Title of Invention

A PROCESS FOR THE SYNTHESIS OF LITHIUM NICKEL MAGNESIUM VANADATE USEFUL AS CATHODE MATERIAL

Abstract

The present invention relates to a process for the preparation of lithium nickel magnesium vanadate (LiNio.5Mgo. 5V04) useful as cathode material. The product is useful as a cathode material for high voltage lithium ion or rocking chair or lithium intercalated cells either in non aqueous or in polymer electrolyte cells. This invention relates to the preparation of the lithium nickel magnesium vanadate (LiNio 5Mgo 5V04) a composite material which is very useful for high voltage lithium secondary cells which can be prepared by mixing oxides of nickel, magnesium and vanadium with lithium carbonate LiOH or LiO or LiN03 by solid state wet grinding and then processing through thermal reaction.

Full Text

The present invention relates to a process for the preparation of lithium nickel magnesium vanadate (LiNio.5Mgo 5VO4) useful as cathode material. The product is useful as a cathode material for high voltage lithium ion or rocking chair or lithium intercalated cells either in non aqueous or in polymer electrolyte cells. This invention relates to the preparation of the lithium nickel magnesium vanadate (LiNio 5Mgo 5VO4) a composite material which is very useful for high voltage lithium secondary cells which can be prepared by mixing oxides of nickel, magnesium and vanadium with lithium carbonate LiOH or LiO or LiNO3 by solid state wet grinding and then processing through thermal reaction. Lithium nickel magnesium vanadate (LiNio.sMgo.sVO4) is a useful positive electrode material for reversible rechargeable secondary cells based on lithium. In earlier studies inverse LiNiVO4 compound was synthesized by using LiNiCh with V203 at 800°C in a furnace for 24 hours. [George Ting-Kuo fey, W.U. Li and J.R. Dhan , J. Electrochera Soc. 141 (1994) 2279 ]. Subsequently a mixture Li2C03, NiC03 and V205 were heated at 600°C in a furnace for several hours. [C.Gonzaler, M.Galtan, M.L. Veija, R. Saez-puche, C.Pico, J. Mat. Sci., 29(1994) 3458). LiNiVO4 was also prepared by heating LiNi02 + NH4VO3 under controlled thermal conditions. [ Jooji, Teeinkew Fuel, JP.07,320,741 (95,320,741) (Cl. H01M4 / 58)] LiNO3 , (NiNo3)2, Vanadium acetyl acetonate mixture was heated for 12 hours to get LiNiVO4. [G.Ting -K.S.Chen, J. Power Sources, 81-82(1999)]. LiNiVO4 has been prepared to increase the stability and eyclebility. However, the addition of Mg ion in the spinel structure of peroskovite certainly has three distinct advantages they are 1. increasing the metal components. 2. Increasing the voltage of the cell 3. Increasing the single electrode potential of the cathode due to mixed potential of the added components. Thus, LiNiVO4 spinel oxide when becomes LiNiMgVO4 by the addition of Mg +2 ion which also shows not only the peroskovite structure but also an increases voltage 0.2 volt and better intercalation property as shown by quartz crystal balance study. Hence, that a new approach has been attempted to increase the voltage and intercolation properly by the addition of Mg +2 in LiNiVO4 ceramic material. This method is first time done and no reference is available. The main object of the present invention is to provide a process for preparation of lithium nickel magnesium vanadate useful as cathode material. It uses by a novel wet grinding procedure. A novel method of preparing this compound namely lithium nickel magnesium vanadate (LiNi0.5Mgo 5VO4) was developed in which an uniform mixing of oxides of nickel, magnesium and vanadium with lithium carbonate or lithium hydroxide or lithium oxide or lithium nitrate and this mixture was made into a paste by adding required quantity of glycerol and the paste was heated in between 6()0-800°C continuously in an electric or muffle furnace for 10-14 hours. The prepared product was subjected to X-ray examination and phase purity. Accordingly the present invention provides a process for preparation of lithium nickel magnesium vanadate (LiNio.5Mgo.5VO4) useful as cathode material which comprises : preparing a paste by mixing oxides of nickel, magnesium, vanadium and lithium source in equimolar quantities with a flux in