incorporation of the polymer between vanadium oxide layer. The results also suggest that the polymer Nan composite acts as a better cathode material than pristine V2O5 oxide material by enhancing lithium diffusion. Evolution of discharge capacity with the number of cycles for various cathode materials compared with PEDOT/V2O5 Nan composite is shown in Figure 2 of the accompanying drawings. able Comparison of room temperature conductivity, interlayer spacing, open circuit voltage and discharge capacity able Nan composites prepared from various EDOT/V2O5 ratio. (Table Removed) WE CLAIM; 1. A process for the preparation of an organo-inorganic hybrid nanocomposite prepared using a transition metal oxide/ dichalcogenides such as V2O5, M0O3, WO3, VS2, M0S2, WS2, ethylene dioxythiophene and a conducting polymer, useful for high energy density cathode materials for rechargeable lithium batteries, which comprise of mixing the oxide/dichalcogenides (M) with a monomer capable of conducting polymers such as Polyaniline (PANI), Polypyrole (PPY), Polythiophene (PTH), Poly (3,4-ethylenedioxythiophene) (PEDOT) (X) in a solvent (Y) such as distilled water under refluxing condition at temperature ranging from 110°C-125°C for a period in the range of 12-18 hrs followed by transferring to an autoclave under microwave solvothermal condition as herein described at temperature ranging from 120°C-150°C for the period of 5-10min. 2. A process as claimed in claim 1 wherein the autoclave was maintained at 120-130°C from 5 to 10 min under microwave solvothermal condition to obtain the nanocomposite. 3. A process as claimed in claim 1 wherein the molar ratio of the transition metal oxide/dichalcogenides (M) and monomer of conducting polymer (X) ranges from 0.02-0.80. 4. A process as claimed in claim 1 wherein the complete nanocomposite (MX) is formed at 8-10 min under microwave solvo thermal condition. 5. A process for the preparation of an organo-inorganic hybrid nanocomposite substantially as herein described and illustrated. .

Documents:

915-DEL-2002-Abstract (09-04-2008).pdf

915-DEL-2002-Abstract-(18-09-2008).pdf

915-del-2002-abstract.pdf

915-DEL-2002-Claims (09-04-2008).pdf

915-DEL-2002-Claims-(18-09-2008).pdf

915-del-2002-claims.pdf

915-del-2002-complete specification (granted).pdf

915-DEL-2002-Correspondence-Others (09-04-2008).pdf

915-DEL-2002-Correspondence-Others-(10-01-2011).pdf

915-DEL-2002-Correspondence-Others-(18-09-2008).pdf

915-del-2002-correspondence-others.pdf

915-del-2002-correspondence-po.pdf

915-DEL-2002-Description (Complete)-(18-09-2008).pdf

915-del-2002-description (complete)-09-04-2008.pdf

915-del-2002-description (complete).pdf

915-DEL-2002-Drawings-(18-09-2008).pdf

915-del-2002-drawings.pdf

915-del-2002-form-1.pdf

915-DEL-2002-Form-15-(10-01-2011).pdf

915-del-2002-form-18.pdf

915-del-2002-form-2.pdf

915-del-2002-form-3.pdf

915-DEL-2002-GPA-(10-01-2011).pdf

915-DELNP-2002-Correspondence-Others-(24-03-2009).pdf

915-DELNP-2002-Form-1-(24-03-2009).pdf

915-DELNP-2002-GPA-(24-03-2009).pdf

915-DELNP-2002-Petition-137-(24-03-2009).pdf