glycerol, heating the so prepared paste upto 800° C for a period of 12 hours followed by cooling to get lithium nickel magnesium vanadate. In an embodiment of this present invention the lithium source may be selected from Li2CO3, Li2O„ LiOH , LiNO3 and mixed with NiO and MgO and V2O5 in equimolar proportion. In another embodiment of this invention Li2C03 and Li20 are mixed in different quantities such that the ratio of Li: Ni: Mg: V205 is of equimolar proportions. In yet still another embodiment of this present invention Li2CO3 and LiNO3 are mixed in different quantities such that the ratio of Li: Ni: Mg: V2O5 is of equimolar proportions. Yet in still another embodiment of this present invention Li2CO3/ LiNO3 / LiOH are mixed in different quantities such that the ratio of Li: Ni: Mg: V205 is of equimolar proportions. In yet still another embodiment of this invention all solid materials are used. In still yet another embodiment of this present invention glycerol is used as a binding agent which does not allow side reactions to occur. In yet another embodiment of this present invention the product obtained by a single step reaction. In still another embodiment of this present invention the temperature of this reaction to get the product is in between 500-800°C. The present invention describes the method of preparing lithium nickel magnesium vanadate (LiNio,5Mgo ,5VO4) for lithium battery, by heating a paste prepared by mixing fine AR samples of Li2CO3 or LiOH or Li2O or LiNO3 with NiO, MgO or V2O5 with glycerol and citric acid as flux. The mixture is made of equimolar quantities of Li20 / Li2C03/ LiOH / LiNO3 with NiO, MgO and V205 . The paste was initially heated slowly in an electric furnace to evaporate off glycerol in order to get a dried mass maintaining the temperature around 150-250 C f strongly in between 600-800°C for 12 hours. The product formed was slowly cooled to room temperature and was then ground well and then examined by X-ray for phase purity and identity an the colour and the particle size of the product were also checked. It was found that the colour of the product was deep yellow and was homogeneous with particle size ranging from 5-10um. X-ray analysis confirmed the product formation of composition LiNio.5Mgo.sVO4 according to figure 1. Further embodiment of the invention the flux used may be selected from citric acid , glycine. The following examples are given by way illustration & therefore should not be construed to limit the scope of the present invention. Example -1 A mixture of AR grade samples of 0.75 gm of Li2C03, 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V20? are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -2 A mixture of AR grade samples of 0.5 gm of Li20, 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V20? are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -3 A mixture of AR grade samples of 1.82 gm of LiOH, 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V2Os are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example- 4 A mixture of AR grade samples of 0.82 gm of LiNO3, 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V2Os are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -5 A mixture of AR grade samples of 0.75 gm of Li2O+Li2CO3, (0.37 gm + 0.38 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250 C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -6 A mixture of AR grade samples of 0.75 gm of Li20 + LiOH, (0.50 gm + 0.25 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V20s are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -7 A mixture of AR grade samples of 0.75 gm of Li20+ LiNOa, (0.50 gm + 0.25 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V20s are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. Example -8 A mixture of AR grade samples of 0.75 gm of Li2O+ Li2CO3+LiOH (0.30 gm + 0.30 gm + 0.15 gm) respectively of 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 95% Example -9 A mixture of AR grade samples of 0.75 gm of Li2O+ Li2CO3+LiNO3, (0.30 gm + 0.30 gm + 0,15 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 93% Example -10 A mixture of AR grade samples of Li2O+ Li2CO3+LiOH (0.30 gm + 0.30 gm + 0.15 gm) respectively of 0.75 gm of Li2CO3, 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get apaste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 95%. Example -11 A mixture of AR grade samples of 0.75 gm of Li2O+LiOH +LiNO3, (0.45 gm + 0.15 gm +0,15 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V20s are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 96% Example -12 A mixture of AR grade samples of 0.75 gm of Li2O+LiOH +LiNO3 +Li2CO3, (0.25 gm + 0.10 gm + 0.15 gm + 0.25 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 750°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 96% Example- 13 A mixture of AR grade samples of 0.75 gm of Li2O+LiOH +LiNO3 +Li2CO3, (0.30 gm + 0.10 gm + 0.10 gm + 0.25 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 800°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 96% Example-14 A mixture of AR grade samples of 0.75 gm of Li2O+LiOH +LiNO3 +Li2CO3, (0.25 gm +0.10 gm + 0.10 gm -4- 0.30 gm) respectively 0.75 gm of NiO, 0.81 gm of MgO and 1.82 gms of V205 are taken in a crucible and was ground well and three times the weight of the mixture, citric acid was added and then small quantities of glycerol was added and ground well the mixture so as to get a paste. The addition of glycerol helped to get an uniform consistency of the mixture. The mixture was initially heated to 250°C to evaporate of the glycerol and then was heated to 700°C for 12 hours to get the product which was brown in colour. The efficiency of the process was 96%. AR quality, NiO, V205, MgO, reacts with LiNO3 , Li2O, LiOH or LiNO3 or its mixtures at temperatures in between 650-800°C to form LiNio.5Mgo.sVO4 solid state composite.The flux should be (citric acid or glycine) three to four times the molar ratio of the reacting mixture. The hour heating is in the range of 10-14 hours.The product formed as the above condition is brown in colour with single phase purity and shows an efficiency of formation of >95 %. The main advantages of the present invention are 1 No side reactions occur due to the binding agent (glycerol). 2. Cheap fluxes like urea, citric acid or glycine can be used. 3 It is a single step heating process. 4. Li2O, LiOH , LiNO3, Li2CO3 can be used alone or of different combinations with NiO+MgO+ ViO5 mixture such that equimolar proportions have to be maintained so that the product LiNio..5Mgo 5VO4 is formed. 5. Purity of the product depends on the purity of the reactants. We Claim: 1. A process for preparation of lithium nickel magnesium vanadate (LiNio.5Mgo.5VO4) useful as cathode material which comprises : preparing a paste by mixing oxides of nickel, magnesium, vanadium and lithium compound as herein described in equimolar quantities with a flux selected from citric acid and glycine in glycerol to obtain paste, heating the so prepared paste upto 800° C for a period of 12 hours followed by cooling to get lithium nickel magnesium vanadate. 2. A process as claimed in claim 1, wherein NiO, MgO and VOs are used to make a paste with any one of the lithium compound selected either alone or as mixtures from Li2O or LiOH or LiNO3 or Li2CO3. 3. A process as claimed in claims 1-2, wherein glycerol is used as a binding agent. 4. A process as claimed in claims 1-3, wherein heating is effected in a furnace initially slowly at a temperature in between 150-250°C followed by heating upto 800°C. 5. A process as claimed in claims 1-4, wherein the product is formed by a single step chemical reaction. 6. A process for preparation of lithium nickel magnesium vanadate (LiNio.5Mgo.5VO4) useful as cathode material substantially as herein described with reference to the examples and drawing accompanying the specification.

Documents:

964-DEL-2002-Abstract-(07-07-2010).pdf

964-del-2002-abstract.pdf

964-DEL-2002-Claims-(07-07-2010).pdf

964-del-2002-claims.pdf

964-DEL-2002-Correspondence-Others-(07-07-2010).pdf

964-del-2002-correspondence-others.pdf

964-del-2002-correspondence-po.pdf

964-DEL-2002-Description (Complete)-(07-07-2010).pdf

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

964-del-2002-drawings.pdf

964-del-2002-form-1.pdf

964-del-2002-form-18.pdf

964-del-2002-form-2.pdf

964-DEL-2002-Form-3-(07-07-2010).pdf

964-del-2002-form-3.pdf